PCB, Multilayer FPC, Flex rigid Multi-layer PCB Fabrication

Flex-rigid PCBs, a combination of flexible and rigid PCBs, offer a unique solution for connecting electronic devices and parts. They are particularly suitable for portable electronic products and wearables due to their small number of connection points and ability to improve product performance. This article delves into the intricate process of manufacturing flex-rigid PCBs, highlighting key engineering design aspects and production phases.

Challenges in Flex-Rigid PCB Fabrication

Flex-rigid PCBs, while offering significant advantages, present unique challenges in the fabrication process. These challenges stem from the complex nature of their design and construction, as well as the specialized manufacturing techniques required to produce them.

Complexity of Manufacturing Technology:

One of the primary challenges in fabricating flex-rigid PCBs is the complexity of the manufacturing technology involved. Unlike traditional rigid PCBs, flex-rigid PCBs require the integration of both flexible and rigid materials, which adds a layer of complexity to the fabrication process. This complexity increases the difficulty of designing and producing flex-rigid PCBs, requiring specialized knowledge and expertise.

Numerous Process Phases:

Another challenge in fabricating flex-rigid PCBs is the number of process phases involved. The production of flex-rigid PCBs typically requires multiple steps, including flex circuit board fabrication, low-flow PP window, plasma cleaning, plasma roughening, pre-milling, laser cutting, shielding film lamination, and stiffening board lamination. Each of these phases adds time and complexity to the manufacturing process, making it more challenging to produce flex-rigid PCBs efficiently.

Long Manufacturing Cycles:

Due to the complexity and numerous process phases involved, the manufacturing cycle for flex-rigid PCBs is often longer than that of traditional rigid PCBs. The longer manufacturing cycle can lead to delays in production and increased lead times, which can be problematic for manufacturers and customers alike.

High Manufacturing Costs:

The complexity and specialized nature of flex-rigid PCB fabrication also contribute to higher manufacturing costs. The use of specialized materials, equipment, and processes adds to the overall cost of producing flex-rigid PCBs, making them more expensive than traditional rigid PCBs.

In summary, while flex-rigid PCBs offer many benefits, including increased reliability and performance, they also present significant challenges in the fabrication process. These challenges require careful consideration and expertise to overcome, making the production of flex-rigid PCBs a specialized and complex endeavor.

Engineering Design and Production of Flex-Rigid PCBs

Structure of Flex-Rigid PCBs

Flex-rigid PCBs consist of rigid outer layers bonded with flexible PCBs. Circuits from the rigid part are interconnected with the flexible part through plated vias. Each flex-rigid PCB board contains one or more rigid and flexible parts, requiring different fabrication technologies.

Process Design of Flex-Rigid PCBs

The fabrication process of flex-rigid PCBs includes new phases not found in traditional rigid PCB manufacturing. These phases include flex circuit board fabrication, low-flow PP window, plasma cleaning, plasma roughening, pre-milling, laser cutting, shielding film lamination, and stiffening board lamination.

Layout Design of Flex-Rigid PCBs

Flex-rigid PCBs feature flexible copper-clad laminate with widths of 250mm and 500mm. The size range of flexible PCBs varies from 250mm×100mm to 250mm×250mm, while rigid PCBs range from 18in×24in to 21in×24in. Layer-up technology is used to combine four or six pieces of flexible boards into a large board with the same size as the rigid board.

Low-Flow Prepreg

Low-flow prepreg is used to bond the flexible and rigid parts of the flex-rigid PCB. The thickness range of low-flow PP is from 40μm to 125μm. The alignment between low-flow PP and the core board is achieved using an OPE machine for punching and alignment.

Plasma Cleaning and Roughening

Flexible boards covered with Coverlay require plasma cleaning before lamination. Plasma roughening is added before lamination with specific cleaning conditions.

Riveting Jig Manufacturing

Manual riveting of flexible and rigid boards is difficult, requiring a riveting jig. The parameter of the dowel on the riveting jig is smaller than that of the rivet.

Solder Mask Technology Selection and Design Requirement

Spraying coating can be applied for flex-rigid PCBs with a thickness of more than 0.5mm, while thin boards usually use silkscreen technology. Solder mask window opening on flexible boards should be more than 4mil to 8mil from the board’s axle wire towards the rigid area.

Pattern Milling Design

Flexible materials are laminated with rigid materials, and the surface rigid materials are eliminated to expose the flex board. Surface finish is then applied to the exposed flexible board, and the complete pattern is milled out.

De-Cap Design

De-Cap alignment target design involves conformal mask alignment holes after lamination. Each plane should make use of its own fiducial marks.

Flex-Rigid PCB Strengthening Design

Connection parts on flex-rigid PCBs should be on the flexible board. Copper should be coated at the connection part without exposed copper.

Strengthening and Shield Film Design

Strengthening board aims to strengthen the rigidity of flexible boards. Shield film manufacturing conforms to customers’ design files.

The Advantages of Flex-Rigid Multi-Layer PCBs in Electronic Devices

Flex-rigid PCBs have become increasingly popular in the electronics industry due to their unique design and numerous advantages over traditional rigid PCBs. These specialized circuit boards combine the benefits of both flexible and rigid PCBs, offering a more robust and reliable solution for modern electronic devices. In this article, we’ll explore the advantages of flex-rigid multi-layer PCBs and how they contribute to the efficiency and performance of electronic devices.

1. Space-saving Design

One of the primary advantages of flex-rigid PCBs is their space-saving design. These PCBs can be folded or bent to fit into compact spaces, making them ideal for devices where space is limited. This flexibility allows for more efficient use of space within electronic devices, leading to smaller and more lightweight products.

2. Enhanced Reliability

Flex-rigid PCBs offer enhanced reliability compared to traditional rigid PCBs. The combination of flexible and rigid materials results in a more durable PCB that is less prone to damage from bending or vibrations. This increased reliability makes flex-rigid PCBs ideal for use in devices that require high durability, such as medical equipment and aerospace systems.

3. Improved Signal Integrity

Flex-rigid PCBs can also improve signal integrity in electronic devices. The design of these PCBs reduces signal loss and interference, resulting in more stable and reliable performance. This is especially important in high-frequency applications where signal integrity is critical for the proper functioning of the device.

4. Cost-effectiveness

Despite their advanced design and numerous benefits, flex-rigid PCBs can be cost-effective compared to traditional rigid PCBs. The ability to combine multiple PCBs into a single flex-rigid PCB can reduce manufacturing and assembly costs, making them a cost-effective solution for many electronic devices.

5. Design Flexibility

Flex-rigid PCBs offer designers greater flexibility in PCB layout and design. The ability to bend or fold the PCB allows for more creative and compact designs, leading to innovative and sleek electronic devices. This design flexibility can also reduce the overall size of the device, further enhancing its appeal to consumers.

6. Environmental Resistance

Flex-rigid PCBs are highly resistant to environmental factors such as moisture, dust, and temperature fluctuations. This resistance makes them ideal for use in harsh environments where traditional PCBs may fail. Additionally, the durability of flex-rigid PCBs means they have a longer lifespan, reducing the need for frequent replacements.

7. Ease of Assembly

Despite their complex design, flex-rigid PCBs are relatively easy to assemble compared to traditional PCBs. The combination of flexible and rigid materials allows for simpler assembly processes, reducing the time and labor required for manufacturing. This ease of assembly can lead to faster production times and lower manufacturing costs.

8. Customization Options

Flex-rigid PCBs offer a wide range of customization options, allowing designers to create PCBs that meet their specific requirements. From the number of layers to the thickness of the board, flex-rigid PCBs can be customized to fit the needs of virtually any electronic device. This customization capability makes them a versatile solution for a variety of applications.

In conclusion, flex-rigid multi-layer PCBs offer numerous advantages over traditional rigid PCBs, including space-saving design, enhanced reliability, improved signal integrity, cost-effectiveness, design flexibility, environmental resistance, ease of assembly, and customization options. These advantages make them an ideal choice for a wide range of electronic devices, from consumer electronics to medical equipment and aerospace systems. With their unique design and numerous benefits, flex-rigid PCBs are sure to continue revolutionizing the electronics industry for years to come.

Why choose Highleap to produce rigid-flex boards?

Choosing Highleap for the production of rigid-flex PCBs offers several key advantages. Firstly, Highleap boasts a team of highly skilled engineers and technicians with years of experience in producing rigid-flex PCBs. Their expertise ensures that your PCBs are manufactured to the highest standards of quality and reliability. Additionally, Highleap uses state-of-the-art equipment and advanced manufacturing processes, guaranteeing that your PCBs are of the highest quality and meet your exact specifications. This commitment to excellence is further supported by strict quality control measures, including thorough testing and inspection of all PCBs before they are shipped to you.

Secondly, Highleap offers a wide range of customization options for rigid-flex PCBs. Whether you need a specific size, shape, or configuration, Highleap can accommodate your needs. This level of customization allows you to tailor your PCBs to meet the unique requirements of your project, ensuring optimal performance and functionality.

Finally, Highleap understands the importance of timely delivery and works hard to ensure that your PCBs are delivered on time, every time. Their efficient production processes and logistics ensure that your PCBs arrive when you need them, minimizing downtime and keeping your project on track. With expertise, advanced technology, customization options, quality assurance, competitive pricing, and timely delivery, Highleap is the ideal choice for your rigid-flex PCB manufacturing needs.

Conclusion

Flex-rigid PCB design features complex structures and requires difficult design and manufacturing technology. The fabrication process demands accuracy control for dimensional stability. This article provides a reference for engineers to optimize flex-rigid PCB designs, ensuring the reliability and performance of electronic products.

For efficient Flex-Rigid PCB Fabrication Demands, contact Highleap, a manufacturer with many years of experience in manufacturing flex-rigid printed circuit boards. Reach out to discuss your Flex-Rigid PCB project or click below to request flex-rigid PCB price.