| 摘要 |
Exemplified viscous adhesive compositions which are applied to insulating bases prior to deposition of metal coatings thereon in the production of printed circuits (see Group II) comprise (1) and (2) phenol-formaldehyde, polyvinyl butyral, powdered cuprous oxide or zinc dust, powdered silica, diethyl carbonate and ethanol; and (3) epoxy modified phenol-aldehyde, butadiene-acrylonitrile, aluminium powder, hexamethylene tetramine, diethyl carbonate and diacetone alcohol. Specifications 674,630, 924,049 and U.S.A. Specifications 2,534,374 and 2,758,953 are referred to.ALSO:In a process of forming a printed circuit, selected areas of an insulating base are coated with a viscous liquid composition containing an adhesive component and particles which act as such, or after activation, as sites for the decomposition of, and deposition of metal from, a currentless metal deposition bath, and the base then immersed in such a bath to deposit metal on the said selected areas. The insulating base may be of ceramic, rubber, phenol-formaldehyde impregnated material, melamine-urea, vinyl acetate-chloride copolymer, cellulose acetate, epoxy resin, glass cloth or epoxy-coated glass. Specified viscous liquid compositions contain phenolformaldehyde or phenol-aldehyde/epoxy resin together with polyvinyl butyral or butadiene acrylonitrile; alternatively, they may be based on cellulose acetate lacquer or gum arabic. Specified active particles are of titanium, aluminium, copper, iron, cobalt, zinc, titanium oxide, copper oxides, stannous chloride, stannous fluoroborate, stannous sulphate or titanium trichloride. Particles which may be activated (successively in stannous chloride and titanium chloride) are of silica, clay, alumina or wood flour. Metals which may be currentlessly deposited are copper, nickel, silver and rhodium. A suitable bath contains copper sulphate, sodium hydroxide, Rochelle salts and formaldehyde. After the metal is deposited, the structure may be heated and the circuit then built up e.g. with silver and rhodium by electrodeposition, or by immersion in molten metal or alloy. Specifications 674,630, 924,049 and U.S.A. Specifications 2,534,374 and 2,758,953 are referred to. |
