Tin zinc alloy plating
Release date:2015-07-16 00:00 Source: Views:
In the process of non cyanide zinc plating tin zinc alloy, the application of citric acid salt bath is more and more. The plating solution is relatively stable, and the content of tin in the plating layer is relatively easy to control. In the process of using citric acid or its salt as complexing agent, acid and auxiliary complexing agent (ammonium salt) together with the use of. If the content of complexing agent is increased, the content of zinc in the alloy coating is increased, while the content of zinc in the coating decreases, and the dispersion ability and the covering power of the plating solution decreases.
In order to stabilize the Sn2+ in the plating bath, the stabilizer must be added in the bath. Usually by two methods: one is in the bath by adding auxiliary complexing agent, such as ascorbic acid, phenol, Resorcinol, toluene sulfonic acid, tartaric acid, malic acid, glycolic acid, lactic acid, glycolic acid and its salts (sodium, potassium or ammonium salts, etc.); the second is the addition of reducing agents, such as vitamin C and molecular structure containing C = O, C = C and - OH groups of compounds.
In order to get the fine, smooth and bright tin zinc alloy coating, it is necessary to add bright agent. Citrate system use brightener, such as gelatin and peptone as organic matter and other organic matter, soluble mixture composition was also available oxygen ethyl ene polymers and ethylene glycol or glycerol and epoxy reaction products, but also to join the right amount of aldehydes compounds, such as piperonal and vanillin as secondary brightener. (precision metal parts manufacturing)