New 'no-clean' pastes leave a soft residue following reflow (to enable pin
testing).  The residue is inert on the outside but does contain small
quantities of active ingredients that remain after reflow that are
'locked-up' inside the residue.
Degradation of the no-clean residues can occur during the conformal coating
process and is dependant on the material used to coat the boards (acrylic,
silicone etc.) and how you coat them (dipping, spraying - i.e. exposure time
to solvents).  In addition, trying to clean 'no-clean' pastes that leave a
soft residue can result in the residue being 'smeared' across the board and
not fully removed.
Older 'no-clean' pastes leave hard residues that are more easily cleaned
i.e. Kester 244.


Michael Kipping


-----Original Message-----
From: Marsico, James [mailto:[log in to unmask]]
Sent: 09 May 2002 13:27
To: [log in to unmask]
Subject: Re: [TN] Cleaning of No-clean Assemblies


I may be mistaken, but I thought that some of the no-clean flux residues
were designed to accept conformal coating.  Perhaps your flux manufacturer
can shed some light...

Jim Marsico
Senior Engineer
Production Engineering
EDO Electronics Systems Group
[log in to unmask] <mailto:[log in to unmask]>
631-595-5879


        -----Original Message-----
        From:   Leland Woodall [SMTP:[log in to unmask]]
        Sent:   Wednesday, May 08, 2002 3:42 PM
        To:     [log in to unmask]
        Subject:        [TN] Cleaning of No-clean Assemblies

        Folks,

        We've been asked to investigate the pros and cons of performing an
aqueous
        wash of our no-clean assemblies prior to them receiving an acrylic
conformal
        coating.  Our management team wants the product to be absolutely
free from
        any type of contamination.

        Has anyone had any experience with this?  What are the possible
advantages
        and some of the pitfalls we could anticipate?

        Are there any knowledge sources that you might be able to recommend?

        Any assistance would be sincerely appreciated.

        Regards,

        Leland Woodall
        Quality Coordinator
        Keihin Carolina System Technology, Inc.
        4047 McNair Road
        Tarboro, NC 27886

        Phone:  252-212-1565, ext. 2865


----------------------------------------------------------------------------
-----
        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 e-mail to
[log in to unmask]: SET Technet NOMAIL
        To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
        Search the archives of previous posts at:
http://listserv.ipc.org/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 e-mail to [log in to unmask]: SET
Technet NOMAIL
To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/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 e-mail to [log in to unmask]: SET Technet NOMAIL
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/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
---------------------------------------------------------------------------------