Feedthrough and feedthrough manufacturing method

Abstract

To provide a feedthrough which provides high reliability and reduces optical loss in an optical fiber, and a feedthrough manufacturing method.SOLUTION: A feedthrough includes: a sleeve comprising a sleeve upper part, a sleeve central part, and a sleeve lower part; a guide at least fitted to an inner peripheral surface of the sleeve central part; an optical fiber inserted into a through hole formed inside the sleeve; and a sealant formed between the sleeve upper part and the guide and sealing a part of the optical fiber in a sealing groove communicating with the through hole. The thermal conductivity of the sleeve lower part is lower than that of the sleeve upper part.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a field-through and a method for manufacturing a field-through.

Background Art

[0002] For example, a submarine cable that uses an optical fiber as a transmission line is installed on the seabed several thousand meters deep together with a submarine repeater, and thus is subject to a high water pressure (for example, a water pressure equivalent to a depth of 8000 m). Therefore, for a field-through, which is a connection part for introducing a submarine cable into a submarine repeater, reliability such as pressure resistance, water tightness, and air tightness, and low optical loss of the optical fiber are required.

[0003] Such a field-through has a structure in which a part of the optical fiber inserted between a sleeve and a guide that fits on the inner peripheral surface of the sleeve is hermetically sealed in a sealing groove filled with a sealing material such as solder in the field-through.

[0004] Patent Document 1 discloses an airtight sealing method for an optical fiber in which a plurality of optical fibers introduced into a pressure-resistant housing are hermetically sealed with solder filled in a solder sealing part in a fiber feed-through. In this method, the solder filled in the solder sealing part is melted by heating means (heating coil), and the melted solder is sequentially solidified from the sealing bottom side of the solder sealing part to the sealing upper side of the solder sealing part.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the technology described in Patent Document 1, by cooling the range from the central part of the sleeve (metal sleeve) to the upper part of the sleeve by water cooling or the like, the melted sealing material (solder) is solidified from the sealing bottom side of the solder sealing part, which is a sealing groove, to the sealing upper side of the solder sealing part in sequence. Thus, in the technology described in Patent Document 1, since it is not assumed to cool the lower part of the sleeve of the sleeve, especially when the heating time by the heating means is long or the heating temperature by the heating means is high, the melted sealing material easily flows downward from the sealing groove.

[0007] When the melted sealing material flows out downward from the sealing groove more than necessary, in the field through after the sealing material has solidified, the filling amount of the sealing material filled in the sealing groove may become insufficient, or voids may occur inside the sealing material due to uneven filling of the sealing material, resulting in uneven filling. In this case, there is a problem that the reliability such as the pressure resistance, water tightness, and air tightness of the field through decreases, and the optical loss increases due to the generation of microbends in the optical fiber. The decrease in the reliability of the field through and the increase in the optical loss of the optical fiber lead to a decrease in the reliability of the undersea repeater connected to the undersea cable by the field through.

[0008] An object of the present disclosure is to provide a field through with high reliability and reduced optical loss of an optical fiber, and a method for manufacturing the field through, in view of the above-described problems.

Means for Solving the Problems

[0009] A field through according to an embodiment includes a sleeve including an upper sleeve part, a central sleeve part, and a lower sleeve part, a guide fitted to at least the inner peripheral surface of the central sleeve part, an optical fiber inserted into a through hole formed in the sleeve, and a sealing material that hermetically seals a part of the optical fiber in a sealing groove formed between the upper sleeve part and the guide and communicating with the through hole. The sleeve has lower thermal conductivity of the lower sleeve part than that of the upper sleeve part.

[0010] Further, in the method for manufacturing a field-through according to one embodiment, a part of an optical fiber inserted into a through-hole formed in a sleeve including an upper sleeve portion, a central sleeve portion, and a lower sleeve portion is formed between the upper sleeve portion and a guide fitted to the inner peripheral surfaces of at least the central sleeve portion, and a sealing step of hermetically sealing a sealing groove communicating with the through-hole is provided. The sleeve has lower thermal conductivity in the lower sleeve portion than in the upper sleeve portion.

Effect of the Invention

[0011] According to the present disclosure, it is possible to provide a field-through with high reliability and reduced optical loss of an optical fiber, and a method for manufacturing a field-through.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0013] Hereinafter, this embodiment will be described with reference to the drawings. However, the present disclosure is not limited to the following embodiments. Further, for clarity of explanation, the following description and drawings are appropriately simplified. Furthermore, in the following description, the same or equivalent elements are denoted by the same reference numerals, and redundant descriptions are omitted.

[0014] Embodiment 1 First, a configuration example of the field-through 1 will be described with reference to FIG. 1. FIG. 1 is a diagram showing the field-through according to the present disclosure. Above FIG. 1, a plan view of the field-through 1 is shown. In the center of FIG. 1, an A-A cross-sectional view of the field-through 1 is shown. Below FIG. 1, a bottom view of the field-through 1 is shown. Note that in the plan view of FIG. 1, the sealing material 60 filled in the sealing groove 50 is shown by hatching, but this hatching does not show the cross-section of the sealing material 60.

[0015] This field-through 1 is, for example, a connection part for introducing a submarine cable into a submarine repeater. Hereinafter, the field-through 1 for connecting a submarine cable using the optical fiber 40 as a transmission line to a submarine repeater will be described in detail. However, the field-through 1 of the present disclosure can be applied not only to submarine repeaters but also to other electronic devices.

[0016] As shown in FIG. 1, the field-through 1 includes a sleeve 10 including a sleeve upper part 11, a sleeve central part 12, and a sleeve lower part 13, and a guide 20 fitted to at least the inner peripheral surface of the sleeve central part 12. Further, the field-through 1 has an optical fiber 40 inserted into a through hole 30 formed in the sleeve 10. Further, the field-through 1 has a sealing material 60 that hermetically seals a part of the optical fiber 40 in a sealing groove 50 formed between the sleeve upper part 11 and the guide 20 and communicating with the through hole 30. And the heat conductivity of the sleeve lower part 13 is lower than that of the sleeve upper part 11 of the sleeve 10.

[0017] According to such a configuration, in the sealing process when manufacturing the field-through 1 described later, it is possible to suppress the molten sealing material 60 from flowing downward from the sealing groove 50 more than necessary, and preferably fill the sealing material 60 that hermetically seals a part of the optical fiber 40 in the sealing groove 50.

[0018] Details of each component of the field-through 1 will be described. The sleeve 10 is a bottomed cylindrical member made of metal that extends in the vertical direction. The sleeve 10 includes a sleeve upper part 11 formed in a substantially cylindrical shape, a sleeve central part 12 formed in a substantially cylindrical shape, and a sleeve lower part 13 formed in a substantially columnar shape. The sleeve upper part 11, the sleeve central part 12, and the sleeve lower part 13 are arranged vertically in this order from above and are integrally formed.

[0019] The sleeve upper part 11, together with the sleeve central part 12, constitutes the cylindrical part of the sleeve 10. The sleeve central part 12 has a thickness larger than that of the sleeve upper part 11 so as to expand radially inward of the sleeve 10. Therefore, the sleeve central part 12 has an inner diameter smaller than the inner diameter of the sleeve upper part 11 and has an outer diameter substantially the same as the outer diameter of the sleeve upper part 11. Further, a heat adjustment groove 12a that recesses from the outer peripheral surface toward the radially inner side of the sleeve 10 is formed in the sleeve central part 12. The heat adjustment groove 12a extends in the circumferential direction. The heat adjustment groove 12a has a function of adjusting the relative heat capacity of the sleeve central part 12 and the guide lower part 22 by reducing the heat capacity of the sleeve central part 12.

[0020] The sleeve lower part 13 constitutes the bottom of the sleeve 10. The sleeve lower part 13 has a thickness larger than that of the sleeve upper part 11 so as to expand radially outward of the sleeve 10. Therefore, the sleeve lower part 13 has an inner diameter substantially the same as the inner diameter of the sleeve upper part 11 and has an outer diameter larger than the outer diameter of the sleeve upper part 11. Since the heat dissipation area of the sleeve lower part 13 is increased compared with the sleeve upper part 11, the heat capacity is increased.

[0021] The guide 20 is a metal rod-shaped member extending in the vertical direction. The guide 20 includes a guide upper portion 21 and a guide lower portion 22. The guide upper portion 21 and the guide lower portion 22 are arranged vertically in this order from above and are integrally formed. A heat adjustment groove 21a that is recessed downward from the upper end surface is formed in the guide upper portion 21. The heat adjustment groove 21a extends in the vertical direction along the sealing groove 50. The heat adjustment groove 21a has a function of adjusting the relative heat capacity of the sleeve upper portion 11 and the guide upper portion 21 by reducing the heat capacity of the guide upper portion 21.

[0022] The guide lower portion 22 has an outer diameter slightly smaller than the inner diameter of the sleeve central portion 12 and fits onto the inner peripheral surface of the sleeve central portion 12. Further, the guide lower portion 22 has an outer diameter larger than the outer diameter of the guide upper portion 21. The guide 20 fitted onto the inner peripheral surface of the sleeve central portion 12 has the guide lower portion 22 abutting against the sleeve lower portion 13. As a result, downward movement of the guide 20 within the sleeve 10 is restricted, so that at least after the sealing process, the field-through 1 does not require a fixing member such as a nut for fixing the guide 20 within the sleeve 10.

[0023] The field-through 1 has a plurality of optical fibers 40. The optical fibers 40 are inserted into a through-hole 30 that penetrates the field-through 1 in the vertical direction. In the field-through 1 shown in FIG. 1, two optical fibers 40 are inserted into the through-hole 30 such that they are arranged symmetrically in the radial direction with respect to the central axis of the vertically extending field-through 1. The optical fiber 40 has a coated portion 41 in which a metal coating is applied to the surface of a resin primary coat exposed by removing a part of the resin protective coating.

[0024] The sealing groove 50 filled with the sealing material 60 is a groove extending in the vertical direction defined by the inner peripheral surface of the sleeve upper portion 11 and the outer peripheral surface of the guide upper portion 21. The sealing groove 50 has an upper end that is open and communicates with the outside, and a lower end that communicates with the through-hole 30.

[0025] For the sealing material 60, a low melting point metal such as solder can be used. The sealing material 60 is filled into the sealing groove 50 by heating and melting and then solidifying. The sealing material 60 can be filled into the sealing groove 50 by heating and melting it by bringing a solder bar R inserted into the sealing groove 50 into contact with the sleeve 10 (specifically, the upper end surface of the upper part 11 of the sleeve) from the opening of the sealing groove 50 and then solidifying it. However, the method of filling the sealing groove 50 with the sealing material 60 is not limited to this. For example, the sealing material 60 may be filled into the sealing groove 50 by heating and melting and then solidifying the molten solder poured into the sealing groove 50 from the opening of the sealing groove 50. The sealing material 60 can be heated and melted by heating means H such as a heating coil provided outside the sleeve 10. When solidifying the sealing material 60, the sealing material 60 may be cooled and solidified by appropriate cooling means.

[0026] Here, FIG. 2 is a diagram showing a field-through 100 according to a comparative example. Above FIG. 2, a plan view of the field-through 100 is shown. In the center of FIG. 2, a cross-sectional view taken along line B-B of the field-through 100 is shown. Below FIG. 2, a bottom view of the field-through 100 is shown. Similar to the case of FIG. 1, in the plan view of FIG. 2, the sealing material 60 filled in the sealing groove 50 is shown by hatching, but this hatching does not show the cross-section of the sealing material 60.

[0027] As shown in FIG. 2, the field-through 100 according to the comparative example has the same components as the field-through 1 except that it has a sleeve 15 instead of the sleeve 10. Therefore, the field-through 100 will be described centering on the differences from the field-through 1.

[0028] The field-through 100 has a sleeve 15 including an upper sleeve portion 11, a central sleeve portion 12, and a lower sleeve portion 16, and a guide 20 fitted to the inner peripheral surface of the central sleeve portion 12. Further, the field-through 100 has an optical fiber 40 inserted into a through-hole 30 formed in the sleeve 15. Further, the field-through 100 has a sealing material 60 that hermetically seals a part of the optical fiber 40 in a sealing groove 50 formed between the upper sleeve portion 11 and the guide 20 and communicating with the through-hole 30.

[0029] Unlike the lower sleeve portion 13, the lower sleeve portion 16 has a thickness substantially the same as that of the upper sleeve portion 11. Therefore, the lower sleeve portion 16 has an inner diameter substantially the same as the inner diameter of the upper sleeve portion 11 and an outer diameter substantially the same as the outer diameter of the upper sleeve portion 11. The sleeve 15 has the same thermal conductivity of the lower sleeve portion 16 as that of the upper sleeve portion 11.

[0030] The manufacturing method of the field-through 1, 100 has a sealing step of hermetically sealing a part of the optical fiber 40 in the sealing groove 50 with the sealing material 60 that has been heated and melted and solidified. In this sealing step, the sleeve 10, 15 (particularly the upper sleeve portion 11) is heated by the heating means H so that the temperature of the sleeve 10, 15 becomes equal to or higher than the melting point temperature of the sealing material 60, thereby melting the sealing material 60. However, when the sleeve 10, 15 is heated by the heating means H, since the sealing groove 50 serves as heat insulation, heat conduction deteriorates. Therefore, in order to heat the temperature of the inner side in the radial direction (the guide 20 side) of the sealing groove 50 to a temperature equal to or higher than the melting point of the sealing material 60, it is necessary to apply excessive heat to the sleeve 10, 15 by the heating means H.

[0031] Here, when at least one of the sealing groove 50 and the through hole 30 is overheated, the primary coat in the covering portion 41 thermally deforms, increasing light loss, and the pressure resistance, watertightness, and airtightness of the field-throughs 1, 100 may decrease. Further, when a temperature gradient from the outer side (sleeve 10 side or sleeve 15 side) to the inner side in the radial direction occurs in the sealing groove 50, when the sealing material 60 solidifies, strain occurs inside the sealing material 60, generating microbends in the optical fiber 40, which may increase light loss.

[0032] In the field-throughs 1, 100, since the heat adjustment groove 21a is provided in the upper guide 21, the heating amount by the heating means H can be reduced, so overheating of the sealing groove 50 (particularly the outer side in the radial direction of the sealing groove 50) together with the upper sleeve 11 is suppressed. As a result, deformation of the primary coat in the covering portion 41 can be suppressed.

[0033] Also, in the field-throughs 1, 100, since the heat adjustment groove 21a is provided in the upper guide 21, the temperature gradient from the outer side to the inner side in the radial direction in the sealing groove 50 can be reduced, so when the sealing material 60 solidifies, generation of strain inside the sealing material 60 and generation of microbends in the optical fiber 40 are suppressed. As a result, an increase in the light loss of the optical fiber 40 is suppressed.

[0034] Furthermore, in the field-throughs 1, 100, since the heat adjustment groove 12a is provided in the central sleeve 12, the heating amount by the heating means H can be reduced, so overheating of the through hole 30 between the central sleeve 12 and the lower guide 22 together with the central sleeve 12 is suppressed. As a result, thermal deformation of the primary coat in the covering portion 41 is suppressed.

[0035] However, particularly when the heating time by the heating means H is long or the heating temperature by the heating means H is high, in the sealing process when manufacturing the field-through 100, the molten sealing material 60 easily flows downward from the sealing groove 50. When the molten sealing material 60 thus flows out downward from the sealing groove 50 more than necessary, in the field-through 100 after the sealing material 60 has solidified, the filling amount of the sealing material 60 filled in the sealing groove 50 may become insufficient. Also, in the field-through 100 after the sealing material 60 has solidified, voids may occur inside the sealing material 60 due to non-uniform filling of the sealing material 60. In this case, there are problems that the reliability such as the pressure resistance, water tightness, and air tightness of the field-through 100 decreases, and the optical loss increases due to the generation of micro-bends in the optical fiber 40.

[0036] Therefore, the manufacturing method of the field-through 1 includes a sealing process of hermetically sealing a part of the optical fiber 40 inserted into the through-hole 30 formed in the sleeve 10 with the sealing material 60 that has been heated, melted, and solidified between the guide 20 fitted to the inner peripheral surfaces of at least the sleeve central portion 12 and the sleeve upper portion 11 and communicating with the through-hole 30. And this sleeve 10 is characterized in that the thermal conductivity of the sleeve lower portion 13 is lower than the thermal conductivity of the sleeve upper portion 11. By such a manufacturing method, it is possible to obtain a field-through 1 in which the sealing groove 50 is preferably filled with the sealing material 60 that hermetically seals a part of the optical fiber 40.

[0037] In the sealing process of manufacturing the field-through 1, when the sleeve 10 is heated by the heating means H, the heat dissipation effect of the lower part 13 of the sleeve is high, so that the temperature of the through hole 30 in the lower part 13 of the sleeve can be reduced. Therefore, in this sealing process, even if the molten sealing material 60 flows downward from the sealing groove 50, the sealing material 60 solidifies and stays in the range near the upper part 11 of the sleeve of the through hole 30. Therefore, it is possible to suppress the molten sealing material 60 from flowing out downward from the sealing groove 50 more than necessary. As a result, the sealing groove 50 can be uniformly filled with the sealing material 60 having a sufficient filling amount. Therefore, it is possible to suppress a decrease in the reliability such as the pressure resistance, water tightness, and air tightness of the field-through 1, and an increase in the optical loss due to the generation of microbends in the optical fiber 40.

[0038] Therefore, according to the present embodiment, it is possible to provide the field-through 1 having high reliability and reducing the optical loss of the optical fiber 40, and a method for manufacturing the field-through 1.

[0039] Other embodiments In the above-described Embodiment 1, by making the thickness of the lower part 13 of the sleeve larger than the thickness of the upper part 11 of the sleeve, a difference in thermal conductivity is generated between the upper part 11 and the lower part 13 of the sleeve. However, if the thermal conductivity of the lower part 13 of the sleeve can be made lower than the thermal conductivity of the upper part 11 of the sleeve, other configurations may be adopted.

[0040] For example, in the field-through 1, a heat dissipation member may be attached to the outer peripheral surface of the lower part 13 of the sleeve. The heat dissipation member is a member having higher thermal conductivity than the sleeve 10. As the heat dissipation member, for example, a heat dissipation sheet such as a cool sheet or a heat sink can be used. These heat dissipation members are preferably attached so as to be in close contact with the outer peripheral surface of the lower part 13 of the sleeve. Further, in the case of the lower part 13 of the sleeve having an outer peripheral surface and an inner peripheral surface, a heat dissipation member may be attached to at least one of the inner peripheral surface and the outer peripheral surface of the lower part 13 of the sleeve.

[0041] Also, these heat dissipation members may be used individually or in combination. When these heat dissipation members are used in combination, for example, the heat dissipation member may include a heat sink attached to the outer peripheral surface of the lower part 13 of the sleeve as a heat radiator, and may include a cool sheet interposed between the lower part 13 of the sleeve and the heat radiator as a heat dissipation sheet. By attaching a substantially cylindrical heat sink to the outer peripheral surface of the lower part 13 of the sleeve and interposing a cool sheet with high adhesiveness between the lower part 13 of the sleeve and the heat sink, the heat dissipation effect can be further enhanced.

[0042] Also, the lower part 13 of the sleeve may have a fin shape. When the lower part 13 of the sleeve has a fin shape, since the heat dissipation area of the lower part 13 of the sleeve increases, the heat dissipation effect can be enhanced.

[0043] In the other embodiments described above, it is not necessary to make the thickness of the lower part 13 of the sleeve larger than the thickness of the upper part 11 of the sleeve, but the thickness of the lower part 13 of the sleeve may be made larger than the thickness of the upper part 11 of the sleeve as necessary.

[0044] As described above, the present disclosure has been described with reference to the embodiments, but the present disclosure is not limited to the above-described embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present disclosure within the scope of the present disclosure. And each embodiment can be combined with other embodiments as appropriate.

[0045] The figures are merely illustrative for explaining one or more embodiments. Each figure may be associated with not only one specific embodiment but also one or more other embodiments. As can be understood by those skilled in the art, various features or steps described with reference to any one figure can be combined with features or steps shown in one or more other figures to create, for example, embodiments not explicitly illustrated or described. Not all of the features or steps shown in any one figure for explaining exemplary embodiments are necessarily essential, and some features or steps may be omitted. The order of the steps described in any figure may be changed as appropriate.

[0046] Some or all of the above embodiments may be described as follows, but are not limited thereto. Some or all of the elements (such as configurations and functions) described in Appendices 2 to 7 subordinate to Appendix 1 may be subordinate to Appendix 8 in the same subordinate relationship as Appendices 2 to 7. (Appendix 1) A sleeve including an upper sleeve portion, a central sleeve portion, and a lower sleeve portion, A guide fitted to at least the inner peripheral surface of the central sleeve portion, An optical fiber inserted into a through hole formed in the sleeve, A sealing material that hermetically seals a part of the optical fiber in a sealing groove formed between the upper sleeve portion and the guide and communicating with the through hole, The sleeve is a field-through in which the thermal conductivity of the lower sleeve portion is lower than that of the upper sleeve portion. (Appendix 2) The lower sleeve portion of the field-through according to Appendix 1 has a thickness greater than that of the upper sleeve portion so as to expand outward in the radial direction. (Appendix 3) The field-through according to Appendix 1, wherein a heat dissipation member is attached to at least one of the inner peripheral surface and the outer peripheral surface of the lower sleeve portion. (Appendix 4) The lower part of the sleeve has a field-through as described in Appendix 1 having a fin shape. (Appendix 5) In the central part of the sleeve, a heat adjustment groove that is recessed radially inward from the outer peripheral surface is formed in the field-through as described in Appendix 1. (Appendix 6) In the upper part of the guide of the guide, a heat adjustment groove that is recessed downward from the upper end surface is formed in the field-through as described in Appendix 1. (Appendix 7) Connect a submarine cable using the optical fiber as a transmission path to a submarine repeater in the field-through as described in Appendix 1. (Appendix 8) A sealing process is provided in which a part of the optical fiber inserted into a through hole formed in a sleeve including the upper part of the sleeve, the central part of the sleeve, and the lower part of the sleeve by a sealing material that has been heated and melted and solidified is hermetically sealed in a sealing groove formed between the upper part of the sleeve and at least the inner peripheral surface of the central part of the sleeve and communicating with the through hole. A method for manufacturing a field-through in which the heat conductivity of the lower part of the sleeve is lower than the heat conductivity of the upper part of the sleeve.

Explanation of reference numerals

[0047] 1, 100 Field-through 10, 15 Sleeve 11 Upper part of the sleeve 12 Central part of the sleeve 12a Heat adjustment groove 13, 16 Lower part of the sleeve 20 Guide 21 Upper part of the guide 21a Heat adjustment groove 22 Lower part of the guide 30 Through hole 40 Optical fiber 41 Coating part 50 Sealing groove 60 Sealing material H Heating means R Solder bar

Claims

1. a sleeve including an upper sleeve portion, a middle sleeve portion, and a lower sleeve portion; A guide fitted to an inner peripheral surface of at least the central portion of the sleeve; an optical fiber inserted into a through hole formed in the sleeve; a sealing material that hermetically seals a portion of the optical fiber in a sealing groove that is formed between the upper portion of the sleeve and the guide and communicates with the through hole, The sleeve has a field through which the thermal conductivity of the lower portion of the sleeve is lower than the thermal conductivity of the upper portion of the sleeve.

2. The feedthrough of claim 1 , wherein the lower sleeve portion has a thickness greater than a thickness of the upper sleeve portion so as to expand radially outward.

3. 2. The feedthrough according to claim 1, wherein a heat dissipating member is attached to at least one of an inner peripheral surface and an outer peripheral surface of the lower portion of the sleeve.

4. The feedthrough of claim 1 , wherein the lower sleeve portion has a fin shape.

5. 2. The feedthrough according to claim 1, wherein a heat adjustment groove recessed radially inward from an outer circumferential surface is formed in a central portion of the sleeve.

6. 2. The feedthrough according to claim 1, wherein a heat adjustment groove recessed downward from an upper end surface of the guide is formed in an upper portion of the guide.

7. 2. The feedthrough according to claim 1, wherein an undersea cable using said optical fiber as a transmission line is connected to an undersea repeater.

8. a sealing step of hermetically sealing a part of an optical fiber inserted into a through hole formed in a sleeve including an upper sleeve portion, a central sleeve portion, and a lower sleeve portion, in a sealing groove formed between the upper sleeve portion and a guide fitted to an inner peripheral surface of at least the central sleeve portion and communicating with the through hole, by using a sealing material that is heated, melted, and solidified; A method for manufacturing a feedthrough, the sleeve having a lower thermal conductivity than an upper portion of the sleeve.

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