BATH FOR THE ELECTROLESS DEPOSITION OF DUCTILE COPPER

1400120 Electroless deposition of Cu PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd 2 Oct 1973 [5 Oct 1972] 45936/73 Heading C7F An alkaline aqueous Cu-plating bath comprises 0.01-0.15 mole/1 water soluble Cu salt 0.01-0.80 mole/1 complexing agent for Cu3 +ions 0.01-0.35 mole/1 formaldehyde, or compound producing formaldehyde 0.05-0.50 mole/1 alkali metal hydroxide (pH11-13.5) 0.001-0.5 wt per cent of a thioether of a polyalkylene glycol, said thioether defined by:- where R 1 is an aliphatic or cyclic group, R2 is H, a sulphate, a phosphate or POCl 2 ,(a+b+c)= 20- 500, and wherein b#O and (a+c) #O. The Cu salt is preferably CuSO 4 À5H 2 O, and the complexing agent may be triethanolamine, EDTA, tetra Na salt of EDTA, Rochelle salt, diethylenetriaminepentaacetic acid, cyclohexanediaminetetra-acetic acid, nitrilo-triacetic acid, or N-hydroethyl EDTA. In examples, glass plates are activated in SnCl 2 +HCl, sensitized in PdCl 2 and treated in a solution of NaOH and formaldehyde prior to immersion in the plating bath. Examples are given of suitable thioethers.