The growing NexLogic customer demand for the design and manufacturing of wearables and Internet of Things (IoT) is dramatically expanding our flex circuitry design and manufacturing experience base. Not long ago, flex circuitry was considered a required item for a particular PCB design. However, today, it is taking center stage and is mainstream, not only for wearables, but also for other small PCB applications.
Flex circuits are light and thin electrical circuits targeted at applications that are mostly confined to small spaces and contoured shapes. Conductive strips of metal – usually copper – are encapsulated with insulated dielectric material, typically polyimide or solder mask or a combination of both.
Polyimide is an excellent insulator that allows the circuit to bend and resist contamination and corrosion. Plus, it withstands high temperature ranges so that flex circuits using polyimide insulated dielectric material can effectively undergo high temp thermal profiles during assembly.
An example of a multi-layer flex circuit is shown in Fig. 1.
Let’s take a quick inventory of what’s important when it comes to flex circuitry. Three basic characteristics are:
- Biggest advantage is it significantly reduces the number of multiple interconnects.
- It bends every which way and can be used for any number of shapes and sizes to connect with parallel boards.
- It reduces shape, weight, and size of virtually any small PCB application.
Aside from this trio, flex circuits come in many shapes, forms, and types. They can use through-hole or SMT components. Different types of combinations can be used; flex and rigid PCBs can be used together for certain applications especially in Mil/Aero arena.
Flex circuits have a variety of different bend and twist curvatures. They come in different materials, such as polyimide or Kapton, and flex circuits come in different thicknesses to suit given applications.