Component Comprising a MEMS Microphone and Method for the Production of Said Component

• US 20090232336A1
• Filed: 03/23/2009
• Published: 09/17/2009
• Est. Priority Date: 09/29/2006
• Status: Active Grant

• Current Assignee: TDK Corporation
• Original Assignee: Epcos AG (TDK Corporation)
• Inventors: Pahl, Wolfgang
• Granted Patent: US 8,218,794 B2
• Time in Patent Office: Days
• US Class Current: 381/175
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2924/10155 being other than a cuboid
• CPC Class Codes: H04R 1/04 Structural association of microphone with electric circuitry therefor in deaf-aid sets H04R25/00
• CPC Class Codes: H04R 1/2892 Mountings or supports for transducers
• CPC Class Codes: H04R 19/005 using semiconductor materials
• CPC Class Codes: H04R 31/006 Interconnection of transducer parts of diaphragm and outer suspension by moulding H04R31/003

Abstract

A component with a housing for a MEMS microphone is proposed that has a cavity with terminals arranged in the cavity, a sound inlet opening, and SMT contacts on an outer side. The MEMS chip installed in this housing closes the sound inlet opening from the inside and is connected by means of electrically conductive connections to the terminals of the housing. Opposite the electrically conductive connections, the MEMS chip is in mechanically intimate contact with the housing. The dimensioning of the housing relative to the MEMS chip allows the cavity at the sides of the MEMS chip to be used as an acoustic rear volume.

Claims

1. A component with MEMS microphone, the component comprising:

a housing that has a cavity;

terminals arranged in the cavity;

a sound inlet opening;

SMT contacts on an outer side of the housing;

a MEMS chip with microphone function that is installed in the cavity of the housing and closing the sound inlet opening from the inside, the MEMS chip being connected by means of an electrically conductive connection to the terminals arranged in the cavity of the housing and being connected through the housing to the SMT contacts, the MEMS chip being in mechanically intimate contact with the housing with its surface lying opposite the electrically conductive connections;

wherein a back side volume for the microphone function of the MEMS chip is expanded from the cavity in the housing to sides of the MEMS chip.

2. The component according to claim 1, wherein the mechanically intimate contact is realized by means of an elastic compound that is arranged between the MEMS chip and the housing.

3. The component according to claim 1, wherein the SMT contacts are arranged on the bottom side of the housing and wherein the MEMS chip is mounted on a housing floor by means of a flip-chip-like connection.

4. The component according to claim 1, wherein the MEMS chip is mounted on a housing floor with an electrically conductive adhesive.

5. The component according to claim 1, wherein the MEMS chip is mounted on a housing floor directly or indirectly by means of a solder point.

6. The component according to claim 1, wherein the SMT contacts are arranged on a bottom side of the housing and wherein the sound inlet opening points upward.

7. The component according to claim 1, wherein the housing comprises a metallic material or has a metallic coating.

8. The component according to claim 1, wherein the sound inlet opening is closed tightly by a surface of the MEMS chip, but on an opposite surface of the MEMS chip, between the housing and MEMS chip there is a connection suitable for quick pressure equalization between this surface and the cavity in the housing at sides of the MEMS chip.

9. The component according to claim 1, wherein the housing includes a bottom part and a cover, wherein, in the bottom part, there is a recess defining the cavity.

10. The component according to claim 9, wherein the cover includes a structured metal foil or a structured, metal-coated plastic foil with a sound inlet opening.

11. The component according to claim 9, wherein the cover is bonded, soldered, or welded on the bottom part.

12. The component according to claim 1, wherein the sound inlet opening includes a region with a plurality of smaller openings arranged in this region.

13. The component according to claim 1, wherein the electrically conductive connections comprise spring elements.

14. The component according to claim 1, wherein a housing floor includes a circuit board.

15. The component according to claim 14, wherein the circuit board has vias that connect the terminals to the SMT contacts.

16. A method for producing an encapsulated microphone, the method comprising:

preparing a bottom housing part and a cover that are shaped so that they form a cavity between themselves at joint surfaces connecting to each other, wherein the bottom housing part has SMT contacts mounted on outside and inner terminals that are connected to the SMT contacts by means of vias through the bottom housing part;

locating a MEMS chip with microphone function in the cavity of the bottom housing part and electrically connecting the MEMS chip with the inner terminals; and

mounting the cover on the bottom housing part and attaching the cover with the bottom housing part and a reverse side of the MEMS chip, so that the MEMS chip is enclosed in the cavity but does not completely fill it.

17. The method according to claim 16, wherein the cover includes a sound inlet opening in which an attachment of the cover to the MEMS chip is realized so that the sound inlet opening is closed by the MEMS chip from the cavity.

18. The method according to claim 16, wherein mounting the cover comprises bonding, soldering, or welding the cover to the bottom housing part.

19. The method according to claim 18, wherein mounting the cover comprises bonding the cover that is coated with adhesive.

20. The method according to claim 18, wherein the cover has perforations at least in a region of the joint surfaces and wherein, after the mounting of the cover, an adhesive is pressed through the mentioned perforations, in order to adhere the cover with the bottom housing part and MEMS chip.

21. The method according to claim 16, wherein an electrically conductive or electrically conductive coated cover is used, in which a metallic, or in the cavity, a metal-coated, bottom housing part is used, wherein the cover is connected electrically to the coating of the bottom housing part during or after the mounting.

22. The method according to claim 16, wherein mounting the cover comprises depositing a completely surrounding solder frame on the joint surfaces of the bottom housing part to solder the bottom housing part to the cover, the cover being electrically conductive or electrically conductive coated.

23. The method according to claim 16, wherein the MEMS chip is electrically connected with the inner terminals by spring elements that are provided at the bottom housing part.

24. The method according to claim 23, wherein locating the MEMS chip in the cavity and electrically connecting the MEMS chip with the inner terminals comprises:

depositing and structuring a sacrificial layer on the bottom housing part;

depositing a structured metal layer so that spring elements are created of which a first region sits on the terminals and a second region away from this first region is arranged on the structured sacrificial layer;

placing the MEMS chip on the second region of the spring elements and connecting the MEMS chip to the spring elements;

removing the sacrificial layer before or after connecting, wherein an air gap remains between the regions of the bottom housing part connected to the component.

25. The method according to claim 24,

wherein a first large surface area housing sub-wafer is made available in which a plurality of recesses is formed in advance,

wherein the spring elements are generated for all recesses in a common processing step in the recesses,

wherein each MEMS chip is inserted into a respective recess of the first housing sub-wafer and is mounted on the spring elements,

wherein the recesses are closed with a cover,

wherein the connected bottom housing part and cover are separated into individual housings.

26. The method according to claim 25, wherein depositing the structured metal layer is realized so that inner walls of the recess and the joint surfaces of the bottom housing part are coated with metal.

27. The method according to claim 25, wherein, each MEMS chip is handled in an intermediate step, each MEMS chip being mounted at a correct spacing with the reverse side lying opposite their electrical contact surfaces on an auxiliary carrier that is removed again after connection of the MEMS chip to the spring elements.

28. The method according to claim 24, wherein the sacrificial layer comprises an organic layer that can decompose thermally, without forming solid residues.

29. The method according to claim 28, wherein removing the sacrificial layer is performed together with a soldering or bonding process with which the MEMS chip is connected to spring elements.