Abstract
In the course of the development of hybrid voltage regulators for automobile use, increasing the reverse blocking voltage with decreasing of saturation voltage for output power darlington transistors, the capability of monolithic IC chip against surge pulses generated in cars, and an improvement of the pattern design of thick film in order to withstand temperature cycling, have been important subjects. Power darlingtons have more than 150 V of reverse voltage as well as large secondary breakdown capacity and less than 1.2 V of saturation voltage. A monolithic chip having small saturation voltage and more than 500 mA of surge current capability, has been developed. A neck-shaped thick film pattern was developed to make soldering in a controlled manner. The problems in the earlier stage with surge current and temperature cycling have been almost solved by these improvements.In this paper the characteristics of the transistor and the monolithic chip the structure of the device and related problems observed in temperature cycling are described.