Fabrication of Rhodium Coated Ni-Co Microelectromechanical Systems Probe Tips Using Electroplating Method

Abstract

Rhodium (Rh) was electroplated at various conditions for wear-resistant probe card tips to improve perfor-mance and durability. When direct current (DC) was applied for the electroplating, the cracks were developed on the electrodeposited Rh due to the high residual stress. Pulse current (PC) method was applied to reduce cracks. Two conditions of on:off were applied and the crack free surfaces were obtained. The surface hard-ness of the deposits was over HV 800, it is 60% higher than that of Ni-Co deposits. To secure the thermal stability at high temperature, heat treatments were conducted at 300 degrees C. The addition of additives such as sul-famic acid and sodium dodecyl sulfate (SDS) can improve the ductility of Rh/Ni-Co deposits to overcome the difference of coefficient of thermal expansion (CTE) between the electrodeposits and the substrate. Finally, crack free Rh coated Ni-Co probe tips were fabricated using PC with addition of additives.