Re: Any recommendations for contract assembly companies?

Hello,

(sorry, don't know your name)


Qualify "test"... ICT's purpose is to make sure all desired locations
are populated with approximately the correct component values.
Something like a Zentel tester is used. The bed-o-nails is custom but
the tester itself is generic, software-reprogrammable. It's not
significantly more expensive to make a bed-o-nails for the panel than
for the individual PCB; it's a step and repeat CNC process to drill the
probe positions.


With test I mean a detailed enough diagnostic routine. In most of our cases it entails an extra few routine on a uC. This pipes signals from otherwise quiet port pins into strategic points and from the response it is deduced what could be wrong. Mis-stuffed caps, resistors, lack of hfe in a transistor and so on. The transistor thingie is next to impossible with ICT, at least for RF. Not that we hadn't done that on a Zehntel in the past but it required elaborate 'satellite boards'.

Wrong component values are pretty much a thing of the past these days. Same with tombstoning but that could be found via optical inspection anyway. The last time I saw a design being subjected to the big Teradyne was more than a decade ago.


Sometimes ICT will include programming flash chips, EEPROMs,
serialization, etc.


Yes, that's a nice advantage. But contract assemblers charge a lot for ICT.


FT's purpose is to make sure the device as a whole functions within
specifications. This is almost always a custom fixture.


There usually is no fixture. Upon power-up plus sometimes a 'secret button' press the circuit performs a self-test. The only time when there is a fixture is for checking cal levels of voltages, frequencies and the like. But that boils down to a connection plus connector saver and some PC controlled lab equipment.


It's very difficult to perform equivalent functionality to a
bed-o-nails ICT in vivo on the device itself. If this feature is a
customer requirement, then it can be engineered in, but at a
staggeringly high cost.


True but one doesn't necessarily need all that functionality. In the RF world the functionality of ICT is actually lower or sometimes ICT can't do it at all.

Staggering cost? Cannot agree here. Not if testability is a functional requirement from day one of the design cycle. Which it should. In the medical world that's almost the law so we have to.

Regards, Joerg

http://www.analogconsultants.com
.

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