Considerations for FPC and PEMS designs need an understanding of how to interface to the brains that control your product. Basically, connectors connect the circuitry and the device it will control with considerations of connector costs, size and durability, and remembering when mating headers are involved.
FPC and Printed Electronics circuits 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 or double row connectors designed for flex circuits. Or, the tail can be designed to interface with a Zero Insertion Force (ZIF) or Low Insertion Force (LIF) connector. Typically, the lowest-cost interconnect are these ZIF or LIF connectors. Circuits may also be terminated with solder tabs that can be directly soldered onto the circuit board.
Basic Connector Options (at 0.100″ or 0.050″ centers):
- Bare tail: interfaces to LIF or ZIF style connector
- Female connector: Plain – interfaces to a square posted header
- Female connector: Latching – interfaces to center latching header
- Male connector: Plain – interfaces to a center female header (0.100″ only)
- Male connector: Latching – interfaces to a center latching header (0.100″ only)
- Solder tabs – can be directly soldered to PCB or wires
ZIF & LIF Connectors
ZIF and LIF connectors have no physical connector on your circuit and rely on a receptacle connector that is available from numerous manufacturers. Some offer locking and strain relief capability that involve cutting tail shapes to properly engage. Keep in mind that smaller pitches are available but due to the limitations of screen printing are limited to FPC designs. Note anything finer than 1.25mm is usually limited to FPC. Alignment and insertion/extraction limitations should be noted.
Crimp Male, Female, or Solder Tab Connections:
These connector systems tend 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 0.050″ and .100” spacing.
There are a handful of crimp connection styles, some offering different design recommendations such as pad size or thickness of material. A determination of interface will usually direct proper solution and circuit designers will know proper specifications to make certain the chosen connector will crimp properly to the circuit.
Industry standards allow for cross mating of products but care should be taken for supplier specific polarizing, locking and with some care latching styles. An example is that both Tyco and Molex designed latching style connectors that are not necessarily compatible.
Phil Heft – PEMS Specialist; firstname.lastname@example.org