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issue: February 2008 APPLIANCE Magazine

Switches & Switching Devices
Switching on Versatility


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by Leanna Skarnulis, Contributing Editor

Suppliers of switches and switch technology must meet a host of demands from an appliance industry in flux.

PSE switches from Schurter Electronic Components offer protection in hostile environments, vandal-proofing, explosion-proofing, IP ratings from 40 to 67, and tactile or optical feedback.

Driving change in the global appliance landscape are gains in market share by Asian OEMs, a slumping U.S. economy, competition for improved design and functionality, the need to keep materials and labor costs down, new limitations posed by the Restriction of Hazardous Substances (RoHS) Directive, and other new materials restrictions.

Impact of a Geographic Shift

“The appliance industry continues to go through a large transition,” says Paul Farrell, director of sales and marketing for appliance and commercial building equipment, Tyco Electronics (Harrisburg, PA, U.S.). “From the OEM standpoint, they continue to try to make more-efficient appliances, to electronify appliances on the high end, to design in North America, and to migrate harnessing to Mexico and Asia Pacific.” He says that the majority of control boards for U.S. dishwashing, cooking, and laundry appliances are designed in the United States, manufactured for subassembly and subassembled in Asia Pacific, and shipped back to North America for final assembly.

“As electronics and more harnesses migrate to Asia, there has to be local manufacturing capability,” says James Connors, appliance industry manager for Tyco Electronics. “OEMs want product that’s locally available. They don’t want to have to ship product over there from North America.”

That means switch suppliers need to be globally deployed in order to serve those OEMs. “Fortunately, Tyco Electronics is locally deployed in all three regions of the world,” says Farrell.

“The appliance industry is in a down cycle, suffering due to the credit crunch and housing slump in the U.S.,” says Farrell. He adds there’s increasing pressure on North American manufacturers from Asia. “You see in Best Buy a larger concentration of higher-end appliances from companies like Samsung and LG.”

Medical Equipment an Exception

One industry segment that remains healthy in spite of the ailing credit and housing environment is medical equipment. “The medical industry is growing. As a result, there’s a lot of opportunity for switches, such as rocker switches on ultrasound machines,” says Mark Zitto, product manager, Tyco Electronics. “In addition, there’s increasing use of disposable handheld appliances requiring switches.”

Medical equipment OEMs demand switches that offer safety, durability, and reliability. Diane Cupples, vice president of marketing for Schurter Electronic Components (Santa Rosa, CA, U.S.), says one requirement is a low profile for switches so that equipment can’t be accidentally activated. Another requirement on certain types of equipment, such as wheelchairs and hospital beds, is the ability to withstand repeated actuation and use by multiple operators. “Use of stainless-steel and heavy-duty, low-profile switches becomes important. Piezo switches—electronic switches with no mechanical or moving parts—don’t break down over time due to continued actuation, so they’re more reliable.”

A piezo switch consists of a small piezo crystal element connected to an electronic hybrid circuit and sealed in a rugged housing. Compressing this element distorts its crystal structure to create a voltage between its surfaces which can be amplified and interpreted as a switching signal. Service life can be 20 million operations.

E-Switch’s new 100K-series locking toggle switch prevents appliances from being accidentally turned on or off. Markets include telecommunications, instrumentation, networking, and medical equipment.

Looking Good

Appliance OEMs are looking for aesthetic enhancements and switches that integrate into their look. Competition among suppliers to meet that demand is keen. Cupples says manufacturers of high-end appliances are driving the demand for improved aesthetics such as metal switches that integrate nicely for an overall sleek look. “There’s a multitude of technologies and a vast number of suppliers doing niche or broadline types of products. The appliance designer has a lot of options to choose from.”

She says the challenge for the supplier is to do a good job explaining the key features and benefits to appliance engineers so they can better integrate them into their appliances. “For example, costs can vary from one extreme to the other. In the case of metal-line products, we have a lower-cost product as well as the higher-end piezoelectronic products. There you have a vast array of products and prices within the range of push-button switches. We have to get to the designer, understand their challenges, and be able to provide solutions. They see a standard product and want to know if they can get it with a different color light or a resistor for different voltage. The more you work with appliance designers, the better you can help them solve problems.”

Trend toward Miniaturization

Appliance OEMs want switches with a smaller footprint and more power. “The push has been to smaller devices and SMT products, which help the OEMs to reduce costs in their manufacturing,” says Ron Celander, director of engineering for E-Switch (Brooklyn Park, MN, U.S.).

C&K Components’ (Newton, MA, U.S.) worldwide product manager David S. Webber agrees that miniaturization is a trend, but he says to some degree it’s limited by the materials. “Many appliance manufacturers use tactile switches and membranes with relays to step up and down power.” He adds that saving real estate on PCBs has become a priority for appliance manufacturers.

C&K recently introduced the KMT series, billed as the industry’s smallest top-actuated tactile switch with integrated push plate. It is said to offer sharper tactile feel and an extended life cycle of 150,000 operations. C&K senior product manager Jerome Smolinski says an integrated actuator for simpler button design yields an excellent tactile ratio of 30% minimum, providing sharp feedback. A grounding pin option for ESD protection is available, as well as actuation force options of 1.6 N (tactile ratio 30%) for mobile devices and 1.0 N (tactile ratio 10%) for hearing aids and headsets.

More electronics are being packed into appliances and space constraints are tightening, so OEMs demand more power with a smaller footprint. “Components have to get smaller,” says Connors of Tyco. They also have to handle more power. One answer from Tyco is its recently released PRC series of power rocker switches. The series is designed for snap-in panel mounting and carries an IP66 rating for protection against dust and liquids. Applications include vacuum cleaners, HVAC equipment, power tools, power supplies, audio equipment, and fitness equipment.

“There’s still a market for commodity switches, but as appliances get upgraded and the focus is on more efficiency, custom applications are increasingly in demand,” says Connors.

C&K’s miniature slide switches in the JS Slide Series are designed to offer low-profile, cost-effective solutions for applications with limited PC board space and height restrictions, including mobile telecommunications, computers, and remote-control equipment.

Technology in the Kitchen

The challenges posed by the kitchen environment drive many technological improvements in switches. “Sealing improvements have occurred, especially in the areas of cooking, dishwashing, and refrigeration,” says Connors. “External switches have to be protected from the environment. Moisture-proofing is a key item with all the different cleaning agents used in the kitchen. Also there’s ongoing focus on improving temperature ratings for cooking applications.”

Cupples says a priority for Schurter has been improvements in push-button switches to address market demands for ingress protection, impact resistance, vandal-proofing, and protection from extreme temperatures. All these factors come into play in commercial kitchens. “Restaurant frying machines, food-dispensing machines, cookers, and grills are examples,” says Cupples. “One challenge is having product that can withstand ingress of any type of material that would leave particles or bacteria on equipment. These elements have to be removed through washing, deep cleaning, or even power washing.”

Schurter’s Piezo PSE models have been tested under high-pressure washing and steam-cleaning conditions and carry an IP69 rating and an extended temperature range of –40° to 85°C.

Inside and outside the kitchen, switch suppliers are continually improving functionality that benefits appliance OEMs. “Expanding mechanical and electrical life, coupled with increased operating temperature ranges, has allowed appliance makers to extend warranty periods,” says Webber. “C&K has invested in materials and process development and conducts extensive testing and verification to ensure long life.”

The new PRC Power Rocker Series from Tyco Electronics Corp. is rated IP66 against dust and liquids. The switches are designed for snap-in panel mounting in appliances that include vacuum cleaners, HVAC equipment, power tools, power supplies, audio equipment, and fitness equipment.

RoHS Rules

The European market is driving a significant change in switching technology through its RoHS Directive restricting hazardous materials. “More components, including switches, have to be RoHS compliant,” says Connors. “All OEMs are working on more global designs, so anyone supplying to North American markets for switches and other devices has to have a comparable offering for RoHS-ready components.”

Changes in materials and finishes to meet RoHS compliance put an added burden on component manufacturers, says Zitto of Tyco. “Costs will sometimes increase because you have to build new molds, for instance, yet you have to hold costs down to be competitive.”

Of the six materials restricted by RoHS, lead and cadmium have had the most profound impact on the switch industry, including lead in the form of tin/lead solder and tin/lead plating. In an article describing the RoHS challenge, Peter Brouillette, general manager for APEM Components Inc. (Haverhill, MA, U.S.), writes: “The RoHS Directive has forced PCB and component manufacturers towards ‘lead-free’ processing, producing two challenges for the switch industry: the elimination of lead and the modification of product designs to ensure switches can withstand the higher temperatures associated with new lead-free solder processing. APEM has developed alternatives to tin/lead, offering silver, gold, and matte tin-plating options on its 125 families of switch products.”

Silver–cadmium oxide (AgCdO) remains the material of choice for high-current electrical contacts in many switches and relays. “Unfortunately, alternatives to silver–cad oxide do not provide the same benefits,” Brouillette writes. “One material being considered as a replacement by many switch companies including APEM is silver–tin oxide (AgSnO). Silver–tin oxide contacts are harder than AgCdO and provide superior welding resistance, but unfortunately provide lower electrical conductivity performance.”

Use of cadmium and its compounds for electrical contacts is exempted from the RoHS Directive.

In addition to RoHS compliance, certification and verification are of particular concern to appliance makers, says Webber. “C&K is well positioned, given our worldwide footprint and having a testing facility in plants across the globe.”

APEM featured its expanded IPP series at National Manufacturing Week (Rosemont, IL, U.S.) last September. The switches are designed for applications that require a sealed, ergonomic electrical interface.

More-Stringent Plastics Standards

Another challenge for the switching industry is increasingly stringent UL/CSA/IEC standards for plastic materials. “This mainly has to do with flammability requirements within hot wire and glow wire,” says Connors. “A number of materials that might have been good three or five years ago are in the process of changing. Each appliance has its own standard. For example, with refrigeration, there are a lot of IEC requirements for glow wire. It affects not just switches, but also terminal connectors and other component areas.”

In developing plastic materials, Tyco Electronics works closely with its own test labs and those of customers. “Some customers’ standards are more stringent than others,” says Connors. “So when you meet requirements of one OEM you may have added requirements to consider for others.”

Helping OEMs Cut Costs

Switch suppliers as well as suppliers of other components are faced with the challenge of trying to help appliance OEMs reduce production costs even as the cost of raw materials climbs.

“Appliance manufacturers continue to seek out components that will help improve the overall quality and reliability of their products while at the same time making every effort to maintain or reduce costs,” says Lloyd Bodle, national sales manager for E-Switch. “This has become increasingly difficult in today’s world of surging raw materials costs. E-Switch works closely with our customers to suggest and design switching solutions that help our customers achieve these goals. We continue to find ways to improve product design to ensure long-term reliability while maintaining very competitive prices.”

OEMs also expect suppliers to reduce the number of components and simplify assembly.

Connors says helping OEMs keep manufacturing costs down is an ongoing priority for Tyco. One way is by replacing point-to-point wiring with mating housing connectors on rocker and micro switches to reduce labor costs. “Tyco Electronics’ advantage is that we provide not only the switches but also the mating harness components,” says Connors. “Part of our extensive product offering is terminals and connectors to mate to various components. We produce both custom and standard connector solutions for mating to switches which allow the OEMs to reduce their assembly costs.”

Zitto says there’s been a shift in higher-end appliances to go to more electronics. The move has been to switches with lower currents. For example, a washing machine that once used a rocker switch now uses tactile switches. “With tactile switches, OEMs have more design freedom, and the cost is much lower than for a rocker switch.”

Connors adds that tactile switches are put on electronic assemblies as well. “It gives OEMs the benefits of automation in manufacturing. They’re already developing a control board, and now they can eliminate some hard-wired switch points and add them to the electronics they already have.”

Besides trying to help appliance OEMs reduce material costs and boost manufacturing efficiencies, Connors says Tyco Electronics seeks to help OEMs improve ergonomics. “Preventing injury to operators is of increasing importance.”

Staying Current

As appliance trends in place for a number of years—such as lean manufacturing and the demand for improved functionality—meet newer trends, such as the shifting global marketplace and the RoHS Directive, switch suppliers are challenged to stay current. Perhaps the greatest demand of OEMs is for suppliers that make themselves part of the solution.

 

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