Flex and Rigid-Flex circuits give the ability to design circuitry to fit the device, instead of building a device to fit the circuit board. They are designed for the rigors of aerospace, medical and military applications, with dependable reliability.
Unlike regular printed circuit boards (PCBs) flexible circuit board can fit where no other solutions are able. You can even save more space by replacing a wired assembly with a Flex Circuit(s). Flex designs are typically only 10% the space and weight of wired solutions. There is also an increase in tighter bend capabilities. There may even be opportunity to replace multiple PCBs, connectors, etc. with a single rigid-flex unit. As far as component/connector assembly is concerned Flex PCBs accepts any component or connector that can be assembled to a Rigid PCB. Additional options that are available include ZIF connectors, crimped contacts, and direct solder. Flex circuits also perform well in harsh environments. Extreme temperature applications can run between 200 + Celsius and flex provides better heat dissipation than Rigid PCBs. Flex circuits also have excellent resistance to chemical, radiation, and UV exposure.
As the principle elements of a flex circuit assembly, the flex circuit and components should be properly prepared. One thing that most plastic components and flex circuits have in common is that they take up moisture. This means that they must be protected from humid environments. Otherwise, they must be pre-baked to prevent explosive out gassing of trapped moisture and the creation of defective conditions such as cracked components or blistering and delamination of the cover layer.
Types of Flex Circuits:
Single-Layer Flex Circuit
It refers to IPC 6013 – Type 1: It has one conductive layer, either bonded between two insulating layers or uncovered on one side. It can have Stiffeners, pins, connectors, components, etc.
Double-Sided Flex Circuit
It refers to IPC 6013 – Type 2: It has two conductive layers with an insulating layer between; outer layers may have covers or exposed pads. It has plated through-holes provide connection between layers. Again, Stiffeners, pins, connectors; components can be there as optional.
Multi-Layer Flex Circuit
It refers to IPC 6013 – Type 3: Three or more flexible conductive layers with flexible insulating layers between each one; outer layers may have covers or exposed pads. Plated through-holes provide connection between layers. It can have possibilities for Controlled impedance.