All About Flex

April 12, 2018

All About Flex: Terms and Conditions

An issue that is frequently addressed by many of us in the printed circuit industry, and by others in the world of contract fabrication and assembly, is dealing with the “Terms and Conditions” in a purchase agreement or contract.

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March 28, 2018

All About Flex: ISO 9001 Basics

ISO 9001 is an internationally recognized standard that specifies requirements for a business’s or organization’s quality management system. Companies achieving ISO 9001 certification are audited to review compliance for systems to assure products or services are delivered with a consistent quality level and meet agreed upon specifications.

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March 08, 2018

All About Flex: FAQs on UL Listings for Flexible Circuits

The requirement for flexible circuitry recognition is driven by the end product specification as flexible circuits themselves are not sold directly to the consumer. The applicable UL spec for flexible circuits is UL796. The following are some common questions and answers relating to UL recognition.

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February 22, 2018

All About Flex: Avoiding Trace Fracturing in a Flexible Circuit

Flexible circuits are used in applications requiring millions of flex cycles. But this does not suggest they never experience failures due to flex life. In fact, occurrences of performance issues as the result of fractured traces have been experienced in a variety of applications. Solutions are often the result of design, construction, and feature location modifications.

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February 08, 2018

Polyimide vs. Silicone for Flexible Heaters

Flexible heaters are sub-divided into two primary technology platforms: etched-foil and wire-based technology. Wire-based (wire strands woven together or single strand wire) is the more common technology, with multiple customers offering a wide range of products.

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February 05, 2018

All About Flex: Copper Thickness Requirements for Flex Circuits

An end user will specify the copper thickness of a printed circuit for different reasons. The most obvious reason would be for current-carrying capacity, but copper thickness also directly impacts thermal performance and impedance. All these are vital properties impacting the functionality and reliability of a flexible circuit.

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January 04, 2018

All About Flex: Copper Grain Direction

Many materials have different characteristics depending upon the orientation of the material. For example, woven textile materials have a warp and a weft direction. The warp direction is the longitude direction and the weft is the transverse.

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November 15, 2017

All About Flex: Options for Purchasing Flexible Heaters

Flexible heaters represent a product technology generically described as thin and flexible heating elements used as attachments to various heat sinks to provide freeze protection, consistent temperatures, and thermal control from -80°C to +230°C and higher.

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October 30, 2017

All About Flex: More on UAVs and Flexible Circuits

The use of drones or unmanned aircraft vehicles (UAVs) is growing at a nearly exponential rate. This includes drones used by the government, private companies and hobbyists. If you have $100, you can find a long list of drones for purchase.

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October 19, 2017

All About Flex: Flexible Circuit Failure Analysis

Design reviews and early involvement by a circuit board fabrication house can minimize the possibility of field problems, but despite best efforts, there remain occasions when diagnosis of a poorly performing design is required.

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September 21, 2017

All About Flex: Flexible Circuits for Reusable Medical Products

Flexible circuits have been used in medical devices and medical instrumentation for several decades. Flex circuits and flexible heaters can be ideal solutions in applications requiring lightweight, continuous movement, and highly reliable interconnections that are biocompatible.

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September 12, 2017

All About Flex: Flexible Circuits and Man-Made Satellites

The first satellite was launched by the USSR in 1957. The U.S. successfully launched its first satellite, Explorer 1, in 1958 while announcing the intention to “win” the race to outer space. Today satellites serve many vital purposes.

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September 07, 2017

All About Flex: Using ZIF Connectors with Flexible Circuits

Zero insertion force (ZIF) connectors are probably the most popular flexible circuitry connector because they allow the circuit to be inserted and removed multiple times with very little mechanical wear on the copper traces.

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August 22, 2017

All About Flex: The Anatomy of a Flex Circuit Cutline

Numerous methods are used to create the cutline of a flexible circuit. With the various tooling options, the methods, process steps, tooling and technology are different. These differences affect the actual physics of cutting, and create slight variations on the circuit material.

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August 15, 2017

All About Flex: ITAR Registration

Vendors building product for the defense industry often stipulate a supplier needs to be ITAR registered. ITAR stands for International Traffic in Arms Regulations and is a program run by the U.S. government to control the export of defense-related technology to foreign countries.

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August 02, 2017

Successful Flex Circuit Assembly

Many contract manufacturers are reluctant to mix rigid and flexible circuits on the same assembly line as the handling and fixturing requirements can be quite different. Characteristics allowing a flexible circuit to be flexible can often present learning curve challenges when component or mechanical assembly is required. This article details some of the common issues experienced when assembling flexible circuits, and strategies to ensure reliable assembly.

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July 20, 2017

All About Flex: Button Plating on a Flexible Circuit

Button plating describes a fabrication process widely used in the flex circuit industry to selectively electroplate copper to the vias and onto the pads capturing the vias. The rest of the copper traces do not have plating. Another industry term used to describe this feature is pads only plating. Producing a circuit with this processing methodology requires two photolithography steps.

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July 17, 2017

All About Flex: Trends in the Medical Electronics Industry

The U.S. medical electronics industry has been one of the fastest growing industries over the past decade. Similarly, to the rest of the electronics world, growth has been accompanied by the adoption of significant new product technology and innovation.

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July 12, 2017

All About Flex: CAD for Flexible Circuits

CAD engineers take a CAD file that defines a single part and panelize the data by creating a nested pattern repeated across the panel. Reverse nesting and off-angle part placement may optimize material utilization, which is a constant cost concern. But this optimization needs to be balanced by ease of stiffener placement and component assembly.

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July 06, 2017

All About Flex: Flexible Circuit Component Assembly…and a Math Lesson

The market for rigid PCBs is estimated to be about 10X the market size for flexible printed circuits (FPCs). As a result, the equipment infrastructure is driven primarily by the needs of the rigid board market. This is true of both equipment used to fabricate the circuitry (image, etch, copper plate, AOI, etc.) and equipment used for component assembly (wave solder and SMT assembly).

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June 22, 2017

All About Flex: Etchback on Type 3 and Type 4 Flexible Circuits

Through-hole etchback is a requirement that is sometimes specified on medical, military and aerospace procurement documents for multilayer flexible circuits and combination multilayer flex/rigid board circuits. It specifically relates to the copper plated through-holes and the relative dimensions between the dielectric layers and copper layers.

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June 01, 2017

All About Flex: Back-Bared Flexible Circuits

Back-bared pad flexible circuits are a distinctive type of single-sided flexible circuit providing some advantages over more standard circuits. In the printed circuit industry, back-bared pad circuit designs are also referred to as dual-access or reversed bared.

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May 11, 2017

All About Flex: Origami Interconnection

Origami is the art of folding paper; it was believed to have originated in Japan, but historical evidence suggests it existed in several parts of the world during the same period. Origami artistry starts with a flat sheet of paper and by making a series of folds and creases, the result is a three-dimensional figure. Creating even just a simple figure takes imagination and a unique ability to visualize in three dimensions. Three-dimensional folding to fit into a multiplanar shape? Why does this sound familiar?

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April 27, 2017

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.

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April 13, 2017

All About Flex: Flex Circuit Stiffeners

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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March 02, 2017

All About Flex: Considering a Flexible Heater?

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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February 16, 2017

All About Flex: Volume Considerations

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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February 02, 2017

All About Flex: Creating a Flexible Circuit Cutline

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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January 12, 2017

All About Flex: Are Manufacturing Companies Susceptible to Ransomware?

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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December 22, 2016

All About Flex: Customer Acquisition

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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December 08, 2016

All About Flex: Disruption in the Supply Chain

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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December 01, 2016

All About Flex: Packaging Flexible Circuits and Assemblies

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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November 22, 2016

All About Flex: Non-Copper Flexible Circuit Applications

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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October 27, 2016

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

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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October 27, 2016

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

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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October 13, 2016

All About Flex: Flexible Circuit Prototypes

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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September 30, 2016

Flex Circuit Specifications for Commercial and Military Applications

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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September 23, 2016

All About Flex: Lead-Free Soldering Flexible Circuits

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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September 02, 2016

All About Flex: FAQs on RoHS for Flex Circuits

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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July 29, 2016

All About Flex: Creating Via Holes in Flexible Laminates

Almost all double-sided and multilayer flexible circuits require through-holes or vias to enable an electrical connection between conductive layers. Creating a reliable plated via requires several critical steps. The first one is creating the through-hole.

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June 28, 2016

All About Flex: Imaging Methods for Etch Resist, Part 3: LDI

When LDI technology was first introduced around 20 years ago, throughput was an issue. LDI was often restricted to low volume or prototype runs. Subsequent advances in equipment as well as faster acting photoresist have made it practical for high volume circuit fabrication.

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June 23, 2016

All About Flex: Common Flex Circuit Surface Finish Requirements

Copper is a unique metal and has been proven with the test of time in an incredible array of printed circuit and electrical wiring applications. It is highly conductive, has good flexibility properties, can withstand high temperatures and has good chemical resistance.

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June 16, 2016

Plating Process Options for Flexible Circuits

Plating copper through-holes or vias is a requirement for double-sided and multilayer circuits. In a previous column we discussed the plating process; specifically copper seed coating using electroless copper and Shadow® plating, which is then followed with an electroplating process.

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May 16, 2016

Imaging Methods for Etch Resist, Part 2: Photoimaging

This is the second of three columns describing typical methods for creating an etch resist for fabrication of printed circuits. Photoresist can come in the form of a liquid that gets coated on the substrate or as a dry film that is laminated. Liquid and dry film resist can be positive-acting or negative-acting.

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May 30, 2016

All About Flex: Flexible Circuit Fabrication and Cleanroom Manufacturing

Facility cleanliness is a vital part of process control for flexible circuit fabricators. As higher density requirements continue a relentless drive toward finer traces and spaces, particles and foreign material can cause problems in a number of operations.

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May 16, 2016

All About Flex: Flexible Circuits and Kaizen Events

All Flex uses a variety of different tools and techniques in its continuous improvement efforts. A Kaizen event or Blitz is one technique that has resulted in significant improvements in our yields, productivity and customer satisfaction.

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April 28, 2016

All About Flex: Imaging Methods for Etch Resist, Part 1

Imaging is a major process step in creating a copper circuit or flexible PCB. In single-sided circuit fabrication, the imaging process creates the resist pattern that protects the copper from the etchant. It is critical that this pattern precisely define the circuit traces, as issues with imaging will transfer to the subsequent processes.

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April 21, 2016

All About Flex: Lean Manufacturing and NPIP for Flexible Circuits

Many companies are familiar with lean manufacturing concepts and have successfully used these techniques to improve manufacturing processes. Lean techniques, while most often used in printed circuit fabrication and assembly operations, can also be applied to nonmanufacturing processes. One such process is new part number introduction (NPIP).

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April 13, 2016

All About Flex: Why Copper is Ideal for Flexible Circuitry

Copper is the second-most conductive metal (in pure form). The copper used on flexible circuits can be formed by a number of methods such as electro-deposition (ED), rolling/annealing, or a combination of the two. The conductivity of copper by volume on a flexible circuit is not exactly the same as pure copper, but it is quite close.

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March 17, 2016

All About Flex: Using Aluminum in Flexible Circuits

Aluminum circuitry can be a cost-effective, lighter weight alternative to its copper cousin, but there are significant limitations to consider. Aluminum would be a poor choice for applications requiring component assembly, multilayer configuration or high density. Long term compatibility with the application environment and possibilities of metal corrosion should be properly considered when this metal becomes a circuitry candidate. The supply infrastructure is more limited when aluminum becomes the foil of choice.

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March 10, 2016

Three Emerging Trends That You Can Bet On

Flexible circuits are light weight, require minimal space, can be bent into “origami” shapes for adoption to a wide range of applications. These utilitarian features give electronic designers endless options for the new and exciting products that will soon become part of our everyday life.

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January 21, 2016

High-Temperature Performance Flexible Circuits

Markets requiring thermal exposure at elevated temperatures include down-hole oil drilling, semiconductor processing, medical diagnostics and a multitude of military/aerospace requirements. But a limitation of flexible circuitry has been performance at extremely high temperatures.

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December 03, 2015

All About Flex: Embracing the Mess

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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November 12, 2015

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

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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October 29, 2015

Plated Through-holes in Flexible Circuits

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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October 15, 2015

Testing Flexible Circuits, Part 3: The Completed Flex Circuit

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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September 17, 2015

Testing Flexible Circuits, Part I: Requirements and Procedures

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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September 02, 2015

Catching Up to Yesterday

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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August 20, 2015

The Butterfly Effect

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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August 13, 2015

Is Wearable Technology Just a Fad?

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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August 06, 2015

Unique Single-Sided Flexible Circuits

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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July 28, 2015

Agricultural Drones and Flexible Circuits

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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July 23, 2015

Eliminate Connectors with Sculptured Flex

Any time you eliminate a component, hidden costs are eliminated, such as the cost of stocking, tracking and managing the supply chain for that part number. When designing an electronic package, don’t assume that you need a component for every connection point. Sculptured flex will give some options that can make your electronic package, lighter, less costly, more reliable, and take up less space.

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July 22, 2015

Designing a Manufacturable Flexible PCB Involves Tradeoffs

Dave Becker writes that designers are always inquiring about the limits of flexible PCBs. Maximum amperage, copper thickness, flex life, and minimum recommended pitch are just a few examples of the limits that designers are exploring when designing electronic packages. Design guides and websites provide information and tools related to many of these questions, and materials and properties pages provide information on the various materials and material thicknesses that are typically used.

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July 21, 2015

The Drive to More Flexible Solutions

It is understandable that some of the more advanced, cutting edge technologies are requiring the use of flexible circuits. Flex tends to be light weight, thin, bendable and its versatility for interconnection can eliminate assembly costs. Flexible circuits can be your high density solution for just about any electronic application. Not only could a flexible circuit solve your size and weight challenges, a flexible circuit could be your most cost effective solution for electronic interconnects.

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June 11, 2015

Wearable Technology and Flexible Circuits

Flexible circuits are an ideal fit for wearable technology. Wearable electronics need to be light, dense and bendable. While what is currently considered standard flexible circuit technology is more than adequate for many the wearable products, there are requirements that may be pushing the boundaries a bit.

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May 28, 2015

Flexible Circuits and UAV Applications

The utility offered by flexible circuits in UAVs mimics the advantages that make it popular in other portable electronic applications: lightweight, thin, highly reliable, flexible during use, and an ability to electrically connect across multiple layers as part of a complete packaging interconnect solution.

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July 02, 2015

Flexible PCBs and Connectors

While a well-designed flexible circuit will eliminate many connectors, ultimately most need to connect to something. Probably the most common entity that a flex circuit connects to is a rigid printed circuit board, but cable harnesses, polyester membrane switches, and even other flex circuits are also possible connection partners. Dave Becker of All Flex explains.

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June 18, 2015

Flexible Circuits and the Implantable Medical Device Market

Implantable medical device manufacturing was once considered the last area of U.S. manufacturing dominance. Today, the U.S. is still a dominant player, and the implantable medical device industry is growing; however, many companies are experiencing reduced profits and are moving to a cost-cutting mode.

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