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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