Ultrahigh-sensitivity MEMS loudspeaker and production process of coil

Abstract

The ultrahigh-sensitivity MEMS loudspeaker comprises a shell and a circuit board arranged at the bottom of the shell, an upper magnetic circuit and a lower magnetic circuit which are distributed up and down are arranged in a cavity formed by the shell and the circuit board, bonding pads are distributed on the lower magnetic circuit, a supporting ring used for welding the positive electrode and the negative electrode of a coil lead is arranged on the lower magnetic circuit, and a vibration system is arranged on the supporting ring. The mode of combining the coil and the vibration film is adopted, the semiconductor technology is utilized, the coil is made into multiple layers, the semiconductor printer and the micro-electro-mechanical casting mold technology are adopted, conductive silver paste is attached to the vibration film to form the coil, due to the fact that the line width and the thickness of the coil in the semiconductor technology are within 10 micrometers, the coil can be attached to multiple layers, and the more the layers are, the more the layers are. The longer the coil length is, the higher the sensitivity of the loudspeaker is by more than 3db, the thickness of the MEMS loudspeaker can be 1.0 mm through the multi-layer coil made through the semiconductor technology, and the product sensitivity is 50% higher than that of a traditional MEMS.

Description

Technical Field

[0001] The present invention relates to the technical field of loudspeakers, and in particular to a production process of an ultra-high-sensitivity MEMS loudspeaker and a coil. Background Art

[0002] Traditional MEMS speakers mostly use the principle of piezoelectric vibration, but require a driving voltage of more than 1V, so MEMS speakers need additional power amplifier chips, which will increase the cost on the one hand and increase the power consumption of MEMS speakers on the other. Summary of the invention

[0003] The purpose of the present invention is to provide a production process of an ultra-high-sensitivity MEMS speaker and a coil, thereby solving the problems in the prior art.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A super-sensitive MEMS loudspeaker comprises a shell and a circuit board arranged at the bottom of the shell, wherein an upper magnetic circuit and a lower magnetic circuit distributed up and down are arranged in a chamber formed by the shell and the circuit board, and a support ring with welding pads distributed thereon and used for welding positive and negative electrodes of coil leads is arranged on the lower magnetic circuit, and a vibration system is arranged on the support ring.

[0006] Furthermore, the vibration system includes a vibration film and a coil insulation layer group, a coil insulation layer group is arranged on the vibration film, the thickness of the vibration film is 2um to 50um, the coil insulation layer group includes insulation layer one, insulation layer two and insulation layer three, insulation layer one, insulation layer two and insulation layer three are arranged from bottom to top, and the insulation layer one, insulation layer two and insulation layer three are UV positive photoresist.

[0007] Furthermore, the coil insulation layer group includes coil one, coil two, coil three and coil four, coil one is arranged on the vibration film, insulating layer one is arranged between coil one and coil two, insulating layer two is arranged between coil two and coil three, insulating layer three is arranged between coil three and coil four, and the material of coil one, coil two, coil three and coil four is conductive silver paste.

[0008] Furthermore, the vibration film is made of a material that is flexible and capable of semiconductor etching grooves, and the shape of the vibration film is circular, square or racetrack.

[0009] Furthermore, the upper magnetic circuit and the lower magnetic circuit both include an inner magnet and an outer magnet, the inner magnet is arranged in the center of the outer magnet, the upper magnetic circuit is located above the support ring, and the lower magnetic circuit is located below the support ring. The magnet material of the upper magnetic circuit and the lower magnetic circuit is NdFeB, the magnet shape is round or square, and the shape of a runway, and the magnetic properties of the inner magnet and the outer magnet are opposite.

[0010] The production process of the ultra-high sensitivity MEMS speaker coil is used to produce the ultra-high sensitivity MEMS speaker coil, comprising the following steps:

[0011] Firstly, a coil 1 is attached to the vibration film, and an insulating layer 1 is coated on the surface of the coil 1;

[0012] After the insulating layer 1 is applied to the surface of coil 1, coil 2 is laid, and after coil 2 is laid, insulating layer 2 is attached, and so on, with the insulating layer and coil spaced apart.

[0013] Furthermore, one of the contacts of coil one extends out of insulating layer one and is not coated, and the contact is welded to one of the pads, and another contact of coil one and the contacts of coils two, three and four are not coated.

[0014] Furthermore, the method of attaching the vibrating film to the coil includes:

[0015] Through the semiconductor micron-level silk-screen circuit technology, liquid conductive silver paste is coated on the vibration film according to the designed shape, and a gap of 1um-10um is reserved between the circuits of the insulating layer to prevent short circuit.

[0016] Furthermore, the method of attaching the vibrating film to the coil includes:

[0017] The shape of the insulating layer circuit is made into a mold through micro-electromechanical casting technology, and then the conductive silver paste is poured on the vibration film.

[0018] Furthermore, the conduction method between the coil 1, the coil 2, the coil 3 and the coil 4 is as follows:

[0019] Another contact of coil one is connected to a contact of coil two, another contact of coil two is connected to a contact of coil three, another contact of coil three is connected to a contact of coil four, and another contact of coil four is welded to another pad.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention adopts a combination of coils and vibration films, and uses semiconductor technology to make the coils into multiple layers with a thickness of less than 0.1 mm. A semiconductor printer and micro-electromechanical casting mold technology are used to attach conductive silver paste to the vibration film to form a coil. Since the line width and thickness of the coils made by the semiconductor process are within 10 um, the coils can be attached with multiple layers. The more layers there are, the longer the coil length is. According to the Lorentz force F=BIL, the coil length L doubles and F doubles, so the sensitivity of the speaker will be more than 3 db higher. The thickness of the multi-layer coils made by semiconductor technology can be as high as 1.0 mm, and the product sensitivity is 50% higher than that of traditional MEMS. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the assembly of the MEMS speaker of the present invention;

[0023] Figure 2 An exploded schematic diagram of the MEMS speaker of the present invention;

[0024] Figure 3 is a cross-sectional view of a MEMS speaker of the present invention;

[0025] Figure 4 for Figure 3 A magnified image of point A;

[0026] In the figure: 1. outer shell; 2. circuit board; 3. support ring; 4. vibration film; 5. insulation layer 1; 6. insulation layer 2; 7. insulation layer 3; 8. coil 1; 9. coil 2; 10. coil 3; 11. coil 4; 12. inner magnet; 13. outer magnet. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] See also Figure 1-Figure 3 A super-sensitive MEMS speaker comprises a shell 1 and a circuit board 2 arranged at the bottom of the shell 1. An upper magnetic circuit and a lower magnetic circuit distributed up and down are arranged in a chamber formed by the shell 1 and the circuit board 2. The upper magnetic circuit is fixedly installed on the shell 1. The upper magnetic circuit is more than 10um away from the coil, which is convenient for the vibration of the vibration film 4. The lower magnetic circuit is fixed on the circuit board 2. The lower magnetic circuit is also more than 10um away from the coil. A support ring 3 with pads distributed on it and used for welding the positive and negative poles of the coil lead is arranged on the lower magnetic circuit. A vibration system is arranged on the support ring 3, and the support ring 3 is used to support the vibration film 4.

[0029] See also Figure 2 The vibration system includes a vibration film 4 and a coil insulation layer group. A coil insulation layer group is arranged on the vibration film 4. The thickness of the vibration film 4 is 2um to 50um. The thinner the thickness, the better the low-frequency performance. The coil insulation layer group includes an insulation layer 1 5, an insulation layer 2 6 and an insulation layer 3 7. The insulation layer 1 5, the insulation layer 2 6 and the insulation layer 3 7 are arranged from bottom to top. The insulation layer 1 5, the insulation layer 2 6 and the insulation layer 3 7 are highly insulating UV positive photoresists containing photosensitive resins and solvents (propylene glycol methyl ether acetate).

[0030] See also Figure 2 The coil insulation layer group includes coil one 8, coil two 9, coil three 10 and coil four 11. Coil one 8 is arranged on the vibration film 4. An insulating layer one 5 is arranged between coil one 8 and coil two 9, an insulating layer two 6 is arranged between coil two 9 and coil three 10, and an insulating layer three 7 is arranged between coil three 10 and coil four 11. The material of coil one 8, coil two 9, coil three 10 and coil four 11 is conductive silver paste. Each layer of coils is separated by an insulating layer in the middle to prevent short circuit. The shape of the coil is round or square, runway shape, etc. The coil of this embodiment is round. The width of coil one 8, coil two 9, coil three 10 and coil four 11 is 1um~10um, and the depth is 1um~20um.

[0031] The number of coil layers shown in the present invention is 4 layers, and it can also be set to a single layer or stacked with more layers of coils. The number can be adjusted according to actual conditions and can be more. Correspondingly, the number of insulating layers changes with the number of coil layers. The advantage of multi-layer coils is that the magnetic field force is stronger and the sensitivity is higher.

[0032] The vibration film 4 diaphragm material is selected to have a certain degree of flexibility, and can be semiconductor etched grooves (such as Figure 4 a, a conductive silver paste is coated in the groove to form a coil) material, such as polyethylene terephthalate (PET), polydimethylsiloxane (PDMS), polyimide (PI), etc., the vibration film 4 is in the shape of a circle, a square or a runway. The vibration film 4 of this embodiment is in the shape of a circle.

[0033] The upper magnetic circuit and the lower magnetic circuit both include an inner magnet 12 and an outer magnet 13. The inner magnet 12 is arranged in the center of the outer magnet 13. The upper magnetic circuit is located above the support ring 3, and the lower magnetic circuit is located below the support ring 3. The magnets of the upper magnetic circuit and the lower magnetic circuit are made of permanent magnets such as neodymium iron boron. The magnets are round or square, runway-shaped, and the magnetic properties of the inner magnet 12 and the outer magnet 13 are opposite.

[0034] The present invention shows a dual magnetic circuit structure, but a single magnetic circuit structure can also be adopted, that is, only an upper magnetic circuit or only a lower magnetic circuit is provided, but the performance of the dual magnetic circuit is 50% higher than that of the single magnetic circuit.

[0035] The production process of ultra-high sensitivity MEMS speaker coils includes the following steps:

[0036] First, a coil 8 is attached to the vibration film 4, and an insulating layer 5 is coated on the surface of the coil 8;

[0037] After the insulating layer 1 5 is applied on the surface of the coil 1 8 , the coil 2 9 is laid, and after the coil 2 9 is laid, the insulating layer 2 6 is attached, and so on, with the insulating layer and the coil being spaced apart.

[0038] One of the contacts of coil 1 8 extends out of the insulating layer 1 5 and is not coated. The contact is welded to one of the pads. The other contact of coil 1 8 and the contacts of coil 2 9 , coil 3 10 and coil 4 11 are not coated.

[0039] The conduction method between coil 1 8, coil 2 9, coil 3 10 and coil 4 11 is as follows:

[0040] The contact at the other end of coil one 8 is connected to the contact at one end of coil two 9, the contact at the other end of coil two 9 is connected to the contact at one end of coil three 10, the contact at the other end of coil three 10 is connected to the contact at one end of coil four 11, and the contact at the other end of coil four 11 is welded to another pad, so that coil one 8, coil two 9, coil three 10 and coil four 11 are connected in series to form a conductive loop, so that the current direction of all coils is the same, so that the direction in which the coils are acted upon by the magnetic field force will also be consistent.

[0041] Embodiment 1: A method for attaching a coil 8 to a vibration film 4 includes:

[0042] Through the semiconductor micron-level screen printing circuit technology, liquid conductive silver paste is coated on the vibration film 4 according to the designed shape, and a gap of 1um-10um is reserved between the circuits of the insulating layer 5 to prevent short circuit.

[0043] Embodiment 2: A method for attaching a coil 8 to a vibrating film 4 includes:

[0044] By applying a variety of micro-nano principles, the shape of the insulating layer circuit is made into a mold through micro-electromechanical casting technology. Micro-electromechanical casting technology can reduce the traditional casting by one million times. The circuit shape is made into a mold, and then the conductive silver paste is poured on the vibration film 4. Since it is a one-time molding, the efficiency is higher.

[0045] Working principle: The magnetic properties of the opposite surfaces of the upper and lower magnetic circuits are the same, and the directions of the magnetic lines of force of the upper and lower magnetic circuits are both from N to S. The coil is placed in the middle of the upper and lower magnetic circuits. After the four upper and lower layered coils are connected in series through contacts, when the coils are energized, since the directions of the coil currents are the same, the directions in which the coils are acted upon by the magnetic field forces will also be the same. The vibration film 4 is driven to vibrate up and down by the upper and lower magnetic fields and make sounds.

[0046] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An ultra-high-sensitivity MEMS loudspeaker, comprising a housing (1) and a circuit board (2) arranged at the bottom of the housing (1), characterized in that: An upper magnetic circuit and a lower magnetic circuit are arranged in a chamber formed by the housing (1) and the circuit board (2), and the lower magnetic circuit is provided with a support ring (3) having solder pads distributed thereon and used for soldering the positive and negative poles of the coil lead wires, and a vibration system is arranged on the support ring (3).

2. The ultra-high sensitivity MEMS speaker according to claim 1, characterized in that: The vibration system comprises a vibration film (4) and a coil insulation layer group, wherein the coil insulation layer group is arranged on the vibration film (4), the thickness of the vibration film (4) is 2um to 50um, the coil insulation layer group comprises an insulation layer 1 (5), an insulation layer 2 (6) and an insulation layer 3 (7), the insulation layer 1 (5), the insulation layer 2 (6) and the insulation layer 3 (7) are arranged from bottom to top, and the insulation layer 1 (5), the insulation layer 2 (6) and the insulation layer 3 (7) are UV positive photoresist.

3. The ultra-high sensitivity MEMS speaker according to claim 2, characterized in that: The coil insulation layer group comprises coil one (8), coil two (9), coil three (10) and coil four (11); coil one (8) is arranged on the vibration film (4); an insulation layer one (5) is arranged between coil one (8) and coil two (9); an insulation layer two (6) is arranged between coil two (9) and coil three (10); an insulation layer three (7) is arranged between coil three (10) and coil four (11); and the material of coil one (8), coil two (9), coil three (10) and coil four (11) is conductive silver paste.

4. The ultra-high sensitivity MEMS speaker according to claim 1, characterized in that: The vibration film (4) is made of a material that is flexible and capable of forming semiconductor etching grooves. The vibration film (4) is in the shape of a circle, a square or a racetrack.

5. The ultra-high sensitivity MEMS speaker according to claim 1, characterized in that: The upper magnetic circuit and the lower magnetic circuit both comprise an inner magnet (12) and an outer magnet (13); the inner magnet (12) is arranged at the center of the outer magnet (13); the upper magnetic circuit is located above the support ring (3); and the lower magnetic circuit is located below the support ring (3); the magnets of the upper magnetic circuit and the lower magnetic circuit are made of neodymium iron boron; the magnets are round or square, in a racetrack shape; and the inner magnet (12) and the outer magnet (13) have opposite magnetic properties.

6. A process for producing an ultra-high sensitivity MEMS speaker coil, used for producing the ultra-high sensitivity MEMS speaker coil according to any one of claims 1 to 5, characterized in that: The steps include: First, a coil (8) is attached to the vibration film (4), and an insulating layer (5) is coated on the surface of the coil (8) by coating. After the insulating layer 1 (5) is coated on the surface of the coil 1 (8), the coil 2 (9) is laid, and after the coil 2 (9) is laid, the insulating layer 2 (6) is attached, and so on, with the insulating layer and the coil spaced apart.

7. The production process of the ultra-high sensitivity MEMS speaker coil according to claim 6, characterized in that: One of the contacts of coil one (8) extends out of insulating layer one (5) and is not coated. The contact is welded to one of the pads. The other contact of coil one (8) and the contacts of coil two (9), coil three (10) and coil four (11) are not coated.

8. The production process of the ultra-high sensitivity MEMS speaker coil according to claim 6, characterized in that: The method of attaching the vibrating film (4) to the coil 1 (8) comprises: Through the semiconductor micron-level screen printing circuit technology, liquid conductive silver paste is coated on the vibration film (4) according to the designed shape, and a gap of 1um-10um is reserved between the circuits of the insulating layer (5) to prevent short circuit.

9. The production process of the ultra-high sensitivity MEMS speaker coil according to claim 6, characterized in that: The method of attaching a coil 1 (8) to a vibrating film (4) comprises: The insulating layer circuit shape is made into a mold through micro-electromechanical casting technology, and then the conductive silver paste is poured on the vibration film (4).

10. The production process of the ultra-high sensitivity MEMS speaker coil according to claim 1, characterized in that: The conduction method between the coil 1 (8), the coil 2 (9), the coil 3 (10) and the coil 4 (11) is as follows: Another contact of coil one (8) is connected to a contact of coil two (9), another contact of coil two (9) is connected to a contact of coil three (10), another contact of coil three (10) is connected to a contact of coil four (11), and another contact of coil four (11) is welded to another pad.

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