Thermal Interface Material is a fluidic material that fills small gaps or irregularities between two mating solid surfaces to help transfer heat between them more effectively. It is common in most industries including automotive, aerospace and energy production to include some type of TIM in the assembly process. TIMs come in a variety of forms such as grease, silicone, adhesives, pads and gels each offering unique properties and benefits for their specific application.
The main goal of a TIM is to prevent components from overheating by transferring the waste heat to a larger area such as a metal housing or thermoelectric cooler. The ideal TIM is able to dissipate the heat without introducing damaging vibration or thermal cycles that could lead to delamination and cracking. This is typically achieved through the use of a high-performance TIM that includes a combination of both physical and chemical properties such as good adhesion, high thermal conductivity and low thermal impedance.
The most commonly used TIMs include pastes and pads that are applied directly to the mating surfaces of a device. The main difference between these types of TIMs is their consistency and ease of application. While thermal pastes can be messy to work with during assembly, pads are pre-fabricated to ensure even placement. In addition, pads offer greater electrical isolation than a paste and often come with a pre-determined thermal conductivity rating of between 1.0 and 6.0 W/m*K. Another type of TIM is a phase change material (PCM) which has a very unique characteristic. When heated to the correct temperature these materials transition from a solid to a soft liquid to fill any gaps and expel air. Once the temperature has fallen below this point, the material returns to its original solid state.