Re: repairing broken traces on a PCB

On Fri, 24 Feb 2006 23:08:02 +0100, the renowned "Frank Bemelman"
<f.bemelmanq@xxxxxxxxxxxxxxxxx> wrote:

"Spehro Pefhany" <speffSNIP@xxxxxxxxxxxxxxxxxxxxxxx> schreef in bericht
news:3i0vv195e58n088sddpu25m71tunhsf6hh@xxxxxxxxxx
On Fri, 24 Feb 2006 22:35:36 +0100, the renowned "Frank Bemelman"
<f.bemelmanq@xxxxxxxxxxxxxxxxx> wrote:

"samIam" <him@xxxxxxxx> schreef in bericht
news:pzHLf.17$Ry.12@xxxxxxxxxxx
I have broken traces on a PCB I recently etched. Just a handful ...

I am wondering how some of you repair them. Trying to tap into your
body
of experience with this.

More interesting is to hear about experiences in finding hairline
cracks in tracks.

I rather enjoy paying for 100% electrical inspection. Let the machines
find the problems.

Well, I have a board here worth $100 perhaps, that certainly passed
all tests, but fails now. When I bend it, it works. I should add, that
after bending it ~15 times it stayed in failure mode. I found one
decoupling cap standing in the air, some flux rubbish (?) between a few
legs of a TQFP, but nothing that causes the failure. Ditched it
already.

Probably wise. I've found such problems, out of sheer stubborness, but
it's hardly cost-effective in itself, but necessary sometimes if you
want to make sure it isn't something more ominous than a single
failure.

I wonder what the dropout percentage is for tested boards, and if
it is worth paying for.

Around 1% for moderate quantity 2-sided boards, IME, but hair shorts
are more likely, and it's not that sensitive to design rules (10 mils
and 8 mils are about the same).

Difficult to anwer of course, I simply have
excellent experience with untested boards, even with 7mil tracks/distance.
Seems that more goes wrong with the assembly of parts, imo

We got a batch from a Taiwan manufacturer one time that was more than
20% bad. That was a long time ago.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@xxxxxxxxxxxx Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
.

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