Tinning on old PCBs

From: Louis Schulman <louiss_at_gate.net>
Date: Wed Dec 19 21:17:21 2001

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).

Thanks,

Louis
Received on Wed Dec 19 2001 - 21:17:21 GMT