Hi Mark!
Can something conform to spec but still show poor workmanship?
Absolutely! I've always interpreted workmanship as an indicator of the
care that goes into building something, and to some degree a measure of
consistency. I'll use some examples from CCA assembly as I'm not a PWB
guy, hopefully my meaning will be apparent.
Say hypothetical assembly factory X can build a board that is covered
with things that are acceptable to spec, but are clearly not the target
situation. This would be acceptable, but would not demonstrate (in my
view) good workmanship. Say factory X builds a board that's got a bunch
of parts with barely acceptable side overhang on the lead to pad
registration, the amount of solder just barely meets the fillet height
and length requirements, and there is a delaminated area that is small
and not bridging more than 25% of the distance between conductors. This
would be totally acceptable per spec, and can be shipped. BUT - the
workmanship on such a hypothetical board is not good, as it shows
production at a quality level that is dangerously close to rejectable.
If factory X was building boards like that for me, while I would have to
accept it, I would question the workmanship because the next one could
easily be rejectable with a small variance in the processing.
I'd call good workmanship the condition where the product meets the
target configuration a majority of the time. If I get a PWB where the
holes are dramatically off center compared with the annular ring, where
there is lots of solder mask touchup, etc. - acceptable, but poor
workmanship.
regards,
Graham Collins
Process Engineer,
Northrop Grumman Canada Corporation
Halifax
(902) 873-2000 ext 6215
>>> [log in to unmask] 05/21/04 11:14AM >>>
Hi All,
May be a dumb question, but here goes:
What's the difference (if any) between conformance to spec (ie.
IPC6012
class2) and workmanship? Can a bare board that conforms to the spec
exhibit
poor workmanship (or visa versa)?
Thanks,
Mark Hargreaves
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