| 摘要 |
PURPOSE: To form a thick film of a porous material having smooth surface and pores adapted for the heat insulation layer of a thermal head by a sol-gel method by previously forming a resin layer on a board before a porous gel is formed. CONSTITUTION: An alumina board 1 of a predetermined position for forming a heat insulation layer 2 is coated with varnish silicone resin, and baked to form a resin film 8 having a thickness of about 1μm. Then, the film 8 of the board 1 is coated in a protrusion state with gel 9 obtained by hydrolyzing a metallic alkoxide. Thereafter, the gel 9 is dried at a predetermined temperature, further dehydrating condensing reaction is expedited, thereby forming a fine and relatively uniform porous gel 10 of several 10Å. Then, the board 1 formed with the gel 10 is heat treated at a predetermined temperature or higher for thermally decomposing the layer 8 operated as an absorber, the layer 8 is thermally decomposed, the layer 8 is removed from above the board, and the gel 10 is directly sintered on the board 1.
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