Methods of manufacture of bottom port surface mount MEMS microphones

• US 9,133,020 B1
• Filed: 02/18/2014
• Issued: 09/15/2015
• 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:
  US14/182,960
• Time in Patent Office: 574 Days
• US Class Current: 1/1
• 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
• 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

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 printed 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 including a plurality of individual rectangular substrates, each rectangular substrate including;

a rigid base layer including multiple sub-layers of non-conductive material, each sub-layer having a predetermined coefficient of thermal expansion, 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 flat metal pads disposed on the top surface of the base layer and defined by a first solder mask;

a second plurality of flat metal pads disposed on the bottom surface of the base layer and defined by a second solder mask layer, the second plurality of metal pads arranged to be within a perimeter 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 and has an inner diameter that is greater than the diameter of the acoustic port;

mounting a MEMS microphone die to the top surface of a plurality of the individual substrates of the panel of unsingulated substrates, and electrically coupling the mounted 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 solid single-piece rectangular covers, wherein each rectangular cover has a predetermined shape and includes a top portion, and a substantially vertical and continuous sidewall portion that adjoins the top portion at an angle and that completely surrounds and supports the top portion, the sidewall portion having a predetermined height, an exterior sidewall surface, an interior sidewall surface, and an attachment surface;

attaching one rectangular cover to each substrate of the panel of unsingulated substrates having a MEMS microphone die mounted thereon,

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

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

singulating the substrate panel into discrete surface mount MEMS microphones.

2. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 1, wherein 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 for one or more of the substrates of the panel of unsingulated substrates.

3. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 2, wherein, for each individual substrate of the panel of unsingulated substrates that includes at least one passive electrical element, 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 of the panel of unsingulated substrates that includes at least one passive electrical element, the at least one passive electrical element includes a dielectric or resistive material that is different from the sub-layers of 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 3, wherein, for each individual substrate of the panel of unsingulated substrates that includes at least one passive electrical element, 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 one or more of the substrates of the panel of unsingulated substrates, the substrate further includes an acoustic material that substantially blocks contaminants from passing through the acoustic port.

7. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 6, wherein, for each substrate of the panel of unsingulated substrates that includes the acoustic material to block contaminants, the 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 substrate of the panel of unsingulated substrates that includes the acoustic material to block contaminants, the material is hydrophobic.

9. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 1, wherein, for one or more of the substrates of the panel of unsingulated substrates, the first plurality of metal pads further includes 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 one or more of the substrates of the panel of unsingulated substrates, the first plurality of metal pads further includes 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.

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

12. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 1, wherein the enclosure of the surface mount MEMS microphone protects its respective 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 a diaphragm of the MEMS microphone die of the surface mount MEMS microphone defines a front volume and a back volume within its respective acoustic chamber, and the acoustic port disposed in the base layer of its respective 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 the surface mount MEMS 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 the MEMS microphone die is a pressure-equalizing MEMS microphone die.

16. 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 including;

a rigid base layer including multiple sub-layers of printed circuit board material, each sub-layer having a predetermined coefficient of thermal expansion, 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 flat metal pads located on the upper surface of the base layer and defined by a first solder mask;

a plurality of flat solder pads located on the lower surface of the base layer and defined by a second solder mask layer, the plurality of solder pads arranged to be within a perimeter 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 plurality of solder pads is a solder pad ring that completely surrounds the acoustic port in the base layer and has an inner diameter that is greater than the diameter of the acoustic port; 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, wherein the at least one passive electrical element includes a dielectric or resistive material that is different from the sub-layers of printed circuit board material;

mounting a MEMS microphone die to the upper surface of a plurality of the base portions in the unsingulated panel of base portions, and electrically coupling the mounted 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 solid rectangular cover portions, each rectangular cover portion formed from a single piece of material and having a predetermined shape, each rectangular cover portion having a top portion and a substantially vertical and continuous sidewall portion that adjoins the top portion at an angle and that completely surrounds and supports the top portion, the sidewall portion having a predetermined height, an exterior surface, an interior surface, and a coupling surface;

coupling one rectangular cover portion to each base portion of the panel of unsingulated base portions having a MEMS microphone die mounted thereon,

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

wherein the predetermined height of the sidewall portion of the cover portion, the interior surface of the sidewall portion of the cover portion, and the interior surface of the top portion of the cover portion being coupled, in cooperation with the interior region of the upper surface of the base layer of its respective base portion, defines an acoustic chamber for the MEMS microphone die and provides a protective enclosure for its respective MEMS microphone die; and

wherein the overall length of base portions having a MEMS microphone die mounted thereon and their respective cover portions are substantially equal, and the overall width of the base portions having a MEMS microphone die mounted thereon and their respective cover portions are substantially equal; and

singulating the panel of base portions into discrete surface mount MEMS microphones.

17. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 16, wherein, for one or more of the base portions of the panel of unsingulated base portions, the plurality of metal pads further includes 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.

18. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 16, wherein the enclosure of the surface mount MEMS microphone protects its respective MEMS microphone die from at least one of light, electromagnetic interference, and physical damage.

19. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 16, wherein, for one or more of the base portions of the panel of unsingulated base portions, the base layer of the base portion further includes an acoustic material that substantially blocks contaminants from passing through the acoustic port.

20. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 19, wherein, for one or more of the base portions of the panel of unsingulated base portions, the acoustic material is a film of polymeric material.

21. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 19, wherein, for one or more of the base portions of the panel of unsingulated base portions, the acoustic material is hydrophobic.

22. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 16, wherein a diaphragm of the MEMS microphone die of the surface mount MEMS microphone defines a front volume and a back volume within its respective acoustic chamber, and the acoustic port disposed in the base layer of its respective 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.

23. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 16, wherein, for each base portion that includes at least one passive electrical element, the at least one passive electrical element is configured to filter one or more of an input signal, an output signal, or input power.

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

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

a rigid core layer including multiple sub-layers of FR-4 printed circuit board material, each sub-layer having a predetermined coefficient of thermal expansion, 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 flat metal pads located on the top surface of the core layer and defined by a first solder mask;

a plurality of flat solder pads located on the bottom surface of the core layer and defined by a second solder mask, 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;

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 plurality of solder pads is a solder pad ring that completely surrounds the acoustic port in the base element and has an inner diameter that is greater than the diameter of the acoustic port; 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 includes a dielectric or resistive material that is different from the sub-layers of printed circuit board material; 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 solid single-piece rectangular cover elements having a predetermined shape, each rectangular cover element having a top region and a continuous wall region, the continuous wall region supporting the top region and 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 base element of the panel of unsingulated base elements, one cover element to each individual base element,

wherein each cover element is coupled to its respective 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 its respective MEMS microphone die;

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;

wherein a diaphragm of the MEMS microphone die defines a front volume and a back volume within its respective 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 continuous wall region of 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; and

singulating the panel of base elements into discrete surface mount MEMS microphones.

25. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 24, wherein, for each base element that includes at least one passive electrical element, the at least one passive electrical element is configured to filter one or more of an input signal, an output signal, or input power.

26. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 24, wherein the enclosure of the surface mount MEMS microphone protects its respective MEMS microphone die from at least one of light, electromagnetic interference, and physical damage.

27. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 24, wherein, for one or more of the individual base elements of the panel of unsingulated base elements, the core layer of the base element further includes an acoustic material that substantially blocks contaminants from passing through the acoustic port.

28. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 27, wherein, for one or more of the individual base elements of the panel of unsingulated base elements, the acoustic material is a film of polymeric material.

29. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 27, wherein, for one or more of the individual base elements of the panel of unsingulated base elements, the acoustic material is hydrophobic.

30. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 25, wherein, one or more of the individual base elements of the panel of unsingulated base elements, the plurality of metal pads further includes a metal pad with an opening, wherein the opening surrounds the acoustic port in the core layer, and the metal pad is interposed between the MEMS microphone die and the top surface of the core layer.

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

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

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

a rigid core layer including multiple layers of FR-4 printed circuit board material, each layer of FR-4 material having a predetermined coefficient of thermal expansion, 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 flat metal pads disposed on the top surface of the core layer and defined by a first solder mask 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 and defined by a second solder mask 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 includes 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 substantially flat top region and a continuous wall region, the continuous wall region supporting the top region and adjoining the top region at a substantially perpendicular angle, the continuous wall region having a predetermined height, an exterior surface, an interior surface, and an attachment surface;

coupling one of the plurality of MEMS microphone die to one or more of the first housing elements 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;

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

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 discrete surface mount MEMS microphones.

32. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 31, wherein the enclosure of each surface mount MEMS microphone protects its respective 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 31, wherein, for one or more of the first housing elements in the unsingulated panel of first housing elements, the core layer of the first housing element further includes an acoustic material that substantially blocks contaminants from passing through the acoustic port.

34. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 33, wherein, for one or more of the first housing elements in the unsingulated panel of first housing 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 one or more of the first housing elements in the unsingulated panel of first housing elements, the acoustic material is hydrophobic.

36. A method for manufacturing a plurality of surface mount MEMS microphones according to claim 31, wherein, for each first housing element that includes at least one passive electrical element, the at least one passive electrical element is configured to filter one or more of an input signal, an output signal, or input power.