Autoclavable electrical feedthroughs and glass for autoclavable electrical feedthroughs

Abstract

It provides an autoclavable electrical feedthrough. [Solution] The present invention relates to an electrical feedthrough comprising a substrate 20 including at least one through-opening 22 extending through the substrate, and an insulating material 30 housed in the through-opening extending through the substrate, which is made of or contains glass. Furthermore, the electrical feedthrough comprises at least one electrical conductor 40 extending through the insulating material housed in the through-opening, wherein the substrate contains titanium or a titanium alloy. The electrical feedthrough is characterized in that the glass is a special alkaline earth metal oxide-containing lanthanum borate glass that has improved hydrolysis resistance and can withstand the harsh conditions of multiple autoclave treatments. The feedthrough with glass has at least 1 × 10⁻¹⁰ 9 It has an insulating resistance in ohms.

Description

[Technical Field]

[0001] The present invention relates to an autoclavable electrical feedthrough comprising a metal-containing substrate, wherein an insulating material comprising glass having an electrical conductor extending through it is housed within the substrate. Furthermore, the present invention relates to glass for such an autoclavable electrical feedthrough.

[0002] Electrical feedthroughs (glass-metal-feedthroughs), comprising an outer metal substrate and an inner glass component acting as an insulator, through which one or more conductors extend, are used in many applications, particularly in airtight wall components such as housing elements. Corresponding components are used, for example, in the medical technology field, in electrical connectors and airtight housing components / seals of medical devices such as endoscopes and surgical instruments, which are used for examination, surgery, and treatment, and come into contact with the body for only a short time, but for that purpose, more often, can be reused after proper sterilization. One application area is, for example, robotic surgery. Further application areas include implantable medical devices (IMDs), applications requiring lightweight structures (e.g., the aerospace sector), and many other fields. While different requirement profiles may need to be considered depending on the application area, there are also commonalities regarding the optimization and improvement of known solutions.

[0003] The use of feedthroughs in medical technology devices presents specific requirements. Generally, in this field, feedthroughs are incorporated into components made of titanium or titanium alloys. Because titanium is an extremely reactive material, glass sealing of titanium or titanium alloys presents unique challenges. With high silicate content glass, at the typical glass sealing temperatures of approximately 700-900°C required for glass-metal-feedthrough manufacturing, titanium reacts with SiO2 to form titanium silicide, and this reaction generates bubbles at the glass-metal interface. Furthermore, it must be considered that pure titanium has a phase transition temperature of 880°C (transition from low-temperature modified alpha titanium to high-temperature modified beta titanium). For titanium alloys, such as titanium grade 5 (TiAl6V4), this phase transition temperature is higher, but the reaction mechanism at the glass interface is the same. Therefore, the glass composition must be optimized for lower glass sealing temperatures so that glass sealing can be performed below the transition reaction that impairs sealing performance.

[0004] Furthermore, it is generally desired that devices or components with glass-metal-feedthroughs usable in medical technology be autoclavable, i.e., sterilizable at high vapor pressure and temperatures >100°C, thereby allowing repeated use of the device for diagnosis or treatment on or within the human or animal body, or for testing biomaterials in a laboratory, etc., which constitutes one aspect of the problem addressed by the present invention. Repeated autoclaving cycles or operations, i.e., repeated autoclaving, place a high load on the materials used, particularly the glass in the feedthrough. Known glass used in medical device feedthroughs has relatively low autoclavability, i.e., low chemical stability of the glass, so the insulating resistance provided by the glass in the feedthrough decreases after a relatively small number of autoclaves, rendering the device unusable. Therefore, in this respect, frequently used medical devices that do not remain permanently in the body and must be sterilized many times after use are subject to stricter requirements than implantable medical devices (IMDs), such as pacemakers, defibrillators, pumps, etc.

[0005] Furthermore, it is generally desired that the components used do not exhibit toxic effects even when they may come into contact with bodily fluids, at least intermittently, or (in the case of implantable devices) continuously. This applies not only to substrates and electrical conductors, but especially to glass (due to elution effects), and for this reason, it may be conceivable here to perform elution tests in advance, particularly before conducting more specific qualification tests for medical devices and implantable devices. Modern feedthroughs for medical applications typically contain boron-aluminum silicate glass. Because they require high stability in aqueous solutions, they often do not contain alkali metals and have high content of B2O3, Al2O3, and alkaline earth metal oxides (CaO, MgO, SrO). In known elution tests, elution in water is generally determined by determining the dissolution rate by the weight loss of a polished glass sample after a two-week residence time in deionized water at 70°C (see below). It is believed that the lower the elution rate of the sample, the greater the resistance of the glass composition to chemical reactions by moisture, water, or aqueous bodily fluids (i.e., the greater its water resistance).

[0006] However, autoclavable components with electrical feedthroughs impose even stricter requirements on the chemical resistance of the glass. Glass is subjected to significant stress during steam sterilization at high temperatures (typically 110-140°C). If hydrolysis resistance is low, glass components will continuously dissolve during repeated autoclave cycles, causing the insulation resistance of the feedthrough to fall below a critical value, thus rendering the equipment unsafe to use.

[0007] A further requirement for glass suitable for feedthroughs in medical technology equipment is its coefficient of thermal expansion, which should ideally be harmonized with the metal components used and the desired pressure conditions within the feedthrough.

[0008] U.S. Patent Publication No. 2009 / 0229858, U.S. Patent Publication No. 2020 / 0261732, and U.S. Patent Publication No. 2021 / 0290964 disclose implantable medical devices comprising a titanium component with a glass-metal-feedthrough, wherein the glass is an alkaline earth metal-containing boron-aluminum silicate glass and may have fillers to adjust the coefficient of thermal expansion (CTE). Thus, composite materials are disclosed. CTE adjustment is a major theme in U.S. Patent Publication No. 2020 / 0261732. U.S. Patent Publication No. 2021 / 0290964 teaches how the CTE and modulus of the composite material are altered by differences in the content of crystalline fillers, specifically by the addition of Al2O3 particles. The glass disclosed in that specification has low resistance to vapor pressure sterilization at temperatures. However, since implantable medical devices only need to withstand a few sterilization cycles before remaining permanently in the body, such glass is sufficient for these applications despite its poor hydrolysis resistance. However, such glass is not suitable for components with feedthroughs that will be autoclaved hundreds of times. In other words, the autoclavability of feedthroughs with glass suitable for implantable medical devices does not meet the requirements imposed on frequently used medical devices that do not remain in the body and must be sterilized many times after use.

[0009] U.S. Patent No. 5,648,302 discloses a glass composition for airtight glass-metal-feedthroughs for implantable medical devices having titanium and titanium alloys that are resistant to aqueous solutions (determined by an elution test of polished glass samples in deionized water at 70°C). The glass is barium lanthanum borate glass. Due to the high BaO content of the glass, such glass is highly corroded by water at high temperatures (>100°C), meaning that the glass has relatively low hydrolysis resistance at high temperatures present during autoclaving, and that glass-metal-feedthroughs can only be autoclaved a few times (e.g., <100°C) before the insulation resistance becomes insufficient. This is sufficient for implantable applications but not for devices that can be reused multiple times, such as in medical technology.

[0010] U.S. Patent No. 5,693,580 discloses glass compositions for airtight glass-metal-feedthroughs for implantable medical devices, having high resistance to aqueous solutions (determined by elution tests of polished glass samples in deionized water at 70°C). The glass is calcium lanthanum borate glass. The glass disclosed in the patent does not contain SiO2 to avoid the formation of titanium silicides. These glasses also exhibit low hydrolysis resistance at temperatures >100°C, meaning they do not maintain autoclave stability after multiple cycles.

[0011] U.S. Patent No. 10544058 discloses a special composite material containing alkali metal aluminosilicate glass and fillers. Due to the alkali metal and filler content, which can lead to a certain degree of porosity, such glass is not well-suited for applications requiring high autoclave stability and feedthrough.

[0012] Furthermore, implantable medical devices, such as cochlear implants, are known, including a sealed housing with electronic components and a feedthrough using ceramic as an insulating material, as described in U.S. Patent No. 2015 / 0088226.

[0013] International Publication No. 2023 / 016964 describes a feedthrough comprising a titanium or titanium alloy substrate having a feedthrough, glass as an insulating material, and at least one electrical conductor, wherein the glass forms a specific contact angle with the metal component. The alkali metal aluminosilicate glass disclosed in that publication has relatively low resistance to repeated autoclaving due to its alkali metal content.

[0014] In general, it is desirable to improve the resistance of the feedthrough described at the beginning, for example, to chemical and / or physical influences, and to improve the sealing of insulating materials to electrical conductors that extend to and / or through the surrounding substrate, which constitutes the object of the present invention. In particular, the object of the present invention is to provide feedthrough that maintains the required insulation resistance while being autoclavable multiple times. Furthermore, it is an object to provide a glass suitable for multiple autoclaving processes and suitable for bonding with titanium or titanium alloy substrates.

[0015] Disclosure of the invention To solve this problem, the present invention provides an electrical feedthrough comprising a substrate including at least one through-opening extending through the substrate, an insulating material housed in the through-opening extending through the substrate, and at least one electrical conductor extending through the insulating material housed in the through-opening, wherein the substrate comprises titanium or a titanium alloy, and the insulating material comprises or consists of glass.

[0016] The glass is lanthanum borate glass, and lanthanum borate glass contains the following components (in mole percent on an oxide basis): B2O322.0~37.0 La2O3 1.0~12.0 SiO2 10.5~23.0 RO(MgO+CaO+SrO) 29.0~45.0 Nb2O5 + ZrO2 + TiO2 + Ta2O5 0.1~6.0 SiO2 / (Nb2O5+ZrO2+TiO2+Ta2O5) >3.00 Includes, When the glass is measured for hydrolysis resistance in accordance with DIN ISO 720:2021-12, it has a Na2O equivalent value of <1250 μg / g, and therefore, feedthroughs having such glass have long-term autoclave resistance. Preferably, the insulation resistance of the feedthrough after 300 autoclave cycles is at least 1 × 10⁻⁶. 9 It is Ohm.

[0017] The inventors have surprisingly found that the hydrolysis resistance of lanthanum borate glass to the harsh conditions present during autoclave processing can be significantly improved when the glass has a relatively high proportion of SiO2 and a specific proportion of Nb2O5 and / or ZrO2 and / or TiO2 and / or Ta2O5 for glass-metal feedthrough with titanium or a titanium alloy. The components mentioned act individually or in combination, i.e., at least two of these components, as resistance improvers for hydrolysis resistance. In other words, the resistance improver has at least one component selected from the group including Nb2O5, ZrO2, TiO2, and Ta2O5. According to the present invention, these components are constituent elements of the glass, i.e., fillers added later. Therefore, in contrast to glass or insulating materials having fillers, the glass or insulating material according to the present invention has only a few pores in the feedthrough, which is advantageous for hermetic seals. Such glass feedthroughs have the advantage of being resistant to long-term autoclaving and can therefore be used in medical devices, components, etc., that must be autoclavable multiple times. Advantageously, the glass or insulating material does not have pores.

[0018] The hydrolysis resistance of the glass is measured using glass grit at 121 °C, i.e., at a high temperature similar to that during autoclave treatment, in accordance with DIN ISO 720:2021-12. Glass grit with a defined particle size and surface is held in distilled water in an autoclave at 121 °C for 30 minutes. The resistance is measured and expressed as the volume of acid required to titrate the alkali solution extracted from the glass per unit mass, and can also be expressed as the amount of sodium oxide corresponding to this volume of acid. In the context of the present invention, it is adjusted to the sodium oxide conversion value expressed as the mass of sodium oxide per 1 g of glass grains.

[0019] The glass according to the present invention has a Na₂O conversion value of <1250 μg / g. Advantageous configurations have a Na₂O conversion value of <1100 μg / g or <1000 μm / g. A particularly advantageous variant has a Na₂O conversion value of <930 μg / g, whereby, in accordance with DIN ISO 720:2021-12, it will be classified in class HGA 3. Advantageously, this glass has a Na₂O conversion value, and thus a feedthrough having such glass has long-term autoclave treatment resistance.

[0020] "Long-term autoclave treatment resistance" in the context of the present invention means that the feedthrough can be autoclaved at least 300 times for 20 minutes at a temperature of 135.5 °C and a pressure of 2.16 bar while maintaining sufficient insulation resistance. Thereby, this feedthrough meets the requirements imposed on frequently used healthcare devices, medical products and laboratory equipment. The resistance to repeated autoclave treatment is determined as described later in relation to the examples. This is referred to in order to avoid repetition.

[0021] Advantageously, the insulation resistance of the feedthrough remains at least 1×10 even after 300 or at least 300 autoclave treatments. 9It is ohmic. If the insulation resistance falls below this limit value, the conductors (also called pins) within the feed-through and the external conductors are no longer sufficiently insulated, and as a result, there is a possibility of leakage current and even short circuits. With the mentioned minimum insulation resistance, equipment including a feed-through having long-term autoclave treatment resistance according to the present invention can operate safely. A feed-through that can withstand at least 300 autoclave treatment operations under the above conditions can also withstand performing high-temperature and / or high-pressure and / or long-term sterilization treatments many times more than the above feed-through.

[0022] Advantageously, the insulation resistance of the feed-through remains at least 1×10 9 ohms even after at least 600 times, preferably at least 900 times, more preferably at least 1200 times of autoclave treatment, and the sterilization treatment was carried out under the above-mentioned conditions (that is, 135.5 °C, 2.16 bar, and 20 minutes) respectively.

[0023] The insulation resistance, which is an indicator of autoclave treatment stability, is measured using a feed-through with a glass-sealed conductor in accordance with MIL-STD-883, Method.1003. In this case, the electrodes are arranged on the substrate and the conductor. The measurement is carried out one by one at a voltage of 100 V and a measurement time of 5 seconds at room temperature (20 °C) and the humidity under typical laboratory conditions (relative humidity 50% ± 10%) respectively. In order to determine the insulation resistance, in the context of the present invention, an electrical feed-through having the following dimensions is always used: the diameter of the through-opening in the substrate accommodating the insulating material with the conductor is 1.8 mm, the diameter of the conductor is 0.5 mm, and the glass-sealing length is 3.0 mm. Of course, the dimensions may be different in applications.

[0024] Regarding airtightness, advantageously, after 300 or at least 300 autoclave treatments, the helium leakage rate determined by a pressure difference of 1 bar for the feed-through is less than 1·10 -8 mbar·l / s, advantageously less than 1 - 10 -9 mbar·l / s, particularly preferably less than -10 -10It can be assumed that the airtightness is characterized by being less than mbar·l / s. The airtightness of the feedthrough can be determined, for example, by a helium leak test, according to MIL-STD-883, Method.1014 A4. Even after at least 600 autoclave cycles, preferably at least 900, and preferably at least 1200 autoclave cycles, it may still be advantageously 1.10 -8 A helium leakage rate of less than mbar·l / s is achieved. This means that the insulating material contained in the through-opening of the substrate is in close contact with the substrate and / or at least one electrical conductor. Advantageously, during the manufacturing of the feedthrough, the glass melts and vitrifies on the metal component, thereby providing a lasting, airtight, sealed glass-metal bond.

[0025] glass composition The characteristics and advantageous configurations of the compositions described below contribute to the advantageous properties of the glass according to the present invention. This description applies to both the glass and the feedthroughs equipped with such glass. In alkaline earth metal oxide-containing lanthanum borate glass, it has been found that the chemical resistance of the glass can be improved, particularly by a defined content of one or more specific components acting as resistance enhancers as glass components, and a certain proportion of SiO2, so that it can withstand the harsh conditions of repeated autoclave treatments. Furthermore, this glass satisfies further desired advantageous properties, such as, for example, the airtight seal of the feedthrough, the glass sealing temperature for manufacturing the feedthrough, and thermal expansion.

[0026] The glass sealing temperature for manufacturing glass-metal-feedthroughs is advantageously ≤950°C, advantageously ≤930°C, advantageously ≤900°C, and advantageously ≤880°C. In this case, the glass sealing temperature is the temperature at which a hermetically sealed feedthrough can be successfully manufactured. One indicator of the glass sealing temperature is the half-spherical temperature. Empirically, the glass sealing temperature is approximately the same as the half-spherical temperature, or a few degrees higher, for example, at least 5°C, or at least 25°C, or at least 50°C, or at least 70°C higher.

[0027] The glass according to the present invention contains B2O3. Advantageously, this component is present in a proportion of 22.0 to 37.0 mol%. B2O3 is an important glass component for glass formation and hydrolysis resistance. Furthermore, B2O3 can form a Ti-B layer with titanium, which leads to a more chemically and mechanically stable bond between the titanium-containing component and the glass. Therefore, this component is advantageously present in the glass in a proportion of at least 22.0 mol% or at least 22.5 mol%. It is desirable not to exceed the upper limit of 37.0 mol%, because otherwise, the content of other glass components, particularly alkaline earth metal oxides and / or Al2O3, would have to be reduced, which would lead to a deterioration of the desired glass properties, such as a decrease in the coefficient of thermal expansion or an increase in the glass sealing temperature. In some advantageous modifications, the glass may have a B2O3 content of at least 25.0 mol%, at least 27.0 mol%, or at least 28.0 mol%. In favorable formulations, the content may be at most 37.0 mol% or at most 35.0 mol%. In some favorable variations, 31.0 mol% or less may also be appropriate upper limits.

[0028] The glass according to the present invention contains La2O3 in a proportion of 1.0 to 12.0 mol%. La2O3 is a glass component that improves glass flow during melting and lowers the glass sealing temperature, thereby enabling glass sealing of conductors in a substrate at a relatively low temperature. Furthermore, this component can increase the thermal expansion coefficient of the glass. For these reasons, this component is advantageously included in the glass at a concentration of at least 1.0 mol%. It is desirable not to exceed the upper limit of 12.0 mol%, because otherwise the glass sealing temperature would become too high. In advantageous embodiments, the glass has a La2O3 content of at least 1.5 mol% or at least 2.0 mol%. In advantageous configurations, the content may optionally be at most 11.0 mol%, at most 10.0 mol%, at most 9.0 mol%, at most 8.0 mol%, or less than 8.0 mol%.

[0029] The glass according to the present invention contains SiO2 in a content of 10.5 to 23.0 mol%. It is desirable that the lower limit is not below 10.5 mol%, because otherwise the hydrolysis resistance of the glass, and consequently the autoclave resistance of the feedthrough, will not be achieved. It is also desirable that the upper limit is not exceeded at 23.0 mol%, because as the SiO2 content increases, the temperature required to glass-seal the conductor in the substrate rises, which may lead to undesirable phase transitions (alpha-titanium-beta-titanium) in the titanium or titanium alloy of the substrate, and possibly the conductor, resulting in negative changes in properties, or the titanium may react with SiO2 to form titanium silicide. This can lead to volume changes and / or bubble formation in the glass at the interface with the metal. Furthermore, excessively high SiO2 content reduces the coefficient of thermal expansion. In advantageous embodiments, the glass has an SiO2 content of at least 11.0 mol%, or at least 11.5 mol%, or at least 12.0 mol%. In favorable modifications, the minimum SiO2 content may be 15.0 mol% or greater than 15.0 mol%. In some favorable modifications, the lower limit may be 15.5 mol% or 16.0 mol%. The SiO2 content may be, optionally, at most 22.5 mol%, favorably at most 22.0 mol%, favorably at most 21.0 mol%, and in some modifications at most 20.0 mol%.

[0030] The glass according to the present invention contains a resistance improver in a content of 0.1 to 6.0 mol%, the resistance improver being at least one component selected from the group including Nb2O5, ZrO2, TiO2, and Ta2O5. The total content of the components Nb2O5 + ZrO2 + TiO2 + Ta2O5 is preferably at least 0.1 mol%, because otherwise the hydrolysis resistance will not be sufficiently improved. A favorable lower limit may be 0.2 mol%, 0.3 mol%, or in some modifications, 0.4 mol%. It is preferable not to exceed the upper limit of 6.0 mol%, because this increases the risk of devitrification, i.e., crystal formation. Furthermore, the glass sealing temperature increases with increasing content, accompanied by the disadvantages described above for the SiO2 component. A favorable upper limit for the total may also be 5.5 mol%, 5.0 mol%, or 4.5 mol%. The resistance improver is a component of the molten glass, i.e., a glass component.

[0031] As a resistance enhancer, the glass may preferably contain Nb2O5 in a content of 0.0 to 6.0 mol%. If the glass contains Nb2O5, the component may preferably be present in an amount of at least 0.05 mol%, at least 0.1 mol%, or at least 0.2 mol%. In a favorable embodiment, the Nb2O5 content is limited to a maximum of 6.0 mol%, preferably a maximum of 5.5 mol%, preferably a maximum of 5.0 mol%, preferably a maximum of 4.5 mol%, or preferably a maximum of 4.0 mol%. In a favorable embodiment, the glass does not contain Nb2O5. To prevent crystal formation in the glass and / or an increase in the glass sealing temperature, it may be advantageous to reduce the Nb2O5 content or to completely omit Nb2O5.

[0032] As a resistance enhancer, the glass may preferably contain ZrO2 in a content of 0.0 to 6.0 mol%. If the glass contains ZrO2, the component may preferably be present in an amount of at least 0.05 mol%, at least 0.1 mol%, or at least 0.2 mol%. In a favorable embodiment, the ZrO2 content is limited to a maximum of 6.0 mol%, preferably 5.5 mol%, preferably 5.0 mol%, preferably 4.5 mol%, preferably 4.0 mol%, or preferably 3.5 mol%. In a favorable embodiment, the glass does not contain ZrO2. To prevent crystal formation in the glass and / or an increase in the glass sealing temperature, it may be advantageous to reduce the ZrO2 content or to completely omit ZrO2.

[0033] As a resistance enhancer, the glass may contain TiO2 in an advantageous amount of 0.0 to 6.0 mol%. If the glass contains TiO2, the component may be present in an advantageous amount of at least 0.05 mol%, 0.1 mol%, or at least 0.2 mol%. In advantageous embodiments, the TiO2 content is limited to a maximum of 6.0 mol%, advantageously up to 5.5 mol%, advantageously up to 5.0 mol%, advantageously up to 4.5 mol%, or up to 4.0 mol%. In advantageous embodiments, the glass does not contain TiO2. To prevent crystal formation in the glass, it may be advantageous to reduce the TiO2 content or to have no TiO2 at all.

[0034] As a resistance enhancer, the glass may preferably contain Ta2O5 in a content of 0.0 to 6 mol%. If the glass contains Ta2O5, the component may preferably be present in an amount of at least 0.05 mol%, at least 0.1 mol%, or at least 0.2 mol%. In a favorable embodiment, the Ta2O5 content is limited to a maximum of 6.0 mol%, preferably 5.5 mol%, preferably 5.0 mol%, preferably 4.5 mol%, preferably 4.0 mol%, or preferably 3.5 mol%. In a favorable embodiment, the glass does not contain Ta2O5. To maintain a low glass sealing temperature and prevent crystal formation in the glass, it may be advantageous to reduce the Ta2O5 content or to completely omit Ta2O5.

[0035] The glass according to the present invention contains RO in a content of 29.0 to 45.0 mol%, where RO represents the sum of alkaline earth metal oxides MgO + CaO + SrO. Alkaline earth metal oxides can lower the temperature at which glass sealing of conductors can occur in the substrate and increase the coefficient of thermal expansion; for this reason, at least 29.0 mol% of RO is included. It is desirable not to exceed the upper limit of 45.0 mol%, because otherwise the chemical resistance of the glass will deteriorate and there is a risk of crystal formation (devitrification) in the glass. In advantageous embodiments, the glass contains at least 30.0 mol% or at least 31.0 mol% of RO. Advantageously, the content can be limited to a maximum of 42.0 mol% or a maximum of 40.0 mol%, or in some modifications, a maximum of 39.5 mol%, a maximum of 39.0 mol%, a maximum of 38.0 mol%, or a maximum of 37.0 mol%.

[0036] In favorable configurations, the glass may contain MgO in a content of 0.0 to 20.0 mol%, i.e., the MgO content is up to 20.0 mol%. In favorable embodiments, the MgO content is limited to a maximum of 18.0 mol%, a maximum of 17.0 mol%, and a maximum of 16.0 mol%. If the glass contains MgO, in some variations, it may favorably contain at least 0.1 mol% or at least 0.2 mol% of MgO. In favorable variations, it contains at least 4.0 mol%, a maximum of 5.0 mol%, or at least 6.0 mol% of MgO. Some favorable variations may also contain at least 8.0 mol% or at least 9.0 mol% of MgO. Providing a certain content of MgO in addition to CaO and / or SrO in the glass may be advantageous in preventing crystal formation in the glass due to the combination. The favorable range for MgO may be 6.0 to 18.0 mol%. In alternative, advantageous embodiments, the glass does not need to contain MgO.

[0037] In favorable configurations, the glass may contain CaO in a content of 0.0 to 20.0 mol%, i.e., a maximum CaO content of 20.0 mol%. In favorable embodiments, the CaO content is limited to a maximum of 19.0 mol% or 18.0 mol%, or in some variations, a maximum of 17.0 mol%. If the glass contains CaO, in some variations, it may favorably contain at least 0.1 mol% or 0.2 mol% CaO. In favorable variations, it contains at least 5.0 mol% or 7.0 mol% or 10.0 mol% CaO. Providing a certain content of CaO in addition to MgO and / or SrO in the glass may be advantageous in preventing crystal formation in the glass due to the combination. The favorable range for CaO may be 10.0 to 20.0 mol%. In alternative favorable embodiments, the glass may not contain CaO.

[0038] In an advantageous configuration, the glass may contain SrO in an amount of 0.0 to 10.0 mol%, i.e., a maximum SrO content of 10.0 mol%. In an advantageous embodiment, the SrO content is limited to a maximum of 9.0 mol% or a maximum of 8.0 mol%. If the glass contains SrO, in some modifications, it may advantageously contain at least 0.1 mol% or at least 0.2 mol% SrO. In an advantageous modification, it may contain at least 2.0 mol% or at least 3.0 mol% or at least 4.0 mol% SrO. Providing a certain amount of SrO in addition to MgO and / or CaO in the glass may be advantageous in preventing crystal formation in the glass due to the combination. The advantageous range for SrO may be 3.0 to 8.0 mol%. In an alternative advantageous embodiment, the glass may not contain SrO.

[0039] To reduce the risk of devitrification, the glass preferably contains at least two alkaline earth metal oxides in any combination selected from the group consisting of MgO, CaO, and SrO. Particularly preferably, the glass contains MgO, CaO, and SrO.

[0040] The glass may preferably contain 0.0 to a maximum of 1.5 mol% BaO. It is desirable not to exceed this limit, because this component may reduce the hydrolysis resistance of the glass, thereby preventing the desired long-term autoclave stability of the feedthrough. Advantageously, the glass may contain a maximum of 1.0 mol%, advantageously a maximum of 0.5 mol%, or advantageously a maximum of 0.1 mol% BaO. Particularly preferable, the glass may contain no BaO.

[0041] In one composition, the glass may advantageously contain a proportion of ZnO, particularly between 0.0 mol% and a maximum of 5.0 mol%. The content should be limited to a maximum of 5.0 mol% because this component adversely affects the hydrolysis resistance of the glass. A favorable upper limit may also be a maximum of 3.0 mol% or a maximum of 2.0 mol%. If ZnO is present in the glass, a favorable lower limit may be at least 0.1 mol%, at least 0.2 mol%, or at least 0.5 mol%. A preferred modification of the glass does not require the presence of ZnO.

[0042] The glass may preferably contain Al2O3 to enhance hydrolysis resistance, increase the coefficient of thermal expansion, and reduce the tendency to crystallize. The proportion of Al2O3 in the glass composition may be at least 3.0 mol%, preferably at least 7.0 mol%, preferably at least 8.0 mol%, and particularly preferably at least 9.0 mol%. The advantageous upper limit may be up to 20.0 mol%, preferably up to 17.0 mol%, and preferably up to 16.0 mol%. It is desirable not to exceed the upper limit, because otherwise there is a risk of crystallization and / or an increase in the glass sealing temperature. In some advantageous modifications, the upper limit can be up to 15.0 mol%, or up to 14.0 mol%, or up to 13.0 mol%. Particularly advantageous ranges may be 7.0 mol% to 17.0 mol% or 7.0 to <15.0 mol%, preferably 8.0 to 14.0 mol%.

[0043] In preferred embodiments, the glass according to the present invention is low-alkali, and more preferably alkali-free. This is because alkali metal ions reduce the chemical resistance, particularly hydrolysis resistance, of the glass, and thus have an adverse effect on its long-term autoclaveability. In the context of the present invention, low alkali means that the total amount of alkali metal oxides R2O (Li2O + Na2O + K2O + Cs2O + Rb2O) in the glass is advantageously 3.0 mol% or less, advantageously up to 2.0 mol%, advantageously up to 1.0 mol%, advantageously 0.5 mol% or less, and preferably up to 0.1 mol% or less. If the glass contains only a single alkali metal oxide, the upper limits mentioned may apply individually to each alkali metal oxide. If two or more alkali metal oxides are contained, the upper limits mentioned may apply appropriately to any combination thereof. A particularly preferred variation of the glass is alkali-free, apart from ordinary impurities, i.e., free from alkali metal oxides Li2O and / or Na2O and / or K2O, and especially free from Li2O, Na2O, K2O, Cs2O and / or Rb2O.

[0044] Regarding glass composition, it may be advantageous if certain totals and / or ratios of glass components are met individually or in combination:

[0045] The total amount of the components SiO2 + ZrO2 + Nb2O5 + TiO2 + Ta2O5 may be in the advantageous range of >10.5 to 28.0 mol%. This improves hydrolysis resistance and reduces the risk of crystallization. Furthermore, it improves the viscosity of the glass. Some variations may have an advantageous lower limit of 12.0 mol%, 14.0 mol%, or 15.5 mol%, and / or an advantageous upper limit of 26.0 mol%, or 24.0 mol%. In some advantageous variations, the range may be 15.5 mol% to 23.0 mol%.

[0046] The total SiO2 + B2O3 content of the components may be in the advantageous range of >40.5 to 55.0 mol%. This improves hydrolysis resistance and allows for a lower glass sealing temperature. Some modifications may have a lower limit of 42.0 mol% or 43.0 mol% and / or an upper limit of 53.0 mol% or 51.0 mol%. In some advantageous modifications, the range may be 42.0 mol% to 53.0 mol%.

[0047] The ratio of components (SiO2 + Al2O3) / B2O3 may be advantageously 0.70 to 1.70, thereby allowing the glass sealing temperature to be kept low. Some variations may have an advantageous lower limit of 0.75 or 0.80 and / or an advantageous upper limit of 1.60, 1.50, 1.30, or 1.20. In some advantageous variations, the range may be 0.80 to 1.20 or 0.85 to 1.10.

[0048] The ratio of the components (SiO2 + Al2O3) / (B2O3 + RO) may be advantageously 0.30 to 0.90. This allows for a lower glass sealing temperature and improved glass viscosity. Some variations may have an advantageous lower limit of 0.35 or 0.40 and / or an advantageous upper limit of 0.80, 0.70, or 0.65. In some advantageous variations, the range may be 0.35 to 0.70.

[0049] The ratio of the components (SiO2 + Al2O3 + Nb2O5 + ZrO2 + TiO2 + Ta2O5) / (B2O3 + RO) may be advantageously between 0.35 and 0.90. This improves hydrolysis resistance on the one hand and reduces the risk of crystallization on the other hand. Furthermore, the viscosity of the glass is improved. Some variations may have an advantageous lower limit of 0.37 or 0.40 and / or an advantageous upper limit of 0.80 or 0.75 or 0.70 or 0.65. In some advantageous variations, the range may be between 0.35 and 0.75.

[0050] The ratio of the components (SiO2) / (Nb2O5+ZrO2+TiO2+Ta2O5) is greater than 3.00. A favorable range may be >3.00 to 55.00. This results in a balanced ratio of components in the glass that, in the context of the present invention, improves chemical resistance, particularly hydrolysis resistance, while also reducing the risk of crystallization. Furthermore, the viscosity of the glass is improved. Favouritely, the ratio may be less than 55.00, preferably less than 50.00, and preferably less than 45.00. In some favorable modifications, the ratio may be as high as 40.00 or as high as 35.00.

[0051] The glass composition preferably does not contain the following elements: Cr, Ni, Cd, Pb, Hg, As, Sb, Be, Ag, Sn, Cd, Tl, or compounds thereof, because these are toxic and / or can cause allergies. Furthermore, the glass is advantageously low in alkalinity, with the total alkali metal oxides (Li2O + Na2O + K2O + Cs2O + Rb2O) preferably less than 0.5 mol%. Particularly preferably, the glass is alkali-free (R2O-free).

[0052] The terms “Pb-free,” “lead-free,” “alkali-free,” or generally “component x-free” are understood in the context of this invention to mean that these substances or their oxides are not intentionally added to the glass as components, but are present at most in trace or small residual amounts, i.e., at most as impurities in the glass. For example, in the case of lead, this means that the Pb content is less than 1000 ppm. Advantageously, for example, the Pb content may be less than 500 ppm, preferably less than 100 ppm. For example, for Li2O, Na2O, K2O, Cs2O, Rb2O and / or other components (advantageously, some of which are described above as “not present”), the content per component may be less than 1000 ppm or less than 500 ppm, preferably less than 100 ppm, more preferably less than 50 ppm.

[0053] According to one embodiment, the glass is present in at least 94.0 mol%, preferably at least 95.0 mol%, preferably at least 97.0 mol%, and in some advantageous modifications at least 99.0 mol%, from the components La2O3, B2O3, SiO2, Al2O3, Nb2O5, ZrO2, TiO2, Ta2O5, and RO.

[0054] According to favorable modifications, the glass does not contain any components not mentioned in this disclosure.

[0055] In an advantageous developmental form, the glass may have the following components in mole percent on an oxide basis: [Table 1]

[0056] More preferably, the glass may contain, individually or in any combination, the following components in molar percentages, within the above-mentioned limit range for the total of Nb2O5 + ZrO2 + TiO2 + Ta2O5: [Table 2]

[0057] More preferably, the glass may contain, individually or in any combination, the following components in molar percentages, within the above-mentioned limit range for the total of Al2O3 and MgO+CaO+SrO: [Table 3]

[0058] In advantageous developmental forms, the glass may have the following components, individually or in any combination, within the limits set above, in molar percentages on an oxide basis: [Table 4]

[0059] Preferably, the glass may contain less than 3% by weight of filler. Fillers are often used to adapt the expansion behavior of the glass, i.e., the CTE, to the metal components used in the electrical feedthrough. Advantageously, the glass contains less than 1% by weight or less than 0.5% by weight of filler. Preferably, the glass is filler-free. Glasses having a defined content of specific components acting as hydrolysis resistance improvers and a certain proportion of SiO2 have, in the context of the present disclosure, a CTE that can be adapted to titanium and titanium alloys even without a filler, and thus a filler for strain adaptation is not required.

[0060] Regarding the coefficient of thermal expansion (CTE) of the glass, advantageously, the glass of the insulating material may have a CTE (20 °C; 300 °C) in the range of 5.0 to 13.0 ppm / K, advantageously in the range of 5.0 to 10.5 ppm / K, advantageously in the range of 6.0 to 10.5 or 6.0 to 9.0 ppm / K, and particularly preferably in the range of 6.5 to 8.0 ppm / K. The inventors have noticed that by a special selection of the glass components, it is possible to provide a glass with high hydrolysis resistance that has a CTE suitable for a glass-metal feedthrough with titanium or titanium alloy even without a filler. This was surprising. In particular, this enables material matching with titanium or titanium alloy, and as a result, the airtightness of the feedthrough, especially the airtight seal, can be improved. The CTE is determined by a dilatometric method (using a push rod dilatometer) in a static measurement in accordance with ISO 7991:1987-12.

[0061] The glass of the insulating material preferably has a density in the range of 2.50 to 3.80 g / cm 3 advantageously in the range of 2.70 to 3.70 g / cm 3 and particularly in the range of 2.80 to 3.50 g / cm 3 The density can be determined according to known methods, for example, in accordance with ASTM C693:1993.

[0062] Furthermore, the glass of the insulating material has a glass transition temperature T that is advantageously lower than 750°C, advantageously lower than 700°C, advantageously lower than 670°C, and especially advantageously lower than 650°C. g It is conceivable that it may have a transition temperature. The transition temperature is determined by known methods according to DIN ISO 7884-8:1998-02.

[0063] In particular, the glass of insulating materials has a glass transition temperature T in the range of 500-700°C, preferably in the range of 560-670°C, and especially in the range of 600-650°C. g It may have a lower glass transition temperature T. g This may be advantageous in terms of processing.

[0064] Advantageously, the insulating glass material may have a spherical temperature of up to 850°C, advantageously up to 820°C, and particularly preferably up to 790°C.

[0065] Advantageously, the insulating glass material may have a hemispherical temperature of up to 900°C, advantageously up to 880°C, advantageously up to 870°C, and advantageously up to 860°C.

[0066] The glass properties "spherical temperature" and "hemispherical temperature" were determined using established heating microscopy (EHM) methods with the EMI301 heating microscope and EMI III heating microscope software from Hesse Instruments. Evaluation is performed automatically, for example, by analyzing the shadow profile of the sample according to DIN 51730. The hemispherical temperature indicates the temperature at which the originally cylindrical sample pieces melt together to form a hemispherical mass. The hemispherical temperature of glass roughly corresponds to the temperature at which a leak-free glass-metal-feedthrough can be produced, i.e., roughly the glass sealing temperature. The glass sealing temperature may be 5°C to 70°C higher than the hemispherical temperature.

[0067] The feedthrough substrate, also called the outer conductor, comprises titanium or a titanium alloy, and the material is advantageously selected from Grade 1 titanium, Grade 2 titanium, Grade 3 titanium, Grade 4 titanium, or Grade 5 titanium, particularly TiAl6V4 alloy. Titanium and titanium alloys may have a coefficient of thermal expansion CTE(20;300) in the range of 8 to 10 ppm / K, preferably in the range of 8.5 to 9.5 ppm / K.

[0068] The electrical conductor of the feedthrough may contain or consist of a metal. Preferably, the metal is selected from Kovar, molybdenum, nickel, nickel-iron alloy, titanium, titanium alloy, platinum, platinum alloy (e.g., Pt / Ir alloy), tantalum, tantalum alloy, niobium, and niobium alloy.

[0069] The electrical conductor may have a coefficient of thermal expansion CTE (20;300) in the range of 5 to 13 ppm / K, preferably in the range of 6 to 10 ppm / K, and preferably in the range of 7 to 9 ppm / K. A suitable glass seal can be provided by appropriately selecting an insulating material in combination with a substrate having titanium or a titanium alloy, or in combination with a substrate made of titanium or a titanium alloy.

[0070] In the case of a fitted glass seal, it is preferable that the difference in thermal expansion coefficients between the substrate and the insulating material, and more preferably between the substrate, the insulating material, and the conductor, is less than 5%.

[0071] In particular, a fitted feedthrough means that the coefficient of thermal expansion is at most 1 × 10⁻⁶. -6 It is understood that a difference of 1 / K means that they are essentially the same.

[0072] A favorable alternative is to provide pressurized glass seals in combination with a substrate containing titanium or a titanium alloy, thereby enhancing mechanical robustness. The thermal expansion coefficient of the substrate is selected to be greater than that of the insulating material, so that the substrate contracts more strongly than the insulating material after the temperature treatment in which the insulating material is glass-sealed within the through-opening. This applies a sustained compressive force to the insulating material through the substrate. These preload the insulating material, resulting in a particularly durable seal.

[0073] Accordingly, it is preferable that the thermal expansion coefficient of the substrate is greater than that of the insulating material. Particularly preferable, in the case of pressurized glass sealing, the thermal expansion coefficient of the substrate is selected to be at least 5%, preferably at least 10%, particularly preferably at least 20%, and most preferably at least 50% greater than that of the insulating material.

[0074] The pre-pressure for pressurized glass sealing is substantially determined by the difference in thermal expansion coefficients between the substrate material and the insulating material.

[0075] To the extent that the values ​​of the coefficient of thermal expansion are mentioned above in relation to pressurized or fitted glass seals on a material, these refer to the linear coefficient of thermal expansion α in the temperature range of 20–300°C, as is typically shown in relation to glass-metal-feedthrough.

[0076] To manufacture a feedthrough, an insulating material or precursor material containing glass can be provided in the form of a molded body. This molded body may, for example, have the shape of a hollow cylinder. For the formation of an electrical feedthrough, an electrical conductor is inserted into the hollow cylinder, which is also inserted into a through-opening in a substrate containing or made of titanium or a titanium alloy. Subsequently, the opening is glass-sealed by heat treatment, and the insulating material, in particular the glass, is closely bonded with the conductor material and the substrate material, thus forming a glass-metal feedthrough. The glass melts during the heat treatment process.

[0077] In some cases, the use of titanium or titanium alloys in chemical reactions can lead to a special situation where the glass component SiO2 reacts with titanium to form titanium silicide, resulting in delamination in the glass-metal contact zone. This problem can be mitigated or avoided, in particular, by the aforementioned values ​​regarding the glass composition. Specifically, this reaction can be suppressed by the values ​​mentioned for B2O3, resulting in a TiB layer that provides a more chemically and mechanically stable bond between the titanium-containing component and the glass.

[0078] As a general rule, it must be considered that titanium or titanium alloys are highly reactive. Using the glass composition according to the present invention, when a conductor is glass-sealed to a substrate (for example, at a glass sealing temperature of 700-900°C), the reaction of titanium (alloy) with SiO2 to form titanium silicide can be mitigated or avoided, for example, the formation of bubbles at the interface. Furthermore, using the glass according to the present invention, a low glass sealing temperature can be selected so that glass-metal-feedthroughs can be manufactured at temperatures lower than the temperature range of the α / β phase transition of titanium.

[0079] In an advantageous modification, the feedthrough may have exactly one electrical conductor that extends through the insulating material contained within the through-opening.

[0080] In advantageous modifications, the feedthrough may have multiple electrical conductors, for example, at least two electrical conductors, and more preferably at least ten electrical conductors, that extend through the insulating material contained within the through-opening.

[0081] The substrate may include a plurality of through-openings, each containing an insulating material, and each through-opening has at least one, in particular exactly one, electrical conductor extending through the insulating material.

[0082] A substrate containing titanium or a titanium alloy may be formed in the shape of a plate. The substrate may have a first surface and a second surface facing it, and the through-opening may form an inner wall connecting the first surface and the second surface. The substrate may define a plane running parallel to the first surface and / or the second surface. The substrate may have dimensions larger than the diameter of the through-opening, particularly at least twice, and particularly at least three times, along the direction running parallel to the first and / or second surface and / or the direction running in the aforementioned plane.

[0083] The insulating material located in the through-opening can be recessed relative to the first and / or second surface of the substrate. In other words, the insulating material can be housed in the through-opening such that it is stepped relative to the substrate at the position of the inner wall. Alternatively, it can be coplanar with one or both surfaces of the substrate, or even protrude beyond one or both surfaces of the substrate.

[0084] The conductors can protrude from the first and / or second surfaces of the substrate.

[0085] Further aspects of the present invention include, in particular, a glass for electrical feedthroughs having a titanium or titanium alloy substrate according to the first aspect of the present invention, wherein the glass is lanthanum borate glass, and the lanthanum borate glass comprises the following components (in mole percent on an oxide basis): B2O322.0~37.0 La2O3 1.0~12.0 SiO2 10.5~23.0 RO(MgO+CaO+SrO) 29.0~45.0 Nb2O5 + ZrO2 + TiO2 + Ta2O5 0.1~6.0 SiO2 / (Nb2O5+ZrO2+TiO2+Ta2O5) >3.00 Includes, The glass, when measured for hydrolysis resistance in accordance with DIN ISO 720:2021-12, has a Na2O equivalent value of <1250 μg / g. Regarding glass.

[0086] The components mentioned are glass components. That is, at least one component from (Nb2O5 + ZrO2 + TiO2 + Ta2O5) is a constituent of molten glass.

[0087] Details regarding the advantages of the glass composition according to the present invention, its favorable development forms, and its advantageous chemical and physical properties have already been described above in connection with the description of the first aspect of the present invention. This disclosure is fully incorporated into the description of further aspects of the present invention. To avoid duplication, it is referred to here.

[0088] This glass and electrical feedthroughs manufactured using it can be used in connection with electrical and medical devices, particularly autoclavable feedthroughs having metallic components made of titanium or titanium alloys. Favorable application areas include endoscopes and surgical instruments used for examination, surgery, and treatment, which come into contact with the body only for short periods but can, relatively often, be reused after proper sterilization, such as instruments in robotic surgery. Implantable medical devices or devices that can be worn on the body, such as wearable devices, are also application areas. Because titanium or titanium alloy components are often used in fields such as aerospace and motorsport due to their excellent strength, resistance, and light weight, this glass and joints and feedthroughs manufactured using it can also be used in these fields.

[0089] Therefore, a further aspect of the present invention relates to the use of feedthroughs or glass according to the present invention in feedthroughs or joints having metallic components from titanium or titanium alloys in the fields of medical devices, wearable devices, aerospace, and motorsport.

[0090] It is obvious that the features of the present invention, including those described above and several embodiments further below, can be used in combinations other than those shown, without departing from the scope of the present invention.

[0091] The present invention will be described in more detail below based on the figures and several embodiments. [Brief explanation of the drawing]

[0092] [Figure 1] This figure shows a schematic diagram of the feedthrough according to the first embodiment. [Figure 2] This figure shows a schematic diagram of the feedthrough according to the second embodiment. [Figure 3] This figure shows a schematic diagram of the feedthrough according to the third embodiment.

[0093] Referring to Figure 1, a feedthrough that can be autoclaved for a long period of time has an outer substrate 20 through which one or more through-openings 22 (two in this case) extend, each of which an insulating material 30 containing or made of glass is introduced, through which at least one electrical conductor 40 extends. The conductor can protrude from the insulating material on one side or both sides (both sides in this case). The illustrated feedthrough has two internal conductors (pins) and can therefore be called a two-pole feedthrough. The substrate 20 can function as an external conductor and thus form further electrical conductors. Of course, a feedthrough with only one internal conductor (pin), i.e., a simple feedthrough or one-pole feedthrough, is also possible.

[0094] In this example, the substrate 20 is made of titanium, but it can also be made of a titanium alloy. In this case, the conductor 40 is also made of titanium. However, it may also be made of another biocompatible material, such as titanium alloy, Kovar, molybdenum, nickel-iron alloy, nickel, tantalum, tantalum alloy, niobium, niobium alloy, platinum, or platinum alloy. The insulating material 30 is made of lanthanum borate glass containing alkaline earth metal oxides according to the present invention.

[0095] Referring to Figures 2 and 3, a feedthrough that can be autoclaved for a long period of time may also have multiple internal conductors (pins), thereby providing, for example, a 17-pin feedthrough (Figure 2) or a 30-pin feedthrough (Figure 3). In the illustrated connector, each internal conductor 40 extends through the insulating material of a single through-opening 22, but it is also possible for multiple or many electrical conductors to extend through the same insulating material of the same through-opening 22.

[0096] Examples Glass having the compositions described in Tables 1 and 2 was melted from conventional raw materials in a heated Pt crucible or Pt / Ir crucible at a temperature exceeding 1350°C. The molten material was maintained at this temperature for more than 20 minutes, stirred for homogenization, and then cast into a casting block.

[0097] In addition to composition, the following parameters and properties of the example glass (Ex.) and comparative example glass (CEx.) according to the present invention were investigated using bulk samples according to the method described above: CTE (20;300), density, T g .

[0098] To produce glass powder, a molten material can be passed through a water-cooled metal roller, and then glass tape (ribbon) can be crushed.

[0099] Compressed samples were prepared from pure powder using known methods, and characteristic points were examined by heating microscopy (EHM) according to the methods described above to characterize the softening and melting behavior of the glass: spherical temperature, hemispherical temperature.

[0100] A hollow cylindrical molded body was manufactured from glass powder using a known method for producing an electrical feedthrough. To form the electrical feedthrough, an electrical conductor made of titanium was inserted into the hollow cylinder, which was also inserted into the feedthrough of a titanium substrate. Subsequently, the opening was glass-sealed by heat treatment, causing the glass to melt and bond closely with the conductor material and the substrate material, thus forming the glass-metal-feedthrough. The temperature at which a hermetically sealed feedthrough can be successfully manufactured is the glass sealing temperature.

[0101] After the feedthroughs were manufactured, i.e., before the first autoclave treatment, the insulation resistance of the glass-sealed conductors in each feedthrough was measured according to the method described at the beginning (MIL-STD-883, Method.1003). The diameter of the substrate through-hole was 1.8 mm, the diameter of the conductor was 0.5 mm, and the glass-sealed length was 3.0 mm.

[0102] Next, the long-term autoclave resistance of each feedthrough was investigated as follows: The feedthrough was placed in a petri dish and placed on a grid inside the autoclave. This was possible on multiple rails. Then, a permanently programmed autoclave sequence was started with the parameters 135.5°C, 2.16 bar, and 20 minutes. The feedthrough remained there for at least 300 cycles. Each cycle included the following stages: removal of air from the sterilization chamber; steam generation; sterilization stage (135.5°C and 2.16 bar pressure for 20 minutes); vacuum drying; removal of used water from the circulation system, pressure equalization to air pressure in the sterilization chamber, and active cooling to room temperature (end of cycle). After the first 300 cycles, the insulation resistance of each feedthrough was measured again. The insulation resistance was still at least 1 × 10⁻⁶ 9 In the case of Ohm, the feedthrough was autoclaved for a further 300 cycles, after which the insulation resistance was measured again. In the case of the feedthroughs with glass according to the present invention (Examples 1-4, 12-14), the insulation resistance still exceeded the required minimum resistance value, so the test was stopped after 1200 cycles.

[0103] Using known glass materials (CEx.A~C) suitable for use in implantable device feedthroughs, corresponding feedthroughs were manufactured and tested under the same conditions. The measured insulation resistance was 1 × 10⁻⁶. 9 Since the resistance level was below ohms, the test was stopped after 300 autoclave cycles.

[0104] Furthermore, the helium leakage rate of the feedthrough was determined after the completion or discontinuation of the autoclave treatment cycle.

[0105] Table 1 shows 14 examples (Ex.) of the present invention, and Table 2 shows comparative examples (CEx.).

[0106] [Table 5-1] [Table 5-2]

[0107] [Table 6]

[0108] Examples 2-4 and 12-14 show lower Na2O equivalent values ​​compared to Comparative Examples A-C, meaning the glass according to the present invention has superior hydrolysis resistance. The Na2O equivalent values ​​for Examples 2-4 and 12-14 are less than 930 μg / g, meaning these glasses correspond to Class 3 according to DIN ISO 720. The improved hydrolysis resistance is due to a relatively high proportion of SiO2 in the glass-metal feedthrough having titanium or a titanium alloy, and a certain proportion of a resistance enhancer selected from the group consisting of Nb2O5, ZrO2, TiO2, and Ta2O5, where SiO2 and the resistance enhancer are present in a balanced proportion.

[0109] Using the glass according to the present invention, a feedthrough with long-term autoclave resistance can be provided for a titanium or titanium alloy substrate. In Comparative Examples A and B, the required minimum insulation resistance of 1 × 10⁻¹⁰ was achieved after 300 autoclave cycles. 9 Although the ohm is no longer achieved, the glass of Examples 1-4 and 12-14 still has an insulation resistance of 1 × 10⁻¹⁶ after 1200 autoclave cycles. 9 It is higher than ohms, and the helium leakage rate is 1 × 10⁻⁶. -8 Feedthroughs with a density of less than mbar·l / s can be manufactured, meaning that, unlike the comparative feedthroughs using glass in Comparative Examples A-C, the feedthroughs according to the present invention remain airtightly sealed even after more than 300 autoclave cycles (1200 or more in this case).

[0110] Furthermore, the glass according to the present invention has a CTE (20;300) even without fillers, making it suitable for the manufacture of airtight seal feedthroughs comprising a titanium or titanium alloy substrate and a conductor from the material defined above.

[0111] The softening and melting behavior of the glass according to the present invention is optimized so that glass sealing in titanium or titanium alloys can be carried out without exceeding, or particularly preferably falling too high, the temperature range of the α / β phase transition of titanium. The hemispherical temperatures of Examples 1-4 and 12-14 are less than 870°C, and therefore the glass sealing temperature can be correspondingly low, particularly <930°C, and advantageously <900°C.

Claims

1. It is an electrical feedthrough, A substrate, the substrate including at least one through-opening extending through the substrate, A through-opening extending through the substrate is housed in an insulating material made of or containing glass, At least one electrical conductor extending through the insulating material housed in the through-opening, wherein the substrate comprises titanium or a titanium alloy, and In electrical feedthroughs, including, The glass is lanthanum borate glass, and the lanthanum borate glass has the following components (in mole percent on an oxide basis): B ２ O ３ 22.0~37.0 L ２ O ３ 1.00-1.

20. Yes ２ 10.5~23.00 RO (MgO+CaO+SrO) 29.0~45.0 Nb ２ O ５ +ZﺒO ２ +T&O ２ +Ta ２ O ５ 0.1~6.0 SiO ２ / (Nｬ ２ O ５ +ZﺒO ２ +T&O ２ +Ta ２ O ５ ) >3.00 Includes, When the hydrolysis resistance of the aforementioned glass was measured in accordance with DIN ISO 720:2021-12, it contained <1250 μg / g of Na. ２ Having an O equivalent value, the feedthrough having such glass has long-term autoclave resistance, The insulation resistance of the feedthrough after 300 autoclave cycles is at least 1 × 10⁻⁶ ９ Ohm An electrical feedthrough characterized by the following:

2. The aforementioned feedthrough, after 300 autoclave cycles, is 1 x 10 －８ The electrical feedthrough according to claim 1, having airtightness characterized by a helium leakage rate of less than mbar·l / s.

3. The aforementioned glass, individually or in any combination, contains the following components in molar percentages on an oxide basis: Nb ２ O ５ 0.0~6.0 ZrO ２ 0.0~6.0 TO ２ 0.00~6.00 That ２ Oh ５ 0.00~6.00 An electrical feedthrough according to claim 1 or 2, including the following:

4. Total SiO of the aforementioned components ２ +ZrO ２ +Nb ２ O ５ +TiO ２ +Ta ２ O ５ However, the electrical feedthrough according to at least one of claims 1 to 3 is in the range of >10.5 to 28.0 mol%.

5. The aforementioned glass, individually or in any combination, contains the following components in molar percentages on an oxide basis: Al ２ O ３ 700-1700 MgO 0.0~20.0 CaO 0.0-20.0 SrO 0.0~10.0 An electrical feedthrough according to at least one of claims 1 to 4, including

6. SiO in the aforementioned glass ２ The content is at least 12.0 mol%, preferably more than 15.0 mol%, and / or the glass is Al ２ O ３ An electrical feedthrough according to at least one of claims 1 to 5, comprising 7.0 to <15.0 mol%, preferably 8.0 to 14.0 mol% of .

7. The glass meets at least one condition: - A maximum of 1.5 mol% BaO, preferably without BaO. - <3.0 mol% alkali metal oxide (R ２ O), R is advantageous ２ Does not contain O An electrical feedthrough according to at least one of claims 1 to 6, satisfying the requirements.

8. The aforementioned glass is subject to the following conditions: - A coefficient of thermal expansion (20°C; 300°C) in the range of 5.0 to 13.0 ppm / K, preferably 6.0 to 10.5 ppm / K. - A glass transition temperature T lower than 750°C, and preferably lower than 700°C. ｇ , - Maximum hemispherical temperature of 900°C, advantageously up to 870°C. An electrical feedthrough according to at least one of claims 1 to 7, satisfying at least one of the following:

9. The substrate material is selected from Grade 1 titanium, Grade 2 titanium, Grade 3 titanium, Grade 4 titanium, or Grade 5 titanium, particularly TiAl6V4 alloy, and / or The aforementioned electrical conductor includes or consists of a material selected from Kovar, molybdenum, nickel, nickel-iron alloy, titanium, titanium alloy, platinum, platinum alloy (e.g., Pt / Ir alloy), tantalum, tantalum alloy, niobium, and niobium alloy. An electrical feedthrough according to at least one of claims 1 to 8.

10. In particular, a glass for electrical feedthrough having a titanium or titanium alloy substrate according to at least one of claims 1 to 9, wherein the glass is lanthanum borate glass, and the lanthanum borate glass comprises the following components (in mole percent on an oxide basis): B ２ O ３ 22.0~37.0 L ２ O ３ 1.00-1.

20. Yes ２ 10.5~23.00 RO (MgO+CaO+SrO) 29.0~45.0 Nb ２ O ５ +ZﺒO ２ +T&O ２ +Ta ２ O ５ 0.1~6.0 SiO ２ / (Nｬ ２ O ５ +ZﺒO ２ +T&O ２ +Ta ２ O ５ ) >3.00 Includes, When the hydrolysis resistance of the aforementioned glass was measured in accordance with DIN ISO 720:2021-12, it contained <1250 μg / g of Na. ２ Having an O equivalent value, Glass.

11. Use of a feedthrough according to at least one of claims 1 to 9 or glass according to claim 10 in a feedthrough or joint having a metallic component from titanium or a titanium alloy in the fields of medical devices, wearable devices, aerospace, and motorsport.

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