Miniature pressure sensor packaging structure

Abstract

The invention discloses a miniature pressure sensor packaging structure. The miniature pressure sensor packaging structure comprises a shell, isolation flexible glue and a flexible circuit board, the substrate is arranged in the shell, a silicon wafer is arranged on the substrate, the isolation flexible glue covers the silicon wafer, one end of the flexible circuit board is connected with the silicon wafer, and the other end of the flexible circuit board extends out of the shell; the shell is made of polymer resin and wraps and seals the isolation flexible glue, the silicon wafer and the substrate. The rigid strength is good, high-pressure resistance, high-temperature resistance, acid and alkali resistance and corrosion resistance are achieved, and the overall size is small.

Description

Technical Field

[0001] The invention belongs to the field of pressure sensors and relates to a micro pressure sensor packaging structure. Background Art

[0002] Pressure sensors are the most commonly used sensors in industrial practice. According to the sensor principle, they can be divided into metal strain gauge type, ceramic type, diffused silicon type, silicon-sapphire type, piezoelectric type, capacitor or resonance type, etc. At present, many pressure sensors, such as those used in oil well measurement, have many defects or limitations, such as: large size limits application, metal shell packaging is not resistant to acid and alkali and is easy to corrode, the use of silicone oil as a medium for isolation requires a special isolation diaphragm, which limits the material selection, and some sensors have defects such as easy to break, insufficient range, and not resistant to high temperature.

[0003] In order to better and timely understand the well conditions during oil drilling, various parameters downhole need to be measured. Well pressure parameters are important data. The downhole oil measurement environment is harsh, with pressures as high as 100MPa and temperatures as high as 150℃. There are drilling equipment and drilling fluids in the well, so a measuring device that can withstand acid and alkali environments and has good corrosion resistance, seismic resistance and impact resistance is needed.

[0004] In order to meet the needs of measuring downhole pressure parameters, a tiny pressure sensor is needed. The first problem that this sensor needs to solve is to be able to work normally in complex drilling wells. Therefore, compared with many existing pressure sensors, the key issues of pressure sensors in this application environment are packaging methods, packaging materials and corresponding mass production. However, existing pressure sensors cannot meet the packaging requirements and cannot withstand high pressure, high temperature and high corrosion working environments. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned shortcomings of the prior art and provide a micro pressure sensor packaging structure with good rigidity, high pressure resistance, high temperature resistance, acid and alkali resistance, corrosion resistance and small overall size.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A micro pressure sensor packaging structure, comprising a housing, an isolation soft glue and a flexible circuit board;

[0008] The substrate is arranged inside the shell, a silicon wafer is arranged on the substrate, an isolation soft glue covers the silicon wafer, one end of the flexible circuit board is connected to the silicon wafer, and the other end extends out of the shell;

[0009] The shell is made of polymer resin, and the shell wraps and seals the isolation soft glue, silicon wafer and substrate.

[0010] Preferably, a pressure transmission port is provided at the top of the shell, one end of the pressure transmission port is connected to the outside of the shell, and the other end is connected to the isolation soft rubber, and an isolation soft rubber is provided in the pressure transmission port.

[0011] Furthermore, the pressure transmission port adopts a capillary tube filled with insulating soft rubber.

[0012] Furthermore, the inner diameter of the capillary is 1 mm.

[0013] Preferably, the substrate is made of glass.

[0014] Preferably, one end of the flexible circuit board extending out of the housing is connected to the circuit interface.

[0015] Preferably, the shell is made of BEEP6109A / B material.

[0016] Preferably, the shell is a capsule-shaped structure.

[0017] Furthermore, the shell has a diameter of 10 mm and a height of 18 mm.

[0018] Preferably, the size of the silicon wafer and the substrate are both 2.8 mm×2.8 mm.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention adopts a high temperature and high pressure resistant polymer resin as the shell of the packaging structure, which has a tensile strength of 67MPa, an elastic modulus of 3500MPa, a bending strength of 100MPa, and a Barcol hardness of 45. It is solidified and formed through a customized mold and used as the shell package of the sensor. It is easy to produce, has good rigidity, is acid and alkali resistant, corrosion resistant, and has a small overall volume. The silicon wafer is attached to the substrate, and the electrical signal is led out through the flexible circuit board welded on the wafer to provide an electrical interface to the control unit. With the use of a flexible circuit board, the circuit will not break during the resin curing and forming process, and the gold wire binding process and the like are eliminated.

[0021] Furthermore, a capillary is used as a pressure inlet, filled with soft colloid, and connected to the soft colloid covering the silicon wafer, serving as an isolation layer between the wafer inside the sensor and the external medium. The external pressure of the sensor is transmitted to the surface of the silicon wafer through this tube, and acts on the diffused silicon layer to generate strain, which can convert the pressure into an electrical signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the packaging structure of the micro pressure sensor of the present invention;

[0023] Figure 2 It is a schematic diagram of the structure of the measuring capsule of the present invention;

[0024] Figure 3is a schematic cross-sectional view of a measuring capsule of the present invention;

[0025] Figure 4 It is a schematic diagram of the drilling system of the present invention.

[0026] Among them: 1-pressure transmission port; 2-isolation soft glue; 3-silicon wafer; 4-substrate; 5-housing; 6-circuit interface; 7-flexible circuit board; 8-injection device; 9-vibrating screen; 10-recovery device. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0028] It should be noted that the words "front", "rear", "left", "right", "up" and "down" used in the following description refer to directions in the drawings, and the words "inside" and "outside" refer to directions toward or away from the geometric center of a specific component, respectively.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0030] In order to meet the special applications of the oil drilling measurement industry, this design adopts the diffused silicon technology principle, which has mature current technical theory, perfect raw material supply chain, is suitable for small-size differential pressure detection, and has good temperature resistance.

[0031] The integrated process technology is used to dope and diffuse the microcrystalline glass, and along the characteristic crystal direction of the single crystal silicon wafer. The elastic mechanical properties of silicon material are used to perform anisotropic micromachining on the same cut silicon material, and finally a silicon sensitive element with a Wheatstone bridge and a precise mechanical structure is manufactured.

[0032] The silicon sensitive element is welded on the gold-plated flexible circuit board 7 through a specific process, so as to lead out the electrical interface for power input and detection signal output. Special equipment and corresponding molds for polymer resin curing are designed, and finally a sensor that can be used for underground oil well measurement is made.

[0033] like Figure 1As shown, the micro pressure sensor packaging structure of the present invention includes a pressure transmission port 1, an isolation soft glue 2, a silicon wafer 3, a substrate 4, a polymer resin, a circuit interface 6 and a flexible circuit board 7.

[0034] The silicon wafer 3 is disposed on the substrate 4 , and the isolation soft glue 2 covers the silicon wafer 3 .

[0035] The polymer resin serves as the shell 5 of the packaging structure, and wraps the isolation soft glue 2, the silicon wafer 3 and the substrate 4.

[0036] A pressure inlet 1 is provided on the top of the shell 5 , one end of the pressure inlet 1 is connected to the outside of the polymer resin, and the other end is connected to the isolation soft glue 2 .

[0037] A flexible circuit board 7 is disposed in the housing 5 . One end of the flexible circuit board 7 is connected to the silicon wafer 3 , and the other end thereof extends out of the housing 5 .

[0038] One end of the flexible circuit board 7 extending out of the polymer resin is connected to the circuit interface 6 .

[0039] Each component is described separately and in detail below.

[0040] Pressure inlet 1:

[0041] The pressure transmission port 1 is a capillary with an inner diameter of 1 mm filled with an isolation soft glue 2. It is an industrial silicone sealant, a single-component room temperature curing silicone rubber, temperature resistant -60 to 300°C, shock resistant, aging resistant, anti-leakage, and good adhesion. The isolation soft glue 2 separates the external medium and the silicon wafer 3 inside the sensor. The capillary aperture is very small to prevent particles from entering or clogging.

[0042] Isolation soft glue 2:

[0043] The surface of the silicon wafer 3 is covered with a layer of isolation soft glue 2, which is used to protect the surface of the silicon wafer 3 and to connect the capillary. The pressure can directly reach the surface of the silicon wafer 3 through the pressure transmission port 1.

[0044] Silicon wafer 3:

[0045] like Figure 3 As shown, the customized 2.8mm×2.8mm tiny diffused silicon pressure sensor wafer is the core device for converting the physical quantity of pressure into the electrical signal quantity.

[0046] Substrate 4:

[0047] It uses a tiny glass material of 2.8mm×2.8mm, which can withstand high temperatures of 180°C and high pressures of 150MPa. It serves as the substrate 4 of the silicon wafer 3 and carries the core of pressure conversion.

[0048] Polymer resin:

[0049] The core components of the pressure sensor, the isolation soft glue 2, the silicon wafer 3, the substrate 4, the flexible circuit board 7 and the capillary are all sealed in this polymer resin material by means of a special mold. After curing, this material can withstand high temperatures of 200°C and high pressures of 150MPa, and has the characteristics of corrosion resistance, acid and alkali resistance.

[0050] Circuit interface 6:

[0051] As the electrical interface of the sensor, it is used to supply power to the sensor and output signals.

[0052] Flexible circuit board 7:

[0053] As a transition line between the sensor core semiconductor device and the circuit interface 6 , it can be freely bent and shaped, with one end welded on the silicon wafer 3 and the other end led out of the housing 5 .

[0054] The flexible circuit board 7 adopts a flexible ultra-thin circuit board, and the circuit will not be broken during the resin curing and forming process, eliminating the process of gold wire binding and the like.

[0055] The application object of the present invention is a small pressure measuring device. According to the application requirements, two packaging methods can be adopted for application.

[0056] Method 1:

[0057] By using the present invention, a packaged micro pressure sensor probe is first manufactured, and then the probe is welded and installed on a corresponding circuit board. After debugging, testing and verification, the probe and all circuit structures are finally sealed and formed at one time with corresponding packaging materials. The material is appropriately selected according to application requirements, and the pressure detection product with different shapes can be sealed according to application requirements.

[0058] Method 2:

[0059] According to the principle of the present invention, all components and application circuit structures required for the sensor are packaged together with the polymer resin material of the present invention to produce a pressure detection product for a specific target application.

[0060] By using the present invention, combined with a low-power processing chip, power management and corresponding circuits, a microchip intelligent downhole measurement capsule can be made, such as Figure 2 As shown. The minimum size of the capsule can be 10 mm in diameter and 18 mm in height. The overall specific gravity is close to the specific gravity of the drilling fluid in the oil drilling equipment, and it can move freely inside the drilling circulation pipeline with the drilling fluid. This application implementation case adopts the above method 2:

[0061] First, a sealing mold is designed and prepared. The final product produced after sealing with this mold is the final product. The mold defines the shape and size of the final product.

[0062] Secondly, prepare all the materials mentioned in the present invention, except for the packaging materials; prepare the corresponding circuit and internal structure materials; and assemble all the materials into a semi-finished product.

[0063] Finally, the semi-finished product is placed in a mold and filled with polymer resin material for sealing. After solidification and forming, the product that comes out of the mold is the finished product.

[0064] When the microchip intelligent downhole measurement capsule is used in the oil drilling process, it is injected into the working pipe string through the injection device 8, and it will circulate to the bottom of the well with the drilling fluid, and then return to the surface from the annulus in the well. It can be recovered by the recovery device 10 at the filter vibrating screen 9 of the drilling equipment. During the whole process, the intelligent capsule continuously measures and records downhole parameters such as temperature and pressure, and the data is recovered, downloaded and processed on the ground to achieve the purpose of real-time monitoring of downhole dynamic environmental parameters. See the schematic diagram of the drilling system. Figure 4 .

[0065] It uses high-molecular unsaturated polyester resin that is resistant to high temperature and high pressure, with a tensile strength of 67MPa, elastic modulus of 3500MPa, bending strength of 100MPa, and Barcol hardness of 45. It is solidified and formed through a customized mold and used as the shell package of the sensor. It is easy to produce, has good rigidity, is acid and alkali resistant, corrosion resistant, and has a small overall size.

[0066] The capillary is used as the pressure inlet, filled with soft colloid, and connected to the soft colloid covering the silicon wafer 3, as an isolation layer between the internal wafer of the sensor and the external medium. The external pressure of the sensor is transmitted to the surface of the silicon wafer 3 through this tube, and acts on the diffused silicon layer to generate strain, which can convert the pressure into an electrical signal.

[0067] The silicon wafer 3 is attached to the substrate 4, and the electrical signal is led out through the flexible circuit board 7 welded on the silicon wafer 3 to provide an electrical interface to the control unit. The flexible ultra-thin circuit board is used, and the circuit will not break during the resin curing process, eliminating the process of gold wire binding.

[0068] Design special molds for polymer resin curing to ensure the consistency of sensor production and the feasibility of mass production.

[0069] The present invention adopts the specially made small-sized diffused silicon pressure sensor wafer which is mature in the industry, and can greatly reduce the volume size of the pressure sensor, so as to be more suitable for the application in the narrow space underground.

[0070] The present invention innovatively adopts a soft and freely deformable colloid, that is, an isolation soft gel 2 to replace the silicone oil medium for isolation, which simplifies the assembly process, eliminates the isolation film, and eliminates the problem of irreversible deformation of the isolation film in high-range applications.

[0071] The innovative use of polymer resin material as the packaging shell makes the sensor packaging easy to shape. The resin material after shaping and curing has high rigidity and good toughness. While effectively protecting the pressure sensor wafer, it is also resistant to corrosion, acid and alkali, and rolling and impact.

[0072] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0073] It should be understood that the above description is for illustration and not for limitation. Many embodiments and many applications beyond the examples provided will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of the present teachings should not be determined with reference to the above description, but rather with reference to the foregoing claims and the full scope of equivalents to which such claims are entitled. For the purpose of comprehensiveness, all articles and references, including disclosures of patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the foregoing claims is not intended to be a waiver of such subject matter, nor should it be considered that the applicant has not considered such subject matter to be part of the disclosed inventive subject matter.

Claims

1. A micro pressure sensor packaging structure, characterized in that: It comprises a housing (5), an isolation soft glue (2) and a flexible circuit board (7); The substrate (4) is arranged inside the housing (5), a silicon wafer (3) is arranged on the substrate (4), the isolation soft glue (2) covers the silicon wafer (3), one end of the flexible circuit board (7) is connected to the silicon wafer (3), and the other end extends out of the housing (5); The shell (5) is made of polymer resin, and the shell (5) wraps and seals the isolation soft glue (2), the silicon wafer (3) and the substrate (4).

2. The micro pressure sensor packaging structure according to claim 1, characterized in that: A pressure transmission port (1) is provided at the top of the shell (5), one end of the pressure transmission port (1) is connected to the outside of the shell (5), and the other end is connected to the isolation soft rubber (2), and the isolation soft rubber (2) is provided in the pressure transmission port (1).

3. The micro pressure sensor packaging structure according to claim 2, characterized in that: The pressure transmission port (1) is a capillary tube filled with an isolation soft rubber (2).

4. The micro pressure sensor packaging structure according to claim 3, characterized in that: The inner diameter of the capillary is 1 mm.

5. The micro pressure sensor packaging structure according to claim 1, characterized in that: The substrate (4) is made of glass.

6. The micro pressure sensor packaging structure according to claim 1, characterized in that: One end of the flexible circuit board (7) extending out of the housing (5) is connected to the circuit interface (6).

7. The micro pressure sensor packaging structure according to claim 1, characterized in that: The shell (5) is made of BEEP6109A / B material.

8. The micro pressure sensor packaging structure according to claim 1, characterized in that: The shell (5) is a capsule-shaped structure.

9. The micro pressure sensor packaging structure according to claim 8, characterized in that: The shell (5) has a diameter of 10 mm and a height of 18 mm.

10. The micro pressure sensor packaging structure according to claim 1, characterized in that: The sizes of the silicon wafer (3) and the substrate (4) are both 2.8 mm×2.8 mm.

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