On Fri, 17 Aug 2007 00:29:20 +0100, Martin Crossley wrote:
Arfa Daily wrote:
"David Farber" wrote in message
...
I occasionally see this residue where the components are soldered.
Is this flux? Something else?

http://www.pbase.com/image/83992679

I'm not sure what that is, but it doesn't look like any flux residue
that I've ever seen. The little brownish 'blobs' on the tops of
Q200's legs do, as does the lttle patch at the upper edge of its
centre leg. If it is flux residue, I'm sure that you would agree, as
a repairer yourself, that it is very unusual for it to be white like
that, which is why you are asking for the opinions of others on here,
I would guess ? Perhaps solder guru Smitty could offer an opinion
from the production point of view.

I've seen it before; It's flux residue that has become damp, then dried out
again.
Is there also a touch of rust on the end of the transistor's legs (the
brownish blobs)?
And possibly a bit of corrosion on the edges of the tracks, or just poor
resist?
Yet I can't see any corrosion on the 0R22-resistor, but the solder is a bit
grainy, so it's probably either lead-free or has been damp.
I bet the white deposits will turn back to ordinary flux deposit if heated.

It is not of manufacturing origin.

It looks like a (field? post-inspection?) repair -- the replacement of
"Q200". After soldering, the leads of Q200 have been snipped off with a
pair of flush wire cutters -- leaving a clean exposure of the copper of
the leads.

So, the residue is probably dictated by the brand and the quality of the
solder used in the repair.

Jonesy
--
Marvin L Jones | jonz | W3DHJ | linux
38.24N 104.55W | @ config.com | Jonesy | OS/2
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