Judging by the way some users handle portable consumer electronics, it’s fair to say that they can be considered harsh environment devices. Cell phones, MP3 players, tablets and other portable electronic devices have become ubiquitous personal and professional tools that are used constantly throughout the day and not with the gentlest of care. As a result, switch manufacturers must create new rugged miniature switches that combine significant space and weight reductions with ruggedness and long operating lives.
These miniature switches must function in the same reliable, consistent manner as the more substantially-sized industrial design, all the while maintaining optimum functionality, performance and extended lifespans. Switch manufacturers that offer value-added services, including manufacturing modules and custom assemblies, can deliver complete electromechanical solutions that not only meet the size and performance requirements, but can also withstand the elements like vibration and shock.
Double Action Switches
Low-profile double action, double-tactile switches are now being designed into handheld and portable electronic devices that require specific ergonomics, such as the focus and shutter release on a digital camera or mobile phone. These switches provide fast, repetitive action in these type of handheld consumer electronics applications. The increased functionality from miniature double-action, double-tactile switches enables designers to eliminate components from their designs, decreasing the weight and size of their end product.
Some miniature double action, double-tactile switches available on the market today are offered in package sizes as small as 3.7mm x 3.0mm x 0.95mm, including the height of the actuator. Standard pushbutton switches have a typical life cycle of around 30,000 actuations.
Ultra-miniaturized nano switches improve upon traditional switch designs. Unlike detect switches or pushbuttons, ultra-miniaturized top-actuated nano switches are smaller and more flexible by design. The NanoT Series from C&K, for example, employs small domes between one and two millimeters within new types of switch structures, representing significant size reductions over micro switches. These truly miniature switches measure 2.2mm x 2.0mm x 0.5mm. A longer version at 3.0 x 2.0 mm can also be available with KXT3 series. Ultra-miniaturized top-actuated nano switches usually provide multiple actuation forces between 1.0N and 2.2N with a 30% tactile minimum. Nano switches also typically provide an operating life of 300,000 cycles with an IP68-rated sealing. The ultra-miniaturized top-actuated nano switches deliver an extended lifespan and rugged design through the use of advanced films and strong redesigned bases, making them an ideal choice for designers working with limited space, but cannot afford to sacrifice switch or signal quality.
Ultra-miniature nano switches have become increasingly popular for behind-the-ear hearing aids, where all components must be small, yet function consistently and effectively. These switches help designers reduce the overall size of the hearing aid, thereby increasing user comfort and reducing the visibility of the device behind the ear.
Pedometers also benefit from switch miniaturization through a reduction in the overall weight and assembly of the wrist portable version. The pedometer has to work under harsh conditions and keep working for a high number of actuations, making reliability the top concern when considering a new switch design.
Tactile switches are inherently smaller and more flexible than many other switch technologies. These types of switches afford the capability of multiple mounting and actuation configurations, providing greater flexibility along with the ability to configure the switch for application-specific needs. Typical tactile switches can reach a range of 100,000 and 600,000 actuations, respectively, with a target goal of up to 1,000,000 for future tactile switch designs. Their long operating life is due in part to a resistance to shock and vibration of 10 to 500Hz and an operating temperature of -40˚C to +85˚C.
Scroll switches are a popular solution in shrinking electronics because of their miniaturized packaging and rugged functionality. Scroll switches typically maintain longer lifespans than pushbutton switches because there are fewer aspects of the switch that can be comprised due to tactile interference. Scroll switches typically feature life cycles of more than one million central select actuations and one million rotation actuations (each direction), with a maximum contact resistance of 300mΩ and inherently strong shock and vibration protection. Conventional switch designs can typically only reach 200,000 cycles.
Designed specifically for applications where height or surface area are restricted, sub-miniature slide switches combine a low-profile with an extended electrical and mechanical life. Available in glass-filled housings with 4/6 nylon (UL94V-2) actuators, these sub-miniature slide switches feature a stainless-steel cover and return spring to allow for a 100,000-cycle standard lifespan. Measuring as small as 2.6mm by 7.6mm, the surface-mount switches are ideal for a range of applications, including on/off touch screens, handheld games, remote controls and instrumentation applications.
Side-actuated DIP switches combine miniaturization and high-reliability for logic switching within computers. The DIP switches’ combination of numerous mounting options and a low board-mounted profile increases available PCB space and offers a uniquely flexible solution for design engineers. These half-pitch DIP switches feature a dual bifurcated wiping action that ensures reliable contact. When mounted horizontally, the side-actuation mechanism provides visual confirmation of the on/off status, ideal for logic switching grids where multiple signal paths must be manually routed via switchboards.
These miniature DIP switches measure as little as 4.16mm above the PC board and feature a 1.28mm layout pitch. Process-sealed for surface mount wash processing, the device features gold over nickel over copper alloy contacts and a UL 94V-0 PPS flame retardant housing.
Modules and Assemblies
To provide a complete solution, switch manufacturers can also design and manufacture modules and assemblies that meet customer-specific application requirements. Switch manufacturers with engineering expertise can quickly and efficiently integrate switches and electronics (from simple to complex circuitry) into attractive and functional packages that assemble neatly into customers’ finished products. These value-added services can also include manufacturing inserts and injection molded parts, stamped parts and lead frames to provide a one-stop-shop for customers.
Advanced switch manufacturers can not only refine a switch’s sound (tunability), feel (haptics), and control (interface) within assemblies and modules to suit customer preferences, but also offer a wide range of additional build options, including decoration, lighting, connections and sealing. Incorporating custom graphics, logos, textures and finishes onto critical surfaces also provide a benefit to the end product. Using two-shot molding, paint and laser etch, pad printing and plating, these decorative solutions are designed to stand out and fit easily into a portable device, such as an iPhone or iPad. Lighting options include backlight accenting and light piping to enhance a product’s appearance and practicality to a design.
Miniaturization and reliability are two of the more important considerations in the consumer device market today. The development of innovative miniature switches has helped enable design engineers to continue this trend. Because electrical and mechanical specifications in consumer applications are critical – tolerances are extremely tight and product profiles are small – and development cycles and lead time requirements are short, switch manufacturers that develop flexible and reliable devices while also adding value by manufacturing modules and assemblies are at a distinct advantage for design wins.