Preparation of Anisotropic Conductive Particles by Electroless Nickel Plating.

Abstract

Demand for mechanical solderless chip connection methods using anisotropic conductive particles has increased in the field of electronic devises. In this study, the preparation of conductive resin particles (5 to 10μm in diameter) by electroless nickel plating and the surface morphology of nickel film were investigated. Since the surface area of particles are much larger than in a bulk substrate, a batch-type electroless plating bath is unstable. Therefore, we applied the continuous dropping method to improve the stability of the Electroless nickel plating. The surface morphology of the deposited nickel was greatly influenced by the complexing agent used, the bath temperatrue and solution pH. Uniform deposits on the particles were obtained at pH 5 by using ammonium acetate as the complexing agent. In contrast, extraneous deposits were recognized at pH 5 when using sodium tartrate as the complexing agent and in baths at pH6. This extraneous deposition could be decreased by lowering the bath temperature.