Tinning on old PCBs

From: Allison <ajp166_at_bellatlantic.net>
Date: Thu Dec 20 07:22:17 2001

Are you sure it was the solder plating and not the resist(solder)
mask(a plastic like over coating material)? If it was the tinning,
that's there to improve solderability and appearance as well.

The tinning adds very little to the current carrying capability as
tin and lead have significantly more resistance than copper.


-----Original Message-----
From: Louis Schulman <louiss_at_gate.net>
To: classiccmp_at_classiccmp.org <classiccmp_at_classiccmp.org>
Date: Wednesday, December 19, 2001 10:34 PM
Subject: Tinning on old PCBs

>I was cleaning a 20+ year old printed circuit board today, in the manner
recently discussed here at length
>(but by hand, I don't have a dishwasher). I was somewhat alarmed when some
of the tinning flaked off the
>copper tracks in places. The tracks themselves are fine, but evidently
they had not been properly prepared
>before tinning, so the tinning lost its grip.
>My questions is this: Is the copper itself sufficient to carry the
currents, or is the tinning required to reduce
>resistance? Or, putting it another way, is the tinning required, or is it
just to assist in attaching components?
>Or, putting it one last way, do I need to re-tin the bare spots?
>For what it's worth, this took place on the motherboard of my newly
acquired Exidy Sorcerer #2, a Mark I
>32K unit. This one came with a fair number of manuals and software (on
tape, of course).
Received on Thu Dec 20 2001 - 07:22:17 GMT

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