Rigid-Flex PCBs

A rigid flexible board is one that integrates a rigid board and a flexible printed circuit board (FPC).
This page describes rigid flexible substrates.

What are Rigid-Flex Printed Circuit Boards?

Source: Sanyo Corporation Official Website
(http://www.k2p.jp/manufacturing/flex_rf.html)

A rigid-flex printed circuit board combines and integrates a rigid printed circuit board and a flexible printed circuit (FPC) to create a structure that leverages the advantages of each. The structure of a rigid-flex PCB consists of a rigid section and a flex section. Components are mounted on the rigid section, while the flex section is designed to bend.

The rigid part consists of a rigid layer for mounting components and a flexible layer for three-dimensional wiring, and each layer is connected by through holes. The flex section consists of only a flexible layer, which is separated by one or two layers to maintain flexibility. The manufacturing process is also complicated due to the complex structure.

Therefore, the unit cost is higher compared to rigid PCBs and flexible PCBs (FPCs).

Differences from Flexible Printed Circuits

Flexible printed circuits (FPCs) are primarily required to function as cables. Their component mounting capability is inferior to that of rigid PCBs. Therefore, they are generally used in combination with rigid PCBs that mount electronic components.

On the other hand, with rigid-flex PCBs, where the rigid PCB and the flexible PCB (FPC) are integrated from the beginning, there is no need to prepare a separate rigid PCB. Connectors to connect the rigid PCB and the flexible PCB (FPC) are also unnecessary.

Cost and Design Constraints

When using flexible PCBs (FPCs), rigid PCBs, and connectors, design constraints such as space limitations may arise. However, when using rigid-flex PCBs, these design constraints, including space limitations, can be minimized.

While rigid-flex PCBs have a high unit cost, it is not always accurate to say they are expensive when considering the design constraints, the cost of necessary boards and components, and the costs associated with the mounting process.

Recommended Applications

Because connectors are unnecessary for connecting between boards, they are ideal for applications that dislike noise generation and require thinner, smaller, and higher-density designs.

They are commonly used in digital devices with many high-performance parts and high-functionality components, as well as small mobile devices.

Summary

Rigid-flex printed circuit boards offer various advantages compared to using rigid PCBs and flexible PCBs (FPCs) separately.
If you need to achieve thinner, smaller, and higher-density electronic devices, consider adopting rigid-flex PCBs.

See the List of Manufacturers
Handling Flexible PCBs