A method for interconnecting a hemispherical anchor column and an electrode, and a hemispherical resonant gyroscope

Abstract

The present invention discloses a method for interconnecting a hemispherical anchor post with an electrode and a hemispherical resonator gyroscope. The method comprises the following steps: 1) copper coating the surface of the anchor post of a hemispherical resonator and the wall of the central hole of the electrode; 2) applying a nano-copper paste to the copper-coated surface of the anchor post of the hemispherical resonator and / or the wall of the central hole of the electrode; and 3) inserting the anchor post of the hemispherical resonator into the central hole of the electrode so that the surface of the anchor post of the hemispherical resonator and the wall of the central hole of the electrode contact each other through the copper paste. A low-temperature pressureless bonding process is then used to achieve conductive interconnection between the anchor post of the hemispherical resonator and the wall of the central hole of the electrode. The present invention can achieve a conductive interconnection between the hemispherical anchor post and the electrode with high mechanical strength and low contact resistance.

Description

Technical Field

[0001] The present invention relates to the field of inertial navigation technology, and in particular to a method for interconnecting a hemispherical anchor column and an electrode, and a hemispherical resonant gyroscope. Background Art

[0002] With the rapid development of microelectronics and inertial navigation systems, MEMS components have been widely used in aerospace, military, and precision instrumentation. As the core of high-precision inertial navigation systems, the hemispherical resonant gyroscope (HRG) relies on an efficient and stable connection between the hemispherical oscillator and the anchor electrode.

[0003] Currently, commonly used connection technologies for hemispherical resonator anchors and electrodes include eutectic bonding with gold-indium and adhesive bonding. However, these methods have certain limitations in terms of bonding conditions, long-term use, and high reliability requirements. For example, gold-indium eutectic bonding requires very small clearances between mating holes, complex solder pad sizes, and pre-treatment processes. Other eutectic bonding methods, such as copper-tin bonding, may damage heat-sensitive materials during high-temperature processing. Traditional adhesives have problems such as poor conductivity or the formation of holes during the curing process, making it difficult to meet the requirements of high-performance electrical connections and structural strength. Furthermore, subsequent use can easily generate volatile substances such as water vapor and impurities, which can cause the vacuum state of the hemispherical resonator gyroscope to deteriorate, affecting the gyroscope's long-term service life. In contrast, nano-copper, due to its surface effect and small size effect, can be sintered at low temperatures when used to bond between the hemispherical resonator anchor and electrode, effectively avoiding high-temperature damage to the microstructure and reducing production costs. At the same time, due to the small size effect, bonding does not produce defects such as pores that affect the structural strength of the connector. In addition, compared to gold-indium bonding, it has lower requirements for the matching relationship of the connector and avoids the high cost of gold plating on the counterpart. However, nano-copper bonding inevitably requires the use of dispersants and viscosity modifiers. Hemispherical gyroscopes must be used under high vacuum conditions. Improper selection of dispersants and viscosity modifiers will cause evaporation, contaminating the clean and high-vacuum environment, seriously affecting the accuracy of the hemispherical gyroscope. Moreover, hemispherical gyroscopes are used under high-frequency vibration, which requires high interface bonding strength and uniformity. Improper selection of dispersants and viscosity modifiers can also lead to poor interface bonding strength and uniformity of nano-copper low-temperature bonding, thus affecting its long-term service life. Summary of the Invention

[0004] In response to the problems in the background technology, the present invention proposes a conductive interconnection method for achieving high mechanical strength and low contact resistance between a hemispherical anchor post and an electrode. In addition, a hemispherical resonant gyroscope manufactured by the above interconnection method is also provided.

[0005] The present invention adopts the following technical solutions:

[0006] A method for interconnecting a hemispherical anchor post and an electrode, comprising the following steps:

[0007] 1) Copper film is plated on the anchor column surface of the hemispherical resonator and the wall of the central hole of the electrode;

[0008] 2) Coating the nano-copper paste on the anchor column surface and / or the center hole wall of the electrode of the hemispherical resonator after the copper film is plated;

[0009] 3) Insert the anchor post of the hemispherical resonator into the center hole of the electrode so that the cylindrical surface of the anchor post of the hemispherical resonator and the wall of the center hole of the electrode are in contact through the copper paste between the two. Use a low-temperature pressureless bonding process to achieve conductive interconnection between the anchor post of the hemispherical resonator and the wall of the center hole of the electrode.

[0010] Optionally, based on 100% of the total weight of the nano-copper paste, the nano-copper paste includes 68 wt %-72 wt % of nano-copper particles, 18 wt %-22 wt % of a dispersant, and 8 wt %-12 wt % of a viscosity regulator.

[0011] Optionally, the dispersant is triethanolamine.

[0012] Optionally, the viscosity modifier is γ-glycidyloxypropyltrimethoxysilane.

[0013] Optionally, the conditions of the low-temperature pressureless bonding process are: keeping warm for 1.5-2.5 hours at a vacuum degree of less than 1 Pa and 220-270° C.

[0014] Optionally, the diameter of the nano copper particles is 50 nm-500 nm.

[0015] Optionally, the nano copper paste includes 70 wt % of nano copper particles, 20 wt % of a dispersant and 10 wt % of a viscosity regulator.

[0016] Optionally, the preparation process of the nano copper paste is as follows:

[0017] Nano copper particles, a dispersant and a viscosity regulator are mixed in proportion, and dispersed by high-temperature ultrasound to obtain a nano copper slurry.

[0018] Optionally, the temperature of the high-temperature ultrasonic dispersion is 70-80° C., and the time is 100-150 min.

[0019] Optionally, the copper film has a thickness of 1-2 μm.

[0020] Optionally, a copper film is plated on the anchor column surface of the hemispherical resonator and the wall of the central hole of the electrode by magnetron sputtering process. The process conditions of magnetron sputtering are: magnetron sputtering power is 100-200W, argon flow rate is 25-35sccm, time is 30-60min, and vacuum degree is less than 1Pa.

[0021] Optionally, before step 1), the following steps may also be included:

[0022] The anchor column surface of the hemispherical resonator and the center hole wall of the electrode are ion cleaned. The process conditions of ion cleaning are: current 20-40mA, argon flow rate 15-25sccm, vacuum degree less than 1Pa, and cleaning time 10-30min.

[0023] Optionally, after step 3), the following steps are further included:

[0024] The interconnected hemispherical resonator and the electrode are chemically cleaned to remove excess dispersant and viscosity modifier between the hemispherical resonator and the electrode.

[0025] Optionally, the interconnected hemispherical resonators and electrodes are cleaned by bubbling with ethanol, acetone and ethanol solution in sequence, each cleaning lasting 3-6 minutes, followed by nitrogen purging and drying.

[0026] As a general inventive concept, the present invention also provides a hemispherical resonant gyroscope obtained by the above-mentioned method of interconnecting hemispherical anchors and electrodes.

[0027] Compared with the prior art, the advantages of the present invention are:

[0028] The method of interconnecting a hemispherical anchor post and an electrode of the present invention can achieve efficient and reliable bonding connection between a hemispherical resonator and an anchor post electrode at low temperature and without pressure. Specifically, a copper film is first plated on the hemispherical anchor post and the hole wall of the electrode post to provide an excellent interface suitable for pressureless bonding. Then, a suitable dispersant and viscosity modifier are used and the copper slurry ratio is optimized. After bonding, a vacuum insulation volatilization and cleaning process is superimposed. As a result, the hemispherical resonator gyroscope bonded with nano-copper of the present invention exhibits excellent mechanical strength and electrical conductivity under harsh working conditions such as vacuum, low temperature, and high-frequency vibration. Under long-term use conditions, no volatile substances that pollute the vacuum are generated, meeting the high-standard assembly, electrical connection, and long-term reliability requirements of the hemispherical resonator gyroscope. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to make the present invention more easily understood, the present invention will be described in more detail with reference to the specific embodiments shown in the accompanying drawings. These drawings only depict typical embodiments of the present invention and should not be considered as limiting the scope of protection of the present invention.

[0030] Figure 1 This is a flow chart of the method for interconnecting the hemispherical anchor post and the electrode according to the present invention.

[0031] Figure 2 This is a physical picture of the hemispherical anchor column after copper film plating according to an embodiment of the present invention.

[0032] Figure 3This is a scanning electron microscope image of the hemispherical anchor column after copper film plating according to an embodiment of the present invention.

[0033] Figure 4 This is an atomic force microscope image of the hemispherical anchor column after copper film plating according to an embodiment of the present invention.

[0034] Figure 5 Schematic diagram of low-temperature bonding of a hemispherical resonator and an electrode system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0035] The following describes the embodiments of the present invention with reference to the accompanying drawings so that those skilled in the art can better understand the present invention and implement it. However, the enumerated embodiments are not intended to limit the present invention. Unless there is a conflict, the following embodiments and the technical features in the embodiments can be combined with each other, wherein the same components are represented by the same figure marks.

[0036] like Figure 1 As shown, the present invention provides a method for interconnecting a hemispherical anchor post and an electrode, comprising the following steps:

[0037] 1) Copper film is plated on the anchor column surface of the hemispherical resonator and the wall of the central hole of the electrode;

[0038] 2) Coating the nano-copper paste on the anchor column surface and / or the center hole wall of the electrode of the hemispherical resonator after the copper film is plated;

[0039] 3) Insert the anchor post of the hemispherical resonator into the central hole of the electrode so that the cylindrical surface of the anchor post of the hemispherical resonator and the wall of the central hole of the electrode are in contact with each other through the copper paste between the two. A low-temperature pressureless bonding process is used to achieve conductive interconnection between the anchor post of the hemispherical resonator and the wall of the central hole of the electrode.

[0040] Therefore, the present invention can achieve efficient and reliable bonding connection between the hemispherical resonator and the anchor electrode at low temperature and without pressure. Specifically, a copper film is first plated on the hemispherical anchor and the electrode hole wall to provide an excellent interface suitable for pressureless bonding, and then a suitable dispersant and viscosity modifier are used and the copper slurry ratio is optimized. After bonding, a vacuum insulation volatilization and cleaning process is superimposed. This allows the hemispherical resonator gyroscope bonded with nano-copper of the present invention to exhibit excellent mechanical strength and conductive properties under harsh working conditions such as vacuum, low temperature and high-frequency vibration. Under long-term use conditions, no volatile substances that pollute the vacuum are generated, meeting the high-standard assembly, electrical connection requirements and long-term reliability requirements of the hemispherical resonator gyroscope.

[0041] In this embodiment, based on the total weight of the nano-copper paste being 100%, the nano-copper paste includes 68 wt %-72 wt % of nano-copper particles, 18 wt %-22 wt % of a dispersant, and 8 wt %-12 wt % of a viscosity regulator.

[0042] In this embodiment, the nano-copper paste preferably includes 70 wt % of nano-copper particles, 20 wt % of a dispersant, and 10 wt % of a viscosity modifier.

[0043] In this embodiment, the dispersant is triethanolamine, and the viscosity modifier is γ-glycidoxypropyltrimethoxysilane.

[0044] In this embodiment, the low-temperature pressureless bonding process conditions are: a vacuum degree of less than 1 Pa and a temperature of 220-270° C. for 1.5-2.5 hours.

[0045] In this embodiment, the diameter of the nano copper particles is 50 nm-500 nm.

[0046] The innovative features of the present invention include:

[0047] 1. Developed a nano copper paste formulation suitable for long-term vacuum environments:

[0048] In the nano-copper paste, different ratios of triethanolamine and γ-glycidyloxypropyltrimethoxysilane are optimized, each playing a key role to meet the long-term vacuum environment requirements of the hemispherical gyroscope. To reduce the nano-copper bonding temperature and prevent agglomeration, 68wt%-72wt% of the nano-copper paste is nano-copper, which forms a dense bonding interface and ensures mechanical strength and conductivity. 18wt%-22wt% of triethanolamine is used as a dispersant to ensure uniform distribution of the paste during deposition and sintering, and promotes atomic diffusion bonding between the copper particles at the neck under pressure-free conditions. 8wt%-12wt% of γ-glycidyloxypropyltrimethoxysilane is further added as a crosslinker to promote densification and interconnectivity of the copper particles during sintering. Heat treatment time and vacuum atmosphere are controlled to remove excess organic matter, ensuring long-term performance in a vacuum environment. By balancing the contradictions between dispersibility, bonding strength, and conductivity, a highly reliable copper-copper bonding interface suitable for vacuum conditions is achieved.

[0049] Specifically, 18-22 wt% of triethanolamine is used as a dispersant. Triethanolamine has excellent coordination properties and can adsorb onto the surface of copper nanoparticles, forming a protective layer that inhibits interparticle aggregation and agglomeration, maintaining dispersion. Triethanolamine also helps improve the coating properties of the copper slurry by regulating viscosity, ensuring uniform distribution of the slurry during deposition and sintering, thereby ensuring uniform interface bonding between the hemispherical anchor and the wall of the electrode's central hole.

[0050] Using 8-12 wt% of γ-glycidyloxypropyltrimethoxysilane as a crosslinker forms covalent or hydrogen bonds with the copper particle surface. It also reacts with functional groups in the organic matrix, forming an organic-inorganic composite interface and significantly enhancing the adhesion between the particles and the matrix. This improved contact and interaction between the particles also promotes the densification and interconnectivity of the copper particles during sintering, thereby optimizing the mechanical strength of the interface between the hemispherical anchor and the electrode's central pore wall.

[0051] In addition, the boiling points of triethanolamine and γ-glycidyloxypropyltrimethoxysilane decrease in the later stage of vacuum nano-copper bonding, thereby gradually volatilizing. In the present invention, in order to ensure that all excess organic matter is volatilized, the holding time is extended under vacuum conditions and bonding temperature to ensure that they are completely volatilized. After the bonding is completed, the hemispherical gyroscope is then encapsulated in a vacuum cavity. Therefore, the bonding process of the present invention does not affect the high vacuum degree of the use environment of the hemispherical gyroscope.

[0052] 2. Pressure-free bonding process between hemispherical resonator and planar electrode:

[0053] To avoid material damage during bonding, the present invention develops a pressureless thermal bonding process, specifically designed to minimize damage to the assembly, given that both the hemispherical resonator and the electrode base are made of quartz. Unlike traditional bonding methods, this technique first deposits a 1-2 µm thick metal film on the hemispherical resonator anchor and the planar electrode limiter using a magnetron sputtering copper plating process. The resulting metal film exhibits excellent surface uniformity (roughness <25 nm) and low interfacial defect density, providing an excellent interface for pressureless bonding at low temperatures of 200-300°C. Furthermore, triethanolamine, a dispersant, not only maintains the uniformity of the nano-copper paste but also promotes interparticle neck formation and atomic diffusion at relatively low temperatures, thereby ensuring that the bonding interface maintains strength even under pressureless conditions.

[0054] Furthermore, particle size plays a critical role in the sintering process of nano-copper pastes. Due to the high specific surface area and surface energy of nano-copper with an appropriate particle size (preferably 100 nm), sintering can be achieved at relatively low temperatures (200–300°C), forming a dense conductive network and thus improving conductivity. However, too small a particle size can easily lead to copper particle agglomeration and oxidation, compromising conductivity. Furthermore, the addition of a dispersant can effectively improve the dispersion of nano-copper particles, prevent agglomeration, and ensure slurry uniformity. However, an excessive amount of dispersant may form residues during sintering, hindering contact between copper particles and reducing conductivity. Furthermore, an appropriate amount of cross-linking agent helps form a dense structure and effectively reduces unreacted copper powder contamination. However, the addition of organic components may lead to the formation of an insulating layer, hindering electron transport. Appropriate sintering conditions also facilitate the removal of organic contaminants and the sintering of copper particles, forming a continuous conductive path. In summary, by rationally designing the nano-copper particle size, optimizing the dispersant and cross-linking agent, and their sintering parameters, a high-density and continuous conductive network can be achieved at a relatively low temperature, thereby balancing conductivity after bonding.

[0055] Specifically, the preparation process of nano copper paste is as follows:

[0056] Nano copper particles, a dispersant and a viscosity regulator are mixed in proportion, and dispersed by high-temperature ultrasound to obtain a nano copper slurry.

[0057] In this embodiment, the temperature of high-temperature ultrasonic dispersion is 70-80° C., and the time is 100-150 minutes.

[0058] In this embodiment, a copper film is deposited on the surface of the anchor post of the hemispherical resonator and the wall of the central hole of the electrode using a magnetron sputtering process. The magnetron sputtering conditions are: a magnetron sputtering power of 100-200 W, an argon flow rate of 25-35 sccm, a time of 30-60 minutes, and a vacuum level of less than 1 Pa. The copper film formed by this process has a thickness of 1-2 μm.

[0059] In this embodiment, before step 1), the following steps are further included:

[0060] The anchor column surface of the hemispherical resonator and the center hole wall of the electrode are ion cleaned. The process conditions of ion cleaning are: current 20-40mA, argon flow rate 15-25sccm, vacuum degree less than 1Pa, and cleaning time 10-30min.

[0061] In this embodiment, after step 3), the following steps are further included:

[0062] The interconnected hemispherical resonator and the electrode are chemically cleaned to remove excess dispersant and viscosity modifier between the hemispherical resonator and the electrode.

[0063] Specifically, the interconnected hemispherical resonators and electrodes were cleaned by bubbling with ethanol, acetone and ethanol solution in sequence, each cleaning lasting 3-6 minutes, and then purged with nitrogen and dried.

[0064] Example 1

[0065] Step 1: Preparation of nano copper paste

[0066] Considering that hemispherical resonators must operate in a vacuum environment in practical applications, the present invention specifically optimizes the nano-copper paste formula, adding dispersants and crosslinkers to form a stable interface bond. This helps improve the copper paste's coating properties and ensures uniform distribution of the paste during deposition and sintering. Furthermore, the selected dispersant and excess viscosity modifier are fully evaporated under low-temperature vacuum conditions, thus ensuring the long-term usability of the bond between the hemispherical resonator and the planar electrode.

[0067] The nano-copper paste of this example was prepared as follows: Commercial nano-copper particles, a dispersant, and a cross-linking agent were added to a glass flask in appropriate proportions. The nano-copper paste was obtained by ultrasonically dispersing the particles at high temperatures. The ultrasonic water bath temperature was 75°C, and the ultrasonic dispersion time was 120 minutes. The nano-copper particle size was 100 nm.

[0068] In this example, 20 wt% triethanolamine was used as a dispersant, based on the total weight of the nano-copper paste as 100%. Triethanolamine has excellent coordination properties and can adsorb onto the surface of the copper nanoparticles, forming a protective layer. This inhibits aggregation and agglomeration between particles and maintains dispersion. Triethanolamine also helps improve the coating properties of the copper paste by regulating viscosity, ensuring uniform distribution of the paste during deposition and sintering.

[0069] In this embodiment, based on the total weight of the nano-copper paste as 100%, 10wt% of γ-glycidyloxypropyltrimethoxysilane is used as a crosslinking agent. This crosslinking agent can form covalent bonds or hydrogen bonds with the surface of the copper particles and also react with functional groups in the organic matrix to form an organic-inorganic composite interface, significantly improving the adhesion between the particles and the matrix. At the same time, by improving the contact and interaction between the particles, the densification and interconnectivity of the copper particles can be promoted during the sintering process, thereby optimizing the mechanical strength.

[0070] Step 2: Preparation of nanometal film

[0071] Magnetron sputtering physical vapor deposition coating technology is used to deposit nano-copper films on the anchor column 3 of the hemispherical resonator 1 and the limiting hole surface of the planar electrode 2, respectively, to provide a nano-copper paste bonding interface. The specific process is as follows: First, in a vacuum environment less than 1Pa, the hemispherical resonator anchor rod and the planar electrode limiting hole are cleaned for 20 minutes by 30mA and 20sccm argon plasma to provide a clean base for depositing the metal film and ensure the quality of the film layer. Then, in a vacuum environment less than 1Pa, using 150W magnetron sputtering copper plating power and 30sccm argon flow rate, a nano-copper film of about 1.5µm is deposited within 45 minutes, forming a first copper film 4 on the hemispherical resonator anchor rod and a second copper film 5 on the wall of the planar electrode limiting hole. Figure 2 、 3 As shown in Figure 4, the surface roughness of the copper film is less than 25nm, with excellent uniformity, providing an excellent bonding interface for bonding. In other embodiments, a copper-nickel film can be plated to expand the applicability of the bonding process.

[0072] Step 3: Hemispherical oscillator-electrode base assembly

[0073] like Figure 5 As shown, the specific process of this step is as follows:

[0074] 1. Apply nano-copper paste 6 to the anchor post 3 of the hemispherical resonator 1 with a thickness such that the nano-copper paste 6 can contact the anchor post of the hemispherical resonator and the limiting hole wall of the planar electrode 2, respectively. To address the concentricity control problem that may arise during the bonding process of two vertical curved surfaces, this embodiment uses a mature self-made planar electrode structure hemispherical resonator gyroscope precision assembly device and accurately controls the thickness of the applied copper paste (controlled within the range of 5-40 μm) and optimizes the component ratio to optimize the rheological properties of the copper paste, thereby preventing excessive accumulation of the paste at the bottom due to gravity and ensuring the uniformity of the overall bonding strength of the assembly.

[0075] 2. Under vacuum conditions, a low-temperature thermal bonding process at 240°C is used to achieve copper-copper bonding between the hemispherical oscillator and the coated electrode base, thereby completing low-temperature conductive interconnection.

[0076] Traditional methods generally use copper paste to bond copper sheets at low temperatures. However, the surface roughness of the copper sheets is relatively high, and pressure (5-20 MPa) must be applied to achieve a tight interface connection. However, the hemispherical vibrator and base are both made of quartz, which is fragile, so hot pressing and hot bonding processes cannot be used, as they may cause mechanical damage. Therefore, this embodiment uses a metal film deposited by magnetron sputtering, which has higher surface uniformity and lower interface roughness than copper foil. In combination with triethanolamine, it promotes neck formation and atomic diffusion between copper particles, enabling pressure-free bonding while ensuring the mechanical strength and conductivity of the bonding interface.

[0077] To achieve the bonding strength requirement between the copper films, this embodiment selects 240°C as the bonding temperature under a vacuum environment. Test results show that at a bonding temperature of 240°C, a high mechanical strength of 30 MPa and a low contact resistance of 300 Ω can be achieved simultaneously.

[0078] The traditional nano-copper sintering process generally has a bonding time of 30 to 60 minutes. To ensure that all excess organic matter is volatilized, the process is maintained at a constant temperature of 240°C for 2 hours under a vacuum condition of <1Pa to ensure long-term operation under vacuum conditions. The dispersant and cross-linking agent selected in this embodiment mainly participate in bonding and sintering in the early stage of vacuum insulation. In the later stage of vacuum insulation, the excess dispersant and cross-linking agent can be accelerated to decompose under vacuum conditions. Sintering under vacuum conditions can not only effectively lower the boiling point of organic matter and promote its volatilization, but also increase the diffusion rate of small molecules decomposed at high temperatures, accelerating overflow.

[0079] In the present invention, the distance between the anchor rod and the electrode hole is in the range of 5 to 40 μm, which has wider applicability. It is best to apply the slurry so as to just fill the gap between the anchor rod and the electrode hole.

[0080] The electrode holes can be assembled in two ways: blind holes and through holes, thereby expanding the application scope of the present invention.

[0081] After bonding is completed, the interconnected hemispherical resonator and electrode products are bubble-cleaned for 5 minutes using ethanol, acetone, and ethanol solutions respectively to remove possible residual organic matter and nano-copper powder while avoiding surface damage caused by conventional ultrasound. They are then purged with nitrogen and dried in a 55°C oven.

[0082] The present invention selects nano-copper with different particle sizes (50nm, 100nm, 200nm, 500nm) as the raw material of nano-copper paste. According to the sintering uniformity and conductivity, as shown in Table 1, 100nm nano-copper is finally preferred as the raw material.

[0083] Table 1

[0084]

[0085] The present invention selects different heating bonding temperatures (200°C, 220°C, 240°C, 270°C and 300°C), and according to sintering uniformity and conductivity, as shown in Table 2, ultimately prefers 240°C as the bonding temperature for low-temperature pressureless bonding.

[0086] Table 2

[0087]

[0088] Comparative Example 1

[0089] This comparative example is basically the same as Example 1, and the only difference is that the dispersant and the cross-linking agent are adjusted in proportion. The basic components include 70 wt% of 100 nm nano-copper, 30 wt% of dispersant and 0 wt% of cross-linking agent.

[0090] A higher content of dispersant helps to form a sufficient protective layer in the slurry, ensuring that the nano-copper particles can be evenly dispersed and reducing the risk of agglomeration. However, due to the lack of cross-linking agent, the slurry lacks the formation of a cross-linked network, which will lead to insufficient bonding between the components during the sintering process. At the same time, after the dispersant is removed, it is very easy to disintegrate into loose copper powder, which not only causes the shear strength of the bonding interface to drop to 18MPa, but also causes contamination and defects due to powder shedding during subsequent packaging and use, seriously weakening the mechanical stability and long-term reliability of the device.

[0091] Comparative Example 2

[0092] This comparative example is basically the same as Example 1, and the only difference is that the proportion of the dispersant and the cross-linking agent is adjusted. The basic components include 70 wt% of 100 nm nano-copper, 10 wt% of the dispersant and 20 wt% of the cross-linking agent.

[0093] Reducing the dispersant content may reduce the uniform dispersion of nano-copper to some extent, but adding an appropriate amount of cross-linking agent can promote the formation of an organic-inorganic composite cross-linked network. This cross-linking strengthens the chemical bonding between particles and at the interface, improving densification and interfacial strength during sintering, and significantly enhancing the formation of nano-copper powders. However, excessively high viscosity cross-linking agents increase the interfacial contact resistance to 3000Ω, which is not conducive to meeting the conductivity requirements of the hemispherical resonator.

[0094] Comparative Example 3

[0095] This comparative example is basically the same as Example 1, and the only difference is that the dispersant and the cross-linking agent are adjusted in proportion. The basic components include 70 wt% of 100 nm nano-copper, 0 wt% of dispersant and 30 wt% of cross-linking agent.

[0096] Although completely eliminating the dispersant and using 30wt% cross-linking agent can strengthen the cross-linking reaction and prevent dust formation, the nano-copper particles are prone to agglomeration due to the lack of dispersion protection, which in turn causes local insufficient density and interface defects during the sintering process, resulting in a reduction in the interface shear strength to 15MPa. At the same time, the excessive cross-linking agent makes the contact resistance greater than 50KΩ, which does not meet the conductivity requirements of the hemispherical resonator.

[0097] In summary, the nano-copper bonding process based on sputtering copper plating of hemispherical anchor posts and electrode holes proposed in the present invention realizes pressure-free low-temperature bonding in a low-temperature, vacuum environment by adopting a pre-deposited dense metal film and an optimized ratio of nano-copper paste. This process overcomes the shortcomings of traditional high-temperature eutectic bonding and copper paste low-temperature bonding in the assembly of fragile quartz bases, and ensures high bonding strength and low contact resistance. Specific implementation data show that under the optimal process conditions, the connection between the hemispherical oscillator and the anchor post electrode has a shear strength of 30MPa and a contact resistance of less than about 300Ω, which meets the assembly requirements of high-precision inertial navigation systems. This process has the advantages of stable process and wide applicability, and provides reliable technical support for the MEMS field and high-precision inertial navigation systems.

[0098] The embodiments described above are merely preferred embodiments of the present invention. The phrases "in one embodiment," "in another embodiment," "in yet another embodiment," or "in other embodiments" used in this specification may refer to one or more of the same or different embodiments of the present disclosure. Any common changes and substitutions made by those skilled in the art within the scope of the present invention are intended to be encompassed within the scope of protection of the present invention.

Claims

1. A method for interconnecting a hemispherical anchor post and an electrode, characterized in that: The following steps are involved: 1) Copper film is plated on the anchor column surface of the hemispherical resonator and the wall of the central hole of the electrode; 2) Coating the nano-copper paste on the anchor column surface and / or the center hole wall of the electrode of the hemispherical resonator after the copper film is plated; 3) inserting the anchor post of the hemispherical resonator into the central hole of the electrode so that the cylindrical surface of the anchor post of the hemispherical resonator and the wall of the central hole of the electrode are in contact through the copper paste therebetween, and adopting a low-temperature pressureless bonding process to achieve conductive interconnection between the anchor post of the hemispherical resonator and the wall of the central hole of the electrode. Calculated based on the total weight of the nano-copper paste as 100%, the nano-copper paste includes 68wt%-72wt% of nano-copper particles, 18wt%-22wt% of a dispersant, and 8wt%-12wt% of a viscosity regulator.

2. The method for interconnecting a hemispherical anchor post and an electrode according to claim 1, wherein: The dispersant is triethanolamine, and the viscosity modifier is gamma-glycidyloxypropyltrimethoxysilane.

3. The method for interconnecting a hemispherical anchor post and an electrode according to claim 1 or 2, characterized in that: The conditions of the low-temperature pressureless bonding process are: a vacuum degree of less than 1 Pa and a temperature of 220-270° C. for 1.5-2.5 hours.

4. The method for interconnecting a hemispherical anchor post and an electrode according to claim 1 or 2, characterized in that: The diameter of the nano copper particles is 50nm-500nm.

5. The method for interconnecting a hemispherical anchor post and an electrode according to claim 1 or 2, characterized in that: The preparation process of the nano copper paste is as follows: Nano copper particles, a dispersant and a viscosity regulator are mixed in proportion, and dispersed by high-temperature ultrasound to obtain a nano copper slurry.

6. The method for interconnecting a hemispherical anchor post and an electrode according to claim 1 or 2, characterized in that: The thickness of the copper film is 1-2 μm.

7. The method for interconnecting a hemispherical anchor post and an electrode according to claim 6, wherein: The copper film is plated on the anchor column surface and the center hole wall of the electrode of the hemispherical resonator by magnetron sputtering process. The process conditions of magnetron sputtering are: magnetron sputtering power is 100-200W, argon flow rate is 25-35sccm, time is 30-60min, and vacuum degree is less than 1Pa.

8. The method for interconnecting a hemispherical anchor post and an electrode according to claim 1 or 2, characterized in that: Before step 1), also include: The anchor column surface of the hemispherical resonator and the center hole wall of the electrode are ion cleaned. The process conditions of ion cleaning are: current 20-40mA, argon flow rate 15-25sccm, vacuum degree less than 1Pa, and cleaning time 10-30min.

9. A hemispherical resonant gyroscope obtained by the method for interconnecting a hemispherical anchor post and an electrode according to any one of claims 1 to 8.

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