Stannum-copper binary alloy leadless solder paste

A lead-free solder paste, binary alloy technology, applied in welding media, welding equipment, metal processing equipment, etc., can solve the problems of low reliability of solder joints and damage to PCB components

Inactive Publication Date: 2008-09-24
CHANGSHA TAIHUI NETWORK TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] In order to overcome the low melting point of low-temperature solder paste made of bismuth-tin binary eutectic alloy Bi48Sn42 solder powder, the solder joints formed have low reliability during use, and tin-silver-copper, tin-silver-bismuth High-temperature solder paste made of multi-component alloy solder powder such as tin-copper may easily cause damage to PCB boards and components during solder paste welding. Lead Solder Paste

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0006] Embodiment 1: The solder powder in the lead-free solder paste is made of bismuth-tin binary eutectic alloy Bi48.Sn42 alloy solder powder and tin-copper binary alloy solder powder, plus flux. The mass percentage of bismuth-tin binary eutectic alloy solder powder is 81%, the mass percentage of tin-copper binary alloy solder powder is 18.8%, and the mass percentage of flux is 0.2%. The resulting lead-free solder paste has a peak reflow temperature of 210°C.

Embodiment 2

[0007] Embodiment 2: The solder powder in the lead-free solder paste is made of bismuth-tin binary eutectic alloy Bi48.Sn42 alloy solder powder and tin-copper binary alloy solder powder, plus flux. The mass percentage of bismuth-tin binary eutectic alloy solder powder is 89%, the mass percentage of tin-copper binary alloy solder powder is 10.9%, and the mass percentage of flux is 0.1%. The resulting lead-free solder paste had a peak reflow temperature of 206°C.

Embodiment 3

[0008] Embodiment 3: The solder powder in the lead-free solder paste is made of bismuth-tin binary eutectic alloy Bi48.Sn42 alloy solder powder and tin-copper binary alloy solder powder, plus flux. The mass percentage of bismuth-tin binary eutectic alloy solder powder is 85%, the mass percentage of tin-copper binary alloy solder powder is 14.5%, and the mass percentage of flux is 0.5%. The resulting lead-free solder paste had a peak reflow temperature of 206°C.

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PUM

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Abstract

The invention relates to a lead-free soldering paste. Alloy welding powder is made to the soldering paste through mixing bismuth-tin binary eutectic alloy welding powder Bi48Sn42 and tin-copper binary eutectic alloy welding powder which are in the mixture ratio of 20 to 60:80 to 40 and adding scaling powder. The alloy welding powder is made up of the bismuth-tin binary eutectic alloy welding powder Bi48Sn42 which takes the mass percent of 80 to 90 percent, and the tin-copper binary eutectic alloy welding powder takes the mass percent of 10 to 20 percent. The lead-free soldering paste keeps the peak value temperature between 210 to 220 DEG C in reflow soldering process, greatly reducing the peak value temperature and the possibility for damaging a breadboard and an element device.

Description

technical field [0001] The invention relates to a lead-free solder paste, in particular to a lead-free solder paste used in the surface mounting process of electronic products. Background technique [0002] In the surface mounting process of electronic products, lead-containing solder paste made of tin-lead alloy powder is widely used at present, and lead is harmful to the environment and does not meet environmental protection requirements. At present, the most common lead-free solder paste The tin-silver-copper (SnAgCu) alloy system is mostly used. At the same time, tin-silver, tin-silver-bismuth, tin-copper, and tin-copper are alloy systems composed of a small amount of transition metal elements such as nickel and cobalt. However, the melting points of these alloys are above 210°C, and the reflow temperature is higher. Such a high operating temperature often causes damage to circuit boards and components. The low-temperature solder paste made of bismuth-tin binary eutec...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B23K35/24B23K35/26
Inventor 谭周成莫力黄劲松
Owner CHANGSHA TAIHUI NETWORK TECH
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