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Subject:
From:
kwood716 <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, kwood716 <[log in to unmask]>
Date:
Thu, 20 Nov 2008 20:45:02 -0500
Content-Type:
text/plain
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text/plain (1595 lines)
ok experts...time for a definitive posting.

Black Pad is ? (any photos?)

Caused by:
1) ?
2) ?
Fixed By:
1) ?
2) ?

A little while back a new customer asked me what RoHS finish I prefer. I told him that I liked ENIG for a few reasons
over silver or tin. He quickly asked me "Aren't you worried about black pad?" Being that I recently had a tetanus shot and take a daily multi-vitamin
I thought I was in pretty good shape so I said that I was not worried about it. That being said...I too would like to know more about this issue since I've used gold finishes for many years now and have never had an issues with it. I've seen soldering issues due to the type of solder used or thickness of gold but nothing like this issue.

_____________________________________
Kenneth J. Wood
President
Saturn PCB Design, Inc.              [log in to unmask]
2737 Bishop Lane                       Phone:(407) 340-2668
Deltona, Fl 32725                        Fax: (386) 789-2765
www.saturnpcb.com











-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier /*
Sent: Thursday, November 20, 2008 6:18 PM
To: [log in to unmask]
Subject: Re: [TN] black pad

 Agreed, the prescription for the fix will be different.

Werner


 


 

-----Original Message-----
From: Igoshev, Vladimir <[log in to unmask]>
To: [log in to unmask]
Sent: Thu, 20 Nov 2008 5:52 pm
Subject: Re: [TN] black pad










Hi Werner,

I completely agree on what we disagree on :-)

I think that the same appearnce can (and is in that particuar case) be caused by 
completely different phenomena, therefore the recepie to fix/avoid it will be 
different.

Regards,

Vladimir

----- Original Message -----
From: TechNet <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Sent: Thu Nov 20 17:28:06 2008
Subject: Re: [TN] black pad


 Hi Vladimir,
That is where we disagree--the definition of 'Black Pad.'
I define it as the phenomenon root cause regardless of what caused it--that is 
not to say that who caused it is unimportant.

Werner


 


 

-----Original Message-----
From: Igoshev, Vladimir <[log in to unmask]>
To: [log in to unmask]
Sent: Thu, 20 Nov 2008 5:20 pm
Subject: RE: [TN] black pad





























Hi Werner,



 



I should have referred to your exact phrase,
so you wouldn’t have to correct me J



As far as the definition of BP is
concerned, then I still prefer to define it as a manufacturing defect, which
has nothing to do with the assembly process.



The presence of thicker P-enriched layer
isn’t a good thing but in true cases of BP it’s normal
(thickn
ess-wise) but the joints has almost zero strength.





Regards,



 



Vladimir



 
















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

Sent: Thursday, November 20, 2008
5:06 PM

To: [log in to unmask]; Igoshev,
Vladimir

Subject: Re: [TN] black pad






 






Hi Vladimir,

I did not say 'excessive temperature'-- I said 'the more you expose
an ENIG layer to soldering temperatures'--that means multiple or lengthy
exposures.

If you define 'Black Pad' as the presence of P at the Ni/NiSn-IMC interlayer to
a degree significantly weakening that interface, then you can arrive at that
condition by
 multiple paths.

One is faulty manufacturing, the other is excessive Ni-dissolution--of course,
these can work in combination.



Werner









 









 






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

From: Igoshev, Vladimir <[log in to unmask]>

To: [log in to unmask]

Sent: Thu, 20 Nov 2008 4:45 pm

Subject: Re: [TN] black pad




Well, with all due respect I would have to disagree with you Werner (not





for the first time :-)). I wouldn't associate Black Pad with excessive





soldering temperature. It's rather a board manufacturing related issue.











Regards,











Vladimir











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





From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier /*





Sent: Thursday, November 20, 2008 4:38 PM

0A


To: [log in to unmask]





Subject: Re: [TN] black pad

















 The more you expose an ENIG layer to soldering temperatures, the more





Ni dissolves leaving more P at the layer between the Ni and the





NiSn-IMC. The more? P the weaker this interface, leading to 'Black Pad'











Werner

















 

















 











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





From: henry rekers <[log in to unmask]>





To: [log in to unmask]





Sent: Thu, 20 Nov 2008 3:41 pm





Subject: Re: [TN] black pad


=0
A





























































Can you give me any examples of black pad being caused by anything other





than a 





"bad board"? ie.? Is there anything in processing "perfect board" that





would 





cause a de-wet condition that indicates black pad??? I guess where I'm





going is, 





can this be anything other than a supplier issue?











--- On Thu, 11/20/08, Werner Engelmaier /* <[log in to unmask]> wrote:











From: Werner Engelmaier /* <[log in to unmask]>





Subject: Re: [TN] black pad





To: [log in to unmask]





Received: Thursday, November 20, 2008, 1:26 PM











 Hi 'rekers,'





You canno
t broad-brush like this. Some FAB houses do quite well, others





not.





ENIG, from various sources and at various conditions, has shown nickel





corrosion or high phosphide concentrations. The underlying reasons for





these are





different, actually diametrically opposed. Some are the fault of the FAB





house





others not.











Werner

















 

















 











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





From: henry rekers <[log in to unmask]>





To: [log in to unmask]





Sent: Thu, 20 Nov 2008 12:45 pm


=0
A

Subject: [TN] black pad

































































Anybody out there experiencing mass dewetting issues from North American





board 





shops?





?





From what I understand primary causes for dewetting (assuming the





reflow/wave 





profile is bang on) is all on the board, ie nickel corrosion,





degeneration of 





the nickel, or outgassing of the nickel/copper.? (I'm talking enig





here.)





?





Anybody?

















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