Reed switch with multiple reeds sealed at same end and sealing process thereof

Abstract

The invention discloses a reed switch with multiple reeds sealed at the same end and a sealing process of the reed switch, and relates to the technical field of electronic component manufacturing. A multi-reed assembly, wherein the multi-reed assembly comprises at least two reeds; the low-temperature medium glass sealing ring is provided with prefabricated through holes, and the number of the prefabricated through holes is matched with that of the multi-reed assemblies; and a seal; according to the invention, the graphite mold is matched with the continuous mesh belt furnace, so that a'full-page and full-batch 'production mode is realized, and the efficiency is improved by dozens of times compared with the traditional single-piece sealing; according to the invention, a special metal pre-oxidation process is introduced before sealing, and annealing is carried out under the protection of nitrogen, so that chemical bond combination of glass and a metal medium is tighter, the air tightness grade is improved to 10 <-9 > cc.P0 / min or above from traditional 10 <-8 >, the reliability of a product is greatly improved, and the service life of the product is greatly prolonged.

Description

Technical Field

[0001] This invention relates to the field of electronic component manufacturing technology, specifically to a reed switch with multiple reeds sealed at the same end and its sealing process. Background Technology

[0002] Reed switches, as physical switches with wide applications and high reliability, play an important role in communications, security, medical, and automotive electronics. Traditional reed switch structures typically consist of a glass tube, a fixed reed, and a moving reed, and their manufacturing process mainly employs flame or laser heating. Specifically, in an environment filled with an inert gas (such as nitrogen), the two ends of the glass tube are locally heated to a high temperature, causing the glass to melt and seal it together with the metal reed, thus forming a hermetically sealed package.

[0003] However, existing traditional sealing technologies have significant defects and shortcomings: First, production efficiency is low. Traditional methods typically involve single-piece assembly, positioning, sealing, and annealing, with the entire process taking an average of about 30 seconds per piece. Furthermore, it is difficult to achieve large-scale continuous automated production, resulting in high manufacturing costs.

[0004] Secondly, the airtightness level is limited. Due to the instantaneous fusion method of directly heating both ends of the glass tube with flame or laser, the metal spring often does not have enough time for sufficient pre-oxidation treatment. According to the theory and practice of glass-metal sealing, the interfacial bonding force of metal-glass seals without pre-oxidation is weak, and the airtightness level is generally lower than 10^-8 cc.P0 / min, which is a general level and cannot meet the high reliability requirements of high-end precision instruments.

[0005] Secondly, the structure has significant limitations. Traditional processes make it difficult to simultaneously seal two or more reeds at the same end. This is because the softening flow at the end of the glass tube is difficult to control precisely during flame or laser heating. If multiple reeds are inserted at the same end, it can easily lead to uncontrolled reed spacing, short circuits, or uneven glass coverage, making it impossible to guarantee product consistency.

[0006] To address this, a reed switch with multiple reeds sealed at the same end and its sealing process are proposed. Summary of the Invention

[0007] The purpose of this invention is to provide a reed switch with multiple reeds sealed at the same end and the sealing process thereof. This addresses one of the technical problems existing in the prior art: low production efficiency, poor airtightness, and the inability to achieve sealing of multiple reeds at the same end.

[0008] Firstly, to solve the aforementioned technical problems, this application adopts a technical solution as follows: a reed switch with multiple reeds sealed at the same end, comprising: glass tube; A multi-reed assembly comprising at least two reeds; A cryogenic dielectric glass sealing ring, wherein the cryogenic dielectric glass sealing ring is provided with prefabricated through holes adapted to the number of the multi-spring sheet assembly; And seals; The cryogenic medium glass sealing ring is sealed to one end of the glass tube, and each spring of the multi-spring assembly passes through the pre-made through hole of the cryogenic medium glass sealing ring and extends into the interior of the glass tube; the sealing element is sealed to the other end of the glass tube. The cryogenic medium glass sealing ring is made of glass material with a softening temperature lower than that of the glass tube, and a heat-fused airtight connection layer is formed between the cryogenic medium glass sealing ring, the multi-spring assembly, and the inner wall of the glass tube.

[0009] More preferably, the softening temperature of the low-temperature medium glass sealing ring is 80°C to 100°C lower than the softening temperature of the glass tube. The thermal expansion coefficient of the cryogenic medium glass sealing ring matches that of the multi-spring assembly, with a value range of 8.5~9.5 PPM.

[0010] More preferably, the multi-spring assembly includes two or three springs, which are evenly distributed along the circumference of the cryogenic medium glass sealing ring; The diameter of the pre-fabricated through holes is 0.5~3mm, and the center distance between adjacent pre-fabricated through holes is 0.5~2mm.

[0011] More preferably, the surface of the reed located within the hot-melt airtight connection layer has a metal pre-oxidation layer, and the airtightness level of the reed switch is not less than 10^-9 cc.P0 / min.

[0012] The second aspect: A sealing process for a reed switch with multiple reeds sealed at the same end, employing a continuous production method, includes the following steps: S1. Assembly and positioning: The multi-spring assembly is passed through the pre-made through hole of the low-temperature medium glass sealing ring and assembled together with the sealing element at both ends of the glass tube to form the assembly to be sealed. S2. Fixture loading: Multiple components to be sealed are loaded into a graphite precision positioning fixture in batches, and the fixture is used to restrict the axial and radial positions of the components to be sealed. S3. Continuous heat treatment: The graphite precision positioning fixture loaded with the components to be sealed is continuously fed into a continuous sealing furnace filled with protective gas, and passes through the pre-oxidation temperature zone, sealing temperature zone and annealing temperature zone in sequence. S4. Cooling and unloading: After heat treatment, the components are cooled by the fixture to obtain a reed tube with multiple reeds sealed at the same end.

[0013] More preferably, in step S3, the multi-spring assembly is pre-oxidized online in the pre-oxidation temperature zone before entering the sealing temperature zone; The process parameters for the pre-oxidation temperature zone are: temperature 380℃~420℃, holding time 25~35 minutes, and protective gas purity not less than 99.99%.

[0014] More preferably, in step S3, the temperature of the sealing temperature zone is set to the melting sealing temperature of the low-temperature medium glass sealing ring, and is lower than the softening temperature of the glass tube; The specific sealing process parameters are: temperature 630℃~670℃, holding time 25~35 minutes, and furnace atmosphere pressure maintained at 0.1~0.3MPa.

[0015] More preferably, in step S3, the process parameters of the annealing temperature zone are: constant temperature 430℃~470℃, constant temperature time 25~35 minutes, followed by gradient cooling at a rate of 5~10℃ / min.

[0016] More preferably, the graphite precision positioning fixture has a positioning groove adapted to the outer diameter of the glass tube, the dimensional tolerance of the positioning groove is controlled within ±0.02mm, and the inner wall of the positioning groove is coated with a high-temperature resistant lubricating coating.

[0017] More preferably, the protective gas is nitrogen; in step S4, the reed switch is removed from the sealing furnace after being cooled to below 50°C along with the fixture.

[0018] Advantages of this invention: This invention uses graphite molds in conjunction with a continuous mesh belt furnace to achieve a "whole plate, whole batch" production mode, which improves efficiency by dozens of times compared to traditional single-seal sealing. This invention introduces a special metal pre-oxidation process before sealing and annealing under nitrogen protection, which makes the chemical bond between the glass and the metal medium tighter and improves the airtightness level from the traditional 10^-8 to more than 10^-9 cc.P0 / min, thus greatly improving the reliability and lifespan of the product.

[0019] This invention utilizes a pre-fabricated low-temperature medium glass sealing ring as a positioning carrier, successfully solving the problem of fixed position when multiple reeds are sealed at the same end, enabling the reed switch to achieve complex functions such as single-end multi-channel control.

[0020] This invention utilizes low-temperature glass (such as MDM-910L) as an intermediate medium. The sealing temperature is much lower than the softening point of the glass tube body, thus avoiding thermal damage to the tube body. Combined with a scientific annealing curve, residual stress is effectively eliminated. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of a three-pin reed switch with multiple reeds sealed at the same end according to the present invention. Figure 2 This is a schematic diagram of a two-pin reed switch with multiple reeds sealed at the same end according to the present invention. Figure 1 ; Figure 3 This is a schematic diagram of a two-pin reed switch with multiple reeds sealed at the same end according to the present invention. Figure 2 ; Figure 4 This is a flowchart of the sealing process for the reed switch with multiple reeds sealed at the same end according to the present invention.

[0024] 1. Glass tube; 2. Multi-spring assembly; 3. Low-temperature medium glass sealing ring; 4. Seal. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Figures 1-3 This is a schematic diagram of the structure of a reed switch with multiple reeds sealed at the same end according to an embodiment of the present invention.

[0027] Example 1

[0028] like Figures 1-3 The reed switch shown is a multi-reed reed switch with the same end sealed, comprising: Glass tube 1; Multi-reed assembly 2, wherein the multi-reed assembly 2 comprises at least two reeds; The cryogenic medium glass sealing ring 3 is provided with prefabricated through holes that are adapted to the number of the multi-spring assembly 2. And seal 4; The cryogenic medium glass sealing ring 3 is sealed to one end of the glass tube 1, and each spring of the multi-spring assembly 2 passes through the pre-made through hole of the cryogenic medium glass sealing ring 3 and extends into the interior of the glass tube 1; the sealing member 4 is sealed to the other end of the glass tube 1. The cryogenic medium glass sealing ring 3 is made of glass material with a softening temperature lower than that of the glass tube 1, and a heat-fused airtight connection layer is formed between the cryogenic medium glass sealing ring 3, the multi-spring assembly 2, and the inner wall of the glass tube 1.

[0029] In this embodiment, specifically, the softening temperature of the low-temperature medium glass sealing ring 3 is 80°C to 100°C lower than the softening temperature of the glass tube 1. The thermal expansion coefficient of the cryogenic medium glass sealing ring 3 is matched with that of the multi-spring assembly 2, with a value range of 8.5~9.5 PPM.

[0030] In this embodiment, specifically, the multi-spring assembly 2 includes two or three springs, which are evenly distributed along the circumference of the low-temperature medium glass sealing ring 3. The diameter of the pre-fabricated through holes is 0.5~3mm, and the center distance between adjacent pre-fabricated through holes is 0.5~2mm.

[0031] In this embodiment, specifically, the surface of the reed located within the hot-melt airtight connection layer has a metal pre-oxidation layer, and the airtightness level of the reed switch is not less than 10^-9 cc.P0 / min.

[0032] Example 2

[0033] This embodiment provides a reed switch with multiple reeds sealed at the same end, mainly including a glass tube body, a multi-reed assembly, a low-temperature medium glass sealing ring, and a sealing glass block.

[0034] The glass tube body is made of high borosilicate glass, which has a high softening temperature. The cryogenic medium glass sealing ring uses the cryogenic environmentally friendly glass material MDM-910L. This material is specially formulated with a coefficient of thermal expansion (CTE) of 9.1 PPM, which is highly matched with the expansion coefficient of commonly used iron-nickel alloy springs, thereby reducing airtightness failure caused by thermal expansion and contraction. Crucially, the sealing temperature of MDM-910L is 650℃, and its softening temperature is 80-100℃ lower than that of the glass tube body. This means that during the sealing process, the sealing ring melts and wraps around the spring, while the glass tube body remains solid and rigid, preventing collapse and deformation.

[0035] In terms of structural details, the cryogenic medium glass sealing ring is pre-machined with a group of through holes. In this embodiment, it is designed with three springs sealed at the same end, so the sealing ring has three axially evenly distributed through holes with a diameter of 1.5 mm (within the range of 0.5~3 mm). The diameter tolerance is strictly controlled within ±0.05 mm, and the center distance between adjacent through holes is 4 mm. This high-precision prefabricated structure ensures that the relative position of the springs can be fixed without complex external clamps after insertion.

[0036] Example 3

[0037] like Figure 4 This embodiment also provides a sealing process for a reed switch with multiple reeds sealed at the same end, which adopts a continuous production method and includes the following steps: S1. Assembly and positioning: The multi-spring assembly is passed through the pre-made through hole of the low-temperature medium glass sealing ring and assembled together with the sealing element at both ends of the glass tube to form the assembly to be sealed. S2. Fixture loading: Multiple components to be sealed are loaded into a graphite precision positioning fixture in batches, and the fixture is used to restrict the axial and radial positions of the components to be sealed. S3. Continuous heat treatment: The graphite precision positioning fixture loaded with the components to be sealed is continuously fed into a continuous sealing furnace filled with protective gas, and passes through the pre-oxidation temperature zone, sealing temperature zone and annealing temperature zone in sequence. S4. Cooling and unloading: After heat treatment, the components are cooled by the fixture to obtain a reed tube with multiple reeds sealed at the same end.

[0038] In step S3, before entering the sealing temperature zone, the multi-spring assembly is first subjected to online pre-oxidation treatment in the pre-oxidation temperature zone; The process parameters for the pre-oxidation temperature zone are: temperature 380℃~420℃, holding time 25~35 minutes, and protective gas purity not less than 99.99%.

[0039] In step S3, the temperature of the sealing temperature zone is set to the melting sealing temperature of the low-temperature medium glass sealing ring, and is lower than the softening temperature of the glass tube. The specific sealing process parameters are: temperature 630℃~670℃, holding time 25~35 minutes, and furnace atmosphere pressure maintained at 0.1~0.3MPa.

[0040] In step S3, the process parameters for the annealing temperature zone are: constant temperature of 430℃~470℃, constant temperature time of 25~35 minutes, followed by gradient cooling at a rate of 5~10℃ / min.

[0041] The graphite precision positioning fixture has a positioning groove that matches the outer diameter of the glass tube (1). The dimensional tolerance of the positioning groove is controlled within ±0.02mm, and the inner wall of the positioning groove is coated with a high-temperature resistant lubricating coating.

[0042] The protective gas is nitrogen; in step S4, the reed switch is removed from the sealing furnace after being cooled to below 50°C along with the fixture.

[0043] Example 4

[0044] This embodiment also provides a sealing process based on the above structure, which specifically includes the following steps: Step S1: Precision Assembly The three cleaned metal springs are passed through the corresponding through holes of the cryogenic medium glass sealing ring. The sealing ring is pushed to the predetermined sealing position of the springs. The assembly is then inserted into one end of the glass tube. At the other end of the glass tube, another set of springs or a simple sealing glass block (approximately 3 mm thick) is installed as needed.

[0045] Step S2: Mold positioning A specialized graphite precision positioning fixture is used. Graphite has excellent thermal conductivity and high-temperature resistance, and a low coefficient of thermal expansion. The fixture has hundreds of precision positioning grooves, with dimensional tolerances controlled within ±0.02mm, and the inner walls are coated with a high-temperature resistant lubricating coating (such as boron nitride coating) to prevent the glass from sticking to the mold after melting. The reed switch semi-finished product assembled in step S1 is laid flat in the fixture.

[0046] Step S3: Continuous furnace feeding The graphite fixture filled with the product is placed on the conveyor belt of a nitrogen-protected continuous sealing furnace. The furnace is filled with nitrogen gas with a purity of not less than 99.99% to prevent uncontrolled metal oxidation.

[0047] Step S4: The product undergoes gradient temperature control treatment, passing through four temperature zones sequentially within the furnace: Metal pre-oxidation zone: Temperature set at 400℃, holding time 30 minutes. At this temperature, the iron-nickel alloy on the reed surface reacts with trace amounts of oxygen (or controlled oxygen partial pressure in the atmosphere) to form a dense oxide film of moderate thickness. This oxide film is crucial for the subsequent chemical bonding between the glass and the metal.

[0048] High-temperature sealing zone: The temperature rises to 650℃ and is held for 30 minutes, while the nitrogen pressure inside the furnace is maintained at 0.1~0.3MPa. At this time, the low-temperature medium glass sealing ring softens and melts, tightly wrapping the pre-oxidized layer of the spring sheet by surface tension, and fusing with the inner wall of the glass tube, filling all gaps and forming a solid seal.

[0049] Precision annealing zone: The temperature is reduced to 450℃ and held for 30 minutes, followed by slow cooling at a rate of 5~10℃ / min. This process is used to eliminate residual thermal stress inside the glass caused by rapid cooling, preventing the product from cracking during subsequent use.

[0050] Cooling zone after exiting the furnace: The product continues to run along the conveyor belt and is naturally cooled to below 50°C before being exited from the furnace.

[0051] Example 5

[0052] For a continuous sealing furnace under nitrogen protection, the following sealing process parameters are set: process Metal pre-oxidation seal annealing Cooling down before baking Parameter settings 400℃ 650℃ 450℃ 50℃ time 30 minutes 30 minutes 30 minutes 30 minutes Effect verification: The reed switches produced using the above process, after being tested with a helium mass spectrometer leak detector, generally achieved an airtightness level of over 10^-9 cc.P0 / min, which is superior to the 10^-8 level of traditional processes. Furthermore, due to the implementation of a single-end 3-reed structure, this reed switch can be used as a single-pole double-throw (SPDT) or even more complex logic switch, greatly expanding its application range.

[0053] For a detailed description of this embodiment, please refer to the corresponding descriptions in the foregoing embodiments, which will not be repeated here.

[0054] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A reed switch with multiple reeds sealed at the same end, characterized in that, include: Glass tube (1); A multi-reed assembly (2) comprising at least two reeds; The cryogenic medium glass sealing ring (3) is provided with prefabricated through holes that are adapted to the number of the multi-spring assembly (2); And the seal (4); The cryogenic medium glass sealing ring (3) is sealed to one end of the glass tube (1), and each spring of the multi-spring assembly (2) passes through the pre-made through hole of the cryogenic medium glass sealing ring (3) and extends into the interior of the glass tube (1); the sealing element (4) is sealed to the other end of the glass tube (1). The low-temperature medium glass sealing ring (3) is made of glass material with a softening temperature lower than that of the glass tube (1), and a heat-fused airtight connection layer is formed between the low-temperature medium glass sealing ring (3), the multi-spring assembly (2), and the inner wall of the glass tube (1).

2. The reed switch with multiple reeds sealed at the same end according to claim 1, characterized in that, The softening temperature of the low-temperature medium glass sealing ring (3) is 80°C to 100°C lower than that of the glass tube (1). The thermal expansion coefficient of the cryogenic medium glass sealing ring (3) matches that of the multi-spring assembly (2), with a value range of 8.5~9.5 PPM.

3. The reed switch with multiple reeds sealed at the same end according to claim 1, characterized in that, The multi-spring assembly (2) includes two or three springs, which are evenly distributed along the circumference of the cryogenic medium glass sealing ring (3). The diameter of the pre-fabricated through holes is 0.5~3mm, and the center distance between adjacent pre-fabricated through holes is 0.5~2mm.

4. The reed switch with multiple reeds sealed at the same end according to claim 1, characterized in that, The reed has a metal pre-oxidation layer on its surface located within the hot-melt airtight connection layer, and the airtightness level of the reed switch is not less than 10^-9 cc.P0 / min.

5. A sealing process for a reed switch with multiple reeds sealed at the same end as described in any one of claims 1-4, characterized in that, The continuous production method includes the following steps: S1. Assembly and positioning: The multi-spring assembly (2) is passed through the pre-made through hole of the low-temperature medium glass sealing ring (3) and assembled together with the sealing element (4) at both ends of the glass tube (1) to form the assembly to be sealed. S2. Fixture loading: Multiple components to be sealed are loaded into a graphite precision positioning fixture in batches, and the fixture is used to restrict the axial and radial positions of the components to be sealed. S3. Continuous heat treatment: The graphite precision positioning fixture loaded with the components to be sealed is continuously fed into a continuous sealing furnace filled with protective gas, and passes through the pre-oxidation temperature zone, sealing temperature zone and annealing temperature zone in sequence. S4. Cooling and unloading: After heat treatment, the components are cooled by the fixture to obtain a reed tube with multiple reeds sealed at the same end.

6. The sealing process according to claim 5, characterized in that, In step S3, before entering the sealing temperature zone, the multi-spring assembly (2) is subjected to online pre-oxidation treatment in the pre-oxidation temperature zone; The process parameters for the pre-oxidation temperature zone are: temperature 380℃~420℃, holding time 25~35 minutes, and protective gas purity not less than 99.99%.

7. The sealing process according to claim 5, characterized in that, In step S3, the temperature of the sealing temperature zone is set to the melting sealing temperature of the low-temperature medium glass sealing ring (3), and is lower than the softening temperature of the glass tube (1). The specific sealing process parameters are: temperature 630℃~670℃, holding time 25~35 minutes, and furnace atmosphere pressure maintained at 0.1~0.3MPa.

8. The sealing process according to claim 5, characterized in that, In step S3, the process parameters for the annealing temperature zone are: constant temperature of 430℃~470℃, constant temperature time of 25~35 minutes, followed by gradient cooling at a rate of 5~10℃ / min.

9. The sealing process according to claim 5, characterized in that, The graphite precision positioning fixture has a positioning groove that matches the outer diameter of the glass tube (1). The dimensional tolerance of the positioning groove is controlled within ±0.02mm, and the inner wall of the positioning groove is coated with a high-temperature resistant lubricating coating.

10. The sealing process according to claim 5, characterized in that, The protective gas is nitrogen; in step S4, the reed switch is removed from the sealing furnace after being cooled to below 50°C along with the fixture.

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