I thought Hyper-corrosion was what happened to a 1970's era Chevy Vega. The era of the biodegradable car! regards, - Graham -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman Sent: Friday, May 25, 2012 1:41 PM To: [log in to unmask] Subject: Re: [TN] Phosphorus content in Electroless Nickel Hi Bob - excessive chemical attack of the nickel plating surface by micro etch and pre-gold deposition processing. Evidence of the hypercorrosioin attack is attack at the nickel grain boundaries in the plating. Dave "Robert Kondner" <[log in to unmask]> 05/25/2012 09:53 AM Please respond to <[log in to unmask]> To "'TechNet E-Mail Forum'" <[log in to unmask]>, <[log in to unmask]> cc Subject RE: [TN] Phosphorus content in Electroless Nickel 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. 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