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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