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Research paper : Development of laser-assisted inkjet printing technology (A. Endo et al.)−16−Synthesiology - English edition Vol.4 No.1 (2011) However, the method for quantitatively measuring the adhesiveness of fine wiring with thickness and width of tens of m has not been established, and new development is necessary to evaluate the adhesive strength of the wires.5 Technological potential of the laser-assisted inkjet and its future prospectIn this paper, the possible solution to the problems that were considered difficult with conventional inkjet printing technology was indicated by using the laser-assisted inkjet technology in the wiring process for the diverse-type variable-volume production of electronic devices.By setting and solving the technological issue of controlling the wet-spreading of ink, it was shown that the improvement of inkjet printing technology throughput and low wire resistance were possible. By controlling the wet-spreading of ink using the laser-assisted inkjet technology, the possibility of handling high frequency transmission needed for 3D mounting, wire formation on nonplanar substrate, and wire formation onto flexible substrate becomes a reality.The positioning and possibility of the laser-assisted inkjet as a mounting technology are as follows:(1) Achieving high frequency for the IC chip: fabrication of high frequency transmission line and good high frequency property at 1 GHz ~ 40 GHzPossibility of high frequency transmission without shortening the distance of wiring between elements(2) 3D wiring technology: capable of wiring onto uneven, stepped, and rough-surface substrateSimplification of electric connection as well as flip chip mounting(3) Durability of wiring: improved adhesiveness of the wiringApplicability to the wiring of device that must be environment-resistantFig. 11 Tape peeling test for wires on mirror-surface and rough-surface substratesWired tapeWired tapeWiring peeled offWiring peeled offCellophane tapeCellophane tapePeeling testTape adhesionFormed wireRough-surface substrateMirror-surface substrateIt is necessary to solve several other technological issues to establish this technology as a practical 3D mounting technology based on these results. It is also important to clarify the basic mechanism of the laser-assisted inkjet method and the phenomenon of gaining high aspect for the wire.This means it is necessary to conduct a dual development into Type 1 Basic Research and Product Realization Research, using the Type 2 Basic Research as the entrance.The principles of the mechanism by which wire with width less than the droplet diameter can be formed and the phenomenon by which high aspect ratio is obtained are not clarified, and to further improve the performance, the basic research to clarify the phenomena or Type 1 Basic Research is necessary.On the other hand, to greatly minimize the time needed for practical application, the technological development for multiple functions and increased yield should be the central issue of the increased production efficiency, which is an area that is not a stronghold of the inkjet printing, and can be positioned as the Product Realization Research.As the technological issue to improve the production efficiency, the advancement of multiple nozzle and post-annealing process technology are necessary. As technological issues of multiple functions, the development of functional ink, understanding of applicability of various substrate materials, and control of forming conditions are needed.The technological development issues from Type 1 Basic Research to Product Realization Research become varied with the progress of R&D. Of course, there are limits in terms of human and monetary resources to engage in practical technology for a single research institute like AIST. It is mandatory to effectively appeal the technological concept of the results from the Type 2 Basic Research, and to continue the industry-academia-government collaboration to integrate the researchers and engineers of various fields.Through such development of R&D, we wish to take the laser-assisted inkjet technology toward practical use and to establish it as the core technology of minimal manufacturing.6 Summary and future prospectThis paper is a report of the R&D process of the laser-assisted inkjet technology, which is a development of the wiring technology using inkjet printing and has the potential to become the core technology for practical high-diversity variable-volume production. Comparison with other wiring technologies currently in practice, extraction of issues for

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