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 <[log in to unmask]> 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]
>