CN111225331A

CN111225331A - MEMS microphone

Info

Publication number: CN111225331A
Application number: CN202010183496.6A
Authority: CN
Inventors: 柏杨; 饶成辉; 洪亭亭
Original assignee: AAC Acoustic Technologies Shenzhen Co Ltd
Current assignee: AAC Technologies Holdings Shenzhen Co Ltd
Priority date: 2020-03-16
Filing date: 2020-03-16
Publication date: 2020-06-02
Anticipated expiration: 2040-03-16
Also published as: CN111225331B; WO2021184403A1

Abstract

The invention provides a MEMS microphone. The MEMS microphone comprises a shell with a packaging cavity, an MEMS chip and an ASIC chip, and further comprises a conductive dustproof net covering the acoustic through hole, a first grounding bonding pad fixedly connected with the conductive dustproof net, a first grounding bonding pad arranged on the outer surface of the substrate and electrically connected with a grounding end of an external circuit, and a metal conductive piece electrically connected with the first metal lead, the first grounding bonding pad and the first grounding bonding pad. The first metal lead guides static electricity in the ASIC chip to a ground layer of an external circuit of the terminal equipment through the first grounding welding sheet or the conductive dustproof net, and the first grounding welding sheet guides static electricity in the substrate to the ground layer of the external circuit of the terminal equipment through the first grounding welding sheet or the conductive dustproof net, so that the ASIC chip and a buried resistance layer in the substrate can be prevented from being broken down by ESD current to a great extent to cause open circuit or short circuit.

Description

MEMS microphone

[ technical field ] A method for producing a semiconductor device

The invention relates to the technical field of electroacoustic conversion, in particular to an MEMS microphone.

[ background of the invention ]

The MEMS microphone is an electric transducer manufactured based on MEMS (micro electro mechanical system) technology, and has the characteristics of small volume, good frequency response characteristics, low noise, and the like. With the development of miniaturization and thinning of electronic devices, MEMS microphones are increasingly widely used in electronic devices.

Mobile terminals such as mobile phones and tablet phones have increasingly powerful functions, and as circuit boards are made smaller and smaller, the integration level is higher and higher, and MEMS microphones in mobile phones are more and more easily damaged by static electricity. ESD (Electro-Static discharge) means "electrostatic discharge". ESD has been developed in the middle of the 20 th century to study the generation and damage of static electricity and the protection of static electricity. Therefore, it is customary internationally to refer to the equipment for electrostatic protection collectively as ESD, herein termed electrostatic impeders. Under the ESD electrostatic discharge scene, the embedded resistance layers in the ASIC chip and the packaging substrate are easy to be broken down to cause short circuit or open circuit, and the heat generated by ESD current is easy to burn out materials, even the MEMS chip is affected, so that the failure of the MEMS microphone is caused.

[ summary of the invention ]

The invention aims to provide an MEMS microphone, aiming at solving the problem of open circuit or short circuit caused by breakdown of an ASIC chip and a buried resistance layer in a substrate by electrostatic discharge current.

The technical scheme of the invention is as follows:

the invention discloses a first MEMS microphone, which comprises a shell with a packaging cavity, and an MEMS chip and an ASIC chip which are arranged in the packaging cavity, the shell comprises a substrate for mounting the MEMS chip and the ASIC chip and a shell which forms the packaging cavity by enclosing with the substrate, the microphone further includes a first metal lead electrically connecting the ASIC chip and the substrate and a second metal lead electrically connecting the ASIC chip and the MEMS chip, the MEMS microphone is characterized in that an acoustic through hole is formed in the substrate, the MEMS microphone further comprises a conductive dustproof net covering the acoustic through hole, a first grounding bonding pad fixedly connected with the conductive dustproof net, a first grounding bonding pad arranged on the outer surface of the substrate and electrically connected with the grounding end of an external circuit, and a metal conductive piece electrically connected with the first metal lead, the first grounding bonding pad and the first grounding bonding pad.

Preferably, the conductive dustproof net is arranged on the surface of the substrate close to the MEMS chip or far away from the surface of the MEMS chip.

Preferably, the conductive dustproof net is arranged inside the substrate.

Preferably, the metal conductive member includes a first metal conductive member penetrating through the substrate and having one end electrically connected to the first metal lead and the other end electrically connected to the first ground pad, and a second metal conductive member having one end electrically connected to the first metal conductive member and the other end electrically connected to the first ground pad.

Preferably, the MEMS microphone further includes a conductive adhesive for electrically connecting the conductive dust screen and the first ground pad.

Preferably, the first ground pad includes not less than two.

Preferably, the substrate is a circuit board.

Preferably, the metal conductive member is a metalized through hole or a conductive wire.

The invention discloses a second MEMS microphone, which comprises a shell with a packaging cavity, and an MEMS chip and an ASIC chip which are arranged in the packaging cavity, the shell comprises a substrate for mounting the MEMS chip and the ASIC chip and a shell which forms the packaging cavity by enclosing with the substrate, the microphone further includes a first metal lead electrically connecting the ASIC chip and the substrate and a second metal lead electrically connecting the ASIC chip and the MEMS chip, the MEMS microphone is characterized in that an acoustic through hole is formed in the substrate, the MEMS microphone further comprises an acoustic through hole, a conductive dustproof net, a second grounding pad and an electric connection piece, wherein the acoustic through hole is formed in the substrate and is arranged far away from the surface of the MEMS chip, the second grounding pad is electrically connected with the conductive dustproof net, the first metal lead is electrically connected with the metal conductive piece of the second grounding pad, and the conductive dustproof net is electrically connected with a grounding end of an external circuit.

Preferably, the substrate is further provided with a second grounding bonding pad, the metal conductive member includes a third metal conductive member penetrating through the substrate and having one end electrically connected to the first metal lead and the other end electrically connected to the second grounding bonding pad, and a fourth metal conductive member having one end electrically connected to the third metal conductive member and the other end electrically connected to the second grounding bonding pad.

The invention has the beneficial effects that:

according to the first MEMS microphone, the conductive dustproof net is covered on the acoustic through hole, so that the dustproof function of the microphone is improved; the arrangement of the metal conductive piece realizes the conduction of the first metal lead, the first grounding welding pad and the first grounding welding piece, the ASIC chip is electrically connected with the first metal lead, the first metal lead guides static electricity in the ASIC chip into a stratum of an external circuit of the terminal equipment through the first grounding welding piece or the conductive dustproof net, the conductive dustproof net is electrically connected with the first grounding welding pad, the first grounding welding pad guides the static electricity in the substrate into the stratum of the external circuit of the terminal equipment through the first grounding welding piece or the conductive dustproof net, and the open circuit or the short circuit caused by the breakdown of ESD current on the ASIC chip and a buried resistance layer in the substrate can be avoided to a great extent; and the heat generated by the electrostatic discharge current in the substrate can be transferred to the conductive dustproof net, so that the heat dissipation effect of the substrate is improved, and the reliability of the MEMS microphone is also improved.

According to the second MEMS microphone, the conductive dustproof net is arranged on the surface, far away from the MEMS chip, of the substrate, so that the conductive dustproof net can be directly contacted with the ground layer of an external circuit of the terminal equipment, the metal conductive piece realizes conduction between the second grounding pad and the first metal lead, the ASIC chip is electrically connected with the first metal lead, the conductive dustproof net is electrically connected with the second grounding pad, static electricity in the ASIC chip sequentially passes through the first metal lead, the metal conductive piece and the second grounding pad and is led into the ground layer of the external circuit of the terminal equipment through the conductive dustproof net, and an open circuit or a short circuit caused by breakdown of ESD current of the ASIC chip and a buried resistance layer in the substrate can be avoided to a great extent; and the heat generated by the electrostatic discharge current in the substrate can be transferred to the conductive dustproof net, so that the heat dissipation effect of the substrate is improved, and the reliability of the MEMS microphone is also improved.

[ description of the drawings ]

FIG. 1 is a schematic cross-sectional view of a first embodiment of a MEMS microphone of the present invention;

FIG. 2 is an enlarged view of a portion of FIG. 1 taken within circle A;

FIG. 3 is a schematic cross-sectional view of a second embodiment of a MEMS microphone of the present invention;

FIG. 4 is an enlarged view of a portion of FIG. 3 taken within circle B;

FIG. 5 is a schematic cross-sectional view of a third embodiment of a MEMS microphone of the invention;

FIG. 6 is an enlarged view of a portion of FIG. 5 taken within circle C;

fig. 7 is a schematic cross-sectional view of a MEMS microphone according to a fourth embodiment of the invention.

[ detailed description ] embodiments

The invention is further described with reference to the following figures and embodiments.

First embodiment

Referring to fig. 1-2, a MEMS microphone of the present embodiment includes a housing 10 having a package cavity 110, and a MEMS chip 13 and an ASIC chip 14 mounted in the package cavity 110, the housing 10 includes a substrate 11 for mounting the MEMS chip 13 and the ASIC chip 14, and a housing 12 enclosing the substrate 11 to form the package cavity 110, the microphone further includes a first metal lead 17 electrically connecting the ASIC chip 14 and the substrate 11, and a second metal lead 18 electrically connecting the ASIC chip 14 and the MEMS chip 13, the substrate 11 is provided with an acoustic through hole 111, the MEMS microphone further includes a conductive dust-proof mesh 15 covering one end of the acoustic through hole 111 close to the MEMS chip 13, a first ground pad 112 fixedly connected to the conductive dust-proof mesh 15, a first ground pad 116 disposed on an outer surface of the substrate and electrically connected to a ground terminal of an external circuit, and a second metal lead 17, First ground pad 112, first ground pad 116 electrically connected to metal conductive member 19.

The conductive dust screen 15 in the present embodiment is fixed to the inner surface of the substrate 11. Specifically, the inner surface of the substrate 11 is provided with a first mounting groove 113 for accommodating the conductive dust screen 15, and the conductive dust screen 15 is disposed at one end of the substrate 11 close to the MEMS chip 13. The MEMS chip 13 has a back cavity, the acoustic via 111 communicates with the back cavity, one surface of the conductive dust-proof mesh 15 in this embodiment is opposite to the back cavity of the MEMS chip 13, and the other surface of the conductive dust-proof mesh 15 communicates with the acoustic via 111, so that both surfaces of the conductive dust-proof mesh 15 can radiate heat well in the heat dissipation process.

The MEMS microphone of the present embodiment improves the dust-proof function of the microphone by covering the conductive dust-proof mesh 15 on the acoustic through hole 111; the arrangement of the metal conductive member 19 can realize the conduction of the first metal lead 17, the first grounding pad 112 and the first grounding welding sheet 116, the ASIC chip 14 is electrically connected with the first metal lead 17, the first metal lead 17 guides the static electricity in the ASIC chip 14 to be led into the ground layer of the external circuit of the terminal equipment from the first grounding welding sheet 116 through the guide of the metal conductive member 19, the first grounding pad 112 guides the static electricity in the substrate 11 to be led into the ground layer of the external circuit of the terminal equipment from the first grounding welding sheet 116 through the guide of the metal conductive member 19, and the open circuit or the short circuit caused by the breakdown of the ESD current of the embedded resistance layers in the ASIC chip 14 and the substrate 11 can be avoided to a great extent; and the heat generated by the electrostatic discharge current in the substrate 11 can be transferred to the conductive dustproof net 15, so that the heat dissipation effect of the substrate 11 is improved, and the reliability of the MEMS microphone is also improved.

In the present embodiment, the metal conductor 19 includes a first metal conductor 191 penetrating the substrate 11 and electrically connected to the first metal lead 17 at one end and the first ground pad 116 at the other end, and a second metal conductor 192 electrically connected to the first metal conductor 191 at one end and the first ground pad 112 at the other end. In the scheme, the first metal conductive member 191 and the second metal conductive member 192 are perpendicular to each other, so that the consumption of consumables is reduced to the maximum extent, and meanwhile, the grounding of the ASIC chip 14 and the grounding of the conductive dust screen 15 are realized.

In this embodiment, the MEMS microphone further includes a conductive paste 16 that electrically connects the conductive dust-proof mesh 15 and the first ground pad 112. The conductive dust screen 15 and the first ground pad 112 are electrically connected by a conductive paste 16. The conductive adhesive 16 can not only realize the fixed connection between the conductive dustproof net 15 and the pad, but also connect the conductive path between the conductive dustproof net 15 and the pad. It should be noted that, the first grounding tab 116 and the first grounding pad 112 are both fixedly connected to the substrate 11, and in the connection process between the first grounding tab 116 and the first conductive metal member 191, since the first conductive metal member 191 is also fixed in the substrate 11, there is no need to add the conductive adhesive 16 therebetween.

In the present embodiment, the first ground pads 112 include not less than two. The two first grounding bonding pads 112 are symmetrically arranged at the bottom of the first mounting groove 113, and the two first grounding bonding pads 112 are respectively fixedly connected with the two ends of the conductive dustproof net 15 through the conductive adhesive 16, so that the fixing stability of the conductive dustproof net 15 can be ensured, and meanwhile, the two first grounding bonding pads 112 can release static electricity to the conductive dustproof net 15 simultaneously, and the static electricity can be released more uniformly and safely. Of course, the present invention is not limited to the use of two first ground pads 112, and the number of pads may be increased or decreased according to specific needs.

In the present embodiment, the substrate 11 is a wiring board. The ASIC chip 14 and the MEMS chip 13 are electrically connected to the wiring board through first metal leads 17.

In this embodiment, the metal conductive element 19 is a metalized through hole or a conductive wire, and the metal conductive element 19 mainly serves to conduct the first metal lead 17 and the first ground pad 112 to the first ground pad 116 respectively so as to achieve electrostatic ground discharge, and mainly can achieve a conductive function, and the specific structure thereof is not limited.

Second embodiment

Referring to fig. 3-4, the difference between the first embodiment and the second embodiment is that the conductive dust-proof screen 15 of the present embodiment is fixed inside the substrate 11. Specifically, a second mounting groove 114 for accommodating the conductive dust screen 15 is disposed between the inner surface and the outer surface of the substrate 11, and the conductive dust screen 15 covers the middle position of the hole of the acoustic through hole 111.

The MEMS microphone of the present embodiment improves the dust-proof function of the microphone by covering the conductive dust-proof mesh 15 on the acoustic through hole 111; the arrangement of the metal conductive member 19 can realize the conduction of the first metal lead led out from the ASIC chip 14, the first grounding pad 112 and the first grounding tab 116, the ASIC chip 14 is electrically connected with the first metal lead 17, the first metal lead 17 guides the static electricity in the ASIC chip 14 to be led into the ground layer of the external circuit of the terminal device from the first grounding tab 116 through the guide of the metal conductive member 19, the first grounding pad 112 guides the static electricity in the substrate 11 through the guide of the metal conductive member 19, and the open circuit or the short circuit caused by the breakdown of the embedded resistance layers in the ASIC chip 14 and the substrate 11 by the ESD current can be avoided to a great extent; and the heat generated by the electrostatic discharge current in the substrate 11 can be transferred to the conductive dustproof net 15, so that the heat dissipation effect of the substrate 11 is improved, and the reliability of the MEMS microphone is also improved.

In the present embodiment, the second mounting groove 114 is opened inside the substrate 11, and the surface form of the substrate 11 is not affected at all, and the conductive dust screen 15 is further hidden. Meanwhile, the conductive dust screen 15 is preferably disposed at an intermediate position between the inner surface and the outer surface of the substrate 11, so that the discharge of static electricity is more sufficient and uniform, and the conductive dust screen 15 is more fully utilized.

Third embodiment

Referring to fig. 5-6, different from the first and second embodiments, the conductive dust-proof mesh 15 is disposed on the surface of the substrate 11 away from the MEMS chip 13, a second ground pad 117 electrically connected to the conductive dust-proof mesh 15 and a metal conductive member 19 electrically connected to the first metal lead 17 and the second ground pad 117 are disposed on the substrate 11, and the conductive dust-proof mesh 15 is electrically connected to a ground terminal of an external circuit.

It should be noted that the outer surface of the substrate 11 is provided with a first mounting groove 113 for accommodating the conductive dust-proof net 15, and the conductive dust-proof net 15 covers an end of the acoustic through hole 111 away from the MEMS chip 13. The conductive dustproof net 15 is arranged on the outer surface of the substrate 11, the outer surface of the conductive dustproof net 15 and the outer surface of the substrate 11 are located on the same horizontal plane, so that the conductive dustproof net 15 does not occupy redundant space, physical contact between the conductive dustproof net 15 and the ground layer of an external circuit of a terminal device can be directly achieved, the grounding area of electrostatic discharge is increased, and electrostatic discharge and heat dissipation can be better performed.

Compared with the prior art, in the MEMS microphone of the present embodiment, the conductive dust-proof net 15 is disposed on the surface of the substrate 11 away from the MEMS chip 13, so that the conductive dust-proof net 15 can directly contact with the ground layer of the external circuit of the terminal device, the metal conductive member 19 realizes conduction between the second ground pad 117 and the first metal lead 17, the ASIC chip 14 is electrically connected to the first metal lead 17, the conductive dust-proof net 15 is electrically connected to the second ground pad 117, static electricity in the ASIC chip 14 sequentially passes through the first metal lead 17, the metal conductive member 19 and the second ground pad 117 and is introduced into the ground layer of the external circuit of the terminal device through the conductive dust-proof net 15, and thus open circuit or short circuit caused by breakdown of ESD current in the ASIC chip 14 and the substrate 11 can be largely avoided; and the heat generated by the electrostatic discharge current in the substrate 11 can be transferred to the conductive dustproof net 15, so that the heat dissipation effect of the substrate 11 is improved, and the reliability of the MEMS microphone is also improved.

The conductive dust screen 15 of the present embodiment is set to be in a direct grounding position, which can directly discharge static electricity, and compared with the first embodiment and the second embodiment, the structure is simpler and the effect is more significant without adding the first grounding tab 116.

Fourth embodiment

Referring to fig. 7, different from the third embodiment, a second grounding tab 118 is further disposed on the substrate 11, and the metal conductive member 19 includes a third metal conductive member 193 penetrating through the substrate 11 and having two ends respectively electrically connected to the first metal lead 17 and the second grounding tab 118, and a fourth metal conductive member 194 having one end electrically connected to the third metal conductive member 193 and the other end electrically connected to the second grounding pad 117. The provision of the second ground pad 118 may increase the stability and efficiency of electrostatic discharge.

The above are only embodiments of the present invention, and it should be noted that, for those skilled in the art, modifications can be made without departing from the inventive concept of the present invention, but these are all within the scope of the present invention.

Claims

1. A MEMS microphone comprises a shell with a packaging cavity, and a MEMS chip and an ASIC chip which are arranged in the packaging cavity, the shell comprises a substrate for mounting the MEMS chip and the ASIC chip and a shell which forms the packaging cavity by enclosing with the substrate, the microphone further includes a first metal lead electrically connecting the ASIC chip and the substrate and a second metal lead electrically connecting the ASIC chip and the MEMS chip, the MEMS microphone is characterized in that an acoustic through hole is formed in the substrate, and the MEMS microphone further comprises a conductive dustproof net covering the acoustic through hole, a first grounding bonding pad fixedly connected with the conductive dustproof net, a first grounding bonding pad arranged on the outer surface of the substrate and electrically connected with the grounding end of an external circuit, and a metal conductive piece electrically connected with the first metal lead, the first grounding bonding pad and the first grounding bonding pad.

2. The MEMS microphone of claim 1, wherein the dust screen is disposed on a surface of the substrate close to the MEMS chip or remote from the MEMS chip.

3. The MEMS microphone of claim 1, wherein the conductive dust screen is disposed inside the substrate.

4. The MEMS microphone of claim 1, wherein the metal conductive members comprise a first metal conductive member penetrating the substrate and electrically connected to the first metal lead at one end and the first ground pad at the other end, and a second metal conductive member electrically connected to the first metal conductive member at one end and the first ground pad at the other end.

5. The MEMS microphone of claim 1, further comprising a conductive glue that electrically connects the conductive dust screen to the first ground pad.

6. The MEMS microphone of claim 1, wherein the first ground pad comprises no less than two.

7. The MEMS microphone of claim 1, wherein the substrate is a circuit board.

8. The MEMS microphone of claim 1, wherein the metal conductive member is a metalized via or a conductive wire.

9. A MEMS microphone is characterized by comprising a shell with a packaging cavity, and a MEMS chip and an ASIC chip which are arranged in the packaging cavity, the shell comprises a substrate for mounting the MEMS chip and the ASIC chip and a shell which forms the packaging cavity by enclosing with the substrate, the microphone further includes a first metal lead electrically connecting the ASIC chip and the substrate and a second metal lead electrically connecting the ASIC chip and the MEMS chip, the MEMS microphone is characterized in that an acoustic through hole is formed in the substrate, the MEMS microphone further comprises an acoustic through hole, a conductive dustproof net, a second grounding pad and an electric connection piece, wherein the acoustic through hole is formed in the substrate and is arranged far away from the surface of the MEMS chip, the second grounding pad is electrically connected with the conductive dustproof net, the first metal lead is electrically connected with the metal conductive piece of the second grounding pad, and the conductive dustproof net is electrically connected with a grounding end of an external circuit.

10. The MEMS microphone of claim 9, wherein a second grounding pad is further disposed on the substrate, and the metal conductive member comprises a third metal conductive member penetrating through the substrate and electrically connected to the first metal lead at one end and the second grounding pad at the other end, and a fourth metal conductive member electrically connected to the third metal conductive member at one end and the second grounding pad at the other end.