Transistor Museum Early Germanium Power Transistor History by Joe Knight BTL Western Electric Page 24

A SURVEY OF EARLY POWER TRANSISTORS

by Joe Knight

THE POWER TRANSISTOR

BELL TELEPHONE LABS AND WESTERN ELECTRIC

By 1958, Bell Labs had developed the WE 2081, a NPN Silicon triple-diffused Power Transistor (no photo). This would be the predecessor to later WE diffused base power transistors. By 1959, Western Electric released the 2N1072, a NPN double-diffused Silicon Mesa Power Transistor, as a core-memory driver and switching device, rated at 12.5 watts of dissipated power. Shown below are three versions of the 2N1072, the first one on the left a hand-painted number pre-production type. The middle one below, from 1959, shows the typical exhaust tube tip. The far right sample is from 1961 and shows the then norm black-painted exterior (= better heat dissipation?) with the gold plated bottom surfaces and connecting wires. This was in the new TO-38 standard with the three thin wire connections.

The above cut-open sample shows the typical small square-built diffusion wafer (the individual wafers were cut from a larger round diffused wafer, as it is done still today) which allowed for its super-quick nanosecond switching speed.

The 2N1072 was used in the later Nike “Hercules/Zeus” air defense missiles for the guidance and control system (with W.E. being one of the prime contractors for the Nike).

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Joe Knight Early Power Transistor History – BTL/WESTERN ELECTRIC Page 24