Top port multi-part surface mount silicon condenser microphone

• US 9,006,880 B1
• Filed: 01/14/2014
• Issued: 04/14/2015
• Est. Priority Date: 11/28/2000
• Status: Expired due to Fees

• Current Assignee: Knowles Electronics Llc (Knowles Corporation)
• Original Assignee: Knowles Electronics Llc (Knowles Corporation)
• Inventors: Minervini, Anthony D.
• Primary Examiner(s): Chambliss, Alonzo
• Application Number:
  US14/155,025
• Time in Patent Office: 455 Days
• US Class Current: 257/704
• CPC Class Codes: B81B 2201/0257 Microphones or microspeakers
• CPC Class Codes: B81B 2207/092 Buried interconnects in the substrate or in the lid
• CPC Class Codes: B81B 3/0021 Transducers for transforming electrical into mechanical energy or vice versa dynamo-electric machines H02K99/00; electrostatic machines H02N1/00; piezoelectric devices H10N30/00
• CPC Class Codes: B81B 7/0038 using materials for controlling the level of pressure, contaminants or moisture inside of the package, e.g. getters
• CPC Class Codes: B81B 7/0058 for protecting against damages due to external chemical or mechanical influences, e.g. shocks or vibrations
• CPC Class Codes: B81B 7/0061 suitable for fluid transfer from the MEMS out of the package or vice versa, e.g. transfer of liquid, gas, sound
• CPC Class Codes: B81B 7/0064 for protecting against electromagnetic or electrostatic interferences
• CPC Class Codes: B81B 7/007 Interconnections between the MEMS and external electrical signals
• CPC Class Codes: B81C 1/00158 Diaphragms, membranes manufacture process for semi-permeable inorganic membranes B01D67/0039
• CPC Class Codes: B81C 1/00301 Connecting electric signal lines from the MEMS device with external electrical signal lines, e.g. through vias
• CPC Class Codes: B81C 3/00 Assembling of devices or systems from individually processed components
• CPC Class Codes: H01L 21/78 with subsequent division of the substrate into plural individual devices cutting to change the surface-physical characteristics or shape of semiconductor bodies H01L21/304
• CPC Class Codes: H01L 23/10 characterised by the material or arrangement of seals between parts, e.g. between cap and base of the container or between leads and walls of the container
• CPC Class Codes: H01L 23/15 Ceramic or glass substrates H01L23/142, H01L23/145, H01L23/147 take precedence
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 2924/1461 MEMS
• CPC Class Codes: H04R 1/04 Structural association of microphone with electric circuitry therefor in deaf-aid sets H04R25/00
• CPC Class Codes: H04R 1/222 for microphones H04R1/24, H04R1/26 take precedence
• CPC Class Codes: H04R 1/2892 Mountings or supports for transducers
• CPC Class Codes: H04R 19/005 : using semiconductor materials
• CPC Class Codes: H04R 19/016 : for microphones
• CPC Class Codes: H04R 19/04 : Microphones H04R19/01 takes precedence
• CPC Class Codes: H04R 2201/003 : Mems transducers or their use of the electrostatic type H04R19/005
• CPC Class Codes: H04R 2225/49 : Reducing the effects of electromagnetic noise on the functioning of hearing aids, by, e.g. shielding, signal processing adaptation, selective (de)activation of electronic parts in hearing aid
• CPC Class Codes: H04R 23/00 : Transducers other than those covered by groups H04R9/00 - H04R21/00 diaphragms for transducers of the distributed-mode type H04R7/045
• CPC Class Codes: H04R 2410/03 : Reduction of intrinsic noise in microphones
• CPC Class Codes: H04R 3/00 : Circuits for transducers , loudspeakers or microphones
• CPC Class Codes: H04R 31/006 : Interconnection of transducer parts of diaphragm and outer suspension by moulding H04R31/003
• CPC Class Codes: Y10T 29/49005 : Acoustic transducer
• CPC Class Codes: Y10T 29/4908 : Acoustic transducer
• CPC Class Codes: Y10T 29/49798 : Dividing sequentially from leading end, e.g., by cutting or breaking

Abstract

The present invention relates to a surface mount package for a micro-electro-mechanical system (MEMS) microphone die and methods for manufacturing the surface mount package. The surface mount package uses a limited number of components that simplifies manufacturing and lowers costs. The surface mount package features a substrate that performs functions for which multiple components were traditionally required, including providing an interior surface on which the MEMS microphone die is mechanically attached, providing an interior surface for making electrical connections between the MEMS microphone die and the package, and providing an exterior surface for surface mounting the microphone package to a device'"'"'s printed circuit board and for making electrical connections between the microphone package and the device'"'"'s circuit board. The microphone package has a substrate with metal pads on its top and bottom surfaces, a sidewall spacer, and a lid. A MEMS microphone die is mounted on the substrate, and the substrate, the sidewall spacer, and the lid are joined together to form the MEMS microphone.

Claims

1. A solder reflow surface mount micro-electro-mechanical system (MEMS) microphone, the microphone comprising:

a lid having top and bottom surfaces and comprising at least one conductive layer, at least one non-conductive layer, and an acoustic port, wherein at least one the conductive layer comprises the bottom surface of the lid, and wherein the bottom surface has an attachment region and an interior region, the attachment region positioned between the interior region and the edges of the lid, and completely bounding the interior region;

a sidewall spacer having top and bottom surfaces and comprising at least two conductive layers with a center layer of non-conductive material having predefined thickness disposed between the two conductive layers, wherein one conductive layer comprises the top surface of the sidewall spacer and the other conductive layer comprises the bottom surface of the sidewall spacer, and wherein the sidewall spacer further comprises an opening having walls covered with conductive material, and the opening walls extend through the center layer to the top surface and the bottom surface;

a substrate comprising;

a base layer comprised of at least one layer of non-conductive material, wherein the base layer has a planar top surface and a planar bottom surface, the top surface having an interior region and an attachment region, the attachment region disposed between the interior region and the edges of the base layer, and completely bounding the interior region;

a first plurality of metal pads disposed on the top surface of the base layer, wherein at least one pad of the first plurality of metal pads is located in the attachment region of the top surface of the base layer;

a second plurality of metal pads disposed on the bottom surface of the base layer, the second plurality of metal pads arranged to be within the edges of the base layer; and

one or more electrical pathways disposed completely within the base layer, wherein the pathways electrically couple one or more of the first plurality of metal pads on the top surface of the base layer to one or more of the second plurality of metal pads on the bottom surface of the base layer, and wherein the at least one metal pad located in the attachment region of the top surface of the base layer is electrically coupled to one or more of the second plurality of metal pads;

a MEMS microphone die mounted on the top surface of the base layer, and electrically coupled to at least one of the first plurality of metal pads on the top surface of the base layer;

wherein the substrate, the sidewall spacer and the lid cooperate with each other to form a housing, wherein the edges of the substrate, the sidewall spacer and the lid create side surfaces substantially perpendicular to the bottom surface of the substrate, and wherein the housing has an internal acoustic chamber for the MEMS microphone die;

wherein the bottom surface of the sidewall spacer is coupled to the attachment region of the top surface of the substrate such that the opening of the sidewall spacer and the interior region of the top surface of the substrate are aligned, and the conductive material on the opening walls of the sidewall spacer is electrically coupled to the at least one metal pad located in the attachment region of the substrate;

wherein the top surface of the sidewall spacer is coupled to the attachment region of the bottom surface of the lid such that the opening of the sidewall spacer and the interior region of the bottom surface of the lid are aligned, and the conductive layer of the lid is electrically coupled to the conductive material on the opening walls of the sidewall spacer; and

wherein the interior region of the top surface of the substrate, the opening walls of the sidewall spacer, and the interior region of the bottom surface of the lid, when attached, define the internal acoustic chamber for the MEMS microphone die.

2. A surface mount MEMS microphone according to claim 1, further comprising at least one passive electrical element electrically coupled between one of the first plurality of metal pads and one of the second plurality of metal pads.

3. A surface mount MEMS microphone according to claim 2, wherein the at least one passive electrical element is disposed within the base layer of the substrate.

4. A surface mount MEMS microphone according to claim 2, wherein the at least one passive electrical element is disposed within the base layer of the substrate and comprises a dielectric or resistive material that is different from the non-conductive material of the base layer.

5. A surface mount MEMS microphone according to claim 2, wherein the at least one passive electrical element filters one or more of an input signal, an output signal, or input power.

6. A surface mount MEMS microphone according to claim 1, wherein the lid is attached to the sidewall spacer with a first conductive material, and the substrate is attached to the sidewall spacer with a second conductive material.

7. A surface mount MEMS microphone according to claim 1, wherein the housing protects the MEMS microphone die from at least one of light, electromagnetic interference, and physical damage.

8. A surface mount MEMS microphone according to claim 1, wherein the housing further comprises a material that substantially blocks environmental contaminants from entering the acoustic chamber through the acoustic port.

9. A surface mount MEMS microphone according to claim 1, wherein the lid further comprises a material layer that that substantially blocks environmental contaminants from entering the acoustic chamber through the acoustic port.

10. A surface mount MEMS microphone according to claim 1, wherein the acoustic port is disposed in a position offset from the lid centerpoint.

11. A surface mount MEMS microphone according to claim 1, wherein sidewall spacer comprises multiple layers of conductive and non-conductive material, and the conductive material on the opening walls electrically couples the conductive layers to each other.

12. A surface mount MEMS microphone according to claim 1, wherein the first and second pluralities of metal pads on the base layer of the substrate are plated with a metal that is different from the metal used for the first and second pluralities of metal pads.

13. A surface mount MEMS microphone according to claim 1, wherein the base layer of the substrate further comprises at least one additional non-conductive layer and at least one additional conductive layer.

14. A surface mount MEMS microphone according to claim 1, wherein the base layer of the substrate further comprises a recess disposed therein, and MEMS microphone die is positioned over the recess.

15. A surface mount MEMS microphone according to claim 1, wherein the base layer of the substrate further comprises an internal cavity with an aperture in the top surface of the base layer, and the MEMS microphone die is positioned over the aperture in the top surface of the base layer.

16. A surface mount MEMS microphone according to claim 1, wherein the acoustic port disposed in the lid is a first acoustic port, and the base layer of the substrate further comprises a second acoustic port, and wherein the MEMS microphone die is positioned over the second acoustic port in the base layer.

17. A surface mount MEMS microphone according to claim 16, wherein the base layer of the substrate further comprises a material layer that that substantially blocks environmental contaminants from reaching the MEMS microphone die through the second acoustic port in the base layer.

18. A surface mount MEMS microphone according to claim 1, wherein electrical continuity is present between the conductive layer in the lid, the conductive material on the opening walls of the sidewall spacer, and at least one of the second plurality of metal pads.

19. A surface mount MEMS microphone according to claim 1, wherein the at least one non-conductive layer of the lid, the center layer of non-conductive material of the sidewall spacer, and the non-conductive material of the base layer each have a substantially similar predetermined coefficient of thermal expansion.

20. A solder reflow surface mount micro-electro-mechanical system (MEMS) microphone, the microphone comprising:

a top portion having upper and lower surfaces and comprising at least one metal layer, at least one printed circuit board material layer, and an acoustic port, wherein the at least one metal layer comprises the lower surface of the top portion, and wherein the lower surface has a coupling area and an inner area, the coupling area being arranged between the inner area and the edges of the top portion, and completely surrounding the inner area;

a spacer portion having upper and lower surfaces and comprising at least two metal layers with at least one printed circuit board material layer of predefined thickness disposed between the two metal layers, wherein one metal layer comprises the upper surface of the spacer portion and the other metal layer comprises the lower surface of the spacer portion, and wherein the spacer portion further comprises a window having walls covered with a metal layer, and the window walls extend through the printed circuit board material layer to the upper surface and the lower surface;

a bottom portion comprising;

a base layer comprised of at least one layer of printed circuit board material, wherein the base layer has a substantially flat upper surface and a substantially flat lower surface, the upper surface having an inner area and a coupling area, the coupling area located between the inner area and the edges of the base layer, and completely surrounding the inner area;

a plurality of metal pads located on the upper surface of the base layer, wherein at least one pad of the plurality of metal pads is positioned in the coupling area of the upper surface of the base layer;

a plurality of solder pads located on the lower surface of the base layer, the plurality of solder pads arranged to be within the edges of the base layer;

one or more electrical connections passing through the base layer, wherein the connections electrically couple one or more of the plurality of metal pads on the upper surface of the base layer to one or more of the plurality of solder pads on the lower surface of the base layer, and wherein the at least one metal pad positioned in the coupling area of the upper surface of the base layer is electrically coupled to one or more of the plurality of solder pads; and

at least one passive electrical element electrically coupled between one of the plurality of metal pads and one of the plurality of solder pads;

a MEMS microphone die physically coupled to the upper surface of the base layer, and electrically coupled to at least one of the plurality of metal pads on the upper surface of the base layer;

wherein the bottom portion, the spacer portion and the top portion cooperate with each other to form a housing having a substantially rectangular shape with an internal acoustic chamber for the MEMS microphone die, and that protects the MEMS microphone die from at least one of light, electromagnetic interference, and physical damage;

wherein a conductive material physically couples the lower surface of the spacer portion to the coupling area of the upper surface of the bottom portion such that the window of the spacer portion and the inner area of the upper surface of the bottom portion are aligned, and the metal layer on the window walls of the spacer portion is electrically coupled to the at least one metal pad positioned in the coupling area of the bottom portion;

wherein a conductive material physically couples the upper surface of the spacer portion to the coupling area of the lower surface of the top portion such that the window of the spacer portion and the inner area of the lower surface of the top portion are aligned, and the metal layer of the top portion is electrically coupled to the metal layer on the window walls of the spacer portion;

wherein electrical continuity is present between the at least one metal layer in the top portion, the metal layer on the window walls of the spacer portion, and at least one of the plurality of solder pads; and

wherein the inner area of the upper surface of the bottom portion, the window walls of the spacer portion, and the inner area of the lower surface of the top portion, when attached, define the internal acoustic chamber that acoustically couples the MEMS microphone die to the acoustic port.

21. A surface mount MEMS microphone according to claim 20, wherein the housing further comprises a material that substantially blocks environmental contaminants from entering the acoustic chamber through the acoustic port.

22. A surface mount MEMS microphone according to claim 20, wherein the acoustic port is disposed in a position offset from the centerpoint of the top portion.

23. A surface mount MEMS microphone according to claim 20, wherein the bottom portion further comprises a cavity with an opening in the upper surface of the base layer, and the MEMS microphone die is positioned over the opening in the upper surface of the base layer such that the MEMS microphone die is acoustically coupled to the cavity.

24. A surface mount MEMS microphone according to claim 20, wherein the base layer of the bottom portion further comprises an acoustic port, and wherein the MEMS microphone die is positioned over the acoustic port in the bottom portion.

25. A surface mount MEMS microphone according to claim 20, wherein the at least one passive electrical element is disposed within the base layer of the bottom portion and comprises a dielectric or resistive material that is different from the printed circuit board material of the base layer.

26. A surface mount MEMS microphone according to claim 25, wherein the at least one passive electrical element filters one or more of an input signal, an output signal, or input power.

27. A surface mount MEMS microphone according to claim 20, wherein the printed circuit board layer of the spacer portion further comprises additional layers of printed circuit board material alternating with additional metal layers, and the conductive material on the window walls electrically couples the additional metal layers to each other.

28. A surface mount MEMS microphone according to claim 20, wherein the base layer of the bottom portion further comprises at least one additional non-conductive layer and at least one additional conductive layer.

29. A surface mount MEMS microphone according to claim 20, wherein the first enclosure element further comprises additional metal layers alternating with the FR-4 printed circuit board material layers, and the metal layer of the interior open volume walls electrically couples the additional metal layers to each other.

30. A solder reflow surface mount micro-electro-mechanical system (MEMS) microphone, the microphone comprising:

a base substrate comprising;

a core layer comprised of at least one layer of FR-4 printed circuit board material, wherein the core layer has a substantially flat top surface and a substantially flat bottom surface, the top surface having a die mount region and an attachment region, the attachment region positioned between the die mount region and the edges of the core layer, and completely surrounding the die mount region;

a plurality of metal pads located on the top surface of the core layer, wherein at least one pad of the plurality of metal pads is located in the attachment region of the top surface of the core layer;

a plurality of solder pads located on the bottom surface of the core layer, the plurality of solder pads arranged to be within the edges of the core layer;

a plurality of electrical connections passing through the core layer that electrically couple one or more of the plurality of metal pads on the top surface of the core layer to one or more of the plurality of solder pads on the bottom surface of the core layer, and wherein the at least one metal pad located in the attachment region of the top surface of the core layer is electrically coupled to one or more of the plurality of solder pads; and

a pressure-equalizing MEMS microphone die having an internal acoustic channel mounted in the die mount region of the core layer, and electrically coupled to one or more of the metal pads on the top surface of the core layer;

an enclosure comprising;

a first enclosure element having substantially flat top and bottom surfaces and comprising at least two metal layers with multiple FR-4 printed circuit board material layers of predefined thickness disposed between the two metal layers, wherein one metal layer comprises the top surface of the first enclosure element and the other metal layer comprises the bottom surface of the first enclosure element;

a second enclosure element having substantially flat top and bottom surfaces and comprising at least one metal layer, at least one FR-4 printed circuit board material layer, and an acoustic port that is disposed in an offset position from the centerpoint of the second enclosure element, wherein the metal layer comprises the bottom surface of the second enclosure element, and wherein the bottom surface has an attachment region and an inner region, the attachment region being arranged between the attachment region and the edges of the second enclosure element, and completely surrounding the attachment region;

wherein a conductive material physically couples the top surface of the first enclosure element to the attachment region of the bottom surface of the second enclosure element;

wherein the first enclosure element comprises an interior open volume with walls, thereby exposing the inner region of the bottom surface of the second enclosure element; and

wherein the interior open volume walls have a metal layer that is electrically connected to the bottom surface metal layer of the second enclosure element;

the base substrate and the enclosure being joined together to form a housing that has an internal acoustic chamber for the MEMS microphone die, and that protects the MEMS microphone die from at least one of light, electromagnetic interference, and physical damage, wherein a conductive material physically couples the bottom surface metal layer of the first enclosure element to the attachment region of the base substrate, and wherein the interior open volume of the first enclosure element is aligned with the die mount region of the base substrate and the metal pad positioned in the attachment region is electrically coupled to the metal layer of the interior open volume walls in the first enclosure element;

wherein the interior region of the bottom surface of the second enclosure element, the interior open volume walls of the first enclosure element, and the die mount region of the base substrate define the internal acoustic chamber that is a front volume for the MEMS microphone die, and acoustically couples the acoustic port to the MEMS microphone die;

wherein electrical continuity exists between the metal layer of the second enclosure element, the metal-covered interior open volume walls of the enclosure element, and one or more of the plurality of solder pads on the base substrate; and

wherein the length of the base substrate and the length of the enclosure are substantially equal, and the width of the base substrate and the width of the enclosure are substantially equal.

31. A surface mount MEMS microphone according to claim 30, further comprising at least one passive electrical element electrically coupled between one of the plurality of metal pads and one of the plurality of solder pads, and disposed within the core layer of the base substrate.

32. A surface mount MEMS microphone according to claim 31, wherein the at least one passive electrical element is disposed within the core layer of the base substrate and comprises a dielectric or resistive material that is different from the FR-4 printed circuit board material of the core layer.

33. A surface mount MEMS microphone according to claim 32, wherein the at least one passive electrical element filters one or more of an input signal, an output signal, or input power.

34. A surface mount MEMS microphone according to claim 30, wherein the housing further comprises a material that substantially blocks environmental contaminants from entering the acoustic chamber through the acoustic port.

35. A surface mount MEMS microphone according to claim 30, wherein the core layer of the base substrate further comprises an internal cavity with an aperture in the top surface of the core layer, and the internal acoustic channel of the MEMS microphone die is positioned over and acoustically coupled to the aperture in the top surface of the core layer.

36. A solder reflow surface mount micro-electro-mechanical system (MEMS) microphone, the microphone comprising:

a pressure-equalizing MEMS microphone die having an internal acoustic channel;

a housing for the MEMS microphone die comprising;

a first housing element having substantially flat top and bottom surfaces and comprising at least at least one metal layer, at least one printed circuit board material layer, and an acoustic port, wherein the at least one metal layer comprises the bottom surface of the first housing element, wherein the bottom surface has an attachment region and an interior region, the attachment region located between the interior region and the edges of the first housing element and completely surrounding the interior region, and wherein the acoustic port is disposed in a position offset from the centerpoint of the first housing element;

a second housing element having substantially flat top and bottom surfaces and comprising at least first and second metal layers with multiple printed circuit board material layers of predefined thickness disposed between the first and second metal layers, wherein the first metal layer comprises the top surface of the second housing element and the second metal layer comprises the bottom surface of the second housing element, and wherein the second housing element further comprises an aperture having metal-covered walls, and the aperture walls extend through the printed circuit board material layer to the top and bottom surfaces of the second housing element;

a third housing element comprising;

a core layer comprised of at least one layer of printed circuit board material, wherein the core layer has a substantially flat top surface and a substantially flat bottom surface, wherein the top surface has an interior region and an attachment region, the attachment region being arranged between the interior region and the edges of the core layer, and the attachment region completely surrounds the interior region;

a plurality of metal pads disposed on the top surface of the core layer, wherein at least one pad of the plurality of metal pads is positioned in the attachment region of the top surface of the core layer;

a plurality of solder pads disposed on the bottom surface of the core layer, the plurality of solder pads arranged to be within the edges of the core layer; and

one or more electrical vias located inside the core layer, wherein the vias electrically couple one or more of the plurality of metal pads on the top surface of the core layer to one or more of the plurality of solder pads on the bottom surface of the core layer, and wherein a via electrically couples the at least one metal pad positioned in the attachment region of the top surface of the core layer to one or more of the plurality of solder pads;

wherein the MEMS microphone die is physically coupled to the top surface of the core layer, and electrically coupled to at least one of the plurality of metal pads on the top surface of the core layer;

wherein the first, second, and third housing elements cooperate with each other to form a housing, wherein the edges of the first, second, and third housing elements create side surfaces substantially perpendicular to the bottom surface of the third housing element, wherein the housing has an internal acoustic chamber for the MEMS microphone die, and wherein the housing protects the MEMS microphone die from at least one of light, electromagnetic interference, and physical damage;

wherein a conductive material physically couples the attachment region of the bottom surface of the first housing element to the top surface of the second housing element to such that the interior region of the bottom surface of the first housing element and the aperture of the second housing element are aligned, and the metal layer of the first housing element is electrically coupled to the metal-covered aperture walls of the second housing element;

wherein a conductive material physically couples the bottom surface of the second housing element to the attachment region of the top surface of the third housing element such that the aperture of the second housing element and the interior region of the top surface of the third housing element are aligned, and the metal-covered aperture walls of the second housing element are electrically coupled to the at least one metal pad positioned in the attachment region of the third housing element;

wherein the interior region of the bottom surface of the first housing element, the aperture walls of the second housing element, and the interior region of the top surface of the third housing element, when attached, define the internal acoustic chamber that is a front volume for the MEMS microphone die, and acoustically couples the acoustic port to the MEMS microphone die; and

wherein electrical continuity exists between the metal layer of the first housing element, the metal-covered aperture walls of the second housing element, and one or more of the plurality of solder pads on the third housing element.

37. A surface mount MEMS microphone according to claim 36, further comprising at least one passive electrical element electrically coupled between one of the plurality of metal pads and one of the plurality of solder pads.

38. A surface mount MEMS microphone according to claim 37, wherein the at least one passive electrical element is disposed within the core layer of the third housing element and comprises a dielectric or resistive material that is different from the printed circuit board material of the core layer.

39. A surface mount MEMS microphone according to claim 38, wherein the at least one passive electrical element filters one or more of an input signal, an output signal, or input power.

40. A surface mount MEMS microphone according to claim 37, wherein the second housing element further comprises additional metal layers interposed between the multiple layers of printed circuit board material, and the metal-covered walls of the aperture electrically couples the additional metal layers to each other.

41. A surface mount MEMS microphone according to claim 36, wherein the housing further comprises a material that substantially blocks environmental contaminants from entering the acoustic chamber through the acoustic port.

42. A surface mount MEMS microphone according to claim 36, wherein the third housing element further comprises a cavity with an opening in the top surface of the core layer of the third housing element, and the MEMS microphone die is positioned over the opening in the top surface of the core layer such that the internal acoustic channel of the MEMS microphone die is acoustically coupled to the cavity.