Skip to main content

Rigid-Flex PCB Examples and Applications

In this post today, I’ll walk you through Rigid-Flex PCB in detail.

PCB (Printed Circuits Boards) are common in most electronics. They provide physical support and wiring area for socketed and surface-mounted electrical components.

PCBs are normally manufactured using composite epoxy, fibreglass, and other composite material. You’ll find them in digital and modern consumer electronics including LEDs, smartphones, digital cameras, radios, and TVs.

They range from a single layer, double layer, and multiple layers to flexible, rigid, and rigid-flex boards. In this section, however, we’ll only discuss rigid-flex PCB designs.

Let’s get started.

What is Rigid-Flex PCB?

Rigid Flex PCB boards are a combination of both rigid and flex circuits serving the purpose of each. High precision, substantial reduction of interconnects, and the freedom of packaging geometry make these boards a right match for the medical, military, and aerospace industries. These boards provide better quality control and higher component density and are designed to fit in hard-to-reach places.

The demand for portable electronic circuits is increasing every day. To blend both rigid and flex circuits into a single package, designers require cost-effective solutions that fill in the gap for using both rigid and flex circuits separately.

Example of a rigid-flex PCB

Moreover, these boards are compact, reliable, and efficient and are easy to handle compared to flexible circuit boards. The electrical components are normally soldered onto the circuit board to mechanically connect and electrically fasten it.

The rigid-flex designs are made up of multiple layers of flexible substrates which are further integrated into one or more rigid boards internally or externally based on the design of the application.

The rigid-flex circuits are made in a 3D space; the reason you can roll, twist and turn flexible board substrates as you like better to achieve the required design.

They provide greater spatial efficiency which makes them more challenging to design than the making of regular rigid circuit boards. While a rigid portion of the board offers strength and toughness, the flexible material removes the weight and space issues by offering a spatial degree of freedom.

Manufacturing of Rigid-Flex PCB:

The Rigid-Flex designs are very challenging and complex to design compared to developing traditional circuit boards.

The manufacturing process starts with designing PCB layout with the help of PCB designing software like DesignSpark PCB, Proteus, Eagle, or CAD. The software is easy to learn and anyone with little or no technical expertise can start working with them to create required PCB designs.

Rigid-Flex PCBs are manufactured when layers of rigid and flexible substrate materials are orderly stacked up with plated through holes offering a connection between layers.

The following image represents the basic structure of the rigid-flex design.

Basic structure of Rigid-Flex PCB

The reliability and strength of Rigid-Flex designs remove the intense heat and contact problems happened by connectors and harnesses.

Rigid-Flex PCBs have been around for a while and the manufacturing process of these boards has improved over time. Recently Rigid-Flex PCB manufacturing process uses glass fibre epoxy resin (FR4) as an external rigid board where solder mask is applied on the rigid layer to secure rigid circuit pattern. And the flexible substrate material is composed of polyimide (PI) double-layer board covered with copper where the acrylic film is used to secure flexible design pattern.

The following are manufacturing steps for developing rigid-flex circuits.

  1. Preparation of base material
  2. Generate circuit pattern
  3. Etch the copper laminate
  4. Precise mechanical drilling
  5. Through-hole plating
  6. Protect the boar with a cover plate.

The following image represents the manufacturing process of a 6-layer Rigid-Flex circuit design.

Manufacturing process of a 6 layer rigid-flex PCB

The Rigid-Flex board offers exceptional mechanical support and electrical performance and it can be bent into any shape due to the flexible material. The flexible substrate material not only provides flexibility but also shows remarkable dielectric stability that makes the board a perfect match for impedance control and high-frequency signal transmission.

Flexible substrate material comes with a high moisture absorption rate and a large coefficient of thermal expansion that ensures size tolerance accumulation, effective circuit pattern, drilling, layer up, and plating.

Rigid-Flex PCB Advantages:

Rigid-Flex designs offer the advantages of both rigid and flex circuits. The following are some benefits they provide for consumers and manufacturers.

Mechanical Stability:

The rigid-flex designs are composed of multiple layers of flexible substrates attached to one or more rigid boards, offering both stability and flexibility for installation in hard-to-reach places.

Dynamism:

The boards offer high precision, repeatability, and greater flexibility with packaging designs.

Connection Reliability:

The greater stability and polarity of these boards ensure safe and secure connections with other electrical components.

Withstand Extreme Environment:

Heavy electronic components come with shock and vibration issues during the execution of electrical projects. However, when soldering the electrical component with the rigid-flex designs you don’t to worry about these issues as the boards can withstand high temperature, heat, radiation, shock, and the extreme environment really well.

Rigid-Flex PCB Examples & Applications:

Rigid-Flex designs are used in scores of applications where you need to achieve the flexibility of the board without compromising the rigidity of the design.

You’ll find them in commercial, industrial and military applications. From digital cameras to cell phones to smart devices, they serve them all. Especially in the medical industry for developing pacemakers for their weight reduction, space, and flexible capabilities.

These boards support delicate and fragile wiring minimizing the connection issues and providing high reliability. Few solder joints are needed in rigid-flex designs that offer high connection reliability and make them useful for automobile and testing and measuring applications.

These boards are economical to manufacture as less logistical and assembly cost is required to develop these boards. As they are low weight and small in size, they are a perfect fit for bar code scanners and computer servers applications.

That’s all for today. Hope you’ve enjoyed reading this article. If you have any questions, you can pop your comment in the section below. I’ll help you the best way I can. Thank you for reading this article.

HI, I am a student of Electrical Engineering. I am currently working for an electronic store. I work at the electrical components there. I am learning many useful practical concepts there. On the other hand, I give online tuitions to some students of high school I love electrical and electronics devices and have a plan to have a Master's Degree in Electronics.
DesignSpark Electrical Logolinkedin