Flexible Printed Circuits
A flexible printed circuit is a circuit board that has the ability to bend or twist. Flex circuits are used in a variety of electronics, including medical devices, handheld computers, printers, and scanners. They are also used in vehicles to support backup cameras, sensors, and GPS software. While both rigid and flexible circuits perform the same electrical function, they differ in mechanical and structural design.
The primary distinction is that a regular flexible printed circuit cannot be bent, whereas a flexible circuit can. This requires different manufacturing processes, materials, and designs. It is important to understand these differences before designing a flexible printed circuit, as it can influence the overall cost of a project.
One major difference is the layer count of a flex circuit. A flex circuit can be single-sided, double-sided, or multilayer. Single-sided flex circuits are the simplest and least expensive option. Multilayer flex circuits offer greater flexibility and routing density.
Standard Sizes for Flexible Printed Circuits
Another difference is the type of base material and conductor used for a flex circuit. A flex PCB must be made of a material that can withstand bending and that provides thermal resistance. This material is typically FR4, but other materials such as polyimide (PI) or aramid may be used. In addition, the flex circuit must have sufficient copper to carry signals over long distances.
It is also important to choose the right thickness for the flex circuit. The thinner the copper, the more likely it is to break or deform during bending. This is because the copper will not have as much strength as thicker layers of copper. The minimum bending radius for a flex circuit depends on its intended use, and it is important to work with an experienced fabrication house to ensure that the flex circuit meets the required specifications.
Finally, it is important to consider the number and location of vias on a flex circuit. It is best to avoid placing vias in flex areas, as they can be difficult to place components and route traces on. In addition, it is important to minimize the number of holes in a flex circuit, as this can lead to signal interference.
In general, a flex circuit can save time and money in production by eliminating the need for multiple rigid boards or wire harnesses. It can also reduce component inventory, simplify assembly, and improve product reliability. For example, a rigid-flex circuit can replace multiple individual rigid circuit boards within a product by connecting the rigid sections with a flex section in a panel. This can lead to significant inventory and cost savings for the manufacturer. In addition, a flex circuit can reduce the weight of a product by replacing heavy wires and connectors. This can help to increase consumer satisfaction and make the product easier to handle.