Method for manufacturing three-dimensionally structured member, method for manufacturing acceleration pickup, acceleration pickup, and acceleration sensor

A method for manufacturing a three-dimensional structural member including four portions different in thickness by molding a flat plate-like base, the method comprising:

• a mask forming step of forming a mask over at least one principal surface of the base;
• a first mask removing step of removing a part of the mask corresponding to a thinnest portion of the three-dimensional structural member;
• a first etching step of etching an exposed portion of the base corresponding to the thinnest portion of the three-dimensional structural member;
• a second mask removing step of removing a part of the mask corresponding to a second thinnest portion of the three-dimensional structural member;
• a second etching step of etching exposed portions of the base corresponding to the second thinnest portion and the thinnest portion of the three-dimensional structural member;
• a third mask removing step of removing a part of the mask corresponding to a third thinnest portion of the three-dimensional structural member;
• and
• a third etching step of etching exposed portions of the base corresponding to the third thinnest portion, the second thinnest portion, and the thinnest portion of the three-dimensional structural member,
• wherein the second mask removing step is performed only after a start of the first etching step.

A method for manufacturing an acceleration pickup member for use in an acceleration sensor by molding a flat plate-like base, the acceleration pickup member including a pendulum section, a hinge section coupled to the pendulum section, a support section supporting the pendulum section through the hinge section, and a through groove section between the pendulum section and the support section, the method comprising:

• a mask forming step of forming a mask over each principal surface of the base;
• a first mask removing step of removing a part of the mask corresponding to the through groove section;
• a first etching step of etching an exposed portion of the base corresponding to the through groove section;
• a second mask removing step of removing a part of the mask corresponding to the hinge section;
• a second etching step of etching exposed portions of the base corresponding to the hinge section and the through groove section;
• a third mask removing step of removing a part of the mask corresponding to the pendulum section;
• and
• a third etching step of etching exposed portions of the base corresponding to the pendulum section, the hinge section, and the through groove section,
• wherein the second mask removing step is performed only after a start of the first etching step.

An acceleration pickup member for use in an acceleration sensor, the acceleration pickup member comprising:

• a pendulum section swinging in accordance with acceleration;
• a hinge section coupled to the pendulum section;
• a support section supporting the pendulum section through the hinge section;
• and
• a through groove section between the pendulum section and the support section, wherein
• an interior angle of a center section in a thickness direction in a side surface opposite to the support section of the pendulum section is 90°±10°, and
• an interior angle in a boundary between the pendulum section and the hinge section is 120°±10°.