Hi Lyon,

Was it SMOBC (Solder Mask Over Bare Copper)? Occasionally I still see
old legacy boards that call out fused tin covered by solder mask and
some (for whatever reason) just don't want to change the drawing. Of
course the tin reflows, the mask loses adhesion and starts flaking off.
But I doubt that's your problem. When I see a board like that I tell
them that we're going to have to charge them to hand solder everything,
and most (not all) will change the board to SMOBC...hehehe.

You say that there are some boards out of the same datecode that show
this while the rest of them are okay, I would say that's a material
issue. The boards that have the mask peeling off were contaminated with
something (moisture, greasy finger prints, etc) before they were masked.
I would be giving your board vendor a call...

Steve 


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of lyonyuan
Sent: Tuesday, April 8, 2014 5:42 AM
To: [log in to unmask]
Subject: [TN] solder mask peel off after Top sider reflow

Hi Team,

 

We found some PCBA boards(the same date code) with solder mask peel off
after Top side reflow. Material issue or process issue?

 

Lyon yuan

 



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