White mask historically has performed different than it's green counterpart. Depending on the pigment used to make it white, it can have an affect on cure, but also the initial exposure step that created the image (I'm assuming we are talking about a liquid photoimagable solder mask). If the UV light does not cross link the mask enough in the initial exposure step the developer will "attack" the mask more in the development stage and diminish performance during the assemble process. In addition to insuring the proper curing steps are observed, which could include a UV cure, I would make sure they are tack drying and exposing the white mask to the manufactures recommendations. If the fabricator is simply using the same steps used to process green mask, this could be creating your problem. Regards, Bob Metcalf Western Regional Manager Atotech USA Inc 1750 Overview Drive Rock Hill, South Carolina 29730 USA Mobile: 714-334-7667 e-mail: [log in to unmask] Internet: www.atotech.com Managing Director: Kuldip Johal This e-mail and any attachments hereto are business documents of Atotech USA Inc. and may contain CONFIDENTIAL OR PROPRIETARY BUSINESS INFORMATION. Unauthorized disclosure and/or use of information contained in this e-mail are prohibited. If you are not the intended recipient, you should dispose of it and not use, disseminate or copy this message or any other files transmitted with it. . From: Frank Kimmey <[log in to unmask]> To: <[log in to unmask]> Date: 08/08/2011 08:03 AM Subject: Re: [TN] White SolderMask Sent by: TechNet <[log in to unmask]> 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 ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. 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