The thermal creep of thermal conductive silicone rubber is reversible, meaning that it can be restored to its original state after thermal creep occurs, which is the key to improving the reliability of thermal conductive silicone rubber. The recovery ability depends on the confrontation between driving force and resistance, where driving force mainly comes from the elasticity of silicone rubber, and resistance mainly comes from the internal resistance formed by thermal conductive powder and silicone rubber. Therefore, in order to improve the reliability of conventional thermal conductive silicone rubber, two approaches can be taken: (1) increasing the elasticity of silicone rubber, and (2) reducing the internal resistance generated by thermal conductive powder and silicone rubber.
(1) Improve the elasticity of silicone rubber
The elasticity of silicone rubber mainly comes from its network like macromolecular structure, which depends on the molecular structure of vinyl silicone oil and the amount of hydrogen containing silicone oil used on the side.
Increasing the amount of hydrogen containing silicone oil on the side can improve the elasticity of thermal conductive silicone rubber, thereby enhancing its reliability. For example, among the common types of thermal conductive silicone rubber products, the amount of hydrogen containing silicone oil in the side of the silicone thermal conductive potting adhesive is relatively high, and the hardness of the finished product is high, which has better temperature resistance and reliability than thermal conductive silicone sheet, thermal conductive gel, thermal conductive structural adhesive, etc.
However, many applications of thermal conductive silicone rubber require it to have low hardness and high compressibility. If the amount of hydrogen containing silicone oil on the side is blindly increased, although it can improve the reliability of thermal conductive silicone rubber, it will lead to excessive hardness, low compressibility, and loss of application value.