A MEMS sensor device package structure

Abstract

The application provides a MEMS sensor device packaging structure, which comprises a packaging shell, an ASIC chip and a MEMS chip, the packaging shell has an accommodating cavity with an opening upward, a cover is connected to the upper part of the packaging shell and is used for plugging the accommodating cavity, the ASIC chip is arranged in the accommodating cavity and is electrically connected to the packaging shell, and the MEMS chip is arranged above the ASIC chip and is electrically connected to the ASIC chip through a plurality of connecting columns which are arranged through the ASIC chip and the MEMS chip along the up-down direction. The MEMS sensor device packaging structure provided by the application effectively reduces the packaging volume by forming the up-down stacked layout structure of the MEMS chip and the ASIC chip, realizes the electrical connection and mechanical fixation between the ASIC chip and the MEMS chip through the arrangement of the connecting columns, avoids the stress transmission caused by the glue solidification shrinkage and temperature cycle from the root, significantly reduces the stress concentration on the MEMS chip, and improves the stability of the sensor device packaging structure.

Description

Technical Field

[0001] This invention belongs to the field of MEMS sensor technology, and specifically relates to a MEMS sensor device packaging structure. Background Technology

[0002] MEMS sensors are a new type of sensor manufactured using microelectronics and micromachining technologies. Compared with traditional sensors, they are characterized by small size, light weight, low cost, low power consumption, high reliability, suitability for mass production, ease of integration, and ability to achieve intelligent operation.

[0003] Currently, MEMS sensor packaging structures can be mainly divided into metal shell packaging, ceramic packaging, and plastic packaging. Since the core material of MEMS chips is single-crystal silicon, and the components of the packaging structure (adhesive, wire bonding wires, etc.) have significantly different coefficients of thermal expansion from silicon, different materials have different degrees of thermal expansion and contraction during the temperature cycling of the packaging process or the actual temperature change of the sensor, resulting in thermal stress inside the packaging structure. This stress will be directly transmitted to the sensitive structure of the MEMS sensor through the chip adhesive layer or wire bonding points, forming stress concentration.

[0004] The core working principle of MEMS sensors is based on the mechanical properties of the sensitive structure, such as the piezoresistive effect of strain gauges and the gap changes of capacitor plates. Stress concentration can directly disrupt their mechanical equilibrium, thereby affecting the stability of the sensor chip's operation. Summary of the Invention

[0005] The MEMS sensor device packaging structure provided in this embodiment of the invention can solve the technical problem of stress concentration in the prior art of MEMS sensor packaging structures and ensure the working stability of the sensor chip after packaging.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: to provide a MEMS sensor device packaging structure, comprising:

[0007] A packaged tube has an upward-opening receiving cavity, and a cap is connected to the top of the packaged tube to seal the receiving cavity;

[0008] An ASIC chip is disposed within the receiving cavity and is electrically connected to the packaged housing;

[0009] The MEMS chip is located above the ASIC chip and is electrically connected to the ASIC chip through a number of connecting posts. The connecting posts pass through the ASIC chip and the MEMS chip in the vertical direction.

[0010] In one possible implementation, the connecting post includes:

[0011] A limiting sleeve, penetrating both the ASIC chip and the MEMS chip, and having a first limiting portion abutting against the bottom surface of the ASIC chip; and

[0012] The limiting rod is inserted into the limiting sleeve and has a second limiting part that abuts against the upper surface of the MEMS chip;

[0013] An anti-detachment unit is provided between the limiting sleeve and the limiting rod. The anti-detachment unit is used to lock the axial position of the limiting sleeve and the limiting rod so that the MEMS chip and the ASIC chip can be connected.

[0014] In some embodiments, the anti-detachment unit includes:

[0015] Multiple anti-detachment teeth are spaced apart along the axial direction of the limiting sleeve on the inner peripheral wall of the limiting sleeve. The lower tooth surface of the anti-detachment teeth is arranged horizontally along the radial direction of the limiting sleeve, and the upper tooth surface of the anti-detachment teeth is gradually inclined upward from the axis of the limiting sleeve to the outer periphery.

[0016] A snap-fit ​​element, hinged to the outer periphery of the limiting rod, has a snap-fit ​​portion capable of abutting against the lower tooth surface of the anti-disengagement tooth; and

[0017] An elastic element, connected between the snap-fit ​​member and the limiting rod, is configured with a preload force that moves the snap-fit ​​portion away from the limiting rod.

[0018] In one possible implementation, a buffer ring is further provided between the ASIC chip and the receiving cavity, the bottom surface of the buffer ring being bonded to the bottom wall of the receiving cavity, and the top surface of the buffer ring being bonded to the bottom surface of the ASIC chip.

[0019] In some embodiments, the top surface of the buffer pad ring is provided with a circumferentially extending adhesive groove, which is used to fill adhesive to bond the ASIC chip.

[0020] In some embodiments, the buffer pad ring and the ASIC chip enclose an inner space, and a plurality of vent holes are provided through the peripheral wall of the buffer pad ring, which are used to connect the inner space and the receiving cavity.

[0021] In some embodiments, a support plate is further provided between the ASIC chip and the bottom wall of the receiving cavity, and the buffer pad ring is located around the support plate;

[0022] The top surface of the support plate is provided with a number of spaced support protrusions, and the top surface of the support protrusions is bonded to the bottom surface of the ASIC chip.

[0023] In one possible implementation, a buffer pad is further provided between the MEMS chip and the ASIC chip, and the connecting post is disposed through the buffer pad;

[0024] The top surface of the buffer pad has a plurality of spaced-apart first protrusions, which abut against the bottom surface of the MEMS chip; the bottom surface of the buffer pad has a plurality of spaced-apart second protrusions, which abut against the top surface of the ASIC chip.

[0025] The projections of the first protrusion and the second protrusion on the horizontal plane are staggered.

[0026] In some embodiments, the cushioning pad includes:

[0027] Intermediate plate;

[0028] An upper flexible plate is connected above the intermediate plate, and the first protrusion is integrally formed on the upper flexible plate; and

[0029] The lower flexible plate is connected below the middle plate, and the second protrusion is integrally formed on the lower flexible plate.

[0030] In one possible implementation, the ASIC chip is electrically connected to the inner peripheral wall of the package via copper pillars.

[0031] The beneficial effects of the MEMS sensor device packaging structure provided by this invention are as follows: Compared with the prior art, the MEMS sensor device packaging structure of this invention forms a closed space inside the cavity by sealing the cavity with a cap, which can effectively isolate external moisture, dust and other pollutants and ensure the atmospheric environment inside the cavity; by placing the MEMS chip on top of the ASIC chip to form a stacked layout structure, compared with the traditional planar side-by-side placement, the area occupied on the bottom surface of the package shell is significantly reduced, effectively reducing the package volume; through the setting of connecting posts, the electrical connection and mechanical fixation between the ASIC chip and the MEMS chip are realized simultaneously, without relying on glue for mechanical fixation, fundamentally avoiding stress transmission caused by glue curing shrinkage and temperature cycling, significantly reducing stress concentration on the MEMS chip, and improving the stability of the sensor device packaging structure. Attached Figure Description

[0032] Figure 1 This is a cross-sectional view of a MEMS sensor device packaging structure provided in an embodiment of the present invention;

[0033] Figure 2 This is a cross-sectional structural schematic diagram of the connecting column provided in an embodiment of the present invention;

[0034] Figure 3This is a schematic diagram of the structure of the buffer pad ring provided in an embodiment of the present invention;

[0035] Figure 4 This is a schematic diagram of the structure of the support plate provided in an embodiment of the present invention;

[0036] Figure 5 This is a cross-sectional view of the buffer pad provided in an embodiment of the present invention.

[0037] The following are the labeling elements in the figure:

[0038] 1. Encapsulated housing; 11. Receiving cavity; 12. Cap; 2. ASIC chip; 3. MEMS chip; 4. Connecting post; 41. Limiting sleeve; 411. First limiting part; 412. Anti-dislodgement tooth; 42. Limiting rod; 421. Second limiting part; 422. Snap-fit ​​component; 4221. Snap-fit ​​part; 423. Elastic component; 5. Buffer pad ring; 51. Adhesive groove; 52. Vent hole; 53. Inner space of the ring; 54. Positioning block; 6. Support plate; 61. Support protrusion; 7. Buffer pad; 71. Intermediate plate; 72. Upper flexible plate; 721. First protrusion; 73. Lower flexible plate; 731. Second protrusion; 8. Copper pillar. Detailed Implementation

[0039] 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.

[0040] It should be noted that when an element is referred to as being "set on" another element, it can be directly on or indirectly on the other element. It should be understood that the terms "length," "width," "upper," "lower," "front," "rear," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the invention, "a plurality of" or "several" means two or more, unless otherwise explicitly specified.

[0041] Please refer to the following: Figures 1 to 5The present invention will now describe a MEMS sensor device packaging structure. The MEMS sensor device packaging structure includes a packaging shell 1, an ASIC chip 2, and a MEMS chip 3. The packaging shell 1 has an upward-opening receiving cavity 11, and a cap 12 is connected to the top of the packaging shell 1 to seal the receiving cavity 11. The ASIC chip 2 is disposed within the receiving cavity 11 and is electrically connected to the packaging shell 1. The MEMS chip 3 is disposed above the ASIC chip 2 and is electrically connected to the ASIC chip 2 through several connecting posts 4. The connecting posts 4 are arranged to penetrate the ASIC chip 2 and the MEMS chip 3 in a vertical direction.

[0042] This embodiment provides a MEMS sensor device packaging structure that, compared with the prior art, seals the receiving cavity 11 with the cap 12, forming a closed space within the receiving cavity 11. This effectively isolates external moisture, dust, and other contaminants, ensuring the atmospheric environment within the receiving cavity 11. By placing the MEMS chip 3 above the ASIC chip 2, a stacked layout is formed. Compared with the traditional planar side-by-side placement, this significantly reduces the area occupied on the bottom surface of the packaging shell 1, effectively reducing the packaging volume. Through the setting of the connecting post 4, both electrical connection and mechanical fixation between the ASIC chip 2 and the MEMS chip 3 are achieved simultaneously, eliminating the need for adhesive for mechanical fixation. This fundamentally avoids stress transmission caused by adhesive curing shrinkage and temperature cycling, significantly reducing stress concentration on the MEMS chip 3 and improving the stability of the sensor device packaging structure.

[0043] It should be noted that the MEMS sensor chip can sense physical quantities such as bone vibration information, acceleration, and angular velocity, and output analog signals. The ASIC chip 2 can convert these analog signals into corresponding digital signals, facilitating subsequent signal processing and analysis by subsequent devices. Integrating the MEMS chip 3 and the ASIC chip 2 into a package 1 enables a high-performance, high-reliability miniature intelligent sensing system.

[0044] If the MEMS chip 3 and the ASIC chip 2 are bonded together using traditional adhesive, a uniform amount of adhesive (commonly epoxy resin adhesive) needs to be applied to the contact surfaces of the two chips. However, since the thermal expansion coefficients of the chip and the adhesive are quite different, when the ambient temperature changes (such as the curing cooling during the packaging process or the temperature fluctuations during sensor operation), the significant deformation of the adhesive will directly pull or squeeze the chip surface, forming significant stress concentration, which will cause the sensor output signal to drift and directly affect the measurement accuracy of the sensor.

[0045] In this embodiment, several connecting posts 4 form a multi-point connection between the MEMS chip 3 and the ASIC chip 2, replacing the traditional glue bonding method. This reduces the contact area and fundamentally avoids the problem of stress concentration in the MEMS chip 3 caused by the difference in thermal expansion coefficients. At the same time, it can ensure stable mechanical positioning between the two chips. In addition, at the electrical connection level, the connecting posts 4 are made of copper material and directly penetrate the ASIC chip 2 and the MEMS chip 3 to form a low-impedance, short-path conductive path. Compared with the traditional wire bonding method, this reduces signal transmission loss and parasitic parameters, ensuring that the sensing signal of the MEMS chip 3 is efficiently transmitted to the ASIC chip 2 for processing, thus improving signal integrity and transmission efficiency.

[0046] The package housing 1 is made of ceramic, which can serve as a reliable load-bearing and protective component in the package structure. The ceramic housing has high airtightness and insulation. When used in conjunction with the cover 12, it can provide a moisture-proof and dust-proof sealed environment for the MEMS chip 3 and ASIC chip 2, avoiding external environmental interference from affecting device performance. It can also ensure the electrical isolation of the circuit wiring inside the package housing 1, ensuring stable signal transmission.

[0047] In some possible implementations, the connecting post 4 described above adopts the following... Figure 2 The structure shown. See also Figure 2 The connecting post 4 includes a limiting sleeve 41 and a limiting rod 42. The limiting sleeve 41 passes through the ASIC chip 2 and the MEMS chip 3 and has a first limiting part 411 that abuts against the bottom surface of the ASIC chip 2. The limiting rod 42 is inserted into the limiting sleeve 41 and has a second limiting part 421 that abuts against the upper surface of the MEMS chip 3. An anti-disengagement unit is provided between the limiting sleeve 41 and the limiting rod 42. The anti-disengagement unit is used to lock the axial position of the limiting sleeve 41 and the limiting rod 42 so that the MEMS chip 3 and the ASIC chip 2 are connected.

[0048] In this embodiment, the ASIC chip 2 and the MEMS chip 3 are respectively provided with through holes running vertically. The inner wall of the through hole is coated with a conductive layer. The limiting sleeve 41 and the limiting rod 42 are both made of conductive materials (such as copper alloy). When the limiting sleeve 41 is inserted into the through hole, its outer wall is tightly fitted with the conductive layer of the inner wall of the through hole. After the limiting rod 42 is inserted into the limiting sleeve 41 and locked with it, a conductive path is formed between the MEMS chip 3 and the ASIC chip 2 through the connecting post 4 and the conductive layer of the through hole, so as to realize the transmission of electrical signals.

[0049] Specifically, the limiting sleeve 41 can penetrate the through holes on both the MEMS chip 3 and the ASIC chip 2, meaning it can be tightly fitted to the inner walls of the through holes of both chips simultaneously, allowing direct electrical connection between the two chips via the limiting sleeve 41. Alternatively, the limiting sleeve 41 can be tightly fitted only to the through hole on the ASIC chip 2, while the upper part of the limiting rod 42 is tightly fitted to the through hole on the MEMS chip 3. After the anti-detachment unit at the lower part of the limiting rod 42 locks the axial position of the limiting sleeve 41, a conductive path between the two chips is formed by the limiting rod 42, the anti-detachment unit, and the limiting sleeve 41.

[0050] In actual installation, the limiting sleeve 41 is first inserted into the through hole of the ASIC chip 2 from bottom to top, and the first limiting part 411 abuts against the bottom surface of the ASIC chip 2. Then, the limiting rod 42 is inserted into the limiting sleeve 41 from top to bottom, so that the second limiting part 421 abuts against the top surface of the MEMS chip 3. At the same time, the position of the limiting rod 42 is locked by the anti-detachment unit, which can realize the quick connection between the MEMS chip 3 and the ASIC chip 2, simplify the assembly process, and help improve packaging efficiency.

[0051] In the above structure, the first limiting part 411 and the second limiting part 421 form a bidirectional mechanical limiting structure for the two chips. At the same time, with the locking effect of the anti-detachment unit, a reliable mechanical connection can be formed after the two chips are stacked on top of each other, and the stability of the electrical connection can be guaranteed, avoiding the increase of contact resistance due to loose connection.

[0052] The anti-detachment unit enables unidirectional insertion of the limiting rod 42 and the limiting sleeve 41, preventing the limiting rod 42 from detaching in the opposite direction. Specifically, a ratchet and pawl structure can be adopted, such as setting continuous ratchet on the outer peripheral wall of the limiting rod 42 and setting a rotatable pawl at the corresponding position inside the limiting sleeve 41. The unidirectional locking action of the pawl and ratchet is used to achieve axial locking between the limiting rod 42 and the limiting sleeve 41.

[0053] Optionally, the anti-detachment unit can also adopt an elastic locking pin and positioning hole structure. For example, multiple positioning holes are spaced along the length direction on the inner peripheral wall of the limiting sleeve 41, and an elastic locking pin with a return spring is assembled on the outer peripheral wall of the limiting rod 42. The outer end of the elastic locking pin is hemispherical, and the limiting rod 42 can only move to one side of the spherical surface and cannot be allowed to move in the opposite direction.

[0054] Alternatively, the limiting sleeve 41 and the limiting rod 42 can be directly connected by threads, using the self-locking property of the threads to lock the axial position of the limiting rod 42.

[0055] The first limiting part 411 can be an annular boss located at the lower end of the limiting sleeve 41, with the upper side of the annular boss abutting against the bottom surface of the ASIC chip 2. Similarly, the second limiting part 421 can be a circular boss located at the upper end of the limiting rod 42, with the lower side of the circular boss abutting against the top surface of the MEMS chip 3.

[0056] In some possible embodiments, the above-mentioned anti-detachment unit adopts, for example... Figure 2 The structure shown. See also Figure 2 The anti-detachment unit includes multiple anti-detachment teeth 412, a snap-fit ​​element 422, and an elastic element 423. The multiple anti-detachment teeth 412 are spaced apart along the axial direction of the limiting sleeve 41 on the inner peripheral wall of the limiting sleeve 41. The lower tooth surface of the anti-detachment teeth 412 is arranged horizontally along the radial direction of the limiting sleeve 41, and the upper tooth surface of the anti-detachment teeth 412 is gradually inclined upward from the axis of the limiting sleeve 41 to the outer periphery. The snap-fit ​​element 422 is hinged to the outer periphery of the limiting rod 42 and has a snap-fit ​​portion 4221 that can abut against the lower tooth surface of the anti-detachment teeth 412. The elastic element 423 is connected between the snap-fit ​​element 422 and the limiting rod 42 and is configured with a pre-tightening force to move the snap-fit ​​portion 4221 away from the limiting rod 42.

[0057] When the limiting rod 42 is inserted into the limiting sleeve 41, the locking member 422 slides along the upper tooth surface of the anti-disengagement tooth 412 and compresses the elastic member 423. When the limiting rod 42 is inserted to the preset position (the two chips are stacked and installed), the locking part 4221 passes over the current anti-disengagement tooth 412 and swings outward to reset under the pre-tightening force of the elastic member 423. The locking part 4221 forms a rigid abutment with the lower tooth surface of the anti-disengagement tooth 412. At this time, if the limiting rod 42 is subjected to axial tension and attempts to withdraw, the locking part 4221 will be blocked by the lower tooth surface of the anti-disengagement tooth 412 and cannot move in the opposite direction, thereby achieving axial locking between the limiting sleeve 41 and the limiting rod 42.

[0058] The aforementioned anti-detachment teeth 412 and locking components 422 form a unidirectional constraint on the axial position of the limiting rod 42, which not only facilitates assembly but also ensures the reliability of the mechanical connection. Multiple anti-detachment teeth 412 are spaced apart along the axial direction, allowing the locking position of the limiting rod 42 and the limiting sleeve 41 to be flexibly adjusted according to the chip thickness, improving the versatility of the structure. The elastic preload of the elastic element 423 ensures that the locking part 4221 is always tightly fitted with the anti-detachment teeth 412, ensuring the rigidity of the mechanical connection and maintaining stable conductive contact even under vibration conditions.

[0059] Specifically, the outer peripheral wall of the limiting rod 42 is provided with a mounting groove, and the snap-fit ​​member 422 is hinged in the mounting groove. The elastic member 423 can be a cylindrical helical spring connected between the mounting groove wall and the snap-fit ​​member 422, or it can be a torsion spring provided on the hinge shaft of the snap-fit ​​member 422. When the limiting rod 42 is inserted downward into the limiting sleeve 41, the snap-fit ​​member 422 can compress the elastic member 423 and swing into the mounting groove to prevent interference with the insertion action of the limiting rod 42. The outer peripheral wall of the limiting rod 42 can be adapted to the inner peripheral wall of the limiting sleeve 41 to form a sliding fit, thereby reducing the fit clearance and avoiding shaking that would affect the connection stability.

[0060] In this embodiment, there are two sets of snap-fit ​​components 422. The two sets of snap-fit ​​components 422 are arranged at intervals along the axial direction of the limiting rod 42. Each set of snap-fit ​​components 422 includes two snap-fit ​​components 422 symmetrically arranged on both sides of the limiting rod 42. Each snap-fit ​​component 422 is provided with two snap-fit ​​parts 4221, which can simultaneously form a snap-fit ​​with two adjacent anti-detachment teeth 412, further increasing the anti-detachment effect and ensuring the reliability of the mechanical connection.

[0061] See some possible embodiments. Figure 1 A buffer ring 5 is also provided between the ASIC chip 2 and the receiving cavity 11. The bottom surface of the buffer ring 5 is bonded to the bottom wall of the receiving cavity 11, and the top surface of the buffer ring 5 is bonded to the bottom surface of the ASIC chip 2.

[0062] The buffer ring 5 is preferably made of silicone. The buffer ring 5 is bonded between the ASIC chip 2 and the bottom wall of the cavity 11. On the one hand, the excellent deformation ability of silicone material itself can be used to buffer the vibration of the equipment and avoid hard contact between the ASIC chip 2 and the bottom wall of the cavity 11, thereby reducing the transmission of external stress to the MEMS chip 3. It is especially suitable for the protection requirements of the MEMS chip 3 that is sensitive to vibration.

[0063] On the other hand, the buffer ring 5 has a ring-shaped structure, which helps to reduce the bonding area with the ASIC chip 2, thereby ensuring the heat dissipation area of ​​the ASIC chip 2; moreover, the thermal expansion coefficient of the silicone buffer ring 5 is less different from that of the chip material, which can alleviate the thermal stress between the ASIC chip 2 and the housing cavity 11, thereby reducing the stress transmitted to the MEMS chip 3 and ensuring the working stability of the MEMS chip 3 after packaging.

[0064] Specifically, the outer dimensions of the buffer pad ring 5 match the outer dimensions of the ASIC chip 2. For example, if the ASIC chip 2 is rectangular, then the buffer pad ring 5 is also rectangular, and the outer edges of the two correspond vertically.

[0065] In some possible embodiments, the aforementioned buffer ring 5 may be adopted as follows: Figure 1 and Figure 3 The structure shown. See also Figure 1 and Figure 3 The top surface of the buffer pad ring 5 is provided with a circumferentially extending adhesive groove 51, which is used to fill adhesive to bond the ASIC chip 2.

[0066] The adhesive reservoir 51 provides additional space for the adhesive, allowing the adhesive to not only cover the flat area of ​​the top surface of the buffer ring 5, but also fill the adhesive reservoir 51 to form a three-dimensional adhesive structure. This effectively increases the contact area between the adhesive and the buffer ring 5 and the ASIC chip 2, thereby improving the adhesive adhesion and effectively resisting the peeling force generated by vibration, impact or thermal expansion and contraction on the ASIC chip 2. This prevents the ASIC chip 2 from shifting relative to the buffer ring 5 and ensures the stability of the overall packaging structure.

[0067] When the ASIC chip 2 is pressed down to adhere to the buffer pad ring 5, the adhesive groove 51 forms a closed space to contain the adhesive, preventing the adhesive from overflowing to the outside of the buffer pad ring 5 and causing contamination to other components.

[0068] Furthermore, the outer edge of the top surface of the buffer pad ring 5 is provided with multiple positioning blocks 54 at intervals. The positioning blocks 54 can be limited to the outer peripheral wall of the ASIC chip 2, and play an auxiliary positioning role when bonding the ASIC chip 2, so as to avoid misalignment between the ASIC chip 2 and the buffer pad ring 5, and ensure the bonding contact area between the two, thereby ensuring the reliability of the bonding.

[0069] For some specific embodiments, see Figure 1 and Figure 3 The buffer pad ring 5 and the ASIC chip 2 enclose each other to form an inner space 53. Several vent holes 52 are provided on the peripheral wall of the buffer pad ring 5. The vent holes 52 are used to connect the inner space 53 and the receiving cavity 11.

[0070] After the buffer ring 5 is bonded to the ASIC chip 2, the inner space 53 of the ring will form a relatively closed area. When the temperature changes, a pressure difference is easily formed between the inner space 53 of the ring and the receiving cavity 11. The setting of the vent 52 can balance the gas pressure between the inner space 53 of the ring and the receiving cavity 11, and avoid the failure of the bonding relationship between the buffer ring 5 and the ASIC chip 2 due to the internal and external pressure difference.

[0071] In addition, the ASIC chip 2 continuously generates heat during operation, some of which is transferred to the inner ring space 53 through its bottom surface. If the inner ring space 53 is closed, heat can easily accumulate there, affecting the heat dissipation efficiency of the ASIC chip 2. The vent 52 allows for airflow to assist in heat dissipation, which helps improve the operational stability of the ASIC chip 2 after packaging.

[0072] See some possible embodiments. Figure 1 and Figure 4A support plate 6 is provided between the ASIC chip 2 and the bottom wall of the cavity 11, and a buffer pad ring 5 is located on the periphery of the support plate 6. The top surface of the support plate 6 is provided with a number of spaced support protrusions 61, and the top surface of the support protrusions 61 is bonded to the bottom surface of the ASIC chip 2.

[0073] If the ASIC chip 2 relies solely on the outer buffer ring 5 for support, the concentrated force can easily cause the middle of the ASIC chip 2 to sag or deform. The support plate 6 provides support for the middle of the ASIC chip 2, resisting the chip's own weight and external stress.

[0074] The multiple spaced support bumps 61 reduce the bonding area between the support plate 6 and the ASIC chip 2, thereby reducing the stress coupling between the ASIC chip 2 and the package shell 1 and ensuring the packaging stability of the ASIC chip 2.

[0075] Furthermore, the support plate 6 can be made of rigid materials such as metal, and the support protrusion 61 can be made of the same silicone material as the buffer ring 5, which can both ensure the stable support of the ASIC chip 2 and ensure the buffering effect when the ASIC chip 2 is subjected to force.

[0076] Specifically, the determination of the number and area of ​​the support bumps 61 needs to take into account both stress isolation and bonding strength. Reducing the area and number of support bumps 61 helps to improve the stress isolation effect; increasing the area and number of support bumps 61 helps to improve the bonding and support effect on the ASIC chip 2.

[0077] See some possible embodiments. Figure 1 and Figure 5 A buffer pad 7 is provided between the MEMS chip 3 and the ASIC chip 2, and the connecting post 4 passes through the buffer pad 7. The top surface of the buffer pad 7 is provided with a number of spaced first protrusions 721, which abut against the bottom surface of the MEMS chip 3. The bottom surface of the buffer pad 7 is provided with a number of spaced second protrusions 731, which abut against the top surface of the ASIC chip 2. The projections of the first protrusions 721 and the second protrusions 731 on the horizontal plane are staggered.

[0078] The core functions of MEMS chips rely on micron- or even nanometer-scale structures (such as microcantilever beams and microcapacitor plates), making them extremely sensitive to vibration and shock. Even minute vibrations can lead to a decrease in measurement accuracy or functional failure.

[0079] The buffer pad 7 can preferably be made of silicone, which has a low elastic modulus and a high damping coefficient. It can effectively absorb vibration energy and prevent vibration from being directly transmitted to the MEMS chip 3 through the rigid connection between the ASIC chip 2 and the MEMS chip 3. This provides an effective shock-absorbing buffer layer for the high-precision structure of the MEMS chip 3.

[0080] The arrangement of the first protrusion 721 and the second protrusion 731 enables the buffer pad 7 to form point contact support with the two chips respectively. Compared with surface contact, point contact can significantly reduce the contact area for vibration transmission and reduce the transmission efficiency of vibration from ASIC chip 2 to MEMS chip 3. At the same time, the elastic deformation of the protrusion can further enhance the buffering effect against instantaneous impact.

[0081] When the ASIC chip 2 and MEMS chip 3 are fixed by the connecting post 4 and a clamping force is generated, the clamping force will be distributed to different areas of the two chips through the staggered first protrusion 721 and second protrusion 731, so as to avoid the situation that a single area will have indentations or package damage due to overload.

[0082] In addition, the first protrusion 721 and the second protrusion 731 can maintain a gap between the buffer pad 7 and the two chip surfaces. At the same time, the staggered arrangement of the first protrusion 721 and the second protrusion 731 makes the gap pass through the chip surface, forming an air circulation channel. The heat generated by the MEMS chip 3 and the ASIC chip 2 can be diffused outward through the gap, thus meeting the heat dissipation requirements of the chip.

[0083] In some possible embodiments, the aforementioned buffer pad 7 employs, for example... Figure 5 The structure shown. See also Figure 5 The buffer pad 7 includes an intermediate plate 71, an upper flexible plate 72 and a lower flexible plate 73. The upper flexible plate 72 is connected above the intermediate plate 71, and a first protrusion 721 is integrally formed on the upper flexible plate 72. The lower flexible plate 73 is connected below the intermediate plate 71, and a second protrusion 731 is integrally formed on the lower flexible plate 73.

[0084] The intermediate plate 71 can be made of a material with high rigidity to serve as a rigid skeleton for the overall structure, preventing the upper flexible plate 72 and the lower flexible plate 73 from collapsing due to excessive softness, ensuring the flatness of the buffer pad 7, and preventing the MEMS chip 3 from tilting after installation; at the same time, it can ensure the stability of the buffer elasticity of the first protrusion 721 and the second protrusion 731, and ensure that the stress dispersion effect does not fail.

[0085] Both the upper flexible plate 72 and the lower flexible plate 73 are made of materials with good elasticity. In actual processing, the first protrusion 721 and the second protrusion 731 can be integrally formed by injection molding or compression molding, which simplifies the processing technology and ensures the vibration damping ability of the first protrusion 721 and the second protrusion 731. The upper flexible plate 72 and the lower flexible plate 73 can be made with the intermediate plate 71 by hot pressing or vulcanization process to ensure the stability of the interlayer structure.

[0086] See some possible embodiments. Figure 1The ASIC chip 2 is electrically connected to the inner peripheral wall of the package 1 through a copper pillar 8.

[0087] Traditional gold wire bonding relies on ultrasonic welding to connect tiny solder joints with soft gold wires. This not only results in low solder joint strength and weak resistance to mechanical stress, but also makes the gold wires prone to breakage and solder joint detachment under transportation vibration, impact, or high-temperature thermal fatigue.

[0088] The copper pillar 8 in this embodiment has high mechanical strength and rigidity. It is connected to the pads of the ASIC chip 2 and the package shell 1 through surface contact. The bonding strength is much higher than that of gold wire solder joints. It can directly withstand the stress between the ASIC chip 2 and the package shell 1, which greatly reduces the risk of connection failure caused by vibration, impact and thermal cycling, and significantly improves the stability of the package structure.

[0089] On the other hand, traditional gold wire bonding, due to uneven bonding lengths, can lead to varying parasitic inductance and capacitance across different signal paths. This is especially problematic in high-frequency signal transmission scenarios, easily causing signal delays, crosstalk, and other interference issues, thus affecting signal integrity. In this embodiment, copper pillars (8-pin) are used for connection, facilitating precise control of connection height and position, effectively reducing parasitic parameter differences, avoiding signal interference caused by uneven bonding wire lengths, and ensuring the stability and accuracy of signal transmission.

[0090] Specifically, one end of the copper pillar 8 can be tightly connected to the pad of the ASIC chip 2 by welding, and the other end is also welded to the preset conductive area (such as metal pad or conductive plating) on ​​the inner peripheral wall of the package shell 1, so that the copper pillar 8 establishes an electrical connection between the ASIC chip 2 and the package shell 1. At the same time, welding also ensures the mechanical stability of the connection and avoids loosening that could affect the conductivity.

[0091] 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 sensor device packaging structure, characterized in that, include: The encapsulated housing (1) has an upward-opening receiving cavity (11), and a cap (12) is connected to the top of the encapsulated housing (1) for sealing the receiving cavity (11); An ASIC chip (2) is disposed in the receiving cavity (11) and electrically connected to the package shell (1); The MEMS chip (3) is located above the ASIC chip (2) and is electrically connected to the ASIC chip (2) through a number of connecting posts (4). The connecting posts (4) are arranged to pass through the ASIC chip (2) and the MEMS chip (3) in the vertical direction. The connecting post (4) includes: A limiting sleeve (41) penetrates the ASIC chip (2) and the MEMS chip (3), and has a first limiting portion (411) abutting against the bottom surface of the ASIC chip (2); and The limiting rod (42) is inserted into the limiting sleeve (41) and has a second limiting part (421) that abuts against the upper surface of the MEMS chip (3); An anti-detachment unit is provided between the limiting sleeve (41) and the limiting rod (42). The anti-detachment unit is used to lock the axial position of the limiting sleeve (41) and the limiting rod (42) so that the MEMS chip (3) and the ASIC chip (2) are connected. The anti-detachment unit includes: Multiple anti-detachment teeth (412) are spaced apart along the axial direction of the limiting sleeve (41) on the inner peripheral wall of the limiting sleeve (41). The lower tooth surface of the anti-detachment teeth (412) is arranged horizontally along the radial direction of the limiting sleeve (41), and the upper tooth surface of the anti-detachment teeth (412) is gradually inclined upward from the axis of the limiting sleeve (41) to the outer periphery. A snap-fit ​​member (422), hinged to the outer periphery of the limiting rod (42), has a snap-fit ​​portion (4221) capable of abutting against the lower tooth surface of the anti-disengagement tooth (412); and An elastic element (423), connected between the snap-fit ​​element (422) and the limiting rod (42), is configured with a preload force to move the snap-fit ​​portion (4221) away from the limiting rod (42).

2. The MEMS sensor device packaging structure as described in claim 1, characterized in that, A buffer ring (5) is also provided between the ASIC chip (2) and the receiving cavity (11). The bottom surface of the buffer ring (5) is bonded to the bottom wall of the receiving cavity (11), and the top surface of the buffer ring (5) is bonded to the bottom surface of the ASIC chip (2).

3. The MEMS sensor device packaging structure as described in claim 2, characterized in that, The top surface of the buffer pad ring (5) is provided with a circumferentially extending adhesive groove (51), which is used to fill adhesive to bond the ASIC chip (2).

4. The MEMS sensor device packaging structure as described in claim 2, characterized in that, The buffer pad ring (5) and the ASIC chip (2) enclose each other to form an inner space (53). A plurality of vent holes (52) are provided on the peripheral wall of the buffer pad ring (5). The vent holes (52) are used to connect the inner space (53) and the receiving cavity (11).

5. The MEMS sensor device packaging structure as described in claim 2, characterized in that, A support plate (6) is also provided between the ASIC chip (2) and the bottom wall of the cavity (11), and the buffer pad ring (5) is located on the periphery of the support plate (6); The top surface of the support plate (6) is provided with a plurality of spaced support protrusions (61), and the top surface of the support protrusions (61) is bonded to the bottom surface of the ASIC chip (2).

6. The MEMS sensor device packaging structure as described in claim 1, characterized in that, A buffer pad (7) is provided between the MEMS chip (3) and the ASIC chip (2), and the connecting post (4) is provided through the buffer pad (7); The top surface of the buffer pad (7) is provided with a plurality of spaced first protrusions (721), which abut against the bottom surface of the MEMS chip (3); the bottom surface of the buffer pad (7) is provided with a plurality of spaced second protrusions (731), which abut against the top surface of the ASIC chip (2). The projections of the first protrusion (721) and the second protrusion (731) on the horizontal plane are staggered.

7. The MEMS sensor device packaging structure as described in claim 6, characterized in that, The cushioning pad (7) includes: Intermediate plate (71); An upper flexible plate (72) is connected above the intermediate plate (71), and the first protrusion (721) is integrally formed on the upper flexible plate (72); and The lower flexible plate (73) is connected below the middle plate (71), and the second protrusion (731) is integrally formed on the lower flexible plate (73).

8. The MEMS sensor device packaging structure as described in claim 1, characterized in that, The ASIC chip (2) is electrically connected to the inner peripheral wall of the package shell (1) via a copper pillar (8).

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