You cannot lose sight of the facts presented.
If it is the wave solder machine, why only this assembly?
There are some things not quite right in the picture of the PWB, as Steve so correctly pointed out.
I would focus on the PWB, but not the components on the CCA, as the problem is on all components, but only those on that particular CCA.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Mike Fenner
Sent: Tuesday, September 01, 2015 7:27 AM
To: [log in to unmask]
Subject: Re: [TN] Textured Solder?
Well to me it's more than surface appearance from say slow cooling - it looks like contamination of one sort or another. The granular blobs are quite large and wetting to the leads is not inspectable because of them, so you could have poor wetting or not. [The blobs make looking for a low contact angle impossible in some cases.] It's complicated by the problem only appearing (at the moment anyway) on one board set.
So a process of elimination, consider your wave solder machine.
How's your hygiene? As Guy suggested, clean up the wave guide etc. Is the pot properly topped up, some machines with low fill level can draw dross from the surface and pump it through. What's the pot temp. Looking at the wave can you see anything rising up with the solder?
How does the pot look? If it's metallic contamination possibly you will see lumpy formations in the pot. If you take a sample from the wave does it freeze to granular or smooth?
If the sample freezes granular, first thing to do is to get an analysis.
Perhaps do that anyway for a definitive elimination.
Meanwhile you could reduce the percents by allowing the pot to cool thereby allowing the intermetallics to solidify slightly and float to top. Scoop out some kilos and replenish. That would drop the concentration when restored to operating temperatures and pumped a while to homogenize.
Keep the scooped out stuff for reclaim $$. [This could also be done as a diagnostic.] As best practice, make sure the flux is correct and applied properly.
So now your process is good.
If the machine is in good health and clean then that leaves the board set.
If it really is just one board set then focussing on that: What differentiates it from your other work?
For example what's the board finish? Heavily contaminated HASL could possibly do this.
--
Regards
Mike
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Theodore J Tontis
Sent: Monday, August 31, 2015 8:08 PM
To: [log in to unmask]
Subject: Re: [TN] Textured Solder?
I saw that as well but chalked it up as flux residue after the wave, in response to the snake like appearance to the solder resist.
Ted T.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Monday, August 31, 2015 2:01 PM
To: [log in to unmask]
Subject: Re: [TN] Textured Solder?
Hi again Dick,
Pre-heat temp sounds fine. But something else about the picture caught my eye, and I don't know if it's just an artifact from the digital image or not, but the solder mask seems a little weird looking with the dark spots around the edges of the apertures and along the traces, the rest of the surface has a sort of snake skin appearance in color too...kind of weird. I wonder if the mask might be under cured and something is going on that might be causing the surface appearance of the solder joints that you're seeing.
Is there SMT on the board, or is it all PTH? If there is SMT then you would think that reflow would eliminate the under cured mask theory.
It's strange that you're just seeing this on these boards and not others....
Steve
On Mon, Aug 31, 2015 at 12:28 PM, Richard Krug <[log in to unmask]> wrote:
> First, thanks for posting picture Steve.
>
> I'll try to answer all questions received thus far.
> Solder is Sn63Pb37
> Board is wave soldered.
> Topside board temp before the wave ~115C
> Leads of this component are solder dipped, alloy not
> specified, but SnPb. Similar appearance on virtually all solder
> joints on
the board.
> This result was found on all boards of this work order, but
> not on other assemblies soldered on the same wave.
> Flux coverage could be a cause, but dross is unlikely since
> not on other assemblies.
> Flux is ORH. Boards have been washed with saponified water.
>
> Thanks for the questions.
>
> Dick Krug, CSSBB, CSMTPE
> Lead Process Engineer
> Sparton Brooksville, LLC
> 30167 Power Line Road
> Brooksville, FL 34602-8299
> (352) 540-4012
> [log in to unmask]
>
>
> -----Original Message-----
> From: Guy Ramsey [mailto:[log in to unmask]]
> Sent: Monday, August 31, 2015 1:43 PM
> To: 'TechNet E-Mail Forum'; Richard Krug
> Subject: RE: [TN] Textured Solder?
>
> Might be past time to clean the wave guide. I have seen something like
> that when dross breaks off the inside of the guide and gets mixed in
> with the wave.
> I notice that three of the leads don't look like they wetted very well.
> Are you sure you have good flux coverage?
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Richard Krug
> Sent: Monday, August 31, 2015 12:15 PM
> To: [log in to unmask]
> Subject: [TN] Textured Solder?
>
> I've got something I haven't seen before. We wave soldered boards
> with
> Sn63Pb37 and found a "textured" surface after soldering.
> We seem to have good wetting, but it looks like we have "lumps" under
> the solder surface. The lumps are most visible where the solder is
> thin, but can also be found on thicker solder joints as well.
> The application is class 3. We do monthly solder analysis on the pot
> so I don't think it is contamination in the solder.
> Any insights would be appreciated
>
> I know the picture will be stripped out of the message, but I'm
> copying Steve Gregory directly in hopes he can post the picture.
>
> Steve - Please post this picture to go with my question for the
> TechNet forum. Thanks in advance.
>
> Dick Krug, CSSBB, CSMTPE
> Lead Process Engineer
> Sparton Brooksville, LLC
> 30167 Power Line Road
> Brooksville, FL 34602-8299
> (352) 540-4012
> [log in to unmask]
>
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