Jack,
Looks like could be caused by incomplete curing of soldermask.
Baking would complete curing process.
Delamination of Soldermask seems to be commonly caused by poor cure and then to high a thermal excursion (i.e. soldering).
I would start with the PCB fabricator and look at their soldermask curing process and times.
It is possible the white mask needs a bit more time then the conventional green type.
I would definitely talk to the PCB supplier about the failure as I would think the assembly just caused a fab failure mode to appear.
Just some thoughts,
FNK

Frank N Kimmey CID+
Manager - PCB Design
Powerwave Technologies Inc
Mobile - 916-670-0645

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Jack Olson
Sent: Monday, August 08, 2011 7:47 AM
To: [log in to unmask]
Subject: [TN] White SolderMask

Greetings,

Have any of you experienced mask problems like the ones shown in these
pictures?

http://frontdoor.biz/PCBportal/WhiteMask.jpg

The bottom picture shows exposed copper, and I believe there is a copper
plane on the top layer.
(this has happened to different boards, different lot codes, but MIGHT be
the same batch of mask)

What I'm wondering is, is it more likely that the problem is related to the
fact that the mask is WHITE, or that it is some other problem?
If the properties of white mask are different, maybe it doesn't adhere as
well to the surface? I remember back in the olden days they used to ask us
to break up solid copper planes so the mask would stick better to the
laminate, but I haven't heard of anyone having problems with that for a long
time.

The supplier said they baked some bare boards and ran them through the oven,
and the problem went away, but we are reluctant to just blindly add a
permanent baking step if there are other considerations.

Jack


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