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Forty years after the first silicon microprocessors, we demonstrate an 8-bit microprocessor made from plastic electronic technology directly on flexible plastic foil. The operation speed is today limited to 40 instructions per second. The power consumption is as low as 100 μW. The ALU-foil operates at a supply voltage of 10 V and back-gate voltage of 50 V. The microprocessor can execute user-defined programs: we demonstrate the execution of the multiplication of two 4-bit numbers and the calculation of the moving average of a string of incoming 6-bit numbers. To execute such dedicated tasks on the microprocessor, we create small plastic circuits that generate the sequences of appropriate instructions. The near transparency, mechanical flexibility, and low power consumption of the processor are attractive features for integration on everyday objects, where it could be programmed as, amongst other items, a calculator, timer, or game controller.

There has been enormous worldwide effort to increase the volumetric efficiency of electronic packaging. Much of this effort has been driven by the telecommunications industry that has succeeded in reducing cell phone size while simultaneously increasing functionality. The hearing aid business has always had the need to use extremely small electronic packaging because hearing aids pack electronics into the ear canal. In recent years hearing aid microelectronic packaging has moved from ceramic hybrid based packaging to a flexible circuit based technology. Due to the size and shape of all types of hearing aids, flexible circuits need to be folding and bent to fit inside hearing aid cases. In order to reduce space, bends and folds are pushing conventional wisdom on the limits of mechanical integrity. There is little published information regarding bendability of multilayer flexible circuits for class I medical device applications. This paper will examine bending and folding effects on a Polyimide/Adhesive/Copper/Polyimide/Copper/Adhesive/Polyimide structural stack-up on a test coupon and a HDI flexible circuit. A forming tool that controls every aspect of bend testing will be discussed. A variety of factors were investigated including bend angle, thickness of the circuit, bend radius, foil weight, copper materials, construction, and frequency of flexing. The circuit electrical resistance, microstructure and crack initiation were monitored during the process and will be examined. Failure mechanisms will be discussed as well as their impact on design.

Purpose – To provide an overview of a process for making proper selection of base materials for use in the manufacture of flexible circuits.Design/methodology/approach – The paper provides an introductory review of the desirable attributes for flexible circuit substrates and includes a description of the attribute and its specific role and impact on the finished product.Findings – The paper highlights the importance of making informed materials choices in flexible circuit manufacture. Flexible circuits are an increasingly important member of the family of electronic interconnection technologies and are also the fastest growing. A variety of materials can be used for flexible circuit construction, however, the choice must be tempered by the manufacturing and assembly processes and the application of the finished product.Research limitations/implications – The paper provides a limited overview of the desirable properties of flexible circuit materials and is designed to provide initial background and guidanc...

Due to the material properties and technology advancement in printed circuit flex tapes, traditional PCB inspection algorithms using reference image cannot be used. Flex tapes are flexible circuits enabling the design and production of lighter, faster and smaller electronic products. A flex tape is made of flexible polymer film that is laminated onto a thin sheet of conductive material and etched to produce a circuit pattern. The width of fine pitch patterns can be of a few microns. Due to the material characteristics of printed circuit tapes, such as thinness and flexibility, the images captured during inspection are distorted (stretch or shrink, tilt, meandering, etc.). These anomalies and shining tape surface make the possibility of using conventional PCB inspection algorithms using referential methods for pattern inspection, difficult. The goal of pattern inspection is to identify pattern defects — open, short, nick, protrusion, island, pinholes and dust particles. Non-repetitive and non-uniform distortions are some of the main challenges in inspecting these flexible tapes. Some of the other challenges faced during the design of the defect detection algorithm are non-uniform lighting and the gamut of sizes, shapes & orientation of defects as well as features on the printed circuit. Moreover, the algorithms need to take into account the stringent defect tolerance limits followed by the industry.

Polymer thick film (PTF) technology provides the lowest cost, cleanest and most efficient manufacturing method for producing flexible circuits. Non‐contact radio frequency (RF) smart cards and related information transaction devices, such as RFID tags, appear to be a good fit for PTF‐flex. Flip chip also seems well suited for these “contactless” RF transceiver products. Flip chip and PTF adhesive technologies are highly compatible and synergistic. All PTF SMT adhesives assembly methods are viable for flip chip. However, the merging of flip chip with PTF‐flex presents major challenges in design, materials and processing. This paper will compare assembly methods and discuss obstacles and solutions for state‐of‐the‐art flip chip on flex within the RFID product environment.

“A patterned arrangement of printed wiring utilizing flexible base material with or without flexible coverlayers”. The balance of this brief article will hopefully serve to help the reader understand this remarkable interconnection technology and appreciate just how widely the technology can be applied.

This article comprises Chapter 6 from the recently published book ‘An Engineer’s Guide to Flexible Circuit Technology by J. Fjelstad

This seminar introduces three recent progresses that can extend the application of high performance flexible inorganic electronics.

In this paper, we propose a process on forming durable and flexible circuits directly on textile using transfer printing technology. This process allows electronic textiles to demonstrate stable performance in the presence of physical stress, and allows us to implement high resolution textile circuits, compatible with variety of commercially-off-the-shelf chips. Using our technology, a flexible, wearable, and durable textile wristwatch is developed.

Publisher Summary This chapter provides an introduction to several methods for patterning that include both atmospheric processing and in vacuum patterning techniques. There are different options with the atmospheric patterning process. One of which produces a positive pattern and the other a negative of the same pattern. In order to reduce costs it is preferable to reduce the number of process steps and this may be done using in-vacuum pattern metalization. The first process developed was to produce uncoated stripes down the length of the web as required for capacitors. This could be done using fixed masks across the deposition zone; however, any permanent mask would have a clearance distance between the mask and the web and this would cause a shadow area where the metal thickness was graded down from full to zero. An improvement to this process was to use a continuous belt that could be brought into contact with the film around the deposition drum. The belt, made of stainless steel or polyimide, would then pass round behind the deposition sources and be brought back into contact with the web. Another progression in the in-vacuum pattern metalization has been to also include the option for in-register in-vacuum pattern metalization.

Textiles are ubiquitous to us, enveloping our skin and surroundings. Not only do they provide a protective shield or act as a comforting cocoon but they also serve esthetic appeal and cultural importance. Recent technologies have allowed the traditional functionality of textiles to be extended. Advances in materials science have added intelligence to textiles and created ‘smart’ clothes. Smart textiles can sense and react to environmental conditions or stimuli, e.g., from mechanical, thermal, chemical, electrical, or magnetic sources (Lam Po Tang and Stylios 2006). Such textiles find uses in many applications ranging from military and security to personalized healthcare, hygiene, and entertainment. Smart textiles may be termed ‘‘passive’’ or ‘‘active.’’ A passive smart textile monitors the wearer’s physiology or the environment, e.g., a shirt with in-built thermistors to log body temperature over time. If actuators are integrated, the textile becomes an active, smart textile as it may respond to a particular stimulus, e.g., the temperature-aware shirt may automatically roll up the sleeves when body temperature rises. The fundamental components in any smart textile are sensors and actuators. Interconnections, power supply, and a control unit are also needed to complete the system. All these components must be integrated into textiles while still retaining the usual tactile, flexible, and comfortable properties that we expect from a textile. Adding new functionalities to textiles while still maintaining the look and feel of the fabric is where nanotechnology has a huge impact on the textile industry. This article describes current developments in materials for smart nanotextiles and some of the many applications where these innovative textiles are of great benefit.

Insulated Metal Substrates (IMS) have been used in the automotive industry for a number of years. The popularity of this technology is due to the good thermal conductivity of the thin insulation material, which is more effective than convection cooling, and the high temperature performance of the adhesive used for under‐bonnet applications. This paper describes how IMS circuits can be designed and manufactured with two or more layers without using the traditional plating processes.

The main objective of the U.S. Army's Active Coatings Technologies Program is to develop technologies that can be used in combination to tailor coatings for utilization on Army Materiel. The Active Coatings Technologies Program, ACT, is divided into several thrusts, including the Smart Coatings Materiel Program, Munitions Coatings Technologies, Active Sensor packages, Systems Health Monitoring, Novel Technology Development, as well as other advanced technologies. The goal of the ACT Program is to conduct research leading to the development of multiple coatings systems for use on various military platforms, incorporating unique properties such as self repair, selective removal, corrosion resistance, sensing, ability to modify coatings' physical properties, colorizing, and alerting logistics staff when tanks or weaponry require more extensive repair. A partnership between the U.S. Army Corrosion Office at Picatinny Arsenal, NJ along with researchers at the New Jersey Institute of Technology, NJ, Clemson University, SC, University of New Hampshire, NH, and University of Massachusetts (Lowell), MA, are developing the next generation of Smart Coatings Materiel via novel technologies such as nanotechnology, Micro-electromechanical Systems (MEMS), meta-materials, flexible electronics, electrochromics, electroluminescence, etc. This paper will provide the reader with an overview of the Active Coatings Technologies Program, including an update of the on-going Smart Coatings Materiel Program, its progress thus far, description of the prototype Smart Coatings Systems and research tasks as well as future nanotechnology concepts, and applications for the Department of Defense.

Electronic circuits that can bend and flex seem to bring out the science fiction writer in many a reporter (and indeed they've been used in numerous sci-fi movies and TV shows as a convenient way to underline the futuristic nature of a setting). Current excitement about the technology is centered on materials such as OLEDs and carbon nanotubes. But as this ad from May 1965 shows, the exciting future of flexible circuits is actually an old story. (Also worth noting is the reference to Princess telephones, which were first introduced in 1959 and sold until 1994. They are now considered a collectible design classic.)

No Abstract Available.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

This paper documents the successful development and evaluation of a novel membrane switch. The process results in lower environmental burdens and manufacturing costs than current screen-printed polyester solutions. Detailed is the evaluation of offset lithographically printed conductive tracks on paper substrates for application in computer keyboard assemblies. Offset lithographic printing of conductive tracks is an emerging fabrication technique finding application in low-cost, high volume, flexible circuitry applications. Several fully featured demonstration keyboards and switch membranes have been constructed and tested. These are currently in use in office environments and are presented.

THE USE of engineering adhesives in manufacturing is seen to be a major area of growth, at the expense of conventional fastening techniques such as screwing, welding and riveting. Similarly, flexible circuits are also seen to be set to grow in use as manufacturers seek to cram in more electronics and functions into ever‐smaller and more complex packages.

A significant consideration to be made with respect to the application of a flexible circuit is the degree to which it can be bent when incorporated into the next level of assembly. The application of stress analysis techniques to arrive at a flexible circuit design that will be structurally sound for a given set of parameters and materials relative to the required application is discussed.

The manufacture of flexi‐rigid multilayer boards poses a number of problems which are not met with in ordinary multilayer production or in the making of plain flexible circuits. Steps have to be taken to overcome the poor dimensional stability of thin polyimide foils during processing and to ensure that those portions of the assembly which need to be rigid are bonded whilst flexible portions are left unbonded other than for a cover coat. Pressure on cover coated flexible areas must be maintained during bonding without allowing resin to now over these areas, and finally the bonded unit must be profiled, often with superimposed flexible areas of different shapes. This article describes some of the techniques used by a leading manufacturer to overcome these problems. Several of the processes described are covered by patents held by Exacta Circuits Ltd. This article is an extract from a forthcoming book ‘Handbook of Multilayer Printed Circuits’ to be published at the end of the year by Electrochemical Publications Ltd., 8 Barns Street, Ayr, Scotland.

SummaryAn account is given of the production of fine line flexible circuits having conductors of 200 microns in width etched to a tolerance of ± 12 microns over a length of 3 metres. The various stages of cleaning the base material, coating, exposing, developing and etching the patterns are described with full practical details. All the techniques used are those of the basic printed wiring process but refined to give the results reported.

This paper surveys recent innovations which led to technological advances in electronics applications using polyester film for insulation. Innovation occurred in materials, manufacturing processes and product designs. The applications involved are membrane touch switches, flexible circuits and miniature capacitors. These applications place a premium on miniaturization, high reliability, design flexibility, lightweight and low cost.

Flexible circuits are true components in their own rights—not solely replacements for discrete wiring—and must be designed as an efficient component for production. This paper discusses all the parameters which must be met.