NEW DEVELOPMENTS

New way to test computer components for invisible defects

Bruce C. Kim, an assistant professor of electrical engineering and computer sciences at Tufts University, has come up with a new, inexpensive way to test the latest generation of computer components for invisible defects.

The method he developed may help the new multichip modules (MCM's) find their way into a host of consumer products, including cellular telephones and tiny one-pound laptops that fit in the palm of a hand.

An MCM -- typically the size of a credit card -- holds the computer's central processing unit and several memory chips. Eventually, manufacturers hope to integrate all the inner workings of the computer onto a single component.

"If you make an MCM the brain of the computer, the computer will be smaller and lighter. And as the overall weight is reduced, the power consumption is lowered," Kim said.

In the race to build smaller and more powerful computers, the components sometimes pay a price for such small quarters. MCMs are based on multiple thin metal layers that are sandwiched together to form a substrate, each embedded with interconnects that allow the chips to talk to one another.

The high temperatures and pressures of the manufacturing process can result in short circuits or other defects in the interconnections. Because the lower levels of the substrate are no longer directly accessible during the final test stages, many electrical contacts are required for a complete test, driving the cost of testing an MCM to as much as half of the total manufacturing cost.

Kim's testing method is based on a relatively simple setup of a voltage source and an off-the-shelf resonator to produce a signal to send through the interconnect being tested.

For more information, contact Deborah Halber, Tufts University, (617) 627-3500.

Interface links transducers and microprocessors

With the approval of a new interface standard developed by NIST and industry, users and makers of sensors and actuators soon may be exulting in diversity, rather than lamenting it.

Just adopted by the Institute of Electrical and Electronics Engineers, the digital standard (IEEE-1451.2) provides a common "smart" link between transducers and microprocessors. The interface could spur some healthy mingling of technologies and applications in what is now a highly fragmented market.

Numbering about 3,000, transducer manufacturers have tended to specialize in application areas, each favoring a small subset of the multitude of control-network alternatives. "It has been too costly for many transducer manufacturers to customize their interfaces to the particular requirements of each network," explains NISDT's Kang Lee, chairman of the IEEE committee that developed the standard. Consequently, industrial customers' technology options were also limited, despite the burst of innovation in sensors and actuators.

The IEEE standard is network independent, making it able to work with microprocessors designed for any of the various control networks. It features a standard digital format for transferring data from transducer to processor. The format includes a transducer electronic data sheet that contains information ranging from data code and serial number to sampling rate and date of last calibration.

For more information, contact Kang Lee, NIST, (301) 975-6604.

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