Lead-free high-temperature soft solder and preparation method thereof

Abstract

The invention relates to a lead-free high-temperature soft solder which is non-toxic and pollution-free and can replace high-lead solders with poor environment friendliness and Au-based solders with expensive price. Each performance of the lead-free high-temperature soft solder meets the requirement of electronic packaging. By taking the total weight of the solder as reference, the lead-free high-temperature soft solder comprises the following components in percentage by weight: 5 to 10 percent of Sb, 5.1 to 8 percent of Cu, 0.001 to 0.1 percent of In, 0.01 to 0.5 percent of Ni, 0.02 to 1 percent of X and the balance of Sn, wherein X is Ga and / or mixed rare earth. The method for preparing the solder comprises the following steps of: mixing the components, putting the mixed components into a smelting furnace, heating to the temperature of between 850 and 900 DEG C, keeping the temperature for 1 to 2 hours, so that the components are melted completely, stirring fully before discharging, and pouring and solidifying to obtain the solder. The lead-free high-temperature soft solder is suitable for the electronic packaging.

Description

technical field [0001] The invention relates to a lead-free high-temperature solder and a preparation method thereof, belonging to the technical field of soldering. Background technique [0002] High Pb solders (Pb content>85wt.%) are widely used in the high temperature field of microelectronic packaging. However, with the improvement of people's awareness of environmental protection and the increasing concern for their own health, countries have successively legislated to limit the use of Pb in the microelectronics industry. At present, the low- and medium-temperature lead-free solders that replace Pb-containing solders in the world have basically matured and entered the stage of large-scale industrial application. However, there is currently no suitable lead-free substitute for high-Pb solder in high-temperature applications, so this high-Pb solder is still exempt in the European Union's "RoHS" directive. Although high-lead solder is temporarily exempted, due to vario...

AI Technical Summary

Problems solved by technology

However, the alloy has poor performance, such as high brittleness, poor processability and weak bonding strength with the matrix, so there are many problems for practical application

[0005] 3) Zn-Al alloy: In general, Zn-based alloys have insufficient ductility, poor processability, difficulty in processing into wires or strips, poor stress relaxation ability, and easy oxidation resulting in poor wettability. These properties are very important. This limits the application of the alloy to a certain extent

[0006] 4) Sn-Sb alloy: There are a series of problems such as high brittleness, poor processability, weak bonding strength with the substrate, wide solid-liquidus line interval, and poor wettability on Cu and Ni substrates.

However, this alloy still has the problem of fast corrosion of Cu or Ni substrate pads; moreover, this series of alloys has poor oxidation resistance, and a large amount of tin slag will be produced during high temperature welding.

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