WO2022213911A1 - Soldering material, and preparation method therefor and use thereof - Google Patents

Soldering material, and preparation method therefor and use thereof Download PDF

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Publication number
WO2022213911A1
WO2022213911A1 PCT/CN2022/084952 CN2022084952W WO2022213911A1 WO 2022213911 A1 WO2022213911 A1 WO 2022213911A1 CN 2022084952 W CN2022084952 W CN 2022084952W WO 2022213911 A1 WO2022213911 A1 WO 2022213911A1
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Prior art keywords
solder
crystal grains
substrate
welding material
raw material
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PCT/CN2022/084952
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French (fr)
Chinese (zh)
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华菲
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宁波施捷电子有限公司
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Publication of WO2022213911A1 publication Critical patent/WO2022213911A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
    • B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
    • B23K35/24—Selection of soldering or welding materials proper
    • B23K35/26—Selection of soldering or welding materials proper with the principal constituent melting at less than 400 degrees C
    • B23K35/262—Sn as the principal constituent
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
    • B23K35/40—Making wire or rods for soldering or welding

Definitions

  • the embodiments of the present application relate to the field of materials, for example, a welding material and a preparation method and use thereof.
  • the grain size of the solder joint is close to the size of the nano-grain, (such as less than 1 ⁇ m, 200 nm, 50 nm, or even less than 30 nm), the solder joint material will have superplastic properties, and the solder joint is more likely to relax the locally accumulated stress. Therefore, if a nanograin structure can be imparted to the solder, the fatigue life of the solder joint can be improved.
  • Electron migration the movement of atoms when an electric current passes through a conductor, such as the interconnecting wires of a solder joint, was demonstrated more than 100 years ago.
  • EM Electron migration
  • Electromigration reduces the reliability of integrated circuit chips, especially chips assembled with lead-free solders such as Sn-Ag, Sn-Cu, Sn-Ag-cu, Sn-Sb, Bi-Sn, Sn-In type solder alloys .
  • the reliability assessment of solder joints can be examined by an electromigration test, usually by passing a high density current through the solder joint at a temperature of 100-180°C for 100-10,000 hours.
  • Lead-free solders such as Sn-Cu or Sn-Ag-Cu have higher electron migration resistance than conventional eutectic Pb-Sn solders because they generally have higher melting points than conventional eutectic Pb-Sn solders. It is very necessary to further reduce the failure rate of solder joints caused by electron migration by improving the microstructure of lead-free solder to reduce the failure rate of related equipment.
  • CN105935845A discloses a bismuth telluride nanoparticle reinforced tin-silver-copper solder and a method for using the same.
  • the solder provided by the method comprises 0.5-1% of bismuth telluride nanoparticles, 80-90% of tin-silver-copper micron powder and Flux 10 to 20%.
  • the average particle size of the bismuth telluride nanoparticles is 20 nm, and the atomic ratio of tellurium to bismuth is 3:2.
  • the average particle size of the tin-silver-copper micro-powder is 30 ⁇ m tin element, and the weight percentage of silver element and copper element is 96.5%: 3.0%: 0.5%.
  • the flux is rosin flux.
  • CN103639614A discloses a nano-scale/micron-scale particle hybrid lead-free solder paste with size effect and a preparation method thereof, comprising the following steps: slowly adding nano-scale solder into the flux paste/agent, and after mechanical stirring, Introduce ultrasonic vibration, continue stirring, then stop ultrasonic vibration, slowly add micron-sized solder/paste, and continue stirring to obtain a uniform mixed solder paste.
  • the embodiments of the present application provide a welding material and a preparation method and application thereof.
  • the welding materials provided by the embodiments of the present application have superplasticity, extremely high anti-fatigue fracture and anti-electron migration, high reliability, and long service life.
  • an embodiment of the present application provides a soldering material, the soldering material is composed of crystal grains, the grain size of the crystal grains is less than 1 ⁇ m and/or the phase difference between adjacent crystal grains in the soldering material less than 10°.
  • the solder is mainly composed of small-sized crystal grains, and the crystal grain size of the crystal grains is less than 1 ⁇ m, for example, the crystal grain size is 0.9 ⁇ m, 0.8 ⁇ m, 0.7 ⁇ m, 0.6 ⁇ m, 0.5 ⁇ m, 0.4 ⁇ m, 0.3 ⁇ m, 0.2 ⁇ m, 0.1 ⁇ m, 75nm, 50nm, 40nm, 30nm or 25nm etc.
  • the grains in the solder provided by the present application have such a nanometer size, so that the solder exhibits superplasticity and high mechanical elongation, and the solder joint is more likely to release local accumulated stress.
  • small grains increase the diffusion of atoms at the grain boundaries, thereby increasing the probability of electron drift failure.
  • small-angle grain boundaries can reduce the grain boundary diffusion rate.
  • high melting point raw materials can also reduce the risk of solder joint failure caused by solder electromigration.
  • the phase difference between adjacent die in the solder provided by the present application is less than 10°, such as 9°, 8°, 7°, 6°, 5°, 4°, 3°, 2° or 1°, etc.
  • the solder joint materials provided by this application have small-angle grain boundaries because: (1) the grain boundary energy of the small-angle grain boundaries is small, and when the temperature increases, the diffusion of atoms is weakened, and the overall structure is in a relatively stable state; (2) The atoms at the grain boundary are irregularly arranged, and the existence of the grain boundary will hinder the movement of dislocations at room temperature, resulting in an increase in the resistance to plastic deformation.
  • the finer grain strengthening The higher the strength of the material, the finer grain strengthening; (3) the atoms at the grain boundary deviate from the equilibrium position and have higher kinetic energy, and there are more defects such as holes, impurity atoms and dislocations at the grain boundary. , so the diffusion rate of atoms at the grain boundary is much faster than that in the grain, and the small-angle grain boundary can slow down the diffusion rate; (4) the strength of the grain boundary is higher than that of the grain at low temperature, and the strength of the grain boundary is lower than that of the grain at high temperature. Shown as low temperature weakening.
  • the solder provided by the present application has excellent properties of resistance to electron migration and fatigue resistance.
  • the size of the crystal grains is less than 1 ⁇ m.
  • the size of the crystal grains is less than 50 nm.
  • the size of the crystal grains is less than 30 nm.
  • the grains are alloys and/or intermetallics.
  • Sn is included in the alloy.
  • the alloy further includes any one or a combination of at least two of Ag, Cu, Sb, In or Bi.
  • Typical but non-limiting types of alloys are Sn-Ag, Sn-Cu, Sn-Sb, Sn-In, Bi-Sn, Sn-Ag-Cu, Sn-Ag-Cu or Sn-Ag-In.
  • the proportion of Sn is ⁇ 30wt%, such as 30wt%, 35wt%, 40wt%, 45wt%, 50wt% , 55wt%, 60wt%, 65wt%, 70wt%, 75wt%, 80wt% or 85wt%, etc.
  • the proportion of Ag is 0.5-5wt%, for example, 0.5wt%, 1wt%, 2wt%, 3wt%, based on the total mass of the crystal grains in the solder material being 100% , 4wt% or 5wt%, etc.
  • the proportion of Cu is 0.2-2 wt %, for example, 0.2 wt %, 0.5 wt %, 1 wt %, 1.5 wt %, based on the total mass of the crystal grains in the welding material being 100 %. wt% or 2wt%, etc.
  • the proportion of Sb is 0.5-5wt%, such as 0.5wt%, 1wt%, 2wt%, 3wt%, based on the total mass of the crystal grains in the welding material being 100%. , 4wt% or 5wt%, etc.
  • the proportion of In is 0.5-5wt%, for example, 0.5wt%, 1wt%, 2wt%, 3wt%, based on the total mass of the crystal grains in the welding material being 100%. , 4wt% or 5wt%, etc.
  • the proportion of Bi is 0.5-5wt%, for example, 0.5wt%, 1wt%, 2wt%, 3wt%, based on the total mass of the crystal grains in the welding material being 100%. , 4wt% or 5wt%, etc.
  • the intermetallic compound includes any one or a combination of at least two of Cu 6 Sn 5 , Cu 3 Sn, Cu 7 In 3 , Sn 3 Sb 2 or SnSb.
  • an embodiment of the present application provides a method for preparing and welding the welding material as described in the first aspect, the method comprising the following steps:
  • step (2) Coat the solder paste of step (1) on the first substrate, place the second substrate on the solder paste, and perform reflow sintering to obtain the solder material and realize the bonding between the first substrate and the second substrate.
  • the sintering temperature is below the melting point temperature of the nano-solder raw material.
  • step (2) the solder paste is heated and sintered rapidly to below the melting point of the solder joint, so as to maintain the size of the nanocrystalline grains without causing extensive enlargement of the grains.
  • the interface is sintered without melting the solder itself.
  • the solder obtained by the preparation method has superplasticity and fatigue resistance.
  • the size of the nano-solder raw material in step (1) is less than 500 nm, such as 490 nm, 450 nm, 400 nm, 300 nm, 200 nm, 100 nm, 50 nm, 30 nm or 20 nm, etc., preferably less than 100 nm, more preferably less than 50 nm, more preferably less than 30 nm.
  • the preparation method of the nano-solder raw material in step (1) includes spark erosion, chemical synthesis or physical vapor deposition, preferably spark erosion.
  • spark erosion is one of the common and preferred methods for preparing solder alloy nanoparticles because of the ease and cost-effectiveness of large-scale manufacturing.
  • the EDM unit is shaped like a "gate" and contains two electrodes and charged particles composed of an associated solder alloy, placed on a mesh screen, and immersed in a non-electrolyte solution (a solution that does not conduct electricity). The electrodes are connected to a pulsed power source.
  • the spark erosion unit is housed in a double-walled vacuum-jacketed glass vessel containing a non-electrolyte solution, preferably liquid nitrogen, to prevent oxidation of the nanoparticles.
  • Two alloyed electrodes were installed in the unit and connected to a pulsed power source. Charge particles of the same solder alloy (eg, 1 to 3 cm in diameter) are filled into the perforated holder to make contact with the electrodes. Vibrate the glass container to make contact and disconnection between the electrodes and the charged particles. Therefore, the electrical contact between the electrodes is random, and each spark leads to the formation of nanoparticles.
  • a pulsed power supply is a energized capacitor.
  • the capacitor discharges, creating sparks (microplasma) between the associated components.
  • This plasma of electrons and positive ions is very hot, about 10,000K.
  • the energy of the faster electrons and slower ions is deposited in the localized area where the spark occurs, overheating them to the point of boiling.
  • the spark collapses the vaporized alloy and droplets are violently ejected from the boiling region and pass through the plasma region into the medium liquid, where they are rapidly cooled and quenched.
  • the vaporized part of the metal or alloy is an important part of the synthesis of "nano" particles because the vapor nucleates densely and freezes into extremely small nanoparticles.
  • Molten metal or alloy droplets are quenched into micron-sized particles, which are easily filtered because of their small size. Because the quench rate is very rapid, even micron-sized particles can have very small grain sizes. In-situ quenching of droplets or condensed vapors tends to produce spherical particles with sub-nanograin structure. These particles descend through a mesh screen to the bottom of the EDM unit, where they are collected and processed.
  • the preparation method of the nano-solder raw material in step (1) includes spark erosion, chemical synthesis or physical vapor deposition.
  • the flux in step (1) includes no-clean flux and/or water-wash flux.
  • the solvent in step (1) includes any one or a combination of at least two of ethanol, propanol, butanol, acetone, toluene isobutyl ketone, ethyl acetate, butyl acetate or inorganic ion solutions.
  • step (1) further comprises: adding additives to the solder paste.
  • the additives include synthetic resin surfactants, organic acid activators, corrosion inhibitors, cosolvents, film formers, wetting agents, adhesives, thixotropic agents, thickeners, matting agents, brighteners or Any one or a combination of at least two of the flame retardants.
  • the addition ratios of nano-solder raw materials, fluxes, solvents and additives can be adjusted as required, which are not limited here.
  • the method of applying the solder paste of step (1) on the first substrate in step (2) includes screen printing, ink nozzle printing or pattern transfer printing using an imprint mold.
  • the first substrate and the second substrate in step (2) are both electronic devices.
  • the method for placing the second substrate on the solder paste in step (2) is a flip-chip mounting method.
  • the sintering time in step (2) is 30-90 seconds, such as 30 seconds, 40 seconds, 50 seconds, 60 seconds, 70 seconds, 80 seconds or 90 seconds, etc.
  • the sintering time is too long, the grain size will be too large, which is not conducive to the formation of small-angle grain boundaries.
  • the method further includes: in step (1), mixing the dispersant, the nano-solder raw material, the flux and the solvent together to obtain a solder paste.
  • the prepared dispersant-induced nanoparticle solder has the microstructure of ultrafine grains or nanoscale solder (such as grain size ⁇ 1 ⁇ m, preferably ⁇ 0.2 ⁇ m, more preferably ⁇ 50nm average particle size), which is different from coarse grained solder ( Compared with >5 ⁇ m grain size), it exhibits superplasticity and conforms to mechanical elongation in tensile test, which is increased by at least 50%.
  • nanoscale solders exhibit at least a 2-fold improvement in fatigue life or electron migration resistance (eg >5 ⁇ m particle size).
  • the dispersing agent comprises oxides, nitrides, oxynitrides, fluorides or carbides, and the dispersing agent contains any one of Ti, Zr, Al, Si, Fe, Cr or Ge .
  • the dispersants in this method are insoluble nanoparticles, TiO 2 , ZrO 2 , Al 2 O 3 , SiO 2 , Fe 2 O 3 , Cr 2 O 3 , SiO 2 , GeO 2 or other oxides, nitrides, oxynitrides 2-10nm diameter nanoparticles of sulfide, fluoride or carbide, insoluble nanoparticles (such as Al, Cr, Ge, Si) are intentionally added and uniformly distributed in the solder matrix.
  • the size of the dispersant is 2-10 nm, such as 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm or 10 nm, and the like.
  • an embodiment of the present application provides another method for preparing a welding material as described in the first aspect, the method comprising the following steps:
  • the solder raw material is subjected to a heating-cooling cycle to obtain the solder material.
  • This method is another new method for preparing nanoparticle solder joints, which is realized by phase-change thermal cycle (solid to liquid or solid to solid), repeated many times, and gradually refines the grains.
  • This ultra-fine or nano-sized grain structure is beneficial for realizing superplastic and mechanical failure-resistant joints with fatigue and electron migration resistance.
  • the solder texture obtained by this method eg grain size ⁇ 5 ⁇ m, preferably ⁇ 1 ⁇ m, more preferably ⁇ 0.2 ⁇ m, even preferably ⁇ 50 nm average grain size), compared to coarse-grained solders (eg > 5 ⁇ m grain size), Exhibits superplasticity in tensile tests and is consistent with at least a 50% increase in mechanical elongation.
  • the nanoscale solder exhibits at least a 2-fold improvement in fatigue life or electron migration resistance compared to a solder of the same composition with a coarse grain structure.
  • Nano-solder can also be realized by heating-cooling cyclic solid phase transition, so that the phase difference between adjacent grains is less than 10° while realizing ultra-fine grains.
  • the number of cycles of the heating-cooling cycle is 1-20 times, such as 1 time, 2 times, 3 times, 4 times, 5 times, 6 times, 7 times, 8 times, 9 times , 10 times, 11 times, 12 times, 13 times, 14 times, 15 times, 16 times, 17 times, 18 times, 19 times or 20 times, etc.
  • the solder stock is placed between the substrate and the flip-chip type device to be packaged to form a solid solder joint prior to the heating-cooling cycle.
  • the heating-cooling cycle causes the welding material to undergo a solid-state phase transition.
  • the solder material eg, tin material
  • the solder material undergoes a solid-state phase transition, and the solder material is obtained after several cycles.
  • the embodiments of the present application provide another method for preparing a welding material according to the first aspect, the method comprising the following steps:
  • the solder material is obtained by subjecting the solder raw material to a tension-compression cycle.
  • Nano-grained solders prepared by this method eg, grain size ⁇ 1 ⁇ m, preferably ⁇ 0.2 ⁇ m, more preferably ⁇ 50 nm average grain size
  • coarse-grained solders eg >5 ⁇ m grain size
  • the nano-grained solder also has anti-fatigue properties and anti-electromigration properties, compared with the same composition solder with a coarse grain structure, the anti-fatigue life or anti-electromigration life is increased by at least 2 times (eg >5 ⁇ m grain size) .
  • the preparation method achieves that the phase difference between adjacent crystal grains is less than 10° through the stretching-compression cycle.
  • the stretching includes thermal stretching, mechanical stretching or vibration stretching;
  • the solder stock is placed between the substrate and the flip-chip type device to be packaged to form a solid solder joint prior to performing the stretch-compression cycle.
  • the thermal expansion and contraction coefficients of the chip and the base material may be different so that the solder raw material is thermally stretched when the temperature changes.
  • embodiments of the present application provide the use of the solder material according to the first aspect for interconnection and packaging applications in electronics, computers, communications, transportation, aerospace applications, military applications or consumer applications .
  • the welding materials provided in the embodiments of the present application have small grains and small-angle grain boundaries, which significantly improve the mechanical elongation, fatigue life and electron migration resistance of the welding materials.
  • FIG. 1 is a schematic diagram of an apparatus for preparing nano-solder raw materials in Example 1 of the application.
  • FIG. 2 is a schematic diagram of the action principle of the dispersant in the process of preparing the nano-solder in Example 1 of the application.
  • This embodiment provides a solder, the solder is mainly composed of crystal grains, the crystal grains are Sn-Ag-Cu alloy, the grain size range is 20-30 nm, and the phase difference between adjacent crystal grains is 2° -7°. Based on the total mass of Sn-Ag-Cu alloy grains in the solder, the mass fraction of Sn in the grains is 94wt%, the mass fraction of Ag is 5wt%, and the mass fraction of Cu is 1wt%.
  • the solder also contains a mass fraction of 0.1-0.25% wt % SiO 2 dispersant (based on the total mass of Sn-Ag-Cu alloy grains in the solder as 100%, the size of the dispersant is 2-10 nm).
  • This embodiment also provides a method for preparing the solder, the specific method of which is:
  • step (2) Coat the solder paste described in step (1) on the surface of the first substrate (substrate device) by screen printing, and then place the second substrate (another chip device) on the surface of the first substrate (another chip device) by flip-chip mounting Paste on the first substrate for electronic package assembly.
  • the solder is then reflowed and sintered by heating to 200°C.
  • the preparation method of the nano-solder raw material Sn-Ag-Cu alloy nanoparticles in step (1) is shown in Figure 1.
  • the solder charge particles (diameter 1-3cm) composed of solder and gold are placed on a mesh screen, and the mesh screen is placed.
  • a non-electrolyte solution liquid nitrogen
  • two electrolyzers were placed on the mesh screen and connected to a pulsed power source. Vibrate the glass container to make contact and disconnection between the electrodes and the charged particles. Therefore, the electrical contact between the electrodes is random, and each spark leads to the formation of nanoparticles.
  • a pulsed power supply is a energized capacitor.
  • the capacitor discharges, creating sparks (microplasma) between the associated components.
  • This plasma of electrons and positive ions is very hot, about 10,000K.
  • the energy of the faster electrons and slower ions is deposited in the localized area where the spark occurs, overheating them to the point of boiling.
  • the spark collapses the vaporized alloy and droplets are violently ejected from the boiling region and pass through the plasma region into the medium liquid, where they are rapidly cooled and quenched, resulting in the nanosolder feedstock.
  • the role of the dispersant SiO 2 in step (1) is shown in Figure 2.
  • the small-sized dispersant has the best growth inhibition property, and after sintering, the Sn-Ag-Cu alloy grains can have a nano-grain structure, A dense solder is obtained.
  • This embodiment provides a solder, the solder is mainly composed of crystal grains, the crystal grains are Sn-Ag-In alloys, the grain size range is 40-50 nm, and the phase difference between adjacent crystal grains is 4° . Based on the total mass of Sn-Ag-In alloy grains in the solder, the mass fraction of Sn in the grains is 94.5wt%, the mass fraction of Ag is 0.5wt%, and the mass fraction of In is 5wt%.
  • the solder also contains a TiO 2 dispersant with a mass fraction of 0.1 wt % (the size of the dispersant is 2-10 nm based on the total mass of Sn-Ag-In alloy grains in the solder as 100%).
  • This embodiment also provides a method for preparing the solder, the specific method of which is:
  • nano-solder raw material Sn-Ag-In alloy nanoparticles particle size is 40-50nm
  • no-clean flux solvent butanol
  • dispersant TiO 2 are mixed in a mass ratio of 2:1:3:0.2, get solder paste
  • step (2) The solder paste described in step (1) is coated on the surface of the first substrate (substrate device) by the ink nozzle printing method, and then the second substrate (another chip device) is placed on the surface of the first substrate (another chip device) by flip-chip mounting. Paste on the first substrate for electronic package assembly. The solder was then obtained by heating to 150° C. for reflow sintering for 30 seconds.
  • the preparation method of Sn-Ag-In alloy nanoparticles refers to Embodiment 1.
  • This embodiment provides a solder, the solder is mainly composed of crystal grains, the crystal grains are Sn-Cu alloy, the grain size range is 80-120 nm, and the phase difference between adjacent crystal grains is 5°. Based on the total mass of Sn-Cu alloy grains in the solder, the mass fraction of Sn in the grains is 98 wt %, and the mass fraction of Cu is 2 wt %.
  • This embodiment also provides a method for preparing the solder, the specific method of which is:
  • nano-solder raw material Sn-Cu alloy nanoparticles (particle size is 60-120nm), water-washing flux, solvent
  • Acetone is mixed in a mass ratio of 4:1:3 to obtain solder paste
  • step (2) Coat the solder paste described in step (1) on the surface of the first substrate (substrate device) by screen printing, and then place the second substrate (another chip device) on the surface of the first substrate (another chip device) by flip-chip mounting Paste on the first substrate for electronic package assembly.
  • the solder was then obtained by heating to 200°C for 90 seconds and sintering.
  • the preparation method of Sn-Cu alloy nanoparticles refers to Embodiment 1.
  • This embodiment provides a solder, the solder is mainly composed of crystal grains, the crystal grains are Sn-Sb alloys, the grain size ranges from 170 to 190 nm, and the phase difference between adjacent crystal grains is 7°. Based on the total mass of Sn-Sb alloy crystal grains in the solder, the mass fraction of Sn in the crystal grains is 95 wt %, and the mass fraction of Sb is 5 wt %.
  • This embodiment also provides a method for preparing the solder, the specific method of which is:
  • the solder was obtained by heating-cooling a macroscopic Sn-Sb alloy (about 0.5 cm 3 in volume) placed between the substrate and the flip-chip device to be packaged to form a solid solder joint for 15 times.
  • Each of the heating-cooling cycles consisted of heating at 200°C for 15 minutes and cooling at 10°C for 15 minutes.
  • Each heating-cooling cycle causes the Sn-Sb alloy to undergo a solid-state phase transition, which induces nanograins.
  • This embodiment provides a solder, the solder is mainly composed of crystal grains, the crystal grains are intermetallic compound Cu 3 Sn, the grain size range is 180-205 nm, and the phase difference between adjacent crystal grains is 5° .
  • This embodiment also provides a method for preparing the solder, the specific method of which is:
  • the solder of this comparative example is Sn-Cu alloy, the grain size range is about 5 ⁇ m, and the phase difference between adjacent grains is 9°. Based on the total mass of Sn-Cu alloy grains in the solder, the mass fraction of Sn in the grains is 98 wt%, and the mass fraction of Cu is 2 wt% (the proportion of constituent elements is the same as that of the solder in Example 3).
  • the solder of this comparative example is Sn-Cu alloy, the grain size range is about 1 ⁇ m, and the phase difference between adjacent grains is 26°. Based on the total mass of Sn-Cu alloy grains in the solder, the mass fraction of Sn in the grains is 98 wt%, and the mass fraction of Cu is 2 wt% (the proportion of constituent elements is the same as that of the solder in Example 3).
  • solders provided in Examples 1-5 have small grains and small-angle grain boundaries, so that the mechanical elongation, fatigue resistance and electron migration resistance of the solders are significantly improved.
  • the present application illustrates the detailed method of the present application through the above-mentioned embodiments, but the present application is not limited to the above-mentioned detailed method, which does not mean that the present application must rely on the above-mentioned detailed method for implementation.
  • Those skilled in the art should understand that any improvement to the application, the equivalent replacement of each raw material of the product of the application, the addition of auxiliary components, the selection of specific methods, etc., all fall within the scope of protection and disclosure of the application.

Abstract

A soldering material, and a preparation method therefor and a use thereof. The soldering material has micro grains or a small-angle grain boundary microstructure; the grain size of the grains is generally less than 1 µm; and the small-angle grain boundary phase difference in the soldering material is generally less than 10. The method comprises: (1) mixing a nano-solder raw material with a soldering flux and a solvent to obtain a soldering paste; and (2) coating the soldering paste obtained in step (1) on a first substrate, and placing a second substrate on the soldering paste for sintering to obtain the soldering material, a soldering reflow temperature being below the melting point temperature of the nano-solder raw material.

Description

一种焊接材料及其制备方法和用途A kind of welding material and its preparation method and use 技术领域technical field
本申请实施例涉及材料领域，例如一种焊接材料及其制备方法和用途。The embodiments of the present application relate to the field of materials, for example, a welding material and a preparation method and use thereof.
背景技术Background technique
众所周知，现代电子设备需要为包括计算机中央处理器(CPU)在内的应用进行包装和组装。目前封装的趋势是不断小型化，缩小尺寸使得电子芯片和器件的电流密度增加到更高的水平，即从10 5到10 6A/cm 2。但当器件电流密度增加时，由于电流通过导致的电阻热也会增加，进而使器件和互连/封装结构处于更恶劣的使用条件下(在器件开和关时，温度差增大)，芯片和基底热膨胀系数(CTE)的不匹配性也随之增加，焊点所遇到的应力(包括CTE不匹配引起的或热循环引起的疲劳问题)要求焊点材料具有更强的柔韧性以适应这种应力。当焊点的晶粒尺寸接近纳米晶粒的尺寸时，(如小于1μm、200nm、50nm，甚至小于30nm)，焊点材料会有超塑性性能，焊点更容易放松局部积累的应力。因此，如果能赋予焊料纳米晶粒结构，焊点的疲劳寿命可以得到改善。 It is well known that modern electronic devices require packaging and assembly for applications including computer central processing units (CPUs). The current trend in packaging is to continue to miniaturize, and the shrinking size allows the current density of electronic chips and devices to increase to higher levels, ie from 10 5 to 10 6 A/cm 2 . But when the device current density increases, the resistive heating due to the passing of the current also increases, which in turn puts the device and interconnect/package structure in harsher service conditions (the temperature difference increases when the device is turned on and off), and the chip The mismatch in the coefficient of thermal expansion (CTE) of the substrate also increases, and the stresses encountered by the solder joint (including fatigue problems caused by CTE mismatch or thermal cycling) require the solder joint material to be more flexible to accommodate this stress. When the grain size of the solder joint is close to the size of the nano-grain, (such as less than 1 μm, 200 nm, 50 nm, or even less than 30 nm), the solder joint material will have superplastic properties, and the solder joint is more likely to relax the locally accumulated stress. Therefore, if a nanograin structure can be imparted to the solder, the fatigue life of the solder joint can be improved.
在先进的高密度电子电路中，高电流密度(如10 6A/cm 2)也会引起更明显的电子迁移和热迁移问题，最终导致焊点失效。电子迁移(EM)是电流通过导体(如焊点的互连线)时原子的运动，已在100多年前被证实。当电流引起原子向焊点阳极一侧迁移时，焊点材料阴极一侧出现晶格空隙，晶格空隙不断累积形成空洞，通常类似于薄烤饼状。这种空洞缺陷不断增长最终会导致焊点失效。电迁移降低了集成电路芯片的可靠性，特别是常用无铅焊料组装的芯片，如Sn-Ag、Sn-Cu、Sn-Ag-cu、Sn-Sb、Bi-Sn、Sn-In型焊料合金。在这样一个背景下，焊点的可靠性评估可以由一个电子迁移测试来检测，通常是使高密度电流在100-180℃的温度下通过焊点，时间持续100-10000小时。无铅焊料如Sn-Cu或Sn-Ag-Cu电子迁移阻力高于传统的共晶Pb-Sn焊料，因为它们通常比传统的共晶Pb-Sn焊料具有更高的熔点。通过改进无铅焊料的微观结构以进一步减少电子迁移所引起的焊点失效率，以降低相关设备故障率是非常必要的。 In advanced high-density electronic circuits, high current densities (eg, 10 6 A/cm 2 ) also cause more pronounced electromigration and thermal migration problems, ultimately leading to solder joint failure. Electron migration (EM), the movement of atoms when an electric current passes through a conductor, such as the interconnecting wires of a solder joint, was demonstrated more than 100 years ago. When the current causes atoms to migrate toward the anode side of the solder joint, lattice voids appear on the cathode side of the solder joint material, and the lattice voids accumulate to form voids, often resembling a pancake. This growing void defect will eventually lead to solder joint failure. Electromigration reduces the reliability of integrated circuit chips, especially chips assembled with lead-free solders such as Sn-Ag, Sn-Cu, Sn-Ag-cu, Sn-Sb, Bi-Sn, Sn-In type solder alloys . In such a context, the reliability assessment of solder joints can be examined by an electromigration test, usually by passing a high density current through the solder joint at a temperature of 100-180°C for 100-10,000 hours. Lead-free solders such as Sn-Cu or Sn-Ag-Cu have higher electron migration resistance than conventional eutectic Pb-Sn solders because they generally have higher melting points than conventional eutectic Pb-Sn solders. It is very necessary to further reduce the failure rate of solder joints caused by electron migration by improving the microstructure of lead-free solder to reduce the failure rate of related equipment.
CN105935845A公开了一种碲化铋纳米颗粒强化锡银铜焊料及其使用方法，该方法提供的焊料按重量百分比计包含碲化铋纳米颗粒0.5～1％、锡银铜微米粉 末80～90％以及助焊剂10～20％。碲化铋纳米颗粒的平均粒径为20nm，碲元素与铋元素的原子比为3:2。锡银铜微米粉末的平均粒径为30μm锡元素、银元素与铜元素的重量百分比为96.5％：3.0％：0.5％。助焊剂为松香助焊剂。CN105935845A discloses a bismuth telluride nanoparticle reinforced tin-silver-copper solder and a method for using the same. The solder provided by the method comprises 0.5-1% of bismuth telluride nanoparticles, 80-90% of tin-silver-copper micron powder and Flux 10 to 20%. The average particle size of the bismuth telluride nanoparticles is 20 nm, and the atomic ratio of tellurium to bismuth is 3:2. The average particle size of the tin-silver-copper micro-powder is 30 μm tin element, and the weight percentage of silver element and copper element is 96.5%: 3.0%: 0.5%. The flux is rosin flux.
CN103639614A公开了一种具备尺寸效应的纳米级/微米级颗粒混合型无铅焊料膏及其制备方法，包括以下几个步骤：将纳米级焊料缓慢的加入助焊膏/剂中，机械搅拌后在引入超声振荡，继续搅拌，然后停止超声振荡，缓慢加入微米级焊料/膏，继续搅拌得到混合均匀的混合型焊料膏。CN103639614A discloses a nano-scale/micron-scale particle hybrid lead-free solder paste with size effect and a preparation method thereof, comprising the following steps: slowly adding nano-scale solder into the flux paste/agent, and after mechanical stirring, Introduce ultrasonic vibration, continue stirring, then stop ultrasonic vibration, slowly add micron-sized solder/paste, and continue stirring to obtain a uniform mixed solder paste.
但是上述方案均存在焊料产品的抗电子迁移和抗疲劳性能仍有待加强。However, the above solutions all have the anti-electron migration and anti-fatigue properties of solder products still to be strengthened.
发明内容SUMMARY OF THE INVENTION
以下是对本文详细描述的主题的概述。本概述并非是为了限制权利要求的保护范围。The following is an overview of the topics detailed in this article. This summary is not intended to limit the scope of protection of the claims.
本申请实施例提供一种焊接材料及其制备方法和用途。本申请实施例提供的焊接材料具有超塑性，以及极高的抗疲劳断裂和抗电子迁移高可靠性，超长寿命。The embodiments of the present application provide a welding material and a preparation method and application thereof. The welding materials provided by the embodiments of the present application have superplasticity, extremely high anti-fatigue fracture and anti-electron migration, high reliability, and long service life.
第一方面，本申请实施例提供一种焊接材料，所述焊接材料由晶粒组成，所述晶粒的晶粒尺寸小于1μm和/或所述焊接材料中相邻晶粒之间的位相差小于10°。In a first aspect, an embodiment of the present application provides a soldering material, the soldering material is composed of crystal grains, the grain size of the crystal grains is less than 1 μm and/or the phase difference between adjacent crystal grains in the soldering material less than 10°.
本申请中，所述焊料主要由小尺寸的晶粒组成，所述晶粒的晶粒尺寸小于1μm，例如晶粒尺寸为0.9μm、0.8μm、0.7μm、0.6μm、0.5μm、0.4μm、0.3μm、0.2μm、0.1μm、75nm、50nm、40nm、30nm或25nm等。本申请提供的焊料中的晶粒具有这种纳米尺寸，使得焊料表现出超塑性和高机械延伸率，焊点更容易释放局部累积应力。通常小晶粒会增加原子在晶界的扩散，从而增加电子漂移失效的可能性。但是小角度晶界可以降低晶界扩散速度。另外，高熔点原材料也可以降低由焊锡电迁移引起的焊点失效风险。In this application, the solder is mainly composed of small-sized crystal grains, and the crystal grain size of the crystal grains is less than 1 μm, for example, the crystal grain size is 0.9 μm, 0.8 μm, 0.7 μm, 0.6 μm, 0.5 μm, 0.4 μm, 0.3μm, 0.2μm, 0.1μm, 75nm, 50nm, 40nm, 30nm or 25nm etc. The grains in the solder provided by the present application have such a nanometer size, so that the solder exhibits superplasticity and high mechanical elongation, and the solder joint is more likely to release local accumulated stress. Usually small grains increase the diffusion of atoms at the grain boundaries, thereby increasing the probability of electron drift failure. However, small-angle grain boundaries can reduce the grain boundary diffusion rate. In addition, high melting point raw materials can also reduce the risk of solder joint failure caused by solder electromigration.
本申请提供的焊料中相邻晶粒之间的位相差小于10°，例如9°、8°、7°、6°、5°、4°、3°、2°或1°等。本申请提供的焊点材料具有小角度晶界，这因为：(1)小角度晶界的晶界能小，温度升高时，原子的扩散被削弱，整体结构处于相对稳定状态；(2)晶界处原子排列不规则，在常温下晶界的存在会对位错的运动起阻碍作用，致使塑性变形抗力提高，宏观表现为晶界较晶内具有较 高的强度和硬度；晶粒越细，材料的强度越高，即是细晶强化；(3)晶界处原子偏离平衡位置,具有较高的动能,并且晶界处存在较多的缺陷如空穴、杂质原子和位错等,故晶界处原子的扩散速度比在晶内快得多，小角度晶界可以减缓扩散速度；(4)低温下晶界强度比晶粒内高，高温下晶界强度比晶内低，表现为低温弱化。使得本申请提供的焊料具有耐电子迁移、抗疲劳优良特性。The phase difference between adjacent die in the solder provided by the present application is less than 10°, such as 9°, 8°, 7°, 6°, 5°, 4°, 3°, 2° or 1°, etc. The solder joint materials provided by this application have small-angle grain boundaries because: (1) the grain boundary energy of the small-angle grain boundaries is small, and when the temperature increases, the diffusion of atoms is weakened, and the overall structure is in a relatively stable state; (2) The atoms at the grain boundary are irregularly arranged, and the existence of the grain boundary will hinder the movement of dislocations at room temperature, resulting in an increase in the resistance to plastic deformation. The higher the strength of the material, the finer grain strengthening; (3) the atoms at the grain boundary deviate from the equilibrium position and have higher kinetic energy, and there are more defects such as holes, impurity atoms and dislocations at the grain boundary. , so the diffusion rate of atoms at the grain boundary is much faster than that in the grain, and the small-angle grain boundary can slow down the diffusion rate; (4) the strength of the grain boundary is higher than that of the grain at low temperature, and the strength of the grain boundary is lower than that of the grain at high temperature. Shown as low temperature weakening. The solder provided by the present application has excellent properties of resistance to electron migration and fatigue resistance.
以下作为本申请优选的技术方案，但不作为对本申请提供的技术方案的限制，通过以下优选的技术方案，可以更好的达到和实现本申请的技术目的和有益效果。The following are the preferred technical solutions of the present application, but are not intended to limit the technical solutions provided by the present application. The technical purposes and beneficial effects of the present application can be better achieved and realized through the following preferred technical solutions.
作为本申请优选的技术方案，所述晶粒的尺寸小于1μm。As a preferred technical solution of the present application, the size of the crystal grains is less than 1 μm.
优选地，所述晶粒的尺寸小于50nm。Preferably, the size of the crystal grains is less than 50 nm.
优选地，所述晶粒的尺寸小于30nm。Preferably, the size of the crystal grains is less than 30 nm.
优选地，所述晶粒为合金和/或金属间化合物。Preferably, the grains are alloys and/or intermetallics.
优选地，所述合金中包括Sn。Preferably, Sn is included in the alloy.
优选地，所述合金中还包括Ag、Cu、Sb、In或Bi中的任意一种或至少两种的组合。Preferably, the alloy further includes any one or a combination of at least two of Ag, Cu, Sb, In or Bi.
典型但是非限制性的合金种类有：Sn-Ag、Sn-Cu、Sn-Sb、Sn-In、Bi-Sn、Sn-Ag-Cu、Sn-Ag-Cu或Sn-Ag-In等。Typical but non-limiting types of alloys are Sn-Ag, Sn-Cu, Sn-Sb, Sn-In, Bi-Sn, Sn-Ag-Cu, Sn-Ag-Cu or Sn-Ag-In.
优选地，当所述晶粒中存在Sn时，以焊接材料中晶粒的总质量为100％计，Sn的占比≥30wt％，例如30wt％、35wt％、40wt％、45wt％、50wt％、55wt％、60wt％、65wt％、70wt％、75wt％、80wt％或85wt％等。Preferably, when Sn exists in the crystal grains, based on the total mass of the crystal grains in the welding material being 100%, the proportion of Sn is ≥30wt%, such as 30wt%, 35wt%, 40wt%, 45wt%, 50wt% , 55wt%, 60wt%, 65wt%, 70wt%, 75wt%, 80wt% or 85wt%, etc.
优选地，当所述晶粒中存在Ag时，以焊接材料中晶粒的总质量为100％计，Ag的占比为0.5-5wt％，例如0.5wt％、1wt％、2wt％、3wt％、4wt％或5wt％等。Preferably, when Ag exists in the crystal grains, the proportion of Ag is 0.5-5wt%, for example, 0.5wt%, 1wt%, 2wt%, 3wt%, based on the total mass of the crystal grains in the solder material being 100% , 4wt% or 5wt%, etc.
优选地，当所述晶粒中存在Cu时，以焊接材料中晶粒的总质量为100％计，Cu的占比为0.2-2wt％，例如0.2wt％、0.5wt％、1wt％、1.5wt％或2wt％等。Preferably, when Cu is present in the crystal grains, the proportion of Cu is 0.2-2 wt %, for example, 0.2 wt %, 0.5 wt %, 1 wt %, 1.5 wt %, based on the total mass of the crystal grains in the welding material being 100 %. wt% or 2wt%, etc.
优选地，当所述晶粒中存在Sb时，以焊接材料中晶粒的总质量为100％计，Sb的占比为0.5-5wt％，例如0.5wt％、1wt％、2wt％、3wt％、4wt％或5wt％等。Preferably, when Sb exists in the crystal grains, the proportion of Sb is 0.5-5wt%, such as 0.5wt%, 1wt%, 2wt%, 3wt%, based on the total mass of the crystal grains in the welding material being 100%. , 4wt% or 5wt%, etc.
优选地，当所述晶粒中存在In时，以焊接材料中晶粒的总质量为100％计，In的占比为0.5-5wt％，例如0.5wt％、1wt％、2wt％、3wt％、4wt％或5wt％ 等。Preferably, when In exists in the crystal grains, the proportion of In is 0.5-5wt%, for example, 0.5wt%, 1wt%, 2wt%, 3wt%, based on the total mass of the crystal grains in the welding material being 100%. , 4wt% or 5wt%, etc.
优选地，当所述晶粒中存在Bi时，以焊接材料中晶粒的总质量为100％计，Bi的占比为0.5-5wt％，例如0.5wt％、1wt％、2wt％、3wt％、4wt％或5wt％等。Preferably, when Bi exists in the crystal grains, the proportion of Bi is 0.5-5wt%, for example, 0.5wt%, 1wt%, 2wt%, 3wt%, based on the total mass of the crystal grains in the welding material being 100%. , 4wt% or 5wt%, etc.
优选地，所述金属间化合物包括Cu 6Sn 5、Cu 3Sn、Cu 7In 3、Sn 3Sb 2或SnSb中的任意一种或至少两种的组合。 Preferably, the intermetallic compound includes any one or a combination of at least two of Cu 6 Sn 5 , Cu 3 Sn, Cu 7 In 3 , Sn 3 Sb 2 or SnSb.
第二方面，本申请实施例提供一种制备如第一方面所述焊接材料并焊接的方法，所述方法包括以下步骤：In a second aspect, an embodiment of the present application provides a method for preparing and welding the welding material as described in the first aspect, the method comprising the following steps:
(1)将纳米焊料原料与助焊剂和溶剂混合，得到焊膏；(1) Mix the nano-solder raw material with flux and solvent to obtain solder paste;
(2)将步骤(1)所述焊膏涂在第一基底上，将第二基底置于所述焊膏上，进行回流烧结，得到所述焊接材料并实现第一基底和第二基底的焊接，所述烧结的温度在纳米焊料原料的熔点温度以下。(2) Coat the solder paste of step (1) on the first substrate, place the second substrate on the solder paste, and perform reflow sintering to obtain the solder material and realize the bonding between the first substrate and the second substrate. For soldering, the sintering temperature is below the melting point temperature of the nano-solder raw material.
该制备方法中，步骤(2)将焊膏加热并快速烧结至焊点熔点以下，以保持纳米晶粒尺寸，而不会使晶粒发生广泛的变大。In the preparation method, in step (2), the solder paste is heated and sintered rapidly to below the melting point of the solder joint, so as to maintain the size of the nanocrystalline grains without causing extensive enlargement of the grains.
该方法中，和常用焊接相比，接口是烧结而成，无需熔化焊料本身。In this method, compared with conventional soldering, the interface is sintered without melting the solder itself.
该制备方法中，纳米焊料原料可以为合金，如Sn为基板的焊料合金、Bi-Sn基板焊料合金、In-Sn基板焊料合金，也可以为熔点相对较低的金属间化合物的纳米粒子，如包含Sn或包含Cu金属间化合物(例如Cu 6Sn 5(熔点＝415℃),Cu 3Sn(熔点＝676℃),Cu 7In 3(熔点＝631℃),Sn 3Sb 2(熔点＝322℃),SnSb(熔点～400℃))。 In the preparation method, the nano-solder raw material can be an alloy, such as a solder alloy with Sn as a substrate, a Bi-Sn substrate solder alloy, an In-Sn substrate solder alloy, or a nanoparticle of an intermetallic compound with a relatively low melting point, such as Sn-containing or Cu-containing intermetallic compounds (eg Cu 6 Sn 5 (melting point=415°C), Cu 3 Sn (melting point=676° C.), Cu 7 In 3 (melting point=631° C.), Sn 3 Sb 2 (melting point=322° C.) ℃), SnSb (melting point ~ 400℃)).
该制备方法得到的焊料具有超塑性和抗疲劳性。The solder obtained by the preparation method has superplasticity and fatigue resistance.
作为本申请优选的技术方案，步骤(1)所述纳米焊料原料的尺寸小于500nm，例如490nm、450nm、400nm、300nm、200nm、100nm、50nm、30nm或20nm等，优选为小于100nm，更优选为小于50nm，进一步优选为小于30nm。As a preferred technical solution of the present application, the size of the nano-solder raw material in step (1) is less than 500 nm, such as 490 nm, 450 nm, 400 nm, 300 nm, 200 nm, 100 nm, 50 nm, 30 nm or 20 nm, etc., preferably less than 100 nm, more preferably less than 50 nm, more preferably less than 30 nm.
优选地，步骤(1)所述纳米焊料原料的制备方法包括火花电蚀、化学合成或物理气相沉积，优选为火花电蚀。Preferably, the preparation method of the nano-solder raw material in step (1) includes spark erosion, chemical synthesis or physical vapor deposition, preferably spark erosion.
虽然制备纳米颗粒的技术多种多样，但根据本申请，火花电蚀法是制备焊料合金纳米颗粒的通用且首选的方法之一，因为大规模制造容易且成本有效。电火花蚀刻单元像“门”字形轮廓，包含有两个电极和由相关焊料合金组成的电荷颗粒，放置在网筛上面，并浸入非电解质溶液(不导电的溶液)中。电极与脉冲电源相连。火花电蚀单元安装在双壁真空夹套玻璃容器中，该玻璃容器 装有非电解质溶液，优选液氮，以防止纳米粒子氧化。两个合金的电极被安装在本单元中并连接到脉冲电源。将相同的焊料合金电荷颗粒件(如直径1～3cm)充入穿孔支架内，使其与电极接触。振动玻璃容器，使电极和电荷颗粒之间接触和断开。因此，电极之间的电接触是随机的，每一个火花都会导致纳米颗粒的形成。Although there are various techniques for preparing nanoparticles, according to the present application, spark erosion is one of the common and preferred methods for preparing solder alloy nanoparticles because of the ease and cost-effectiveness of large-scale manufacturing. The EDM unit is shaped like a "gate" and contains two electrodes and charged particles composed of an associated solder alloy, placed on a mesh screen, and immersed in a non-electrolyte solution (a solution that does not conduct electricity). The electrodes are connected to a pulsed power source. The spark erosion unit is housed in a double-walled vacuum-jacketed glass vessel containing a non-electrolyte solution, preferably liquid nitrogen, to prevent oxidation of the nanoparticles. Two alloyed electrodes were installed in the unit and connected to a pulsed power source. Charge particles of the same solder alloy (eg, 1 to 3 cm in diameter) are filled into the perforated holder to make contact with the electrodes. Vibrate the glass container to make contact and disconnection between the electrodes and the charged particles. Therefore, the electrical contact between the electrodes is random, and each spark leads to the formation of nanoparticles.
脉冲电源是一个通电电容器。当电极和电荷之间的间隙足够小，使它们之间的电场大于介质击穿电场时，电容器就会放电，在相关部件之间产生火花(微等离子体)。这个由电子和正离子组成的等离子体温度非常高，大约是10000K。速度较快的电子和速度较慢的离子的能量沉积在产生火花的局部区域，使它们过热至沸腾。当火花崩溃时，蒸发的合金和熔滴从沸腾区域猛烈地喷射出来，并穿过等离子体区域进入介质液体，在那里它们被迅速冷却而淬火。A pulsed power supply is a energized capacitor. When the gap between the electrodes and the charge is small enough that the electric field between them is greater than the dielectric breakdown electric field, the capacitor discharges, creating sparks (microplasma) between the associated components. This plasma of electrons and positive ions is very hot, about 10,000K. The energy of the faster electrons and slower ions is deposited in the localized area where the spark occurs, overheating them to the point of boiling. When the spark collapses, the vaporized alloy and droplets are violently ejected from the boiling region and pass through the plasma region into the medium liquid, where they are rapidly cooled and quenched.
金属或合金的汽化部分是“纳米”颗粒合成的一个重要部分，因为蒸汽密集地成核并冻结成极小的纳米颗粒。熔化的金属或合金液滴淬火成微米级状态的颗粒，因为很小，很容易被过滤。因为淬火速率非常迅速，甚至微米级的粒子也可以有很小的晶粒尺寸。液滴或冷凝蒸汽的原位淬火倾向于产生具有亚纳米晶粒结构的球形颗粒。这些颗粒通过网筛下降到电火花蚀刻单元的底部，然后被收集和处理。The vaporized part of the metal or alloy is an important part of the synthesis of "nano" particles because the vapor nucleates densely and freezes into extremely small nanoparticles. Molten metal or alloy droplets are quenched into micron-sized particles, which are easily filtered because of their small size. Because the quench rate is very rapid, even micron-sized particles can have very small grain sizes. In-situ quenching of droplets or condensed vapors tends to produce spherical particles with sub-nanograin structure. These particles descend through a mesh screen to the bottom of the EDM unit, where they are collected and processed.
优选地，步骤(1)所述纳米焊料原料的制备方法包括火花电蚀、化学合成或物理气相沉积。Preferably, the preparation method of the nano-solder raw material in step (1) includes spark erosion, chemical synthesis or physical vapor deposition.
优选地，步骤(1)所述助焊剂包括免洗助焊剂和/或水洗助焊剂。Preferably, the flux in step (1) includes no-clean flux and/or water-wash flux.
优选地，步骤(1)所述溶剂包括乙醇、丙醇、丁醇、丙酮、甲苯异丁基甲酮、醋酸乙酯、醋酸丁酯或无机离子溶液中的任意一种或至少两种的组合。Preferably, the solvent in step (1) includes any one or a combination of at least two of ethanol, propanol, butanol, acetone, toluene isobutyl ketone, ethyl acetate, butyl acetate or inorganic ion solutions.
优选地，步骤(1)还包括：在所述焊膏中加入添加剂。Preferably, step (1) further comprises: adding additives to the solder paste.
优选地，所述添加剂包括合成树脂表面活性剂、有机酸活化剂、防腐蚀剂，助溶剂、成膜剂、润湿剂、胶黏剂、触变剂、增稠剂、消光剂、光亮剂或阻燃剂中的任意一种或至少两种的组合。Preferably, the additives include synthetic resin surfactants, organic acid activators, corrosion inhibitors, cosolvents, film formers, wetting agents, adhesives, thixotropic agents, thickeners, matting agents, brighteners or Any one or a combination of at least two of the flame retardants.
该制备方法中，纳米焊料原料、助焊剂、溶剂以及添加剂的加入比例可根据需要进行调整，这里不作限定。In the preparation method, the addition ratios of nano-solder raw materials, fluxes, solvents and additives can be adjusted as required, which are not limited here.
优选地，步骤(2)所述将步骤(1)所述焊膏涂在第一基底上的方法包括网板印刷、油墨喷嘴打印或使用压印模具的图案转移印刷。Preferably, the method of applying the solder paste of step (1) on the first substrate in step (2) includes screen printing, ink nozzle printing or pattern transfer printing using an imprint mold.
优选地，步骤(2)所述第一基底和第二基底均为电子器件。Preferably, the first substrate and the second substrate in step (2) are both electronic devices.
优选地，步骤(2)所述将第二基底置于所述焊膏上的方法为倒装芯片安装法。Preferably, the method for placing the second substrate on the solder paste in step (2) is a flip-chip mounting method.
优选地，步骤(2)所述烧结的时间为30-90秒，例如30秒、40秒、50秒、60秒、70秒、80秒或90秒等。这里，如果烧结时间过长，会导致晶粒过大，也不利于小角度晶界的生成。Preferably, the sintering time in step (2) is 30-90 seconds, such as 30 seconds, 40 seconds, 50 seconds, 60 seconds, 70 seconds, 80 seconds or 90 seconds, etc. Here, if the sintering time is too long, the grain size will be too large, which is not conducive to the formation of small-angle grain boundaries.
作为本申请优选的技术方案，所述方法还包括：在步骤(1)中，将分散剂与纳米焊料原料、助焊剂和溶剂一起混合，得到焊膏。As a preferred technical solution of the present application, the method further includes: in step (1), mixing the dispersant, the nano-solder raw material, the flux and the solvent together to obtain a solder paste.
当应用于器件封装焊接头时，由于具有较小分散剂纳米粒子的晶粒具有生长抑制特性，烧结后形成具有纳米晶粒结构的致密焊料合金，这有利于增强超塑性特性，以适应偶然的应力集中，并提高抗疲劳性和抗电子迁移性。所制得的分散剂诱导的纳米颗粒焊料具有超细晶粒或纳米级焊料的微观结构(如晶粒尺寸<1μm，优选<0.2μm，更优选<50nm平均粒径)，与粗粒焊料(如>5μm晶粒尺寸)相比，在拉伸试验中表现出超塑性和符合机械延伸率，至少提高了50％。与具有粗晶粒结构的相同成分的焊料相比，纳米级焊料的抗疲劳寿命或抗电子迁移寿命至少提高了2倍(如>5μm颗粒尺寸)。When applied to device packaging solder joints, due to the growth-inhibiting properties of grains with smaller dispersant nanoparticles, a dense solder alloy with a nanograin structure is formed after sintering, which is beneficial for enhancing superplastic properties to accommodate accidental Stress concentration, and improved fatigue resistance and resistance to electron migration. The prepared dispersant-induced nanoparticle solder has the microstructure of ultrafine grains or nanoscale solder (such as grain size <1 μm, preferably <0.2 μm, more preferably <50nm average particle size), which is different from coarse grained solder ( Compared with >5μm grain size), it exhibits superplasticity and conforms to mechanical elongation in tensile test, which is increased by at least 50%. Compared to solders of the same composition with a coarse-grained structure, nanoscale solders exhibit at least a 2-fold improvement in fatigue life or electron migration resistance (eg >5 μm particle size).
优选地，所述分散剂包括氧化物、氮化物、氧氮化物、氟化物或碳化物，且所述分散剂中的含有Ti、Zr、Al、Si、Fe、Cr或Ge中的任意一种。Preferably, the dispersing agent comprises oxides, nitrides, oxynitrides, fluorides or carbides, and the dispersing agent contains any one of Ti, Zr, Al, Si, Fe, Cr or Ge .
该方法中的分散剂是不溶性纳米粒子，TiO 2、ZrO 2、Al 2O 3、SiO 2、Fe 2O 3、Cr 2O 3、SiO 2、GeO 2或其他氧化物、氮化物、氧氮化物、氟化物或碳化物的2-10nm直径纳米粒子，将不溶性纳米粒子(如Al、Cr、Ge、Si)特意加入并均匀分布于焊料基体中。 The dispersants in this method are insoluble nanoparticles, TiO 2 , ZrO 2 , Al 2 O 3 , SiO 2 , Fe 2 O 3 , Cr 2 O 3 , SiO 2 , GeO 2 or other oxides, nitrides, oxynitrides 2-10nm diameter nanoparticles of sulfide, fluoride or carbide, insoluble nanoparticles (such as Al, Cr, Ge, Si) are intentionally added and uniformly distributed in the solder matrix.
优选的，所述分散剂的尺寸为2-10nm，例如2nm、3nm、4nm、5nm、6nm、7nm、8nm、9nm或10nm等。Preferably, the size of the dispersant is 2-10 nm, such as 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm or 10 nm, and the like.
第三方面，本申请实施例提供另一种如第一方面所述焊接材料的制备方法，所述方法包括以下步骤：In a third aspect, an embodiment of the present application provides another method for preparing a welding material as described in the first aspect, the method comprising the following steps:
对焊料原料进行加热-冷却循环，得到所述焊接材料。The solder raw material is subjected to a heating-cooling cycle to obtain the solder material.
该方法通过相变热循环(固态到液态或固态到固态)，重复多次，逐步细化晶粒而实现的另一种制备纳米颗粒焊点的新方法。这种超细或纳米尺寸的晶粒结构有利于实现具有抗疲劳和抗电子迁移能力的超塑性和抗机械失效的接头。该 方法得到的焊料组织(例如晶粒尺寸<5μm，优选<1μm，更优选<0.2μm，甚至优选<50nm的平均晶粒尺寸)，与粗粒焊料(如>5μm晶粒尺寸)相比，在拉伸试验中表现出超塑性，且符合机械延伸率提高至少50％。与具有粗晶粒结构的相同成分的焊料相比，纳米级焊料的抗疲劳寿命或抗电子迁移寿命提高了至少2倍。This method is another new method for preparing nanoparticle solder joints, which is realized by phase-change thermal cycle (solid to liquid or solid to solid), repeated many times, and gradually refines the grains. This ultra-fine or nano-sized grain structure is beneficial for realizing superplastic and mechanical failure-resistant joints with fatigue and electron migration resistance. The solder texture obtained by this method (eg grain size < 5 μm, preferably < 1 μm, more preferably < 0.2 μm, even preferably < 50 nm average grain size), compared to coarse-grained solders (eg > 5 μm grain size), Exhibits superplasticity in tensile tests and is consistent with at least a 50% increase in mechanical elongation. The nanoscale solder exhibits at least a 2-fold improvement in fatigue life or electron migration resistance compared to a solder of the same composition with a coarse grain structure.
纳米焊料也可以通过加热-冷却循环固体相变来实现，这样在实现超微晶粒的同时，实现了相邻晶粒之间的位相差小于10°。Nano-solder can also be realized by heating-cooling cyclic solid phase transition, so that the phase difference between adjacent grains is less than 10° while realizing ultra-fine grains.
作为本申请优选的技术方案，所述加热-冷却循环的循环次数为1-20次，例如1次、2次、3次、4次、5次、6次、7次、8次、9次、10次、11次、12次、13次、14次、15次、16次、17次、18次、19次或20次等。As a preferred technical solution of the present application, the number of cycles of the heating-cooling cycle is 1-20 times, such as 1 time, 2 times, 3 times, 4 times, 5 times, 6 times, 7 times, 8 times, 9 times , 10 times, 11 times, 12 times, 13 times, 14 times, 15 times, 16 times, 17 times, 18 times, 19 times or 20 times, etc.
优选地，在进行加热-冷却循环前，将所述焊料原料置于基底和要封装的倒装芯片类器件之间形成固体焊点。Preferably, the solder stock is placed between the substrate and the flip-chip type device to be packaged to form a solid solder joint prior to the heating-cooling cycle.
优选的，所述加热-冷却循环使得所述焊接材料产生固态相变。温度变化时，焊料原料(例如锡料)经理固态相变，循环多次后得到所述焊接材料。Preferably, the heating-cooling cycle causes the welding material to undergo a solid-state phase transition. When the temperature changes, the solder material (eg, tin material) undergoes a solid-state phase transition, and the solder material is obtained after several cycles.
第四方面，本申请实施例提供又一种如第一方面所述焊接材料的制备方法，所述方法包括以下步骤：In a fourth aspect, the embodiments of the present application provide another method for preparing a welding material according to the first aspect, the method comprising the following steps:
对焊料原料进行拉伸-压缩循环，得到所述焊接材料。The solder material is obtained by subjecting the solder raw material to a tension-compression cycle.
该方法通过应力循环诱导的具有渐进变形和再结晶的超细晶或纳米晶焊点，有利于增强超塑性特性，以适应偶然的应力集中和具有抗疲劳和耐电迁移的防机械失效焊接头。该方法制备的纳米晶粒焊料(如晶粒尺寸的<1μm,最好是<0.2μm,更好是<50nm平均晶粒尺寸)与粗粒焊料(如>5μm晶粒尺寸)相比，在拉伸试验中表现出超塑性，且符合机械延伸率至少提高50％。该纳米晶粒焊料还具有抗疲劳性能和抗电迁移特性,与具有粗晶粒结构的相同成分焊料相比，抗疲劳寿命或抗电迁移寿命至少提高了2倍(如>5μm晶粒尺寸)。This method facilitates enhanced superplastic properties through stress cycling-induced ultrafine or nanocrystalline solder joints with progressive deformation and recrystallization to accommodate accidental stress concentrations and mechanical failure-resistant solder joints with fatigue and electromigration resistance . Nano-grained solders prepared by this method (eg, grain size <1 μm, preferably <0.2 μm, more preferably <50 nm average grain size), compared with coarse-grained solders (eg >5 μm grain size), in It exhibits superplasticity in tensile tests and is consistent with at least a 50% increase in mechanical elongation. The nano-grained solder also has anti-fatigue properties and anti-electromigration properties, compared with the same composition solder with a coarse grain structure, the anti-fatigue life or anti-electromigration life is increased by at least 2 times (eg >5μm grain size) .
该制备方法通过拉伸-压缩循环，同时实现了相邻晶粒之间的位相差小于10°。The preparation method achieves that the phase difference between adjacent crystal grains is less than 10° through the stretching-compression cycle.
作为本申请优选的技术方案，所述拉伸包括热拉伸、机械拉伸或振动拉伸；As a preferred technical solution of the present application, the stretching includes thermal stretching, mechanical stretching or vibration stretching;
优选地，在进行拉伸-压缩循环之前，将所述焊料原料置于基底和要封装的倒装芯片类器件之间形成固体焊点。Preferably, the solder stock is placed between the substrate and the flip-chip type device to be packaged to form a solid solder joint prior to performing the stretch-compression cycle.
所述热拉伸可以有芯片和基底材料的热胀冷缩系数不同而在温度变化时对 焊料原料产生热拉伸。In the thermal stretching, the thermal expansion and contraction coefficients of the chip and the base material may be different so that the solder raw material is thermally stretched when the temperature changes.
第五方面，本申请实施例提供如第一方面所述焊接材料的用途，所述焊接材料用于电子、计算机、通信、运输、航空航天应用、军事应用或消费应用中的互连和封装用途。In a fifth aspect, embodiments of the present application provide the use of the solder material according to the first aspect for interconnection and packaging applications in electronics, computers, communications, transportation, aerospace applications, military applications or consumer applications .
与相关技术相比，本申请具有以下有益效果：Compared with the related art, the present application has the following beneficial effects:
(1)本申请实施例提供的焊接材料具有小晶粒和小角度晶界，这使得所述焊接材料的机械延伸率、抗疲劳寿命和抗电子迁移寿命有显著的改善。(1) The welding materials provided in the embodiments of the present application have small grains and small-angle grain boundaries, which significantly improve the mechanical elongation, fatigue life and electron migration resistance of the welding materials.
(2)本申请实施例提供的焊接材料制备方法均具有操作简单、流程短、生产成本低廉，适于进行产业化应用的优点。(2) The welding material preparation methods provided in the embodiments of the present application all have the advantages of simple operation, short process and low production cost, and are suitable for industrial application.
在阅读并理解了附图和详细描述后，可以明白其他方面。Other aspects will become apparent upon reading and understanding of the drawings and detailed description.
附图说明Description of drawings
附图用来提供对本文技术方案的进一步理解，并且构成说明书的一部分，与本申请的实施例一起用于解释本文的技术方案，并不构成对本文技术方案的限制。The accompanying drawings are used to provide a further understanding of the technical solutions herein, and constitute a part of the specification, and together with the embodiments of the present application, they are used to explain the technical solutions herein, and do not constitute a limitation on the technical solutions herein.
图1为本申请实施例1中制备纳米焊料原料的装置示意图。FIG. 1 is a schematic diagram of an apparatus for preparing nano-solder raw materials in Example 1 of the application.
图2为本申请实施例1中制备纳米焊料的过程中分散剂的作用原理示意图。FIG. 2 is a schematic diagram of the action principle of the dispersant in the process of preparing the nano-solder in Example 1 of the application.
具体实施方式Detailed ways
为更好地说明本申请，便于理解本申请的技术方案，下面对本申请进一步详细说明。但下述的实施例仅仅是本申请的简易例子，并不代表或限制本申请的权利保护范围，本申请保护范围以权利要求书为准。In order to better illustrate the present application and facilitate the understanding of the technical solutions of the present application, the present application will be described in further detail below. However, the following embodiments are only simple examples of the present application, and do not represent or limit the protection scope of the present application. The protection scope of the present application is subject to the claims.
以下为本申请典型但非限制性实施例：The following are typical but non-limiting examples of the application:
实施例1Example 1
本实施例提供一种焊料，所述焊料主要由晶粒组成，所述晶粒为Sn-Ag-Cu合金，晶粒尺寸范围为20-30nm，相邻晶粒之间的位相差为2°-7°。以焊料中以Sn-Ag-Cu合金晶粒的总质量计，晶粒中Sn的质量分数为94wt％，Ag的质量分数为5wt％，Cu的质量分数为1wt％。所述焊料中还含有质量分数为0.1-0.25％wt％的SiO 2分散剂(以焊料中Sn-Ag-Cu合金晶粒的总质量为100％计，分散剂的尺寸为2-10nm)。 This embodiment provides a solder, the solder is mainly composed of crystal grains, the crystal grains are Sn-Ag-Cu alloy, the grain size range is 20-30 nm, and the phase difference between adjacent crystal grains is 2° -7°. Based on the total mass of Sn-Ag-Cu alloy grains in the solder, the mass fraction of Sn in the grains is 94wt%, the mass fraction of Ag is 5wt%, and the mass fraction of Cu is 1wt%. The solder also contains a mass fraction of 0.1-0.25% wt % SiO 2 dispersant (based on the total mass of Sn-Ag-Cu alloy grains in the solder as 100%, the size of the dispersant is 2-10 nm).
本实施例还提供一种制备所述焊料的方法，其具体方法为：This embodiment also provides a method for preparing the solder, the specific method of which is:
(1)将纳米焊料原料Sn-Ag-Cu合金纳米颗粒(粒径为20-30nm)、免洗助焊剂、溶剂乙醇、分散剂SiO 2以2:1:5:0.5的质量比混合，得到焊膏； (1) Mix the nano-solder raw material Sn-Ag-Cu alloy nanoparticles (particle size is 20-30nm), no-clean flux, solvent ethanol, and dispersant SiO in a mass ratio of 2 :1:5:0.5 to obtain solder paste;
(2)将步骤(1)所述焊膏用网板印刷法涂在第一基底(基板器件)表面，然后将第二基底(另一芯片器件)通过倒装芯片安装方式放置在涂有焊膏的第一基底上，用于电子封装组装。然后将加热到200℃回流烧结，得到所述焊料。(2) Coat the solder paste described in step (1) on the surface of the first substrate (substrate device) by screen printing, and then place the second substrate (another chip device) on the surface of the first substrate (another chip device) by flip-chip mounting Paste on the first substrate for electronic package assembly. The solder is then reflowed and sintered by heating to 200°C.
步骤(1)所述纳米焊料原料Sn-Ag-Cu合金纳米颗粒的制备方法如图1所示，在焊料和金组成的焊料电荷颗粒(直径1-3cm)置于网筛上，网筛置于非电解质溶液(液氮)中，网筛上设有两个电解并连接到脉冲电源。振动玻璃容器，使电极和电荷颗粒之间接触和断开。因此，电极之间的电接触是随机的，每一个火花都会导致纳米颗粒的形成。脉冲电源是一个通电电容器。当电极和电荷之间的间隙足够小，使它们之间的电场大于介质击穿电场时，电容器就会放电，在相关部件之间产生火花(微等离子体)。这个由电子和正离子组成的等离子体温度非常高，大约是10000K。速度较快的电子和速度较慢的离子的能量沉积在产生火花的局部区域，使它们过热至沸腾。当火花崩溃时，蒸发的合金和熔滴从沸腾区域猛烈地喷射出来，并穿过等离子体区域进入介质液体，在那里它们被迅速冷却而淬火，得到所述纳米焊料原料。The preparation method of the nano-solder raw material Sn-Ag-Cu alloy nanoparticles in step (1) is shown in Figure 1. The solder charge particles (diameter 1-3cm) composed of solder and gold are placed on a mesh screen, and the mesh screen is placed. In a non-electrolyte solution (liquid nitrogen), two electrolyzers were placed on the mesh screen and connected to a pulsed power source. Vibrate the glass container to make contact and disconnection between the electrodes and the charged particles. Therefore, the electrical contact between the electrodes is random, and each spark leads to the formation of nanoparticles. A pulsed power supply is a energized capacitor. When the gap between the electrodes and the charge is small enough that the electric field between them is greater than the dielectric breakdown electric field, the capacitor discharges, creating sparks (microplasma) between the associated components. This plasma of electrons and positive ions is very hot, about 10,000K. The energy of the faster electrons and slower ions is deposited in the localized area where the spark occurs, overheating them to the point of boiling. When the spark collapses, the vaporized alloy and droplets are violently ejected from the boiling region and pass through the plasma region into the medium liquid, where they are rapidly cooled and quenched, resulting in the nanosolder feedstock.
步骤(1)所述分散剂SiO 2所起的作用如图2所示，小尺寸的分散剂存在尽力生长抑制特性，在烧结后可以使Sn-Ag-Cu合金晶粒具有纳米晶粒结构，得到致密的焊料。 The role of the dispersant SiO 2 in step (1) is shown in Figure 2. The small-sized dispersant has the best growth inhibition property, and after sintering, the Sn-Ag-Cu alloy grains can have a nano-grain structure, A dense solder is obtained.
实施例2Example 2
本实施例提供一种焊料，所述焊料主要由晶粒组成，所述晶粒为Sn-Ag-In合金，晶粒尺寸范围为40-50nm，相邻晶粒之间的位相差为4°。以焊料中以Sn-Ag-In合金晶粒的总质量计，晶粒中Sn的质量分数为94.5wt％，Ag的质量分数为0.5wt％，In的质量分数为5wt％。所述焊料中还含有质量分数为0.1wt％的TiO 2分散剂(以焊料中Sn-Ag-In合金晶粒的总质量为100％计，分散剂的尺寸为2-10nm)。 This embodiment provides a solder, the solder is mainly composed of crystal grains, the crystal grains are Sn-Ag-In alloys, the grain size range is 40-50 nm, and the phase difference between adjacent crystal grains is 4° . Based on the total mass of Sn-Ag-In alloy grains in the solder, the mass fraction of Sn in the grains is 94.5wt%, the mass fraction of Ag is 0.5wt%, and the mass fraction of In is 5wt%. The solder also contains a TiO 2 dispersant with a mass fraction of 0.1 wt % (the size of the dispersant is 2-10 nm based on the total mass of Sn-Ag-In alloy grains in the solder as 100%).
本实施例还提供一种制备所述焊料的方法，其具体方法为：This embodiment also provides a method for preparing the solder, the specific method of which is:
(1)将纳米焊料原料Sn-Ag-In合金纳米颗粒(粒径为40-50nm)、免洗助焊剂、溶剂丁醇、分散剂TiO 2以2:1:3:0.2的质量比混合，得到焊膏； (1) The nano-solder raw material Sn-Ag-In alloy nanoparticles (particle size is 40-50nm), no-clean flux, solvent butanol, dispersant TiO 2 are mixed in a mass ratio of 2:1:3:0.2, get solder paste;
(2)将步骤(1)所述焊膏用油墨喷嘴打印法涂在第一基底(基板器件) 表面，然后将第二基底(另一芯片器件)通过倒装芯片安装方式放置在涂有焊膏的第一基底上，用于电子封装组装。然后将加热到150℃回流烧结30秒，得到所述焊料。(2) The solder paste described in step (1) is coated on the surface of the first substrate (substrate device) by the ink nozzle printing method, and then the second substrate (another chip device) is placed on the surface of the first substrate (another chip device) by flip-chip mounting. Paste on the first substrate for electronic package assembly. The solder was then obtained by heating to 150° C. for reflow sintering for 30 seconds.
本实施例中，Sn-Ag-In合金纳米颗粒的制备方法参照实施例1。In this embodiment, the preparation method of Sn-Ag-In alloy nanoparticles refers to Embodiment 1.
实施例3Example 3
本实施例提供一种焊料，所述焊料主要由晶粒组成，所述晶粒为Sn-Cu合金，晶粒尺寸范围为80-120nm，相邻晶粒之间的位相差为5°。以焊料中以Sn-Cu合金晶粒的总质量计，晶粒中Sn的质量分数为98wt％，Cu的质量分数为2wt％。This embodiment provides a solder, the solder is mainly composed of crystal grains, the crystal grains are Sn-Cu alloy, the grain size range is 80-120 nm, and the phase difference between adjacent crystal grains is 5°. Based on the total mass of Sn-Cu alloy grains in the solder, the mass fraction of Sn in the grains is 98 wt %, and the mass fraction of Cu is 2 wt %.
本实施例还提供一种制备所述焊料的方法，其具体方法为：This embodiment also provides a method for preparing the solder, the specific method of which is:
(1)将纳米焊料原料Sn-Cu合金纳米颗粒(粒径为60-120nm)、水洗助焊剂、溶剂(1) The nano-solder raw material Sn-Cu alloy nanoparticles (particle size is 60-120nm), water-washing flux, solvent
丙酮以4:1:3的质量比混合，得到焊膏；Acetone is mixed in a mass ratio of 4:1:3 to obtain solder paste;
(2)将步骤(1)所述焊膏用网板印刷法涂在第一基底(基板器件)表面，然后将第二基底(另一芯片器件)通过倒装芯片安装方式放置在涂有焊膏的第一基底上，用于电子封装组装。然后将加热到200℃烧结90秒，得到所述焊料。(2) Coat the solder paste described in step (1) on the surface of the first substrate (substrate device) by screen printing, and then place the second substrate (another chip device) on the surface of the first substrate (another chip device) by flip-chip mounting Paste on the first substrate for electronic package assembly. The solder was then obtained by heating to 200°C for 90 seconds and sintering.
本实施例中，Sn-Cu合金纳米颗粒的制备方法参照实施例1。In this embodiment, the preparation method of Sn-Cu alloy nanoparticles refers to Embodiment 1.
实施例4Example 4
本实施例提供一种焊料，所述焊料主要由晶粒组成，所述晶粒为Sn-Sb合金，晶粒尺寸范围为170-190nm，相邻晶粒之间的位相差为7°。以焊料中以Sn-Sb合金晶粒的总质量计，晶粒中Sn的质量分数为95wt％，Sb的质量分数为5wt％。This embodiment provides a solder, the solder is mainly composed of crystal grains, the crystal grains are Sn-Sb alloys, the grain size ranges from 170 to 190 nm, and the phase difference between adjacent crystal grains is 7°. Based on the total mass of Sn-Sb alloy crystal grains in the solder, the mass fraction of Sn in the crystal grains is 95 wt %, and the mass fraction of Sb is 5 wt %.
本实施例还提供一种制备所述焊料的方法，其具体方法为：This embodiment also provides a method for preparing the solder, the specific method of which is:
对置于基底和要封装的倒装芯片类器件之间形成固体焊点的宏观Sn-Sb合金(体积约0.5cm 3)进行加热-冷却15次，得到所述焊料。每一个所述加热-冷却循环均由200℃加热15分钟和10℃冷却15分钟组成。每一个加热-冷却循环都使得Sn-Sb合金经历固态相变，相变诱导产生纳米晶粒。 The solder was obtained by heating-cooling a macroscopic Sn-Sb alloy (about 0.5 cm 3 in volume) placed between the substrate and the flip-chip device to be packaged to form a solid solder joint for 15 times. Each of the heating-cooling cycles consisted of heating at 200°C for 15 minutes and cooling at 10°C for 15 minutes. Each heating-cooling cycle causes the Sn-Sb alloy to undergo a solid-state phase transition, which induces nanograins.
实施例5Example 5
本实施例提供一种焊料，所述焊料主要由晶粒组成，所述晶粒为金属间化合物Cu 3Sn，晶粒尺寸范围为180-205nm，相邻晶粒之间的位相差为5°。 This embodiment provides a solder, the solder is mainly composed of crystal grains, the crystal grains are intermetallic compound Cu 3 Sn, the grain size range is 180-205 nm, and the phase difference between adjacent crystal grains is 5° .
本实施例还提供一种制备所述焊料的方法，其具体方法为：This embodiment also provides a method for preparing the solder, the specific method of which is:
对置于基底和要封装的倒装芯片类器件之间形成固体焊点的宏观金属间化合物Cu 3Sn(体积约0.5cm 3)进行机械上拉-下压的循环20次，得到所述焊料。每个所述机械上拉-下压循环的上拉拉力均为100N，上拉时间均为15秒，下压压力均为100N，下压时间均为15秒。 Perform 20 cycles of mechanical pull-up and push down on the macro intermetallic compound Cu 3 Sn (volume about 0.5 cm 3 ) that forms solid solder joints between the substrate and the flip-chip device to be packaged to obtain the solder . The pull-up force of each mechanical pull-up-pull-down cycle is 100N, the pull-up time is 15 seconds, the push-down pressure is 100N, and the push-down time is 15 seconds.
对比例1Comparative Example 1
本对比例的焊料为Sn-Cu合金，晶粒尺寸范围约为5μm，相邻晶粒之间的位相差为9°。以焊料中以Sn-Cu合金晶粒的总质量计，晶粒中Sn的质量分数为98wt％，Cu的质量分数为2wt％(组成元素的比例与实施例3的焊料相同)。The solder of this comparative example is Sn-Cu alloy, the grain size range is about 5 μm, and the phase difference between adjacent grains is 9°. Based on the total mass of Sn-Cu alloy grains in the solder, the mass fraction of Sn in the grains is 98 wt%, and the mass fraction of Cu is 2 wt% (the proportion of constituent elements is the same as that of the solder in Example 3).
对比例2Comparative Example 2
本对比例的焊料为Sn-Cu合金，晶粒尺寸范围约为1μm，相邻晶粒之间的位相差为26°。以焊料中以Sn-Cu合金晶粒的总质量计，晶粒中Sn的质量分数为98wt％，Cu的质量分数为2wt％(组成元素的比例与实施例3的焊料相同)。The solder of this comparative example is Sn-Cu alloy, the grain size range is about 1 μm, and the phase difference between adjacent grains is 26°. Based on the total mass of Sn-Cu alloy grains in the solder, the mass fraction of Sn in the grains is 98 wt%, and the mass fraction of Cu is 2 wt% (the proportion of constituent elements is the same as that of the solder in Example 3).
上述实施例和对比例中，实施例1-5提供的焊料因为具有小晶粒和小角度晶界，使得所述焊料的机械延伸率、抗疲劳寿命和抗电子迁移寿命有显著的改善。In the above examples and comparative examples, the solders provided in Examples 1-5 have small grains and small-angle grain boundaries, so that the mechanical elongation, fatigue resistance and electron migration resistance of the solders are significantly improved.
对比例1因为晶粒尺寸过大，导致性能下降。In Comparative Example 1, the performance was degraded because the grain size was too large.
对比例2因为相邻晶粒之间的位相差过大，导致性能下降。In Comparative Example 2, the performance was degraded because the phase difference between adjacent crystal grains was too large.
申请人声明，本申请通过上述实施例来说明本申请的详细方法，但本申请并不局限于上述详细方法，即不意味着本申请必须依赖上述详细方法才能实施。所属技术领域的技术人员应该明了，对本申请的任何改进，对本申请产品各原料的等效替换及辅助成分的添加、具体方式的选择等，均落在本申请的保护范围和公开范围之内。The applicant declares that the present application illustrates the detailed method of the present application through the above-mentioned embodiments, but the present application is not limited to the above-mentioned detailed method, which does not mean that the present application must rely on the above-mentioned detailed method for implementation. Those skilled in the art should understand that any improvement to the application, the equivalent replacement of each raw material of the product of the application, the addition of auxiliary components, the selection of specific methods, etc., all fall within the scope of protection and disclosure of the application.

Claims (17)

  1. 一种焊接材料，其中，所述焊接材料包括由晶粒组成，所述晶粒的晶粒尺寸小于1μm和/或所述焊接材料中相邻晶粒之间的位相差小于10°。A welding material, wherein the welding material is composed of crystal grains, the grain size of the crystal grains is less than 1 μm and/or the phase difference between adjacent crystal grains in the welding material is less than 10°.
  2. 根据权利要求1所述焊接材料，其中，所述晶粒的尺寸小于1μm；优选地，所述晶粒的尺寸小于50nm；优选地，所述晶粒的尺寸小于30nm。The solder material according to claim 1, wherein the size of the crystal grains is less than 1 μm; preferably, the size of the crystal grains is less than 50 nm; preferably, the size of the crystal grains is less than 30 nm.
  3. 根据权利要求1或2所述焊接材料，其中，所述晶粒为合金和/或金属间化合物。The welding material according to claim 1 or 2, wherein the crystal grains are alloys and/or intermetallic compounds.
  4. 根据权利要求3所述焊接材料，其中，所述合金中包括Sn；The welding material according to claim 3, wherein Sn is included in the alloy;
    优选地，所述合金中还包括Ag、Cu、Sb、In或Bi中的任意一种或至少两种的组合；Preferably, the alloy further includes any one or a combination of at least two of Ag, Cu, Sb, In or Bi;
    优选地，当所述晶粒中存在Sn时，以焊接材料中晶粒的总质量为100％计，Sn的质量占比≥30 wt％；Preferably, when Sn exists in the crystal grains, based on the total mass of the crystal grains in the welding material being 100%, the mass proportion of Sn is ≥30 wt%;
    优选地，当所述晶粒中存在Ag时，以焊接材料中晶粒的总质量为100％计，Ag的质量占比为0.5-5 wt％；Preferably, when Ag exists in the crystal grains, the mass proportion of Ag is 0.5-5 wt% based on the total mass of the crystal grains in the soldering material being 100%;
    优选地，当所述晶粒中存在Cu时，以焊接材料中晶粒的总质量为100％计，Cu的质量分数为占比0.2-2 wt％；Preferably, when Cu exists in the crystal grains, the mass fraction of Cu accounts for 0.2-2 wt% based on the total mass of the crystal grains in the welding material being 100%;
    优选地，当所述晶粒中存在Sb时，以焊接材料中晶粒的总质量为100％计，Sb的质量占比为0.5-5 wt％；Preferably, when Sb exists in the crystal grains, based on the total mass of the crystal grains in the welding material being 100%, the mass ratio of Sb is 0.5-5 wt%;
    优选地，当所述晶粒中存在In时，以焊接材料的总质量为100％计，In的质量占比为0.5-5 wt％；Preferably, when In exists in the crystal grains, based on the total mass of the welding material being 100%, the mass proportion of In is 0.5-5 wt%;
    优选地，当所述晶粒中存在Bi时，以焊接材料中晶粒的总质量为100％计，Bi的质量占比为0.5-5 wt％；Preferably, when Bi exists in the crystal grains, the mass proportion of Bi is 0.5-5 wt% based on the total mass of the crystal grains in the welding material being 100%;
    优选地，所述金属间化合物包括Cu 6Sn 5、Cu 3Sn、Cu 7In 3、Sn 3Sb 2或SnSb中的任意一种或至少两种的组合。 Preferably, the intermetallic compound includes any one or a combination of at least two of Cu 6 Sn 5 , Cu 3 Sn, Cu 7 In 3 , Sn 3 Sb 2 or SnSb.
  5. 一种制备如权利要求1-4任一项所述焊接材料并焊接的方法，其包括以下步骤：A method for preparing and welding the welding material according to any one of claims 1-4, comprising the steps of:
    (1)将纳米焊料原料与助焊剂和溶剂混合，得到焊膏；(1) Mix the nano-solder raw material with flux and solvent to obtain solder paste;
    (2)将步骤(1)所述焊膏涂在第一基底上，将第二基底置于所述焊膏上，进行回流烧结，得到所述焊接材料并实现第一基底和第二基底的焊接，所述回流烧结的温度在纳米焊料原料的熔点温度以下。(2) Coat the solder paste of step (1) on the first substrate, place the second substrate on the solder paste, and perform reflow sintering to obtain the solder material and realize the bonding between the first substrate and the second substrate. For soldering, the temperature of the reflow sintering is below the melting point temperature of the nano-solder raw material.
  6. 根据权利要求5所述的方法，其中，步骤(1)所述纳米焊料原料的尺 寸小于500nm，优选为小于100nm，更优选为小于50nm，进一步优选为小于30nm。The method according to claim 5, wherein the size of the nano-solder raw material in step (1) is less than 500nm, preferably less than 100nm, more preferably less than 50nm, further preferably less than 30nm.
  7. 根据权利要求5或6所述的方法，其中，步骤(1)所述纳米焊料原料的制备方法包括火花电蚀、化学合成或物理气相沉积。The method according to claim 5 or 6, wherein the preparation method of the nano-solder raw material in step (1) comprises spark erosion, chemical synthesis or physical vapor deposition.
  8. 根据权利要求5-7任一项所述的方法，其中，步骤(1)所述助焊剂包括免洗助焊剂和/或水洗助焊剂；The method according to any one of claims 5-7, wherein the flux in step (1) comprises no-clean flux and/or water-wash flux;
    优选地，步骤(1)所述溶剂包括乙醇、丙醇、丁醇；、丙酮、甲苯异丁基甲酮、醋酸乙酯、醋酸丁酯或无机离子溶液中的任意一种或至少两种的组合；Preferably, the solvent in step (1) comprises ethanol, propanol, butanol; acetone, toluene isobutyl ketone, ethyl acetate, butyl acetate or any one or a combination of at least two of the inorganic ion solutions;
    优选地，步骤(1)还包括：在所述焊膏中加入添加剂；Preferably, step (1) further comprises: adding additives to the solder paste;
    优选地，所述添加剂包括合成树脂表面活性剂、有机酸活化剂、防腐蚀剂，助溶剂、成膜剂、润湿剂、胶黏剂、触变剂、增稠剂、消光剂、光亮剂或阻燃剂中的任意一种或至少两种的组合；Preferably, the additives include synthetic resin surfactants, organic acid activators, anticorrosion agents, cosolvents, film formers, wetting agents, adhesives, thixotropic agents, thickeners, matting agents, brighteners or any one or a combination of at least two of the flame retardants;
    优选地，步骤(2)所述将步骤(1)所述焊膏涂在第一基底上的方法包括网板印刷、油墨喷嘴打印或使用压印模具的图案转移印刷；Preferably, the method of applying the solder paste of step (1) on the first substrate in step (2) includes screen printing, ink nozzle printing or pattern transfer printing using an imprint mold;
    优选地，步骤(2)所述第一基底和第二基底均为电子器件；Preferably, the first substrate and the second substrate in step (2) are both electronic devices;
    优选地，步骤(2)所述将第二基底置于所述焊膏上的方法为倒装芯片安装法；Preferably, the method of placing the second substrate on the solder paste in step (2) is a flip-chip mounting method;
    优选地，步骤(2)所述烧结的时间为30-90秒。Preferably, the sintering time in step (2) is 30-90 seconds.
  9. 根据权利要求5-8任一项所述的方法，其中，所述方法还包括：在步骤(1)中，将分散剂与纳米焊料原料、助焊剂和溶剂一起混合，得到焊膏；The method according to any one of claims 5-8, wherein the method further comprises: in step (1), mixing the dispersant with the nano-solder raw material, the flux and the solvent to obtain a solder paste;
    优选地，所述分散剂包括氧化物、氮化物、氧氮化物、氟化物或碳化物，且所述分散剂中的含有Ti、Zr、Al、Si、Fe、Cr或Ge中的任意一种；Preferably, the dispersing agent comprises oxides, nitrides, oxynitrides, fluorides or carbides, and the dispersing agent contains any one of Ti, Zr, Al, Si, Fe, Cr or Ge ;
    优选地，所述分散剂的尺寸为2-10nm。Preferably, the size of the dispersant is 2-10 nm.
  10. 一种如权利要求1-4任一项所述焊接材料的制备方法，其包括以下步骤：A method for preparing a welding material as claimed in any one of claims 1-4, comprising the steps of:
    对焊料原料进行快速加热-冷却循环，得到所述焊接材料。The solder material is obtained by subjecting the solder raw material to a rapid heating-cooling cycle.
  11. 根据权利要求10所述的制备方法，其中，所述加热-冷却循环的循环次数为1-20次。The preparation method according to claim 10, wherein the number of cycles of the heating-cooling cycle is 1-20 times.
  12. 根据权利要求10或11所述的制备方法，其中，在进行加热-冷却循环前，将所述焊料原料置于基底和要封装的倒装芯片类器件之间形成固体焊点。The manufacturing method according to claim 10 or 11, wherein the solder raw material is placed between the substrate and the flip-chip type device to be packaged to form a solid solder joint before the heating-cooling cycle is performed.
  13. 根据权利要求10-12任一项所述的制备方法，其中，所述加热-冷却循环使得所述焊接材料产生相变。The preparation method according to any one of claims 10-12, wherein the heating-cooling cycle causes the welding material to undergo a phase change.
  14. 一种如权利要求1-4所述焊接材料的制备方法，其包括以下步骤：A method for preparing a welding material as claimed in claims 1-4, comprising the steps of:
    对焊料原料进行拉伸-压缩循环，得到所述焊接材料。The solder material is obtained by subjecting the solder raw material to a tension-compression cycle.
  15. 根据权利要求14所述的制备方法，其中，所述拉伸包括热拉伸、机械拉伸或振动拉伸。The preparation method according to claim 14, wherein the stretching comprises thermal stretching, mechanical stretching or vibration stretching.
  16. 根据权利要求14或15所述的制备方法，其中，在进行拉伸-压缩循环之前，将所述焊料原料置于基底和要封装的倒装芯片类器件之间形成固体焊点。15. The manufacturing method of claim 14 or 15, wherein the solder stock is placed between the substrate and the flip-chip type device to be packaged to form a solid solder joint prior to performing the stretch-compression cycle.
  17. 如权利要求1-4任一项所述焊接材料的用途，其中，所述焊接材料用于电子、计算机、通信、运输、航空航天应用、军事应用或消费应用中的互连和封装用途。The use of solder material according to any one of claims 1 to 4, wherein the solder material is for interconnection and packaging applications in electronics, computers, communications, transportation, aerospace applications, military applications or consumer applications.
PCT/CN2022/084952 2021-04-09 2022-04-02 Soldering material, and preparation method therefor and use thereof WO2022213911A1 (en)

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