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Subject:
From:
David Hillman <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, David Hillman <[log in to unmask]>
Date:
Thu, 10 Nov 2016 15:05:18 -0600
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Hi Blair - not necessarily, it may just mean the impact of the IMC on the
overall solder joint integrity may be different. The majority of the time,
for most product applications, that "IMC difference" doesn't impact my
solder joint quality/integrity such that I impact product field quality.
There is are conversations that pop up every once in awhile on how which to
an ENIG board made the solder joint more prone to impact damage. There are
lots of variables in the whole impact damage discussion but one of them is
that tin/nickel IMC is not quite as good as tin/copper IMC. Again, that
difference is small and I am probably whacking the solder joint with a
force that makes the IMC strength is a moot point. But, I believe knowledge
is a key part of having a good process.

The real question, which we all ultimately ask, is the solder joint created
good enough for its application and is the HASL joint superior to the ENIG
joint?

Dave

On Thu, Nov 10, 2016 at 2:48 PM, Blair Hogg <[log in to unmask]> wrote:

> Interesting, Dave. That seems to indicate that a profile that works fine
> for a HASL board may not work as well for a ENIG board as the solder
> doesn't have sufficient time above liquidus to create a bond with the
> nickel. Is my understanding correct?
>
> Blair
>
> On Thu, 10 Nov 2016 13:48:51 -0600, David Hillman <david.hillman@
> ROCKWELLCOLLINS.COM> wrote:
>
> >Hi folks - lots of good comments, just one more to add: copper diffuses
> >faster than nickel so some folks increase their reflow temperatures 5-10C
> >and/or slow down the belt speed 3-6 inches per minute. It isn't necessary
> >to do this but it does have some good metallurgical basis. Werner
> >Englemaier used to advocate doing this when a board finish involved nickel
> >(Werner and I discussed this at length, very fun conversations). I set my
> >reflow profile based on the board thermal characteristics and the solder
> >paste material but being aware of the plating metallurgy impacts (such as
> >the gold embrittlement Wayne detailed) is always a good idea.
> >
> >Dave Hillman
> >Rockwell Collins
> >[log in to unmask]
> >
>

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