In a message dated 03/01/2000 7:28:24 PM Central Standard Time,
[log in to unmask] writes:

> Hello Guys
>
>  anybody knows about suppliers for high temp solder paste?
>  And that is lead free?

Hi Jonathan!

Most all manufactures of solder paste can supply you with a "High Temp"
alloy, as Phil suggested Indium is one source. The most widely used (as far
as I know) is a Tin/Silver alloy. SN96/4AG which of course is lead free...

But the curve that's thrown into this, is the solderable terminations of the
components....as far as I know, everybody that manufactures components
(except for Texas Instruments) finishes the solderable terminations with
tin/lead. The mix of the tin/lead on the terminations will affect the desired
operating temperatures that the high-temp solders are being spec'd out for...

For instance, a solder that has a liquidous temp of around 230 degrees C.
(average for a SN96/AG4) maybe lowered because of the mix of the termination
alloy on the component that will happen with the paste during reflow...and
then possibly  not perform as intended because of that fact. For instance
talking about oilwell downhole boards, they need every single degree they can
get as far as high temperatures go. You can imagine that it's not a cheap
deal to pull a oil-well head out from 5,000 ft. or more to fix a board that's
failed. So a whole lot depends on the application...and what the operating
temperatures are.

Then the final curve that's thrown into th whole deal is whether or not the
components can stand the heat while you're trying to reflow the whole
deal...getting into high temp solders (or lead-free stuff for that matter) is
a big challenge, and it's not gonna be easy...

-Steve Gregory-

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