On 4/7/17 6:25 PM, Bob kb8tq wrote:
Hi
On Apr 7, 2017, at 7:19 PM, jimlux <jim...@earthlink.net> wrote:
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.
Humidity does not tend to be a big issue once you get in space :)
Bob
Yeah, but you sit for years on the ground waiting, in tropical areas no
less.
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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