What is this stuff on this pc board?

I occasionally see this residue where the components are soldered. Is this
flux? Something else?

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

Thanks for your reply.

 

Rosin core solder leaves flux if not cleaned. So, yes.

 

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.

Arfa

 

Looks like dried coffee creamer

 

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.
Martin.

 

The "brownish blobs" are not flux or anything else. They are simply
the ends of the cropped component leads. The device was soldered with
long leads and then the leads were cropped.

The white residue could be water soluble flux which has not been
removed after soldering the component.
http://www.kester.com/en-us/documentation/White Residue (26Jan05).pdf

 

looks like flux residue. But the boaed has not been washed and dried
properly after soldering process.
rw

--

 

Guru? Surely you exaggerate. But that dry, flaky, powdery white stuff
looks exactly like rosin flux residue that's been incompletely cleaned
using a saponifier and hot water. That methodology largely replaced
solvents some time back, as one alternative to water-soluble fluxes.

 

David

Conformal coating. Probably used for moisture protection among other
things. Like a varnish. Also some coatings were epoxy types.

Bob AZ

 

Plenty of solder processes these days do not require washing and cleaning. Most
consumer goods in fact.

Graham

 

It is NOT conformal coating. Besides you'll probably only ever see that on
high-end industrial or military gear.

Graham

 

On Fri, 17 Aug 2007 03:20:40 GMT, Ross Herbert

SNIP

It seems that the brackets around the date in the link act as a
terminator to the hyperlink underlining so you will have to copy and
paste the full url to get the document.

 

It works for me.

Graham

 

Or just about anything marine related.

 

Thanks Graham. When I paste the url link using Agent the underlining
stops before the opening bracket so I thought I'd better give a
warning.

 

It is flux residue. All of the VOCs have been removed and the solids are
left. Not to worry. Not pretty, but, ehhh...

Al

 

When I double click the link it is incomplete.

 

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

 

That is flux residue left after a run through a PC board washer, and
oven dry cycle. I saw it all the time in manufacturing. The ladies that
worked the cleaning room hand cleaned that with IPA and flux brushes, or
with a spray defluxer when they couldn't reach it with a brush.

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

That isn't conformal coating. It is a poor cleaning after the board
was made. The thinnest flux was washed away, the thickest is still
there. The powder is where the flux was a little too thick to
completely wash away in the automated cleaning process, and there was no
attempt to finish the job.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida