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The lab director Ed Herold (mentioned in Kurshan's
history) felt we should work on diffusion for the diode junction. In
retrospect he was right, as usual. We did do one experiment with diffusion
but we didn't know how to proceed after the diffusion step. The program
really got into high gear when I got back to Somerville and Lorne Armstrong
took charge. Hank Harmon was also assigned. We built a good sized vacuum
furnace using a pyrex tube about 18" long and about 1 1/2 " in
diameter. The heater strip was wound on the outside. We made good aluminum
to silicon junctions, when we could get decent crystal. Because aluminum is
difficult to make a connection to, we came up with a way of firing a small
tungsten ribbon into the aluminum dot during the alloying step. This
described in U.S. Patent # 2,878,432 entitled "Silicon Junction
Devices", inventors: Lorne Armstrong, Henry Harmon and me.
The mechanical requirements were very high; one of the
planned applications was in proximity fuses in artillery shells. I was part
of a group with a goal of putting a germanium transistor mount in an
element meeting the form factor with a tough height requirement
~0.050". The structure is explained pictorially in U.S.Patent
#2,971,138 ; inventors Adam Pikor, Leonard Schork, Adolf Blicher, and me.
Some of the engineering solutions I worked out were: figuring a temporary
mount to get through connector wire solder, etch, rinse , bake, junction
coat , test, cut of from the temporary mount, mount into cavity, develop an
alumina loaded resin to fill cavity, hot solder seal with pure rosin flux.
Samples passed temp cycling, life test, and 20,000 G centrifuge.
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