Bev, Sheila and others,
As I understand it, the purpose of cleaning is essentially to remove
potentially harmful flux residues. Remember that there is no such thing as
no-residue fluxing.
Now, if you wish to be environment friendly in process, why not use water
soluble flux that require only water for removal - not even a saponifier!
Granted you need a damn good cleaner, but there are hundreds out there.
By the way, when you run your SIR tests, you should try to take frequent
samples because we have research proving that dendrites can form within 20
minutes. So you need current limiting resistors to preserve them for failure
analysis and frequent measurements to make sure you have not missed anything.
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 On Behalf Of Bev Christian
Sent: Wednesday, November 19, 1997 9:19 PM
To: [log in to unmask]
Subject: Re: [TN] ASSY: Cleaners
Sheila,
We have started to look at this solvent from the point of view of does
it meet Nortel modified BellCore requirements for the telecommunications
industry. This test set includes copper mirror, halide ion test (silver
chromate paper), surface insulation resistance and a more stringent
electromigration test (includes compatability with permanent solder
masks, as well as the usual 85C/85%RH, 20 days, 10 V DC, 100 V measure
potential). The results to-date:
Great Lakes Chemical Corp's CN2309 failed
Albemarle Corp's Abzol EG passed
Envirotech International Inc.'s Ensolv is still under test
We have also looked at some of ETEC's fluoroiodocarbon mixtures and
presented a paper last week at the 5th Chemical Congress of North
America on our preliminary work. These are compatible with most of the
plastics of interest to the electronics industry. Two passed
preliminary "BellCore" testing. These materials are presently very
expensive and at least one of them does not smell very nice.
One other thing about all of this "stuff": people talk about ODP's and
GWP's, VOC's, but I wonder even if a compound itself has good "numbers",
what about the process to make it?. For instance, if a material has a
very low global warming potential but if it takes enough energy to make
a kilogram as it does to keep all the people in the Canadian Arctic warm
for a winter, I doubt we are ahead. (Some exaggeration here, but I am
trying to make a point.) This is the added information we need to see
from suppliers for anything. Certainly it is the sort of thing we are
starting to get asked for by our customers. We need to look at the
whole picture, the laws of thermodynamics still apply, even if we didn't
like them in university! :)
My personal, present bottom line: I prefer Axarel 2200 from Petroferm
(initially formulated by Dr. Ken Dishart of DuPont). This is a good
flux residue solvent that does not go after labels and their printing.
It is hydrocarbon based so if you are in one of the air quality
authority jurisdictions of California this might be a problem for you.
It also burns, of course.
I think I have got a little carried away here. Hope nobody minds.
Perhaps it will spark some useful debate.
Neither myself or Nortel has any vested interest in any of the companies
mentioned and this information is provided purely for information
purposes only. No responsibility for the use of any of these materials
is accepted, implied, etc.. in the presentation of this information.
Bev Christian, PhD Chemist
Manager,
Materials Engineering Laboratory
Nortel
Belleville, Ontario CANADA
>----------
>From: Sheila Smith[SMTP:[log in to unmask]]
>Sent: Wednesday, November 19, 1997 1:36 PM
>To: [log in to unmask]
>Subject: [TN] ASSY: Cleaners
>
>Hi Technet,
>
>Does anyone have any experience with using n-propyl bromide as a general
>cleaning solvent for electronics? Just reviewing the data sheet I've got,
>materials compatibility may be an issue -- just wondered if anyone had
>already been down this road & is willing to share. Thanks!
>
>Sheila Smith, TRACOR AES
>
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