Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.

Solder mask

Ed Mentzer


Solder mask | 11 December, 2001

Does anyone have experience with different colors of solder mask. I am interested to know if a clear or light color mask is better in the reflow process. Most of the boards we do have a green solder mask. It seems to me that I read somewhere that the clear was better for reflow, since less heat would build up in the board. We are using a Heller 1500 oven. We think we may be having some problems with a 10 layer double sided SMT board. We are in the process of checking to see if the board is delaminating during reflow.

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Solder mask | 11 December, 2001

I'd be surprised if solder mask color is causing your delamination.

We use various solder mask colors on FR4 boards and notice no difference. * ~99% of our boards are a medium green * ~1% of our boards are dark green * One of our boards is caramel brown * One of our boards is Chianti red

Help us understand how the color of solder mask affects the heat build up in the board? Would different thickness of masks affect this also? LPI masks are much thiner than screened masks.

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Michael Parker


Solder mask | 12 December, 2001

Aw Dave - you guys are so fashionable, are the dark green and red combos seasonal? caramel brown like a Pale Ale?

I once heard that the green was chosen because it gives the best color contrast for white silk screens.

As for color reflecting or absorbing heat, I doubt that makes sense at this scale. A big black truck will collect a lot of heat in the sunlight but 2-5 mils of mask would not be reflective or inflective.

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Solder mask | 12 December, 2001

Caramel is more like a amber ale than a pale ale, although not as redish as the amber. Actually, it's more like caramel. It is real brittle and scratches easily. If we built the board more often, we'd change it to a more familiar material.

Naw, no seasonal stuff here. Although, we do allow seasonal decorations in the break room.

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