Lee
I don't like your suggestion of local cleaning with IPA or a proprietary
product. All you will do is to spread the contamination over a wider
area, mayb, if you're lucky, rendering them invisible but asking for
long term trouble after re-coating.
Brian
Lee Whiteman wrote:
>
> 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]
> >
> > ------------------------------------------------------------------
> > ---------------
> > Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
> > To unsubscribe, send a message to [log in to unmask] with following text in
> > the BODY (NOT the subject field): SIGNOFF Technet
> > To temporarily halt delivery of Technet send the following
> > message: SET Technet NOMAIL
> > Search previous postings at: www.ipc.org > On-Line Resources &
> > Databases > E-mail Archives
> > Please visit IPC web site (http://www.ipc.org/html/forum.htm) for
> > additional
> > information, or contact Keach Sasamori at [log in to unmask] or
> > 847-509-9700 ext.5315
> > ------------------------------------------------------------------
> > ---------------
> >
>
> ---------------------------------------------------------------------------------
> Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
> To unsubscribe, send a message to [log in to unmask] with following text in
> the BODY (NOT the subject field): SIGNOFF Technet
> To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL
> Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
> Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
> information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
> ---------------------------------------------------------------------------------
---------------------------------------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------
|
