Slide Switches SMT & miniature Slide Switches-SHOUHAN Technology
Slide switches are mechanical switches using a slider that moves (slides) from the open (off) position to the closed (on) position. They allow control over current flow in a circuit without having to manually cut or splice wire. This type of switch is best used for controlling current flow in small projects.
There are two common internal designs of slide switches. The most common design uses metal slides that make contact with the flat metal parts on the switch. As the slider is moved it causes the metal slide contacts to slide from one set of metal contacts to the other, actuating the switch. The second design uses a metal seesaw. The slider has a spring that pushes down on one side of the metal seesaw or the other.
Slide switches are maintained-contact switches. Maintained-contact switches stay in one state until actuated into a new state and then remain in that state until acted upon once again.
Depending on the actuator type, the handle is either flush or raised. Choosing a flush or raised switch will depend on the intended application.
Slide switches may have a variety of features that best fit the desired application.
Pilot lights are used to indicate whether the circuit is active. This allows operators to tell at a glance if the switch is ON.
Illuminated switches have an integral lamp to indicate a connection to an energized circuit.
Wiping contacts are self-cleaning and usually low-resistance. However, wiping creates mechanical wear.
Time delays allow for the switch to automatically turn a load OFF at a predetermined time interval.
Pole and Throw Configurations
Pole and throw configurations for slide switches are very similar to those of pushbutton switches. To learn more about pole and throw configuration visit the Pushbutton Switch Selection Guide.
Most slide switches are of the SPDT variety. SPDT switches should have three terminals: one common pin and two pins which compete for connection to the common. They are best used for selecting between two power sources and swapping inputs.
Another common pole and throw configuration is DPDT. The common terminal is usually in the middle and the two select positions are on the outside.
There are many different terminal types for slide switches. Examples include: feed-through style, wire leads, solder terminals, screw terminals, quick connect or blade terminals, surface mount technology (SMT), and panel mount switches.
SMT switches are smaller than feed-through switches. They sit flat on top of a PCB and require a gentle touch. They are not designed to sustain as much switching force as a feed-through switch.
Panel mount switches are designed to sit outside an enclosure to offer protection to the slide switch.
Slide switch sizes are usually described as subminiature, miniature, and standard.
Electrical specifications for slide switches include: maximum current rating, maximum AC voltage, maximum DC voltage, and maximum mechanical life.
Maximum current rating is the amount of current that can run through the switch at one time. A switch has a small amount of resistance, between the contacts and because of that resistance; all switches are rated for a maximum amount of current they can withstand. If that current rating is exceeded the switch may overheat, causing melting and smoke.
Maximum AC/DC voltage is the amount of voltage the switch can safely handle at one time.
Maximum mechanical life is the mechanical life expectancy of the switch. Often a switch‘s electrical life expectance is less than its mechanical life.