CN115213514B - Copper core intermetallic compound welding spot and preparation method thereof - Google Patents
Copper core intermetallic compound welding spot and preparation method thereof Download PDFInfo
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- CN115213514B CN115213514B CN202210910966.3A CN202210910966A CN115213514B CN 115213514 B CN115213514 B CN 115213514B CN 202210910966 A CN202210910966 A CN 202210910966A CN 115213514 B CN115213514 B CN 115213514B
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- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical group [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 title claims abstract description 106
- 229910000765 intermetallic Inorganic materials 0.000 title claims abstract description 55
- 238000003466 welding Methods 0.000 title claims abstract description 42
- 238000002360 preparation method Methods 0.000 title claims abstract description 11
- 229910000679 solder Inorganic materials 0.000 claims abstract description 75
- 229910052751 metal Inorganic materials 0.000 claims abstract description 73
- 239000002184 metal Substances 0.000 claims abstract description 73
- 239000010949 copper Substances 0.000 claims abstract description 36
- 238000005476 soldering Methods 0.000 claims abstract description 32
- 229910052802 copper Inorganic materials 0.000 claims abstract description 25
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 20
- 239000000956 alloy Substances 0.000 claims abstract description 20
- 238000000034 method Methods 0.000 claims abstract description 10
- 239000000758 substrate Substances 0.000 claims description 39
- 239000011248 coating agent Substances 0.000 claims description 14
- 238000000576 coating method Methods 0.000 claims description 14
- 230000004907 flux Effects 0.000 claims description 14
- 229910052718 tin Inorganic materials 0.000 claims description 14
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims description 10
- 238000005219 brazing Methods 0.000 claims description 10
- 239000000945 filler Substances 0.000 claims description 10
- 238000002844 melting Methods 0.000 claims description 5
- 230000008018 melting Effects 0.000 claims description 5
- 238000004519 manufacturing process Methods 0.000 claims description 4
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 4
- 150000001875 compounds Chemical class 0.000 claims description 2
- 238000001816 cooling Methods 0.000 claims description 2
- 239000011258 core-shell material Substances 0.000 claims description 2
- 229910052759 nickel Inorganic materials 0.000 claims description 2
- 229910052709 silver Inorganic materials 0.000 claims description 2
- 230000008569 process Effects 0.000 abstract description 5
- 230000008646 thermal stress Effects 0.000 abstract description 4
- 238000012536 packaging technology Methods 0.000 abstract description 3
- UQMRAFJOBWOFNS-UHFFFAOYSA-N butyl 2-(2,4-dichlorophenoxy)acetate Chemical compound CCCCOC(=O)COC1=CC=C(Cl)C=C1Cl UQMRAFJOBWOFNS-UHFFFAOYSA-N 0.000 description 15
- 238000009713 electroplating Methods 0.000 description 10
- 238000010438 heat treatment Methods 0.000 description 8
- 238000006243 chemical reaction Methods 0.000 description 6
- 238000004377 microelectronic Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 238000004321 preservation Methods 0.000 description 3
- 238000004021 metal welding Methods 0.000 description 2
- 238000004806 packaging method and process Methods 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 239000007943 implant Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 230000005476 size effect Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
Classifications
-
- 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
-
- 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
- B23K3/08—Auxiliary devices therefor
- B23K3/082—Flux dispensers; Apparatus for applying flux
-
- 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
- B23K35/02—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape
- B23K35/0222—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape for use in soldering, brazing
Abstract
The invention provides a copper core intermetallic compound welding spot and a preparation method thereof, wherein the copper or copper-base alloy core is arranged in the copper core intermetallic compound welding spot, the intermetallic compound shell layer covering the surface of the core is arranged outside the copper or copper-base alloy core, and the ratio of the thickness of the intermetallic compound shell layer in the copper core intermetallic compound welding spot to the diameter of the copper or copper-base alloy core is less than 1/4. The preparation method comprises the steps of implanting copper core solder balls on the first metal bonding pads, reflowing to form copper core solder bumps, aligning and contacting the second metal bonding pads with the copper core solder bumps, and applying a reflow soldering process until the solder is completely converted into an intermetallic compound with a certain thickness. The invention has simple preparation process, low cost, excellent conductivity and high strength, has good compatibility with the prior packaging technology, can realize the technical difficulty of low-temperature connection and high-temperature service, reduces the thermal stress in the reflow soldering process, and improves the reliability and service performance of welding spots.
Description
Technical Field
The invention relates to the technical field of microelectronic package manufacturing, in particular to a copper core intermetallic compound welding spot and a preparation method thereof.
Background
The third generation wide bandgap semiconductor represented by SiC and GaN has excellent performances of high breakdown electric field, high saturated electron drift velocity, strong thermal conductivity, high thermal stability and the like, and can be suitable for application scenes such as high frequency, high temperature and the like. The third-generation semiconductor power device manufactured at present can stably work at the temperature of 600 ℃ at maximum, but the solder joint of the tin-based solder commonly used in the electronic package at present cannot be used at such high temperature. If solder joints are prepared by using other systems with too high melting points, the high temperature during reflow will not only damage the circuit board and other components, but also generate large thermal stresses, which is extremely detrimental to the performance and reliability of the overall packaging system.
In the prior art, the solder welding spot is generally converted into an all-intermetallic compound welding spot so as to realize low-temperature interconnection and high-temperature service. Namely, the transition of the solder to intermetallic compounds is accelerated by introducing external fields such as temperature gradients, currents and the like, but when the height of a welding spot reaches hundreds of micrometers, the transition time is still long, even more than 1 hour, the efficiency is low and the element is damaged.
According to research, the traditional copper core solder ball can effectively solve the technical problems of collapse, displacement and the like, but a solder layer wrapped outside the copper core is reserved in an interface reaction, so that a welding spot taking the copper core and the solder as a main connecting medium cannot bear the high temperature above the melting point of the solder, and the problems cannot be well solved.
Therefore, how to realize the interconnection of components at a lower reflow soldering temperature, and the obtained solder joint can bear a higher service temperature becomes a difficult problem in the field of microelectronic package manufacturing.
Disclosure of Invention
According to the technical problems that the circuit board is easy to be damaged at high temperature in the reflow soldering process, the packaging reliability is poor and the like, the copper core intermetallic compound welding spot and the preparation method are provided. The invention replaces the traditional solder ball by the copper core solder ball, so that the solder joint after reflow soldering is mainly composed of the copper core and the intermetallic compound shell, and the purpose of high-temperature service through low-temperature connection can be rapidly realized. The copper core referred to by the invention is copper or copper-based alloy core (hereinafter collectively referred to as copper core), based on the principle of size effect, namely, the thinner the solder layer is, the faster the solder is converted into intermetallic compound, the thinner solder layer in the copper core solder ball structure can be quickly converted into intermetallic compound, and the reflow soldering time is greatly shortened. The whole process of the invention has good compatibility with the existing microelectronic packaging technology.
The invention adopts the following technical means:
a copper core intermetallic compound welding spot, characterized in that the inside of a connecting medium between a first metal welding disc used for connecting a first substrate and a second metal welding disc of a second substrate is a copper or copper-base alloy core, the outside of the connecting medium is an intermetallic compound shell layer coated on the surface of the core, and the ratio of the thickness of the intermetallic compound shell layer to the diameter of the copper or copper-base alloy core in the copper core intermetallic compound welding spot is less than 1/4.
The invention also discloses a preparation method of the copper core intermetallic compound welding spot, which is characterized by comprising the following steps:
step one: providing a first substrate, preparing at least one first metal bonding pad on the first substrate, coating soldering flux on the first metal bonding pad, then implanting copper core solder balls, and forming copper core solder bumps through reflow soldering; providing a second substrate, and preparing at least one second metal bonding pad on the second substrate;
the copper core solder ball is a core-shell structure ball taking copper or copper base alloy ball as a core and taking solder as a shell, and the metal ball comprises pure Cu or Cu-base alloy consisting of Cu and one or more elements of Ni, zn, sn and rare earth elements; the solder comprises pure Sn or Sn-based alloy composed of Sn and one or more of Ag, cu, au, in, bi, zn, ni, ga and rare earth elements;
step two: coating soldering flux on the second metal bonding pad, aligning the copper core solder bumps on the first metal bonding pad with the second metal bonding pad one by one, and placing the copper core solder bumps in contact with the second metal bonding pad to form a combination body;
step three: carrying out reflow soldering on the combination body formed in the second step until all the brazing filler metal between the copper ball and the metal bonding pad is converted into intermetallic compound and has a certain thickness, and cooling to obtain a copper core intermetallic compound bonding point;
the first and second metal pads are left after reflow soldering.
Further, the first substrate and the second substrate are chips, package substrates or printed circuit boards.
Further, the thickness of the intermetallic compound satisfies an empirical formula: t=kt n Wherein T is the thickness of the intermetallic compound, K is the growth coefficient of the compound, the value is between 0.5 and 10, T is the reflow soldering time, n is the time coefficient, and the time coefficient value is usually between 0.2 and 1, preferably 0.4.
Further, in the third step, when the intermetallic compound connects the copper core and the bonding pad, the reflow soldering is completed, and the intermetallic compound bonding spot of the copper core is formed. The thickness of the intermetallic compound layer in the formed copper core intermetallic compound welding spot is less than 50 micrometers.
Further, in the third step, the peak temperature of reflow soldering is at least 10 ℃ higher than the melting temperature of the solder layer in the copper core solder ball.
Further, in the third step, ultrasonic, current and temperature fields are introduced during reflow soldering to accelerate the transformation of the solder into intermetallic compounds.
Compared with the prior art, the copper core intermetallic compound welding spot provided by the invention has the advantages that the copper or copper base alloy core is arranged inside, and the intermetallic compound shell layer coated on the surface of the core is arranged outside, so that the traditional soft solder welding spot is replaced.
And simultaneously, the preparation method of the invention is to implant copper core solder balls on the first metal bonding pads, then reflow to form copper core solder bumps, align and contact the second metal bonding pads with the copper core solder bumps, and apply a reflow process until the solder is completely converted into intermetallic compounds with certain thickness.
The invention has simple preparation process, low cost, excellent conductivity and high strength, can realize interconnection at 30-280 ℃ and high-temperature service at 600 ℃ or below, simultaneously reduces thermal stress caused by reflow soldering, can realize low-temperature connection and high-temperature service, has good compatibility with the prior packaging technology, and improves the reliability and service performance of welding spots.
For the reasons, the invention can be widely popularized in the technical field of microelectronic package manufacturing.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings may be obtained according to the drawings without inventive effort to a person skilled in the art.
FIG. 1 is a schematic diagram of a first metal pad/copper core solder bump formed in step one of the present invention;
FIG. 2 is a schematic diagram of a combination formed in step two of the present invention;
FIG. 3 is a schematic diagram of a copper intermetallic compound solder joint formed in step three of the present invention;
FIG. 4 is a back-scattered image of a copper core intermetallic bond joint interface structure formed in accordance with the present invention;
in the figure: 11. a first substrate; 21. a first metal pad; 12. a second substrate; 22. a second metal pad; 30. a copper core; 40. a solder shell layer; 50. an intermetallic compound layer.
Detailed Description
It should be noted that, without conflict, the embodiments of the present invention and features of the embodiments may be combined with each other. The invention will be described in detail below with reference to the drawings in connection with embodiments.
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. The following description of at least one exemplary embodiment is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the present invention. As used herein, the singular is also intended to include the plural unless the context clearly indicates otherwise, and furthermore, it is to be understood that the terms "comprises" and/or "comprising" when used in this specification are taken to specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof.
The invention is further described below with reference to fig. 1, 2, 3 and 4.
Example 1
Step one: providing a first substrate 11, and electroplating and preparing an array of 20×30 Cu first metal pads 21 with thickness of 30 μm and diameter of 200 μm on the substrate; providing 600 copper core 30 pure tin solder shell 40 balls, wherein the diameter of the copper core balls 30 is 300 mu m, and the thickness of the pure tin solder shell 40 is 20 mu m; after coating soldering flux on the first metal bonding pad, implanting copper core solder balls, and preparing copper core welding spots by reflow for 30s at 250 ℃ as shown in figure 1; providing a second substrate 12, and electroplating on the substrate to prepare an array of 20×30 Cu second metal pads 22 with thickness of 30 μm and diameter of 200 μm;
step two: coating flux on the surface of the second metal pad 22, aligning the copper core welding spots with the second metal pad 22 one by one and placing the copper core welding spots in contact with the second metal pad 22 to form a combination body, as shown in fig. 2;
step three: and (3) heating the assembly formed in the second step to 270 ℃ for reflow soldering, connecting bonding pads at two sides by using a melted pure Sn brazing filler metal shell 40 in the heating and heat preservation stage, performing interface reaction with the first bonding pad 21 and the second bonding pad 22, and almost completely converting the bonding pads into intermetallic compounds after 30min to obtain copper core full-intermetallic compound welding spots, wherein the structure is shown in figure 3, and the copper core/bonding pad interface picture is shown in figure 4.
The melting point of the generated copper core full intermetallic compound welding spot is higher than 400 ℃, and the strength is higher than that of pure tin. Therefore, the structure of the micro welding spots can well meet the requirement of high-temperature service of low-temperature connection, and the service life of the micro welding spots or devices with the material structures is prolonged.
Example 2
Step one: providing a first substrate 11, and electroplating and preparing an array of 20×30 Cu first metal pads 21 with a thickness of 20 μm and a diameter of 50 μm on the substrate; providing 600 copper core 30SAC305 solder shell 40 balls, wherein the diameter of the copper core ball 30 is 100 mu m, and the thickness of the SAC305 solder shell 40 is 10 mu m; after coating soldering flux on the first metal pad 21, implanting copper core solder balls, and preparing copper core solder joints by reflow for 30s at 250 ℃ as shown in fig. 1; providing a second substrate 12, and electroplating on the substrate to prepare an array of 20×30 Cu second metal pads 22 with a thickness of 20 μm and a diameter of 50 μm;
step two: coating flux on the surface of the second metal pad 22, aligning the copper core welding spots with the second metal pad 22 one by one and placing the copper core welding spots in contact with the second metal pad 22 to form a combination body, as shown in fig. 2;
step three: and (3) heating the assembly formed in the second step to 270 ℃ for reflow soldering, introducing an ultrasonic external field, connecting bonding pads at two sides by using a melted solder shell 40 in the heating and heat-preserving stages, performing interface reaction with the first bonding pad 21 and the second bonding pad 22, and almost completely converting the bonding pads into intermetallic compounds after 10min to prepare copper core full intermetallic compound welding spots, wherein the structure of the copper core full intermetallic compound welding spots is shown in figure 3.
The improvement of the introduction of an external field such as ultrasonic can accelerate the conversion of the solder to intermetallic compounds and shorten the reflow soldering time.
Example 3
Step one: providing a first substrate 11, and electroplating and preparing an array of 20×30 Cu first metal pads 21 with thickness of 30 μm and diameter of 100 μm on the substrate; providing 600 copper core 30Sn58Bi shell 40 spheres, wherein the diameter of the copper core sphere 30 is 200 mu m, and the thickness of the Sn58Bi solder shell 40 is 20 mu m; after coating soldering flux on the first metal pad 21, implanting copper core solder balls, and preparing copper core solder joints by reflow for 30s at 150 ℃ as shown in fig. 1; providing a second substrate 12, and electroplating on the substrate to prepare an array of 20×30 Cu second metal pads 22 with thickness of 30 μm and diameter of 100 μm;
step two: coating flux on the surface of the second metal pad 22, aligning the copper core welding spots with the second metal pad 22 one by one and placing the copper core welding spots in contact with the second metal pad 22 to form a combination body, as shown in fig. 2;
step three: and (3) heating the assembly formed in the second step to 180 ℃ for reflow soldering, and connecting bonding pads at two sides by using a molten Sn58Bi brazing filler metal shell 40 in a heating and heat preservation stage, so that interface reaction is carried out between the bonding pads and the first bonding pad 21 and the second bonding pad 22, and Sn is almost completely converted into intermetallic compounds after 40min, so that a copper core full intermetallic compound welding spot is prepared, wherein the structure of the copper core full intermetallic compound welding spot is shown in figure 3.
The use of low temperature solder as the solder shell 40 can reduce the reflow temperature, thereby reducing the thermal stress that is generated.
Example 4
Step one: providing a first substrate 11, and electroplating and preparing an array of 20×30 Cu first metal pads 21 with a thickness of 20 μm and a diameter of 50 μm on the substrate; providing 600 copper core 30SAC305 solder shell 40 balls, wherein the diameter of the copper core ball 30 is 100 mu m, and the thickness of the SAC305 solder shell 40 is 10 mu m; after coating soldering flux on the first metal pad 21, implanting copper core solder balls, and preparing copper core solder joints by reflow for 30s at 250 ℃ as shown in fig. 1; providing a second substrate 12, and electroplating on the substrate to prepare an array of 20×30 Cu second metal pads 22 with a thickness of 20 μm and a diameter of 50 μm;
step two: coating flux on the surface of the second metal pad 22, aligning the copper core welding spots with the second metal pad 22 one by one and placing the copper core welding spots in contact with the second metal pad 22 to form a combination body, as shown in fig. 2;
step three: and (3) setting the first metal bonding pad in the combination in the second step as a hot end, enabling the temperature of the second metal bonding pad to be lower than that of the first metal matrix, and further forming a temperature gradient of 500 ℃/cm in the molten solder, wherein the average temperature is 270 ℃. And (3) carrying out reflow under the assistance of a temperature gradient, wherein the brazing filler metal layer is gradually and completely consumed, and an intermetallic compound welding spot is generated.
Example 5
Step one: providing a first substrate 11, and electroplating and preparing an array of 20×30 Cu first metal pads 21 with thickness of 30 μm and diameter of 100 μm on the substrate; providing 600 pure tin solder shell 40 balls of Cu-5Ni alloy cores 30, wherein the diameter of the Cu-5Ni alloy core balls 30 is 200 mu m, and the thickness of the pure tin solder shell 40 is 20 mu m; after coating soldering flux on the first metal pad 21, implanting copper core solder balls, and preparing copper core solder joints by reflow for 30s at 250 ℃ as shown in fig. 1; providing a second substrate 12, and electroplating on the substrate to prepare an array of 20×30 Cu second metal pads 22 with thickness of 30 μm and diameter of 100 μm;
step two: coating flux on the surface of the second metal pad 22, aligning the copper core welding spots with the second metal pad 22 one by one and placing the copper core welding spots in contact with the second metal pad 22 to form a combination body, as shown in fig. 2;
step three: and (3) heating the assembly formed in the second step to 270 ℃ for reflow soldering, and connecting bonding pads at two sides by using a melted pure Sn brazing filler metal shell 40 in the heating and heat preservation stages, performing interface reaction with the first metal bonding pad 21 and the second metal bonding pad 22, and almost completely converting the bonding pads into intermetallic compounds after 20 minutes to prepare the Cu-5Ni nuclear full intermetallic compound welding spot.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.
Claims (6)
1. The preparation method of the copper core intermetallic compound welding spot is characterized by comprising the following steps of:
step one: providing a first substrate, preparing at least one first metal bonding pad on the first substrate, coating soldering flux on the first metal bonding pad, then implanting copper core solder balls, and forming copper core solder bumps through reflow soldering; providing a second substrate, and preparing at least one second metal bonding pad on the second substrate;
the copper core solder ball is a core-shell structure ball taking copper or copper-base alloy ball as a core and taking solder as a shell, and the copper or copper-base alloy ball comprises pure Cu or Cu-base alloy composed of Cu and one or more elements of Ni, zn, sn and rare earth elements; the solder comprises pure Sn or Sn-based alloy composed of Sn and one or more of Ag, cu, au, in, bi, zn, ni, ga and rare earth elements;
step two: coating soldering flux on the second metal bonding pad, aligning the copper core solder bumps on the first metal bonding pad with the second metal bonding pad one by one, and placing the copper core solder bumps in contact with the second metal bonding pad to form a combination body;
step three: carrying out reflow soldering on the combination body formed in the second step until all brazing filler metal between the copper or copper-base alloy balls and the metal bonding pads is converted into intermetallic compounds, and cooling to obtain copper core intermetallic compound welding spots;
the first and second metal pads are left after reflow soldering;
in particular, the method comprises the steps of,
the solder is pure tin, the diameter of copper core sphere is 300 mu m, the thickness of the shell layer of the pure tin solder is 20 mu m, or,
the brazing filler metal is SAC305, the diameter of the copper core sphere is 100 mu m, the thickness of the brazing filler metal shell layer of SAC305 is 10 mu m, or,
the solder is Sn58Bi, the diameter of copper core balls is 200 mu m, the thickness of a Sn58Bi solder shell layer is 20 mu m, or,
the brazing filler metal is pure tin, the diameter of the Cu-5Ni alloy core sphere is 200 mu m, and the thickness of the pure tin brazing filler metal shell layer is 20 mu m.
2. The method of claim 1, wherein the first and second substrates are chips, package substrates, or printed circuit boards.
3. The method according to claim 1, wherein the thickness of the intermetallic compound satisfies an empirical formula: t=kt n Wherein T is the thickness of the intermetallic compound, K is the growth coefficient of the compound, T is the reflow soldering time, and n is the time coefficient.
4. The method of claim 1, wherein in the third step, the thickness of the intermetallic layer in the copper core intermetallic spot is less than 50 μm.
5. The method of claim 1, wherein in the third step, the peak temperature of the reflow is at least 10 ℃ higher than the melting temperature of the solder layer in the copper core solder ball.
6. The method of manufacturing as claimed in claim 1, wherein the inner part of the connection medium between the first metal pad of the first substrate and the second metal pad of the second substrate is copper or copper-based alloy core, the outer part is intermetallic compound shell layer coated on the surface of the core, and the ratio of the thickness of the intermetallic compound shell layer to the diameter of the copper or copper-based alloy core in the intermetallic compound pad of the copper core is less than 1/4.
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| Title |
|---|
| Interfacial Reactions and Mechanical Properties of Ball-Grid-Array Solder Joints Using Cu-Cored Solder Balls;CHIH-MING CHEN等;Journal of ELECTRONIC MATERIALS;第35卷(第11期);第1938页左栏倒数第1段-第1940页 * |
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|---|---|
| CN115213514A (en) | 2022-10-21 |
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