Flux paste special for unleaded tin-bismuth solder and preparation method thereof

Abstract

The invention discloses flux paste special for unleaded tin-bismuth solder. The flux paste special for the unleaded tin-bismuth solder comprises, by weight, 10-20 parts of hydrogenated rosin, 5-10 parts of disproportionated rosin, 10-15 parts of dimer rosin, 5-10 parts of tetrahydrofurfuryl alcohol, 5-10 parts of pentaerythritol, 5-8 parts of butyl cellosolve, 5-8 parts of octyl ether, 5-8 parts of dibasic acid esters, 2-5 parts of phthalic acid dibutyl esters, 2-3 parts of oleyl alcohol polyoxyethylene ether, 3-6 parts of polyamide modified hydrogenated castor oil, 2-4 parts of succinic acid, 1-2 parts of pyridine hydrochloride, 1-2 parts of bromic acid tributylamine, 4-8 parts of DIACID 1550 and 1-3 parts of N,N,N,N'',N''-pentamethyldiethylenetriamine. The flux paste special for the unleaded tin-bismuth solder is good in wettability, the welding defect is lower than that of existing flux paste for the unleaded tin-bismuth solder, organic acid and polyamine decompose and volatilize in the welding process, the amount of residues generated after welding is small, and protective films can be formed on the surfaces of welding points through the used rosin.

Description

technical field [0001] The invention relates to the technical field of electronic welding, in particular to a special soldering paste for lead-free tin-bismuth solder and a preparation method thereof. Background technique [0002] In the development process of solder, tin-lead alloy has always been the best quality and cheap soldering material, both in terms of soldering quality and reliability after soldering can meet the requirements of use; however, with the strengthening of human environmental protection awareness, "lead" The hazards of the compounds and their compounds to the human body and the pollution to the environment have been paid more and more attention by human beings. Lead-free is already the trend of technological development, so due to the substitution of lead-free solder, the solder paste used in lead solder has been gradually replaced by lead-free solder paste. Lead-free solder is divided into SnAg series, Sn( Ag)Bi series, SnAgCu series, Sn(Ag)Zn series,...

AI Technical Summary

Problems solved by technology

The low-temperature lead-free solder paste is mainly tin-bismuth solder paste. However, the existing tin-bismuth solder paste is not highly active, which leads to the inability to remove the surface oxide layer for nickel-plated and copper-plated pads, resulting in soldering defects, such as virtual soldering. Monuments, solder balls, non-wetting and other adverse phenomena, the reason is that the low-temperature lead-free solder paste has a high content of bismuth, and bismuth is a metal that is easily oxidized, so the activity requirements of the solder paste are particularly high, and tin The high activity of the paste maintains excellent printability, and the activity and printing performance of the solder paste are mainly determined by the performance of the solder paste in the solder paste