How TIM impacts thermal performance of electronics: A thermal point of view study to understand impact of Thermal Interface Material (TIM)

For an electronic product, its housing plays a critical role in protecting the electronic components from environmental loads. In past few years, electronics industry has developed several housing designs. One of the most common designs is a metallic housing, having heat sink and fins. Heat Sink is an important part of a metallic housing. There are several factors affecting the performance of heat sink. One important factor is the Thermal Interface Material (TIM), which is used to ensure physical contact between the Printed Circuit Board (PCB) and heat sink, and to avoid electrical contact between the two parts. The performance of heat sink is affected by the thickness, cross-sectional area and thermal conductivity of TIM. In this study, the importance of TIM is evaluated, by varying all the three parameters viz. thickness (t), thermal conductivity (k) and cross-sectional area (A), of TLM which in turn affect the performance of heat sink. In first part of the study, a typical TIM of typical thickness is used. And evaluations are carried out by varying the percentage area coverage. In second part of the study, the thickness of TLM is varied for constant value of thermal conductivity. The thickness variation is done within the recommended range of thicknesses for materials under study. In third part of the study, thermal conductivity of TIM is varied. The variation is between the TIMs having the highest to the lowest thermal conductivity, which are available in the market for industrial use. All the simulations were steady state simulations, carried out in FIoTHERM (TM) and all three modes of heat transfer i.e. Conduction, Convection and Radiation are considered. The ambient around the electronics is considered to be similar to that faced by automotive electronics in the field. All simulations are carried out for natural convection air flow conditions. These studies will help any electronics development engineer understand the significance of TIM on temperatures of power dissipating components in an ECU. Since the change in material leads to change in cost of the electronics, this study can help the product managers understand trade-off of changing material of TLM, without having to do any new studies.