Very good point. Your comments are right on the mark. We tend to use
simpler to understand terms that are not actually accurate.
Best Regards,
Tim Jensen
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of Vladimir Igoshev
Sent: Friday, January 19, 2007 10:33 AM
To: [log in to unmask]
Subject: Re: [LF] SAC+, SACN and Low-Ag SAC Solder Ball Alloy
Hi Tim,
I don't think any of the Pb-free alloys should be "called" brittle. They
are all rather ductile (in many cases less ductile than Pb-Sn, but still
ductile).
The fact that solder joints made of Pb-free alloy can fail in a brittle
manner does not mean the alloys are brittle. Those failures occur at the
interfaces, but not in the bulk of solder. Therefore, the solders are
still ductile, but the interface becomes 'brittle", so to say.
Regards,
Vladimir
AMD
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of Tim Jensen
Sent: Friday, January 19, 2007 9:40 AM
To: [log in to unmask]
Subject: Re: [LF] SAC+, SACN and Low-Ag SAC Solder Ball Alloy
I believe that there is some confusion regarding the initial question.
There are absolutely new alloys being developed to enhance the
mechanical
reliability of SAC alloys and are of primary interest to BGA/CSP
manufacturers for the spheres on their components. Although there are
alloys being designed to compete with SN100C, I don't think those are
the
alloys that the initial emailer was talking about.
The industry has recognized that the standard SAC305, 405, and 387 are
much
more rigid and brittle than good ol' Sn/Pb and this has generally had
the
most negative impact on assembled BGA/CSP's (esp. in devices prone to
mechanical shock). In an attempt to improve this, component suppliers
are
trending toward SAC105 spheres as the low Ag content does reduce the
brittleness of the alloy. Although SAC105 is better than SAC305, they
both
appear to fall well short of Sn/Pb. Companies are now investigating
alternative alloys that can narrow the gap that now exists between
SAC105
and Sn/Pb.
Based on the limited work that I have seen, it does appear that some of
these alternative alloys appear promising (although there is a need for
much
more data). I don't think these alloys are being designed as a
replacement
for current pb-free solder pastes, wires, and bar solder alloys.
Best Regards,
Tim Jensen
Product Manager
Advanced Assembly Materials
Indium Corporation
+1-315-853-4900 x7568
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of [log in to unmask]
Sent: Friday, January 19, 2007 12:52 AM
To: [log in to unmask]
Subject: Re: [LF] SAC+, SACN and Low-Ag SAC Solder Ball Alloy
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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***This email, its content and any files transmitted with it are intended solely for the addressee(s) and may be legally privileged and/or confidential. If you are not the intended recipient please delete and contact the sender by return and delete the material from any computer. Any review, retransmission, dissemination or other use of, or taking of any action in reliance upon, this information by persons or entities other than the intended recipient is prohibited.
Messages sent via this medium may be subject to delays, non-delivery and unauthorized alteration. This email has been prepared using information believed by the author to be reliable and accurate, but Indium Corporation makes no warranty as to accuracy or completeness. In particular, Indium Corporation does not accept responsibility for changes made to this email after it was sent. Any opinions or recommendations expressed herein are solely those of the author. They may be subject to change without notice.***
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