Charles,
Man, do you ever get some interesting things to do! I unfortunately
don't have a lot to offer except for a few small things.
1)Under #1 do you mean Pd/Pt/Au? This could explain the dull color. We
(and others) have found soldering palladium plated leads with no-clean
fluxes is very flux dependent -some chemistries will do it and others
don't. We're not sure what the difference is, just go by empirical
results.
2) If you have a choice, pick door number 2, sounds like a much more
typical coating (IGON?) and the pads sizes are better.
3) If at all possible I would preheat that ceramic if you can.
Application of that much heat to such a small area of a thin ceramic is
inviting trouble.
I hope you get a lot more help on this one. Good luck!
Bev Christian
Nortel
>----------
>From: Charles Barker[SMTP:[log in to unmask]]
>Sent: Wednesday, November 05, 1997 4:35 PM
>To: [log in to unmask]
>Subject: [TN] Assy: Hi Temp Soldering to pads on Ceramic substrate
>
>Charles Barker@IO-US
>11/05/97 03:35 PM
>
> We have been asked to run some tests to establish procedures for
>attaching leads (24-28 AWG, teflon insul. tinned CU, stranded) to ceramic
>substrate material 0.025" thick. We have a few sample pieces of ceramic
>with the two different "pads" on them to test with. I do not want to start
>out down the wrong path and destroy the samples.
> The following is information I have received from the Engineer in
>charge of this project:
>1. The first substrates have a Pl/Pt/Au metal, about 0.001" - 0.003" thick.
>(Looks dull as all get-out to me and quite thin-closer to the .001"
>thickness.) (Small pads on my samples, about 0.063" square.)
>2. The second substrates have a thick film metal covered with 0.005" thk
>Cu, with 150 microinches typ of Ni, covered with 5 - 10 microinches of Au.
>I don't think that the type of thick film metal matters because of the
>copper. (Large, roomy surfaces to solder to on the samples.)
>3. The solder spec calls out a 5% Sn, 94% Pb, 1% Ag for the high
>temperature solder (HMP). (Liquidus around 300 deg C.)
>
>For any of you that have worked with this type of material before:
>1. Any recommendations or suggestions about soldering iron temperatures,
>dwell time, etc.
>2. What about suggested fluxes? (I don't believe the solder we are getting
>is cored.)
>3. Any special tricks or techniques?
>4. Should we try to pre-heat the ceramic? (This may not be possible with
>the finished product.)
>5. Does anyone have any pull-strength data they might be able and willing
>to share?
>
>Many TIA's
>
>Charlie B.
>
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