Electromechanical switches used in extreme environmental conditions offer more than ruggedness and extended operating temperature ranges, including miniaturization and easy installation for space-constrained applications

By Gina Roos, editor-in-chief

Selecting the right electromechanical switch for harsh and extreme environmental conditions like shock and vibration are a big concern for designers. Add the need for miniaturization and ease of installation into the mix, and it becomes a greater challenge.

This is particularly true for space-constrained applications, such as smartwatches and medical wearables. In many cases, these applications require more than miniaturization. They also need to withstand harsh environments like exposure to water and vibration, ease installation on the board, and offer long life.

The availability of more options and higher integration are also becoming more important in the drive to meet cost demands. These features help designers select the exact functionality for their application needs without driving up cost.

One of these switches isC&K’s Nano Tactile (NanoT ) switch series. C&K claims that this is the smallest tactile switch on the market for IoT devices, including smartwatches and medical wearables such as health-monitoring trackers and hearing aids. Growing customer demand for smaller devices is driving component miniaturization.

First, the switches are tiny, housed in a 2.2 × 1.70 × 1.65-mm package. This frees up board space for designers to add new functionality or reduce their PCB size. In terms of protection, they are available in PIP or SMT on edge-mount configurations to protect wearable and medical products from extreme environmental conditions such as vibration, accidental drops, or exposure to liquid while improving the devices’ life cycles. They are also IP67-sealed.

The switches also offer an integrated actuator that lowers cost and integration challenges with full interface buttons. They come in three versions: 100 gf, 160 gf, and 240 gf. Electrical life is rated at 300,000 cycles.

Also designed for harsh environments but in heavy-duty applications like transportation, construction equipment, industrial control equipment, medical devices, and marine equipment is the IP67-rated knurled toggle switch from NKK Switches. The addition to NKK’s M Series features a knurled, textured lever that enables a firm non-slip and ergonomic grip. An inner o-ring and an external rubber washer enable the switch to meet the IP67 rating to keep dust out of the switch and to protect the switch from temporary immersion in water.

Key features include a locking lever to prevent accidental actuation, an anti-rotation structure to protect the toggle and bushing, and an anti-jamming design to protect the actuator. Other features include external insulating barriers for increased insulation resistance and dielectric strength, as well as epoxy-sealed solder lug terminals to stop the entry of contaminants.

The molded case meets flammability standards for UL94V-0. The knurled cap is compatible with other M Series locking lever parts.

Emergency stop, or e-stop, switches used as a safety mechanism in machinery also need to meet tough environmental conditions along with industry regulations. Switch manufacturers are making them easier to install.

For example, RAFI has expanded its RAMO Series product offering of pushbuttons and signal indicators to include e-stop switches (E-Stop )  for rugged applications. E-stops are used to protect the safety of machine operators and machinery in a variety of emergency shutdown situations. These switches are regulated by international safety standards for performance and the requirements for e-stops on equipment. They meet ISO and IEC standards.

These pushbutton control components feature fully enclosed mono-housings with ingress protections (IP65, IP67, and IP69K) and are sealed from both above and below the mounting surface. The E-Stop switch features a 2NC contact capable of switching 35 V and is available in both 22-mm and 30-mm versions.

The design includes standard M12 plug-and-play connectors that simplify installation and save assembly time by reducing the amount of wiring effort. Installers can also use the M12 connectors featuring right-angle exits to fit into tight-space applications. Rotated by 135°, the cable exits allow for a high packing density.

APEM’s IX series of pushbutton switches combines a compact size, waterproofing, and customization for harsh environment applications, including material handling, military, and agriculture machinery. The IX series switches come with a backlit switch, a 12-mm-diameter compact bushing, and a flexible elastomer membrane switch.

The switch meets IP67 and IP69K sealing. The flexible elastomer membrane actuator with no space between the actuator and bushing guarantees the IP69K panel sealing. This provides excellent resistance to frost, sand, and other contaminants, according to APEM. The ultra-thin design is well-suited for tight matrix mounting.

In addition, the switch offers customization for colors and markings. The series offers nine actuator colors, illuminated markings with five LED colors, and several marking symbols. Illumination can be limited to the symbol or the entire membrane actuator.

Addressing the growing need to reduce weight and space in vehicles as car makers pack higher functionality across subsystems, Alps Alpine Co. Ltd. has designed the waterproof SPVQ8 Series  detector switch with a short fork terminal. Each car uses about 10 detector switches, said Alps.

The switch is compact, measuring 8.3 × 5.3 × 7 mm, and is used for detecting the opening/closing of side doors, hoods, and other vehicle doors. It can also be used in connection detection like seatbelts, electric vehicle chargers, and smart rearview mirror on/off detection.

The SPVQ8 series saves space with its short fork terminal design thanks to high-precision die manufacturing and stamping technology, which has reduced the overall thickness of the switch by 25%. In addition, it features a solderless design that allows for one-touch board mounting.

For use in shock and vibration environments, the switch design uses a double-sided sliding contact to ensure stable contact. The operating temperature range is –40°C to 85°C, and the operating life is 300,000 cycles. Other specs include an operating force of 1±0.5N and a 2.2-mm travel.

EAO has developed a complete series of switches with an extended temperature range for extreme environments. The Series 04 includes pushbuttons, indicators, selectors, mushroom-headed switches, key switches, and e-stop buttons. These switches are UL-certified and IP65-sealed (front protection) and operate over a temperature range of –40°C to 55°C. These switches are suited for a range of equipment including freezers, cold storage, and refrigeration.

The switch series fits into 22.5-mm mounting holes for standard raised mounting applications or 30.5-mm round and square cutouts for flush mounting. In addition, the series is modular, which allows for easy assembly and customization. Options include self-cleaning, snap-action, and slow-make switching elements. It also offers a range of contact configurations.

Series 04 components are rated up to 500 VAC. All products comply with international standards, including UL, CE, RoHS, CB – EN/IEC 60947-5-1, NFF 16-102, CSA, CCC, GOST, and German Lloyd. UL approval is for copper wire, size 26-16.

E-Switch has added a pre-wired option for its ULV anti-vandal series switches. The ULV4, ULV7, and ULV8 are available with 300-mm-long wire leads off the shelf and ready for installation. The wire leads are color-coded and compatible with a variety of connectors.

The ULV Series switches are UL-certified and IP67-rated for moisture and dust protection. Panel cutout sizes for the ULV4, ULV7, and ULV8 are 19 mm, 22 mm, and 25 mm, respectively. The ULV Series is available in SPDT or DPDT and offers a long operating life of up to 1 million life cycles (momentary) and 500,000 (latching).

All ULV models offer a ring lens style and multiple illumination color options. The ULV 4 also offers non-illumination or a choice of dot or power symbol lens style, as well as custom lens style options. The series is available in multiple functions, body and actuator finishes, LED color options including bi-color choices, and multiple illumination voltage options.

Honeywell expanded its Micro Switch series with an explosion-proof, snap-action sealed switch designed for household appliances as well as other hazardous locations where flammable gasses may be present. The V15W2 Basic Switch is designed for applications such as commercial appliances, valves and actuators, commercial refrigeration, ice makers, and HVAC/R (furnace, refrigeration, and ventilation). In a household refrigerator, these switches can be used to control the production of ice in a freezer or turn on an interior light when the door is opened.

The independent component testing organization DEKRA has certified the switches with an explosion-proof rating in accordance with the International Electrotechnical Commission System for Certification to Standards Relating to Equipment for Use in Explosive Atmospheres (IECEx System). This is the first low-cost sealed switch to receive the explosion-proof rating globally, according to Honeywell.

The switches can be used in Zone 2 hazardous locations, which are classified as an environment where a mixture of air and flammable gas or vapor is not likely to occur in normal, day-to-day operations.

The 5-A switches can also lower manufacturing costs by eliminating the need for extra protective shielding and redundant measures. The switches offer an ambient temperature range of –25°C to 85°C. Service life is rated at more than 1 million mechanical actuations.

Designed as a cost-effective and easy-to-install switch, the CSW-Series combination switch from Carling Technologies features a multi-position rotary, a three-position lever, and momentary pushbutton functions. The switches offer IP67 sealing protection and customizable legends and are compatible with a variety of connectors. Applications include commercial and recreational vehicles, as well as lawn and garden equipment.

Termination options include flying leads or several available connectors. The pushbutton circuit (momentary switch) is rated at 10 A max; and both the rotary control circuit (four positions) and the lever control circuit (three positions) are rated at 15 A max. The operating temperature range is –40°C to 85°C.

Schurter has expanded its MCS series of short-travel switches with a durable 16-mm variant with a low mounting depth. The Metal Line Switch MCS 16 is available with either a zinc die-cast or stainless steel actuator. The stainless steel version offers the option of individual laser marking. The switch housing, however, is always made of zinc die-cast.

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