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Rigid Flex PCB vs. Traditional PCB: Making the Right Choice

Rigid Flex PCB

Innovation is riding up the call for smaller and extra flexible technologies. Rigid-flex PCBs combine the advantages of both rigid circuit boards and flexible circuit boards: they are stable at the rigid parts where many components are assembled and flexible at the parts that need to be bendable! Rigid-flex technology has a fascinating range of benefits, but in addition, it poses some thrilling demanding situations in production and usage.

The phrase “PCB” is often used to call rigid printed circuit boards. However, the term “PCB” might also be used for flexible or rigid PCBs. PCBs which are flexible are every so often known as “flexible circuits” (PCBs). They are mostly called flexible PCBs, flexible circuit boards. In recent times, flexible circuits have been widely used. Because they’ll be fashioned into endless exceptional configurations by way of folding, twisting, and bending. Connecting several mechanical and electrical components by one single PCB is the ultimate goal of each rigid and flexible PCB.

In this article, we talk about the difference between traditional PCBs and more advance rigid-flex PCBs. 

Table of contents: 

  1. Introduction of rigid PCBs, flex PCBs and Rigid-flex PCBs
  2. What differences exist between rigid-flex PCBs and conventional rigid PCBs?
  3. Effectiveness of the use of rigid-flex circuit boards
  4. What difficulties arise in rigid-flex circuit boards?
  5. How to decide between traditional PCB and rigid-flex PCB?
  6. Conclusion

Introduction of rigid PCBs, Flex PCBs and Rigid-flex PCBs

Features of rigid PCBs

The shape of a rigid PCB cannot be changed. The board’s electricity and stiffness come from the strong and rigid substrate that acts as its foundation. The material commonly used as a substrate for rigid PCB is FR4. Single-sided, double-sided, or multilayered rigid PWBs are all viable. Rigid printed circuit boards cannot be bent or folded into a different shape after it is produced.

Applications of rigid PCBs

GPS gadgets, desktops, laptops, drugs, smartphones, MRI systems, X-ray machines, heart video display units, CAT scans, temperature sensors, manage tower instrumentation, and different devices all appoint rigid PCBs.

Traditional rigid PCB

Traditional rigid PCB

Features of Flexible PCBs

Flex PCBs are more flexible than rigid PCBs, and they can be folded. Flexible PCBs may be single, double, or multilayer in format, much like rigid PCBs.

However, flexible PCBs have numerous benefits over rigid PCBs. The most superb function of these benefits is their flexibility. This implies that they can be encircled round corners and folded over edges. Since a single flexible PCB can be utilized to cover areas that might need many rigid PCBs, and flexible PCBs are also thinner and lighter, it results in weight cost savings.

Applications of Flex PCB

Flexible circuit boards, or flex PCBs, are applied within the manufacturing of natural light-emitting diodes (OLEDs), LCDs, flex sun cells, motors, cell phones, cameras, and different state-of-the-art electronic items.

  • Functions of rigid-flexible PCBs

A rigid-flex PCB is a hybrid circuit board that can be folded or continuously flexed by combining additives from rigid and flexible circuit boards. A rigid circuit board joined to a flexible circuit board is the primary form of rigid-flex printed circuit board.

  • Applications of rigid-Flex PCBs

Compact layout and light-weight construction make rigid-flex boards a remarkable preference for a ramification of programs within the industrial electronics, medical devices, telecommunication applications, IoTs, robotics and even aerospace industries.

Rigid-flex printed circuit board

Rigid-flex printed circuit board

What differences exist between rigid-flex PCBs and conventional rigid PCBs?

Conventional rigid printed circuit boards are not intended to bend or flex; they may be made mostly with FR-4 materials. Rigid-flex PCBs, on the other hand, are made so that they will bend and flex in positive locations. The usage of rigid-flex printed circuit boards (PCBs) has numerous benefits over conventional rigid boards. Flexible PCBs use a flexible material, which includes polyimide. Flexible circuits can tolerate vibration, release heat, and fold up into a spread of configurations way to a flexible basis. Compact and resourceful electronics are using flex circuits increasingly because of their structural supply. Nowadays, all electronic gadgets—from tiny wearable devices to extremely complex radar systems—are made to be lightweight, flexible, and compact. In huge element, rigid-flex PCBs assist in obtaining those necessities.

Rigid printed circuit boards offer several benefits:

  • Optimized Cost: conventional rigid PCBs are a desired alternative for many trendy digital applications due to the fact they’re generally much less costly to fabricate.
  • High Production: traditional rigid PCBs may be mass-synthetic economically and correctly when electronic items are created in large portions.
  • Geometric elements: traditional rigid boards are good enough for applications where regular rectangular or square PCBs suit nicely within the enclosure.

Rigid flexible circuits provide a number of benefits:

  • Bendability: Bendable printed circuit boards perform properly in conditions requiring regular bending or flexing. They can squeeze into small regions and tackle a variety of forms.
  • Lightweight: because flexible PCBs are lightweight, they’re beneficial in programs wherein weight is a factor, such as portable electronics and drones.
  • Reduced space necessities: flexible PCBs have the gain of keeping area in applications wherein compactness is vital.

Effectiveness of the use of rigid-flex circuit boards

  • Space efficiency: due to the fact that rigid-flex PCBs do no longer require connectors and decrease the need for added interconnects, they may be highly space-green. they may be best for small, intently packed electronic devices considering the fact that they may be twisted or folded to healthy in restrained locations.
  • Reliability: Reliability is expanded when there are fewer connectors on the grounds that there are fewer viable points of failure. Connector-associated troubles are less commonplace with rigid-flex PCBs.
  • Increased Durability: appropriate for use in antagonistic settings, rigid-flex PCBs are made to bear mechanical stress, vibrations, and temperature changes.
  • Reduced assembly prices: due to the fact that rigid-flex PCBs have fewer additives and require fewer manual assembly approaches, they often bring about decreased assembly costs, in spite of their preliminary manufacturing complexity.
  • Complicated Geometries: the usage of rigid-flex generation makes it viable to create complex. And the final assembly process is also easier. 
  • Cost saving: One rigid flex PCB can replace several rigid PCBs and flexible PCBs, and a lot of cables and connectors can also be omitted. So a lot of costs may be saved. 
All kinds of PCBs

All kinds of PCBs

What difficulties arise in rigid-flex circuit boards?

Complicated layout rules: as compared to rigid PCBs, rigid-flex PCBs often have complicated layout guidelines. Bend radius, layer stack up, and fabric obstacles are only some of the mechanical and electric specs that designers ought to be aware of whilst operating with rigid and flexible sections.

Bend Radius considerations: selecting the proper bend radius for the flexible sections is an important part of the rigid-flex layout procedure. Deciding on an excessively small bend radius can result in sign integrity troubles and mechanical failure.

Base material selection: it’s essential to pick out the ideal materials for the PCB’s flexible and rigid sections. The bendability of the base flexible material will affect the durability of the rigid flex circuit boards greatly. The thermal expansion coefficients of diverse materials vary, which might cause reliability troubles as temperatures alternate. The most famous rigid flex material is polyimide laminate, which is produced by Dupont.

PCB layup: The designer needs to be familiar with rigid-flex circuit boards. Usually, we can only place electronic components on the rigid part, and no components on flexibles. And also we need to keep enough distance between two rigid parts. 

How to decide between traditional PCB and rigid-flex PCB?

Generally speaking, traditional PCBs are appropriate for consumer electronics or bigger devices like computer computers and televisions, but rigid flexible circuits are wished for more advanced and smaller gadgets like wearable generation and cell phones.

Whether we should use a traditional PCB or rigid-flex PCB, we should consider the following points:

Usage: Firstly we need to understand how to use this application. Do we need to bend the devices or not? If yes, we definitely need to use flexible PCBs. If there are many advanced electronics needs in a small space, like ICs and BGAs, then we had to use a rigid-flex design since normal flexible circuit boards are not very suitable for complex designs. 

Cost considerations: We should always think about cost. If it is cheaper to use one rigid-flex circuit board to take over several rigid PCBs and flex PCBs, then we can use rigid-flex design in our applications. But if the rigid-flex circuit is more expensive, then we should use traditional circuit boards and assemble them together. 

Reliability: For some applications, we need very high reliability. Using rigid flex PCB can provide better reliability than using cables and wires. So we had better use rigid-flex circuits. 

Conclusion

Rigid-flex printed circuit boards have several advantages compared to traditional FR-4 PCBs. The primary reason is that it can be bent and even folded in usage. Also, because of its lightweight and compact layout, the packing is smaller. It can be made to fit into tight spaces, which greatly aids in the downsizing of products. As it integrates each flexible and rigid PCB, there are fewer interconnects needed. So, it is a more robust production technique that can be used to make it proof against surprise, vibrations, and different harsh industrial situations. Besides, it suggests exceptional resistance to robust chemical substances, lubricants, and UV and radiation exposures. 

In a nutshell, the rigid-flex circuit board is a more advanced circuit board, which is widely used in the aerospace, manufacturing, creation, energy technology, consumer, and automotive industries because of all of the aforementioned features.

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