Nice idea but how about turning off the saponifier feed when cleaning water
washable flux. By using hot water instead, you would not cause that
foaming... All you have to do is to make sure you segregate and properly
identify the boards.
Just a thought,
Alain Savard, B.Sc.
Chemical Process Analyst
CAE Electronics Ltd.
-----Original Message-----
From: Michael Fenner
Subject: Re: [TN] Cleaning Strategies...
Good thought, but there is no definitive yes no type answer here. Some
general comments
for consideration...
The "saponifiers" you buy for flux removal are basically caustic solutions
which turn the
normally solvent soluble rosin in the flux into a soap which is water
soluble and
therefore can be rinsed off in water. Being alkaline the saponifiers will
also mop up any
acid residues which are present and (although leaving a lot of unreacted
saponifier on the
board), they will usually also contain some sort of solvent acting material
which will
deal with the nonsaponifiable portions of the rosin residues.
So in theory you can use a cleaning system with saponifier in it to remove
water soluble
flux. In practise you will need to think this through to get your process
and control
parameters, monitoring procedures properly established, and then see if it
is viable on a
production basis.
The real problem is the great variety of candidate chemicals that can be
used for flux
makeup. The saponifier manufacturer has optimised his product for removing a
specific type
of flux and will not have tested it for every other possible flux type let
alone brand on
the market. You will need to verify whether the particular types you have
are compatible,
and whether you can meet you cleanliness requirements routinely in
production without
undue waste or heroic control measures.
Putting the odd water sol board into a batch cleaner with saponifier in it
is probably OK,
but to do this on a regular basis is going to use up a lot of saponifier
which actually is
going to pass through the machine unreacted, so you could have foaming and
effluent issues
for example. Also you might find the OA in the water sol product generates
white reaction
products onto your work and so on. As ever drying is one of the things that
can catch you
out in the reality of production practise when going from one machine type /
process
chemistry to another. The stuff may creep into all sorts of places in one
system that it
didn't in the other, especially if you encourage it with the detergent like
saponifier.
Having said all that I think if you still have the old Polyclean literature
on file you
will find that the machines could be configure for water sol or saponify and
certainly
some installations were made dual use with a saponifier chamber which could
be turned on
or off.
So as we say here (and maybe you there) "do a quick suck it and see",
alternatively if you
have been to college: " I suggest you carry out an empirical trial", before
committing to
a proper
evaluation and changeover.
Mike Fenner
----- Original Message -----
From: Stephen R. Gregory
Subject: [TN] Cleaning Strategies...
> Hi ya'll!
>
> Just brainstorming a bit...when you have two different flux processes,
what
> do ya'll think makes most sense, have two different and separate cleaning
> systems, or have one system that will cover both?
>
> Precisely; we do both RMA and water soluble, and have two different
cleaners
> here... an Electrovert MCS-1000 for our RMA boards (which is basically a
> fancy batch cleaner) , and a old Hollis Polyclean for our water soluble
stuff.
>
> I'm thinking that if we had the type of cleaner that would cover all the
> different types of residues would be more cost effective than having two
> separate cleaners. Sure, there would be saponification used (or some other
> type of process to clean RMA residues that wouldn't be necessary when
> cleaning water soluble flux residues) but still, wouldn't that make more
> sense than trying to support two separate cleaners?
>
> Does anybody else do this? Do any of ya'll use one cleaner that does it
all?
> Is it cost effective? I know it depends on the percentage of boards that
are
> RMA vs. water soluble...I would estimate our percentages are about
> 50/50...with the percentages increasing towards water soluble...don't
think
> that we'll ever consider no-clean anytime in the near future, it's just
the
> nature of our business...
>
> As usual, thanks ya'll!
>
> -Steve Gregory-
>
##############################################################
TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c
##############################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in
the body:
To subscribe: SUBSCRIBE TECHNET <your full name>
To unsubscribe: SIGNOFF TECHNET
##############################################################
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information.
If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or
847-509-9700 ext.5365
##############################################################
|
