US20130330604A1

US20130330604A1 - Feed-through and method for integrating the feed-through in a housing by ultrasonic welding

Info

Publication number: US20130330604A1
Application number: US13/966,959
Authority: US
Inventors: Frank Kroll; Helmut Hartl; Andreas Roters; Hauke Esemann; Dieter Goedeke; Ulf Dahlmann; Sabine Pichler-Wilhelm; Martin Landendinger; Linda Johanna Backnaes
Original assignee: Schott AG
Current assignee: Schott AG
Priority date: 2011-02-18
Filing date: 2013-08-14
Publication date: 2013-12-12
Also published as: CN103380097B; PL2675768T3; JP2019192657A; KR20140006905A; CN103384649B; US9527157B2; EP2675766B1; EP3579296A1; CN109956682B; EP2675768A1; JP2014510366A; US20170098803A1; KR101966607B1; WO2012110242A4; US9539665B2; CN109956682A; JP2014511544A; US20130330600A1; CN103298762B; CN103402941B

Abstract

A feed-through, in particular a feed-through which passes through a housing component of a housing, for example a battery housing, such as a battery cell housing. The housing component includes at least one opening through which at least one conductor, for example an essentially pin-shaped conductor, is guided. The pin-shaped conductor is at least partially surrounded by an insulator, for example made of a glass or a glass ceramic material. The at least one conductor connection, for example of the essentially pin-shaped conductor and/or of the housing component with the insulator, which is a glass or a glass ceramic material, is formed, the connection being an ultrasonic welding.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation of PCT application No. PCT/EP2012/000701, entitled “FEED-THROUGH, IN PARTICULAR FOR BATTERIES AND METHOD FOR INTEGRATING SAID FEED-THROUGH IN A HOUSING BY MEANS OF ULTRASONIC WELDING”, filed Feb. 17, 2012, which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a feed-through, for example a feed-through which passes through a housing component or respectively a part of a housing, such as a battery cell housing, whereby the housing part or respectively the housing component includes at least one opening through which a conductor, for example an essentially pin-shaped conductor, is guided. Moreover, the present invention relates to a housing, in particular for a battery cell having a feed-through, as well as to a method for providing a housing component or respectively a housing part with a feed-through, and a storage device, such as an accumulator with a battery cell housing, whereby the battery cell housing includes at least one opening with one feed-through.
2. Description of the Related Art
According to the current state of the art electric feed-throughs, as described for example in the following references: U.S. Pat. No. 5,243,492; U.S. Pat. No. 7,770,520; US 2010/0064923; EP 1 061 325; and DE 10 2007 016692, are produced from solder glasses which function as insulators. With all feed-throughs known from the current state of the art, an essentially pin-shaped conductor is connected with the respective housing component by means of melting a glass having a low melting point. It is disadvantageous hereby that the thermal stability of the metallic materials, in particular their melting point, limits the possible maximum melting temperature for the utilized solder glass. Moreover it is necessary that the melted solder glass wets the used materials of the components well in order to ensure the required tightness and mechanical stability. A further requirement is that generally the solder glass has to be selected for the plurality of feed-throughs in such a manner that the thermal expansion of the components does not greatly deviate from each other. An exception hereto are only compression seal feed-throughs, or respectively compression seals in the form of special seals, whereby different thermal expansions of glass or glass ceramic material and surrounding metal lead to a frictional connection of glass or glass ceramic material and surrounding metal. These types of compression seal feed-throughs are used for example for airbag igniters. In the case of compression seal feed-throughs the glass or glass ceramic material adheres to the surrounding metal; however no molecular connection exists between the glass or glass ceramic material and the metal. The frictional connection is lost as soon as the opposing force of the static friction is exceeded.
From DE 10 006 199 it is known to hermetically seal a body form consisting of a brittle material, in particular glass with an opening, with a sealing body, whereby the body form and the sealing body are permanently welded together. According to DE 10 006 199 the body form consists of a glass, a glass ceramic or a ceramic and the sealing body preferably of a metal, a metal alloy or a metal composite material. The thermal expansions of the body form and the sealing body are hereby adapted. An electric feed-through is not shown in DE 10 006 199.
Connection of a metal strip with an optical element, comprising preferably a glass or glass ceramic material by means of ultrasonic welding is also known from DE 1 496 614. As the preferred material for the metal which is to be joined, an aluminum alloy is shown in DE 1 496 614. There are also no feed-throughs shown in DE 1 496 614.
Accumulators, preferably lithium-ion batteries are intended for various applications, for example for portable electronic equipment, cell phones, power tools and in particular electric vehicles. The batteries can replace traditional energy sources, for example lead-acid batteries, nickel-cadmium batteries or nickel-metal hydride batteries.
Lithium-ion batteries have been known for many years. In this regard we refer you to the “Handbook of Batteries, published by David Linden, 2nd issue, McGrawhill, 1995, chapters 36 and 39”. Various aspects of lithium-ion accumulators are described in a multitude of patents, for example: U.S. Pat. No. 961,672; U.S. Pat. No. 5,952,126; U.S. Pat. No. 5,900,183; U.S. Pat. No. 5,874,185; U.S. Pat. No. 5,849,434; U.S. Pat. No. 5,853,914; and U.S. Pat. No. 5,773,959.
Lithium-ion batteries, in particular for applications in the automobile industry generally feature a multitude of individual battery cells which are generally connected in-series. The in-series connected battery cells are usually combined into so-called battery packs and then to a battery module which is also referred to as lithium-ion battery. Each individual battery cell has electrodes which are led out of a housing of the battery cell.
In particular in the use of lithium-ion batteries in the automobile industry, a multitude of problems such as corrosion resistance, stability in accidents and vibration resistance must be solved. An additional problem is the hermetic seal of the battery cells over an extended period of time. The hermetic seal may for example be compromised by leakage in the area of the electrodes of the battery cell or respectively the electrode feed-through of the battery cell. Such leakages may for example be caused by temperature changes and alternating mechanical stresses, for example vibrations in the vehicle or aging of the synthetic material. A short-circuit or temperature changes in the battery or respectively battery cell can lead to a reduced life span of the battery or the battery cell.
In order to ensure better stability in accidents, a housing for a lithium-ion battery is suggested for example in DE 101 05 877 A1, whereby the housing includes a metal jacket which is open on both sides and which is being sealed. The power connection is insulated by a synthetic material. A disadvantage of the synthetic material insulations is the limited temperature resistance, the limited mechanical stability, aging and the uncertain hermetic seal over the service life. The current feed-throughs on the lithium-ion batteries according to the current state of the art are therefore not integrated hermetically sealed into the cover part of the lithium-ion battery. Moreover, the electrodes are crimped and laser welded connecting components with additional insulators in the interior of the battery.
An alkaline battery has become known from DE 27 33 948 A1 wherein an insulator, for example glass or ceramic, is joined directly by means of a fusion bond with a metal component.
One of the metal parts is connected electrically with one anode of the alkaline battery and the other is connected electrically with the cathode of the alkaline battery. The metals used in DE 27 33, 948 A1 are iron or steel. Light metals like aluminum are not described in DE 27 33 948 A1. Also, the sealing temperature of the glass or ceramic material is not cited in DE 27 33 948 A1. The alkaline battery described in DE 27 33 948 A1 is a battery with an alkaline electrolyte which, according to DE 27 33 948 A1, contains sodium hydroxide or potassium hydroxide. Lithium-ion batteries are not favored in DE 27 33 948 A1.
A method to produce asymmetrical organic carboxylic acid esters and to produce anhydrous organic electrolytes for alkali-ion batteries has become known from DE 698 04 378 T2, or respectively EP 0885 874 B1. Electrolytes for rechargeable lithium-ion cells are also described in DE 698 04 378 T2, or respectively EP 0885 874 B1.
An RF-feed through, or a radio frequency-feed-through, with improved electrical efficiency is described in DE 699 23 805 T2, or respectively EP 0 954 045 B1. The feed-throughs known from DE 699 23 805 T2 or respectively EP 0 954 045 B1 are not glass-metal feed-throughs. Glass-metal feed-throughs which are provided immediately inside for example the metal wall of a packing are described in EP 0 954 045 B1 as being disadvantageous since RF feed-throughs of this type due to embrittlement of the glass are not durable.
DE 690 230 71 T2, or respectively EP 0 412 655 B1, describes a glass-metal feed-through for batteries or other electrochemical cells, whereby glasses having an SiO₂content of approximately 45 weight-% are being used and metals, in particular alloys, are being used which contain molybdenum and/or chromium and/or nickel. The use of light metals is insufficiently addressed in DE 690 230 71 T2, as are sealing temperatures or respectively bonding temperatures for the used glasses. The materials used for the pin shaped conductor are, according to DE 690 230 71 T2 or respectively EP 0 412 655 B1, alloys which contain molybdenum, niobium or tantalum.
A glass-metal feed-through for lithium-ion batteries has become known from U.S. Pat. No. 7,687,200. According to U.S. Pat. No. 7,687,200 the housing was produced from high-grade steel and the pin-shaped conductor from platinum/iridium. The glass materials cited in U.S. Pat. No. 7,687,200 are glasses TA23 and CABAL-12. According to U.S. Pat. No. 5,015,530 these are CaO—MgO—Al₂O₃-α₂O₃systems having sealing temperatures of 1025° C. or 800° C. Moreover, glass compositions for glass-metal feed-throughs for lithium batteries have become known from U.S. Pat. No. 7,687,200 which contain CaO, Al₂O₃, B₂O₃, SrO and BaO whose sealing temperatures are in the range of 650° C.-750° C. and which are therefore too high for use with light metals. Furthermore, barium is undesirable in many applications since it is considered to be environmentally harmful and hazardous to health. Also discussed is strontium, the use of which is also to be avoided in the future. Furthermore, the glass compositions according to U.S. Pat. No. 7,687,200 moreover have a coefficient of expansion a in the temperature range of 20° C. to 300° C. of only a α≈9×10⁻⁶/K.
What is needed in the art is to avoid the disadvantages of the current state of the art as described above and to cite an electric feed-through which is simple to produce and which can in particular also be used in a battery cell housing. The feed-through shall moreover also distinguish itself through high stability.

SUMMARY OF THE INVENTION

The present invention provides a housing component of a housing, such as a battery housing, whereby the housing component includes at least one opening through which a conductor, such as an essentially pin-shaped conductor is guided and whereby the conductor, in particular the essentially pin-shaped conductor is surrounded at least partially by an insulator, for example by a glass or glass ceramic material. The inventive feed-through includes at least one connection of the essentially pin-shaped conductor and/or the housing component with the insulator, which is in the form of a glass or glass ceramic material, the connection being an ultrasonic welding.
A battery according to the present invention is to be understood to be a disposable battery which is disposed of and/or recycled after its discharge, as well as an accumulator.
Ultrasonic welding is a joining technology which is used, for example, with thermoplastic and polymer-compatible plastics, for example in situations where short process times at high process reliability are required. During ultrasonic welding, high frequency mechanical vibrations cause molecular and interfacial friction in a joining region. The heat necessary for welding is thereby generated and the material is being plasticized. After the ultrasound action, a homogeneous solidification of the joining region is achieved through short cooling times and by maintaining the joining pressure. The geometry of the sonotrode, as well as the configuration of the joining region can, for example, also influence the welding result. In contrast to pressure sealing wherein only a friction connection is provided, the connection between the glass material and the material with which the glass material is joined is a chemical connection.
The fundamental characteristics of ultrasonic welding are: very short process times, very good process control and reliability through monitoring of the welding parameters, selective energy supply using digital control of the welding process, constant welding quality with optical perfect and stable, as well as reproducible welding seams and optically appealing welding seam appearance. Moreover it is possible to connect any desired contours, in particular also any desired closed contours of two materials with each other. Cold welding tools can advantageously be utilized, so that no consideration has to be given to warm-up times of the machine and fast, simple changeover of the welding tools is possible. Moreover, the welding seams are air tight as well as liquid tight.
Due to the arrangement as an ultrasonic welding connection it is possible to use glass or glass ceramic materials which have higher sealing temperatures than, for example, the melting temperatures of the materials of the housing component. This makes the selection of glasses or glass ceramic materials possible which, in their wetting behavior are adapted to the used materials of the housing component and/or pin. Due to the good wettability, the glass and/or glass ceramic materials then provides the necessary tightness and mechanical stability, whereby the sealing temperature of the used materials can then be freely selected.
Sealing temperature of the glass or glass ceramic is understood to be the temperature of the glass or the glass ceramic whereby the glass material softens and then fits closely against the metal which is to be sealed so that a bonded joint connection is obtained between the glass or the glass ceramic and the metal.
The sealing temperature may, for example, be determined through the hemispherical temperature as described in R. Gorke, K. J. Leers: Keram. Z. 48 (1996) 300-305, or according to DIN 51730, ISO 540 or CEN/TS 15404 and 15370-1 whose disclosure content is incorporated in its entirety into the current patent application. According to DE 10 2009 011 182A1, the hemispherical temperature can be determined in a microscopic process by using a heating stage microscope. It identifies the temperature at which an originally cylindrical test body melts into a hemispherical mass. A viscosity of approximately log η=4.6 deciPascals (dPas) can be allocated to the hemispherical temperature, as can be learned from appropriate technical literature. If a crystallization-free glass, for example in the form of a glass powder, is melted down and then cooled so that it solidifies, it can then normally be melted down again at the same melting temperature. For a bonded connection with a crystallization-free glass this means that the operating temperature to which the bonded connection is continuously subjected may not be higher than the sealing temperature. Glass compositions as utilized in the current application are generally often produced from a glass powder which is melted down and which, under the influence of heat provides the bonded connection with the components which are to be joined. Generally, the sealing temperature or melting temperature is consistent with the level of the so-called hemispherical temperature of the glass. Glasses having low sealing temperatures or respectively melting temperatures are also referred to as solder glass. Instead of fusing or melting temperature, one speaks of solder temperature or soldering temperature in this instance. The sealing temperature or respectively the solder temperature may deviate from the hemispherical temperature by +20K.
The solder glass having become known from DE 10 2009 011 182 A1 pertains to high temperature applications, for example fuel cells.
An additional advantage of the connection between insulator, in particular glass material, with the surrounding material using a welding connection, such as an ultrasonic welding connection in accordance with the present invention is to be seen in that the utilized materials may be selected relatively freely and an adaptation, for example of the thermal expansion of the components is no longer in the foreground. This allows, for example, for the glass or the glass ceramic to be adapted to the electrolyte of the battery cell. In particular, materials can be selected that offer a high resistance to the chemically aggressive electrolytes. This is the case especially if the connection of the insulator to the base body, as well as the connection of the insulator to the essentially pin-shaped conductor occurs by ultrasonic welding. In such a case, a glass ceramic or quartz glass could, for example, be used as the material for the insulator. The glass ceramic distinguishes itself through very high strength, high chemical resistance and a low coefficient of expansion. Quartz glass has a very high stability, in particular when compared to most of the melting or solder glasses.
According to an embodiment of the present invention, the pin-shaped conductor includes a head part and the insulator, in particular the glass or glass ceramic material is introduced between the head part and housing component. The glass or glass ceramic material is, for example, ring-shaped, for example a glass ring. In this embodiment of a pin-shaped conductor with a head part, welding can be provided between the essentially pin-shaped conductor, produced for example of aluminum and the ring-shaped material, for example the glass ring. The ultrasonically welded joint may however also be located between the insulator and the housing component. If both joints are welded joints the greatest freedom in regard to material selection for the insulator as described above is provided. The arrangement of the pin-shaped conductor with a head part has particular advantages in regard to space which, inside battery cells is mostly very tight. Pin-shaped conductors with a head part permit for example that the head area of the head part which is generally larger than the head area of the pin-shaped conductor can be connected to an electrode connecting part, which in turn is connected with the anode or cathode of the battery cell.
The electrode connecting parts or respectively electrode connecting components can for example be firmly connected with the head part by welding, for example laser welding, resistance welding, electron beam welding, friction welding, ultrasonic welding, bonding, gluing, soldering, caulking, shrinking, grouting, jamming and crimping.
Materials finding use for the conductor, preferably the pin-shaped conductor are, for example, metals, in particular Cu, CuSiC or copper alloys, Al or AlSiC or aluminum alloys, Mg or magnesium alloys, gold or gold alloys, silver or silver alloys, NiFe, an NiFe-jacket with copper core, as well as a cobalt-iron alloy.
As aluminum or respectively aluminum alloys, the following may be used:

- EN AW-1050 A;
- EN AW-1350;
- EN AW-2014;
- EN AW-3003;
- EN AW-4032;
- EN AW-5019;
- EN AW-5056;
- EN AW-5083;
- EN AW-5556A;
- EN AW-6060; and
- EN AW-6061.

As copper or respectively copper alloys, the following may be used:

- Cu-PHC 2.0070;
- Cu-OF 2.0070;
- Cu-ETP 2.0065;
- Cu-HCP 2.0070; and
- Cu-DHP 2.0090.

Exemplary glass or glass ceramic materials for one embodiment are such materials which have a sealing temperature which is lower than the melting temperature of the conductor, in particular the essentially pin-shaped conductor and/or the housing component. For example, light metals may be used for pin-shaped conductors and as the materials of the housing component.
In the current application, metals which have a specific weight of less than 5.0 kilograms per cubic decimeter (kg/dm³) are understood to be light metals. The specific weight of the light metals is, for example, in the range of 1.0 kg/dm³to 3.0 kg/dm³.
If the light metals are additionally used as materials for the conductors, for example for the pin shaped conductor or the electrode connecting component, then the light metals further distinguish themselves through an electric conductivity in the range of 5×10⁶Siemens per meter (S/m) to 50×10⁶S/m. When used in compression seal feed-throughs the coefficient of expansion a for the range of 20° C. to 300° C. is moreover in the range of 18×10⁻⁶per degree Kelvin (K) to 30×10⁻⁶/K. Light metals generally have melting temperatures in the range of 350° C. to 800° C.
Exemplary glass compositions which can be used include the following components in mol-%:
P₂O₅35-50 mol-%, for example 39-48 mol-%;
Al₂O₃0-14 mol-%, for example 2-12 mol-%;
B₂O₃2-10 mol-%, for example 4-8 mol-%;
Na₂O 0-30 mol-%, for example 0-20 mol-%;
M₂O 0-20 mol-%, for example 12-20 mol-%, wherein M is K, Cs or Rb;
PbO 0-10 mol-%, for example 0-9 mol-%;
Li₂O 0-45 mol-%, for example 0-40 mol-%, or 17-40 mol-%;
BaO 0-20 mol-%, for example 0-20 mol-%, or 5-20 mol-%; and
Bi₂O₃0-10 mol-%, for example 1-5 mol-%, or 2-5 mol-%.
A further exemplary composition includes the following components in mol-%:
P₂O₅38-50 mol-%, for example 39-48 mol-%;
Al₂O₃3-14 mol-%, for example 4-12 mol-%;
B₂O₃4-10 mol-%, for example 4-8 mol-%;
Na₂O 10-30 mol-%, for example 14-20 mol-%;
K₂O 10-20 mol-%, for example 12-19 mol-%; and
PbO 0-10 mol-%, for example 0-9 mol-%.
The previously listed glass compositions distinguish themselves not only through a low sealing temperature and a low transition temperature Tg, but also in that they have sufficient resistance to battery-electrolytes, as used for example in lithium-ion batteries, and in this respect ensure the required long-term durability.
The glass materials disclosed above are stable phosphate glasses which, as known alkali-phosphate glasses have clearly a low overall alkali content.
The previously mentioned glass compositions contain lithium which is integrated in the glass structure. The glass compositions are hereby especially suited for lithium-ion storage devices which include electrolytes based on lithium, for example a 1 Molar (M) LiPF₆-solution, including a 1:1 mixture of ethylene-carbonate and dimethyl-carbonate.
Further exemplary compositions are low sodium or respectively sodium-free glass compositions, since the diffusion of the alkali-ions occurs in Na+>K+>Cs+ sequence and since therefore low sodium glasses to 20 mol-% Na₂O or respectively sodium-free glasses are especially resistant to electrolytes, especially those which are used in lithium-ion storage devices.
The resistance of the glass composition according to the present invention in regard to the battery electrolytes can be verified in that the glass composition in the form of a glass powder is ground to a granularity of d50=10 micrometers (μm) and is stored in the electrolytes for a predetermined time period, for example one week. d50 means, that 50% of all particles or granules of the glass powder are smaller than or equivalent to a diameter of 10 μm. A carbonate mixture of ethylene-carbonate and dimethyl-carbonate is used as non-aqueous electrolyte for example at a ratio of 1:1 M LiPF₆as conducting salt. After the glass powder is exposed to the electrolyte, the glass powder can be filtered off and the electrolyte be examined for glass elements which were leached from the glass. Herein it has been proven that with the phosphate glasses in the previously described composition ranges such leaching occurs surprisingly only to a limited extent of less than 20 mass percent; and that in special instances leaching of <5 mass percent is achieved. Moreover, such glass compositions have a thermal expansion a (20° C. to 300° C.)>14×10⁻⁶/K, for example between 15×10⁻⁶/K and 25×10⁻⁶/K. An additional advantage of the previously cited glass composition can be seen in that sealing of the glass with the surrounding light metal or respectively the metal of the conductor, in particular in the embodiment of a metal pin is possible also in a gaseous atmosphere which is not an inert gas atmosphere. In contrast to the previously used method, a vacuum is also no longer necessary for aluminum (Al)-fusing. This type of fusing can rather occur under atmospheric conditions. For both types of fusing nitrogen (N₂) or argon (Ar) can be used as inert gas.
As a pre-treatment for sealing the metal, the light metal is cleaned and/or etched, and if necessary is subjected to targeted oxidizing or coating. During the process, temperatures of between 300° C. and 600° C. are used at heating rates of 0.1 to 30 degrees Kelvin per minute (K/min) and dwell times of 1 to 60 minutes.
In addition to the feed-through through a housing component, a housing such as a battery cell housing, for example a battery cover, is cited which includes at least one feed-through according to the present invention, as well as a storage device, such as a battery with such a feed-through. In addition to the feed-through and the housing, the present invention also provides a method to equip a housing component with a feed-through. In a first arrangement of the present invention an essentially pin-shaped conductor is first sealed with an insulator, in particular a glass or glass ceramic material, resulting in the feed-through. The feed-through is then connected with the housing component by ultrasonic welding, for example hermetically sealed. Hereby the essentially pin-shaped conductor of the feed-through is guided through an opening in the housing component, and following insertion of the conductor, for example the essentially pin-shaped conductor through the housing component the feed-through is connected through ultrasonic welding with the housing component. In order to obtain a good result with the welding process with certain housing component materials, provision can be made for a contact material, for example an aluminum foil to be placed before welding, between the insulator and the housing component. It is also feasible for the ultrasonic welding to occur, for example, by a torsion sonotrode, and in particular from the direction of the housing component.
The battery is, for example, a lithium-ion battery. The lithium-ion battery may have a non-aqueous electrolyte, in particular on a carbonate basis, such as a carbonate mixture. The carbonate mixture can include a mixture of ethylene-carbonate and dimethyl-carbonate, with a conducting salt, for example LiPF₆.
The material for the housing component is, for example a metal, such as a light metal, for example aluminum, ALSiC, an aluminum alloy, magnesium or a magnesium alloy. For the battery housing as well as for the base body titanium and/or titanium alloys such as Ti6246 and/or Ti6242 can be used. Titanium is a material which is well tolerated by the body, so that it is used for medical applications for example in prosthetics. Due to its strength, resistance and low weight its use is also favored in special applications, for example in racing sports and for aerospace applications. Alternative materials for the housing component and/or the base body are also steel, stainless steel, standard steel, or high-grade steel.
Standard steels, used in particular are St35, St37 or St38. Exemplary high-grade steels are for example X12CrMoS17, X5CrNi1810, XCrNiS189, X2CrNi1911, X12CrNi177, X5CrNiMo17-12-2, X6CrNiMoTi17-12-2, X6CrNiTi1810 and X15CrNiSi25-20, X10CrNi1808, X2CrNiMo17-12-2 and X6CrNiMoTi17-12-2. However high-grade steels having material grade numbers (WNr.) according to Euro-Norm (EN) 1.4301, 1.4302, 1.4303, 1.4304, 1.4305, 1.4306, as well as 1.4307 are also feasible. These high-grade steels distinguish themselves through their effective weldability, in particular with laser welding or resistance welding, as well as deep-drawing properties.
Machining steels, for example with material number 1.0718, which possess a suitable coefficient of expansion and can be machined by turning, or construction steels, for example those having material number 1.0338, which can be processed by punching and can be used for the housing and/or the base body.
Alternatively to welding of the completed feed-through, in other words, of the insulator with one part of the housing component as described above, it is also possible to seal the insulator, in particular the glass or glass ceramic material with the housing component according to the current state of the art and to connect the pin-shaped conductor by ultrasonic welding with the insulator, for example hermetically sealed, after sealing of the housing component with the glass or glass ceramic material. This method is particularly advantageous if the conductor, in particular the pin-shaped conductor is equipped with a head part, so that the head part of the pin-shaped conductor can be joined with the glass or glass ceramic material by ultrasonic welding.
Alternatively, the insulator, or respectively the glass or glass ceramic, can be welded with the housing component, as can the essentially pin-shaped conductor be welded with the insulator, in particular by ultrasonic welding. This opens up considerable freedom in regard to material selection for the insulator. For example, glass ceramics or quartz glass could then be selected as material for the insulator.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a first arrangement of the present invention with a contact material;

FIG. 2 is a second arrangement of the present invention without a contact material;

FIG. 3 is a third arrangement of the present invention whereby the essentially pin-shaped conductor is equipped with a head part; and

FIGS. 4 a and 4 b illustrate a battery cell having an inventive feed-through.

Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate embodiments of the invention and such exemplifications are not to be construed as limiting the scope of the invention in any manner.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, and more particularly to FIG. 1, there is shown an electric feed-through according to the present invention through a housing component 3, as part of a battery cell housing. Battery cell housing 3 includes an opening 5 through which the conductor 7, in particular the essentially pin-shaped conductor 7, of feed-through 1 is guided. Housing part 3 includes an inside 10.1, and an outside 10.2. Inside 10.1 of housing part 3 faces toward the battery cell. Essentially pin-shaped conductor 7 protrudes over outside 10.2 of housing component 3.
The materials for housing component 3 as well as for conductor 7, in particular for pin-shaped conductor 7 can include different materials. The conductor 7, for example essentially pin-shaped conductor 7, may consist of copper or aluminum due to the high electric conductivity, whereas for example housing component 3 can be produced from high-grade steel to be welded later with other high-grade steel components. A light metal would also be possible alternatively for housing component 3.
In the current application metals which have a specific weight of less than 5.0 kilograms per cubic decimeter (kg/dm³) are understood to be light metals. The specific weight of the light metals is, for example in the range of 1.0 kg/dm³to 3.0 kg/dm³.
If the light metals are additionally used as materials for the conductors, for example for the pin shaped conductor or the electrode connection component, then the light metals further distinguish themselves through an electric conductivity in the range of 5×10⁶S/m to 50×10⁻⁶S/m. When used in compression seal feed-throughs the coefficient of expansion a of the light metal for the range of 20° C. to 300° C. is moreover in the range of 10×10⁻⁶/K to 30×10⁻⁶/K. Light metals generally have melting temperatures in the range of 350° C. to 800° C.
According to the invention, feed-through 1 includes, in addition to the essentially pin-shaped conductor 7, an insulator 20 which is formed, for example, of a glass or glass ceramic material. Essentially pin-shaped conductor 7 is hermetically sealed with insulator 20, in this case with the glass or glass ceramic material, in a first process step, for example through fusing or ultrasonic welding. Insulator 20 is, for example ring-shaped, for example a glass ring. Even though the glass ring is described here as being ring-shaped, this contour is in no way obligatory. Other contours for the insulator would also be possible, for example a polygon. The freedom in the selection of the contour becomes possible in particular in that the connection of insulator and housing can occur with the assistance of ultrasonic welding. After the feedthrough consisting of the conductor 7, in particular essentially pin-shaped conductor 7 as well as insulator 20 into which essentially pin-shaped conductor 7 is sealed has been produced, feedthrough 1 as a whole is connected with housing component 3 by welding, for example ultrasonic welding. If essentially pin-shaped conductor 7 is sealed with insulator 20, for example the glass ring, it is necessary to adapt the material properties of insulator 20, for example the glass or respectively the glass ring, to the material of essentially pin-shaped conductor 7, for example in regard to the sealing temperature. If insulator 20, for example the glass ring is connected with essentially pin-shaped conductor 7 by ultrasonic welding, the choice of the material for insulator 20 is even freer than in the aforementioned example, since then adaptation of the sealing temperature of the insulator 20 to essentially pin-shaped conductor 7 is not necessary. A glass ceramic or quartz glass can then be selected as the material for insulator 20. The connection of pre-manufactured feed-through 1 with housing component 3 occurs in the inventive arrangement illustrated in FIG. 1 through welding by a contact material 32 positioned between insulating material 20 and housing component 3. Use of contact material 32 advantageously achieves that the insulator can be connected not only with a ductile metal, such as for example soft aluminum by ultrasonic welding, but also with other less ductile metals such as high-grade steel or copper.
If pin-shaped conductor 7 is connected with insulator 20 through ultrasonic welding, contact material 32, in particular the aluminum foil can be wound around essentially pin-shaped conductor 7 (not illustrated). An aluminum foil is especially advantageous as a contact material for conductors consisting of Cu-materials.
Aluminum foil may advantageously serve as a contact material. Welding of insulators 20 of feed-through 1 with housing component 3 occurs, for example from the direction of the side of housing component 3 by a torsion sonotrode through ultrasonic coupling.
In addition to aluminum (Al), an aluminum alloy, AlSiC, possible materials for conductor 7, for example essentially pin-shaped conductor 7, are also Cu, CuSiC, a copper alloy, an NiFe-jacket with a copper component, silver, a silver as well as a cobalt-iron alloy.
Possible materials for insulator 20 are, for example glass or glass ceramic materials, such as melting glasses or solder glasses in the following compositions:
P₂O₅35-50 mol-%, for example 39-48 mol-%;
Al₂O₃0-14 mol-%, for example 2-12 mol-%;
B₂O₃2-10 mol-%, for example 4-8 mol-%;
Na₂O 0-30 mol-%, for example 0-20 mol-%;
M₂O 0-20 mol-%, for example 12-20 mol-%, wherein M is K, Cs or Rb;
PbO 0-10 mol-%, for example 0-9 mol-%;
Li₂O 0-45 mol-%, for example 0-40 mol-%, or 17-40 mol-%;
BaO 0-20 mol-%, for example 0-20 mol-%, or 5-20 mol-%; and
Bi₂O₃0-10 mol-%, for example 1-5 mol-%, or 2-5 mol-%.
An additional exemplary composition is as follows:
P₂O₅38-50 mol-%, for example 39-48 mol-%;
Al₂O₃3-14 mol-%, for example 4-12 mol-%;
B₂O₃4-10 mol-%, for example 4-8 mol-%;
Na₂O 10-30 mol-%, for example 14-20 mol-%;
K₂O 10-20 mol-%, for example 12-19 mol-%; and
PbO 0-10 mol-%, for example 0-9 mol-%.
The previously mentioned phosphate glasses have a high crystallization stability. The high crystallization stability of the phosphate glasses generally ensures melting of the glasses even at temperatures of <600° C.
The sealing temperature may for example be determined through the hemispherical temperature as described in R. Gorke, K. J. Leers: Keram. Z. 48 (1996) 300-305, or according to DIN 51730, ISO 540 or CEN/TS 15404 and 15370-1 whose disclosure content is incorporated in its entirety into the current patent application. According to DE 10 2009 011 182A1 the hemispherical temperature can be determined in a microscopic process by using a heating stage microscope. It identifies the temperature at which an originally cylindrical test body melts into a hemispherical mass. A viscosity of approximately log η=4.6 deciPascals (dPas) can be allocated to the hemispherical temperature, as can be learned from appropriate technical literature. If a crystallization-free glass, for example in the form of a glass powder, is melted down and then cooled so that it solidifies, it can then normally be melted down again at the same melting temperature. For a bonded connection with a crystallization-free glass this means that the operating temperature to which the bonded connection is continuously subjected may not be higher than the sealing temperature. Glass compositions as utilized in the current application are generally often produced from a glass powder which is melted down and which, under the influence of heat, provides the bonded connection with the components which are to be joined. Generally, the sealing temperature or melting temperature is consistent with the level of the so-called hemispherical temperature of the glass. Glasses having low sealing temperatures or respectively melting temperatures are also referred to as solder glass. Instead of fusing or melting temperature, one speaks of solder temperature or soldering temperature in this instance. The sealing temperature or respectively the solder temperature may deviate from the hemispherical temperature by +20K.
Table 1 below illustrates exemplary phosphate glasses:

TABLE 1

AB1	AB2	AB3	AB4	AB5	AB6	AB7	AB8

Mol-%
P₂O₅	47.6	43.3	43.3	43.3	37.1	40.0	42.0	46.5
B₂O₃	7.6	4.8	4.7	4.8	4.9	6.0	6.0	7.6
Al₂O₃	4.2	8.6	8.7	2.0	2	12.0	12.0	4.2
Na₂O	28.3	17.3				15.0	16.0	28.3
K₂O	12.4	17.3	17.3			18.0	19.0	12.4
PbO						9.0
BaO		8.7	8.7	15.4	14
Li₂O			17.3	34.6	42.1
Bi₂O₃							5	1
Hemispherical	513	554	564	540	625		553	502
Temperature
(° C.)
α (20-300° C.)	19	16.5	14.9	13.7	14.8	16.7	16.0	19.8
(10⁻⁶/K)
Tg (° C.)	325	375	354	369	359	392	425	347
Density	2.56					3	3.02	2.63
[g/cm³]
Leaching	18.7	14.11	7.66	12.63	1.47	3.7	29.01	8.43
In Ma-%
Weight	10.7	0.37	0.1	0.13	0.13	n.b.	0.006/0.001	0.45/0.66
Loss (%)
after 70 h
in 70° C.-
water

Example 1 (AB1) in Table 1 is suited in particular for aluminum/aluminum sealing, that is sealing of an aluminum pin in the embodiment of a conductor into a surrounding aluminum base body.
In addition to leaching, water resistances of the individual glasses were also determined. The hydrolytic resistance tests were conducted so that melted down glass samples were produced (2×2 centimeters (cm), height: ˜0.5 cm) which were stored in 200 milliliters (mL) water at 25° C. and 70° C. for 70 hours. Subsequently the material loss in weight % was determined and listed in the table.
Example 6 (AB6) in Table 1 is, for example suitable for Cu/Al sealing, that is sealing of a copper pin as a conductor into a surrounding aluminum base body.
Even though some of the examples have coefficients of expansion which tend to be too low for bonding with copper (Cu), it is clear that a high lithium-share in the molten mass can be dissolved without the glass of such a glass composition becoming unstable.
Examples 7 and 8 (AB7 and AB8) distinguish themselves in that they contain Bi₂O₃instead of PbO, as in example 6 (AB6).
Surprisingly it has been shown that the hydrolytic resistance can be clearly increased by Bi₂O₃. For example, by adding 1 mol-% Bi₂O₃a 10-times higher water resistance would be achieved in example 8 (AB8) than in example 1 (AB1). Bi₂O₃can in particular also be used in place of PbO according to example 6 (AB6). Due to their environmental compatibility, compositions which except for contaminants are free of lead, meaning that they include less than 100 parts per million (ppm), for example less than 10 ppm, or less than 1 ppm of lead are particularly feasible.
Table 1 shows the composition in mol-%, the transition temperature Tg as defined for example in “Schott Guide to Glass, second edition, 1996, Chapman & Hall, pages 18-21, the total leaching in mass percentage (Ma-%), the expansion coefficient α in 10⁻⁶per degree Kelvin in the range of 20° C.-300° C., as well as the density in g/cm³. The total leaching is determined as described below. First, the glass composition is ground to glass powder having a d50=10 micrometers (μm) granularity, and is exposed for one week to the electrolyte consisting of ethylene-carbonate/dimethyl-carbonate at a ratio 1:1, with 1 Molar LiPF₆in the form of conducting salt dissolved therein and after this time is examined for glass components which were leached from the glass. “n.b.” in Table 1 denotes unknown properties.
Referring now to FIG. 2, there is shown a second arrangement, whereby no contact material is used in the electrical feed-through. Identical components as those in FIG. 1 are identified by the same reference numbers.
An arrangement without the use of a contact foil, as shown in FIG. 1, is considered especially when conductor 7, in particular pin-shaped conductor 7, or respectively housing component 3, consist of aluminum. In such a case the additional layer can be foregone, since the metals which are to be welded are ductile metals. The manufacturing process occurs again as shown in FIG. 1—first pin-shaped conductor 7 is sealed with the insulator 20, for example the glass or glass ceramic material, or through ultrasonic welding and after producing feed-through 1 consisting of essentially pin-shaped conductor 7 and insulator 20, the entire feedthrough 1 with housing component 3 is connected by a welding process, for example through ultrasonic welding. In contrast to FIG. 1, a direct sealing of insulator 20 with inside 10.1 of housing component 3 occurs hereby. Side 10.2 of the housing component represents the outside, side 10.1 the inside, that is the side which in arranging the housing component faces the inside of the battery, that is the battery cell as part of a battery cell housing. Essentially pin-shaped conductor 7 is again guided to the outside through opening 5 in housing component 3.
Referring now to FIG. 3, there is shown an alternative arrangement of the electric feed-through according to the present invention. In the arrangement according to FIG. 3 identical components as shown in FIGS. 1 and 2 are identified with reference numbers increased by 100. Feed-through 101 now includes an essentially pin-shaped conductor 107 with a head part 130. Surface F of the head part is substantially larger than surface FS of the essentially pin-shaped conductor 107.
In contrast to the arrangements according to FIGS. 1 and 2, the insulator 120, in particular the glass or glass ceramic material 120 according to FIG. 3, is introduced between area F of head part 130 of essentially pin-shaped conductor 107 and inside 110.1 of the housing part.
The conductor 107, in particular essentially pin-shaped conductor 107 according to FIG. 3 with a head part 130 has the advantage that electrode connecting components can be attached, for example through contact on the inside surface, that is on surface Fl of head part 130 facing the battery cell. Protrusion 140 extending beyond head part 130 of pin-shaped conductor 107 can be utilized for an electrode connecting part, for example for centering or twist lock. The electrode connecting part which is not illustrated and which is to be connected with the head part 130 of essentially pin-shaped conductor 107 is connected to the cathode or respectively the anode in the battery cell. In contrast to the arrangement in FIGS. 1 and 2, inventive feed-through 1, shown in FIG. 3, can be connected with the housing part 103 in such a manner that first insulator 120, for example in the embodiment of a ring-shaped insulator, such as a glass ring is sealed with housing component 103 for example in accordance with conventional methods, or by ultrasonic welding. After sealing or welding of insulator 120 with housing outside 110.1 essentially pin-shaped conductor 107 is guided through opening 105 in housing component 103, as well as the opening in glass ring 120. After having been guided through the opening in glass ring 120 and in housing component 103, essentially pin-shaped conductor 107 is connected in particular in the region of inside surface F of the head part with glass ring 120 by welding, for example ultrasonic welding. As previously discussed, welding of conductor 107 with insulator 120, as well as of insulator 120 with housing component 103 is advantageous since the materials, in particular for the insulator can be freely selected. Quartz glass and glass ceramic are also suitable as materials.
In addition to glasses and glass ceramic materials, ceramic materials may also be used as insulators with the inventive feed-throughs. When using ceramics they are connected with the housing component 103 or essentially pin-shaped conductor 107, for example, with a metallic solder.
Referring now to FIGS. 4 a and 4 b, there are shown complete battery cells with integrated feed-throughs. FIGS. 4 a and 4 b hereby illustrate an arrangement whereby the essentially pin-shaped conductor is equipped with a head part. FIG. 4 a shows the basic structure of a battery cell 1000. Battery cell 1000 includes a housing 1100 with side walls 1110 and a cover part 1120. Openings 1130.1, 1130.2 are worked into the opening of cover part 1120 of housing 1100, for example by stamping. The essentially pin-shaped conductors 1140.1, 1140.2 of the feedthroughs are guided through the two openings 1130.1, 1130.2.
FIG. 4 b shows a detailed section of battery cover 1120 with opening 1130.1 and therein inserted feed-through 1140.1. Feed-through 1140.1 includes pin-shaped conductor 2003, as well as a base body 2200 or respectively insulator 2200. Base body 2200 or respectively the insulator 2200 in the current example is ring-shaped and in the current example is essentially in the embodiment of a glass or glass ceramic ring. Pin-shaped conductor 2003 with a head part is connected with base body 2200 through sealing or ultrasonic welding. After joining of pin-shaped conductor 2003 by sealing or ultrasonic welding with base body 2200, pin-shaped conductor 2003 is guided through opening 1130.1 of housing 1100. Afterwards, the base body or respectively insulator 2200 is joined by sealing or ultrasonic welding with inside 1110.1 of housing 1100 in the region of cover part 1120.
An electrode connecting part 2020 can be joined with head part 2130 of the essentially pin-shaped conductor (for example by means of welding, in particular laser welding, resistance welding, electron beam welding, friction welding, ultrasonic welding). The electrode connecting part 2020 again serves as the connection to either the cathode or anode of electrochemical cell 2004 of battery 1000. The electrochemical cell of the lithium-ion battery is also referred to as battery cell 2004. Housing 1100 surrounding battery cell 2004 is in the embodiment of a battery cell housing.
Based on the inventive flat structure of the pin-shaped conductor 2003 with head part 2130 as illustrated in FIG. 4 b it is possible to minimize the unused space inside the battery cell housing 1100.
Materials for the conductor are in particular metals, for example aluminum, AlSiC, copper, CuSiC, magnesium, silver, gold, an aluminum alloy, a magnesium alloy, a copper alloy, a silver alloy, a gold alloy or NiFe-alloys.
The base body and/or the housing component include, for example a light metal, high-grade steel, steel, stainless steel, in particular aluminum, AlSiC, an aluminum alloy, magnesium, a magnesium alloy, titanium or a titanium alloy.
With the pin-shaped conductor with a head part and the thereto connected electrode-connecting components a very high stability, in particular against mechanical stresses such as vibration is achieved. All embodiments of the feed-through discussed in this application have in common that an adaptation of the insulator in regard to the material of the essentially pin-shaped conductor, as well as to the housing component, is no longer necessary. Due to the low temperatures occurring with ultrasonic welding it is possible, to connect components having a clearly different thermal expansion and/or melting temperature. Also the wetting properties of the melted glass only play a subordinate roll, at least on one of the contact materials where no sealing takes place. The connection by ultrasonic welding hereby provides freedoms regarding the choice of materials, as well as freedom in the selection of the insulator, in particular the glass or glass ceramic material. It is possible to use glass or respectively glass ceramic materials which are resistant to mediums, for example, to the electrolytes of the battery cell.
The discussed feed-throughs are especially suited for use electric feed-throughs for batteries, in particular lithium-ion batteries.
With the feed-through according to the present invention, a battery housing can be provided which is hermetically sealed even in the event of a deformation of the battery housing, as opposed to plastic feed-throughs which have a tendency to crack formation. On batteries with battery housings which are equipped with an inventive feed-through an especially high fire resistance is hereby provided in the event of a vehicle accident. This is particularly relevant in the use of batteries, such as lithium-ion batteries in the automobile industry.
While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.

Claims

What is claimed is:

1. A feed-through, comprising:

a housing component of a housing, said housing component having at least one opening;

an insulator;

at least one conductor which is at least partially surrounded by said insulator, said at least one conductor being guided through said at least one opening of said housing component; and

an ultrasonic welding connection between said at least one conductor and at least one of said housing component and said insulator.

2. The feed-through according to claim 1, wherein said housing is a battery cell housing.

3. The feed-through according to claim 1, wherein said at least one conductor is an essentially pin-shaped conductor.

4. The feed-through according to claim 1, wherein said insulator is a material which is one of a glass material and a glass ceramic material.

5. The feed-through according to claim 3, wherein said conductor includes a head part and said insulator is positioned between said head part and said housing component.

6. The feed-through according to claim 3, wherein said conductor includes a metal.

7. The feed-through according to claim 6, wherein said metal is one of copper, copper silicon carbide (CuSiC), a copper alloy, aluminum, aluminum silicon carbide (AlSiC), an aluminum alloy, nickel-iron (NiFe), an NiFe jacket with a copper core, magnesium, a magnesium alloy, silver, a silver alloy, gold, a gold alloy and a cobalt-iron alloy.

8. The feed-through according to claim 4, wherein said glass or ceramic glass material of said insulator includes in Mole (mol) percent (%):

P₂O₅35-50 mol-%;

Al₂O₃0-14 mol-%;

B₂O₃2-10 mol-%;

Na₂O 0-30 mol-%;

M₂O 0-20 mol-%, wherein M is one of K, Cs and Rb;

PbO 0-10 mol-%;

Li₂O 0-45 mol-%;

BaO 0-20 mol-%; and

Bi₂O₃0-10 mol-%.

9. The feed-through according to claim 8, wherein said glass or glass ceramic material of said insulator includes (in mol-%):

P₂O₅39-48 mol-%;

Al₂O₃2-12 mol-%;

B₂O₃4-8 mol-%;

Na₂O 0-29 mol-%;

M₂O 12-20 mol-%;

PbO 0-9 mol-%;

Li₂O 0-40 mol-%;

BaO 0-20 mol-%; and

Bi₂O₃0-5 mol-%.

10. The feed-through according to claim 9, wherein said glass or glass ceramic material of said insulator includes (in mol-%):

Li₂O 17-40 mol-%;

BaO 5-20 mol-%; and

Bi₂O₃2-5 mol-%.

11. The feed-through according to claim 8, wherein said glass or glass ceramic material of said insulator includes (in mol-%):

P₂O₅38-50 mol-%;

Al₂O₃3-14 mol-%;

B₂O₃4-10 mol-%;

Na₂O 10-30 mol-%;

K₂O 10-20 mol-%; and

PbO 0-10 mol-%.

12. A housing, comprising:

a housing component having at least one opening;

at least one feed-through including:

an insulator;

at least one conductor which is at least partially surrounded by said insulator, said at least one conductor being guided through said at least one opening; and

13. The housing according to claim 12, wherein the housing is for a battery cell.

14. The housing according to claim 13, the housing including a metal.

15. The housing according to claim 14, wherein said metal is a light metal.

16. The housing according to claim 15, wherein said light metal is one of aluminum, an aluminum alloy, magnesium, a magnesium alloy, titanium, a titanium alloy, steel, a high grade steel, a stainless steel and a tool steel.

17. A storage device, comprising:

a feed-through including:

a housing having at least one opening;

an insulator;

at least one conductor which is at least partially surrounded by said insulator, said at least one conductor being guided through said at least one opening in said housing; and

18. The storage device according to claim 17, wherein the storage device is an accumulator.

19. The storage device according to claim 18, wherein said accumulator is a lithium-ion battery with at least one battery cell surrounded by said housing.

20. The storage device according to claim 19, wherein said housing is a battery cell housing.

21. The storage device according to claim 17, wherein said at least one conductor is an essentially pin-shaped conductor.

22. The storage device according to claim 17, wherein said housing includes one of a metal, a high-grade steel, steel, stainless steel, tool steel and a light metal.

23. The storage device according to claim 22, wherein said light metal is one of aluminum, aluminum silicon carbide (AlSiC), an aluminum alloy, magnesium, a magnesium alloy, titanium and a titanium alloy.

24. A method of providing a housing component with a feed-through, the method comprising the steps of:

one of sealing and joining a conductor with an insulator using ultrasonic welding to form a feed-through; and

using ultrasonic welding to connect said feed-through with the housing component.

25. The method according to claim 24, wherein said conductor is an essentially pin-shaped conductor.

26. The method according to claim 24, wherein said insulator is one of a glass material and a glass ceramic material.

27. The method according to claim 24, wherein said connecting step further comprises the step of hermetically sealing said feed-through with said housing component.

28. The method according to claim 24, further comprising the step of placing a contact material between said insulator and said housing component prior to said connecting step using said ultrasonic welding.

29. The method according to claim 28, wherein said contact material is an aluminum foil.

31. A method of providing a housing component with a feed-through, the method comprising the steps of:

using ultrasonic welding to one of seal and join an insulator with the housing component; and

using ultrasonic welding to join a conductor with said insulator.

32. The method according to claim 31, wherein said insulator is one of a glass material and a glass ceramic material.

33. The method according to claim 32, wherein said conductor is an essentially pin-shaped conductor.

34. The method according to claim 31, wherein said conductor is hermetically sealed with said insulator.

35. The method according to claim 33, wherein said conductor includes a head part, said step of joining said conductor with said insulator further comprising the step of joining said head part with said insulator using ultrasonic welding.