Methods of manufacture of bottom port surface mount MEMS microphones

• US 9,150,409 B1
• Filed: 01/14/2014
• Issued: 10/06/2015
• Est. Priority Date: 11/28/2000
• Status: Expired due to Term

• 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:
  US14/155,054
• Time in Patent Office: 630 Days
• US Class Current: 1/1
• CPC Class Codes: B81B 2201/0257 Microphones or microspeakers
• CPC Class Codes: B81B 2207/097 Interconnects arranged on the substrate or the lid, and covered by the package seal
• 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 7/0061 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: B81C 1/00301 Connecting electric signal lines from the MEMS device with external electrical signal lines, e.g. through vias
• CPC Class Codes: B81C 1/00309 suitable for fluid transfer from the MEMS out of the package or vice versa, e.g. transfer of liquid, gas, sound
• CPC Class Codes: B81C 1/00333 Aspects relating to packaging of MEMS devices, not covered by groups B81C1/00269 - B81C1/00325
• CPC Class Codes: B81C 3/002 Aligning microparts
• 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 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 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 3/00 : Circuits for transducers , loudspeakers or microphones
• CPC Class Codes: Y10T 29/49005 : Acoustic transducer
• CPC Class Codes: Y10T 29/4908 : Acoustic transducer

Abstract

Methods for manufacturing multiple bottom port, surface mount microphones, each containing a micro-electro-mechanical system (MEMS) microphone die, are disclosed. Each surface mount microphone features a substrate with metal pads for surface mounting the package to a device'"'"'s printed circuit board and for making electrical connections between the microphone package and the device'"'"'s circuit board. The surface mount microphones are manufactured from a panel of unsingulated substrates, each substrate having an acoustic port, and each MEMS microphone die is substrate-mounted and acoustically coupled to its respective acoustic port. Individual covers are joined to the panel of unsingulated substrates, and each individual substrate and cover pair cooperates to form an acoustic chamber for its respective MEMS microphone die. The completed panel is singulated to form individual MEMS microphones.

Claims

1. A method for manufacturing a plurality of solder reflow surface mount microelectromechanical system (MEMS) microphones, the method comprising:

providing an unsingulated panel comprised of a plurality of individual rectangular substrates, each rectangular 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;

a second plurality of flat 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 bottom surface of the base layer;

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

an acoustic port disposed in the interior region of the base layer and passing completely through the base layer, wherein the acoustic port is disposed in a position offset from a centerpoint of the substrate, and wherein one of the second plurality of metal pads is a metal ring that completely surrounds the acoustic port in the base layer;

mounting a MEMS microphone die to the top surface of each individual substrate in the panel of unsingulated substrates, and electrically coupling the MEMS microphone die to at least one of the first plurality of metal pads on the top surface of its respective substrate, the MEMS microphone die being disposed directly over the acoustic port in the base layer of its respective substrate;

providing a plurality of single-piece rectangular covers, wherein each individual rectangular cover is formed from a solid material and has a top portion and a sidewall portion, the sidewall portion supporting the top portion and adjoining the top portion at a substantially perpendicular angle and having a predetermined height, an exterior surface, an interior surface, and an attachment surface;

attaching a single-piece rectangular cover to each individual substrate on the panel of unsingulated substrates, one cover to each individual substrate,

wherein the attachment surface of the sidewall portion of the cover is aligned with and attached to the attachment region of the top surface of its respective individual substrate, and

wherein the predetermined height and interior surface of the sidewall portion of the cover and the interior surface of the top portion of the cover, in cooperation with the interior region of the top surface of its respective individual substrate, forms a protective enclosure for the MEMS microphone die to reduce electromagnetic interference and to define an acoustic chamber for the MEMS microphone die; and

singulating the substrate panel into individual MEMS microphones.

2. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 1, wherein, for each individual substrate in the panel of unsingulated substrates, the method further comprises electrically coupling at least one passive electrical element between one of the first plurality of metal pads and one of the second plurality of metal pads.

3. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 2, wherein, for each individual substrate in the panel of unsingulated substrates, the at least one passive electrical element is disposed within the base layer of the individual substrate.

4. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 3, wherein, for each individual substrate in the panel of unsingulated substrates, the at least one passive electrical element comprises a dielectric or resistive material that is different from the non-conductive material in the base layer of the individual substrate.

5. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 2, wherein, for each individual substrate in the panel of unsingulated substrates, the at least one passive electrical element is configured to filter one or more of an input signal, an output signal, or input power.

6. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 1, wherein, for each individual substrate in the panel of unsingulated substrates, the individual substrate further comprises an acoustic material that substantially blocks environmental contaminants from entering the acoustic chamber through the acoustic port.

7. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 6, wherein, for each individual substrate in the panel of unsingulated substrates, the acoustic material is a film of polymeric material.

8. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 6, wherein, for each individual substrate in the panel of unsingulated substrates, the acoustic material is hydrophobic.

9. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 1, wherein, for each individual substrate in the panel of unsingulated substrates, the individual substrate further comprises a metal pad with an opening, wherein the opening surrounds the acoustic port in the base layer, and the metal pad is interposed between the MEMS microphone die and the top surface of the base layer.

10. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 1, wherein, for each individual substrate in the panel of unsingulated substrates, the individual substrate further comprises a metal pad with an opening, wherein the opening surrounds the acoustic port in the base layer, and the MEMS microphone die contacts the metal pad when mounted on the top surface of the base layer.

11. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 1, wherein, for each individual substrate in the panel of unsingulated substrates, the base layer comprises one or more layers of FR-4 printed circuit board material.

12. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 1, wherein, for each individual microphone, the enclosure protects the MEMS microphone die from at least one of light and physical damage.

13. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 1, wherein, for each individual microphone, a diaphragm of the MEMS microphone die defines a front volume and a back volume within the acoustic chamber, and the acoustic port disposed in the base layer of the substrate is acoustically coupled to the front volume.

14. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 13, wherein, for each individual microphone, the interface between the attachment surface of the sidewall portion of the cover and the attachment region of the top surface of the substrate is sealed to maintain acoustic pressure within the back volume.

15. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 1, wherein, for each individual microphone, the MEMS microphone die is a pressure-equalizing MEMS microphone die.

16. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 1, wherein, for each individual microphone, the acoustic port in the base layer is a first acoustic port and the top portion of the rectangular cover further comprises a second acoustic port.

17. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 16, wherein, after each individual rectangular cover is attached to its respective substrate in the unsingulated panel of substrates, its respective acoustic chamber acoustically couples the diaphragm of its respective MEMS microphone die to its respective second acoustic port.

18. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 16, wherein, for each individual rectangular cover, the second acoustic port further comprises a barrier that substantially blocks contaminants from entering the acoustic chamber through the second acoustic port.

19. A method for manufacturing a plurality of solder reflow surface mount microelectromechanical system (MEMS) microphones, the method comprising:

providing an unsingulated patent of rectangular base portions, each individual rectangular base 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;

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

an acoustic port located in the inner area of the base layer and passing completely through the base layer, wherein the acoustic port is disposed in a position offset from a centerpoint of the base portion, and wherein one of the second plurality of solder pads is a solder pad ring that completely surrounds the acoustic port in the base layer; and

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

mounting a MEMS microphone die to the upper surface of each individual base portion in the unsingulated panel of base portions, and electrically coupling each MEMS microphone die to at least one of the plurality of metal pads on the upper surface of the base layer of its respective base portion, wherein the MEMS microphone die being disposed directly over the acoustic port in the base layer of its respective base portion; and

providing a plurality of individual rectangular cover portions, each rectangular cover portion formed from a single piece of solid material, and having a top portion and a sidewall portion, the sidewall portion supporting the top portion and adjoining the top portion at a substantially perpendicular angle and having a predetermined height, an exterior surface, an interior surface, and a coupling surface;

coupling a rectangular cover portion to each individual base portion on the panel of unsingulated base portions, one cover portion to each individual base portion,

wherein the coupling surface of the sidewall portion of the cover portion is aligned with and mechanically attached to the coupling area of the base layer of its respective base portion;

wherein the predetermined height and interior surface of the sidewall portion of the cover position, and the interior surface of the top portion of the cover portion, in cooperation with the interior region of the upper surface of the base layer of respective base portion, forms a protective enclosure for the MEMS microphone die to define an acoustic chamber for the MEMS microphone die; and

wherein the overall length of the base portion and cover portion are substantially equal, and the overall width of the base portion and cover portion are substantially equal; and

singulating the panel of base portions into individual MEMS microphones.

20. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 19, wherein, for each individual base portion in the panel of unsingulated base portions, each individual base portion further comprises a metal pad with an opening, wherein the opening surrounds the acoustic port in the base layer of the base portion, and the metal pad is interposed between the MEMS microphone die and the upper surface of the base layer of the base portion.

21. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 19, wherein, for each individual MEMS microphone, the enclosure protects the MEMS microphone die from at least one of light, electromagnetic interference, and physical damage.

22. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 19, wherein, for each individual base portion in the panel of unsingulated base portions, the base layer of each individual base portion further comprises an acoustic material that substantially blocks contaminants from entering the acoustic chamber through the acoustic port.

23. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 22, wherein, for each individual base portion in the panel of unsingulated base portions, the acoustic material is a film of polymeric material.

24. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 22, wherein, for each individual base portion in the panel of unsingulated base portions, the acoustic material is hydrophobic.

25. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 19, wherein, for each individual MEMS microphone, a diaphragm of the MEMS microphone die defines a front volume and a back volume within the acoustic chamber, and the acoustic port disposed in the base layer of the base portion is acoustically coupled to the front volume;

and

wherein the interface between the coupling surface of the sidewall portion of the cover portion and the coupling area of the upper surface of the base layer of the base portion is sealed to maintain acoustic pressure within the back volume.

26. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 19, wherein, for each individual microphone, the acoustic port of the base layer is a first acoustic port and the top portion of the rectangular cover portion further comprises a second acoustic port.

27. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 19, wherein, for each individual base portion in the panel of unsingulated base portions, the at least one passive electrical element is disposed within the base layer of the base portion, wherein the at least one passive electrical element comprises a dielectric or resistive material that is different from the printed circuit board material in the base layer of the base portion.

28. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 27, wherein, for each individual base portion in the panel of unsingulated base portions, the at least one passive electrical element is configured to filter one or more of an input signal, an output signal, or input power.

29. A method for manufacturing a plurality of solder reflow surface mount microelectromechanical system (MEMS) microphones, the method comprising:

providing an unsingulated panel comprising a plurality of rectangular base elements, each individual base element 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;

a plurality of flat solder pads located on the bottom surface of the core layer, the plurality of solder pads arranged to be within the edges of the bottom surface of the core layer, wherein the solder pads are plated with at least one metal;

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;

an acoustic port located in the interior region of the core layer and passing completely through the core layer, wherein the acoustic port is disposed in a position offset from a centerpoint of the base element, and wherein one of the second plurality of solder pads is a solder pad ring that completely surrounds the acoustic port in the base element; and

at least one passive electrical element disposed within the core layer and electrically coupled between one of the plurality of metal pads and one 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, the internal acoustic channel of the MEMS microphone die being arranged directly over the acoustic port in the core layer;

providing a plurality of single-piece rectangular cover elements, each rectangular cover element formed from a solid material and having a top region and a wall region, the wall portion supporting the top portion and wall region adjoining the top region at a substantially perpendicular angle and having a predetermined height, an exterior surface, an interior surface, and an attachment surface;

coupling a rectangular cover element to each individual base element on the panel of unsingulated base elements, one cover element to each individual base element,

wherein the cover element is attached to the base element such that the attachment surface of the wall region of the cover element is aligned with and physically coupled to the attachment region of the top surface of the core layer of its respective base element, thereby forming a protective enclosure for the MEMS microphone die, and

wherein the interior of the protective enclosure is an acoustic chamber having a volume defined by the predetermined height of wall region of the cover element, and the width and length of the top region of the cover element; and

singulating the panel of base elements into individual MEMS microphones.

30. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 29, wherein, for each individual base element in the panel of unsingulated base elements, the at least one passive electrical element comprises a dielectric or resistive material that is different from the FR-4 printed circuit board material in the core layer of the base element.

31. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 30, wherein, for each individual base element in the panel of unsingulated base elements, the at least one passive electrical element is configured to filter one or more of an input signal, an output signal, or input power.

32. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 29, wherein, for each individual MEMS microphone, the enclosure protects the MEMS microphone die from at least one of light, electromagnetic interference, and physical damage.

33. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 29, wherein, for each individual base element in the panel of unsingulated base elements, the core layer of the base element further comprises an acoustic material that substantially blocks contaminants from entering the acoustic chamber through the acoustic port.

34. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 33, wherein, for each individual base element in the panel of unsingulated base elements, the acoustic material is a film of polymeric material.

35. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 33, wherein, for each individual base element in the panel of unsingulated base elements, the acoustic material is hydrophobic.

36. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 29, wherein, for each individual MEMS microphone, a diaphragm of the MEMS microphone die defines a front volume and a back volume within the acoustic chamber, and the acoustic port disposed in the core layer of the base element is acoustically coupled to the front volume;

and

wherein the interface between the attachment surface of the wall region of the cover element and the attachment area of the top surface of the core layer of the base element is sealed to maintain acoustic pressure within the back volume.

37. A method for manufacturing a plurality of solder reflow surface mount microelectromechanical system (MEMS) microphones, the method comprising:

providing a plurality of a pressure-equalizing MEMS microphone die, each having an internal acoustic channel;

providing an unsingulated panel comprising a plurality of first housing elements each having a rectangular shape, the first housing elements further comprising;

a core layer comprised of multiple layers of FR-4 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 die mount region and an attachment region, the attachment region being arranged between the die mount region and the edges of the core layer, and the attachment region completely surrounds the die mount region;

a plurality of metal pads disposed on the top surface of the core layer, wherein the metal pads are plated with at least one metal;

a plurality of flat solder pads disposed on the bottom surface of the core layer, the plurality of solder pads arranged to be within a perimeter of the bottom surface of the core layer, wherein the solder pads are plated with at least one metal;

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;

an acoustic port located in the die mount region of the core layer and passing completely through the core layer, wherein the acoustic port is disposed in a position offset from a centerpoint of the first housing element, and wherein one of the plurality of solder pads is a solder pad ring that completely surrounds the acoustic port in the core layer; and

at least one passive electrical element disposed within the core layer and electrically coupled between one of the plurality of metal pads and one of the plurality of solder pads, wherein the at least one passive electrical element comprises a dielectric or resistive material that is different from the printed circuit board material in the core layer;

providing a plurality of second housing elements each having a rectangular shape, each second housing element formed from a single piece of solid material, and having a top region and a wall region, the wall portion supporting the top portion and wall region adjoining the top region at a substantially perpendicular angle and having a predetermined height, an exterior surface, an interior surface, and an attachment surface;

coupling a MEMS microphone die to each first housing element in the unsingulated panel of first housing elements, wherein each MEMS microphone die is disposed in the die mount region of the core layer of its respective first housing element, and electrically coupled to one or more of the metal pads on the top surface of the core layer of its respective first housing element, the internal acoustic channel of the MEMS microphone die being arranged directly over the acoustic port in the core layer in its respective first housing element;

forming a protective housing for each MEMS microphone die mounted on a first housing element in the unsingulated panel of first housing elements by coupling a second housing element to each first housing element in the unsingulated panel of first housing elements,

wherein the attachment surface of the wall region of the second housing element is aligned with and physically coupled to the attachment region of the top surface of the core layer of the first housing element, thereby forming a protective enclosure for the MEMS microphone die, and

wherein the interior of the protective enclosure is an acoustic chamber having a volume defined by the predetermined height of wall region of the second housing element, and the width and length of the top region of the second housing element; and

singulating the panel of first housing elements into individual MEMS microphones.

38. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 37, wherein, for each individual MEMS microphone, the enclosure protects the MEMS microphone die from at least one of light, electromagnetic interference, and physical damage.

39. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 37, wherein, for each first housing element in the unsingulated panel of first housing elements, the core layer of the first housing element further comprises an acoustic material that substantially blocks contaminants from entering the acoustic chamber through the acoustic port.

40. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 39, wherein, for each first housing element in the unsingulated panel of first housing elements, the acoustic material is a film of polymeric material.

41. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 39, wherein, for each first housing element in the unsingulated panel of first housing elements, the acoustic material is hydrophobic.

42. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 37, wherein, for each individual microphone, the acoustic port in the core layer of the first housing element is a first acoustic port and the top portion of the second housing element further comprises a second acoustic port.

43. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 37, wherein, for each first housing element in the unsingulated panel of first housing elements, the at least one passive electrical element is configured to filter one or more of an input signal, an output signal, or input power.