Grant-in-Aid for Scientific Research (C)
|Allocation Type||Single-year Grants|
|Research Institution||TOKAI UNIVERSITY|
YASUNAGA Nobuo Tokai University School of Engineering Professor, 工学部, 教授 (70256171)
|Project Period (FY)
1996 – 1997
Completed(Fiscal Year 1997)
|Budget Amount *help
¥1,800,000 (Direct Cost : ¥1,800,000)
Fiscal Year 1997 : ¥200,000 (Direct Cost : ¥200,000)
Fiscal Year 1996 : ¥1,600,000 (Direct Cost : ¥1,600,000)
|Keywords||YAG laser / Micro-fabrication / Sapphire / Laser etching / Laser PVD / Joining|
This study aims to find the possibility of micro-patterning on so-called difficult-to-machine materials like sapphire, silicon carbide and diamond by YAG laser irradiation in etching reagent and of high strength joining of these materials by YAG laser PVD.
As for the research on micro-patterning, following results were obtained by laser irradiation experiments on polished sapphire surfaces in a etchant-circulable vessel developed.
(1) Thin carbon film deposition about 0.2mum enables to absorb YAG laser energy on sapphire surfaces which is tranparent to YAG laser wave length.
(2) If a laser irradiation condition is chosen so as to generate no melting but only micro-crack on the sapphire surface, fine grooves can be formed by subsequent etching in hot H_3PO_4 solution.
(3) The groove depth obtained can be controlled in the range of 20-220 mum by changing the solution density and laser irradiation conditions.
(4) Sharp patterned grooves can be formed by laser irradiation through a shaped metal
(5) Another new phenomenon was observed that plasma plume generated at the focused point on Si_3N_4 ceramics target which YAG laser is irradiated onto through an uncoated sapphire plate attacks the sapphire plate generating a through-hole, a crater or deposited film according to the distance between the sapphire plate and the target aud laser power.
As for joining research, a prototype optical system was set up in a vacuum chamber for conducting laser PVD by irradiating YAG laser on a rotating Al_2O_3 target from tilted angle. It was revealed that uniform transparent alumina film with high adhesion strength can be coated to glass plate.
These research works have clarified that patterned groove can be easily formed on difficult-to-machine sapphire surfaces by a sequential process of YAG laser irradiation and chemical etching and uniform thin alunina film deposition with high adhesion strength by YAG laser irradiation is possible suggesting that sapphire plates can be joined each other using glass film as an adhesive material. Less