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Sn-Ag-Cu system lead-free soldering paste

A lead-free solder paste and flux technology, applied in the direction of welding medium, welding equipment, welding/cutting medium/material, etc., can solve the problems of function deterioration, unusability, thermal damage of electronic parts, etc., and achieve the effect of long pot life

Inactive Publication Date: 2014-02-05
NINGBO YINZHOU HENGXUN ELECTRONICS MATERIALS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

When electronic parts have low heat resistance, sometimes electronic parts suffer from heat damage and cause functional deterioration
Furthermore, if connecting parts, such as connectors, are mounted on the soldering surface of a printed circuit board, there is a problem that molten solder penetrates into the holes of the connectors, which can no longer be used after that

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0032] Example 1 is according to the present invention and a comparative example, in which the flux is prepared using maleic rosin, polymerized rosin, hydrogenated rosin and phenol-modified rosin. Flux is made by adding rosin to a solvent and heating it to melt the rosin. The heating was then turned off and cooled to about 100°C. When the temperature of the liquid reaches about 100°C, the thixotropic agent is added and melted, followed by the activator and stirred to dissolve. After all the materials are dissolved, the flux is solidified by water cooling or isocooling.

example 2

[0033] Example 2 is mixing Sn-Ag based solder powder with the flux prepared in Example 1 to prepare solder paste. The flux content of each solder paste is a reference value of 10.5% (mass), and the flux content can be adjusted until the viscosity is about 200 Pa per second. Each solder paste was left at room temperature for one day, and then its viscosity was measured. In addition, each solder paste was preserved for 60 days in a storage room set at a constant temperature of 25° C., and then its viscosity was measured. The change over time of each solder paste can be compared and pot life can be determined.

example 3

[0034] Example 3 is a comparison of the wettability and color 2 of the solder paste residue produced in Example 2. Measure the temperature of the solder bath to be 250+3°C. The color of the solder paste residue is determined by the printed solder paste. Printed using a metal mask with a thickness of 0.2mm and a hole with a diameter of 6.5mm on a tough copper plate measuring 5.0mm x 10.0mm x 0.5mm and then reflowed using a solder bath at 250+3°C . The color of the flux residue can be compared after cooling.

[0035] Summarizing the above, the solder powder of the alloy has at least 1% by mass of Sb added to the Sn-Ag alloy or Sn-Ag-Cu-based alloy, thereby suppressing the change in viscosity when maleic rosin is used. However, when the Sb content is less than 1% by mass, it cannot suppress the change in viscosity, and when the addition of Sb exceeds 8% by mass, the wettability of the solder paste will be inhibited. Furthermore, according to the present invention, i...

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PUM

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Abstract

The invention discloses a Sn-Ag-Cu system lead-free soldering paste, which is characterized by comprising 5-45% (mass) of maleated rosin soldering flux and solder alloy powder mixed with soldering flux, wherein the powder comprises Sn, Ag and 1-8% (mass) of Sb; the solder alloy powder comprises 1.0-4.0% (mass) of Ag, 0.4-1.0% (mass) of Cu, 1-8% (mass) of Sb and the balance of Sn. The solder alloy powder also comprises one of nickel, cobalt and iron, and the total content is lower than 0.5% (mass). The soldering flux comprises more than one kind of haloid acid of which the content is larger than 0-2% (mass), and the use level of organohalogen compound is 0-3% (mass). The Sn-Ag-Cu system lead-free soldering paste has the beneficial effects that the cleaning is avoided, the soldering paste cannot easily change as time goes on, and the soldering paste is suitable for being used for a longer period.

Description

technical field [0001] The invention relates to a solder paste for welding electronic equipment, in particular to a lead-free solder paste. Background technique [0002] As is well known, soldering methods for electronic parts include soldering with a soldering iron, fluid soldering, reflow soldering, and the like. Soldering with a soldering iron is one of these soldering methods, where a flux-filled wire is placed on the part to be soldered, and the solder wire is heated and melted with a soldering iron. However, when soldering is performed by the soldering iron soldering method, a certain part is soldered at one time, so it has a problem of productivity and is not suitable for mass production. Whereas, in the flow soldering method, the soldering surface of the printed circuit board is brought into contact with molten solder to facilitate soldering. Its excellent productivity is that the entire printed circuit board can be soldered in a single operation. However, with ...

Claims

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Application Information

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IPC IPC(8): B23K35/26B23K35/363
CPCB23K35/262B23K35/3613B23K35/362
Inventor 王伟德
Owner NINGBO YINZHOU HENGXUN ELECTRONICS MATERIALS
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