Microphone Unit, Method of Manufacturing Microphone Unit, Electronic Apparatus, Substrate for Microphone Unit and Method of Manufacturing Substrate for Microphone Unit

A method of manufacturing a microphone unit, comprising steps of:

• forming a hollow portion transmitting a sound in a substrate having a first surface where a vibrating portion converting a sound to an electric signal is set and a second surface opposite to said first surface;
• forming a first substrate sound hole portion causing said hollow portion and said vibrating portion to communicate with each other on said first surface of said substrate;
• forming a second substrate sound hole portion causing said hollow portion and the exterior to communicate with each other on said first surface of said substrate;
• forming a coating liquid draining hole portion causing said hollow portion and the exterior to communicate with each other on said second surface;
• forming a coating layer on an inner surface of said hollow portion of said substrate;
• and
• sealing said coating liquid draining hole portion after the formation of said coating layer.

An electronic apparatus comprising a microphone unit, wherein

• said microphone unit includes:
• a vibrating portion converting a sound to an electric signal;
• a substrate having a first surface where said vibrating portion is set and a second surface opposite to said first surface and including a hollow portion transmitting a sound therein;
• and
• a coating layer formed on an inner surface of said hollow portion of said substrate,
• said substrate further includes:
• a first substrate sound hole portion provided on said first surface for causing said hollow portion and said vibrating portion to communicate with each other,
• a second substrate sound hole portion provided on said first surface for causing said hollow portion and the exterior to communicate with each other, and
• a coating liquid draining hole portion provided on said second surface for causing said hollow portion and the exterior to communicate with each other, and
• said coating liquid draining hole portion is sealed.

A substrate for a microphone unit, comprising:

• a substrate having a first surface where a vibrating portion converting a sound to an electric signal is set and a second surface opposite to said first surface and including a hollow portion transmitting a sound therein;
• and
• a coating layer formed on an inner surface of said hollow portion of said substrate, wherein
• said substrate further includes:
• a first substrate sound hole portion provided on said first surface for causing said hollow portion and said vibrating portion to communicate with each other,
• a second substrate sound hole portion provided on said first surface for causing said hollow portion and the exterior to communicate with each other, and
• a coating liquid draining hole portion provided on said second surface for causing said hollow portion and the exterior to communicate with each other, and
• said coating liquid draining hole portion is sealed.

A method of manufacturing a substrate for a microphone unit, comprising steps of:

• forming a hollow portion transmitting a sound in a substrate having a first surface where a vibrating portion converting a sound to an electric signal is set and a second surface opposite to said first surface;
• forming a first substrate sound hole portion causing said hollow portion and said vibrating portion to communicate with each other on said first surface of said substrate;
• forming a second substrate sound hole portion causing said hollow portion and the exterior to communicate with each other on said first surface of said substrate;
• forming a coating liquid draining hole portion causing said hollow portion and the exterior to communicate with each other on said second surface;
• forming a coating layer on an inner surface of said hollow portion of said substrate;
• and
• sealing said coating liquid draining hole portion after the formation of said coating layer.