Graham is correct in describing water alone not being adequate to effectivly handle the cleaning of OA today.
Smaller packaging requirements (bga, COB, flipchip) have put a kink in an otherwise easy/simple/cost effective wash process.
Whether thru solvency or saponification something is needed to reduce the surface tension of water to allow cleaning the flux under these components.
Some folks (contract mfgrs.) have resolved to pre-soaking in a chemistry whenever a contract with bga's or whetever comes down the production line. This relieves them from charging the big gallon use in-line with chemistry.
The PC document mentioned describing the process at Lockheed is available electronically.
Contact me off line and I can forward to you.
Regards,
Charlie Pitarys
Process Development Manager
Kyzen Corporation
[log in to unmask]
603-622-2900 x115
>>> Graham Naisbitt <[log in to unmask]> 08/20/99 06:31am >>>
Cecilia, and others,
I believe that the original work for qualifying an OA process for the
military was conducted by Bob Clarke of (then) Hughes Missile Systems in
Tucson, AZ.
I still have a copy of that report provided by Bob Clarke.
To my knowledge this formed the basis of the MIL-F-14256 spec., which
(facilitated or approved?) the OA process.
The materials used in this programme were HF1149 flux (H = Hughes F = Flux
11 = November and - you guessed it - 89 = 1989) As Kester is the "Marketing"
arm of GM/Hughes, it fell to them to "market it" but they found it necessary
to modify the formulation for better processability which resulted in
HF1189A.
The solder paste that was used was Microbond WS300, which may well have been
based on the same flux formulation
- lemon juice and water, then apple juice and water, but maybe I am just
over-simplifying the chemical make-up :-)
When this MIL Spec., along with MIL-P-28809 and MIL-Std 2000, were
"Cancelled without replacement" in June 1995, no other materials were
qualified - although there are many excellent new materials available!
The best new information published (to my knowledge!!) was the article by
Linda Woody entitled "Cleaning LCC Assemblies" published in Precision
Cleaning Magazine, February 1999. Linda is (or was) a Staff Engineer at
Lockheed Martin Electronics and Missile Systems, Ocala Florida. (Hey, home
of the lemon juice? :-)
As I now understand it, with the newest component developments, such as
Flip-Chip, COB, BGA etc., OA + water alone is not adequate. You need to add
saponification to the cleaning regime. This ups the cost of the cleaner and
the cleaning process by around 30% - but that is what it takes!
Now finally, in answer to your question about water soluble flux residues
and their effect on the reliability of the product: They will kill the
product of they are not removed.
I hope this will help but that it will also encourage some others to join in
with info about cleaning.
Regards,
Graham Naisbitt
[log in to unmask]
WEB: http://www.concoat.co.uk
CONCOAT Ltd
Alasan House, Albany Park
CAMBERLEY GU15 2PL UK
Tel: +44 (0) 1276 691100 Fax: +44 (0) 1276 691227
----- Original Message -----
From: Cecilia Alkhagen (EMW) <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, August 19, 1999 2:33 PM
Subject: [TN]
> Hello!
>
> I need some help on the following topic.
> Is there any information available on using water soluble flux and paste
in the military/defence industry?
> Does anyone have experience with this kind of flux system for military
applications?
> How does the residues from water soluble flux affect the reliability of
the product?
>
>
> Cecilia Alkhagen
> ******************************************
> Ericsson Microwave Systems AB
> Production Engineering Development
> Bergfotsgatan 2
> S-431 84 Mölndal
>
> Telephone +46 31 747 0000
> Direct +46 31 747 0288
> Fax +46 31 747 2635
>
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