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May 2012

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Subject:
From:
Vladimir Igoshev <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, [log in to unmask]
Date:
Sat, 26 May 2012 16:15:27 -0400
Content-Type:
text/plain
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That is when you'd see those black streaks in a layer of electroless Ni. 

Regards,

Vladimir

SENTEC Testing Lab

On Fri, 25 May 2012 10:53:55 -0400, Robert Kondner 
<[log in to unmask]> wrote:
Dumb Question:
>
>  What Is "Hyper-corrosion"?
>
> Bob K. 
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman
> Sent: Friday, May 25, 2012 9:29 AM
> To: [log in to unmask]
> Subject: Re: [TN] Phosphorus content in Electroless Nickel
>
> Hi folks! Just to add a couple of details to Geoge's good details. The
> general rule of thumb is that the "low P" nickels have good solderability
> but can be prone to "black pad" issues and the "high P" nickels have good
> corrosion resistance but can be prone to solderability issues. The 
> "mid P" nickels are requested by many users/designers are a 
> compromise for dealing
> with those three attributes. And as George detailed, the P content isn't the
> root cause of black pad - hypercorrosion of the nickel plating prior to
> immersion gold deposition is the root cause and can be (but not always) more
> prevalent with some "low P" nickel plating formulations. One thing to keep
> in mind is that process control of a nickel plating chemistry is critical to
> achieving the plating properties you are expecting - any of these three
> types of nickel plating can be done incorrectly if due diligence is not
> followed. 
>
> Dave
>
>
>
> "Wenger, George M." <[log in to unmask]> Sent by: TechNet
> <[log in to unmask]>
> 05/24/2012 11:51 AM
> Please respond to
> TechNet E-Mail Forum <[log in to unmask]>; Please respond to
> "Wenger, George M."     <[log in to unmask]>
>
>
> To
> <[log in to unmask]>
> cc
>
> Subject
> Re: [TN] Phosphorus content in Electroless Nickel
>
>
>
>
>
>
> Frank,
>
> 2-5% is considered Low P
> 6-10% is considered Mid range P
> 11-14% is considered High P
>
> Many of the boards we examined years ago that were fabricated with 
> ENIG had Mid range P.  I'm not sure if I can find Zequm Mei's 
> original ENIG work but he first thought that P content was the cause 
> of BP failures since when he looked at fracture surface there was 
> always high P content. However,  you can't look just at a fracture 
> surface because there will always be a high P content because at the 
> interface you consume some Ni during the IAu processing and then more 
> again during soldering.  So you might have a Mid range P ENIG but at 
> the fractured surface it may look like High P.  Since then there has 
> been lots of information indicating that P content isn't the root 
> cause for BP.  I think I have the final HP paper on ENIG that Sequm 
> was one of he authors and can send it if I find it. 
>
>
> Regards,
> George
> George M. Wenger
> Senior Principal Reliability / FMA Engineer
> Andrew Corporation - Wireless Network Solutions
> 40 Technology Drive, Warren, NJ 07059
> (908) 546-4531 Office (732) 309-8964 Mobile
> E-mail: [log in to unmask]
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Frank Kimmey
> Sent: Thursday, May 24, 2012 12:22 PM
> To: [log in to unmask]
> Subject: [TN] Phosphorus content in Electroless Nickel
>
> I know this may be difficult to commit to but what would you consider 
> an acceptable percentage of Phosphorus in Electroless Nickel. 
> I am being asked to accept 7-10% and am not sure if this may lead 
> towards Solderability issues. 
> Feedback from Chemists, Board Fabricators or anyone with an opinion 
> is appreciated. 
> Thanks to a great group of minds,
> FNK
>
> Frank N Kimmey CID+
> Manager - PCB Design
> Powerwave Technologies Inc. 
> Mobile - 916-670-0645
>
>
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