Mems package structure with thermal expansion coefficient matching

Abstract

The application provides a thermal expansion coefficient matched MEMS packaging structure, and belongs to the technical field of semiconductors.The thermal expansion coefficient matched MEMS packaging structure comprises an outer shell, a mounting substrate, a thermal expansion transition layer and a MEMS device, the outer shell has an inner cavity, the mounting substrate is arranged in the inner cavity, the mounting substrate is fixed to the bottom wall of the inner cavity, the thermal expansion transition layer is arranged between the mounting substrate and the bottom wall of the inner cavity, and the MEMS device is arranged on the top of the mounting substrate, and the bottom of the MEMS device is provided with a connecting structure connected with the mounting substrate.The thermal expansion coefficient matched MEMS packaging structure provided by the application can establish a thermal expansion buffer and a transition area between two different materials by arranging the thermal expansion transition layer between the outer shell and the mounting substrate, stress is avoided from being concentrated on a single connecting interface when the temperature changes, and additional thermal stress is reduced.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor technology, and specifically relates to a MEMS packaging structure with a matching coefficient of thermal expansion. Background Technology

[0002] MEMS (Micro Electro Mechanical Systems) packaging is a crucial step in the MEMS R&D process, determining the reliability and cost of MEMS devices and being key to their miniaturization. The MEMS device packaging structure primarily serves to secure, protect, and connect the devices, ensuring they maintain normal operation under external environmental conditions and meet installation, usage, and reliability requirements.

[0003] Existing MEMS device packaging structures typically include a housing and a mounting base. Different structures use different materials. For example, the housing is usually made of Kovar alloy, while the mounting base is usually made of ceramic material. The two materials are different, and the way the atoms are bonded in the materials is different. Therefore, when the temperature rises, the atomic amplitudes of the different materials are different, that is, the coefficients of thermal expansion are different.

[0004] Different coefficients of thermal expansion can easily lead to additional thermal stress and localized deformation under mutual constraint. This thermal mismatch can not only cause reliability problems such as stress concentration, cracking, debonding, and delamination in the adhesive layer, solder joints, or connection interfaces, but also cause stress to be further transmitted to the sensitive structure of MEMS devices, causing defects such as zero-bias drift. Under temperature cycling conditions, the above effects may further accumulate, leading to a decrease in the long-term stability of the device, and in severe cases, even causing package failure. Summary of the Invention

[0005] This invention provides a MEMS packaging structure with a matching coefficient of thermal expansion, aiming to solve the technical problem that existing packaging structures are prone to reliability issues due to different materials and their different coefficients of thermal expansion, which can lead to zero-bias drift and, in the long run, packaging failure.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: to provide a MEMS packaging structure with matched thermal expansion coefficient, comprising: The outer shell has an inner cavity; A mounting base plate is disposed within the inner cavity, and the mounting base plate is fixed to the bottom wall of the inner cavity; A thermal expansion transition layer is disposed between the mounting substrate and the bottom wall of the inner cavity; A MEMS device is disposed on the top of the mounting substrate, and the bottom of the MEMS device is provided with a connection structure for connecting to the mounting substrate.

[0007] In one possible implementation, the thermal expansion transition layer includes: The annular body is fixed to the bottom wall of the inner cavity; A support member is embedded in the annular body, the top end of the support member is flush with the top surface of the annular body, and is fixedly connected to the bottom of the mounting base plate. The annular body is made of a different material than the support member.

[0008] In one possible implementation, the annular body is made of rubber, and the support is made of metal or ceramic.

[0009] In one possible implementation, the top of the annular body is provided with a groove, the mounting base plate is engaged with the groove, and the support member is located within the projected area of ​​the groove.

[0010] In one possible implementation, the thermal expansion transition layer includes a metal layer, a rubber layer, and a ceramic layer arranged sequentially from bottom to top.

[0011] In one possible implementation, the rubber layer has through holes running vertically through it, and the through holes are used to fill the connecting adhesive.

[0012] In one possible implementation, the housing includes: A housing having the inner cavity, the top of the housing having an opening; A cap is detachably attached to the opening.

[0013] In one possible implementation, the inner wall of the housing is provided with a positioning rib that abuts against the outer periphery of the mounting base plate.

[0014] In one possible implementation, the positioning rib has a guide groove, and the bottom end of the cover is provided with a guide post, the guide post being in clearance fit with the guide groove.

[0015] In one possible implementation, the connection structure includes a plurality of spaced rubber pillars, and the bottom of the MEMS device is provided with a positioning block for extending into the gap between adjacent rubber pillars.

[0016] The solution described in this application, compared with the prior art, establishes a thermal expansion buffer and transition region between two different materials by setting a thermal expansion transition layer between the housing and the mounting substrate. This avoids stress concentration at a single connection interface during temperature changes, thereby reducing additional thermal stress. The thermal expansion transition layer can absorb or disperse the deformation caused by the difference in the thermal expansion coefficients of the materials, reducing the local stress peak in the connection area between the mounting substrate and the housing. Therefore, it helps to reduce the risk of cracking, debonding, and delamination of the adhesive layer, solder joint, or interface, and improves the reliability of the package connection. The MEMS device is disposed on top of the mounting substrate, and the mounting substrate and the housing are separated by the thermal expansion transition layer, so that the thermomechanical stress from the housing is attenuated in the transmission path, which is beneficial to protect the sensitive internal structure of the MEMS device and reduce stress disturbance.

[0017] The connection structure can also serve as a stress transfer adjustment point between the MEMS device and the mounting substrate. When the housing, mounting substrate, and MEMS device undergo different degrees of thermal expansion or contraction under temperature changes, the connection structure can buffer, absorb, or disperse the relative displacement and local deformation between them, thereby reducing the degree to which thermal stress on the mounting substrate is directly transferred to the sensitive structure of the MEMS device. Attached Figure Description

[0018] Figure 1 An exploded view of a MEMS packaging structure with matched thermal expansion coefficients provided in an embodiment of the present invention. Figure 2 A top view schematic diagram of a MEMS packaging structure with matched thermal expansion coefficient provided in an embodiment of the present invention; Figure 3 For along Figure 2 Schematic diagram of the cross-sectional structure along line AA; Figure 4 For along Figure 3 Schematic diagram of the cross-sectional structure of the middle BB line; Figure 5 This is a top view schematic diagram of the shell and thermal expansion transition layer used in one embodiment of the present invention; Figure 6 A cross-sectional schematic diagram of a MEMS packaging structure with matched thermal expansion coefficient provided in another embodiment of the present invention; Figure 7 This is a schematic diagram of the exploded structure of the thermal expansion transition layer used in another embodiment of the present invention.

[0019] Explanation of reference numerals in the attached figures: 10-Outer shell; 11-Housing shell; 12-Cap; 13-Positioning rib; 14-Guide post; 15-Guide groove; 20 - Mounting substrate; 30 - Thermal expansion transition layer; 31 - Annular body; 32 - Support component; 33 - Groove; 34 - Metal layer; 35 - Rubber layer; 351 - Through hole; 36 - Ceramic layer; 40 - MEMS devices; 41 - Positioning blocks; 50 - Connection structure; 51 - Rubber column; 52 - Adhesive layer. Detailed Implementation

[0020] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0021] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. The following description of at least one exemplary embodiment is actually illustrative only and is in no way intended to limit this application or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0022] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0023] Please refer to the following: Figures 1 to 7 The present invention will now describe the MEMS packaging structure with matching thermal expansion coefficient.

[0024] The thermal expansion coefficient-matched MEMS packaging structure includes a shell 10, a mounting substrate 20, a thermal expansion transition layer 30, and a MEMS device 40.

[0025] The housing 10 has an inner cavity for accommodating the mounting substrate 20, the thermal expansion transition layer 30, and the MEMS device 40, and providing a relatively enclosed mounting and protection space for the MEMS device 40. The housing 10 may be made of a metallic material, such as Kovar alloy, stainless steel, or aluminum alloy.

[0026] The mounting substrate 20 is disposed within the inner cavity of the housing 10 and fixed to the bottom wall of the inner cavity. The mounting substrate 20 is used to support the MEMS device 40 and can also serve as an electrical connection deployment platform. The mounting substrate 20 can be made of ceramic substrate, glass substrate, silicon substrate or composite material substrate.

[0027] A thermal expansion transition layer 30 is disposed between the mounting substrate 20 and the bottom wall of the inner cavity. The thermal expansion transition layer 30 is used to establish a transition relationship of thermal expansion coefficient between the outer shell 10 and the mounting substrate 20, thereby reducing thermal mismatch caused by the difference in materials between the two. Specifically, when the external temperature changes, the thermal expansion transition layer 30 can buffer, absorb or disperse the relative deformation between the outer shell 10 and the mounting substrate 20, so as to reduce the direct transmission of thermal stress to the mounting substrate 20 and the MEMS device 40 above it.

[0028] MEMS device 40 is disposed on the top of mounting substrate 20. MEMS device 40 can be a sensitive chip in MEMS gyroscope, MEMS accelerometer, or inertial measurement unit. The bottom of MEMS device 40 is provided with a connection structure 50 for connecting to mounting substrate 20. This connection structure 50 is used to achieve a fixed connection between MEMS device 40 and mounting substrate 20 and to further reduce stress coupling.

[0029] In practice, the thermal expansion transition layer 30 can be fixed to the bottom wall of the inner cavity of the housing 10 first, then the mounting substrate 20 can be mounted on the thermal expansion transition layer 30, and finally the MEMS device 40 can be mounted on top of the mounting substrate 20 through the connecting structure 50. Through the above-mentioned hierarchical arrangement, the housing 10, the thermal expansion transition layer 30, the mounting substrate 20 and the MEMS device 40 are arranged vertically in sequence to form a stress transmission path from the packaging housing to the sensitive device. The thermal expansion transition layer 30 is located in the middle of this stress transmission path, playing a role in thermal stress transition and isolation.

[0030] The thermal expansion coefficient-matched MEMS packaging structure provided in this embodiment, compared with the prior art, establishes a thermal expansion buffer and transition region between two different materials by setting a thermal expansion transition layer 30 between the housing 10 and the mounting substrate 20. This avoids stress concentration at a single connection interface when the temperature changes, thereby reducing additional thermal stress. The thermal expansion transition layer 30 can absorb or disperse the deformation caused by the difference in the thermal expansion coefficients of the materials, reducing the local stress peak in the connection area between the mounting substrate 20 and the housing 10. Therefore, it helps to reduce the risk of cracking, debonding, and delamination of the adhesive layer, solder joint, or interface, and improves the reliability of the package connection. The MEMS device 40 is disposed on top of the mounting substrate 20, and the mounting substrate 20 and the housing 10 are separated by the thermal expansion transition layer 30, so that the thermomechanical stress from the housing 10 is attenuated in the transmission path, which is beneficial to protect the sensitive internal structure of the MEMS device 40 and reduce stress disturbance.

[0031] The connection structure 50 can also serve as a stress transmission adjustment point between the MEMS device 40 and the mounting substrate 20. When the housing 10, the mounting substrate 20 and the MEMS device 40 undergo different degrees of thermal expansion or contraction under temperature change conditions, the connection structure 50 can buffer, absorb or disperse the relative displacement and local deformation between them, thereby reducing the degree to which the thermal stress on the mounting substrate 20 is directly transmitted to the sensitive structure of the MEMS device 40.

[0032] In some embodiments, a specific implementation of the above-mentioned thermal expansion transition layer may employ, as follows: Figure 5 The structure shown. The thermal expansion transition layer 30 includes an annular body 31 and a support member 32.

[0033] The annular body 31 is fixed to the bottom wall of the inner cavity of the outer shell 10. The annular body 31 is ring-shaped and can enclose a hollow area. The annular body 31 can be installed on the bottom wall of the inner cavity by means of bonding, welding or other methods to form a transition support structure between the outer shell 10 and the mounting base plate 20.

[0034] The support member 32 is embedded in the annular body 31, with its top end flush with the top surface of the annular body 31, and is fixedly connected to the bottom of the mounting base 20. After the mounting base 20 is installed, its bottom can simultaneously cooperate with the top area of ​​the annular body 31 and the top area of ​​the support member 32 to form a relatively stable support structure.

[0035] Specifically, the annular body 31 serves as an outer support and thermal stress transition structure, while the support member 32 serves as a central load-bearing and support structure. This composite structure differentiates the functions of different regions of the thermal expansion transition layer 30. The annular body 31 primarily connects to the outer shell 10 and absorbs the thermal deformation from the outer shell 10, while the support member 32 provides effective support and connection to the mounting base plate 20. This ensures the stability of the mounting base plate 20 while dispersing and transitioning the thermal stress transmitted from the outer shell 10.

[0036] It should be noted that the annular area of ​​the annular body 31 is the same as the outer contour of the mounting substrate 20, and the outer contour of the annular body 31 is larger than the outer contour of the mounting substrate 20, while the inner contour of the annular body 31 is smaller than the inner contour of the mounting substrate 20. During the production of the annular body 31, holes corresponding to the support member 32 need to be machined. The support member 32 and the holes on the annular body 31 are fitted with a clearance fit and can be fixed by adhesive.

[0037] In this embodiment, the thermal expansion transition layer 30 adopts a ring-shaped partial connection structure instead of providing full coverage support to the bottom of the mounting substrate 20. This structure can reduce the rigid coupling area between the thermal expansion transition layer 30 and the mounting substrate 20 while ensuring the basic support stability of the mounting substrate 20. On the other hand, the non-connected areas of the mounting substrate 20 can retain a certain degree of free deformation capability, which is beneficial for buffering the thermal stress concentration caused by the difference in the thermal expansion coefficients of the materials.

[0038] By setting the thermal expansion transition layer 30 as a composite structure including an annular body 31 and a support member 32, and using different materials for the annular body 31 and the support member 32, the thermal expansion transition layer 30 can form a partitioned thermal expansion buffer and support path between the outer shell 10 and the mounting substrate 20. The annular body 31 can buffer, absorb, or disperse thermal deformation from the outer shell 10 side, while the support member 32 can bear and redistribute thermal stress while ensuring the support stability of the mounting substrate 20, reducing the local stress peak in the connection area between the mounting substrate 20 and the outer shell 10.

[0039] In some embodiments, see Figure 5 Multiple support members 32 can be configured. These support members 32 can be spaced apart within the annular body 31 and distributed uniformly or non-uniformly along the circumference of the annular body 31. For example, the multiple support members 32 can be arranged in a circumferential array, symmetrically, or with locally denser distribution. By distributing the multiple support members 32, the mounting substrate 20 can be supported at multiple locations, thereby improving support stability and facilitating the dispersion and redistribution of thermal stress between different areas.

[0040] In some embodiments, the annular body 31 is made of rubber, and the support member 32 is made of metal or ceramic. The annular body 31 is made of rubber, giving it a certain elastic deformation capacity and cushioning ability. When the outer shell 10 and the mounting substrate 20 undergo relative deformation under temperature changes due to differences in their thermal expansion coefficients, the rubber annular body 31 can absorb, buffer, or release this relative deformation through its own elastic deformation, thereby reducing the thermal stress concentration phenomenon caused by the rigid connection between the outer shell 10 and the mounting substrate 20.

[0041] The support member 32 made of metal or ceramic has high mechanical strength and load-bearing capacity, and can provide relatively stable support at the bottom of the mounting base 20. However, the support member 32 made of ceramic has higher compatibility with the mounting base 20. Support members 32 made of different materials can be selected according to different scenarios.

[0042] By having the annular body 31 made of rubber cooperate with the support member 32 made of metal or ceramic, the thermal expansion transition layer 30 has both thermal stress buffering function and stable support function. This ensures the installation stability of the mounting substrate 20 while reducing the transmission of thermomechanical stress from the outer shell 10 to the mounting substrate 20 and the sensitive structure of the MEMS device 40. This helps to reduce the risk of zero-bias drift and long-term reliability degradation, thereby improving the reliability and stability of the entire MEMS packaging structure.

[0043] In some embodiments, an improved implementation of the above-described annular body 31 may employ, as follows: Figure 3 and Figure 5 The structure shown is as follows. The top of the annular body 31 is provided with a groove 33, the mounting base 20 is engaged with the groove 33, and the support member 32 is located within the projected area of ​​the groove 33.

[0044] The groove 33 can be formed on the top surface of the annular body 31 and recessed downward along the top of the annular body 31. The shape of the groove 33 can be adapted to the outer contour of the mounting substrate 20, for example, it can be set as a rectangular groove, a circular groove, etc., so that the mounting substrate 20 can be embedded in the groove 33 and form a snap-fit ​​with it.

[0045] The bottom edge region of the mounting substrate 20 can at least partially extend into the groove 33. Through this snap-fit ​​engagement, the mounting substrate 20 achieves a certain degree of horizontal restraint, thereby providing better positioning and assembly stability when mounted on the thermal expansion transition layer 30. Furthermore, during use, it reduces the risk of misalignment or tilting of the mounting substrate 20, improving assembly accuracy and reliability.

[0046] When viewed along the vertical projection direction, the support member 32 is located within the coverage area corresponding to the groove 33. With this configuration, when the mounting base 20 is embedded in the groove 33 and forms a snap-fit ​​engagement with the groove 33, the support member 32 can be located below the effective support area of ​​the mounting base 20, thereby providing a more concentrated and stable support for the mounting base 20.

[0047] The depth and shape of the groove 33 can be set according to the thickness and size of the mounting substrate 20. An interference fit, a gap fit, or a limiting fit structure after adhesive bonding can be formed between the groove 33 and the mounting substrate 20 to meet the assembly requirements of different packaging structures.

[0048] In some embodiments, a modified implementation of the thermal expansion transition layer 30 may employ, as follows: Figures 6 to 7 The structure shown is as follows. The thermal expansion transition layer 30 includes a metal layer 34, a rubber layer 35, and a ceramic layer 36 arranged sequentially from bottom to top.

[0049] The metal layer 34 is located in the lower part of the thermal expansion transition layer 30, and is situated on the side closest to the bottom wall of the inner cavity of the outer casing 10. The metal layer 34 can be fixedly connected to the bottom wall of the inner cavity of the outer casing 10, serving as the connection base between the thermal expansion transition layer 30 and the outer casing 10. By providing the metal layer 34, the thermal expansion transition layer 30 can have material properties closer to those of the outer casing 10 on the side closest to the outer casing 10, thereby helping to reduce the degree of material abruptness between the outer casing 10 and the thermal expansion transition layer 30.

[0050] A rubber layer 35 is disposed between the metal layer 34 and the ceramic layer 36. The rubber layer 35 can serve as an intermediate buffer layer to buffer, absorb, or disperse relative displacement, local deformation, or thermal stress caused by the material difference between the metal layer 34 and the ceramic layer 36. When the external temperature changes, the rubber layer 35 can utilize its own elastic deformation capability to form a flexible transition region between the metal layer 34 and the ceramic layer 36 to reduce thermal stress concentration.

[0051] The ceramic layer 36 is located in the upper part of the thermal expansion transition layer 30, and is situated on the side closest to the mounting substrate 20. The ceramic layer 36 can be used to connect with the mounting substrate 20 or to provide support for the mounting substrate 20. Since the mounting substrate 20 can be made of ceramic, by providing the ceramic layer 36, the side of the thermal expansion transition layer 30 closest to the mounting substrate 20 can have material properties similar to those of the mounting substrate 20, thereby improving the material compatibility between the thermal expansion transition layer 30 and the mounting substrate 20.

[0052] In this embodiment, the thermomechanical stress on the outer shell 10 side is first received by the metal layer 34, then buffered and released by the rubber layer 35, and then transferred to the mounting substrate 20 through the ceramic layer 36 in a relatively stable manner, thereby reducing the thermal mismatch problem caused by direct contact between different materials.

[0053] Optionally, the metal layer 34 can be made of Kovar alloy, stainless steel, copper alloy or aluminum alloy; the rubber layer 35 can be made of silicone rubber, fluororubber or other materials; and the ceramic layer 36 can be made of alumina, aluminum nitride or other materials.

[0054] Specifically, the metal layer 34, rubber layer 35, and ceramic layer 36 can be bonded, vulcanized, or mechanically pressed to form an integral or combined structure to ensure the connection stability of the thermal expansion transition layer 30 during use.

[0055] In some embodiments, an improved implementation of the rubber layer 35 may employ, as follows: Figure 7 The structure shown is as follows. The rubber layer 35 has a through hole 351 running vertically through it, and the through hole 351 is used to fill the connecting adhesive.

[0056] The through-holes 351 are provided through the rubber layer 35 along its thickness direction. There can be one or more through-holes 351, which can be distributed at intervals in different areas of the rubber layer 35, and can be evenly distributed, arrayed, or locally distributed according to the load-bearing requirements. Optionally, the through-holes 351 can be round holes, elliptical holes, polygonal holes, or other hole structures suitable for glue injection filling.

[0057] After the adhesive fills the through hole 351, a through-type connection can be formed in the vertical direction of the rubber layer 35. On the one hand, the elastic deformation capability of the rubber layer 35 itself can be used to buffer thermal stress; on the other hand, the adhesive in the through hole 351 can provide a certain connection strength in the thickness direction of the thermal expansion transition layer 30, thereby avoiding the problem of insufficient connection stability caused by relying solely on the surface bonding of the rubber layer 35.

[0058] Optionally, the adhesive can be an adhesive material with a certain degree of elasticity or toughness, such as silicone adhesive, epoxy adhesive, modified epoxy adhesive, polyurethane adhesive, etc.

[0059] In some embodiments, a specific implementation of the housing 10 described above may employ, as follows: Figure 1 , Figure 3 and Figure 6 The structure is shown. The outer casing 10 includes a housing 11 and a cover 12. The housing 11 has the aforementioned inner cavity, and the top of the housing 11 is provided with an opening. The cover 12 is detachably connected to the opening.

[0060] An opening is provided at the top of the housing 11 to facilitate the installation, positioning, connection, and subsequent maintenance of the substrate 20, thermal expansion transition layer 30, and MEMS device 40.

[0061] The cover 12 and the housing 11 can be detachably connected by means of threaded connection, snap-fit ​​connection, screw connection, crimp connection, etc. By detachably connecting the cover 12 to the opening, the inner cavity can be sealed after the internal components are assembled, thereby providing a relatively independent protective space for the MEMS device 40; when it is necessary to test, repair, replace internal components or adjust the assembly state, the cover 12 can be easily removed, improving the maintainability and assembly flexibility of the packaging structure.

[0062] It should be noted that the bottom of the cover 12 can mate with the edge of the top opening of the housing 11 to cover and seal the opening. A sealing element, such as a sealing ring, gasket, or sealing adhesive layer, can be further provided between the cover 12 and the housing 11 to improve the sealing performance at the opening and reduce the possibility of external dust, moisture, or other contaminants entering the inner cavity.

[0063] In some embodiments, an improved implementation of the above-described housing may employ, as follows: Figure 1 , Figures 4 to 5 The structure shown is such that a positioning rib 13 protrudes from the inner wall of the housing 11 and abuts against the outer periphery of the mounting base plate 20.

[0064] The positioning rib 13 can be integrally formed with the housing 11. The positioning rib 13 extends in the vertical direction and has no sharp edges on its outer periphery. There can be one or more positioning ribs 13, and multiple positioning ribs 13 can be distributed circumferentially at intervals along the inner wall of the housing 11. For example, multiple positioning ribs 13 can be symmetrically arranged around the mounting substrate 20, or they can be set in a continuous, segmented, or other style according to the outer contour of the mounting substrate 20 to meet the positioning requirements of different packaging structures.

[0065] After the mounting base plate 20 is placed in the inner cavity of the housing 11, its outer peripheral edge abuts against the positioning rib 13. The positioning rib 13 limits the outer periphery of the mounting base plate 20, constraining its position in the horizontal direction and giving it a clear assembly reference position within the housing 11. This reduces the possibility of the mounting base plate 20 shifting, thereby improving the assembly accuracy of the internal structure.

[0066] In some embodiments, an improved mating method between the housing and the cover can be adopted as follows: Figure 1 , Figures 4 to 5 The structure is shown. The positioning rib 13 has a guide groove 15, and the bottom end of the cover 12 is provided with a guide post 14, which is clearance-fitted with the guide groove 15.

[0067] The height of the positioning rib 13 is consistent with the height of the inner cavity of the housing 11. The guide groove 15 is located at the center of the positioning rib 13 and opens upward. When installing the cover 12, first inject adhesive into the guide groove 15, and then install the guide post 14 on the cover 12 in correspondence with the positioning rib 13. After the cover 12 is installed, the guide post 14 is located in the guide groove 15 and is bonded to the side wall of the guide groove 15 to fix the cover 12.

[0068] As an example, if the housing 11 is quadrilateral and the positioning ribs 13 are located at the four corners of the housing 11, then the number of guide posts 14 on the corresponding cover 12 is 4, and they correspond one-to-one with the positioning ribs 13 at the four corners.

[0069] The guide post 14 can be integrally formed with the cover 12, or it can be fixed to the bottom of the cover 12 by post-assembly. The cross-sectional shape of the guide post 14 can be circular, rectangular, etc., and must be consistent with the cross-sectional shape of the guide groove 15.

[0070] It is easy to imagine that the thermal expansion transition layer 30 is located between the mounting substrate 20 and the bottom wall of the housing 10. In order not to prevent the positioning rib 13 from abutting against the outer periphery of the mounting substrate 20, the thermal expansion transition layer 30 needs to be provided with a notch corresponding to the positioning rib 13.

[0071] In some embodiments, a specific implementation of the connection structure 50 described above may adopt the following approach: Figure 4 The structure shown is as follows. The connection structure 50 includes multiple spaced rubber pillars 51. The bottom of the MEMS device 40 is provided with a positioning block 41, which is used to extend into the gap between adjacent rubber pillars 51. The rubber pillars 51 can be made of materials such as silicone rubber or fluororubber.

[0072] The rubber pillars 51 can be arranged in a rectangular array, a circular array, or a symmetrical array. The positioning block 41 can be integrally formed with the MEMS device 40. After the positioning block 41 extends into the gap between the rubber pillars 51, it forms a matching positioning relationship with the rubber pillars 51, so that the MEMS device 40 can obtain a certain lateral limiting and relative position correction effect when it is mounted on the mounting substrate 20.

[0073] Furthermore, when the housing 10, mounting substrate 20, and MEMS device 40 experience relative displacement under temperature changes, vibration, or impact conditions, the multiple rubber pillars 51 can buffer, absorb, or disperse the displacement and stress through their own elastic deformation; the positioning block 41 can play a role in preventing displacement and limiting the position between adjacent rubber pillars 51, so that the MEMS device 40 can maintain good installation posture stability while obtaining flexible support.

[0074] To facilitate the installation of multiple rubber pillars 51, the connecting structure 50 also includes an adhesive layer 52 fixed to the bottom of the multiple rubber pillars 51. The adhesive layer 52 and the rubber pillars 51 can be an integral structure, that is, the adhesive layer 52 also uses the same material as the rubber pillars 51. When installing the connecting structure 50, the adhesive layer 52 is bonded to the top surface of the mounting base plate 20, which can complete the fixing of all rubber pillars 51. The assembly efficiency is high and the operation is convenient.

[0075] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A MEMS packaging structure with matched coefficient of thermal expansion, characterized in that, include: The outer shell has an inner cavity; A mounting base plate is disposed within the inner cavity, and the mounting base plate is fixed to the bottom wall of the inner cavity; A thermal expansion transition layer is disposed between the mounting substrate and the bottom wall of the inner cavity; A MEMS device is disposed on the top of the mounting substrate, and a connection structure for connecting the MEMS device to the mounting substrate is provided on the bottom of the MEMS device.

2. The MEMS packaging structure with matched thermal expansion coefficient as described in claim 1, characterized in that, The thermal expansion transition layer includes: The annular body is fixed to the bottom wall of the inner cavity; A support member is embedded in the annular body, the top end of the support member is flush with the top surface of the annular body, and is fixedly connected to the bottom of the mounting base plate. The annular body is made of a different material than the support member.

3. The MEMS packaging structure with matched thermal expansion coefficient as described in claim 2, characterized in that, The ring-shaped main body is made of rubber, and the supporting component is made of metal or ceramic.

4. The MEMS packaging structure with matched thermal expansion coefficient as described in claim 2, characterized in that, The top of the annular body is provided with a groove, the mounting base plate is engaged with the groove, and the support member is located within the projected area of ​​the groove.

5. The MEMS packaging structure with matched thermal expansion coefficient as described in claim 1, characterized in that, The thermal expansion transition layer includes a metal layer, a rubber layer, and a ceramic layer arranged sequentially from bottom to top.

6. The MEMS packaging structure with matched thermal expansion coefficient as described in claim 5, characterized in that, The rubber layer has through holes running vertically through it, and the through holes are used to fill the connecting adhesive.

7. The MEMS packaging structure with matched thermal expansion coefficient as described in claim 1, characterized in that, The outer casing includes: A housing having the inner cavity, the top of the housing having an opening; A cap is detachably attached to the opening.

8. The MEMS packaging structure with matched thermal expansion coefficient as described in claim 7, characterized in that, The inner wall of the housing is provided with a positioning rib, which abuts against the outer periphery of the mounting base plate.

9. The MEMS packaging structure with matched thermal expansion coefficient as described in claim 8, characterized in that, The positioning rib has a guide groove, and the bottom end of the cover is provided with a guide post, which is in clearance fit with the guide groove.

10. The MEMS packaging structure with matched thermal expansion coefficient as described in claim 1, characterized in that, The connection structure includes multiple spaced rubber pillars, and the bottom of the MEMS device is provided with a positioning block, which is used to extend into the gap between adjacent rubber pillars.

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