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Transistors - die pictures

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mawyatt:
Nice images and storyline Noopy :clap:

Thanks for the continual efforts in showing these great semiconductor images, along with the excellent storylines & analysis :-+

Best,

AnalogTodd:

--- Quote from: RoGeorge on December 06, 2023, 12:04:11 pm ---Interesting story, beautiful pics, thanks!  :-+

Just out of curiosity, estimating R of a tin whisker:
R = \$\rho\$*L/S
\$\rho_{\mathrm{Sn}}\$ = 10.9E-8\$\Omega\$*m
L = 0.1mm
d = 5um

R = 10.9E-8 * 0.1E-3 / (3.14 * 25E-12 / 4) = 1.09/(3.14*1.25) = roughly 1/4 = 0.25\$\Omega\$  ???

I was expecting a much bigger R from such a thin wire.

--- End quote ---
When you're talking short distances, resistances turn out to be fairly low value. A gold bond wire that is 1mil diameter ends up at about 4.5 milliohm. What is the big deal on it isn't so much the resistance, but instead the fusing current. That's dependent on a number of variables from mass/cross sectional area to power dissipation and time. Sitting in open air like those will also lower the fusing current (over-molded bond wires can handle higher currents).

Noopy:
Thank you all for your input and positiv feedback!  :)

I had a small mistake in the name: It was called OC846A not OC864A.  :-+

floobydust:

--- Quote from: Noopy on December 06, 2023, 04:57:42 am ---
Here you can see the germanium power transistor OC864A, which was developed in the Funkwerk Erfurt but never went into series production. Only a few sample exist in the Thuringian Museum of Electrical Engineering (https://www.elektromuseum.de). The following background information also comes from this museum.

In 1959, the VEB Funkwerk Erfurt (FWE) ceased production of transmitter tubes. The capacities freed up were used to start developing germanium power transistors in the so-called Zentrallabor für Empfängerröhren (ZLE). An important basis for this work was a Soviet documentation. In addition to the necessary dimensions of the germanium crystal, it described how to etch the material, which alloy materials to use and which geometries to aim for. Alloying was carried out in a graphite mould under vacuum. The design of the alloying furnace was also taken from the Soviet documentation. However, the optimum temperatures and times for the alloying process were missing and had to be determined from tests. At the end of 1962, after the development had been completed, the results were transferred to the Halbleiterwerk Frankfurt Oder (HFO). [...]

--- End quote ---

"An important basis for this work was a Soviet documentation. "

High purity germanium crystal growing tech was a big deal back then. I'm curious who really had it or was it simply stolen IP?
Bell Labs 1953 William Pfann developed "zone refining" and I saw Japan using it to make transistors in the early 1950's.

Noopy:

--- Quote from: floobydust on December 06, 2023, 10:39:53 pm ---"An important basis for this work was a Soviet documentation. "

High purity germanium crystal growing tech was a big deal back then. I'm curious who really had it or was it simply stolen IP?
Bell Labs 1953 William Pfann developed "zone refining" and I saw Japan using it to make transistors in the early 1950's.

--- End quote ---


Well I don´t know. Would definitely be interesting...

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