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March 1998

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From:
SteveZeva <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Mon, 30 Mar 1998 09:49:04 EST
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In a message dated 98-03-30 05:25:28 EST, [log in to unmask] writes:

<< But why should we accept this demarkation line? Let's not lower our
 standards just for TIs convienience. Has anybody done any metalurgical
 research into this?>>

    Boy! SOMEBODY must've not had a good weekend! (GRIN) Just joshin'...I
honestly don't think I've lowered my standards, I just understand that
palladium is a different material than a tin/lead plating is, and it is going
to have an affect on how the solder joint appears...it's not going to look the
same, no doubt about it.

    Unfortunately I suppose, I've never had the luxury of having the resources
of a full-blown failure analysis lab, or the time to conduct a study. But, I
have done some what might be considered "un-scientific" tests. One test I've
done that convinced me that there is a good metallurgical bond, is to pull on
a component with a pair of needle-nosed pliers until the pads and traces rip
out of the laminate before the solder joint would fail. Yeah I know, I didn't
put a strain gage whose accuracy is down to the hundreth of a gram on
everything while I was ripping the part up, but I know what I saw...and that
was good enough for me.

     I think there's a lot of people out there in the same position that I've
been in, employed at a contract assembly company working without a lot of time
and/or lab equipment, that has to get product built and out the door in a
certain amount of time. I will say that TI was pretty quiet about everything
when they first started to use palladium, which I don't think was very helpful
when I first ran across the differences in the solder joint appearance. I,
just like everybody else did, thought there was something wrong. But since
that time I've learned to adjust to the slightly different appearance that
certain aspects of a solder joint has with a palladium coated lead.

     As far as having to accept it, I really don't mind. If any company can
come up with different processes and methods to build something easier and
cheaper, that still gives me something that will perform to specification
within it's intended lifespan, then good for them! It is the small incremental
changes in materials and processees that have helped prices for 200mhz Pentium
computer systems drop below $1,000.

     I'm not saying that TI, or palladium causes cheap computers, it's just
that you seem so hung up on the solder joint appearance being different from
the way "they used to look". May I pose a question to you? Do you have any
evidence of palladium coated leads causing premature failures? I'm open to any
inputs you may have...

                                                                       -Steve
Gregory-

P.S. I DON'T work for Texas Intruments, have stock in a palladium mining
company, or work for Electrovert...I'm just a process engineer...

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