All About Flex: FAQs for Extended Length Flexible Circuits

Extended length flexible circuits are larger than typically offered sizes in the interconnect industry. The length of these oversized circuits can be anywhere from two feet to 10 feet or longer. A long, continuous flexible circuit can offer design advantages over using normal sized circuits where multiple connections and connection assembly steps are required. By eliminating connectors and the assembly labor required for the connections, the long length circuit can be lighter, more flexible, lower overall cost and more reliable. At All Flex, we have branded our extended length circuits as Maxi-Flex.

The following are some common questions we have received regarding extended length circuits.

Q. Why are there so few flexible circuit fabricators that offer extended length circuits?
A. Most of the standard equipment used in the industry is geared toward 12” x 18” or 18” x 24” panel sizes, based on standard rigid board process technology. Oversized circuits are a relatively small niche within the industry and require custom fabrication equipment and techniques that many fabricators have avoided due to capital expense.

Q. What are the biggest challenges in producing an extended length circuit?
A.  There are a number of process steps where the standard equipment and tooling need significant modification. Many of the challenges are related to material handling. Since opens and shorts render a part useless, any defect in the length of a circuit reduces panel yield.

Q. In what applications are extended length circuits commonly used?
A. We see a variety of applications. Any application where having a long, thin, continuous interconnect system would be ideal. Unmanned aerial vehicles (UAV) and medical probing systems are a couple of applications driving existing demand, but like other flex circuit applications, demand is often generated by the imagination of a creative engineer.

Q. Can an extended length circuit have a multilayer construction?
A.  It is quite common for extended length circuits to have several layers, but limitations occur because of unique processing requirements. As a design layout consequence, the higher density region of the circuit may need to be confined to some subset area of the overall circuit size.

Q. Will feature-to-feature tolerances be different for extended length circuits?
A. Feature-to-feature specifications are often restricted to within small zones of an extended length circuit. Tolerances within smaller zones are similar to tolerances held on standard-sized circuits. Dimensional tolerances spanning the length of the circuit will need to be reviewed on a case-by-case basis.

Q. Is impedance control offered on extended length circuits?
A. Yes, it is very common for extended length circuits to be built to meet impedance specifications. Impedance control often requires thinner copper and thicker dielectric. As circuits become lengthy, material construction options are important considerations. Since oversized circuits are usually built on laminates that have been fabricated in a continuous roll process, limitations in thicknesses and constructions are possible.

Q. What are the line width and spacing limitations for extended length circuits?
A.  Like all good questions about capability, the answer is usually “it depends.” The probability of a circuit trace having a flaw is a function of its length and width. As trace runs get lengthy, and especially if combined with multiple traces, the chance of a circuit flaw increases and yield can be an issue. We have produced extended length circuits with <3 mil lines and spaces.

An extended length circuit can be fully customized to meet most requirements. These circuits provide customers with a single interconnect solution for physically large electronic systems and can be built in a variety of customized constructions including heater circuits.

 

Dave Becker is vice president of sales and marketing at All Flex Flexible Circuits LLC.

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2017

All About Flex: FAQs for Extended Length Flexible Circuits

04-27-2017

Extended length flexible circuits are larger than typically offered sizes in the interconnect industry. The length of these oversized circuits can be anywhere from two feet to 10 feet or longer. A long, continuous flexible circuit can offer design advantages over using normal sized circuits where multiple connections and connection assembly steps are required.

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All About Flex: Flex Circuit Stiffeners

04-13-2017

Many flexible circuit designs require selectively bonded stiffeners…they’re just too flexible! Stiffener materials can be any number of materials, but they are usually polyimide films or FR-4 glass/epoxy substrates and are available in a wide variety of thicknesses. Three-dimensional metal stiffeners may also be attached for thermal dissipation properties. The purpose of a stiffener is to rigidize or structurally support discrete areas of the flexible circuit.

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All About Flex: Considering a Flexible Heater?

03-02-2017

Custom flexible heaters are available in an infinite variety of sizes, shapes and materials. The most common flexible materials are polyimide and silicone rubber. While silicone rubber has traditionally been thought of as the higher temperature flexible heater option, recent advances in polyimide-based materials have allowed high performance heater constructions to operate successfully at temperatures that exceed 250°C.

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All About Flex: Volume Considerations

02-16-2017

With any new electronic interconnection project, one immediate question the supplier will inquire about is program volume expectations. Customers often ask “What is your capacity?” with low-, medium- and high-volume having different meanings to different people.

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All About Flex: Creating a Flexible Circuit Cutline

02-02-2017

The perimeter dimensions of a flexible circuit are often referred to as the cutline. While rigid printed circuits are often rectangular and generally a less complex outline, the requirement for a flexible circuit to be an integrated part of the product packaging often involves unusual sizes, shapes and features in the circuit perimeter.

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All About Flex: Are Manufacturing Companies Susceptible to Ransomware?

01-12-2017

Every business (and every individual) needs to pay attention to cyber security. There are many sophisticated hackers throughout the world looking for ways to access or corrupt systems. While manufacturing companies have not been a common target, there are certainly risks that need to be considered.

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2016

All About Flex: Customer Acquisition

12-22-2016

The “Customer Acquisition” process can be thought of as consisting of three major segments: collection, selection and execution. While these sub-divisions should be considered as intimately interrelated, examining them as separate disciplines can be enlightening.

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All About Flex: Disruption in the Supply Chain

12-08-2016

Manufacturers need a highly dependable supply chain to successfully support their products. This is especially true of custom designed and built components, as many times, only one supplier is available for a component since tooling and development costs discourage dual sourcing.

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All About Flex: Packaging Flexible Circuits and Assemblies

12-01-2016

Many facets are involved in delivering a flexible circuit. During the quote and design phase, requirements are reviewed. So assuming the relevant product documentation was gathered, the salesperson turned around the quote, and the customer placed an order and parts were built, it’s all over, right? Not quite. One critical aspect that does not get much discussion is packaging and shipping.

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All About Flex: Non-Copper Flexible Circuit Applications

11-22-2016

While pure copper is the most common choice for flexible circuit fabrication, there are times a different metal is more suitable for an application. Copper is well known for its excellent electrical and thermal conductivity, but there are applications where the best thermal or electrical conductivity can be a disadvantage.

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All About Flex: Flex Circuit Specifications for Commercial and Military Applications

10-27-2016

Applications across the various markets for printed circuit boards can have significantly different specifications and performance requirements. Circuits for toys and games logically have lower performance requirements than those used in medical devices. IPC-6013 is an industry-driven specification that defines the performance requirements and acceptance features for flexible printed circuit boards.

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All About Flex: Five Characteristics of a Reliable Flexible Circuit Supplier

10-27-2016

Due diligence when selecting a source for a custom electronic product can be a critical sourcing procedure. Chains are only as good as the weakest link, and the electronic components assembled to create a marketable product need to combine into a robust solution.

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All About Flex: Flexible Circuit Prototypes

10-13-2016

Most electronic projects begin with at least one build of prototype parts before moving into volume manufacturing. But the definition of a flex circuit prototype can vary considerably from one project to another. In many cases, a prototype build is only a few parts used to verify form, fit and function, with engineering trying to determine if something actually works.

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Flex Circuit Specifications for Commercial and Military Applications

09-30-2016

Applications across the various markets for printed circuit boards can have significantly different specifications and performance requirements. Circuits for toys and games logically have lower performance requirements than those used in medical devices. IPC 6013 is an industry-driven specification that defines the performance requirements and acceptance features for flexible printed circuit boards.

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All About Flex: Lead-Free Soldering Flexible Circuits

09-23-2016

Ever since the European community adopted the RoHS directive in 2006, the U.S. electronics industry has been steadily increasing its use of lead-free solder. Medical was the first U.S. industry to go totally lead-free. Today, a significant percentage of electronics soldering is done with lead-free solder.

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All About Flex: FAQs on RoHS for Flex Circuits

09-02-2016

In 2003, the European Union (EU) adopted a standard called the Restriction of Hazardous Substances (RoHS), which restricts the use of certain materials in electronic products and electronic equipment. The intent is to reduce the environmental impact of known hazardous materials and has driven changes in manufacturing processes and materials used to manufacture a wide array of electronic products.

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2015

All About Flex: Embracing the Mess

12-03-2015

Marketing in the world of printed circuits is an important discipline, but I have learned it is better to be prepared with a nimble reaction than to expect the marketing department to consistently be successful in predicting the future. The path to the goal is often achieved much more quickly by making an early decision followed by a course correction rather than waiting for all the information.

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All About Flex: Flexible PCB: What’s in a Name?

11-12-2015

Flexible PCB is a common term that is synonymous with flexible circuits. While the term “PCB” is generally used to describe rigid printed circuitry, “flexible PCB” is a little contradictory because “boards” aren’t really flexible. Some companies, like All Flex, design and manufactures flexible PCBs, but not rigid PCBs. There are many similarities between the two, but also significant differences.

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Plated Through-holes in Flexible Circuits

10-29-2015

There is probably no more important feature than the plated through-hole (also called via or via hole) with regard to the reliability and integrity of a flexible circuit. The through-hole provides electrical connection between insulated layers and enables electrical functionality on double-sided and multilayer flexible circuits.

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Testing Flexible Circuits, Part 3: The Completed Flex Circuit

10-15-2015

Most flex houses perform a variety of tests on completed flexible circuits. The type, frequency, and complexity of these tests vary with customer and application. Test requirements are generally defined by the customer, but input is often solicited from the supplier during the quote process.

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Testing Flexible Circuits, Part I: Requirements and Procedures

09-17-2015

In this first of a three part series regarding tests for flexible circuits, I will examine overall requirements and procedures; the second installment will focus on raw materials, and the third and final part will focus on testing for bare flexible circuit and circuit assemblies.

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Catching Up to Yesterday

09-02-2015

Recently, KPMG, an international consultancy that operates as a network of member firms offering audit, tax and advisory services, came out with their 6th annual survey of manufacturing executives focusing on global manufacturing trends.

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The Butterfly Effect

08-20-2015

If a random initial disturbance from the wings of a butterfly can have a dramatic effect, just think what can be accomplished with intentional acts aimed at making sure our customers are receiving proactive attention.

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Is Wearable Technology Just a Fad?

08-13-2015

Wearable technology is in its infancy. The industry needs to mature and go back to basic marketing—finding a need and filling it. Flexible circuits have been around since the mid-1960s and have been successfully filling needs. Flexible circuits are ideal for wearable technology because they are thin and lightweight. As the marketing matures, the applications will come and flexible circuits will be there to fill the technical needs.

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Unique Single-Sided Flexible Circuits

08-06-2015

The number of iterations, sequences and combinations possible when manufacturing a flexible circuit can create unique product features to reduce hand assembly of wires, create switch contacts, or eliminate connectors. With minor alterations in basic processing steps, a flex circuit applications engineer can often imagine and configure a dramatically different flexible circuit.

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Agricultural Drones and Flexible Circuits

07-28-2015

According to MIT Technology Review, one of theTop 10 breakthrough technologies last year was the agricultural drone. I focused on drones in one of my recent columns, Flexible Circuits and UAV Applications, which briefly mentioned agriculture as one of the uses for drones.

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