High-reliability metal shell for gyroscope and preparation method of high-reliability metal shell

Abstract

The invention discloses a high-reliability metal shell for a gyroscope, which is characterized by comprising a metal shell substrate made of iron-nickel alloy; the ceramic insulator is fixedly arranged in the through hole of the metal shell base body; the metal lead penetrates through the ceramic insulator and is electrically isolated from the ceramic insulator; wherein a plurality of adaptive structures for mounting chips are arranged in the metal shell base body, and flange holes for assembling and positioning are formed in the outer part of the metal shell base body.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electronic packaging, in particular to a high-reliability metal shell for a gyroscope and a preparation method thereof. BACKGROUND

[0002] With the rapid development of modern aerospace, precision navigation and industrial automation, the performance requirements of the core sensor, i.e. the gyroscope, are increasingly stringent. The gyroscope is developing towards lightweight, miniaturization and high reliability. As a core support and protection component of the gyroscope, the metal shell not only needs to provide mechanical support and physical protection for the internal precision chip and circuit, but also must have excellent heat dissipation performance, long-term sealing performance and stable service capability in extreme environments (such as high and low temperature, severe vibration and high vacuum).

[0003] At present, the commonly used shell base materials for the gyroscope in the industry mainly include stainless steel, aluminum alloy and titanium alloy, but they each have inherent defects that are difficult to overcome: the stainless steel base material is heavy, which is not conducive to weight reduction of the equipment; the aluminum alloy base material has insufficient mechanical strength and is difficult to cope with extreme working conditions; the titanium alloy base material is high in cost and is not conducive to large-scale application.

[0004] In addition, the above-mentioned metal materials face a common process difficulty in the process of preparing the hermetic packaging of the shell: after high-temperature sintering, an oxide layer is easily formed on the surface of the base, which must be polished and cleaned with a strong acid solution. This process not only has a potential corrosion risk to the surface of the base, but also produces a large amount of waste acid, which is not environmentally friendly.

[0005] Therefore, there is an urgent need in the art for a new material and preparation scheme with excellent comprehensive performance and environmentally friendly process to prepare a metal shell that can meet the requirements of the next generation of high-reliability gyroscopes. SUMMARY

[0006] Objectives of the present application To solve the above-mentioned problems in the prior art, the first objective of the present application is to provide a metal shell for a gyroscope with high reliability, high hermeticity, light weight and suitable for environmentally friendly process. The second objective of the present application is to provide a preparation method for the shell, which is stable in process and can achieve excellent metal-ceramic sealing connection.

[0007] Technical solutions of the present application To achieve the above-mentioned objectives, the present application adopts the following technical solutions: A high-reliability metal shell for a gyroscope, comprising a metal shell base, a ceramic insulator and a metal lead. The material of the metal shell base is iron-nickel alloy, preferably with a grade of 4J33, and the nickel content is 32% to 33.6%. The alloy has the characteristics of low density, good thermal expansion coefficient matching with ceramic, high mechanical strength and excellent weldability.

[0008] The metal casing substrate has an internal adapter structure for chip mounting and external flange holes for assembly positioning. A key improvement is the presence of several stepped through holes on the metal casing substrate, including stepped holes and open holes. The stepped holes have a diameter slightly larger than the outer diameter of the ceramic insulator by 0.02–0.05 mm, used for precise positioning of the ceramic insulator. The open holes have a diameter larger than the outer diameter of the ceramic insulator by 0.5–0.8 mm, forming cavities to accommodate metal solder.

[0009] The ceramic insulator is made of alumina ceramic with an Al2O3 content of 93%–95%, exhibiting good insulation and a thermal expansion coefficient that matches that of metals. The metal lead penetrates the ceramic insulator and is hermetically sealed to the metal outer shell substrate using solder.

[0010] A method for manufacturing a high-reliability metal casing for the above-mentioned gyroscope includes the following steps: We provide metal housing substrates, ceramic insulators, metal leads, metal solder, and matching lead positioning molds and inner positioning molds; The metal leads are fitted to the lead positioning mold; Place the metal casing substrate and the metal lead wires side by side on the surface of the lead wire positioning mold. Insert the ceramic insulator into the metal lead and adapt it to the stepped hole in the metal casing substrate; Metal solder is placed in the gap between the opening and the ceramic insulator; The internal positioning mold is fitted to the assembled parts and flatly attached to the inner surface of the metal shell base to fix the internal structure. The assembled product is placed in a hydrogen atmosphere furnace for welding, where the hydrogen volume concentration is 10% to 15%, the welding temperature is 810℃ to 830℃, and the welding time is 8 min to 10 min. After welding, the product is cooled to room temperature under a protective atmosphere to obtain the finished product.

[0011] The positioning hole diameter of the mold is 1.01 to 1.03 times the diameter of the metal lead wire to ensure accurate positioning.

[0012] Beneficial effects of the present invention Compared with the prior art, the present invention has the following significant advantages: The material boasts significant advantages: 4J33 iron-nickel alloy is selected as the matrix, perfectly balancing lightweight, high strength, excellent solderability, and moderate cost. Its coefficient of thermal expansion is highly compatible with alumina ceramics, fundamentally reducing the risk of failure due to thermal stress after encapsulation.

[0013] The ingenious structural design features a unique stepped through-hole structure. Through precise dimensional matching (stepped hole positioning and open hole material holding), the relative positional accuracy between the ceramic insulator and the metal shell is ensured, laying the structural foundation for the formation of a uniform and complete solder sealing layer.

[0014] Exceptional sealing performance: Based on optimized material combinations and structural design, coupled with precisely controlled hydrogen-protected welding processes, the manufactured shell achieves extremely high airtightness, with a sealing performance of 1×10⁻⁶. -11 Pa m 3 / s, far exceeding the current technology level (1×10 -9 Pa m 3 ( / s), which can meet the long-term use requirements of extreme environments such as aerospace.

[0015] The process is environmentally friendly and reliable: The hydrogen atmosphere welding process used in this invention is a clean reducing atmosphere that can effectively remove oxides from the metal surface during the welding process. It eliminates the strong acid cleaning step in the traditional process, eliminates the risk of corrosion to the substrate and environmental pollution, and conforms to the trend of green manufacturing.

[0016] High yield and good consistency: By using dedicated inner and outer positioning molds, the relative positions of each component (especially multiple leads) are kept fixed during the welding process, effectively avoiding problems such as misalignment and skewing, and greatly improving the first-time molding pass rate and batch consistency of the products. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of this embodiment; Figure 2 This is a partial structural diagram of this embodiment; Figure 3 This is a schematic diagram of the through hole structure; Reference numerals: 1-Metal casing substrate, 2-Ceramic insulator, 3-Metal lead wire, 4-Lead wire positioning mold, 5-Inner positioning mold, 6-Through hole, 7-Open hole, 8-Stepped hole, 9-Flange hole. Detailed Implementation

[0018] The following is in conjunction with the appendix Figure 1 and Figure 2 and Figure 3 The present invention will be described in further detail below. Example

[0019] This embodiment uses the minimum value of the parameters in the claims to verify the performance of the metal casing under extreme conditions.

[0020] Component provided: Metal casing substrate 1: Made of iron-nickel alloy, grade 4J33, with a nickel content of 32% (minimum). Precision machined, it has multiple stepped through holes 6 machined on it. Among them, the diameter of the stepped hole 8 is 0.02mm larger than the outer diameter of the ceramic insulator 2, and the diameter of the open hole 7 is 0.5mm larger than the outer diameter of the ceramic insulator 2.

[0021] Ceramic insulator 2: Made of alumina ceramic with an Al2O3 content of 93%.

[0022] Metal lead 3: Kovar alloy is used.

[0023] Metal solder: Silver-copper alloy solder is used.

[0024] Mold: including lead wire positioning mold 4 and inner positioning mold 5, the diameter of the positioning hole is 1.01 times the diameter of the metal lead wire 3.

[0025] Preparation steps: The metal lead 3 is precisely inserted into the corresponding hole of the lead positioning mold 4.

[0026] Cover the mold with the metal shell substrate 1, aligning its through hole 6 with the metal lead wire 3.

[0027] The ceramic insulator 2 is passed through the metal lead 3 in sequence and gently pressed into the stepped hole 8, and the initial positioning is achieved by using a gap of 0.02mm.

[0028] A predetermined amount of silver-copper solder ring is filled into the annular gap formed by each opening 7 and the ceramic insulator 2.

[0029] Cover the inner positioning mold 5 and make it flat against the inner surface of the metal housing base 1 to fix the entire component.

[0030] The entire assembly is fed into an atmosphere sintering furnace filled with a hydrogen-nitrogen mixture, with the hydrogen volume concentration controlled at 10%.

[0031] The furnace temperature is raised to 810℃ at a certain heating rate and held at this temperature for 8 minutes to allow the solder to fully melt, flow and form a tight seal.

[0032] After welding is completed, the metal casing of the gyroscope is cooled to below 150°C in the furnace and then removed to obtain a high-airtightness gyroscope metal shell.

[0033] Test results: The airtightness of the shell prepared in this embodiment was determined to be 9.2 × 10⁻⁶ after testing with a helium mass spectrometer leak detector. -12 Pa·m 3 / s, far exceeding conventional requirements (1×10 -9 Pa·m 3 / s). The housing is lightweight and high-strength, meeting the application requirements of aerospace-grade gyroscopes. Example

[0034] This embodiment uses the maximum value of the parameters in the claims to verify the performance of the metal casing under another extreme condition.

[0035] Component provided: Metal casing substrate 1: Made of iron-nickel alloy, grade 4J33, with a nickel content of 33.6%. Precision machined, it has multiple stepped through holes 6 machined on it. Among them, the diameter of the stepped hole 8 is 0.05mm larger than the outer diameter of the ceramic insulator 2, and the diameter of the open hole 7 is 0.8mm larger than the outer diameter of the ceramic insulator 2.

[0036] Ceramic insulator 2: Made of alumina ceramic with an Al2O3 content of 95%.

[0037] Metal lead 3: Kovar alloy is used.

[0038] Metal solder: Silver-copper alloy solder is used.

[0039] Mold: including lead wire positioning mold 4 and inner positioning mold 5, the diameter of the positioning hole is 1.03 times the diameter of the metal lead wire 3.

[0040] Preparation steps: The metal lead 3 is precisely inserted into the corresponding hole of the lead positioning mold 4.

[0041] Cover the mold with the metal shell substrate 1, aligning its through hole 6 with the metal lead wire 3.

[0042] The ceramic insulator 2 is passed through the metal lead 3 in sequence and gently pressed into the stepped hole 8, and the initial positioning is achieved by using a gap of 0.05mm.

[0043] A predetermined amount of silver-copper solder ring is filled into the annular gap formed by each opening 7 and the ceramic insulator 2.

[0044] Cover the inner positioning mold 5 and make it flat against the inner surface of the metal housing base 1 to fix the entire component.

[0045] The entire assembly is fed into an atmosphere sintering furnace filled with a hydrogen-nitrogen mixture, with the hydrogen volume concentration controlled at 15%.

[0046] The furnace temperature is raised to 830°C at a certain heating rate and held at this temperature for 10 minutes to allow the solder to fully melt, flow, and form a tight seal.

[0047] After welding is completed, the metal casing of the gyroscope is cooled to below 150°C in the furnace and then removed to obtain a high-airtightness gyroscope metal shell.

[0048] Test results: The airtightness of the shell prepared in this embodiment was determined to be 7.8 × 10⁻⁶ by helium mass spectrometry leak detection. -12 Pa·m 3 / s, far exceeding conventional requirements. The housing maintains excellent sealing performance even under high temperatures and prolonged welding, making it suitable for extreme environments. Example

[0049] This embodiment uses the midpoint value of the parameter in the claims as a typical implementation method.

[0050] Component provided: Metal outer casing substrate 1: Made of iron-nickel alloy, grade 4J33, with a nickel content of 32.8%. Precision machined, it has multiple stepped through holes 6 machined on it. Among them, the diameter of the stepped hole 8 is 0.03mm larger than the outer diameter of the ceramic insulator 2, and the diameter of the open hole 7 is 0.65mm larger than the outer diameter of the ceramic insulator 2.

[0051] Ceramic insulator 2: Made of alumina ceramic with an Al2O3 content of 94%.

[0052] Metal lead 3: Kovar alloy is used.

[0053] Metal solder: Silver-copper alloy solder is used.

[0054] Mold: including lead wire positioning mold 4 and inner positioning mold 5, the diameter of the positioning hole is 1.02 times the diameter of the metal lead wire 3.

[0055] Preparation steps: The metal lead 3 is precisely inserted into the corresponding hole of the lead positioning mold 4.

[0056] Cover the mold with the metal shell substrate 1, aligning its through hole 6 with the metal lead wire 3.

[0057] The ceramic insulator 2 is passed through the metal lead 3 in sequence and gently pressed into the stepped hole 8, and the initial positioning is achieved by using a gap of 0.03mm.

[0058] A predetermined amount of silver-copper solder ring is filled into the annular gap formed by each opening 7 and the ceramic insulator 2.

[0059] Cover the inner positioning mold 5 and make it flat against the inner surface of the metal housing base 1 to fix the entire component.

[0060] The entire assembly was fed into an atmosphere sintering furnace filled with a hydrogen-nitrogen mixture, with the hydrogen volume concentration controlled at 12%.

[0061] The furnace temperature is raised to 820°C at a certain heating rate and held at this temperature for 9 minutes to allow the solder to fully melt, flow and form a tight seal.

[0062] After welding is completed, the metal casing of the gyroscope is cooled to below 150°C in the furnace and then removed to obtain a high-airtightness gyroscope metal shell.

[0063] Test results: The airtightness of the shell prepared in this embodiment was determined to be 8.5 × 10⁻⁶ after testing with a helium mass spectrometer leak detector. -12 Pa·m 3 / s, far exceeding conventional requirements. The overall performance of the casing is excellent, representing a typical implementation effect of the present invention.

[0064] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A high-reliability metal housing for a gyroscope, characterized in that, include: The metal outer shell base is made of an iron-nickel alloy; A ceramic insulator is fixedly installed inside the through hole of the metal outer shell substrate; A metal lead wire passes through the ceramic insulator and provides electrical isolation therefrom; The metal casing substrate has several adapter structures inside for mounting chips, and flange holes on its exterior for assembly and positioning.

2. The high-reliability metal housing for a gyroscope according to claim 1, characterized in that, The iron-nickel alloy is designated as 4J33, and its nickel content is 32% to 33.6%.

3. The high-reliability metal housing for a gyroscope according to claim 1, characterized in that, The through hole has a stepped structure, including a stepped hole and an open hole; The diameter of the stepped hole is slightly larger than the outer diameter of the ceramic insulator, and is used for radial positioning of the ceramic insulator; The diameter of the opening is larger than that of the stepped hole, and it is used to accommodate metal solder.

4. The high-reliability metal housing for a gyroscope according to claim 3, characterized in that, The diameter of the stepped hole is 0.02 to 0.05 mm larger than the outer diameter of the ceramic insulator.

5. The high-reliability metal housing for a gyroscope according to claim 3, characterized in that, The diameter of the opening is 0.5 to 0.8 mm larger than the outer diameter of the ceramic insulator.

6. The high-reliability metal housing for a gyroscope according to claim 1, characterized in that, The ceramic insulator is made of alumina ceramic with an Al2O3 content of 93% to 95%.

7. A method for manufacturing a high-reliability metal casing for a gyroscope as described in any one of claims 1 to 6, characterized in that, Includes the following steps: We provide metal housing substrates, ceramic insulators, metal leads, metal solder, and matching lead positioning molds and inner positioning molds; The metal lead wire is fitted into the lead wire positioning mold; The metal outer shell substrate is aligned with the metal lead wire and placed flat on the surface of the lead wire positioning mold. The ceramic insulator is inserted into the metal lead and adapted to the stepped hole of the metal shell substrate; The metal solder is placed in the gap between the opening and the ceramic insulator; The inner positioning mold is fitted to the assembled parts and then flattened onto the inner surface of the metal shell substrate. The assembled product is placed in a hydrogen atmosphere furnace for welding. After welding, it is cooled to obtain the finished product.

8. The preparation method according to claim 7, characterized in that, In the hydrogen atmosphere furnace, the volume concentration of hydrogen is 10% to 15%.

9. The preparation method according to claim 7, characterized in that, The welding temperature is 810℃~830℃, and the welding time is 8min~10min.

10. The preparation method according to claim 7, characterized in that, The matching mold includes a lead wire positioning mold and an inner positioning mold. The mold is provided with positioning holes corresponding to the outer shell. The diameter of the positioning holes is 1.01 to 1.03 times the diameter of the metal lead wire.

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