Hello All,

 

We are experiencing a pad non-wetting issue for the though-hole
component pads ONLY! The PCB goes through few heat cycles with top and
bottom side assembly during at SMT process and then through-hole
assembly at wave process. The problem is found at Wave process. The Pb
solder does not wet to the through-hole component pads on the solder
side only! An SEM/EDS evaluation revealed high concentration of P in the
Nickel and Nickel/Tin intermetalic layer of 11% to 21%. I would like to
ask anyone if they have experienced a similar defect in the past. What
is the Root Cause?

 

Thank you in advance,

Paymon


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