Werner,



I believe I saw a similar failure on a board from the same board shop and it WAS NOT BP. :-)



Regards,



Vladimir



----- Original Message -----

From: TechNet <[log in to unmask]>

To: [log in to unmask] <[log in to unmask]>

Sent: Fri Oct 10 09:34:54 2008

Subject: Re: [TN] PCB pad non-wetting issues





 

-----------------------------------------------------

Hi Paymon,

The root cause is ENIG 'Black Pad.'

In order to protect the electroless Ni from the immersion Au plating bath, P is codeposited. 

As more and more Ni is dissolved during numerous soldering processes more P is left behind 

weakening the interfacial structure--the more P, te weaker the interface.



Werner







 





 



-----Original Message-----

From: Paymon Sani <[log in to unmask]>

To: [log in to unmask]

Sent: Thu, 9 Oct 2008 9:57 am

Subject: [TN] PCB pad non-wetting issues





















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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