20 Dec
2001
20 Dec
'01
2:25 p.m.
From: "Louis Schulman"
<louiss(a)gate.net>
To: "classiccmp(a)classiccmp.org" <classiccmp(a)classiccmp.org>
Date: Thu, 20 Dec 2001 19:59:28 -0500 (EST)
Subject: Re: Tinning on old PCBs
Reply-to: classiccmp(a)classiccmp.org
Yes, this is the actual lead/tin that is peeling off.
There is no coating on this PCB, just the bare tinned traces
on a bare board. I will admit, this is quite unusual, since the solder must have flowed
out to tin the traces in
the first place, yet it did not bond properly.
I seen this once on Seagate HD ST1201A. Many SMD simply
popped off easily leaving bare copper where solder "bonded" to it.
Phyically when intact, looked good but that layer between copper and
solder is bad even everything looked "wetted" properly. Ditto to
many component leads (also on thru hole) even it was "soldered"
properly at factory.
Everybody else here's the Qs:
What is this failure called?
What causes this failure?
Cheers,
Wizard
Louis