Just make sure that this blasting is made in a 50% humidity plus
environment.
        Regards,
        Ramon

> -----Original Message-----
> From: Steve Gregory [SMTP:[log in to unmask]]
> Sent: Monday, January 06, 2003 6:29 PM
> To:   [log in to unmask]
> Subject:      Re: [TN] Removal of Soldermask from assembled PCBAs
>
> Hi Frank!
>
> Whoa...you've got quite a task ahead of you! I've never been faced with
> removing ALL the soldermask from the bottomside of an assembly.
>
> I can't think of any good way to use chemicals and restrict it to the
> bottomside of the board... and the point about whatever chemical can take
> off the mask is probably going to damage the laminate is true.
>
> I still think micro-blasting using Crystal Mark is the way to go. As far
> as ESD issues, they use point ionizers at the tips of the nozzles to
> eliminate ESD problems. In fact, they talk about that on their web page.
>
> I used them to remove some cured Loctite from the footprint of a QFP that
> was mistakenly bonded to a board...the entire footprint was covered with
> the cured adhesive (almost 2" X 2"). Getting the part off the board to be
> able to remove the adhesive was fun, believe you me!
>
> The process removed the adhesive, and the mask as well...clean as a
> whistle. We used some SR1000 to re-apply the mask when we got the assembly
> back. They can select the abrasive material that will remove the mask, but
> won't touch the copper.
>
> I'd give them a call, they may be able to turn things quickly for you.
>
> Good Luck!
>
> -Steve Gregory-
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