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CN-121988928-A - Nano copper composite solder for low-temperature interconnection and preparation method and application thereof

CN121988928ACN 121988928 ACN121988928 ACN 121988928ACN-121988928-A

Abstract

The invention belongs to the technical field of electronic packaging, and particularly relates to a nano copper composite solder for low-temperature interconnection and a preparation method and application thereof. The nano copper composite solder for low-temperature interconnection comprises the following raw materials, by mass, 70-85% of surface modified nano copper, 5-20% of organic carrier and the balance of tin-based alloy powder to 100%, wherein the nano copper composite solder provided by the invention can realize low-temperature sintering at the temperature of less than 250 ℃, breaks through the technical bottleneck that the traditional solder needs to be welded at the process temperature of 250 ℃ and above, meets the interconnection requirement of heat-sensitive elements, can effectively fill interface gaps, inhibit excessive interface reaction and form a compact and stable connecting interface, and the obtained welding spot has high shear strength and high thermal shock reliability.

Inventors

  • YANG FAN
  • HU BO
  • JIANG LIANG
  • CHEN JUNYI

Assignees

  • 深圳芯源新材料有限公司

Dates

Publication Date
20260508
Application Date
20260408

Claims (10)

  1. 1. The nano copper composite solder for low-temperature interconnection is characterized by comprising the following raw materials, by mass, 70-85% of surface modified nano copper, 5-20% of an organic carrier and the balance of tin-based alloy powder, wherein the preparation method of the surface modified nano copper comprises the following steps of: s1, mixing ureido silane, ethanol and formic acid, adding pretreated nanometer copper powder, and stirring to obtain dispersion; S2, adding ethylene-acrylic acid copolymer into the dispersion liquid, stirring, filtering, washing and drying to obtain ethylene-acrylic acid copolymer-siloxane composite coated nano copper; s3, mixing ethylene-acrylic acid copolymer-siloxane composite coated nano copper and sodium phosphite reducing solution to obtain silver plating reducing solution, mixing silver nitrate, deionized water, sodium hexametaphosphate and a stabilizer to obtain silver plating oxidizing solution, adding the silver plating oxidizing solution into the silver plating reducing solution, stirring for reaction, centrifugally separating, and drying to obtain the surface modified nano copper.
  2. 2. The nano-copper composite solder for low-temperature interconnection according to claim 1, wherein the ureido silane is at least one selected from the group consisting of 3-ureidopropyltriethoxysilane and 3-ureidopropyltrimethoxysilane.
  3. 3. The nano-copper composite solder for low-temperature interconnection according to claim 2, wherein the mass ratio of ureido silane, ethanol, formic acid and pretreated nano-copper powder is 0.2-5:200-500:5-50:10-50.
  4. 4. The nano-copper composite solder for low temperature interconnection according to claim 3, wherein the mass ratio of the ethylene-acrylic acid copolymer to the pretreated nano-copper powder is 1-3:10.
  5. 5. The nano-copper composite solder for low-temperature interconnection according to claim 4, wherein the mass ratio of the ethylene-acrylic acid copolymer-siloxane composite coated nano-copper to silver nitrate is 2-8:1.
  6. 6. The nano-copper composite solder for low-temperature interconnection according to any one of claims 1 to 5, wherein the mass percentage of tin in the tin-based alloy powder is 40 to 100%.
  7. 7. The nano-copper composite solder for low temperature interconnection according to any one of claims 1 to 5, wherein the organic carrier comprises an organic solvent, an activator, a surfactant, a thixotropic agent, and an organic resin.
  8. 8. The nano-copper composite solder for low-temperature interconnection according to claim 7, wherein the mass ratio of the organic solvent, the activator, the surfactant, the thixotropic agent and the organic resin is 70-85:2-6:0.1-1:0.5-3.5:15-25.
  9. 9. The method for preparing the nano copper composite solder for low-temperature interconnection according to any one of claims 1 to 8, which is characterized by comprising the steps of adding the surface modified nano copper and the tin-based alloy powder into an organic carrier, homogenizing, stirring, grinding and homogenizing.
  10. 10. Use of the nano-copper composite solder for low temperature interconnect of any of claims 1-8 in power device package interconnect.

Description

Nano copper composite solder for low-temperature interconnection and preparation method and application thereof Technical Field The invention belongs to the technical field of electronic packaging, and particularly relates to a nano copper composite solder for low-temperature interconnection and a preparation method and application thereof. Background With the development of miniaturization, high density and multifunction of electronic devices, traditional tin-based solders have difficulty meeting increasing interconnection requirements, especially in the field of large-area interconnection scenes, such as power devices, LED packages, flexible electronics and the like. The high temperature welding is easy to damage the heat sensitive element, especially the traditional solder has high melting point, and the high temperature is easy to cause the performance of the heat sensitive element to be reduced or even to be invalid in the welding process. In addition, the traditional welding spots have poor reliability and are not resistant to thermal fatigue damage particularly in high-temperature service. Defects such as holes and cracks are easy to generate during large-area interconnection, and the reliability of welding spots and the service life of devices are influenced. Most importantly, the traditional solder has limited electric and heat conductivity, and is difficult to meet the heat dissipation and electric conduction requirements of high-power density devices. Nano copper is a technology that has been tried in recent years instead of nano silver. But the sintering temperature is higher than that of nano silver, the nano silver is easy to oxidize, copper oxide generated by oxidation can cause interconnection failure, and meanwhile, the electric conduction and heat conduction system and the reliability of the joint are obviously reduced. The sintering temperature of the nano copper composite solder in the prior art is mostly more than 250 ℃, the strength of the nano copper composite solder with the sintering temperature below 250 ℃ after sintering is lower, and the reliability of welding spots cannot be guaranteed. For example, chinese patent with publication number CN112756841B discloses a micro-nano composite silver-copper alloy soldering paste for low-temperature sintering interconnection and a preparation method thereof, wherein the preparation method comprises the steps of uniformly mixing an organic solvent, a thickener, a dispersing agent, a coupling agent and a defoaming agent in a certain proportion to be used as an organic carrier of the micro-nano composite silver-copper alloy soldering paste; and then uniformly mixing the nano silver-copper alloy and the micro silver particles prepared by the chemical reduction method with a certain amount of organic carriers. The technical scheme adopts the principle of solid solution alloy, copper atoms are doped in a silver phase to obtain silver-copper alloy particles with a single phase, the problem of copper oxidation is solved, meanwhile, the doping of copper atoms reduces the diffusion rate of atoms, the problem of massive volume shrinkage of pure nano soldering paste in the sintering process is solved, the cost is reduced, the yield is improved, and the method is suitable for mass production, however, the sintering temperature of the technical scheme is at least 250-300 ℃ and needs to be reduced. Chinese patent publication No. CN117862733a discloses a high thermal conductivity nano copper composite solder paste, its preparation method and application. The preparation method comprises the steps of dispersing the high-heat-conductivity nano-material in a copper salt mixed solution to obtain a dispersion liquid, obtaining a suspension of nano-copper particles and the high-heat-conductivity nano-material under the action of a reducing agent by the dispersion liquid, centrifugally drying the suspension to obtain high-heat-conductivity nano-copper composite particles, adding a thickening agent into the high-heat-conductivity nano-copper composite particles, and stirring and defoaming to obtain the high-heat-conductivity nano-copper composite soldering paste. According to the technical scheme, the high-heat-conductivity nano-copper composite soldering paste with good dispersibility is obtained by adding the high-heat-conductivity doped nano-material while the reducing agent and the copper salt undergo a reduction reaction, however, the sintering temperature of 250 ℃ can only be realized by the technical scheme, and the shearing strength of the soldering point of the technical scheme can only reach about 23 MPa. In addition, the technical scheme does not relate to the relevant test of the reliability of the welding spots. Disclosure of Invention In order to overcome the defects of the prior art, the invention aims to provide a nano copper composite solder for low-temperature interconnection, and a preparation method and application thereof. In order to achieve