Airtight Terminal

Abstract

A hermetic terminal according to the present disclosure includes: a tubular metal sleeve; a ceramic board which is fixed to an inner circumferential surface of the metal sleeve, and which has a through-hole in an axial direction of the metal sleeve; and a columnar conductive member which is inserted into the through-hole, and which is joined to the ceramic board by means of a brazing material. The through-hole has a first opening portion and a second opening portion each of which opens in an inverted frustoconical shape from either end in the axial direction. A metallized layer is deposited over the entire inner circumferential surface of the through-hole in the ceramic board.

Description

[Technical field]

[0001] The present disclosure relates to a hermetic terminal. [Background technology]

[0002] Conventionally, in vacuum pumps such as turbomolecular pumps, airtight terminals are used to supply electrical signals from the outside of the vacuum pump to the inside, which is a vacuum space. Such airtight terminals generally include a cylindrical metal sleeve, a disk-shaped insulating base having a through hole in the axial direction and brazed to the inner peripheral surface of the metal sleeve, and a lead pin (conductive member) having a washer (annular member) fixed in the through hole.

[0003] For example, Patent Document 1 describes an airtight terminal in which a metal layer (metallized layer) is formed on the periphery of a through hole in an insulating base and on the inner surface of the through hole to a depth of 200 μm to 5 mm from the opening of the through hole. A washer and a lead pin are fixed to this metal layer by brazing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-16620 Summary of the Invention [Means for solving the problem]

[0005] The hermetic terminal according to the present disclosure includes a cylindrical metal sleeve, a ceramic substrate fixed to the inner peripheral surface of the metal sleeve and having a through hole along the axial direction of the metal sleeve, and a columnar conductive member inserted into the through hole and joined to the ceramic substrate by a brazing material. The through hole has a first opening and a second opening that open in an inverted frustum shape from both ends in the axial direction. A metallized layer is applied over the entire inner peripheral surface of the through hole in the ceramic substrate. The vacuum pump according to the present disclosure includes this hermetic terminal. [Brief description of the drawings]

[0006] [Figure 1] FIG. 2 is a plan view showing a hermetic terminal according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is an explanatory diagram for illustrating a cross section taken along line XX shown in FIG. [Diagram 3] 3 is an enlarged explanatory view for explaining a region Y shown in FIG. 2. FIG. [Figure 4] 3 is an enlarged explanatory view for explaining another embodiment of the region Y shown in FIG. 2.

[0023] FIG. [Diagram 5] 3 is an enlarged explanatory view for explaining another embodiment of the region Y shown in FIG. 2.

[0023] FIG. [Figure 6] 3 is an enlarged explanatory view for explaining another embodiment of the region Y shown in FIG. 2.

[0023] FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] As described above, when a relatively thick insulating base having a thickness of more than 5 mm is used, the end of the metal layer formed on the inner peripheral surface of the through hole of the insulating base is located inside the through hole. If the end of the metal layer is located inside the through hole, there is a risk that a crack will occur from the tip of the metal part toward the insulating base made of ceramic when an unavoidable force is applied.

[0008] The object of the present disclosure is to provide an airtight terminal that can reduce the occurrence of cracks extending from the tip of a metallized layer toward a ceramic substrate even when unavoidable forces are applied from the outside, and can maintain airtightness for a long period of time.

[0009] As described above, in the hermetic terminal according to the present disclosure, the metallized layer is applied over the entire inner circumferential surface of the through hole of the ceramic substrate, which faces the conductive member. With this structure, the end of the metallized layer is not positioned inside the through hole. Therefore, with the hermetic terminal according to the present disclosure, even if an unavoidable force is applied from the outside, it is possible to reduce the occurrence of cracks extending from the tip of the metallized layer toward the ceramic substrate, and it is possible to maintain hermeticity for a long period of time.

[0010] A hermetic terminal according to one embodiment of the present disclosure will be described with reference to Figures 1 to 3. The hermetic terminal 1 according to one embodiment shown in Figure 1 includes a metal sleeve 2, a ceramic substrate 3, and a conductive member 4. Figure 1 is a plan view showing the hermetic terminal 1 according to one embodiment.

[0011] The metal sleeve 2 has a tubular shape, and the shape is not limited, and may be a cylindrical shape or a rectangular shape (e.g., a triangular shape, a square shape, a pentagonal shape, a hexagonal shape, etc.) as long as it is a cylindrical shape. The size of the metal sleeve 2 may be appropriately set according to the device equipped with the airtight terminal 1. The length of the metal sleeve 2 is, for example, 15 mm or more and 30 mm or less, and the outer diameter is 20 mm or more and 30 mm or less. In the case of a rectangular tube shape, the outer diameter means the length of the longest outer edge. The metal sleeve 2 is formed of a metal such as carbon steel, low alloy steel, tool steel, stainless steel, iron, copper, copper alloy, titanium, titanium alloy, molybdenum, molybdenum alloy, Fe-Ni alloy, Fe-Ni-Cr-Ti-Al alloy, Fe-Cr-Al alloy, Fe-Co-Cr alloy, Fe-Co-based alloy, Fe-Co-C-based alloy, Fe-Ni-based alloy, or Fe-Ni-Co-based alloy.

[0012] Carbon steel is an alloy of Fe and 0.02 to 2.14 mass% C, and contains Si, Mn, P, and S in addition to C. Examples of such carbon steel include S10C, S12C, S15C, S17C, S20C, S22C, S25C, S28C, S30C, S33C, S35C, S38C, S40C, S43C, S45C, S48C, S50C, S53C, S55C, S58C, S60C, S65C, S70C, and S75C, which are specified in JIS G 4051:2016.

[0013] Low alloy steel refers to carbon steel that contains at least one of Al, B, Co, Cr, Cu, La, Mo, Nb, Ni, Pb, Se, Te, Ti, V, W, and Zr, and the total content of these elements is 5 mass% or less.

[0014] Tool steel refers to carbon tool steel as specified in JIS G 4401:2009 and alloy tool steel as specified in JIS G 4404:2006.

[0015] Stainless steel is an alloy of Fe and 10.5 mass% or more of Cr with a C content of 1.2% or less, and other components are specified, for example, in ISO 15510: 2014. Examples of stainless steel include SUS304, SUS304L, SUS304ULC, SUS310ULC, and SUSXM15J1.

[0016] The ceramic substrate 3 is a member for fixing the conductive member 4, which will be described later, inside the metal sleeve 2. As shown in Figs. 1 and 2, the ceramic substrate 3 is fixed between the outer peripheral surface of the ceramic substrate 3 and the inner wall surface of the metal sleeve 2. That is, the ceramic substrate 3 is formed according to the inner diameter of the metal sleeve 2. The thickness of the ceramic substrate 3 may be any thickness that allows the conductive member 4 to be fixed, and is, for example, 4 mm or more and 10 mm or less. Fig. 2 is an explanatory diagram for explaining a cross section when cut along the XX line shown in Fig. 1.

[0017] There are no limitations on the ceramic substrate 3 as long as it is made of ceramics. Examples of such ceramics include ceramics containing aluminum oxide, aluminum nitride, silicon carbide, or silicon nitride as a main component.

[0018] In this specification, the term "main component" refers to a component that occupies 80% by mass or more of the total 100% by mass of the components that make up the ceramic. Each component contained in the ceramic can be identified by an X-ray diffraction device using CuKα radiation, and the content of each component can be determined, for example, by an ICP (Inductively Coupled Plasma) emission spectrometer or a fluorescent X-ray analyzer.

[0019] The ceramic substrate 3 has a through hole 31 along the axial direction of the metal sleeve 2. The through hole 31 is a through hole for inserting the conductive member 4, and the diameter of the through hole 31 is set appropriately depending on the outer diameter of the conductive member 4. It is sufficient that at least one through hole 31 is formed in the ceramic substrate 3, and the diameter is set appropriately depending on the number of conductive members 4 to be inserted.

[0020] As shown in Fig. 2, an annular member 5 is positioned on the surface of the ceramic substrate 3. The annular member 5 corresponds to a washer, and is formed of a metal such as carbon steel, low alloy steel, tool steel, stainless steel, iron, copper, copper alloy, titanium, titanium alloy, molybdenum, molybdenum alloy, Fe-Ni alloy, Fe-Ni-Cr-Ti-Al alloy, Fe-Cr-Al alloy, Fe-Co-Cr alloy, Fe-Co based alloy, Fe-Co-C based alloy, Fe-Ni based alloy, or Fe-Ni-Co based alloy. The definitions of carbon steel, low alloy steel, tool steel, and stainless steel are as described above.

[0021] There are no limitations on the size of the annular member 5 as long as it is smaller than the width and thickness of the ceramic substrate 3 and has a size that allows the conductive member 4 to be inserted therein. Regarding the size of the annular member 5, for example, the outer diameter of the annular member 5 is about 1.2 to 2 times, and particularly preferably 1.4 to 1.8 times, the outer diameter of the conductive member 4. The thickness is about 0.1 mm to 0.5 mm.

[0022] The annular member 5 is a member used as needed, and has a second through hole located coaxially with the through hole 31 formed in the ceramic substrate 3. The second through hole is a through hole for inserting the conductive member 4, and the diameter of the second through hole is set appropriately depending on the outer diameter of the conductive member 4. The annular member 5 may be located on one surface or both surfaces of the ceramic substrate 3, as shown in FIG.

[0023] The conductive member 4 corresponds to a lead pin, and the shape is not limited as long as it has a columnar shape such as a cylindrical shape or a rectangular columnar shape (e.g., a triangular columnar shape, a rectangular columnar shape, a pentagonal columnar shape, a hexagonal columnar shape, etc.). The length and the outer diameter of the conductive member 4 are appropriately set according to, for example, the size of the metal sleeve 2. The conductive member 4 is formed of a metal such as copper, for example, oxygen-free copper (e.g., alloy number C1020 specified in JIS H 3100:2012 or alloy number C1011 specified in JIS H 3510:2012). At least one conductive member 4 may be included, and may be appropriately set according to the use of the airtight terminal 1, etc.

[0024] The conductive member 4 is inserted into a through hole 31 formed in the ceramic substrate 3 and a second through hole formed in the annular member 5, and is fixed to the ceramic substrate 3. Specifically, the conductive member 4 is brazed to the surface of the ceramic substrate 3 using a brazing material 6 so as to cover the annular member 5. Examples of the brazing material 6 include BAg-8, BAg-8A, BAg-8B, and BAg-9.

[0025] In the airtight terminal 1, the through hole 31 formed in the ceramic substrate 3 is covered over the entire inner circumferential surface with a metallized layer 32 as shown in Fig. 3. Fig. 3 is an enlarged explanatory view for explaining region Y shown in Fig. 2. In this manner, by covering the entire inner circumferential surface of the through hole 31 formed in the ceramic substrate 3 with the metallized layer 32, the occurrence of cracks extending from the tip of the metallized layer 32 toward the ceramic substrate 3 is suppressed even if an unavoidable force is applied from the outside. As a result, airtightness can be maintained for a long period of time.

[0026] The metal forming the metallization layer 32 is not limited, and examples thereof include a Mo-Mn alloy and an Ag-Cu-Ti alloy. The metallization layer 32 may have a thickness of, for example, 15 μm or more and 45 μm or less. When the metallization layer 3 is formed of a Mo-Mn alloy, the metallization layer 32 may be covered with a Ni plating layer to suppress oxidation of Mo. The thickness of the Ni plating layer is, for example, 3 μm or more and 10 μm or less.

[0027] The metallized layer 32 may be thicker in the center of the axial direction than at both ends of the through hole 31 in the axial direction. For example, within the above thickness range, the center of the through hole 31 may be thicker than at both ends. Both ends in the axial direction refer to the vicinity of the first opening 31a and the vicinity of the second opening 31b. Stress is likely to occur in the ceramic substrate 3 near both ends. In order to reduce the stress applied to the ceramic substrate 3, it is preferable to make the metallized layer 32 at both ends thin. On the other hand, the center of the axial direction is less susceptible to the influence of the brazing material 6 expanding and contracting in the vertical direction due to repeated heating and cooling. As a result, even if cracks occur in the metallized layer 32 or the ceramic substrate 3 due to repeated heating and cooling, the progression of the cracks can be suppressed.

[0028] 3, the metallized layer 32 may extend to the periphery of at least one of the first opening 31a and the second opening 31b of the ceramic substrate 3. Even if an unavoidable force is applied from the outside, the occurrence of cracks extending from the tip of the metallized layer 32 toward the ceramic substrate 3 is suppressed. As a result, airtightness can be maintained for a long period of time.

[0029] The through hole 31 has a first opening 31a and a second opening 31b that open in an inverted frustum shape from both ends in the axial direction. When the first opening 31a and the second opening 31b have a shape that opens in an inverted frustum shape, the stress of the ceramic substrate 3 near the first opening 31a and the second opening 31b is dispersed more than when the ceramic substrate 3 has a shape other than an inverted frustum shape (for example, an inverted cone shape or an inverted pyramid shape). As a result, even if the ceramic substrate 3 is repeatedly heated and cooled, cracks and the like are less likely to occur, and the ceramic substrate 3 can be used for a long period of time. The inverted frustum shape can be an inverted truncated cone shape, an inverted truncated pyramid shape, or the like, depending on the shape of the conductive member 4 (the shape of the first through hole 3a). As shown in FIG. 1, when the conductive member 4 is cylindrical, the inverted frustum shape is an inverted truncated cone shape.

[0030] In the through hole 31 formed in the ceramic substrate 3, the first opening 31a and the second opening 31b are preferably symmetrical with respect to an imaginary plane that is perpendicular to the axial direction of the through hole 31 and passes through the center of the thickness of the ceramic substrate 3. This configuration suppresses uneven distribution of stress in the thickness direction (axial direction) of the ceramic substrate 3. As a result, cracks and the like are less likely to occur in the ceramic substrate 3, allowing it to be used for a long period of time.

[0031] The brazing material 6 located between the through hole 31 formed in the ceramic substrate 3 and the conductive member 4 may have a long void in the thickness direction of the ceramic substrate 3. The presence of such a void reduces residual stress even when heating and cooling are repeated. At least one tip side of the void may have a convex curved surface. When at least one tip side of the void has a convex curved surface, stress concentration is suppressed at the tip on the convex curved surface side. As a result, the occurrence of cracks from the tip on the convex curved surface side is suppressed.

[0032] 2 and 3, the annular member 5 may be covered from the top surface to the side surfaces with a brazing material 6. When the annular member 5 is covered with the brazing material, the conductive member 4 is less likely to come off even if a high pressure is applied to the annular member 5 from the outside.

[0033] 3, the brazing material 6 may form a fillet from above the upper surface of the annular member 5 toward the outside of the outer circumferential surface of the annular member 5. By forming a fillet with the brazing material 6, the contact area of ​​the brazing material 6 with the ceramic substrate 3, the conductive member 4, and the annular member 5 can be increased. When the ceramic substrate 3 is provided with an extending metallized layer 32 and a plating layer (not shown) that covers the metallized layer 32, the contact area of ​​the brazing material 6 with the plating layer can be increased in place of the ceramic substrate 3. As a result, peeling is less likely to occur even when a force pulling outward is applied, and the product can be used for a long period of time.

[0034] A hermetic terminal 40 according to another embodiment of the present disclosure will be described with reference to FIG. 4. A configuration different from the first embodiment will be described. As shown in FIG. 4, the cross-sectional contour of the brazing material 6 may have concave surfaces 7a, 7b. Since the brazing material 6 has the concave surfaces 7a, 7b, the volume of the brazing material 6 can be reduced compared to a case where the concave surfaces 7a, 7b are not present. This reduces the stress applied to the ceramic substrate 3, and particularly suppresses the occurrence of cracks in the ceramic substrate 3. In particular, since the brazing material 6 has the concave surface 7a, the stress applied to the ceramic substrate 3 is reduced.

[0035] A convex surface 8 is formed at the boundary between the concave surfaces 7a and 7b. The apex of the convex surface 8 may be close to the intersection line between the upper surface and the outer circumferential surface of the annular member 5. When the apex of the convex surface 8 is close to the intersection line between the upper surface and the outer circumferential surface of the annular member 5, the thickness of the brazing material is thin in the area close to the convex surface 8. This reduces the stress applied to the ceramic substrate 3, making it possible to particularly suppress the occurrence of cracks in the ceramic substrate 3.

[0036] The average radius of curvature of the convex surface 8 may be 60 μm or more and 190 μm or less. When the average radius of curvature of the convex surface 8 is 60 μm or more and 190 μm or less, the bonding strength of the conductive member 4 to the ceramic substrate 3 is improved, and when a plurality of conductive members 4 are arranged along the axial direction of the metal sleeve 2, it is possible to prevent adjacent conductive members 4 from being short-circuited by the brazing material 6. Here, if the conductive member 4 is cylindrical, the convex surface 8 will be annular and will surround the conductive member 4.

[0037] The average radius of curvature of the convex surface 8 can be measured using a shape analysis laser microscope (Keyence Corporation, ultra-deep color 3D shape measuring microscope (VK-X1100 or its successor model)). The measurement conditions are set as follows: the illumination method is coaxial, the magnification is 120x, and the measurement range including the convex surface 8 is, for example, 2792 μm × 2093 μm per location, and profile measurement can be performed.

[0038] Specifically, first, in one measurement range, four lines to be measured are drawn from the conductive member 4 side toward the ceramic substrate 3 side so as to include the convex surface 8. The length of each line is, for example, 200 μm or more and 300 μm or less. At least three measurement ranges are set, and at least 12 lines are to be measured. The average value of the measured values ​​obtained from the 12 lines to be measured is regarded as the average radius of curvature of the convex surface 8.

[0039] An airtight terminal 50 according to another embodiment of the present disclosure will be described with reference to FIG. 5. A configuration different from the first embodiment will be described. As shown in FIG. 5, a part of the annular member 5 may be located inside the first opening 31a of the ceramic substrate 3. That is, the lower surface of the annular member 5 may be located at a distance D in the axial direction of the first through hole 31 from the surface of the ceramic substrate 3 toward the first opening 31a. With the structure as shown in FIG. 5, the volume of the brazing material 6 in the first through hole 31 is reduced by the annular member 5. Therefore, the stress applied to the ceramic substrate 3 adjacent to the first through hole 31 is reduced, and the occurrence of cracks in the ceramic substrate 3 can be particularly suppressed.

[0040] A hermetic terminal 60 according to another embodiment of the present disclosure will be described with reference to FIG. 6. A configuration different from the first embodiment will be described. As shown in FIG. 6, the distance between the outer peripheral surface of the conductive member 4 and the inner peripheral surface of the annular member 5 may not be uniform. In FIG. 6, the distance between the outer peripheral surface of the conductive member 4 and the inner peripheral surface of the annular member 5 is W1 on the left side of the paper and W2 on the right side of the paper, where W1>W2. It is preferable to have such a structure. The reason for this is presumed to be as follows. When W1 is larger than W2, the volume of the brazing material 6 between the first region 51 and the conductive member 4 increases in the region on the left side of the paper. When W1 is larger than W2, the distance between the intersection line between the upper surface and the outer peripheral surface of the annular member 5 and the convex surface 8 can be reduced in the region on the left side of the paper.

[0041] On the other hand, in the region on the right side of the page, the volume of the brazing material 6 between the first region 51 and the conductive member 4 increases. In the region on the right side of the page, the volume of the brazing material 6 between the first region 51 and the conductive member 4 decreases. By distributing the brazing material 6 non-uniformly in this manner, localized stress concentration in a portion of the first opening 31a of the ceramic substrate 3 is suppressed. As a result, the occurrence of cracks in the ceramic substrate 3 can be particularly suppressed.

[0042] When the surface of the ceramic substrate 3 is provided with an extending metallized layer 32 surrounding the conductive member 4, and a plating layer covering the metallized layer 32, the average value of the cut level difference Rδc1 representing the difference between the cut level at a load length ratio of 25% on the roughness curve of the surface of the plating layer and the cut level at a load length ratio of 75% on the roughness curve may be greater than the average value of the cut level difference Rδc2 representing the difference between the cut level at a load length ratio of 25% on the roughness curve of the exposed portion of the surface of the ceramic substrate 3 and the cut level at a load length ratio of 75% on the roughness curve.

[0043] When the average value of the cut level difference Rδc1 is larger than the average value of the cut level difference Rδc2, the anchor effect of the brazed portion is increased, and the bonding strength of the brazed portion to the plating layer can be increased. In this case, the average value of the cut level difference Rδc2 is smaller than the average value of the cut level difference Rδc1, so that gaps are less likely to occur between the surface of the ceramic substrate 3 and the extended metallized layer 32, improving the adhesion of the extended metallized layer 32 to the ceramic substrate 3. Furthermore, the variation in thickness of the extended metallized layer 32 is also suppressed.

[0044] The cut level differences Rδc1 and Rδc2 can be measured using a shape analysis laser microscope (Keyence Corporation, ultra-deep color 3D shape measuring microscope (VK-X1100 or its successor model)). The measurement conditions are as follows: coaxial lighting, 60x magnification, no cutoff value λs, 0.8mm cutoff value λf, no cutoff value λf, and end effect correction.

[0045] The measurement is performed on the surface of the plating layer around the conductive member 4 and on the exposed portion of the surface of the ceramic substrate 3, and the measurement range per location is, for example, 5657 μm × 4232 m. When the cut level difference Rδc1 is obtained, a circumference C1 to be measured is drawn on the surface of the plating layer, with the axis of the conductive member 4 as the center. The length of one circumference is, for example, 6.2 mm or more and 6.6 mm or less. When the cut level difference Rδc2 is obtained, a circumference C2 is drawn on the same axis as the circumference C1 on the exposed portion of the surface of the ceramic substrate 3. The length of one circumference is, for example, 7.8 mm or more and 8.3 mm or less. The measured values ​​of the cut level differences Rδc1 and Rδc2 are obtained so that the number of the measured values ​​is the same as the number of the conductive members 4, and the average values ​​of the measured values ​​are calculated. When there is one conductive member 4, the measured value of the cut level difference Rδc1 and the measured value of the cut level difference Rδc2 can be compared.

[0046] For example, the average value of the cut level difference Rδc1 is 4 μm or more and 7 μm or less, and the average value of the cut level difference Rδc2 is 1 μm or more and 2 μm or less. In particular, it is preferable that the difference between the average value of the cut level difference Rδc1 and the average value of the cut level difference Rδc2 is 2 μm or more and 5 μm or less.

[0047] The airtight terminal 1 according to one embodiment is manufactured, for example, by the following procedure. First, the metal sleeve 2 is prepared. Next, the ceramic substrate 3 is fixed to the inner peripheral surface of the metal sleeve 2. The inner peripheral surface of the through hole 31 formed in the ceramic substrate 3 is metallized over the entire surface in advance, and a metallized layer 32 is formed. The metallization is performed, for example, by a molybdenum-manganese method (Mo-Mn method) or the like. Next, the annular member 5 is placed on the ceramic substrate 3 so that the through hole 31 formed in the ceramic substrate 3 and the second through hole formed in the annular member 5 overlap. Next, the conductive member 4 is inserted into the through hole 31 and the second through hole, and the ceramic substrate 3, the conductive member 4, and the annular member 5 are fixed with the brazing material 6 so as to cover the annular member 5 from the top surface to the side surface. The mass of the brazing material 6 and the brazing temperature can be adjusted to control the shape of the fillet. In this manner, the airtight terminal 1 according to one embodiment is obtained.

[0048] Alternatively, the conductive member 4 and the annular member 5 may be fixed to the ceramic substrate 3 with the brazing material 6 in advance, and then the ceramic substrate 3 may be fixed to the inner peripheral surface of the metal sleeve 2 .

[0049] A method for manufacturing an airtight terminal 40 according to another embodiment having the recesses 7a, 7b and the protrusions 8 shown in FIG. 4 will be described. First, a metal sleeve 2 is prepared. Next, a ceramic substrate 3 is fixed to the inner peripheral surface of the metal sleeve 2. Separately, a brazing material 6 is coated on the annular member 5 in advance. The annular member 5 coated with the brazing material 6 can be produced, for example, by applying a paste consisting of a fine powder of the brazing material 6 and an organic solvent or the like to the entire periphery of the annular member 5, i.e., the upper surface, the lower surface, the inner peripheral surface, and the outer peripheral surface, and then heating and cooling the paste. The annular member 5 is placed on the ceramic substrate 3 so that the first through hole 31 formed in the ceramic substrate 3 and the second through hole (which is coated with the brazing material 6 in advance) formed in the annular member 5 overlap with each other. Next, a conductive member 4 is inserted into the first through hole 3a and the second through hole, and the ceramic substrate 3, the conductive member 4, and the annular member 5 are fixed with the brazing material 6 so as to cover the annular member 5. In this manner, an airtight terminal 40 according to another embodiment is obtained.

[0050] A method for manufacturing an airtight terminal 50 according to another embodiment in which a part of the annular member 5 is located inside the first opening 3a' of the ceramic substrate 3 shown in Fig. 5 will be described. To manufacture an airtight terminal 50 in which a part of the annular member 5 is located inside the first opening 31a of the ceramic substrate 3, the annular member 5 is placed such that the lower surface of the annular member 5 is positioned at a distance D in the axial direction of the first through hole 31 from the surface of the ceramic substrate 3 toward the first opening 31a, and then the annular member 5 is fixed. In this manner, the airtight terminal 50 according to another embodiment is obtained.

[0051] 6, the airtight terminal 60 in which the distances W1 and W2 are different can be manufactured as follows. In a first manufacturing method, the annular member 5 is placed on the ceramic substrate 3, and the conductive member 4 is inserted so that the gap between the conductive member 4 and the annular member 5 is not uniform. Then, the annular member 4 and the conductive member 5 are fixed with a brazing material 6.

[0052] That is, in the first manufacturing method, first, the metal sleeve 2 is prepared. Next, the ceramic substrate 3 is fixed to the inner peripheral surface of the metal sleeve 2. The annular member 5 is placed on the ceramic substrate 3 so that the first through hole 31 formed in the ceramic substrate 3 and the second through hole formed in the annular member 5 overlap. Next, the conductive member 4 is inserted into the first through hole 3a and the second through hole so that the gap between the conductive member 4 and the annular member 5 is not uniform. After that, the annular member 4 and the conductive member 5 are fixed with a brazing material 6.

[0053] In the second manufacturing method, the axial direction is tilted at 10 to 30 degrees with respect to gravity before fixing the brazing material 6. Then, while maintaining the tilted state, the brazing material is heated to melt, and further cooled to solidify the brazing material 6.

[0054] That is, in the second manufacturing method, first, the metal sleeve 2 is prepared. Then, the ceramic substrate 3 is fixed to the inner peripheral surface of the metal sleeve 2. The annular member 5 is placed on the ceramic substrate 3 so that the first through hole 3a formed in the ceramic substrate 3 and the second through hole formed in the annular member 5 overlap. Then, the conductive member 4 is inserted into the first through hole 3a and the second through hole. Before fixing with the brazing material 6, the ceramic substrate 3 is tilted so that the axial direction of the annular member 5 is inclined by 10 to 30 degrees with respect to the vertical direction. Then, while maintaining the inclined state of the annular member 5 and the ceramic substrate 3, the brazing material 6 is heated and then cooled, and the conductive member 4 and the annular member 5 are fixed. In this manner, the airtight terminal 60 according to another embodiment is obtained.

[0055] In order to make the average value of the cutting level differences R.DELTA.c1 greater than the average value of the cutting level differences R.DELTA.c2, the upper surface of the ceramic substrate 3 may be ground or polished in advance.

[0056] The airtight terminal 1 according to one embodiment is used in various devices, such as a vacuum pump, a plasma processing device such as a plasma film forming device, a plasma etching device, or a plasma ashing device. [Explanation of symbols]

[0057] 1, 40, 50, 60 Airtight Terminal 2 Metal sleeve 3. Ceramic Substrate 31 Through hole 31a 1st opening 31b 2nd opening 32 Metallization layer 4 Conductive materials 5 Annular member 6 Brazing material

Claims

1. A cylindrical metal sleeve; a ceramic substrate fixed to an inner peripheral surface of the metal sleeve and having a through hole along an axial direction of the metal sleeve; a columnar conductive member inserted into the through hole and joined to the ceramic substrate by a brazing material; Including, The through hole has a first opening and a second opening that open in an inverted frustum shape from both ends in the axial direction, A metallized layer is applied over the entire inner circumferential surface of the through hole, an annular member is disposed on at least one surface side of the ceramic substrate so as to surround the conductive member, and the entire annular member is covered with the brazing material; The brazing material forms a fillet from above the upper surface of the annular member toward the outside of the outer circumferential surface of the annular member, The fillet has a convex surface at least on a side closer to the ceramic substrate, and the mean radius of curvature of the convex surface is 60 μm or more and 190 μm or less. Airtight terminal.

2. The hermetic terminal according to claim 1 , wherein the first opening and the second opening are symmetrical with respect to an imaginary plane that is perpendicular to an axial direction of the through hole and passes through a center of a thickness of the ceramic substrate.

3. The hermetic terminal according to claim 1 , wherein the metallization layer is thicker in a central portion in the axial direction than at both ends in the axial direction.

4. The hermetic terminal according to claim 1 , wherein the brazing material located between the through hole and the conductive member has a gap that is long in a thickness direction of the ceramic substrate.

5. The hermetic terminal according to claim 4 , wherein at least one end of the gap portion has a convex curved surface.

6. The hermetic terminal according to claim 1 , wherein the metallization layer extends to a peripheral edge of at least one of the first opening and the second opening.

7. The hermetic terminal according to claim 1 , wherein a portion of the annular member is located inside the first opening.

8. a metallized layer and a plating layer covering the metallized layer are provided on a surface of the ceramic substrate so as to surround the conductive member; 2. The hermetic terminal according to claim 1, wherein an average value of a cut level difference Rδc1 representing a difference between a cut level at a load length ratio of 25% on a roughness curve of the surface of the plating layer and a cut level at a load length ratio of 75% on the roughness curve is greater than an average value of a cut level difference Rδc2 representing a difference between a cut level at a load length ratio of 25% on a roughness curve of an exposed portion of the surface of the ceramic substrate and a cut level at a load length ratio of 75% on the roughness curve.

9. A vacuum pump comprising the airtight terminal according to any one of claims 1 to 8.

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