Tin-bismuth-silver series lead-free solder and preparation method

A lead-free solder, tin-bismuth technology, used in welding equipment, welding/cutting media/materials, welding media, etc., can solve the problems of declining product competitiveness and increasing solder production costs, and achieve low product cost and high tensile strength. The effect of strength, good development prospects

Inactive Publication Date: 2010-10-20
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

But the Sn-Ag-Cu alloy has a higher Ag content, and the high price of silver directly leads to the increase of solder production cost and the decline of product competitiveness

Method used

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  • Tin-bismuth-silver series lead-free solder and preparation method
  • Tin-bismuth-silver series lead-free solder and preparation method
  • Tin-bismuth-silver series lead-free solder and preparation method

Examples

Experimental program
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Effect test

Embodiment 1

[0021] Heat tin, bismuth and silver with a purity of 99.99% in a mass ratio of 98.9:1:0.1 in a vacuum melting furnace under the protection of argon to 1100°C to melt, and at the same time add magnetic stirring to make the alloy composition uniform, and then water-cooled and solidified . Then the alloy is turned over and reheated to 500° C. to melt, and at the same time, it is magnetically stirred and water-cooled, so that the Sn-1%Bi-0.1%Ag lead-free solder is obtained by repeating this at least four times. Its microstructure is as figure 1 As shown, the particles are Ag 3 Sn phase.

Embodiment 2

[0023] The tin, bismuth, and silver with a purity of 99.99% are heated to 1100°C in a vacuum melting furnace under the protection of argon in a mass ratio of 93:5:2, and are magnetically stirred at the same time to make the alloy composition uniform, and then water-cooled and solidified . Then the alloy is turned over and reheated to 500° C. to melt, and at the same time, it is magnetically stirred and water-cooled, so that the Sn-5%Bi-2%Ag lead-free solder is obtained by repeating this process at least four times. Its microstructure is as figure 2 As shown, the particles are Ag 3 Sn phase, white particles are Bi, the alloy has a lower melting point, higher microhardness and tensile strength.

Embodiment 3

[0025] The tin, bismuth, silver, zinc, and indium with a purity of 99.99% are heated to 1100 ° C in a vacuum melting furnace under the protection of argon in a mass ratio of 95.4: 2: 0.5: 2: 0.1, and are magnetically stirred at the same time. Make the alloy composition uniform, and then freeze and solidify. The alloy is turned over and reheated to 500° C. to melt, magnetically stirred and water-cooled at the same time, thus repeated at least four times to obtain Sn-2%Bi-0.5%Ag-2%Zn-0.1%In lead-free solder. Its microstructure is as image 3 As shown, the particles are Ag 3 Sn phase and Ag-Zn phase, the white enrichment area is Bi.

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Abstract

The invention relates to a tin-bismuth-silver series lead-free solder, wherein the solder comprises the following components in mass percentage: the mass ratio of tin to bismuth to silver with the purity of 99.99% is 98.9 to 93:1 to 5:0.1 to 2. At least one or more of 0 to 2 percent of zinc, 0 to 2 percent of copper, 0 to 1 percent of aluminum, 0 to 1 percent of indium, 0 to 1 percent of rare-earth element, 0 to 1 percent of gallium or 0 to 1 percent of phosphorus can also be added. A preparation method comprises the following steps: proportionally preparing raw materials, heating to the temperature of 500 to 1300 DEG C for melting in a vacuum smelting furnace under argon protection, simultaneously carrying out magnetic stirring to enable alloy components to be uniform, and then carrying out water-cooling solidification; then overturning an alloy, then reheating to the temperature of 300 to 600 DEG C for melting, simultaneously carrying out magnetic stirring and water cooling, and repeating for at least five times. On the premise of ensuring the industrial application thereof, the solder alloy with low silver content has lower product cost, and the alloy has lower melting temperature, higher tensile strength and higher microhardness.

Description

technical field [0001] The invention relates to lead-free electronic packaging technology, in particular to a tin-bismuth-silver low-cost and high-performance lead-free solder. Background technique [0002] Since the beginning of the 21st century, with the continuous rapid development of the electronics industry and the increasingly serious problem of electronic waste, the issue of green manufacturing in the electronics industry has attracted more and more attention. Various laws and regulations related to green electronic manufacturing and green electronic products formulated by governments based on public interests and public opinion play a decisive role in promoting the "green" process. It mainly includes green electronic design, green electronic materials, green electronic packaging and technology, etc. Among them, green electronic packaging materials are very important and currently the most researched, that is, lead-free and halogen-free electronic packaging materials....

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B23K35/32B23K35/40
Inventor 高志明董明杰王珣刘永长
Owner TIANJIN UNIV
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