Rigid Flex PCB Design Guidelines and Manufacturing

In response to market requirements, Hemeixinpcb also offers production of its core HDI PCB technology in combination with flexible PCBs. To make this possible, Hemeixinpcb can offer rigid-flex and flexible PCBs and HDIs for high-reliability applications, with features down to 25 µm and flexible dielectric core down to 25 µm. With the revolution in portable communications’ products over the last decade, flexible PCB manufacturing has become a preferred design solution for both complex, three-dimensional product assembly and advanced component surface mounting demands.

Rigid Flex Circuits provide you with a unique tool in order to bring your innovative packaging ideas to market, and to also separate your products from the crowd. In addition, rigid-flex PCbs give you the ability to design your circuitry to fit the device, rather than building the device to fit the circuit board. Learn more about rigid flex pcb cost.

What is Rigid flex PCB

A Rigid-Flex PCB is a hybrid circuit board combining elements of both flexible circuit boards and rigid circuit boards, with an end result of a board that is able to be folded or continuously flexed and is normally formed into a flexed shape or curve during the manufacturing process. Most rigid flex boards consist of multiple layers of flexible circuit substrates attached to one or more rigid boards externally and/or internally, depending upon the design of the application. The flexible substrates are designed to be in a constant state of flex and are usually formed into the flexed curve during manufacturing or installation.

The flexible layers of a Rigid-Flex PCB are buried within the board and penetrate through the rigid sections of the PCB.

The trend to miniaturization in electronics continues. Integrated circuit board solutions are becoming more and more popular as a means of efficiently utilizing the even smaller casing volume in all three dimensions.

A rigid-flex printed circuit board is unique as the rigid part of the circuitry can be placed directly into the application. Then, the flexible section can be bent and even folded to fit around components to make another direct connection. This aspect ensures a reliable connection to parts for higher performance.

Some of the most common products that incorporate rigid-flex PCBs in their design include laptop computers, smartphones, and wearable devices due to the bending capabilities of rigid-flex.

Rigid-flex pcb boards are PCBs that have Flexible PCBs (FPC) and Rigid PCBs on the same board, which are commonly employed to save space, remove wiring assemblies and can also be welded with complex components. Combining other higher technology boards, such as HDI, as a part of its packaging, is also a common design.

Rigid Flex PCB design

The designs of Rigid Flex PCBs are a little more complex as these boards are designed in 3D, which allows the board to be folded or twisted to create the desired shape for the product. Designing a board in 3D means they can offer greater spatial efficiency and can subsequently be used in special instances where space and weight reduction may be necessary, such as in medical devices. By being able to design in three dimensions designers can twist, fold and roll the flexible board substrates to achieve their desired shape for the final application's package.

Rigid Flex PCBs are usually thinner than other boards, meaning it’s a great option for any thin or light packaging needs your products may have. With thin copper layers and adhesive-less laminates, it’s a great small, thin and light solution for your circuit design needs.

Benefits of Rigid Flex PCB

• Space requirements can be minimized by applying 3D
• By removing the need for connectors and cables between the individual rigid parts the board size and overall system weight can be reduced.
• By maximizing space, there is often a lower count in parts.
• Less solder joints assure higher connection reliability.
• Handling during assembly is easier in comparison with flexible boards.
• Simplified PCB assembly processes.
• Integrated ZIF contacts provide simple modular interfaces to the system environment.
• Test conditions are simplified. A complete test prior to installation becomes possible.
• Logistical and assembly costs are significantly reduced with flex-rigid boards.
• It is possible to increase the complexity of mechanical designs, which also improves the degree of freedom for optimized housing solutions.

Rigid Flex PCB Fabrication Applications

Rigid flexible PCBs offer a wide array of applications, ranging from military weaponry and aerospace systems to cell phones and digital cameras. Increasingly, rigid flex board fabrication has been used in medical devices such as pacemakers for their space and weight reduction capabilities. The same advantages for rigid flex PCB usage can be applied to military weaponry and weapon control systems

In consumer products, rigid flex doesn't just maximize space and weight but greatly improves reliability, eliminating many needs for solder joints and delicate, fragile wiring that are prone to connection issues. These are just some examples, but rigid flex PCBs can be used to benefit nearly all advanced electrical applications including testing equipment, tools and automobiles.

Available structures for rigid flex PCB

There are numerous, different structures available. The more common ones are defined below:

• Traditional rigid flex construction (IPC-6013 type 4) Multilayer rigid and flexible circuit combination containing three or more layers with plated through holes.
• Asymmetrical rigid flex construction, where the FPC is situated on the outer layer of the rigid construction. Containing three or more layers with plated through holes.
• Multilayer rigid flex construction with buried / blind via (microvia) as part of the rigid construction. 2 layers of microvia are achievable. Construction may also include two rigid structures as part of a homogeneous build.

Rigid Flex Printed Circuit Board Manufacturer

Rigid flex printed circuit boards (PCBs) are manufactured by combining rigid and flexible board technologies. These circuit boards are made up of multiple flexible circuit inner layers. An epoxy pre-preg bonding film is used to attach together these inner layers. The key benefit of these boards is that they are a combination of the best quality of flexible and rigid circuit boards. This can have several further benefits as far as stability, assembly, signal transmission, and overall size of the circuit are concerned. Hemeixin provides a number of variants in rigid flex PCBs, which include 4 layer rigid flex with ENIG finish, 10 layer rigid flex with 4 layer flex, 12 layer rigid flex with heat sink, 14 layer rigid flex circuit boards, and many more. It is one of the leading rigid flex PCB manufacturers.

4 Layer rigid flex PCB

Being the leading rigid flex printed circuit board manufacturer, Hemeixin provides them in different custom sizes and surface finishes. This 4-layer rigid flex PCB with ENIG finish is ideal for applications that involve ball grid arrays, as well as surface mount devices. The basic material used for its construction includes polyimide, as well as FR4. The polyimide helps improve the temperature resistance of this circuit board and makes it ideal for high temperature applications.

ENIG is an abbreviation of Electroless Nickel Immersion Gold. It is basically a two layer coating of 2-8 μin Au over 120-240 μin Ni. The components are soldered to the nickel layer, and it creates a barrier over the copper. Necessary protection during the storage is provided by the gold. The gold also offers low contact resistance that is required by thin deposits of gold. This is one of the most widely used finishes in the PCB industry due to its compliance with RoHS regulations.

We can provide the printed circuit boards in various sizes, from small to large. The maximum panel size offered is 18″x24″, whereas board thicknesses can easily vary from 0.5mm~3.0mm (0.02″~0.12″). The outlines are created by methods such as routing, V-cut, and punching. We use laser equipment that helps us achieve finish thickness as small as 0.2mm (flex), and 1.0mm.

Every printed circuit board depends on the copper for carrying electricity. We understand that copper thickness plays a key role in the performance of these circuit boards. Thus, we allow the customers to choose from a variety of copper thicknesses, including 0.5 OZ, 1.0 OZ, 2.0 OZ, 3.0 OZ, up to 6 OZ. The solder mask helps in improving the aesthetic appeal of the components on the PCB. We can provide rigid flex printed circuit boards in various solder mask colors, including white, black, blue, green, red, and Taiyo PSR4000 white. The PCB can be availed in silkscreen colors – black and white.

rigid flex printed circuit boards have minimal space requirements that are optimized by 3D application. These circuit boards require no cables or connectors between the rigid parts. This helps reduce the board size, as well as overall system weight. These lesser solder joints also help assure high connectivity. Additionally, these boards have ZIF contacts that are integrated. These contacts help simplify the system interfacing. This 4 layer rigid flex PCB and other printed circuit boards are vacuum packed during the transit. This helps us assure the quality, as well as working condition of the boards.

6 Layer rigid flex PCB

Hemeixin provides rigid flex printed circuit boards in various standard and custom specifications. These printed circuit boards are used regularly in industries such as power, automobile, telecommunication and lighting. Hemeixin's six-layered rigid flex printed circuit boards have gained popularity over the years. These printed circuit boards are known to offer flexibility, as well as design freedom to PCB engineers.

A six-layered rigid flex circuit board comprises 6 conductive layers, and are fabricated in a variety of sizes up to 18″ x 24″, and in board thicknesses 0.5mm~3.0mm (0.02″~0.12″). The outlines are created using methods such as punching, routing, and V-cut. We employ only laser drilling to create holes, which enables us achieve holes as small as 0.004″, and minimum finish thickness 0.3mm (flex), 1.6mm.

The conductive layers of this PCB are created using copper. We use various types of copper to meet the diverse application needs. Annealed copper is mostly used in applications that demand repeated movement of the printed circuit board. The circuit boards can be availed in various thicknesses ranging from 0.5 OZ, 1.0 OZ, 2.0 OZ, 3.0 OZ, up to 6 OZ.

8 Layer rigid flex Circuit Boards

rigid flex printed circuit boards combine rigid and flexible pcb board technologies, and are known for their operational efficiency. Hemeixin provides a wide range of rigid flex printed circuit boards that are regularly used by manufacturers, who manufacture transformers, inductors, stepper motors, planar magnetics, etc. We provide 8 layer rigid flex circuit boards, which are used in various industrial, as well as consumer electronic applications. These circuit boards comprise alternate layers of flexible and rigid circuits that combine the best of both technologies.

The printed circuit board is manufactured using polyimide and FR4 material. This combination helps improve the thermal stability of the board, as well as makes it ideal for high-temperature applications. Additionally, the variety of surface finishing options such as immersion gold, OSP, and HASL, helps improve the performance of these PCBs in challenging conditions involving UV and radiations, oils, and harsh chemicals. The PCBs can be availed in either of two solder mask colors – black, and white.

We, at Hemeixin, can work on specifications, which are complex, as well as challenging. For instance, this 8 layer rigid flex circuit board can be availed in board thicknesses ranging from 0.5mm~3.0mm (0.02″~0.12″), and copper thicknesses 0.5 OZ, 1.0 OZ, 2.0 OZ, 3.0 OZ, up to 6 OZ. Also, we can assure the finish thickness of 0.2mm (flex), 1.6mm.

We employ fabrication methods such as scoring and break away routing, as well as punching and V-cut to create precise outlines. Our advanced laser drilling equipment enable us to provide drilled holes in sizes as small as 0.004″. Laser technology is also employed during the trimming and routing processes. Our advanced technology capabilities enable us to achieve the panel sizes up to 18″ x 24″, and various other complex dimensions.

All the printed circuit boards designed by us undergo rigorous testing before leaving the premises. These boards are considered ideal for applications, where space and weight can be a major concern. We have often concentrated on building circuit boards with lesser cables, connectors, and solder joints, while meeting a major requirement – a lightweight circuit board. This 8 layer rigid flex printed circuit board is vacuum packed that helps avoid shocks during transport, and, aids us to stay true to our quality commitment. In addition to this 8 layer circuit board, we can provide these rigid flex PCBs in any number of layers between 1 and 20. We can provide these printed circuit boards in a variety of layouts to meet the requirements of customers across various industries.

10 Layer rigid flex PCB

This is a specially designed 10 layer rigid flex printed circuit board (PCB), which has 4 additional flexible layers. This provides advantages in terms of stability and flexibility. At Hemeixin, we use Polyimide, Kapton, and PET as the main materials for manufacturing printed circuit boards. Especially for the rigid section, we use specialized Taiyo PSR 4000 white solder masks. This stable, rigid area of the PCB is where the main components are mounted. The supplementary flexible layers allow for a large flex surface, as well as high frequency component to connector connections across the flexible area. Overall, this results in dynamic bending, strong signal integrity, and high reliability.

The 10 layer rigid flex PCB with 4 layer flex circuit boards that we provide are made from FR4 + Pl material. The finish thickness of these printed circuit boards is 1.6 mm. These specially designed PCBs have a decent insulation resistance of about 1000 MW, and an excellent dielectric strength of 5 KV. These circuit boards are surface treated with immersion gold material. However, you can also get the surface finishing done in other materials, such as OSP, and HASL. You can avail these printed circuit boards in a wide range of copper thicknesses, including 0.5 OZ, 1.0 OZ, 2.0 OZ, 3.0 OZ, up to 6 OZ. The board thickness can also be customized from 0.5 mm to 3.0 mm. The selection of solder mask can be done from varied color options, such as white, black, blue, green, red, and Taiyo PSR4000 white.

12 Layer rigid flex PCB

Rigid flex printed circuit boards are the improved printed circuit board designs, where multiple layers of rigid copper and flexible layers are organized one above the other. These circuit boards are designed to work with complex electronics. Hemeixin has gained recognition as rigid flex PCB manufacturer in the China. Our 12 layer rigid flex PCB with heat sink help avoid overheating, thereby ensuring efficient performance of chips, connectors, traces, and solder joints.

The PCB comprises a combination of polyimide and FR4 material, which offers excellent electrical insulation, and thermal stability. The heat sink components equipped to the PCB are designed to transfer the heat produced from a device to a fluid medium like air. Sometimes, coolants and water are also fused with air. The use of this medium enables the heat to dissipate from the printed circuit board. Other benefits of heat sinks include excellent thermal conductivity, enhanced surface area in connection to fluid medium, and improved performance of the PCBs. The PCB has two layers dedicated to ground and power. The power and ground layers allow an even distribution of heat.

Our advanced pcb fabrication facilities help us design and manufacture PCBs in thickness ranging from 0.02ʺ to 0.12ʺ. Also, we can provide copper layers in thicknesses 0.5, 1.0, 2.0, 3.0 up to 6 Oz. The finish thickness is 0.2mm (flex), 1.6mm, and maximum panel size is 18ʺ X 24ʺ. We provide a wide variety of solder mask colors, including white, blue, black, red, green, and Taiyo PSR4000 white. There is also a huge variety, when it comes to surface finishing, such as HASL, immersion gold, OSP, etc. All printed circuit boards are vacuum packed or packed individually in plastic bags to avoid damages while transportation.

14 Layer rigid flex PCB

Hemeixin is one of the leading manufacturers of 14 layer rigid flex PCBs. These PCBs are used for applications, which demand extreme precision and tight tolerances. Over the years, we have helped clients by designing and providing compact sized 14 layer rigid flex PCBs. These circuit boards comprise flexible inner layers, which are attached using a prepeg film, which resembles to a multilayer flexible circuit. These rigid flex PCBs are equipped with a board internally, externally, or both – as needed by the circuit.

The rigid components of these circuit boards are utilized for high density device boards. Additionally, flexible circuits allow narrow lines, thereby supporting high density device population. The combination of rigid boards and flexible circuits allow us to offer streamline design, thereby reducing package weight and size.

Typically, these circuit boards are made from FR4 material. We can also provide them in exotic materials such as Rogers Ultralam 2000, Rogers RO4350, Arlon AR350, Nelco 4013, as well as several metal core materials. We use various types of stiffeners to bond flexible layers. They include stainless steel, FR4, polyimide, etc. We can provide 14 layer rigid flex PCBs in minimum thickness 0.054ʺ and maximum thickness 0.250ʺ. The surface treatment is ENIG, whereas we also provide surface finishes like HASL – leaded and lead free solders, electroless soft gold, electrolytic nickel, immersion silver, carbon ink, etc. We use advanced laser machines, which enable us to deliver accuracy of mil traces, lines, and patterns. The 14 layer rigid flex PCBs are used in applications such as telecommunication, computers, medical devices, and automobiles.

HDI rigid flex PCB

High-dense-interconnect PCB boards have a higher wiring density per unit area than typical PCBs. With changing technology, printed circuit board technology has evolved to meet the demand for smaller and faster products. HDIs have denser wiring, resulting in lighter, more compact PCBs. Instead of using several PCBs in a device, one HDI PCB board can replace all the preceding boards.

Hemeixin provides industry-leading HDI capabilities to optimize today's challenging designs. The use of HDI and Every Layer Interconnect (ELIC) stacked copper filled µVias, fine feature etching, and precision registration provide unique, mass-production solutions for complex designs.

With extensive investments in leading-edge production systems, HDI Rigid flex PCB Hemeixin can build the next generation of interconnect solutions.

Rigid Flex pcb designs utilizing HDI/ELIC capabilities eliminate the need for the module connectors and saves precious space within the slim, high-style designs compact designs. Hemeixin provides this new end-to-end solution from initial design to mass production.

HDI rigid flex PCB Builds

HDI PCBs have a much higher wiring and pad connection density than traditional PCBs, due to their design constraint. The structural build up is explained below.

• 1+N+1 – PCBs contain 1 “build-up” of high-density interconnection layers.
• i+N+i (i ≥ 2) – PCBs contain 2 or more “build-up” of high density interconnection layers. Microvias on different layers can either be staggered or stacked up.
• Any Layer HDI – The layers of a PCB are high density interconnection layers which allow the conductors on any layer of the PCB to be interconnected freely with copper filled stacked microvia structures.

RIGID FLEX PCB combine the benefits of flexible and stiff board technologies. These PCBs provide mechanism reliability in condensed packages of extreme conditions that may not be tolerable for connectors. Depending on the application, most rigid flex PCB have some layers of flexible circuit substrates linked to one or more rigid boards externally and/or internally. Flexible substrates are made in a constant state of flex and can be frequently bent into a flexed curve during the complete lifecycle of the product.

How are RIGID FLEX PCB made?

RIGID FLEX PCB board designs are more challenging to create than traditional rigid board designs because they are made in 3D space, which allows for higher spatial efficiency. Designers can twist, fold, and roll flexible PCB board substrates to get their desired results by designing three dimensions.

In the early phases of designing, it is beneficial to carefully consider and thoroughly evaluate the available possibilities of RIGID FLEX PCB solutions that will yield considerable benefits. In addition, it’s vital to involve the PCB fabricator early in the design process to guarantee that the design and fabrication phases are in sync and that final product changes are considered.

The method has been proven and reliable in various applications, including stiff flex prototypes and large-scale PCB fabrication and PCB assembly. The flex PCB section excels in overcoming space and weight constraints with spatial degrees of freedom.

Hybrid flex pcb

Flex and Rigid-Flex PCBs will include some degree of flexibility. This can be in the whole circuit (Flex) or a dynamic flexible join between two or more rigid boards (Rigid-Flex). The main advantage is often considered as having the ability to physically fit into products where no other solution would work but they have many other advantages.

Each Flex-rigid board has multiple zones of rigid and flex materials based on the design that work in sync to produce one seamless board. The common materials used in manufacturing of rigid-flex boards are FR4 for the rigid part of the PCB and materials like Kapton for the flex part. Usually Rigid part has more layers than the flex.

There are two common types of Rigid-Flex PCBs; flex to install and dynamic flex.

• Flex to install: this is the most common of the two and applies when a board only folds once, either when the device or product is assembled or dismantled, but is otherwise sturdy and stable throughout
• Dynamic flex: a dynamic flex board will be used when a product is required to fold and bend when in use, meaning they are highly durable and can last through a thousand flex cycles

Whilst the design might be a touch more complex, and the process slightly more time consuming than the usual printed circuit board, they are an investment worth making with their versatile and durable nature.

Blind via rigid flex pcb

Rigid flex PCB is a special class of printed circuit board wherein both rigid and flex PCB materials are combined into a single composite. This highly versatile construction allows designers to replace cumbersome arrangements of connectors, wires and ribbon cables with integrated flex segments between rigid board elements. Since rigid flex PCBs can be bent and folded, it is an ideal technology for the purpose of optimizing 3D volume utilization and dynamic loading conditions. By additionally exploiting the unique characteristics that each material type has to offer, specific performance and/or mechanical interface challenges can be addressed, resulting in a functionally superior, less complex, lighter and more reliable interconnect solution than would otherwise have been possible.

Given the multiple advantages of rigid flex PCB, it is no surprise that it finds widespread use in highly robust aerospace and defense applications as well as in high-performance medical devices that target form factor reduction. Its inherent suitability for the purpose of simplifying module/system level design, however, make it an attractive, viable and costeffective technology for various other industrial sectors, as well.

Hemeixin has been serving the market for rigid flex PCB technology for more than 15 years, continually building upon its expertise and reputation for excellence by providing workable solutions for highly complex and unique interconnect challenges. Be it a 14-layer bookbinder PCB for the Herschel Satellite, a highdensity board for an F-1 steering wheel or a 3D-miniaturization project in the field of medical implants, Hemeixin' expertise in rigid flex PCB circuitry will serve you with a tailor-made, highquality solution that fully meets your needs.

A combination of rigid Printed Circuit Board technology and flex circuit technology allows for a very wide variety of rigid and flex layer counts and combinations. Rigid areas can utilize blind and buried vias, with some limitations, and via in pad technology. Rigid area layer counts range from 2–20+ and flex area layer counts from 1–8+.

• Multilayer HDI/microvia rigid-flex circuit boards for 3D-miniaturization
• Sequential, parallel, symmetric and asymmetric build-ups
• High-frequency, high-temperature and ruggedized rigid-flex solutions
• High-frequency rigid-flex HDI solutions based on LCP base material
• Thinned bending zones
• High variety of flex & rigid base materials, surface protections and surface finishes

6 Layer Rigid flex PCB Blind and Buried Via

An implant demands high reliability and the limited space has to be used in an optimal way. The flexible areas of the populated PCB can be bent to achieve a space saving 3D assembly.

• Turnkey flex solutions targeting 3D miniaturization
• Highly reliable, extremely robust multilayer flex/microvia substrates
• Ultra-thin base materials
• Filled via and stacked via process available
• Complex mechanical/assembly assist features, including special profiles, fold lines, cut-outs and thinned bending zones/cavities
• Wrap-around boards
• Chip-on-flex (COF), chip scale packaging (CSP) substrates, and BGAs
• A wide variety of surface finishes, for example;OSP, ENIG, ENEPIG
• Flying leads
• Bending test for flexible circuits
• Ultra-fine line flex cables

16 layer rigid flex PCB for medical application

The high packing density with lots of BGAs requires a highly integrated printed circuit board with 16 layers and buried as well as blind vias. The numerous signals from the sensors are transmitted through 6 flex layers. In order to keep the 6-layer flex areas flexible bookbinder and window technology was used. This PCB measures 168 x 91 x 2.1 mm.

In recent years, Hemeixin has accumulated extensive expertise in costumer projects and commissions of the widest variety of designs and applications, from Aerospace to Medical devices and currently it supplies many customers. With the broad range of technology we offer, you can make the best possible selection for any requirements in terms of performance and costs.

Hemeixin is offering a big variety of rigid-flex PCB constructions, using high end/quality base materials, like high TG/low CTE FR4, combined with polyimide foils and various adhesives. State of the art interconnection technologies like stacked or staggered vias and via-in-pad structures are used to drive miniaturization further down the road. A big portfolio of surface finishings is enabling Hemeixin customers to use all available assembly methods on boards produced by us.

Rigid flexible PCB circuits are an essential part of modern day technologies. The fact that they can bend and be folded means that these circuits are highly adaptable to any circumstance and application. One simply does not have that capability when it comes to completely rigid PCB circuits, which serve their purpose in conventional electronics, but fail when it comes to specialized situations.

There are many advantages to using rigid flex PCB over traditional circuit boards. For example, during the manufacturing process, conventional boards are exposed to potential human error when soldering, routing, or wrapping the wires. But because rigid flex circuits must be manufactured through automated processes adhering to precise designs, there is less room for error.

Of course, the greatest advantage to using rigid flex circuits is that they are designed to have the freedom to move without compromising the overall integrity of the device’s components over time.

Our rigid flex PCB manufacturing allows circuits to be configured in ways that satisfy your specifications and needs. We can create circuit boards according to specific shapes, and we can also modify their thickness. That means that the circuit board’s flexibility doesn’t just extend to its physical properties, but also in the various ways it can be designed. Rather than creating a product around your circuit board, we allow you to build your rigid flex PCB around your product, ultimately reducing size and space limitation issues and considerations.

Moreover, when talking about the functionality of rigid flex PCB manufacturing it is also important to consider the higher device density population it enables, allowing for more features to be included in your product.

Finally, since the rigid flex PCB circuits are thinner and less bulky than conventional circuit boards, heat is able to dissipate with a higher degree of effectiveness, resulting in a longer operational duration.

The bottom line is that rigid flex PCB is the right choice for you if you want to produce lighter, functional products.