Extracting TIM properties with localized transient pulses

Thermal engineers require accurate package-level resistance estimates to design optimized cooling systems. Although Theta-JC is a commonly quoted metric to define the junction to case resistance, it does not accurately predict package performance for a range of heat sink and thermal interface material (TIM) conditions. To overcome this limitation, a steady-state and a transient test method is presented to extract the thermal resistance of the TIM. A high resistance adhesive, a low resistance gel and an Indium TIM are investigated. The transient method is shown to be approximately 20% more accurate compared to the steady-state method and also simplifies both the experimental testing and corresponding numerical simulations.