Silicon-based piezoresistive differential pressure pressure sensor packaging structure, method and limiting assembly device

Abstract

The application discloses a silicon-based piezoresistive differential pressure pressure sensor packaging structure, a method and a limiting assembly device, relates to the technical field of pressure sensor packaging, and comprises a metal base, an adapter and a silicon-based piezoresistive pressure sensitive chip. The metal base is internally provided with a penetrating internal air channel; the adapter is made of glass, is fixed to the upper surface of the metal base through a first adhesive layer, and is internally provided with a through hole in communication with the internal air channel of the metal base; the first adhesive layer is a polymer adhesive layer with stress buffering capacity; the silicon-based piezoresistive pressure sensitive chip is fixed to the upper surface of the adapter through a eutectic bonding layer and corresponds to the position of the through hole, so that the measured pressure transmitted by the internal air channel can act on the chip. The application can simultaneously consider the mechanical stability of chip connection, ultrahigh air tightness, excellent thermal stress adaptability and long-term measurement precision stability.

Description

Technical Field

[0001] This invention relates to the field of pressure sensor packaging technology, and in particular to a silicon-based piezoresistive differential pressure sensor packaging structure, method, and limiting assembly device. Background Technology

[0002] Silicon-based piezoresistive pressure sensors are widely used in industrial control, environmental monitoring, and aerospace fields due to their excellent sensitivity, stability, and mature manufacturing processes. In high-end applications such as wind tunnel testing and engine monitoring, electronic pressure scanning valves are often used to simultaneously acquire pressure data from hundreds of channels. This requires integrated pressure sensors to have millimeter-scale dimensions to achieve high-density array integration, while maintaining extremely high long-term measurement accuracy and reliability in harsh environments such as high and low temperature cycling, vibration, and the presence of contaminated media.

[0003] Currently, to achieve high hermeticity and stable connection in sensors, one of the mainstream technologies is to directly bond silicon-based pressure-sensitive chips to a metal substrate (such as stainless steel or kova alloy) using eutectic bonding. Eutectic bonding can form a high-strength, hermetic-tight intermetallic compound connection layer, but this approach has a fundamental drawback: the coefficients of thermal expansion of silicon and commonly used metal substrate materials differ significantly. When subjected to operating temperature changes or high and low temperature cycling, huge thermal mismatch stresses will act on the eutectic bonding interface, easily leading to microcracks or even full cracks at the interface, causing sensor sealing failure, signal drift, or complete damage.

[0004] To alleviate thermal stress, another approach is to use organic adhesives (such as epoxy resin or silicone rubber) to bond the chip to the substrate. The adhesive layer possesses a certain degree of elasticity, which can buffer thermal stress. However, these polymer materials generally suffer from creep, aging, gas escaping, and large temperature drift. Under long-term pressure loads and temperature variations, even minute deformations of the adhesive layer can interfere with the accurate transmission of pressure to the sensitive chip, and its material properties change over time and with environmental changes, causing irreversible drift in the sensor's zero point and sensitivity, severely compromising long-term measurement accuracy and stability.

[0005] Therefore, existing technologies face a dilemma: eutectic bonding offers superior mechanical strength and hermeticity, but carries a high risk of thermal stress; adhesive bonding improves thermal stress adaptability, but compromises long-term stability and accuracy. This contradiction is particularly pronounced in sensors for electronic pressure scanning valves, which require extremely miniaturized dimensions and operate in harsh environments. There is an urgent need for an innovative packaging architecture that can simultaneously ensure mechanical robustness of the chip connection, ultra-high hermeticity, excellent thermal stress adaptability, and long-term measurement accuracy stability. Summary of the Invention

[0006] The purpose of this invention is to provide a silicon-based piezoresistive differential pressure sensor packaging structure, method, and limiting assembly device to solve the problems existing in the prior art, and to simultaneously ensure the mechanical stability of chip connection, ultra-high airtightness, excellent thermal stress adaptability, and long-term measurement accuracy stability.

[0007] To achieve the above objectives, the present invention provides the following solution: This invention provides a silicon-based piezoresistive differential pressure sensor packaging structure, comprising: a metal base, an adapter, and a silicon-based piezoresistive pressure-sensitive chip. The metal base has a through-hole for internal airflow. The adapter is made of glass and is fixed to the upper surface of the metal base by a first adhesive layer. The adapter has a through-hole communicating with the internal airflow of the metal base. The first adhesive layer is a polymer adhesive layer with stress-buffering capacity. The silicon-based piezoresistive pressure-sensitive chip is fixed to the upper surface of the adapter by a eutectic bonding layer, corresponding to the position of the through-hole, so that the pressure to be measured transmitted by the internal airflow can act on the chip.

[0008] Preferably, the first adhesive layer is a UV-curable adhesive layer.

[0009] Preferably, it further includes an electrical interconnection component and a protective cover; the electrical interconnection component includes a plurality of gold-plated spring sheets fixed on the metal base, and metal leads that connect the pads on the silicon-based piezoresistive pressure-sensitive chip to the corresponding gold-plated spring sheets via wire bonding; the protective cover is disposed on the metal base to form a sealed cavity for accommodating the chip and the electrical interconnection component, and the protective cover has a reference pressure hole communicating with the sealed cavity.

[0010] Preferably, the metal base is an aerospace aluminum alloy base.

[0011] Preferably, the overall dimensions of the packaging structure (length × width × height) are no greater than 4.7mm × 4.4mm × 3.5mm, and the dimensions of the silicon-based piezoresistive pressure-sensitive chip are no greater than 2.45mm × 2.45mm × 3mm.

[0012] Preferably, it further includes a resin connector, which is connected to the metal base and located inside the protective cover, together with the protective cover forming the sealed cavity. The resin connector is provided with an installation channel for the gold-plated spring sheet to pass through, and the gold-plated spring sheet is interference-fitted or snap-fitted to the inner wall of the installation channel.

[0013] The present invention also provides a packaging method for manufacturing the packaging structure described above, comprising the following steps: It provides a metal substrate and a chip assembly; wherein the chip assembly is composed of an adapter and a silicon-based piezoresistive pressure-sensitive chip bonded together. The chip components are bonded to the corresponding positions on the metal base using a polymer adhesive layer; Gold-plated spring sheets are mounted on the metal base, and the pads of the sensitive chip are electrically connected to the corresponding gold-plated spring sheets by wire bonding. Install a protective cover to form a sealed cavity, thus completing the encapsulation.

[0014] Preferably, the step of bonding the chip assembly to the corresponding position on the metal base includes: UV-curable adhesive is applied to the interface between the chip assembly and the metal substrate; A limiting assembly device is used to relatively position and press-fit the chip assembly to the metal base; The ultraviolet-curable adhesive is irradiated to cure it, thereby achieving the bonding between the chip assembly and the metal substrate.

[0015] The present invention also provides a limiting assembly device for the packaging method described above. The device has a multi-layer locking structure, including: a bottom cover, a metal base locking layer, a sensitive element locking layer, and a clamping layer. The metal base locking layer is detachably mounted on the bottom cover and has a locking groove for accommodating the metal base; the sensitive element locking layer is detachably mounted on the metal base locking layer and has a positioning hole for guiding the placement of the sensitive element or adapter; the clamping layer is detachably mounted on the sensitive element locking layer and has a clamping post coaxial with the positioning hole for applying pressure.

[0016] Preferably, the end face of the clamping post that contacts the chip assembly is made of a flexible material and its dimensions are adapted to the positioning hole.

[0017] The present invention achieves the following technical effects compared to the prior art: In this invention, because the eutectic bonding layer is a dense intermetallic compound, it achieves a rigid connection between the chip and the adapter with strength approaching that of the bulk material and extremely high hermeticity. This ensures the accuracy and stability of the pressure transmission path and avoids long-term accuracy drift caused by adhesive creep and aging in pure adhesive bonding schemes. Simultaneously, the polymer adhesive layer located between the adapter and the metal substrate, with its inherent elasticity and low elastic modulus, effectively absorbs and buffers the thermal stress generated by the difference in thermal expansion coefficients between the metal substrate and the adapter. This design decouples the significant thermal mismatch stress at two interfaces: the high-strength eutectic bonding interface ensures the mechanical and hermetic integrity of the core sensing unit, while the elastic adhesive interface is dedicated to stress buffering. Therefore, this structure simultaneously overcomes the risk of thermal stress cracking in traditional eutectic bonding direct connection schemes and the long-term accuracy and reliability deficiencies of traditional pure adhesive bonding schemes, achieving a balance between high hermeticity, low thermal stress, and long-term measurement stability. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is an exploded view of the pressure sensor packaging structure provided in an embodiment of the present invention; Figure 2 Four views of the pressure sensor packaging structure provided in an embodiment of the present invention; Figure 3 This is a cross-sectional view of the pressure sensor packaging structure provided in an embodiment of the present invention; Figure 4 An exploded view of the structure of the limiting assembly device (single-hole device) provided in an embodiment of the present invention. Figure 5 for Figure 4 A sectional view; Figure 6 An exploded view of the structure of the limiting assembly device (three-hole device) provided in an embodiment of the present invention. Figure 7 for Figure 6 The three views; Figure 8 An exploded view of the limiting assembly device (nine-hole device) provided in an embodiment of the present invention. Figure 9 for Figure 8 The three views; In the diagram: 1-Metal base; 2-Silicon-based piezoresistive pressure sensitive chip; 3-Adapter; 4-Gold-plated spring sheet; 5-Resin connector; 6-Protective cover; 7-Reference air pressure hole; 8-M1 threaded connection hole; 9-Internal air passage; 10-Through hole; 11-Bottom cover; 12-Metal base mounting layer; 13-Sensitive element mounting layer; 14-Pressure layer; 15-Leakage hole; 16-Mounting groove; 17-Positioning hole; 18-Pressure post; 19-Positioning groove. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] The purpose of this invention is to provide a silicon-based piezoresistive differential pressure sensor packaging structure, method, and limiting assembly device to solve the problems existing in the prior art, and to simultaneously ensure the mechanical stability of chip connection, ultra-high airtightness, excellent thermal stress adaptability, and long-term measurement accuracy stability.

[0022] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] The following is combined Figures 1 to 9 The following describes embodiments of the present invention.

[0024] Example 1 This invention provides a silicon-based piezoresistive differential pressure sensor packaging structure, comprising: a metal base 1, an adapter 3, and a silicon-based piezoresistive pressure sensitive chip 2. The metal base 1 has a through-hole 9. The adapter 3 is made of glass and is fixed to the upper surface of the metal base 1 by a first adhesive layer. The adapter 3 has a through hole 10 that communicates with the internal air passage 9 of the metal base 1. The first adhesive layer is a polymer adhesive layer with stress buffering capability. The silicon-based piezoresistive pressure sensitive chip 2 is fixed to the upper surface of the adapter 3 by a eutectic bonding layer, and the position corresponds to the through hole 10, so that the pressure to be measured transmitted by the internal air passage 9 can act on the chip.

[0025] In this embodiment, because the eutectic bonding layer is a dense intermetallic compound, it achieves a rigid connection with strength close to that of the bulk material and extremely high airtightness between the chip and the adapter 3, ensuring the accuracy and stability of the pressure transmission path and avoiding long-term accuracy drift caused by adhesive creep and aging in pure adhesive bonding schemes. Simultaneously, the polymer adhesive layer located between the adapter 3 and the metal substrate 1, with its inherent elasticity and low elastic modulus, effectively absorbs and buffers the thermal stress generated by the difference in thermal expansion coefficients between the metal substrate 1 and the adapter 3. This design decouples the huge thermal mismatch stress at two interfaces: the high-strength eutectic bonding interface is responsible for ensuring the mechanical and airtight integrity of the core sensing unit, while the elastic adhesive interface is dedicated to stress buffering. Therefore, this structure simultaneously overcomes the risk of thermal stress cracking in traditional eutectic bonding direct connection schemes and the problem of insufficient long-term accuracy and reliability in traditional pure adhesive bonding schemes, achieving a balance between high airtightness, low thermal stress, and long-term measurement stability.

[0026] In some embodiments, the metal base 1 is provided with an M1 threaded connection hole 8, which is used to connect the gas path of the gas pressure to be measured.

[0027] In some embodiments, the first adhesive layer is a UV-curable adhesive layer.

[0028] This embodiment utilizes UV-curable adhesive, which offers several technological advantages. First, the curing process is triggered by UV light, enabling rapid curing (from seconds to minutes), significantly improving encapsulation efficiency and making it suitable for mass production. Second, the curing process is a cold curing process, where the reaction is initiated only in the localized adhesive application area by light irradiation, avoiding overall heating that could cause thermal damage to the bonded chip components (especially the eutectic bonding layer) and surrounding precision parts.

[0029] Of course, other types of fast-curing adhesives can also be used for the first bonding layer, such as visible light curing adhesives, moisture curing adhesives, or two-component fast-curing epoxy resins. The key to selection lies in its curing speed, curing shrinkage rate, final mechanical properties (especially elastic modulus and elongation at break), and adhesion strength to the metal and glass interface, which must meet the process requirements of stress buffering and rapid, precise positioning and curing.

[0030] In some embodiments, the coefficient of thermal expansion of the glass material of the adapter 3 is between that of the silicon material of the silicon-based piezoresistive pressure-sensitive chip 2 and the coefficient of thermal expansion of the metal material of the metal base 1.

[0031] In some embodiments, the adapter 3 is made of a transparent or translucent material to facilitate UV curing of the UV-curable adhesive layer between the adapter 3 and the silicon-based piezoresistive pressure-sensitive chip 2.

[0032] In some embodiments, the packaging structure further includes electrical interconnect components and a protective cover 6; the electrical interconnect components include a plurality of gold-plated spring sheets 4 fixed on the metal base 1, and metal leads that connect the pads on the silicon-based piezoresistive pressure-sensitive chip 2 to the corresponding gold-plated spring sheets 4 by wire bonding; the protective cover 6 is disposed on the metal base 1 to form a sealed cavity for accommodating the chip and the electrical interconnect components, and the protective cover 6 has a reference pressure hole 7 communicating with the sealed cavity.

[0033] In this embodiment, the electrical interconnection between the gold-plated spring sheet 4 and the gold wire leads provides a standard interface for achieving reliable electrical connection within a very limited space. The gold-plated spring sheet 4 possesses excellent conductivity, elastic contact capability, and corrosion resistance, facilitating plug-and-play connection with the socket of an external scanning valve. The gold wire bonding technology is mature, with small connection points and reliable strength, and the natural curvature of the gold wire can absorb some mechanical stress. The core function of the protective cover 6 is physical protection and establishing a reference pressure benchmark. Its reference pressure port 7 ensures that the sensor back cavity (reference cavity) is connected to the external atmospheric pressure, which is the physical basis for the normal operation of the differential pressure sensor. At the same time, the protective cover 6 isolates the fragile chip, gold wires, and other critical components from the environment, preventing mechanical damage, dust contamination, and direct moisture intrusion, significantly improving the sensor's environmental robustness and long-term service life.

[0034] Of course, electrical interconnection is not limited to gold wire bonding; copper wire bonding, aluminum wire bonding, etc., can also be used. The reference air pressure hole 7 of the protective cover 6 can be designed as a straight hole 10, a labyrinth hole, or covered with a breathable and waterproof membrane, depending on the application scenario requirements, to balance the pressure response speed and dustproof and waterproof requirements.

[0035] In some embodiments, the protective cover 6 is a high-temperature resistant resin cover made by 3D printing. The protective cover 6 and the metal base 1 are connected by adhesive.

[0036] In some embodiments, the metal base 1 is an aerospace-grade aluminum alloy base. This base material is specifically chosen for the harsh operating conditions where the sensor needs to operate for extended periods at high temperatures (e.g., 80°C) and under continuous mechanical pressure loads. In such applications, the packaged sensor is typically mounted as an independent unit in a high-density matrix within corresponding slots or holes. The contact electrodes within the slots / holes are directly pressed onto the gold-plated spring sheet 4 on the outside of the metal base 1 to achieve electrical connection. If conventional base materials such as plastic or resin are used, creep and softening are likely to occur under long-term high-temperature conditions, leading to structural deformation and potentially compromising the integrity of the interface between the chip and the base, or even causing breakage. Aerospace-grade aluminum alloy, due to its excellent high-temperature strength, creep resistance, and low coefficient of thermal expansion, maintains superior dimensional stability under these conditions. It not only resists deformation itself but also provides a robust mechanical foundation for the entire packaging structure, thereby ensuring the measurement reliability and lifespan of the sensor under long-term pressure and temperature cycling.

[0037] Furthermore, considering the specific structure of the metal base 1 illustrated, the force and positioning mechanism of this encapsulation structure in the installed state is optimized. The encapsulation structure has a first side and a second side arranged opposite to each other: the outermost layer of the first side is formed by a side wall of the metal base 1, and the outermost layer of the second side is formed by the extended end of the gold-plated spring sheet 4. When the encapsulation structure is inserted into the corresponding slot or hole of an external system, the gold-plated spring sheet 4 first abuts against the contact electrode in the slot / hole and is subjected to a compressive force towards the first side. This compressive force pushes the entire encapsulation structure to move along the second side towards the first side until the rigid side wall of the metal base 1 tightly abuts against the inner wall of the other side of the slot or hole. Because the metal base 1 is made of high-rigidity aerospace aluminum alloy, its resistance to deformation is far greater than that of the spring sheet, enabling the encapsulation structure to achieve rapid and precise self-positioning within the installation space. Ultimately, the packaging structure achieves mechanical fixation through the contact between one side of the rigid base and the stable surface of the inner wall of the slot, while a reliable electrical connection is achieved through the continuous pressing of the other side of the elastic gold-plated spring sheet 4 with the contact electrode, forming a stable installation interface of "rigid positioning on one side and elastic electrical connection on the other side", which effectively improves the connection reliability and signal stability of the sensor in a vibration environment.

[0038] In some embodiments, the overall dimensions of the package structure (length × width × height) are no greater than 4.7mm × 4.4mm × 3.5mm, and the dimensions of the silicon-based piezoresistive pressure-sensitive chip 2 are no greater than 2.45mm × 2.45mm × 3mm.

[0039] The strict limitation on the overall and core chip dimensions in this embodiment is key to the direct application of this packaging technology to high-density electronic pressure scanning valves. Electronic pressure scanning valves require the integration of dozens to hundreds of independent measurement channels within a limited volume, necessitating extremely miniaturization of each sensor unit. The dimensional boundaries specified in this embodiment (overall ≤ 4.7mm × 4.4mm × 3.5mm) ensure that the sensors can meet the design requirements of a high-density matrix arrangement in three-dimensional space, providing a physical basis for achieving multi-channel synchronous pressure measurement. It is worth noting that achieving high-reliability packaging under such a small volume constraint increases the technical difficulty exponentially. This precisely underscores the necessity and effectiveness of the series of technical solutions described above, such as "glass adapter 3 buffering thermal stress," "UV-cured adhesive for precise positioning," and the "limiting assembly device ensuring consistency." It is the synergistic effect of these solutions that allows all necessary components, including the chip, adapter 3, interconnects, and seals, to be accommodated within a millimeter-level space, while ensuring that the airtightness, long-term stability, and resistance to environmental stress between components are not compromised. Therefore, this size limitation is not only a result of application requirements, but also a concentrated reflection of the high integration and high reliability design capabilities of this packaging technology solution.

[0040] In some embodiments, a resin connector 5 is also included. The resin connector 5 is connected to the metal base 1 and located inside the protective cover 6, forming a sealed cavity together with the protective cover 6. The resin connector 5 is provided with an installation channel for the gold-plated spring sheet 4 to pass through. The gold-plated spring sheet 4 is interference-fitted or snap-fitted to the inner wall of the installation channel.

[0041] In this embodiment, the resin connector 5 serves as an independent intermediate structural component, achieving functional integration and assembly optimization. Firstly, it provides precise and robust mechanical fixation (through interference fit or snap-fit) for the gold-plated spring sheet 4, ensuring the dimensional stability and insertion / removal durability of the external electrical connection interface and avoiding assembly stress or positioning inaccuracies that might result from directly fixing the spring sheet to the metal base 1. Secondly, using resin materials (such as engineering plastics) to manufacture this component allows for the utilization of its insulating properties to provide additional electrical isolation between the spring sheets, enhancing safety.

[0042] In some embodiments, the through-hole 10 and the internal air passage 9 are coaxial at the connection point, which requires high positioning accuracy. Therefore, using the limiting assembly device described in Embodiment 3 below to assist in packaging will greatly improve the alignment accuracy of the through-hole 10 and the internal air passage 9.

[0043] Example 2 The present invention also provides a packaging method for manufacturing the packaging structure in Embodiment 1, comprising the following steps: A metal substrate 1 and a chip assembly are provided; wherein the chip assembly is formed by bonding an adapter 3 and a silicon-based piezoresistive pressure-sensitive chip 2. The chip assembly is bonded to the corresponding position on the metal base 1 using a polymer adhesive layer; Gold-plated spring sheets 4 are mounted on the metal base 1, and the pads of the sensitive chip are electrically connected to the corresponding gold-plated spring sheets 4 through wire bonding process. Install the protective cover 6 to form a sealed cavity and complete the encapsulation.

[0044] This packaging method moves the most precise "chip-interface 3" eutectic bonding step, which has the highest requirements for cleanliness and process environment, to the forefront. This step is performed by chip or component suppliers with the corresponding clean production lines and process capabilities. The packaging plant or customer receives a highly intact "chip assembly," and subsequent work mainly involves mechanical assembly, bonding, and electrical interconnection. This division of labor optimizes the supply chain, allowing packaging plants to focus on their expertise in macroscopic precision assembly and sealing processes without investing in and maintaining expensive eutectic bonding equipment and ultra-clean environments. This reduces overall manufacturing costs, increases production flexibility, and helps ensure the consistency of the core sensing unit performance in the final product.

[0045] Of course, depending on the level of production integration, the eutectic bonding step can also be incorporated into the overall process of the packaging plant or the customer to achieve full-process control.

[0046] In some embodiments, the step of bonding the chip assembly to the corresponding position on the metal substrate 1 includes: UV-curable adhesive is applied to the interface between the chip assembly and the metal substrate 1. A limiting assembly device is used to relative position and press-fit the chip assembly and the metal base 1. The UV-curable adhesive is irradiated to cure it, thereby achieving bonding between the chip assembly and the metal substrate 1.

[0047] Example 3 The present invention also provides a limiting assembly device for the packaging method of Embodiment 2. The device is a multi-layer locking structure, including: a bottom cover 11, a metal base locking layer 12, a sensitive element locking layer 13, and a pressing layer 14. The metal base locking layer 12 is detachably mounted on the bottom cover 11 and is provided with a locking groove 16 for accommodating the metal base 1; the sensitive element locking layer 13 is detachably mounted on the metal base locking layer 12 and is provided with a positioning hole 17 for guiding the placement of the sensitive element or adapter 3; the pressing layer 14 is detachably mounted on the sensitive element locking layer 13 and is provided with a pressing post 18 coaxial with the positioning hole 17 for applying pressure.

[0048] This limiting assembly device is the core tooling for achieving high-precision, high-efficiency, and high-consistency packaging in this method. Its multi-layered locking design uses mechanical hard locking to completely determine the spatial relationship between the metal base 1 and the chip assembly based on the machining accuracy of the mold, thus eliminating the uncertainty of manual operation. Specifically: the bottom cover 11 engages with the metal base locking layer 12 to uniquely and correctly position the base; that is, the cross-section of the locking groove 16 and the bottom surface dimensions and shape of the metal base 1 are exactly the same. Of course, due to manufacturing limitations, there will inevitably be tolerances between the two, which can be controlled within a reasonable range, such as ±0.01mm. In principle, as long as precise assembly of the two can be achieved, it is acceptable. After the sensitive element locking layer 13 is superimposed, its positioning holes 17 precisely define the planar position of the chip assembly. Finally, the clamping layer 14 provides vertical and uniform clamping force through flexible clamping posts 18, ensuring uniform adhesive layer and eliminating air bubbles. The entire assembly process is clear in its steps, simple to operate, and has low dependence on operator skills.

[0049] In some embodiments, at least the end face of the clamping post 18 that contacts the chip assembly is made of a flexible material and its dimensions are adapted to the positioning hole 17. The cross-sectional dimensions and shape of the positioning hole 17 are the same as those of the chip assembly, which helps to improve positioning accuracy.

[0050] The flexible clamping pile 18 avoids scratching the fragile chip surface with hard materials.

[0051] In some embodiments, the device is a multi-station structure, and the metal base positioning layer 12, the sensitive element positioning layer 13 and the clamping layer 14 are respectively provided with a plurality of positioning grooves 16, positioning holes 17 and clamping pins 18, which can simultaneously limit the assembly of multiple sensor components.

[0052] This device is particularly suitable for mass production, ensuring that each sensor product has almost identical assembly precision, thereby achieving excellent and consistent product performance.

[0053] In some embodiments, at least one of the bottom cover 11, the locking layer, and the pressing layer 14 of the limiting assembly device can be made of transparent or translucent glass. This material choice gives the device excellent light transmittance. After the chip assembly and metal base 1 are precisely positioned and pressed together, the assembly does not need to be removed from the device. The ultraviolet light source can directly pass through the glass device layer and irradiate the ultraviolet curing adhesive layer at the junction of the chip assembly and the metal base 1, thereby achieving in-situ, rapid curing. This design not only simplifies the operation steps and avoids possible micro-displacement during the transfer process, but also ensures the absolute fixation of the relative position of the components at the moment of curing, further improving the packaging alignment accuracy and process consistency.

[0054] In some embodiments, the bottom cover 11 is also provided with a drain hole 15. After the chip assembly is manufactured, the drain hole 15 is used to allow a push rod or push pin to be inserted from the back of the drain hole 15 and push out the chip assembly in the slot 16.

[0055] In some embodiments, the layers are precisely positioned and assembled by the cooperation of positioning grooves 19 and positioning bosses.

[0056] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A silicon-based piezoresistive differential pressure sensor packaging structure, characterized in that, include: A metal base with a through-type internal air passage; The adapter is made of glass and is fixed to the upper surface of the metal base by a first adhesive layer. The adapter has a through hole inside that communicates with the internal air passage of the metal base. The first adhesive layer is a polymer adhesive layer with stress buffering capacity. The silicon-based piezoresistive pressure-sensitive chip is fixed to the upper surface of the adapter through a eutectic bonding layer, and its position corresponds to that of the through hole, so that the pressure to be measured transmitted by the internal air path can act on the chip.

2. The silicon-based piezoresistive differential pressure sensor packaging structure according to claim 1, characterized in that: The first adhesive layer is a UV-curable adhesive layer.

3. The silicon-based piezoresistive differential pressure sensor packaging structure according to claim 1, characterized in that: It also includes electrical interconnect components and a protective cover; the electrical interconnect components include a plurality of gold-plated spring sheets fixed on the metal base, and metal leads that connect the pads on the silicon-based piezoresistive pressure-sensitive chip to the corresponding gold-plated spring sheets via wire bonding; the protective cover is disposed on the metal base to form a sealed cavity for accommodating the chip and the electrical interconnect components, and the protective cover has a reference pressure hole communicating with the sealed cavity.

4. The silicon-based piezoresistive differential pressure sensor packaging structure according to claim 1, characterized in that: The metal base is an aviation aluminum alloy base.

5. The silicon-based piezoresistive differential pressure sensor packaging structure according to claim 1, characterized in that: The overall dimensions of the packaging structure (length × width × height) are no greater than 4.7mm × 4.4mm × 3.5mm, and the dimensions of the silicon-based piezoresistive pressure-sensitive chip are no greater than 2.45mm × 2.45mm × 3mm.

6. The silicon-based piezoresistive differential pressure sensor packaging structure according to claim 3, characterized in that: It also includes a resin connector, which is connected to the metal base and located inside the protective cover, together with the protective cover forming the sealed cavity. The resin connector is provided with an installation channel for the gold-plated spring sheet to pass through, and the gold-plated spring sheet is interference-fitted or snap-fitted to the inner wall of the installation channel.

7. A packaging method for manufacturing a packaging structure as described in any one of claims 1-6, characterized in that, Includes the following steps: It provides a metal substrate and a chip assembly; wherein the chip assembly is composed of an adapter and a silicon-based piezoresistive pressure-sensitive chip bonded together. The chip components are bonded to the corresponding positions on the metal base using a polymer adhesive layer; Gold-plated spring sheets are mounted on the metal base, and the pads of the sensitive chip are electrically connected to the corresponding gold-plated spring sheets by wire bonding. Install a protective cover to form a sealed cavity, thus completing the encapsulation.

8. The packaging method according to claim 7, characterized in that, The step of bonding the chip assembly to the corresponding position of the metal base includes: UV-curable adhesive is applied to the interface between the chip assembly and the metal substrate; A limiting assembly device is used to relatively position and press-fit the chip assembly to the metal base; The ultraviolet-curable adhesive is irradiated to cure it, thereby achieving the bonding between the chip assembly and the metal substrate.

9. A limiting assembly device for the packaging method of claim 8, characterized in that, The device has a multi-layer locking structure, including: Bottom cover; A metal base mounting layer is detachably mounted on the bottom cover and is provided with a mounting groove for accommodating the metal base; The sensitive element mounting layer is detachably mounted on the metal base mounting layer and is provided with positioning holes for guiding the placement of the sensitive element or adapter. The clamping layer is detachably mounted on the sensitive element positioning layer and is provided with clamping posts coaxial with the positioning holes for applying pressure.

10. The limiting assembly device according to claim 9, characterized in that, The end face of the clamping post that contacts the chip assembly is made of a flexible material and its size is adapted to the positioning hole.

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