Ketan
It makes no sense using "no-clean" and the cleaning, especially with a
poor solvent which will not remove the metal salts. You would be far
better using water-soluble chemistry and a good aqueous cleaning/drying,
followed by your coating, IMHO. Cheaper, too and no fire or toxicity
hazards.
Brian
Ketan Bhatt wrote:
>
> Dear Mr. Lee,
>
> We are energy meter manufacturing company and on our boards - we are using no-clean solder paste/flux. And we are doing cleaning using IPA and then do conformal coating.
>
> I request you to kindly advise on:
>
> 1) Can we stop cleaning using IPA and do coating directly?
>
> 2) What type of CRC could be used for this application - with details about suppliers.
>
> 3) Pls. also provide details of chemicals required to remove coating for rework.
>
> Thanks and best regards,
>
> Ketan Bhatt
> Secure Meters Limited.
>
> -----Original Message-----
> From: Lee Whiteman [SMTP:[log in to unmask]]
> Sent: Friday, December 22, 2000 1:05 AM
> Subject: Re: Conformal Coating and Aqueous Cleaning
>
> Bob Barr,
>
> I agree with Phil Crepeau on this one.
>
> I've seen some aqueous and semi-aqueous cleaning chemistries remove
> conformal coating from a board at room temperature very efficiently (less
> than 1 minute exposure - it came off like a banana peel off a banana). I can
> only imagine what would happen at an elevated temperature.
>
> It depends on the type of conformal coating used, how well the conformal
> coating was cured, the type and concentration of the aqueous and
> semi-aqueous cleaning chemistries, the operating temperature, and length of
> exposure. From those experiments, I never attempted to run a conformally
> coated board through the aqueous and semi-aqueous processes I implemented.
>
> Concerning damaging the aqueous cleaning system, while I doubt that this
> practice would damage the system, I can envision where conformal coating
> material would leach into the water supply if the conformal coating was not
> completely cured (If anyone has any feedback on this scenario, I would be
> interested in hearing about it.).
>
> I never stripped the entire board - just the area in question. When I had
> operators perform rework on a board, which required conformal coating
> removal, I had them use IPA, or some of the MicroCare cleaning products to
> remove any residue, prior to re-coating that area of the board.
>
> Lee Whiteman
> Senior Manufacturing Engineer
> ACI / EMPF
> Telephone: (610) 362-1200; Ext. 208
> FAX: (610) 362-1290
> E-Mail: [log in to unmask] <mailto:[log in to unmask]>
>
> > -----Original Message-----
> > From: TechNet [mailto:[log in to unmask]]On Behalf Of bbarr
> > Sent: Thursday, December 21, 2000 12:22 PM
> > To: [log in to unmask]
> > Subject: [TN] Conformal Coating and Aqueous Cleaning
> >
> >
> > I have some boards that are coated with acrylic conformal coating. We have
> > to do a few chip replacements. The coating will be selectively stripped
> > around the chips and the rework performed. Is there a problem
> > with sending a
> > coated board through an in-line aqueous cleaner? I am running
> > just water at
> > 130 degrees F. Will the pressure damage the coating? Will the water
> > recycling system become contaminated? Do I have to strip the board
> > completely prior to rework to avoid any problems?
> >
> > Thanks for your help.
> >
> >
> > Bob
> >
> >
> > Robert Barr
> > Manufacturing Engineering
> > Formation, Inc.
> > Voice: 856-234-5020 x3035
> > Fax: 856-234-6679
> > email: [log in to unmask]
> >
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