Hi Bob,

We went through this at my last job using Humiseal products.  Our final
conclusion - completely strip, clean and recoat the assembly.  This process
maintained identical quality levels for assemblies which required rework and
those that didn't - a requirement from our customer.  Otherwise you end up
with a residue around the reworked area - check it with a black light.

At what pressure are you spraying the assemblies?  I'm guessing 25 - 35 psi.
I've seen plenty of coatings lifted off the board after it was run through
an aqueous cleaner.

Hans

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Hans M. Hinners
Process Engineer
Toppan Electronics, Inc.
770 Miramar Road
San Diego, CA 92126
(858) 695 - 2222 ext. 241
(858) 695 - 6823 fax
[log in to unmask]


-----Original Message-----
From: bbarr [mailto:[log in to unmask]]
Sent: Thursday, December 21, 2000 9:22 AM
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
---------------------------------------------------------------------------------