P.M. Harrey

Capacitive-type humidity sensors fabricated using the offset lithographic printing process

This paper reports on the fabrication of a novel capacitive-type relative humidity sensor of which the electrode films are deposited using the high speed printing process, offset lithography. Parallel-plate capacitor sensor structures have been formed with a number of humidity sensitive polymers including polyimide and polyethersulphone (PES). Details of the fabrication process and sensor characteristics such as linearity, sensitivity and response time are included.

Lithographic film circuits – a review

Conductive lithographic films (CLF) are an emerging fabrication process for electronic interconnect and a range of passive component structures. This paper reviews the manufacture, properties and applications of CLF conductors, and discusses other lithographically deposited electronic materials including resistive, dielectric and ferrite films. Recent developments in CLF technology, including multilayer structures and concurrent printing of interconnect with printed passive components, are presented.

INTERDIGITATED CAPACITORS BY OFFSET LITHOGRAPHY

This paper reports on an initial investigation into interdigitated capacitors manufactured via the offset lithographic printing process. Results taken from print-trials reveal the relationship between electrode geometry and capacitance. The paper also identifies a relationship between the substrate characteristics and the behaviour of the capacitive structures. This work is in support of a low cost and low environmental impact approach to circuit board manufacture.

A novel manufacturing process for capacitors using offset lithography

A novel fabrication technique for passive electronic components and circuit interconnects based on offset lithographic printing is described. The application of this work is in low cost and low environmental impact substitutes for resin-laminate circuit boards populated with discrete components. Multilayer ceramic capacitor elements are formed on flexible substrates by depositing layers of metal and ceramic-loaded inks sequentially via a standard lithographic printing press.

Integrated capacitors for conductive lithographic film circuits

This paper reports on fabrication of low-value embedded capacitors in conductive lithographic film (CLF) circuit boards. The CLF process is a low-cost and high speed manufacturing technique for flexible circuits and systems. We report on the construction and electrical characteristics of CLF capacitor structures printed onto flexible substrates. These components comprise a single polyester dielectric layer, which separates the printed electrode films. Multilayer circuit boards with printed components and interconnect can be fabricated using this technique.

Via and embedded resistor production in low cost lithographically printed substrates

Lithographic printing of silver based conductive inks to form circuit tracking provides a very low cost, environmentally friendly method of production. It allows circuits with line widths down to 100 /spl mu/m and a sheet resistance of 0.3 /spl Omega/ per square to be produced at rates of up to 10000 impressions per hour. The process makes use of low capital cost equipment and has low set up costs. To date, an equally cost effective method of manufacturing vias in these circuits has not been developed. This paper proposes two new techniques for via production which are compatible with the rest of the manufacturing process. In the first technique, suitably profiled holes are laser drilled for subsequent filling as part of the lithographic printing. In the second technique laser energy is used to melt the substrate material so that it is able to mix with the conductive ink and so form a conductive path. The paper describes the proposed production techniques and discusses the factors affecting each method and in particular the substrate properties affecting production. The substrate materials considered in detail are Glossart and Teslin. The optical absorption and ablation characteristics of these materials for excimer and CO/sub 2/ lasers are reported, as are the thermal diffusivities.

Via and embedded resistor formation by matrix-assisted pulsed laser deposition

Abstract A novel method of forming vias and embedded resistors in a double-sided electronic circuit substrate is proposed. The structures are formed by removing conductive material from a target by laser ablation and depositing it into a hole previously drilled in the substrate. The target is composed of a matrix material, which is readily ablated, supporting conductive particles that are ejected along with the matrix material to be re-deposited on the sides of the hole. The nature of the conductive particles determines whether a via or a resistor is formed.