Low-cost Printing Research Articles

Designing solution-processable air-stable liquid crystalline crosslinkable semiconductors

Organic electronics technology, in which at least the semiconducting component of the integrated circuit is an organic material, offers the potential for fabrication of electronic products by low-cost printing technologies, such as ink jet, gravure offset lithography and flexography. The products will typically be of lower performance than those using the present state of the art single crystal or polysilicon transistors, but comparable to amorphous silicon. A range of prototypes are under development, including rollable electrophoretic displays, active matrix liquid crystal (LC) displays, flexible organic light emitting diode displays, low frequency radio frequency identification tag and other low performance electronics. Organic semiconductors that offer both electrical performance and stability with respect to storage and operation under ambient conditions are required. This work describes the development of reactive mesogen semiconductors, which form large crosslinked LC domains on polymerization within mesophases. These crosslinked domains offer mechanical stability and are inert to solvent exposure in further processing steps. Reactive mesogens containing conjugated aromatic cores, designed to facilitate charge transport and provide good oxidative stability, were prepared and their liquid crystalline properties evaluated. The organization and alignment of the mesogens, both before and after crosslinking, were probed by grazing incidence wide-angle X-ray scattering of thin films. Both time-of-flight and field effect transistor devices were prepared and their electrical characterization reported.

SEMICONDUCTORS FROM LIQUIDS

A NOVEL SEMICONDUCTOR-processing technique based on a liquid precursor to solid silicon may one day replace traditional vapor-deposition methods for fabricating microelectronic devices. The procedure, developed by researchers in Japan, may enable the use of low-cost ink-jet printing methods to manufacture large-area displays and other advanced electronic devices. At the core of most modern microelectronic devices lies a siliconbased brain that's been painstakingly constructed via a variety of exacting and energy-intensive processes. Manufacturers often depend on procedures in which highly purified silicon is heated and vaporized in vacuum and then deposited on a support material to build up structures in a layer-by-layer fashion. The overall process generally involves multiple refining, deposition, and etching steps to convert the solid film into a functioning circuit component. Simpler approaches using liquids could capitalize on today's high-resolution printing technology to draw fine circuit featur...

A novel and facile route of ink-jet printing to thin film SnO 2 anode for rechargeable lithium ion batteries

Thin film SnO 2 electrode has been prepared for the first time by using a novel facile and low-cost ink-jet printing technique. Wet ball-milling was employed to stabilize SnO 2 nano particles and conducting agent acetylene black (AB) using two kinds of polymeric hyperdispersants CH10B and CH12B, respectively, to prepare the stable colloid as “ink”. The morphology, structure, composition and electrochemical performance of SnO 2 thin film electrodes were investigated in detail by SEM, TEM, XRD, EDX, cyclic voltammograms (CV) and galvanostatic charge–discharge measurements. SEM images show uniform distribution of as-printed SnO 2 thin film electrodes. The thickness of monolayer thin film electrode was about 770–780 nm by TEM observation. The thickness of SnO 2 thin film could be increased by repeating the printing procedure on the Cu foil substrate. The average thickness of 10-layer SnO 2 thin-film electrode after compression for electrochemical measurement was about 2.3 μm. High initial discharge capacity about 812.7 mAh/g was observed at a constant discharge current density of 33 μA/cm 2 in a potential range of 0.05–1.2 V. It is expected that ink-jet printing is a very feasible, simple, convenient and inexpensive way to prepare thin film electrode for lithium ion batteries.

Using Photomaps to Support Participatory Processes of Community Forestry in the Middle Hills of Nepal

Making information and decision-making processes accessible to disadvantaged and nonliterate people is a challenge for community forestry in Nepal. In studies jointly conducted by the Nepal–UK Community Forestry Project (NUKCFP) and His Majesty's Government (HMG) of Nepal Department of Forest, aerial photographs and participatory photomapping (tracing maps over aerial photographs) were evaluated with a view to supporting participatory processes of community forestry in Parbat District of the Middle Hill Region. Results indicate that, regardless of educational status, most people accurately interpreted forest condition and profiles of community use from photographs. Photographs were appreciated because they presented authentic information, allowed consistency of interpretation between groups, and made it possible to calibrate perceptions of resources. District Forest Officers and Community Forestry Officers valued aerial photographs as robust instruments that naturally directed discussions toward community and resource issues. Results of a pilot study of the use of aerial images for surveys indicated that orthorectified aerial images may substantially reduce time spent by District Forest Office (DFO) staff in chain-and-compass surveys of community forests. Surveys based on aerial images encourage the participation of users, and boundaries drawn over survey photomaps are represented in the context of important reference information contained in the photographic image. The development of a service for low-cost printing of high-resolution and geographically correct photomaps is described.

Initial investigations into low-cost ultra-fine pitch solder printing process based on innovative laser printing technology

Advances in electronics packaging and assembly technology are driving increased demand for ultra-fine pitch solder deposition. In this work, innovative solder deposition techniques based on laser printing are investigated for low-cost ultra-fine pitch printing applications. This paper investigates the feasibility of using solder particles in off-the-shelf xerographic technology. The physics of two development systems (dual component and monocomponent) is discussed. This inquisition leads to a discussion of triboelectric charging of the solder toners, coating the solder with thin dielectrics, and charge induction by an applied electric field. This initial investigation explores the basic feasibility of xerographic printing techniques using solder and defines future work.

Using printing and molding techniques to produce distributed feedback and Bragg reflector resonators for plastic lasers

We describe the use of low cost printing and molding techniques to fabricate distributed feedback and Bragg reflector resonators for photoexcited plastic lasers that have narrow emission profiles in the visible range. The good performance of the lasers demonstrates the suitability of these techniques for fabricating certain types of functional optoelectronic devices that require submicron features patterned over macroscopic areas.

Area bonding conductive epoxy adhesives for low-cost grid array chip carriers

This paper describes a new type of Z-axis epoxy film adhesive, called area bonding conductive (ABC) epoxies, to replace solder and solder balls for surface mounting grid array chip carriers. The ABC adhesives are made by a low-cost screen printing process, starting from customer-supplied artwork, so that the conductive epoxy regions are located only at the desired bond pad locations. Reliability data, presented for plastic and LTCC packages attached to FR-4 boards with these adhesives, show better resistance to thermal cycling and thermal shock than soldered packages. This paper also describes a new low-cost copper-lidded pad array chip carrier (Cu-PAC), which uses an ABC epoxy for die and for substrate attach. The Cu-PACs have the potential for major cost savings, size reduction, and improved heat removal compared to present molded plastic grid array (PGA) packages.

Ferroelectric liquid-crystal shutter array with a-Si:H TFT driver

A ferroelectric liquid crystal (FLC) shutter array with an a-Si:H thin-film transistor (TFT) drive, designed for a low-cost and high-performance optical printing head, is presented. The a-Si:H TFT driver consists of inverter circuits, switch TFTs, and matrix circuits. A block driving method was employed to compensate for the low operating speed of the a-Si:H TFTs. The 256-dot, 300-dot/in resolution prototype device mounted in a printing head shows an over-30 contrast ratio and an 8-page/min operating speed. Additional measurements on this device demonstrate the possibility of operation with a 24-page/min speed at a 600 dot/in resolution. >

Ferroelectric liquid-crystal shutter array with poly-Si TFT driver

A ferroelectric liquid crystal (FLC) shutter array with an a-Si:H thin-film transistor (TFT) drive, designed for a low-cost and high-performance optical printing head, is presented. The a-Si:H TFT driver consists of inverter circuits, switch TFTs, and matrix circuits. A block driving method was employed to compensate for the low operating speed of the a-Si:H TFTs. The 256-dot, 300-dot/in resolution prototype device mounted in a printing head shows an over-30 contrast ratio and an 8-page/min operating speed. Additional measurements on this device demonstrate the possibility of operation with a 24-page/min speed at a 600 dot/in resolution. >

Desk-Top Publishing: Current Approaches and Future Trends

In order to assess future trends in desk-top publishing (DTP), it is necessary to understand the problems encountered in today's solutions. The environment addressed by this paper is the single-user interactive workstation for a business, technical or publishing professional. A local or shared low-cost printer is assumed. High-quality and high-volume printing is treated as a remote or an external function to which a document can be transferred in machine-readable form.

Desk-Top Publishing: Current Approaches and Future Trends

In order to assess future trends in desk-top publishing (DTP), it is necessary to understand the problems encountered in today's solutions. The environment addressed by this paper is the single-user interactive workstation for a business, technical or publishing professional. A local or shared low-cost printer is assumed. High-quality and high-volume printing is treated as a remote or an external function to which a document can be transferred in machine-readable form.

X-ray diffraction with a microcomputer

A computer program which generates a replica of a Debye-Scherrer powder photograph for any cubic structure is described. The program also calculates Bragg angles for any such structure, real or hypothetical. It has been implemented using an inexpensive Sinclair Spectrum microcomputer in conjunction with a low-cost printer.

An inexpensive, portable, printing event recorder for behavior studies

An inexpensive, field-portable event recorder for monitoring insect or other animal behavior is described. The recorder consists of a 16-key event code keyboard and a 99.99-min timer interfaced to a low-cost printing calculator. The event code number and the elapsed time (.01-min resolution) from the start of an observation period are printed whenever an event key is pressed. The recorder is operable over a temperature range of 0°C to 50°C, with a timing error of less than ±.05% of the 99.99-min full-scale timing range. Periods longer than 99.99 min can be monitored, provided the return to zero of the timer is noted and taken into consideration.

High-speed terminal printers

A description of high-speed (3,000 wpm) low-cost terminal printing equipment using the basic technique of electrostatic printing. Speeds of 30,000 wpm are practicable with line feed on intermittent demand.