Category Archive: Uncategorized

What Is IPC-6013 and Why Is It Important for Rigid-Flex PCBs?

To ensure the integrity of rigid-flex PCBs, it is necessary to inspect and test them following a standardized set of procedures. IPC-6013 is a key performance specification for both flexible and rigid-flexible circuits. This blog will discuss what IPC-6013 and IPC inspection standards are, and why they are important for these PCB types. 

What is IPC Testing?

Founded in 1957, the Institute for Printed Circuits (IPC) is a global trade association that represents the electronics industry with a core focus on electronics design, assembly, and PCB manufacturing. There are numerous IPC specifications that products can be tested on, ranging from raw material and design specifications to performance and assembly specifications. Performing IPC testing allows manufacturers to build more reliable products by following a set of proven standards. Companies can become certified by the IPC to perform testing on products and ensure they meet IPC specifications. 

 

The IPC outlines a wide range of testing methods, including:

  • Visual examination
  • Dimensional measurements
  • Chemical testing
  • Mechanical testing
  • Electrical testing
  • Environmental exposure
  • Material requirements

Performing these tests ensures that electronic products meet the necessary performance and manufacturing standards. However, it’s important to note that the testing of circuit boards is very application- and environment-specific. For example, PCBs used in aerospace applications require a more rigorous testing and inspection process compared to PCBs used in consumer products.

What is IPC-6013? Why is it Important for Flex & Rigid-Flex PCBs?

IPC-6013D: Qualification and Performance Specification for Flexible/Rigid-Flexible Printed Boards

IPC-6013D: Qualification and Performance Specification for Flexible/Rigid-Flexible Printed Boards

IPC-6013 is the standard for the qualification and performance for flexible circuits, including both flexible and rigid-flex PCBs. There are four different IPC classifications for circuit boards, each of which has different requirements for testing and inspection. These classifications include: 

  • Class 1. This group is assigned to general electronic boards with a limited life and simple function capabilities, such as those used in everyday consumer electronics.
  • Class 2. Dedicated service electronic products make up this class, including low-level industrial applications and certain medical applications. These boards have extended life and higher reliability, and they follow more stringent standards than Class 1.
  • Class 3. Class 3 PCBs are used in high-performance electronic products that cannot fail and are often used in demanding performance applications. These boards are very reliable and require high levels of testing and inspection for conformance to the requirements.
  • Class 3A. This is the highest class for printed circuit boards. These boards must follow extremely stringent standards for testing and inspection as they are often used in critical aerospace and military applications. 

The primary difference between each classification is the degree of inspection and permissible defects. For example, Class 1 and Class 2 boards can have minor cosmetic defects as long as they don’t affect the board’s overall function; however, Class 3 and Class 3A boards must be free from defects to ensure reliable performance with no failures in the end application.

Following IPC testing procedures is an essential step in ensuring the integrity of flex and rigid-flex PCBs. There are many possible ways to verify the quality of your raw materials and finished products; however, the guidelines set up in IPC-6013 are the most comprehensive and globally recognized starting point. 

About Rigid-Flex PCBs at Printed Circuits

When choosing a rigid-flex PCB manufacturer for any application, it’s important to choose a company that can demonstrate the effectiveness of its products. Testing according to IPC-6013 standards is a globally recognized way of ensuring the quality, performance, and overall integrity of your PCBs. This type of testing is particularly critical in Class 3 and 3A boards, which require extremely tight tolerances and conformance to stringent high reliability standards.

Printed Circuits has been designing and manufacturing rigid-flex PCBs for over 40 years. We have an in-depth understanding of the industry demands for PCBs across a wide range of applications, and we primarily fabricate IPC-6013 Class 3 boards and above. Whatever your required board attributes or product yield, our state-of-the-art equipment and 65,000 sq. ft. manufacturing space allows us to meet your PCB needs. To learn more about the IPC-6013 specification or our rigid-flex PCBs, contact us today.

 

FR4 Rigid Boards vs. Rigid-Flex Boards: What Are the Differences?

Printed circuit boards (PCBs) are a key component of many electronic devices and systems. They come in many variations, including in regard to design, material, and more to suit the requirements of different industrial applications. Among these variations are FR4-based boards, as well as rigid-flex PCBs. The following blog post overviews the differences between PCBs made from FR4 or other rigid materials, and rigid-flex PCBs which are hybrid systems of flexible circuits and laminates bonded together with no-flow prepreg. 

FR4 Rigid Boards

Rigid PCBs —referred to as rigid boards or hardboards—are made from inflexible substrates that prevent them from bending. Due to their relatively low cost, wide availability,  and reliability, they are one of the most popular types of PCBs. 

The most common substrate used for rigid PCBs is FR4 epoxy laminate and prepreg, which are made from glass cloth impregnated with epoxy resin. The term “FR4” refers to the designation given to materials that meet certain requirements as defined by NEMA LI 1-1998 standards. The materials generally demonstrate good physical, mechanical, thermal, and electrical properties. Additionally, they are often the lowest cost material for PCBs. These aspects make FR4 an excellent material for rigid PCBs for many applications. 

FR4 material is commonly used to produce single-sided and double-sided PCBs, as well as multilayered PCBs, typically with lower layer counts (less than 14 layers). While it is a cost-effective option for these PCB builds, it becomes increasingly less cost-effective with higher layer counts and more advanced materials. 

Other common resin systems and materials for building rigid PCBs include epoxy blends to achieve desired mechanical or electrical performance properties, polyimide, Teflon and Teflon blends.  Each offer enhance performance attributes for today’s electronics designer.

Rigid-Flex Boards

Rigid-flex PCBs incorporate features of both rigid and flexible PCBs. They have flexible and inflexible sections. The flexible sections assure electronic connection, but still allow the board to be folded into place. The inflexible sections provide the mechanical and electrical connectivity for the electronic components such as semiconductors, resistors, capacitors, etc.. These qualities make them ideal for use in more complex electronic designs. 

One of the most common – and necessary – materials used in the construction of rigid-flex PCBs is no-flow and low-flow prepregs, which is a prepreg material that has undergone a longer curing period. The result is a prepreg sheet that has a lower rate of resin flow. This ensures that the resin material can flow to the edge of the rigid sections without overflowing into the flexible sections, which is critical to ensuring the rigidity of the rigid sections without affecting the flexibility of the flex sections. 

No-flow prepregs are also commonly used to bond components to PCBs (e.g., heat sinks to rigid sections and stiffeners to flexible sections). They are not ideal for use with heavier copper weights – such as three ounce copper and above, as the resin generally does not have sufficient flow to encapsulate the circuitry. 

Key Differences Between FR4 Rigid Boards and No-Flow Rigid-Flex Boards

Rigid PCBs made from FR4 and rigid-flex PCBs both offer unique advantages and disadvantages that make them suitable for particular applications. For example: 

  • FR4 rigid boards are much less expensive than rigid flex PCBs. This makes FR4 rigid boards a common choice for consumer electronics in everything from appliances, to computers, gaming systems and even a large amount of automotive electronics, where cost is more of a concern.

  • Rigid-flex boards are flexible in some areas and rigid in others. As a result, rigid-flex boards are ideal in high reliability applications such as environments with high levels of shock or vibration where conventional connectors with flexible cabling will fail.  They are also ideal for dynamic flex applications where the flexible sections are bent hundreds of thousands of cycles without failure.  These features make rigid flex ideal for “never fail” electronics applications typically found in medical, military, aerospace and industrial applications.

Choose Rigid-Flex PCBs at Printed Circuits

At Printed Circuits, we specialize in the design and fabrication of rigid-flex printed circuit boards. With over 40 years of PCB experience and state-of-the-art PCB manufacturing equipment, we produce high-quality PCB solutions to our customers’ exact requirements. We maintain ISO 9001:2015 certification, ITAR registration, and IPC membership. 

Looking to learn more about rigid-flex PCBs? Check out this list of FAQs about rigid-flex PCBs compiled by the Printed Circuits team!

To learn more about the differences between FR4 boards and rigid-flex boards or find out more about our capabilities, reach out to us today. To discuss specific PCB requirements with one of our team members, request a quote.

Understanding the Rigid Flex PCB Prototyping Process

Rigid flex printed circuit boards (PCBs) feature a hybrid circuit board design that combines the malleability of flexible circuits with the rigidity of hardboards. The resulting component is hard at some points and flexible at others, which allows it to be folded or flexed as needed to fit the electronic configuration. 

Rigid flex PCBs are highly customizable; they can be designed and assembled to a variety of configurations, flexibilities and rigidities, and sizes to suit nearly any application. This factor allows them to be tailored to meet stringent system requirements. However, they must be carefully engineered and constructed to ensure they operate and perform as intended. Otherwise, they may cause issues within the equipment in which they are installed. For this reason, prototyping is a critical step in the rigid flex PCB production process. 

Prototypes allow PCB fabricators to evaluate the functionality, performance, and quality of a rigid flex PCB design and determine if modifications and alterations are needed to comply with the necessary specifications and standards. By identifying any necessary changes before a design proceeds to the production stage, fabricators and customers will ultimately save time and money. 

How the Rigid Flex PCB Prototyping Process Works

The rigid flex PCB prototyping process is similar to the actual rigid flex PCB production process; both processes entail creating a PCB based on a PCB design. However, unlike the production process, the prototyping process can involve many designs. As new rigid flex PCBs are typically unique to the system for which they are intended, board fabricators generally cannot reference past PCB designs for a suitable solution. As a result, they may develop a few different designs before finding the right combination of mechanical and electrical properties. 

While the rigid flex PCB prototyping process may vary slightly from one project to the next depending on the production specifications, it generally involves the following steps: 

  • Initial Design Creation. The engineering team creates an initial design based on the specifications and requirements provided by the customer. Customers can make it easier for the team to create an initial design that meets their needs by providing as detailed information about their system and end goals as possible. 
  • Design Review. Once the team creates an initial design, they send it to the PCB fabricator for review. One of the most important aspects of this review process is determining all possible failure points of the design—i.e., how it may fail in the manufacturing process as well as in the end application.  
  • Customer Follow-Up. Once the design has undergone the review process, the team can bring it back to the customer. At this point, they can answer and address any questions or concerns the customer may have about the design and alter or add any elements the customer may request. While the latter can add to the overall lead time for the project, it is easier and cheaper to make any changes during the prototyping stage rather than in the production stage. 

For a more comprehensive overview of the overall rigid flex PCB manufacturing process, check out this flow diagram

Key Considerations for Rigid Flex PCB Prototyping

During a rigid flex PCB manufacturing project, there are many design and fabrication factors to consider to ensure you receive a product that fully meets your needs. An experienced and knowledgeable PCB fabricator can help guide you through the process. Their input and insight can help you find a balance between product design and product manufacturability, ensuring you receive a design that contains all of the elements you want and they have the capabilities to actualize it. 

One of the main questions customers ask regarding the rigid flex prototyping process is “why does it take so long?” This question is particularly prevalent among customers who generally use rigid PCBs. While many rigid PCBs are available with lead times of 24 hours, quality rigid flex PCBs come with a minimum lead time of two weeks and a more reasonable lead time of four to six weeks. There are several reasons for these longer lead times, such as:

  • Long bake cycles. When producing rigid flex PCB prototypes, the amount of time needed for the board baking alone can be days or even weeks when added together.  
  • Challenging design elements. The lead time for rigid flex PCB prototypes is highly dependent on the design. Many rigid flex PCB designs integrate challenging elements that increase the overall lead time for prototype production. For example, buried vias (design elements that connect the outer layer of the PCB to one or more inner layers) can add two to three weeks to the overall lead time, while bookbinding constructions (design elements that allow the PCB to bend at tighter angles) can add 12 weeks to the overall lead time. 
  • Extensive manufacturing evaluation process. Good PCB fabricators carefully evaluate prototypes to ensure the final product will operate and perform as intended. Some of the many things they may check include: 1) are the various elements on the board communicating with each other correctly? 2) is the impedance working correctly? 3) are the signals arriving at the chip at the right time?  

While some PCB fabricators may boast about producing and delivering rigid flex PCB in two weeks or less, they often take shortcuts that can provide lower quality products. For industries with mission-critical applications (e.g., aerospace, medical, and military electronics), these quickly produced PCBs can lead to field failures. For this reason, it is essential to partner with a reliable PCB fabricator who will check all the boxes and do so thoroughly. While truly high quality rigid flex PCBs may have longer lead times, you can rest assured they will meet your specifications and industry reliability standards. 

Rigid Flex PCB Prototyping at Printed Circuits

Rigid flex PCBs find application in a wide range of electronic devices and systems. However, they must be carefully designed and manufactured to ensure they operate as intended and perform as expected, which is why prototyping is an essential step in their manufacture. 

Equipped with over 40 years of experiencing designing and constructing rigid flex PCBs and state-of-the-art manufacturing technology, Printed Circuits is the ideal partner for all rigid flex PCB needs. We can fabricate quality product solutions for nearly any customer need, including PCBs that comply with UL 94 V-0 and ISO 9001:2015 standards. 

Have any questions about rigid flex PCBs or the rigid flex prototyping process? Reach out to us today.

What is UL 94 V-0 Certification and Why is it Advantageous for Rigid Flex PCBs?

Rigid-flex printed circuit boards (PCBs) combine ideal design elements of both rigid and flexible circuits into a single, versatile electronic package. Their hybrid design allows them to be folded or bent to fit confined or irregularly-shaped spaces while still maintaining rigidity in areas that require more support. Due to the mission-critical nature of the applications they integrate with, rigid-flex PCBs must meet certain standards and qualifications to verify their safety and performance. Among these qualifications is the difficult-to-obtain UL 94 V-0 certification, which is a safety standard pertaining to a PCB’s flammability.

In this blog, we highlight the details of the UL 94 V-0 certification and the advantages of partnering with a UL 94 V-0-certified rigid flex PCB manufacturer capable of providing it.

What is UL 94 V-0 Certification?

Underwriters Laboratory (UL) is a third-party safety science organization that develops comprehensive standards and testing procedures aimed at validating the physical and environmental safety of products. The purpose of the UL 94 V-0 certification is to ensure fire protection and electrical safety of electronic components. A UL 94 V-0 rating indicates that the product can tolerate a certain amount of exposure to a flame without igniting.

Electronics designers and fabricators are often required to obtain UL recognition to prove the viability of their products and meet liability insurance carrier requirements. Acquiring this certification can be challenging due to the rigorous and thorough nature of the testing process. It essentially requires separate testing for each individual component used in a product’s design, which can quickly become overwhelming, expensive, and time-consuming.

Why is UL 94 V-0 Certification Advantageous for Rigid Flex PCB Constructions?

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Why is UL 94 V-0 Certification Advantageous for Rigid Flex PCB Constructions

When it comes to product safety, UL has a long-standing track record of integrity. By providing unbiased confirmation of safety, the UL mark communicates to consumers that the product can be trusted and allows them to feel more confident in purchasing it. For PCB manufacturers, UL certification represents alignment with the best safety practices in the industry, giving them a major advantage over competitors.

The growing popularity of rigid flex PCB technology in mission-critical aerospace, medical, and military applications has generated a high demand for UL 94 V-0 recognition among PCB fabricators in order to demonstrate the safety of their products and comply with insurance carrier requirements. To obtain this qualification for their customers, rigid flex PCB fabricators tend to use one of the following three approaches:

  • Submitting individual constructions.One option is to submit the constructions for UL recognition one material set at a time. This can become an extremely expensive and time-consuming process, especially if changes in the product’s materials or configuration are required after submission. Even slight material modifications after obtaining the initial certification will disqualify the part from UL recognition.
  • Specifying UL 94 V-0-rated materials.Some fabricators attempt to work around the individual sampling and testing requirements by specifying that the board be constructed with UL 94 V-0-certified materials. The error in this approach is that it does not translate to UL certification of the resulting PCB board and fails to meet insurance carrier requirements.
  • Mixing and matching individually certified constructions.Less informed board fabricators sometimes make the faulty assumption that individually certified flexible circuit constructions and rigid board constructions can be mixed and matched without testing and verifying the resulting new constructions. However, UL’s letter of recognition clearly states that any changes in construction after the product was originally evaluated will invalidate the UL mark.

Because of Printed Circuits’ comprehensive UL 94 V-0 qualification for rigid flex circuits, customers can now have a single source for fully-compliant circuit boards that meet their insurance carrier requirements. The majority of constructions can be certified immediately, eliminating the expensive and lengthy process of submitting and testing individual board constructions.

UL Certified Rigid Flex PCBs at Printed Circuits

With over 38 years of expertise in rigid flex PCB design and construction, Printed Circuits has developed an expertise in creating fail-proof board solutions for a wide range of demanding applications. Our UL 94 V-0 recognition on most popular rigid flex PCB designs provides buyers and designers with immediate access to UL-certified boards without the usual costs and delays. As demonstrated by our prestigious certifications and accreditations, we are committed to producing high-quality products and meeting stringent industry standards.

For additional information regarding rigid flex PCBs and our specific design and fabrication capabilities, please see the following resources:

To learn more about UL 94 V-0 certification or about Printed Circuits’ rigid flex PCB capabilities, reach out to us or request a quote today.

The History of PCBs

With the expansion of computer technology and electronics into virtually every aspect of our lives, it is easy to dismiss or disregard the foundation which they are built upon: printed circuit boards, or PCBs. Although they have become ubiquitous in our daily activities, electronics and their components have only been around for about a century. The printed circuit boards (PCBs) used in today’s electronics equipment were first designed and developed in the 1930s.

In 1936, Austrian inventor Paul Eisler developed the first PCB to operate a radio system, based on a circuit design originally patented by Charles Ducas. The technology was quickly picked up by the United States military and used in proximity fuses during World War II. The technology was released to the public in 1948, and printed circuit boards, also known as printed wiring boards (PWBs), started to evolve.

In order to help you follow the history of PCB boards, here we provide a timeline that overviews the primary discoveries, changes, and breakthroughs that have made PCBs what they are today.

a person working on a printed circuit board

PCBs Throughout the Years

The first PCBs are nearly unrecognizable compared with modern designs. The fundamental premise was to create an electrical path on an insulated substrate to facilitate the control and movement of electrical current. Over the years, numerous changes and adjustments were made to improve upon the concept. Material developments and computerization aided the continued evolution of the PCB into multi-layered boards, flexible circuits, rigid-flex hybrid boards, and miniaturized designs used in modern electronics.

PCB Evolution Timeline

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The History of PCBs

  • 1925: Charles Ducas, an American inventor, patents the first circuit board design when he stencils conductive materials onto a flat wooden board.
  • 1936: Paul Eisler develops the first printed circuit board for use in a radio set.
  • 1943: Eisler patents a more advanced PCB design that involves etching the circuits onto copper foil on glass-reinforced, non-conductive substrate.
  • 1944: The United States and Britain work together to develop proximity fuses for use in mines, bombs, and artillery shells during WWII.
  • 1948: The United States Army releases PCB technology to the public, prompting widespread development.
  • 1950s: Transistors are introduced to the electronics market, reducing the overall size of electronics, and making it easier to incorporate PCBs and dramatically improving electronics reliability.
  • 1950s-1960s: PCBs evolve into double-sided boards with electrical components on one side and identification printing on the other. Zinc plates are incorporated into PCB designs and corrosion-resistant materials and coatings are implemented to prevent degradation.
  • 1960s:  The integrated circuit – IC or silicon chip – is introduced into electronic designs, putting thousands and even tens of thousands of components on a single chip – significantly improving the power, speed, and reliability of electronics that incorporate these devices. To accommodate the new IC’s the number of conductors in a PCB had to increase dramatically, resulting in more layers within the average PCB.  And at the same time, because the IC chips are so small, the PCBs begin to grow smaller, and soldering connections reliably becomes more difficult.
  • 1970s: Printed circuit boards are incorrectly associated with the environmentally harmful chemical polychlorinated biphenyl, which was also abbreviated as PCB at the time. This confusion results in public confusion and community health concerns. To reduce confusion, printed circuit boards (PCBs) are renamed printed wiring boards (PWB) until chemical PCBs are phased out in the 1990s.
  • 1970s – 1980s: Soldermasks of thin polymer materials are developed to facilitate easier solder application onto the copper circuits without bridging adjacent circuits, further increasing circuit density. A photo imageable polymer coating is later developed that can be applied directly to the circuits, dried, and modified by photo exposure afterward, further improving circuit density. This becomes a standard manufacturing method for PCBs.
  • 1980’s:  A new assembly technology is developed called surface mount technology – or SMT for short.  Previously all PCB components had wire leads that were soldered into holes in the PCBs.  These holes took up valuable real estate that was needed for additional circuit routing.  SMT components were developed, and quickly became the manufacturing standard, that were soldered directly onto small pads on the PCB, without needing holes.  SMT components proliferated quickly becoming the industry standard, and worked to replace through hole components, again improving functional power, performance, reliability as well as reducing electronic manufacturing costs.
  • 1990s: PCBs continue to decrease in size as computer-aided design and manufacturing (CAD/CAM) software becomes more prominent. Computerization design automates many steps in PCB design, and facilitates increasingly complex designs with smaller, lighter components. The component suppliers work simultaneously to improve the performance of their devices, reduce their electrical consumption, increase their reliability, while at the same time reducing cost.  Smaller connections allow for rapidly increasing PCB miniaturization.
  • 2000s: PCBs have become smaller, lighter, much higher layer counts and more complex. Multi-layered and flexible circuit PCB designs allow for vastly more operational functionality in electronic devices, with increasingly smaller and lower cost PCBs.

Printed Circuit Boards Today

Today, printed circuit boards have outlived the stigma of chemical PCBs and are openly referred to as PCBs without confusion. This is largely due to the phasing out of chemical PCBs over the past four decades. The terms printed circuit board and printed wire board (PWB) are now used interchangeably in the industry, though printed circuit board is now the more common term.

As printed circuit boards continue to evolve, they can be expected to grow ever smaller and more complex. The latest innovation in PCB technology—the rigid flex PCB—combines the complexity and reliability of a hardboard circuit with flexible layers that are incorporated into the rigid structure. With these combined layers, rigid-flex PCBs are smaller, thinner and can fit into unusually shaped or especially small products.

The Latest PCB Technology by Printed Circuits

Since 1977, Printed Circuits has been at the forefront of PCB technology. We pride ourselves on our ability to provide the highest quality PCBs in the industry, and each of our rigid flex PCBs undergoes rigorous quality assurance testing to ensure that they meet and exceed industry standards. Our sizable 55,000-square-foot manufacturing facility is centrally located in Minneapolis, Minnesota, a hotbed of flexible circuit experts and resources.

To learn more about our cutting edge rigid flex PCB capabilities, contact us today or request a quote.

How to Reduce Rigid Flex PCB Costs

Rigid flex printed circuit boards (PCBs) are highly versatile circuit boards that incorporate aspects of both hardboard and flexible circuits. They are typically composed of multiple layers of rigid circuit boards with layers of flexible circuitry buried within the hard boards.

Although rigid flex PCBs come at a higher cost than rigid PCBs, they are more versatile and easier to tailor to the needs of specific applications. Rigid flex PCBs are particularly useful for militaryaerospace, and medical applications, where they exhibit resilience to high levels of shock and vibration. They are easier to assemble into precise applications, and their smaller and more flexible configuration makes them well suited to electronics where circuit weight and space are of particular consideration.

rigid flex boards are used in the Bell Boeing helicopters

When appropriate, cost-saving measures can be exercised to make sure you are still able to get the best value from rigid flex PCBs. The number of circuit layers, materials used, and design processes can all be tailored to meet the needs of your application.

Rigid Flex PCB Cost

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How to Reduce Rigid Flex PCB Costs

Rigid flex PCBs are approximately seven times more expensive than an equivalent rigid PCB, largely due to the raw materials required, and in general lower overall yields.

Rigid flex PCB’s use materials that are common to hard board and flexible circuit PCB manufacturers – core, prepreg, copper foil, flexible laminates, coverlayers and bondplies.  But some are unique to rigid flex manufacturers and cost more than traditional PCB materials.

One of the most critical components to successful rigid flex manufacturing is the use of no or low flow prepregs.  No flow prepregs are necessary to prevent the flow of epoxy or polyimide resin out onto the flexible sections of the boards.  They flow enough to go to the edge of the rigid, without flowing out onto the flex arms.

No flow prepregs generally cost about 10X traditional FR4 and polyimide prepregs.  Additionally, they are only available in two glass fabrics – 106 and 1080, which are very thin.  Rigid flex manufacturers do not have the option of using some of the lower cost, and thicker fabrics, such as 2113, 2313, 2116, 1652 and 7628 because they are not available in no flow variants. Consequently, rigid flex manufacturers use a more expensive ply of prepreg, and at the same time need to use more sheets to glue the final composite package together.

Also, because it is a no flow resin, it is generally risky to use a single ply of prepreg, typically utilized by hard board manufacturers to reduce board costs.  Two plies are usually essential to assure adequate encapsulation of the internal circuitry – another factor that increases cost of rigid flex designs.

 

rigid flex board with the materials showing

One cost driver in rigid flex manufacturing is the flexible copper clad laminates within the package.  There are many different types of flexible laminates in the World – polyester, PEN, polyimide, and even paper, etc.  Some are made with adhesive systems to bond the copper onto the base film, and some are not.  Rigid flex manufacturers to improve yield, use almost exclusively adhesiveless laminates with polyimide base materials – generally the most expensive flexible laminates available.  Additionally, controlled impedance designs, generally require thicker polymide films, to make the impedance circuits function properly.  Those materials come at an exponentially higher cost than the thinner materials.

Rigid flex boards are built in separate components and then assembled into the final board – adding processing steps and complexity, which increases cost.  In general, slower, more conservative and intentional manufacturing methods are used by rigid flex fabricators to achieve better manufacturing yields.

The last thing that impacts the cost of rigid flex boards is overall manufacturing yield.  Rigid flex boards combine materials with very dissimilar dimensional stability characteristics.  Getting those dissimilar materials to register to one another requires experience, specialized equipment and software tools.  Even with those though, yields in rigid flex manufacturing are inherently lower than hard boards or conventional flexible circuits.

The overall cost of rigid flex PCB manufacturing can, therefore, be reduced by choosing materials carefully and tailoring the material set to the specific needs of the application. The less material used, the greater the reduction in manufacturing costs. We recommend working closely with your rigid flex PCB manufacturer to find out if raw material costs can be streamlined for your specific needs.

For a good starting point, for designing low cost rigid flex designs, consult our Valu Build Brochure that is available here.  The Valu Build program gives material layups and suggestions to provide you with optimized cost solutions for your design.

Minimizing Rigid Flex PCB Design Costs

You can further lower the cost of rigid flex PCBs by tailoring the material to minimize the layers, thickness, and overall costs. Some of the major considerations that will affect the cost of your PCB design include:

Keep overall layers to a minimum:  Reducing the number of layers in your design, reduces the number of plies of prepreg required to bond your board together.  At the same time, fewer layers optimize the ability of the manufacture to improve manufacturing yields – both of which reduce your overall cost.

Keep flexible layers to a minimum:  The flexible laminate is more expensive than the rigid laminates.  Limiting the number of layers of flexible circuits, reduces your overall cost for the board.  The flexible layers are constructed separately from the final rigid flex board, which also adds to their cost.  Reducing the layers of flexible circuitry on your design, lowers your overall package cost.

Use rigid board laminates to achieve overall thickness:  If you are attempting to achieve a specific overall thickness, try to do so using the rigid board laminates, rather than additional plies of no flow prepreg or flexible laminates. The rigid laminates are the lowest cost material in the construction.

Limit controlled impedance requirements:  In high speed designs, it is tempting to define all the impedance values that you wish to achieve.  And this is fine, and you should employ your fabricator to help model all the impedance values you desire.  However, the print should list only the impedance traces that you want tested.  With rigid flex designs and test coupons required for the flexible sections as well as the rigid sections, the impedance coupons can get very large very quickly, removing parts from the production panel. It is wise to model and test only those impedance values your design truly needs.

Have all flexible arms in the design terminate in rigid boards:  Often rigid flex designers want one or more arms to end in a flex cable, typically for mating with a zif connector, or other device.  They do not desire the thickness or rigidity of the hard board in these sections. To achieve this feature though, the rigid flex manufacturer must incorporate a technique called “pouching” to protect the flex arm, during outerlayer manufacturing.  Pouched rigid flex boards require a lot of extra hand processing to build them successfully and should have strain relief beading applied to the rigid to flex transitions area – a subsequent hand applied material.  Having all flexible arms terminate in rigid boards affords you the lowest possible cost for your design.

Specialized processing:  There are techniques that are very common to rigid board designs that are much more difficult to achieve reasonable yields in rigid flex designs.  Because they are difficult to achieve, they create lower overall manufacturing yields, that increase the cost of your part.  Some of the most common elements are via in pads requiring filled vias, dual surface finishes such as ENIG and electroplated nickel gold or hot air leveled solder, buried, blind and laser vias, innerlayer copper thicknesses greater than three ounces, blue and black soldermask, and V scoring can all present challenges for your fabricator.  Consult your fabricator for advice on what they would suggest for improving the cost of your design.

Manufacturing Cost Considerations for Rigid Flex PCBs

In addition to optimizing material usage and design parameters, the configuration of the PCB can be simplified to further reduce manufacturing costs. The size, shape, complexity, and configuration of a board will affect the cost of materials and assembly. Any additional plated slots, edges and other customized design requirements will reduce yield and further inflate the cost.

Early involvement of the fabricator in the product design process allows the fabricator to produce PCBs optimized for the end application, without the need for costly adjustments or redesigns. A full assessment of available manufacturing options can be conducted at the beginning of the design process. This careful planning will ensure the design is optimized for use in the desired applications, a successful first time build, while accounting for expected product variations.

Affordable Rigid Flex PCBs From Printed Circuits

Although more expensive than traditional rigid counterparts, the manufacturing costs of rigid flex PCBs can be significantly reduced using thoughtful engineering that reduce unnecessary complexity and material usage. In addition, the savings in product design, logistics, and assembly make rigid flex PCBs a cost effective option.

For more than 40 years, Printed Circuits has been providing cutting-edge PCB technology for customers around the world. We are dedicated to providing the highest quality rigid flex and flexible circuits in the industry. To learn more about reducing rigid flex PCB costs, contact us today.

The Differences Between Rigid, Flex, and Rigid-Flex Printed Circuit Boards

Printed circuit boards (PCBs) connect electrical components together using discrete wiring, resulting in a complete and functional unit. PCBs can be as simple as one or two layers of copper circuits, but are far more likely to have many layers of circuitry. The layers are necessary for the designer to “route” all of the circuits between the components – where one, two, or even eight layers of circuitry may not be enough to complete their design and make all of their connections.

While all circuit boards perform the same basic function as a substrate for the electronic components, the design and materials of their construction are the key distinguishing points. Circuit boards are custom-tailored to their particular application.

The three main types of PCBs are rigid boards, flexible circuits (or flex), and rigid-flex. This blog post will provide a clearer understanding of the differences and similarities between each type of PCB.

Rigid PCB vs. Flex PCB

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The Differences Between Rigid,Flex,and Rig

The most notable difference between rigid PCBs and flex PCBs can be inferred from their names. Rigid PCBs are inflexible, while flex PCBs can be bent or otherwise shaped to fit inside the designated system. Flexible circuits, when designed correctly, can also be flexed for hundreds of thousands of cycles repeatedly without failure. The increased versatility of flex boards typically comes at a higher cost, but they are essential for applications with limited space requirements, such as consumer electronics, medical devices, space and automotive applications.

Rigid circuit boards are very popular largely due to their low cost. In conventional electronics, and particularly in consumer electronics, with greater space availability, manufacturers can save significantly by using rigid circuit boards. However, flexible PCBs are beginning to siphon market share from rigid circuit boards due to their versatility, among other advantages, such as:

  • Flexibility. Flexible circuits can be bent, folded, and even creased to fit the end application, giving the designer the ability to have the circuitry fit the device, rather than the end device being built around the electronics and circuit boards. Flexible circuits are ideal for wearable electronics, for example.
  • Connectivity. Flexible circuits provide greater connectivity between other circuit boards, electronic components and the user interface in electronic packaging. They can even provide connectivity in dynamic flex applications where the flexible circuit needs to flex continuously over the life of the device, so they are used extensively in laptop computers, foldable electronics, and display connectivity.
  • Reduced weight. A lower-weight circuit board results in a lighter end product, which is essential in today’s electronics market where small, lightweight devices are preferred by electronic device designers and consumers. Flexible circuits are ideal for unmanned vehicles and drones, due to their very light weight.
  • Durability. While rigid PCBs are typically thicker and fairly strong, flex PCBs absorb shocks and vibrations much more effectively than rigid PCBs. This contributes directly to long-term reliability, product life and functionality. Flexible circuits are used extensively in medical electronics, missile guidance systems, weapons, satellite and other applications requiring excellent environmental survivability.
  • Resistant. While rigid PCBs are at risk of damage or warping from heat, chemicals, or radiation, flex PCBs are much more resistant to these detrimental environments. This explains their wide application in today’s automotive electronics.

With the differences between rigid and flexible PCBs in mind, we will now compare these PCB types with their hybrid counterpart, the rigid-flex PCB.

Dynamic Flex - rigid flex pcb

Rigid-Flex PCB vs. Rigid and Flex PCB

As its name suggests, the rigid-flex PCB is a hybrid of both rigid and flex PCBs, and features the great qualities of both while eliminating many of their individual limitations. A rigid-flex PCB incorporates flexible materials in conjunction with rigid materials by layering flexible circuit substrates inside of the rigid circuit board materials, ultimately combining the versatility of flexible circuits with the stability, strength and circuit routing densities of rigid PCBs. This hybridization opens up a spectrum of possibilities for much more complex and mechanically challenging designs.

Rigid-flex PCBs are a means to streamline the electronic design, by eliminating flexible cables, connectors and discrete wiring. The electrical performance of a rigid flex PCB is enhanced compared to its counterparts, because the circuits are integral to the overall construction. All of the electrical and mechanical connections are internally contained within the rigid-flex PCB, providing the electronics designer with much improved service reliability and electrical performance.

While they do typically arrive at a higher cost than their flex and rigid board counterparts, the reliability, weight reduction, strength and space-saving advantages of rigid-flex boards are often ideal in certain applications, and outperform any other electronic packaging techniques. Ultimately, rigid-flex PCBs provide the best benefits of rigid and flex PCBs in one solution. Applications where rigid flex PCBs excel are:

  • High-reliability applications. If an assembly will be exposed to excessive or repeated shock, or high vibration environments, connectors with flexible cables are more likely to fail. Rigid flex PCBs provide great reliability even when subjected to extreme vibration and shock applications.
  • High-density applications. Within a small enclosure, it’s sometimes impossible to accommodate all of the cables and connectors that an electronic PCB design would require. Rigid flex boards can fold into very small, and very thin profiles, offering substantial space savings in these instances.
  • Five or more rigid boards. If your application will ultimately involve five or more rigid boards connected to one another with flex cables, an integrated rigid flex solution is often the optimal and most cost-effective choice.

mri machine uses rigid flex pcbs

Rigid-Flex PCB Capabilities at Printed Circuits

The applications of rigid-flex PCBs are extensive, and their implementation is growing across industries ranging from automotive, medical, military, and many more.

Based in Minneapolis, Printed Circuits is centrally located in one of the world’s largest flexible circuit manufacturing hubs. With more than 40 years of manufacturing experience in advanced circuitry, we pride ourselves on the quality and precision of our rigid-flex products and services. For more information about rigid, flex, or rigid-flex PCBs for your application, contact us today to learn more.

How to Choose the Right Rigid Flex PCB Manufacturer

How you package your electronic device is one of the more critical decisions you can make as a designer.

There are times when a conventional hardboard is the best, most robust solution at the lowest possible cost. Then there are times when a flexible circuit will provide you with greater creative control in your design – allowing the function to follow your desired form factor.

But, there are certain cases where neither a conventional hard board nor a flexible circuit is the ideal fit for a given electronic application. Conventional hard boards provide you with increased routing density – but no flexibility. Flexible circuits are flexible, but have limited routing density relative to hard boards, usually just a few layers or less, and often limited by stiffener placement as well.

To get the most routing density and still get some level of flexibility/folding of your design, rigid flex is the best packaging solution.

Rigid flex printed circuit boards (PCBs) serve as an innovative and versatile solution for more complex circuit designs. These boards combine the characteristics of both flexible and rigid circuit boards, meaning that they can be folded to fit into a space or device, or used in applications where they must be folded repeatedly (known as “dynamic flex”). In either case, the rigid portions of the circuit provide high circuit densities as well as a stable and rigid surface on both sides of the board for your components. This combination is ideal for ensuring structural integrity even throughout highly demanding environmental conditions.

rigid flex pcb

Some applications where rigid flex circuits excel over conventional hard board and flexible circuits:

  • High vibration environments – where traditional connectors and flex cabling will fail in time
  • High shock environments – the flexible circuits are buried within the hard boards, for the ultimate in packaging reliability, withstanding tens of thousands of g’s without failure
  • Ultralight packaging – rigid flex circuits can be built with very thin, ultralight components providing you with circuit density AND lightweight design
  • Lower cost – when your design includes four or more hardboards connected with connectors and/or flexible cables, a rigid flex design can often cost less (see our rigid flex cost estimator)

Once you have decided to investigate rigid flex packaging for your design, it is time to locate a fabricator who can work closely with you to make your concept a reality. Unlike with conventional hard boards or flexible circuit designs, the relationship between the rigid flex designer(s), the fabricator and even the assembler is MUCH more collaborative. Remember, your board will be for a three-dimensional application, requiring mechanical engineering skills. It also may have electrical requirements with dissimilar materials, requiring electrical engineering skills.

Mechanical engineers, electrical engineers, PCB layout engineers, CAD engineers, assembly line engineers and your fabricator’s front-end engineering department work together to produce a successful rigid flex PCB product.

Material selection, physical stack up, signal integrity requirements and design rule constraints all become more critical in rigid flex design. As there are many factors to consider, it is crucial to select a PCB manufacturer who will carefully analyze your application so that your needs are adequately met.

Here are some starter guidelines on how to successfully partner with the right rigid flex manufacturer for your needs.

How to Find the Right Rigid Flex PCB Manufacturer

When selecting a rigid flex PCB manufacturer, consider these essential factors:

  • Experience and expertise. Manufacturing rigid flex PCBs successfully increasingly requires higher-end equipment and software that analyzes and predicts material movement. Therefore, selecting a manufacturer with ample proof of each of these resources is crucial. Additionally, while many PCB manufacturers offer rigid, flex, assembly, and rigid flex boards, it is important to partner with one with an extensive expertise in rigid flex to ensure they have the necessary skills and knowledge to meet your project requirements and standards.
  • Capabilities for PCBs with UL 94 V-0 flame ratings. Another way to assess a potential rigid flex PCB partner is to find out whether they offer boards with UL 94 V-0 ratings. This is especially important for medical and industrial applications, or anyone whose insurance carrier requires UL certification as a condition of coverage. Additionally, UL ratings are notoriously difficult to obtain with rigid flex constructions, and it saves a lot of time and effort if your manufacturer can provide pre-approved, UL-certified rigid flex PCBs.
  • Impedance requirements. Modeling and manufacturing impedance-controlled circuits on rigid flex boards is more demanding than doing so for flexible circuits or hard boards. Impedance circuits that transverse the flexible areas of the part and the rigid sections need to be modeled for both structures. Dielectric values supplied by material manufacturers can be inaccurate, and online free modeling software usually returns erroneous values, and can only model simple trace to plane structures. If impedance is important or critical to your design, you need to find a supplier who will work with you in the beginning to model the requirements in your board, and one that has the software to help you model your requirements. It is also important to choose someone who will test your boards at the end of your build to make sure they match the impedance values that you want. Controlled impedance, without testing the results, is not really controlled at all.

At Printed Circuits, we specialize in providing rigid flex PCB solutions. To further expand our product offerings and capabilities, we obtained UL 94 V-0 flame ratings for an extensive, representative sampling of our constructions. By doing so, we can offer cost-effective, fully-compliant boards without the expense and time required to get individual certification. We have the software, material libraries, experience, and expertise to help you achieve the impedance values you want for your design, and then have the test facilities to verify that we met your requirements.

Inside a Clinac® Radiation Machine

Cost Factors to Consider

While experience and dedication to quality are among the most critical factors in selecting a rigid flex provider, cost should also be considered.

In general, it is well-known that rigid flex PCBs are more expensive than either hard boards or flexible circuits. The raw materials (such as no flow prepreg, adhesiveless flexible laminates) and specialized construction components for specific operating requirements (such as thicker flex dielectrics for impedance layers) are key contributors to the higher cost involved. However, there are constructions and methods that you can use to limit those costs.

The Printed Circuits team created a guide—Valu Builds for Rigid Flex—to help you navigate the process of designing and selecting cost-effective PCBs. It provides the lowest cost, as well as the most robust and stable rigid flex design guidelines. Additionally, you can check out our Rigid Flex Cost Estimator to receive a cost estimate of your rigid flex design before you start. It will give you a quick go/no go estimate on what your design might cost in low volume production. While not an exact quote, this tool is designed to make it simple to determine whether a rigid flex PCB is feasible for your project.

Contact Printed Circuits for Your PCB Needs

If you have determined that a rigid flex PCB would be a great choice for your project, there are several factors to consider before partnering with a manufacturer, including experience, available resources, manufacturing capabilities, and cost requirements.

At Printed Circuits, we understand that when customers opt for rigid flex solutions, they are looking for excellent quality and great long-term value, which is why we have spent decades refining our equipment, engineering support, and technology to optimize it for rigid flex packaging solutions. Since 1997, we have served the medical, aerospace, military, and industrial and commercial industries with high reliability rigid flex PCBs.

Our highly-collaborative design process begins with design assistance services to help you create the design that suits your needs. Our technicians and state-of-the-art equipment then build your circuit to your exact specifications. We are certified to the military performance specification ISO 9001:2015, ITAR, and the JCP 4532 standard, so you can trust us to provide high-quality PCBs.
Contact us or request a quote today to see how our rigid flex PCB solutions can suit your unique project and design needs.

How to Choose the Right Rigid Flex Manufacturer