Large Body Lidded FCBGA Thermal Performance Study with Indium-Silver Alloy TIM

The power consumption required for semiconductors has increased to hundreds of watts due to the growing artificial intelligence (AI) and high-performance computing (HPC) industries. High temperatures resulting from high-power consumption can reduce the electrical performance of integrated circuit (IC) chips, therefore, the effective heat dissipation of IC packages is essential to enhance their performance and extend their life. The thermal interface material (TIM) is one of the critical key factors to thermally improved packaging. Many TIMs, such as polymer, graphite and metal TIMs, have been developed to provide the best thermal performance for packages. Among the various TIMs, indium-silver (InAg) alloy TIMs showed superior thermal performance because of their higher thermal bulk conductivity and much lower interfacial thermal resistance. However, it is also important to maintain the excellent performance even after board level long-term reliability tests. Therefore, the thermal performance of InAg alloy TIMs is described with two long-term reliability tests: 1) 2,000 cycles temperature cycling (TC) test at Condition K and 2) 2,000 hours high temperature storage (HTS) test at 135°C. Junction-to-case thermal resistance (ӨJC) measurements of 60 x 60-mm body lidded flip chip ball grid array (FCBGA) packages were performed with a water-cooled, cold plate cooling system. The 60 x 60-mm body lidded FCBGA thermal test vehicle (TTV) has a 25.6 x 25.6-mm die divided into 36 unit-cells with the temperature of each cell measured individually. The indium-silver alloy TIM thermal performance was quite different from polymer or graphite TIMs. The difference of the heat flow mechanism from the die to lid of both HTS and TC test conditions is described using three-dimensional (3D) thermal simulation to further understand the thermal characteristics of the metal TIM.