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Electroglas Receives Patent for Advanced Dual Loop Z-Stage Control

Thursday, March 20, 2008

San Jose, CA -- Electroglas, Inc. (Nasdaq: EGLS), a leading supplier of wafer probing and software solutions for the semiconductor industry, today announced that they have received a patent for their "Dual Loop Z-Stage Control."

Dual Loop Z-Stage Control significantly improves the ability to accurately and quickly position semiconductor devices in wafer form against the probe card. This results in reduced damage to the device contact surfaces while maintaining good electrical continuity between the device and the test equipment. The method of implementation of the second encoder chosen by Electroglas simultaneously solves the problem of thermally induced Z-stage position errors when testing at elevated temperatures.

As is the case for any motion control system, knowing the acceleration, velocity and position of the Z-stage at any given time is paramount in avoiding overshoot and settling. Until now, single encoders were used to provide positional information on the Z-stage drive motor. Although the input from a single encoder can be mathematically converted to velocity and acceleration information, the real time aspect is lost in this process. By adding a second, absolute encoder close to the surface on which the wafer is held, both velocity and position can be read directly. In addition, the thermally compensated attachment point of the second encoder ensures that the desired position can be maintained across a broad range of test temperatures.

Uday Nayak, Electroglas Sr. Director of Engineering, states: "We are operating in a very competitive industry and therefore are always looking for new technology that will differentiate our tools. The advanced control over our Z-stage can result in a significant yield and throughput improvement for our customers. Receiving this patent underscores the uniqueness of the Electroglas solution as well as protecting our advantage in this area of machine performance."

About Electroglas

Electroglas is a leading supplier of wafer probers and software solutions and services for the semiconductor industry. For more than 40 years, Electroglas has helped integrated device manufacturers (IDMs), wafer foundries and outsourced assembly and test (OSAT) suppliers improve the overall effectiveness of semiconductor manufacturers' wafer testing. Headquartered in San Jose, California, with offices throughout the world, Electroglas has shipped more than 16,500 systems worldwide. Electroglas' stock trades on the NASDAQ Global Market under the symbol "EGLS." Additional information about Electroglas is available at

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