Reducing the failure risk of portable electronic devices under field use conditions through triaxial strain gage array technology

Increasing functional density of portable electronic devices has led to the explosive growth in the array-based package (ABP) usage, however, the decreasing I/O pitch of ABPs and the consequent smaller pads and solder joints, along with the introduction of brittle lead-free solder alloy, make the interconnect reliability of portable electronic devices more challenging. In this paper, triaxial strain gage array technology was used for monitoring the strain response of laptops under various field use conditions, including rotating a screen, knocking keys, holding a laptop, and so on. The failure analysis results for the ABP assemblies subjected to the above loadings indicated that there was obvious positive correlation between the extents of solder joint damage and strain level around the corresponding areas. In addition to assessing the interconnect reliability risk during different events, the triaxial strain gage array technology can also be applied to compare the impact of mechanical structure design modifications to the solder joint reliability and determine the optimal design.