I'll try to get some pictures today. It is a very strange behavior. We are seeing everything in spec from the board vendors (thickness/P content) and we are seeing everything in spec in the wave process, flux, alloy, profile. But, we still get these dewets. We've seen it on selective and standard wave from at least two different board shops using two different chemistries. It has been suggested that decreasing dwell time, or using more agressive flux may help, but I hesitate to make major changes in an established process without knowing what the root cause is. We're spending a lot of bucks on lab work, so I was hoping to collaborate with anyone else that is having this issue. I've heard rumors that an oem on the east coast had the same issues?
Apparently the plating committee and the enig suppliers have been looking at this and it is described as a bit of an epidemic and they are calling it a new phenomenon that could rival black pad. I would just like to find out more.
Thanks.
--- On Fri, 11/28/08, David D. Hillman <[log in to unmask]> wrote:
From: David D. Hillman <[log in to unmask]>
Subject: Re: [TN] nickel erosion
To: [log in to unmask]
Received: Friday, November 28, 2008, 10:39 AM
Hi Henry! Wow, nickel plating is commonly used as a barrier layer in a
number of electronics applications so having an erosion issue would be
somewhat odd. I would expect that a lead-free soldering process would
remove more nickel (either thru erosion or dissolution) in comparison to a
tin/lead soldering process due to the increased process temperatures but
what you are describing (large?) sounds strange. Have you compared the
nickel thickness pre and post soldering process? Do you have any
microsection photos Steve could post so we could get a look at the
situation? I have run a significant number of ENIG pwbs thru both
lead-free wave and reflow processes but have not seen the condition you
describe. Are you on a mini-wave, selective solder or typical wave solder
system?
Dave Hillman
Rockwell Collins
[log in to unmask]
henry rekers <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
11/26/2008 06:17 PM
Please respond to
[log in to unmask]
To
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cc
Subject
[TN] nickel erosion
Any technetters out there experiencing this mysterious nickel erosion
process with enig boards on their leadfree waves? Apparently there is a
committee set up already. I would like to share experiences if anyone is
willing to come forward.
Essentially, the defect shows up as a dewet on the annular ring of the TH
devices. On cross section, there is large amounts of nickel eroded away
and the surface is non-wettable. No corrosion is evident, so it's NOT
black pad.
Anybody?
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