There are standards regarding surface resistivity which are dealing with
this topic. If you need more details please contact me offline.
The bellcore standard also deals with this topic.

Siggi

-----Original Message-----
From: Vivari, John [mailto:[log in to unmask]]
Sent: Dienstag, 11. März 2003 15:11
To: [log in to unmask]
Subject: [TN] Mixing fluxes - documentation vacuum


Dear TechNetters,

A customer of ours came to us with a request for a reference to an IPC
document or other industry standard that explicitly states the hazards of
mixing flux types on an assembly.  He asked for this because his contract
manufacturer built a set of boards using a No-clean solder paste and
reworked some BGAs with a water soluble solder paste.  The contract
manufacture states that he cannot find a standard "anywhere" that says the
flux types should not be mixed or that there will be any long term
reliability issues.  I know this seems naive but that is their position.

We have searched our library of specifications, books, and industry
periodicals and have come up empty except for vague statements about having
to clean between soldering operations for certain classes of product without
explaining why and a reference in Ning-Cheng Lee's new book cautioning
against combining incompatible fluxes between reflow and wave soldering.  We
are well versed in the hazards of mixing our own fluxes (never mind others)
but have never been asked to provide "industry standard documentation"
before (as opposed to a letter of explanation).

Can anyone point to a reference that we have missed?

Hopefully yours,

John Vivari
Technical Service Engineer
EFD Inc.
[log in to unmask]
www.efdsolder.com
Ph: 401-333-3800
Fx: 401-333-4954

---------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8e
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 or (re-start) delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL or (MAIL)
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 1.8e
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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
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
-----------------------------------------------------