Packaging structure of MEMS loudspeaker

Abstract

The utility model discloses a packaging structure of an MEMS (Micro Electro Mechanical System) loudspeaker, which is used for connecting a loudspeaker chip with a PCB (Printed Circuit Board), a lower sound outlet hole and a pin contact on the side of the lower sound outlet hole are preset on the PCB, and the loudspeaker chip is positively arranged on the surface of the PCB in a way that a silicon substrate is arranged at the lower part and a vibrating diaphragm part is arranged at the upper part. An electrode contact, at a high position, of the loudspeaker chip is connected with a pin contact through a metal lead; the surface of the PCB is fixedly connected with a metal shell which completely covers the loudspeaker chip and the pin contacts, an air cavity is formed between the metal shell and the loudspeaker chip, and the metal shell is provided with an upper sound outlet hole for maintaining the strength of the metal shell. By applying the packaging structure based on chip normal installation, the convenience of connection between the electrode contact of the chip and the pin contact of the PCB is improved, and the production yield bottleneck of high alignment precision requirement is overcome; meanwhile, the amplitude space of the vibrating diaphragm is guaranteed, and the risk of failure of the touch panel in the using process is eliminated.

Description

Technical Field

[0001] The utility model relates to a packaging structure of an electroacoustic transducer, in particular to a packaging structure of a MEMS loudspeaker which is beneficial to improving yield and reducing cost. Background Art

[0002] MEMS chip refers to Micro-Electro-Mechanical Systems chip, also known as micro-electromechanical system integrated circuit. MEMS acoustic devices are also used in audio devices such as speakers and microphones to provide a better audio experience. Miniature MEMS speakers can use thin film piezoelectric materials as actuators and silicon-containing layers as membranes, which are processed and formed by at least one semiconductor process. In order to make this kind of micro speaker more widely used, the industry is committed to designing micro speakers with higher yield and performance.

[0003] In the related art, MEMS speakers are mostly electrically connected by metal bonding and then assembled on the PCB board through side walls and covers. However, this method usually has a complicated packaging process, especially high pin alignment accuracy requirements and low packaging yield. In addition, since the speaker chip is flipped on the PCB board, the distance between the diaphragm of the speaker chip and the surface of the PCB board is limited, so the diaphragm is very easy to touch the PCB board during use, resulting in abnormal sound or failure. Summary of the invention

[0004] The utility model aims to provide a packaging structure of a MEMS speaker, which solves the problem of improving yield and product reliability at a lower cost.

[0005] To achieve the above-mentioned purpose, the utility model provides the following technical solutions: a packaging structure of a MEMS speaker, used for connecting a speaker chip with a PCB board, the PCB board is preset with a lower sound outlet and pin contacts next to it, the speaker chip is mounted on the surface of the PCB board with the silicon substrate at the bottom and the diaphragm part at the top, and the electrode contacts of the speaker chip at a high position are connected to the pin contacts through metal leads; a metal shell is fixedly connected to the surface of the PCB board, which completely covers the speaker chip and the pin contacts and forms an air cavity between the speaker chip, and the metal shell is provided with an upper sound outlet for maintaining its own strength.

[0006] Furthermore, the lower sound outlet hole is a single opening and is opened at a position offset from the center relative to the speaker chip.

[0007] Furthermore, the lower sound outlet holes are arranged as multiple openings with increasing number and decreasing hole diameters per unit area on the central bottom side of the corresponding speaker chip.

[0008] Furthermore, the metal lead wire is an enameled flat wire or an insulation-coated single-strand round wire, and the length of the metal lead wire is sufficient to bridge the electrode contacts and the pin contacts and leave a portion of redundant length.

[0009] Furthermore, the metal shell is a formed body formed by bending, welding or die stamping of metal sheets, and is formed with a fence and a top cover.

[0010] Furthermore, the fence is arranged in a closed loop and the top cover is provided with a plurality of upper sound outlet holes which are arranged linearly or distributed in an array.

[0011] Furthermore, the top cover is fully shielded and a groove-shaped upper sound outlet is provided on one side wall of the fence.

[0012] Furthermore, a dense-hole dustproof net is respectively attached to the bottom side of the PCB board corresponding to the lower sound outlet hole and the inner side of the metal shell corresponding to the upper sound outlet hole.

[0013] Compared with the prior art, the application of the chip upright packaging structure of the utility model has the following beneficial effects: the convenience of connecting the electrode contacts of the chip with the pin contacts of the PCB board is improved, and the production yield bottleneck with high requirements for positioning accuracy is overcome; at the same time, the amplitude space of the diaphragm is guaranteed, eliminating the risk of touch panel failure during use. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural diagram of the first packaging embodiment of the MEMS speaker chip of the utility model.

[0015] Figure 2 It is a structural diagram of the second packaging embodiment of the MEMS speaker chip of the utility model.

[0016] Figure 3 It is a structural diagram of the third packaging embodiment of the MEMS speaker chip of the utility model.

[0017] Figure 4 It is a structural diagram of the fourth packaging embodiment of the MEMS speaker chip of the utility model.

[0018] Figure 5 It is a structural diagram of the fifth packaging embodiment of the MEMS speaker chip of the utility model. DETAILED DESCRIPTION

[0019] The specific implementation methods of the utility model will be further described below in conjunction with the accompanying drawings of the embodiments, so that the technical solution of the utility model is easier to understand and grasp, thereby making a clearer definition of the protection scope of the utility model.

[0020] The utility model proposes a packaging structure of a MEMS speaker, which is used for packaging a speaker chip on a PCB board, and further improves the protection strength of the diaphragm part, product reliability and sound output performance while giving full play to the sound-generating function of the speaker chip.

[0021] like Figure 1 As shown in the diagram of a packaging embodiment, the packaging structure involves a MEMS speaker (or speaker chip 2) and a PCB board 1 (or substrate), and the two parts are usually made by independent and mature processes and have completed product quality inspection. However, these are not the technical points that this application is committed to protecting, and therefore detailed description is omitted. However, in terms of the packaging structure, the PCB board 1 is preset with a lower sound outlet 11 and a pin contact 12 beside it. The speaker chip 2 is mounted on the surface of the PCB board 1 with the silicon substrate 21 at the bottom and the diaphragm part 22 at the top. An inner air cavity A is formed between the diaphragm part and the PCB board, and the electrode contact 23 of the speaker chip 2 at a high position is connected to the pin contact 12 through a metal lead 3. Necessarily, a metal shell 4 is also fixed to the surface of the PCB board 1, which completely covers the speaker chip 2 and the pin contact 12 and forms a middle-layer air cavity B between the speaker chip. The metal shell 4 is also provided with an upper sound outlet hole that is conducive to the circulation of the middle-layer air cavity B with the outside air and can maintain its own strength.

[0022] From the further refinement of the features, the lower sound outlet 11 in the first embodiment is a single opening, and is opened at the center of the speaker chip. Theoretically, the speaker chip in this embodiment also needs to perform low-precision alignment operations, but it is not necessary. On the one hand, the metal lead 3 can be an enameled flat wire or an insulating single-strand round wire, and the length of the metal lead 3 meets the requirements of the cross-connect electrode contact 23 and the pin contact 12 and leaves a part of redundant length, that is, the speaker chip can still be freely adjusted and positioned within a limited range under the premise of completing the electrical connection. On the other hand, the metal shell 4 can be bent into a container shape by a metal sheet and welded into shape, or it can be stamped into a metal sheet by a prefabricated mold. According to the figure, it can be roughly divided into two parts: a fence 41 and a top cover 42, which are actually connected as a whole. And the metal shell is only provided with a plurality of upper sound outlets 43a arranged linearly or in an array at the top cover 42.

[0023] like Figure 2 The second packaging embodiment shown in the figure can be seen. Its packaging structure body and Figure 1 The embodiment shown is basically the same, with the slight difference being that the lower sound outlet hole 11 of the PCB board 1 is opened at a position offset from the center relative to the speaker chip 2; this can effectively avoid the introduction of particles that limit the vibration of the driving structure of the speaker chip during the process.

[0024] like Figure 3The third packaging embodiment shown in the figure can be seen. Its packaging structure body is also similar to Figure 1 The difference is that the lower sound outlet hole 11 of the PCB board 1 is a multi-hole arrangement with an increased number and a reduced hole diameter per unit area on the central bottom side of the corresponding speaker chip 2. The advantage of this is that the probability of particle introduction can be reduced, and the amplitude of the first-order resonance frequency can be reduced, thereby improving the smoothness of the frequency response curve.

[0025] like Figure 4 The fourth packaging embodiment shown in the figure can be seen. Its packaging structure body is also similar to Figure 1 The metal shell is basically the same as shown, with the minor difference that the top cover 42 is fully shielded in the metal shell, that is, the middle air cavity B no longer circulates air upward; and a groove-shaped upper sound outlet 43b is opened on one side wall of the fence 41. In this way, the upper sound outlet can be directly opposite to the sound outlet of the earphone in the internal layout of the earphone module design.

[0026] like Figure 5 The fifth packaging embodiment shown in the figure can be seen. Its packaging structure body and Figure 2 The figures are basically the same as shown, with the slight difference being that, on the one hand, the fence 41 of the metal sheet 4 is arranged in a closed loop and the top cover 42 has only one upper sound outlet hole 43c; on the other hand, a dense-hole dustproof net 5 is respectively attached on the bottom side of the PCB board 1 corresponding to the lower sound outlet hole 11 and on the inner side of the metal shell 4 corresponding to the upper sound outlet hole 43c.

[0027] From the above introduction to the packaging structure scheme and detailed description of the embodiments of the MEMS speaker of the utility model, it can be seen that this scheme has substantial characteristics and progress: the packaging structure based on chip upright mounting is utilized to improve the convenience of connecting the electrode contacts of the chip with the pin contacts of the PCB board, thereby overcoming the production yield bottleneck with high requirements for alignment accuracy; at the same time, the amplitude space of the diaphragm is guaranteed, eliminating the risk of touch panel failure during use.

[0028] In addition to the above-mentioned embodiments, the present invention may also have other implementation modes. Any technical solutions formed by equivalent replacement or equivalent transformation shall fall within the scope of protection required by the present invention.

Claims

1. A packaging structure of a MEMS speaker, used for connecting a speaker chip to a PCB board, characterized in that: The PCB board is preset with a lower sound hole and pin contacts next to it. The speaker chip is mounted on the surface of the PCB board with the silicon substrate at the bottom and the diaphragm part at the top, and the electrode contacts of the speaker chip at a high position are connected to the pin contacts through metal leads. A metal shell is fixed to the surface of the PCB board, which completely covers the speaker chip and the pin contacts and forms an air cavity between the speaker chip, and the metal shell is provided with an upper sound hole for maintaining its own strength.

2. The packaging structure of the MEMS speaker according to claim 1, characterized in that: The lower sound outlet hole is a single opening and is opened at a position offset from the center relative to the speaker chip.

3. The packaging structure of the MEMS speaker according to claim 1, characterized in that: The lower sound outlet holes are arranged as multiple openings with increasing number and decreasing hole diameters per unit area on the central bottom side of the corresponding speaker chip.

4. The packaging structure of the MEMS speaker according to claim 1, characterized in that: The metal lead wire is an enameled flat wire or an insulation-coated single-strand round wire, and the length of the metal lead wire is sufficient to bridge the electrode contacts and the pin contacts and leave a portion of redundant length.

5. The packaging structure of the MEMS speaker according to claim 1, characterized in that: The metal shell is a formed body formed by bending and welding of metal sheets or by die stamping, and is formed with a fence and a top cover.

6. The packaging structure of the MEMS speaker according to claim 5, characterized in that: The fence is arranged in a closed loop and the top cover is provided with a plurality of upper sound outlet holes which are arranged linearly or distributed in an array.

7. The packaging structure of the MEMS speaker according to claim 5, characterized in that: The top cover is fully shielded and a groove-shaped upper sound outlet hole is opened on one side wall of the fence.

8. The packaging structure of the MEMS speaker according to claim 1, characterized in that: The PCB board is provided with a dense-hole dustproof net on the bottom side corresponding to the lower sound outlet hole and the metal shell is provided with a dense-hole dustproof net on the inner side corresponding to the upper sound outlet hole.

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