CN113579563B - Nano cubic silver solder paste, interconnection structure and welding method - Google Patents
Nano cubic silver solder paste, interconnection structure and welding method Download PDFInfo
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- CN113579563B CN113579563B CN202110860085.0A CN202110860085A CN113579563B CN 113579563 B CN113579563 B CN 113579563B CN 202110860085 A CN202110860085 A CN 202110860085A CN 113579563 B CN113579563 B CN 113579563B
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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
- B23K35/30—Selection of soldering or welding materials proper with the principal constituent melting at less than 1550 degrees C
- B23K35/3006—Ag as the principal constituent
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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
- B23K1/00—Soldering, e.g. brazing, or unsoldering
- B23K1/0008—Soldering, e.g. brazing, or unsoldering specially adapted for particular articles or work
- B23K1/0016—Brazing of electronic components
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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
- B23K1/00—Soldering, e.g. brazing, or unsoldering
- B23K1/008—Soldering within a furnace
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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
- B23K3/00—Tools, devices, or special appurtenances for soldering, e.g. brazing, or unsoldering, not specially adapted for particular methods
- B23K3/06—Solder feeding devices; Solder melting pans
- B23K3/0607—Solder feeding devices
- B23K3/0638—Solder feeding devices for viscous material feeding, e.g. solder paste feeding
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
- H01L24/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
- H01L24/26—Layer connectors, e.g. plate connectors, solder or adhesive layers; Manufacturing methods related thereto
- H01L24/28—Structure, shape, material or disposition of the layer connectors prior to the connecting process
- H01L24/29—Structure, shape, material or disposition of the layer connectors prior to the connecting process of an individual layer connector
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
- H01L24/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
- H01L24/26—Layer connectors, e.g. plate connectors, solder or adhesive layers; Manufacturing methods related thereto
- H01L24/31—Structure, shape, material or disposition of the layer connectors after the connecting process
- H01L24/32—Structure, shape, material or disposition of the layer connectors after the connecting process of an individual layer connector
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
- H01L24/80—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected
- H01L24/83—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected using a layer connector
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
- H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
- H01L2224/26—Layer connectors, e.g. plate connectors, solder or adhesive layers; Manufacturing methods related thereto
- H01L2224/28—Structure, shape, material or disposition of the layer connectors prior to the connecting process
- H01L2224/29—Structure, shape, material or disposition of the layer connectors prior to the connecting process of an individual layer connector
- H01L2224/29001—Core members of the layer connector
- H01L2224/29099—Material
- H01L2224/291—Material with a principal constituent of the material being a metal or a metalloid, e.g. boron [B], silicon [Si], germanium [Ge], arsenic [As], antimony [Sb], tellurium [Te] and polonium [Po], and alloys thereof
- H01L2224/29138—Material with a principal constituent of the material being a metal or a metalloid, e.g. boron [B], silicon [Si], germanium [Ge], arsenic [As], antimony [Sb], tellurium [Te] and polonium [Po], and alloys thereof the principal constituent melting at a temperature of greater than or equal to 950°C and less than 1550°C
- H01L2224/29139—Silver [Ag] as principal constituent
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
- H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
- H01L2224/26—Layer connectors, e.g. plate connectors, solder or adhesive layers; Manufacturing methods related thereto
- H01L2224/31—Structure, shape, material or disposition of the layer connectors after the connecting process
- H01L2224/32—Structure, shape, material or disposition of the layer connectors after the connecting process of an individual layer connector
- H01L2224/325—Material
- H01L2224/32501—Material at the bonding interface
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
- H01L2224/80—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected
- H01L2224/83—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected using a layer connector
- H01L2224/838—Bonding techniques
- H01L2224/83801—Soldering or alloying
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
Abstract
The invention discloses a nano cubic silver soldering paste, an interconnection structure and a welding method thereof. The nano cubic silver particles are cubic and have the particle size of 20-200 nm, and the nano cubic silver soldering paste can be used for preparing a copper-clad ceramic substrate and an interconnection structure of an IGBT module power chip; the invention utilizes the self-assembly performance of the nano cubic silver particles to form a superlattice structure, realizes the close arrangement of the nano cubic silver particles, and the connection joint interface layer of the connection layer formed after welding has good combination, the porosity of the connection layer is about 5 percent, the shear strength reaches more than 30Mpa, and the connection joint has higher shear strength and can be well applied to the packaging interconnection of electronic devices; the preparation process is simple and convenient for industrial production.
Description
Technical Field
The invention belongs to the field of connection of metal nanoparticles, and particularly relates to a nano cubic silver soldering paste and a soldering method thereof.
Background
High power devices such as IGBT modules face challenges in terms of temperature, thermal conductivity, electrical conductivity, and reliability of use. The IGBT module chip is connected by the connecting material to realize the interconnection of the power semiconductor chip and the substrate. Since the connection layer between the chip and the substrate is required to provide necessary functions of heat dissipation, electrical conduction, and mechanical support, the chip interface bonding technology is the most important part in the power semiconductor module package. Conventional high lead solders have reached the limits of performance. In recent years, silver paste soldering technology has been used as a new technology to cope with this challenge. In order to improve the temperature resistance and reliability of the IGBT module, the nano silver solder paste soldering technology has drawn more and more attention in the packaging of IGBT silicon-based chips and other aspects.
The welding technology of the nano silver soldering paste is a method for realizing the interconnection of a power semiconductor device and a substrate by welding nano silver particles. It is a technique for welding nano-silver particles at a temperature below 300 ℃ and realizing good connection through inter-atomic diffusion. Because silver has excellent electric conduction and heat conduction characteristics, the nano-silver soldering paste low-temperature soldering connection layer has high shear strength and connection strength, and the metal silver has a higher melting point (961 ℃), so that the nano-silver soldering paste low-temperature soldering connection layer is very suitable for serving as a high-temperature-resistant chip connection material. The improvement of the overall performance of an electronic packaging product brought by the low-temperature welding technology of the nano-silver soldering paste is far more than 5%, so that the nano-silver soldering paste has better prospect in the packaging application of high-integration and high-power semiconductor devices in the field of power electronics in the future.
The soldering technique of nano-silver solder paste also presents some challenges. The existing nano silver soldering paste usually uses one or two of spherical nano silver particles, flaky nano silver particles or columnar nano silver particles as raw materials, the nano silver particles are tightly arranged by utilizing the self-assembly performance of the nano silver particles, because the nano silver particles have different shapes and non-uniform sizes, the particles can have cavity defects when being tightly arranged, and the porosity of a welded joint connecting layer after welding can also be increased. Both of which can severely reduce the shear strength and thermal conductivity of the die attach layer.
In the invention, a silver soldering paste taking nano cubic silver as a raw material is developed, a superlattice structure is formed before welding by utilizing the self-assembly performance of nano cubic silver particles, the close arrangement of the nano cubic silver particles is realized, and the porosity of a welding connection layer is reduced. The purpose of reducing the porosity of the chip connecting layer is further achieved by a welding method.
Disclosure of Invention
The invention aims to provide a nano cubic silver soldering paste and a welding method thereof, and an interconnection structure and a welding method of a copper-clad ceramic substrate and an IGBT module power chip, which are formed aiming at the problems in the prior art, and better solve the problems of high porosity and low shearing strength of a connecting layer formed by the existing nano silver soldering paste during welding.
In order to solve the technical problems, the technical scheme provided by the invention is as follows:
a nano cubic silver solder paste is formed by mixing nano cubic silver particles with uniform size and an organic solvent, wherein the nano cubic silver particles are cubic and have the particle size of 20-200 nm.
As a preferred mode, a superlattice array structure is formed by utilizing the self-assembly performance of the material in the welding process, so that the close arrangement of nano cubic silver particles is realized, and the porosity of a welding connection layer is reduced.
Preferably, the organic solvent is one or a mixture of two or more selected from the group consisting of ethylene glycol, terpineol, α -terpineol, β -terpineol, γ -terpineol, δ -terpineol, glycerol, diethylene glycol and triethylene glycol.
Preferably, the mass ratio of the nano cubic silver particles to the organic solvent is (5-12): 1.
as a preferred mode, the nano cubic silver particles with the particle size of 20 nm-200 nm are prepared by a polyol thermal reduction method, and the method comprises the following specific steps:
(1) dissolving a catalyst in a solvent to obtain a first reaction solution;
(2) dissolving a ligand in a solvent to obtain a second reaction solution;
(3) dissolving a protective agent in a solvent to obtain a third reaction solution;
(4) dissolving a silver source precursor in a solvent to obtain a fourth reaction solution;
(5) heating ethylene glycol to 155-165 ℃, keeping the temperature for 1-1.5 h, then respectively adding a first reaction solution, a second reaction solution, a third reaction solution and a fourth reaction solution, reacting for 1-2 h at the temperature of 155-165 ℃ under the stirring of a magnetic stirrer, and obtaining a suspension of high-concentration nano cubic silver particles and ethylene glycol after the reaction is finished;
(6) carrying out solid phase separation on the suspension of the nano cubic silver particles and the ethylene glycol to obtain a solid phase product;
(7) sequentially washing and drying the solid-phase product to obtain the nano cubic silver particles;
wherein, the catalyst is selected from any one of sodium sulfide and sodium hydrosulfide;
the ligand is selected from one of hydrochloric acid, sodium chloride and potassium chloride;
the solvent is selected from any one of deionized water, ethanol and glycol;
the silver source precursor is selected from any one of silver nitrate, silver acetate and silver carbonate;
the concentration of the catalyst is 2 mM-6 mM;
the concentration of the ligand is 2 mM-3 mM;
the concentration of the protective agent is 20 mg/mL-40 mg/mL;
the concentration of the silver source precursor is 270 mM-300 mM.
The invention also provides a welding method, which uses the nano cubic silver soldering paste.
The invention also provides an interconnection structure of the copper-clad ceramic substrate and the IGBT module power chip, which is prepared by connecting any one of the nano cubic silver soldering pastes.
Preferably, the copper-clad ceramic substrate and IGBT module power chip interconnection structure is: the chip interconnection structure comprises a copper-clad ceramic substrate, a chemical silver-plated layer, a connecting layer and a silicon carbide power chip in an IGBT module from bottom to top, wherein the connecting layer uses nano cubic silver soldering paste.
The invention also provides a welding method of the interconnection structure of the copper-clad ceramic substrate and the IGBT module power chip, which comprises the following steps:
(1) coating the nano cubic silver soldering paste on a silver-plated copper-clad ceramic substrate in a screen printing mode to obtain printing soldering paste, wherein the nano cubic silver particles form a superlattice array structure through self-assembly performance in the process;
(2) placing an IGBT power chip on the surface of the IGBT power chip to form an interconnection structure;
(3) and (3) placing the interconnection structure in a heating furnace for welding, wherein the heating temperature is 150-300 ℃, the heat preservation time is 20-60 min, and the pressing pressure is 0Mpa, so that the copper-clad ceramic substrate and the silicon carbide power chip are interconnected.
Preferably, in the method for welding the copper-clad ceramic substrate and the interconnection structure of the IGBT module power chip, the silver plating method of the copper-clad ceramic substrate in step (1) is one selected from electroless silver plating and electrolytic silver plating.
Preferably, the heating furnace is selected from one of a tube furnace, a muffle furnace and a vacuum reflux furnace;
preferably, in the welding process, the heating temperature is 150-300 ℃, and the welding time is 20-60 min.
Compared with the prior art, the invention has the beneficial effects that:
(1) the small-size effect of the nano cubic silver particles reduces the welding temperature of the powder, and realizes the non-pressure low-temperature connection of the copper-clad ceramic substrate and the silicon carbide power chip;
(2) the nano cubic silver particles provided by the invention have a self-assembly function, and as shown in fig. 3, the low porosity of a connecting layer of a copper-clad ceramic substrate and a silicon carbide power chip is realized;
(3) the copper-clad ceramic substrate and IGBT module power chip interconnection structure provided by the invention is as shown in figure 1: the IGBT module comprises a copper-clad ceramic substrate, a chemical silver-plated layer, a connecting layer and a silicon carbide power chip in the IGBT module from bottom to top, wherein the connecting layer uses nano cubic silver soldering paste;
(4) the nano cubic silver solder paste provided by the invention can be applied to the field of electronic packaging in low-temperature connection and long-term high-temperature environment work, the connection temperature is 150-300 ℃, and is far lower than the melting temperature (961.8 ℃) of silver blocks;
(5) the interface layer of the connection joint of the connection layer formed by the nano cubic silver soldering paste after soldering is well combined, as shown in figure 4: the porosity of the tie layer is about 5%; the shear strength reaches more than 30Mpa, the low porosity and high shear strength are realized, and the high-strength high-shear-strength high-porosity high-shear-strength high-toughness high-shear-strength high-toughness high-;
(6) the nano cubic silver soldering paste provided by the invention is simple in preparation process and convenient for industrial production.
Drawings
FIG. 1 is a schematic structural diagram of a copper-clad ceramic substrate and a silicon carbide power chip connector in an example of the invention;
FIG. 2 is an SEM image of nano cubic silver prepared by the invention;
FIG. 3 is an SEM image of the nano-cubic silver after self-assembly;
FIG. 4 is an SEM image of a cross section of a copper-clad ceramic substrate and a copper-clad ceramic substrate connector according to the present invention.
The manufacturing method comprises the following steps of 1-silicon carbide power chip, 2-nano cubic silver soldering paste, 3-chemical silver coating, 4-copper coating on a bottom copper-clad ceramic substrate, 5-copper coating on a bottom copper-clad ceramic substrate, and 6-copper coating on a ceramic substrate.
Detailed Description
The invention is further illustrated by the following examples, which are from the patent examples already disclosed and are intended to be illustrative only of the feasibility of the invention and not to limit the scope of the right of protection of the invention.
Comparative example
And preparing the nano silver soldering paste by using one or two of spherical nano silver particles, flaky nano silver particles or columnar nano silver particles as raw materials.
Due to their different shapes and sizes, voids between particles may occur when they are closely arranged, and the porosity of the welded joint connection layer may also increase after welding. Both of which can severely reduce the shear strength and thermal conductivity of the die attach layer. The porosity and shear strength of the tie layer are very important parameters.
The nano silver soldering paste prepared by the prior art and containing the mixed flaky nano silver and the organic solvent carrier has the shear strength of 15MPa and the porosity of about 10 percent under the condition that the temperature of soldering connection is 150-300 ℃.
Example 1
1) The preparation method of the nano cubic silver particles comprises the following specific steps:
firstly, 0.0017g of NaHS is put into 10mL of glycol to prepare a first reaction solution; preparing a second reaction solution by putting 2.5 mu of LHCl into 10mL of ethylene glycol; 0.05g of polyvinylpyrrolidone is put into 2.5mL of glycol to prepare a third reaction solution; a fourth reaction solution was prepared by adding 0.25g of silver trifluoroacetate to 4mL of ethylene glycol. Subsequently, 5mL of ethylene glycol was placed in a glass bottle and heated to 160 ℃ and stirred at a constant temperature for 1 hour, then 0.06mL of the first reaction solution was added, 2 minutes later, 0.5mL of the second reaction solution and 1.25mL of the third reaction solution were added, 2 minutes later, 0.4mL of the fourth reaction solution was added, and the reaction was carried out for 1 hour. And finally, placing the suspension of the nano cubic silver particles and the ethylene glycol in a centrifuge for centrifugal cleaning, wherein the centrifugal speed is 5000r/min, the cleaning is carried out for 5 times, the cleaning time is 20min each time, deionized water is used for cleaning for 4 times, absolute ethyl alcohol is used for cleaning for 1 time, and the nano cubic silver particles with the particle size of 20nm are obtained after drying.
2) The preparation method of the nano cubic silver soldering paste comprises the following specific steps:
adding the prepared nano cubic silver with the particle size of 20nm into the mixture according to the mass ratio of 5: 1 in alpha-terpineol, evenly stirring to obtain the nano cubic silver soldering paste.
3) The preparation method of the nano cubic silver soldering paste for welding the copper-clad ceramic substrate and the IGBT module power chip comprises the following specific steps:
firstly, the copper surface of the copper-clad ceramic substrate is chemically plated with silver, and the thickness of the silver plating layer is 2 μm. Then, ultrasonically cleaning the silver-plated copper-clad ceramic substrate in absolute ethyl alcohol for 10min, and drying for later use; and coating the prepared nano cubic silver soldering paste on a silver-plated copper-clad ceramic substrate in a screen printing mode to obtain printing soldering paste, and placing IGBT power chips on the surface of the printing soldering paste to form interconnection. Finally, the interconnection structure is placed in a muffle furnace for welding, low-temperature welding is carried out under the pressure of 0Mpa, the heating temperature is 200 ℃, the heating rate is 5 ℃/min, and the heat preservation time is 60 min; and cooling along with the furnace after welding is finished to obtain the final product, namely the copper-clad ceramic substrate and the interconnection structure connected with the silicon carbide power chip.
The interconnection structure formed by connecting the copper-clad ceramic substrate and the silicon carbide power chip prepared in the embodiment is subjected to a shear strength test on an electronic universal tester, and the shear strength of the joint is 32 MPa.
According to the microscopic topography of the section of the copper-clad ceramic substrate and the silicon carbide power chip connecting piece prepared by the application example, the porosity of the connecting layer is measured to be 4%.
As shown in fig. 1, the interconnection structure of the copper-clad ceramic substrate and the IGBT module power chip prepared in this embodiment includes, from bottom to top, a copper-clad ceramic substrate 6, a chemical silver coating 3, a connection layer, and a silicon carbide power chip 1 in the IGBT module, the connection layer uses a nano cubic silver solder paste 2, and the copper-clad ceramic substrate 6 includes a copper layer 4 on a bottom copper-clad ceramic substrate and a bottom copper-clad ceramic substrate ceramic layer 5.
Example 2
1) The preparation method of the nano cubic silver particles comprises the following specific steps:
first, 0.0023g of Na was added 2 S is put into 10mL of glycol to prepare a first reaction liquid; 0.05g of NaCl is put into 10mL of glycol to prepare a second reaction solution; 0.05g of polyvinylpyrrolidone is put into 2.5mL of glycol to prepare a third reaction solution; a fourth reaction solution was prepared by adding 0.30g of silver nitrate to 4mL of ethylene glycol. Subsequently, 5mL of ethylene glycol was put in a glass bottle and heated to 155 ℃ and stirred at a constant temperature for 1.5 hours, then 0.06mL of the first reaction solution was added, 2 minutes later, 0.5mL of the second reaction solution and 2.25mL of the third reaction solution were added, 2 minutes later, 0.4mL of the fourth reaction solution was added, and the reaction was carried out for 1.5 hours. And finally, placing the suspension of the nano cubic silver particles and the ethylene glycol in a centrifuge for centrifugal cleaning, wherein the centrifugal speed is 5000r/min, the cleaning is carried out for 5 times, the cleaning time is 20min each time, deionized water is used for cleaning for 4 times, absolute ethyl alcohol is used for cleaning for 1 time, and the nano cubic silver particles with the particle size of 200nm are obtained after drying.
2) The preparation method of the nano cubic silver soldering paste comprises the following specific steps:
adding the nano cubic silver with the particle size of 200nm into the mixture according to the mass ratio of 8: 1, evenly stirring to obtain the nano cubic silver soldering paste.
3) The preparation method of the nano cubic silver soldering paste for welding the copper-clad ceramic substrate and the IGBT module power chip comprises the following specific steps:
firstly, the copper surface of the copper-clad ceramic substrate is chemically plated with silver, and the thickness of the silver plating layer is 2 μm. Then, ultrasonically cleaning the silver-plated copper-clad ceramic substrate in absolute ethyl alcohol for 10min, and drying for later use; and coating the prepared nano cubic silver soldering paste on a silver-plated copper-clad ceramic substrate in a screen printing mode to obtain printing soldering paste, and placing IGBT power chips on the surface of the printing soldering paste to form interconnection. Finally, the interconnection structure is placed in a muffle furnace for welding, and low-temperature welding is carried out under the pressure of 0Mpa, the heating temperature is 300 ℃, the heating rate is 5 ℃/min, and the heat preservation time is 30 min; and cooling along with the furnace after welding is finished to obtain the final product, namely the copper-clad ceramic substrate and the interconnection structure connected with the silicon carbide power chip.
The interconnection structure of the copper-clad ceramic substrate and the silicon carbide power chip prepared in the embodiment was subjected to a shear strength test in an electronic universal tester, and the shear strength of the joint was measured to be 30 MPa.
According to the microscopic topography of the section of the copper-clad ceramic substrate and the silicon carbide power chip connecting piece prepared by the embodiment, the porosity of the connecting layer is measured to be 5%.
As shown in fig. 1, the interconnection structure of the copper-clad ceramic substrate and the IGBT module power chip prepared in this embodiment includes, from bottom to top, a copper-clad ceramic substrate 6, an electroless silver coating layer 3, a connection layer, and a silicon carbide power chip 1 in the IGBT module, the connection layer uses a nano cubic silver solder paste 2, and the copper-clad ceramic substrate 6 includes a copper layer 4 on the bottom copper-clad ceramic substrate and a bottom copper-clad ceramic substrate ceramic layer 5.
Example 3
1) The preparation method of the nano cubic silver particles comprises the following specific steps:
first, 0.0032g of Na 2 S is put into 10mL deionized water to prepare a first reaction liquid; 0.08g KCl was placed in 10mL deionized waterPreparing a second reaction solution; 0.05g of polyvinylpyrrolidone is put into 2.5mL of deionized water to prepare a third reaction solution; a fourth reaction solution was prepared by adding 0.25g of silver carbonate to 4mL of deionized water. Subsequently, 5mL of ethylene glycol was placed in a glass bottle and heated to 165 ℃ and stirred at a constant temperature for 1.25 hours, then 0.06mL of the first reaction solution was added, 2 minutes later, 0.5mL of the second reaction solution and 2.25mL of the third reaction solution were added, 2 minutes later, 0.4mL of the fourth reaction solution was added, and the reaction was carried out for 2 hours. And finally, placing the suspension of the nano cubic silver particles and ethylene glycol in a centrifuge for centrifugal cleaning at the centrifugal rate of 5000r/min for 5 times, wherein the cleaning time is 20min each time, cleaning for 4 times by using deionized water and cleaning for 1 time by using absolute ethyl alcohol, and drying to obtain the nano cubic silver particles with the particle size of 100 nm.
2) The preparation method of the nano cubic silver soldering paste comprises the following specific steps:
adding the prepared nano cubic silver with the particle size of 100nm into the mixed solution according to the mass ratio of 12: 1, and uniformly stirring the mixture in the mixed solution of the glycol and the glycerol to obtain the nano cubic silver soldering paste.
3) The preparation method of the nano cubic silver soldering paste for welding the copper-clad ceramic substrate and the IGBT module power chip comprises the following specific steps:
firstly, the copper surface of the copper-clad ceramic substrate is chemically plated with silver, and the thickness of the silver plating layer is 2 μm. Then, ultrasonically cleaning the silver-plated copper-clad ceramic substrate in absolute ethyl alcohol for 10min, and drying for later use; and coating the prepared nano cubic silver soldering paste on a silver-plated copper-clad ceramic substrate in a screen printing mode to obtain printing soldering paste, and placing IGBT power chips on the surface of the printing soldering paste to form interconnection. Finally, the interconnection structure is placed in a muffle furnace for welding, and low-temperature welding is carried out under the pressure of 0Mpa, the heating temperature is 150 ℃, the heating rate is 5 ℃/min, and the heat preservation time is 60 min; and cooling along with the furnace after welding is finished to obtain the final product, namely the copper-clad ceramic substrate and the interconnection structure connected with the silicon carbide power chip.
The interconnection structure formed by connecting the copper-clad ceramic substrate and the silicon carbide power chip prepared in the embodiment is subjected to a shear strength test on an electronic universal tester, and the shear strength of the joint is measured to be 31 MPa.
According to the microscopic topography of the section of the copper-clad ceramic substrate and the silicon carbide power chip connecting piece prepared by the application example, the porosity of the connecting layer is measured to be 5%.
As shown in fig. 1, the interconnection structure of the copper-clad ceramic substrate and the IGBT module power chip prepared in this embodiment includes, from bottom to top, a copper-clad ceramic substrate 6, an electroless silver coating layer 3, a connection layer, and a silicon carbide power chip 1 in the IGBT module, the connection layer uses a nano cubic silver solder paste 2, and the copper-clad ceramic substrate 6 includes a copper layer 4 on the bottom copper-clad ceramic substrate and a bottom copper-clad ceramic substrate ceramic layer 5.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
Claims (7)
1. A nano cubic silver solder paste is characterized in that: the silver nanoparticle is formed by mixing nano cubic silver particles with uniform size and an organic solvent, wherein the nano cubic silver particles are cubic, and the particle size of the nano cubic silver particles is 20-200 nm;
in the welding process, a superlattice array structure is formed by utilizing the self-assembly performance of the nano cubic silver particles, so that the nano cubic silver particles are tightly arranged, and the porosity of a welding connection layer is reduced;
the nano cubic silver particles with the particle size of 20 nm-200 nm are prepared by a polyol thermal reduction method, and the method comprises the following specific steps:
(1) dissolving a catalyst in a solvent to obtain a first reaction solution;
(2) dissolving a ligand in a solvent to obtain a second reaction solution;
(3) dissolving a protective agent in a solvent to obtain a third reaction solution;
(4) dissolving a silver source precursor in a solvent to obtain a fourth reaction solution;
(5) heating ethylene glycol to 155-165 ℃, keeping the temperature for 1-1.5 hours, then respectively adding a first reaction liquid, a second reaction liquid, a third reaction liquid and a fourth reaction liquid, reacting for 1-2 hours at the temperature of 155-165 ℃ under the stirring of a magnetic stirrer, and obtaining a suspension of high-concentration cubic nano silver particles and ethylene glycol after the reaction is finished;
(6) carrying out solid phase separation on the suspension of the nano cubic silver particles and the ethylene glycol to obtain a solid phase product;
(7) sequentially washing and drying the solid-phase product to obtain the nano cubic silver particles;
wherein the catalyst is selected from any one of sodium sulfide and sodium hydrosulfide;
the ligand is selected from one of hydrochloric acid, sodium chloride and potassium chloride;
the solvent is selected from any one of deionized water, ethanol and glycol;
the silver source precursor is selected from any one of silver nitrate, silver acetate and silver carbonate;
the concentration of the catalyst is 2 mmol/L-6 mmol/L;
the concentration of the ligand is 2 mmol/L-3 mmol/L;
the concentration of the protective agent is 20 mg/mL-40 mg/mL;
the concentration of the silver source precursor is 270 mmol/L-300 mmol/L.
2. The nano cubic silver solder paste according to claim 1, wherein: the organic solvent is selected from one or more of ethylene glycol, terpineol, alpha-terpineol, beta-terpineol, gamma-terpineol, delta-terpineol, glycerol, diethylene glycol and triethylene glycol.
3. The nano cubic silver solder paste according to claim 1, wherein: the mass ratio of the nano cubic silver particles to the organic solvent is (5-12): 1.
4. the utility model provides a copper-clad ceramic substrate and IGBT module power chip's interconnect structure which characterized in that: the nano cubic silver soldering paste is prepared by connecting the nano cubic silver soldering paste as defined in any one of claims 1 to 3.
5. The copper-clad ceramic substrate and IGBT module power chip interconnection structure of claim 4, wherein: the chip interconnection structure comprises a copper-clad ceramic substrate, a chemical silver coating layer, a connecting layer and a silicon carbide power chip in an IGBT module from bottom to top, wherein the connecting layer uses nano cubic silver soldering paste.
6. The method for welding the copper-clad ceramic substrate and the interconnection structure of the IGBT module power chip according to claim 5, characterized by comprising the steps of:
(1) coating the nano cubic silver soldering paste on a silver-plated copper-clad ceramic substrate in a screen printing mode to obtain printing soldering paste, wherein the nano cubic silver particles form a superlattice array structure through self-assembly performance in the process;
(2) placing an IGBT power chip on the surface of the IGBT power chip to form an interconnection structure;
(3) and (3) placing the interconnection structure in a heating furnace for welding, wherein the heating temperature is 150-300 ℃, the heat preservation time is 20-60 min, and the pressing pressure is 0Mpa, so that the interconnection of the copper-clad ceramic substrate and the silicon carbide power chip is realized.
7. The method for welding the copper-clad ceramic substrate and the interconnection structure of the IGBT module power chip according to claim 6, characterized in that: the silver plating mode of the copper-clad ceramic substrate in the step (1) is selected from one of chemical silver plating and electric silver plating.
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