Jan,
I am not sure if I will be talking out of turn, but Bob Clarke of (then)
Hughes Missiles in Tucson Arizona (maybe now at Fullerton, CA ?) carried out a
development project for water soluble processes for military assemblies that
formed the foundation of the MIL-F-14256 Spec..
Whether a copy of this is readily available, I am not sure, although I do have
a copy myself which I could make available if permission was granted - Is Bob
Clarke out there???
An essential element of his programme involved SIR testing.
Now to answer your questions:
Are SIR tests required to prove cleaning methods?
YES but please refer to my recent posting wherein I suggested the entire
process be checked out.
Are SIR tests required for MIL/DOD contracts?
Not yet to my knowledge but SIR Doug Pauls may be better able to answer that
one.
Can WS / OA be used on stranded wire?
Now they can!
Which is the better process for WS / OA, Batch or In-line?
In-line!! WS / OA are good aggressive products that may allow you to solder
black leaded components - so any residues must be thoroughly cleaned off. This
involves surface attrition as much as solvent power and batch (Dip 'n Dunk)
demands ultrasonics but suffer enormously from poor drying performance.
(Processing >1000 assemblies per week, I know this to be true, and we designed
the system!!)
Why did your consultant recommend WS / OA over RMA?
Because rosin processes demand chemistry in the wash rather than a PURE
aqueous approach. In order to minimise solvent transfer into the rinse stage,
you must isolate one from the other and this involves:
Pre-wash - Wash - Isolation - Rinse - Dry, as compared to:
Prewash - Wash / Rinse - Dry
Result: At least a 30% cost saving on equipment. A substantial saving on your
process / running costs and a process window as big as a barn door!
I am not able to answer your question about government contracts and their
preferences but, WS / OA certainly seems easier and less expensive which
always attracts interest.
I hope this helps and that if you need more, you will please contact me.
Graham Naisbitt
Concoat Ltd Email: [log in to unmask]
Alasan House, Albany Park Tel: +44 (0)1276 691100
Camberley, Surrey GU15 2PL UK Fax: +44 (0)1276 691227
-----Original Message-----
From: TechNet On Behalf Of Jan Satterfield
Sent: Friday, October 10, 1997 9:56 PM
To: [log in to unmask]
Subject: [TECHNET] Assy: Water Soluble Flux
I need a quick education. The company I have recently hired on at,
would like to immediately change over from RMA flux to Water Soluble
flux for both SMT and thru-hole. Most of our work is military. It has
been several years since I've researched this topic.
Are SIR tests still required to prove your cleaning methods?
Are SIR tests only required for government contracts?
Can Water Soluble fluxes be used on stranded wire?
Which is a better cleaning process for Water Soluble flux, Batch systems
or in-line systems?
Have most government contractors switched to WS Flux or still using RMA?
Thanks in advance for all responses.
Jan Satterfield
Sr. Process Engineer
L3 Communications
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