Patent ID: 7956430

Claim:
An acceleration sensor device comprising: a substrate having a front surface and a rear surface, the substrate including a weight portion, a frame portion surrounding the weight portion, and a brace portion connecting the frame portion to the weight portion; at least one sensor element attached to or buried in the brace portion; a first groove portion having a front surface pattern in the front surface; a second groove portion having a rear surface pattern in the rear surface, at least parts of said first groove portion and said second groove portion overlapping so that the overlapping parts of the first and second groove portions become through-holes that extend entirely through the substrate; and at least one groove width variation portion including a concave portion extending into at least one inner wall of said first groove portion at the through-holes, wherein a part of said concave portion of said at least one groove width variation portion does not overlap the second groove portion, and said at least one groove width variation portion includes a stepwise shape in a plane parallel to said first front surface.