That was a very good explanation. With the advances in process controllers and software I would think or expect that the ENIG process is less risky now than some 10 years ago when I used to hear about these issues. I know from a manufacturing poit I'll take ENIG over OSP any day. 

-------------- Original message -------------- 
From: Inge <[log in to unmask]> 

> Can we call it 'Black Pudding' instead, as it is a mess of obscure 
> ingredients? 
> Inge 
> 
> 
> ----- Original Message ----- 
> From: "Wenger, George M." 
> To: 
> Sent: Friday, November 21, 2008 10:47 AM 
> Subject: Re: [TN] black pad 
> 
> 
> That is how a lot of the confusion around (I hate t 
> 
> Peter, 
> 
> That is how a lot of the confusion around (I hate the name but I need to 
> use it here) Black Pad started. Creep fatigue cracking, brittle 
> fracture, etc. are recognized failure modes or mechanisms, "Black Pad"," 
> Black Line Nickel", etc. are not names of recognized failure modes. 
> They are names of what people see when they look at a failure. They 
> are short cute names that people like to repeat but they don't help to 
> describe what the failure is or what caused it. All I know about "Black 
> Pad" is that it happens with ENIG, it's a low level problem that follows 
> Murphy's Law (i.e., it happens when you least expect it and usually and 
> an inappropriate time), it might be caused by a high P content at the 
> interface, it might be caused by "weak" electroless nickel, it might be 
> caused by cavitation and attack at grain boundaries, it might be cause 
> by too much gold plating attaching the under lying nickel, it might be 
> caused by board shops not controlling the ENIG process properly, etc. 
> There are just too many "might". The data that has been generated by 
> many over the last couple of years certainly shows that control of the 
> plating chemistry is a key to reducing the occurrences of "Black Pad" 
> failures and the number of occurrences has certainly decreased but the 
> failures certainly have not been eliminated. Many of the ENIG failures 
> I've seen over the years are fractures at an interface. Vladimir would 
> certainly not agree with calling all ENIG failures "Black Pad" and I'd 
> agree with him. I'd much rather refer to the ENIG failures as "ENIG 
> Interface Failures" rather than "Black Pad" but that will never happen 
> because "Black Pad" is a cute and short 8 letter name that can even be 
> shorted to two ("BP"). It takes 23 key strokes to type "ENIG Interface 
> failures". 
> 
> 
> Sorry for the long answer but it's Friday and I had an exhausting week. 
> 
> Regards, 
> George 
> George M. Wenger 
> Andrew Wireless Solutions 
> Senior Principle FMA/Reliability Engineer 
> 40 Technology Drive, Warren, NJ 07059 
> (908) 546-4531 (Office) (732) 309-8964 (cell) 
> [log in to unmask] 
> -----Original Message----- 
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Pete Houwen 
> Sent: Friday, November 21, 2008 12:54 PM 
> To: [log in to unmask] 
> Subject: Re: [TN] black pad 
> 
> not to step in a place I don't beloing, between werner and Vladimir, but 
> how 
> about "dark line defect" instead of "black pad"? 
> 
> Similar phenomenon for a different reason. 
> 
> We went through this a while ago, wondering why suddenly boards from a 
> very 
> good ENiG supplier were looking like black pad, all that P on top of the 
> pad. 
> Changing reflow profiles to reduce TAL and max temp, reducing rework 
> cycles 
> made it all go away. All that extra time at temperature just continued 
> the 
> Ni/Sn reaction, leaving P behind. Quantities of Ni in the Sn tipped us 
> off that 
> we weren't starting out with black pad, but we were ending up with it. 
> 
> I do get why people don't like ENiG, but we've done very well with it by 
> making 
> sure we use good suppliers. 
> 
> Pete 
> 
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