TO:  W.G. KENYON and others ...

Thanks for your quick reply !

You're right, it should be : 
"At our new SMA facility we now use solder pastes WHICH show
flux-residue after reflowing."

At this moment, cleaning of the SMT P.C.B.'s is done
with a special cleaning product in a Systronic machine.
THIS IS NOT AN IN-LINE MACHINE. IT IS USED BY THE THROUGH HOLE
PRODUCTION AS WELL. PERHAPS THAT IS A PROBLEM TOO.

My questions are :

1) can anybody give me an advise on which type of solderpaste
   (SEE ALSO QUESTION 2) I should consider testing.
NOT WITHOUT MORE INFORMATION- SEE BELOW

2) is cleaning with water or IPA (or mixed) a good option for SMT
   related products and who has experience with it ?
ALCOHOL BY ITSELF CANNOT CARRY ENOUGH ROSIN FLUX RESIDUE, YOU
WILL HAVE TO CHANGE IT OUT FREQUENTLY AND YOU MAY (ALMOST
CERTAIN) TO HAVE "WHITE RESIDUE" PROBLEMS.  SAME FOR MIXED IPA
AND WATER.
IF YOU USE WATER SOLUBLE PASTE (FLUX) THEN THE QUESTION IS ONE OF
PRODUCTION VOLUME. HIGH PRESSURE WATER SPRAY MACHINES CAN CLEAN
EFFECTIVELY IN THE 0.005 INCH STAND-OFF RANGE WITHOUT ANY
PROBLEM, HAVE BEEN REPORTED TO CLEAN AS LOW AS 0.002 INCH.
HOWEVER, YOU WOULD HAVE TO HAVE ENOUGH PRODUCTIO VOLUME TO
JUSTIFY SUCH AN INLINE CLEANER, WHICH IS NOT TYPICAL OF EUROPEAN
PRODUCTION.  ALSO, IF YOU HAVE HIGH VOLUME, THEN THE SOLDER PASTE
STENCIL LIFE IS NOT AS IMPORTANT, SINCE IT IS BEING REPLENISHED
REGULARLY. LOW OR INTERMITTENT VOLUME USERS ARE OFTEN BETTER OFF
WITH ROSIN BASED PASTES, WHICH DO HAVE A LONGER LIFE ON STENCIL.

I hope your answers can help me in selecting the right
solder-paste(s).
THE ABOVE MAY NOT GIVE YOU A QUICK ANSWER, BUT MAY HELP TO SET
YOUR PRIORITIES IN THE EVALUATION PROCESS.

Your have an ineteresting point here. Production volume, i mean. 
Our volume is low. Much costumers are producers of "specials".
We try to be "flexible", thus meaning low production volumes.
The switch to higher production series, because of our automated SMA
process, is difficult to make. Back to the subject ...

What you stated about stencil life is affecting my decision. We now have
a manual stencil printer, but want to buy an in-line machine. 
(NO COMMERCIALS PLEASE). When our equipment and organisation is ready 
for it, we want to change to higher volumes. At the moment we're in
the "grey area" of changing process, organisation and materials.

I think i will go and think it all over, thanks for your useful remarks !

Ivo de Rooij
Process Engineer/Operator Surface Mount Assembly
Fokker Elmo BV

-- Houdt Fokker in de lucht -- (Keep Fokker in the air) --