Dr. Beverly Crusher,
Could you tell us a little bit more about your experience with
PADS? We, I or many of manufacturing guys/gals are morons
about chemical terminology. What's this oxy-business? How
does PADS' process turn tin suface to oxyflu? What is your
experience with PADS? Does it change the chemical property of
tin surface to a molecular structure to inhibit corrosion? How
thin is this coating? How long is the coating good? Any special
process requirement for implementing the fluxless soldering in
production? How practical is it for the future replacement of
no-clean and water-soluble processes?
Well, whatever info I have is good for marketing guys, and is too
good to be true for mfg engineers. Throw away all existing
known processes and go, go for the fluxless soldering? Wait a
minute, I tested a similar thing with an electrically conductive
epoxy for the future replacement of solderpaste. It turned out it
was too good to be true for SMT manufacturing. I'm keeping
these technologically advanced marketing secrets handy in case
our senior management has a future vision of us to become a
world-class manufacturer. Well there's no chance of that
happening, our mfg operation is being marketed out, phased
out, or booted out. Whichever way is convenient for my employer.
Hope oxyflu is not one of those Asian flu.
Sign out
Matthew.
>>> "Bev Christian" <[log in to unmask]> March 10,
1999 10:43 am >>>
Technetters,
A PADS unit can be purchased from Integrated Electronic
Innovations in North
Carolina (919-461-3773). I know a couple of other big
companies have also
played with this system besides us. PADS is especially useful if
you
positively cannot have any organic residues around, like say for
an optical
system.
I wouldn't say it turns the surface oxide resistant but rather
solder-philic. Somehow it transforms tin(II) oxide to either a tin
oxyfluoride or perhaps there is a formation of a hydrogen bonded
adduct
between the surface oxide and hydrogen fluoride produced in the
process.
(Don't worry, from a corrosion point of view, the "coating" is so
thin it is
Bellcore compliant.)
Of course there are always down sides to everything, right, even
marriage?
:) The system uses sulfur hexafluoride, which like CFCs, are
relatively
safe for humans but terrible environmentally. Now there is no
chlorine so
there is no threat to the ozone layer, but SF6 is one heck of a
good global
warmer. With CO2 having a global warming value of 1 SF6 has
a value over
3000! The other thing is that it won't do much for tin(IV) oxide, so
if you
have old parts and boards you are out of luck.
There are also other systems that are sometimes lumped in
with fluxless
soldering, like the SEHO formic acid vapor system of the early
90's, special
very hot systems where reducing gases have been tried, and
even the ROSA
system that uses a vanadium based aqueous reducing solution.
Of course we
could start arguing semantics here, but that is not what I am
trying to
start. The point is there have been/are fluxless units, but I doubt
that is
what your marketing guy was after. These systems are not well
known.
regards,
Bev Christian
Nortel Networks
> -----Original Message-----
> From: Matthew Park [SMTP:[log in to unmask]]
> Sent: Wednesday, March 10, 1999 1:09 PM
> To: [log in to unmask]
> Subject: Re: [TN] Fluxless Soldering
>
> Richard,
>
> This time, I guess, your design engineering manager is right.
There is a
> fluxless soldering process available. If I remember correctly,
one process
> I am aware is called *PADS* (Plasma Assisted Dry
Soldering???). Wow... a
> fancy jargon isn*t it? In this process, components or
assembled boards
> are exposed in a PADS treatment within a vacuum chamber.
This treatment
> turns soldering surface to oxide-resistant by modifying
soldering surface
> layer. From there, you can store components or assembled
boards for a
> specified period prior to wavesoldering, reflow or
handsoldering. You
> don*t need to apply flux to allow wetting, thus no cleaning is
required.
>
> This process is ok for a lab application or a small production
run. I
> don*t have the info handy, but I am sure I have it filed away in
my filing
> cabinets. I can dig out something for you if you need to look
further.
>
> Regards
> Matthew
> Norsat International Inc.
>
>
>
> >>> Richard Hamilton <[log in to unmask]> March
10, 1999 8:46 am >>>
> Hello fellow TechNetters,
>
> Well, we were asked a question by the design engineering
manager yesterday
> if we had considered a fluxless soldering process. We are
aware of a
> process
> called Solid Solder Deposit (SSD), but not a fluxless process
by name.
>
> After the manager read us the email he got from one of the
marketing
> types,
> I tend to believe that he was referring to no-clean process
because of a
> reference in his note about cleaning boards at a previous
manufacturer
> (TI).
> My guess (oh how I hate to guess/assume) is that this
marketing type has
> just mixed up a couple of buzz-words together,.....kinda like
'military
> intelligence'. I mean look at it, 'no-clean flux', I can see how a
sales
> person would want to shorten that to 'no-flux'. Now as usual, it
is up to
> us
> manufacturing people to invent the process that has been sold
to the
> customer!!
>
> And as a side note: Steve -
>
> Your comments on machine maintenance are RIGHT ON!! You
couldn't be more
> correct. Sometimes I cringe at the way some machines are
treated, and the
> surprise that goes on when it does drop out!
>
> Thanks all.
>
> Richard Hamilton
> Clemar Mfg. / Rain Bird
> [log in to unmask]
>
>
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