Joint Development of a Package-Level Thermal Interface Material Test System

As the microelectronics industry continues to trend towards smaller, lighter, and higher power devices, thermal management is becoming more important than ever. Thermal interface materials (TIMs) play a crucial role in removing heat from both bare die and lidded packages. A serious challenge the industry has been facing is the lack of an agreed upon test standard that is specifically tailored for TIM thermal performance measurements between TIM suppliers and OEM customers. ASTM D 5470 is not necessarily the best gauge for TIMs in-application performance. Data generated by the OEM often differ from TIM supplier’s results, and thus can not be used confidently in thermal design. An OEM’s material selection can also prove to be unreliable when comparing data from different TIM suppliers. This paper presents a successful model that an OEM customer (Sun Microsystems) and a TIM supplier (LORD Corporation) have established for characterization of TIMs, and illustrates a package-level thermal test vehicle (TTV) setup for junction-to-sink thermal resistance measurements. Also presented are test results for several TIMs and repeatability of the test method. The effects of a few influencing factors, such as pressure load and TIM staging time, on the test results are also discussed.