Development of new method to fabricate a conductive ball for an anisotropic conductive film

We present a new and simple method to fabricate conductive ball by using mechanical embedded Ni nanoparticles in a core particle to form an underplated, instead of a plated, layer. The core particles and the Ni nanoparticles were mixed in proportion by weight and put together into a chamber, in which the Ni nanoparticles were subjected to a mechanical force to be embed the surface of a PMMA polymer ball. Then, a gold-plating process was carried out to attain a proper electrical conductivity and chemical stability. In this method, we could acquire conductive balls for anisotropic conductive films by means of a simplified process, with low cost and reduced use of noxious materials.