Size Evaluation of SiO₂ Nano–Particles in Silver Plating by Using Small–Angle X–ray Scattering

Abstract

Multiway connectors made of silver–plated copper and copper alloys are widely used in automotive electronic control systems because of their high conductivity and low contact resistance. With the development of autonomous car, these systems will be expected to require more these connectors. On the other hand, these connectors require high insertion force, which makes the assembly operation difficult. Therefore, demand of lower insertion force has grown for a silver plating. We are developing silver composite plating which is made by co–deposition of sub–micron order silica particles. It is important to evaluate the size and distribution of the silica particles in order to form a low insertion force composite plating without losing the conductivity, and then the small angle X–ray scattering measurements (SAXS) is the most suitable analysis method. The size of the silica particles in a silver plating estimated from synchrotron SAXS measurement agrees with the measured size from SEM investigation. On the other hand, it was found that the distribution of the silica particles is changed by the difference of the X–ray scattering of Ag plating.