Hermetic terminal with improved adhesion of glass seal to high power lead

Abstract

There is provided a hermetic terminal for a large amount of power so as to secure wettability of a lead member to glass and improve hermetic reliability of a glass sealing portion. A hermetic terminal includes: a metal base provided with at least one through hole; a lead inserted in the through hole of the metal base; and an insulating member that seals the lead in the metal base. The lead includes: a core member; a binding member that at least coats an outer diameter portion of the core member; an intermediate member that coats a surface of the binding member and that is composed of a low-electric-resistance material; and an outer coating member that coats the intermediate member and that has a stable glass binding characteristic at a sealing temperature.

Claims

1. A hermetic terminal for feeding electrical power into a hermetically sealed housing comprising: a metal base having a through hole; a lead extending through the through hole of the metal base; and an insulating member that seals the lead in the through hole of the metal base; wherein the lead includes: a core member serving as a structural member, a binding layer that coats at least an outer diameter portion of the core member, an intermediate layer that coats a surface of the binding layer and that is composed of a low-electric-resistance material, and an outer coating layer that coats a surface of the intermediate layer and that has a stable binding characteristic of binding to the insulating member at a sealing temperature; and the binding layer and the outer coating layer are composed of the same material.

2. The hermetic terminal according to claim 1, wherein the core member is composed of Fe or a Fe-based alloy.

3. The hermetic terminal according to claim 1, wherein the binding layer is composed of a metal selected from a group consisting of Ni, Cu, Ag, a Ni alloy, a Cu alloy, and an Ag alloy.

4. The hermetic terminal according to claim 1, wherein the low-electric-resistance material of the intermediate layer exhibits an electric resistance value less than an electric resistance value of a copper material.

5. The hermetic terminal according to claim 1, wherein the low-electric-resistance material of the intermediate layer is a metal composed of Cu or Al or an alloy including at least 5 weight % of at least one of Cu and Al.

6. The hermetic terminal according to claim 1, wherein the sealing temperature is at least 600° C. and at most 1100° C.

7. The hermetic terminal according to claim 1, wherein the insulating member consists of a glass material.

8. The hermetic terminal according to claim 1, wherein the insulating member consists of a resin material.

9. The hermetic terminal according to claim 1, wherein the outer coating layer has characteristics as result from forming the outer coating layer by plating or cladding a coating material of the outer coating layer onto the intermediate layer.

10. The hermetic terminal according to claim 1, wherein the outer coating layer consists of a coating material that has better adhesion than the low-electric-resistance material of the intermediate layer to an insulating material of the insulating member.

11. The hermetic terminal according to claim 1, wherein the binding layer consists of a binding material that has affinity to a core material of the core member and to the low-electric-resistance material of the intermediate layer, and is unlikely to be diffused into the core material and/or into the low-electric-resistance material.

12. The hermetic terminal according to claim 1, wherein the outer coating layer consists of a coating material that forms an oxide thereof on a surface of the outer coating layer, wherein the coating material and/or the oxide has a characteristic of slowly dissolving in an insulating material of the insulating member at the sealing temperature.

13. The hermetic terminal according to claim 1, wherein the low-electric-resistance material of the intermediate layer exhibits an electric resistance value comparable to an electric resistance value of a copper material.

14. The hermetic terminal according to claim 1, wherein the core member consists of an Fe—Cr alloy, the binding layer consists of Ni, the low-electric-resistance material of the intermediate layer consists of Cu, and the outer coating layer consists of a metal selected from the group consisting of Cr, Ni and Pd.

15. The hermetic terminal according to claim 1, wherein the core member consists of an Fe—Cr alloy, the binding layer consists of Cu, Ni or Ag, the intermediate layer consists of Al, and the outer coating layer consists of Cr, Ni or Pd.

16. The hermetic terminal according to claim 1, wherein: the core member is composed of Fe or a Fe-based alloy, the binding layer is composed of a metal selected from a group consisting of Ni, Cu, Ag, a Ni alloy, a Cu alloy, and an Ag alloy, the low-electric-resistance material of the intermediate layer is a metal composed of Cu or Al or an alloy including at least 5 weight % of at least one of Cu and Al, and the outer coating layer is composed of one of metals composed of at least one of transition elements in groups 6A to 8 except for Tc in a long periodic table, or is composed of an alloy including at least 5 weight % of at least one of said metals.

17. The hermetic terminal according to claim 1, wherein the outer coating layer is composed of one of metals composed of at least one of transition elements in groups 6A to 8 except for Tc in a long periodic table, or is composed of an alloy including at least 5 weight % of at least one of said metals.

18. The hermetic terminal according to claim 17, wherein said metals composed of at least one of the transition elements, and the alloy including at least 5 weight % of at least one of said metals, are each composed of a metal selected from a group consisting of Cr, Ni, Ni—P, and Pd.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a plan view showing a hermetic terminal according to the present invention.

(2) FIG. 2 is a front partial cross sectional view showing the hermetic terminal according to the present invention and taken along a II-II line of FIG. 1.

(3) FIG. 3 is a bottom view showing the hermetic terminal according to the present invention.

DESCRIPTION OF EMBODIMENTS

(4) As shown in FIG. 1 to FIG. 3, a hermetic terminal 10 according to the present embodiment includes: a metal base 11 provided with at least one through hole; a lead 12 inserted in the through hole of metal base 11; and an insulating member 13 that seals lead 12 in metal base 11. Lead 12 includes: a core member 12a serving as a structural member; a binding member 12b that at least coats an outer diameter portion of core member 12a; an intermediate member 12c that coats a surface of this binding member 12b and that is composed of a low-electric-resistance material; and an outer coating member 12d that coats a surface of intermediate member 12c and that has a stable glass binding characteristic at a sealing temperature. Since the surface of intermediate member 12c composed of the low-electric-resistance material is coated with outer coating member 12d having a stable glass binding characteristic at the sealing temperature, adhesion with the glass can be secured by outer coating member 12d on the surface while the low-electric-resistance material having low adhesion with the glass is disposed as intermediate member 12c.

(5) Core member 12a of the present embodiment is composed of Fe or a Fe-based alloy for the structural member. Any material may be used for binding member 12b of the present invention as long as the material has affinity to core member 12a and intermediate member 12c and is unlikely to be diffused into core member 12a and intermediate member 12c. For example, as binding member 12b, Ni, Cu, Ag, a Ni alloy, a Cu alloy, or an Ag alloy can be used suitably.

(6) Any material may be used for intermediate member 12c of the present embodiment as long as the material is a low-electric-resistance material exhibiting an electric resistance value comparable to or less than or equal to an electric resistance value of a copper material. For example, as intermediate member 12c, a metal composed of Cu or Al, or an alloy including more than or equal to 5 weight % of at least one of Cu and Al can be suitably used.

(7) Any material may be used for outer coating member 12d of the present embodiment as long as the material is an outer coating member having a stable glass binding characteristic at a sealing temperature of more than or equal to 600° C. and less than or equal to 1100° C. For example, outer coating member 12d is composed of one of metals composed of transition elements in groups 6A to 8 except for Tc in a long periodic table, or is composed of an alloy including more than or equal to 5 weight % of at least one of the metals. At the sealing temperature, a compound, such as an oxide thereof, on a surface of such an outer coating member 12d or the metal thereof itself is slowly dissolved in glass. Therefore, even when the film thicknesses of the compound on the surface and the metal are thin, a cracked portion otherwise resulting from reaction with the glass is less likely to be formed. Hence, this is suitable. Particularly, an outer coating member 12d composed of a metal selected from a group of Cr, Ni, Ni—P, and Pd can be used suitably.

(8) According to the above-described configuration, while using, for intermediate member 12c, the low-electric-resistance material having low adhesion with the glass, outer coating member 12d prevents excessive reaction with the sealing glass at the lead interface of the hermetic terminal, thus attaining sealing with excellent hermeticity. Moreover, outer coating member 12d may be partially provided only at the interface with insulating member 13.

(9) It should be noted that a hermetic terminal with three terminals is illustrated in the present specification and figures; however, any form of hermetic terminal may be employed as long as a lead is sealed in a base with glass. The hermetic terminal is not limited to the one illustrated therein.

EXAMPLES

(10) As shown in FIG. 1 to FIG. 3, a hermetic terminal 10 according to an Example 1 includes: a metal base 11 that is provided with three through holes and that is composed of carbon steel; leads 12 inserted in the respective through holes of metal base 11; and insulating members 13 that seal leads 12 in metal base 11 and that are each composed of soda barium glass. Each of leads 12 includes: a core member 12a composed of a Fe—Cr alloy; a binding member 12b that coats an outer diameter portion of core member 12a and that is composed of Ni; an intermediate member 12c that coats a surface of binding member 12b and that is composed of Cu; and an outer coating member 12d that coats a surface of intermediate member 12c and that is composed of Cr.

(11) As shown in FIG. 1 to FIG. 3, a hermetic terminal 10 according to an Example 2 includes: a metal base 11 that is provided with three through holes and that is composed of carbon steel; leads 12 inserted in the respective through holes of metal base 11; and insulating members 13 that seal leads 12 in metal base 11 and that are each composed of soda barium glass. Each of leads 12 includes: a core member 12a composed of a Fe—Cr alloy; a binding member 12b that coats an outer diameter portion of core member 12a and that is composed of Ni; an intermediate member 12c that coats a surface of binding member 12b and that is composed of Cu; and an outer coating member 12d that coats a surface of intermediate member 12c and that is composed of Ni.

(12) As shown in FIG. 1 to FIG. 3, a hermetic terminal 10 according to an Example 3 includes: a metal base 11 that is provided with three through holes and that is composed of carbon steel; leads 12 inserted in the respective through holes of metal base 11; and insulating members 13 that seal leads 12 in metal base 11 and that are each composed of soda barium glass. Each of leads 12 includes: a core member 12a composed of a Fe—Cr alloy; a binding member 12b that coats an outer diameter portion of core member 12a and that is composed of Ni; an intermediate member 12c that coats a surface of binding member 12b and that is composed of Cu; and an outer coating member 12d that coats a surface of intermediate member 12c and that is composed of Pd.

(13) As shown in FIG. 1 to FIG. 3, a hermetic terminal 10 according to an Example 4 includes: a metal base 11 that is provided with three through holes and that is composed of stainless steel; leads 12 inserted in the respective through holes of metal base 11; and insulating members 13 that seal leads 12 in metal base 11 and that are each composed of soda barium glass. Each of leads 12 includes: a core member 12a composed of a Fe—Cr alloy; a binding member 12b that coats an outer diameter portion of core member 12a and that is composed of Cu; an intermediate member 12c that coats a surface of binding member 12b and that is composed of Al; and an outer coating member 12d that coats a surface of intermediate member 12c and that is composed of Cr.

(14) As shown in FIG. 1 to FIG. 3, a hermetic terminal 10 according to an Example 5 includes: a metal base 11 that is provided with three through holes and that is composed of stainless steel; leads 12 inserted in the respective through holes of metal base 11; and insulating members 13 that seal leads 12 in metal base 11 and that are each composed of soda barium glass. Each of leads 12 includes: a core member 12a composed of a Fe—Cr alloy; a binding member 12b that coats an outer diameter portion of core member 12a and that is composed of Ni; an intermediate member 12c that coats a surface of binding member 12b and that is composed of Al; and an outer coating member 12d that coats a surface of intermediate member 12c and that is composed of Ni.

(15) As shown in FIG. 1 to FIG. 3, a hermetic terminal 10 according to an Example 6 includes: a metal base 11 that is provided with three through holes and that is composed of stainless steel; leads 12 inserted in the respective through holes of metal base 11; and insulating members 13 that seal leads 12 in metal base 11 and that are each composed of soda barium glass. Each of leads 12 includes: a core member 12a composed of a Fe—Cr alloy; a binding member 12b that coats an outer diameter portion of core member 12a and that is composed of Ag; an intermediate member 12c that coats a surface of binding member 12b and that is composed of Al; and an outer coating member 12d that coats a surface of intermediate member 12c and that is composed of Pd.

(16) In the hermetic terminal according to the present embodiment, after sealing the lead in the metal base with glass, desired finishing plating can be further provided onto the metal surface. Moreover, for each of the core members described in the above-described Examples, any material may be used as long as a base structure for the intermediate member and the outer coating member can be formed. For example, the material of the core member is not limited to the Fe—Cr alloy, and may be a Fe—Ni alloy, carbon steel, or the like.

(17) Moreover, for each of the insulating members described in the above-described Examples, any material can be used as long as the lead can be insulated from and hermetically sealed in the metal base. The material of the insulating member is not limited to the soda barium glass, and any glass material can be used therefor. As the insulating member, a resin material such as an epoxy resin may be used instead of the glass material in view of such a fact that the outer coating member of the present embodiment has a function of protecting the chemically weak intermediate member from interface erosion, corrosion, and the like. An insulating coating such as a silicone resin may be provided on each of portions of the lead and metal base of the hermetic terminal of the present embodiment.

(18) The embodiments disclosed herein are illustrative and non-restrictive in any respect. The scope of the present invention is defined by the terms of the claims, rather than the embodiments described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

INDUSTRIAL APPLICABILITY

(19) The hermetic terminal according to the present invention can handle particularly high voltage and high current, and can be used as a hermetic terminal for which high hermeticity is required.

REFERENCE SIGNS LIST

(20) 10: hermetic terminal; 11: metal base; 12: lead; 12a: core member; 12b: binding member; 12c: intermediate member; 12d: outer coating member; 13: insulating member.