williams@kirk.DEC (John Williams 223-3402) (06/17/85)
Two important effects that contribute to Solid State wearing out: 1) Diffusion If the device is extremely hot, the features will lose their clarity due to diffusion which will tend to make the crystal impurities homogenous. 2) Thermal Cycle When the device is powered up and down, The device expands and contracts causing micro fractures in the structure. The silicon will tend to anneal itself, and diffuse causing greater leakage currents, and the metal structure will tend to develop cracks, which will increase the series resistance. The major failure mechanism to date in Computers is that of the device slowing down due to these effects. If the timing requirements for this device are critical, then this effect constitutes a failure. John.