Woodward Governor Company

John C Driscoll

Theodore S Wilmot

Eugene N Bryan

Richard S Brzostek

Fabrication processes for manufacturing and connecting a semiconductor switching device are disclosed, including an embodiment for dicing a wafer into individual circuit die by sawing the interface between adjacent die with a saw blade that has an angled configuration across its width, preferably in a generally V-shape so that the adjacent die are severed from one another while simultaneously providing a beveled surface on the sides of each separated die. Another embodiment relates to the manner in which damage to a beveled side surface of the individual die can be smoothed by a chemical etching process. Another embodiment relates to the manner in which the device can be easily mounted on a printed circuit board by providing conductive lands on the printed circuit board that are coextensive with metallized electrodes on the device and which can be placed on the printed circuit board and soldered in place and a unique lead frame which can be soldered to another electrode metallization on the opposite side of the chip and the printed circuit board in a manner which substantially reduces if not eliminates harmful thermal stress and which assures secure bonding notwithstanding elevation differences between the electrode metallization and the printed circuit board the lead frame is attached to. Another embodiment relates to an output connector for interconnecting an exciter circuit product with a spark producing device wherein the output connector utilizes a configuration that includes a sealing structure that is reliable and easily installed.

Method and apparatus for fabricating and connecting a semiconductor power switching device

A turbine engine ignition exciter circuit applies energy stored in the exciter tank capacitor to the load (igniter plug) through a thyristor type semiconductor switching device that minimizes leakage current at elevated operating temperatures. The semiconductor switching device is periodically activated by a trigger circuit to initiate discharge of energy stored in exciter tank capacitor to mating ignition lead and igniter plug. The circuit operates at a modest, for example, approximately 1.8 kV, tank circuit voltage to further reduce switching device leakage current related stresses at elevated temperatures allowing relatively long capacitor charge cycles, increased upper operating temperature capability and improved reliability. The circuit uses a low side switch circuit topology for releasing energy from said capacitor to ground whereby negative polarity energy is applied to the exciter.

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Raleign, NC, United States of America

John C Driscoll