by John Williamson
Contributing Editor, MEMS Investor Journal
The proliferation of electronic devices and manufacturers' needs to test products before releasing them to market has placed added importance on the automated test equipment (ATE) industry. Switching is a key component in ATE with options that include MEMS and non-MEMS based devices. We recently polled a number of players in ATE switching to get their views on the topic including the current technology status, cost trends and upcoming milestones. In this article, we share the participants' sometimes widely different viewpoints.
ATE Market Outlook
John McKillop, Managing Director of Tekton Consulting, identifies three main ATE applications where switching is used: load boards, pin electronics and signal distribution. "These applications are generally satisfied by three types of switches: electromechanical, reed relays and MEMS," Dr. McKillop says.
In terms of the ATE market outlook, Omron Corporation believes that the market will not see the growth this year that occurred in 2010 largely due to overcapacity in some consumer driven ICs. Yet, according to Product Manager Donna Sandfox, "MEMS relay demand will dramatically increase by the second half of 2011 due to the completion of long-term qualification studies coupled with test engineers becoming more trusting in the technology."
Trust is an important concern at Giga-tronics Incorporated, where CTO Jeffrey Lum cites poor reliability and high failure rates for MEMS switches as reasons why the company does not employ the technology in products for a majority of their customers. Power and voltage limitations are also concerns.
Countering this is a list of positive attributes for MEMS ATE switches offered by Dan Hyman, President of XCOM Wireless. "MEMS are small, enabling switching to be placed close to devices under test," he says. "They are fast, they consume no, or low, power and they last a long time. MEMS are repeatable and inexpensive when considering their high level of performance."
A similar optimistic outlook prevails at Radant MEMS where Vice President and Chief Operating Officer John Maciel comments, "We have seen the ATE business improve over the past 6 months," adding "the major advantages of employing MEMS switches in ATE are their much greater bandwidth and reliability over traditional solutions, which are dominated by reed relays that suffer from limited high-frequency performance and orders of magnitude less reliability." As an example, he cites 10 million switching cycles for reed relays versus 100 billion cycles for MEMS. "We see MEMS becoming an attractive alternative to current technologies," Dr. Maciel predicts.
MEMS switch for ATE applications. Photo courtesy of Radant MEMS, Inc.
This positive view is echoed at Omron, where Senior Sales Engineer Jeff Rumowski says, "Our MEMS relay offers guaranteed electrical life of 100 million operations, hot switched at 0.5V DC and 0.5 mA. This far surpasses any other available mechanical high frequency relay on the market today."
Other features cited include an extremely small size and power consumption (10 uW), a fraction of that required to operate a coil-driven electromagnetic relay, making it ideal for high-density board test applications. The downside, Rumowski says, is that the small size makes MEMS relays susceptible to electrostatic discharge (ESD) during assembly, which calls for precautions, including properly ground equipment.
John McKillop at Tekton believes that the best application for MEMS switches in the short term is for load boards. "Here they offer the advantages of low contact resistance in the DC mode, broad bandwidth for high speed digital signal integrity, and low cost," he says. Dr. McKillop also comments that disadvantages of EM switches include large size, costs in the range of $5-$10 and relatively short lifetimes. This compares to approximately ~$1 for reed relays, he says.
XCOM's Dan Hyman says that despite encouraging trends there is lots of room for improvement in the ATE business. "The industry is highly fragmented, specialized and lagging behind the recovery of its own customers. Fortunately the wireless and high speed digital ATE market segments have not seen the same level of slowdown as the industry as a whole," he says. Dr. Hyman comments that the increasing semiconductor and wireless test costs as a percentage of product cost suggests the testing infrastructure has not kept pace with Moore’s Law or the wireless revolution. "We anticipate that recovering consumer confidence will encourage the industry to invest in emerging technologies and get back on track to control testing cost and improve system up-time," he says.
A different perspective is provided by Jordan Dolman, Product Manager for National Instruments non-MEMS switches. "Traditionally, electromechanical and reed relays have been the technology of choice for ATE despite shortcomings such as limited switching lifetimes. We address this with switch modules that store the number of relay actuations on an EEPROM and access the information through software function calls," Dolman says. Another approach is the adoption of solid state or FET technologies with their low drive current and unlimited switching lifetimes. "This has proved useful in creating very high density switch matrices offered by National Instruments," he says. Dolman also offers this comparison of four non-MEMS ATE switching options:
As to MEMS based ATE switches, Dolman comments they offer high cycle lifetimes, excellent RF specs and low drive currents when compared to the non-MEMS switch types cited above. However, according to Dolman, MEMS based relay cycle lifetime drops dramatically as switching current, voltage and power increase. According to Dolman, this severely limits MEMS device use in DC switching applications.
Looking Ahead -- Technology and Pricing
Radant's John Maciel believes MEMS based switching can meet upcoming technical challenges facing the ATE community. "We do expect further penetration into that market," he says. "The main limitation to MEMS is a higher price compared to reed relays but this can be offset by the higher frequency performance and longer life of MEMS switches." He forecasts that the price gap will close as volumes ramp up.
Omron's Rumowski says technology milestones for 2011 will include higher frequencies and multiple switches per package. Concerning non-MEMS switches, National Instruments' Dolman predicts that solid state switching will gaining traction for both DC and RF/microwave automated test applications. "In high-volume production test systems the unlimited switching lifetime of solid state RF relays is proving to be invaluable," Dolman says. "This is a major differentiator from MEMS devices and their limited lifetime."
On costs, the feeling at Omron is that MEMS relays are priced reasonably when the total switching cost over the life of the board is considered when compared to products with a much shorter life span. Radant provides specific figures, citing typical reed relay switches at ~$5 compared to their lowest-cost MEMS switch at ~$10. MEMS pricing will become more attractive as production volumes increase, according to John Maciel.
XCOM's Dan Hyman predicts that the industry players will be investing in new technologies across many levels. "Software reconfigurability is probably the most important factor in this industry," he says. "This allows system manufacturers and users to squeeze much more function and cross-platform value out of each new system."
Batch fabrication of MEMS relays at high production volumes enables low prices. Photo courtesy of XCOM Wireless, Inc.
Summarizing costs, Dr. Hyman believes that electromechanical components will range from a few up to many thousands of dollars depending on configuration and performance. Reed relays, at a lower cost tier, are generally in the $1 to $10 range while semiconductor relays have perhaps the widest cost range -- from a few cents to hundreds of thousands of dollars depending on application. As to MEMS pricing, Dr. Hyman says that because these are semiconductor products their cost structure closely matches the semiconductor industry. As examples he notes that MEMS relays are available in the $20 - $50 range for low volumes of surface mount parts or $100 - $1000 for coaxial boards. "Fortunately batch-fabricated MEMS relays scale down to $2 - $6 in higher volumes and can compete with reed and semiconductor relays in cost-sensitive applications where higher performance adds real value," he says.
At National Instruments, Jordan Dolman says that in ATE switching the cost of the relays has a direct impact on the pricing of the final products, with improved specifications often coming at a higher price. "For a high-density matrix switch, prices start at $5.5 for a FET crosspoint and go as high as $10 for a reed crosspoint," he says. "In the RF space, a 2.7 GHz SPDT will cost $400 while a 26.5 GHz version will cost $675." He adds that as the cost of relays decreases and the performance of new models increases, ATE switch vendors will be able to upgrade their products to provide improved specifications at a lower cost.
In Conclusion
These viewpoints and predictions by producers of switches and ATE equipment suggest that serious thought be given to switch selection by manufacturers of automated test equipment. As the role of production testing becomes increasingly crucial, the importance of selecting the correct ATE switching option likewise will grow.
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This article is a part of MEMS Investor Journal's ongoing market research project in the area of MEMS and non-MEMS switching devices for ATE applications. If you would like to receive our comprehensive market research report on this topic, please contact John Williamson at jwilliamson@memsinvestorjournal.com for more information about rates and report contents.
Copyright 2011 MEMS Investor Journal, Inc.