Issue with solder mask on freshly assembled PCB

[Hrvoje-CRO]

Hello!

Few weeks ago i've assembled one project (2same pcb's) and what really makes me frustrated is this:
http://postimg.org/image/6z4rwswf7/
As you can see, solder mask around that joints looks like residues of flux, but it's not a flux! Even worse - it's a solder mask "swelled" but i have no idea why? Only on 2 exactly same PCB's and exactly same parts of PCB.
Is it possible that the cause of that issue is kontakt LR spray? Because i used that spray only on that 2 PCB's. But why arround solder joints and not on entire PCB?

Thank you in advance!

[jahonen]

Non-SMOBC-soldermask? If soldermask is not SMOBC (Solder Mask Over Bare Copper), then the solder will easily creep under the solder mask and cause "swelling". Difference is that SMOBC is put on the PCB before pads are plated, (thus no plating between solder mask and copper), but non-SMOBC boards will get plating for whole PCB and solder mask is put there only after plating.

Regards,
Janne

[Hrvoje-CRO]

Hi Janne!

PCB is factory made, and it is galvanic tinned. Company that has made for me PCB answered me that is possible on some places issues like mine. But i am still concerned with that. Oh yes, what about temperature of soldering? Perhaps i chose too high temperature of my soldering iron. I do not remember...

Regards,
Hrvoje

[Alphatronique]

Hi

that definitively a PCB shop issue  ,caused by bad solder mask  or shop for save money not strip the tin plating it use as etch resist ..

be aware that normally when that happen mask may flake and expose trace
that later oxidise and may cut trace ...

so better to change your pcb supplier ...

[Hrvoje-CRO]

Believe it or not the cause of my problem was Kontakt LR spray.

[Alphatronique]

Hi

ok but solder mask normally not deteriorate whit normal flux cleaner ;-)

was not found MSDN for it was curious what it put on it

[Hrvoje-CRO]

Hi again,

Yes and i know that! This is why i am frustrated because i am not 100% sure if is LR cause. But obviously it is after use on other PCB from same manufacturer.

[Kjelt]

The manual of the cleaner does say:

If a “whitish deposit” forms on the printed circuit board after cleaning, this might mean
there was probably a coating present which has been partially dissolved by KONTAKT
PCC. In this case a perfect appearance is restored to the circuit board by coating it with
our conformal coating PLASTIK 70.

Try flushing with IPA after use, that is what I always do. But I would first test the PCB if this is really the cause, so apply on places where there is no bubbling yet and see if this is really the cause or that it was perhaps a too hot/long soldering that was the cause. Because it is both on a large PCB plane part , so you needed more heat to get the soldering done on that place so that could also be the cause?

[Hrvoje-CRO]

The manual of the cleaner does say:

If a “whitish deposit” forms on the printed circuit board after cleaning, this might mean
there was probably a coating present which has been partially dissolved by KONTAKT
PCC. In this case a perfect appearance is restored to the circuit board by coating it with
our conformal coating PLASTIK 70.

Try flushing with IPA after use, that is what I always do. But I would first test the PCB if this is really the cause, so apply on places where there is no bubbling yet and see if this is really the cause or that it was perhaps a too hot/long soldering that was the cause. Because it is both on a large PCB plane part , so you needed more heat to get the soldering done on that place so that could also be the cause?

Hi Kjelt,

Could be main cause of that be alfa fluitin's flux? And no, it is NOT due to usage of spray that i mention as a cause.
I ask that because i've noticed on another PCB something strange. One tiny line near solder joint is covered with flux residues and exactly on that part soldermask has "bubbled".

[Kjelt]

Hi Kjelt,
Could be main cause of that be alfa fluitin's flux? And no, it is NOT due to usage of spray that i mention as a cause.
I ask that because i've noticed on another PCB something strange. One tiny line near solder joint is covered with flux residues and exactly on that part soldermask has "bubbled". 

Ok if spray is not the cause: the marked places are all ground planes, you needed to apply much more (longer) heat for soldering those spots, could that be the issue? 

[Hrvoje-CRO]

Hi Kjelt,
Could be main cause of that be alfa fluitin's flux? And no, it is NOT due to usage of spray that i mention as a cause.
I ask that because i've noticed on another PCB something strange. One tiny line near solder joint is covered with flux residues and exactly on that part soldermask has "bubbled". 

Ok if spray is not the cause: the marked places are all ground planes, you needed to apply much more (longer) heat for soldering those spots, could that be the issue? 

Good question! Actually, i think, did i maybe put too much heat into those spots? You mean that?

Interesting, because, wider lines are also affected, especially where i soldered connectors with thicker pins... there you need to apply more heat.

[peter.mitchell]

I still think it is Non-SMOBC-soldermask, you can check by very gently scraping off some solder mask over a track/plane in a non visible area.

[Hrvoje-CRO]

I still think it is Non-SMOBC-soldermask, you can check by very gently scraping off some solder mask over a track/plane in a non visible area.

It is non SMOBC, no copper on PCB, just galvanic tined.