Many thanks Harvey. I would very much interest to know the detail of the presentation. The nano particles are utilized in printed electronics, in various elements and organic conductive media to improve conductivity and flexibility. Normally, printed electronics are processed in low temperature with large surface contact area (roll to roll printing). Therefore, it can be flexible and thin, the resistance short coming of the nano-particles due its large surface/interface characteristics (sometimes, it is hopping rather than normal conduction mechanism) are compensated by large conduction contact surfaces and thin joints.
Sintering/fusing of the nano-particle can be done at lower temperature due to highly active surface energy, however, unless performed under pressure, you might get un-controlled re-crystallization and growth of the grain, resulted preferential growth of certain orientation of grain and leave some voids behind (low angle co-incidence grain boundary, as well as twining, are stable boundary, but not high angle gain boundary)- you might get more conductivity loss in high frequency and resistance increase. Of course, all the oxidation must be taking care of (copper is very readily oxidized, even with OSP coated, with that much surface area (nano particle). Acid media is more less like a flux can take care some of surface oxidation, but you still need to control the coalescence and growth (not all orientation are grow at same rate...).
The existing solder interconnect is heading towards smaller, more compact (solid) joints, for example, flip chip, or TSV for high speed, high density interconnect (in line with the high density IC with node of <20 nm). The solder interconnect joints more in the 3D stack, rather than 2D in printed electronics. High surface/interface might be good for some application, such as low frequency, low temperature application, I am a bit curious how it can be apply to the high frequency, high I/O, short and dense interconnect at lower voltage, and high device temperature (current processor dissipated 40-100W in some cases). Looking forward to see the presentation (I would really appreciated if you can share with us). I haven't been in the field for long time, Looking forward to update my knowledge. Thanks. My 2 cents.
Best regards,
Joyce Koo
Researcher
Materials Interconnect Lab
Office: (519) 888-7465 79945
BlackBerry: (226) 220-4760
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of harvey
Sent: Saturday, April 06, 2013 9:16 PM
To: [log in to unmask]
Subject: [TN] copper nanosolder--fyi
Biltmore Santa Clara for dinner (or non-dinner)
June 12, 2013.
Dr. Zinn's bio and abstract are at the end.
Lockheed's nano-copper solder is an answer to the lead-free solder
fiasco.
Remember "the non-solution to the non-problem",
that
is, until we get rid of most solder altogether, most solder paste,
anyhow.
Speaker:
Alfred Zinn, Lockheed Martin Space
System Company ATC, Senior Scientist
Abstract:
NanoCopper Materials Platform for Electronic
Packaging and Printed Electronics with 200 °C Processing
Temperature
The Advanced Technology Center of the Lockheed Martin
Corporation has developed a nanocopper-based material that can
be fused to bulk copper around 200 °C taking advantage of the
rapidly decreasing fusion temperature with decreasing particle
size at the nanoscale. The nanocopper material has the
potential to replace tin-based solder to eliminate whisker
growth and mechanical reliability concerns encountered with
current lead-free solder. Fully optimized, the fused copper is
expected to exhibit 10-15x electrical and thermal conductivity
improvements over tin-based materials currently in use. The
materials platform is enabled by our scalable Cu nanoparticle
fabrication process employing a low cost solution-phase
chemical reduction approach. A proprietary mixture of
surfactants controls particle size and size distribution as
well as stabilizing the particles preventing particle growth
and oxidation, which would otherwise degrade its activity. We
have demonstrated assembly of fully functional LED test boards
using a paste formulated with nanocopper that exhibits a
consistency very similar to standard tin-based solder paste.
To date, we have demonstrated 26-pin through-hole connector
assembly and a variety of surface mount components. We
demonstrated feasibility of drop-in solder replacement using
standard stencil and pick & place packaging equipment as
well as demonstrated feasibility of using the material for
printed electronics applications.
Dr. Zinn
received his Doctor of Science degree in Chemistry in 1990
from the Philipps University, Marburg, Germany. Following
completion of his graduate studies, Dr. Zinn spent five years
at UCLA as a lecturer and conducting postdoctoral research on
low-temperature CVD for interconnect, diffusion, and migration
barrier deposition, as well as magnetic nanomaterials design
and synthesis. In 2004, he joined Lockheed Martin Space
Systems Company Advanced technology Center in Palo Alto, CA
developing high-temperature materials systems, nanostructured
functional materials (electrical, thermal, thermoelectric),
modeling quantum/superlattice structures and devices, high
performance energy conversion devices (solar, high & low
quality heat conversion). He holds seven patents in materials,
structures and processing, two THz technology patents, with
ten additional patents pending (multiple international
filings) as well as four trade secrets. He has authored or
co-authored over 20 archival journal publications, including
book chapters in "The Chemistry of Metal CVD" as well as the
"Encyclopedia of Inorganic
Chemistry.
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