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Soldermask color relating to thickness

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SMTA-Matthew

#83797

Soldermask color relating to thickness | 22 November, 2019

We have some circuit boards where the solder mask seems clear instead of green on top of some of the tented via pads. No gold deposited during the ENiG process and no solder sticks to it but why is it clear and does it have any correlation to the thickness of the mask? Could it be a pigment issue? Pictures available.

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#83799

Soldermask color relating to thickness | 22 November, 2019

I'd guess ...

+ Pads have no solder mask, clear or otherwise.

+ Pads won't take solder, because you're trying to solder to nickel.

+ Nickel on the pads is oxidized and is sticking out its tongue at the flux you're using.

+ Something went south with you supplier's via tent process

What does your board fab say? Have you sectioned a board?

[it's always fun to blame the board fab for everything bad that happens in production. If that doesn't work, blame the knitters.]

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#83805

Soldermask color relating to thickness | 24 November, 2019

If you want to check if solder mask on tented via, better to do cross section to have a clear view.

Sometime supplier will not tell you the truth once you ask question for potential quality issue.

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