A study balancing physical properties for an optimized thermal interface material

Thermal dissipation requirements for advanced flip chip devices are becoming significant. High end flip chip devices that used lidded packages are now being redesigned to utilize even more advanced materials. Devices that previously did not require a lidded package are now being forced to utilize such a package. The latter scenario can also can benefit from more advanced materials. Initial thermal performance is a key factor for selecting a candidate thermal interface material (TIM), but how well the package can survive reliability conditions is also important. Cost pressures on the overall structural design can also be a significant factor for some types of applications. Polymeric TIMs can address many of these issues by having a high initial thermal performance and by allowing adequate mechanical stress relief to survive reliability conditions. The TIM properties, such as elongation and modulus can be as important as the thermal conductivity. Properties such as thermal resistance and thermal impedance are even more important. This paper will detail how these properties are inter-related and will demonstrate that an optimum balance between them can be achieved.