Thermal Characteristics of Integrated Fan-Out on Substrate (InFO_oS) Packaging Technology

Unprecedented computing power is pursued for the next generation of big data, cloud computing and artificial intelligence, and it is driving all kinds of new technology in semiconductor industry now. Integrated fan-out on substrate (InFO_oS) packaging technology emerges as one of the innovative package solutions to connect multiple dies, and therefore could deliver higher performance than conventional one-die package. Due to extremely high power is accommodated in one single package, accurate thermal analysis of it is crucial to avoid thermal issue of integrated chips. In order to understand the thermal characteristic of integrated fan-out on substrate package, not only a detailed package thermal model was constructed but also a thermal test vehicle (TTV) was developed in this work. Standard JEDEC package thermal resistance of junction-to-case experiments was conducted with large body InFO_oS TTV, including multiple heat sources. It is shown that the thermal model can achieve great accuracy compared with measurement result. Meanwhile, as thermal interface material (TIM) between die and metal lid plays a big role of thermal resistance of junction-to-case, different kinds of TIM materials were adopted in this TTV to characterize their thermal performance. The effect of bond line thickness (BLT) of TIM was also investigated as it is another key factor. In this study, a detail InFO_oS thermal model was verified and fundamental thermal characteristic of it was completed. Furthermore, based on the correlated thermal model, a series of thermal simulation was executed to study thermal power budget with advanced thermal solutions and with different TIM materials adopted in InFO_oS package. It would be practical and beneficial to implement this methodology in design phase to reduce thermal risk in system application of end product.