Building
Research
Seattle
Quake Lessons: Not Bad, But We Can Do Better
The
magnitude 6.8 Seattle earthquake of Feb. 28, 2001, officially
known as the Nisqually Earthquake for the shifting tectonic plate
beneath the region, caused more than $2 billion in damages, yet
killed no one and left most buildings intact. Most earthquake
experts would characterize these results as “not too bad,”
given that the quake’s source was deep underground and the
actual ground shaking was closer in strength to a lesser magnitude
event. Engineers in the National Institute of Standards and Technology’s
Building and Fire Research
Laboratory, would agree—with a caveat that “we can
still do better.”
In testimony recently submitted to Congress, BFRL
Structures Division Chief Shyam Sunder credited the relatively
“mild” Seattle results, in part, to the region’s
successful implementation of U.S. building codes and standards
specifically designed to reduce earthquake hazards. However, he
noted that current codes and standards focus primarily on saving
lives. Additional performance-based standards are needed, Sunder
said, so that critical facilities such as air traffic control
systems, hospitals, and fire and rescue services will be fully
operational or ready for immediate occupancy after major disasters.
Sunder’s testimony also stressed the importance of developing
new guidelines and standards for infrastructure lifelines such
as utility systems (such as electricity, water/sewage, and telecommunication).
Finally, he urged a community-based effort to selectively upgrade
or retrofit older construction that is most vulnerable as well
as a national effort to increase public awareness of the problem
and increase research and development that will develop new seismic
retrofit technologies.
Media
Contact:
John
Blair, (301) 975-4261
Semiconductors
Bringing
Polymer Patterns into Focus
Semiconductors
chips, with their 20-plus layers and Lilliputian linewidths,
represent the ultimate measurement and quality control challenge.
And now as manufacturers move to linewidths too small to be
seen with optical microscopes, the task is getting even harder.
With partial funding from the Defense Advanced Research Projects
Agency and in cooperation with the IBM T.J. Watson Research
Center, NIST researchers are using neutrons to improve the tools
available for precision measurements of polymer “resists”
used as “molds” for semiconductor circuit patterns.
Using a
technique called small angle neutron
scattering, the researchers aim a focused neutron beam through
a silicon wafer patterned with a complex, one micrometer (0.00004
inch, or equivalent to the diameter of a red blood cell) thick
polymer layer. The neutrons are scattered by the grating-like
polymer pattern but are unaffected by the relatively thick silicon
substrate.
The technique
allows accurate measurement of the shape, size and roughness
of polymer structures 100 to 300 nanometers (one-tenth to three-tenths
of a micrometer) wide. In addition, unlike current imaging techniques
such as electron or atomic force microscopy, neutron scattering
does not degrade the sample and becomes easier as the linewidths
shrink.
Physics
Tiny
Structures Are Focus for New NIST Facility
The
colorful, swirling image of cobalt
atoms arranged on a copper surface might look a bit like a
high-tech robin’s nest, but in reality, it may be a view
into the future of electronics.
The image of the 8 nanometers (300 billionths of an inch) square
structure represents one of the first creations of the new Nanoscale
Physics Facility at the National Institute of Standards and Technology.
NIST physicists designed and built the facility so that they could
manipulate and arrange atoms, one by one, into desired patterns
on a metallic surface.
“One of our motivations for doing this is to enable the U.S.
electronics industry to manufacture smaller, faster and more powerful
and versatile communications devices and computers,” says
project leader Joseph Stroscio.
In the not-too-distant future, as elec-tronic chip features shrink,
they will approach the boundary between classical and quantum
laws of physics. At the quantum level, single atoms and subatomic
particles, like electrons or photons, can behave in very unusual
ways unpredictable by the classical laws of physics that govern
larger objects.
In the Nanoscale Physics Facility, NIST physicists are exploring
the physical effects of quantum phenomena in a new generation
of nanoscale devices. By building tiny structures atom by atom,
NIST scientists are able to see how the cloud of electrons orbiting
each atom changes the fundamental physical properties of the assembled
structures.
Media
Contact:
Michael
Baum, (301) 975-2763
Materials
Putting
a 'Whisker-Free' Face on Electronic Parts
To
improve the solderability of electronic device components, manufacturers
often deposit a protective coating made with tin or tin-copper
alloy upon the parts. However, these coatings can result in the
formation of hair-like crystals known as “whiskers.”
Whiskers, which may extend for several millimeters, can divert
current away from its proper path and cause electrical shorts
or failures.
To prevent whisker formation in the past, manufacturers added
lead to the tin-based coating. Today’s lead-free electronics
finishing, however, precludes the use of this harmful substance.
Therefore, manufacturers are seeking new ways to coat electronic
components with tin or tin-copper alloy without the worry of whiskers.
To facilitate the development of these methods, materials researchers
at the National Institute of Standards and Technology have been
studying the basics of why and how whiskers form. So far, their
investigations have revealed seven types (shapes) of whiskers
that form with tin and tin-copper alloy coatings. They also have
found that contamination of the tin electroplating bath can contribute
to whisker formation.
Eventually, the NIST researchers hope to devise a test that manufacturers
can use to determine the likelihood of whisker formation during
the production process.
Media
Contact:
Pamela
Houghtaling, (301) 975-5745
'MEMS'
the Word for Newly Patented Device
Sometimes
it makes perfect sense to sweat the small stuff.
Researchers at the National Institute of Standards and Technology
recently received a microsystems patent for inventing a machine
that is too small to see with the naked eye, a device that scientists
and engineers call a MicroElectroMechanical
System, or MEMS. The patent covers a radically new way
to make a specific MEMS device known as an accelerometer. While
most Americans may not be familiar with the term “accelerometer,”
this tiny machine plays a critical safety role each time someone
gets behind the wheel of an automobile. Accelerometers detect
movement; in their most important job, they quickly sense the
sudden stop of a car during an accident and trigger inflation
of protective air bags.
The
NIST patent involves creating a standard way to make accelerometers
by combining new and existing technologies. Integrated circuit
technology widely used in the semiconductor industry is combined
with a microscopic heater (also invented in the NIST laboratories).
Acceleration affects the convection process of gases, creating
minuscule differences in temperature on both sides of the microheater.
Sensors built into the chip then detect the temperature differences.
Accelerometers can be employed in a variety of ways besides their
common use in air bags. For example, the Global Positioning System
network of satellites to determine precise position on Earth can
use accelerometers to track acceleration and direction of cars
or other vehicles.
Media
Contact:
Philip
Bulman, (301) 975-5661
Energy
On Top
of Old Smoky, the Hot Water's Courtesy of NIST
A
working vacation in the mountains was just what the doctor ordered
for showing the value of an experimental solar water heater system
developed by the National Institute of Standards and
Technology.
During the last year of a four-year trial at the Sugarlands Visitor
Center in Tennessee’s Great Smoky Mountains National Park,
the NIST system provided nearly 60 percent of the energy needed
by facility. Based on an expected life span of 25 years, the system
is projected to save $3,400 in energy costs. Using Environmental
Protection Agency calculations for a system of this size, emission
levels for the same period will range from an approximately 250-kilogram
(550-pound) reduction for nitrogen oxide to a reduction of more
than 100,000 kilograms (112 tons) for carbon dioxide.
Traditional solar thermal systems work by pumping water or an
antifreeze solution through solar collector panels. These systems
require the pipes and circulating pumps to transport the fluid
from the storage tank through the collectors. NIST’s system
operates without pipes, fluids that can leak or freeze, or moving
parts that can fail. The system uses panels of photovoltaic cells
to convert sunlight to electricity. A microprocessor continuously
monitors solar conditions and operates the system for optimum
performance efficiency. Energy
produced by the PV cells is transported by conventional house
wiring to hot water tanks.
Although the initial field tests are over, the NIST solar water
heater will continue to save energy and reduce pollution in the
Great Smoky Mountains.
Media
Contact:
John
Blair, (301) 975-4261
In
1962, scientists and technicians at NIST examined a small roll
of aluminum tape for clues to the probable cause of one of history's
worst air disasters. The tape, which contained the complete flight
record from the American Airlines Boeing 707 that crashed on take-off
into Jamaica Bay, was sent by the Civil Aeronautics Board to the
Engineering Metallurgy Section to be cleaned and smoothed before
being read.
The
International Astronomical Union gave official names to more than
500 craters on the moon's far side in August 1970. The honorees
include six NIST staffers from throughout the agency's history:
William W. Coblentz, John H. Dellinger, Hugh L. Dryden, Nicholas
E. Golovin, William F. Meggers and Paul W. Merrill.
In
a 1975 study for the Department of Housing and Urban Development,
a NIST team (chemists McClure Godette, Mildred Post and Paul Campbell)
spent 18 months surveying and evaluating commercially available
graffiti removers, as well as graffiti-resistant coatings. They
found no single product would remove all graffiti.
