Paladium Leads Revisted

Recently there was a thread on soldering paladium leads on ICs. A gent from TI suggested an article he had written. Various folks suggested making sure the reflow profile peaked above 215C. My question is: How does one recognize paladium leads so that the profile can be set properly? Dave F

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| My question is: How does one recognize paladium leads so that the profile can be set properly? | Dave F Hi Dave, It's kinda' subjective, but what I think it looks like is almost like having a nickel appearance to it, it's smoother and not as porous looking as tin lead plating looks...if ya' want to tell for sure, grab just about any Texas Insturments part and compare it with another part that you know is tin lead. As far as I know, every T.I. part is palladium plated. -Steve Gregory-

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| | My question is: How does one recognize paladium leads so that the profile can be set properly? | | Dave F | Hi Dave, | It's kinda' subjective, but what I think it looks like is almost like having a nickel appearance to it, it's smoother and not as porous looking as tin lead plating looks...if ya' want to tell for sure, grab just about any Texas Insturments part and compare it with another part that you know is tin lead. As far as I know, every T.I. part is palladium plated. | -Steve Gregory- Steve: I agree. We just assume all TI parts are Pd. We thinking about assuming all partts are Pd and re-setting our profiles. Dave F

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| Recently there was a thread on soldering paladium leads on ICs. A gent from TI suggested an article he had written. Various folks suggested making sure the reflow profile peaked above 215C. | My question is: How does one recognize paladium leads so that the profile can be set properly? | Dave F

I think I started the most recent discussion on the Paladium lead issue. My input from TI and others is that invariably you will see bare copper at the ends of the leads where they were trimmed. For all my TI parts and a handfull of others from various sources this holds true. At last I contribute more than questions. Gary

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Just wanted to add a few comments on the discussion of how to identify palladium parts. Generally, there is no "clear-cut" way to identify Pd versus Sn/Pb. It mainly comes with experience. Any part that is is plated prior to being trim/formed will show exposed Cu at the dam bar and lead tip, not just Pd parts. I have seen solder plated parts in the field from a number of vendors which showed exposed Cu. Exposed Cu is not simply limited to Pd parts. Yes, you can assume that any TI logic or linear IC that you have is Pd finish. These 2 product groups are virtually 100% converted. Our Application Specific Product group is converting now but is not yet complete. Pd does "look" different than Sn/Pb but you have to look at a large number of units to be able to recognize the difference. As for the statement about changing reflow profiles, our (TI) goal when we introduced Pd finish was that our customers would have to make no changes to their assembly processes. We like to think of it as a "drop-in replacement" to Sn/Pb. Yes, a small number of our customers disagree with this term but with over 20 Billion parts in the field with no major disruption to our customer base we think this is a fair statement. In general, if you are running below 210C you may see problems. However, since most paste manufacturers give recommended profiles for their pastes with peak temperatures in the range of 210-225C, this would be a problem for the paste anyway. As a reminder if you care to see TI published technical papers you can go to "http://www.ti.com/sc/docs/asl/palladm/index.htm" Also, look for our latest article in an upcoming issue of Circuits Assembly magazine.

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