CN216291435U

CN216291435U - Packaging board of MEMS microphone and microphone

Info

Publication number: CN216291435U
Application number: CN202120834566.XU
Authority: CN
Inventors: 陈为波; 曹诚; 李涛
Original assignee: Dongguan Ruiqin Electronics Co ltd
Current assignee: Dongguan Ruiqin Electronics Co ltd
Priority date: 2021-04-22
Filing date: 2021-04-22
Publication date: 2022-04-12
Anticipated expiration: 2031-04-22

Abstract

The utility model discloses a packaging plate of an MEMS microphone and the microphone. The packaging plate of the MEMS microphone comprises a first circuit board; and the second circuit board is arranged opposite to the first circuit board and forms a first back cavity with the first circuit board, wherein a through hole is formed in the second circuit board and communicated with the first back cavity. According to the packaging plate of the MEMS microphone and the microphone, the volume of the back cavity of the microphone can be increased, and the signal-to-noise ratio of the microphone is improved.

Description

Packaging board of MEMS microphone and microphone

Technical Field

The utility model relates to the technical field of semiconductor devices, in particular to a packaging plate of an MEMS microphone and the microphone.

Background

MEMS (Micro-Electro-Mechanical System) microphones are microphones manufactured based on MEMS technology, and compared to conventional microphones, MEMS microphones can be manufactured by a surface mount process, can withstand a high reflow temperature, are easily integrated with CMOS (Complementary Metal-Oxide-Semiconductor) processes and other audio circuits, and have improved noise cancellation performance and good RF (Radio Frequency) and EMI (Electromagnetic Interference) suppression performance. MEMS is widely used in the field of intelligent terminals such as voice call, intelligent voice interaction and the like at present.

The SIGNAL-to-NOISE RATIO (S/N) of the MEMS microphone is an important index, and is related to the sound pick-up definition and the algorithm NOISE reduction effect. S/N is the ratio of the electric signal of the microphone to the noise therein, generally, the larger the signal-to-noise ratio, the quieter the microphone is, the smaller the noise mixed in the electric signal, the more margin is provided for isolating the required sound from the unnecessary noise, and the higher the sound quality of the sound playback is. In a MEMS microphone, the back cavity volume is an important factor affecting the signal-to-noise ratio, and the larger the back cavity volume, the smaller the signal-to-noise ratio, and vice versa. In the existing MEMS microphone, only a cavity formed by a chip and the surface of a packaging plate is used as a back cavity, and the volume of the back cavity greatly limits the improvement of the signal-to-noise ratio.

Therefore, a new package board for MEMS microphone and microphone are desired, which can overcome the above problems.

SUMMERY OF THE UTILITY MODEL

In view of the above problems, the present invention provides a package board of a MEMS microphone and a microphone, so as to increase the volume of a back cavity of the microphone, thereby improving the signal-to-noise ratio of the microphone.

According to an aspect of the present invention, there is provided a package board of a MEMS microphone, including a first circuit board; and the second circuit board is arranged opposite to the first circuit board and forms a first back cavity with the first circuit board, wherein a through hole is formed in the second circuit board and communicated with the first back cavity.

Preferably, the package board further includes an adhesive, which is respectively connected to the first circuit board and the second circuit board, and is used for adhering and/or spacing the first circuit board and the second circuit board.

Preferably, the first circuit board and/or the second circuit board comprises a boss for forming the first back cavity.

Preferably, the first circuit board comprises a printed circuit board; the second circuit board comprises a flexible circuit board.

According to another aspect of the present invention, there is provided a MEMS microphone comprising a package plate as described above; and the chip is positioned on the packaging plate, forms a second back cavity with the packaging plate and is used for converting a sound signal into an electric signal, wherein the second back cavity is communicated with the first back cavity through the through hole.

Preferably, the MEMS microphone further comprises a housing connected with the package board; the sound receiving hole is positioned on the shell, penetrates through the shell and is used for leading in the sound signal; an ASIC chip electrically connected with the chip to receive the electric signal and process the electric signal; the bonding wire is respectively connected with the chip and the ASIC chip and used for transmitting the electric signals; and the protective glue is positioned on the ASIC chip and used for protecting the ASIC chip.

Preferably, the open area of the through hole is smaller than or equal to the cross-sectional area of the second back cavity.

Preferably, the through hole is a circular through hole; the cross section of the second back cavity is circular or rectangular; the diameter of the through hole is smaller than or equal to the diameter of the second back cavity or the side length of the cross section.

Preferably, the chip comprises a substrate, and a vibrating membrane and a back plate which are positioned on the substrate; an opening is formed in the substrate, and the opening and the vibrating membrane form a groove; the groove is used for forming the second back cavity.

According to the packaging plate of the MEMS microphone and the microphone provided by the embodiment of the utility model, the first back cavity used for increasing the volume of the back cavity is arranged on the packaging plate, so that the volume of the back cavity is increased, and the performances of the microphone such as the signal-to-noise ratio and the like are improved.

According to the packaging plate of the MEMS microphone and the microphone, the shape and the volume of the first back cavity in the packaging plate, the position relation between the first back cavity and the second back cavity and the like can be adjusted according to the adhesive and/or the lug boss, so that the performance of the microphone can be adjusted flexibly, and the MEMS microphone has a wider application range.

According to the packaging plate of the MEMS microphone and the microphone, the packaging plate is formed by laminating the PCB with the cavity and the FPC with the hole or is formed by SMT (surface mount technology) mounting in a packaging factory, the structure is simple, and the manufacturing is simple and convenient.

According to the packaging plate of the MEMS microphone and the microphone, a first back cavity and a through hole are formed in the packaging plate, and a second back cavity is formed by a chip and the packaging plate; the first back cavity is communicated with the second back cavity through the through hole to form a back cavity with a larger volume, so that the signal-to-noise ratio of the microphone is improved.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

fig. 1 shows a schematic structural diagram of a MEMS microphone according to an embodiment of the utility model;

fig. 2 shows a schematic structural view of a package board according to an embodiment of the utility model;

FIG. 3 shows a schematic structural diagram of a back cavity according to an embodiment of the utility model;

fig. 4 shows a schematic perspective view of a MEMS microphone according to an embodiment of the present invention.

Detailed Description

Various embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Like elements in the various figures are denoted by the same or similar reference numerals. For purposes of clarity, the various features in the drawings are not necessarily drawn to scale. Moreover, certain well-known elements may not be shown in the figures.

The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples. In the following description, numerous specific details of the utility model, such as structure, materials, dimensions, processing techniques and techniques of components, are set forth in order to provide a more thorough understanding of the utility model. However, as will be understood by those skilled in the art, the present invention may be practiced without these specific details.

It will be understood that when a layer, region or layer is referred to as being "on" or "over" another layer, region or layer in describing the structure of the component, it can be directly on the other layer, region or layer or intervening layers or regions may also be present. Also, if the component is turned over, one layer or region may be "under" or "beneath" another layer or region.

Fig. 1 shows a schematic structural diagram of a MEMS microphone according to an embodiment of the present invention. As shown in fig. 1, the MEMS microphone according to the embodiment of the present invention includes a package board 10, a chip 20, a housing 30, a bonding wire 40, a sound receiving hole 50, a protective adhesive 60, an ASIC chip 70, a cavity 80, and a back cavity 90. Wherein the back cavity 90 comprises a first back cavity 91 and a second back cavity 92.

In particular, the package plate 10 is used for the packaging of a microphone structure and provides a first back cavity 91. The package Board 10 includes, for example, a PCB (Printed Circuit Board) Board and an FPC (Flexible Printed Circuit) Board. The FPC board is used to support the chip 20 and the like. The package board 10 may also be referred to as a package structure, or as a Printed Circuit Board Assembly (PCBA).

The housing 30 is coupled to the package plate 10 to form a cavity 80. The cavity 80 is used for accommodating devices such as the chip 20. Optionally, the housing 30 forms a front cavity together with the package plate 10 and the chip 20. The housing 30 may be a metal housing, a ceramic housing, a plastic housing, or the like.

The chip 20 is located on the package board 10 and forms a second back cavity 92 with the package board 10, and the chip 20 is used for converting the sound signal into an electrical signal. The package board 10 is provided with a through hole, and after the chip 20 is connected to the package board 10, the second back cavity 92 and the first back cavity 91 are communicated through the through hole. The chip 20 is, for example, a sensor chip, and is capable of converting a received sound signal into an electrical signal. The chip 20 includes, for example, a diaphragm and a plate disposed opposite to the diaphragm, with a gap therebetween, and the diaphragm and the plate form a capacitor. When the MEMS microphone works, sound entering from the sound hole causes the vibration of the vibration membrane, so that the distance between the vibration membrane and the polar plate is changed, the change of the capacitance value is caused, and further, a sound signal is converted into an electric signal. The chip 20 may also be another kind of device that can convert an acoustic signal into an electrical signal.

The acoustic opening 50 is located on the housing 30 and extends through the housing 30. The acoustic hole 50 is used for introduction of an acoustic signal. The shape of the acoustic hole 50 may be circular, square, oval, etc., and the number may be one or more. The acoustic hole 50 may be provided at any position of the housing 30. Preferably, the acoustic opening 50 is disposed opposite (the diaphragm of) the chip 20.

An ASIC (Application Specific Integrated Circuit) chip 70 is electrically connected to the chip 20 to receive and process electrical signals. The ASIC chip 70 may be disposed in various locations. Optionally, an ASIC chip 70 is disposed in the cavity 80. Optionally, an ASIC chip 70 is attached to the package board 10. Optionally, the ASIC chip 70 is an audio amplifier chip.

The bonding wires 40 are connected to the chip 20 and the ASIC chip 70, respectively, for the transfer of electrical signals. The bonding wire 40 is, for example, a gold wire, a silver wire, or the like. Alternatively, the bonding wires 40 are plural, and the bonding wires 40 are also connected to the ASIC chip 70 and the package board (PCB board and/or FPC board) 10, respectively.

The protective paste 60 is located on the ASIC chip 70 to protect the ASIC chip 70. The protective paste 60 is, for example, located on the upper surface of the ASIC chip 70, and is used to protect the connection between the ASIC chip 70 and the bonding wire 40. The protective adhesive 60 is, for example, an epoxy adhesive.

The utility model belongs to the technical field of semiconductor elements, relates to microphone raw materials and packaging technology, and particularly relates to a structure of a PCB (packaging board). Specifically, the design relates to a PCB used in a microphone packaging process, and the PCB comprises a PCB with an (inverted) groove structure and a surface layer FPC flexible printed circuit board.

Fig. 2 shows a schematic structural view of a package board according to an embodiment of the present invention. As shown in fig. 2, the package board 10 according to the embodiment of the present invention includes a first circuit board 11, a second circuit board 13, an adhesive 12, and a first back cavity 91. Wherein the second circuit board 13 is provided with a through hole 93.

Specifically, the first circuit board 11 is, for example, a PCB board. Optionally, the first circuit board 11 is located at the bottom of the package board 10.

The second circuit board 13 is disposed opposite to the first circuit board 11, and forms a first back cavity 91 with the first circuit board. The second circuit board 13 is provided with a through hole 93, and the through hole 93 is communicated with the first back cavity 91. The second circuit board 13 is, for example, an FPC board. The second circuit board 13(FPC) is used to support the MEMS chip. The second circuit board 13 is disposed opposite to the first circuit board 11 with a certain interval to form a cavity as the first back cavity 91. Alternatively, an adhesive and/or a boss for spacing (a certain distance between the first circuit board and the second circuit board) is provided between the first circuit board 11 and the second circuit board 13.

And an adhesive (adhesive layer) 12 connected to the first circuit board 11 and the second circuit board 13, respectively, for adhering the first circuit board 11 and the second circuit board 13. Alternatively, the adhesive (adhesive layer) 12 has a certain thickness, and also serves to space the first circuit board 11 and the second circuit board 13 to form the first back cavity 91. Alternatively, the thickness of the adhesive 12 may be adjustable, and the thickness of the adhesive layer may be set according to actual requirements to adjust the volume (depth) of the first back cavity 91. Optionally, the adhesive 12 is a solder paste adhesive.

In an alternative embodiment of the present invention, the first circuit board 11 includes a boss 111, and the boss 111 is used to form the first back cavity 91. Specifically, the bottom surface of the first circuit board 11 forms a groove (deepened groove) with the boss 111 on the first circuit board 11. After the first circuit board 11 is connected to the second circuit board 13, the groove and the second circuit board 13 form a first back cavity 91. Alternatively, bosses may be provided on the first circuit board 11 and/or the second circuit board 13 (in the case where bosses are provided on both the first circuit board 11 and the second circuit board 13, the bosses on the first circuit board 11 are disposed opposite the bosses on the second circuit board 13). The boss is used for the formation of the first back cavity 91. Specifically, the bosses are provided such that the non-boss positions of the first circuit board 11 and the second circuit board 13 cannot be directly contacted (a gap exists between the first circuit board 11 and the second circuit board 13), thereby forming the first back cavity 91.

In an alternative embodiment of the present invention, the first circuit board 11 comprises (is) a PCB board, and the second circuit board 13 comprises (is) a FPC board, which are bonded (connected) together by using a Surface Mounted Technology (SMT) or other process.

Fig. 3 shows a schematic structural diagram of a back cavity according to an embodiment of the utility model. As shown in fig. 3, the back cavity 90 according to an embodiment of the present invention includes a first back cavity 91 and a second back cavity 92.

Specifically, the chip 20 is, for example, a MEMS chip, and includes a substrate 23, a diaphragm 22 located on the substrate 23, and a back plate 21. An opening is provided in the substrate 23, and the opening in the substrate 23 forms a groove with the diaphragm 22. The recess is used to form a second back cavity 92. After the chip 20 is attached to the package board, a second back cavity 92 is formed (by the groove on the chip 20 and the package board).

The package plate is provided with a through hole 93 and a first back cavity 91. The chip 20 is connected to the package board and is located above the through hole 93. After the chip 20 is connected to the package board, the first back cavity 91 and the second back cavity 92 are communicated through the through hole 93 to form a back cavity 90. Alternatively, the chip 20 is fixed in the corresponding position of the package board by an adhesive, so that the second back cavity 92 is located above the through hole 93. For example, a silicone adhesive having stress resistance and buffering is selected to bond the package board and the chip 20.

In an alternative embodiment of the present invention, the open area of the through hole 93 is less than or equal to the cross-sectional area of the second back cavity 92. The through hole 93 is located directly below the second back cavity 92. Alternatively, the through hole 93 is a circular through hole, the cross section of the second back cavity 92 is circular or rectangular, and the diameter of the through hole 93 is smaller than or equal to the diameter (inner diameter) or the cross section side length of the second back cavity 92.

In an alternative embodiment of the utility model, the first circuit board on the package board forms a deepened groove with the boss and/or the adhesive on the first circuit board. The length, width, depth, shape, volume and the like of the deepening groove can be set according to actual requirements.

In an alternative embodiment of the present invention, the number of the through holes 93 is plural for communicating the first back chamber 91 and the second back chamber 92. Optionally, a plurality of through holes 93 are distributed in an array on the package board.

As shown in fig. 3, the package board according to the embodiment of the present invention includes a first circuit board 11, an adhesive 12, and a second circuit board 13. Wherein a first back cavity 91 is formed in the package board; the second circuit board 13 is provided with a through hole 93.

Specifically, the adhesive 12 is connected to the first circuit board 11 and the second circuit board 13, respectively, for connecting and/or spacing the first circuit board 11 and the second circuit board 13. The (lower surface of the) first circuit board 11, the (upper surface of the) second circuit board 13 and the (side surface of the) adhesive 12 form a groove (first back cavity 91). The shape, position, etc. of the adhesive 12 can be flexibly set according to actual requirements, so that the shape, position, relative position of the first back cavity 91 and the second back cavity 92, etc. can meet the actual requirements. Optionally, a boss is disposed on the first circuit board 11 and/or the second circuit board 13, and the boss is used for spacing the first circuit board 11 and the second circuit board 13 and forming the first back cavity 91. The shape, position, etc. of boss can carry out nimble setting according to actual demand to make the shape, the position of first back of the body chamber 91, and the relative position of first back of the body chamber 91 and second back of the body chamber 92 etc. satisfy actual demand.

Fig. 4 shows a schematic perspective view of a MEMS microphone according to an embodiment of the present invention. As shown in fig. 4, the MEMS microphone according to the embodiment of the present invention includes a package board 10, a chip 20, and a case 30. Wherein, the package board 10 is provided with a through hole 93; the housing 30 is provided with a sound-absorbing hole 50.

Specifically, the housing 30 is connected to the package board 10(PCB substrate), and the housing 30 is attached to the solder ring of the package board 10(PCB substrate) by Surface Mount Technology (SMT) using, for example, solder paste. The housing 30 and the package plate 10 form a cavity.

The housing 30 is provided with a sound receiving hole 50 for transmitting sound. The acoustic hole 50 is a through hole penetrating the case 30.

The chip 20 is located in the cavity formed by the housing 30 and the package board 10, and is connected to the package board 10. The chip 20 is shaped as a rectangular parallelepiped with a hollow center and no bottom. After the chip 20 is connected to the package board 10, a second cavity is formed. The package board 10 is provided with a through hole 93, and the through hole 93 is located on the package board 10 below the chip 20. A first back cavity is provided inside the package plate 10. The first back cavity is communicated with the second back cavity through a through hole 93. The first back cavity and the second back cavity jointly form a back cavity of the MEMS microphone. The housing 30 together with the package plate 10 and (the outer surface of) the chip 20 constitute the front cavity of the MEMS microphone.

The MEMS microphone according to the embodiment of the utility model can be manufactured according to the following steps:

step S101: connecting the chip and the packaging plate, wherein the chip and the packaging plate form a second back cavity;

the chip is connected to the package plate, for example, by being fixed to the package plate by an adhesive, and the chip and the package plate form a second back cavity.

In an alternative embodiment of the present invention, a (Sensor) chip and an audio Amplifier (ASIC) chip are fixed on the corresponding positions of a PCB substrate (package board) by an adhesive, wherein the Sensor chip is bonded by a silicone adhesive having stress resistance and buffering function, and the audio amplifier chip is bonded by an epoxy adhesive. Optionally, the sensor chip, the audio amplifier chip and the package (substrate) are electrically connected by a bonding wire.

Step S102: the housing is connected to the package board.

The housing is connected to the package board, for example, between the housing and the PCB substrate by using solder paste attached to solder rings of the PCB substrate by SMT techniques. Wherein, a first back cavity is arranged in the packaging plate; the packaging plate is provided with a through hole at a position opposite to the chip, and the first back cavity and the second back cavity are communicated through the through hole.

In an alternative embodiment of the present invention, the package board includes a first circuit board (PCB) and a second circuit board (FPC). The manufacturing method of the package board includes: and pressing the PCB and the FPC together by adopting a soft and hard board combined process in a board factory.

In an alternative embodiment of the present invention, the package board includes a first circuit board (PCB) and a second circuit board (FPC). The manufacturing method of the package board includes: the first circuit board and the second circuit board are obtained (e.g., the PCB and FPC are purchased from a supplier, respectively) and are joined together at a packaging facility using a process such as SMT.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

In accordance with the embodiments of the present invention as set forth above, these embodiments are not exhaustive and do not limit the utility model to the precise embodiments described. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the utility model and the practical application, to thereby enable others skilled in the art to best utilize the utility model and various embodiments with various modifications as are suited to the particular use contemplated. The utility model is limited only by the claims and their full scope and equivalents.

Claims

1. A package board for a MEMS microphone, comprising:

a first circuit board; and

a second circuit board arranged opposite to the first circuit board and forming a first back cavity with the first circuit board,

the second circuit board is provided with a through hole, and the through hole is communicated with the first back cavity;

the package board further includes:

and the adhesive is respectively connected with the first circuit board and the second circuit board and is used for bonding and/or spacing the first circuit board and the second circuit board.

2. The package board according to claim 1, wherein the first circuit board and/or the second circuit comprises:

a boss for forming the first back cavity.

3. The package board of claim 1, wherein the first circuit board comprises a printed circuit board; the second circuit board comprises a flexible circuit board.

4. A MEMS microphone, comprising:

the package board of any one of claims 1-3; and

a chip located on the packaging plate and forming a second back cavity with the packaging plate for converting the sound signal into an electrical signal,

wherein the second back cavity and the first back cavity are communicated through the through hole.

5. The MEMS microphone of claim 4, further comprising:

the shell is connected with the packaging plate;

the sound receiving hole is positioned on the shell, penetrates through the shell and is used for leading in the sound signal;

an ASIC chip electrically connected with the chip to receive the electric signal and process the electric signal;

the bonding wire is respectively connected with the chip and the ASIC chip and used for transmitting the electric signals; and

and the protective glue is positioned on the ASIC chip and used for protecting the ASIC chip.

6. The MEMS microphone of claim 4, wherein the open area of the through hole is less than or equal to the cross-sectional area of the second back cavity.

7. The MEMS microphone of claim 6, wherein the through-hole is a circular through-hole;

the cross section of the second back cavity is circular or rectangular;

the diameter of the through hole is smaller than or equal to the diameter of the second back cavity or the side length of the cross section.

8. The MEMS microphone of claim 4, wherein the chip comprises a substrate and a diaphragm and a backplate on the substrate;

an opening is formed in the substrate, and the opening and the vibrating membrane form a groove;

the groove is used for forming the second back cavity.