A Statistical Approach For Characterizing The Thermal Impact Of TIM Voids

Traditional methods of TIM (thermal interface material) void content specification are often based on a worst case analysis and can often lead to conservative and expensive lid attach design/process development, especially in high performance microprocessor package designs that are the norm today. In a meaningful departure from such methods, we present a practical approach to specify the maximum void content using the methods of statistical analysis. Our approach lends itself to a simple design paradigm where the business side of the package development drives the concept of an acceptable fallout level (AFL) and the technical specifications dictate the acceptable coolable power loss (ACPL). Together, these concepts are tied to a unique void content specification that is significantly less conservative than a worst-case approach, and readily meets the requirements of the design. We illustrate this novel approach for the simple case of TIM voids that have an area-wise uniform probability distribution, and compare the findings with a traditional worst-case void content specification.