With the increasing recognition of the Nihon Superior SN100C lead-free solder
technology (Sn-0.7Cu+Ni+Ge) there has been a proliferation of attempts to
come up with alloys that take advantage of the knowhow without infringing the
Nihon Superior patent.

The SnAgCuNi you mention is probably another of those attempts.   The problem
for those trying to avoid the patent is that everything that has been added
to the basic SN100C formulation so far has the effect of diminishing the
beneficial effect of the Ni addition without bringing any new benefit to compensate
for the consequent loss of functionality   That is certainly the case for Ag
even at levels of only 0.1%.   P which is often added to these lead-free
solders as an antioxidant also has a negative effect.

These attempts to avoid the Nihon Superior patent reveal a lack of
understanding of the key benefit of the Ni addition.    By inducing true eutectic
behaviour the Ni addition turns Sn-0.7Cu into an alloy that matches the behaviour of
the greatly missed "63/37" tin-lead solder more closely than any other
currently available lead-free solder.  All the other additions to the alloy push the
behaviour away from that well recognised ideal.

Keith Sweatman
Nihon Superior Co., Ltd.


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