ELECTRO-ACOUSTIC TRANSDUCER COMPRISING A MEMS SENSOR

• US 20100195864A1
• Filed: 07/29/2008
• Published: 08/05/2010
• Est. Priority Date: 08/02/2007
• Status: Active Grant

• Current Assignee: Knowles IPC Sendirian Berhad (Knowles Corporation)
• Original Assignee: NXP B.V. (NXP Semiconductors NV)
• Inventors: Leitner, Stefan, Lutz, Josef
• Granted Patent: US 8,526,665 B2
• Time in Patent Office: Days
• US Class Current: 381/433
• CPC Class Codes: H04R 19/005 using semiconductor materials
• CPC Class Codes: H04R 19/04 Microphones H04R19/01 takes precedence

Abstract

An electro-acoustic transducer (1) is disclosed, comprising a substrate (2) that comprises conducting paths (3), a cover (4) attached to said substrate (2) thus forming an inner chamber (A) and a space (B) outside said chamber (A), wherein said cover (4) comprises one or more ports (5). A MEMS sensor (6) of said transducer (1) has at least one hole (7) extending from a first side (C) to a second side (D). A membrane (8) is arranged in said hole (7) transverse to the hole axis (E) thus forming a first hole space (a) and a second hole space (b). The sensor (6) furthermore has electrical connectors (9) designed to carry electrical signals representing sound acting on said membrane (8), which connectors (9) are connected to said conducting paths (3). According to the invention, said MEMS sensor (6) is arranged inside said chamber (A) in such a way that said second hole space (b) is connected to said outside space (B) via said port or ports (5) and said first hole space (a) is connected to said inner chamber (A).

Claims

1. Electro-acoustic transducer, comprising:

a substrate comprising a plurality of conducting paths; and

a cover attached to said substrate thus forming an inner chamber and a space outside said chamber, wherein said cover comprises at least one port; and

a Micro Electro Mechanical Systems sensor, MEMS sensor for short, comprising a first side and second side and at least one hole extending from the first side to the second side and a membrane being arranged in said hole transverse to the hole axis thus forming a first hole space and a second hole space and having a plurality of electrical connectors adapted to carry electrical signals representing sound acting on said membrane, the connectors being connected to said conducting paths; and

wherein said MEMS sensor is arranged inside said chamber in such a way that said second hole space is connected to said outside space via said at least one port and said first hole space is connected to said inner chamber.

2. Electro-acoustic transducer according to claim 1, wherein said electrical connectors are arranged on said first side and connected to said conducting paths by flip chip technology.

3. Electro-acoustic transducer according to claim 2, wherein said connections between said electrical connectors and said conducting paths form channels between said substrate and said MEMS sensor, which channels connect said first hole space to said inner chamber.

4. Electro-acoustic transducer according to claim 2, wherein a groove is formed in said first side, which groove connects said first hole space to said inner chamber.

5. Electro-acoustic transducer according to claim 1, wherein said electrical connectors are arranged on said second side and connected to said conducting paths by wire bonds.

6. Electro-acoustic transducer according to claim 5, wherein a groove is formed in first side, which groove connects said first hole space to said inner chamber.

7. Electro-acoustic transducer according to claim 1, further comprising a mechanism for equalizing air pressure between said chamber and said outside space.

8. Electro-acoustic transducer according to claim 7, wherein said equalizing mechanism includes at least one of a hole in the substrate;

a hole in the cover;

a hole in the MEMS sensor;

a hole in the membrane, and a port formed by said cover and the substrate or the MEMS sensor, in particular by a break of a seal between said cover and the substrate or the MEMS sensor.

9. Electro-acoustic transducer according to claim 1, additionally comprising one or more integrated circuits inside said chamber, which cooperate with said MEMS sensor.

10. Electro-acoustic transducer according to claim 1, wherein said cover is air-tightly attached to said substrate and to said second side of said MEMS sensor.

11. Electro-acoustic transducer according to claim 1, wherein the volume of at least one of said first hole space and said second hole space is zero.

12. Electro-acoustic transducer according to claim 1, further comprising a dust cover over the cover forming a gap between them, wherein said dust cover comprises at least one port which is offset against said port or ports of said cover.

13. Electro-acoustic transducer according to claim 12, wherein an adhesive is applied to at least one of the surface of the cover facing the gap and the surface of the dust cover facing the gap.

14. Electro-acoustic transducer according to claim 1, wherein said cover comprises a dent that forms a gap together with a housing of a device, into which said transducer is built.

15. Electro-acoustic transducer according to claim 14, wherein an adhesive is applied to the surface of the dent.