Transistor Museum Oral History Ralph Greenburg Page 7

EARLY TRANSISTOR HISTORY AT MOTOROLA

An Interview with Ralph Greenburg

Historic Semiconductor Devices and Applications

Ralph recounts that one of the major contributions of the early Motorola transistor program was the development of the “diamond-shaped” TO-3 case style. He attributes the development of the TO-3 case format to Dale Kelley at Motorola. Shown above are segments of one of Dale’s patents (assigned to Motorola) relating to the TO-3. As shown, the power transistor could be bolted directly to the automobile radio case, which would act as heat sink. Other related Kelley TO-3 patents are 3060553 and 3142791. Ralph also mentions that the original Motorola prototype germanium power transistors used a stud mount. At right is a photo comparing one of the early Motorola stud mount prototypes with an early 2N176 TO-3 case. By the late 1950s, Motorola was manufacturing millions of TO-3 devices annually – this was the first major success for Motorola as a semiconductor manufacturer.

Go To Greenburg Oral History, Page 8

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