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CN-122007710-A - Ultralow-thermal-resistance low-temperature welding material, preparation method and welding method

CN122007710ACN 122007710 ACN122007710 ACN 122007710ACN-122007710-A

Abstract

The application provides an ultralow thermal resistance low-temperature welding material, a preparation method and a welding method, which belong to the technical field of electronic packaging and thermal management materials, wherein solder comprises 70-85% of tin-bismuth alloy powder, 5-10% of gallium-based liquid metal and 5-25% of soldering flux, the tin-bismuth alloy powder comprises tin and bismuth, the gallium-based liquid metal comprises gallium and indium, and the soldering flux comprises modified rosin, dipropylene glycol and diethylene glycol dibutyl ether. The preparation method comprises the steps of preparing tin-bismuth alloy powder, gallium-based liquid metal and soldering flux, mixing the gallium-based liquid metal with the soldering flux, mechanically stirring, ultrasonically dispersing until the mixture is uniform, adding the tin-bismuth alloy powder into the mixture, mechanically stirring, and cooling to room temperature. During welding, tin and bismuth react with the base material to generate an IMC layer, and gallium and indium are filled in a welding cavity in a high-temperature melting state to generate a compact IMC interface. Interface thermal resistance is reduced, and compatibility, safety and connection reliability are improved.

Inventors

  • LIU BIN
  • JIA XIAO
  • ZHOU JINGZHI
  • XU MIN
  • CHEN LIN

Assignees

  • 中国科学院工程热物理研究所

Dates

Publication Date
20260512
Application Date
20260306

Claims (10)

  1. 1. The ultralow-thermal-resistance low-temperature welding material is characterized by comprising 70-85% of tin-bismuth alloy powder, 5-10% of gallium-based liquid metal and 5-25% of soldering flux, wherein the tin-bismuth alloy powder comprises tin and bismuth, the gallium-based liquid metal comprises gallium and indium, and the soldering flux comprises modified rosin, dipropylene glycol and diethylene glycol dibutyl ether.
  2. 2. The ultralow thermal resistance low-temperature welding material according to claim 1, wherein the ratio of tin to tin-bismuth alloy powder is 38-45%, and the ratio of bismuth to tin-bismuth alloy powder is 62-55%.
  3. 3. The ultralow thermal resistance low-temperature welding material according to claim 1, wherein the gallium is 60-80% in the gallium-based liquid metal and the indium is 20-40% in the gallium-based liquid metal.
  4. 4. The ultralow thermal resistance low-temperature welding material according to claim 1, wherein the modified rosin accounts for 40-60% of the soldering flux, the dipropylene glycol accounts for 20-30% of the soldering flux, and the diethylene glycol dibutyl ether accounts for 20-30% of the soldering flux.
  5. 5. The ultralow-thermal-resistance low-temperature welding material according to claim 1, wherein the granularity of the tin-bismuth alloy powder is 10-100 μm, and the droplet diameter of the gallium-based liquid metal is 20-50 μm.
  6. 6. A method for producing an ultralow thermal resistance low temperature welding material according to any one of claims 1 to 5, comprising: Adding the tin metal block and the bismuth metal block into an inert gas protection smelting furnace according to a proportion, heating to melt, preserving heat for a preset time, uniformly stirring, cooling to room temperature, and crushing into tin-bismuth alloy powder; preparing gallium-based liquid metal, namely mixing gallium and indium according to a proportion, and stirring at room temperature until the gallium and the indium are completely fused; preparing a soldering flux, namely mixing and stirring modified rosin, dipropylene glycol and diethylene glycol dibutyl ether in proportion, and dispersing the mixture through a three-roller grinder to obtain the soldering flux with uniform dispersion; The solder compounding and dispersing process includes mixing gallium-base liquid metal and soldering flux, the first mechanical stirring, ultrasonic dispersing to mix gallium-base liquid metal and soldering flux, adding tin-bismuth alloy powder into the mixture, the second mechanical stirring, and cooling to room temperature to obtain the soldering material.
  7. 7. The method for producing an ultralow thermal resistance low temperature solder material according to claim 6, wherein in the step of producing the tin-bismuth alloy powder, the heating temperature is 200 to 250 ℃, and the preset time for heat preservation is 30 to 60 minutes.
  8. 8. The method for producing an ultralow thermal resistance low temperature solder material according to claim 6, wherein in the step of producing the flux, the temperature of mixing and stirring is 100 ℃.
  9. 9. The method for preparing an ultralow thermal resistance low-temperature welding material according to claim 6, wherein in the steps of compounding and dispersing the solder, the first mechanical stirring time is 30-60 minutes at 50-80 ℃, the second mechanical stirring time is 30-60 minutes at 80-100 ℃, and the ultrasonic dispersing power is 100-300W for 15-30 minutes.
  10. 10. A method of soldering an ultra-low thermal resistance low temperature soldering material according to any one of claims 1 to 5, comprising: pretreating a substrate; placing the welding material between the base materials, heating to 100-180 ℃ in an inert gas or air atmosphere, and preserving heat for 3-10 minutes; in the welding process, tin and bismuth in the tin-bismuth alloy powder react with the base material to generate an IMC layer, gallium and indium in the gallium-based liquid metal are filled in a welding cavity in a high-temperature melting state to generate a compact IMC interface, and finally, a metallurgical bonding structure of the base material-the IMC layer-the liquid metal-the IMC layer-the base material is formed.

Description

Ultralow-thermal-resistance low-temperature welding material, preparation method and welding method Technical Field The application relates to the technical field of electronic packaging and thermal management materials, in particular to an ultralow-thermal-resistance low-temperature welding material, a preparation method and a welding method. Background The traditional tin (Sn) bismuth (Bi) alloy soldering tin realizes low-temperature soldering by relying on Sn-Bi eutectic phase (the melting point is about 138 ℃), but has small and uneven generation amount of interfacial intermetallic compounds with common radiator base materials such as copper, aluminum and the like, and is easy to generate soldering voids, so that the thermal resistance is higher (usually 0.3-0.5K.cm 2/W), and interfacial peeling is easy to occur after long-term use. Pure liquid metal (such as gallium-based alloy) has excellent heat conductivity coefficient (more than or equal to 40W/(m.K)), but has two major problems when directly used for connection, namely strong reaction with a base material (aluminum) to cause interface embrittlement and corrosion, and strong liquid metal fluidity, easy leakage and poor compatibility with electronic devices. Therefore, developing a solder material with low-temperature welding characteristics, stable IMC interface, ultra-low thermal resistance and high connection reliability becomes a key requirement for solving the high-efficiency heat dissipation of electronic devices. Disclosure of Invention In view of the above, the embodiments of the present application provide an ultralow thermal resistance low temperature soldering material, a preparation method and a soldering method, which are used for a low temperature solder material for connecting a radiator and a heat source (such as a chip and a power device), so as to solve the technical problems of high thermal resistance, unstable interface bonding, and easy corrosion of a substrate and leakage of pure liquid metal in the conventional tin-bismuth alloy solder in the prior art. In a first aspect, the embodiment of the application provides an ultralow-thermal-resistance low-temperature welding material, which comprises, by weight, 70-85% of tin-bismuth alloy powder, 5-10% of gallium-based liquid metal and 5-25% of soldering flux, wherein the tin-bismuth alloy powder comprises tin and bismuth, the gallium-based liquid metal comprises gallium and indium, and the soldering flux comprises modified rosin, dipropylene glycol and diethylene glycol dibutyl ether. According to a specific implementation mode of the embodiment of the application, the proportion of tin in the tin-bismuth alloy powder is 38-45%, and the proportion of bismuth in the tin-bismuth alloy powder is 62-55%. According to a specific implementation mode of the embodiment of the application, the proportion of gallium in the gallium-based liquid metal is 60-80%, and the proportion of indium in the gallium-based liquid metal is 20-40%. According to a specific implementation mode of the embodiment of the application, the proportion of the modified rosin in the soldering flux is 40-60%, the proportion of dipropylene glycol in the soldering flux is 20-30%, and the proportion of diethylene glycol dibutyl ether in the soldering flux is 20-30%. According to a specific implementation mode of the embodiment of the application, the granularity of the tin-bismuth alloy powder is 10-100 mu m, and the droplet diameter of the gallium-based liquid metal is 20-50 mu m. In a second aspect, an embodiment of the present application further provides a method for preparing the ultralow thermal resistance low temperature welding material according to any one of the embodiments of the first aspect, where the method includes: Adding the tin metal block and the bismuth metal block into an inert gas protection smelting furnace according to a proportion, heating to melt, preserving heat for a preset time, uniformly stirring, cooling to room temperature, and crushing into tin-bismuth alloy powder; preparing gallium-based liquid metal, namely mixing gallium and indium according to a proportion, and stirring at room temperature until the gallium and the indium are completely fused; preparing a soldering flux, namely mixing and stirring modified rosin, dipropylene glycol and diethylene glycol dibutyl ether in proportion, and dispersing the mixture through a three-roller grinder to obtain the soldering flux with uniform dispersion; The solder compounding and dispersing process includes mixing gallium-base liquid metal and soldering flux, the first mechanical stirring, ultrasonic dispersing to mix gallium-base liquid metal and soldering flux, adding tin-bismuth alloy powder into the mixture, the second mechanical stirring, and cooling to room temperature to obtain the soldering material. According to a specific implementation manner of the embodiment of the application, in the step of preparing the tin-bismuth alloy powder, t