Eric

Interesting, but I'm nor all that keen. Some bronzes, which are
essentially high in Cu/Sn intermetallics, are devils to solder.

Brian

Eric Dawson wrote:
>
> Hi All,
>
> I notice that a few new references have been made to the above subject and
> thought I would share some of my early work with you.
>
> In my first post as a graduate, I researched the causes of dewetting on
> circuit boards. I came across a solution, the make-up of which I have since
> lost, which dissolved the tin lead alloy but left the two intermetallic
> layers.
>
> I produced a number of one inch square coupons which I soldered using 63/37
> alloy, RMA flux and a Tri Moore Rotary Dip Tester.
>
> These were divided into three categories:
>
> 1       Control
> 2       Remove tin lead and re test in the Rotary Dip.
> 3       Remove tin lead, Several hours steam ageing and re test.
>
> Microsections showed that I had taken off the alloy successfully and left
> the IMC.s.
>
> All of the re tested coupons soldered successfully, including the steam aged
> ones.
>
> This was some years ago so I cannot remember the etchant nor the hours and
> conditions in the steam ageing equipment. I do remember that the IMC
> soldered very well so I am always dubious when somebody blames the
> intermetallic for poor soldering.
>
> I seem to be alone in my faith that the IMC solders but this was the result
> of my very own work and I stand by it.
>
> Regards
> Eric Dawson, Defender of the IMC.
>
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