PURPOSE: To obtain a superior electrically conductive filler for electrically conductive resin or paste by immersing fine spherical resin in an aq. tin chloride soln. having a very low Pb content to form a tin coat and by forming a silver coat on the tin coat by electroless plating.
CONSTITUTION: Hydrochloric acid is added to an aq. soln. contg. 30g/l stannous chloride and resin powder having cation exchange capacity is immersed in the soln. by 1-10g/l to adsorb Pb in the soln. on the resin powder and to prepare an aq. tin chloride soln. having <10ppb Pb content. Spherical resin of 0.5-1,000μm average grain size such as cross-linked polystyrene resin or phenol resin is immersed in the prepd. soln. to form a tin coat on the surface of the resin. This resin is then immersed in an electroless silver plating soln. to form a silver coat on the tin coat by electroless plating. An electrically conductive filler for electrically conductive resin or paste is produced.
SEKIGUCHI MASAHIRO
YOSHIZUMI MOTOHIKO
