Mechanical Properties analysis of Indium-Silver Alloys Thermal Interface Materials for FCBGA Reliability

This study used mechanical properties to compare whether pure indium and indium-silver alloys with different silver contents as thermal interface materials (TIM) for flip-chip ball grid arrays (FCBGAs) would crack due to thermal stress during reliability testing. Because from the product structure analysis, it is known that during the reliability thermal cycle test (TCT), the warping behavior of the product causes the TIM to be subjected to repeated vertical stretching. This cyclic stress exceeds the mechanical limit of indium metal, causing central fracture and reducing TIM coverage in scanning acoustic tomography (SAT) analysis. The coverage of the chip surface plays a crucial role in determining the heat dissipation performance of the packaged product, so it is necessary to select materials with higher mechanical strength. To address the TIM cracking problem caused by warpage stress, we propose the use of indium silver alloy as an alternative solution. Although this would traditionally compromise thermal conductivity, minimizing coverage loss can effectively enhance current heat dissipation capabilities.