Measurement of High-Performance Thermal Interfaces Using a Reduced Scale Steady-State Tester and Infrared Microscopy

Thermal interface materials (TIMs) have reached values approaching the measurement uncertainty of standard ASTM D5470 based testers of approximately ±1 × 10−6 m2 K/W. This paper presents a miniature ASTM-type steady-state tester that was developed to address the resolution limits of standard testers by reducing the heat meter bar thickness and using infrared (IR) thermography to measure the temperature gradient along the heat meter bar. Thermal interfacial resistance measurements on the order of 1 × 10−6 m2 K/W with an order of magnitude improvement in the uncertainty of ±1 × 10−7 m2 K/W are demonstrated. These measurements were made on several TIMs with a thermal resistance as low as 1.14 × 10−6 m2 K/W.