| 摘要 |
PROBLEM TO BE SOLVED: To sustain water repellency for a long term by setting the etching depth of a protruding and recessed structure being formed on the surface of a basic material at a specified value or less. SOLUTION: A water repellent structure is provided with a protruding and recessed structure comprising recesses 17 and protrusions 18 formed on the surface of a silicon substrate. Consequently, an air layer is generated in the recesses 17. In order to exhibit an water repellent function, contact angle of waterθis set at 120 deg. or above (about 90 deg. or above in case of ink liquid drop). Size of the recess 17 is set such that a liquid drop touches the air layer without dropping into the recess 17. Since the diameter of ink drop is about 10μm, A [width of protrusion (by mask design)] and B [width of trench (by mask design)] are preferably set in the range of 1-10μm and C machining amount [depth (10μm or less), by etching time]} is preferably set at about 1μm or above. Uniformity of height of the protrusions is set within about 0.1 time of the value of A, B in view point of scratch resistance.
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