Hermetic terminal

Abstract

The air-tight terminal of the present disclosure includes a first conductive member in a columnar or cylindrical shape; a first insulating member having a through-hole in which a portion of the first conductive member is located inside, disposed along the axial direction of the first conductive member; a first annular member located on the outer peripheral surface of the first conductive member; a second conductive member in a cylindrical shape located outside the first insulating member; and an insulating layer located at the opposing portions of the first insulating member and the first conductive member. The first insulating member includes a first annular insulating portion and a second annular insulating portion having a larger outer diameter than the first annular insulating portion. The first annular insulating portion is located at least on one side in the axial direction of the second annular insulating portion. The first annular member is engaged with the end surface of the first annular insulating portion, and the second conductive member is engaged with the outer peripheral surface of the second annular insulating portion. The insulating layer includes a first insulating layer located at the opposing portions of the first annular insulating portion and the first conductive member, and a second insulating layer located at the opposing portions of the second annular insulating portion and the first conductive member. The radial thickness of the first insulating layer is smaller than the radial thickness of the second insulating layer.

Description

Technical Field

[0001] This disclosure relates to hermetic terminals used in vacuum equipment, nuclear energy equipment, and equipment operating at extremely low temperatures in the presence of liquid hydrogen (e.g., flow meters for cryogenic liquids). Background Technology

[0002] Conventionally, as a hermetically sealed terminal, there is known, for example, an insulating coaxial vacuum terminal as described in Patent Document 1, which includes: a metal rod-shaped pin; a first ceramic cylindrical body having a through hole for insertion of the pin; a first metal cylindrical body fitted around the outer periphery of the first ceramic cylindrical body; a second ceramic cylindrical body fitted around the outer periphery of the first metal cylindrical body; and a second metal cylindrical body fitted around the outer periphery of the second ceramic cylindrical body.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Publication No. 55-2065 Summary of the Invention

[0006] Methods for solving problems

[0007] The airtight terminal disclosed herein comprises: a columnar or cylindrical first conductive member; a first insulating member having a through hole for a portion of the first conductive member to be located inside, and disposed along the axial direction of the first conductive member; a first annular member located on the outer peripheral surface of the first conductive member; a cylindrical second conductive member located on the outer periphery of the first insulating member; and an insulating layer located on the opposing portion of the first insulating member and the first conductive member. The first insulating member includes a first annular insulating portion and a second annular insulating portion with an outer diameter larger than the first annular insulating portion. The first annular insulating portion is located at least on one axial side of the second annular insulating portion. The first annular member engages with the end face of the first annular insulating portion, and the second conductive member engages with the outer peripheral surface of the second annular insulating portion. The insulating layer includes a first insulating layer located on the opposing portion of the first annular insulating portion and the first conductive member, and a second insulating layer located on the opposing portion of the second annular insulating portion and the first conductive member. The radial thickness of the first insulating layer is smaller than the radial thickness of the second insulating layer. Attached Figure Description

[0008] Figure 1 This is a cross-sectional view showing an airtight terminal according to an embodiment of the present disclosure.

[0009] Figure 2A yes Figure 1 An enlarged cross-sectional view of part A of the airtight terminal shown.

[0010] Figure 2B It does not have Figure 2A A partially enlarged cross-sectional view of the hermetic terminal of the first insulating layer shown.

[0011] Figure 3 It means Figure 1 A cross-sectional view of another embodiment of the airtight terminal shown.

[0012] Figure 4 It means Figure 1 A cross-sectional view of another embodiment of the airtight terminal shown.

[0013] Figure 5 This is a cross-sectional view showing an airtight terminal according to another embodiment of the present disclosure.

[0014] Figure 6 This is a cross-sectional view showing an airtight terminal according to another embodiment of the present disclosure. Detailed Implementation

[0015] The conventional hermetic terminals described in Patent Document 1 suffer from poor high-frequency signal transmission characteristics due to the lack of impedance matching, particularly above the GHz band. Here, impedance matching refers to adjusting the output impedance R of the circuit that supplies the output voltage. OUT The input impedance R of the circuit (load side) to which the input voltage is applied. IN The values ​​are the same. By making the output impedance R... OUT With input impedance R IN Similarly, this allows the circuit to transmit the maximum power of the output voltage, improving the transmission characteristics of high-frequency signals. Therefore, it is necessary to seek airtight terminals with good transmission characteristics for high-frequency signals, especially those above the GHz band.

[0016] The hermetic terminal of this disclosure, by having the configuration described above, improves insulation by ensuring the creepage distance between the first and second conducting members, and facilitates impedance matching above GHz, resulting in better signal transmission characteristics in the high-frequency band. Furthermore, the hermetic terminal of this disclosure also ensures high hermeticity.

[0017] Hereinafter, the airtight terminal of this disclosure will be described based on the accompanying drawings. However, the drawings referred to below are simplified representations of embodiments of this disclosure for ease of explanation. Therefore, the airtight terminal disclosed below can include any constituent members not shown in the referenced drawings. In addition, the dimensions of the members in the drawings do not faithfully represent the actual dimensions of the constituent members or the dimensional ratios of each member.

[0018] Figure 1 This is a schematic cross-sectional view showing the airtight terminal of this embodiment. (e.g.) Figure 1As shown, the airtight terminal of this embodiment includes: a columnar first conductive member 1; a first insulating member 3 having a through hole 2 in which a portion of the first conductive member 1 is located; a first annular member 4 located on the outer peripheral surface of the first conductive member 1; and a cylindrical second conductive member 5 located on the outer periphery of the first insulating member 3. Cylindrical bodies 6a and 6b are respectively engaged at the two axial end faces of the second conductive member 5. Cylindrical bodies 6a and 6b are components for mating with coaxial connectors such as SMA connectors, N connectors, and BNC connectors. Cylindrical bodies 6a and 6b can have the same structure or different structures. By providing such cylindrical bodies 6a and 6b, it is easy to engage with connectors standardized to industrial specifications. That is, cylindrical bodies 6a and 6b are not limited to simple cylindrical bodies, but can have any structure, as long as they are capable of engaging with standardized connectors.

[0019] In this embodiment, the hermetic terminal is a coaxial terminal (hereinafter sometimes referred to as a high-frequency coaxial terminal). The first conductive member 1 functions as an inner conductor, and the second conductive member 5 functions as an outer conductor. The conductor on the inner side of the coaxial line is called the inner conductor, and the conductor on the outer side is called the outer conductor. The inner conductor is also called the internal conductor, and the outer conductor is also called the external conductor. It should be noted that the first conductive member 1 can also be cylindrical. A cylindrical first conductive member 1 contributes to the weight reduction of the hermetic terminal; the larger the hermetic terminal, the greater the contribution. The first conductive member 1 is inserted through the through hole 2.

[0020] The first insulating member 3 has a convex shape including a first annular insulating portion 31 (hereinafter, sometimes referred to as the first insulating portion 31) and a second annular insulating portion 32 (hereinafter, sometimes referred to as the second insulating portion 32) with an outer diameter larger than the first insulating portion 31. The first insulating portion 31 and the second insulating portion 32 are arranged along the axial direction of the first conductive member 1. The first insulating portion 31 and the second insulating portion 32 can be formed integrally or separately, or there can be a gap between the first insulating portion 31 and the second insulating portion 32. However, the gap needs to be set to a size that does not affect the transmission characteristics (hereinafter, sometimes referred to as RF (radio frequency) characteristics) of the signal in the high-frequency band of the coaxial terminal. Not affecting the RF characteristics means that the VSWR (Voltage Standing Wave Ratio) is ≤3 in the high-frequency characteristics. The VSWR is set to ≤3 because even if the signal strength is attenuated, it is equivalent to the output signal strength being more than half of the input signal strength. The target value of VSWR can be appropriately changed according to the required characteristics.

[0021] The first annular member 4 can be, for example, a flange portion disposed on the outer peripheral surface of the first conductive member 1, or it can be a washer located on the outer peripheral surface. To ensure the airtightness of the airtight terminal, the end face of the first annular member 4 and the first insulating portion 31 are continuously and without gaps joined in the circumferential direction of the first annular member 4. The outer peripheral surface of the second conductive member 5 and the second insulating portion 32 are continuously and without gaps joined in the circumferential direction of the second conductive member 5. "Without gaps" means meeting the airtightness requirements, such as those in a helium leak test (JIS Z2331:2006).

[0022] The first conductive component 1, the first annular component 4, and the second conductive component 5 include, for example, iron-nickel-cobalt alloys, Fe-Ni alloys, Fe-Ni-Cr-Ti-Al alloys, Fe-Co-Cr alloys, Fe-Cr-Al alloys, Ti, Ti alloys, and Mo, Cu, Cu alloys, etc.

[0023] The first insulating component 3, for example, comprises a ceramic with alumina as its main component. The main component in the ceramic refers to a component comprising 85% or more of the total 100% by mass of the components constituting the ceramic. In addition to alumina as the main component, the ceramic may also contain at least one of silicon, calcium, and magnesium as oxides. After identifying the crystal phase of the main component using X-ray diffraction (XRD), the content of the metal element constituting the main component is determined using X-ray fluorescence (XRF) or intraluminescence immunoassay (ICP), and then converted into the content of the main component.

[0024] The end face of the first insulating portion 31, which contains ceramic, is joined to the first annular member 4 via a first joint 71. Furthermore, the outer peripheral surface of the second insulating portion 32, which also contains ceramic, is joined to the second conductive member 5 via a second joint 72. The second joint 72 is formed continuously in the circumferential direction over the entire outer peripheral surface of the second insulating portion 32 while ensuring airtightness. However, the second joint 72 may also be formed continuously in the circumferential direction on a portion of the outer peripheral surface. For example, a brazed portion can be considered as the first joint 71 and the second joint 72.

[0025] like Figure 2A As shown, brazing can be performed using brazing filler metal 10 via metal layers 9a and 9b located on the first insulating portion 31 side and the second insulating portion 32 side. This ensures airtightness. Metal layers 9a and 9b comprise metallization layers located on the first insulating portion 31 side and the second insulating portion 32 side, and a coating layer located on the metallization layers.

[0026] Figure 2A yes Figure 1 An enlarged view of part A in the diagram, schematically showing the first joint 71 and the second joint 72. (See diagram for reference.) Figure 2AAs shown, the first joint 71 is joined to the first annular member 4 via a metal layer 9a located on the side of the first insulating portion 31 by solder 10. The second joint 72 is also joined to the second conductive member 5 via a metal layer 9b located on the side of the second insulating portion 32 by solder 10.

[0027] The metallization layers constituting metal layers 9a and 9b are primarily composed of molybdenum and contain manganese. The coating layer, used to reduce oxidation of the metallization layers, is primarily composed of nickel, copper, or a copper-nickel alloy, and may also contain phosphorus or boron. The thickness of the metallization layer can be, for example, 10 μm or more and 50 μm or less, and the thickness of the coating layer can be, for example, 1 μm or more and 10 μm or less.

[0028] The main component in a coating refers to the component comprising 88% or more of the total 100% by mass of the components constituting the coating. In the case of a coating with a copper-nickel alloy as the main component, the total content of copper and nickel is the content of the main component. The content of the elements constituting the main component in the coating is determined using X-ray fluorescence (XRF) or intraluminescence immunoassay (ICP) spectrophotometry, and then converted into the content of the main component.

[0029] Brazing can be performed using brazing filler metals 10, such as BAg-8, BAg-8A, and BAg-8B, which are primarily composed of silver. The primary component of brazing filler metal 10 refers to a component comprising at least 60% by mass out of a total of 100% by mass of its constituent elements. The elemental composition of brazing filler metal 10 can be determined using X-ray fluorescence (XRF) or intraluminescence immunoassay (ICP). In this disclosure, brazing filler metal 10 refers to the brazing filler metal defined in JIS Z 3001-3:2008 (ISO 857-2:2005 (MOD)).

[0030] Alternatively, the end face of the first insulating portion 31 containing ceramic can be joined to the first annular member 4 using a solder containing active metal instead of the aforementioned solder 10. The outer peripheral surface of the second insulating portion 32 containing ceramic can also be joined to the second conductive member 5 using a solder containing active metal instead of the aforementioned solder 10. Thus, joining can be performed without the inclusion of metal layers 9a and 9b.

[0031] In this case, the solder 10 used contains, for example, 20% to 40% by mass of copper, 1% to 3% by mass of an active metal, 1.2% to 6% by mass of tin or indium, with the remainder being Ag. Examples of active metals include at least one selected from titanium, zirconium, hafnium, and niobium.

[0032] like Figure 1As shown, in the hermetic terminal of this embodiment, the insulating layer 8 is located at the portion opposite to the first insulating portion 31 and the first conductive member 1. The insulating layer 8 includes a first insulating layer 8a and a second insulating layer 8b. The radial thickness of the first insulating layer 8a is smaller than the radial thickness of the second insulating layer 8b. That is, the outer diameter of the portion opposite to the first insulating portion 31 of the first conductive member 1 is larger than the outer diameter of the portion opposite to the second insulating portion 32.

[0033] That is, the characteristic impedance of the portion where the first insulating member 3 is located is determined by the ratio of the outer diameter of the first conducting member 1 to the inner diameter of the second conducting member 5, and the thickness and relative permittivity of the insulating members (first insulating member 3, first insulating layer 8a and second insulating layer 8b, and insulating layer (vacuum, gas, resin, etc.)) located between the outer peripheral surface of the first conducting member 1 and the inner peripheral surface of the second conducting member 5. Here, the radial thicknesses of the first insulating portion 31 and the second insulating portion 32 are different. Therefore, impedance matching can be achieved by adjusting the thicknesses of the first insulating layer 8a and the second insulating layer 8b.

[0034] The end of the second insulating layer 8b can be located at the same position as the end of the opposing first insulating member 3, or, within limits that do not affect the RF characteristics (VSWR≤3), it can be located closer to the first insulating member 3 than that end. Thus, the first conductive member 1 must be in contact with the first insulating member 3 within the through hole 2, thereby ensuring the surface distance and maintaining the insulation of the hermetic terminal.

[0035] It should be noted that even if the outer diameter of the first conductive member 1 is changed instead of the inner diameter of the first insulating member 3 being larger than the outer diameter of the first conductive member 1, and the inner diameter of the first insulating part 31 being smaller than the inner diameter of the second insulating part 32, the first insulating layer 8a and the second insulating layer 8b can still be formed.

[0036] Examples of materials that can be used as the first insulating layer 8a and the second insulating layer 8b include vacuum, gas, or resin, which have a lower relative permittivity than the first insulating member 3. Examples of gases include air, oxygen, nitrogen, hydrogen, helium, and sulfur hexafluoride. Examples of resins include epoxy resin, silicone resin, polyurethane resin, fluoropolymer (Teflon, etc.), and liquid crystal polymer.

[0037] The first insulating member 3 has a convex shape including a first insulating portion 31 and a second insulating portion 32, and is engaged with the first conductive member 1 and the second conductive member 5 through the first engaging portion 71 and the second engaging portion 72. Therefore, as Figure 2A As shown, the shortest distance separating the first conductive member 1 and the second conductive member 5 along the surface of the first insulating member 3, i.e., the surface distance, becomes longer due to the convex shape of the first insulating member 3.

[0038] That is, the starting point of the surface distance on the side of the first conductive member 1 is the end L1 of the metal layer 9a that is electrically connected to the first conductive member 1 via the solder 10, closest to the end of the second conductive member 5. The starting point of the surface distance on the side of the second conductive member 5 is the end L2 of the second conductive member 5 that is closest to the first conductive member 1, where the second conductive member 5 contacts the second insulating portion 32. The case where end L2 is closest to the side of the first conductive member 1 refers to the case where the end of the surface of the first insulating portion 31 side of the second insulating portion 32 contacts the inner peripheral surface of the second conductive member 5, regardless of the position of the second joint 72. Therefore, compared to the surface distance (L11-L21) when the first insulating member 3 does not have a convex shape, the length from end L1 to the surface of the second insulating portion 32 (end L2) becomes longer when it has a convex shape, ensuring a longer surface distance. This ensures the insulation required for the hermetic terminal.

[0039] When the first insulating layer 8a is in a vacuum or gas state, a gap is formed beneath the first insulating portion 31 through the first insulating layer 8a. Therefore, as Figure 2A As shown, in the first joint 71, welds 11 and 12 are formed at both ends of the brazing filler metal 10 after the end face of the first insulating part 31 is brazed to the first annular member 4. In particular, at the lower part of the brazing filler metal 10, a weld 12 with a stable shape is formed through the gap of the first insulating layer 8a. When the first insulating layer 8a is resin, the weld 12 is formed because resin is filled after brazing.

[0040] on the other hand, Figure 2B This is a partially enlarged cross-sectional view showing a hermetically sealed terminal without the first insulating layer 8a. Figure 2B In this figure, the conductive member 100 and the insulating member 130 are in close contact (it should be noted that, for ease of illustration, they are depicted with a gap between them). Therefore, the solder 10 is immersed in and accumulates between the conductive member 100 and the insulating member 130. As a result, the insulating member 130 may crack due to localized stress concentration caused by the expansion of the solder 10, etc.

[0041] In contrast, as in this embodiment, when there is a gap between the first insulating portion 31 and the first conductive member 1 through the first insulating layer 8a, a weld 12 is formed between the first insulating portion 31 and the first conductive member 1. As a result, the solder 10 does not accumulate, and the insulating member 130 does not crack due to localized stress concentration. Furthermore, in Figure 2B In the hermetic terminal shown, strict dimensional control is required to ensure a tight fit between the conductive member 100 and the insulating member 130. However, as... Figure 2A As shown, with the first insulating layer 8a (gap), strict dimensional control is not required, and therefore manufacturing is easy.

[0042] like Figure 1 As shown, the second conductive member 5 includes a first cylindrical portion 51 and a second cylindrical portion 52. The inner diameter of the first cylindrical portion 51 is larger than the inner diameter of the second cylindrical portion 52, and the first cylindrical portion 51 is joined to the outer peripheral surface of the second insulating portion 32 via a second joint portion 72. That is, the inner diameter of the second cylindrical portion 52 is smaller than the outer diameter of the second insulating portion 32, which is the maximum outer diameter of the first insulating member 3, thus forming a step.

[0043] Therefore, in the transmission characteristics of signals in the high-frequency band of the high-frequency coaxial terminal, which serves as a hermetically sealed terminal, the characteristic impedance can be matched relative to the difference between the dielectric constant of the first insulating member 3 and the dielectric constant of the space portion (in gas or vacuum). Characteristic impedance matching means that the value of the characteristic impedance is within a range that does not affect the RF characteristics (VSWR≤3), as described above. Furthermore, the second cylindrical portion 52 of the second conducting member 5 does not necessarily need to be in contact with the first insulating member 3, and can be separated within a range that does not affect the RF characteristics (VSWR≤3).

[0044] The first insulating member 3, which has a convex shape, can also have a curved corner R on its surface within a range that does not affect the RF characteristics (VSWR≤3). This makes the fabrication of the first insulating member 3 easier and reduces the stress concentration of external forces and thermal stress at the corner R.

[0045] To investigate the optimal value of the average radius of curvature of the corner R, simulation can be performed. For example, simulations can be conducted using Altair's "Fedo" software, analyzing the VSWR (Voltage Standing Wave Ratio) relative to frequency using the FEM (Finite Element Method). The value of the radius of curvature of the corner R can be determined in a manner that achieves impedance matching without affecting the RF characteristics.

[0046] Figure 3 express Figure 1 Another embodiment of the illustrated implementation. In Figure 3 In this drawing, components that are identical to those in the above embodiments are labeled with the same reference numerals, and detailed descriptions are omitted. For example... Figure 3 As shown, in addition to the first cylindrical portion 51 and the second cylindrical portion 52, the second conductive member 5 also includes a third cylindrical portion 53 located between the first cylindrical portion 51 and the second cylindrical portion 52. The inner diameter of the third cylindrical portion 53 is smaller than the inner diameter of the first cylindrical portion 51, and the inner diameter of the second cylindrical portion 52 is smaller than the inner diameter of the third cylindrical portion 53.

[0047] Therefore, the radial length ratio of the end face of the second insulating portion 32 in the first insulating member 3 that connects with the gap formed by the third cylindrical portion 53 is in Figure 1The end face of the second insulating portion 32 shown is longer than the radial length h of the gap formed by the second cylindrical portion 52. In other words, the radial length of the end face of the second insulating portion 32 in contact with the second conductive member 5 is longer than the radial length of the gap formed by the second cylindrical portion 52. Figure 1 In the illustrated embodiment, the radial length h of the end face of the second insulating portion 32 that connects to the second conducting member 5 is shorter than the end face length. As a result, in the RF characteristics of the high-frequency coaxial terminal, the surface distance of the first insulating member 3 can be extended while achieving characteristic impedance matching, thus improving the insulation of the hermetic terminal. Other aspects are similar to... Figure 1 The implementation methods shown are the same.

[0048] The voids can be, for example, vacuum or gases (e.g., air, oxygen, nitrogen, hydrogen, helium, and sulfur hexafluoride) with a relative permittivity lower than that of the first insulating member 3. Alternatively, the voids can be filled with resin (e.g., epoxy resin, silicone resin, polyurethane resin, fluoropolymer (Teflon, a registered trademark), and liquid crystal polymers). The voids or the resin replacing the voids can also be made of the same material as the first insulating layer 8a and the second insulating layer 8b. If the same material is used, the manufacturing process becomes easier, and it is also effective from a manufacturing cost perspective.

[0049] Furthermore, to investigate the optimal value of the depth d of the third cylindrical section 53, a simulation similar to the one described above can be performed. Using an Altair-manufactured "Fedo" simulator, the VSWR (Voltage Standing Wave Ratio) relative to frequency can be analyzed using FEM (Finite Element Method). The value of depth d can be determined in a manner that does not affect RF characteristics and ensures characteristic impedance matching. However, to ensure insulation between the end face of the second insulating section 32 and the second cylindrical section 52 separated by the gap, the minimum value of depth d should be set to 0.1 mm or more.

[0050] Figure 4 express Figure 1 Another embodiment of the illustrated implementation. In Figure 4 In this drawing, components that are identical to those in the above embodiments are labeled with the same reference numerals, and detailed descriptions are omitted. For example... Figure 4 As shown, the second conductive member 5 includes a fourth cylindrical portion 54 in addition to the first cylindrical portion 51 and the second cylindrical portion 52. The fourth cylindrical portion 54 is located axially in a position where the first insulating member 3 is not provided. The inner diameter D of the fourth cylindrical portion 54 is... 41 The ratio of the outer diameter D4 of the first conductive member 1 opposite to the fourth cylindrical section 54 to the outer diameter D4 is D4 / D. 41 The inner diameter D of the second cylindrical section 52 is equal to 21 The ratio of the outer diameter D2 of the first conductive member 1 opposite to the second cylindrical section 52 to the outer diameter D2 is D2 / D. 21 However, as mentioned above, the ratio of D4 / D...41 and D2 / D 21 It can also differ within a range that does not affect RF characteristics. Other than... Figure 1 The implementation methods shown are the same.

[0051] Thus, in another embodiment, even if the dielectric constant of the first insulating member 3 differs from that of the space portion in the RF characteristics of the high-frequency coaxial terminal, impedance matching can be maintained at each location of the first cylindrical portion 51, the second cylindrical portion 52, and the fourth cylindrical portion 54. As a result, RF characteristics can be improved.

[0052] The fourth cylindrical portion 54 can be made of the same or different conductive material as the second conductive member 5. Different conductive materials can be combinations of different conductive materials listed above as being made of the material of the second conductive member 5, or materials such as SUS. The conductive material can be selected in a manner that does not affect the RF characteristics. Therefore, the fourth cylindrical portion 54 can be integrally formed with the second conductive member 5, or it can be formed separately from the second conductive member 5. As described above, a gap can exist between it and the second conductive member 5 within the range that does not affect the RF characteristics.

[0053] When the fourth cylindrical portion 54 is integrally formed with the second conductive member 5, the first cylindrical portion 51, the second cylindrical portion 52, and the fourth cylindrical portion 54 integrally formed with the second conductive member 5 can also be axially separated and joined by brazing or the like. It should be noted that, in Figure 4 In another embodiment shown, a method without having Figure 3 The third cylindrical portion 53 shown is an airtight terminal, but of course, it may also have a third cylindrical portion 53.

[0054] Figure 5 This refers to a hermetic terminal representing another embodiment of the present invention. For example... Figure 5 As shown, the first insulating member 30 of the airtight terminal has a shape in which the first insulating portions 310a and 310b are located on both sides of the second insulating portion 320, that is, it has a shape with protrusions on both sides.

[0055] The first insulating portions 310a and 310b and the second insulating portion 320 have through holes 20 for a portion of the first conductive member 18 to be located inside, and are arranged along the axial direction of the first conductive member 18. In addition, the first conductive member 18 has two first annular members 4a and 4b located on its outer peripheral surface, and these first annular members 4a and 4b are respectively joined to the end faces of the first insulating portions 310a and 310b by brazing or the like.

[0056] Additionally, the cylindrical second conductive member 50 is located on the outer periphery of the first insulating member 30 and engages with the outer peripheral surface of the second insulating portion 320. The insulating layer 80 is located at the opposing portions of the first insulating member 30 and the first conductive member 18. The insulating layer 80 includes first insulating layers 80a and 80b at the opposing portions of the first insulating portions 310a and 310b and the first conductive member 18, and includes a second insulating layer 80c at the opposing portion of the second insulating portion 320 and the first conductive member 18. The radial thickness of the first insulating layers 80a and 80b is smaller than that of the second insulating layer 80c.

[0057] The rest is the same as the above-described embodiments, so detailed descriptions are omitted. It should be noted that the size and shape of the first insulating portions 310a and 310b do not need to be the same, and their size and shape can also be different.

[0058] Figure 6 This describes an airtight terminal according to another embodiment of the present invention. Figure 6 In this drawing, components that are identical to those in the above embodiments are labeled with the same reference numerals, and detailed descriptions are omitted. For example... Figure 6 As shown, the airtight terminal of this embodiment has a triple coaxial structure. This triple coaxial structure includes, on the outer peripheral surface of the second conductive member 5: an annular second insulating member 14 having a gap 13, with at least a portion of the second conductive member 5 located in the gap 13; and a third conductive member 15 located on the outer periphery of the second insulating member 14. Cylindrical connector portions 17a and 17b for engaging with other components (not shown) are respectively installed at both ends of the third conductive member 15.

[0059] On the outer periphery of the second conducting member 5, a third conducting member 15, insulated from the second conducting member 5 by the second insulating member 14, is provided such that it at least covers the entire area of ​​the second conducting member 5. Therefore, the influence of external electromagnetic waves on the signal transmitted by the first conducting member 1 and the second conducting member 5 can be eliminated, reducing the noise level of the transmitted signal. That is, the third conducting member 15 functions as a shielding member, thus covering the entire length of the first insulating member 3 and the second insulating member 14 (the axial direction of the first conducting member 1). Furthermore, since the third conducting member 15 functions as a shielding member, its shape is not particularly limited, regardless of the RF characteristics of the high-frequency coaxial terminal; for example, it can also be a cylindrical shape with a polygonal cross-section.

[0060] The third conductive member 15 can be made of the same or different conductive material as the first conductive member 1 and the second conductive member 5. Different conductive materials can be combinations of conductive materials listed below that of the second conductive member 5, or materials such as SUS. The conductive material can be selected in a way that does not affect the RF characteristics.

[0061] The second insulating member 14 is respectively joined to the outer peripheral surface of the second conductive member 5 and the inner peripheral surface of the third conductive member 15. The joint positions of the outer peripheral surface of the first insulating member 3 and the inner peripheral surface of the second conductive member 5 and the joint positions of the outer peripheral surface of the second conductive member 5 and the inner peripheral surface of the second insulating member 14 are axially offset and do not overlap with each other (i.e., the second joint 72 and the third joint 73 described later). As a result, during the brazing of the hermetic terminal or in high-temperature and low-temperature (including extremely low-temperature) operating environments, the stress applied to the second conductive member 5 can be reduced from becoming excessive, which is effective in reducing cracking.

[0062] Specifically, the second annular member 16 is located on the outer peripheral surface of the second conductive member 5. The outer peripheral surface of the first insulating member 3 and the inner peripheral surface of the second conductive member 5 are joined by the second joint 72, and the plane of the second annular member 16 opposite to the second insulating member 14 and the end face of the second insulating member 14 opposite to the plane of the second annular member 16 are joined by the third joint 73. In this way, the surfaces joined by the second joint 72 are orthogonal to the surfaces joined by the third joint 73. As a result, the stress applied to the second joint 72 and the third joint 73 can be further reduced.

[0063] The second annular member 16 may be formed by a flange portion disposed on the outer peripheral surface of the second conductive member 5, or it may be formed by a washer located on the outer peripheral surface. The inner peripheral surface of the third conductive member 15 is joined to the outer peripheral surface of the second insulating member 14 through the fourth joint portion 74.

[0064] The third joint 73 can be formed by the aforementioned brazing or the like. That is, the plane of the second annular member 16 and the end face of the second insulating member 14 are joined by brazing filler metal, such as... Figure 1 and Figure 2A As explained, a weld is formed, and the brazing filler metal also flows on the outer peripheral surface of the second conductive member 5. For this purpose, it is preferable to form a gap 13 between the outer peripheral surface of the second conductive member 5 and the second insulating member 14. Alternatively, the gap can be formed by at least partially increasing the inner diameter of the second insulating member 14 or at least partially decreasing the outer diameter of the second conductive member 5.

[0065] The first insulating member 3 and the second insulating member 14 are preferably located at a position where at least a portion of them overlap each other in the radial direction. This allows for a reduction in the axial length of the first conductive member 1 of the hermetic terminal, contributing to the miniaturization of the hermetic terminal.

[0066] The embodiments of the present disclosure have been described above. However, the invention of the present disclosure is not limited to the embodiments described above, and various modifications and improvements can be made within the scope of the present disclosure shown in (1) to (10) below.

[0067] (1) The airtight terminal of this disclosure comprises: a columnar or cylindrical first conductive member; a first insulating member having a through hole for a portion of the first conductive member to be located inside, and disposed along the axial direction of the first conductive member; a first annular member located on the outer peripheral surface of the first conductive member; a cylindrical second conductive member located on the outer periphery of the first insulating member; and an insulating layer located on the opposing portion of the first insulating member and the first conductive member. The first insulating member includes a first annular insulating portion and a second annular insulating portion with an outer diameter larger than the first annular insulating portion. The first annular insulating portion is located at least on one side of the second annular insulating portion in the axial direction. The first annular member is engaged with the end face of the first annular insulating portion, and the second conductive member is engaged with the outer peripheral surface of the second annular insulating portion. The insulating layer includes a first insulating layer located on the opposing portion of the first annular insulating portion and the first conductive member, and a second insulating layer located on the opposing portion of the second annular insulating portion and the first conductive member. The radial thickness of the first insulating layer is smaller than the radial thickness of the second insulating layer.

[0068] (2) Based on the airtight terminal described in (1) above, the first insulating layer and the second insulating layer are vacuum, gas or resin.

[0069] (3) Based on the airtight terminal described in (1) or (2) above, the second conductive member includes a first cylindrical portion and a second cylindrical portion. The inner diameter of the first cylindrical portion is larger than the inner diameter of the second cylindrical portion, and the first cylindrical portion is joined to the outer peripheral surface of the second annular insulating portion.

[0070] (4) Based on the airtight terminal described in (3) above, the second conductive member includes a first cylindrical portion, a second cylindrical portion, and a third cylindrical portion located between the first cylindrical portion and the second cylindrical portion. The inner diameter of the third cylindrical portion is smaller than the inner diameter of the first cylindrical portion, and the inner diameter of the second cylindrical portion is smaller than the inner diameter of the third cylindrical portion.

[0071] (5) Based on the airtight terminal described in (3) or (4) above, the second conductive member has a fourth cylindrical portion, which is located at a position where the first insulating member is not provided.

[0072] (6) Based on the airtight terminal described in (5) above, the inner diameter D of the fourth cylindrical section 41 The ratio of the outer diameter D4 of the first conductive member opposite the fourth cylindrical section to the outer diameter D4 is D4 / D 41 Equal to the inner diameter D of the second cylinder 21 The ratio of the outer diameter D2 of the first conductive member opposite the second cylindrical section to the outer diameter D2 is D2 / D 21 .

[0073] (7) Based on the airtight terminal of any one of (1) to (6) above, the outer peripheral surface of the second conductive member is provided with: an annular second insulating member having a through hole, at least a portion of the second conductive member being located in the through hole; and a third conductive member being located on the outer periphery of the second insulating member.

[0074] (8) Based on the airtight terminal described in (7) above, the second insulating member is respectively joined to the outer peripheral surface of the second conductive member and the inner peripheral surface of the third conductive member. The joint position between the outer peripheral surface of the first insulating member and the inner peripheral surface of the second conductive member and the joint position between the second conductive member and the second insulating member do not overlap in the axial direction.

[0075] (9) Based on the airtight terminal described in (7) or (8) above, the second annular member is located on the outer peripheral surface of the second conductive member. The outer peripheral surface of the first insulating member is joined to the inner peripheral surface of the second conductive member, and the second annular member is joined to the end face of the second insulating member.

[0076] (10) Based on the airtight terminal described in (8) or (9) above, the first insulating member and the second insulating member are located at a position where at least a portion of them overlap each other in the radial direction.

[0077] Explanation of reference numerals in the attached figures:

[0078] 1.18 First Conducting Component

[0079] 2. 20 Through Holes

[0080] 3 First insulating component

[0081] 31, 310a, 310b First Insulation Part (First Annular Insulation Part)

[0082] 32, 320 Second Insulation Section (Second Annular Insulation Section)

[0083] 4, 4a, 4b First annular component

[0084] 5 Second Conducting Component

[0085] 51 First tube section

[0086] 52 Second cylinder section

[0087] 53 Third tube section

[0088] 54 Fourth cylindrical section

[0089] 6a, 6b cylinders

[0090] 71 First joint

[0091] 72 Second joint

[0092] 73 Third joint

[0093] 74 Fourth joint

[0094] 8. Insulation layer

[0095] 8a, 80a, 80b First Insulation Layer

[0096] 8b, 80c Second Insulation Layer

[0097] 9a and 9b metal layers

[0098] 10. Brazing filler metal

[0099] Welds 11 and 12

[0100] 13 gaps

[0101] 14 Second insulating component

[0102] 15 Third Conductor

[0103] 16 Second ring-shaped component

[0104] 17 Connector Section

[0105] 100 Conductive component

[0106] 130 Insulating components.

Claims

1. An airtight terminal, wherein, The airtight terminal includes: A columnar or cylindrical first conductive component; A first insulating member has a through hole in which a portion of the first conductive member is located, and is disposed along the axial direction of the first conductive member; The first annular member is located on the outer peripheral surface of the first conductive member; A cylindrical second conductive member is located on the outer periphery of the first insulating member; as well as An insulating layer is located on the portion opposite the first insulating member and the first conductive member. The first insulating member includes a first annular insulating portion and a second annular insulating portion with an outer diameter larger than the first annular insulating portion. The first annular insulating portion is located at least on one side of the second annular insulating portion along the axial direction. The first annular member engages with the end face of the first annular insulating portion. The second conductive member engages with the outer peripheral surface of the second annular insulating portion. The insulating layer includes: A first insulating layer is located at the portion opposite to the first annular insulating portion and the first conductive member; as well as The second insulating layer is located at the portion opposite to the second annular insulating portion and the first conductive member. The radial thickness of the first insulating layer is smaller than the radial thickness of the second insulating layer.

2. The airtight terminal according to claim 1, wherein, The first insulating layer and the second insulating layer are vacuum, gas or resin.

3. The airtight terminal according to claim 1 or 2, wherein, The second conductive member includes a first cylindrical portion and a second cylindrical portion, wherein the inner diameter of the first cylindrical portion is larger than the inner diameter of the second cylindrical portion, and the first cylindrical portion is engaged with the outer peripheral surface of the second annular insulating portion.

4. The airtight terminal according to claim 3, wherein, The second conductive member includes a first cylindrical portion, a second cylindrical portion, and a third cylindrical portion located between the first cylindrical portion and the second cylindrical portion. The inner diameter of the third cylindrical portion is smaller than the inner diameter of the first cylindrical portion, and the inner diameter of the second cylindrical portion is smaller than the inner diameter of the third cylindrical portion.

5. The airtight terminal according to claim 3 or 4, wherein, The second conductive member has a fourth cylindrical portion located at a position where the first insulating member is not provided.

6. The airtight terminal according to claim 5, wherein, The inner diameter D of the fourth cylindrical section 41 The ratio of the outer diameter D4 of the first conductive member opposite the fourth cylindrical portion to the outer diameter D4 is D4 / D 41 Equal to the inner diameter D of the second cylindrical section 21 The ratio of the outer diameter D2 of the first conductive member opposite the second cylindrical portion to the outer diameter D2 is D2 / D 21 .

7. The airtight terminal according to any one of claims 1 to 6, wherein, The outer peripheral surface of the second conductive member has: An annular second insulating member having a through hole, at least a portion of the second conductive member being located in the through hole; and The third conductive member is located on the outer periphery of the second insulating member.

8. The airtight terminal according to claim 7, wherein, The second insulating member is respectively joined to the outer peripheral surface of the second conductive member and the inner peripheral surface of the third conductive member. The engagement positions of the outer peripheral surface of the first insulating member and the inner peripheral surface of the second conductive member, and the engagement positions of the second conductive member and the second insulating member, do not overlap in the axial direction.

9. The airtight terminal according to claim 7 or 8, wherein, The second annular member is located on the outer peripheral surface of the second conductive member. The outer peripheral surface of the first insulating member is engaged with the inner peripheral surface of the second conductive member. The second annular member engages with the end face of the second insulating member.

10. The airtight terminal according to claim 8 or 9, wherein, The first insulating member and the second insulating member are located at a position where at least a portion of them overlap each other in the radial direction.

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