Saravanan,

   A picture is worth one thousand words.   How did you derives at the 140% for nail heading?

Victor,

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ramakrishnan Saravanan
Sent: Friday, August 01, 2014 11:00 AM
To: [log in to unmask]
Subject: [TN] PAD LIFT

Dear all,

We are procuring high reliability PCBs from a contract pcb fabricator. The procurement specifications is MIL-PRF-55110G.

In recent batches of PCB, we are finding knee of the PTH is slightly raised than the rest of the PAD. Nail heading is also present when micro sectioning is done. Nail heading is around 140 %,

When we are touching the PAD on the edge with the soldering Ion (290 deg C, < 5 Seconds) ,the PAD is getting lifted from the base material.

But when we do the rework simulation , lift is not observed. Similarly solder dip test does not lift the PAD. Because of the pad lifting , we are unable to use the PCBs.

Why the pad lifting is observed only when we touch the edge of the PAD with soldering iron ?. The PCB is lead free compatible & having tested peel strength of 1.05 N/mm. Kindly help us. regards,

Saravanan RAMAKRISHNAN

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