The Influence of Cell Size on Lightning Surge Protection Semiconductor Devices

Transient temperature rise is analyzed for a lightning surge protective semiconductor device. When a lightning surge strikes a conventional protective device, it is found that the heat concentrates, raising the device temperature. We propose a multi-cell device that reduces the maximum temperature caused by the heat concentration, thus improving the surge handling capability of the device. We examine the influence of cell size on maximum temperature by analyzing the transient thermal characteristics. The maximum temperature is found to strongly depend on the unit cell size, so that the multi-cell device efficiently decreases the maximum temperature. Our fabricated surge protective device with 8 cells has a 30% higher surge handling capability than a conventional device for lightning surge waveforms of (10/1000) µ s.