Re Graham's resonse, I have a couple of additional comments:

> ----------
> From:         Graham Naisbitt[SMTP:[log in to unmask]]
> Sent:         Friday, October 10, 1997 4:27 PM
> To:   [log in to unmask]
> Subject:      Re: [TECHNET] Assy:  Water Soluble Flux
> Are SIR tests required to prove cleaning methods?
        "Required"??  By contract:  Depends on what spec you fab to. As
I recall only MIL-STD-2000A (now cancelled) and ANSI/J-STD-001B
specifically discuss SIR.  In ANSI, it's only required for
"non-traditional" fluxes (ie. fluxes not classified as "RO or RE - L0 or
L1  (rosin or resin)-(<0.5% halide)".    The ANSI doesn't require doing
SIR for a change in cleaning (but it is strongly recommended).
        Required (ie. really good idea to check): We do SIR when we
change flux chemistries, soldering or fluxing method, substrate
(material or vendor) and cleaners.

> Are SIR tests required for MIL/DOD contracts?
        See above, depends on contract.  Typically not when just
changing cleaner but in some cases when changing flux.

> Can WS / OA be used on stranded wire?
        First off, most WS/OA fluxes are classified per ANSI/J-STD-004
as H0 or H1 (high activity/corrosivity).  Per ANSI/J-STD-001B (see 4.2),
type H fluxes "Type H fluxes may be used for tinning of terminals, solid
wire and sealed components when performed as part of an integrated
fluxing, soldering, cleaning, and cleanliness test system."  Strictly
speaking it's allowed but typically not recommeded (e.g. above exception
allows H for SOLID wire).  Problem is that these fluxes can be very
corrosive and they wick up wire where they are not totally heated and
not "extractable" for process control tools like Omegameter/SIR.  Also,
if stranded wire NEEDs OA to tin, you have bigger problems.  Tossing the
wire is cheaper than process controls necessary to assure no problems in
OA process on stranded wire.

> Which is the better process for WS / OA, Batch or In-line?
        Actually, depends on fluxing method, cleaning chemistry, etc.
No "one answer"; we've qualified both and in some cases gotten BETTER
results with batch (chemistry "a") vs. inline (chemistry "b").  Also, be
aware that more power doesn't always equate to cleaner PWAs.  We found
REALLY high spray pressures just tend to "bounce" solvent off the
substrate, leaving areas not in direct spray DIRTIER than with a lower
spray pressure.

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