Steve,
Could possibly be the manufacturer skippped the UV
bump prior to the final bake cure, which I believe can be
performed after bake also. It is pretty critical because the exposure is
between 3-5 joules.
Tony Steinke
AIT-ATlanta Inc.
----- Original Message -----
From: "Stephen Gregory" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, June 08, 2005 1:53 PM
Subject: Re: [TN] Tiny Blisters on dry-film soldermask
> Hi Bob!
>
> Boards that have been touched-up or hand soldered with RMA
> flux, are cleaned within the shift....that's the way it's supposed to
> go anyway.
>
> I wouldn't have thought it would attack the mask either, and yes,
> it is just only on the surface.
>
> We clean with Kyzen Aquanox 4512P mixed with DI water.
>
> One more question, is the board history now? Has the mask been
> compromised? This is a class-3 radar assembly that doesn't get
> coated.
>
> Kind regards,
>
> -Steve Gregory-
> Senior Process Engineer
> LaBarge Incorporated
> Tulsa, Oklahoma
> (918) 459-2285
> (918) 459-2350 FAX
>
>
> |---------+----------------------------->
> | | "Bob Metcalf" |
> | | <Bob@CircuitSoluti|
> | | onsPCB.com> |
> | | |
> | | 06/08/2005 12:43 |
> | | PM |
> | | |
> |---------+----------------------------->
>
> >--------------------------------------------------------------------------------------------------------------|
> |
> |
> | To: "TechNet E-Mail Forum" <[log in to unmask]>,
> <[log in to unmask]> |
> | cc:
> |
> | Subject: RE: [TN]
> |
>
> >--------------------------------------------------------------------------------------------------------------|
>
>
>
>
> Steve,
>
> How long did the flux sit on the board before wave soldering? RMA fluxes
> do
> not normally attack the solder mask, however RMA's contain alcohol and
> that
> will attack the solder mask. Long exposure prior to soldering could lead
> to
> the type of surface attack (assume surface only) you are seeing.
>
> What type of cleaning followed the soldering?
>
> Bob Metcalf
> Circuit Solutions
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]]On Behalf Of Stephen Gregory
> Sent: Wednesday, June 08, 2005 9:08 AM
> To: [log in to unmask]
> Subject: [TN]
>
>
> Hi All!
>
> My turn to post a picture today...hehehe.
>
> Have this very strange problem with my good ol' freind
> dry film soldermask...eh, what's new?
>
> Take a look at; "Mask Blisters, and Mask Blisters 2" on
> my page at: http://www.stevezeva.homestead.com
>
> These are very little tiny blisters on the backside of a built
> assembly. The board was baked and it was wave soldered.
> The blisters don't appear on the topside of the board at all.
>
> The soldermask is Dupont Vacrel 8140. The little blisters appear
> everywhere there's been touch-up done. It's not just around the
> solder joints, but it looks like the blisters appear where ever flux
> has contacted the mask.
>
> The liquid flux that we use for touch-up is Alpha 615 RMA.
>
> What in the world could cause this sort of thing?
>
> Kind regards,
>
> -Steve Gregory-
> Senior Process Engineer
> LaBarge Incorporated
> Tulsa, Oklahoma
> (918) 459-2285
> (918) 459-2350 FAX
> __________________________________________________________________
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> __________________________________________________________________
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