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High-melting point lead-free solder and production technique thereof

A technology of lead-free solder and production process, which is applied in the direction of welding/cutting medium/material, welding medium, manufacturing tools, etc., and can solve the problems of high price, low precious metal content, and high price

Inactive Publication Date: 2008-12-31
GUANGZHOU SOLDERWELL ADVANCED MATERIALS +1
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Problems solved by technology

[0003] Existing melting point has two kinds of lead-free solders more than 260 ℃, and a kind of is well-known expensive Au80 (wt%)-Sn20 (wt%) solder, because the mass percent of this solder gold is about 80%, As a result, its price is very expensive, and its application range is greatly limited
[0004] The other is the high-melting-point lead-free solder disclosed in patent 01823276.0, whose alloy composition is 2wt%-18wt% of Ag and 98wt%-82wt% of Bi. Compared with the former high-melting-point lead-free solder, this The price of the solder disclosed in the patent has been significantly reduced; however, since silver is also a precious metal, and its content in the solder may reach 18wt% at the highest and 2wt% at the lowest, in terms of cost, This high-melting-point lead-free solder is not an ideal material, so the industry urgently needs a high-melting-point lead-free solder with low precious metal content or even no precious metal

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  • High-melting point lead-free solder and production technique thereof

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[0014] The high-melting-point lead-free solder of the present invention comprises a Bi-based alloy, the content of Bi in the alloy is 95wt%-98wt%, and it is made by alloying after adding Sb, wherein the content of Sb is 2wt%-5wt%. The solid phase point of the prepared solder is not lower than 270°C, and the liquid phase point is not higher than 310°C. It can replace leaded solder for chip soldering and IC package soldering.

[0015] Since the Bi-Sb alloy belongs to the infinite miscible alloy, the solid and liquid phase points of the alloy increase with the increase of the Sb content. The binary alloy phase diagram shown in Figure 1 is obtained through experiments. When the Sb content is equal to 2wt%, Its lowest solid phase point is higher than 270°C. When the Sb content is equal to 5wt%, its lowest liquid phase point is lower than 310°C. From this we can conclude that the solid phase point temperature of the solder is not lower than 270°C, and its liquid phase The point is ...

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Abstract

The invention provides an alloy contained in a high melting point and lead-free solder. The alloy consists of 2wt% - 5wt% of Sb and 98wt% - 95wt% of Bi, the solidus temperature of the alloy is not lower than 270 DEG C, while the liquidus temperature of the alloy is not higher than 310 DEG C. As the Bi-Sb alloy belongs to an ultimate mutual soluble alloy, the solidus point and the liquidus point of the alloy increase with the increase of Sb content. Compared with the conventional Pb-10Sn solder, the high-melting point and lead-free solder is more environmentally friendly. The alloy can be further added with a proper amount of silver when the solder is made into a welding collar in order to improve the weldability of the solder.

Description

technical field [0001] The invention relates to a lead-free solder, in particular to a high melting point lead-free solder for chip welding and IC package welding. Background technique [0002] Chip soldering and IC packaging soldering require the melting point of the solder to be higher than 260°C. A low melting point of the solder will cause later soldering to damage the solder joints that were soldered earlier, thereby affecting soldering quality. Generally, the high melting point solder used for chip soldering and IC package soldering is leaded high melting point solder. Since this solder contains lead elements that are harmful to the human body, it will be banned in the next few years, so everyone is looking for it. Lead-free solder that replaces leaded high-melting point solder. [0003] Existing melting point has two kinds of lead-free solders more than 260 ℃, and a kind of is well-known expensive Au80 (wt%)-Sn20 (wt%) solder, because the mass percent of this solder ...

Claims

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Application Information

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IPC IPC(8): B23K35/16C22C1/02
CPCC22C12/00B23K35/264
Inventor 蔡烈松陈明汉叶富华邹家炎杜昆
Owner GUANGZHOU SOLDERWELL ADVANCED MATERIALS
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