Impact of High Temperature Storage for Prolonged Duration on Cu Leadframe Material Properties for Automotive Applications

Copper-based leadframe material with Tin (Sn) and Nickel-Palladium (NiPd) finishing are studied in this work. The samples are subjected to high temperature storage (HTS) conditions of 175 °C for prolonged duration of up to 4000 hours. Multiple material analysis techniques are implemented to study the change in properties before and after HTS which includes nano-indentation (NI) for material mechanical properties such as hardness and modulus, cross-sectional scanning electron microscope imaging (XSEM) for morphology of material along the Z-axis, energy dispersive X-ray analysis (EDX) for elemental composition and X-ray diffraction (XRD) for crystallinity. It was observed that both Sn and NiPd finishing materials show increase in modulus after HTS. By contrast, hardness of NiPd remains stable after HTS while Sn shows drastic hardness increase. XSEM, EDX and XRD analysis results are found to correlate with the material’s mechanical response measured by NI.

Introduction

There is increasing number of electrical and electronic systems in an automobile to support features from infotainment to advanced driver assistance systems (ADAS), from comfort and control to power train electronics for electric vehicles (EV) [1] [2]. These applications are driving the semiconductor industry to fabricate products that are reliable, power-efficient, and environment-friendly [3] [4].