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Subject:
From:
"Wenger, George M." <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Wenger, George M.
Date:
Fri, 21 Nov 2008 14:57:49 -0500
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text/plain (176 lines)
Touché! I agree whole heartedly.

Regards,

John,



Touché! I agree whole heartedly.



Regards,

George

George M. Wenger

Andrew Wireless Solutions

Senior Principal FMA / Reliability Engineer

40 Technology Drive, Warren, NJ 07059

(908) 546-4531 [Office]  (732) 309-8964 [Cell]

[log in to unmask]

 



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

From: John Burke [mailto:[log in to unmask]] 

Sent: Friday, November 21, 2008 2:13 PM

To: 'TechNet E-Mail Forum'; Wenger, George M.

Subject: RE: [TN] NTC black pad



On the other hand - to save key strokes - it only takes 10 keystrokes to

type "enig sucks"



John Burke

(408) 515 4992



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

From: TechNet [mailto:[log in to unmask]] On Behalf Of Wenger, George M.

Sent: Friday, November 21, 2008 10:48 AM

To: [log in to unmask]

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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