CN210781346U - Novel single-directional MEMS microphone - Google Patents

Abstract

The utility model relates to the field of microphones, in particular to a novel single-direction MEMS microphone, which comprises a bonding pad PCB and an MEMS microphone, the pad PCB is provided with a pad first sound hole and a pad second sound hole which penetrate through the pad PCB, the positions of a first sound hole and a second sound hole of the bonding pad on the lower end surface of the bonding pad PCB are both fixed with tuning cloths, a lower sound guide groove PCB is fixed on the upper end surface of the welding disc PCB, a lower first sound hole penetrating through the lower sound guide groove PCB is arranged on the lower sound guide groove PCB corresponding to the first sound hole of the welding disc, a second sound guide groove is arranged on the lower sound guide groove PCB and at the position of the second sound hole of the bonding pad, a lower second sound hole connected with the tail end of the second sound guide groove is arranged at the middle position on the lower sound guide groove PCB, an upper sound guide groove PCB is fixed on the upper end face of the lower sound guide groove PCB, and a cavity for accommodating the MEMS microphone is arranged in the middle of the upper sound guide groove PCB. The device can effectively pick up the sound in front of the opposite side of the first sound hole of the bonding pad.

Description

Novel single-directional MEMS microphone

[ technical field ] A method for producing a semiconductor device

The invention relates to the field of microphones, in particular to a novel single-direction MEMS (micro-electromechanical systems) microphone.

[ background of the invention ]

MEMS is a Micro-Electro mechanical System (Micro-Electro mechanical System), which refers to a sensor device with a size of several millimeters or less, and the internal structure of the sensor device is generally in the micrometer or nanometer level, and the sensor device is an independent intelligent System. Briefly, the MEMS is a silicon-based sensor formed by miniaturizing mechanical components of a conventional sensor, fixing a device on a silicon wafer (wafer) by a three-dimensional stacking technique, for example, a three-dimensional through-silicon via (TSV) technique, and finally cutting and assembling the device in a specially-customized packaging form according to different application occasions. The MEMS has the advantages of miniaturization and high integration degree which cannot be achieved by the common sensor;

the microphone can be divided into a full direction, a double direction and a single direction according to different pickup modes of the microphone; the omnidirectional microphone has the same sensitivity to sounds in all directions, and the recognition degrees of the sounds in different directions are consistent; the double-directional microphone is sensitive to the sounds in the front and the back, and the sensitivity to the sounds in other areas is reduced; the single directional microphone is sensitive to only forward sound, and the sensitivity to sound in other areas is reduced; the unidirectional microphone and the double-directional microphone are collectively called as the directional microphone, compared with the omni-directional microphone, the directional microphone can reject a large amount of environmental noise, selectively pick up sound signals in a fixed area, can realize the directional sound pickup function through a single product, and has important value for terminal products needing regional sound pickup. However, the existing microphone cannot achieve complete unidirectional sound pickup, and noise is generated during use.

[ summary of the invention ]

The invention aims to overcome the defects of the prior art and provides a novel single-direction MEMS microphone and a production method thereof, which can effectively avoid noise picked up when the microphone picks up sound in a single direction.

The invention can be realized by the following technical scheme:

the invention discloses a novel single-direction MEMS microphone, which comprises a pad PCB and an MEMS microphone, wherein a first pad sound hole and a second pad sound hole which penetrate through the pad PCB are arranged on the pad PCB, tuning cloth is fixed at the positions of the first pad sound hole and the second pad sound hole on the lower end surface of the pad PCB, a lower sound guide groove PCB is fixed on the upper end surface of the pad PCB, a lower first sound hole which penetrates through the lower sound guide groove PCB is arranged at the position, corresponding to the first pad sound hole, on the lower sound guide groove PCB, a second sound guide groove is arranged at the position, corresponding to the second pad sound hole, on the lower sound guide groove PCB, a lower second sound hole which is connected with the tail end of the second sound guide groove is arranged at the middle position on the lower sound guide groove PCB, an upper sound guide groove PCB is fixed on the upper end surface of the lower sound guide groove PCB, a cavity for accommodating the MEMS microphone is arranged at the middle part of the upper sound guide groove PCB, and is connected with the lower second sound hole, a first sound guiding groove connected with the cavity is further formed in one side of the upper sound guiding groove PCB, the first sound guiding groove is connected with the lower first sound hole, a cover plate PCB is further fixed on the upper end face of the upper sound guiding groove PCB, the MEMS microphone comprises a Sensor chip fixed on the lower sound guiding groove PCB, the Sensor chip is connected with the audio amplification chip through a bonding wire, the Sensor chip comprises a circular silicon substrate surrounding the outer peripheral side of the lower second sound hole, a back electrode covering the silicon substrate is fixed above the silicon substrate, and a vibrating diaphragm surrounding the inner wall of the silicon substrate is fixed below the back electrode; because the bonding pad PCB, the lower sound guide groove PCB, the upper sound guide groove PCB and the cover plate PCB are tightly matched, the Sensor chip is fixed outside the lower second sound hole in a surrounding way, external sound reaches the upper surface of the vibrating diaphragm after passing through the first sound hole of the bonding pad, the lower first sound hole and the first sound guide groove, the external sound reaches the lower surface of the vibrating diaphragm after passing through the second sound hole of the bonding pad, the lower second sound hole and the second sound guide groove, pressure difference is formed between the upper surface and the lower surface of the vibrating diaphragm to drive the vibrating diaphragm to vibrate, the sound pressure of the upper end surface of the vibrating diaphragm is more than or equal to that of the lower end surface of the vibrating diaphragm in the process, and along with the change of the direction, the attenuation of sound signals is larger due to the fact that the sound path is longer in different directions, so that the difference between the signals after reaching the first sound hole of the bonding pad and being damped by the tuning cloth and the second sound hole, the two signals can almost cancel each other out, and two almost equally large forces act on the upper and lower sides of the diaphragm, so that the signals are almost absent, and the sound in front of the face opposite to the first sound hole of the bonding pad can be effectively picked up.

A novel production method of a single-direction MEMS microphone comprises the following steps

a. The audio amplification chip is pasted on the upper end surface of the lower sound guide groove PCB by using an adhesive and is cured by baking;

b. the Sensor chip is attached to the upper portion of the lower sound guide groove PCB right above the second sound hole through an adhesive, and the bottom of the Sensor chip is completely sealed through the adhesive;

c. the electrical connection among the Sensor chip, the audio amplification chip and the lower sound guide groove PCB is completed by using a bonding wire in a lead bonding mode;

d. bonding the lower sound guide groove PCB and the pad PCB together by using an adhesive, wherein the adhesive layer is completely sealed;

f. bonding the lower sound guide groove PCB and the upper sound guide groove PCB together by using an adhesive, wherein the adhesive layer is completely sealed;

g. bonding the cover plate PCB and the upper sound guide groove PCB together by using an adhesive, wherein the adhesive layer is completely sealed;

h. and attaching the tuning cloth to the first sound hole of the bonding pad and the second sound hole of the bonding pad.

Preferably, the Sensor chip is fixed at the position of the lower second sound hole.

Preferably, the damping of the tuning cloth at the first sound hole of the bonding pad is smaller than the damping of the tuning cloth at the second sound hole of the bonding pad.

Preferably, the bonding wire is made of metal materials such as gold, aluminum, copper and the like.

Preferably, the adhesive is made of a silica gel material.

Compared with the prior art, the invention has the following advantages:

1. because the bonding pad PCB, the lower sound guide groove PCB, the upper sound guide groove PCB and the cover plate PCB are tightly matched, the Sensor chip is fixed outside the lower second sound hole in a surrounding way, external sound reaches the upper surface of the vibrating diaphragm after passing through the first sound hole of the bonding pad, the lower first sound hole and the first sound guide groove, the external sound reaches the lower surface of the vibrating diaphragm after passing through the second sound hole of the bonding pad, the lower second sound hole and the second sound guide groove, pressure difference is formed between the upper surface and the lower surface of the vibrating diaphragm to drive the vibrating diaphragm to vibrate, the sound pressure of the upper end surface of the vibrating diaphragm is more than or equal to that of the lower end surface of the vibrating diaphragm in the process, and along with the change of the direction, the attenuation of sound signals is larger due to the fact that the sound path is longer in different directions, so that the difference between the signals after reaching the first sound hole of the bonding pad and being damped by the tuning cloth and the second sound hole, the two signals can almost cancel each other out, and two almost equally large forces act on the upper and lower sides of the diaphragm, so that the signals are almost absent, and the sound in front of the face directly opposite to the first sound hole can be effectively picked up.

2. The tuning cloth still has dirt-proof effect, can effectively avoid foreign matters such as dust to enter into the sound intracavity, influences this device and uses.

3. The product can reduce the product volume through the surface mounting mode, so that the product is more miniaturized.

[ description of the drawings ]

The following detailed description of embodiments of the invention is provided in conjunction with the appended drawings, in which:

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a cross-sectional view of the present invention;

FIG. 3 is a diagram of a MEMS chip of the present invention;

FIG. 4 is a schematic diagram of the structure of the MEMS chip of the present invention;

FIG. 5 is a circuit diagram of a microphone of the present invention;

in the figure: 1. a pad PCB; 11. a pad first acoustic hole; 12. a second sound hole of the bonding pad; 2. a lower sound guide groove PCB; 21. a lower first sound hole; 22. a lower second sound hole; 23. a second sound guide groove; 3. an upper sound guide groove PCB; 31. a first sound guide groove; 32. a cavity; 4. a Sensor chip; 401. a back electrode; 402. silicon-based; 403. vibrating diaphragm; 5. a sound adjusting cloth; 6. a cover plate PCB; 7. an audio amplification chip;

[ detailed description ] embodiments

The embodiments of the present invention will be described in detail below with reference to the accompanying drawings:

as shown in fig. 1 to 5, the present invention discloses a novel single-direction MEMS microphone, which comprises a pad PCB1 and a MEMS microphone, wherein a pad PCB1 is provided with a pad first sound hole 11 and a pad second sound hole 12 penetrating through a pad PCB1, a tuning cloth 5 is fixed at each of the pad first sound hole 11 and the pad second sound hole 12 at a lower end surface of the pad PCB1, a lower sound guiding groove PCB2 is fixed at an upper end surface of the pad PCB1, a lower first sound hole 21 penetrating through a lower sound guiding groove PCB2 is arranged at a position on the lower sound guiding groove PCB2 corresponding to the pad first sound hole 11, a second sound guiding groove 23 is arranged at a position on the lower sound guiding groove PCB2 corresponding to the pad second sound hole 12, a lower second sound hole 22 connected to a terminal of the second sound guiding groove 23 is arranged at an intermediate position on the lower sound guiding groove PCB2, an upper end surface of the lower sound guiding groove PCB2 is fixed with an upper sound guiding groove 3, a cavity for accommodating the microphone 32 is arranged at a middle portion of the upper sound guiding groove 3, and the lower sound guiding groove PCB 22 is connected to the MEMS microphone, a first sound guiding groove 31 connected with the cavity 32 is further arranged on one side of the upper sound guiding groove PCB3, the first sound guiding groove 31 is connected with the lower first sound hole 21, a cover plate PCB6 is further fixed on the upper end face of the upper sound guiding groove PCB3, the MEMS microphone comprises a Sensor chip 4 fixed on the lower sound guiding groove PCB2, the Sensor chip 4 is connected with the audio amplification chip 7 through a bonding wire, the Sensor chip 4 comprises a circular silicon substrate 402 surrounding the outer peripheral side of the lower second sound hole 22, a back electrode 401 covering the silicon substrate 402 is fixed above the silicon substrate 402, and a vibrating diaphragm 403 surrounding the inner wall of the silicon substrate 402 is fixed below the back electrode 401; because the bonding pad PCB1, the lower sound guide groove PCB2, the upper sound guide groove PCB3 and the cover plate PCB6 are tightly matched, the Sensor chip 4 is fixed outside the lower second sound hole 22 in a surrounding manner, external sound reaches the upper surface of the vibrating diaphragm 403 after passing through the bonding pad first sound hole 11, the lower first sound hole 21 and the first sound guide groove 31, the external sound reaches the lower surface of the vibrating diaphragm 403 after passing through the bonding pad second sound hole 12, the lower second sound hole 22 and the second sound guide groove 23, pressure difference is formed between the upper surface and the lower surface of the vibrating diaphragm 403 to drive the vibrating diaphragm 403 to vibrate, and because the forces acting on the vibrating diaphragm 403 by sound transmitted in different directions are different, in the process, the sound pressure on the upper end surface of the vibrating diaphragm 403 is larger than or equal to the sound pressure on the lower end surface of the vibrating diaphragm 403, and along with the change of directions, the sound signal attenuation in different directions is larger because of longer damping, so that the difference between the signal after reaching the bonding pad first sound hole 11 and being damped by the sound tuning cloth 5, the two signals almost cancel each other, and two almost equally large forces act on the upper and lower sides of the diaphragm 403, so that the signals are almost absent, and the sound just in front of the face of the pad first sound hole 11 can be effectively picked up.

A novel production method of a single-direction MEMS microphone comprises the following steps

a. The audio amplification chip 7 is attached to the upper end face of the lower sound guide groove PCB2 by using an adhesive and is cured by baking;

b. the Sensor chip 4 is attached to the upper end face of the lower sound guide groove PCB2 right above the second sound hole 22 through an adhesive, and the bottom of the Sensor chip 4 is completely sealed through the adhesive;

c. the electrical connection among the Sensor chip 4, the audio amplification chip 7 and the lower sound guide groove PCB2 is completed by using a bonding wire in a lead bonding mode;

d. the lower sound guide groove PCB2 and the land PCB1 are adhered together using an adhesive, the adhesive layer being completely sealed;

f. the lower sound guide groove PCB2 and the upper sound guide groove PCB3 are adhered together using an adhesive, the adhesive layer being completely sealed;

g. the cover PCB6 and the upper sound guide groove PCB3 are adhered together using an adhesive, the adhesive layer being completely sealed;

h. the tuning cloth 5 is attached to the pad first sound hole 11 and the pad second sound hole 12.

△ is the equivalent distance between the front and the back of the diaphragm 403, the sound reaches the two sides of the diaphragm 403 with different strengths after passing through different damping tuning cloths 5, so that there is a pressure difference between the two sides of the diaphragm 403, as shown in fig. 4, the sound pressures acting on the two sides of the diaphragm 403 are respectively P1 and P2, and then the force F of the diaphragm is (P1-P2) S, where P1 is the sound pressure on one side of the diaphragm 403, P2 is the sound pressure on the other side of the diaphragm 403, P1 and P2 act on the two sides of the diaphragm 403, and the actions of P1 and P2 are mutually inhibited, and finally, the motion state of the diaphragm 403 is compliant with the sound pressure on the side with the larger sound pressure and moves under the action of the force F.

As shown in fig. 3, the structure of the Sensor chip 4 is shown, the Sensor chip 4 is composed of a diaphragm 403, a back electrode 401 and a silicon substrate 402, the diaphragm 403 and the back electrode 401 are fixed inside a cavity of the silicon substrate 402 by a semiconductor processing technology (etching, polishing, evaporation, etc.), the operation principle of the chip is equivalent to a parallel plate capacitor, the diaphragm 403 and the back electrode 401 constitute upper and lower substrates of the capacitor, charges directionally move under the action of voltage, a stable voltage difference is formed between the upper and lower substrates, when external sound pressure acts on the diaphragm 403, the distance between the diaphragm 403 and the back electrode 401 changes, the formula C ∈ S/4 π kd shows that the capacitance of the capacitor changes accordingly when the distance changes (C: capacitance ∈: dielectric constant, S: the facing area d between the diaphragm 403 and the back electrode 401: the distance between the two plates, k: Q/C), when the distance changes, the output voltage value changes (Q: the constant charge value of the capacitor 403, Q: the constant charge value, U: U-403, U-36, U-v — 3632, when the voltage of the chip is changed, U — 3632, the voltage of the chip is changed after the external sound pressure changes, and the voltage of the chip is changed by the voltage is 1-3632.

As shown in fig. 5: the MEMS transducer is a Sensor chip 4 and is connected with an audio amplification chip 7 at the rear end through a bonding wire;

wherein the BIAS electrode of the Sensor chip 4 is connected with the BIAS voltage of the audio amplification chip 7, and the audio amplification chip 7 provides a stable Charge source for the operation of the Sensor chip 4 through a Charge bump; the MICIN electrode of the audio amplification chip 7 is connected with Vout of the Sensor chip, the Sensor chip transmits the output signal to the interface MICIN of the audio amplification chip 7, and the audio amplification chip 7 performs subsequent amplification, filtering and other processing;

the audio amplifier chip 7 needs an external power supply for working, so that the VDD end of the audio amplifier chip 7 needs an external power supply, the power supply voltage is 1.6V-3.6V, the GND end of the audio amplifier chip 7 is grounded, and the OUT end of the audio amplifier chip 7 is connected with the OUT end of the lower sound guide groove PCB2, thereby realizing the function of leading OUT an output signal.

Wherein the Sensor chip 4 is fixed at the position of the lower second sound hole 22.

The damping of the tuning cloth 5 at the first sound hole 11 of the pad is smaller than that of the tuning cloth 5 at the second sound hole 12 of the pad.

The bonding wire is made of metal materials such as gold, aluminum, copper and the like.

Wherein, the adhesive is made of silica gel material.

The above description is only a preferred embodiment of the present invention, and it should be noted that a person skilled in the art can make various changes, modifications, substitutions and alterations to the embodiments without departing from the technical principles of the present invention, and such changes, modifications, substitutions and alterations should also be regarded as the protection scope of the present invention.

Claims (3)

1. A novel single-directional MEMS microphone is characterized in that: the MEMS microphone comprises a pad PCB and an MEMS microphone, wherein a first pad sound hole and a second pad sound hole which penetrate through the pad PCB are arranged on the pad PCB, sound-tuning cloths are fixed at the positions of the first pad sound hole and the second pad sound hole of the lower end face of the pad PCB, a lower sound-guiding groove PCB is fixed on the upper end face of the pad PCB, a lower first sound hole which penetrates through the lower sound-guiding groove PCB is arranged at the position, corresponding to the first pad sound hole, of the lower sound-guiding groove PCB, a second sound-guiding groove is arranged at the position, corresponding to the second pad sound hole, of the lower sound-guiding groove PCB, a lower second sound hole which is connected with the tail end of the second sound-guiding groove is arranged at the middle position of the lower sound-guiding groove PCB, an upper sound-guiding groove PCB is fixed on the upper end face of the lower sound-guiding groove PCB, a cavity for accommodating the MEMS microphone is arranged in the middle of the upper sound-guiding groove PCB, the cavity is connected with the lower second sound hole, a first sound-guiding groove, the first sound guiding groove is connected with the lower first sound hole, a cover plate PCB is further fixed on the upper end face of the upper sound guiding groove PCB, the MEMS microphone comprises a Sensor chip fixed on the lower sound guiding groove PCB, and the Sensor chip is connected with the audio amplification chip through a bonding wire.

2. The novel single directional MEMS microphone of claim 1, wherein: the Sensor chip is fixed at the position of the lower second sound hole.

3. The novel single directional MEMS microphone of claim 1, wherein: and the damping of the tuning cloth at the first sound hole of the bonding pad is smaller than that of the tuning cloth at the second sound hole of the bonding pad.

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