CN115070031A - Cu @ In @ Ag core-shell structure interconnection material and preparation method thereof - Google Patents
Cu @ In @ Ag core-shell structure interconnection material and preparation method thereof Download PDFInfo
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- CN115070031A CN115070031A CN202210621654.0A CN202210621654A CN115070031A CN 115070031 A CN115070031 A CN 115070031A CN 202210621654 A CN202210621654 A CN 202210621654A CN 115070031 A CN115070031 A CN 115070031A
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- 239000011258 core-shell material Substances 0.000 title claims abstract description 81
- 239000000463 material Substances 0.000 title claims abstract description 32
- 238000002360 preparation method Methods 0.000 title claims abstract description 17
- 239000000843 powder Substances 0.000 claims abstract description 59
- 239000010949 copper Substances 0.000 claims abstract description 56
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 48
- 229910000765 intermetallic Inorganic materials 0.000 claims abstract description 19
- 238000007747 plating Methods 0.000 claims description 76
- 229910052738 indium Inorganic materials 0.000 claims description 44
- APFVFJFRJDLVQX-UHFFFAOYSA-N indium atom Chemical compound [In] APFVFJFRJDLVQX-UHFFFAOYSA-N 0.000 claims description 39
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical group [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 33
- 238000006243 chemical reaction Methods 0.000 claims description 28
- 239000008139 complexing agent Substances 0.000 claims description 24
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 claims description 22
- 229910052709 silver Inorganic materials 0.000 claims description 21
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims description 19
- 239000003638 chemical reducing agent Substances 0.000 claims description 18
- 239000004332 silver Substances 0.000 claims description 18
- 239000000126 substance Substances 0.000 claims description 16
- QIGBRXMKCJKVMJ-UHFFFAOYSA-N 1,4-Benzenediol Natural products OC1=CC=C(O)C=C1 QIGBRXMKCJKVMJ-UHFFFAOYSA-N 0.000 claims description 14
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 12
- 239000012279 sodium borohydride Substances 0.000 claims description 12
- 229910000033 sodium borohydride Inorganic materials 0.000 claims description 12
- 239000003963 antioxidant agent Substances 0.000 claims description 11
- 230000003078 antioxidant effect Effects 0.000 claims description 11
- 229910001961 silver nitrate Inorganic materials 0.000 claims description 11
- KDFGOTCGVFPNOU-UHFFFAOYSA-N 2-hydroxy-5-sulfobenzoic acid pentahydrate Chemical compound O.O.O.O.O.OC(=O)c1cc(ccc1O)S(O)(=O)=O KDFGOTCGVFPNOU-UHFFFAOYSA-N 0.000 claims description 9
- ATRRKUHOCOJYRX-UHFFFAOYSA-N Ammonium bicarbonate Chemical compound [NH4+].OC([O-])=O ATRRKUHOCOJYRX-UHFFFAOYSA-N 0.000 claims description 9
- QNAYBMKLOCPYGJ-REOHCLBHSA-N L-alanine Chemical compound C[C@H](N)C(O)=O QNAYBMKLOCPYGJ-REOHCLBHSA-N 0.000 claims description 9
- 235000004279 alanine Nutrition 0.000 claims description 9
- 239000001099 ammonium carbonate Substances 0.000 claims description 9
- 235000012501 ammonium carbonate Nutrition 0.000 claims description 9
- MGFYIUFZLHCRTH-UHFFFAOYSA-N nitrilotriacetic acid Chemical compound OC(=O)CN(CC(O)=O)CC(O)=O MGFYIUFZLHCRTH-UHFFFAOYSA-N 0.000 claims description 9
- GSEJCLTVZPLZKY-UHFFFAOYSA-N Triethanolamine Chemical compound OCCN(CCO)CCO GSEJCLTVZPLZKY-UHFFFAOYSA-N 0.000 claims description 8
- 238000001035 drying Methods 0.000 claims description 8
- 239000002245 particle Substances 0.000 claims description 8
- 229910000337 indium(III) sulfate Inorganic materials 0.000 claims description 7
- XGCKLPDYTQRDTR-UHFFFAOYSA-H indium(iii) sulfate Chemical group [In+3].[In+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O XGCKLPDYTQRDTR-UHFFFAOYSA-H 0.000 claims description 7
- 239000003109 Disodium ethylene diamine tetraacetate Substances 0.000 claims description 6
- ZGTMUACCHSMWAC-UHFFFAOYSA-L EDTA disodium salt (anhydrous) Chemical compound [Na+].[Na+].OC(=O)CN(CC([O-])=O)CCN(CC(O)=O)CC([O-])=O ZGTMUACCHSMWAC-UHFFFAOYSA-L 0.000 claims description 6
- 238000004140 cleaning Methods 0.000 claims description 6
- 235000019301 disodium ethylene diamine tetraacetate Nutrition 0.000 claims description 6
- 238000005554 pickling Methods 0.000 claims description 5
- 238000002791 soaking Methods 0.000 claims description 4
- 125000000687 hydroquinonyl group Chemical group C1(O)=C(C=C(O)C=C1)* 0.000 claims description 2
- 239000007788 liquid Substances 0.000 claims description 2
- 238000007781 pre-processing Methods 0.000 claims description 2
- 238000003466 welding Methods 0.000 abstract description 38
- 238000000034 method Methods 0.000 abstract description 22
- 239000000758 substrate Substances 0.000 abstract description 21
- 229910052802 copper Inorganic materials 0.000 abstract description 20
- 230000008569 process Effects 0.000 abstract description 17
- 230000003647 oxidation Effects 0.000 abstract description 10
- 238000007254 oxidation reaction Methods 0.000 abstract description 10
- 239000000243 solution Substances 0.000 description 97
- 239000002184 metal Substances 0.000 description 31
- 229910052751 metal Inorganic materials 0.000 description 31
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 26
- 238000005303 weighing Methods 0.000 description 21
- 230000006872 improvement Effects 0.000 description 20
- 239000010410 layer Substances 0.000 description 20
- 239000008367 deionised water Substances 0.000 description 17
- 229910021641 deionized water Inorganic materials 0.000 description 17
- 239000003795 chemical substances by application Substances 0.000 description 15
- 238000002844 melting Methods 0.000 description 10
- 238000003756 stirring Methods 0.000 description 10
- 230000008018 melting Effects 0.000 description 9
- 229910000679 solder Inorganic materials 0.000 description 8
- QAOWNCQODCNURD-UHFFFAOYSA-N sulfuric acid Substances OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 8
- 239000006228 supernatant Substances 0.000 description 8
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 7
- 239000000203 mixture Substances 0.000 description 6
- 238000002156 mixing Methods 0.000 description 5
- 238000001291 vacuum drying Methods 0.000 description 5
- 239000007864 aqueous solution Substances 0.000 description 4
- 238000007731 hot pressing Methods 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- 230000035484 reaction time Effects 0.000 description 4
- 238000005219 brazing Methods 0.000 description 3
- 239000007795 chemical reaction product Substances 0.000 description 3
- 235000019441 ethanol Nutrition 0.000 description 3
- 239000000945 filler Substances 0.000 description 3
- 150000002739 metals Chemical class 0.000 description 3
- 238000011946 reduction process Methods 0.000 description 3
- 238000010992 reflux Methods 0.000 description 3
- 239000004065 semiconductor Substances 0.000 description 3
- 238000010008 shearing Methods 0.000 description 3
- 229910052718 tin Inorganic materials 0.000 description 3
- 238000005406 washing Methods 0.000 description 3
- BDOYKFSQFYNPKF-UHFFFAOYSA-N 2-[2-[bis(carboxymethyl)amino]ethyl-(carboxymethyl)amino]acetic acid;sodium Chemical compound [Na].[Na].OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O BDOYKFSQFYNPKF-UHFFFAOYSA-N 0.000 description 2
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 2
- 238000000026 X-ray photoelectron spectrum Methods 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000007772 electroless plating Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 239000005022 packaging material Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000006722 reduction reaction Methods 0.000 description 2
- 238000004088 simulation Methods 0.000 description 2
- 238000005476 soldering Methods 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- 229910017980 Ag—Sn Inorganic materials 0.000 description 1
- JPVYNHNXODAKFH-UHFFFAOYSA-N Cu2+ Chemical compound [Cu+2] JPVYNHNXODAKFH-UHFFFAOYSA-N 0.000 description 1
- 239000002202 Polyethylene glycol Substances 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052797 bismuth Inorganic materials 0.000 description 1
- JCXGWMGPZLAOME-UHFFFAOYSA-N bismuth atom Chemical compound [Bi] JCXGWMGPZLAOME-UHFFFAOYSA-N 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 229910001431 copper ion Inorganic materials 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 230000020169 heat generation Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 229910001449 indium ion Inorganic materials 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 230000033116 oxidation-reduction process Effects 0.000 description 1
- 238000006864 oxidative decomposition reaction Methods 0.000 description 1
- 239000003002 pH adjusting agent Substances 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 229920001223 polyethylene glycol Polymers 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000006479 redox reaction Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- -1 silver ions Chemical class 0.000 description 1
- YPNVIBVEFVRZPJ-UHFFFAOYSA-L silver sulfate Chemical compound [Ag+].[Ag+].[O-]S([O-])(=O)=O YPNVIBVEFVRZPJ-UHFFFAOYSA-L 0.000 description 1
- 229910000367 silver sulfate Inorganic materials 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 238000003892 spreading Methods 0.000 description 1
- 230000007480 spreading Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000010301 surface-oxidation reaction Methods 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/17—Metallic particles coated with metal
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
- C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
- C23C18/18—Pretreatment of the material to be coated
- C23C18/1803—Pretreatment of the material to be coated of metallic material surfaces or of a non-specific material surfaces
- C23C18/1824—Pretreatment of the material to be coated of metallic material surfaces or of a non-specific material surfaces by chemical pretreatment
- C23C18/1827—Pretreatment of the material to be coated of metallic material surfaces or of a non-specific material surfaces by chemical pretreatment only one step pretreatment
- C23C18/1834—Use of organic or inorganic compounds other than metals, e.g. activation, sensitisation with polymers
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
- C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
- C23C18/31—Coating with metals
- C23C18/42—Coating with noble metals
- C23C18/44—Coating with noble metals using reducing agents
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
- C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
- C23C18/52—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating using reducing agents for coating with metallic material not provided for in a single one of groups C23C18/32 - C23C18/50
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L23/00—Details of semiconductor or other solid state devices
- H01L23/52—Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames
- H01L23/522—Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames including external interconnections consisting of a multilayer structure of conductive and insulating layers inseparably formed on the semiconductor body
- H01L23/532—Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames including external interconnections consisting of a multilayer structure of conductive and insulating layers inseparably formed on the semiconductor body characterised by the materials
- H01L23/53204—Conductive materials
- H01L23/53209—Conductive materials based on metals, e.g. alloys, metal silicides
- H01L23/53228—Conductive materials based on metals, e.g. alloys, metal silicides the principal metal being copper
- H01L23/53238—Additional layers associated with copper layers, e.g. adhesion, barrier, cladding layers
-
- 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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- 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 provides a Cu @ In @ Ag core-shell structure interconnection material and a preparation method thereof. According to the technical scheme, copper is used as a core, In @ Ag is coated outside the copper, the middle layer In can enable the welding temperature to be lower than 250 ℃, the outermost layer Ag improves the oxidation resistance of core-shell structure powder, and meanwhile, the Ag reacts with In the backflow process to generate a high-melting-point intermetallic compound phase, so that the high-temperature resistance and high-temperature shear strength of a welding spot are improved, and the purpose of low-temperature connection and high-temperature service is achieved; the existence of the micron-sized copper core can relieve stress concentration, match the thermal expansion coefficient of the substrate and prevent crack propagation.
Description
Technical Field
The invention belongs to the technical field of new materials, and particularly relates to a Cu @ In @ Ag core-shell structure interconnection material and a preparation method thereof.
Background
With the development of the electronic industry, devices have gradually changed to miniaturization and integration, which results in the increase of power density and current density per unit area, thereby causing the increase of heat generation, and some local temperatures can reach 350 ℃. While the traditional semiconductor material Si can only stably work at the temperature lower than 175 ℃, the third generation semiconductors such as SiC, GaN and the like have wider band gaps, higher electronic saturation ratio and breakdown voltage, so that the semiconductor material Si can be stably used in the environment with higher temperature. Nowadays, more and more fields are applied to high-power devices, such as radars, aircrafts, space exploration, new energy sources and the like; SiC power devices have also been successfully applied to solar inverters, wind turbines, power control units for energy vehicles, and the like.
The current commonly used chip interconnection materials have the following defects: the tin-based solder such as SAC305 which is widely applied has good wetting and spreading properties and can form reliable metallurgical bonding with most metals, but has a low melting point and cannot stably work under the high-temperature condition of more than 250 ℃; the gold-based brazing filler metal has good mechanical property, but the generated welding spot is locally hard and brittle, and the cost is high; the bismuth-based solder has a lower melting point, can be subjected to a reflow soldering process at a lower temperature, but has lower thermal conductivity and general reliability; the conductive adhesive has attracted much attention in recent years as an interconnection material with a large potential, but has poor thermoelectric performance due to its high polymer content; the nano silver paste is another interconnection material with wide application prospect, can be sintered at the temperature of below 300 ℃, can bear the high temperature of 900 ℃, and has excellent electrical conductivity and thermal conductivity, but the electromigration phenomenon of silver ions and higher cost thereof prevent the wide application of the nano silver paste.
Chinese patent CN106180696B discloses a preparation method of a Ni @ Sn core-shell structure-based high-temperature solder, wherein the core-shell structure metal powder only contains two elements of Ni and Sn, and is realized by plating a Sn layer with certain thickness and weldability on the surfaces of micro-nano nickel spheres. The method is of a double-layer core-shell structure, Sn at the outermost layer is easy to oxidize, the connection between core-shell powder in the backflow process is influenced, and finally generated welding seams are poor in oxidation resistance and cannot be used for a long time; due to the existence of Sn, the reflow temperature needs to be set at 250 ℃, and the thermal influence on the chip caused by the high reflow temperature is increased; meanwhile, the Ni spheres with micro and nano levels are taken as cores, and the cost is higher than that of Cu, so that the method is not suitable for industrial production.
Disclosure of Invention
Aiming at the technical problems, the invention discloses a Cu @ In @ Ag core-shell structure interconnection material and a preparation method thereof, the material can be prepared into a prefabricated sheet of the interconnection material, a welding spot formed by welding the prefabricated sheet and a copper substrate/silver-plated copper substrate can be subjected to reflux at the temperature of lower than 200 ℃, and the finally generated welding spot can be In service at the temperature of higher than 400 ℃, and has better thermoelectric property, oxidation resistance and high-temperature reliability.
In contrast, the technical scheme adopted by the invention is as follows:
the Cu @ In @ Ag core-shell structure interconnection material comprises a Cu core, wherein an In @ Ag layer is coated on the surface of the Cu core to form a Cu @ In @ Ag core-shell structure, and the In @ Ag layer is an Ag-In intermetallic compound.
As a further improvement of the invention, the particle size of the Cu core is 5-35 μm. Further, the morphology of the Cu core is spherical.
As a further improvement of the invention, the Ag-In intermetallic compound comprises AgIn 2 。
As a further improvement of the invention, the In @ Ag layer has a thickness of 1 to 5 μm.
The invention discloses a preparation method of the Cu @ In @ Ag core-shell structure interconnection material, which comprises the following steps:
step S1, copper powder is pretreated;
step S2, preparing an indium plating solution;
step S3, adding the copper powder pretreated In the step S1 into the indium plating solution, adding a reducing agent to carry out chemical plating reaction, and plating an In layer on the surface of the copper powder;
step S4, cleaning the obtained product, and drying to obtain Cu @ In core-shell structure powder;
step S5, preparing silver plating solution;
and step S6, adding the obtained Cu @ In core-shell structure powder into the silver plating solution for chemical plating reaction, and cleaning and drying to obtain the Cu @ In @ Ag core-shell structure interconnection material.
As a further improvement of the present invention, In step S2, the indium plating solution contains an In source substance, a complexing agent, a dispersing agent, and a pH adjusting agent.
As a further improvement of the invention, the In source substance is indium sulfate, the complexing agents are disodium ethylene diamine tetraacetate and triethanolamine, the pH regulator is sodium hydroxide, and the antioxidant is hydroquinone; the reducing agent is sodium borohydride.
The technical scheme preferably comprises a complexing agent, an antioxidant and a reducing agent, wherein the complexing agent can form a stable complex with Cu so that the Cu 2+ The electrode potential of/Cu is shifted to a negative value until it is lower than In 3+ An electrode potential of/In; simultaneously assisting with a reducing agent to accelerate the oxidation-reduction reaction; the antioxidant can keep chemical balance, reduce surface tension, prevent actions of light, thermal decomposition or oxidative decomposition and the like, and simultaneously prevent self-agglomeration among particles, so that the oxidation-reduction process can be uniformly reacted on the copper particles.
As a further improvement of the present invention, in step S2, the indium plating solution is prepared by the following steps:
weighing indium sulfate powder, dissolving In appropriate amount of concentrated sulfuric acid, adding appropriate amount of deionized water to obtain indium plating solution 3+ The concentration is 0.1-0.3 mol/L; weighing and adding a coordination agent A, wherein the coordination agent A is ethylene diamine tetraacetic acid disodium, so that the concentration of the coordination agent in the indium plating solution is 0.1-0.3 mol/L; weighing and adding a coordination agent B, wherein the coordination agent B is triethanolamine, and the concentration of the coordination agent B in the indium plating solution is 0.2-0.6 mol/L; weighing antioxidant, adding hydroquinone, and making the concentration of hydroquinone in indium plating solution be 0.02-0.1 mol/L. Weighing sodium hydroxide powderFinally, the mixture is dissolved in deionized water to ensure that the concentration of sodium hydroxide in the pH regulating solution is 5 mol/L. Dropwise adding a sodium hydroxide solution into the indium plating solution containing the coordination agent and the antioxidant by using a rubber head dropper, and adjusting the pH to 9.0. Further, In the indium plating solution 3+ The concentration ratio of the complexing agent to the complexing agent A and the complexing agent to the complexing agent B is as follows: 1:1-3:2-6. Further, In the indium plating solution 3+ The concentration ratio of the complexing agent to the complexing agent A to the complexing agent to the antioxidant is as follows: 1:1-3:2-6: 0.2-1.
Further, weighing indium sulfate powder, dissolving In a proper amount of concentrated sulfuric acid, and adding a proper amount of deionized water to prepare an indium plating solution so that In is In 3+ The concentration is 0.1 mol/L; weighing and adding a coordination agent A, wherein the coordination agent A is ethylene diamine tetraacetic acid disodium, so that the concentration of the coordination agent in the indium plating solution is 0.1 mol/L; weighing and adding a coordination agent B, wherein the coordination agent B is triethanolamine, and the concentration of the coordination agent B in the indium plating solution is 0.2 mol/L; weighing antioxidant, namely hydroquinone, and adding the antioxidant into the indium plating solution to ensure that the concentration of the hydroquinone in the indium plating solution is 0.02 mol/L. By adopting the technical scheme, In indium plating solution is controlled 3+ The concentration, the concentration of a coordination agent, the pH value, the concentration of a reducing agent and the like, and a proper amount of In and Ag are coated on the surface of the micron-sized copper powder In sequence, so that a more stable three-layer metal core-shell structure can be obtained.
As a further improvement of the invention, the reducing agent sodium borohydride is weighed and prepared into an aqueous solution, the concentration of the aqueous solution is 2-3mol/L, and a reducing agent solution is obtained, and when the reducing agent is added in the step S3, the reducing agent solution is added in a manner of adding the reducing agent solution.
As a further improvement of the present invention, in step S1, the preprocessing includes: and (3) pickling the copper powder, and then soaking the copper powder in absolute ethyl alcohol.
As a further improvement of the invention, in step S1, the grain size of the Cu powder is selected to be 5-35 μm, and the Cu morphology is spherical.
As a further improvement of the invention, in step S1, the copper powder is acid-washed by using a dilute sulfuric acid solution with the mass fraction of 10-15%. Further, dilute sulfuric acid and copper powder are mixed and stirred for 5 minutes by magnetons, and the surface oxidation film of the copper powder is fully removed. A proper amount of absolute ethyl alcohol is weighed and added into the copper powder treated by the dilute hydrochloric acid, and magneton stirring is carried out to remove residual acid and organic matters on the surface, so that the surface of the copper powder keeps activity, and the subsequent chemical plating process is facilitated.
As a further improvement of the invention, in step S5, silver nitrate or silver sulfate is weighed and dissolved in deionized water, and a proper amount of complexing agent is added and stirred uniformly to form a silver plating solution.
As a further improvement of the present invention, in step S5, the silver plating solution contains pentahydrate sulfosalicylic acid, nitrilotriacetic acid, alanine, ammonium carbonate, and silver nitrate, and the molar concentration ratio of the pentahydrate sulfosalicylic acid, nitrilotriacetic acid, alanine, ammonium carbonate, and silver nitrate is 1-4: 0.5-2: 4-7: 4-6: 1. further, in step S5, the silver plating solution includes sulfosalicylic acid pentahydrate, nitrilotriacetic acid, alanine, ammonium carbonate, and silver nitrate, and the molar concentration ratio of sulfosalicylic acid pentahydrate, nitrilotriacetic acid, alanine, ammonium carbonate, and silver nitrate is 2-3: 1-1.5: 5-6: 5: 1.
further, in step S5, sulfosalicylic acid pentahydrate, nitrilotriacetic acid, alanine, ammonium carbonate, silver nitrate and deionized water are weighed and mixed to form a silver plating solution, and the concentrations of the silver plating solution are respectively 0.2-0.3, 0.10-0.15, 0.5-0.6, 0.5 and 0.1 mol/L.
As a further improvement of the invention, in the electroless plating reaction in the step S3, the pH value of the solution is 8.0-10.0, the reaction temperature is 70-90 ℃, and a reducing agent is dripped in the reaction process to ensure sufficient reaction.
Further, the indium plating solution is added with the pre-treated copper powder under the condition of continuous stirring, the mixture is placed in a water bath kettle at the temperature of 80 ℃ and stirred with magnetons at a proper rotating speed for 40-60min, and a reducing agent is dripped in the reaction process to ensure full reaction. Further, the concentration of the reducing agent sodium borohydride solution is 2-3 mol/L.
As a further improvement of the invention, In step S3, the pH value of the indium plating solution is adjusted to 9.0 by using 5mol/L sodium hydroxide solution, the pretreated copper powder is poured into the indium plating solution, a proper amount of reducing solution is dripped at a proper rotating speed at 80 ℃ at intervals to reduce the In the indium plating solution to the surface of Cu powder as much as possible, the reducing solution is dripped for the last time, magneton stirring is continued for 5min, and the supernatant is poured out after standing to obtain Cu @ In core-shell structure powder.
As a further improvement of the present invention, the step S4 of washing and drying the obtained product comprises: the reaction product is washed respectively three times by using deionized water and absolute ethyl alcohol, and is dried in a vacuum drying oven for 12 hours.
As a further improvement of the invention, in the electroless plating reaction in the step S6, the pH value of the solution is 8.0-10.0, and the reaction temperature is 40-50 ℃. Further, the pH of the solution was 9.0 and the reaction temperature was 45 ℃. Further preferably, the Cu @ In core-shell structure powder is added into the silver plating solution, continuously stirred and placed In a 45 ℃ water bath kettle to be stirred for 2min at a proper rotating speed In a magneton mode so as to ensure full reaction.
As a further improvement of the invention, the reaction time In the silver plating process is also critical to the formation of the Cu @ In @ Ag core-shell structure, the plating time is 1-3min, preferably about 2min, and the judgment is made by observing the color of the supernatant: when the supernatant was blue, indicating the presence of copper ions, the In layer was completely reduced, at which point the reaction was stopped. Therefore, to obtain a three-layer core-shell structure, the reaction time must be appropriate to prevent In from Cu @ In from being Ag + And reducing, and controlling proper reaction time to obtain a stable three-layer core-shell structure for a subsequent interconnection process. As a further improvement of the invention, In step S6, the obtained Cu @ In core-shell structure powder is added into the silver plating solution to be fully mixed, plating is carried out for 2min at 45 ℃ and proper rotating speed, supernatant is poured after standing, the obtained Cu @ In @ Ag core-shell structure powder is sequentially washed twice by deionized water and alcohol, and the obtained product is dried for 12h In a vacuum drying oven at 50 ℃.
As a further improvement of the invention, the preparation method of the Cu @ In @ Ag core-shell structure interconnection material further comprises the step S7 of tabletting the Cu @ In @ Ag core-shell structure interconnection material obtained In the step S6 to obtain a Cu @ In @ Ag prefabricated sheet. Further, the pressure applied by the tablet is 7-8 MPa.
After the metal powder with the Cu @ In @ Ag core-shell structure is pressed into a prefabricated sheet, the connection of a copper substrate can be realized under certain hot pressing conditions (10 MPa and 200 ℃), and the low melting point is realized In the hot pressing processIntermetallic compound AgIn 2 Will gradually form Ag 9 In 4 、AgIn 3 In the case of high melting point phase, Cu is also formed at the interface where Cu and In are In contact during reflow 11 In 9 And Cu is generated after the reflow is finished 16 In 9 . The final solder joint structure is formed by the intermetallic compound Cu with high melting point 16 In 9 、AgIn 3 、Ag 9 In 4 And a Cu core, thereby realizing the purpose of low-temperature connection and high-temperature service.
Compared with the prior art, the invention has the beneficial effects that:
firstly, the core-shell structure material of the technical scheme of the invention takes copper as a core, and an Ag-In intermetallic compound coats the core, wherein the existence of the intermediate layer In can enable the welding temperature to be lower than 250 ℃, and experiments prove that the welding process can be carried out at 200 ℃; the outermost layer of Ag is used for improving the oxidation resistance of the core-shell structure powder, and simultaneously reacts with In a backflow process to generate a high-melting intermetallic compound phase, so that the high temperature resistance and the high temperature shear strength of a welding spot are improved; the existence of the micron-sized copper core can relieve stress concentration, match the thermal expansion coefficient of the substrate and prevent crack propagation.
A structure that copper particles are dispersedly distributed in an intermetallic compound structure is formed in a welding seam obtained through welding, the existence of a large amount of copper enables the thermal expansion coefficient of the welding seam to be matched with that of a substrate, the problems of substrate warping and cracking caused by heat input are reduced, stress concentration can be relieved due to the existence of micron-sized copper cores, and the anti-shearing capacity of the welding seam is improved. The welding spot formed by welding the prefabricated sheet and the copper substrate/silver-plated copper substrate can be reflowed at the temperature of less than 200 ℃, and the finally generated welding spot can be served at the temperature of more than 400 ℃, so that the welding spot has better thermoelectric property, oxidation resistance and high-temperature reliability.
Secondly, the technical scheme of the invention adopts the principle of chemical plating, the surface of copper powder is coated with a plurality of metal layers, and the plating of powder with a three-layer core-shell structure is realized by controlling reaction conditions such as reaction time, pH value, plating solution concentration and the like, thereby not only providing a new solution for low-temperature (lower than 250 ℃) welding, but also solving the problem that common Sn-based brazing filler metal is easy to oxidize, and having stronger controllability and applicability.
Thirdly, the technical scheme of the invention has a special multilayer core-shell structure, the combination of multi-element metals is realized through two-step plating, the welding process is greatly shortened due to the improvement of the relative contact area between the metals, and a certain amount of high-melting-point intermetallic compound phases can be generated under the conditions of low temperature and short time, so that the welding seam has certain high temperature resistance; the combination of multi-metal is realized through a novel three-layer core-shell structure, and the multi-metal is acted in a finally generated welding seam.
Fourthly, the technical scheme of the invention has simple process and low cost, can be used as a packaging material for a high-power device, can be welded at 200 ℃, can bear the high temperature of 400 ℃ at the final welding spot, has better oxidation resistance and mechanical property, solves the problems of high process temperature and long process time of the conventional packaging material for the power device, and provides a solution for the packaging of the high-power device. In addition, the technical scheme of the invention is suitable for connecting various metal coating substrates such as silver-plated substrates and tin-plated substrates, and the like, and is realized by interconnection of Ag-Ag and Ag-Sn, and the interconnection mechanism is mainly formed by metallurgical bonding of intermetallic compounds, so the applicability is wide.
Drawings
FIG. 1 is a morphology chart and a local area scan result of the Cu @ In @ Ag core-shell structure metal powder of embodiment 2 of the present invention.
FIG. 2 is a sectional view of Cu @ In @ Ag core-shell structure metal powder of example 2 of the present invention and the results of line scanning, wherein (a) is the sectional view and (b) is the results of line scanning.
FIG. 3 is an XRD spectrum of Cu @ In @ Ag core-shell structure metal powder of example 3 of the present invention before and after reflow.
Fig. 4 is a cross-sectional view of a solder joint formed by the Cu @ In @ Ag core-shell structure metal powder and the copper substrate In embodiment 3 of the present invention.
Fig. 5 is an internal structure diagram of a welding spot formed by the Cu @ In @ Ag core-shell structure metal powder In embodiment 4 of the present invention, which can be seen from fig. 1 to 3, wherein: 0501 is copper core; 0502 is Cu formed by reaction of In at outer layer of metal powder and Cu nucleus 16 In 9 (ii) a 0503 reaction of outermost Ag layer with InFormed Ag 9 In 4 。
FIG. 6 is a preform sample of example 3 of the present invention pressed with Cu @ In @ Ag core-shell structure powder.
FIG. 7 is a comparative XPS spectra of Cu @ In @ Ag core-shell powder and Cu @ In powder of example 2 of the present invention to verify their oxidation resistance; wherein, (a) is Cu @ In powder, and (b) is Cu @ In @ Ag core-shell structure powder.
FIG. 8 is a linear simulation of the coefficient of thermal expansion of a preform pressed from Cu @ In @ Ag core-shell structure powder of example 4 of the present invention.
FIG. 9 is a fracture morphology diagram of a solder joint formed by hot pressing Cu @ In @ Ag core-shell structure powder of example 4 of the present invention under high temperature shearing; wherein (a) and (b) are graphs at different magnifications.
FIG. 10 is a graphical representation of Cu @ In core-shell structured metal powders prepared under different conditions In example 5 of the present invention; wherein (a) is In 3+ The mol ratio of the complexing agent to the complexing agent is 1: 5, plated Cu @ In core-shell structure metal powder; (b) the Cu @ In core-shell structure metal powder is not fully obtained In the reduction process.
Detailed Description
Preferred embodiments of the present invention are described in further detail below.
The Cu @ In @ Ag powder with the core-shell structure is prepared by a chemical method, and the chemical method comprises the following steps:
step one, preparing a dilute hydrochloric acid solution, weighing 10ml of concentrated hydrochloric acid with the mass fraction of 98%, dropwise adding the deionized water solution and continuously stirring to finally obtain the dilute hydrochloric acid solution with the mass fraction of 10-15%;
secondly, weighing copper powder, completely dispersing the copper powder to the diluted hydrochloric acid solution prepared in the first step, stirring the copper powder for 5min by using magnetons, and pouring out supernatant after standing;
thirdly, preparing indium plating solution and reducing solution, adjusting the pH value of the indium plating solution to 9.0 by using 5mol/L sodium hydroxide solution, pouring the treated copper powder into the indium plating solution, dropwise adding a proper amount of reducing solution at a proper rotating speed at 80 ℃ at intervals to reduce In the indium plating solution to the surface of Cu powder as much as possible, continuously stirring with magnetons for 5min after dropwise adding the reducing solution for the last time, standing and pouring out supernatant to obtain Cu @ In core-shell structure powder;
and step four, preparing a silver plating solution, adjusting the pH value of the indium plating solution to 9.0 by using a 5mol/L sodium hydroxide solution, fully mixing the Cu @ In core-shell structure powder obtained In the step three with the silver plating solution, plating for 2min at 45 ℃ and a proper rotating speed, pouring out a supernatant after standing, sequentially washing the obtained Cu @ In @ Ag core-shell structure powder twice by using deionized water and alcohol, and drying In a 50 ℃ vacuum drying box for 12 h.
In the above preparation method, preferably, in the third step, indium sulfate powder is weighed and dissolved in concentrated sulfuric acid, and then a proper amount of deionized water is added to prepare an indium sulfate solution as an indium source, so that the indium ion concentration is 0.1 mol/L; weighing disodium ethylene diamine tetraacetate and triethanolamine to prepare a complexing agent solution, wherein the concentrations of the disodium ethylene diamine tetraacetate and the triethanolamine in the indium plating solution are respectively 0.1mol/L and 0.2 mol/L; weighing antioxidant hydroquinone to prepare a solution, wherein the concentration of the solution in the indium plating solution is 0.02 mol/L; and uniformly mixing the three solutions to obtain the indium plating solution. Weighing reducing agent sodium borohydride to prepare aqueous solution, and enabling the concentration of the aqueous solution to be 2-3mol/L to obtain reducing solution.
In the above preparation method, preferably, in the fourth step, sulfosalicylic acid pentahydrate, nitrilotriacetic acid, alanine, ammonium carbonate, silver nitrate and deionized water are weighed and mixed to form a silver plating solution, and the concentrations of the silver plating solution are respectively 0.2-0.3, 0.10-0.15, 0.5-0.6, 0.5 and 0.1 mol/L.
The following description will be given with reference to specific examples.
Example 1
The preparation method of the Cu @ In core-shell structure metal powder comprises the following steps:
firstly, weighing micron spherical copper powder, placing the micron spherical copper powder in a beaker, soaking the beaker by using a proper amount of diluted hydrochloric acid, placing pickling solution in a water bath kettle, stirring the pickling solution for 5min, standing the pickling solution for 1min, and pouring out supernatant;
secondly, soaking the copper powder after acid washing by using a proper amount of absolute ethyl alcohol, and stirring for 5min in a water bath kettle by using magnetons;
thirdly, 1.51g of indium sulfate powder is weighed and dissolved in 4.5g of concentrated sulfuric acid, and then 20ml of deionized water is added to prepare indium plating solution;
fourthly, weighing 2.2g of disodium ethylene diamine tetraacetate, 1.8g of triethanolamine and 0.1g of hydroquinone, dissolving in 40ml of water, and fully mixing in indium plating solution;
fifthly, weighing 4g of sodium hydroxide, dissolving the sodium hydroxide in 20ml of deionized water to prepare a pH adjusting solution, and adjusting the pH of the mixed indium plating solution to 9.0.
Sixthly, weighing 2g of sodium borohydride, and dissolving the sodium borohydride in 20ml of deionized water to prepare a reducing solution. And mixing the copper powder soaked in the ethanol and the indium plating solution with the pH value of 9.0, putting the mixture into a water bath kettle at the temperature of 80 ℃ and at a proper rotating speed, and dropwise adding 6ml of reducing solution every 5min until the reaction is finished.
And seventhly, repeatedly cleaning the reaction product by using water and absolute ethyl alcohol until the solution is clear, and placing the solution in a vacuum drying oven for drying for 12 hours.
Example 2
And (3) preparing Cu @ In @ Ag core-shell structure metal powder.
Firstly, weighing 4g of ammonium carbonate, 4.6g of pentahydrate sulfosalicylic acid and 4g of alanine, dissolving in 50mL of deionized water, and stirring until the solution is clear to form solution A;
secondly, weighing 1g of silver nitrate, dissolving the silver nitrate in 10mL of deionized water, and stirring until the solution is clear to form solution B;
thirdly, 0.5g of polyethylene glycol and 2.1g of nitrilotriacetic acid are weighed and dissolved in 20mL of deionized water, and the mixture is stirred until the mixture is clear to form solution C;
fourthly, mixing A, B, C liquid, adding sodium hydroxide solution, adjusting the pH value to 9, adding the Cu @ In powder prepared In the previous step, placing the mixture In a water bath kettle at the temperature of 45 ℃, adjusting the rotating speed and plating for 2 min;
and fifthly, repeatedly cleaning the reaction product by using water and absolute ethyl alcohol until the solution is clear, and drying the solution in a vacuum drying oven for 12 hours.
The morphology of the obtained Cu @ In @ Ag core-shell structure metal powder is shown In figure 1, and spherical core-shell structure particles with a coating structure can be obtained. The cross section of the Cu @ In @ Ag core-shell structure powder metal powder is shown In figure 2, and the coating layer at the outermost layer can be proved to be an Ag-In intermetallic compound AgIn 2 Having a melting point below 160 ℃ can be provided at lower temperaturesThe reflow capability can also enable the core-shell structure metal powder to have certain oxidation resistance, which is beneficial to the phase transformation of intermetallic compounds in the subsequent reflow process, thereby forming reliable interconnection.
The oxidation resistance of the Cu @ In core-shell powder and the Cu @ In @ Ag core-shell powder is shown In the XPS spectra of fig. 7, which shows that the content of InOx is reduced from 55.3% to 49.7%, indicating that the plated Ag improves the oxidation resistance of the Cu @ In particles.
Example 3
And (3) preparing a Cu @ In @ Ag core-shell structure powder prefabricated sheet.
Weighing 3g of dried Cu @ In @ Ag powder, placing the powder In a specific mold, maintaining the pressure for 5min under the pressure of 7-8MPa, pressing to form a prefabricated sheet with the thickness of about 300 microns, wherein the shape of the prefabricated sheet is as shown In figure 6 and is used for subsequent Cu-Cu interconnection, the prefabricated sheet can reflow at 200 ℃ and form interconnection with a copper substrate, and combining the result of figure 3 and the sectional view of the welding spot of figure 4 (In figure 4, the dark color is Cu, and the grey white color is Ag-In IMCs), the reflowed tissues are mainly Cu and Ag-In IMCs, so that the welding spot can be stably In service at 450 ℃, and the brazing filler metal has the characteristic of low-temperature reflow and high-temperature service.
The welding method applying the core-shell structure precast slab is preferably as follows:
preheating the prefabricated sheet and the substrate at 150 ℃ for 30s, heating to 200 ℃, and performing reflux for 15min under the pressure of 10MPa for welding; the cross section of the generated welding line is shown in figure 4, the micron-sized welding line is composed of core-shell structure powder and IMCs, and the welding line is compact and has no obvious holes. Experiments prove that the substrates for interconnection can be selected from copper substrates and silver-plated copper plates, and proper soldering tin paste is coated on two sides of the prefabricated sheet to form metallurgical bonding, so that reliable welding spots are obtained.
XRD patterns before and after the Cu @ In @ Ag core-shell structure metal powder reflows are shown In figure 3, and therefore, a low-melting-point phase Cu appears In the powder before welding 11 In 9 And Ag 2 In, and a small amount of incompletely reacted In; the phase transformation of intermetallic compound occurs after refluxing for 15min at 200 ℃, and the main product is Cu 16 In 9 、Ag 9 In 4 Equal heightMelting point phase, which indicates the intermetallic compound AgIn with low melting point in the hot pressing process 2 Will gradually form Ag 9 In 4 、AgIn 3 In the high melting point phase, Cu is generated at the contact interface between Cu and In during the reflow process 11 In 9 And Cu is generated after the reflow is finished 16 In 9 . The final solder joint structure is formed by the intermetallic compound Cu with high melting point 16 In 9 、AgIn 3 、Ag 9 In 4 And a Cu core, thereby realizing the purpose of low-temperature connection and high-temperature service.
Example 4
Welding application of Cu @ In @ Ag prefabricated sheet (Cu substrate)
Through multiple tests, the prefabricated sheet obtained in the embodiment 3 and the Cu substrate coated with the solder paste with the thickness of 50 microns are used for welding under the process parameters of preheating at 150 ℃ for 2min and reflowing at 200 ℃ for 15min, so that the prefabricated sheet can be connected with various substrates, and the generated welding spots still have good reliability at high temperature.
In welded on the outer layer of the core-shell structure particles In the reflow process can be melted and reacts with Cu and Ag to generate corresponding intermetallic compounds, and finally a structure that Cu cores are dispersed and distributed In the intermetallic compounds can be generated, wherein the macroscopic structure is shown In figure 4; the microstructure is shown in FIG. 5.
The linear simulation graph of the thermal expansion coefficient of the precast slab is 17.2 × 10 as shown in FIG. 8 –6 K, this value is between the chip (4.7X 10) –6 K) and copper substrate (17.7X 10) –6 /K) and is therefore a suitable interconnect material.
The fracture of the welding spot is located in the intermetallic compound between copper cores at 300 ℃, as shown in figure 9, the shearing strength is 21.85MPa, and the welding spot still has good reliability at high temperature.
Example 5
And (3) preparing Cu @ In core-shell structure metal powder under different reaction conditions.
The indium plating solution prepared In the scheme, wherein In 3+ The concentration is 0.1-0.3 mol/L; the complexing agent A is disodium ethylene diamine tetraacetate, and the concentration is 0.1-0.3 mol/L; the coordinating agent B is triethanolamine with concentration of 0.2-0.6 mol-L。In 3+ The mol ratio of the complexing agent to the complexing agent is 1: 3. increasing the concentration of the complexing agent inhibits the reduction of In 3+ The mol ratio of the complexing agent to the complexing agent is 1: as shown In fig. 10(a), the Cu @ In core-shell structure metal powder plated at 5 was found to have a small amount of In on the Cu surface and to have a less uniform dispersion.
During the reaction, In order to make In 3+ And fully reducing the sodium borohydride to the surface of the Cu core, selecting a strong reducing agent, and preferably dropwise adding the sodium borohydride once every 5min until no bubbles are generated in the plating solution, so as to prove that the dropwise added sodium borohydride is completely consumed and ensure that the reaction is fully carried out. If the reduction process is insufficient, sodium borohydride is continuously dripped when bubbles still exist In the plating solution, the reducing agent sodium borohydride cannot completely play a role In reducing In 3+ The metal powder with the Cu @ In core-shell structure finally obtained after reduction to the surface of the Cu core is shown In FIG. 10(b), and a small amount of In is on the surface of the copper core.
In addition, the pH value also affects In 3+ At pH of>When the temperature is 10 ℃, In the indium plating solution can generate precipitates, the subsequent reduction process cannot be carried out, and the pH value is within the range<At 8 th, In 3+ The chemical property is relatively stable under the complexing agent, and the subsequent plating is not facilitated.
The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.
Claims (10)
1. A Cu @ In @ Ag core-shell structure interconnection material is characterized In that: the Cu core-shell structure comprises a Cu core, wherein the surface of the Cu core is coated with an In @ Ag layer to form a Cu @ In @ Ag core-shell structure, and the In @ Ag layer is an Ag-In intermetallic compound.
2. The Cu @ In @ Ag core-shell structure interconnection material of claim 1, wherein: the particle size of the Cu core is 5-35 μm.
3. The Cu @ In @ Ag core-shell structure interconnection material of claim 1, wherein: the Ag-In intermetallic compound comprises AgIn 2 。
4. The Cu @ In @ Ag core-shell structure interconnection material of claim 3, wherein: the thickness of the In @ Ag layer is 1-5 μm.
5. The preparation method of the Cu @ In @ Ag core-shell structure interconnection material as claimed In any one of claims 1 to 4, characterized by comprising the following steps:
step S1, copper powder is pretreated;
step S2, preparing an indium plating solution;
step S3, adding the copper powder pretreated In the step S1 into the indium plating solution, adding a reducing agent to carry out chemical plating reaction, and plating an In layer on the surface of the copper powder;
step S4, cleaning the obtained product, and drying to obtain Cu @ In core-shell structure powder;
step S5, preparing silver plating solution;
and step S6, adding the obtained Cu @ In core-shell structure powder into the silver plating solution for chemical plating reaction, and cleaning and drying to obtain the Cu @ In @ Ag core-shell structure interconnection material.
6. The preparation method of the Cu @ In @ Ag core-shell structure interconnection material according to claim 5, characterized by comprising the following steps: the indium plating solution comprises an In source substance, a complexing agent, an antioxidant and a pH regulator.
7. The preparation method of the Cu @ In @ Ag core-shell structure interconnection material according to claim 6, characterized by comprising the following steps: the In source substance is indium sulfate, the complexing agents are disodium ethylene diamine tetraacetate and triethanolamine, the pH regulator is sodium hydroxide, and the antioxidant is hydroquinone; the reducing agent is sodium borohydride.
8. The preparation method of the Cu @ In @ Ag core-shell structure interconnection material according to claim 5, characterized by comprising the following steps: in step S1, the preprocessing includes: pickling copper powder, and then soaking in absolute ethyl alcohol;
in step S5, the silver plating solution includes sulfosalicylic acid pentahydrate, nitrilotriacetic acid, alanine, ammonium carbonate, and silver nitrate, and the molar concentration ratio of sulfosalicylic acid pentahydrate, nitrilotriacetic acid, alanine, ammonium carbonate, and silver nitrate is 2-3: 1-1.5: 5-6: 5: 1.
9. the preparation method of the Cu @ In @ Ag core-shell structure interconnection material according to claim 5, characterized by comprising the following steps:
in the chemical plating reaction in the step S3, the pH value of the solution is 8.0-10.0, the reaction temperature is 70-90 ℃, and reducing liquid is dripped in the reaction process to ensure full reaction;
in the chemical plating reaction in the step S6, the pH value of the solution is 8.0-10.0, the reaction temperature is 40-50 ℃, and the time is 1-3 min.
10. The preparation method of the Cu @ In @ Ag core-shell structure interconnection material according to claim 5, characterized by comprising the following steps: and S7, tabletting the Cu @ In @ Ag core-shell structure interconnection material obtained In the S6 to obtain a Cu @ In @ Ag prefabricated sheet.
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