High-insulation anti-breakdown MEMS pressure sensor and packaging method thereof

Abstract

The invention discloses a high-insulation anti-breakdown MEMS pressure sensor and a packaging method thereof, and belongs to the technical field of MEMS sensor design and packaging. In order to solve the problems that an MEMS pressure sensor is weak in electric breakdown resistance and low in reliability under temperature cycle and overload conditions, the MEMS pressure sensor comprises an MEMS pressure sensing chip, a pressure bearing substrate, a pressure ring, a pressure sensing metal corrugated diaphragm, an insulating filling ring, liquid oil and a plugging steel ball, the pressure-bearing base body is provided with an inner cavity, and the MEMS pressure sensing chip is fixed in the inner cavity; the insulating filling ring is arranged in the inner cavity and is positioned around the MEMS pressure sensing chip; the pressure-sensitive metal corrugated diaphragm is connected with the end part of the pressure-bearing base body in a sealing manner through the pressing ring, so that a sealing cavity is defined by the pressure-sensitive metal corrugated diaphragm and the end part of the pressure-bearing base body, and the MEMS pressure-sensitive chip and the insulating filling ring are positioned in the sealing cavity; a gap in the sealing cavity is filled with liquid oil; an oil injection hole communicated with the sealing cavity is formed in the pressure-bearing base body, and the blocking steel ball is welded to the oil injection hole in a sealed mode. The invention is applied to the field of pressure sensors.

Description

Technical Field

[0001] This invention relates to a high-insulation, breakdown-resistant MEMS pressure sensor and its packaging method, belonging to the field of MEMS sensor design and packaging technology. Background Technology

[0002] Microelectromechanical systems (MEMS) pressure sensors have become core devices for pressure measurement in fields such as industrial automation, aerospace, automotive electronics, medical devices, and consumer electronics due to their advantages such as small size, high sensitivity, low power consumption, ease of mass production, and integration with readout circuits. Their core pressure-sensing unit is typically based on the piezoresistive effect of silicon material, converting the pressure signal into an electrical signal output via a Wheatstone bridge.

[0003] However, traditional MEMS pressure sensors face significant reliability challenges when used in harsh electrical environments involving high voltage, strong electric fields, frequent electrostatic discharge, or leakage risks. Silicon-based MEMS chips themselves have limited dielectric strength, and traditional packaging structures often focus on mechanical protection and dielectric isolation, with insufficient consideration for electrical insulation design. Common packaging methods, such as using a single metal shell filled with organic potting compound, while providing basic protection, still have significant drawbacks:

[0004] First, a single insulation path is prone to forming a breakdown channel under high voltage;

[0005] Secondly, the coefficient of thermal expansion of organic potting materials differs significantly from that of metals and silicon chips. When the temperature changes drastically, internal stress will be generated, affecting the zero point and long-term stability of the sensor.

[0006] Furthermore, when the sensor's isolation diaphragm ruptures due to mechanical overload, the conductive medium may directly penetrate and come into contact with the chip or leads, causing the sensor itself to fail or even endangering the electrical safety of the entire application system.

[0007] To address these issues, some improvements have been proposed in existing technologies, such as adding a ceramic insulating ring inside the metal casing or using multilayer potting materials. However, these methods are typically complex in structure, difficult to ensure process consistency, or introduce new reliability problems due to material performance mismatch at extreme temperatures, failing to fundamentally achieve a balance between high insulation strength, high electrical breakdown resistance, and excellent long-term stability.

[0008] Therefore, there is an urgent need in this field for an innovative sensor packaging structure and method that can provide multiple and reliable insulation protections for MEMS pressure-sensing chips in harsh electrical environments, effectively resist electrical breakdown, and maintain excellent pressure transmission performance and temperature stability, thereby significantly expanding the application scope of MEMS pressure sensors in key fields such as high-voltage electrical systems, energy exploration, and rail transportation. Summary of the Invention

[0009] The purpose of this invention is to solve the problems of weak electrical breakdown resistance and low reliability of MEMS pressure sensors under temperature cycling and overload conditions, and to provide a high-insulation, breakdown-resistant MEMS pressure sensor and its packaging method.

[0010] The present invention discloses a high-insulation, breakdown-resistant MEMS pressure sensor, comprising:

[0011] MEMS pressure-sensing chip, pressure-bearing substrate, pressure ring, pressure-sensing metal corrugated diaphragm, insulating filler ring, liquid oil and sealing steel balls;

[0012] The pressure-bearing substrate has an inner cavity, and the MEMS pressure-sensing chip is fixed in the inner cavity of the pressure-bearing substrate;

[0013] The insulating filling ring is disposed in the inner cavity and located around the MEMS pressure-sensitive chip; the pressure-sensitive metal corrugated diaphragm is sealed to the end of the pressure-bearing substrate through a pressure ring, together forming a sealed cavity, in which the MEMS pressure-sensitive chip and the insulating filling ring are located;

[0014] The voids within the sealed cavity are filled with liquid oil;

[0015] The pressure-bearing substrate has an oil injection hole that communicates with the sealing cavity, and a sealing steel ball is welded to the oil injection hole.

[0016] Preferably, the pressure-bearing substrate is a multi-layer composite structure, including an outer metal shell, an outer insulating layer, an inner metal shell, and an inner insulating layer stacked sequentially from the outside to the inside, as well as a transfer terminal penetrating the multi-layer composite structure.

[0017] Preferably, the outer metal shell, outer insulation layer, inner metal shell, inner insulation layer and adapter terminal are integrally formed by high-temperature sintering process.

[0018] Preferably, the electrical terminals of the MEMS pressure-sensitive chip are bonded to the adapter terminal via leads.

[0019] Preferably, the insulating filling ring fills the cavity space around and above the MEMS pressure-sensitive chip to reduce the amount of liquid oil filling.

[0020] Preferably, the insulating filler ring is used to increase the surface insulation distance between the MEMS pressure-sensitive chip and the pressure-sensitive metal corrugated diaphragm.

[0021] Preferably, the insulating filler ring is made of a highly insulating rigid material. When liquid oil leaks and the pressure-sensitive metal corrugated diaphragm deforms or ruptures inward, it provides mechanical support for the pressure-sensitive metal corrugated diaphragm and prevents the pressure-sensitive metal corrugated diaphragm from contacting the MEMS pressure-sensitive chip and its leads.

[0022] The present invention discloses a packaging method for a high-insulation, breakdown-resistant MEMS pressure sensor, comprising the following steps:

[0023] The MEMS pressure-sensing chip is fixed at a designated position within the inner cavity of the pressure-bearing substrate;

[0024] The electrical terminals of the MEMS pressure-sensitive chip are electrically interconnected with the adapter terminals on the pressure-bearing substrate via leads;

[0025] An insulating filler ring is installed in the inner cavity;

[0026] The pressure-sensitive corrugated metal diaphragm and the pressure ring are assembled in sequence, and the pressure ring, the pressure-sensitive corrugated metal diaphragm and the pressure-bearing substrate are annularly sealed and welded to form a sealed cavity;

[0027] Liquid oil is filled into the sealed cavity through the oil injection hole on the pressure-bearing substrate using a vacuum oil injection process;

[0028] The oil injection hole is sealed with steel balls to complete the final encapsulation.

[0029] Preferably, the manufacturing steps of the pressure-bearing matrix include:

[0030] The blanks of the outer metal shell, outer insulation layer, inner metal shell, inner insulation layer and adapter terminal are stacked according to the design and sintered at high temperature to form an integrated whole.

[0031] Preferably, the insulating filler ring is made of ceramic or high-performance engineering plastic and its shape matches the non-chip-accommodating area of ​​the pressure-bearing matrix cavity.

[0032] Advantages of this invention: This invention proposes a high-insulation, breakdown-resistant MEMS pressure sensor and its packaging method. It employs a multi-layered composite pressure-bearing substrate comprising an outer metal shell, an outer insulating layer, an inner metal shell, and an inner insulating layer, integrally formed through high-temperature sintering, constructing a high-strength double-layer insulating barrier that significantly improves the overall insulation strength and breakdown resistance of the sensor. By setting a large-volume insulating filler ring in the inner cavity, the amount of liquid silicone oil is significantly reduced, effectively mitigating the impact of thermal expansion and contraction stress caused by temperature changes on the core MEMS chip and improving long-term stability. Simultaneously, this insulating filler ring provides mechanical support and electrical isolation in case of extreme overload leading to oil leakage or deformation of the metal corrugated diaphragm, preventing the diaphragm from contacting internal leads or terminals and avoiding the risk of short circuits in the sensor and system. Furthermore, the overall packaging uses thermoforming welding and vacuum oil injection processes to form a reliable sealed cavity, effectively protecting the chip from media corrosion. The sensor supports multiple mounting methods, such as side O-rings or rear-end welding, enhancing environmental adaptability. Attached Figure Description

[0033] Figure 1 This is a cross-sectional view of the MEMS pressure-sensitive chip described in this invention;

[0034] Figure 2 This is a three-dimensional cross-sectional view of the MEMS pressure-sensitive chip described in this invention;

[0035] Figure 3 This is a cross-sectional view of the pressure-bearing matrix described in this invention;

[0036] Figure 4 This is a three-dimensional cross-sectional view of the pressure-bearing matrix described in this invention;

[0037] Figure 5 This is a cross-sectional view of the overall structure of the high-insulation, breakdown-resistant MEMS pressure sensor described in this invention;

[0038] Figure 6 This is a three-dimensional structural diagram of the high-insulation, breakdown-resistant MEMS pressure sensor described in this invention. Detailed Implementation

[0039] 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.

[0040] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0041] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the invention.

[0042] Example 1:

[0043] The following is combined Figures 1-6 This embodiment describes a high-insulation, breakdown-resistant MEMS pressure sensor, which includes:

[0044] MEMS pressure-sensitive chip 1, pressure-bearing substrate 2, pressure ring 301, pressure-sensitive metal corrugated diaphragm 302, insulating filler ring 303, liquid oil 305, and sealing steel ball 306;

[0045] The pressure-bearing substrate 2 has an inner cavity, and the MEMS pressure-sensing chip 1 is fixed in the inner cavity of the pressure-bearing substrate 2;

[0046] The insulating filling ring 303 is disposed in the inner cavity and located around the MEMS pressure-sensitive chip 1; the pressure-sensitive metal corrugated diaphragm 302 is sealed to the end of the pressure-bearing substrate 2 through the pressure ring 301, together forming a sealed cavity, in which the MEMS pressure-sensitive chip 1 and the insulating filling ring 303 are located.

[0047] The voids within the sealed cavity are filled with liquid oil 305;

[0048] The pressure-bearing substrate 2 has an oil injection hole that communicates with the sealing cavity, and a sealing steel ball 306 is welded to the oil injection hole.

[0049] Furthermore, the pressure-bearing substrate 2 is a multi-layer composite structure, including an outer metal shell 201, an outer insulation layer 202, an inner metal shell 203 and an inner insulation layer 204 stacked sequentially from the outside to the inside, and a transfer terminal 205 penetrating the multi-layer composite structure.

[0050] Furthermore, the outer metal shell 201, outer insulation layer 202, inner metal shell 203, inner insulation layer 204 and adapter terminal 205 are integrally formed by high-temperature sintering process.

[0051] Furthermore, the electrical terminals of the MEMS pressure-sensitive chip 1 are bonded to the adapter terminal 205 via lead 304.

[0052] Furthermore, the insulating filling ring 303 fills the cavity space around and above the MEMS pressure-sensitive chip 1 to reduce the amount of liquid oil 305 filled.

[0053] Furthermore, the insulating filler ring 303 is used to increase the surface insulation distance between the MEMS pressure-sensitive chip 1 and the pressure-sensitive metal corrugated diaphragm 302.

[0054] Furthermore, the insulating filler ring 303 is made of a highly insulating rigid material. When the liquid oil 305 leaks and the pressure-sensitive metal corrugated diaphragm 302 deforms or ruptures inward, it provides mechanical support for the pressure-sensitive metal corrugated diaphragm 302 and prevents the pressure-sensitive metal corrugated diaphragm 302 from contacting the MEMS pressure-sensitive chip 1 and its leads 304.

[0055] Example 2:

[0056] The following is combined Figures 1-6 This embodiment describes a packaging method for a high-insulation, breakdown-resistant MEMS pressure sensor, which includes the following steps:

[0057] The MEMS pressure-sensing chip 1 is fixed at a designated position within the inner cavity of the pressure-bearing substrate 2;

[0058] The electrical terminals of the MEMS pressure-sensitive chip 1 are electrically interconnected with the adapter terminal 205 on the pressure-bearing substrate 2 via lead 304;

[0059] An insulating filler ring 303 is installed in the inner cavity;

[0060] The pressure-sensitive corrugated metal diaphragm 302 and the pressure ring 301 are assembled in sequence, and the pressure ring 301, the pressure-sensitive corrugated metal diaphragm 302 and the pressure-bearing substrate 2 are annularly sealed and welded to form a sealed cavity;

[0061] Liquid oil 305 is filled into the sealed cavity through the oil injection hole on the pressure-bearing base 2 using a vacuum oil injection process.

[0062] The oil injection hole is sealed by welding with steel balls (306) to complete the final encapsulation.

[0063] Furthermore, the manufacturing steps of the pressure-bearing substrate 2 include:

[0064] The blanks of the outer metal shell 201, outer insulation layer 202, inner metal shell 203, inner insulation layer 204 and adapter terminal 205 are stacked according to the design and sintered at high temperature to form an integrated whole.

[0065] Furthermore, the insulating filling ring 303 is made of ceramic or high-performance engineering plastic and its shape matches the non-chip accommodating area of ​​the inner cavity of the pressure-bearing substrate 2.

[0066] In this invention, Figures 1-6 As shown, the main structure includes: MEMS pressure-sensitive chip, pressure-bearing substrate, pressure ring, pressure-sensitive metal corrugated diaphragm, insulating filler ring, liquid oil, and steel balls.

[0067] The MEMS pressure-sensitive chip 1 mainly includes: a silicon chip 101 and a sealing glass 102. The silicon chip 101 is formed into a pressure-sensitive structure and a Wheatstone bridge circuit structure using MEMS design and manufacturing technology. The sealing glass 102 supports the silicon chip 101 while isolating the encapsulation stress generated by subsequent bonding. The silicon chip 101 and the sealing glass 102 are processed into one piece using anodic bonding technology.

[0068] The pressure-bearing substrate mainly comprises: an outer metal shell 201, an outer insulating layer 202, an inner metal shell 203, an inner insulating layer 204, and a transition terminal 205. High-temperature sintering forms the outer metal shell 201, outer insulating layer 202, inner metal shell 203, inner insulating layer 204, and transition terminal 205 into a highly insulating and electrically breakdown-resistant pressure-bearing substrate 2. High-temperature sintering further forms the outer metal shell 201, outer insulating layer 202, inner metal shell 203, inner insulating layer 204, and transition terminal 205 into a high-strength, highly insulating, and electrically breakdown-resistant pressure-bearing substrate 2. The surface of the transition terminal 205 is gold-plated.

[0069] The metal pressure ring 301 is used for sensor encapsulation, welding positioning, and protection of the pressure-sensitive metal corrugated diaphragm 302.

[0070] The pressure-sensitive corrugated metal diaphragm 302 serves to isolate the measured medium from pressure transmission.

[0071] The silicon MEMS pressure chip 1 is bonded to a pre-reserved cavity within the pressure-bearing substrate 2. Electrodes on the chip are interconnected with the adapter terminal 205 using ultrasonic thermo-pressure welding with gold or aluminum wire 304. An insulating filling ring 303 is placed in the remaining space of the pressure-bearing substrate 2. The metal pressure ring 301, the pressure-sensitive metal corrugated diaphragm 302, and the pressure-bearing substrate 2 are integrated using thermo-fusion welding. Liquid oil 305 is used to fill the remaining space in the sealing structure using vacuum injection technology. Steel balls 306 are used to seal the oil injection hole of the pressure-bearing substrate using thermo-fusion welding technology to achieve a sealed sensor cavity and protect the MEMS pressure-sensitive chip.

[0072] The insulating filler ring 303 fills most of the space in the sealed chamber, greatly reducing the amount of liquid oil 305 and reducing the stress caused by the thermal expansion and contraction of the liquid oil due to temperature changes on the MEMS pressure-sensitive chip.

[0073] The insulating filler ring 303 increases the insulation distance between the chip and the external test medium, thus providing insulation protection.

[0074] The insulating filler ring 303 provides support and isolation when the sensor is subjected to an overload exceeding its own capacity, causing damage to the encapsulation structure and leakage of liquid oil 305, which causes deformation or cracking of the pressure-sensitive metal corrugated diaphragm 302. This prevents the metal corrugated diaphragm 302 from deforming or cracking and contacting the gold wire 304 or the adapter terminal 205, thus avoiding short circuits in the sensor itself and the application system.

[0075] A MEMS pressure sensor comprises a pressure ring, a pressure-sensitive corrugated metal diaphragm, an insulating filler ring, liquid oil, a MEMS pressure-sensitive chip, a pressure-bearing substrate, and sealing steel balls. The insulating filler ring and the MEMS pressure-sensitive chip are bonded to the pressure-bearing substrate. The pressure ring, pressure-sensitive corrugated metal diaphragm, pressure-bearing substrate, and sealing steel balls form a protective sealed cavity for the MEMS pressure chip using thermoforming welding technology. The insulating filler ring fills the sealed cavity, and the gap within the cavity is filled with liquid oil using vacuum injection technology. Gold or aluminum wires are used to interconnect the chip electrodes with adapter terminals on the pressure-bearing substrate, and the electrical signals from the chip are led out through the adapter terminals.

[0076] When pressure is applied to the corrugated diaphragm, the liquid oil in the sensor's sealed cavity transmits the pressure. The MEMS pressure-sensing chip senses the pressure and generates a piezoresistive effect. This piezoresistive effect causes a change in the resistance of the Wheatstone bridge within the MEMS chip. Under the excitation of the power supply, the pressure signal is converted into an electrical signal for output.

[0077] The sensor can be installed using either a side O-ring seal or a rear welding seal to measure the pressure of the external medium, allowing for flexible installation methods depending on the operating environment.

[0078] This invention uses vacuum sintering technology to manufacture the sensor body pressure-bearing substrate using metal and insulating materials. Hot melt welding technology is used to form a sealed pressure-bearing structure between the metal corrugated diaphragm and the substrate. The MEMS pressure chip is bonded to the sealed cavity of the substrate. The sealed cavity is filled with liquid oil using vacuum injection technology, and the oil injection hole is sealed with steel balls to protect the pressure chip from corrosion by harmful substances in the measured medium. At the same time, the packaging structure is designed with anti-breakdown isolation to improve the insulation strength and electrical breakdown strength of the sensor through structural protection, effectively improving product life and reliability.

[0079] While the invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that different dependent claims and features described herein can be combined in ways different from those described in the original claims. It is also understood that features described in conjunction with individual embodiments can be used in other described embodiments.

Claims

1. A high-insulation, breakdown-resistant MEMS pressure sensor, characterized in that it include: MEMS pressure-sensitive chip (1), pressure-bearing substrate (2), pressure ring (301), pressure-sensitive metal corrugated diaphragm (302), insulating filler ring (303), liquid oil (305) and sealing steel ball (306). The pressure-bearing substrate (2) has an inner cavity, and the MEMS pressure-sensing chip (1) is fixed in the inner cavity of the pressure-bearing substrate (2); The insulating filling ring (303) is disposed in the inner cavity and located around the MEMS pressure-sensitive chip (1); the pressure-sensitive metal corrugated diaphragm (302) is sealed to the end of the pressure-bearing substrate (2) through the pressure ring (301) to form a sealed cavity together, and the MEMS pressure-sensitive chip (1) and the insulating filling ring (303) are located in the sealed cavity. The voids in the sealed cavity are filled with liquid oil (305). The pressure-bearing substrate (2) has an oil injection hole that communicates with the sealing cavity, and the sealing steel ball (306) is welded to the oil injection hole.

2. The high-insulation, breakdown-resistant MEMS pressure sensor according to claim 1, characterized in that, The pressure-bearing substrate (2) is a multi-layer composite structure, including an outer metal shell (201), an outer insulation layer (202), an inner metal shell (203) and an inner insulation layer (204) stacked sequentially from the outside to the inside, and a transfer terminal (205) penetrating the multi-layer composite structure.

3. The high-insulation, breakdown-resistant MEMS pressure sensor according to claim 2, characterized in that, The outer metal shell (201), outer insulation layer (202), inner metal shell (203), inner insulation layer (204) and adapter terminal (205) are integrally formed by high-temperature sintering process.

4. A high-insulation, breakdown-resistant MEMS pressure sensor according to claim 2, characterized in that, The electrical terminals of the MEMS pressure-sensitive chip (1) are bonded to the adapter terminal (205) via leads (304).

5. A high-insulation, breakdown-resistant MEMS pressure sensor according to claim 1, characterized in that, The insulating filling ring (303) fills the cavity space around and above the MEMS pressure-sensitive chip (1) to reduce the amount of liquid oil (305) filling.

6. A high-insulation, breakdown-resistant MEMS pressure sensor according to claim 1 or 5, characterized in that, The insulating filler ring (303) is used to increase the surface insulation distance between the MEMS pressure-sensitive chip (1) and the pressure-sensitive metal corrugated diaphragm (302).

7. A high-insulation, breakdown-resistant MEMS pressure sensor according to claim 1, characterized in that, The insulating filler ring (303) is made of a highly insulating rigid material. When liquid oil (305) leaks and the pressure-sensitive metal corrugated diaphragm (302) deforms or breaks inward, it provides mechanical support for the pressure-sensitive metal corrugated diaphragm (302) and prevents the pressure-sensitive metal corrugated diaphragm (302) from contacting the MEMS pressure-sensitive chip (1) and its leads (304).

8. A packaging method for manufacturing a high-insulation, breakdown-resistant MEMS pressure sensor, characterized in that, Includes the following steps: The MEMS pressure-sensitive chip (1) is fixed at a designated position inside the pressure-bearing substrate (2); The electrical terminals of the MEMS pressure-sensitive chip (1) are electrically interconnected with the adapter terminals (205) on the pressure-bearing substrate (2) via leads (304); An insulating filler ring (303) is installed in the inner cavity; The pressure-sensitive corrugated metal diaphragm (302) and the pressure ring (301) are assembled in sequence, and the pressure ring (301), the pressure-sensitive corrugated metal diaphragm (302) and the pressure-bearing substrate (2) are annularly sealed and welded to form a sealed cavity; Liquid oil (305) is filled into the sealed cavity through the oil injection hole on the pressure-bearing base (2) using a vacuum oil injection process. The oil injection hole is sealed by welding with steel balls (306) to complete the final encapsulation.

9. A high-insulation, breakdown-resistant MEMS pressure sensor according to claim 8, characterized in that, The manufacturing steps of the pressure-bearing substrate (2) include: The blanks of the outer metal shell (201), outer insulation layer (202), inner metal shell (203), inner insulation layer (204) and adapter terminal (205) are stacked according to the design and sintered at high temperature to form an integrated whole.

10. A high-insulation, breakdown-resistant MEMS pressure sensor according to claim 8, characterized in that, The insulating filler ring (303) is made of ceramic or high-performance engineering plastic and its shape matches the non-chip accommodating area of ​​the inner cavity of the pressure-bearing substrate (2).

Images