Hi TechNetters,

In reply to Alan Kreplick's enquiry, I would recommend both ionic and SIR
testing.

Many new process materials use non-ionic additives that cannot be detected in
ROSE (ionic) measurements but that may be contaminants.

Your PV based on both methods will give you the greatest peace of mind and
verify long term product performance.

As to the cleaner itself, using an OA paste/flux that is truly water soluble
will eliminate the need for any wash chemistry (saponifiers) and save you a
bundle of money (25% to 30%) on capital and a huge amount on consumables.
Saponifiers should only be required where the flux/paste contains rosin.

In an in-line system, this demands proper isolation between wash and rinse
stages and most probably require you to observe regulations on drain. Water
soluble/pure aqueous may be fully closed looped, reduce costs enormously and
minimise drain requirements.

To get thoroughly cleaned assemblies incorporating BGA etc., demands high
performance pumps and high delivery pressure (>15HP) to ensure good washing
under components. It should not demand wash additives to lower water surface
tension if the system is well engineered.

Drying using the same high performances (>15HP) should almost leave redundant,
any IR oven, only being used during initial warm-up for maybe 10-15 minutes -
why bother, its only more unnecessary expense.

Polypropylene machines will do an extremely effective job and cost 30% less
than stainless. Bear in mind that stainless welds will deteriorate in
de-ionised water as it seeks any ions residing, for example, in the weld
carbon residues.

Finally, let me caution you to run the biggest trial you can. A Handful of
boards and run in a machine for 20 minutes will NOT tell you what it will be
like over 24 hours or full scale production. Try also to keep your cleaning as
soon as possible after soldering, the longer fluxes are left, the more
difficult they become to remove properly and the higher the corrosion risk.

Hope this helps.

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 Mail Forum  On Behalf Of Alan Kreplick
Sent:   Friday, August 01, 1997 6:02 PM
To:     [log in to unmask]
Subject:        [TECHNET] Aqueous In-line Cleaner

I will be purchasing an in-line aqueous cleaner in 4q97 and am trying to
come up with a list to compare the systems available & will be using the
cleaner on the SMT line which places fine-pitch (10mil) and BGA's
(micro-BGA's in the future) using OA flux.

Some concerns:

     - best way to measure cleanliness? ionics? SIR? or....

     - use saponifier, and if so, do we need drag-out section to remove
saponifier?

     - hot air blowers only, or with IR heaters?

     - stainless steel vs. ?

     - etc


Any help would be greatly appreciated.


Al Kreplick
Teradyne
(617) 422-3726