Hi Kenny!

WOOOO-HOOOO! IT'S FRIDAY!

Back when Texas Instruments first changed their lead finish to Palladium
in 1989 - 1990 without telling anybody, I remember we were doing all
kinds of touch-up that didn't need to be done because of the different
appearance of the solder joints in comparison to solder joints on parts
that had standard tin/lead plating.

I contacted TI back then because I thought there was some sort of
solderability problem with their parts. It was then that I was directed
to TI's; "Palladium Lead Finish User's Manual". It's still available at:
http://focus.ti.com/lit/ml/sdyv001/sdyv001.pdf 

When you read it, it says they told all their users that they were
switching over to a new palladium lead finish, but I don't think that's
true. Nobody I worked with back at that time knew anything about it.
Anyways, It's got a bunch of environmental data that was done when
everybody was using tin/lead solders.

-Steve Gregory-

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Bloomquist, Ken
Sent: Friday, January 05, 2007 8:08 AM
To: [log in to unmask]
Subject: Re: [TN] Qualification of ROHS Components with tin/lead Solder

Hi Don,

We are struggling with the same issue. When we looked into this we
discovered that for many years we were getting "lead-free" component
leads but never called them that.

I too would like to see a compatibility list of acceptable component
lead finishes that can be used in a non-lead-free environment along with
qualification testing.

KennyB

-----Original Message-----
From: N Burtt [mailto:[log in to unmask]]
Sent: Friday, January 05, 2007 1:23 AM
To: [log in to unmask]
Subject: Re: [TN] Qualification of ROHS Comonents with tin/lead Solder

I'd be willing to place a small bet that despite all due diligence you
have already unwittingly built some product using components with a
tin/lead termination finish. Many suppliers flipped over to a lead-free
finish before the industry woke up to RoHS and often didn't care to give
us much notice of the fact. For most of us this didn't matter, but I'm
glad those that should care about this do!

Temperature should not be an issue as the parts without Sn/Pb coating
will now be designed to survive Pb-free temperatures. The only area
where you

might be very concerned would be BGAs.   

The NPL in the UK did a good study of the reliability of mixed alloy
solder joints, but concentrated mostly on varying levels of Pb
contamination in
Pb-
free alloys, so this won't help you and whisker detection per se was not
part of this project either.

Nigel

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