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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