Silicon microphone device packaging structure and preparation method of silicon microphone device packaging structure

Abstract

Embodiments of the present invention provide a silicon microphone device packaging structure and a preparation method thereof, relating to the technical field of semiconductor packaging. The silicon microphone device packaging structure includes a substrate, a silicon microphone chip, a control chip, and a packaging cover plate. The packaging cover plate includes an inner packaging cover and an outer packaging cover. The inner packaging cover has a first chamber, and the outer packaging cover has a second chamber. The first chamber and the second chamber are in communication, increasing the sound cavity space and improving the sensitivity and signal-to-noise ratio of the silicon microphone chip. A first sound guiding hole is provided on the side wall of the inner packaging cover, thus avoiding direct entry of sound into the first chamber and contact with the silicon microphone chip, and avoiding damage to the silicon microphone chip caused by sound pressure impact. In addition, a vibration rubber film is provided at the first sound guiding hole, and a drainage hole is provided to achieve drainage, avoiding contact between water vapor and the silicon microphone chip, and also avoiding accumulation of water vapor in the second chamber, further ensuring the reliability of the product.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor packaging, and in particular, to a silicon microphone device packaging structure and a preparation method thereof. Background Art

[0002] With the rapid development of the semiconductor industry, microphones have been widely used in various electronic products in the consumer field. Among them, silicon microphones have been widely used in mobile terminals due to their small size and strong stability. The silicon microphone includes a MEMS (Micro Electro Mechanical System) chip, and the MEMS chip includes a silicon diaphragm and a silicon backplate. Among them, the working principle of the MEMS chip is that the pressure gradient generated by the sound change causes the silicon diaphragm to be deformed by the acoustic pressure interference, and then changes the capacitance value between the silicon diaphragm and the silicon backplate, thereby converting the acoustic pressure signal into a voltage signal. In the existing MEMS silicon microphone products, the design is that sound enters the inside of the MEMS chip and the metal cover from a single hole / single direction. Since the sound cavity is small, when the sound signal is very weak, the acoustic pressure signal is weaker, resulting in a decrease in the sensitivity and signal-to-noise ratio of the MEMS silicon microphone products. Moreover, since the silicon diaphragm on the MEMS chip is very sensitive to the change of acoustic pressure, in the prior art, the external acoustic pressure directly contacts the silicon diaphragm on the MEMS chip. Therefore, when the intensity of the acoustic pressure change exceeds a certain value, the silicon diaphragm will rupture due to the impact of the high-intensity acoustic pressure, affecting the product reliability. In addition, in the existing MEMS packaging structure, a sound inlet hole is provided at the top, and no drainage structure is provided, which easily causes water vapor to enter the inside of the sound cavity. When accumulated too much, it will affect the performance of the chip and even damage the chip. Summary of the Invention

[0003] The objectives of the present invention include, for example, providing a silicon microphone device packaging structure and a preparation method thereof, which can increase the volume of the sound cavity, thereby improving the sensitivity and signal-to-noise ratio of the product, and can avoid the direct contact between the external boost pressure and the silicon diaphragm, thereby avoiding the impact of acoustic pressure on the product reliability. Finally, the present application can also achieve drainage and avoid water accumulation inside the sound cavity.

[0004] Embodiments of the present invention may be implemented as follows:

[0005] In a first aspect, the present invention provides a silicon microphone device packaging structure, including:

[0006] A substrate;

[0007] A silicon microphone chip and a control chip disposed on the substrate;

[0008] A packaging cover plate disposed on the substrate and covering the silicon microphone chip and the control chip;

[0009] Among them, the encapsulation cover plate includes an inner encapsulation cover and an outer encapsulation cover. The inner encapsulation cover has a first chamber, and both the MEMS microphone chip and the control chip are accommodated in the first chamber. The outer encapsulation cover covers the outside of the inner encapsulation cover and has a second chamber. A first sound guiding hole is provided on the side wall of the inner encapsulation cover, and the first sound guiding hole is used to conduct the first chamber and the second chamber. A vibration diaphragm is also provided at the first sound guiding hole, and the vibration diaphragm is used to block the first sound guiding hole and transmit sound pressure. A first sound inlet hole communicating with the second chamber is also provided on the outer encapsulation cover, and a drainage hole communicating with the second chamber is also provided at the bottom of the outer encapsulation cover.

[0010] In an alternative embodiment, the inner encapsulation cover is further provided with a pressure transmission channel. The first sound guiding hole is located at the end of the pressure transmission channel and communicates with the pressure transmission channel. A second sound guiding hole is provided at the top wall of the first chamber, and the second sound guiding hole communicates with the pressure transmission channel.

[0011] In an alternative embodiment, a sound transmission groove is provided at the top of the outer encapsulation cover, and the first sound inlet hole is provided on the side wall and / or bottom wall of the sound transmission groove that is joined to the second chamber.

[0012] In an alternative embodiment, the outer encapsulation cover further has a third chamber. A sound insulation board is further provided inside the outer encapsulation cover, and the sound insulation board is used to divide the chamber between the inner encapsulation cover and the outer encapsulation cover into a second chamber and a third chamber. A back sound hole is also provided on the substrate, and the MEMS microphone chip covers the back sound hole, and the back sound hole communicates with the third chamber.

[0013] In an alternative embodiment, a sound transmission hole is further provided on the substrate. The sound transmission hole is located between the inner encapsulation cover and the outer encapsulation cover and communicates with the third chamber. A sound guiding channel is further provided inside the substrate. One end of the sound guiding channel extends to the sound transmission hole, and the other end extends to the back sound hole, so that the back sound hole communicates with the sound transmission hole.

[0014] In an alternative embodiment, a third sound guiding hole is provided on the side wall of the inner encapsulation cover that is joined to the third chamber, and the third chamber communicates with the first chamber through the third sound guiding hole.

[0015] In an alternative embodiment, the width of the third sound guiding hole is greater than the width of the MEMS microphone chip, and the width of the second sound guiding hole is greater than the width of the MEMS microphone chip.

[0016] In an alternative embodiment, a first partition board is further disposed in the third chamber. One end of the first partition board is connected to the sound insulation board and bends and extends to the substrate. The first partition board is used to divide the third chamber into two sub-cavities. A sound transmission opening is further disposed at one end of the first partition board close to the substrate. The sound transmission opening is used to communicate the two sub-cavities.

[0017] In an alternative embodiment, the sound insulation board includes a first sound insulation portion and a second sound insulation portion integrally provided. The first sound insulation portion is connected to the inner wall of the outer encapsulation cover. The second sound insulation portion is connected to the substrate. A fourth chamber is formed between the second sound insulation portion and the inner encapsulation cover. The fourth chamber communicates with the second chamber.

[0018] In an alternative embodiment, a third sound guiding hole is provided on the side wall of the inner encapsulation cover that is joined to the fourth chamber. The fourth chamber communicates with the first chamber through the third sound guiding hole.

[0019] In an alternative embodiment, the sound transmission groove penetrates to the surface of the inner encapsulation cover. A sound transmission through shell is further provided on the outer encapsulation cover. The sound transmission through shell is located in the sound transmission groove. Both ends of the sound transmission through shell are respectively communicated with the second chamber and the fourth chamber. A second sound inlet hole is provided at the bottom of the sound transmission through shell.

[0020] In an alternative embodiment, a third sound inlet hole is provided on the first sound insulation portion. The third sound inlet hole communicates with the third chamber.

[0021] In an alternative embodiment, a fourth sound guiding hole is provided on the second sound insulation portion. The third chamber communicates with the fourth chamber through the fourth sound guiding hole.

[0022] In a second aspect, the present invention provides a preparation method for a silicon microphone device packaging structure for preparing the silicon microphone device packaging structure according to any one of the foregoing embodiments. The preparation method includes:

[0023] Providing a substrate;

[0024] Mounting a silicon microphone chip and a control chip on the substrate;

[0025] Mounting a packaging cover plate on the substrate. The packaging cover plate covers the silicon microphone chip and the control chip.

[0026] Among them, the encapsulation cover plate includes an inner encapsulation cover and an outer encapsulation cover. The inner encapsulation cover has a first chamber, and both the MEMS microphone chip and the control chip are accommodated in the first chamber. The outer encapsulation cover covers the outside of the inner encapsulation cover and has a second chamber. A first sound guiding hole is provided on the side wall of the inner encapsulation cover, and the first sound guiding hole is used to conduct the first chamber and the second chamber. A vibration diaphragm is also provided at the first sound guiding hole, and the vibration diaphragm is used to block the first sound guiding hole and transmit sound pressure. A first sound inlet hole communicating with the second chamber is further provided on the outer encapsulation cover, and a drain hole communicating with the second chamber is further provided at the bottom of the outer encapsulation cover.

[0027] The beneficial effects of the embodiments of the present invention include, for example:

[0028] The MEMS microphone device packaging structure provided by the embodiments of the present invention covers the MEMS microphone chip and the control chip with an encapsulation cover plate. At the same time, the inner encapsulation cover has a first chamber, and the outer encapsulation cover has a second chamber. The first chamber and the second chamber are conducted through the first sound guiding hole, thereby increasing the sound cavity space of the MEMS microphone chip and improving the sensitivity and signal-to-noise ratio of the MEMS microphone chip. At the same time, in this embodiment, sound enters through the first sound inlet hole, and the first sound guiding hole is provided on the side wall of the inner encapsulation cover, thereby avoiding direct contact between the sound and the MEMS microphone chip when entering the first chamber. The first chamber and the second chamber can play a buffering role, thereby avoiding damage to the MEMS microphone chip caused by sound pressure impact. In addition, a vibration diaphragm is provided at the first sound guiding hole. The vibration diaphragm blocks the first sound guiding hole and can transmit sound pressure. The water vapor entering through the first sound inlet hole is blocked at the vibration diaphragm and continues to fall downward into the drain hole at the bottom of the second chamber for discharge, thereby realizing drainage, avoiding contact between the water vapor and the MEMS microphone chip, and also avoiding the accumulation of water vapor in the second chamber, further ensuring the reliability of the product. Description of the Drawings

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0030] Figure 1 It is a cross-sectional schematic diagram of the MEMS microphone device packaging structure provided by the first embodiment of the present invention;

[0031] Figure 2 It is a step block diagram of the manufacturing method of the MEMS microphone device packaging structure provided by the first embodiment of the present invention;

[0032] Figure 3Schematic cross-sectional view of the silicon microphone device packaging structure provided by the second embodiment of the present invention;

[0033] Figure 4 Schematic cross-sectional view of the silicon microphone device packaging structure provided by the third embodiment of the present invention;

[0034] Figure 5 Schematic cross-sectional view of the silicon microphone device packaging structure provided by the fourth embodiment of the present invention;

[0035] Figure 6 Schematic external view of the silicon microphone device packaging structure provided by the fourth embodiment of the present invention;

[0036] Figure 7 Schematic cross-sectional view of the silicon microphone device packaging structure provided by the fifth embodiment of the present invention;

[0037] Figure 8 Schematic cross-sectional view of the silicon microphone device packaging structure provided by the sixth embodiment of the present invention.

[0038] Icons: 100 - Silicon microphone device packaging structure; 110 - Substrate; 111 - Rear sound hole; 112 - Sound transmission hole; 113 - Sound guiding channel; 120 - Silicon microphone chip; 130 - Control chip; 140 - Packaging cover plate; 150 - Inner packaging cover; 151 - First chamber; 152 - First sound guiding hole; 153 - Pressure transmission channel; 154 - Second sound guiding hole; 155 - Third sound guiding hole; 160 - Outer packaging cover; 161 - Second chamber; 162 - Drainage hole; 163 - First sound inlet hole; 164 - Third chamber; 165 - Sound transmission groove; 166 - Fourth chamber; 167 - Sound transmission through shell; 168 - Second sound inlet hole; 169 - Third sound inlet hole; 170 - Vibration diaphragm; 180 - Sound insulation board; 181 - First sound insulation part; 182 - Second sound insulation part; 183 - Fourth sound guiding hole; 190 - First partition board; 191 - Sound transmission opening; 193 - Second partition board. Detailed implementation manners

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and illustrated herein can be arranged and designed in various different configurations.

[0040] Accordingly, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0041] It should be noted that like reference numerals and letters denote like items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0042] In the description of the present invention, it should be noted that if terms such as "upper", "lower", "inner", "outer", etc. are used to indicate the orientation or positional relationship, it is based on the orientation or positional relationship shown in the drawings or the orientation or positional relationship in which the inventive product is usually placed during use. This is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0043] In addition, if terms such as "first", "second", etc. are used only for distinguishing descriptions, they cannot be understood as indicating or implying relative importance.

[0044] As disclosed in the background art, existing MEMS packaging products have the following disadvantages:

[0045] 1. Since the silicon vibration membrane on the MEMS chip is very sensitive to changes in sound pressure, and in the prior art, the external sound pressure directly contacts the silicon vibration membrane on the MEMS chip. Therefore, when the intensity of the sound pressure change exceeds a certain value, the silicon vibration membrane will rupture due to the impact of the high-intensity sound pressure, affecting the product reliability.

[0046] 2. In the design of existing MEMS silicon microphone products, sound enters the inside of the MEMS chip and the metal cover from a single hole / single direction. When the sound signal is very weak, the sound pressure signal becomes weaker, resulting in a decrease in the sensitivity and signal-to-noise ratio of the MEMS silicon microphone products.

[0047] 3. The design of existing MEMS silicon microphone products has no drainage structure, which easily leads to water accumulation, further affecting the product performance and even damaging the chip.

[0048] To solve the above problems, the present invention provides a silicon microphone device packaging structure and a preparation method thereof. It should be noted that, without conflict, the features in the embodiments of the present invention can be combined with each other.

[0049] First Embodiment

[0050] See Figure 1 and Figure 2, this embodiment provides a silicon microphone device packaging structure 100, which can increase the volume of the sound cavity, thereby improving the sensitivity and signal-to-noise ratio of the product, and can prevent the external boost from directly contacting the silicon diaphragm, thereby avoiding the sound pressure impact and affecting the product reliability. Finally, this application can also achieve drainage to prevent water accumulation inside the sound cavity.

[0051] The silicon microphone device packaging structure 100 provided in this embodiment includes a substrate 110, a silicon microphone chip 120, a control chip 130, and a packaging cover plate. The silicon microphone chip 120 and the control chip 130 are arranged on the substrate 110, and the packaging cover plate is arranged on the substrate 110 and covers the silicon microphone chip 120 and the control chip 130. Specifically, in this embodiment, the silicon microphone chip 120 refers to a MEMS chip, and the control chip 130 refers to an ASIC chip (ASIC, Application Specific Integrated Circuit), where the control chip 130 is used to control the silicon microphone chip 120. The specific control principle and working principle can refer to the existing MEMS packaging structure. And the packaging cover plate can be arranged on the substrate 110 by welding or bonding, and the tightness of the connection needs to be ensured, so as to better form the sound cavity of the silicon microphone chip 120.

[0052] The packaging cover plate includes an inner packaging cover 150 and an outer packaging cover 160. The inner packaging cover 150 has a first chamber 151, and both the silicon microphone chip 120 and the control chip 130 are accommodated in the first chamber 151. The outer packaging cover 160 covers the inner packaging cover 150 and has a second chamber 161. A first sound guiding hole 152 is provided on the side wall of the inner packaging cover 150. The first sound guiding hole 152 is used to conduct the first chamber 151 and the second chamber 161. A vibration rubber film 170 is also provided at the first sound guiding hole 152. The vibration rubber film 170 is used to block the first sound guiding hole 152 and transmit the sound pressure. A first sound inlet hole 163 communicating with the second chamber 161 is also provided on the outer packaging cover 160, and a drainage hole 162 communicating with the second chamber 161 is provided at the bottom of the outer packaging cover 160.

[0053] It should be noted that here the inner packaging cover 150 and the outer packaging cover 160 can be integrally provided and made of a metal cover body, which can well transmit the incoming sound. And the drainage hole 162 is provided at one side edge of the outer packaging cover 160, and the drainage hole 162 also corresponds to one side edge of the substrate 110, so that the water discharged from the drainage hole 162 can flow out unobstructed.

[0054] In this embodiment, the vibration film 170 is a thin film adhesive layer, which does not hinder the sound, but only blocks dust, water vapor, etc. The vibration film 170 blocks the first sound guide hole 152 and can transmit sound pressure. The water vapor entering from the first sound inlet hole 163 is blocked at the vibration film 170 and continues to fall downward into the drainage hole 162 at the bottom of the second chamber 161 for discharge, thereby achieving drainage, avoiding contact between water vapor and the silicon microphone chip 120, and avoiding water vapor accumulation in the second chamber 161, further ensuring the reliability of the product.

[0055] It should also be noted that the second chamber 161 is connected to the first chamber 151 here, which means that the sound can be freely transmitted between the second chamber 161 and the first chamber 151. Even if the vibrating rubber film 170 is provided, it will not affect the sound / sound pressure transmission between the second chamber 161 and the first chamber 151.

[0056] In this embodiment, the first chamber 151 and the second chamber 161 are connected and are used to constitute the front sound chamber of the silicon microphone chip 120. The external sound / sound pressure enters the second chamber 161 through the first sound inlet hole 163, and the vibration is transmitted to the first sound guide hole 152 in the second chamber 161, and is further transmitted inward by the vibrating film 170. In addition, the first sound guide hole 152 is arranged on the side wall of the inner packaging cover 150, thereby preventing the sound from directly entering the first chamber 151 and contacting the silicon microphone chip 120. The first chamber 151 and the second chamber 161 can play a buffering role, thereby preventing the silicon microphone chip 120 from being damaged due to sound pressure impact. In addition, the vibrating film 170 blocks the first sound guide hole 152 and can transmit sound pressure. The water vapor entering from the first sound inlet hole 163 is blocked at the vibrating film 170 and continues to fall downward into the drainage hole 162 at the bottom of the second chamber 161 for discharge, thereby achieving drainage, avoiding contact between water vapor and the silicon microphone chip 120, and avoiding accumulation of water vapor in the second chamber 161, further ensuring the reliability of the product.

[0057] It should be noted that the drainage hole 162 here is located at the bottom of the second chamber 161 and is connected to the external space. The drainage hole 162 here not only serves to drain water, but also serves as a sound intake hole. External sound / sound pressure can also enter the second chamber 161 through the drainage hole 162. Cooperating with the first sound intake hole 163, the range of the sound intake channel is expanded, and the sound reception range is also wider, which is conducive to improving the sound reception effect.

[0058] In this embodiment, the inner encapsulation cover 150 is further provided with a pressure transmission channel 153. The first sound guide hole 152 is located at the end of the pressure transmission channel 153 and communicates with the pressure transmission channel 153. A second sound guide hole 154 is provided at the top wall of the first chamber 151, and the second sound guide hole 154 communicates with the pressure transmission channel 153. Specifically, there may be multiple second sound guide holes 154, and the multiple second sound guide holes 154 are all located at the top wall of the first chamber 151 and all communicate with the pressure transmission channel 153. The vibration rubber film 170 is located at the end of the pressure transmission channel 153, which can prevent water vapor from entering the pressure transmission channel 153 and at the same time ensure that sound / sound pressure passes smoothly through the pressure transmission channel 153 to the first chamber 151. Here, the sound / sound pressure at the first sound guide hole 152 can be introduced into the second sound guide hole 154 through the pressure transmission channel 153 to realize the propagation of sound. At the same time, multiple pressure transmission channels 153 can be provided here, so as to increase the propagation area of sound / sound pressure and facilitate the smooth transmission of sound / sound pressure to the first chamber 151.

[0059] In this embodiment, a sound transmission groove 165 is provided at the top of the outer encapsulation cover 160, and the first sound inlet hole 163 is provided on the side wall and / or bottom wall of the sound transmission groove 165 that is joined to the second chamber 161. Specifically, in this embodiment, the first sound inlet hole 163 is provided on the side wall of the sound transmission groove 165, so that when the outer encapsulation cover 160 is adsorbed by a suction nozzle for bonding, the suction nozzle will not contaminate the first sound inlet hole 163, and foreign matter of the suction nozzle will not fall into the sound inlet hole to cause foreign matter in the cavity, and the silicon vibration film will vibrate and break. At the same time, it also prevents external impurities from directly entering the inside of the first sound inlet hole 163. In addition, by using side wall sound inlet, the first sound inlet hole 163 will not directly correspond to the inner encapsulation cover 150, so that the sound path is more tortuous, further playing a role in sound pressure buffering. Of course, in other preferred embodiments, the first sound inlet hole 163 may also be provided on the bottom wall of the sound transmission groove 165, or provided on both the side wall and the bottom wall at the same time.

[0060] In this embodiment, the outer encapsulation cover 160 further has a third chamber 164. A sound insulation board 180 is also provided inside the outer encapsulation cover 160. The sound insulation board 180 is used to divide the chamber between the inner encapsulation cover 150 and the outer encapsulation cover 160 into a second chamber 161 and a third chamber 164. A back sound hole 111 is also provided on the substrate 110, and the MEMS microphone chip 120 is covered on the back sound hole 111. The back sound hole 111 communicates with the third chamber 164. Specifically, in this embodiment, the sound insulation board 180 is located at the middle position of the outer encapsulation cover 160, and the two side edges of the sound insulation board 180 are respectively connected to the inner wall of the outer encapsulation cover 160 and the outer wall of the inner encapsulation cover 150, which can achieve a good sealing and isolation effect, so that the second chamber 161 and the third chamber 164 are isolated from each other. At the same time, the third chamber 164 communicates with the back sound hole 111, thereby forming the rear sound cavity of the MEMS microphone chip 120, which can greatly increase the volume of the rear sound cavity, and further improve the sensitivity and signal-to-noise ratio of the MEMS microphone chip 120.

[0061] It should be noted that here the sound insulation board 180 is also used to form the side wall of one side of the sound transmission groove 165, and the first sound inlet hole 163 is opened on the side wall of the other side. Specifically, the sound transmission groove 165 is located between the second chamber 161 and the third chamber 164. At the same time, the first sound inlet hole 163 is opened on the side wall joined to the second chamber 161, avoiding the situation where the external sound pressure directly contacts the silicon diaphragm on the MEMS microphone chip 120 in the prior art, and avoiding the influence of sound pressure impact on the performance of the MEMS microphone chip 120.

[0062] In this embodiment, a sound transmission hole 112 is also provided on the substrate 110. The sound transmission hole 112 is located between the inner encapsulation cover 150 and the outer encapsulation cover 160 and communicates with the third chamber 164. A sound guiding channel 113 is also provided inside the substrate 110. One end of the sound guiding channel 113 extends to the sound transmission hole 112, and the other end extends to the back sound hole 111, so that the back sound hole 111 communicates with the sound transmission hole 112. Specifically, the sound guiding channel 113 connects the sound transmission hole 112 and the back sound hole 111 in series, so that the bottom cavity of the MEMS microphone chip 120 and the third cavity can be connected as a whole. There can be multiple sound guiding channels 113, thereby further increasing the volume of the rear sound cavity.

[0063] It should also be noted that in this embodiment, the sound insulation board 180 is located in the middle of the outer encapsulation cover 160, so that most of the spaces of the second chamber 161 and the third chamber 164 are located above the inner encapsulation cover 150. This evenly distributed and stacked structure above the inner encapsulation cover 150 can avoid additionally setting a chamber to form the third chamber 164, thereby reducing the size of the outer encapsulation cover 160 and being beneficial to the miniaturization of the product.

[0064] This embodiment also provides a preparation method for the MEMS microphone device packaging structure 100 for preparing the foregoing MEMS microphone device packaging structure 100, which includes the following steps:

[0065] S1: Provide a substrate 110.

[0066] Specifically, the substrate 110 can be prepared in advance, and pads for bonding the control chip 130 can be provided on the substrate 110 in advance. Meanwhile, the sound transmission holes 112, the back sound holes 111, and the sound guiding channels 113 are prepared on the substrate 110 in advance.

[0067] S2: Mount the MEMS microphone chip 120 and the control chip 130 on the substrate 110.

[0068] Specifically, the MEMS microphone chip 120 and the control chip 130 can be mounted in the mounting area on the substrate 110 by using a conventional chip mounting process, where the MEMS microphone chip 120 covers the back sound holes 111. After the chip mounting is completed, wire bonding technology can be used to complete the electrical connection between the control chip 130 and the substrate 110, and between the control chip 130 and the MEMS microphone chip 120.

[0069] S3: Mount the encapsulation cover plate on the substrate 110.

[0070] Specifically, the encapsulation cover plate can be covered outside the MEMS microphone chip 120 and the control chip 130, and the mounting can be completed by using a welding process or an adhesive bonding process.

[0071] Among them, the encapsulation cover plate includes an inner encapsulation cover 150 and an outer encapsulation cover 160. The inner encapsulation cover 150 has a first chamber 151, and both the MEMS microphone chip 120 and the control chip 130 are accommodated in the first chamber 151. The outer encapsulation cover 160 covers the outside of the inner encapsulation cover 150 and has a second chamber 161. A first sound guiding hole 152 is provided on the side wall of the inner encapsulation cover 150, and the first sound guiding hole 152 is used to conduct the first chamber 151 and the second chamber 161. A vibration diaphragm 170 is also provided at the first sound guiding hole 152, and the vibration diaphragm 170 is used to block the first sound guiding hole 152 and transmit sound pressure. A first sound inlet hole 163 communicating with the second chamber 161 is also provided on the outer encapsulation cover 160, and a drain hole 162 communicating with the second chamber 161 is provided at the bottom of the outer encapsulation cover 160.

[0072] It should be noted that in this embodiment, after the operation of mounting the encapsulation cover plate is completed, flipping and cutting are required, and the cutting path corresponds to the edge of the outer encapsulation cover 160. Specifically, the cutting path corresponds to the position of the drain hole 162, so that after cutting, one side edge of the encapsulation cover plate can correspond to one side edge of the substrate 110, and the side edge of the encapsulation cover plate with the drain hole 162 corresponds to the edge of the substrate 110, which is more conducive to the drainage of the drain hole 162. Among them, the edge of the outer encapsulation cover 160 can be used as a cutting stop layer, which is conducive to achieving precise cutting.

[0073] In summary, this embodiment provides a silicon microphone device packaging structure 100 and a manufacturing method thereof. The packaging cover plate is disposed outside the silicon microphone chip 120 and the control chip 130. Meanwhile, the inner packaging cover 150 has a first chamber 151, and the outer packaging cover 160 has a second chamber 161. The first chamber 151 and the second chamber 161 are connected through a first sound guiding hole 152, thereby increasing the sound cavity space of the silicon microphone chip 120 and improving the sensitivity and signal-to-noise ratio of the silicon microphone chip 120. At the same time, in this embodiment, sound enters through the first sound inlet hole 163, and the first sound guiding hole 152 is disposed on the side wall of the inner packaging cover 150, thereby preventing sound from directly entering the first chamber 151 and contacting the silicon microphone chip 120. The first chamber 151 and the second chamber 161 can play a buffering role, thereby preventing the silicon microphone chip 120 from being damaged due to sound pressure impact. In addition, a vibration diaphragm 170 is disposed at the first sound guiding hole 152. The vibration diaphragm 170 blocks the first sound guiding hole 152 and can transmit sound pressure. The water vapor entering from the first sound inlet hole 163 is blocked at the vibration diaphragm 170 and continues to fall downward into the drain hole 162 at the bottom of the second chamber 161 and is discharged, thereby achieving drainage, preventing the water vapor from contacting the silicon microphone chip 120, and also preventing the water vapor from accumulating in the second chamber 161, further ensuring the reliability of the product.

[0074] Second Embodiment

[0075] See Figure 3 , this embodiment provides a silicon microphone device packaging structure. Its basic structure, principle, and the resulting technical effects are the same as those of the first embodiment. For a brief description, for the parts not mentioned in this embodiment, reference can be made to the corresponding content in the first embodiment.

[0076] In this embodiment, the outer packaging cover 160 is disposed on the inner packaging cover 150. The inner packaging cover 150 has a first chamber 151, and the outer packaging cover 160 has a second chamber 161 and a third chamber 164. A third sound guiding hole 155 is disposed on the side wall of the inner packaging cover 150 that is joined to the third chamber 164. The third chamber 164 is connected to the first chamber 151 through the third sound guiding hole 155.

[0077] In this embodiment, there may also be multiple third sound guiding holes 155. Multiple third sound guiding holes 155 all connect the first chamber 151 and the third chamber 164 at the same time, increasing the range of the sound pressure entry channel and achieving the connection between the front sound cavity and the rear sound cavity. Sound enters the silicon diaphragm from multiple directions simultaneously, improving the sensitivity, signal-to-noise ratio, and frequency response performance of the silicon microphone chip 120. Moreover, the connection between the front sound cavity and the rear sound cavity can reduce the resonance between the front and rear sound cavities, avoiding the influence of resonance on the sound collection of the silicon microphone chip 120.

[0078] Third Embodiment

[0079] SeeFigure 4 , this embodiment provides a packaging structure for a silicon microphone device. Its basic structure, principle, and the resulting technical effects are the same as those of the first embodiment or the second embodiment. For a brief description, for the parts not mentioned in this embodiment, reference can be made to the corresponding content in the first embodiment or the second embodiment.

[0080] In this embodiment, a third sound guiding hole 155 is provided on the side wall of the inner packaging cover 150 that is joined to the third chamber 164. The third chamber 164 is connected to the first chamber 151 through the third sound guiding hole 155.

[0081] In this embodiment, the second sound guiding hole 154 is used to conduct the first chamber 151 and the pressure transmission channel 153, and the second sound guiding hole 154 has a single-hole structure. The third sound guiding hole 155 is used to conduct the second chamber 161 and the third chamber 164, and the third sound transmission structure is also a single-hole structure.

[0082] In this embodiment, the width of the third sound guiding hole 155 is greater than the width of the silicon microphone chip 120, and the width of the second sound guiding hole 154 is greater than the width of the silicon microphone chip 120. Specifically, the width of the second sound guiding hole 154 is W1, the width of the third sound guiding hole 155 is W2, and the width of the silicon microphone chip 120 is W3, where W1 > W2 > W3. As shown in the figure, in this embodiment, the second sound guiding hole 154 extends to the inner side wall of the inner packaging cover 150, ensuring a larger sound inlet space. At the same time, the third sound guiding hole 155 is also relatively wide, which can also ensure a larger sound inlet space and improve the connectivity between the front sound cavity and the rear sound cavity.

[0083] It should be noted that the width W1 of the second sound guiding hole 154 in this embodiment refers to the width of the second sound guiding hole 154 in the horizontal direction. The width W2 of the third sound guiding hole 155 refers to the width of the third sound guiding hole 155 in the vertical direction. The width of the silicon microphone chip 120 refers to the width of the silicon microphone chip 120 in the horizontal direction.

[0084] In this embodiment, by adopting a single-hole sound transmission structure and the sizes of the second sound guiding hole 154 and the third sound guiding hole 155 are both larger than the size of the silicon microphone chip 120, the sound / sound pressure transmission area and the sound cavity volume can be increased in a larger range, thereby realizing the internal sound transmission function and improving the sensitivity, signal-to-noise ratio, and frequency response performance of the silicon microphone chip 120.

[0085] Fourth Embodiment

[0086] See Figure 5 and Figure 6 , this embodiment provides a packaging structure 100 for a silicon microphone device. Its basic structure, principle, and the resulting technical effects are the same as those of the first embodiment. For a brief description, for the parts not mentioned in this embodiment, reference can be made to the corresponding content in the first embodiment.

[0087] In this embodiment, the sound insulation board 180 includes a first sound insulation part 181 and a second sound insulation part 182 which are integrally provided. The first sound insulation part 181 is connected to the inner wall of the outer encapsulation cover 160, and the second sound insulation part 182 is connected to the substrate 110. A fourth chamber 166 is formed between the second sound insulation part 182 and the inner encapsulation cover 150, and the fourth chamber 166 communicates with the second chamber 161. Specifically, the first sound insulation part 181 is arranged in the vertical direction, and the second sound insulation part 182 is in a bent state and extends from the bottom end of the first sound insulation part 181 to the surface of the substrate 110, so as to be able to divide the space between the inner encapsulation cover 150 and the outer encapsulation cover 160 into a second chamber 161, a third chamber 164 and a fourth chamber 166.

[0088] In this embodiment, a first partition board 190 is further arranged in the third chamber 164. One end of the first partition board 190 is connected to the sound insulation board 180 and bends and extends to the substrate 110. The first partition board 190 is used to divide the third chamber 164 into two sub-cavities. A sound transmission opening 191 is further arranged at one end of the first partition board 190 close to the substrate 110, and the sound transmission opening 191 is used to communicate the two sub-cavities. Specifically, one end of the first partition board 190 is connected to the first isolation part, the other end is connected to the substrate 110 or suspended above the substrate 110, and a sound transmission opening 191 is formed on the first partition board 190, so as to conduct the two sub-cavities.

[0089] It should be noted that here the third chamber 164 adopts a multi-layer structure, which can divide the rear sound cavity space, thereby reducing the resonance phenomenon of the rear sound cavity. At the same time, it also avoids the situation that the silicon vibration film is broken due to excessive sound pressure, and improves the sensitivity, signal-to-noise ratio and frequency response performance of the silicon microphone chip 120.

[0090] In this embodiment, the height of the second chamber 161 should be the same as that of the third chamber 164, that is, the top wall of the second chamber 161 is flush with the top wall of the upper sub-cavity, so as to ensure the consistency of the appearance. At the same time, it also further increases the volume of the second chamber 161, so that the volume of the front sound cavity is further enlarged.

[0091] In this embodiment, a third sound guide hole 155 is arranged on the side wall of the inner encapsulation cover 150 that is joined to the fourth chamber 166. The fourth chamber 166 communicates with the first chamber 151 through the third sound guide hole 155. By arranging the third sound guide hole 155, the fourth chamber 166, the second chamber 161 and the first chamber 151 can be connected as a whole and jointly form the front sound cavity of the silicon microphone chip 120, so as to realize the increase of the volume of the front sound cavity.

[0092] In this embodiment, a sound transmission groove 165 is provided on the outer encapsulation cover 160. The first sound inlet holes 163 are provided on the side wall and the bottom wall of the sound transmission groove 165 that are joined to the second chamber 161, and each first sound inlet hole 163 communicates with the second chamber 161. Specifically, a plurality of first sound inlet holes 163 can be provided on the side wall of the sound transmission groove 165 here. Preferably, two first sound inlet holes 163 are provided. By providing a plurality of first sound inlet holes 163, the range of the sound inlet channel can be improved, ensuring a better sound collection effect.

[0093] In this embodiment, the sound transmission groove 165 penetrates through to the surface of the inner encapsulation cover 150, and a sound transmission through-shell 167 is further provided on the outer encapsulation cover 160. The sound transmission through-shell is located within the sound transmission groove 165, and both ends of the sound transmission through-shell 167 are respectively in conduction with the second chamber 161 and the fourth chamber 166. A second sound inlet hole 168 is provided at the bottom of the sound transmission through-shell 167. In this embodiment, a second sound inlet hole 168 can also be provided at the top of the sound transmission through-shell 167. Specifically, by providing the second sound inlet hole 168, the range of the sound inlet channel can be further improved, ensuring a better sound collection effect. At the same time, it can also achieve sound inlet through the second sound inlet hole 168 when the side of the sound transmission groove 165 is blocked or obstructed, thereby making the applicability of this encapsulated product wider.

[0094] It should be noted that the sound transmission through-shell 167 here can be single or multiple and arranged at intervals.

[0095] In this embodiment, a second partition plate 193 is further provided in the second chamber 161. A through-hole is provided at the end of the second partition plate 193. By providing the second partition plate 193, it can also divide the second chamber 161 into two sub-cavities, and both sub-cavities are in conduction with the outside through the first sound inlet holes 163. By providing the second partition plate 193 here, the front sound cavity space can be divided, thereby reducing the resonance phenomenon of the front sound cavity. At the same time, it also avoids the situation where the silicon vibration membrane ruptures due to excessive sound pressure, improving the sensitivity, signal-to-noise ratio, and frequency response performance of the silicon microphone chip 120.

[0096] Fifth Embodiment

[0097] See Figure 7 , this embodiment provides a silicon microphone device encapsulation structure 100, whose basic structure, principle, and the resulting technical effects are the same as those of the first embodiment or the fourth embodiment. For a brief description, for the parts not mentioned in this embodiment, reference can be made to the corresponding content in the first embodiment or the fourth embodiment.

[0098] In this embodiment, the sound insulation board 180 includes a first sound insulation part 181 and a second sound insulation part 182 which are integrally provided. The first sound insulation part 181 is connected to the inner wall of the outer encapsulation cover 160, and the second sound insulation part 182 is connected to the substrate 110. A fourth chamber 166 is formed between the second sound insulation part 182 and the inner encapsulation cover 150, and the fourth chamber 166 communicates with the second chamber 161. Specifically, the first sound insulation part 181 is arranged in the vertical direction, and the second sound insulation part 182 is in a bent state and extends from the bottom end of the first sound insulation part 181 to the surface of the substrate 110, so as to be able to divide the space between the inner encapsulation cover 150 and the outer encapsulation cover 160 into a second chamber 161, a third chamber 164, and a fourth chamber 166.

[0099] In this embodiment, no partition structure is provided in the third chamber 164, and the third chamber 164 is a single-chamber structure. Moreover, a third sound guiding hole 155 is provided on the side wall of the inner encapsulation cover 150 that is joined to the fourth chamber 166, and the fourth chamber 166 communicates with the first chamber 151 through the third sound guiding hole 155. By providing the third sound guiding hole 155, the fourth chamber 166, the second chamber 161, and the first chamber 151 can be connected as a whole and jointly form the front sound cavity of the silicon microphone chip 120, thus realizing an increase in the volume of the front sound cavity.

[0100] In this embodiment, the sound transmission groove 165 penetrates through to the surface of the inner encapsulation cover 150, and a sound transmission through-shell 167 is further provided on the outer encapsulation cover 160. The sound transmission through-shell is located in the sound transmission groove 165, and both ends of the sound transmission through-shell 167 are respectively communicated with the second chamber 161 and the fourth chamber 166. A second sound inlet hole 168 is provided at the bottom of the sound transmission through-shell 167. In this embodiment, a second sound inlet hole 168 can also be provided at the top of the sound transmission through-shell 167. Specifically, by providing the second sound inlet hole 168, the range of the sound inlet channel can be further improved to ensure a better sound collection effect. At the same time, it can also realize sound inlet through the second sound inlet hole 168 when the side of the sound transmission groove 165 is blocked or obstructed, so that the applicability of this encapsulated product is wider.

[0101] In this embodiment, a third sound inlet hole 169 is provided on the first sound insulation part 181, and the third sound inlet hole 169 communicates with the third chamber 164. Specifically, the first sound insulation part 181 is used to form one side wall of the sound transmission groove 165, that is, a third sound inlet hole 169 is provided on the side wall of the sound transmission groove 165 that is joined to the third chamber 164, and sound inlet structures are provided on the opposite side walls of the sound transmission groove 165, realizing a double-side wall sound inlet structure. By providing the first sound inlet hole 163 and the third sound inlet hole 169, sound can be input into the front sound cavity and the rear sound cavity respectively, improving the product performance.

[0102] In summary, for the silicon microphone device packaging structure 100 provided in this embodiment, the first chamber 151, the second chamber 161, and the fourth chamber 166 communicate with each other and constitute the front sound cavity of the silicon microphone chip 120, and the third chamber 164 constitutes the rear sound cavity of the silicon microphone chip 120. By adopting the double-side wall sound inlet structure on the sound transmission groove 165, sound can enter the rear sound cavity through the third sound inlet hole 169, and enter the front sound cavity through the first sound inlet hole 163 and the second sound inlet hole 168, realizing the simultaneous conduction of sound to the front and back surfaces of the silicon vibration membrane on the silicon microphone chip 120, thereby further improving the product performance and enhancing its sensitivity and signal-to-noise ratio.

[0103] Sixth Embodiment

[0104] Refer to Figure 8 , this embodiment provides a silicon microphone device packaging structure 100, whose basic structure, principle, and the resulting technical effects are the same as those of the first embodiment or the fifth embodiment. For a brief description, for the parts not mentioned in this embodiment, reference can be made to the corresponding content in the first embodiment or the fifth embodiment.

[0105] In this embodiment, the sound insulation board 180 includes a first sound insulation part 181 and a second sound insulation part 182 which are integrally arranged. The first sound insulation part 181 is connected to the inner wall of the outer packaging cover 160, and the second sound insulation part 182 is connected to the substrate 110. Moreover, a fourth chamber 166 is formed between the second sound insulation part 182 and the inner packaging cover 150, and the fourth chamber 166 communicates with the second chamber 161. Specifically, the first sound insulation part 181 is arranged in the vertical direction, and the second sound insulation part 182 is in a bent state and extends from the bottom end of the first sound insulation part 181 to the surface of the substrate 110, so as to be able to divide the space between the inner packaging cover 150 and the outer packaging cover 160 into the second chamber 161, the third chamber 164, and the fourth chamber 166. In this embodiment, no partition structure is provided in the third chamber 164, and the third chamber 164 is a single-chamber structure. Also, a third sound guiding hole 155 is provided on the side wall of the inner packaging cover 150 that is joined to the fourth chamber 166, and the fourth chamber 166 communicates with the first chamber 151 through the third sound guiding hole 155. By providing the third sound guiding hole 155, the fourth chamber 166, the second chamber 161, and the first chamber 151 can be connected as a whole and jointly constitute the front sound cavity of the silicon microphone chip 120, thereby realizing an increase in the volume of the front sound cavity.

[0106] In this embodiment, a fourth sound guiding hole 183 is provided on the second sound insulation part 182, and the third chamber 164 communicates with the fourth chamber 166 through the fourth sound guiding hole 183. Specifically, the connection between the third chamber 164 and the fourth chamber 166 is realized through the fourth sound guiding hole 183, thereby realizing the conduction between the front sound cavity and the rear sound cavity. Similarly, it can also realize the simultaneous conduction of sound to the front and back surfaces of the silicon vibration membrane on the silicon microphone chip 120, thereby improving the product performance.

[0107] The silicon microphone device packaging structure 100 provided in this embodiment can improve the range of the sound pressure entering the channel through multiple sound inlet hole structures and sound guiding hole structures, and realizes the connection between the front sound cavity and the rear sound cavity. Sound enters the silicon diaphragm simultaneously from multiple directions, improving the sensitivity, signal-to-noise ratio, and frequency response performance of the silicon microphone chip 120. Moreover, since the front sound cavity and the rear sound cavity are connected, the resonance between the front and rear sound cavities can be minimized, avoiding the influence of resonance on the sound collection of the silicon microphone chip 120.

[0108] As described above, the above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A silicon microphone device packaging structure, characterized in that, it includes: a substrate; a silicon microphone chip and a control chip disposed on the substrate; a packaging cover plate disposed on the substrate and covering the silicon microphone chip and the control chip; wherein, the packaging cover plate includes an inner packaging cover and an outer packaging cover, the inner packaging cover has a first chamber, the silicon microphone chip and the control chip are both accommodated in the first chamber, the outer packaging cover covers the inner packaging cover and has a second chamber, a first sound guiding hole is provided on the side wall of the inner packaging cover, the first sound guiding hole is used to conduct the first chamber and the second chamber, a vibration diaphragm is further provided at the first sound guiding hole, the vibration diaphragm is used to block the first sound guiding hole and transmit sound pressure, a first sound inlet hole communicating with the second chamber is further provided on the outer packaging cover, and a drain hole communicating with the second chamber is further provided at the bottom of the outer packaging cover; the inner packaging cover is further provided with a pressure transmission channel, the first sound guiding hole is located at the end of the pressure transmission channel and communicates with the pressure transmission channel, a second sound guiding hole is provided at the top wall of the first chamber, and the second sound guiding hole communicates with the pressure transmission channel.

2. The silicon microphone device packaging structure according to claim 1, characterized in that, a sound transmission groove is provided at the top of the outer packaging cover, and the first sound inlet hole is provided on the side wall and / or the bottom wall of the sound transmission groove that is joined to the second chamber.

3. The silicon microphone device packaging structure according to claim 2, characterized in that, the outer packaging cover further has a third chamber, a sound insulation board is further provided inside the outer packaging cover, the sound insulation board is used to divide the chamber between the inner packaging cover and the outer packaging cover into a second chamber and a third chamber, a back sound hole is further provided on the substrate, the silicon microphone chip covers the back sound hole, and the back sound hole communicates with the third chamber.

4. The silicon microphone device packaging structure according to claim 3, characterized in that, a sound transmission hole is further provided on the substrate, the sound transmission hole is located between the inner packaging cover and the outer packaging cover and communicates with the third chamber, a sound guiding channel is further provided inside the substrate, one end of the sound guiding channel extends to the sound transmission hole, and the other end extends to the back sound hole to enable the back sound hole to communicate with the sound transmission hole.

5. The silicon microphone device packaging structure according to claim 3, characterized in that, a third sound guiding hole is provided on the side wall of the inner packaging cover that is joined to the third chamber, and the third chamber communicates with the first chamber through the third sound guiding hole.

6. The silicon microphone device packaging structure according to claim 5, characterized in that, the width of the third sound guiding hole is greater than the width of the silicon microphone chip, and the width of the second sound guiding hole is greater than the width of the silicon microphone chip.

7. The silicon microphone device packaging structure according to claim 3, characterized in that, A first partition board is further disposed in the third chamber. One end of the first partition board is connected to the sound insulation board and is bent and extended to the substrate. The first partition board is used to divide the third chamber into two sub-cavities. A sound transmission opening is further disposed at one end of the first partition board close to the substrate, and the sound transmission opening is used to communicate the two sub-cavities.

8. The silicon microphone device packaging structure according to claim 3 or 7, characterized in that the sound insulation board includes an integrally provided first sound insulation part and a second sound insulation part. The first sound insulation part is connected to the inner wall of the outer packaging cover, and the second sound insulation part is connected to the substrate. A fourth chamber is formed between the second sound insulation part and the inner packaging cover, and the fourth chamber communicates with the second chamber.

9. The silicon microphone device packaging structure according to claim 8, characterized in that a third sound guiding hole is disposed on the side wall of the inner packaging cover that is joined to the fourth chamber, and the fourth chamber communicates with the first chamber through the third sound guiding hole.

10. The silicon microphone device packaging structure according to claim 8, characterized in that the sound transmission groove penetrates to the surface of the inner packaging cover, and a sound transmission through shell is further disposed on the outer packaging cover. The sound transmission through shell is located in the sound transmission groove, and both ends of the sound transmission through shell are respectively communicated with the second chamber and the fourth chamber. A second sound inlet hole is disposed at the bottom of the sound transmission through shell.

11. The silicon microphone device packaging structure according to claim 10, characterized in that a third sound inlet hole is disposed on the first sound insulation part, and the third sound inlet hole communicates with the third chamber.

12. The silicon microphone device packaging structure according to claim 10, characterized in that a fourth sound guiding hole is disposed on the second sound insulation part, and the third chamber communicates with the fourth chamber through the fourth sound guiding hole.

13. A preparation method of a silicon microphone device packaging structure, characterized in that it is used to prepare the silicon microphone device packaging structure according to any one of claims 1-12, and the preparation method includes: providing a substrate; mounting a silicon microphone chip and a control chip on the substrate; mounting a packaging cover plate on the substrate, and the packaging cover plate covers the silicon microphone chip and the control chip; wherein, the packaging cover plate includes an inner packaging cover and an outer packaging cover. The inner packaging cover has a first chamber, and both the silicon microphone chip and the control chip are accommodated in the first chamber. The outer packaging cover covers the outer packaging cover and has a second chamber. A first sound guiding hole is disposed on the side wall of the inner packaging cover, and the first sound guiding hole is used to conduct the first chamber and the second chamber. A vibration rubber film is further disposed at the first sound guiding hole, and the vibration rubber film is used to block the first sound guiding hole and transmit sound pressure. A first sound inlet hole communicated with the second chamber is further disposed on the outer packaging cover, and a drain hole communicated with the second chamber is further disposed at the bottom of the outer packaging cover.

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