Effect of temperature on vibration durability of SAC305 printed wiring assemblies

Abstract

This study focuses on assessing the effects of temperature on vibration durability of SAC305 PWAs under random vibration excitation on a repetitive shock (RS) shaker. Major complexities involved in quantifying random vibration response and durability data are first discussed through a comparison of specimen unimodal response under harmonic excitation versus multimodal response to random excitation. Three dimensional FEA global modal analysis is conducted to quantify the modal frequencies and mode shapes and is calibrated with the modal frequencies determined from the vibration test. This modal analysis at room temperature provides an important baseline for quantifying the subsequent changes as a function of the test temperature. The response of a PWA with a SAC305 Chip scale Thin Core Ball Grid Array (CTBGA) component is characterized under RS random excitation at different temperatures (125°C, 25°C and −50°C), to qualitatively demonstrate the role of temperature on vibration response. Preliminary test data for vibration durability are also conducted at these temperatures and the results of these accelerated vibration durability tests are included to provide preliminary indication of the role of temperature on vibration durability. Quantification of vibration damage accumulation rates under RS random excitation at different temperatures will be presented in future through more comprehensive random vibration durability experiments, detailed FEA dynamic response analyses and fatigue damage analysis in the time domain using cycle counting methods.