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Bismuthstan silver system lead-free solder

A lead-free solder and silver-based technology, applied in the direction of welding/cutting medium/material, welding medium, welding equipment, etc., can solve the problems of increased production cost of solder

Inactive Publication Date: 2012-07-18
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

But eutectic SAC alloy has higher Ag content (3.0~4.0wt.%), and the raw material price of Ag is about about 30 times of Sn and Bi, and this directly causes the increase of solder production cost; And eutectic SAC alloy The melting point is around 217°C, much higher than the 183°C of traditional Sn-37Pb solder

Method used

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Examples

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Effect test

Embodiment 1

[0017] Take 98.85 grams of tin with a purity of not less than 99.99%, 1.0 grams of bismuth, 0.1 grams of silver, and 0.05 grams of zinc for mixing, heat the mixture to 1100 ° C in a vacuum melting furnace under the protection of argon, and add magnetic stirring. Make the composition of the alloy uniform, and then cool the water-cooled copper mold. Then the alloy is turned over and reheated to 500°C to melt, and at the same time, it is magnetically stirred and cooled by a water-cooled copper mold, and this is repeated at least three times to obtain a solder alloy; the composition is 1.0% Bi-0.1% Ag-0.05% Zn and the matrix is ​​Sn solder alloy. Its microstructure is as figure 1 As shown, the particles are Ag 3 Sn phase, the matrix is ​​Sn.

Embodiment 2

[0019] Take 93.5 grams of tin, 4.0 grams of bismuth, 0.5 grams of silver, 1.0 grams of zinc, and 1.0 grams of copper with a purity of not less than 99.99%, mix them, and heat the mixture to 1100 ° C in a vacuum melting furnace protected by argon. Add magnetic stirring to make the alloy composition uniform, and then cool down in a water-cooled copper mold. Then turn the alloy over and reheat to 500°C to melt, and at the same time add magnetic stirring and water-cooled copper mold to cool down, so repeat at least three times to obtain a solder alloy; the composition is 4.0%Bi-0.5%Ag-1.0%Zn-1.0%Cu The matrix is ​​Sn solder alloy. Its microstructure is as figure 2 As shown, the particles are Ag 3 Sn phase and Cu 6 sn 5 phase, the white particles are Bi, and the matrix is ​​Sn.

Embodiment 3

[0021] Mix tin (98.8-x) gram, bismuth x gram (x=1.0, 2.0, 3.0 or 4.0 gram), silver 0.3 gram, and zinc 0.9 gram with a purity of not less than 99.99%, and place the mixture under argon protection It is heated to 1100°C in the vacuum melting furnace under it, and then magnetically stirred to make the alloy composition uniform, and then the water-cooled copper mold is cooled. The alloy is turned over and reheated to 500°C for melting, while magnetic stirring and cooling of the water-cooled copper mold are performed, so that the solder alloy is obtained at least three times; x%Bi-0.3%Ag-0.9Zn% (x=1.0, 2.0, 3.0 and 4.0) The substrate is a Sn solder alloy.

[0022] Among them, the microstructure of Sn-2.0%Bi-0.3%Ag-0.9%Zn solder alloy is as follows image 3 As shown, the particles are Ag 3 In the Sn phase, the white enrichment area is Bi, and the matrix is ​​Sn. The melting curve and stress-strain of Sn-x%Bi-0.3%Ag-0.9%Zn lead-free solder alloy are shown as Figure 4 and Figur...

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Abstract

The invention relates to bismuthstan silver system lead-free solder, which is characterized in that components of the solder include, in weight percent, 1.0-4.0% of Bi (bismuth), 0.1-0.5% of Ag (silver), 0.05-1.0% of Zn (zinc), 0-1.0% of Cu (copper) and the balance Sn (stannum) (the purity of elements is not lower than 99.99%). Sn-Bi-Ag system solder alloy has a low melting point, the lowest melting point is about 205 DEG C, the alloy has high tensile strength without loss of ductility, the maximum tensile strength reaches about 70MPa, and the content of the Ag is low, so that the cost of the solder is greatly reduced. Besides, the lead-free solder can replace traditional Sn-37% Pb (lead) solder.

Description

technical field [0001] The invention relates to lead-free electronic packaging technology, in particular to a tin-bismuth-silver 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. The toxic heavy metal "Pb" h...

Claims

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Application Information

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IPC IPC(8): B23K35/26
Inventor 刘永长王珣董治中
Owner TIANJIN UNIV
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