Special Report Switching Systems Fi

From reed relays to matrices, products adapt to customer needs

June 21, 2018

Switches are seemingly simple and ubiquitous devices, but selecting one—whether a solid-state device, electromechanical relay, or reed relay—can present challenges to an engineer whose focus is on communications systems, military equipment, medical devices, automotive electronics, or test-and-measurement instrumentation, for example. Gather the switches into a matrix or other system, and the challenges multiply. Fortunately, switching vendors can help meet your switching needs.

“The biggest thing we run into is that customers don’t have the time to reinvent the wheel by learning everything about switching for their specific needs,” said Nick Turner, CEO of Cytec. “While switches should be a fairly simplistic subject, we have a lot of experience and knowledge about relay types, what problems [customers] will run into with specific signal types, and why some switch, control, or connector types should be avoided in certain applications. Our customers are typically looking for switches to automate a procedure to save time and money. They come to us so they can make that happen with as little pain as possible.”

Semiconductor applications

Tektronix serves semiconductor test applications with its S530-HV and S540 test systems, as outlined in the article on p. 8. James Yu, application engineer for the Keithley product line at Tektronix, described several new switch matrices built into those systems, including the 7072-HVD low-current and high-voltage matrix with models operating up to 1 kV or or 3 kV. They include an auto discharging function.

Yu noted that DC testing applications for power semiconductor wafers, including process-control monitoring, reliability test, and wafer acceptance test (also known as good die test) include breakdown-voltage, leakage-current, on-resistance, capacitance, and other standard semiconductor parametric tests.

Production customers need the same quality as lab-grade results, Yu said, while lab/research customers need to test with multiple conditions/parameters such as very low current test and high voltage test. And they need these features while requiring switching capabilities for multiple instruments at one probing device. “Our switching solution provides a wide range of signal pathways,” he said, noting that the switches handle currents from femtoamperes to 2 A and voltages from microvolts to 3 kV. In addition, he said, millisecond pathway switching supports high productivity.

Pickering Interfaces also addresses the semiconductor applications, among others. “Like any high-tech industry, time is money in the semiconductor industry,” said Bob Stasonis, director of sales and marketing at the company. “So, semiconductor test engineers may spend more money on test hardware if the improved test time saves the added cost. To that end, we have focused on a hardware sequencing scheme that is vastly faster than software sequencing due to latencies in most OS architectures.” He added that the use of reed relays is important because they are much faster to open and close compared to electromagnetic relays (EMRs). “While solid-state relays are the fastest, they exhibit poor isolation characteristics,” he added. “The isolation specification is important because of insulation resistance testing required for today’s chip sets. In many cases, the isolation resistance of a matrix needs to be on the order of 1013 Ω.”

Serving many niches

In addition to semiconductor test, said Stasonis, “We really sell into virtually any electronic industry niche. We do focus on aerospace/defense, automotive, medical, and communications. However, you will find our products being used for test in companies that manage the power grid, build massive diesel engines for ships, build satellites, and make monitoring systems for turbines, to name but a few.”

Stasonis cited several benefits, including Pickering Interfaces’ ability to tailor its offerings to meet customers’ requirements for parallel testing in order to reduce test times and to provide scalability. The products are designed for ease of maintenance, he said. “We have our standard catalog of connection products, and for custom requirements, we offer our free on-line Cable Design Tool (CDT),” he said.

“A key feature is how our products are tailored to industry requirements, rather than the industry adapting to what is available,” said Stasonis. “We work closely with customers to fit our products to their applications and offer support to get them up and running.” The company also provides long-term support—for 15 years or more—and a 3-year warranty. “We also are more than switching—our supporting products include cables and connectors, software drivers, switching-manager software, and diagnostic solutions.”

Sibling company Pickering Electronics focuses on reed relays. According to Graham Dale, technical director at the company, “Since 1968, our target market has been for instrumentation and test equipment. Over the years, the quest for miniaturization has excelled; therefore, high-density test applications are now one of our biggest served areas. Our customers, on average, fit up to 80% more relays onto their PCB designs, due to our innovative products.”

At Pickering Electronics, Dale added, “We use only the very highest quality ‘instrumentation grade’ reed switches to meet the demands and long life required by today’s equipment manufacturers. Pickering relays are 100% tested for all operating parameters, including operate and release voltages; operate, release, and contact bounce times; contact resistance; contact resistance stability; and insulation resistance.”

Commenting on application areas, Dale said, “Data acquisition is an area where our products are very successful. The high coil resistance figures reduce self-heating for improved thermal EMF figures. A lower power consumption is useful to conserve battery usage in portable devices. Other applications where you will usually find our reed relays include semiconductor test, high voltage, RF, and high-speed digital switching.”

Stuff no one else offers

According to Turner at Cytec, the company’s new-product niche has always been building the stuff no one else offers. “Switching is all we do so we tend to have a lot of specialized products for specific applications,” said Turner. “Rather than just offer a line of standard products and ask the end-user to make it work, we can customize them to fit their needs. Many of our products have LED indicators, which helps with programming, and we have used the same simplistic ASCIII text string command format for 35 years, which keeps things very simple no matter what control interface you use.” The company offers a 5-year standard warranty and lifetime tech support.

Figure 1. G.fast line-length switch composed of low-crosstalk transfer switches with RJ45 CAT6A connectors for automating crosstalk testing on G-fast DSL cable and equipment

When asked what specific application areas Cytec serves, Turner said, “We do it all,” adding that the company works in areas other vendors don’t address due to the small number of requests, such as those involving very low currents or very high voltages and currents. The company also builds fully customized RF and microwave or one-off solutions for specific test applications. “Some of the applications people come up with are rather amazing,” Turner said, “so we just address them all individually.” He cited as examples high-frequency 75-Ω coax switches for DOCSIS 3.1 cable signals and a G.fast line-length switch, which he described as “…a bunch of low-crosstalk transfer switches with RJ45 CAT6A connectors for automating crosstalk testing on G.fast DSL cables and equipment” (Figure 1).

Turner added that Cytec can also provide software assistance for any programming language at no charge. “We offer drivers for industry-standard platforms such as National Instruments LabView or LabWindows and full-blown GUI software in Java,” he said. “We have programming examples in almost every language and have started offering full custom software solutions as a purchased product.”

Figure 2. Pickering Interfaces 40-202 2-A fault-insertion switch module

Commenting on new products from Pickering Interfaces, Stasonis said that in recent months, the company has introduced the 40-202 2-A fault-insertion switch module (Figure 2), a 4-slot USB/LXI chassis that can accept the majority of Pickering’s 3U PXI switch modules, and finally a major update to SPM (Switch Path Manager) software.

The new fault-insertion switches come with 22 or 11 fault-insertion channels and can simulate fault conditions in automotive and avionics test applications involving the reliability testing of safety-critical controllers. They are specifically designed for differential signaling requirements, with capabilities to insert three different types of fault conditions between the test fixture and the equipment under test: open-circuit, short-circuit between signal pairs, and short-circuit to user-applied fault conditions such as power or ground.

Version 6 of SPM offers a range of new capabilities as well as a new “lite” version. The software simplifies signal routing through complex switching systems and speeds up the development of switching system software. New with Switch Path Manager 6, the software evaluation period is now 14 days, but the time is based on the number of days the software is actually used rather than a fixed period of time. Switch Path Manager Lite is a low-cost solution that is fully functional but with an operational limitation of two active switching modules in a configuration.

Figure 3. PXI matrix featuring Pickering Electronics Series 124 reed relays

For its part, Pickering Electronics has introduced its Series 124 4-mm x 4-mm reed relay that switches up to 5 W at 0.5 A, enabling a dense matrix in PXI (Figure 3). In addition, said Dale, “In 2016 we introduced new high voltage products. The Series 119 is a range of very small single-in-line reed relays with stand-off voltages up to 3 kV. Being less than half the size of established packages, these are ideal for applications such as backplane, cable, transformer test, and other high-voltage applications. The Series 67 and 68 are larger high-voltage relays featuring 50-W tungsten contacts for up to 10 kV. The Series 67 is a PCB mounting relay, while the 68 has flying leads for the high voltage connections, keeping them away from the PCB.”

Other companies have also reported recent innovations in switching. The SentinelEX Switching Series is the most recent switching product introduction from AMETEK VTI Instruments, according to Jon Semancik, director of marketing at the company. “These PXIe switching modules are designed to maximize the integrity of test signals by incorporating advanced circuit-board layout techniques that minimize the effects of unwanted transmission stubs, shield against radiated signals in adjacent card slots, and ultimately extend the usable bandwidth of the test system as a whole,” he said.

A software driver approach based on IVI industry standards lets a single driver session control multiple modules as a subsystem, thereby reducing development time. Advanced triggering and module-to-module synchronization reduces test execution time, while chassis smart health monitoring and relay odometers offer a predictive approach to maintenance, the company reported.

In addition, Universal Switching Corp. recently announced a new switching product—its low-frequency System TS202A Instrumentation Matrix (32×32), designed to automate connectivity of patching signals under test to test equipment, recorders, and evaluation instrumentation.

Many engineers still use manual patch cords and patch panels to interconnect sensors, recorders, scopes and other instrumentation in test and evaluation labs, the company reported. The TS202A can automate much of the lab connectivity while eliminating errors from human patching as well as mechanical connectivity problems from continuous patch-cord activity.

The TS202A provides up to 64 inputs and 64 outputs in a nonblocking full fan-out array. It includes built-in self-tests that noninvasively verify the validity of closed crosspoints (go/no-go). Each input is a differential pair to help eliminate low-frequency sensor noise, and each output is single-ended. Each negative input (of the input pair) can individually be switched to signal ground for application-dependent needs. A DIP switch provides this function for each input depending upon specific signal requirements. The TS202A includes front-panel touchscreen and single controller. Self-monitoring redundant hot-swap power supplies can be powered by any international AC power source. Optional 1RU rack-mount isolated BNC panels and customized configurations are available.

Industry trends

As for industry trends, “Pretty much all electronic equipment manufacturers have been experiencing continuing downward pressure on prices as buyers tighten their equipment budgets,” said Semancik at AMETEK VTI Instruments. “Our newest products are designed to respond to that trend by helping buyers build powerful systems more economically, without sacrificing the performance and capabilities their applications demand.”

According to Stasonis at Pickering Interfaces, “For the semiconductor industry, we will focus on high isolation resistance requirements and higher pin counts that are scalable. For other markets, we are looking at higher voltages in PXI with higher-voltage reed relays and a broader range of resistor modules to address customer demands.”

“We are continuing our quest for further miniaturization. This is where the company excels. We believe that we are the market leader in high-density reed relays,” said Dale at Pickering Electronics. “As no one relay addresses every application, we are constantly developing new models. We have many instances of special requirements from semiconductor customers, where we design special parts for their applications, as there are no standard products on the market that can serve their specific needs. We often are able to provide exactly what the customer requires”—through an adaptation of an existing part or a completely new part.

Concluded Turner at Cytec, “The trends don’t really change much.  It’s always performance vs speed vs size vs cost.  We are always looking at new technologies to improve any of these areas and offer the most versatile products at the lowest price.” EE

AMETEK VTI Instruments
Cytec
Pickering Electronics
Pickering Interfaces
Tektronix
Universal Switching Corp.

About the Author

Rick Nelson | Contributing Editor

Rick is currently Contributing Technical Editor. He was Executive Editor for EE in 2011-2018. Previously he served on several publications, including EDN and Vision Systems Design, and has received awards for signed editorials from the American Society of Business Publication Editors. He began as a design engineer at General Electric and Litton Industries and earned a BSEE degree from Penn State.

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