There are numerous types of flexible circuits that can be designed according to the needs of the customer. Given below are a few basic types:
- Single Sided Flex: This is a flex circuit that comprises a conductive layer of copper on one side of the PCB. Single sided circuit PCBs are ideal for dynamic applications, or equipment that require circuits with high levels of flexibility. They are known for their immense cost-effectiveness and ease of assembly. Single sided flex PCBs require one type of tooling. Hence, multiple copies of the PCB can be reproduced. They are the ideal solution for replacing wire harnesses.
- Double Sided Flex: An expansion on the singled sided flex PCB, the double sided flex comprises a conductive layer of copper on both sides of the PCB. Generally, the copper layers are connected to each other by Plate Through Holes (PTH) or vias. These holes or vias create an active circuitry between the layers. This is one of the most popular flex designs, and is known for its ease of manufacturing. Double sided flex circuits are designed to be light weight, and provide benefits of reproducibility.
- Multi-Layer Flex: As the name suggests, multi-layer flex circuits comprise more than two copper conductors. In a typical circuit, you will find up to 10 conductive layers. Like the double sided flex circuit boards, multi-layer PCBs are interconnected by PTH holes or Vias. The multi-layer design is ideal for applications that require PCBs with high density connectors, and the conductors need to be routed through a small area. The PTH mounting method helps create a more reliable solder joint.
- Rigid Flex Circuit Boards: This circuit is a combination of rigid and flexible circuits. The flexible layers are integrated with the rigid layers, and the PCB is assembled using PTH technology. The advantage of this type of circuit is that the combination of rigid and flex layers creates small interconnect areas, which reduces the chances of PCB failure in an application.
- High Density Interconnects: Also known as HDI, high density interconnects are flex circuit boards, which are designed to provide more technical solutions in terms of design, layout, and construction. Each HDI includes extremely dense flex circuitry with precise features and microvias. These help achieve the manufacturing of small sized yet powerful PCBs with increased functionality. HDIs are known to provide exceptional electrical performance, improved usage of advanced Integrated Circuits (ICs), and greater PCB reliability.
