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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