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- November 12, 2022
- PCB knowledge
- (0)
- 05 mins
Rigid-flex PCB – what makes it be favored
It is said in an electronic industry report that rigid-flex circuit boards has up to $3,835 million market value in 2020 and are expected to raise almost 9.8% by 2025. That’s a considerable number, isn’t it?
But why are they so much used?
Because they are convenient and shock resistant. Besides, they gain traction in communication, space, electronics, and the medical industry.
In this article, you can find everything you want to know about rigid-flex PCB as follows. Let’s give a closer look at it!
Definition of rigid-flex PCB
A rigid-flex PCB, which combines a rigid PCB with a flex PCB, can better provide advanced benefits and enhance electronic machines’ performance, precision and rapid functioning. Here are components of a rigid-flex circuit.
1. Rigid PCB
It is hard and holds its shape with a non-flexible base. Such a base is helpful to avoid distortion of the circuit board, but it only works for some electronic devices.
2. Flex PCB
It can be bent and folded, making it a good choice for places where a hard circuit can’t apply.
Why combine both in a rigid-flex circuit?
Combining both strengths, a rigid-flex circuit can simplify the whole assembly process, use fewer welding spots, and leave more assembly space.
Why choose to use rigid-flex PCB?
Rigid-flex PCB is used extensively in electronic machines as it offers benefits over other types of PCBs. Have a look at some convincing benefits.
● Shock resistant
A sudden shock or heavy vibrations can break the PCB, but the rigid and flexible base of these PCBs is not affected by the shocks and vibrations, keeping the connection stable.
● Use less space
It is bendable to fit in any small space, avoiding the need for large spaces. The rigidness of the structure keeps the firmness to prevent damage.
● Affordable
Reducing the need for additional connectors, these circuit boards are highly money-saving. You can use multiple boards in a single machine without worrying about the cost.
● Quick assembling
A single assembly line required to complete the circuit board saves time and makes the process quicker.
● Convenient testing
A rigid-flex PCB does not need to go through multiple tests. Instead, single testing is enough. It’s because there are no additional components attached.
Rigid-flex PCB vs rigid PCB vs flex PCB
| Rigid-Flex PCB | Rigid PCB | Flex PCB | |
| Composition | A rigid-flex circuit contains layers of rigid and flex PCB. | It is composed of copper traces and paths, giving it rigidity. | A flex PCB contains a flexible polymer polyimide film. |
| Advantages | 1. Suitable to use in small areas with its flexibility, avoiding distortion. 2. It usually does not have additional components, making it easy to assemble. | Help to avoid distortion of the circuit board. | 1. A flex PCB does not break when bent, as it is highly elastic. |
| Disadvantages | Some buyers may feel it is more expensive than other PCBs. | 1. Only works for some electronic devices. 2. Too rigid, making it unfit for less space. | 1. If bent too many times, the flex PCB can scatter. 2. Sometimes, it can’t hold its shape and distorts. |
| Applications | Satellites, mobiles, MRI machines, automobile screens, | Handheld monitors, communication systems, radio communication systems, | OLED displays, medical wearables, and LED car lights. |
Which areas can rigid-flex PCB be used?
You might have never realized, but the mobile or laptop you are holding right now might not work efficiently without a rigid-flex PCB, as it helps add reliability to the complicated structure of the laptop or mobile phone. Curious about rigid-flex printed circuit applications? Let’s have a look.
1. Medical equipment
Medical equipment is highly precise, needing a space-saving yet reliable PCB that fits with a flexible design. X-ray, ultrasound, and MRI machines use a rigid-flex circuit board.
2. Communication Industry
Satellites, mobile phones, drones, PCs, AI chips, and laptops use rigid-flex printed circuits because their staunch connections give better signal strength.
3. Automobiles
Control systems and LCD modules in automobiles use rigid-flex circuits because of their shock-resistant abilities.
Production process of rigid-flex PCB
The selection of materials is the first step requiring attention. As a rigid-flex PCB contains rigid and flex PCB properties, two different materials are needed, including polyimide for the flex layer and FR4 for the rigid layer.
Drilling all parts together to complete the structure of the rigid-flex circuit.
A PCB must conduct electricity effectively and should be plated with copper. Some buyers do not require copper plating, so manufacturers can skip this step.
Now is the time to print the circuit pattern. A UV light is hit on the PCB, printing the pattern using the photo-resistive film.
An alkaline solution is used for the process of etching. Etching is a process where copper plating is removed from the desired circuit.
Now, the circuit board needs inspection with multiple techniques. The most commonly used is automated optical inspection (AOI). It involves taking pictures of the board from various angles to detect errors.
A solder mask of the required color is added to the PCB. Then the silk screening is done, labeling the critical components. As a final step, a surface finish is applied to prevent oxidation.
Hurdles of rigid-flex PCB
Considerations on rigid-flex PCB design
When designing a rigid-flex PCB, it is essential to consider some factors to ensure its proper functioning. Have a look at those considerations.
1. Accurate registration
The accurate registration between the rigid and flex layers is vital. If the registration is imperfect, it creates issues in the alignment of both layers during assembly. Alignment holes are used to ensure proper registration.
2. No voids
There must be no voids in solder joints. Staggered vias are used to distribute the heat, avoiding the formation of gaps in the solder joints. Further, copper pillars are also used to resolve the void issue.
3. Reducing distortion
Larger boards can easily distort shape affecting functionality. To resolve this issue, stiffeners are attached below the PCB. They help to add solidness to the structure, saving it from distortion.
Conclusion
If you want to save your pocket and benefit from multiple circuit boards in one place, reducing the mess of too many circuit components, Rigid-flex PCB can help you. The combination of these two types of PCBs, being flexible yet rigid, adds even more characteristics.
A high-quality PCB is essential for better working electronic machines and devices. Therefore, you must choose one-stop manufacturers for getting your bulk orders at competitive prices.
Get your Quote in IBE to receive your order as soon as possible.
