Stability Investigation of High Heat-Resistant Resin under High Temperature for Ultra-high Blocking Voltage SiC Devices

The reliability of the developed high heat-resistant resins called "Nano-Tech resins" has been evaluated under high temperatures for packages of ultra-high voltage SiC devices. The resins were applied to insulation substrates and high temperature storage tests have been carried out. The insulation performance at 20 kV was maintained for 1,000 hours at 225 degrees C. Even in a higher temperature storage test at 250 degrees C the resins were able to maintain the insulation for 500 hours. Most samples were not able to maintain the insulation for more than 500 hours because of cracks or detachments. Hardening caused by oxidation of the resin and differences in the coefficient of linear thermal expansion (CTE) are considered as causes of the cracks or detachments. It is thought to be necessary to lower the CTE of the resin and inhibit its oxidation in order to use it at more than 250 degrees C for long periods of time.