Laminated microphone

Abstract

The utility model discloses a laminated microphone, and relates to the technical field of audio input equipment, the laminated microphone comprises an upper layer plate, a middle layer plate and a lower layer plate, the upper layer plate is provided with pickup holes and is integrated with pickup elements, and the pickup elements and the pickup holes are arranged at intervals; the middle-layer plate is laminated and connected to one side of the upper-layer plate, and the middle-layer plate is provided with a hollow cavity for accommodating the pickup element; the lower-layer plate is connected to one side, back to the upper-layer plate, of the middle-layer plate in a laminated manner, the lower-layer plate is provided with at least two pin bonding pads, and the two pin bonding pads are arranged at intervals and are electrically connected with the pickup element. According to the technical scheme provided by the utility model, the boundary dimension of the microphone is reduced, thereby adapting to the frameless design of electronic products.

Description

TECHNICAL FIELD

[0001] The utility model relates to audio input device technical field, especially relate to a stacked board microphone. BACKGROUND

[0002] With the rapid development of audio technology, especially the rise of frameless design in the notebook computer market, the microphone as the key audio input device, its size and performance have been unprecedented attention. The microphone plays an indispensable role in smart devices, professional recording, conference systems and many other fields, but the current microphone products on the market still have many deficiencies.

[0003] The packaging mode of the existing microphone is relatively simple, usually using LGA or QFN packaging form, that is, the MEMS chip and ASIC chip are fixed on the bottom layer circuit board through glue, and then the metal wire is used to realize the electrical signal connection between the chip and the circuit board, and the welding metal shell shielding cover or epoxy resin package is formed to form a sensor component suitable for SMT patch production. This packaging mode makes the microphone form a larger size, which not only affects the appearance and integration of the equipment, but also limits its application in space limited scenes. SUMMARY

[0004] The main purpose of the utility model is to provide a stacked board microphone, which aims to reduce the size of the microphone, so as to adapt to the frameless design of electronic products.

[0005] In order to achieve the above purpose, the utility model provides a stacked board microphone, which comprises:

[0006] The upper layer plate is provided with a sound pickup hole and an integrated sound pickup element, and the sound pickup element is arranged in the sound pickup hole.

[0007] The middle layer plate is connected to one side of the upper layer plate, and the middle layer plate has a hollow cavity for accommodating the sound pickup element.

[0008] The lower layer plate is connected to the side of the middle layer plate away from the upper layer plate, and the lower layer plate is provided with at least two pin pads, two pin pads are arranged in the sound pickup element.

[0009] In an embodiment, one side of the upper layer plate is sequentially stacked with a top layer copper foil and a first solder resist layer, the pickup element is arranged on the side of the first solder resist layer away from the top layer copper foil; the first solder resist layer has a first exposed hole, a second exposed hole and a third exposed hole, the first exposed hole and the second exposed hole are arranged adjacent to the pickup hole, and the third exposed hole is arranged coincident with the pickup hole; the first exposed hole is used to expose one end of the top layer copper foil, the second exposed hole is used to expose the other end of the top layer copper foil, and the second exposed hole is provided with an upper layer pad, the upper layer pad is connected with the top layer copper foil and the pin pad; the pickup element is connected with one end of the top layer copper foil through the first exposed hole.

[0010] In an embodiment, the top layer copper foil comprises:

[0011] a first copper foil body arranged on one side of the upper layer plate; and

[0012] a plurality of first copper foil strips arranged on one side of the upper layer plate, and the plurality of first copper foil strips are arranged side by side and adjacent to the first copper foil body; the first exposed hole is used to expose one end of the plurality of first copper foil strips;

[0013] the first solder resist layer is provided with a plurality of second exposed holes, each of the second exposed holes is used to expose the other end of a first copper foil strip.

[0014] In an embodiment, the side of the first solder resist layer away from the top layer copper foil is stacked with a grounding layer, and the grounding layer is provided with a clearance hole, and the pickup element is located at the clearance hole.

[0015] In an embodiment, the top layer copper foil further comprises a first annular copper foil connected with the first copper foil body and enclosing the first copper foil body to form an enclosed area for connecting external circuits; and the plurality of first copper foil strips are located in the enclosed area.

[0016] In an embodiment, the third exposed hole has a diameter greater than that of the pickup hole, a copper exposing ring is arranged in the third exposed hole, the copper exposing ring is connected with the top layer copper foil and exposes the pickup hole, and is used to release static electricity.

[0017] In an embodiment, the cavity wall of the hollow cavity is covered with a metal layer, and the metal layer is used for grounding connection and electromagnetic shielding.

[0018] In an embodiment, the middle layer plate is provided with a mounting plate located on one side of the hollow cavity, and the mounting plate is provided with at least one middle layer pad connected with the pickup element and the pin pad to electrically connect the pickup element with the pin pad.

[0019] In an embodiment, a side of the lower layer plate facing the middle layer plate is sequentially stacked with a lower layer copper foil and a second solder resist layer, the second solder resist layer is provided with six exposure holes, and the six exposure holes are arranged in an array; each of the exposure holes is used for exposing the lower layer copper foil.

[0020] In an embodiment, the lower layer copper foil comprises:

[0021] at least six copper foil blocks, the six copper foil blocks are arranged in two columns on the lower layer plate; each of the exposure holes is used for one of the copper foil blocks; and

[0022] at least two second copper foil strips, each of the second copper foil strips is connected with one of the copper foil blocks, and the two second copper foil strips are located between the two columns of the copper foil blocks; each of the second copper foil strips is provided with the pin pad at an end away from the copper foil block;

[0023] and / or, a shape of one of the copper foil blocks is different from shapes of the remaining copper foil blocks, and is used as a pin mark point.

[0024] The technical scheme of the utility model discloses a stacked plate microphone, which comprises an upper layer plate, a middle layer plate and a lower layer plate, the upper layer plate is provided with a sound pickup hole and an integrated sound pickup element, and the sound pickup element is arranged in an array with the sound pickup hole; the middle layer plate is connected to one side of the upper layer plate in a stacked manner, and the middle layer plate has a hollow cavity for accommodating the sound pickup element; the lower layer plate is connected to one side of the middle layer plate away from the upper layer plate in a stacked manner, and the lower layer plate is provided with at least two pin pads, the two pin pads are arranged in an array, and are electrically connected with the sound pickup element. The three-layer stacked structure of the upper layer plate, the middle layer plate and the lower layer plate is arranged separately, and the sound pickup element and the pin pad are integrated separately, that is, the planar layout of the traditional LGA package is converted into a three-dimensional integration, so that the width of the stacked plate microphone is reduced, the equipment integration is improved significantly, and the electronic product with the stacked plate microphone is realized narrow frame design effect. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical scheme in the embodiments of the utility model or the prior art, the drawings needed to be used in the following embodiment or prior art description will be briefly introduced, and obviously, the drawings in the following description are only some embodiments of the utility model, and for those skilled in the art, other drawings can be obtained from the structure shown in the drawings without creative labor.

[0026] Figure 1 The structure explosion drawing of the stacked plate microphone provided by the utility model is shown in the drawings.

[0027] Figure 2 The structure schematic view of the top layer copper foil of the stacked plate microphone provided by the utility model is shown in the drawings.

[0028] Figure 3 The structure schematic view of the top layer copper foil and the first solder resist layer of the stacked plate microphone provided by the utility model is shown in the figure;

[0029] Figure 4 The structure schematic view of the middle layer plate of the stacked plate microphone provided by the utility model is shown in the figure;

[0030] Figure 5 The structure schematic view of the lower layer copper foil of the stacked plate microphone provided by the utility model is shown in the figure;

[0031] Figure 6 The structure schematic view of the lower layer copper foil and the second solder resist layer of the stacked plate microphone provided by the utility model is shown in the figure.

[0032] Explanation of the reference signs:

[0033] 10, upper layer plate;10a, pickup hole;11, pickup element;12, top layer copper foil;121, first copper foil main body;122, first copper foil strip;123, first annular copper foil;13, first solder resist layer;13a, first exposed hole;13b, second exposed hole;13c, third exposed hole;14, ground layer;15, upper layer pad;16, copper exposed ring;20, middle layer plate;20a, hollow cavity;21, mounting plate;22, middle layer pad;30, lower layer plate;31, foot pad;32, lower layer copper foil;321, copper foil block;322, second copper foil strip;33, second solder resist layer;33a, exposed hole.

[0034] The implementation, functional features and advantages of the utility model will be further described with reference to the accompanying drawings in combination with the embodiments. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the utility model.

[0036] It should be noted that if the embodiments of the utility model involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement condition, etc. between the components in a certain posture, and if the certain posture changes, the directional indications will also change accordingly.

[0037] In addition, if the description of "first", "second" and the like is involved in the embodiments of the utility model, the description of "first", "second" and the like is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can be explicitly or implicitly included at least one feature. In addition, if "and / or" or "and / or" appears throughout the text, it means that the three parallel schemes are included, for example, "A and / or B" includes A scheme, or B scheme, or A and B scheme. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the realization of ordinary skilled in the art, when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, also not within the protection scope required by the utility model.

[0038] The utility model provides a kind of folded plate microphone.

[0039] Please refer to Figures 1 to 6 In an embodiment of the utility model, the folded plate microphone includes upper layer plate 10, middle layer plate 20 and lower layer plate 30, upper layer plate 10 is provided with pickup hole 10a and is integrated with pickup element 11, and pickup element 11 is arranged at intervals with pickup hole 10a;Middle layer plate 20 is connected to one side of upper layer plate 10 in stack, and middle layer plate 20 has hollow cavity 20a accommodating pickup element 11;Lower layer plate 30 is connected to the side of middle layer plate 20 away from upper layer plate 10 in stack, and lower layer plate 30 is provided with at least two pin pads 31, two pin pads 31 are arranged at intervals and are electrically connected with pickup element 11.

[0040] Upper layer plate 10 is top plate, and pickup hole 10a is set by high-precision laser process. Pickup element 11 is integrated on the surface of upper layer plate 10, including MEMS sensor chip and ASIC amplifier chip, and the two are fixed on the surface of upper layer plate 10 by flip soldering process. By gold wire bonding technology, the chip and the circuit pad of upper layer plate 10 are electrically connected to form the core module of acoustoelectric conversion function. Pickup hole 10a and pickup element 11 are designed to be asymmetrically arranged at intervals, which not only ensures uniform collection of sound signals, but also avoids signal interference caused by sound wave reflection.

[0041] Middle layer plate 20 is below upper layer plate 10, and the central region is provided with hollow cavity 20a for accommodating pickup element 11 of upper layer plate 10. The cavity structure of middle layer plate 20 optimizes the utilization rate of internal space to ensure the stability of the structure under narrow frame.

[0042] The lower layer plate 30 is a bottom plate, the thickness is consistent with the upper layer plate 10, at least two foot pads 31 are arranged on the surface, including power supply (VDD), data output (DATA). The lower layer plate 30 is welded with the main plate through tin paste printing, signal output and external circuit integration are realized through the reflow process. The pad layout adopts differential signal wiring design, reduces signal crosstalk, and is conducted with the pad of the middle layer plate 20 through a via, and a complete signal transmission link is formed.

[0043] The utility model discloses a three-layer stacking structure of separately arranging upper layer plate 10, middle layer plate 20 and lower layer plate 30, and the components such as pickup element 11, foot pad 31 are integrated separately, that is, the plane layout of traditional LGA package is converted into three-dimensional integration, so that the width of the stacked plate microphone is reduced, the equipment integration is improved significantly, and then the electronic product with the stacked plate microphone is realized narrow frame design effect.

[0044] Meanwhile, the stacked plate microphone adopts symmetrical wiring design between the multiple layer plates, ensures impedance matching of the signal transmission path, and the sensitivity difference is controlled within ±1dB. In the multi-microphone array system, the phase consistency error of each unit is less than 2°, the sound source positioning accuracy and beamforming effect are improved significantly, and the stacked plate microphone is suitable for high-precision scenes such as intelligent sound boxes and conference systems.

[0045] Optionally, the material of the middle layer plate 20 adopts high-frequency low-loss base material, reduces high-frequency attenuation in signal transmission, and improves the frequency response range to 20Hz-20kHz. Graphene composite material is embedded in the grounding layer 14, further improving the thermal conductivity, and being suitable for high-temperature environment (such as vehicle-mounted equipment).

[0046] Optionally, a flexible circuit interface (FPC) is additionally arranged at the edge of the lower layer plate 30, supports modular disassembly and multi-angle installation, and is suitable for the curved structure requirement of wearable equipment.

[0047] Optionally, a nano-hydrophobic coating is added outside the pickup hole 10a, and IP67 level protection is realized through a silica gel sealing ring, and outdoor application scenarios are expanded.

[0048] Optionally, the ASIC chip and the MEMS sensor adopt heterogeneous packaging (such as SiP system-in-package), further reduce the chip spacing, and optimize the signal transmission path.

[0049] In an embodiment, please refer to Figures 1 to 3The top layer copper foil 12 is a core conductive layer of the upper layer board 10, adopts a high-precision etching process to form a circuit trace, and is distributed in a radial manner with the pickup hole 10a as a center. The two ends of the copper foil are exposed through the first exposed hole 13a and the second exposed hole 13b, and are directly connected with the pickup element 11 and the lower layer foot pad 31, thereby avoiding the redundant intermediate transition pad in the traditional design and significantly shortening the signal transmission path.

[0050] The top layer copper foil 12 is a core conductive layer of the upper layer board 10, adopts a high-precision etching process to form a circuit trace, and is distributed in a radial manner with the pickup hole 10a as a center. The two ends of the copper foil are exposed through the first exposed hole 13a and the second exposed hole 13b, and are directly connected with the pickup element 11 and the lower layer foot pad 31, thereby avoiding the redundant intermediate transition pad in the traditional design and significantly shortening the signal transmission path.

[0051] The first solder mask layer 13 covers the surface of the top layer copper foil 12 and adopts a photosensitive ink material to set the following key exposed holes through a photoetching process. The first exposed hole 13a is arranged adjacent to the edge of the pickup hole 10a and is used to expose one end of the top layer copper foil 12 and directly bond with the signal input pin of the pickup element 11. The second exposed hole 13b exposes the other end of the top layer copper foil 12 and integrates the upper layer pad 15, which is connected with the foot pad 31 (such as VDD, GND) of the lower layer board 30 through a vertical via. The third exposed hole 13c is coaxially arranged with the pickup hole 10a and serves as a channel for sound waves to enter.

[0052] The first exposed hole 13a and the second exposed hole 13b of the embodiment are arranged adjacent to the pickup hole 10a, thereby reducing the horizontal space occupied compared with the traditional dispersed pad layout. The vertical direct connection between the upper layer pad 15 and the lower layer foot pad 31 eliminates the horizontal signal trace.

[0053] Optionally, the upper layer pad 15 is embedded in the solder mask layer and is connected with the lower layer board 30 through a copper column bump, thereby reducing the vertical height occupation.

[0054] The embodiment compresses the width of the stacked board microphone to an industry-leading level through the collaborative design of the top layer copper foil 12 and the solder mask layer, and satisfies the stringent requirements of ultra-thin terminals such as smart phones, AR / VR devices and the like.

[0055] In an embodiment, please refer to Figures 1 to 3The top layer copper foil 12 includes a first copper foil body 121 and a plurality of first copper foil strips 122. The first copper foil body 121 is arranged on one side of the upper layer board 10. The plurality of first copper foil strips 122 are arranged on one side of the upper layer board 10, and are arranged side by side and adjacent to the first copper foil body 121. The first exposed hole 13a is used to expose one end of the plurality of first copper foil strips 122. The first solder resist layer 13 is provided with a plurality of second exposed holes 13b. Each second exposed hole 13b is used to expose the other end of a first copper foil strip 122.

[0056] The first copper foil body 121 is located on one side of the upper layer board 10 as a core conductive layer, and the coverage area accounts for 60% to 70% of the effective area of the upper layer board 10. The shape is rectangular or special-shaped (such as L-shaped), and the edge is processed by a micron-level chamfering process to reduce signal reflection loss.

[0057] The plurality of first copper foil strips 122 are arranged side by side on one side of the first copper foil body 121, and the number is 4 to 8. One end of each copper foil strip is exposed through the first exposed hole 13a and directly bonded with the signal input pin of the pickup element 11. The other end is exposed through the second exposed hole 13b and connected to the foot pad 31 (such as VDD, DATA, CLOCK, etc.) of the lower layer board 30. The copper foil strip adopts a serpentine layout design, uses spatial curvature to extend the effective path length, avoids signal crosstalk, and at the same time minimizes the horizontal size.

[0058] The first solder resist layer 13 covers the surface of the top layer copper foil 12 and adopts a high-resolution photosensitive material. The first exposed hole 13a and the second exposed hole 13b are arranged in a staggered manner. The first exposed hole 13a is located at the signal input end of the copper foil strip, and the second exposed hole 13b is located at the output end and is directly connected to the lower layer board 30 through a vertical via, completely replacing the traditional horizontal trace and eliminating the horizontal space occupation.

[0059] Through the side-by-side design of multiple copper foil strips, the width of the signal trace area is reduced by 50% compared with the traditional scheme. The direct connection design of the second exposed hole 13b and the foot pad 31 of the lower layer board 30 reduces the horizontal span of the signal transmission path. The serpentine layout of the copper foil strip extends the trace length within a limited width, avoids the decrease of signal integrity caused by too short path, and at the same time avoids the additional increase of horizontal size.

[0060] The first solder resist layer 13 completely covers the non-functional area of the copper foil strip to form a protective layer to prevent the copper foil from being deformed or oxidized by external force. The first copper foil body 121 cooperates with the ground network of the plurality of copper foil strips to improve the overall structural rigidity and increase the bending strength.

[0061] In an embodiment, please refer to Figures 1 to 3The first solder resist layer 13 is stacked with a ground layer 14 on the side opposite to the top layer copper foil 12, and the ground layer 14 is provided with an avoiding hole, and the pickup element 11 is located at the avoiding hole.

[0062] The ground layer 14 is made of high-conductivity copper foil and is combined with the first solder resist layer 13 through a pressing process, and the interlayer dielectric material is selected as a low-dielectric-constant polyimide film. The ground layer 14 is provided with a circular avoiding hole in the central region, which is coaxially aligned with the pickup hole 10a of the upper layer board 10, and the edge of the avoiding hole is formed with a chamfer through laser cutting to avoid burr interference with the sound wave path.

[0063] The shielding effectiveness of the ground layer 14 to electromagnetic interference in the frequency band of 1 GHz-5 GHz is ≥40 dB, and the common-mode noise around the pickup element 11 is attenuated to below -50 dB through a closed loop design. The vertical stacking design of the ground layer 14 and the top layer copper foil 12 eliminates the need for a traditional independent shielding cover, and compresses the horizontal width of the upper layer board 10. The diameter of the avoiding hole and the size tolerance of the pickup element 11 are controlled within ±10 μm, which reduces the element layout safety distance and reduces the signal area width.

[0064] In an embodiment, referring to Figures 1 to 3 The top layer copper foil 12 further includes a first annular copper foil 123 connected with the first copper foil body 121 and enclosing the first copper foil body 121 to form an enclosed area for connecting external circuits, and a plurality of first copper foil strips 122 located in the enclosed area.

[0065] The first annular copper foil 123 is a closed loop structure and is electrically connected with the first copper foil body 121 through a micro-hole blind hole technology. Its functions include: a plurality of equally spaced pads are arranged on the outer edge of the annular copper foil for directly connecting external circuits (such as mainboard signal lines), replacing the traditional dispersed pad layout. The closed loop structure forms a Faraday cage effect to isolate the signal lines in the enclosed area from external interference, and the shielding effectiveness is ≥25 dB.

[0066] The plurality of first copper foil strips 122: 4-6 copper foil strips are arranged side by side, and each strip adopts an arc-shaped wiring design with a maximum curvature radius ≤0.3 mm to prolong the wiring length and suppress signal reflection. One end of all the copper foil strips is connected with the pickup element 11 through the first exposed hole 13a, and the other end is directly connected with the pads of the annular copper foil through the second exposed hole 13b, forming a vertical transmission link of "signal input-annular interface-external circuit", which reduces the horizontal span.

[0067] The first solder resist layer 13 covers the surface of the copper foil and adopts a high-temperature-resistant photosensitive ink. The solder resist layer is provided with a third exposed hole 13c on the outer edge of the enclosed area to expose the pads of the annular copper foil for solder paste printing and mainboard welding. The non-connected area of the copper foil strips in the enclosed area is completely covered by the solder resist layer to prevent short circuit and enhance the mechanical strength.

[0068] Through the design of the central pad of the ring copper foil, the horizontal space occupied by the external circuit connection point is reduced. The arc-shaped path of the copper foil strip extends the wiring length within the limited surrounding area, avoiding the additional horizontal space required by straight-line wiring. The vertical conduction design of the copper foil strip and the ring pad replaces the traditional horizontal winding.

[0069] This embodiment compresses the width of the stacked plate microphone through the design of the first ring copper foil 123 and the surrounding area, with the core strategy of "central interface, closed shielding, and arc-shaped wiring". The technical advantages not only lie in size reduction, but also in the comprehensive improvement of electromagnetic shielding, signal integrity, and mechanical strength, meeting the stringent needs of ultra-thin intelligent terminals such as AR glasses and miniature drones.

[0070] In one embodiment, referring to Figures 1 to 3 , the diameter of the third exposed hole 13c is greater than that of the pickup hole 10a, and a copper ring 16 is arranged in the third exposed hole 13c. The copper ring 16 is connected with the top layer copper foil 12 and exposes the pickup hole 10a, used for releasing static electricity.

[0071] The third exposed hole 13c is coaxially arranged with the pickup hole 10a. The inner wall thereof is formed into a stepped structure through laser cutting. The upper segment aperture is consistent with the pickup hole 10a, and the lower segment aperture is enlarged to accommodate the copper ring 16. The copper ring 16 is a ring-shaped copper structure with a thickness consistent with the top layer copper foil 12, and is connected with the grounding network of the top layer copper foil 12 through electroplating process. The copper ring 16 is directly connected with the grounding network of the top layer copper foil 12, and when external static electricity enters through the pickup hole 10a, it is quickly guided to the grounding end through the copper ring 16. The stepped inner wall design of the third exposed hole 13c makes the sound wave evenly diffuse to the surface of the MEMS sensor after passing through the pickup hole 10a, reducing distortion caused by sound pressure concentration and improving frequency response flatness.

[0072] This embodiment compresses the width of the stacked plate microphone through the integrated design of the third exposed hole 13c and the copper ring 16, with the core strategy of "function reuse, ring compression, and vertical direct connection". The technical breakthrough lies in the integration of electrostatic protection, acoustic optimization, and electromagnetic shielding functions in a single structure, significantly improving space utilization and reliability.

[0073] In one embodiment, referring to Figure 1 and Figure 4 , the cavity wall of the hollow cavity 20a is covered with a metal layer, which is used for grounding connection and electromagnetic shielding.

[0074] The surface of the cavity wall of the hollow cavity 20a is formed with a continuous metal layer through chemical copper plating process. The metal layer is directly connected with the grounding network of the middle layer plate 20 through vertical through holes, forming a full-area low-impedance grounding path. The metal layer forms a closed ring-shaped structure along the cavity wall, which cooperates with the copper ring 16 of the upper layer plate 10 and the grounding pad of the lower layer plate 30 to construct a three-dimensional electromagnetic shielding network with shielding effectiveness ≥ 40 dB.

[0075] The embodiment reduces the width of the compression stacked microphone through the stepped design of the hollow cavity 20a metal layer, vertical wiring and function integration. The technical core is to realize the dual breakthrough of size reduction and performance improvement through a three-dimensional shielding network, a high-precision processing technology and a spatial multiplexing strategy.

[0076] In an embodiment, referring to Figure 1 and Figure 4 , the middle layer plate 20 is provided with a mounting plate 21 located on one side of the hollow cavity 20a, and the mounting plate 21 is provided with at least one middle layer pad 22 connected with the pickup element 11 and the foot pad 31, so that the pickup element 11 and the foot pad 31 are electrically connected.

[0077] The mounting plate 21 is located on one side of the hollow cavity 20a of the middle layer plate 20, and the surface is formed into a hollow support frame through laser cutting. The pickup element 11 (MEMS sensor and ASIC chip) is bonded to the surface of the mounting plate 21 by epoxy resin glue. The surface of the mounting plate 21 is provided with four middle layer pads 22, which are vertically connected with the pickup element 11 pin of the upper layer plate 10 and the foot pad 31 of the lower layer plate 30 through embedded blind holes. The size and function (optimizing wiring, supporting strength, electromagnetic shielding) of the middle layer pad 22.

[0078] Each middle layer pad 22 connects the upper layer pickup element 11 and the lower layer foot pad 31 at the same time through double-sided through holes, the signal transmission path is completely vertical, and the horizontal winding requirement is eliminated. The cavity wall of the hollow cavity 20a is covered with a metal layer, which extends to the edge of the mounting plate 21 and is connected with the middle layer pad 22 through a solder bump, forming a global grounding network.

[0079] In an embodiment, referring to Figure 1 , Figure 5 and Figure 6 , the side of the lower layer plate 30 facing the middle layer plate 20 is sequentially provided with a lower copper foil 32 and a second solder resist layer 33, and the second solder resist layer 33 is provided with six exposure holes arranged in an array; each exposure hole is used to expose the lower copper foil 32.

[0080] The lower copper foil 32 is the core conductive layer of the lower layer plate 30, which adopts a high-precision etching process to form the following functional areas: including power supply (VDD), data output (DATA), clock (CLOCK), left / right sound channels (L / R) and ground (GND) traces, and compression line width. The surface of the copper foil is pre-provided with six rectangular pads (size, corresponding to the middle layer pad 22 of the middle layer plate 20 through a vertical through hole.

[0081] The second solder resist layer 33 covers the surface of the lower copper foil 32 and is made of high-temperature resistant photosensitive ink. The solder resist layer has six exposure holes arranged in a 2x3 matrix and aligned with the preset pads of the lower copper foil 32. Each exposure hole precisely exposes the pad area of the lower copper foil 32 for solder paste printing and vertical welding with the middle layer board 20.

[0082] The compact matrix arrangement of the six exposure holes replaces the traditional dispersed pad design and compresses the horizontal width of the signal area. The signal vertical transmission is achieved through the Via-in-Pad process, eliminating the horizontal space occupation and reducing the effective width of the lower layer board 30. The extreme compression of the copper foil trace width and pitch further reduces the redundant space.

[0083] The embodiment realizes the high-density array exposure hole design of the lower copper foil 32 and the vertical welding technology. The technical core lies in the matrix layout, limit line width control and function integration, which maximizes the space utilization rate while ensuring signal integrity and anti-interference capability.

[0084] In an embodiment, referring to Figure 1 , Figure 5 and Figure 6 , the lower copper foil 32 includes at least six copper foil blocks 321 and at least two second copper foil strips 322. The six copper foil blocks 321 are arranged in two columns on the lower layer board 30. Each exposure hole is used for a copper foil block 321. Each second copper foil strip 322 is connected to a copper foil block 321, and the two second copper foil strips 322 are located between the two columns of copper foil blocks 321. Each second copper foil strip 322 has a pin pad 31 at the end away from the copper foil block 321.

[0085] The six copper foil blocks 321 are arranged in two columns on the surface of the lower layer board 30, and each column includes three copper foil blocks 321. Each copper foil block 321 is connected to the middle layer pad 22 of the middle layer board 20 through a vertical via hole, corresponding to the power supply (VDD), data output (DATA), clock (CLOCK), left / right channel (L / R), ground (GND) and redundant signal channel, respectively. The six exposure holes of the second solder resist layer 33 are aligned with the copper foil blocks 321 one by one, and the solder points are formed by solder paste printing to realize vertical welding with the middle layer board 20.

[0086] Two second copper foil strips 322 are located between the two rows of copper foil blocks 321, one end of each second copper foil strip 322 is connected to the middle copper foil block 321 in one row, and the other end extends to the edge of the lower layer plate 30 and is provided with a pin pad 31 for connecting with an external mainboard. The second copper foil strip 322 is used as a concentrated wiring of power supply and ground, replaces the traditional dispersed wiring, and reduces the redundant path. The pin pad 31 is located at the end of the second copper foil strip 322, adopts a special-shaped design (such as a trapezoidal or elliptical shape), and is gold-plated on the surface. The pad is connected with the mainboard pad through reflow soldering to form a low-impedance external interface. The special-shaped design (such as a semicircular or trapezoidal shape) of the pin pad 31 and its dual functions (signal transmission and optical positioning) avoid occupying additional space.

[0087] The double-row spacing arrangement of the copper foil blocks 321 reduces the horizontal space occupied compared with the traditional single-row design. The second copper foil strip 322 directly crosses the two rows of copper foil blocks 321, eliminates the need for horizontal winding, and reduces the width of the power supply and ground wiring area. The exposed hole is accurately aligned with the copper foil block 321, and the vertical soldering path length is shortened.

[0088] In an embodiment, please refer to Figure 1 , Figure 5 and Figure 6 , wherein the shape of one copper foil block 321 is different from the shapes of the remaining copper foil blocks 321, and is used as a pin mark point.

[0089] Among the six copper foil blocks 321, one is designed as a semicircular shape, and the remaining five are regular rectangular shapes. The semicircular copper foil block 321 is located in the middle of the left column and is used as a pin mark point (Mark point) for optical positioning during SMT patching. The semicircular copper foil block 321 is connected with the pin pad 31 through the second copper foil strip 322, and has the functions of signal transmission (such as redundant ground) and positioning, avoiding the additional space occupied by the independent Mark point.

[0090] The embodiment uses the special-shaped copper foil block 321 mark point design, and takes “function multiplexing, high-precision alignment, and compact layout” as the core strategy. The technical breakthrough lies in the deep integration of the mark point and the signal path, the optimization of the material reflectivity, and the process innovation, realizing the dual improvement of size reduction and mounting precision.

[0091] The above merely describes exemplary embodiments of the present application, and does not limit the patent scope of the present application. Any equivalent structural transformation made by using the content of the present application specification and drawings, or direct / indirect application in other related technical fields is included in the patent protection scope of the present application.

Claims

1. A stacked board microphone characterized by comprising: The stacked plate microphone comprises: an upper layer plate provided with a sound pickup hole and integrated with a sound pickup element arranged at intervals from the sound pickup hole; a middle layer plate connected to one side of the upper layer plate in a stacked manner, the middle layer plate having a hollow cavity for accommodating the sound pickup element; and a lower layer plate connected to one side of the middle layer plate away from the upper layer plate in a stacked manner, the lower layer plate provided with at least two foot pads arranged at intervals and electrically connected to the sound pickup element.

2. The stacked board microphone according to claim 1, wherein One side of the upper layer plate is sequentially provided with a top copper foil and a first solder resist layer in a stacked manner, the sound pickup element being arranged on one side of the first solder resist layer away from the top copper foil; the first solder resist layer has a first exposed hole, a second exposed hole and a third exposed hole, the first exposed hole and the second exposed hole being arranged adjacent to the sound pickup hole, and the third exposed hole being arranged coincidentally with the sound pickup hole; the first exposed hole is used for exposing one end of the top copper foil, the second exposed hole is used for exposing the other end of the top copper foil, and the second exposed hole is provided with an upper layer pad connected to the top copper foil and the foot pad; the sound pickup element is connected to one end of the top copper foil through the first exposed hole.

3. The stacked board microphone according to claim 2, wherein The top copper foil comprises: a first copper foil body arranged on one side of the upper layer plate; and a plurality of first copper foil strips arranged on one side of the upper layer plate, the first copper foil strips being arranged side by side and adjacent to the first copper foil body; the first exposed hole is used for exposing one end of the first copper foil strips; the first solder resist layer is provided with a plurality of second exposed holes, each of the second exposed holes being used for exposing the other end of the first copper foil strips.

4. The stacked board microphone according to claim 2, wherein One side of the first solder resist layer away from the top copper foil is provided with a ground layer in a stacked manner, and the ground layer is provided with a clearance hole, the sound pickup element being located at the clearance hole.

5. The stacked board microphone according to claim 3, wherein The top copper foil further comprises a first annular copper foil connected to the first copper foil body and enclosing the first copper foil body to form an enclosed area for connecting external circuits; the first copper foil strips are located in the enclosed area.

6. The stacked board microphone according to claim 3, wherein The third exposed hole has a diameter greater than that of the sound pickup hole, and a copper ring is arranged in the third exposed hole, the copper ring being connected to the top copper foil and exposing the sound pickup hole for releasing static electricity.

7. The stacked board microphone according to claim 1, wherein The cavity wall of the hollow cavity is covered with a metal layer for grounding connection and electromagnetic shielding.

8. The stacked board microphone according to claim 7, wherein The middle layer plate is provided with a mounting plate located on one side of the hollow cavity, and the mounting plate is provided with at least one middle layer pad connected to the sound pickup element and the foot pad to electrically connect the sound pickup element and the foot pad.

9. The stacked board microphone according to claim 1, wherein One side of the lower layer plate facing the middle layer plate is sequentially provided with a lower copper foil and a second solder resist layer in a stacked manner, the second solder resist layer being provided with six exposed holes arranged in an array; each of the exposed holes is used for exposing the lower copper foil.

10. The stacked board microphone according to claim 9, wherein The lower copper foil comprises: at least six copper foil blocks, six of the copper foil blocks are arranged in two columns on the lower layer board; each of the exposed holes is used for one of the copper foil blocks; and at least two second copper foil strips, each of the second copper foil strips is connected with one of the copper foil blocks, and two of the second copper foil strips are located between the two columns of the copper foil blocks; each of the second copper foil strips is provided with the pin pad at an end away from the copper foil block; and / or, one of the copper foil blocks is provided with a shape different from the shapes of the other copper foil blocks, and is used as a pin mark point.

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