IPC standards question

[gohyl]

There are unusual gold deposit like in between pads. Is it normal. No electrical short when measuring the pins with multi meter.

 

[Miner]

No, this is not normal, and I would be concerned about longer term reliability issues as this could make it easier for other things to form such as conductive filament formation, dendritic growth, whiskers, etc.

 

[gohyl]

No, this is not normal, and I would be concerned about longer term reliability issues as this could make it easier for other things to form such as conductive filament formation, dendritic growth, whiskers, etc.

How this happened? Is it copper dissolution after wave?

 

[Guest]

Have you talked to your PCB manufacturer?

 

[outdoorsNW]

Is this under the soldermask or on top?

 

[gohyl]

Have you talked to your PCB manufacturer?

Do not see such at raw pcb.

 

[gohyl]

Is this under the soldermask or on top?

Under the soldermask.

 

[gohyl]

Under the soldermask.

Apparently it's above the solder mask and not under the solder mask.

 

[gohyl]

Did an eval run :
- Raw PCB - No gold deposit observed in between pads.
- Paste Printing > SMT > Reflow = observe gold deposit in between pads.
Surprising the gold deposit can be scrape off easily.
Can i conclude this is a copper dissolution from the copper pad? and now the root-cause?

 

[Ninja]

Surprising the gold deposit can be scrape off easily.
Can i conclude this is a copper dissolution from the copper pad?

Ummm...last I checked, gold and copper are two different metals... Have you confirmed what the deposit actually is?
SEM/EDS
WDS
heating for oxidation
wet chemistry/dissolution
any of these or other tests to confirm the actual chemistry of the deposit?