Lead free tin cream and preparation process

Abstract

The invention provides a lead-free solder paste comprising the tin base alloy welding powder and the pewter. The components of the tin base alloy welding powder are as follows (in % by weight): Sn 91-99, Cu 0.5-3, Ag 0.5-6; the components of the pewter are as follows (in % by weight): mixed alcohol ether 25-40, natural colophony 50-70, natural vegetable oil thixotropic agent 5-15, organic acid 0.5-2.0, additives. The lead-free solder paste preparing process includes the following steps: mixing the components of the pewter in proportion, standing to room temperature, putting the pewter in a refrigerating chamber with the temperature of 1 C. to 10 C. for 48 hours; mixing the pewter and the tin base alloy welding powder in the ratio of 1 to 9 in the vacuum dispersion machine, putting the mixture in the package bottle and storing hermetically with the temperature of between 5 C. and 10 C.. The lead-free solder paste is characterized by good surface activity, moderated viscosity, and no smell.

Description

【Technical field】 [0001] The invention relates to a solder paste, in particular to a lead-free solder paste used in the soldering of electronic products and a preparation method thereof. 【Background technique】 [0002] With the development of the electronics industry, the electronic assembly is becoming more and more complex and sophisticated, and the types of solder paste are also increasing. The selection of suitable solder paste is a scientific and systematic project. The solder paste selected by engineers should not only meet the needs of production, At the same time, we should also pay attention to the occurrence of side effects and avoid adverse consequences. [0003] The existing lead-free solder paste is generally used for soldering electronic products. It is composed of solder powder and flux. It has no moderate viscosity, no good diffusivity and bonding, and the adhesion and printability are not very ideal. , After printing, it cannot maintain its viscosity for a ...

AI Technical Summary

Problems solved by technology

[0003] The existing lead-free solder paste is generally used for soldering electronic products. It is composed of solder powder and flux. It has no moderate viscosity, no good diffusivity and bonding, and the adhesion and printability are not very ideal. After printing, it cannot maintain its viscosity for a long time, which reduces the efficiency of the surface mount process; and it is easy to collapse, easy to splash, corrosive and produce irritating odor during brazing, which affects the health of users and the environment.

In the process of welding, there are shortcomings such as not full and bright solder joints, obvious residues after welding and darker residues, and organic solvents must be used to clean them.