Miniature loudspeaker structure

Abstract

The invention discloses a micro loudspeaker structure. The micro loudspeaker structure comprises a substrate, a vibrating diaphragm, a coil, a circuit board and at least one acoustic net, the substrate is provided with a hollow cavity. The vibrating diaphragm is arranged on the substrate and covers the hollow cavity. The coil is embedded in the vibrating diaphragm. The circuit board is attached to the substrate with at least one vent hole penetrating a top surface and a bottom surface of the circuit board. The acoustic mesh is disposed on the bottom surface of the circuit board to cover the vent hole. The acoustic mesh has a plurality of apertures to allow sound to pass through, and the apertures are smaller than the vent holes.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a micro speaker structure, and in particular, to a micro speaker structure with acoustic mesh. BACKGROUND

[0002] As electronic products become smaller and thinner, how to reduce the size of electronic products becomes an important issue. Micro electromechanical system (MEMS) technology is a technology that combines semiconductor processing and mechanical engineering, which can effectively reduce the size of components and manufacture multifunctional micro components and micro systems.

[0003] Manufacturing of conventional moving coil speakers is quite mature, but the size of conventional moving coil speakers is large and occupies a large space. If moving coil speakers are made on a semiconductor chip using micro electromechanical system (MEMS) manufacturing process, the size and volume of the moving coil speakers will be reduced. However, in addition to size reduction for ease of manufacturing, a micro speaker with better performance needs to be developed. For example, in recent years, the sound pressure level (SPL) performance of micro speakers in the ultrahigh frequency band (e.g., above 20 kHz) is increasingly demanding. SUMMARY

[0004] Some embodiments of the present disclosure provide a micro speaker structure, comprising: a substrate having a hollow chamber; a diaphragm disposed on the substrate and covering the hollow chamber; a coil embedded in the diaphragm; a circuit board attached to the substrate, wherein at least one air hole penetrates the top surface and the bottom surface of the circuit board; and at least one acoustic mesh disposed on the bottom surface of the circuit board to cover the at least one air hole, wherein the at least one acoustic mesh has a plurality of holes to allow sound to pass through, and the plurality of holes are smaller than the at least one air hole.

[0005] In some embodiments, each of the plurality of holes has a hole diameter greater than 0.1 μm and less than 20 μm.

[0006] In some embodiments, the plurality of holes in the at least one acoustic mesh has an average open area percentage greater than 0.1% and less than 20%.

[0007] In some embodiments, the at least one acoustic mesh comprises a plurality of acoustic meshes, and the plurality of acoustic meshes are stacked on the bottom surface of the circuit board.

[0008] In some embodiments, the plurality of acoustic meshes have the same hole diameter and the same average open area percentage.

[0009] In some embodiments, the plurality of acoustic meshes have different pore sizes and different average open area percentages.

[0010] In some embodiments, the at least one acoustic mesh comprises a plurality of acoustic meshes, and the plurality of acoustic meshes are arranged side-by-side on the bottom surface of the circuit board.

[0011] In some embodiments, the plurality of acoustic meshes have different pore sizes and different average open area percentages.

[0012] In some embodiments, the micro-speaker structure further comprises: a first permanent magnetic element disposed on the top surface of the circuit board and in the hollow chamber.

[0013] In some embodiments, the circuit board has a cavity recessed from the top surface of the circuit board, wherein the cavity is configured to accommodate the first permanent magnetic element.

[0014] In some embodiments, the at least one vent hole comprises a plurality of vent holes, and the plurality of vent holes are disposed around the first permanent magnetic element.

[0015] In some embodiments, the micro-speaker structure further comprises: a cover surrounding the substrate and the diaphragm, wherein the cover has an air opening exposing a portion of the top surface of the diaphragm.

[0016] In some embodiments, the cover is made of a metallic material having a magnetic permeability lower than 1.25 x 10 -4 H / m.

[0017] In some embodiments, the micro-speaker structure further comprises: a second permanent magnetic element disposed on the cover, wherein the second permanent magnetic element is located below or above the air opening.

[0018] In some embodiments, the coil comprises a first metal layer and a second metal layer, wherein the first metal layer has a spiral structure around a central axis of the diaphragm, and the second metal layer passes over the spiral structure of the first metal layer from above and is electrically connected to the first metal layer.

[0019] Some embodiments of the present disclosure further provide a micro-speaker structure, comprising: a substrate having a hollow chamber; a diaphragm disposed on the substrate and covering the hollow chamber; a coil embedded in the diaphragm; a circuit board attached to the substrate and having at least one vent hole, wherein the at least one vent hole is configured to allow the hollow chamber to communicate with an external environment; at least one acoustic mesh disposed on a surface of the circuit board to cover the at least one vent hole, wherein the at least one acoustic mesh has a plurality of pores to allow sound to pass, wherein each of the plurality of pores has a pore size greater than 0.1 pm and less than 20 pm; and a cover surrounding the substrate and the diaphragm, wherein the cover has an air opening exposing a portion of the top surface of the diaphragm.

[0020] In some embodiments, the average opening area percentage of the plurality of holes within the at least one acoustic mesh is greater than 0.1% and less than 20%.

[0021] In some embodiments, the miniature speaker structure further includes: a first permanent magnetic element disposed on a circuit board and in a hollow cavity; and a second permanent magnetic element disposed on a cover, wherein the first permanent magnetic element and the second permanent magnetic element are aligned in the vertical direction.

[0022] In some embodiments, the at least one acoustic mesh is disposed on the surface of the circuit board opposite to the cover.

[0023] Some embodiments of the present invention also provide a miniature loudspeaker structure, comprising: a substrate having a hollow cavity; a diaphragm disposed on the substrate and covering the hollow cavity; a coil embedded in the diaphragm; a circuit board attached to the substrate and having at least one vent hole, wherein the at least one vent hole is configured to allow the hollow cavity to communicate with the external environment; a permanent magnetic element disposed on a top surface of the circuit board facing the diaphragm and in the hollow cavity, wherein the circuit board further has a cavity recessed from the top surface of the circuit board for accommodating the permanent magnetic element; at least one acoustic mesh disposed on a surface of the circuit board to cover the at least one vent hole, wherein the at least one acoustic mesh has a plurality of holes to allow sound to pass through, wherein the aperture of each of the plurality of holes is greater than 0.1 μm and less than 20 μm; and a cover surrounding the substrate and the diaphragm, wherein the cover has an air opening that exposes a portion of the top surface of the diaphragm. Attached Figure Description

[0024] The various aspects of the invention will now be described in detail with reference to the accompanying drawings. It should be noted that, in accordance with industry standard practice, the various features are not drawn to scale and are for illustrative purposes only. In fact, the dimensions of the elements may be arbitrarily enlarged or reduced to clearly demonstrate the features of the invention.

[0025] Figure 1 A top view of a miniature speaker structure according to some embodiments;

[0026] Figure 2 For some embodiments Figure 1 A cross-sectional view of the miniature loudspeaker structure shown;

[0027] Figure 3 For some embodiments Figure 1 An enlarged view of region I shown in the diagram;

[0028] Figure 4A and Figure 4B For some embodiments Figure 1 and Figure 2Front and rear perspective views of the miniature speaker structure shown;

[0029] Figures 5A to 5G For the formation of some embodiments Figure 1 A cross-sectional view of the intermediate stage of the micro loudspeaker structure shown;

[0030] Figure 6 A cross-sectional view of a miniature loudspeaker structure including multiple acoustic nets, according to some embodiments;

[0031] Figures 7A to 7F Schematic diagrams of various arrangements of acoustic mesh and vents in some embodiments;

[0032] Figure 8A and Figure 8B A cross-sectional view of a miniature speaker structure according to some embodiments;

[0033] Figure 9 A graph showing the relationship between frequency and sound pressure level (SPL) for miniature loudspeaker structures with and without acoustic mesh.

[0034] Symbol Explanation

[0035] 10,10',10”,10”': Miniature speaker structure

[0036] 100:Substrate

[0037] 102: Diaphragm

[0038] 104: Coil / Multilayer Coil

[0039] 105: First metal layer

[0040] 105A: Spiral structure

[0041] 105B: Wave structure

[0042] 106: Second metal layer

[0043] 108: Lid

[0044] 108A: Air opening

[0045] 108B: End

[0046] 111: Opening

[0047] 112: Insulation layer

[0048] 114: Insulation layer

[0049] 130: Dielectric layer

[0050] 132: Conductive via

[0051] 140: Cutting groove

[0052] 150: Hollow cavity

[0053] 151: Vent

[0054] 160: Carrier board / Printed circuit board

[0055] 160A: Top surface

[0056] 160B: Back

[0057] 162: Cavity

[0058] 170: First permanent magnetic element

[0059] 180: Second permanent magnetic element

[0060] 190, 190-1, 190-2, 191, 192, 193, 194: Acoustics Network

[0061] I: Area

[0062] O: Central axis

[0063] X, Y, Z: Axes

[0064] AA, BB, CC: lines Detailed Implementation

[0065] The following disclosure provides numerous different embodiments or examples to implement various features of the embodiments of the present invention. Specific examples of components and configurations are described below to simplify the description of the embodiments of the present invention. Of course, these specific examples are merely illustrative and not intended to limit the embodiments of the present invention. For example, in the following description, reference to a first feature being formed on or above a second feature indicates that it may include embodiments where the first and second features are in direct contact, or embodiments where an additional feature is formed between the first and second features, so that the first and second features may not be in direct contact. Furthermore, reference numerals and / or letters may be repeated in various examples. Such repetition is for simplicity and clarity and does not in itself limit the relationship between the various embodiments and / or configurations described.

[0066] In addition, spatially related terms such as "below," "lower," "above," "higher," and similar terms may be used herein to describe the relationship between one element or feature shown in the accompanying drawings and another element(s). Besides the orientations shown in the accompanying drawings, these spatially related terms are intended to include different orientations of the device (or structure) in use or operation. The device may be rotated to different orientations (90 degrees or other orientations), and the spatially related terms used herein may be interpreted accordingly.

[0067] When terms such as "about" or "approximately" are used to describe numbers or ranges of numbers, these terms are intended to cover numbers within a reasonable range, including the described number, such as within + / - 10% of the described number or other values ​​understood by a person skilled in the art. For example, the term "about 5 μm" covers a size range from 4.5 μm to 5.5 μm.

[0068] Furthermore, the use of ordinal terms such as "first," "second," and "third" to modify elements in this invention does not imply any priority, precedence, or order of one claim element relative to another claim element, or the chronological order of their formation. Rather, they serve only as labels to distinguish one claim element with a specific name from another element with the same name (but using ordinal terms) to differentiate these claim elements.

[0069] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should be understood that each term defined in a common dictionary should be interpreted as having a meaning consistent with the background or context of the relevant art and this invention, and should not be interpreted in an idealized or overly formal manner, unless otherwise defined herein. For example, the term "permanent magnetic element" as used in this invention refers to an element capable of maintaining magnetism for a long period of time; that is, a permanent magnetic element is not easily demagnetized or magnetized. Furthermore, these permanent magnetic elements may also be referred to as "hard magnetic elements."

[0070] According to some embodiments of the present invention, a miniature loudspeaker structure is provided, wherein at least one acoustic mesh is provided on the back of a carrier plate (e.g., a printed circuit board) to cover vent holes within the carrier plate, thereby reducing the sound pressure level (SPL) drop at ultra-high frequencies (e.g., above 20 kHz), which will be described in more detail below. Therefore, the miniature loudspeaker structure (e.g., a tweeter) of the embodiments of the present invention has improved SPL performance in the ultra-high frequency range.

[0071] Figure 1 This is a top view showing a miniature speaker structure 10 according to some embodiments. The miniature speaker structure 10 is an electroacoustic transducer, such as a miniature moving-coil speaker, which can be installed in general electronic products. Figure 1 As shown, the miniature speaker structure 10 includes a substrate 100, a diaphragm 102, a (multi-layer) coil 104, a cover 108, and a carrier plate 160. It should be noted that... Figure 1In this example, to show the internal structure of the miniature speaker structure 10, the diaphragm 102 and the cover 108 are represented only by rectangular frames.

[0072] Figure 2 Illustrations based on some embodiments Figure 1 A cross-sectional view of the miniature speaker structure shown. (Reference) Figure 1 and Figure 2 A diaphragm 102 is disposed above a substrate 100 and can deform (e.g., oscillate) in the normal direction (e.g., the Z-axis direction) of the substrate 100. A coil 104 is embedded in the diaphragm 102, meaning that the coil 104 is not exposed. The coil 104 is configured to transmit electrical signals and drive the diaphragm 102 to deform relative to the substrate 100 according to the electrical signals. Currently, the resistance of commercially available loudspeakers is mostly 8Ω or 32Ω, which is lower than the resistance of a single-layer coil. The multilayer coil of the present invention can more easily meet the resistance requirements of commercially available products.

[0073] The multilayer coil 104 includes a first metal layer 105 and a second metal layer 106. The first metal layer 105 is electrically connected to the second metal layer 106 in an opening 111 of the diaphragm 102 to transmit electrical signals from a control unit (not shown) to control the operation of the miniature speaker structure 10. In some embodiments, the first metal layer 105 includes a spiral structure 105A located at the center of the diaphragm 102 and a wave structure 105B extending from the spiral structure 105A to the periphery of the diaphragm 102. The spiral structure 105A is disposed around the central axis O of the diaphragm 102, and the wave structure 105B connects the spiral structure 105A to the opening 111. By providing the wave structure 105B, the diaphragm 102 can be more flexible and the difficulty of oscillation can be reduced. In some cases, the second metal layer 106 may also include a wave structure.

[0074] Figure 3 Illustrations based on some embodiments Figure 1 An enlarged view of region I shown. (Reference) Figure 2 and Figure 3 The first metal layer 105 and the second metal layer 106 are located on different horizontal planes parallel to the XY plane, with the second metal layer 106 higher than the first metal layer 105. That is, the second metal layer 106 is closer to the top of the diaphragm 102 than the first metal layer 105. A dielectric layer 130 is disposed between the first metal layer 105 and the second metal layer 106 to prevent short circuits between them. A conductive via 132 is formed in the dielectric layer 130. The second metal layer 106 extends from above over the spiral structure 105A and is electrically connected to the first metal layer 105 through the conductive via 132.

[0075] According to some embodiments, such as Figure 2As shown, a first permanent magnetic element 170 is disposed below the diaphragm 102, and a second permanent magnetic element 180 is disposed above the diaphragm 102. The first permanent magnetic element 170 and the second permanent magnetic element 180 can attract each other to improve the frequency response of the diaphragm 102. It should be noted that, for the sake of simplicity, the figures are... Figure 1 The first permanent magnetic element 170 or the second permanent magnetic element 180 is not shown in the figure.

[0076] Continue to refer to Figure 2 The carrier plate 160 (e.g., a printed circuit board, PCB) has a vent 151, which allows the internal space of the miniature speaker structure 10 (including the rear hollow cavity 150 between the diaphragm 102 and the carrier plate 160 and the front cavity between the diaphragm 102 and the cover 108) to communicate with the external environment. The cover 108 is disposed on the carrier plate 160 and surrounds the aforementioned components for protection. The cover 108 has an air opening 108A to allow air to exit the miniature speaker structure 10, thereby generating sound. A specific appearance of the miniature speaker structure 10 according to some embodiments can be found... Figure 4A and Figure 4B .

[0077] As mentioned above, the market is currently demanding increasingly higher sound pressure level (SPL) performance from miniature loudspeakers (e.g., tweeters) in the ultra-high frequency range (e.g., above 20 kHz). A significant SPL drop has been observed between approximately 20 kHz and 40 kHz (see, for example...). Figure 9 This is caused by the Helmholtz resonance occurring at 150° in the rear hollow chamber.

[0078] To address this issue, the miniature speaker structure 10 according to some embodiments further includes an acoustic mesh 190 disposed on the back surface 160B of the support plate 160 to cover the vent hole 151, such as... Figure 2 and Figure 4B As shown in the diagram. The acoustic mesh 190 may include multiple holes (not specifically shown) to avoid obstructing air or sound, but the holes of the acoustic mesh 190 may be relatively smaller than the vent holes 151 of the carrier plate 160, for example, with a diameter of less than 20 micrometers (μm). Therefore, installing the acoustic mesh 190 is equivalent to making the carrier plate 160 have smaller vent holes, thereby reducing the resonant frequency of the rear hollow cavity 150. As a result, in the ultra-high frequency range, for example, from 20 kHz to 40 kHz, the SPL curve increases (i.e., a smaller SPL drop), as... Figure 9 As shown in the diagram. In other words, the miniature loudspeaker structure 10, including the acoustic mesh 190, achieves improved SPL performance in the ultra-high frequency range.

[0079] The following will combine Figures 5A to 5G This section will explain the detailed structure and formation method of the miniature loudspeaker structure 10.

[0080] Figures 5A to 5G The formation according to some embodiments is shown. Figure 1 The figure shows a cross-sectional view of the intermediate stage of the miniature speaker structure 10. It should be noted that each of these figures includes a section along... Figure 1 The figure shows a cross-sectional view of lines AA, BB, and CC. In this way, the manufacturing process of the different parts of the miniature speaker structure 10 can be shown in a single figure. Figures 5A to 5G Two sets of coordinate axes are provided. The left set corresponds to the sectional view along line AA, while the right set corresponds to the sectional views along lines BB and CC.

[0081] refer to Figure 5A A substrate 100 is provided. In some embodiments, the substrate 100 is part of a semiconductor wafer and may be formed of silicon (Si). Alternatively, the substrate 100 may include other semiconductor materials, such as germanium; compound semiconductors, including silicon carbide (SiC), gallium arsenide (GaAs), gallium phosphide (GaP), gallium nitride (GaN), indium phosphide (InP), and / or indium arsenide (InAs); alloy semiconductors, including SiGe, SiGeC, GaAsP, GaInAs, and / or InGaP; or combinations thereof. In some embodiments, the thickness of the substrate 100 (e.g., in the Z-axis direction) may be between about 100 μm and about 1000 μm.

[0082] Two dielectric or insulating layers 112 and 114 are formed on substrate 100, wherein insulating layer 112 is disposed between insulating layer 114 and substrate 100. Each of insulating layer 112 and insulating layer 114 comprises or is made of silicon dioxide (SiO2) or other suitable insulating material, and can be formed by thermal oxidation, chemical vapor deposition (CVD), low pressure chemical vapor deposition (LPCVD), atmospheric pressure chemical vapor deposition (APCVD), plasma-enhanced chemical vapor deposition (PECVD), or any other suitable fabrication process.

[0083] A first metal layer 105 of a multilayer coil 104 is formed on the insulating layer 114 using electroplating or other deposition processes such as physical vapor deposition (PVD), sputtering, or evaporation. The material of the first metal layer 105 includes an aluminum-silicon alloy, aluminum, copper, or any other suitable conductive material. The first metal layer 105 is then patterned using a process (e.g., including photolithography and / or etching) to produce a patterned coil 104. Figure 1 The spiral structure 105A and wave structure 105B are shown. In some embodiments, the linewidth of the first metal layer 105 may be between 1 μm and 500 μm, and the thickness of the first metal layer 105 (e.g., in the Z-axis direction) may be between 0.1 μm and 20 μm.

[0084] Subsequently, a dielectric layer 130 is conformally formed on the patterned first metal layer 105 and insulating layer 114 using furnace tube fabrication processes, CVD, or other suitable deposition processes. The dielectric layer 130 may be a carbon-doped oxide or any other suitable insulating material.

[0085] Next, in Figure 5B In this process, the dielectric layer 130 is patterned (e.g., by photolithography and / or etching) to form through holes in the dielectric layer 130, thereby exposing the underlying first metal layer 105. Then, a second metal layer 106 of the multilayer coil 104 is formed on the dielectric layer 130 and the first metal layer 105 using electroplating or other deposition processes such as PVD, sputtering, or evaporation. The material of the second metal layer 106 includes aluminum-silicon alloy, aluminum, copper, or any other suitable conductive material. The second metal layer 106 is then patterned (e.g., including photolithography and / or etching), leaving portions located on the dielectric layer 130 or within the through holes (thus forming conductive vias 132). In some embodiments, the linewidth of the second metal layer 106 may be between 1 μm and 500 μm, and the thickness of the second metal layer 106 may be between 0.1 μm and 20 μm.

[0086] It should be noted that the patterned dielectric layer 130 retains only the portion necessary for electrically insulating the first metal layer 105 and the second metal layer 106. By removing the unwanted portions of the dielectric layer 130, the diaphragm 102 (see...) Figure 5C This allows for greater flexibility, thereby improving the performance of the miniature speaker structure 10.

[0087] Next, in Figure 5CIn this configuration, a diaphragm 102 is formed on the aforementioned structure, such that the multilayer coil 104 (including a first metal layer 105 and a second metal layer 106) and the dielectric layer 130 are embedded within the diaphragm 102 (i.e., they are not exposed). The diaphragm 102 can be formed by spin coating or any other suitable fabrication process. In some embodiments, the diaphragm 102 comprises or is made of polydimethylsiloxane (PDMS), phenolic epoxy resin (e.g., SU-8), polyimide (PI), or combinations thereof. In one example, the diaphragm 102 is formed of PDMS, and the Young's modulus of the diaphragm 102 is in the range of about 1 MPa to about 100 GPa. Compared to a diaphragm formed of polyimide, the diaphragm 102 formed of PDMS has a smaller Young's modulus and a softer film structure, which allows the diaphragm 102 to have a larger displacement, thereby producing a larger sound amplitude.

[0088] Next, in Figure 5D In this embodiment, the diaphragm 102 is patterned to form a plurality of openings 111 (only one opening 111 is shown) and a cut groove 140 surrounding the diaphragm 102. In some embodiments where the diaphragm 102 is made of a photosensitive material (e.g., a photosensitive polymer material), the openings 111 and the cut groove 140 can be formed using photolithography and etching techniques. In other embodiments where the diaphragm 102 is made of a non-photosensitive material, the openings 111 and the cut groove 140 can be formed using drilling, cutting, and / or other suitable patterning techniques. The openings 111 may expose the underlying second metal layer 106 such that the first metal layer 105 is electrically connected to the second metal layer 106 in one of the openings 111 (as described above). In other words, when viewed along a vertical direction (e.g., the Z-axis direction), one of the openings 111 of the diaphragm 102 may overlap with one of the conductive vias 132. The cut groove 140 may facilitate the cutting fabrication process to separate multiple micro-speaker structures 10.

[0089] Continue to refer to Figure 5D A deep reactive ion etching process or an etching process applying an etchant (e.g., ammonium hydroxide (NH4OH), hydrofluoric acid (HF), deionized water, tetramethylammonium hydroxide (TMAH), potassium hydroxide (KOH)) is performed on the bottom surface of the substrate 100 to form a hollow cavity 150 in the substrate 100. After the etching process, the diaphragm 102 covers (e.g., is suspended) the hollow cavity 150. It should be noted that insulating layers 112 and 114 can act as etching stop layers during the etching process, thereby protecting the diaphragm 102 and the multilayer coil 104 from etching.

[0090] Next, inFigure 5E In this process, a carrier plate 160 (e.g., a printed circuit board (PCB) 160) is disposed or attached to the bottom surface of the substrate 100. Therefore, the substrate 100 is located between the carrier plate 160 and the diaphragm 102. As described above, the carrier plate 160 has one or more vent holes 151, allowing the hollow chamber 150 to communicate with the external environment. The vent holes 151 may be circular, elliptical, or any other suitable cross-sectional shape.

[0091] Additionally, a first permanent magnetic element 170 is disposed on the support plate 160 and in the hollow cavity 150. The first permanent magnetic element 170 cooperates with the upper multilayer coil 104 (i.e., the magnetic field generated by the first permanent magnetic element 170 interacts with the current flowing through the multilayer coil 104) to generate a Lorentz force (e.g., a Z-axis force) along the normal direction of the diaphragm 102 (i.e., the vertical / Z-axis direction, perpendicular to the top surface of the diaphragm 102), and the diaphragm 102 can be subjected to force to vibrate / oscillate relative to the substrate 100, thereby generating sound. In some embodiments, the first permanent magnetic element 170 may include a neodymium iron boron magnet.

[0092] In some embodiments, vent holes 151 are disposed around the (cylindrical) first permanent magnetic element 170 and are located within the hollow cavity 150 in a plan view (e.g., a top view). Any number of vent holes 151 may be present (see, for example...). Figures 7A to 7F Generally speaking, more vents 151 can improve SPL performance at high frequencies (e.g., above 1kHz).

[0093] In some embodiments, such as Figure 5E As shown, the carrier plate 160 may have a cavity 162 recessed from its top surface 160A for accommodating the first permanent magnetic element 170. This allows for the use of a larger (e.g., thicker) magnet (i.e., the first permanent magnetic element 170), which can generate a greater Lorentz force. Therefore, the performance (e.g., SPL) of the miniature speaker structure 10 is improved.

[0094] Next, in Figure 5F In this structure, a cover 108 is disposed on a support plate 160 and surrounds the substrate 100 and the diaphragm 102. The cover 108 has an air opening 108A that exposes a portion of the top surface of the diaphragm 102 to allow air to exit the miniature speaker structure 10, thereby generating sound. In some embodiments, the cover 108 may include a magnetic permeability less than about 1.25 × 10⁻⁶. -4 Metallic materials with H / m, such as gold (Au), copper (Cu), aluminum (Al), or combinations thereof.

[0095] Continue to refer to Figure 5FA second permanent magnetic element 180 is disposed above the diaphragm 102. In some embodiments, the (annular) second permanent magnetic element 180 is disposed below the end 108B of the cover 108 surrounding the air opening 108A. The second permanent magnetic element 180 and the first permanent magnetic element 170 may attract each other to increase the deflection of the planar magnetic field. Therefore, the force generated by the current through the multilayer coil 104 and the planar magnetic field in the normal direction of the diaphragm 102 increases, resulting in a higher frequency response for the diaphragm 102, thereby improving the performance of the miniature speaker structure 10. In some embodiments, the second permanent magnetic element 180 may include a neodymium iron boron magnet.

[0096] In some embodiments, the (vertical) distance between the first permanent magnetic element 170 and the second permanent magnetic element 180 can be between 200 μm and 1000 μm. If the distance between the first permanent magnetic element 170 and the second permanent magnetic element 180 is greater than 1000 μm, there may not be sufficient attraction between them to increase the deflection of the planar magnetic field, resulting in a smaller frequency response of the micro-speaker structure 10 and thus reducing the performance of the micro-speaker structure 10. Conversely, if the distance between the first permanent magnetic element 170 and the second permanent magnetic element 180 is less than 200 μm, when the diaphragm 102 deforms vertically relative to the substrate 100, it may repeatedly contact and impact the first permanent magnetic element 170 and the second permanent magnetic element 180, causing damage to the micro-speaker structure 10 and thus reducing the reliability of the micro-speaker structure 10.

[0097] Next, in Figure 5G In this process, an acoustic mesh 190 is provided on the bottom surface or back surface 160B of the support plate 160 to cover the vent hole 151 (see also...). Figure 4B The acoustic mesh 190 may comprise a material such as a fabric woven from plastic, metal, or natural fibers. An adhesive layer (not shown) may be provided to adhere the acoustic mesh 190 to the back surface 160B of the support plate 160. In some embodiments, the thickness of the acoustic mesh 190 (e.g., in the Z-axis direction) may be between about 1 mm and about 2.5 mm.

[0098] As described above, the acoustic mesh 190 may have multiple holes (not specifically shown) to avoid obstructing air or sound. The holes in the acoustic mesh 190 may be relatively smaller than the vent holes 151 of the carrier plate 160, for example, with a diameter less than 20 micrometers (μm). In some embodiments, the aperture of the acoustic mesh 190 (e.g., the cross-sectional diameter in the XY plane) may be greater than 0.1 μm and less than 20 μm. Additionally or alternatively, the average open area percentage of the acoustic mesh 190 may be greater than 0.1% and less than 20%. The average open area percentage of the acoustic mesh 190 can be obtained by dividing the total area of ​​the holes within the acoustic mesh 190 by the total area of ​​the acoustic mesh 190. If the aperture of the acoustic mesh 190 is greater than 20 μm and / or the average open area percentage is greater than 20%, the acoustic mesh 190 will have little effect on modulating the resonant frequency (or even reducing SPL drop). If the aperture of the acoustic mesh 190 is less than 0.1 μm and / or the average opening area percentage is less than 0.1%, the acoustic mesh 190 will block the passage of air or sound.

[0099] It has been found that the smaller the aperture and / or average opening area percentage of the acoustic mesh 190, the better the effect of reducing the SPL drop in the ultra-high frequency range. Therefore, different acoustic meshes 190 can be used to adjust the frequency response curve of the miniature loudspeaker structure 10 (e.g., to control the SPL drop depth in the ultra-high frequency range).

[0100] After completing the above Figures 5A to 5G The fabrication process shown can produce a miniature speaker structure 10.

[0101] Figure 6 A cross-sectional view of a miniature loudspeaker structure 10' comprising multiple acoustic meshes 190-1, 190-2 according to some embodiments is shown. Acoustic meshes 190-1 and 190-2 may be similar to the acoustic mesh 190 discussed above. In various embodiments, acoustic meshes 190-1 and 190-2 may have the same aperture and the same average opening area percentage, or may have different apertures and / or different average opening area percentages. By providing multiple acoustic meshes 190-1, 190-2 (e.g., stacked on top of each other using adhesive) on the back surface 160B of the carrier plate 160 to cover the vent holes 151 of the carrier plate 160, the SPL drop in the ultra-high frequency band can be further reduced (compared to the case of providing a single acoustic mesh). Other features of the miniature loudspeaker structure 10' are similar to those of the miniature loudspeaker structure 10 and will not be described again here.

[0102] Figures 7A to 7F Various arrangements of acoustic mesh and vents according to some embodiments are shown. Figure 7AIn the middle, two semi-circular acoustic meshes 191 and 192 (whose aperture and average opening area percentage may be the same or different) are arranged side by side (on the same horizontal plane) and cover all the vent holes 151 of the supporting plate 160. Figure 7B In the middle, four quarter-circular acoustic meshes 191, 192, 193, and 194 (whose aperture and average opening area percentage may be the same or different) are arranged side by side and cover all the vent holes 151 of the support plate 160. Figure 7C In this configuration, three elliptical acoustic meshes 191, 192, and 193 (whose aperture and average opening area percentage may be the same or different) are provided to cover all vents 151, wherein each acoustic mesh corresponds to multiple (e.g., two) vents 151. Figure 7D In this configuration, three circular acoustic meshes 191, 192, and 193 (whose aperture and average opening area percentage may be the same or different) are provided to cover all vents 151, with each acoustic mesh corresponding to one vent 151. Figure 7E In the design, some vents 151 are covered by acoustic mesh 191, 192, and 193, while some vents 151 are exposed. Figure 7F There is only one vent 151, which is covered by an acoustic net 191.

[0103] It should be understood that Figures 7A to 7F The acoustic mesh and vent configurations or arrangements shown are merely illustrative examples and are not intended to, and should not be construed as, limiting the invention. Many alternatives and modifications will be apparent to those skilled in the art once the scope of the invention is understood.

[0104] Figure 8A and Figure 8B A cross-sectional view of a miniature speaker structure (10” or 10”') according to some embodiments is shown. Figure 8A and Figure 8B In the middle, the cover 108 has an annular air opening 108A (instead of...) Figure 5G The circular air opening 108A shown is illustrated, and the second permanent magnetic element 180 is mounted (e.g., fixed) on the top center portion of the cover 180 (located below or above the top center portion). Therefore, the second permanent magnetic element 180 and the first permanent magnetic element 170 can be aligned in the vertical direction (e.g., the Z-axis direction). This helps to generate a greater Lorentz force, thereby improving the performance of the miniature speaker structure (e.g., sound pressure level (SPL)).

[0105] As described above, embodiments of the present invention provide a miniature loudspeaker structure having at least one acoustic mesh disposed on the back of a support plate to cover vent holes. With this configuration, the acoustic mesh can be used to adjust (e.g., reduce) the resonant frequency of the rear chamber of the miniature loudspeaker structure, thereby reducing the SPL drop in the ultra-high frequency range. Therefore, the miniature loudspeaker structure of the present invention has improved SPL performance in the ultra-high frequency range.

[0106] The foregoing has outlined the features of numerous embodiments, enabling those skilled in the art to better understand various aspects of the invention. Those skilled in the art will understand that other manufacturing processes and structures can be easily designed or modified based on the embodiments of the invention to achieve the same objectives and / or advantages as the embodiments described herein. Those skilled in the art will also understand that these equivalent structures do not depart from the spirit and scope of the invention. Various changes, substitutions, and modifications can be made to the embodiments of the invention without departing from the spirit and scope of the appended claims.

Claims

1. A miniature loudspeaker structure, comprising: The substrate has a hollow cavity; A diaphragm is disposed on the substrate and covers the hollow cavity; The coil is embedded in the diaphragm; A circuit board attached to the substrate, wherein at least one vent hole penetrates the top and bottom surfaces of the circuit board; as well as At least one acoustic mesh is disposed on the bottom surface of the circuit board to cover the at least one vent hole, wherein the at least one acoustic mesh has a plurality of holes to allow sound to pass through, and the holes are smaller than the at least one vent hole.

2. The micro loudspeaker structure of claim 1, wherein the aperture of each of the holes is greater than 0.1 μm and less than 20 μm.

3. The miniature speaker structure of claim 1, wherein the average opening area percentage of the holes within the at least one acoustic mesh is greater than 0.1% and less than 20%.

4. The miniature speaker structure of claim 1, wherein the at least one acoustic mesh comprises a plurality of acoustic meshes, and the acoustic meshes are stacked on top of each other on the bottom surface of the circuit board.

5. The micro loudspeaker structure of claim 4, wherein the acoustic meshes have the same aperture and the same average opening area percentage.

6. The micro loudspeaker structure of claim 4, wherein the acoustic meshes have different apertures and different average opening area percentages.

7. The miniature speaker structure of claim 1, wherein the at least one acoustic mesh comprises a plurality of acoustic meshes, and the acoustic meshes are arranged side by side on the bottom surface of the circuit board.

8. The micro loudspeaker structure of claim 7, wherein the acoustic meshes have different apertures and different average opening area percentages.

9. The miniature loudspeaker structure as described in claim 1, further comprising: A first permanent magnetic element is disposed on the top surface of the circuit board and in the hollow cavity.

10. The miniature speaker structure of claim 9, wherein the circuit board has a cavity recessed from the top surface of the circuit board, wherein the cavity is configured to accommodate the first permanent magnetic element.

11. The miniature speaker structure of claim 9, wherein the at least one vent includes a plurality of vents, and the vents are disposed around the first permanent magnetic element.

12. The miniature loudspeaker structure as described in claim 1, further comprising: A cover surrounds the substrate and the diaphragm, wherein the cover has an air opening that exposes a portion of the top surface of the diaphragm.

13. The miniature speaker structure of claim 12, wherein the cover is made of a material with a magnetic permeability of less than 1.25 × 10⁻⁶. -4 Made of metallic material with H / m.

14. The miniature loudspeaker structure as described in claim 12, further comprising: A second permanent magnetic element is disposed on the cover, wherein the second permanent magnetic element is located below or above the air opening.

15. The miniature speaker structure of claim 1, wherein the coil includes a first metal layer and a second metal layer, wherein the first metal layer has a helical structure around the central axis of the diaphragm, and the second metal layer passes over the helical structure of the first metal layer from above and is electrically connected to the first metal layer.

16. A miniature loudspeaker structure, comprising: The substrate has a hollow cavity; A diaphragm is disposed on the substrate and covers the hollow cavity; The coil is embedded in the diaphragm; A circuit board, attached to the substrate and having at least one vent hole, wherein the at least one vent hole is configured to allow the hollow chamber to communicate with the external environment; At least one acoustic mesh is disposed on the surface of the circuit board to cover the at least one vent hole, wherein the at least one acoustic mesh has a plurality of holes to allow sound to pass through, wherein the diameter of each of the holes is greater than 0.1 μm and less than 20 μm; as well as A cover surrounds the substrate and the diaphragm, wherein the cover has an air opening that exposes a portion of the top surface of the diaphragm.

17. The miniature speaker structure of claim 16, wherein the average opening area percentage of the holes within the at least one acoustic mesh is greater than 0.1% and less than 20%.

18. The miniature loudspeaker structure of claim 16, further comprising: A first permanent magnetic element is disposed on the circuit board and in the hollow cavity; as well as A second permanent magnetic element is disposed on the cover, wherein the first permanent magnetic element and the second permanent magnetic element are aligned in the vertical direction.

19. The miniature speaker structure of claim 16, wherein the at least one acoustic mesh is disposed on the surface of the circuit board opposite the cover.

20. A miniature loudspeaker structure, comprising: The substrate has a hollow cavity; A diaphragm is disposed on the substrate and covers the hollow cavity; The coil is embedded in the diaphragm; A circuit board, attached to the substrate and having at least one vent hole, wherein the at least one vent hole is configured to allow the hollow chamber to communicate with the external environment; A permanent magnetic element is disposed on the top surface of the circuit board facing the diaphragm and in the hollow cavity, wherein the circuit board also has a cavity recessed from the top surface of the circuit board for accommodating the permanent magnetic element. At least one acoustic mesh is disposed on the surface of the circuit board to cover the at least one vent hole, wherein the at least one acoustic mesh has a plurality of holes to allow sound to pass through, wherein the diameter of each of the holes is greater than 0.1 μm and less than 20 μm; as well as A cover surrounds the substrate and the diaphragm, wherein the cover has an air opening that exposes a portion of the top surface of the diaphragm.

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