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Rigid-Flex PCB

A rigid-flex PCB combines the advantages of flexible and stiff PCBs. It is made up of many laminated layers of rigid and flexible circuit materials. In this article, we will go over the fundamentals of rigid-flex PCB, how to build it, and how to choose the best PCB manufacturer for your rigid-flex PCB fabrication requirements.

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What is a Rigid-Flex PCB?

Printed circuit boards that are stiff & flexible are intended to solve problems and take the place of rigid PCBs. These circuit boards are a combination of stiff and flexible circuits, as the name implies.

A rigid-flex PCB combines the advantages of both flexible and standard stiff PCBs. It is constructed of several laminated layers of stiff and flexible circuit materials. This makes it possible to combine the advantages of both types of PCBs, such as the flexibility and capacity to bend in certain places while retaining the structural integrity and functionality of a conventional PCB in other places. Electronic gadgets like smartphones, wearables, and military hardware that need a combination of flexibility and endurance frequently employ rigid-flex PCBs.

The majority of rigid-flex circuit boards are constructed from numerous layers of flexible circuit substrates that are either outwardly or internally linked to stiff boards. The flexible substrates are often produced in a flexed curve during manufacture or installation and are intended to be in a continual state of flexibility. This depends on how the application is designed.

Advanced Rigid-Flex Circuit Board
Advanced Rigid-Flex Circuit Board

Applications of Rigid-Flex PCB

Rigid-flex PCBs are used in many applications. High-end mobile phones, digital cameras, military weaponry, and aerospace applications are a few of them. Rigid-flex circuitry is being used by manufacturers of medical equipment to dramatically reduce the size and weight of devices like pacemakers. By using more robust flex PCBs, military armament and control systems are also benefiting from the decrease in size and weight.

Aerospace

Rigid-flex PCBs combine the advantages of rigid and flexible PCBs, making them ideal for aerospace applications that demand stiff PCB construction in certain places but flexibility in others, providing a compact and highly dependable solution. 

If you are manufacturers of aerospace products who are seeking for PCB firms that can produce dependable printed circuit boards that hold up well in harsh conditions. ELEPCB is equipped to meet and beyond the demands and standards of the aerospace sector. We can create unique printed circuit boards to suit certain aerospace applications, whether they include tiny or big aircrafts or space missions.

Rigid-Flex PCB for Aerospace
Rigid-Flex PCB for Aerospace

Automotive Electronics

To make cars safer and easier to use, the automotive industry is always doing research and development. Circuit boards that are both hard and flexible are required with the advent of technologically advanced products in order to improve the entire driving experience for a consumer.

Consumer Electronics - Cell Phone

Today’s cell phones offer technology advancements for a wide range of sectors, including banking, retail, social networking, photography and the Internet. A gadget that puts the entire world at your fingertips requires the proper type of technology. The mobile phone’s effective design and manufacture depend on printed circuit boards.

Home Appliances

Rigid-flex PCB may be utilized for both industrial and domestic appliances because to their versatility. A wide range of tools and appliances, including TV remote controls, different lighting appliances, washing machines, smart home devices, and even home AV equipment, contain printed circuit boards.

You may either trace circuits manually or mechanically, depending on your preference. We can produce complex patterns and designs that promote higher PCB performance. We use premium soldering fillers, which serve as a powerful glue, to make sure that all components are securely fastened to the circuit board. Even after many hours of operation, our printed circuit boards have been shown to work effectively.

Industrial and Instrumentation Products

Today, a wide range of industries employ industrial and instrumentation devices to create effective, dependable, and long-lasting goods. The employment of cutting-edge production techniques, energy control systems, and specialized testing apparatus is essential for the success of these commodities. For the production of industrial items to be made more efficient, all of these technologies must operate at peak efficiency. ELE PCB has provided high performance printed circuit boards to this sector for many years.

Medical Equipment

In the medical sector, printed circuit boards have a significant role to play. To produce outcomes that are precise and of high quality, electronic medical devices require extraordinary process control. PCBs can be utilized in a wide range of devices, such as medical implants, medication delivery systems, imaging equipment, wireless controllers, and laboratory diagnostics.

Military and Defense

Defense applications for the land, air, and sea necessitate solutions with exceptionally high-performance printed circuit boards. In addition to performing to a specific degree of brilliance, the PCBs must also be adaptable to future upgrades.

Manufacturing Of Rigid-Flex PCB

Check the video on the right and learn the successful Flex & Rigid-Flex Designs for Streamlining Production. “Streamlining is defined as making a process more efficient and effective. Having a design that streamlines the production process will have the benefits of improved delivery times, reduced part cost, improved manufacturing yield, and even potentially improved long-term part reliability.”

When compared to conventional rigid board fabrication, the stiff-flex PCB manufacturing method is time-consuming and difficult. There are a number of processes that need to be completed really precisely. Any flexible part of the board that is handled improperly or is misplaced will have a significant impact on the final assembly’s durability and effectiveness. The steps described below are used by makers of rigid-flex circuit boards to assemble the boards.

Preparing the Base Material

Preparing and cleaning the laminate is the initial stage in the manufacture of the board. Before using further manufacturing methods, the laminate including a copper layer with an adhesive or adhesive less covering needs to be carefully cleaned. Pre-cleaning is crucial since vendors frequently sell copper coils with anti-tarnish characteristics to guard against oxidation. However, since this coating interferes with the production of rigid-flex PCBs, it must be removed.

The following actions are typically carried out by PCB makers to remove the coating.

I) The copper coil is first submerged entirely in an acidic liquid or subjected to an acid spray.

II) After using sodium persulfate to cure it, the copper coil is micro-etched.

III) To avoid adhesion and oxidation, the coil is fully coated with the right kinds of oxidation agents.

Circuit Pattern Generation

The preparation of the laminate is followed by the generation of circuit designs. These days, there are two basic methods used to expose the circuit layout.

  • Screen Printing

This method is well-liked because it may produce the necessary circuit designs or deposits right on the laminate’s surface. Not more than 4 to 50 microns thick overall.

  • Photo Imaging

The oldest and still most often used method for representing the circuit traces on the laminate is photo imaging. In this technique, the laminate is in close contact with a dry photoresist sheet that contains the necessary circuitry. The design from the photomask is then transferred to the laminate by this assembly being subjected to UV light. The laminate with the required circuit layout is then left behind after the film has been chemically removed.

Etch Circuit Pattern

Etching the copper laminate carrying the circuit pattern comes next after the production of the circuit pattern. The laminate is either dipped in an etch bath or sprayed with an etching solution by rigid-flex producers. To get the required results, both sides of the lamination are etched simultaneously.

Drilling Processes

The needed number of holes, pads, and vias must now be drilled. To drill precise holes, high speed equipment is utilised. Rigid-flex circuit board makers employ laser drilling techniques to produce very tiny holes. Excimer YAG and CO2 lasers are frequently employed to drill tiny and medium-sized holes in the substrate.

Through-Hole Plating

One of the most important processes in the production process for rigid-flex PCBs, this step demands the utmost accuracy and attention. Once the holes have been bored to the necessary standards, they are chemically coated, then copper is put in them. This creates electrical connectivity from layer to layer.

Apply Cover Lay or Cover Coat

Applying a cover lay to the top and bottom sides of the flex circuit is essential for protection. By doing this, the circuit will be completely protected from damaging weather, strong chemicals, and solvents. The most common cover lay material used by manufacturers is a polyimide sheet with adhesive. Screen printing is used to imprint cover lay material onto the surface, which is subsequently exposed to UV light to cure it. The cover lay material is laminated within predetermined limits of heat and pressure to guarantee good adherence to the substrate.

Cutting Out the Flex

Another crucial process that needs to be carried out carefully is blanking or cutting the individual flex board from the manufacturing panel. Hydraulic punching is typically used by manufacturers to produce rigid-flex PCBs in large quantities. Due to the high tooling costs, the same is not chosen for prototype or short production runs. Small production runs of prototype rigid-flex PCBs are produced using a specialised blanking knife.

Electrical Testing and Verification

Testing and verification are the last and most important steps in the production of rigid-flex circuit boards. The boards go through rigorous electrical testing for circuit performance, continuity, isolation, and quality compared to the design standards. There are several testing techniques employed, such as grid and flying probe test techniques.

2 layer teflon rigid flex circuit board
2 Layer Teflon Rigid Flex Circuit Board

Advantages Of Rigid-Flex PCB

Both rigid and flexible PCBs have distinct characteristics that are useful for particular applications. Designing a rigid-flex PCB is far more difficult than designing a traditional rigid PCB. But sometimes, we need to switch to a rigid-flex PCB to get the best of both.

Rigid-flex is employed in some designs for excellent reasons, notably when fitting the board into small places.

  • When the wire harness needs to be frequently removed from the PCB, connectors are useful. Adding connections to the PCB can only raise the chance of failure for a design that has several interconnected subcircuits in an enclosure.
  • The use of rigid-flex designs eliminates the requirement for board-to-board connectivity. Additionally, this results in weaker solder junctions, which might occasionally fail.
  • A rigid-flex PCB is frequently required in designs when space is at a premium. For instance, since there isn’t much room for high profile connections and wire harnesses, stiff flex PCB designs are advantageous for portable thermal scanners. Instead, you will have more room to route the traces because the linking circuit is already incorporated into the flexible substrate.
  • Due to the difficulty of manufacturing rigid-flex PCBs, they are often less expensive. However, employing stiff flex PCBs can make the product less expensive all around. You’ll save money on the cost of assembly, which in certain cases requires manual work, since wired interconnects are substituted with conductive layers of flexible material. There is no requirement to place a wire harness in the enclosure it is mounted on since a rigid-flex PCB is a complete circuit on its own. Such wiring requires a lot of time and adds to the price of the product per unit.
  • Since all the subcircuits are already linked when the rigid-flex PCB is built, automated testing of the PCB is very simple. Eliminating connection problems before the components are put together can also save waste and costs.

ELE PCB is able to fulfil all of your needs for Rigid-Flex PCBs, beginning with the prototype phase and continuing all the way through the production process. Because of our knowledge and experience in the field of manufacturing multilayer printed circuit boards, we hold a significant advantage over our competitors in the industry of generating printed circuit boards. In addition, we never promise a price that is greater than the prices offered by our rivals, and we never require customers to buy a certain minimum amount of any product with each order that they place.

Rigid-Flex PCB Manufacturer - ELEPCB

Prototyping printed circuit boards (PCBs) is a useful technique for designers since it helps save time and money while guaranteeing a high-quality result. Get in touch with ELE PCB right away if you need PCB prototype services for an upcoming venture. ELE PCB is here to assist you if you’re in the market for professional PCB prototype services.

Custom Rigid Flex Printed Circuit Boards - Symmetrical Structure vs Unsymmetrical Structure
Custom Rigid Flex Printed Circuit Boards - Symmetrical Structure vs Unsymmetrical Structure

ELE Rigid-flex PCB Manufacture Capacity

Layer Counts1-24Layer
Base MaterialPolyimide/FR4
Copper foil thickness1oz / 1/2oz/ 1/3oz
PI thickness25μm / 12.5μm
Board thickness0.07mm-0.5mm
Adhesive13μm
Max. board size400*800 mm
Product thickness tolerance±0.03mm
Min. Hole Diameter0.1mm
Min. Line Width / Distance0.04mm
Etching tolerance±0.015mm
PTH Hole dia. tolerance±0.03mm
NPTH Hole dia. tolerance±0.05mm
Outline Dimension tolerance±0.075mm
Stiffener material type±0.075mm PI / FR4 / PET / Steel piece
Outline profilePunching / Laser cut / Drilled
Surface finishHASL / OSP / ENIG / Immersion silver / Tin / Ni
Solder mask colorMulti-color
Silkscreen colorWhite/Black
Acceptable file formatCAD / Gerber file / powerpcb / AutoCAD / P-cad / CAM-350 /

Q&A about Rigid-Flex PCB

Flexible Printed Circuits (FPC) and Rigid-Flex circuits differ significantly in structure, applications, and manufacturing complexity, catering to varied design needs and functionalities.

FPCs for their unparalleled flexibility and lower cost in space-constrained applications, and Rigid-Flex circuits for their ability to combine robustness with design versatility in complex, reliability-critical devices.

The cost of Rigid-Flex Printed Circuit Boards (PCBs) is generally higher compared to traditional rigid PCBs due to several factors inherent in their design and manufacturing processes.