Chemical Bath Temperature Investigation for Electroless Nickel Immersion Gold

Abstract

Conventional gold wire bonding to alunimium bond pads leads to the formation of intermetallic compound. Electroless Nickel Immersion Gold (ENIG) has been proposed as surface finish for aluminium bond pads to improve high temperature reliability. In order to create acceptable solder bumps prior to reflow process, a particular bump height for ENIG bumps need to be obtained. This paper reports the effects of chemical bath temperature in response to the bump height using a shorter process time. Analysis was done by using a design of experiment (DOE). The results suggest that higher temperature increases the bump height. Electroless nickel temperature has more influence to the bump height compared to immersion gold temperature.