CN116652450A - Epoxy resin composite Sn-Bi-Sb lead-free solder paste and preparation method thereof - Google Patents
Epoxy resin composite Sn-Bi-Sb lead-free solder paste and preparation method thereof Download PDFInfo
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- CN116652450A CN116652450A CN202310881222.8A CN202310881222A CN116652450A CN 116652450 A CN116652450 A CN 116652450A CN 202310881222 A CN202310881222 A CN 202310881222A CN 116652450 A CN116652450 A CN 116652450A
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- 229910000679 solder Inorganic materials 0.000 title claims abstract description 105
- 239000003822 epoxy resin Substances 0.000 title claims abstract description 94
- 229920000647 polyepoxide Polymers 0.000 title claims abstract description 94
- 239000002131 composite material Substances 0.000 title claims abstract description 48
- 238000002360 preparation method Methods 0.000 title abstract description 7
- 238000005476 soldering Methods 0.000 claims abstract description 94
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 48
- 239000000203 mixture Substances 0.000 claims abstract description 29
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims description 38
- IISBACLAFKSPIT-UHFFFAOYSA-N bisphenol A Chemical compound C=1C=C(O)C=CC=1C(C)(C)C1=CC=C(O)C=C1 IISBACLAFKSPIT-UHFFFAOYSA-N 0.000 claims description 36
- 239000000843 powder Substances 0.000 claims description 28
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 20
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims description 20
- 229910001245 Sb alloy Inorganic materials 0.000 claims description 20
- 229910045601 alloy Inorganic materials 0.000 claims description 19
- 239000000956 alloy Substances 0.000 claims description 19
- YCIMNLLNPGFGHC-UHFFFAOYSA-N catechol Chemical compound OC1=CC=CC=C1O YCIMNLLNPGFGHC-UHFFFAOYSA-N 0.000 claims description 18
- GHMLBKRAJCXXBS-UHFFFAOYSA-N resorcinol Chemical compound OC1=CC=CC(O)=C1 GHMLBKRAJCXXBS-UHFFFAOYSA-N 0.000 claims description 18
- AHDSRXYHVZECER-UHFFFAOYSA-N 2,4,6-tris[(dimethylamino)methyl]phenol Chemical compound CN(C)CC1=CC(CN(C)C)=C(O)C(CN(C)C)=C1 AHDSRXYHVZECER-UHFFFAOYSA-N 0.000 claims description 16
- 238000000034 method Methods 0.000 claims description 15
- 239000002245 particle Substances 0.000 claims description 15
- 230000004907 flux Effects 0.000 claims description 10
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 claims description 10
- 238000003756 stirring Methods 0.000 claims description 10
- LGRFSURHDFAFJT-UHFFFAOYSA-N Phthalic anhydride Natural products C1=CC=C2C(=O)OC(=O)C2=C1 LGRFSURHDFAFJT-UHFFFAOYSA-N 0.000 claims description 9
- JHIWVOJDXOSYLW-UHFFFAOYSA-N butyl 2,2-difluorocyclopropane-1-carboxylate Chemical compound CCCCOC(=O)C1CC1(F)F JHIWVOJDXOSYLW-UHFFFAOYSA-N 0.000 claims description 9
- FPYJFEHAWHCUMM-UHFFFAOYSA-N maleic anhydride Chemical compound O=C1OC(=O)C=C1 FPYJFEHAWHCUMM-UHFFFAOYSA-N 0.000 claims description 9
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 6
- 238000003723 Smelting Methods 0.000 claims description 6
- 238000001272 pressureless sintering Methods 0.000 claims description 6
- 239000002994 raw material Substances 0.000 claims description 6
- 238000002156 mixing Methods 0.000 claims description 5
- 238000005457 optimization Methods 0.000 claims description 4
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims description 3
- 238000012387 aerosolization Methods 0.000 claims description 3
- WATWJIUSRGPENY-UHFFFAOYSA-N antimony atom Chemical compound [Sb] WATWJIUSRGPENY-UHFFFAOYSA-N 0.000 claims description 3
- 229910052786 argon Inorganic materials 0.000 claims description 3
- 229910052797 bismuth Inorganic materials 0.000 claims description 3
- JCXGWMGPZLAOME-UHFFFAOYSA-N bismuth atom Chemical compound [Bi] JCXGWMGPZLAOME-UHFFFAOYSA-N 0.000 claims description 3
- 238000005266 casting Methods 0.000 claims description 3
- 239000012535 impurity Substances 0.000 claims description 3
- 239000011261 inert gas Substances 0.000 claims description 3
- 238000012216 screening Methods 0.000 claims description 3
- 238000002844 melting Methods 0.000 claims description 2
- 238000003892 spreading Methods 0.000 abstract description 10
- 230000007480 spreading Effects 0.000 abstract description 10
- 238000009736 wetting Methods 0.000 abstract description 10
- 239000000463 material Substances 0.000 abstract description 5
- 238000005219 brazing Methods 0.000 abstract description 3
- 239000007769 metal material Substances 0.000 abstract description 2
- 238000005272 metallurgy Methods 0.000 abstract 1
- 238000012360 testing method Methods 0.000 description 31
- 238000003466 welding Methods 0.000 description 26
- 238000010008 shearing Methods 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 11
- 230000002787 reinforcement Effects 0.000 description 10
- 229910020830 Sn-Bi Inorganic materials 0.000 description 7
- 229910018728 Sn—Bi Inorganic materials 0.000 description 7
- 230000006872 improvement Effects 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- 238000010998 test method Methods 0.000 description 5
- 229910017802 Sb—Ag Inorganic materials 0.000 description 4
- 239000011247 coating layer Substances 0.000 description 4
- 238000004321 preservation Methods 0.000 description 4
- 229910002059 quaternary alloy Inorganic materials 0.000 description 4
- 229910017944 Ag—Cu Inorganic materials 0.000 description 3
- 239000004593 Epoxy Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000000565 sealant Substances 0.000 description 3
- 239000000758 substrate Substances 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 230000001133 acceleration Effects 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 230000005496 eutectics Effects 0.000 description 2
- 239000010410 layer Substances 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000004806 packaging method and process Methods 0.000 description 2
- 230000003014 reinforcing effect Effects 0.000 description 2
- 229910052718 tin Inorganic materials 0.000 description 2
- 238000005275 alloying Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000002041 carbon nanotube Substances 0.000 description 1
- 229910021393 carbon nanotube Inorganic materials 0.000 description 1
- 230000008859 change Effects 0.000 description 1
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- 238000001816 cooling Methods 0.000 description 1
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- 238000002474 experimental method Methods 0.000 description 1
- 229910021389 graphene Inorganic materials 0.000 description 1
- 238000009863 impact test Methods 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
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- 231100000053 low toxicity Toxicity 0.000 description 1
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- 239000002923 metal particle Substances 0.000 description 1
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- 239000002105 nanoparticle Substances 0.000 description 1
- 231100000252 nontoxic Toxicity 0.000 description 1
- 230000003000 nontoxic effect Effects 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
Classifications
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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
-
- 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
- B23K35/22—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
- B23K35/264—Bi 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
- B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
- B23K35/36—Selection of non-metallic compositions, e.g. coatings, fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest
- B23K35/3612—Selection of non-metallic compositions, e.g. coatings, fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest with organic compounds as principal constituents
- B23K35/3613—Polymers, e.g. resins
-
- 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
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Epoxy Resins (AREA)
Abstract
An epoxy resin composite Sn-Bi-Sb lead-free soldering paste and a preparation method thereof belong to the brazing materials in the metal material and metallurgy fields. The composition of the solder paste comprises 3 to 6 mass percent of epoxy resin, 1.5 to 5.0 mass percent of curing agent and accelerator, and the balance of commercial Sn-Bi-Sb solder paste. Wherein the mixture of the epoxy resin, the curing agent and the accelerator comprises the components in percentage by mass of the composition of the epoxy resin, the curing agent and the accelerator=100:70-85:4-9. The application has good wetting spreading performance, can obviously improve the shear strength and the drop resistance of the soldered joint, and can be used for reflow soldering of products with specific requirements on temperature and drop resistance in the electronic industry.
Description
Technical Field
The application relates to an epoxy resin composite Sn-Bi-Sb lead-free solder paste and a preparation method thereof, belonging to the brazing materials in the metal material and metallurgical fields. The lead-free solder is mainly used for assembling and packaging components in the electronic industry, and has good brazing performance and good welding spot mechanical property.
Background
With the demands of the electronic industry for low-temperature welding, the SnBi low-temperature lead-free solder is increasingly widely applied in the electronic field. The Sn-58Bi eutectic solder is used as the first-choice low-temperature solder, so that the warping problem of a printed circuit board and an electronic component in a reflow soldering process can be reduced, the energy emission can be reduced, the production cost is reduced, and the solder has been widely applied to certain products with specific requirements on temperature. However, since the Sn-58Bi eutectic solder has a high Bi element content, the ductility, strength, temperature cycle reliability and mechanical impact reliability of the solder joint are deteriorated, and the application field is limited.
At present, two methods for improving the performance of the lead-free solder at home and abroad are mainly adopted, one method is alloying, the existing Sn-based lead-free solder is taken as a matrix, and the performance of the solder is improved by adding one or more trace alloy elements; the other method is particle reinforcement, namely, the composite lead-free solder is prepared by internally generating (such as in-situ synthesis) or directly adding second-phase particles (such as adding various nano particles, carbon nano tubes, graphene and the like) in Sn-based solder, so that the performance of the solder is improved.
The inventor finds out through literature search that 'a low-temperature composite soldering paste and a preparation method and a use method thereof' of patent application number 201310002577.1, reports a low-temperature composite soldering paste and a preparation method and a use method thereof, wherein the low-temperature composite soldering paste comprises a low-temperature solder matrix, a flux and metal particles, and is used for an electronic device to have a stable effect in a welding process, so that the high-precision requirement of a welding seam is ensured; the application number 201811229313.9 of the epoxy resin composite Sn-Bi lead-free solder paste reports an epoxy resin composite Sn-Bi lead-free solder paste, which is characterized by comprising 3-8% of epoxy resin, a curing agent and an accelerator (the ratio of the epoxy resin to the curing agent to the accelerator=100:8-30:1-10) in percentage by mass, and the balance of the commercially available Sn-Bi solder paste. The composite Sn-Bi lead-free solder paste has good wetting and spreading performance, can obviously improve the shear strength of a soldered joint, and can be used for reflow soldering of components in the electronic industry; the application No. 201811230768.2, "a composite Sn-Bi lead-free solder paste containing an epoxy resin," reports a composite Sn-Bi lead-free solder paste containing an epoxy resin. The composite Sn-Bi leadless solder paste can improve the wetting and spreading performance of the solder and can obviously improve the shear strength of the soldered joint.
The application number 202111234886.2 of the epoxy resin composite Sn-Ag-Cu lead-free solder paste reports that the improvement range is 14-26% compared with the strength of a soldering point of the Sn-Ag-Cu lead-free solder paste without the epoxy resin, and the improvement range is 27.19N when the optimal addition amount is 5% (when the total addition amount of the epoxy resin, the curing agent and the accelerator is 5%), the improvement range is 26%, the addition of the epoxy resin is fully described, the shearing strength of the soldering point of the Sn-Ag-Cu lead-free solder paste can be remarkably improved, and the solder paste has no negative effect. However, none of the existing solder references have reported improvement of "drop resistance" of solder joints or electronic devices.
The delivery of the smart phone in 2022 is 2.64 hundred million parts, and the smart phone is almost a necessity for life of people, but is a consumable product, and the damage of the smart phone caused by the mobile phone falling is the most common mode, so one of the main objects of the anti-falling test of the smart phone is the anti-falling property of the soldering joint. In order to improve the dropping resistance and the shock resistance of the electronic device (component), thereby improving the reliability of the electronic device (component), various products at home and abroad adopt "pouring sealant" to protect the electronic device on the PCB, but the application of the pouring sealant is limited. The applicant finds through experiments that the anti-drop property of an electronic device (component) can be obviously improved by adopting an epoxy resin composite lead-free solder welding spot, so that the limitation of application of pouring sealant is overcome.
Disclosure of Invention
The application aims to provide a low-temperature lead-free solder with good wetting and spreading performance, which can remarkably improve the shear strength of soldered joints, in particular the drop resistance of soldered joints.
The task of the present application is accomplished in this way.
The epoxy resin composite Sn-Bi-Sb lead-free soldering paste is characterized by comprising 3 to 6 mass percent of epoxy resin, 1.5 to 5.0 mass percent of a mixture consisting of a curing agent and an accelerator, and the balance of commercially available Sn-Bi-Sb soldering paste. Wherein the mixture of the epoxy resin, the curing agent and the accelerator comprises the components in percentage by mass of the composition of the epoxy resin, the curing agent and the accelerator=100:70-85:4-9. The epoxy resin is a combination of 50% E44 bisphenol A and 50% E51 bisphenol A, the curing agent is a combination of 40% maleic anhydride and 60% phthalic anhydride, and the accelerator is a combination of 30% 2,4, 6-tris (dimethylaminomethyl) phenol (i.e. DMP-30) and 30% catechol and 40% resorcinol.
The preparation method of the epoxy resin composite Sn-Bi-Sb lead-free solder paste is characterized by comprising the following steps of: step 1, using a tin ingot, a bismuth block and an antimony ingot which are sold in the market, proportioning raw materials of various elements according to the requirement, adding a covering agent determined by optimization and screening during smelting, or adopting inert gas for protection to carry out smelting and casting to obtain a Sn-Bi-Sb alloy bar; re-melting the smelted Sn-Bi-Sb alloy, and preparing the Sn-Bi-Sb alloy into alloy powder with the particle diameter of 20-75 mu m by adopting argon protection through an 'aerosolization' powder making device; pb element is used as an impurity element in the raw material, and the total amount (mass percent) is controlled within the range of Pb less than or equal to 0.07 wt%; adding a proper amount of ethanol or glycol into 85-95% by mass of Sn-Bi-Sb alloy powder and the balance of commercial soldering flux, using a high-speed stirrer, and stirring for 10-30 min at a rotating speed of 300-1200 r/min to obtain Sn-Bi-Sb leadless solder paste; mixing 50% of an epoxy resin combination mixture of E44 bisphenol A and 50% of E51 bisphenol A, a curing agent combination mixture of 40% of maleic anhydride and 60% of phthalic anhydride, and an accelerator combination mixture of 30% of 2,4, 6-tris (dimethylaminomethyl) phenol and 30% of catechol and 40% of resorcinol in advance according to the ratio of epoxy resin to curing agent to accelerator=100:70-85:4-9, and uniformly mixing for later use; then, adding a proper amount of ethanol or glycol into a mixture consisting of 3-6% by mass of epoxy resin, a curing agent and an accelerator, 1.5-5.0% by mass of commercial nano silver paste and the balance of the Sn-Bi-Sb leadless solder paste prepared by the method, and stirring for 10-30 min by using a high-speed stirrer at the rotating speed of 300-1200 r/min to obtain the epoxy resin composite Sn-Bi-Sb leadless solder paste; wherein the grain diameter of the nano silver in the commercial nano silver paste is 150 nm-250 nm, and the pressureless sintering temperature is not higher than 220 ℃.
The commercial Sn-Bi-Sb soldering paste comprises 85-95% of Sn-Bi-Sb alloy powder by mass percent and the balance of commercial soldering flux. Wherein Bi element accounts for 57-59% of the alloy powder, sb accounts for 1.2-2.0%, the balance is Sn, and the particle diameter of the alloy powder is 20-75 mu m. The epoxy resin composite Sn-Bi-Sb lead-free soldering paste has good wetting and spreading performance (equivalent to that of the commercially available Sn-Bi-Sb soldering paste, has no negative effect), can remarkably improve the shear strength and the anti-drop property of a soldered joint, and can be used for reflow soldering of products with specific requirements on temperature and anti-drop property in the electronic industry.
According to the technical scheme provided by the application, the epoxy resin, the curing agent and the accelerator are low in price (compared with Sn, bi, sb, ag metal elements, the market price of each kilogram is lower than that of Sn, bi, sb, ag metal), the epoxy resin, the curing agent and the accelerator are nontoxic (extremely low-toxicity) and environment-friendly commercial chemical materials, the total dosage of the epoxy resin, the curing agent and the accelerator is 3-6% of that of the paste solder, the addition amount of the nano silver paste is 1.5-5.0% of that of the paste solder, the wetting and spreading performance of the solder can be improved, and the shear strength and the drop resistance of a soldered joint can be obviously improved.
Drawings
FIG. 1 is a graph showing average values of solder joint shear force for a commercially available Sn-58Bi-1.6Sb solder paste and solder joint shear force for example 1 to example 3, comparative example solder paste;
FIG. 2 shows drop number comparison data when a plate-level drop test specimen fails.
Detailed Description
And preparing the Sn-Bi-Sb lead-free solder by adopting a conventional method. Namely, the tin ingot, the metal bismuth block and the antimony ingot which are sold in the market are used, the raw materials of various elements are proportioned according to the requirement, and a covering agent which is determined by optimization and screening is added during smelting or inert gas is adopted for protection for smelting and casting, so that the Sn-Bi-Sb alloy bar is obtained. And (3) remelting the smelted Sn-Bi-Sb alloy, and preparing the Sn-Bi-Sb alloy into alloy powder with the particle diameter of 20-75 mu m by adopting argon protection through an 'aerosolization' powder making device. The lead (namely Pb) is taken as an ' impurity element ' in the raw material, and the total amount (mass percent) is controlled within the range of Pb less than or equal to 0.07wt.% so as to meet the specification of national standard GB/T20422-2018 ' lead-free solder ' of the people's republic of China (Pb less than or equal to 0.07wt.% is specified in the standard).
And (3) adding a proper amount of ethanol or glycol into 85-95% by mass of Sn-Bi-Sb alloy powder and the balance of commercial soldering Flux (such as ECO Flux 823), and stirring for 10-30 min by using a high-speed stirrer (the rotating speed is 300-1200 r/min), thereby obtaining the Sn-Bi-Sb leadless soldering paste.
And then, the epoxy resin combination mixture of 50% of E44 bisphenol A and 50% of E51 bisphenol A, the curing agent combination mixture of 40% of maleic anhydride and 60% of phthalic anhydride, and the accelerator combination mixture of 30% of 2,4, 6-tris (dimethylaminomethyl) phenol (namely DMP-30) and 30% of catechol and 40% of resorcinol are prepared in advance according to the ratio of epoxy resin to curing agent to accelerator=100:70-85:4-9, and are uniformly mixed for standby (the epoxy resin, the curing agent and the accelerator are prepared into a mixture). Then, mixing 3-6% of epoxy resin, a curing agent and an accelerator, 1.5-5.0% of commercial nano silver paste and the balance of the Sn-Bi-Sb leadless solder paste, adding a proper amount of ethanol or glycol, and stirring for 10-30 min by using a high-speed stirrer (the rotating speed is 300-1200 r/min), thus obtaining the epoxy resin composite Sn-Bi-Sb leadless solder paste.
Please refer to fig. 1. The graph shows the average solder joint shear force data for a commercially available Sn-58Bi-1.6Sb solder paste versus 4 example solder pastes. FIG. 1 shows that when three chip resistors (R0603, R0805 and R1210 chip resistors) are used for comparison test, the shear strength (namely, shear force) of the welding spots obtained in the example is improved by more than 80% compared with that of the commercially available Sn-58Bi-1.6Sb soldering paste. The cured epoxy resin forms a thin and uniform coating layer on the surface of the welding spot, so that the welding spot has the function of physical reinforcement (or mechanical reinforcement); the nano silver has a metallurgical reaction with Sn-58Bi-1.6Sb alloy in Sn-58Bi-1.6Sb soldering paste in the soldering process, and nano Ag particles and Sn-58Bi-1.6Sb form Sn-Bi-Sb-Ag quaternary alloy, so that the shearing strength of the soldering point is further improved. The "comparative example" without the addition of the nano silver paste was significantly lower than examples 1 to 3, although the shear force was higher than that of the commercially available Sn-58Bi-1.6Sb solder joint, indicating that the addition of the nano silver paste did help to improve the shear strength of the epoxy resin composite Sn-Bi-Sb lead-free solder paste.
The board-level drop impact test is often applied to the initial development stage of a test piece of a certain product, or provides a certain data support for the service life of the product by monitoring the performance of the test process aiming at a certain specific packaging form or a certain specific connecting material. According to the board-level drop test method provided by the application, the test is carried out on the drop-resistant reliability of welding spots according to the board-level drop test method of the hand-held electronic product element of the international JEDEC standard JEDD 22-B111A-2016. The test parameters are as follows: the peak acceleration was 1500g, the pulse duration was 0.5ms, and the equivalent drop height was 1120mm (i.e., 1.12 meters). The solder joint failure criterion is based on the condition that the digital multimeter detects the change of the resistance value between the positive terminal and the negative terminal of the PCB, and the device for recording the drop test takes the circuit breaking (no conduction) as the final failure basis. Because the board-level drop test method is time-consuming and labor-consuming, when the drop test times of the examples 1, 2 and 3 reach 3500 times (which is 2 times higher than that of the Sn-58Bi solder ball/Sn-58 Bi-1.6Sb solder paste) and still not failed, the test is not continued according to the common practice in the industry.
Please refer to fig. 2. The figure shows drop number comparison data when the plate-level drop test specimen fails. FIG. 2 shows that the drop impact resistance of drop impact on Sn-58Bi solder ball/Sn-58 Bi-1.6Sb solder paste and Sn-58Bi solder ball/example 1 solder paste, sn-58Bi solder ball/example 2 solder paste, sn-58Bi solder ball/example 3 solder paste, sn-58Bi solder ball/comparative example solder paste (i.e., without nano silver paste added) of a double sided Cu substrate in a BGA structure was prepared using Sn-58Bi solder ball/Sn-58 Bi-1.6Sb solder paste and Sn-58Bi solder ball/example 1 solder paste, sn-58Bi solder ball/example 2 solder paste, sn-58Bi solder ball/example 3 solder paste, sn-58Bi solder ball/comparative example composite solder paste, and Sn-58Bi solder paste was investigated. The test results show that the anti-drop impact performance of the solder joints of the epoxy resin composite Sn-Bi-Sb lead-free solder paste (the examples 1 to 3) is far better than that of the Sn-58Bi-1.6Sb solder paste. Although the drop impact resistance of the comparative example without nano silver paste is inferior to that of examples 1-3, the comparative example is still superior to Sn-58Bi-1.6Sb soldering paste, which fully shows that the addition of the epoxy resin, the curing agent and the accelerator thereof after optimization of the preferable and proportion obviously improves the drop impact resistance of the soldering points.
Compared with the prior researches, the application has the following creativity:
1) The mechanism for enhancing the shear strength of the epoxy resin and the nano silver paste on the welding spot of the composite Sn-58Bi-1.6Sb soldering paste is discovered and elucidated. Namely, the cured epoxy resin forms a thin and uniform coating layer on the surface of the welding spot, and plays a role in physical reinforcement (or mechanical reinforcement) of the welding spot. Through soldering comparison tests on chip resistors (R0603, R0805 and R1210) with three sizes, the larger the size of the chip resistor is, the larger the area of an epoxy resin coating layer formed on the surface of a welding spot is, and the larger the absolute value of the shearing force of a soldering welding spot is; however, the shear strength (i.e., shear force) of the solder joint obtained in the examples was compared with the shear force of the commercially available Sn-58Bi-1.6Sb solder paste solder joint, and it was found that the "improvement rate" of the shear force was about 80%. This suggests that the increase in shear force is not solely due to the mechanical reinforcement of the cured epoxy resin, but is also related to the addition of nanosilver. The nano silver and the Sn-Bi-Sb alloy in the Sn-58Bi-1.6Sb soldering paste have a metallurgical reaction in the soldering process, and the nano Ag particles and the Sn-58Bi-1.6Sb form a Sn-Bi-Sb-Ag quaternary alloy, so that the shearing strength of the soldering point is further improved. This theory can be explained from the data of the "comparative example", which is a "comparative example" without the addition of the nano silver paste, although the shear force is higher than that of the commercially available Sn-58Bi-1.6Sb solder joint, but is significantly lower than that of examples 1-3, indicating that the addition of the nano silver paste does "metallurgically react" with the Sn-58Bi-1.6Sb alloy, and that the addition of the nano silver paste helps to further increase the shear strength of the epoxy composite Sn-Bi-Sb lead-free solder paste.
2) The addition of a proper amount of nano silver paste is found to obviously improve the anti-dropping performance of the soldering joint of the epoxy resin Sn-Bi-1.6Sb composite soldering paste. According to the board-level drop test method provided by the international JEDEC standard JEDD 22-B111A-2016 'board-level drop test method of hand-held electronic product element', the drop-resistant reliability of the welding spot is tested. The test parameters are as follows: the peak acceleration was 1500g, the pulse duration was 0.5ms, and the equivalent drop height was 1120mm (i.e., 1.12 meters). The test results show that the anti-drop impact performance of the soldering joint of the epoxy resin composite Sn-Bi-Sb leadless solder paste (the embodiment 1 to the embodiment 3) is far better than that of the soldering joint of the Sn-58Bi-1.6Sb solder paste.
Although the comparative solder joints without the addition of the nano silver paste were inferior to examples 1 to 3 in drop impact resistance, they were still superior to the Sn-58Bi-1.6Sb solder joints. The method is characterized in that a thin and uniform coating layer is formed on the surface of the welding spot by the solidified epoxy resin, and the welding spot is subjected to physical enhancement (or mechanical enhancement), so that the drop impact resistance of the welding spot is improved, but compared with the test data of the embodiment 1-3, the drop resistance of the Sn-58Bi-1.6Sb-Ag quaternary alloy formed by the welding spot is more excellent after the nano silver paste is added.
Analysis of the structure of the dropping failure welding spot shows that when the dropping impact load is born, the welding spot is not only influenced by positive stress (tensile stress and compressive stress) when the PCB substrate is bent and deformed, but also the bonding force of the grain boundary in the welding spot is influenced by the action of shear stress, so that cracks are generated between grains. Although the fracture morphology of the epoxy resin composite welding spot shows that the welding spot is wrapped by the epoxy resin curing material, the mechanical resistance and the plastic deformation capacity of the epoxy resin reinforcing layer provide mechanical resistance for the welding spot to resist drop impact vibration and the deflection deformation of the PCB substrate, and the drop-resistant reliability of the welding spot is improved by a mechanical reinforcement (or physical reinforcement) mode. The thicker or more the epoxy reinforcement layer, the better the drop resistance of the solder joint should be if the analysis is made purely as described above. However, the actual situation shows that: the drop impact resistance is similar to the shear force enhancement mechanism of the braze joint, i.e., not only caused by the cured epoxy reinforcement, but also related to the addition of nanosilver.
As described above, the nano silver particle size in the nano silver paste added in the technical scheme is 150 nm-250 nm, the pressureless sintering temperature is not higher than 220 ℃, the peak temperature of the reflow soldering is 250 ℃, and the temperature is kept for 5min. Under the condition, the nano silver paste can completely react with Sn-58Bi-1.6Sb in a sufficient metallurgical way to form the Sn-Bi-Sb-Ag quaternary alloy. In the "cooling stage" of reflow soldering, the nano Ag particles as "nucleation points" can accelerate the crystallization of Sn-Bi-Sb-Ag alloy and play a role of "refining grains". The result of grain refinement generally results in fine grain strengthening and improved "plasticity". Under the condition that the peak temperature of reflow soldering is 250 ℃ and the temperature is kept for 5min, the added epoxy resin is completely solidified with the curing agent under the action of the accelerator, and the optimal reinforcing effect is achieved. Therefore, the shearing strength and the anti-drop performance of the soldering joint of the epoxy resin composite Sn-Bi-Sb leadless soldering paste (example 1 to example 3) added with the nano silver paste are further improved compared with those of the comparative examples.
According to the mass ratio of the epoxy resin composite Sn-Bi-Sb lead-free solder paste, the specific embodiment of the application is described as follows.
Example 1
The epoxy resin composite Sn-Bi-Sb lead-free soldering paste is characterized by comprising 3% of epoxy resin, 3% of curing agent and 5.0% of nano silver paste by mass percent, and the balance of commercially available Sn-Bi-Sb soldering paste. Wherein the mixture of the epoxy resin, the curing agent and the accelerator comprises the components in percentage by mass of the composition as the ratio of the epoxy resin to the curing agent to the accelerator=100:70:9. The epoxy resin is a combination of 50% E44 bisphenol A and 50% E51 bisphenol A, the curing agent is a combination of 40% maleic anhydride and 60% phthalic anhydride, and the accelerator is a combination of 30% 2,4, 6-tris (dimethylaminomethyl) phenol (i.e. DMP-30) and 30% catechol and 40% resorcinol. The grain diameter of nano silver in the nano silver paste is 150 nm-250 nm, and the pressureless sintering temperature is not higher than 220 ℃. The commercial Sn-Bi-Sb soldering paste comprises 85% of Sn-Bi-Sb alloy powder by mass percent, and the balance of commercial soldering flux. Wherein Bi element accounts for 57% of the alloy powder, sb accounts for 2.0%, the balance is Sn, and the particle diameter of the alloy powder is 20-75 mu m.
According to the proportion, adding a proper amount of ethanol or glycol, and stirring for 10-30 min by using a high-speed stirrer (the rotating speed is 300-1200 r/min), thus obtaining the epoxy resin composite Sn-Bi-Sb lead-free soldering paste.
The prepared epoxy resin composite Sn-Bi-Sb lead-free soldering paste has improved wetting and spreading performance (no negative influence), takes an FR-4 type PCB as a test board, takes R0603, R0805 and R1210 chip resistors as test elements, performs reflow soldering under the conditions of the peak temperature of 250 ℃ and heat preservation for 5min, improves the shearing strength of soldering spots by more than 80 percent compared with the shearing force of soldering spots of the commercially available Sn-58Bi-1.6Sb soldering paste, and ensures that the dropping frequency of a board-level drop test piece when the board-level drop test piece fails reaches more than 3 times of the soldering spots of the commercially available Sn-58Bi-1.6Sb soldering paste.
The solder paste still meets the use requirement when stored at 0 ℃ for more than 1a (i.e. 1 year) in the refrigerator.
Example 2
The epoxy resin composite Sn-Bi-Sb lead-free soldering paste is characterized by comprising 6 mass percent of epoxy resin, a curing agent and an accelerator, 1.5 mass percent of nano silver paste and the balance of commercially available Sn-Bi-Sb soldering paste. Wherein the mixture of the epoxy resin, the curing agent and the accelerator comprises the components in percentage by mass of the composition of the epoxy resin, the curing agent, the accelerator=100:85:4. The epoxy resin is a combination of 50% E44 bisphenol A and 50% E51 bisphenol A, the curing agent is a combination of 40% maleic anhydride and 60% phthalic anhydride, and the accelerator is a combination of 30% 2,4, 6-tris (dimethylaminomethyl) phenol (i.e. DMP-30) and 30% catechol and 40% resorcinol. The grain diameter of nano silver in the nano silver paste is 150 nm-250 nm, and the pressureless sintering temperature is not higher than 220 ℃. The commercial Sn-Bi-Sb soldering paste comprises 85% of Sn-Bi-Sb alloy powder by mass percent, and the balance of commercial soldering flux. Wherein Bi element accounts for 59% of the alloy powder, sb accounts for 1.2%, the balance is Sn, and the diameter of the alloy powder particles is 20-75 mu m.
According to the proportion, adding a proper amount of ethanol or glycol, and stirring for 10-30 min by using a high-speed stirrer (the rotating speed is 300-1200 r/min), thus obtaining the epoxy resin composite Sn-Bi-Sb lead-free soldering paste.
The prepared epoxy resin composite Sn-Bi-Sb lead-free soldering paste has improved wetting and spreading performance (no negative influence), takes an FR-4 type PCB as a test board, takes R0603, R0805 and R1210 chip resistors as test elements, performs reflow soldering under the conditions of the peak temperature of 250 ℃ and heat preservation for 5min, improves the shearing strength of soldering spots by more than 80 percent compared with the shearing force of soldering spots of the commercially available Sn-58Bi-1.6Sb soldering paste, and ensures that the dropping frequency of a board-level drop test piece when the board-level drop test piece fails reaches more than 3 times of the soldering spots of the commercially available Sn-58Bi-1.6Sb soldering paste.
The solder paste still meets the use requirement when stored at 0 ℃ for more than 1a (i.e. 1 year) in the refrigerator.
Example 3
The epoxy resin composite Sn-Bi-Sb lead-free soldering paste is characterized by comprising 4.5% of epoxy resin, a curing agent and an accelerator in percentage by mass, 3.2% of nano silver paste and the balance of commercially available Sn-Bi-Sb soldering paste. Wherein the mixture of the epoxy resin, the curing agent and the accelerator comprises the components in percentage by mass of the composition of the epoxy resin, the curing agent and the accelerator=100:80:6. The epoxy resin is a combination of 50% E44 bisphenol A and 50% E51 bisphenol A, the curing agent is a combination of 40% maleic anhydride and 60% phthalic anhydride, and the accelerator is a combination of 30% 2,4, 6-tris (dimethylaminomethyl) phenol (i.e. DMP-30) and 30% catechol and 40% resorcinol. The grain diameter of nano silver in the nano silver paste is 150 nm-250 nm, and the pressureless sintering temperature is not higher than 220 ℃. The commercial Sn-Bi-Sb soldering paste comprises 90% of Sn-Bi-Sb alloy powder by mass percent, and the balance of commercial soldering flux. Wherein Bi element accounts for 58% of the alloy powder, sb accounts for 1.6%, the balance is Sn, and the particle diameter of the alloy powder is 20-75 mu m.
According to the proportion, adding a proper amount of ethanol or glycol, and stirring for 10-30 min by using a high-speed stirrer (the rotating speed is 300-1200 r/min), thus obtaining the epoxy resin composite Sn-Bi-Sb lead-free soldering paste.
The prepared epoxy resin composite Sn-Bi-Sb lead-free soldering paste has improved wetting and spreading performance (no negative influence), takes an FR-4 type PCB as a test board, takes R0603, R0805 and R1210 chip resistors as test elements, performs reflow soldering under the conditions of the peak temperature of 250 ℃ and heat preservation for 5min, improves the shearing strength of soldering spots by more than 80 percent compared with the shearing force of soldering spots of the commercially available Sn-58Bi-1.6Sb soldering paste, and ensures that the dropping frequency of a board-level drop test piece when the board-level drop test piece fails reaches more than 3 times of the soldering spots of the commercially available Sn-58Bi-1.6Sb soldering paste.
The solder paste still meets the use requirement when stored at 0 ℃ for more than 1a (i.e. 1 year) in the refrigerator.
Comparative example
The epoxy resin composite Sn-Bi-Sb lead-free soldering paste is characterized by comprising 4.5 mass percent of epoxy resin, a curing agent and an accelerator, and the balance of commercially available Sn-Bi-Sb soldering paste. Wherein the mixture of the epoxy resin, the curing agent and the accelerator comprises the components in percentage by mass of the composition of the epoxy resin, the curing agent and the accelerator=100:80:6. The epoxy resin is a combination of 50% E44 bisphenol A and 50% E51 bisphenol A, the curing agent is a combination of 40% maleic anhydride and 60% phthalic anhydride, and the accelerator is a combination of 30% 2,4, 6-tris (dimethylaminomethyl) phenol (i.e. DMP-30) and 30% catechol and 40% resorcinol. The commercial Sn-Bi-Sb soldering paste comprises 90% of Sn-Bi-Sb alloy powder by mass percent, and the balance of commercial soldering flux. Wherein Bi element accounts for 58% of the alloy powder, sb accounts for 1.6%, the balance is Sn, and the particle diameter of the alloy powder is 20-75 mu m.
According to the proportion, adding a proper amount of ethanol or glycol, and stirring for 10-30 min by using a high-speed stirrer (the rotating speed is 300-1200 r/min), thus obtaining the epoxy resin composite Sn-Bi-Sb lead-free soldering paste without nano silver paste.
The prepared epoxy resin composite Sn-Bi-Sb lead-free soldering paste has improved wetting and spreading performance (no negative influence), takes an FR-4 type PCB as a test board, takes R0603, R0805 and R1210 chip resistors as test elements, performs reflow soldering under the conditions of the peak temperature of 250 ℃ and heat preservation for 5min, improves the shearing strength of soldering spots by about 68 percent (lower than that of the soldering spots of the commercially available Sn-58Bi-1.6Sb soldering paste, and improves the dropping times of a board-level drop test piece by about 1 time compared with that of the soldering spots of the commercially available Sn-58Bi-1.6Sb soldering paste, and is remarkably lower than that of the examples 1 to 3 added with nano silver paste.
The solder paste still meets the use requirement when stored at 0 ℃ for more than 1a (i.e. 1 year) in the refrigerator.
Claims (4)
1. An epoxy resin composite Sn-Bi-Sb lead-free soldering paste is characterized in that:
the composition of the solder paste comprises 3 to 6 mass percent of epoxy resin, 1.5 to 5.0 mass percent of curing agent and accelerator, and the balance of commercial Sn-Bi-Sb solder paste;
in the mixture composed of the epoxy resin, the curing agent and the accelerator, the weight percentage of each component in the composition is that the ratio of the epoxy resin to the curing agent to the accelerator=100:70-85:4-9;
the epoxy resin is a combination of 50% of E44 bisphenol A and 50% of E51 bisphenol A;
the curing agent is a combination of 40% maleic anhydride and 60% phthalic anhydride;
the above accelerator was a combination of 30% 2,4, 6-tris (dimethylaminomethyl) phenol (i.e. DMP-30) with 30% catechol and 40% resorcinol.
2. The epoxy resin composite Sn-Bi-Sb lead-free solder paste of claim 1, wherein:
the method adopts the commercial Sn-Bi-Sb soldering paste, wherein the Sn-Bi-Sb alloy powder accounts for 85 to 95 percent of the commercial Sn-Bi-Sb soldering paste by mass percent, and the balance is commercial soldering flux.
3. The epoxy resin composite Sn-Bi-Sb lead-free solder paste of claim 2, wherein:
in the Sn-Bi-Sb alloy powder, according to the mass percentage, bi element accounts for 57-59% of the alloy powder, sb accounts for 1.2-2.0%, and the balance is Sn; the diameter of the alloy powder particles is 20 mm-75 mm.
4. The method for preparing an epoxy resin composite Sn-Bi-Sb lead-free solder paste according to claim 3, comprising the steps of:
step 1, using a tin ingot, a bismuth block and an antimony ingot which are sold in the market, proportioning raw materials of various elements according to the requirement, adding a covering agent determined by optimization and screening during smelting, or adopting inert gas for protection to carry out smelting and casting to obtain a Sn-Bi-Sb alloy bar;
re-melting the smelted Sn-Bi-Sb alloy, and preparing the Sn-Bi-Sb alloy into alloy powder with the particle diameter of 20-75 mm by adopting argon protection through an 'aerosolization' powder making device; pb element is used as an impurity element in the raw material, and the total amount (mass percent) is controlled within the range that Pb is less than or equal to 0.07 and wt percent;
adding a proper amount of ethanol or glycol into 85-95% by mass of Sn-Bi-Sb alloy powder and the balance of commercial soldering flux, using a high-speed stirrer, and stirring for 10-30 min at a rotating speed of 300-1200 r/min to obtain Sn-Bi-Sb leadless solder paste;
mixing 50% of an epoxy resin combination mixture of E44 bisphenol A and 50% of E51 bisphenol A, 40% of a curing agent combination mixture of maleic anhydride and 60% of phthalic anhydride, and 30% of an accelerator combination mixture of 2,4, 6-tris (dimethylaminomethyl) phenol and 30% of catechol and 40% of resorcinol according to the ratio of epoxy resin to curing agent to accelerator=100:70-85:4-9 in advance, and uniformly mixing for later use;
then, adding a proper amount of ethanol or glycol into a mixture consisting of 3-6% by mass of epoxy resin, a curing agent and an accelerator, 1.5-5.0% by mass of commercial nano silver paste and the balance of the Sn-Bi-Sb leadless solder paste prepared by the method, and stirring for 10-30 min by using a high-speed stirrer at the rotating speed of 300-1200 r/min to obtain the epoxy resin composite Sn-Bi-Sb leadless solder paste; wherein the grain diameter of the nano silver in the commercial nano silver paste is 150 nm-250 nm, and the pressureless sintering temperature is not higher than 220 ℃.
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| CN117828956A (en) * | 2024-03-05 | 2024-04-05 | 南京邮电大学 | Packaging drop reliability prediction method based on crystal plasticity finite element model |
| CN117828956B (en) * | 2024-03-05 | 2024-05-28 | 南京邮电大学 | Packaging drop reliability prediction method based on crystal plasticity finite element model |
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