A novel laser transfer process for direct writing of electronic and sensor materials

MAPLE direct write (MAPLE DW) is a new laser-based direct-write technique which combines the basic approach employed in laser-induced forward transfer (LIFT) with the unique advantages of matrix-assisted pulsed-laser evaporation (MAPLE). MAPLE DW utilizes an optically transparent substrate coated on one side with a matrix consisting of the material to be transferred mixed with a polymer or organic binder. As in LIFT, the laser is focused through the transparent substrate onto the matrix. When a laser pulse strikes the matrix, the binder decomposes and aids the transfer of the material of interest to an acceptor substrate placed parallel to the matrix surface. MAPLE DW is a maskless deposition process which operates in air and at room temperature. Powders of Ag, BaTiO3, SrTiO3, and Y3Fe5O12 with average diameters of 1 μm were transferred onto the surfaces of alumina, glass, silicon, and printed circuit board substrates. Parallel-plate and interdigitated capacitors and flat inductors were produced by MAPLE DW over Rogers RO4003 substrates. MAPLE DW was also used to transfer polymer composites for the fabrication of gas sensor chemoresistors. One such composite chemoresistor fabricated with polyepichlorohydrin/graphite was used to detect organic vapors with a sensitivity of parts per million. PACS: 81.15.-z; 81.40.-z; 81.60.-z In the last ten years, the use of electronic systems has increased dramatically. In concert, the demand for faster and smaller products has placed enormous emphasis on miniaturization and increased functionality. In order to fabricate electronic assemblies with reduced weight, volume, cost, and time, new materials and/or tools to process them must be developed. Until now, limited progress in the miniaturization of electronic and sensor components has been achieved ∗Corresponding author. (Fax: +1-202/767-5301, E-mail: [email protected]) COLA’99 – 5th International Conference on Laser Ablation, July 19–23, 1999 in Göttingen, Germany by using surface-mounted components. Surface-mount technologies are based on a three-fold strategy of first designing, then patterning, and finally mounting each of the system components on a circuit board. Modifications to an existing device require time-consuming iterations of the above steps. The use of rapid prototyping techniques can provide a solution to these time-consumption problems. With a rapid prototyping processes, it is possible to direct write elements and components onto the wide variety of surfaces called for in circuit design, essentially eliminating multiple steps and time constraints. Furthermore, the fact that direct-write techniques are compatible with current computer software for integrated design and manufacture (CAD/CAM) is an added advantage. This article presents a novel direct-write technique that combines the positive advantages of laser-induced forward transfer (LIFT) and matrix-assisted pulsed-laser evaporation (MAPLE). This technique is called MAPLE direct write (MAPLE DW). An overview of the MAPLE DW process, along with its advantages, is presented. We give experimental results from various devices made by MAPLE DW such as parallel-plate and interdigitated capacitors, flat inductors, conducting lines, resistors, and chemoresistive gas sensors.