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January 2000

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Subject:
From:
"Kelly M. Schriver" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Fri, 7 Jan 2000 08:42:53 -0600
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Mornin' Steve & All -

Adding to the points that Mike and Brian have made is the issue of materials
compatibility.  I've had the experience on more than one occasion that
certain saponifiers would go after certain dry film solder masks like a duck
on a june bug.  The net result being that all of the previously solder mask
insulated circuits,under component bodies became totally bare.  Very messy!!
Have also seen some components whose body molding compounds and marking inks
were sensitive to the saponifiers.

The other item to consider is whether one can put a multipurpose cleaning
system and its media in place and operate it economically.  I've had
experiences both ways, so go with a bit of caution in this area.  We once
evolved a system so complicated that even its manufacturer had some
reservations about it.

Have a fun day.  I'm gonna go watch the deer herd out in the yard.

Regards - Kelly




-----Original Message-----
From: Michael Fenner <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: Friday, January 07, 2000 8:21 AM
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 <[log in to unmask]>
>To: <[log in to unmask]>
>Sent: 07 January 2000 02:36
>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-
>>
>
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