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White Solder Mask Discolored after Reflow Oven

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#59540

White Solder Mask Discolored after Reflow Oven | 15 August, 2009

Help, experiencing discolor of a white solder resist paint after reflow of 250 degree, it turned yellow.

Have tried many paints, no luck.

Anyone knows one that wouldn't change color and holds the white nicely?

Thanks for your support in advance.

ABEasia

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#59543

White Solder Mask Discolored after Reflow Oven | 16 August, 2009

White, lead free * Taiyo America PSR-4000 LEW1 * Huntsman (formerly Vantico, formerly Ciba Geigy) Probimer 77 white solder mask

Also, search around LEDs Magazine [ http://www.ledsmagazine.com/ ]. White solder masks are often used as a reflective background for LED displays and annunciators.

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#59544

White Solder Mask Discolored after Reflow Oven | 16 August, 2009

Hi Dave F.

Thanks for the suggestion, will give it a try.

With Appreciation, ABE.Asia

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#59616

White Solder Mask Discolored after Reflow Oven | 23 August, 2009

Hi Dave,

I haven't tried the Probimer yet, but the Taiyo ink didn't hold up too well. As a PCB fabricator, finding a white soldermask that has good trace coverage and survives 4X solder immersion (HASL) is like the holy grail of white soldermask.

I did find two newer offerings: Sun Chemical and Peters. I don't know the part numbers offhand but these work better than any of the others I've tried. Also, if you want a Super White, then you can have the board house apply a coating of high temp thermal mask over the LPI.

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#59824

White Solder Mask Discolored after Reflow Oven | 9 September, 2009

What is the cause of this discoloarion? Soldermask masterial wrong? Thanks.

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#59895

White Solder Mask Discolored after Reflow Oven | 18 September, 2009

There's not really a good answer except that I think that the industry wasn't really prepared for such an increased use of white soldermask combined with the importance of using the white as a reflecting surface.

Essentially, the resins commonly used in soldermask to date were not capable of staying clear. However, more recent work on this has resulted in these newer offerings that do resolve the issues at hand.

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