[time-nuts] The ultraAtomic clock for home
jimlux at earthlink.net
Fri Apr 7 19:19:48 EDT 2017
On 4/7/17 3:45 PM, Charles Steinmetz wrote:
> Bob wrote:
>> The epoxy over wire bond construction approach
>> is low cost, and not very experimenter friendly.
> It is also extremely unreliable, particularly WRT environmental effects
> such as temperature changes, humidity, and atmospheric pollutants. In
> my view, it is unsuitable for use in anything but dirt cheap, purely
> disposable devices like greeting-card audio players and disposable cameras.
Interestingly enough it *is* used in space flight hardware. It is much
less expensive, lighter weight and easier to inspect than thick film
hybrids and similar schemes.
You can can do a pre-cap inspection, then apply the potting material,
and then you could even xray it to see if the bond wires moved or something.
A flipchip with a blob is even better.
It's even reworkable (e.g. you can soften the blob & solder and scrape
the die off and bond a new one down).
I suspect that there is a wide variation in the material you blob on
there and so forth.
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