MEMS goes into 10A power switches
Until now, the company says, many industries have had to live with the tradeoffs of solid-state controls, including high-leakage currents, lack of air gap and complicated thermal management, or electromechanical solutions that are slow, bulky and expensive. For its 200V/10A DMS smart power relay, Menlo has combined over 200 micromechanical high-voltage switches, with fully integrated protection and controls, and designed it into a Smart Power Relay evaluation board. The credit-card-sized board is capable of carrying 10A of DC current, without the need of a heat sink.
Typically, these switches are 3-terminal devices operating in the 25W to 50W range. For the Smart Power Relay, Menlo has created a fully isolated 4-terminal architecture, complete with advanced features such as over-current protection.
In an interview with eeNews Europe, Menlo Micro’s Senior Vice President of Products Chris Giovanniello gave us a glimpse of the future.
As the company is using the same proprietary materials and processes across all its lines of switches (RF and power), it can make different products with exactly the same mask, only using a different number of switches (through step replication), explained Giovanniello. Describing the MEMS switches as mechanical transistors, he said those could be used as elementary blocks to design power switches.
“For the power relay, we simply stack more of those mechanical transistors, which allows us to push 10A through it” Giovanniello said. “The more metal, the more contacts, it can scale nicely to massive arrays” he said, adding that power relays could easily be built to handle 20, 50, 80 or even over 100 Amps.
The DMS Power Relay architecture boasts an 80 to 90 percent reduction in volume and weight over electromechanical relays. Each metal-to-metal contact is smaller than a human hair, and when combined in massive arrays, can provide extremely low on-state losses (<10mohm) in a very small package, eliminating the need for large, heavy heat sinks. This will enable entirely new form factors for power electronics designers.
The new relays offer a 1000x improvement in switching speed over traditional electromechanical relays and can be integrated into traditional semiconductor packages (like System-in-Package or Multi-Chip-Modules) while retaining the galvanic isolation properties of traditional mechanical relays.
The company develops the switches at wafer-level but then cuts them in dies for assembly into differentiated products. On its roadmap, it is working on packing more switches for a given mm2 of die area. “For GE’s healthcare products, we delivered 26 switches on a die, then our first RF product had 48 switches on a die. But before we spun out of GE, we did a die with 400 switches. To get a high current density per die, we could create 32x32mm dies, but for yield and efficiency of scale, it makes more sense to have smaller building blocks, around 10A at die level if we are going to have 5x5mm2 dies” explained Giovanniello. “Then building a 50A switch is just a matter of stacking more dies”.
“We have ambitious plans for this year. We’ve already qualified three more switches for production before the end of this year for four different market segments. We are also in the process of moving out our manufacturing from GE, to scale it up in a commercial fab sourced at a lower cost.
Our transfer is close to 90% complete, moving from 4-inch wafers to an 8-inch wafer line which will be qualified by the second half of this year. It’s all going very well” commented Giovanniello.
“We have four or five different customers designing their initial products with our devices for evaluation and we are shipping engineering samples. Until our production line is qualified, we won’t be able to claim design wins but we are targeting a hand-full of design wins before the end of 2018” Giovanniello concluded.
Menlo Micro – www.menlomicro.com
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