Printed Electronics on the Horizon
17 October 2008
Simon Clasper takes a look at emerging and future applications for the screen printer.
Rapid commoditisation of technologies and high-tech products is driving companies to compete for position in leading-edge opportunities, where the best and fastest returns are to be gained. Technology businesses in all global territories, from east to west, are racing to acquire knowledge and capabilities in emerging areas such as embedded passives, organic LEDs (OLEDs), electroluminescent (EL) displays and RFID tags.
To thrive among world-class competition, European electronic manufacturers need fast, accurate, flexible and cost-effective assembly equipment capable of solving current challenges and also able to adapt to future demands for higher market volumes and evolving techniques.
Emerging Roles for Printing
Precision printing technology will be at the heart of forthcoming advances in applications such as electronic displays, identification technologies, and ubiquitous sensing and monitoring. It will also be critical to the ongoing miniaturisation of general electronic assemblies. General assembly, for example, will adopt technologies such as 3D passive integration using materials such as tape dielectrics, in addition to fine-pitch assembly onto standard PCB substrates. Other developments that will rely on precision printing will include tele-healthcare, which will require high-volume production of test strips for patient self-monitoring and medication as well as large numbers of sub-miniature implantable devices.
As far as precision screen printers are concerned, the platforms available for high-volume surface-mount manufacturing are understood to deliver extremely high standards of throughput and accuracy. DEK is aiming to deliver the same high standards for manufacturers in emerging applications and markets with its Horizon product strategy, comprising the Horizon 03i, Horizon 02i and Horizon 01i printers. These are built on a common, scalable printer platform, creating a product curve that allows buyers to optimise the price and performance of their chosen printer while benefiting from a rich options list, future scalability, and industry-standard interfaces These interfaces are central to the ability of Horizon machines to integrate easily into a wide variety of production scenarios. The Horizon platform delivers Cpk 2.0 at +/-12.5 microns, so the three models in the range provide the opportunity to scale up the cycle time from 12 seconds with the Horizon 03i, through 10 seconds with the Horizon 02i and down to just 8 seconds with the Horizon 01i.
By spanning a broad price-performance continuum, the Horizon range allows manufacturers to achieve an optimal specification meeting their needs – whether these are based on high-volume challenges such as price-sensitive consumer goods, or specialist assemblies for markets such as military, medical or prototyping services.
Flexible, Scalable Capability
As a printing platform focused on high productivity, the Horizon machine complements its fundamental speed with a range of standard and optional features to save setup and changeover time, and eliminate human intervention to maximise throughput and repeatability. As a standard feature, the DEK Instinctiv user interface streamlines setup and changeover with task-based design, menu-driven instructions featuring clear graphics, and on-board help to eliminate errors and reduce operator-training requirements.
All three of the basic Horizon configurations allow owners to specify high-performance options such as automatic tooling using the GridLok conformable pin array and high-speed verification using the HawkEye system at continuous scan rates up to 1700mm/s. This system accelerates post-print checking by using streaming video capture with high-speed image analysis to make a go/no-go assessment of print results. 100 percent of boards are analysed at the line beat rate, with the ability to prioritise critical print sites such as areas where high-density interconnects are concentrated. Up to 100% of paste sites can be analysed, depending on the board area and number of sites.
An additional option is the Horizon Dual Lane (Horizon DL) configuration, which uses pipelining techniques to enable manufacturers to deliver printed substrates at full rated speed into two production lines running side by side. Dual-lane manufacturing is an established speed-up technique for many inline assembly challenges where a dramatic increase in throughput is required, along with additional production flexibility. With two independent lanes available manufacturers can assemble two different board types simultaneously, for example to achieve the same turnaround time for several jobs or to build sets comprising dissimilar boards for a complex project.
Horizon printers provide the cornerstone for many European electronic manufacturing businesses, spanning the production spectrum from low-to-mid volume and high mix all the way up to high volume SMT assembly. The platform’s flexibility, in terms of throughput, automation and process capability solves challenges for small and large facilities, including research departments, highly focused business units targeting specialist technologies or first-article build, and high-volume manufacturers such as LCD-TV producers typically based in central Europe.
Adaptable for Opportunities
Among the advanced trends that manufacturers are seeking to address through the use of accurate and flexible screen printers, multilayer circuit techniques including 3D passive integration typically require precision deposition of organic materials onto a ceramic substrate technology such as a tape dielectric. By allowing passive components to be incorporated into the substrate of a device such as a miniature antenna module or filter for cellular phone applications, future products can become smaller, lighter, more reliable and more cost effective. Multilayer fabrication onto tape dielectric – also known as Green Tape – is recognised as an effective solution to achieving next-generation circuit density in high-performance systems such as microwave modules. Accurate and repeatable printing is necessary, to control the impedance of passive circuit elements fabricated on the tape dielectric, and to fulfil associated processes such as via filling.
Further exciting new developments in high-tech manufacturing are emerging in areas such as printed electronics, which encompasses production of RFID tags and EL devices as well as numerous other opportunities such as printed sensors, switches, heaters and smart packaging.
The markets and applications for RFID, for example, are extremely broad and deep. These include access control, security tagging, warehouse management, asset tracking and retail management. Across all of these opportunities, predictions suggest that hundreds of billions of RFID tags and labels will be required. Each transponder embedded into a tag or label requires a passive antenna. These tend to be produced quickly and accurately by screen printing onto a flexible substrate using a polymer thick-film ink. The resistance of the antenna’s conductive coil must be tightly controlled to ensure optimal performance as an RFID transponder. This, in turn, calls for high-accuracy, precision screen printing. At the same time, research is ongoing into new materials to enable smaller and better performing antennas. Precision screen printers such as the DEK Horizon platform provide the accuracy, repeatability and inline automation that transponder manufacturers will require in order to satisfy the expected surge in worldwide demand.
In addition to its high speed and accuracy, the Horizon platform is compatible with reel-to-reel printing, which is becoming widely recognised as a valuable technique for printing onto continuous flexible substrates. Using reel-to-reel technology in conjunction with a proven accurate screen printing platform allows manufacturers to combine high-speed, continuous manufacturing with the high standards of accuracy and repeatability that world-class SMT manufacturers now expect.
Reel-to-reel printing is ideal for producing RFID transponders, since large numbers of antennas can be produced quickly. The thick-film deposit can be cured in anything up to two minutes, at an elevated temperature, and an entire reel of transponder units can be printed and stored ready for singulation with relatively little human intervention.
Similarly, there is growing interest in printing with electroluminescent inks to create ultra-flat printed light sources for use in such applications as human-machine interfaces, advertising displays and general illumination. The growth in EL technology calls for accurate and repeatable printing of multiple conductive layers, which demands high process capability up to Cpk 2.0 at fine resolution. Depending on the target applications, the substrate may be a thin, flexible material such as a clear plastic, or may be a substrate having dramatically different properties, such as polycarbonate or toughened glass. The highly standardised interfaces implemented on the Horizon platform, which are a product of its heritage as a high-speed inline precision printer, maximise opportunities for manufacturers to implement the most suitable handling for a given application. This may involve reel-to-reel printing with a flexible substrate, for example, or may call for a specialist handling solution. In this case, the machine’s standardised interfaces can aid mechanical, electrical and software integration of a custom loader for singulated or panellised substrates.
The global electronics landscape is shifting continuously and quickly. Currently, surface-mount manufacturing appears to be divided along the lines of high-volume assembly in the far east and high-tech/high-margin in the west. However, this model has numerous exceptions, and emerging technologies such as printed electronics will soon prove that the apparently stable picture is simply a snapshot of a dynamic and rapidly changing situation.
Ultra-accurate, high-speed, versatile and scalable platforms, such as the Horizon family for screen printing a wide variety of the electronic materials used in emerging applications, will be critical to the success of these emerging technologies, as well as being essential equipment for companies developing highly miniaturised assemblies using next-generation surface-mount techniques.
Simon Clasper works for DEK
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