Silver-free tin-bismuth-copper leadless solder and preparation method

A lead-free solder, tin-bismuth technology, used in welding equipment, welding/cutting media/materials, welding media, etc., can solve problems such as unsatisfactory oxidation corrosion resistance, lowering the melting point of solder, and increasing the cost of solder. , to achieve good welding wettability and oxidation resistance, reduce high temperature side effects, and reduce material costs

Active Publication Date: 2007-03-14
BEIJING COMPO ADVANCED TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] Several major alloy systems currently developed for lead-free solder: Sn-Ag system (including Sn-Ag-Cu system), Sn-Cu system, Sn-Zn system, Sn-Bi system, if measured according to the user's value equation, all There are inherent defects: Sn-Ag solder can provide good reliability and process yield, but it contains a lot of Ag, the cost of Ag is high, and the oxidation and corrosion resistance is not satisfactory; Sn-Cu eutectic solder and its modification The alloys are cheap and easy to obtain, but there are certain problems in soldering reliability, process yield and oxidation resistance; and the most serious problem is that the melting point of these two systems of solder is much higher than that of the original general-purpose Sn-Pb solder (about 34 ~44℃), which is a huge test for the equipment usually used for Sn-Pb soldering, and it is also the biggest obstacle for the lead-free process
Although Sn-Zn solder has obvious advantages in terms of melting point and cost, it is obviously at a disadvantage due to...

Method used

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  • Silver-free tin-bismuth-copper leadless solder and preparation method
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  • Silver-free tin-bismuth-copper leadless solder and preparation method

Examples

Experimental program
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Effect test

Embodiment 1

[0029] Preparation of Sn-Bi8-Cu0.5: Prepare 5.0 kg of Sn-Cu10 master alloy in a vacuum medium frequency induction melting furnace. During the preparation process: ① Melt the weighed pure Sn to 650 ° C in a vacuum induction melting furnace Add the weighed pure Cu flakes, stir and melt until the furnace temperature is 500-600°C, stir and keep warm for 10 minutes, pour into a square ingot to prepare a Sn-Cu10 master alloy; ② Analyze the uniformity of the composition of the master alloy. Weigh 5g of Sn-Cu10 master alloy, 8g of pure Bi, and 87g of pure Sn. Then melt pure Sn in a resistance furnace and heat it to 300°C, add weighed pure Bi and Sn-Cu10 master alloy in turn, heat to 300°C and keep it for 10 minutes, pour it into a cylindrical mold, and wait until the ingot is completely solidified. Remelt the ingot to 250°C for 10 minutes, pull out the oxidized slag on the surface, and pour it into the ingot mold to make an ingot for use. The ingot can be directly used as a solder ing...

Embodiment 2

[0031] Preparation of Sn-Bi15-Cu0.1: The preparation of the master alloy is the same as Example 1. Weigh 1.0g of Sn-Cu10 master alloy, 15g of pure Bi, and 84g of pure Sn. Then melt pure Sn in a resistance furnace and heat it to 300°C, add weighed pure Bi and Sn-Cu10 master alloy in turn, heat to 300°C and keep it for 10 minutes, pour it into a cylindrical mold, and wait until the ingot is completely solidified Remelt the ingot to 250°C and keep it warm for 10 minutes, pull out the surface oxide slag, and pour it into a bar mold to make a lead-free solder bar.

Embodiment 3

[0033]Preparation of Sn-Bi58-Cu3.0: The preparation of the master alloy is the same as Example 1. Weigh 30g of Sn-Cu10 master alloy, 58g of pure Bi, and 12g of pure Sn. Then melt pure Sn in a resistance furnace and heat it to 300°C, add weighed pure Bi and Sn-Cu10 master alloy in turn, heat to 300°C and keep it for 10 minutes, pour it into a cylindrical mold, and wait until the ingot is completely solidified. The ingot was remelted to 250°C for 10 minutes, and then poured into a flat mold to make a lead-free solder sheet.

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PUM

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Abstract

The invention relates to a tin-base leadless solder without silver, and relative production. Wherein, it comprises Bi at 7.5-60% (without 7.5%), Cu at 0.1-3.0%, and the left is tin; and it also can contain Zn, Ni, P, Ge, Ga, In, Al, La, Ce, Sb, Cr, Fe, Mn, or Co while the total amount of micro alloy element is not higher than 1.0%. And the production comprises that in protective gas or vacuum, smelting middle alloy Sn-Cu10; then smelting into leadless solder alloy ingot which can be used as solder directly or be made into bar band, wire plate or powder. The inventive solder has low cost while its fusion point can be controlled between 140 and 230Deg. C. And it has strong anti-oxidization and anti-corrosion properties.

Description

technical field [0001] The invention relates to the technical field of manufacturing tin-based lead-free solder, in particular to a silver-free tin-bismuth-copper-based lead-free solder and a preparation method thereof. Background technique [0002] Solder is widely used in connecting materials such as electronic appliances. However, as a new type of lead-free electronic packaging solder, it should have good process performance (low melting point, good wettability, good corrosion and oxidation resistance, good mechanical properties, electrical conductivity Good), high process yield (fast spreading speed, high welding yield, high slag formation rate), good reliability of solder joints (high joint strength of solder joints, good creep resistance), easy operation, and low cost. [0003] Several major alloy systems currently developed for lead-free solder: Sn-Ag system (including Sn-Ag-Cu system), Sn-Cu system, Sn-Zn system, Sn-Bi system, if measured according to the user's valu...

Claims

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Application Information

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IPC IPC(8): B23K35/26C22C1/03B23K35/40
Inventor 张富文胡强贺会军徐骏朱学新赵朝辉
Owner BEIJING COMPO ADVANCED TECH
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