MEMS loudspeaker preparation process and MEMS loudspeaker

Abstract

The application provides a MEMS loudspeaker preparation process and a MEMS loudspeaker. The MEMS loudspeaker preparation process comprises the following steps: positioning a PCB plate; inverting and electrically connecting a MEMS chip to one side of the PCB plate where a first groove is formed; filling a high polymer protective material in the gap between the MEMS chip and the PCB plate and solidifying the high polymer protective material to combine the MEMS chip and the PCB plate into one. Since the PCB plate and the MEMS chip are combined into one by the high polymer protective member formed by the high polymer protective material between the PCB plate and the MEMS chip, and the high polymer protective member covers the conductive member, the overall packaging size of the MEMS loudspeaker is basically consistent with the size of the MEMS chip, so that the sensitivity parameter of the MEMS loudspeaker can be significantly improved, the sensitivity parameter is SPL / unit packaging plane area, and the conductive member is sealed and cannot contact external air, so that the reliability is higher, and thus the MEMS loudspeaker is suitable for scenes with narrow space and strict power consumption requirements.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sound production devices, and particularly relates to a MEMS loudspeaker preparation process and a MEMS loudspeaker. BACKGROUND

[0002] A loudspeaker is a device for converting an electric signal into an acoustic signal, and is widely applied to mobile terminals such as mobile phones and computers.

[0003] A MEMS loudspeaker (Micro-Electro-Mechanical System) has the advantages of good consistency, low power consumption, small size and low price compared with a traditional voice coil loudspeaker. A related art MEMS loudspeaker comprises a circuit board, a shell covering the circuit board to form a receiving space, and a MEMS loudspeaker chip placed in the receiving space and connected to the circuit board through wire bonding.

[0004] However, the sensitivity parameter (SPL / unit package plane area) of the MEMS loudspeaker in the related art is not high, which is not conducive to the application of the product in a narrow space and a strict power consumption requirement scene. SUMMARY

[0005] The application aims to provide a MEMS loudspeaker preparation process and a MEMS loudspeaker, which can improve the sensitivity parameter of the MEMS loudspeaker to be applicable to a narrow space and a strict power consumption requirement scene.

[0006] The technical scheme of the application is as follows: a MEMS loudspeaker preparation process is provided, comprising the following steps:

[0007] Positioning a PCB board material, wherein the PCB board material is provided with a first groove on one side thereof and a sound outlet hole penetrating through the other side thereof and communicating with the first groove;

[0008] Inverting and electrically connecting a MEMS chip to one side of the PCB board material on which the first groove is formed, wherein the diaphragm of the MEMS chip falls into the first groove in the thickness direction, and a gap is formed between the MEMS chip and the PCB board material;

[0009] Filling a high polymer protective material in the gap between the MEMS chip and the PCB board material and solidifying the high polymer protective material to combine the MEMS chip and the PCB board material into one body.

[0010] Further, the positioning of the PCB board material comprises:

[0011] Adjusting the pose of the PCB board material to keep the PCB board material horizontal and the first groove upward.

[0012] Further, after the positioning of the PCB board, the method further comprises the steps of:

[0013] Pasting a first mesh on the PCB board, so that the first mesh covers the sound hole.

[0014] Further, the inverted MEMS chip is electrically connected to the side of the PCB board where the first groove is formed, comprising:

[0015] Pointing the pads on the top side of the PCB board with conductive material;

[0016] Adjusting the pose of the MEMS chip so that the MEMS chip is inverted and aligned with the PCB board, and stacking the MEMS chip on the PCB board;

[0017] Curing the conductive material to form a conductive part electrically connected between the MEMS chip and the PCB board.

[0018] Further, the method of filling the gap between the MEMS chip and the PCB board with a polymer protective material and curing it, comprising:

[0019] Providing a glue sealing jig on the outer circumferential side of the MEMS chip and the PCB board, and forming a glue filling port communicating with the gap between the circumferential side of the MEMS chip and the inner side of the glue sealing jig;

[0020] Pointing the liquid polymer protective material to the glue filling port until the gap and the glue filling port are filled;

[0021] Curing the polymer protective material to form a polymer protective part in the gap and on the outer periphery of the MEMS chip.

[0022] Further, the height of the gap is between 1um and 300um.

[0023] Further, the side of the MEMS chip away from the PCB board has a second groove on the side of the diaphragm, and before or after the step of filling the gap between the MEMS chip and the PCB board with a polymer protective material and curing it, the method further comprises:

[0024] Pasting a second mesh on the side of the MEMS chip away from the PCB board to cover the opening of the second groove.

[0025] Further, the PCB board is provided with at least two first grooves, and after the step of filling the gap between the MEMS chip and the PCB board with a polymer protective material and curing it, the method further comprises:

[0026] Cutting the integrated MEMS chip and PCB board along a preset cutting track to form at least two speaker units, the preset cutting track being located between two adjacent first grooves.

[0027] Further, a MEMS speaker is provided, which is made by the preparation process as described in any one of the above, and comprises a PCB board, a MEMS chip located on one side of the PCB board, a conductive piece electrically connected between the PCB board and the MEMS chip, and a polymer protective piece integrated between the PCB board and the MEMS chip and covering the conductive piece, the PCB board and the MEMS chip enclosing a first sound cavity, and a sound hole being formed on a side of the PCB board away from the MEMS chip and communicating with the first sound cavity.

[0028] Further, the MEMS speaker further comprises a first mesh attached to the PCB board and covering the sound hole, and a second mesh attached to a side of the MEMS chip away from the PCB board and enclosing a second sound cavity with the MEMS chip.

[0029] The present application has the following beneficial effects: in the present application, the polymer protective piece formed by the polymer protective material between the PCB board and the MEMS chip is integrated, and the polymer protective piece covers the conductive piece, so that the overall packaging size of the MEMS speaker is basically consistent with the size of the MEMS chip (the chip size / packaging size can be greater than or equal to 95%, such as the chip size is Φ4.8mm, and the packaging size can be only Φ5mm or even smaller), so that the sensitivity parameter of the MEMS speaker can be significantly improved, the sensitivity parameter is SPL / unit packaging area, and the conductive piece is sealed and will not contact the external air, so that the reliability is higher, and thus the present application is suitable for scenes with small space and strict power consumption requirements. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 Structure diagram of the MEMS speaker of the first implementation mode;

[0031] Figure 2 Structure diagram of the MEMS speaker of the second implementation mode;

[0032] Figure 3 Structure diagram of the MEMS speaker of the third implementation mode;

[0033] Figure 4 Flowchart of steps S100 and S200 in the preparation process of the MEMS speaker of one embodiment of the present application;

[0034] Figure 5A flowchart of a first implementation of step S300 in a MEMS loudspeaker manufacturing process of an embodiment of the present application is shown in FIG. 3.

[0035] Figure 6 A flowchart of a second implementation of step S300 in a MEMS loudspeaker manufacturing process of an embodiment of the present application is shown in FIG. 4.

[0036] Figure 7 A flowchart of a MEMS loudspeaker manufacturing process of another embodiment of the present application is shown in FIG. 5. DETAILED DESCRIPTION

[0037] The present application will be further described below in conjunction with the accompanying drawings and embodiments.

[0038] In conjunction with Figures 1-3 A MEMS loudspeaker is provided, which includes a PCB board 1, a MEMS chip 2 located on one side of the PCB board 1, a conductive member 3 electrically connected between the PCB board 1 and the MEMS chip 2, and a polymer protective member 4 combined between the PCB board 1 and the MEMS chip 2 and covering the conductive member 3, the PCB board 1 and the MEMS chip 2 enclosing a first sound cavity 100, and a sound hole 11 is formed on the side of the PCB board 1 away from the MEMS chip 2 and is in communication with the first sound cavity 100.

[0039] In the present solution, the polymer protective member 4 is used to combine the PCB board 1 and the MEMS chip 2 into one, and the polymer protective member 4 covers the conductive member 3, so that the overall packaging size of the MEMS loudspeaker is basically consistent with the size of the MEMS chip 2 (the chip size / packaging size can be greater than or equal to 95%, for example, the chip is Φ4.8mm, and the packaging size can be only Φ5mm or even smaller), which can significantly improve the sensitivity parameter of the MEMS loudspeaker, the sensitivity parameter is SPL / unit packaging plane area, and the conductive member 3 is sealed and will not contact the external air, and the reliability is higher, so as to be suitable for scenes with small space and strict power consumption requirements.

[0040] Further, the MEMS loudspeaker further includes a first mesh 51 attached to the PCB board 1 and covering the sound hole 11, and a second mesh 52 attached to the side of the MEMS chip 2 away from the PCB board 1 and enclosing a second sound cavity 200 with the MEMS chip 2.

[0041] Specifically, the first mesh 51 and the second mesh 52 can be made of porous mesh material 5, such as damping mesh cloth or metal porous mesh, so that on the one hand, the THD (total harmonic distortion) performance can be better, and on the other hand, dust can be prevented from entering the first sound cavity 100 and the second sound cavity 200 and directly contacting the MEMS chip 2, and the reliability is better. Figure 1 andFigure 2 The first mesh 51 can be attached to the side of the PCB plate 1 facing the first acoustic cavity 100, i.e., the first mesh 51 is located in the first acoustic cavity 100. In combination with Figure 3 The first mesh 51 can also be attached to the side of the PCB plate 1 away from the MEMS chip 2, and at this time, the sound hole 11 can be the opening of the first acoustic cavity 100, i.e., the first mesh 51 directly covers the opening of the first acoustic cavity 100.

[0042] Further, the MEMS chip 2 has a diaphragm 21 located between the first acoustic cavity 100 and the second acoustic cavity 200, and the projection of the diaphragm 21 in the thickness direction falls within the projection of the first acoustic cavity 100, so that the diaphragm 21 is not affected by the side wall of the first acoustic cavity 100 during vibration, and the acoustic performance is better.

[0043] Further, the polymer protective piece 4 also covers the outer side of the MEMS chip 2 and the PCB plate 1, thereby isolating the MEMS chip 2 from the outside air to improve the reliability of the MEMS loudspeaker. Preferably, the polymer protective piece 4 can also cover the outer side of the second mesh 52, so that the outer circumferential surface of the MEMS chip 2 is not directly in contact with the air and is not easy to contact dust and other impurities in the air, thereby ensuring the reliability of the MEMS chip 2. When the first mesh 51 is attached to the side of the PCB plate 1 away from the MEMS chip 2, the polymer protective piece 4 can also be arranged to cover the outer side of the first mesh 51, thereby further improving the reliability of the MEMS loudspeaker.

[0044] In some embodiments, the polymer protective piece 4 can also cover the outer side of the MEMS chip 2 without covering the outer side of the PCB plate 1, and at this time, the outer circumferential surface of the polymer protective piece 4 is flush with the outer circumferential surface of the PCB plate 1, so that the amount of polymer protective material can be reduced and the cost can be reduced.

[0045] Further, in combination with Figures 4-7 A preparation process of the MEMS loudspeaker is provided for preparing the MEMS loudspeaker as above, including the following steps:

[0046] S100, positioning the PCB plate 1, the PCB plate 1 being provided with a first recess 12 on one side and a sound hole 11 penetrating through the other side and communicating with the first recess 12;

[0047] The position of the PCB plate 1 can be adjusted so that the PCB plate 1 remains horizontal and the first recess 12 faces upward. Specifically, a positioning jig can be used when positioning the PCB plate 1, and a positioning groove can be arranged on the top side of the positioning jig. The PCB plate 1 can be placed in the positioning groove of the positioning jig by manual or automatic equipment, so that the PCB plate 1 remains horizontal and the first recess 12 faces upward.

[0048] When the first mesh 51 is disposed in the first acoustic cavity 100, after positioning the PCB board 1, the first mesh 51 can be pasted on the bottom side of the first groove 12 and cover the sound hole 11, so that when the MEMS chip 2 is connected to the PCB board 1 subsequently, the first mesh 51 is located in the first acoustic cavity 100.

[0049] When the first mesh 51 is disposed outside the first acoustic cavity 100, the first mesh 51 can be pasted on the side of the PCB board 1 away from the first groove 12 and cover the sound hole 11 before positioning the PCB board 1. Of course, in some embodiments, the first mesh 51 and the PCB board 1 can also be pasted and fixed at the end.

[0050] S200, the MEMS chip 2 is inverted and electrically connected to the side of the PCB board 1 where the first groove 12 is opened, the projection of the diaphragm 21 of the MEMS chip 2 in the thickness direction falls into the first groove 12, and there is a gap between the MEMS chip 2 and the PCB board 1.

[0051] Specifically, in this step, the pad points on the top side of the PCB board 1 are coated with conductive material, and the conductive material can be silver glue, tin paste and the like.

[0052] Adjust the pose of the MEMS chip 2 so that the MEMS chip 2 is inverted and aligned with the PCB board 1, and the MEMS chip 2 is stacked on the PCB board 1; so that the contacts of the MEMS and the point-coated conductive material are in contact, at this time, a gap is formed between the MEMS chip 2 and the PCB board 1, and the height of the gap is between 1um and 300um, so that the subsequent high polymer protective material flows into and fills the gap.

[0053] Solidify the conductive material to form a conductive part 3 electrically connected between the MEMS chip 2 and the PCB board 1. The solidification of the conductive material can be achieved by reflow soldering or hot pressing, so that the formed conductive part 3 can fix and electrically connect the MEMS chip 2 and the PCB board 1, and maintain the connection stability of the MEMS chip 2 and the PCB board 1.

[0054] S300, fill the gap between the MEMS chip 2 and the PCB board 1 with a high polymer protective material and solidify it to combine the MEMS chip 2 and the PCB board 1 into one.

[0055] Combination Figure 5 And Figure 6The step can be provided with an encapsulation jig 10 on the outer periphery side of the MEMS chip 2 and the PCB board 1, and a glue filling opening is formed between the outer periphery of the MEMS chip 2 and the inner side of the encapsulation jig 10. If the polymer protective piece 4 is needed to be coated on the outer side of the PCB board 1, the glue filling opening extends to the bottom side of the PCB board 1 in the thickness direction. The side of the MEMS chip 2 away from the PCB board 1 has a second groove 22 on one side of the diaphragm 21. If the polymer protective piece 4 is needed to be coated on the outer side of the second mesh 52, the polymer protective material is filled in the gap between the MEMS chip 2 and the PCB board 1 and solidified, and before that, the second mesh 52 covering the opening of the second groove 22 is pasted on the side of the MEMS chip 2 away from the PCB board 1. At this time, the outer periphery of the MEMS chip 2 and the outer periphery of the second mesh 52 together form the glue filling opening with the inner side of the encapsulation jig 10. If the outer side of the second mesh 52 does not need to be coated with the polymer protective piece 4, the second mesh 52 covering the opening of the second groove 22 is pasted on the side of the MEMS chip 2 away from the PCB board 1 after the polymer protective material is filled in the gap between the MEMS chip 2 and the PCB board 1 and solidified.

[0056] The liquid polymer protective material is point-coated to the glue filling opening until the gap and the glue filling opening are filled, wherein the polymer protective material can be a plastic insulating material such as polyethylene terephthalate, polycarbonate, polyallylate film, etc. In the present solution, the projection of the diaphragm 21 of the MEMS chip 2 in the thickness direction falls into the first groove 12, that is, the side wall of the first groove 12 is flush with or located outside the edge of the diaphragm 21. In this way, the polymer protective material will not flow to the diaphragm 21 when filling, which will not affect the acoustic performance and is more reliable. In some embodiments, the side of the MEMS chip 2 close to the PCB board 1 or the side of the PCB board 1 close to the MEMS chip 2 can be provided with a limiting rim surrounding the first groove 12, which seals the gap towards the side of the first groove 12, thereby blocking the flow of the polymer protective material to the diaphragm 21, so that the polymer protective material will not flow to the diaphragm 21 when filling, thereby ensuring the acoustic performance of the loudspeaker.

[0057] The polymer protective material is solidified to form the polymer protective piece 4 in the gap and on the outer periphery of the MEMS chip 2, and then the MEMS loudspeaker is demolded from the encapsulation jig 10. The polymer protective piece 4 can tightly combine the MEMS chip 2 and the PCB board 1 on the one hand, and can coat the conductive piece 3 and the outer side of the MEMS chip 2 on the other hand, which can significantly improve the sensitivity parameter of the MEMS loudspeaker under the condition of reliable packaging of the MEMS chip 2.

[0058] Further, in order to improve the production efficiency of the MEMS speaker, a batch production mode can be used, and the PCB plate 1 is provided with at least two first grooves 12, and each first groove 12 is preferably arranged in a rectangular array, that is, a plurality of MEMS speaker units can be formed on a PCB plate 1 at the same time.

[0059] In combination Figure 7 When the batch production mode is used, in S100, only the whole PCB plate 1 needs to be positioned horizontally, and the first grooves 12 face upward, in S200, a corresponding MEMS chip 2 can be flip-chip bonded and fixed at a position corresponding to the first groove 12 of the PCB plate 1, in S300, only the whole PCB plate 1 with the assembled MEMS chip 2 is placed in the potting jig 10, in this way, the outer side of the MEMS chip 2 and the inner side of the potting jig 10, and the adjacent MEMS chips 2 form a mutually connected glue pouring port, and the glue pouring port and the gap between the MEMS chip 2 and the PCB plate 1 are connected, in this way, the liquid polymer protective material is point-painted to the glue pouring port, and all the MEMS chips 2 can be firmly combined on the PCB plate 1. It should be understood that in batch production, the specific process flow of each MEMS speaker unit can refer to the steps in S100-S300, which will not be repeated here.

[0060] Further, for the batch production process, after filling the gap between the MEMS chip 2 and the PCB plate 1 with the polymer protective material and solidifying, the following steps are further included:

[0061] S400, cutting the integrated MEMS chip 2 and PCB plate 1 along a preset cutting track to form at least two speaker units, the cutting mode can be laser cutting or mechanical cutting, and the preset cutting track is located between two adjacent first grooves 12. The batch production process can reduce the positioning and clamping operation steps, and significantly improve the processing efficiency of the MEMS speaker.

[0062] The above only describes the embodiments of the present application, and it should be pointed out that for those skilled in the art, improvements can be made without departing from the inventive concept, but these all belong to the protection scope of the present application.

Claims

1. A MEMS loudspeaker fabrication process, characterized in that, The method comprises the steps of: positioning a PCB board provided with a first groove on one side thereof and a sound hole passing through the other side thereof and communicating with the first groove; pointing a conductive material on a pad point on the top side of the PCB board; adjusting the pose of a MEMS chip, so that the MEMS chip is inverted and aligned with the PCB board, and the MEMS chip is stacked on the side of the PCB board where the first groove is opened; solidifying the conductive material to form a conductive part electrically connected between the MEMS chip and the PCB board, the projection of the diaphragm of the MEMS chip in the thickness direction falls entirely into the first groove, and there is a gap between the MEMS chip and the PCB board; providing a potting jig on the outer circumferential side of the MEMS chip and the PCB board, so that a potting opening communicating with the gap is formed between the circumferential side of the MEMS chip and the inner side of the potting jig; pointing a liquid polymer protective material to the potting opening until the gap and the potting opening are filled; solidifying the polymer protective material to form a polymer protective part in the gap and on the outer circumference of the MEMS chip, so that the MEMS chip and the PCB board are integrated, and the polymer protective part covers the conductive part.

2. The MEMS loudspeaker fabrication process of claim 1, wherein, The positioning of the PCB board comprises: adjusting the pose of the PCB board so that the PCB board remains horizontal and the first groove faces upward.

3. The MEMS loudspeaker fabrication process of claim 1, wherein, After the positioning of the PCB board, the method further comprises the step of: attaching a first mesh to the PCB board so that the first mesh covers the sound hole.

4. The MEMS loudspeaker fabrication process of claim 1, wherein, The height of the gap is between 1 um and 300 um.

5. The MEMS loudspeaker fabrication process of claim 1, wherein, The side of the MEMS chip away from the PCB board has a second groove on one side of the diaphragm, and before or after the step of filling the gap between the MEMS chip and the PCB board with the polymer protective material and solidifying, the method further comprises: attaching a second mesh to the side of the MEMS chip away from the PCB board to cover the opening of the second groove.

6. The MEMS loudspeaker fabrication process of any one of claims 1-5, wherein, The PCB board is provided with at least two first grooves, and after the step of filling the gap between the MEMS chip and the PCB board with the polymer protective material and solidifying, the method further comprises: cutting the integrated MEMS chip and PCB board along a preset cutting track to form at least two loudspeaker units, and the preset cutting track is located between two adjacent first grooves.

7. A MEMS loudspeaker, characterized by, The MEMS loudspeaker is made by the preparation process of any one of claims 1-6, and comprises a PCB board, a MEMS chip on one side of the PCB board, a conductive part electrically connected between the PCB board and the MEMS chip, and a polymer protective part combined between the PCB board and the MEMS chip and covering the conductive part, the PCB board and the MEMS chip enclosing a first sound cavity, and the side of the PCB board away from the MEMS chip being provided with a sound hole communicating with the first sound cavity.

8. The MEMS loudspeaker of claim 7, wherein, The MEMS speaker further comprises a first mesh attached to the PCB plate and covering the sound hole, and a second mesh attached to a side of the MEMS chip away from the PCB plate and forming a second acoustic cavity together with the MEMS chip.

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