| 摘要 |
PROBLEM TO BE SOLVED: To reduce warpage of a substrate/ferrite complex by forming a multitude of cracks on the surface of a ferrite magnetic film for a magnetic device which is not in contact with a substrate, and by specifying an average of diameter of circles to which area of parts surrounded by cracks is converted. SOLUTION: Ferrite powder which is formulated in a specified composition and a binder such as ethylcellulose are mixed to form a paste for easy control of crack introduction in the ferrite magnetic film for a magnetic device and for a low manufacturing cost. The paste is applied to a substrate by screen printing method or the like, is baked and cooled to manufacture the ferrite magnetic film. For intentionally introducing cracks on the surface of the ferrite, the baking temperature is set lower than 900 deg.C and the cooling speed is set higher than the normal speed being about 5 deg.C/min. By setting the average of equivalent diameter of parts surrounded by cracks to 100μm or smaller, a proper film state with a little amount of warpage and without any peeling can be obtained.
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