Patent ID: 7538636

Claim:
An electronic part which includes a substrate, a comb-type electrode that is disposed on an upper surface of the substrate, and a protective film that covers the comb-type electrode and has an uneven shape at a top surface thereof, wherein a height from the surface of the substrate which is in contact with the protective film to a top part of a convex portion of the protective film is t, a height from the surface of the substrate which is in contact with the protective film to a bottom part of a concave portion of the protective film is t 1 , a height (t-t 1 ) from the top part of the convex portion of the protective film to the bottom part of the concave portion of the protective film is t 2 , a pitch width of one pitch in the uneven shape of the protective film is L, a width of one pitch of the convex portion of an unevenness in the uneven shape of the protective film is L 1 , a width of one pitch of the concave portion is L 2 , a pitch width of one pitch of the comb-type electrode is p, a width of one of electrode fingers which form the comb-type electrode is p 1 , a width between the electrode fingers is p 2 , and a film thickness of the comb-type electrode is h so as to satisfy t 2 ≦h, and wherein correlations of L≈p, p 1 +p 2 =p, L 1 +L 2 =L, L 1 <p 1 and L 2 >p 2 are satisfied).