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The space qualified transistors are: Hermetic ceramic and copper tungsten packages. Eutectic die attach. Hand wired bonded. X-rayed for voiding under die. Gette
by madengr 7y ago
The space qualified transistors are:
Hermetic ceramic and copper tungsten packages.
Eutectic die attach.
Hand wired bonded.
X-rayed for voiding under die.
Gettered to absorb hydrogen. High temperature lid soldering in helium atmosphere.
Leak tested.
RF-DC burned in and thermal cycled. Note the threshold voltage changes as the parts are burned in, so all these parts are aged.
The PCBs are aluminum backed.
Gold selectively removed from PCB traces to prevent solder embrittlement.
Parts sometimes vacuum soldered to PCB (to prevent voiding).
X-Rayed to look for voids. Cleaned and vacuum baked.
RF-DC burn in.
My stuff had the lids welded on. Vibration tested. More electrical testing and thermal cycling. Ping tested to hear for loose parts and solder balls.
All this adds up the cost.
Rework is a nightmare, especially after the lids are welded.
All the other SMT parts are also S-level. A single tube of low-outgassing RTV (Dow 340) is $600.