Hi Brian,
Once upon a time, but not quite as far back as Brian went, the MIL-STD-2000
requirement stated:
"When an external liquid flux is used in conjunction with, flux cored
solders, the flux shall be of the same manufacturer's type."
This was further clarified to mean from the same manufacturer (to avoid
incompatible proprietary ingredients) and normally was required to be
documented as compatible to support the contract. This commonly took the
form of a written coordination with the vendor source for the flux.
Mel Parrish
Director, Training Materials Resources
Soldering Technology International
102 Tribble Drive
Madison, AL 35758
256 705 5530
256 705 5538 Fax
[log in to unmask]
www.solderingtech.com
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Brian Ellis
Sent: Tuesday, March 11, 2003 8:41 AM
To: [log in to unmask]
Subject: Re: [TN] Mixing fluxes - documentation vacuum
John
If someone asked you if it would be dangerous to put your head in a
bucket of water and keep it there for ten minutes, what would you reply?
One cannot write specifications or standards governing every stupidity
that people can think up. As it is, we have, BY FAR, too many already.
There is such a thing as commonsense and what you are asking falls into
this category. Dammit, when Moses came down from his mountain, he
carried only ten commandments (OK, I know it was cut down from 14, but
he wasn't allowed to scrap the one on adultery!). I think if there were
one, 'thou shalt not mix fluxes', it would be classed as #23,326,738.
Brian
Vivari, John wrote:
> 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
-----------------------------------------------------
---------------------------------------------------
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
-----------------------------------------------------
|
