Showing papers on "Sodium hypophosphite published in 1978"

Electroless tin and tin-lead alloy plating baths

Abstract: Salt compositions and baths thereof useful in, and methods for, immersion plating of tin and tin-lead alloys which give greatly increased deposition rates and thicker coatings of better quality accomplished by incorporating into immersion plating tin bath compositions soluble plumbous salts in the amount of from 0.5 grams per liter calculated on the basis of elemental lead to the maximum amount soluble in the bath and a sulphur-containing complexing agent for the tin and lead such as thiourea or a thiourea-type derivative. Preferably the salt elements are stannous chloride, lead chloride, sodium hypophosphite (as a solubility enhancer) and with hydrochloric acid used as a agent for adjusting the pH in the resulting bath from 0.5 to 1.0.

Electroless tin plating of electric lamp leads - to permit easy machine soldering even after prolonged storage

Abstract: Wedge base electric lamps are made with current leads which can be machine soldered, the leads consisting of copper-clad wire with length is not >9 mm and having a coating of tin obtd. by electroless plating. The leads on the finished lamp are cleaned; dipped 1.5 hours in a bath (a) at 80-90 degrees C., contg. SnCl2. 2H2O; thiourea; HCl; sodium hypophosphite; a wetting agent; and deionised water. After rinsing, the leads are successively dipped in four baths (b-e), each consisting of glycerine contg. 0.3% ZnCl2 and used as follows:- (b) 30 seconds at 100 degrees C; (c) 20 seconds at 150 degrees C.; (d) 10 seconds at 200 degrees C.; (e) 5 seconds at 240 degrees C. The leads are then rinsed and dried. Machine soldering of the lamp leads is possible even after a storage time of 1 year, due to a pore-free tin coating of 3-4 mu m.