Preparation method of low-leakage-flux TO-5 relay magnetism gathering shell based on side wall deposition magnetism gathering film

Abstract

The invention discloses a preparation method of a low magnetic flux leakage TO-5 relay magnetic gathering shell based on a side wall deposition magnetic gathering film. The method comprises the following steps: 1, positioning a magnetic flux leakage area; 2, performing mask shielding; 3, depositing a thin film; 4, directional magnetizing; and 5, overall detection. Ansys Maxwell simulation software is adopted to determine the projection position of a serious magnetic leakage area on a relay shell in the attraction process of a yoke and an armature, a layer of rare earth permanent magnet magnetism gathering film is attached to the position through a PVD technology to serve as a magnetism gathering ring, and the magnetizing direction of the magnetism gathering film is configured to be repellent to the leakage magnetic flux direction. Therefore, the edge leakage flux is compressed to the center of the working air gap. The problem that solid magnetic steel cannot be additionally installed due to the fact that the internal space of a TO-5 relay is limited is solved through the high-energy-product thin film with the micron-order thickness, the contact attraction and the electromagnetic efficiency are remarkably improved on the premise that the size is not increased, and the TO-5 relay has the advantages of being high in binding force, good in environment resistance and the like.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic relay manufacturing technology, and relates to a magnetic circuit optimization method for sealed relays with limited internal space. Specifically, it relates to a method for preparing a low-leakage magnetic TO-5 relay magnetic housing based on a magnetically concentrated thin film deposited on the sidewall. Background Technology

[0002] TO-5 relays are widely used in aerospace, radio frequency communications, and high-density circuit boards due to their small size, good sealing, and strong resistance to shock and vibration. Because of the standard size limitations of the TO-5 package, its internal magnetic circuit structure is extremely compact.

[0003] In existing electromagnetic relay designs, an unavoidable air gap exists between the yoke and the armature. According to electromagnetic field theory, when magnetic flux passes through the air gap, the magnetic field lines diverge significantly at the gap edge due to the much greater magnetic reluctance of air compared to ferromagnetic materials, resulting in leakage flux. The presence of leakage flux directly leads to a reduction in electromagnetic conversion efficiency, manifested as a decrease in the actual electromagnetic attraction force acting on the armature at the same coil ampere-turns.

[0004] To solve the problem of magnetic leakage, existing large relays typically employ the following two solutions:

[0005] (1) Adding an external magnetic shield: increases volume and weight, not suitable for TO-5 relays.

[0006] (2) Install permanent magnets inside: Place block sintered magnets next to the magnetic circuit. However, the effective space inside the TO-5 relay is often only millimeters or even smaller, and the shape is irregular, making it impossible to accommodate block magnets of conventional size; even if a micro magnet is barely placed, the process of precise positioning and adhesive fixation is extremely difficult, and it is very easy to fall off under impact, leading to product failure.

[0007] Therefore, there is an urgent need for a new technical solution that can effectively utilize a permanent magnetic field to "gather" or "compress" leakage magnetic field without occupying physical space. Summary of the Invention

[0008] To address the challenges of installing magnet-assisted attraction elements and severe magnetic leakage in existing micro-relay technologies, this invention provides a method for fabricating a low-leakage magnetic flux TO-5 relay magnetic housing based on a sidewall-deposited magnetic flux-concentrating thin film. This method uses Ansys Maxwell simulation software to determine the projection location of the area with severe magnetic leakage during the yoke-armature engagement process on the relay housing. A rare-earth permanent magnet magnetic flux-concentrating thin film (such as NdFeB or SmCo) is then deposited at this location as a magnetic flux-concentrating ring using physical vapor deposition (PVD). The magnetization direction of this magnetic flux-concentrating thin film is configured to repel the leakage flux direction, thereby compressing the edge leakage flux towards the center of the working air gap. This invention utilizes a high-energy-product thin film with a thickness of micrometers to solve the problem of limited internal space in TO-5 relays, which prevents the installation of solid magnets. It significantly improves contact attraction and electromagnetic efficiency without increasing volume, and has advantages such as strong bonding force and good environmental resistance.

[0009] The objective of this invention is achieved through the following technical solution:

[0010] A method for fabricating a low-leakage magnetic flux TO-5 relay magnetic housing based on a sidewall-deposited magnetic flux thin film includes the following steps:

[0011] Step 1: Locating the leakage magnetic field area: Collect relay magnetic circuit data, establish a relay magnetic circuit simulation model, and determine the projection position of the area with the most severe leakage magnetic field during the engagement of the yoke and armature on the relay housing through Ansys Maxwell finite element analysis.

[0012] Step 2, Masking: A precision mask is placed on the inner wall of the relay housing to be processed to cover the non-coated areas and expose only the leakage magnetic coating area corresponding to the area with the most severe leakage magnetic field.

[0013] Step 3, Thin Film Deposition: Using magnetron sputtering technology, a magnetically concentrated thin film is deposited in the magnetic leakage coating area using a rare earth permanent magnet alloy as the target material. The main material of the magnetically concentrated thin film is a rare earth permanent magnet material, including rare earth permanent magnet alloys such as neodymium iron boron or samarium cobalt, with a thickness of 10~200μm. The magnetically concentrated thin film has an annular strip structure, distributed along the inner sidewall of the shell, and its height covers the integrity area with severe air gap magnetic leakage.

[0014] Step 4, Directional Magnetization: The magnetic film is biased and magnetized using a magnetization fixture. The magnetization direction of the biased magnetization is opposite to the direction of the leakage flux vector at that location.

[0015] Step 5, Outer shell inspection: Measure the thickness of the magnetic film within the range of 10~200μm, and ensure that its position is in contact with the area of ​​most severe magnetic leakage between the relay yoke and armature to achieve the magnetic focusing effect.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] 1. Small space occupation: The thickness of the PVD film is only at the micron to hundred-micron level, which can be perfectly adapted to the narrow internal space of the TO-5 housing without changing the original external dimensions of the relay.

[0018] 2. Significantly enhances attraction: The strong magnetic field generated by high-energy-product materials compresses the leakage magnetic field at the edges, significantly enhancing the electromagnetic attraction and helping to reduce coil power consumption.

[0019] 3. High process reliability: The deposited film is atomically bonded to the substrate, with a bonding force far stronger than that of adhesives. It is also resistant to high temperatures and vibrations, making it suitable for harsh working conditions. Attached Figure Description

[0020] Figure 1 This is a cross-sectional view of the TO-5 relay.

[0021] Figure 2 This is a schematic diagram of the air gap leakage flux of the TO-5 relay;

[0022] Figure 3 This is a schematic diagram of magnetic focusing;

[0023] Figure 4 This is a process flow diagram for the fabrication of the magnetic housing of a low-leakage TO-5 relay;

[0024] Figure 5 This is a comparison chart of the electromagnetic attraction stroke curves of the present invention and the prior art. Detailed Implementation

[0025] The technical solution of the present invention will be further described below with reference to the accompanying drawings, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention that do not depart from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.

[0026] This invention provides a method for preparing a low-leakage magnetic flux TO-5 relay magnetic housing based on a sidewall-deposited magnetic flux thin film, such as... Figure 1 As shown, the relay includes a base, coil, yoke, armature, and housing. A 100μm thick annular magnetic film is attached to the side of the housing within the working air gap formed by the yoke and armature. This annular magnetic film is deposited using a PVD process, preferably made of rare-earth permanent magnet alloys such as neodymium iron boron (NdFeB) or samarium cobalt (SMC). The annular magnetic film undergoes specific magnetization treatment, and the direction of its generated magnetic field is designed to be opposite to the direction of the original diverging leakage magnetic field at that location. Based on the principle of magnetic field superposition, the magnetic field generated by the annular magnetic film constitutes a magnetic barrier, forcing the edge leakage magnetic field to contract towards the center of the air gap, thereby increasing the magnetic flux density within the effective working area. The preparation steps of the magnetic housing are as follows:

[0027] Step 1: Using Ansys Maxwell simulation, the region with the most severe magnetic leakage during the armature-yoke engagement process is determined to be the annular region on the outer wall of the air gap side. Figure 2 As shown.

[0028] Step 2: Create a precision mask inside the sidewall shell to cover the non-coated areas and expose only the magnetic leakage coating area corresponding to the area with the most severe magnetic leakage.

[0029] Step 3: In a high-vacuum magnetron sputtering apparatus, using NdFeB alloy as the target material, magnetron sputtering technology is employed to deposit a ring-shaped magnetic layer with a total thickness of 100 μm in the magnetic leakage coating area of ​​the outer shell. Figure 1 As shown.

[0030] Step 4: Use a dedicated magnetizing fixture to radially magnetize the film. The magnetization direction is as follows: Figure 3 As shown, it points towards the center of the air gap and is opposite to the direction of leakage magnetic flux.

[0031] Step 5: Ensure that the annular magnetic layer inside the outer shell matches the area with severe magnetic leakage to achieve a magnetic focusing effect.

[0032] To verify the technical effect of the present invention, a two-dimensional finite element model of an aviation TO-5 electromagnetic relay was established using AnsysMaxwell electromagnetic simulation software, and a comparative analysis was conducted with the traditional structure without a magnetic ring.

[0033] like Figure 2 As shown, without the magnetic thin film structure, the magnetic lines of force at the edge of the working air gap exhibit a distinct outward convex shape, indicating that a severe "edge effect" occurs at the edge of the air gap. A large amount of leakage magnetic flux is dispersed into the surrounding air and fails to effectively participate in the armature's attraction, resulting in low magnetic energy utilization.

[0034] like Figure 3 As shown, after a radially magnetized NdFeB magnetic ring was placed on the outer wall of the air gap, the distribution of magnetic field lines changed significantly. Under the action of the reverse magnetic field generated by the magnetic thin film, the magnetic field lines that originally diverged outward at the edge of the air gap were significantly compressed laterally, changing from a convex shape to a straight or even slightly concave shape. This indicates that the "magnetic barrier" constructed by the magnetic thin film effectively suppressed the escape of leakage magnetic flux at the edge, forcing the magnetic flux to contract and concentrate through the working air gap region, thereby significantly improving the effective magnetic flux density at the air gap and the electromagnetic attraction force of the relay.

[0035] like Figure 5The comparison of the suction force data shows that, under the same coil ampere-turns excitation, the relay using the structure of this invention exhibits superior electromagnetic suction force across the entire stroke range compared to the conventional structure. Data shows that at the initial engagement position, the suction force increases from approximately 15.1N to 17.2N; at the engagement endpoint, the suction force increases from approximately 19.0N to 21.2N. Comprehensive calculations indicate that this invention improves the dynamic suction force of the relay by an average of over 10%, significantly enhancing the product's sensitivity and contact reliability.

Claims

1. A method for preparing a low-leakage magnetic flux TO-5 relay magnetic housing based on a sidewall-deposited magnetic thin film, characterized in that... The method includes the following steps: Step 1: Locating the leakage magnetic field area: Collect relay magnetic circuit data, establish a relay magnetic circuit simulation model, and determine the projection position of the area with the most severe leakage magnetic field during the engagement of the yoke and armature on the relay housing through AnsysMaxwell finite element analysis. Step 2, Masking: A precision mask is placed on the inner wall of the relay housing to be processed to cover the non-coated areas and expose only the leakage magnetic coating area corresponding to the area with the most severe leakage magnetic field. Step 3, Thin Film Deposition: Using magnetron sputtering technology, a magnetically concentrated thin film is deposited in the magnetic leakage coating area; Step 4, Directional Magnetization: The magnetic film is biased and magnetized using a magnetization fixture. The magnetization direction of the biased magnetization is opposite to the direction of the leakage flux vector at that location. Step 5, Housing Inspection: Measure the thickness of the magnetic film and ensure that its position is aligned with the area of ​​most severe magnetic leakage between the relay yoke and armature.

2. The method for preparing the low-leakage magnetic flux TO-5 relay magnetic housing based on sidewall deposition of a magnetically concentrated thin film according to claim 1, characterized in that... The main material of the magnetic thin film is rare earth permanent magnet material.

3. The method for preparing the low-leakage magnetic flux TO-5 relay magnetic housing based on sidewall deposition of a magnetically concentrated thin film according to claim 2, characterized in that... The rare earth permanent magnet material is a neodymium iron boron or samarium cobalt rare earth permanent magnet alloy.

4. The method for preparing a low-leakage magnetic flux TO-5 relay magnetic housing based on a sidewall-deposited magnetic thin film according to claim 1 or 2, characterized in that... The thickness of the magnetically concentrated film is 10~200μm.

5. The method for preparing a low-leakage magnetic flux TO-5 relay magnetic housing based on a sidewall-deposited magnetic thin film according to claim 1 or 2, characterized in that... The magnetically concentrated film has an annular strip structure, distributed along the inner sidewall of the shell, and its height covers the integrity area where the air gap leakage magnetic field is severe.

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