Shorts

• Toothy Consequences for Swimmers
• For a Good Time, Call NIST
• Taking the Measure of Infant Formula
• Matchmaking for a Second Time Around

Co-op Corner : Air Speed Testing, Financing, Coatings Standards, Fires in Space

New Uses for Microjet Printing

A new method for microsoldering contact leads for integrated circuits soon may help improve productivity in the electronics industry and at the same time reduce generation of hazardous industrial wastes.

Developed by MicroFab Technologies Inc. of Plano, Texas, with co-funding from NIST's Advanced Technology Program, the new technology applies the basic approach used in ink jet printing to produce tiny solder drops as small as 40 micrometers across or about half the width of a human hair. The solder drops provide the electrically conducting leads needed to attach semiconductor "chips" to circuit boards. As microcircuits have continued to shrink in size to allow improved performance in smaller packages, soldering technology has lagged behind and consumed an increasing share of production costs.

The new technology promises to reduce waste and greatly increase flexibility in the production of circuit boards. Current microsoldering using photolithography and electroplating methods requires acid washes and substantially larger amounts of lead/tin solder material than the microjet method. Changing solder configurations for various products on the same production line or varying the size or depth of solder joints is also much easier with the programmable microjet method.

Research funded by the company's three-year ATP award produced a novel application of piezoelectric materials that allows the system to operate at the high temperatures required for liquefying solders. The piezoelectric materials are central to the system's ability to reliably pinch off uniform-sized solder balls from a liquid metal stream. (See photo above.) The award also allowed the company to design a method to prevent oxidation (rusting) of the liquid solder as the droplets are formed and laid down. The company's system creates a "locally inert" environment with nitrogen gas around the "printing" head as it rasters across a circuit board. This protects the solder drops while they solidify, making them much less reactive.

The ATP's vote of confidence in the technology's promise helped the small 18-person company to attract additional funding for product development from a consortium of six major electronics manufacturers. Prototype microjet soldering systems are now being evaluated by the consortium members, and process technologies are under development to incorporate the system into factory settings.The company also is working with NIST metallurgists to optimize the solder jetting process.

In a separate ATP project, MicroFab is developing a microjet dispensing system that would allow faster, less expensive analysis of DNA for medical research and diagnostics, paternity testing, and other applications.

Contact: David Wallace, (214) 578-8076.

Software Reduces Touch Probe Errors

A NIST computer model that compensates for a common source of error in coordinate measuring machines promises to increase greatly manufacturers' ability to check accurately the shape and dimensions of products.

The new "SuperFit" software corrects "probe-lobing" errors, a chronic and relatively large source of measurement uncertainty in 98 percent of the 30,000 CMMs in U.S. factories and laboratories. Such errors occur due to small variations in the performance of touch trigger probes depending on the angle that the probe approaches a part being measured.

These probes consist of a sensing element and ruby-tipped stylus. As shown in the graphic above, the probe triggers each time it touches the part (white lines show touch points). When measuring a "perfect" sphere, a typical probe stylus bends and the tip may move slightly when contacting the sphere at certain angles, causing measurement errors. Red to yellow areas show where the probe overestimated the sphere's true size. Blue areas show where it underestimated it.

The SuperFit program maps these errors for a particular CMM and then compensates for them in measuring actual parts. Probe-lobing errors typically are reduced from more than 6 micrometers to less than 1 micrometer. Several U.S. CMM manufacturers are now evaluating the software.

Contact: Tyler Estler, (301) 975-3483.

Molecule Magnets Go for the Gold

A new type of "molecular recognition" technology developed by IBC Advanced Technologies of American Fork, Utah, may help crack one of industry's most intractable problems -- how to remove an economically important or environmentally hazardous molecule from a whole lot of something else you don't want.

With co-funding from NIST's Advanced Technology Program, the company is turning an expertise in computer modeling of molecular structures and some Nobel-Prize-winning basic chemistry insights into an economically feasible, highly efficient chemical separation technology with broad applications. The IBC process uses customed-tailored organic molecules that selectively bind to target molecules in a "lock and key" fashion. (See graphic above.)

While the field of separation science has blossomed in academia, commercial successes have been harder to come by. Most current industrial separation processes require several passes of a mixture through a membrane or other filter and still only deliver low concentrations from dilute mixtures. IBC's process attaches the capturing molecules or "locks" on solid substrates, allowing for rapid flow through, and requires only one or two passes. For many systems, the process can produce greater than 99 percent concentrations in one substantially faster pass than current technology.

The key to the IBC process starts with several rounds of molecular designs to optimize geometry, size, composition, electrical charge, and other factors attractive to the target molecule. The company's most developed process involves extracting precious metals such as rhodium, palladium, and platinum from complex mixtures of primary and recycled materials. Future applications include separation of left- from right-handed mirror molecules and ultrapurification of semiconductor and drug making processes.

Contact: Steven Izatt, (801) 375-1600.

Moiré Method Reveals the Strain

The strain of daily cycles can be very fatiguing -- for metals as well as for people. When those metals are critical components connecting integrated circuits within multichip devices, fatigue can cause costly failures.

NIST researchers are working with several U.S. companies to develop ways to detect and model strain in chip to chip connections. One promising method is electron beam moiré,a new NIST technique that allows quantitative analysis of strain within connections on a microscopic scale. The moiré technique exploits the same principle that causes plaid suit coats to vibrate into wavy rainbow patterns on television -- the fact that interference is generated when an image scanner matches up with lines on the subject being imaged.

The colorized graphics above show a cross-sectional view of an interconnection. The red lines are a layer of copper sandwiched between insulating layers of polymer. When a device with this type of connection is turned on, heat generated by nearby chips causes different amounts of expansion within the metal and polymer layers. Repeated cycles of heating and cooling can cause the bucket-shaped connections to crack due to metal fatigue.

Electron beam moiré provides a way to pinpoint areas of high strain to help improve the design of these connections. A horizontal grating is applied to the specimen surface and is viewed with a scanning electron microscope. The left graphic shows the image made before the connection is heated. The right graphic shows the same connection after heating. The grating, which can be thought of as a set of horizontal furrows, produces a series of dark blue or black bands called "fringes" in the SEM images. For every 1 percent expansion of the polymer, five additional fringes appear. Areas with the shortest distance between fringes have expanded the most and consequently are under the most strain.

NIST researchers are using the moiré method to verify computer models that predict strain to help manufacturers ensure the reliability of interconnections without the necessity of testing new circuit designs to failure.

Contact: David Read, (303) 497-3853.

Mammography Gets New X-Ray Standards

Women getting mammography exams at licensed U.S. facilities soon will have greater assurance of receiving proper X-Ray exposures thanks to a new NIST radiation standard and instrument calibration facility. The new facility will allow the operators and inspectors of more than 10,000 U.S. mammography centers to trace the accuracy of their X-Ray exposure measurements to the primary X-Ray standards at NIST.

The calibration facility was established to help the U.S. Food and Drug Administration implement the Mammography Quality Standards Act of 1992. This law requires FDA to set up a certification and inspection program for U.S. mammography clinics. The instruments used by the FDA inspectors to measure X-Ray exposure from the clinical units will be calibrated using standards traceable to the new NIST reference X-Ray beams. Other expected users of the new service will be calibration laboratories and instrument manufacturers.

Contact: Michelle Johnson, (301) 975-2014.

Video Highlights Baldrige Winners

The winners of the 1995 Malcolm Baldrige National Quality Award -- Armstrong World Industries Building Products Operations and Corning Telecommunications Products Division -- are highlighted in two new videos. Available on one cassette, both videos feature interviews with top executives and other employees describing the quality improvement strategies that contributed to each company's success.

Armstrong's BPO manufactures acoustical ceilings. In 1994, BPO reduced operating costs by $40 million, set company and industry safety records, and paid its highest-ever gainsharing and incentive payouts.

Corning TPD manufactures optical fiber. Over its 12-year existence, TPD has increased sales, market share, and profitability; doubled its productivity, and decreased defects nearly tenfold.

VHS copies of "Quest for Excellence VIII" are available from ASQC for $20 plus $4 for shipping and handling. Order item T1030 by calling (800) 248-1946.

SHORTS

Toothy Consequences for Swimmers

Swimming may be the perfect exercise, but it's not too good for your teeth. Dental researchers at NIST recently had a handful of young patients with unusual brown spots on their teeth. The only thing these patients, some as young as seven, had in common was competitive swimming. Surveys of other competitive swimmers across the country found that discolored teeth were common. Of those surveyed 58 percent reported having the brown stains. Older patients sometimes develop deposits known as calculus consisting of plaque that has mineralized. The researchers dubbed the younger patients' stains "swimmer's calculus," but found that the deposits consisted primarily of proteins rather than minerals. In an article in the Journal of the American Dental Association, the researchers say that disinfectants in pool water seem to be changing the structure of saliva proteins that then change color and stick to the teeth. Happily, super swimmers should keep on swimming; a standard dental tool, an ultrasonic scaler, easily removes the stains. Contact: Clifton Carey, (301) 975-6107.

For a Good Time, Call NIST!

If you believe in making every second count NIST has a service for you.The Automated Computer Time Service can set the time on personal computers to NIST-7, one of the world's most accurate atomic clocks and the U.S. contributor to Coordinated Universal Time. The service is available by modem and through the Internet. NIST recently upgraded the modem service so that busy signals will be less frequent. The system handles more than 9,000 calls a day, with a peak capacity of 28,000 calls a day. NIST precise time is useful for scientists running time-dependent experiments, stock brokers, bankers, and many other professional time watchers. A number of software programs will call ACTS and set a computer's internal clock, including NIST Research Material 8101b, available for $45, (301) 975-6776. World Wide Web users can download free software by logging in as anonymous at url: ftp://time.nist.gov. Use your internet address as your password, change directories to /pub/daytime and read the file readme.daytime. The ACTS modem software is also available free at this site. Change directory to /pub/acts and read the file readme.acts. Contact: Judah Levine, (303) 497-3903.

Matchmaking for a Second Time Around

With the advent of mandatory recycling in many jurisdictions, the saying, "One man's garbage is another man's gold," is now truer than ever. A new electronic trading system aims to better match this "gold" with the right buyers. The Chicago Board of Trade Recyclables Exchange was established recently with help from NIST's Manufacturing Extension Partnership and others. The Clean Washington Center ( a division of the Washington State Department of Community Trade and Economic Development) played a key role in designing the system. Participants use an on-line electronic trading system to buy or sell recyclable materials such as recovered glass, plastic, and paper. The exchange will help to create a more stable marketplace for these materials by providing timely and accurate price information and by utilizing new standard definitions for grading the quality of recyclables. NIST's MEP works with the center through the Recycling Assistance Partnership to increase acceptance and use of recycled materials by small and medium-sized manufacturers. Contact: Elizabeth Burger, (206) 389-2530.

Peach tree leaves, whale blubber, and human DNA move over. NIST will soon be stocking its shelves with another unusual Standard Reference Material. In an effort to help food processors better meet requirements of the Nutrition Labeling and Education Act and the Infant Formula Act, Institute chemists have developed an infant formula SRM. The SRM will have assigned values for fat, carbohydrates, protein, and calories, as well as for a variety of minerals and vitamins. Seven industrial laboratories, two other federal laboratories, the Infant Formula Council, and the National Food Processors Association collaborated with NIST on the project. The new SRM will allow food processors to check independently the accuracy of their analytical methods. Currently, infant formula makers rely on regular "round robin" comparisons with other manufacturers for quality assurance. Contact: Katherine Sharpless, (301) 975-3121.

Co-op Corner

Air-Speed Testing -- A new consortium for improving measurement of low air speeds has been launched by NIST, six companies, and two Department of Defense laboratories. The Air-Speed Proficiency Testing Consortium will work to reduce interlaboratory differences in low air-speed measurements, to establish traceability to NIST air-speed standards, and to develop guidelines and test procedures for accurate measurements for air speeds between 0.3 and 15 meters per second. Improvements in low air-speed measurements are important for the control of ventilation in clean-room environments, meteorology, and air-borne pollutant control. Contact: J. Michael Hall, (301) 975-5947.

Financing -- NIST is funding four pilot projects to help smaller manufacturers better understand, identify, and access sources of financing and credit options. The pilots will be conducted at four of NIST's Manufacturing Extension Partnership affiliates: the Chicago Manufacturing Center, the Michigan Manufacturing Technology Center/Industrial Technology Institute, the Mid-America Manufacturing Technology Center, and the New York City Industrial Technology Assistance Corporation. Pilot start-up activities include establishing relationships with local, regional and national sources of capital and learning the processes needed to qualify client companies for financing. Contact: MEP, (301) 975-5020.

Coatings Standards -- Researchers from four different NIST laboratories to improve industry's ability to measure and predict the appearance of paints and coatings. The NIST team hopes that advances in optical technology (such as detectors, light scattering, and imaging) and computer modeling can be used to improve understanding of appearance parameters. Currently, at least 10 different metrics exist for measuring gloss alone. NIST will host a workshop on May 20, 1996, at its Gaithersburg, Md., headquarters to discuss a framework for the cooperative effort and to consider a provisional technical plan, research timetable, and the makeup of an advisory committee. Contact: Jonathan Martin, (301) 975-6707.

Fires in Space -- A project with NASA aboard the recent STS-75 space shuttle mission could help keep future crews aboard the international space station safe from fire. NIST and NASA researchers conducted experiments to study how flames behave in microgravity. The researchers hope to use data from the experiments to learn how to keep sparks from growing into a life-threatening fire aboard a spacecraft. Detailed information on the experiments can be found on NASA's World Wide Web site at http://zeta.lerc.nasa.gov/expr/ritsi.htm. Contact: Takashi Kashiwagi, (301) 975-6699.

About Technology at a Glance:

NIST is an agency of the U.S. Department of Commerce's Technology Administration. NIST promotes U.S. economic growth by working with industry to develop and apply technology, measurements, and standards. Technology at a Glance is produced by the Public and Business Affairs Division, A903 Administration Bldg., NIST, Gaithersburg, Md. 20899-0001. Any mention of commercial products is for information only; it does not imply recommendation or endorsement by NIST. Technology at a Glance Editor: Gail Porter, (301) 975-3392, email:gail.porter@nist.gov. For patent information, call (301) 975-3084.