Membrane Switch Connector Options
One consideration for your membrane switch design is how to connect the membrane switch with the brains that control your product. Basically, connectors connect the keypad and the device it will control. Connectors consist of a contact device and a molded plastic housing, but connectors are certainly not something to choose lightly. Sometimes, knowing which connector to use for an application can be difficult. You need to think about ways to accommodate connector durability and minimize unwanted space when deciding how to terminate your membrane switch.
Flexible membrane switches are connected by a flexible tail that is cut from the circuit material. This flexible tail can be connected to a circuit board with a variety of single row connectors designed for flex circuits. Or, the tail can be designed to interface with a Zero Insertion Force (ZIF) connector. Typically, the lowest-cost interconnect is a ZIF connector. Flex circuits may also be terminated with solder tabs that can be directly soldered onto the circuit board.
Basic Connector Options:
- Bare tail: interfaces to .100” center LIF or ZIF style connector
- Female connector: Plain – interfaces to a .100” center, .025” square posted header
- Female connector: Latching – interfaces to a .100” center latching header
- Male connector: Plain – interfaces to a .100” center female header
- Male connector: Latching – interfaces to a .100” center latching header
- Solder tabs – .100” centers and can be directly soldered to PCB or wires
ZIF connectors have no physical connector on your membrane switch and rely on a receptacle connector that is available from numerous manufacturers. It is important to choose a ZIF connector that is suggested for membrane switches and to keep in mind that smaller pitches are available in polyimide flexible printed circuits only.
ZIF connectors are increasingly common in several applications, especially when connecting to a small display or keyboard. ZIF connectors meet a range of requirements including low profile, lightweight, secure, and removable connections. ZIF connectors are appropriate for more complex applications and allow for higher levels of integration. For ZIF connections, the connector system is not on the membrane tail, but on the PCB. The tail of the circuit is inserted into the ZIF connector to create the contact, and a stiffener is laminated under the tail to ensure stability and maintenance of the electrical contact. ZIF connectors may have anywhere from 2 to 30 positions on a single row, and distances of between 1mm and 2.54 mm are available.
Keep in mind that ZIF connections degrade with insertions, so the maximum number of insertions should not exceed 10 cycles. It’s also important to remember to take care when placing the tail die but in relation to the printed traces, since resistance in the circuit may increase in spacing of less than 1mm where the circuit traces are thinner.
Male, Female, or Solder Tab Housings:
These types of connectors are considered to be more reliable against heavy shock and vibration. They also are known for more ease of assembly. With a much larger connection, male, female, and solder connectors have pins crimped to the circuit and are available with many different housing features. The tail pitch is available in .100” spacing.
Crimpflex Connecting System by Nicomatic
Nicomatic Crimpflex connectors conform to Berg, Molex, and Amp membrane switch connecting specifications by utilizing common pins in a specific housing to meet connection requirements. The Crimpflex crimping presses are dedicated to the manual and pneumatic crimping of male and female contacts and are known for their reliability, ruggedness, simplicity of use, speed, and precision. The Crimpflex contacts ensure mechanical retention and electrical contact by piercing the conductor in six points. The contacts are available in male, male solder tab, and female versions; the female contacts are selective gold or tin-plated. Crimpflex connectors’ standing housings are available in the OF series, which fits with the most common interfaces, or the OM series, which interfaces with cables and comes with an locking system that can be oriented to meet your specifications.
Crimpflex connectors comply with rigorous electrical and mechanical requirements and provide exemplary connection, especially in applications where high vibration is expected. They are mounted by installing the pins on a circuit tail and assembling it into a molded plastic housing. The crimping pierces the conductor, ensuring mechanical retention at two points and electrical contact at four points, with the lowest possible contact resistance. Designers and engineers may specify whether they want low or high insertion force or locking versions.