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Positional Non-adhesion of Sn/Pb Plating Material



I'm an engineer for a semiconductor firm here in the Philippines. For the past 6 months we have been encountering intermittent positional (only on one lead) non-adhesion of Sn-Pb plating material on our 8L & 16L SOIC. There is no flashes/plastic material on lead surface. We have already performed elemental analysis and we could not detect any impurities that would cause such failure.

Thank you in advance for those who could help me on this.


Sharie Equipaje
- Manila, Philippines


Hey Sharie,

I'm not sure what the lead is made from but try to over etch or in some way color the metal (maybe sulfide?). If the one lead doesn't look the same as the others something is on it keeping the solutions at bay. Or, something dipolar may be happening with current in the cleaning / plating cycle.

My money is on the first idea. Let me know what happens.


Fred Mueller, CEF
Wendt Dunnington - Royersford, Pennsylvania

Hi, Had sent a letter last month regarding positional non-adhesion of Sn/Pb plating on base material (copper) of our IC packages. We were able to trace the cause of this positional inc. plating to the clips holding the units in a strip-to-strip plating line. As the thickness of the clip decreases its performance to remove dirts/stains on the base material to be plated also diminishes. Could someone please help me understand the relationship between clip thickness to its performance in supplying the current density needed to remove dirts/stains and subsequently plating the base material. Thanks in advance!

Sharie Equipaje
- Philippines


Hello Sharie,

Your belt grip is important (not only to hold your units) in your electro clean and cathodic activation. Thinner belt means poor contact and the set/optimum current for these processes flactuates. The belt is your medium. Apply ohm's law. And lastly, you belt needs to be changed.
Hope this helps.


Neon Green
- Philippines

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