High-precision getter heater and preparation method thereof

Abstract

The invention relates to the field of electric vacuum component manufacturing, and discloses a high-precision getter heater and a preparation method thereof.The preparation method comprises the following steps that (1) a refractory metal sheet is selected as a base material, and the refractory metal sheet is processed into a metal pattern capable of being electrically heated through an etching method; 2) performing electrophoresis on the surface of the metal pattern which can be electrically heated to form an insulating layer; and 3) performing high-temperature ceramic forming on the insulating layer. The method has the advantages that expensive and complex tools and tedious procedures of annealing, wire winding, shaping and the like are not needed, the production cost is saved, and the benefits are obvious on occasions of multiple varieties and small batches; the size and the shape of the heater can be accurately controlled, and the heater is suitable for production of thin-wall getters; by adjusting the width of the refractory metal after etching, different intensities and temperatures can be realized in different areas of the same heater, the defects of poor contact, breakage and the like can be avoided, and the reliability of the heater is improved.

Description

Technical Field

[0001] The invention belongs to the field of electric vacuum component manufacturing, and particularly relates to a high-precision getter heater and a preparation method thereof. Background Art

[0002] Preparations or devices used to obtain, maintain vacuum, and purify gases, etc., which can effectively adsorb certain (types of) gas molecules are generally called getters.

[0003] Non-evaporable getters are generally formed by pressing or sintering powders of zirconium, titanium, yttrium or binary or multi-element alloys composed of zirconium, titanium, yttrium or vanadium, iron, manganese, cobalt, aluminum, molybdenum, and rare earth. Before the non-evaporable getters work, they must be heated and activated. Due to certain limitations, some devices can only have a thermal subassembly made of a heating wire coated with an insulating layer buried inside.

[0004] Heaters are generally made of refractory metal wire. First, the purchased refractory metal wire needs to be annealed in a hydrogen furnace to make it easy to bend and form. Then the refractory metal wire is wound on a tooling of a specific shape, which is generally also made of refractory metal. During winding, due to the poor plasticity of refractory metal, it is difficult to wind with a small radius of curvature, otherwise it is easy to crack. Subsequently, the hot wire and the tooling need to be heated to a high temperature in a hydrogen furnace and then cooled to room temperature to remove the stress during winding. Then remove the wound hot wire from the tooling. Due to the residual stress, the removed hot wire will always be deformed in all directions, so it is difficult to accurately control the shape and position tolerance of the hot wire. A layer of insulating material needs to be coated on the surface of the wound hot wire, generally a powder of ceramic materials such as alumina and zirconia. Finally, the insulating layer is high-temperature porcelainized to make it firmly bonded to the heating wire. In order to avoid the hot wires touching each other and short-circuiting, a wire diameter spacing must be left between the hot wires of the getter heater made in this way.

[0005] In recent years, with the development trend of device miniaturization and flattening, the size of getter has become smaller and smaller, and the shape and position tolerance range left for assembly has also become smaller and smaller.

[0006] Some devices use hot wires to fix the getter. To ensure strength, thicker hot wires are required. To avoid using large currents to heat the getter, thinner hot wires are required to obtain greater heating resistance. To resolve this contradiction, the thin hot wire is generally wound around the thick hot wire at the part where the getter is led out. This solution occupies a large volume, which conflicts with the device's requirement for miniaturization of the getter. In addition, the reliability of this solution is not high, and sometimes poor contact failures may occur at the winding position. Summary of the invention

[0007] Aiming at the above-mentioned technical deficiencies, the technical problem to be solved by the present invention is a high-precision getter heater and its preparation method, aiming to improve the shape and position accuracy of the getter heater, avoid using expensive and inefficient shaping tooling, and improve the reliability of the connection of the variable-diameter heating wire.

[0008] To solve the above technical problems, the present invention adopts the following technical solutions: The present invention provides a preparation method for a high-precision getter heater, including the following steps: 1) Select a refractory metal sheet as the base material, and use the etching method to process the refractory metal sheet into a metal pattern capable of being electrically heated; 2) Electrophorese an insulating layer on the surface of the electrically heatable metal pattern; 3) High-temperature sinter the insulating layer to form porcelain.

[0009] Further, the step 1) includes: Coat a photoresist on the surface of the refractory metal sheet; Use a mask to expose the refractory metal sheet coated with photoresist, and transfer the designed heating metal pattern on the mask to the photoresist to generate a shadow area; Develop the exposed refractory metal sheet to remove the unexposed photoresist outside the shadow area, and retain the exposed photoresist in the shadow area, obtaining a refractory metal sheet with hardened photoresist protecting the shadow area; Etch away the part of the refractory metal sheet not protected by the photoresist to obtain a metal pattern capable of being electrically heated.

[0010] Further, the refractory metal sheet is one of tungsten, molybdenum, tungsten-molybdenum alloy, tungsten-rhenium alloy, and molybdenum-rhenium alloy.

[0011] Further, the thickness of the refractory metal sheet is 0.01 mm to 1 mm.

[0012] Further, the insulating material for forming the insulating layer is a ceramic powder with high-temperature stability.

[0013] A high-precision getter heater is prepared by using a preparation method for a high-precision getter heater.

[0014] The beneficial effects of the present invention are as follows: It is not necessary to use expensive, complex tooling and cumbersome processes such as annealing, wire winding, and shaping, saving production costs, and having obvious benefits in the case of small batches of multiple varieties; the size and shape of the heater can be precisely controlled, suitable for the production of thin-wall getters; by adjusting the width of the refractory metal after etching, different strengths and temperatures can be achieved in different regions of the same heater, avoiding defects such as poor contact and fracture, and improving the reliability of the heater. Description of the Drawings

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0016] Figure 1 It is a schematic diagram of step 1 of a method for preparing a high-precision getter heater of the present invention; Figure 2 It is a schematic diagram of large geometric tolerances in the prior art; Figure 3 It is a schematic diagram of the heat wire diameter change in the prior art; Detailed implementation manners

[0017] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

[0018] Embodiment 1

[0019] As Figure 1 shown, this embodiment provides a high-precision getter heater and its preparation method, including the following steps: 1) Uniformly coat a layer of photoresist on the surface of a molybdenum plate with a thickness of 0.2 mm.

[0020] 2) Use a mask to expose the molybdenum plate coated with photoresist, and transfer the designed heating metal pattern on the mask to the photoresist to form Figure 1 parallel units with a shadow area width of 0.2 mm and a gap of 0.1 mm in the figure, and the width at both ends is designed to be 0.6 mm to increase the strength.

[0021] 3) Develop the exposed molybdenum plate to remove the unexposed photoresist outside the shadow area and retain the exposed photoresist in the shadow area to obtain a molybdenum plate with hardened photoresist protecting the shadow area.

[0022] 4) Etch away the part of the molybdenum plate not protected by the photoresist to obtain a metal pattern that can be electrically heated.

[0023] 5) Remove the photoresist on the surface of the metal pattern for electric heating obtained by removing the heat wire, and clean, dry it.

[0024] 6) Apply a layer of alumina powder with a thickness of about 0.15 mm on the clean and dry hot wire surface by electrophoresis.

[0025] 7) Porcelainize the hot wire with an insulating coating in a hydrogen furnace at 1600 °C to obtain a getter heater with high precision.

[0026] Example 2

[0027] As Figure 2 and Figure 3 shown, this example is the second example of the present invention. The difference between this example and the first example is that a verification test for the preparation method of a high-precision getter heater is provided to verify and explain the technical effects adopted in this method.

[0028] In the process of preparing traditional getter heaters, the winding process is usually adopted to form the heating element. This method involves using a fine molybdenum wire (or other refractory metal wires) to wind into a specific shape and fixing its form by high-temperature annealing. However, this traditional method has several significant disadvantages. The specific implementation steps of this example in combination with the prior art are described as follows: 1) Anneal the molybdenum wire with a diameter of 0.2 mm at high temperature in a hydrogen furnace to make it soft.

[0029] 2) Fix one end of the molybdenum wire and repeatedly wind it along the positioning pins on the shaping tool made of molybdenum metal as shown in the left figure, and finally fix the other end on the shaping tool as well. Figure 2 As shown in the partial enlarged view, when the hot wire is wound, the convex part will be stretched and the concave part will be compressed. The winding gap should be at least greater than one wire diameter, otherwise, due to the poor plasticity of the hot wire, local cracking is likely to occur at the convex and concave parts. During subsequent power-on heating, these cracked positions are prone to local overheating and fusing due to increased resistance.

[0030] As Figure 2 shown, when the hot wire is wound, the convex part will be stretched and the concave part will be compressed. The winding gap should be at least greater than one wire diameter, otherwise, due to the poor plasticity of the hot wire, local cracking is likely to occur at the convex and concave parts. During subsequent power-on heating, these cracked positions are prone to local overheating and fusing due to increased resistance.

[0031] 3) Anneal the shaping tool at high temperature in a hydrogen furnace.

[0032] Since each hot wire needs to be shaped at high temperature, a large number of shaping tools are required for mass production. These tools also have to be processed using refractory metals, resulting in high costs and low efficiency. However, since the present invention is formed by etching, these shaping tools are not required, and the processing cycle is short, enabling rapid mass production.

[0033] 4) Remove the shaped hot wire from the shaping tool. As Figure 2 shown, due to the existence of residual stress, the hot wire will more or less rebound, resulting in uneven hot wire gaps and a risk of short circuit due to mutual contact between the wires. However, the present invention is formed by etching and has no stress of processing deformation, which can strictly guarantee the initial shape.

[0034] 5) As Figure 3 shown, a 0.2 mm molybdenum wire is wound around one end of a 0.4 mm molybdenum wire to increase the strength of the getter lead-out part. This winding method occupies a relatively large space and has low reliability. However, in the present invention, by adjusting the width of the lead-out part, the strength of the lead-out part can be conveniently increased, and there is no risk of poor contact.

[0035] 6) A layer of alumina powder with a thickness of about 0.15 mm is coated on the surface of the hot wire by electrophoresis.

[0036] 7) The getter is fired in a hydrogen furnace at 1600 °C to obtain a getter hot wire.

[0037] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or perform equivalent replacements on some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a high-precision getter heater, characterized in that: The following steps are involved: 1) Selecting a refractory metal sheet as a substrate, and processing the refractory metal sheet into a metal pattern that can be electrically heated by etching; 2) electrophoretically forming an insulating layer on the surface of the electrically heatable metal pattern; 3) The insulating layer is formed into porcelain at high temperature.

2. The method for preparing a high-precision getter heater according to claim 1, characterized in that: The step 1) comprises: Applying photoresist on the surface of the refractory metal sheet; Using a mask to expose a refractory metal sheet coated with a photoresist, the heated metal pattern designed on the mask is transferred to the photoresist to produce a shadow area; The exposed refractory metal sheet is subjected to a developing process to remove the unexposed photoresist outside the shadow area and retain the exposed photoresist in the shadow area, thereby obtaining a refractory metal sheet with the shadow area protected by the hardened photoresist; The portion of the refractory metal sheet not protected by the photoresist is removed by etching to obtain a metal pattern that can be electrically heated.

3. The method for preparing a high-precision getter heater according to claim 1, characterized in that: The refractory metal sheet is one of tungsten, molybdenum, tungsten-molybdenum alloy, tungsten-rhenium alloy and molybdenum-rhenium alloy.

4. The method for preparing a high-precision getter heater according to claim 1, characterized in that: The thickness of the refractory metal sheet is 0.01 mm to 1 mm.

5. The method for preparing a high-precision getter heater according to claim 1, characterized in that: The insulating material forming the insulating layer is ceramic powder with high temperature stability.

6. A high-precision getter heater, characterized in that: The high-precision getter heater is prepared by the preparation method of any one of claims 1 to 5.

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