Investigation of High-Strength Electroformed Ni for Microprobes

Abstract

We have developed a microprobe that achieves low contact resistance under low contact force only for gold pads. However, in the case of Al pads, an oxide layer formed on the aluminum pad surface obstructs stable contacting, so higher contact force with a strong probe is required. The present study attempts to enhance the strength of the probe material by improving its mechanical properties. It is said that grain downsizing, functionally alloying, or impurity addition can increase material strength. Our study has adopted impurity addition to the electroforming bath because the process can be controlled. Thus, high-strength electroformed Ni has successfully been obtained. Improved Ni has a high Vickers hardness of Hv600 compared with Hv450 for conventional nickel, and a high Young’s modulus of E=200GPa compared with E=150GPa for conventional nickel.