Flexible Circuit Boards
Flexible circuit board or flex circuit board is a conductive connection circuit with a certain degree of flexibility that can be bent close to folding. The circuit is wrapped in a flexible film made of an insulating polymer material.
As shown in the picture below, the layer which contains the copper wires (the circuit) is wrapped in both sides with an adhesive insulator, and then the outer layer made of environment force resistant plastic is placed on the adhesive material layer.
In this case, we have a single layer board. Multiple layer boards can be made as well using about the same configuration. There are various types of flexible circuit boards. Four of common types are listed below:
Single-sided – are flex boards which offer access only to one side, the other side is closed in inaccessible plastic cover.
Double-sided – contrary to the previous type, double-sided flex circuit board provides access on both sides of the circuit.
Multilayer – is made of more than one layer of copper wires, and has no significant loss of flexibility in using multilayer.
Rigid flex board – is the most complicated type of flexible boards. It consists of a number of non-flexible board connected with the flexible circuit board. This is the technology largely used in flexible smart phone devices.
Flexible circuit boards offer a wide range of applications, from consumer electronics to medical devices. The most common purpose for using this board type is the need for the limited space and enduring mechanical pressure, such as vibration or bending. The main drawback of using flexible boards instead of rigid PCBs is the cost and complexity of the fabrication process. When the flexible board is the part of the product design, its production line automation will become more difficult.