Hi Brian!  It is rare but I disagree with you on one point in your 
details. As a society we seem to jump to the "let's ban" option far too 
often. I would offer a different approach - let's make the system more 
efficient and less wasteful. We have enough smart engineers that we should 
be able to design systems where the fluid loss is very very low or 
potentially zero. I understand that would make systems more expensive but 
then we would truly find out where Vapor Phase soldering is really 
necessary. Rockwell Collins utilizes Vapor Phase soldering as it is the 
most efficient and effective way to solder some of our thermally demanding 
designs. Condensation soldering has its place with our other soldering 
methodologies and should be used in a responsible manner. We have all 
witnessed the impact of the environmental legislation where many of the 
substitutions are more harmful to the environment than the material that 
was banned. Our goal should be a balance - ban materials where acceptable 
substitutes are available, be more controlled and efficient with materials 
that have no substitutes and submit to recovery/recycling practices to the 
largest extent possible.  As a  material engineer, I don't believe banning 
the use of materials is always the best approach. I know you are a 
champion the balanced approach so I believe the same approach could be 
used for Vapor Phase fluids.

Dave Hillman
Rockwell Collins
[log in to unmask]



From:   Brian Ellis <[log in to unmask]>
To:     <[log in to unmask]>
Date:   12/07/2012 12:26 PM
Subject:        Re: [TN] Termination finishes, Cu thickness under Ag, 
Au-Pt-Pd
Sent by:        TechNet <[log in to unmask]>



I agree with you, Bev. If you lose only 1 kg of the stuff this year, on 
a linear scale (in reality exponential, but the difference is small), 
there will still be about 990 g of it floating round the earth, warming 
it, 100 years from now, 980 g in 2 centuries, 900 g in 3012 and 500 g in 
somewhere round 10012. In each year, in that time, your 1 kg will have 
the same effect as if you had burnt fossil fuels producing about 10 
tonnes (yes, 10,000 kg) of CO2.

Is that a legacy you want to leave your children, grand-children, 
great-grand-children up to your great^25-grand-children?

The problem is that the fluid has to be stable for more than 5 minutes 
while boiling at the temperature of soldering and the vapour has to have 
high density. These factors preclude any organic substance with a C-H 
covalent bond or any element with a single electron missing (Group VIIB) 
in its outer ring other than fluorine, which has an extremely tight 
bond. Even chlorine, the next one down, has a weak bond which would be 
rapidly destroyed at soldering temperatures, so would be useless for the 
job. This implies that the substance must be perfluorinated, whether a 
complex alkane or cyclic compound. The problem starts in that the 
covalent bond is so darned strong that there is no widely available 
natural mechanism, such as hydrolysis, to break the substance down; it 
requires pyrolysis at >1000°C to do so. The occasional molecule may be 
split by a collision with a high-energy radiated particle and this is 
why most perfluorinated substances have atmospheric residence times of 
the order of thousands or tens of thousands of years - without those odd 
collisions, the lifetime would be infinite.

In practice, as the perfluorinated substances are so inert, it is 
unlikely they would bond with anything on a printed circuit assembly but 
the odd molecules could be imprisoned in the molten flux residues or 
simply trapped under components. This is why you lose your kg or so of 
fluid each year, no matter how good your machine is at recovering as 
much vapour as possible, either by long freeboard dwell times and/or 
vacuum extraction or other mechanical means. This is inevitable. OK, one 
well constructed machine produces a kg or so of losses per year and 
isn't going to make much difference to the climate change caused by the 
teragrams of CO2 emitted by us annually, nor is it likely to be 
restricting to lose a few hundred dollars-worth of the stuff. If, as has 
been suggested, every assembly plant in the world had one, then we are 
talking about hundreds of thousands of such machines, some of them cheap 
and highly emissive, spewing out an aggregate of many tonnes of the 
substances each year. It is conceivable that this would overtake CO2 as 
the chief cause of the greenhouse effect, because the atmospheric 
residence time of CO2 is of the order of a hundredth that of the PFCs 
and is more easily sequestered, being ionically active in the presence 
of water vapour.

I therefore dispute, in the strongest possible terms, the contention 
that vapour-phase soldering should be allowed to proliferate. Rather, it 
would be wise to avoid it.

There is also a political aspect to the question. As we have seen at 
Doha recently, there is discord as to how to handle greenhouse gas 
emissions. It is probable that we are at a turning point and that, in a 
year or two, the nations will agree that something must be done to 
reduce GG emissions. This will involve increasing regulation. CO2 will 
be difficult to regulate but PFCs will be easy, just as the Montreal 
Protocol regulated CFCs. I foresee that PFCs could be phased out from 
manufacture over, say, a five or ten year period, at the end of which 
all the VP reflow machines will be worth only their scrap metal value.

Brian

On 07/12/2012 03:03, Bev Christian wrote:
> "No self-respecting electronics manufacturer should be without a 
vapor-phase
> soldering machine in the facility."
>
> Sorry, I cannot agree.  We tried one and then sent it back. We have a 
ton of
> RF cans with small holes in them for underfill application.  The heat
> transfer liquid condensed inside the cans and we couldn't get it out. It
> was still there days, probably weeks later and as has already been noted 
the
> stuff is expensive.  And how many of the liquids being used are still
> incredibly excellent global warmers? I haven't looked at their tech 
sheets
> lately.
> Bev
>
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
> Sent: Thursday, December 06, 2012 7:38 AM
> To: [log in to unmask]
> Subject: Re: [TN] Termination finishes, Cu thickness under Ag, Au-Pt-Pd
>
> We have two vapor-phase reflow machines here at GD, and I work with VPS 
at
> other companies in the area. The ones we use are from R&D.
> http://www.rdtechnicalservices.com/System-RD2.cfm
> We have an RD-1 and an RD-2, and I am supporting the installation of an
> RD-52 at another site, and have used all three machines at various
> companies.
>
> No self-respecting electronics manufacturer should be without a 
vapor-phase
> soldering machine in the facility.
>
> For high-mass, difficult-to-solder assemblies, VPS just cannot be beat. 
VPS
> is also an excellent method for performing some of the more advanced
> processes such as compliant lead attachment, BGA reballing, CSP and 
flipchip
> reflow, etc. At one location we set up a really good process for
> manufacturing PoP components, including the die-attach where the 
die-bond
> epoxy is cured at the same time the die is soldered. Having an 
oxygen-free
> atmosphere really helps.
>
> Also, I have found R&D to be a really good company, and the owner is a 
real
> square shooter. They have great VPS machines and good service. I don't 
have
> any experience with other VPS systems, so I cannot comment on that. I 
have
> no financial interest in R&D, just a lot of good experience.
>
> As with any VPS, proper maintenance is required. With condensation 
soldering
> you will get a buildup of flux on the inside of the machine and it must 
be
> kept clean. I strictly enforce a monthly maintenance program, and if 
done
> diligently the machines will last a long, long time. For the larger VPS
> systems a small chiller is usually required, so keep that in mind when
> considering purchasing a system.
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Robert Kondner
> Sent: Wednesday, December 05, 2012 2:37 PM
> To: [log in to unmask]
> Subject: Re: [TN] Termination finishes, Cu thickness under Ag, Au-Pt-Pd
>
> Inge,
>
>   On the VPSsubject  your comments echo what I have heard.
>
>   Did you get some actual hands on time for experimentation? If so what
> machine?
>
> Thanks,
> Bob K.
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
> Sent: Wednesday, December 05, 2012 3:09 PM
> To: [log in to unmask]
> Subject: Re: [TN] Termination finishes, Cu thickness under Ag, Au-Pt-Pd
>
> Hi Inge!
>
> Welcome back ol' buddy! I for one, have missed you here! Wish we could 
get
> Paul to drop in once in a while. But I know that will be unlikely.
>
> Me a bagpipe blower? You have got to be kidding me! I don't even know 
how to
> hold one of them things much less play one! They look kinda' creepy to
> me...like an octopus or something. But when I hear "Amazing Grace" being
> played on bagpipes, my heart pounds and I get goose bumps.
>
> I've not faded away, I'm still here, just don't have as much to talk 
about
> as I used to. Anyways, this group has never been about any one person, 
it's
> always been about all of us. Some have been here longer than others, but
> what has made this email forum as solid and long lasting as it has been, 
has
> been the contributions from everyone in this group. I hope that this 
will
> continue.
>
> I'm dealing with what I guess you could call a "speed-bump" in my life's
> road right now, but I plan on being here for a long time...
>
> Again, welcome back!
>
> Steve
>
> -----Original Message-----
> From: Inge Hernefjord
> Sent: Wednesday, December 05, 2012 11:55 AM
> To: [log in to unmask]
> Subject: Re: [TN] Termination finishes, Cu thickness under Ag, Au-Pt-Pd
>
> Hi Wayne & collegues,
>
> heard from Joyce that you missed my comments. Sorry for that. When Steve
> Gregory faded away as kind of bagpipe blower in the TN brigade, I lost 
some
> contact with the troops march and became last one and with time I saw 
the
> troops at distance. Well, with  my old legs, seems as I have to get lift
> with a jeep and catch up with you.
>
> On the theme you just discuss with Julie, I'd say to her not to mix with
> changing the component finish immediately. Doing such things can end in 
a
> never-ending-process. I am not updated with what is actually going on, 
so my
> advice may not be of any help, but there is one soldering method that 
have a
> very generous process window and that is VPS, Vapour Phase Soldering. It 
has
> some very attractive advantages, like instant and simultaneous heating,
> extremly low Oxygen presence and is very fast. All properties that makes
> even many poor weldable>acceptable weldable. You may not be able to try
> this, of some reason. Just wanted to put up a finger and feel the wind
> direction
>
> Inge
>
> On 5 December 2012 00:41, Thayer, Wayne - IS
> <[log in to unmask]>wrote:
>
>> Hi Julie-
>>
>> Sorry for the late response.  I have a lot of experience with this or
>> similar material.  Yes, burnishing helps.  I also deliberately use an
>> iron tip that doesn't wet well.  Paste with SMT works too, and is more
>> controllable.  We typically used the SnPbAg alloy with about 2%Ag, but
>> I don't know if that helped.  Our rule of thumb was you got three
>> shots to solder to it, IF you used pre-heat and were very careful.
>> BUT, this product is cake to solder to compared with AgPd, which most
>> of the thick film commercial products used.  That stuff would only
>> survive a very carefully controlled single reflow.
>>
>> One thing we learned is that the leach rate SKYROCKETS if the designer
>> put the PtPdAu directly on top of thick film Au where the solder was
>> going to be.  That recipe leaches just as bad as plain gold.  The
>> overlap MUST be behind a solder dam.  (The thick film vendors only
>> tell you this AFTER you figure it out on your own!)  By the way, plain
>> gold solders just fine on ceramic using SnAu eutectic solder.  It is
>> very expensive and is quite hot (270C or so).  The joints are very
>> pretty
> shiny silver and very strong.
>>   You can also weld copper wires to thick film gold or silver.
>> MiniCircuits
>> sells piles of RF parts containing tiny transformers attached this
>> way, and this technique is also used on RF inductors which are wound
>> on an alumina mandrel.
>>
>> We ended up having a low temperature copper put on top of the gold
>> whenever we could.  It is much more robust--still wets horribly though!
>>
>> Wayne Thayer
>>
>> -----Original Message-----
>> From: TechNet [mailto:[log in to unmask]] On Behalf Of Steven Creswick
>> Sent: Wednesday, November 28, 2012 8:59 AM
>> To: [log in to unmask]
>> Subject: Re: [TN] Termination finishes, Cu thickness under Ag,
>> Au-Pt-Pd
>>
>> Julie,
>>
>> Yes, the addition of a small amount of Pt does slow up the rate of the
>> conductors leaching into the solder.  From practical experience, the
>> more Pt is added, the better the leach resistance.  However, the more
>> Pt is added, the greater are wetting problems.
>>
>> Thick film ink suppliers [used to] offer inks with different amounts
>> of Pt so you could slightly 'chose your poison.'
>>
>> Also can depend on whether it is a fritted, or a frit-less, system.
>>
>> Like Mike says - BURNISH before solder IS the general rule!
>>
>> Never was something you really 'wanted' to solder to, unless you had
>> no other choice.
>>
>>
>> Steve Creswick
>> Sr Associate - Balanced Enterprise Solutions
>> http://www.linkedin.com/in/stevencreswick
>>                           616 834 1883
>>
>>
>>
>> -----Original Message-----
>> From: TechNet [mailto:[log in to unmask]] On Behalf Of Julie Silk
>> Sent: Tuesday, November 27, 2012 8:02 PM
>> To: [log in to unmask]
>> Subject: Re: [TN] Termination finishes, Cu thickness under Ag,
>> Au-Pt-Pd
>>
>> The claim of the supplier is that the Pt prevents the Au from
>> dissolving into the solder.  Hmmm.  Can anyone back that up?
>> The recent info on this is that it's looking like a wettability
>> problem more than a dissolving-into-the-joint problem, although
>> neither is confirmed.
>>
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