Packaging structure and packaging method of high-integration micro-nano magnetic field sensor

Abstract

The application provides a packaging structure and packaging method of a high-integration micro-nano magnetic field sensor, which comprises a substrate, a first sealing plate, a second sealing plate, a magnetic field sensing element and a signal processing module. A plurality of through holes are arranged in the thickness direction of the substrate; the first sealing plate is sealingly connected to one side of the substrate, and a first packaging cavity is formed between the first sealing plate and the substrate; the second sealing plate is sealingly connected to the other side of the substrate, and a second packaging cavity is formed between the second sealing plate and the substrate; the magnetic field sensing element is located in the first packaging cavity and is fixed on the surface of one side of the substrate; the signal processing module is located in the second packaging cavity and is fixed on the surface of the other side of the substrate; the through holes are filled with conductive material, and the pins of the magnetic field sensing element and the pins of the signal processing module are respectively inserted into the through holes and are electrically connected to the conductive material. In this way, the magnetic field sensing element and the signal processing module are connected vertically in the thickness direction of the substrate to shorten the signal transmission path, which is helpful for the miniaturization and high integration of the magnetic field sensor.

Description

Technical Field

[0001] This invention relates to the field of magnetic field sensor technology, specifically providing a packaging structure and packaging method for a highly integrated micro / nano magnetic field sensor. Background Technology

[0002] MEMS (micro-nano) magnetic field sensors, due to their typical performance advantages such as extremely high sensitivity and resolution, excellent temperature stability, small size, low power consumption, and wide dynamic range, have entered the mainstream magnetic field sensor market and are widely used in various fields such as smart grids, automotive electronics, and the Internet of Things, gradually replacing the original semiconductor Hall devices. As an important basic sensing method, MEMS magnetic field sensors can provide real-time, high-precision magnetic field sensing capabilities, serving key applications such as data support and decision-making, intelligent control and optimization, automated and intelligent production, predictive maintenance, and safety monitoring. This has effectively promoted the digital transformation and development of key areas, bringing significant socio-economic benefits.

[0003] Existing MEMS magnetic field sensors suffer from low integration and limited area utilization. Traditional packaging structures restrict the integration of multiple sensor functions, failing to meet the high integration requirements of modern intelligent systems. Furthermore, planar packaging occupies a large area, hindering the development of miniaturized electronic products. Summary of the Invention

[0004] The purpose of this invention is to solve the problem of low integration density in the packaging of existing magnetic field sensors.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] This invention provides a packaging structure for a highly integrated micro / nano magnetic field sensor, comprising: a substrate having multiple through holes in its thickness direction; a first sealing plate sealed to one side of the substrate, with a first packaging cavity between the first sealing plate and the substrate; a second sealing plate sealed to the other side of the substrate, with a second packaging cavity between the second sealing plate and the substrate; a magnetic field sensing element located in the first packaging cavity and fixed to one side surface of the substrate; and a signal processing module located in the second packaging cavity and fixed to the other side surface of the substrate; the through holes are filled with conductive material, and the pins of the magnetic field sensing element and the pins of the signal processing module are respectively inserted into the through holes and fixed and electrically connected to the conductive material.

[0007] Preferably, the substrate, the first sealing plate, and the second sealing plate are all made of glass.

[0008] Preferably, the packaging structure further includes a protective layer that covers the entire package, which sequentially seals the first sealing plate, the substrate, and the second sealing plate, from the outside.

[0009] Preferably, the protective layer includes a polymer layer that completely encapsulates and covers the entire package.

[0010] Preferably, the protective layer further includes a metal layer that covers the polymer layer.

[0011] Preferably, the protective layer further includes a hydrophobic functional layer located on the surface of the metal layer.

[0012] Based on the same inventive concept, this invention also provides a packaging method for the packaging structure of the highly integrated micro / nano magnetic field sensor, characterized by comprising: substrate pretreatment: processing a glass substrate into a substrate and a sealing plate, wherein at least one of the substrate and the sealing plate has an accommodating groove etched on it; through-hole processing: forming through holes in the thickness direction of the substrate and filling the through holes with conductive material; device mounting: mounting a magnetic field sensing element and a signal processing module on both sides of the substrate, wherein the pins of the magnetic field sensing element and the pins of the signal processing module are inserted into the through holes for fixation and electrically connected to the conductive material; sealing processing: vacuum sealing the two sealing plates to both sides of the substrate so that the magnetic field sensing element and the signal processing module are respectively encapsulated in the two accommodating grooves.

[0013] Preferably, the pretreatment of the substrate includes: cutting: processing the glass substrate into a substrate and a sealing plate of a set size using a cutting process; etching: etching the receiving groove on the surface of the substrate and / or the sealing plate using an etching process; surface treatment: polishing the surface of the substrate using chemical mechanical polishing technology; and cleaning: cleaning the substrate using deionized water and isopropanol solution respectively.

[0014] Preferably, the through-hole processing includes: drilling: using a laser to create through-holes in the thickness direction of the substrate; fine processing: performing smoothing treatment, annealing treatment, and cleaning treatment on the through-holes; and metal backfilling: using an electroplating process to fill the through-holes with the conductive material.

[0015] Preferably, the device mounting includes: positioning: aligning the pins of the magnetic field sensor and the pins of the signal processing module with the through hole using a pick-and-place machine; bonding: fixing the pins of the magnetic field sensor and the pins of the signal processing module to both ends of the through hole using conductive silver paste; and electrical interconnection: electrically connecting the pins of the magnetic field sensor and the pins of the signal processing module to a conductive material using a thermoforming welding process.

[0016] Preferably, the sealing process includes: vacuum preparation: placing the sealing plate and the substrate in a sealed chamber and evacuating them; sealing welding: sealing the sealing plate and the substrate together by laser welding to form a single package; and sealing detection: detecting the airtightness of the package using a helium leak detector or a nitrogen pressurization method.

[0017] Preferably, the encapsulation method further includes sequentially coating, depositing, and hydrophobicating the outer surface of the encapsulation assembly.

[0018] Preferably, the coating process includes: applying a polymer to the outer surface of the package using a spin coating process to form a coating layer; and heating and drying the package to cure the coating layer to form a polymer layer.

[0019] Preferably, the deposition process includes: depositing a metal layer on the surface of the polymer layer using an evaporation deposition process.

[0020] Preferably, the hydrophobic treatment includes: treating the surface of the metal layer using a plasma surface treatment machine to form a hydrophobic functional layer.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] The highly integrated micro / nano magnetic field sensor packaging structure provided by this invention includes a substrate, a first sealing plate, a second sealing plate, a magnetic field sensing element, and a signal processing module. The substrate has multiple through-holes along its thickness direction. The first sealing plate is sealed to one side of the substrate, and a first packaging cavity exists between the first sealing plate and the substrate. The second sealing plate is sealed to the other side of the substrate, and a second packaging cavity exists between the second sealing plate and the substrate. The magnetic field sensing element is located in the first packaging cavity and fixed to one side surface of the substrate. The signal processing module is located in the second packaging cavity and fixed to the other side surface of the substrate. The through-holes are filled with conductive material, and the pins of the magnetic field sensing element and the pins of the signal processing module are respectively inserted into the through-holes, fixed, and electrically connected to the conductive material. This arrangement vertically connects the magnetic field sensing element and the signal processing module along the substrate thickness direction to shorten the signal transmission path, contributing to the miniaturization and high integration of the MEMS magnetic field sensor and improving overall electrical performance. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of the packaging structure of the highly integrated micro / nano magnetic field sensor in Embodiment 1 of the present invention;

[0024] Figure 2 This is a schematic diagram of the substrate in its unprocessed state in Embodiment 1 of the present invention;

[0025] Figure 3This is a schematic diagram of the structure of etching a receiving groove on the substrate in Embodiment 1 of the present invention;

[0026] Figure 4 This is a schematic diagram of a through-hole structure in Embodiment 1 of the present invention;

[0027] Figure 5 This is a schematic diagram of the structure in Embodiment 1 of the present invention, in which conductive material is filled into the through hole;

[0028] Figure 6 This is a schematic diagram of the structure of the magnetic field sensing element and the signal processing module bonded and fixed on the substrate in Embodiment 1 of the present invention;

[0029] Figure 7 This is a schematic diagram of the electrical interconnection between the magnetic field sensing element and the signal processing module on the substrate in Embodiment 1 of the present invention;

[0030] Figure 8 This is a schematic diagram of the packaging relationship between the substrate and the sealing plate in Embodiment 1 of the present invention;

[0031] Figure 9 This is a schematic diagram of the structure of the substrate and the sealing plate after vacuum sealing in Embodiment 1 of the present invention;

[0032] Figure 10 This is a schematic diagram of the packaging relationship between the substrate and the sealing plate in Embodiment 2 of the present invention;

[0033] Figure 11 This is a schematic diagram of the encapsulation relationship between the substrate and the cover plate in Embodiment 3 of the present invention.

[0034] Reference numerals: 1-substrate; 11-through hole; 2-first sealing plate; 3-second sealing plate; 4-magnetic field sensing element; 5-signal processing module; 6-accommodating groove; 7-protective layer; 71-polymer layer; 72-metal layer; 73-hydrophobic functional layer; 8-conductive material; 9-conductive silver paste. Detailed Implementation

[0035] To enable those skilled in the art to better understand the technical solutions of the present invention, the preferred embodiments of the present invention are described below in conjunction with specific applications. Obviously, the described embodiments are merely a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0036] Unless otherwise specified, the experimental, testing, processing methods or processes in the following examples are all conventional methods; the reagents and raw materials are all obtained from conventional commercial sources or prepared by conventional methods unless otherwise specified.

[0037] Example 1

[0038] like Figures 1 to 9 As shown, the packaging structure of the highly integrated micro / nano magnetic field sensor provided in this embodiment of the invention includes a substrate 1, a first sealing plate 2, a second sealing plate 3, a magnetic field sensing element 4, and a signal processing module 5. The substrate 1 has multiple through holes 11 along its thickness direction; the first sealing plate 2 is sealed to one side of the substrate 1, and a first packaging cavity exists between the first sealing plate 2 and the substrate 1; the second sealing plate 3 is sealed to the other side of the substrate 1, and a second packaging cavity exists between the second sealing plate 3 and the substrate 1; the magnetic field sensing element 4 is located in the first packaging cavity and fixed to one side surface of the substrate 1; the signal processing module 5 is located in the second packaging cavity and fixed to the other side surface of the substrate 1; the through holes 11 are filled with conductive material 8, and the pins of the magnetic field sensing element 4 and the pins of the signal processing module 5 are respectively inserted into the through holes 11 and fixed, and electrically connected to the conductive material.

[0039] Specifically, in this embodiment of the invention, the aperture of the through-holes 11 on the substrate 1 ranges from 10 μm to 100 μm, and the spacing between adjacent through-holes 11 on the substrate 1 ranges from 50 μm to 100 μm. The substrate 1, the first sealing plate 2, and the second sealing plate 3 are all made of glass, and the glass material can be any one of borosilicate glass, soda-lime glass, aluminosilicate glass, and alkali-free glass. The conductive material 8 is any one of gold, silver, and copper. Copper is preferred in this embodiment of the invention. Receiving grooves 6 are etched on both the substrate 1 and the second sealing plate 3.

[0040] It is understood that the packaging structure of the present invention adopts a stacked structure. The magnetic field sensing element 4 and the signal processing module 5 are arranged vertically and compactly on the upper and lower sides of the substrate 1 in the thickness direction of the substrate 1. This not only shortens the electrical signal transmission path, reduces signal delay and loss, and improves signal integrity, but also significantly reduces the volume and area of ​​the packaging structure, which helps to realize the integration and miniaturization of MEMS magnetic field sensors.

[0041] Table 1

[0042]

[0043]

[0044] Table 1 compares the performance of glass through-holes (THHs) and silicon through-holes (SHHs). The comparison shows that silicon, being a semiconductor material, exhibits strong electromagnetic coupling with the silicon substrate during signal transmission, leading to eddy currents and poor signal integrity. Glass THHs, on the other hand, do not require the deposition of an insulating layer, simplifying the process and reducing costs. Glass is an insulating material with a dielectric constant only about one-third that of silicon, and its loss factor is 2-3 orders of magnitude lower, significantly reducing substrate loss and parasitic effects, thus effectively improving signal integrity. Plasma or chemical treatment can form a hydrophobic surface functional layer on the glass surface, preventing moisture from affecting the performance of the MEMS magnetic field sensor. The thermal expansion coefficient of glass matches that of the magnetic field sensor 4 and the signal processing module 5, avoiding structural warping caused by thermal expansion mismatch. Glass also exhibits superior performance in terms of airtightness, Mohs hardness, impact resistance, electrical insulation, thermal conductivity, water absorption, temperature range, service life, and chemical stability.

[0045] Furthermore, the glass vias 11, due to their small aperture and spacing, can achieve higher interconnect density. The thermal expansion coefficient of glass is close to that of a circuit board (PCB), making it more suitable for maintaining reliability in stacking. The low dielectric constant of the glass vias 11 is beneficial for high-speed signal transmission, and their good electrical insulation reduces signal interference, lowering signal crosstalk during high-density interconnection. Moreover, the glass via 11 process is simpler than that of silicon vias 11, reducing the number of process steps. In this embodiment of the invention, the substrate 1, the first sealing plate 2, and the second sealing plate 3 are preferably made of alkali-free glass.

[0046] The magnetic field sensing element 4 in this embodiment of the invention is manufactured on a wafer using micromachining techniques such as etching and thin-film deposition (MEMS). The key sensing element has feature sizes on the micrometer scale and typically employs a layered structure, including multiple sensing layers and functional layers. The sensing layers are made of magnetic material thin films and are used to detect changes in the external magnetic field, providing a high-precision magnetic field sensing signal. The functional layers include a conductive layer, an insulating layer, and a shielding layer, ensuring stable signal transmission, isolating external interference, and enabling high-precision, high-stability magnetic field measurement.

[0047] The signal processing module 5 is an IC processing chip, which includes necessary signal conditioning and amplification circuits to directly process the electrical signal of the magnetic field sensing element 4.

[0048] It should be noted that a metal layer circuit can also be deposited on the surface of substrate 1 to be electrically connected to the outside world, and the metal layer circuit is electrically connected to the pins of the IC processing chip.

[0049] like Figure 1As shown, in the assembled state, in this embodiment of the invention, the first sealing plate 2 and the second sealing plate 3 are respectively sealed to the substrate 1, sealing the magnetic field sensing element 4 and the signal processing module 5 in two receiving slots 6 and forming a packaged whole. Each receiving slot 6 forms two packaged cavities within the packaged whole.

[0050] Specifically, such as Figure 8 As shown, the first sealing plate 2 covers and seals the receiving groove 6 on the substrate 1 to form a first encapsulation cavity, and the substrate 1 covers and seals the receiving groove 6 on the second sealing plate 3 to form a second encapsulation cavity. The first encapsulation cavity and the second encapsulation cavity are located on the upper and lower sides of the substrate 1, respectively.

[0051] The encapsulation cavity is either a vacuum cavity or filled with inert gas (such as argon, helium, etc.) to protect the magnetic field sensor 4 and the signal processing module 5 from external moisture, dust, chemicals, etc. The first sealing plate 2 and the second sealing plate 3 are respectively sealed to the substrate 1 by laser welding to ensure the airtightness and long-term stability of the encapsulation cavity.

[0052] like Figure 1 As shown, in this embodiment of the invention, the packaging structure further includes a protective layer 7, which covers the substrate 1 and the entire package from the outside. The protective layer 7 includes a polymer layer 71, a metal layer 72, and a hydrophobic functional layer 73. The polymer layer 71 completely encapsulates the entire package, the metal layer 72 covers the polymer layer 71, and the hydrophobic functional layer 73 is located on the surface of the metal layer 72.

[0053] By adding a polymer layer 71 as a protective layer 7, the polymer layer 71 provides elasticity and alleviates stress caused by the different coefficients of thermal expansion of different materials, while the metal layer 72 enhances the overall mechanical strength of the package. The metal layer 72 has good thermal conductivity and can also effectively dissipate the heat generated by the magnetic field sensing element 4, preventing device failure caused by high temperature. The hydrophobic functional layer 73 is used to increase hydrophobicity and anti-contamination ability.

[0054] Furthermore, the polymer layer 71 is made of polyimide, and the metal layer 72 is an aluminum film. The hydrophobic functional layer 73 is obtained by surface treatment of the metal layer 72 using a plasma surface treatment machine, with fluorine gas (or fluoride gas) selected as the plasma source. Fluorine plasma can effectively modify the surface structure of the metal layer 72.

[0055] The highly integrated micro / nano magnetic field sensor of this invention features a highly airtight packaging structure. The glass substrate 1, first sealing plate 2, second sealing plate 3, and packaging cavity effectively prevent the intrusion of external moisture, dust, and corrosive substances, ensuring the MEMS magnetic field sensor maintains stable performance and extends its service life even in humid or heavily polluted environments. Compared to traditional plastic packaging, even after prolonged operation, the signal of the MEMS magnetic field sensor will not decrease in sensitivity due to moisture or contamination, guaranteeing the measurement accuracy and long-term reliability of the MEMS magnetic field sensor. This characteristic makes this packaging structure particularly suitable for applications with high environmental adaptability requirements, such as smart grids and industrial automation.

[0056] The superior thermal stability of the glass substrate 1 ensures stable operation of the MEMS magnetic field sensor over a wide temperature range. The thermal expansion coefficient of the glass substrate 1 is close to that of the magnetic field sensing element 4, effectively preventing stress accumulation caused by thermal expansion coefficient mismatch, thereby reducing warping and deformation of the packaging structure. This packaging structure can withstand large temperature fluctuations, offering significant advantages in scenarios with frequent temperature changes.

[0057] The addition of protective layer 7 to this packaging structure improves its overall mechanical strength and impact resistance, ensuring the reliability and durability of the MEMS magnetic field sensor under harsh conditions. The glass substrate 1 has higher hardness and impact resistance compared to traditional packaging materials, enabling the MEMS magnetic field sensor to better adapt to environments with high mechanical stress, such as vibration and impact.

[0058] Example 2

[0059] like Figure 10 As shown, compared to the packaging structure in Embodiment 1, the packaging structure of the highly integrated micro / nano magnetic field sensor provided in this embodiment differs in that: in this embodiment, a receiving groove 6 is etched on both the first sealing plate 2 and the second sealing plate 3, while the receiving groove 6 is not etched on the substrate 1. Therefore, drilling can be directly performed on the substrate 1 in this embodiment, and this drilling process can be performed simultaneously with the etching of the receiving groove 6 on the first sealing plate 2 and the second sealing plate 3, shortening the overall packaging process time and improving packaging efficiency.

[0060] The other structures in this embodiment are the same as the packaging structure in Embodiment 1, so they will not be described again.

[0061] Example 3

[0062] like Figure 11As shown, compared to the packaging structure in Embodiment 1, the packaging structure of the highly integrated micro / nano magnetic field sensor provided in this embodiment differs in that: in this embodiment, the receiving grooves 6 are simultaneously etched on both sides of the substrate 1, eliminating the need for etching the first sealing plate 2 and the second sealing plate 3. Therefore, only the substrate 1 needs to be etched in a concentrated manner, saving processing costs.

[0063] The other structures in this embodiment are the same as the packaging structure in Embodiment 1, so they will not be described again.

[0064] Example 4

[0065] This invention provides a packaging method based on the packaging structure of any one of the highly integrated micro / nano magnetic field sensors in embodiments 1 to 3. The main steps of this packaging method include:

[0066] S1. Pre-treatment of the glass sheet: The glass sheet is processed into a substrate 1 and a sealing plate, and at least one of the substrate 1 and the sealing plate has an etched groove 6.

[0067] S2. Through-hole processing: Through-hole 11 is formed in the thickness direction of substrate 1 and conductive material 8 is filled into through-hole 11;

[0068] S2. Device mounting: The magnetic field sensor 4 and the signal processing module 5 are mounted on both sides of the substrate 1, and the pins of the magnetic field sensor 4 and the pins of the signal processing module 5 are inserted into the through hole 11 for fixation and electrically connected to the conductive material 8.

[0069] S4. Sealing process: Vacuum seal the two sealing plates to both sides of the substrate 1 so that the magnetic field sensing element 4 and the signal processing module 5 are respectively encapsulated in the two receiving slots 6.

[0070] S5. Protective layer treatment: The outer surface of the sealed package is sequentially coated, deposited, and treated with hydrophobicity.

[0071] The substrate pretreatment step S1 in this packaging method includes:

[0072] S11. Cutting and processing: Using laser cutting or mechanical cutting processes, the glass sheet is processed into a substrate 1 and a sealing plate of a set size;

[0073] S12, Etching process: Using wet etching or dry etching process, a receiving groove 6 is formed on the surface of substrate 1 and / or cover plate.

[0074] S13. Surface treatment: Polish the surface of substrate 1 using chemical mechanical polishing technology;

[0075] S14. Cleaning treatment: Clean the substrate 1 with deionized water and isopropanol solution respectively.

[0076] Specifically, in step S11, the glass sheet is processed and cut into a substrate 1 with a size of 2cm × 2cm using laser cutting. The cutting dimensional accuracy should be controlled within ±10μm. The sealing plate needs to be precisely cut to the same size as the substrate 1, and the edge gap should be controlled below 5μm to prevent leakage during subsequent encapsulation between the sealing plate and the substrate 1. During the processing of the substrate 1 and the sealing plate, the cutting temperature variation should be controlled within ±5℃ to avoid sudden temperature changes and prevent thermal stress from causing the glass sheet to crack. It should be noted that the processing and cutting dimensions can be flexibly selected according to the actual application.

[0077] It should be noted that the sealing plate and the substrate 1 are made of the same glass material. The thickness of the substrate 1 is 1.5mm-3mm, and the thickness of the sealing plate is about 0.5mm-1.5mm, to ensure that the airtightness and mechanical strength are matched.

[0078] like Figure 2 and Figure 3 As shown, in step S12, a wet etching process is used to etch receiving grooves 6 on the surfaces of the glass substrate 1 and the sealing plate. The depth and dimensions of each receiving groove 6 are determined according to the specific dimensions of the magnetic field sensor 4 or the signal processing module 5. The dimensions of each receiving groove 6 are typically 5% larger than the area of ​​the magnetic field sensor 4 or the signal processing module 5 to ensure a complete seal. It should be noted that wet etching is usually used when a larger area of ​​groove is required, while dry etching is suitable for etching fine structures.

[0079] The sealing plate includes a first sealing plate 2 and a second sealing plate 3, based on the packaging structure of embodiment 1, such as... Figure 8 As shown, receiving grooves 6 are etched on both the substrate 1 and the second sealing plate 3. Based on the packaging structure of embodiment 2, as... Figure 10 As shown, in embodiment 2, both the first sealing plate 2 and the second sealing plate 3 have etched receiving grooves 6, while the substrate 1 does not need to have the receiving grooves 6 etched. Based on the packaging structure of embodiment 3, as... Figure 11 As shown, in embodiment 3, the substrate 1 on both sides needs to be etched with receiving grooves 6, while the first sealing plate 2 and the second sealing plate 3 do not need to be etched with receiving grooves 6.

[0080] In step S13, both the substrate 1 and the cover plate are polished using chemical mechanical polishing technology. To ensure the effect of subsequent processes, the surface roughness of the polished surface should be less than 1 nm.

[0081] In step S14, substrate 1 is cleaned with deionized water and isopropanol solution for 30 minutes each, followed by vacuum drying to ensure the surface of substrate 1 is clean and dust-free. Deionized water is used to remove inorganic salts and particulate contaminants from the glass substrate 1, while isopropanol is used to remove grease and organic impurities. The cleaning steps for the sealing plate are the same as those for substrate 1, and therefore will not be described in detail here.

[0082] Understandably, after completing the above processing steps, the glass sheet is processed into substrate 1 and sealing plate, and the surfaces of substrate 1 and sealing plate are kept clean and dust-free for subsequent use.

[0083] The through-hole processing step S2 in this encapsulation method includes:

[0084] S21. Through-hole processing: A through-hole 11 is formed on the thickness of substrate 1 using a laser;

[0085] S22. Fine processing: Smoothing, annealing and cleaning of through hole 11;

[0086] S23. Metal backfilling: The conductive material 8 is filled into the through hole 11 using an electroplating process.

[0087] Specifically, such as Figure 4 and Figure 5 As shown, in step S21, a high-power laser is used to process multiple through holes 11 on the glass substrate 1. The diameter of the through holes 11 is between 10 μm and 100 μm, and the spacing between two adjacent through holes 11 is between 50 μm and 100 μm to achieve high-density interconnection. During laser drilling, the smoothness and consistency of the edges of the through holes 11 should be ensured to facilitate the uniform filling of the conductive material 8.

[0088] Understandably, after the laser beam drilling process is completed, the inner wall of the through hole 11 is relatively rough and requires further processing.

[0089] In step S22, chemical etching is used to smooth the inner wall of the through hole 11, providing an ideal surface for the subsequent electroplating process of the conductive material 8. The thermal stress generated during laser drilling may cause microcracks in the glass substrate 1. Annealing effectively eliminates glass microcracks and potential stress, ensuring the structural integrity and impact resistance of the substrate 1. The annealing temperature is controlled at 400℃–500℃, and the annealing time is 1 hour–2 hours. After the stress relief treatment by annealing, the through hole 11 is cleaned by rinsing with deionized water to remove any microparticles and impurities that may remain in the through hole 11.

[0090] Understandably, completing the above-mentioned fine processing steps can improve the smoothness and cleanliness of the inner wall of the through hole 11, preparing it for metal backfilling.

[0091] like Figure 6 As shown, in step S23, an electroplating process is used to fill the glass through-hole 11 with conductive material 8 to form an electrical interconnect. The conductive material 8 is made of copper, and multiple electroplating layers are applied to the through-hole 11 until it is completely filled, avoiding gaps or defects in the electroplating layers. The total radial thickness of the filling electroplating layer is at least 90% of the hole diameter to ensure the integrity of the conductive path and the stability of signal transmission within the through-hole 11.

[0092] In addition, after the metal backfilling step is completed, the two sides of the substrate 1 are planarized to remove excess conductive material 8 from the surface of the substrate 1, so that the surface flatness of the substrate 1 is within ±5μm, ensuring a tight fit between the device in the subsequent packaging structure and the substrate 1.

[0093] It is understandable that after the above metal backfilling process is completed, a conductive path with vertical thickness is formed in the substrate 1.

[0094] In this packaging method, step S3, device mounting includes:

[0095] S31, Positioning process: Use a pick-and-place machine to align the pins of the magnetic field sensor 4 and the pins of the signal processing module 5 with the through hole 11 respectively;

[0096] S32, Bonding and fixing: Using conductive silver paste 9, fix the pins of the magnetic field sensing element 4 and the pins of the signal processing module 5 to both ends of the through hole.

[0097] S33, Electrical interconnection: The pins of the magnetic field induction element 4 and the pins of the signal processing module 5 are electrically connected to the conductive material 8 using a hot-press welding process.

[0098] In step S31, the pins of the magnetic field sensor 4 are aligned with the through hole 11 using a precision pick-and-place machine under vacuum adsorption. The alignment error must be controlled within ±1μm. The magnetic field sensor 4 is aligned with the receiving groove 6 on the substrate 1.

[0099] like Figure 6 As shown, in step S32, a bonding machine is used to insert the pins of the magnetic field induction element 4 into the channel for bonding connection. The bonding machine uses conductive silver paste 9, with a curing temperature controlled at 120℃–150℃ and a curing time of 30–60 minutes. The temperature rise rate of the conductive silver paste 9 needs to be controlled at 1℃ / min–2℃ / min to avoid stress damage to the magnetic field induction element 4 on the substrate 1 due to sudden heating, ensuring the conductivity and firmness of the magnetic field induction element 4. Silver has an electrical conductivity of 6.3×10⁷ S / m and a thermal conductivity of 429 W / m·K, suitable for high-precision signal transmission applications. Its coefficient of thermal expansion is 7–10 / ℃, similar to that of glass, which improves the adaptability of the conductive material 8 and the glass substrate 1 under high and low temperature environments. After the conductive silver paste 9 is bonded and cured, it provides electrical connection while simultaneously achieving mechanical fixation of the magnetic field induction element 4 on the substrate 1.

[0100] like Figure 7As shown, in step S33, a hot-press welding machine is used to electrically connect the pins of the magnetic field induction element 4 to the conductive material 8. The welding temperature is controlled between 170℃ and 190℃, preferably 180℃. This ensures tight contact between the conductive material 8 and the device pins, reducing connection impedance, and also seals the device pins in the through-hole 11 with conductive silver paste 9. Because the glass through-hole 11 has a low dielectric constant, crosstalk in signal transmission is low, which helps improve the system's anti-interference capability.

[0101] It should be noted that the installation steps of the signal processing module 5 are exactly the same as those of the magnetic field sensing element 4, so the installation of the signal processing module 5 will not be described again.

[0102] It is understandable that after the above processing steps are completed, the magnetic field sensor 4 and the signal processing module 5 are interconnected at close range.

[0103] The sealing process in step S4 of this encapsulation method includes:

[0104] S41. Vacuum preparation: Place the sealing plate and substrate 1 in a sealed chamber and perform vacuum treatment;

[0105] S42, Sealing Welding: The sealing plate and the substrate 1 are sealed together by laser welding to form a complete package;

[0106] S43. Sealing test: Use a helium leak detector or nitrogen pressurization method to test the overall airtightness of the package.

[0107] In step S41, the first sealing plate 2, the second sealing plate 32 and the substrate 1 are placed in a vacuum chamber, and the vacuum chamber is evacuated to reduce the air pressure in the sealed chamber to below 0.1 Pa, and the vacuum state is maintained for at least 10 minutes.

[0108] In step S42, under vacuum, the first sealing plate 2 covers the receiving groove 6 of the substrate 1 and then uses a high-power laser welding machine to perform sealing welding to form a first packaging cavity. The substrate 1 and the receiving groove 6 of the second sealing plate 3 are covered and then used a high-power laser welding machine to perform sealing welding to form a second packaging cavity. That is, the first sealing plate 2, the second sealing plate 3 and the substrate 1 are sealed and welded to form a package whole.

[0109] To control the sealing condition, the laser power of the laser welding machine is set at around 9W-11W, and the welding speed is controlled at 1mm / s-3mm / s to prevent the glass surface from overheating and causing cracks or bubbles.

[0110] After sealing in step S43, the entire package is left to stand for 24 hours. The airtightness of the package cavity is then tested using a helium leak detector or a nitrogen pressurization method to ensure that there is no gas leakage in either the first or second package cavity and that it can maintain a vacuum state for a long time.

[0111] The coating process in step S5 of this encapsulation method includes:

[0112] S51. A coating layer is formed by applying a polymer to the outer surface of the entire package using a spin coating process.

[0113] S52. Heat and dry the entire package to cure the coating layer and form a polymer layer 71.

[0114] Specifically, such as Figure 1 As shown, in step S51, a spin coater is used to uniformly coat the polymer onto the outer surface of the encapsulation assembly. The spin coater's spin speed is between 2000 rpm and 3000 rpm, and the coating thickness is between 10 μm and 20 μm. The spin coating thickness can also be flexibly selected according to specific application requirements.

[0115] In step S52, the entire package is placed in an oven to cure the coating layer and form polymer layer 71. The oven temperature is 50℃-80℃, and the drying time is 10min-30min.

[0116] The deposition process in step S5 of this encapsulation method includes:

[0117] S53. A metal layer 72 is deposited on the surface of the polymer layer 71 using an evaporation coating process.

[0118] Aluminum is deposited onto the surface of polymer layer 71 using an evaporation deposition machine to form an aluminum thin film. The deposition rate is controlled at 0.1 μm / min-0.3 μm / min to ensure uniformity, and the deposition thickness is 0.5 μm-2 μm. In addition, the deposition thickness can be flexibly selected according to specific application requirements.

[0119] The hydrophobic treatment in step S5 of this encapsulation method includes:

[0120] S54. The surface of the metal layer 72 is treated using a plasma surface treatment machine to form a hydrophobic functional layer 73.

[0121] After the aluminum thin film metal layer 72 is deposited in step S53, fluorine gas (or fluoride gas) is selected as the plasma source in step S54, and a plasma surface treatment machine is used to treat the surface of the protective layer 7. The fluorine plasma can effectively modify the surface structure of the metal layer 72 and increase its hydrophobicity. The treatment time is usually set to 2-5 minutes. When coating the metal layer 72 with other materials, the specific treatment time is adjusted according to the material properties and hydrophobic requirements.

[0122] Understandably, after completing the above processing steps, the thickness of the protective layer 7 should be checked using a microscope or a non-contact optical thickness gauge to ensure uniform thickness across all areas. The adhesion of the protective layer 7 should be tested using a scratch test or a tensile test to ensure it does not detach under temperature and vibration changes, and the adhesion strength should reach at least 500 mN. The surface hydrophobicity should be tested using a water droplet contact angle meter, and the contact angle of the treated surface should reach at least 100°.

[0123] The embodiments of the present invention reduce the difference in thermal expansion coefficients between the substrate 1 and the magnetic field sensing device by designing a unique processing technology, effectively reducing warpage or stress caused by temperature changes during the packaging process.

[0124] Furthermore, the advantages of the packaging structure prepared by the above packaging method are summarized as follows:

[0125] High airtightness: The encapsulation cavity adopts a vacuum sealing process to ensure that the inside of the cavity is isolated from the external environment, effectively resisting the contamination of moisture, dust and chemicals, and improving the long-term stability and reliability of the sensor.

[0126] High stability: The glass substrate 1 has excellent thermal stability and shock resistance, which reduces stress accumulation under different temperature environments, avoids deformation of the packaging structure, and ensures the measurement accuracy and service life of the sensor.

[0127] High-density electrical interconnection and anti-interference capability: The low dielectric constant of the glass via 11 facilitates high-speed signal transmission, reduces signal crosstalk and electromagnetic interference, improves signal transmission integrity and anti-interference capability, and is suitable for complex electromagnetic environments.

[0128] Excellent mechanical strength and heat dissipation performance: The polymer layer 71 significantly enhances the mechanical strength and impact resistance of the package, while the excellent thermal conductivity of the metal layer 72 effectively dissipates heat and prevents the sensor from overheating under high load conditions.

[0129] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of the claims of the present invention pending approval.

Claims

1. A packaging structure of a high-integration micro-nano magnetic field sensor, characterized in that, include: The substrate (1) has a plurality of through holes (11) in the thickness direction; A first sealing plate (2) is sealed to one side of the substrate (1), and a first encapsulation cavity is provided between the first sealing plate (2) and the substrate (1); A second sealing plate (3) is sealed to the other side of the substrate (1), and a second encapsulation cavity is provided between the second sealing plate (3) and the substrate (1). A magnetic field sensing element (4) is located in the first encapsulation cavity and fixed on one side surface of the substrate (1); as well as The signal processing module (5) is located in the second encapsulation cavity and fixed on the other side surface of the substrate (1); The through hole (11) is filled with conductive material. The pins of the magnetic field sensing element (4) and the pins of the signal processing module (5) are respectively inserted into the through hole (11) for fixation and are electrically connected to the conductive material.

2. The packaging structure of a high-integration micro-nano magnetic field sensor according to claim 1, characterized in that, The substrate (1), the first sealing plate (2) and the second sealing plate (3) are all made of glass.

3. The packaging structure of the highly integrated micro / nano magnetic field sensor as described in claim 1, characterized in that, The packaging structure also includes a protective layer (7), which covers the entire package from the outside by sealing the first sealing plate (2), the substrate (1) and the second sealing plate (3) in sequence.

4. The packaging structure of the highly integrated micro / nano magnetic field sensor as described in claim 3, characterized in that, The protective layer (7) includes a polymer layer (71) that covers the entire package.

5. The packaging structure of the highly integrated micro / nano magnetic field sensor as described in claim 4, characterized in that, The protective layer (7) also includes a metal layer that covers the polymer layer (71).

6. The packaging structure of the highly integrated micro / nano magnetic field sensor as described in claim 5, characterized in that, The protective layer (7) further includes a hydrophobic functional layer (73) located on the surface of the metal layer.

7. A packaging method for a packaging structure of a highly integrated micro / nano magnetic field sensor as described in any one of claims 1-6, characterized in that, include: Pre-treatment of the glass sheet: The glass sheet is processed into a substrate (1) and a sealing plate, wherein at least one of the substrate (1) and the sealing plate has an etched receiving groove (6); Through-hole processing: A through-hole (11) is formed in the thickness direction of the substrate (1) and a conductive material is filled into the through-hole (11); Device mounting: The magnetic field sensing element (4) and the signal processing module (5) are respectively mounted on the two sides of the substrate (1), and the pins of the magnetic field sensing element (4) and the pins of the signal processing module (5) are inserted into the through hole (11) for fixation and are electrically connected to the conductive material. Sealing process: The two sealing plates are vacuum sealed to both sides of the substrate (1) so that the magnetic field sensing element (4) and the signal processing module (5) are respectively encapsulated in the two receiving slots (6).

8. The packaging method for the packaging structure of the highly integrated micro / nano magnetic field sensor as described in claim 7, characterized in that, The pretreatment of the sheet material includes: Cutting process: The glass sheet is processed into the substrate (1) and the sealing plate of a set size using a cutting process; Etching process: The receiving groove (6) is formed by etching on the surface of the substrate (1) and / or the cover plate using an etching process; Surface treatment: The surface of the substrate (1) is polished using chemical mechanical polishing technology; Cleaning process: The substrate (1) is cleaned with deionized water and isopropanol solution respectively.

9. The packaging method for the packaging structure of the highly integrated micro / nano magnetic field sensor as described in claim 8, characterized in that, The through-hole processing includes: Drilling: A through hole (11) is made in the thickness direction of the substrate (1) using a laser; Fine processing: The through hole (11) is subjected to smoothing treatment, annealing treatment and cleaning treatment; Metal backfilling: The conductive material is filled into the through hole (11) using an electroplating process.

10. The packaging method for the packaging structure of the highly integrated micro / nano magnetic field sensor as described in claim 9, characterized in that, The device mounting includes: Positioning process: Using a chip mounter, align the pins of the magnetic field sensor (4) and the pins of the signal processing module (5) with the through hole (11); Bonding and fixing: The pins of the magnetic field sensing element (4) and the pins of the signal processing module (5) are fixed at both ends of the channel of the through hole (11) using conductive silver paste. Electrical interconnection: The pins of the magnetic field sensing element (4) and the pins of the signal processing module (5) are electrically connected to the conductive material using a hot-press welding process.

11. The packaging method for the packaging structure of the highly integrated micro / nano magnetic field sensor as described in claim 10, characterized in that, The sealing process includes: Vacuum preparation: Place the sealing plate and the substrate (1) in a sealed chamber and perform vacuum treatment; Sealing welding: The sealing plate and the substrate (1) are sealed together by laser welding to form a single package; Sealing test: The airtightness of the entire package is tested using a helium leak detector or a nitrogen pressurization method.

12. The packaging method for the packaging structure of the highly integrated micro / nano magnetic field sensor as described in claim 11, characterized in that, The encapsulation method further includes sequentially coating, depositing, and hydrophobicating the outer surface of the encapsulated assembly after sealing.

13. The packaging method for the packaging structure of the highly integrated micro / nano magnetic field sensor as described in claim 12, characterized in that, The coating process includes: A coating layer is formed by applying a polymer to the outer surface of the entire package using a spin coating process. The entire package is heated and dried to cure the coating layer and form a polymer layer (71).

14. The packaging method for the packaging structure of the highly integrated micro / nano magnetic field sensor as described in claim 13, characterized in that, The deposition process includes: A metal layer (72) is deposited on the surface of the polymer layer (71) using an evaporation deposition process.

15. The packaging method for the packaging structure of the highly integrated micro / nano magnetic field sensor as described in claim 14, characterized in that, The hydrophobic treatment includes: The surface of the metal layer (72) is treated using a plasma surface treatment machine to form a hydrophobic functional layer (73).

Images