ELECTRICAL FEEDTHROUGH

Abstract

A feedthrough includes: a main body including at least one passage opening running through the main body, the main body including titanium or a titanium alloy; an insulation material accommodated in the at least one passage opening running through the main body, the insulation material including glass, the insulation material having a contact angle of less than 90 degrees at least in a plurality of regions of the insulation material with respect to the main body; and at least one electrical conductor extending through the insulation material accommodated in the at least one passage opening.

Claims

1. A feedthrough, comprising: a main body including at least one passage opening running through the main body, the main body including titanium or a titanium alloy; an insulation material accommodated in the at least one passage opening running through the main body, the insulation material including glass, the insulation material having a contact angle of less than 90 degrees at least in a plurality of regions of the insulation material with respect to the main body; and at least one electrical conductor extending through the insulation material accommodated in the at least one passage opening.

2. The feedthrough according to claim 1, wherein at least one of: (a) the contact angle of the insulation material with respect to the main body is between 56 and 86 degrees; and (b) the insulation material at least in a plurality of regions of the insulation material has a contact angle with respect to the at least one electrical conductor of between 56 and 86 degrees.

3. The feedthrough according to claim 1, wherein: (a) the glass of the insulation material has a glass composition including B.sub.2O.sub.3 and SiO.sub.2, wherein a ratio of a proportion of B.sub.2O.sub.3 in percent by weight to a proportion of SiO.sub.2 in percent by weight is at least 0.45; or (b) the glass of the insulation material has a glass composition including B.sub.2O.sub.3 and SiO.sub.2, wherein a ratio of a proportion of B.sub.2O.sub.3 in percent by weight to a proportion of SiO.sub.2 in percent by weight is between 0.45 and 0.65.

4. The feedthrough according to claim 1, wherein: (a) the glass of the insulation material has a glass composition including B.sub.2O.sub.3, wherein a proportion of B.sub.2O.sub.3 in the glass composition is at least 21 percent by weight; or (b) the glass of the insulation material has a glass composition including B.sub.2O.sub.3, wherein a proportion of B.sub.2O.sub.3 in the glass composition is between 21 and 33 percent by weight.

5. The feedthrough according to claim 1, wherein at least one of: (a) the glass of the insulation material has a softening temperature of not more than 750? C.; (b) the glass of the insulation material has a sphere temperature of not more than 850? C.; (c) the glass of the insulation material has a hemisphere temperature of not more than 950? C.; (d) the glass of the insulation material has a flow temperature of not more than 1050? C.; and (e) the glass of the insulation material is stable on storage in a saline solution at 37.5? C.

6. The feedthrough according to claim 1, wherein: (a) the glass of the insulation material has a glass composition including Al.sub.2O.sub.3, wherein a proportion of Al.sub.2O.sub.3 in the glass composition is at least 3 percent by weight; or (b) the glass of the insulation material has a glass composition including Al.sub.2O.sub.3, wherein a proportion of Al.sub.2O.sub.3 in the glass composition is between 3 and 17 percent by weight.

7. The feedthrough according to claim 1, wherein the glass of the insulation material has a glass composition including Na.sub.2O, wherein a proportion of Na.sub.2O in the glass composition is at least 10 percent by weight.

8. The feedthrough according to claim 1, wherein at least one of: (a) the glass of the insulation material has a glass composition including CaO, wherein a proportion of CaO in the glass composition is at most 11 percent by weight; and (b) the glass of the insulation material has a glass composition including TiO.sub.2, wherein the proportion of TiO.sub.2 in the glass composition is at most 10 percent by weight.

9. The feedthrough according to claim 1, wherein at least one of: (a) the glass of the insulation material has a glass composition including no K.sub.2O or including K.sub.2O, wherein a proportion of K.sub.2O in the glass composition is less than 7 percent by weight; and (b) the glass of the insulation material has a glass composition including no LiO.sub.2 or including LiO.sub.2, wherein a proportion of LiO.sub.2 in the glass composition is less than 2 percent by weight.

10. The feedthrough according to claim 1, wherein at least one of: (a) the glass of the insulation material has a glass composition including no MgO or including MgO, wherein a proportion of MgO in the glass composition is less than 10 percent by weight; and (b) the glass of the insulation material has a glass composition including no ZrO.sub.2 or including ZrO.sub.2, wherein a proportion of ZrO.sub.2 in the glass composition is less than 0.9 percent by weight.

11. The feedthrough according to claim 1, wherein at least one of: (a) the glass of the insulation material has a glass composition including no La.sub.2O.sub.3 or including La.sub.2O.sub.3, wherein a proportion of La.sub.2O.sub.3 in the glass composition is less than 1.5 percent by weight; (b) the glass of the insulation material has a glass composition including no Ta.sub.2O.sub.5 or including Ta.sub.2O.sub.5, wherein a proportion of Ta.sub.2O.sub.5 in the glass composition is less than 2 percent by weight; and (c) the glass of the insulation material has a glass composition including no Nb.sub.2O.sub.5 or including Nb.sub.2O.sub.5, wherein a proportion of Nb.sub.2O.sub.5 in the glass composition is less than 2 percent by weight.

12. The feedthrough according to claim 1, wherein at least one of: (a) the glass of the insulation material has a glass composition including no PbO or including PbO, wherein a proportion of PbO in the glass composition is less than 0.05 percent by weight; (b) the glass of the insulation material has a glass composition including no BaO or including BaO, wherein the proportion of BaO in the glass composition is less than 10 percent by weight; and (c) the glass of the insulation material has a glass composition including no V.sub.2O.sub.5 or including V.sub.2O.sub.5, wherein a proportion of V.sub.2O.sub.5 in the glass composition is less than 0.5 percent by weight.

13. The feedthrough according to claim 1, wherein at least one of: (a) the glass of the insulation material has a glass composition including no Bi.sub.2O.sub.3 or including Bi.sub.2O.sub.3, wherein a proportion of Bi.sub.2O.sub.3 in the glass composition is less than 2 percent by weight; (b) the glass of the insulation material has a glass composition including no WO.sub.3 or including WO.sub.3, wherein a proportion of WO.sub.3 in the glass composition is less than 2 percent by weight; and (c) the glass of the insulation material has a glass composition including no MoO.sub.3 or including MoO.sub.3, wherein a proportion of MoO.sub.3 in the glass composition is less than 2 percent by weight.

14. The feedthrough according to claim 1, wherein the glass of the insulation material has a coefficient of thermal expansion (20? C.); 300? C. in a range from 5 to 10 ppm/K.

15. The feedthrough according to claim 1, wherein at least one of: (a) the glass of the insulation material has a glass transition temperature T.sub.g lower than 590? C.; and (b) the glass of the insulation material has a glass transition temperature T.sub.g in a range from 440 to 590? C.

16. The feedthrough according to claim 1, wherein at least one of: (a) the insulation material includes a first outer surface and a second outer surface, wherein the insulation material, from the first outer surface to the second outer surface, along the at least one passage opening that runs through the main body, has a transmittance T.sub.vis for at least one wavelength in a spectral range from 380 nm to 780 nm of at least 25%; and (b) the feedthrough includes an optical interface configured for transmitting light through the insulation material along the at least one passage opening that runs through the main body.

17. The feedthrough according to claim 1, wherein the insulation material includes at least one outer face and is free of a plurality of graphite particles on the at least one outer face.

18. The feedthrough according to claim 1, wherein the feedthrough includes a contact face, wherein the insulation material accommodated in the at least one passage opening of the main body is in contact at least one of with the main body and with the at least one electrical conductor in such a way that (i) the contact face between the insulation material and the main body and (ii) the feedthrough has a hermiticity characterized by a helium leakage rate of less than 1.Math. 10.sup.?8 mbar.Math.l/s.

19. The feedthrough according to claim 1, further comprising a plurality of the at least one electrical conductor that extends through the insulation material accommodated in the at least one passage opening.

20. The feedthrough according to claim 1, wherein at least one of: (a) the glass of the insulation material is non-cytotoxic; (b) the feedthrough includes at least two of the at least one electrical conductor which are spaced apart by less than 5 mm; and (c) a greatest dimension of the at least one passage opening running through the main body at a right angle to an axis of the at least one electrical conductor is less than 10 mm.

21. The feedthrough according to claim 1, wherein at least one of: (a) the feedthrough at least one of (i) has a shock resistance of at least 100 g and (ii) withstands such a shock with retention of a hermeticity of the feedthrough; and (b) the feedthrough at least one of (i) has a vibration resistance of at least 20 g rms, and (ii) withstands such a vibration with retention of hermeticity of the feedthrough.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0075] 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:

[0076] FIG. 1 is a schematic diagram of a feedthrough according to a first embodiment;

[0077] FIG. 2 is a schematic diagram of the feedthrough shown in FIG. 1 in cross section, showing the contact angle between the insulation material and the main body or electrical conductor;

[0078] FIG. 3 is a schematic diagram of a feedthrough according to a second embodiment; and

[0079] FIG. 4 is a schematic diagram of a feedthrough according to a third embodiment.

[0080] 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

[0081] With reference to FIG. 1, a feedthrough has an outer main body 20, through which one or more passage openings 22 (two here) run, wherein each passage opening 22 accommodates an insulation material 30, through which at least one electrical conductor 40 extends. The conductor here may project out of the insulation material at one or both ends (at both ends here). The feedthrough shown has two internal conductors (pins) and can therefore be referred to as a 2-pole feedthrough. It is possible that the main body 20 serves as outer conductor and hence forms a further electrical conductor.

[0082] With reference to FIG. 2, the insulation material 30 accommodated in the passage opening 22 has a contact angle ? of less than 90 degrees with respect to the surrounding main body 20. In addition, the insulation material 30 may optionally also have a contact angle ? of less than 90? with respect to the electrical conductor 40. In principle, a weight, for example a charcoal mold, may be used in the melting of the insulation material 30 into the passage opening 22, in order to achieve the, or particular, contact angles ? or ?. However, this can sometimes be impractical in the case of a relatively high number of pins. It is alternatively possible that the insulation material is melted into the passage opening 22 in such a way that the contact angle ?<90? is formed merely because of the wetting properties of the insulation material on the main body material, such that it is possible to dispense with any weight, and the outer surface of the insulation material 30 is free of charcoal particles. The term contact angle is in particular synonymous with the term wetting angle.

[0083] With reference to FIGS. 3 and 4, a feedthrough may also have a multitude of internal conductors (pins), such that, for example, a 17-pole feedthrough (FIG. 3) or even a 30-pole feedthrough (FIG. 4) may be provided. In the plug connectors shown, each individual internal conductor 40 extends through the insulation material of a single passage opening 22. However, it is also possible that a plurality or multitude of electrical conductors extend through the same insulation material in the same passage opening 22.

[0084] With regard to wetting of the insulation material 30 on the main titanium body 20 with a contact angle ?<90? (without use of weights), the insulation material 30 may especially take the form of a high-borate glass. It may be the case, for example, that the glass of the insulation material has a glass composition containing B.sub.2O.sub.3 and SiO.sub.2, where the ratio of the proportion of B.sub.2O.sub.3 in percent by weight to the proportion of SiO.sub.2 in percent by weight is at least 0.36, and/or that the glass of the insulation material has a glass composition containing B.sub.2O.sub.3, where the proportion of B.sub.2O.sub.3 in the glass composition is at least 20 percent by weight.

[0085] Especially for a high-borate glass and/or a glass composition having the abovementioned boron contents, it may be advantageous that the glass of the insulation material has a softening temperature of not more than 680? C., a sphere temperature of not more than 780? C., a hemisphere temperature of not more than 850? C. and/or a flow temperature of not more than 950? C., optionally not more than 940? C., optionally not more than 900? C.

[0086] It may especially be the case that the glass of the insulation material can be vitrified at temperatures below 950? C., optionally below 940? C. This results in the optional limitation in the characteristic feature of flow point from the established method of heating microscopy (EHM) to not more than 940? C.

[0087] In the case of vitrification in titanium or titanium alloys, it should be ensured that this process is optionally not conducted too far above, or is optionally conducted below, the temperature range of the ?/? phase transition of titanium.

[0088] In one working example, the insulation material may include a glass having the following composition in % by weight:

TABLE-US-00001 SiO.sub.2 35-55% B.sub.2O.sub.3 20-33% Al.sub.2O.sub.3 3-23% Na.sub.2O 5-20% CaO 0-12% TiO.sub.2 0-10%.

[0089] In a further working example, the insulation material may include a glass having the following composition in % by weight:

TABLE-US-00002 SiO.sub.2 40-51% B.sub.2O.sub.3 24-30% Al.sub.20.sub.3 7-19% Na.sub.20 10-17% CaO 0-7% TiO.sub.2 0-7%.

[0090] In further working examples, the insulation material may include a glass having the aforementioned compositions, but including the following proportion of B.sub.2O.sub.3 in % by weight: 25.0-28.6.

[0091] In further working examples, the insulation material may include a glass having the aforementioned compositions, but including the following proportion of MgO in % by weight: less than 5.5, especially less than 5, especially than 4.5.

[0092] In specific working examples, the insulation material may include a glass having one of the following compositions in % by weight (glass 1 to 5):

TABLE-US-00003 % by wt. Glass 1 Glass 2 Glass 3 Glass 4 Glass 5 SiO.sub.2 42 49.8 41.1 46.8 46 Al.sub.20.sub.3 17 9.2 16.4 8.2 12 B.sub.2O.sub.3 26 25.8 25.4 28.2 26 Na.sub.20 15 15.1 11.4 12.8 12 CaO 6 4 TiO.sub.2 4 Total: 100.0 99.9 100.0 100 100 B.sub.2O.sub.3 / 0.619 0.518 0.618 0.603 0.565 SiO.sub.2

[0093] For the working examples glass 1 to glass 5, the following glass properties and powder properties were ascertained by heating microscopy (EHM):

TABLE-US-00004 Glass 1 Glass 2 Glass 3 Glass 4 Glass 5 CTE(20;300? C.) 8.49 7.9 7.31 7.42 7.33 [ppm/K] Density [g/cm.sup.3] 2.336 2.383 2.411 2.412 2.335 Tg [? C.] 495 528 544 535 485 Ew [? C.] 658 673 656 647 EHM: 577 544 555 525 sintering [? C.] Softening [? C.] 643 670 675 670 663 Sphere [? C.] 764 723 740 719 725 Hemisphere 843 801 828 806 836 [? C.] Flow temp. 926 864 907 864 906 [? C.]

[0094] For glass 1 to glass 5, storage of sintered specimens in 0.9% saline solution at 37.5? C.:

TABLE-US-00005 Weight loss Glass 1 Glass 2 Glass 3 Glass 4 Glass 5 1 d 0.003% 0.005% 2 d 0.01% 0.003% 3 d 0.01% 0.005% 4 d 0.00% 0.02% 0.060% 0.00% 5 d 6 d 0.00% 7 d 0.03% 0.00% 24 d 0.0% n.d.

[0095] For glass 1 to glass 5, properties of sintered specimens:

TABLE-US-00006 Weight loss [%] Glass 1 Glass 2 Glass 3 Glass 4 Glass 5 Cold etch 1.51 0.08 1.84 0.6 0.7 (HF) HCl 4.22 1.2 1.2 1.1 0.4 Strike Ni 0.78 0.57 0.41 0.1 0.1 Acidic before 0.96 0.91 0.89 0.1 0.1 Au H2O - pure 0 0.1 0 0 0.1 Hot degreas 0.05 0.09 0.05 0 0

[0096] The data in the table above suggests that glasses 2 to 5 have higher galvanic stability than glass 1. What is meant by galvanic stability is essentially stability to the aqueous chemicals used in typical galvanic pretreatment and coating processes (acids, alkalis and electrolytes). Hot degreas represents a hot wash liquor for degreasing.

[0097] The glass of the insulation material may also have been admixed with coloring components, e.g. CoO, or pigments, for example spinel-based pigments.

[0098] It is further possible that the glass includes fillers, for example low-expansion fillers, e.g. cordierite. A proportion of low-expansion fillers can make it possible under some circumstances to lower the coefficient of thermal expansion of the glass.

[0099] For example, with a proportion of 11% cordierite (melt for production of cordierite as filler), the lowering in the coefficient of thermal expansion (CTE) of glass 2 can be set to a value of about 7.0 ppm/K, especially without significant loss in the relevant properties.

[0100] For a saline solution test, the test object is produced from glass powder (like the compacts). The glass powder is stirred with demineralized water until small lumps form, which are then pressed manually into cylinder shape and sintered under nitrogen about 30 to 40? C. above the sphere temperature. The test objects usually weigh 0.5 g. The saline solution has a strength of 0.9%. About 120 ml of saline solution is warmed to about 37? C. in a beaker.

[0101] The test object lies at the edge of the beaker. A magnetic stirrer is set such that the saline solution is clearly in motion, but the test object is not moved. The beaker is covered with a glass lid, such that barely any concentration differences arise owing to evaporation. The test object is weighed before the test and once per day, and the relative loss of mass is used as a comparative value.

[0102] Some comparative glasses (Comp. 1 to 4) are specified hereinafter, which were characterized by the same methods as the abovementioned examples glass 1 to glass 5. Comparative glasses: composition in % by weight:

TABLE-US-00007 % by wt. Comp. 1 Comp. 2 Comp. 3 Comp. 4 SiO.sub.2 7.3 47.7 Al.sub.2O.sub.3 18.6 4.5 16.2 30 B.sub.2O.sub.3 25.1 15.8 24.9 42 Na.sub.2O 7.45 K.sub.2O 0.4 CaO 14 14.3 7.2 16 MgO 7.9 12 SrO 6.8 ZrO.sub.2 9.33 TiO.sub.2 16.25 La.sub.2O.sub.3 20.3 35.5

[0103] Comparative glasses: glass properties and powder properties by heating microscopy (EHM):

TABLE-US-00008 Comp. 1 Comp. 2 Comp. 3 Comp. 4 CTE(20;300? C.) 7.8 7.0 7.1 6.2 [ppm/K] Density [g/cm.sup.3] 3.19 2.68 3.62 2.6 Tg [? C.] 620 612 643 617 Ew [? C.] 718 732 726 718 EHM: Softening [? C.] 722 760 738 Sphere [? C.] 746 797 Hemisphere 845 883 1031 [? C.] Flow temp. [? C.] 909 953 1094

[0104] Sintered specimens of comparative glasses: storage in 0.9% saline solution at 37.5? C.:

TABLE-US-00009 Weight loss [%] Comp. 1 Comp. 2 1 d 0.32 0.016 2 d 0.46 0.032 3 d 0.47 0 4 d 0.70 0.020

Comparative Examples: Properties of Sintered Specimens

[0105]

TABLE-US-00010 Weight loss [%] Comp. 1 Comp. 2 Cold etch (HF) 0.21 0.36 HCl 0.57 0 Strike Ni 0.11 0 Acidic before 0.16 0.01 Au H2O - pure 0 0.01 Hot degreas 0 0.03

[0106] Storage of the comparative glass Comp. 1 in saline solution shows that a more than 10-fold weight loss occurs by comparison with the abovementioned glasses.

[0107] This insufficient stability on storage in NaCl solution shows that this Comp. 1 can be considered unsuitable for use in contact with body fluids, depending on the specification.

[0108] Characterization by EHM shows that Comp. 2 with a hemisphere temperature of about 880? C. and a flow temperature of 953? C. can be considered to be on the borderline for an optional feedthrough. In experiments, a vitrification temperature of about 980? C. was required for production of feedthroughs.

[0109] Characterization by EHM indicates that Comp. 3 with a hemisphere temperature well above 1000? C. cannot be vitrified at lower temperatures or, for example, temperatures below 900? C.

[0110] The glass Comp. 4 showed unsatisfactory adaptation to titanium; this type of glass spreads poorly on titanium. In the case of poor spreading and/or inadequate wetting, pressure may be needed, for example in the form of weights. However, such a course of action is less optional since it is more complex, especially for miniaturized designs and/or designs with complex pole geometries, for example designs with a multitude of electrical conductors and small distances between those conductors and/or designs with a multitude of electrical conductors, for example more than 10 electrical conductors.

[0111] Glasses 1 to 5 and comparative glasses 1 and 2 (without use of weights) have a wetting angle or contact angle on titanium of less than 90? C. This has a number of advantages in the production of feedthroughs. There is no need to press carbon dies onto the glass in order to achieve desired surface forms; soiling and sticking of carbon dies on glass surfaces (which can cause insulation problems) are avoided; and differences in coefficients of thermal expansion between carbon fixings and metal components do not constitute a barrier in the design of melt fixings.

[0112] The test glasses and comparative glasses were produced by melting the glasses on a 11 scale and forming them to castings, and also to ribbons of width about 1-2 cm. The cooled castings were used for purposes including determining the density, the coefficient of linear thermal expansion in the range from 20? C. to 300? C., i.e. CTE (20; 300? C.), and the fixed viscosity points T.sub.g and Ew by methods familiar to the person skilled in the art.

[0113] The coefficient of linear thermal expansion CTE was determined in the range of 20 to 300? C. from determination of the length change characteristics on solid-state bodies of length 100 mm by dilatometry.

[0114] Density was determined by measurement of buoyancy.

[0115] The softening temperature Ew (i.e. the temperature at which the lg of viscosity [dPas] is 7.6) was determined by viscometry on a square thread.

[0116] In order to ascertain the powder properties, ribbons of the test glasses were ground to a defined grain size (K3) and then characterized.

[0117] A generally customary method for determination of the vitrification-relevant temperatures is the method of heating microscopy (EHM).

[0118] In addition, the powders were sintered and characterized. The weight loss was ascertained on sintered specimens after exposure to chemical solutions, which represents the different treatments in galvanic processes.

[0119] In order to determine galvanic stability, compacts were produced from the ground powders of the test glasses and sintered. These sintered samples were then immersed in baths that simulate galvanic treatment, and the loss of mass was determined.

[0120] In order to determine stability in saline solution, the sintered specimens were stored in 0.9% saline solution at 37.5? C. for a period of 1-24 days. The loss of mass was then determined.

[0121] In order to determine cytotoxicity, the test for a cytotoxic effect of the test glasses was conducted according to standard EN ISO 10993-5: Test for in vitro cytotoxicity. No cytotoxic effect was detected for the glasses of the present invention.

[0122] In the production of feedthroughs, cleaning and coating in galvanic baths can be implemented, especially in order to improve functionalities such as weldability, bondability and solderability. The individual components, especially the glass used, are therefore optionally designed to be stable in such baths.

[0123] 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.