Metal fixing material implementation, methods for its production and its uses

Description

[0001] The invention relates to a metal fixing material feedthrough according to claim 1, a method according to claim 13 and a use according to claim 15.

[0002] Sensor feedthroughs can, in particular, supply power to sensor elements and / or transmit their signals to evaluation units. Large feedthroughs are generally used in containment vessels, for example, in liquefied gas tanks and / or reactors.

[0003] Battery or capacitor feedthroughs are generally understood to be feedthroughs through the housings of batteries, including accumulators, or capacitors. The term also encompasses the field of supercapacitors, also known as supercapacitors. The feedthrough is typically used to contact electrodes inside the battery or capacitor housing.

[0004] A transistor outline package, also called a TO package, is a power-carrying electronics housing. A TO package basically consists of two components: a base and a cap. While the base primarily ensures the power supply to the encapsulated components, the cap in optoelectronics serves to reliably transmit optical signals. This includes both transmitters (e.g., laser diodes) and receivers of optical signals (e.g., photodiodes). The TO base represents the mechanical basis for the assembly of electronic and optical components, such as semiconductors, laser diodes, or even a simple electrical circuit. At the same time, it supplies the protected components with power via connection pins.

[0005] Airbags and / or seat belt pretensioners are particularly used as pyrotechnic personal protection devices in motor vehicles. Such safety systems can significantly reduce the risk of injury. However, this requires that the respective safety systems do not fail in the event of a collision. Particular attention is paid to the igniters of such pyrotechnic devices, which are essential for the function of such a safety device. In particular, the igniters must continue to function perfectly even many years after their manufacture. The average service life of such igniters is often stated to be 15 years. To ensure long-term, flawless function, it must be ensured that the propellant charge in the igniter does not change over time. Such changes can be caused, for example, by moisture penetrating the igniter.It is therefore important to hermetically seal the propellant charge of the detonator. The detonator must also release the gases from the ignited propellant charge in the correct direction to ignite the propellant charge of a gas generator in the safety system.

[0006] To ensure this, prior art detonators comprise a cap or lid and a relatively solid base, between which the propellant charge is enclosed in a cavity formed from these parts. The current for igniting the propellant charge is conducted through the base via electrical connections. Therefore, the base typically has through-holes containing metal pins that can be supplied with electrical current via a plug connection on one side and are connected, for example, by an ignition bridge on the other side, which ignites the propellant when the current flows through it.

[0007] The base is therefore also commonly referred to as a feedthrough element. When designing the feedthrough element, it must be ensured that the cap or lid, or part of it, is torn off upon ignition of the propellant charge, and that the electrical feedthroughs are not forced out of the base.

[0008] In such feedthrough elements, the base body of the socket is made of metal, and the ignition bridge is realized by means of a welded bridge wire. In this embodiment, a metal pin is fixed as a pin in an electrically insulating fixing material in a through-hole of the base body. A glass material, particularly a glass solder, is typically used as the fixing material. This means that this metal pin is insulated from the outer conductor by glass. Ceramic, glass-ceramic, and / or polymer are also possible as insulation materials.

[0009] A second metal pin is welded or soldered to the outer conductor, which is represented by the base body or base plate. On the upper side of the feedthrough element—the side facing the ignition cap of the final assembly—a bridge wire (usually made of a tungsten alloy) acts as an ignition bridge and comes into contact with the surface of the glass material. To prevent damage to the bridge wire and to ensure the ignition element has a long service life, for example, in a motor vehicle, the surface of the glass material must usually be ground, as surface roughness can damage the bridge wire.

[0010] Ignition devices of the aforementioned type are known, for example, from EP 1813906 B1. JP H06 185897 A discloses a metal-fixing material bushing.

[0011] EP 0586133 A2 describes the production of metal fixing material feedthroughs for airbag igniters, in which the contact pin is glazed into a glass material in the through-hole and the surface of the base body and the fixing material is ground before the bridge wire is attached.

[0012] TO packages are shown, for example, in US Pat. No. 8,908,728 B1. Here, it is conceivable to connect a ground pin to the base body to electrically ground the base body.

[0013] Against this background, it is the object of the present invention to provide a metal fixing material feedthrough for a feedthrough element, in particular for igniters of airbags and / or belt tensioners, in which the disadvantages of the prior art are avoided and grinding of the surface is avoided, as well as a method for production.

[0014] This object is achieved by the metal fixing material feedthrough and the method for its production according to the independent claims. Preferred embodiments and applications are set out in the dependent claims.

[0015] The metal-fixing material feedthrough according to the invention comprises a particularly metallic base body and at least one through-opening in which at least one metal pin is fused into an electrically insulating glassy or glass-ceramic fixing material and thus fixed therein. The surface of the glassy or glass-ceramic fixing material is a freely fused surface, which is particularly advantageously free of exposed bubbles. "Freely fused" within the meaning of the invention means that the surface forms spontaneously as the molten glass material cools. It visually resembles fire-polished surfaces and is recognizable as such with the naked eye, particularly since it can exhibit a mirror-like shine.

[0016] The surface of the melted-free fixing material lies flush with the end face of the at least one metal pin fused into the fixing material. This naturally refers to the end face of the metal pin closest to the fixing material and intended for connection to the conductor or ignition conductor, i.e., the top side of the metal-fixing material feedthrough.

[0017] The metal-fixing material feedthrough is typically manufactured from a compact, which is placed in the through-hole together with the metal pin and then heated so that the compact melts and bonds with the base body and the metal pin. The compact is typically produced by grinding the glass or glass-ceramic material, adding a binder (usually organic) to it, and pressing it into shape. It is also possible for the compact to be sintered before the metal pin is melted. It is also possible for the glass-ceramic material to form from the previously amorphous, glassy material during heating and / or cooling.

[0018] When the metal pin is melted and bonded to the base body, the binder burns out. The glassy or glass-ceramic fixing material in the through hole is usually filled with bubbles and protrudes beyond the surface of the base body. Likewise, the metal pin is usually positioned so that it protrudes above the surface of the base body. Therefore, to achieve a flat, level surface, it is assumed that the surface must be ground flat.

[0019] In contrast, according to the present invention, the surface of the fixing material is melted free during the melting process. In particular, the at least one metal pin is arranged in the through-hole such that its end face is flush with the surface of the base body. The inventors have found that melting free results in a smooth surface of the glassy or glass-ceramic fixing material, making grinding unnecessary.

[0020] The invention also provides for an electrical conductor, in particular an ignition conductor, to be mounted between the base body and the at least one metal pin, which electrically connects the base body and the at least one metal pin. The surface of the fixing material is free of exposed bubbles, at least in the area of the conductor.

[0021] It is particularly advantageous for the entire surface of the fixing material to be free of exposed bubbles. However, it is also technically sufficient and within the scope of the invention if the entire surface of the fixing material is substantially free of molten bubbles, which is understood to mean a maximum of five open bubbles on the surface. These can be distributed over the surface, but as described, not in the area where the ignition wire is present, i.e., in particular, where it rests on the fixing material.

[0022] Typically, mild steel such as St 35 and / or St 37 and / or St 38 or stainless steel and / or rust-proof steel are used as the material for the base body. Stainless steel according to DIN EN 10020 is a designation for alloyed or unalloyed steels whose sulfur and phosphorus content (so-called iron constituents) does not exceed 0.035%. Further heat treatments (e.g., tempering) are often required. Examples of stainless steels include high-purity steels, in which components such as aluminum and silicon are precipitated from the melt through a special manufacturing process, as well as high-alloy tool steels intended for subsequent heat treatment. These steels contain chromium in particular. Examples of materials that can be used are: X12CrMoS17, X5CrNi1810, XCrNiS189, X2CrNi1911, X12CrNi177, X5CrNiMo17-12-2, X6CrNiMoTi17-12-2, X6CrNiTi1810 and X15CrNiSi25-20, X10CrNi1808, X2CrNiMo17-12-2, X6CrNiMoTi17-12-2.

[0023] To ensure maximum manufacturing efficiency for the feedthrough according to the invention, the metallic base body can advantageously also be made of non-stainless steel. Instead, the base body is advantageously made of a steel from group 1.01xx to 1.07xx (unalloyed quality steels). The steel group is specified according to DIN EN 10 027-2, with the first digit indicating the main material group and the sequence of digits after the first decimal point indicating the steel group number.

[0024] To ensure the best possible corrosion resistance, the base body can be coated with metals. A nickel coating is preferred. This is especially true for base bodies made of unalloyed quality steels.

[0025] The glassy or glass-ceramic fixing material is preferably selected so that its thermal expansion is lower than that of the metallic base body. During melting and subsequent cooling, the base body shrinks onto the solidified fixing material, creating a so-called pressure feedthrough, also known as pressure glazing. This means that the base body exerts axial pressure on the fixing material, which increases its mechanical holding force in the through-hole.

[0026] In this way, a hermetically sealed metal-fixing material feedthrough is achieved.

[0027] The inventors have determined that, in the procedure described above, particularly during surface melting, the glassy or glass-ceramic fixing material may contain bubbles with a bubble fraction BV within its volume, but a glass skin on its surface, which has a bubble fraction significantly smaller than BV. Particularly preferably, the glass skin is essentially bubble-free, meaning that there are no more than five bubbles, or even completely bubble-free. In particular, the glass skin and / or the surface of the fixing material is bubble-free in the area where the ignition wire rests.

[0028] Because the fixation material has a molten surface, its roughness is lower than that of previously ground metal fixation material feedthroughs. In particular, the average roughness Ra of the surface of the glassy or glass-ceramic fixation material is less than 0.1 µm, particularly in the range of 0.02 µm to 0.05 µm. In contrast, typical Ra values for previously ground metal fixation material feedthroughs are between 0.2 µm and 0.5 µm. The higher roughness values of the previously ground fixation material generally result from the remaining grinding marks, particularly in the form of grooves.

[0029] The mean roughness Ra is defined according to DIN EN ISO 4287:2010 and is determined in a manner familiar to those skilled in the art. The mean roughness, or mean roughness Ra, indicates the average distance of a measurement point within a vertical section, i.e., the profile of the microstructure, from the center line. The center line intersects the actual profile within the reference section in such a way that the sum of the profile deviations (relative to the center line) is minimized. The mean roughness Ra thus corresponds to the arithmetic mean of the absolute deviation from the center line.

[0030] The smoother surface of the metal-fixing material feedthrough according to the invention has the further advantage over the prior art of reducing the risk of damage to the bridge wire when it rests on the fixing material. In airbag igniters or belt tensioners, the bridge wire is in contact with the igniting material, which can often be in powder form. Even if the grain size of the powder is usually larger than the grooves of the grinding marks, powder abrasion and thus very fine grain can develop over the course of the product's lifetime, which can become wedged into the grooves under the bridge wire and thus exert mechanical stress on it. The metal-fixing material feedthrough according to the invention prevents this.

[0031] In a further preferred embodiment, the base body is designed such that there is a continuous transition from the surface of the base body to the inner wall of the through-opening, in particular with an increasing gradient towards the inner wall of the through-opening. Continuous transition means that if the section through this area is viewed as a curve, the first derivative of this curve has a continuous course. In contrast, the base bodies from the prior art have a sharp bend, so that the first derivative of their section is discontinuous. This design has the advantage that the base body can be easily manufactured using forming and / or punching processes, in particular the through-opening, without the need for further post-processing steps to achieve vertical angles.A further advantage of this base body design is that the volume of the compact, which determines the fill level of the fixation material in the through-hole, is less sensitive to volume fluctuations. This means that for a given volume fluctuation, the fill level in the through-hole changes less than the diameter of the fixation material, which is less critical for the attachment of the bridge wire than a possible step that would result from insufficient filling.

[0032] The continuous transition also results in a thin layer of fixing material on the area that slopes gently toward the through-hole. Surprisingly, despite the pressure-induced glazing, no flaking of the fixing material was observed.

[0033] Particularly preferably, a trench is provided between the inner wall of the through-opening and the glassy or glass-ceramic fixing material in the region of its surface. A trench generally represents a depression in the surface of the fixing material. The width B of the trench is preferably at most 0.13 mm, particularly preferably from 0.005 mm to 0.13 mm or 0.01 to 0.13 mm. Particularly preferably, the depth T of this trench is at most 0.03 mm, in particular at most 0.015 mm, and particularly preferably the depth T is between 0.05 mm and 0.025 mm.

[0034] The formation of the trench can be promoted by the aforementioned design of the transition from the surface of the base body to the inner wall of the through-opening, ie this design and the presence of the trench interact particularly advantageously.

[0035] The presence of the trench has the advantage that it can prevent film deposition on the surface of the fixing material and / or the surface of the base body, particularly during operation of the metal fixing material feedthrough. Such films can be, in particular, water-containing films and / or deposits, which can occur during long-term operation and, in the worst case, can lead to reduced contact resistance, short circuits, and / or electrochemical corrosion, and thus to damage to the component including the metal fixing material feedthrough.

[0036] The groove can advantageously form spontaneously during the melting of the fixation material and its subsequent cooling. It is assumed that this results from the adhesion and wetting properties of the glassy or glass-ceramic fixation material. It is also possible to emboss the groove while the heated fixation material is still malleable.

[0037] An advantageous embodiment is one in which the glassy or glass-ceramic fixing material rests on and / or contacts the surface of the at least one metal pin without forming a groove. This means that the aforementioned groove is located only in the transition region from the fixing material to the base body and not in the transition region from the fixing material to the metal pin. This can be achieved in particular if the radius of any rounded portion on the metal pin, i.e., the overhang from its end face to the lateral surface, is smaller than the radius of the transition of the base body from its surface to the inner wall of the through-opening.

[0038] As already described, the trench can advantageously serve as a barrier for interfering films covering the surface, which can influence the electrical behavior of the electrical conductor, particularly its ignition behavior. On the other hand, the trench is advantageously dimensioned so that no interfering large particles can become trapped between them and the electrical conductor and thus place excessive mechanical stress on the conductor.

[0039] In particular, the metal pin is arranged such that the top side, i.e., the flat end face of the metal pin, lies flush with the surface of the glassy or glass-ceramic fixing material. Advantageously, the metal pin is rounded, i.e., in particular, the transition between the top side of the metal pin and its side wall is rounded, with the transition point between this rounding and the side wall lying below the surface of the glassy or glass-ceramic fixing material.

[0040] In particular, the trench is circumferential, preferably circular. The through-opening is preferably circular in plan view, and the trench follows the inner wall of the through-opening in a circular manner, possibly with a gap.

[0041] Particularly preferred is a metal-fixing material feedthrough in which an electrical conductor, in particular a wire-shaped conductor, in particular an ignition conductor, is arranged between the base body and the at least one metal pin, which electrically connects the base body and the at least one metal pin. The conductor rests at least partially on the surface of the glassy or glass-ceramic fixing material and preferably bridges the trench. InIn this area, where the trench is bridged, there is a free space beneath the conductor. It is also possible to fill and / or coat this free space, e.g., with a plastic, particularly a hydrophobic plastic or one with a hydrophobic surface. As described, the trench can serve as a tear-off edge, particularly for electrically conductive coatings or corrosive films. The surrounding edge shields the fixing material and / or the at least one metal pin from these coatings and / or films.

[0042] In a further preferred embodiment, the base body consists of a steel, in particular stainless steel, at least at the interface with the glassy or glass-ceramic fixing material. Likewise, the at least one metal pin consists of a steel, in particular stainless steel, at least at the interface with the glassy or glass-ceramic fixing material. Particularly advantageously, the steel and / or stainless steel exhibits wetting and / or adhesion to glass, which at least supports the formation of the trench.

[0043] It is advantageous, and encompassed by the invention, if the top side of the metal pin lies in a plane with the surface of the glassy or glass-ceramic fixing material. In particular, the transition between the top side of the metal pin and its side wall can be rounded, with the transition point between this rounding and the side wall lying below the surface of the glassy or glass-ceramic fixing material. The rounding is thus, so to speak, drawn into the fixing material. Compared to a sharp transition, in which the side wall of the metal pin meets its surface directly perpendicularly, this has the advantage of reducing the likelihood of crack formation at the interface between the metal pin and the fixing material.

[0044] As described, the top side of the metal pin, i.e. its end face, lies in a plane with the surface of the glassy or glass-ceramic fixing material. In particular, the transition between the top side of the metal pin and its side wall can be rounded, with the transition point between this rounding and the side wall lying below the surface of the glassy or glass-ceramic fixing material. The rounding is thus, so to speak, drawn into the fixing material. Compared to a sharp transition, where the side wall of the metal pin meets its surface directly perpendicularly, this has the advantage of reducing the likelihood of crack formation at the interface between the metal pin and the fixing material.

[0045] It is also provided that an electrical conductor, in particular an ignition conductor, is mounted between the base body and the at least one metal pin, which electrically connects the base body and the at least one metal pin. This conductor is typically welded in place. This conductor rests at least partially on the surface of the glassy or glass-ceramic fixing material. In particular, it bridges the described trench.

[0046] The invention also includes the method for producing a metal fixing material feedthrough, in particular for igniters of airbags and / or belt tensioners, with at least one metal pin which is fused into a through-opening of a base body in a glassy or glass-ceramic fixing material by heating and subsequent cooling, which has a surface between the at least one metal pin and the base body, wherein when the at least one metal pin is fused into the glassy or glass-ceramic fixing material, the heated fixing material is melted free at this surface.

[0047] During this process, the fixing material glazes onto the inner wall of the through-opening and the outer wall of the at least one metal pin. All features previously described with regard to the metal fixing material feedthrough are also transferable to the method.

[0048] The claimed method comprises part of the overall manufacturing steps of a bushing and / or an airbag igniter or belt tensioner.

[0049] Preferably, a substantially bubble-free surface of the fixing material forms, in particular spontaneously, during the melting process. Substantially bubble-free means a maximum of 5 bubbles on the surface, which of course also includes a complete absence of bubbles. Preferably, the average roughness Ra of the surface of the glassy or glass-ceramic fixing material is less than 0.1 µm, in particular Ra is in the range from 0.015 µm to 0.055 µm, particularly advantageously from 0.02 µm to 0.05 µm. In a preferred embodiment, the glassy or glass-ceramic fixing material lies against the surface of the at least one metal pin without forming a groove. This means that it is particularly advantageous if the groove is present between the base body and the fixing material, but not between the fixing material and the metal pin.

[0050] The through-opening itself is preferably circular in plan view, and the trench particularly preferably follows the inner wall of the through-opening in a circular manner. A circular through-opening can be achieved, in particular, by punching and / or forming. However, drilling and other suitable methods are also possible.

[0051] As already described, a particularly advantageous method is to produce the base body and / or the through-hole by forming and / or punching. The base body can be produced by forming, with the at least one through-hole being punched out, in a particularly material-efficient manner.

[0052] It is particularly advantageous if the base body is or will be shaped in such a way that there is a continuous transition from the surface of the base body to the inner wall of the through-hole, particularly with an increasing gradient toward the inner wall of the through-hole. This corresponds, so to speak, to a rounding with a progressive gradient. This shape can be created particularly during the punching process of the through-hole.

[0053] In a preferred method, a trench (55) forms automatically between the inner wall of the through-opening and the glassy or glass-ceramic fixing material in the region of the surface thereof upon heating and / or cooling. Alternatively, this trench is embossed, for example, with a stamping or embossing tool. In particular, the trench has a width B that is preferably at most 0.13 mm. Particularly preferably, the depth T of the trench is at most 0.03 mm, in particular at most 0.015 mm, and particularly preferably the depth T is between 0.05 mm and 0.025 mm.

[0054] It is also possible to create the trench using suitable tools, such as stamps, or by removing material.

[0055] During further processing, an electrical conductor can be attached, in particular welded, between the metal pin and the surface of the base body as described.

[0056] It is also common practice for at least one additional conductor, particularly a metal pin, to be electrically connected to the base body. This is usually a grounding or earthing conductor. The described electrically conductive connection of a metal pin to the base body is usually a soldered connection. It is also possible to weld this conductor to the base body.

[0057] Preferred applications of the metal fixing material implementation according to the invention and / or the method result according to the invention are in airbag igniters and / or belt tensioners and / or gas generators.

[0058] In airbag igniters and / or belt tensioners and / or gas generators, the metal pin fixed in the through-hole, as well as the ground pin soldered to the base body, are usually gold-plated at least in sections along their axis. The gold coating ensures permanent resistance to corrosion and a permanent contact. The metal pins are often gold-plated at their ends. This preferably gold-plated area of the metal pin that is located inside the plug connection during assembly for use with the igniter. This reduces the contact resistance in the plug contact.

[0059] In an advantageous embodiment, at least two metal pins on the side of the base body facing the propellant are electrically connected to each other by means of an ignition bridge. The ignition bridge can be formed by the ignition wire described above.

[0060] As described above, the roughness of the fixing material surface, or rather smoothness in the sense of the invention, can be characterized by the average roughness Ra. Likewise, the average roughness depth Rz can be specified as known to those skilled in the art.

[0061] In tests, which also represent exemplary embodiments, the described metal fixing material feedthrough was manufactured using the described method, and the roughness of the fixing material surface was determined, which was melted free according to the invention. For comparison, Table 1 also shows the measured values for fixing material surfaces ground according to the state of the art. The tactile measurement method used, known to those skilled in the art, using a Hommel probe, was used. Table 1: Roughness measurements on melted fixing material surface According to the invention: Freely melted fixing material surface State of the art: Ground fixing material surface Measurement No. Ra [µm] Rmax [µm] Rz [µm] Ra [µm] Rmax [µm] Rz [µm] 1 0,032 0,301 0,249 1,206 15,524 9,217 2 0,030 0,293 0,235 0,905 14,364 9,974 3 0,024 0,275 0,192 0,679 11,667 7,082 4 0,023 0,662 0,261 0,954 11,466 9,286 5 0,024 0,178 0,166 1,174 14,079 8,915 6 0,023 0,200 0,168 Mean: 0,026 0,212 0,984 8,895

[0062] The invention is explained in more detail below with reference to the figures. The drawings are not to scale; the illustrated embodiments are schematic. The figures also represent exemplary embodiments. All reference numerals shown in the figures also apply to the other figures. Figure 1 shows a known ignition device including a metal fixing material feedthrough according to the prior art, with a ground surface on which the ignition wire rests. Figure 2 shows a section through a metal fixing material feedthrough according to the invention parallel to its axial center axis. Figure 3 shows an excerpt from Figure 2 . Figure 4 shows the photograph of the top view of a metal fixing material penetration according to the invention and the measurement curve of the trench survey.

[0063] In Figure 1A prior art ignition device for a pyrotechnic protective device is shown, here an airbag igniter as an example. Figure 1in particular a sectional view of a metal fixing material feedthrough. The metal fixing material feedthrough comprises a metal carrier part with a base body (1), which in this case has a disc-shaped basic shape. Basic shapes with a release area are also known and encompassed by the invention. The metal fixing material feedthrough according to the invention is often also referred to as a base element or, in short, base or header. A metal pin (5) as a functional element is also arranged in a through-opening (4) of the base body (1). The through-opening (4) was punched out of the base body (1). The metal pin (5) serves to contact an ignition bridge (9) with electrical current, via which the propellant charge (25) enclosed in the finished igniter is ignited. The ignition bridge rests on the upper side (11) of the base body. The side facing the propellant charge is referred to as the upper side.The ignition device is closed by the cap (2), which, together with the base body (1), forms a cavity for accommodating the propellant charge (25). The cap (2) is usually welded to the base body.

[0064] In the prior art, the current feedthrough in the through-hole (4) is designed, in particular, as a glass-to-metal feedthrough, with glass serving as the fixing material (10) between the metal pin (5) and the wall of the through-hole (4) in the metallic base body (3). It is also possible to use high-performance polymers or other suitable materials in the through-hole, as well as glass-ceramic materials.

[0065] The through hole (4) is in the Figure 1In the example shown, it is arranged eccentrically with respect to the axial center axis of the base body (1). This ensures that even with a small radius of the base body (3), there is sufficient space available for attaching a second metal pin (6). The second metal pin (6) is butt-soldered to the base body (1) and thus serves as a ground pin, also called a ground pin (6). Metallic solder materials, in particular hard solder, are used as the solder material (7). The solder material (7) forms a meniscus between the surface of the base body and the ground pin (6).

[0066] Figure 2shows a section through a metal fixing material feedthrough according to the invention, parallel to and through its axial center axis. The base body (1) has a first surface (11), here the top side, and a second surface (12), here the bottom side, which runs parallel thereto in many embodiments. The top side (11) usually faces the propellant (25), and the electrical contacts are usually made on the bottom side (12). The metallic base body (1) has a through-opening (4) through which the metal pin (5) is guided as a pin. The through-opening (4) can be punched out of the base body (1). In this example, the outer contour of the base body (1) was also punched out of a sheet metal strip, so that the entire base body (1) represents a punched part.However, it is also possible, and encompassed by the invention, for the base body to be produced from a wire material by cold forming. The metal pin (5) is fused, i.e., fixed, in the through-hole (4) as the first pin, also called a contact pin, by means of a glassy or glass-ceramic fixing material (10), electrically insulated from the base body (1).

[0067] The first metal pin (5) is, in particular, hermetically sealed in the first through-hole (4) of the metallic base body (1). The glassy or glass-ceramic fixing material (10) of this metal-fixing material feedthrough is completely surrounded by the material of the base body (1), which represents the outer conductor.

[0068] The glassy or glass-ceramic fixing material (10) has, in particular, a lower thermal expansion coefficient than the metal of the base body (1), so that when the base body (1) cools after the metal pin (5) has been glazed into the fixing material (10), it virtually shrinks onto the metal pin and thus the glass-metal feedthrough, thereby exerting permanent mechanical pressure on the feedthrough and the fixing material (10). In this way, a particularly tight and mechanically stable connection is created between the metal pin (5), the fixing material (10), and the base body (1). This arrangement is called pressure glazing and is preferred, for example, for airbag igniters. The use of glass materials and / or glass-ceramic materials is also possible and encompassed by the invention.

[0069] The surface (110) of the fixing material (10) on the upper side (11) of the base body (1) is a fused surface and lies in a plane with the end face (50) of the fused metal pin (5) and advantageously also in a plane with the upper side (11) of the base body. As already described, the fused surface is advantageously characterized by a glass skin (40) which, compared to the volume of the fixing material (10), has a reduced proportion of bubbles, in particular no open bubbles on its surface (110), at least in the region of the ignition conductor.

[0070] The ignition conductor (9) rests on the surface (110) of the fixing material and is welded to both the metal pin (5) and the base body (1), i.e., to the end face (50) of the metal pin (5) and the surface (110) of the base body (1). The groove (55) is not shown.

[0071] The second metal pin (6) is connected to the base body (1) as a ground pin using solder material (7).

[0072] Figure 3 shows an excerpt from Figure 2 , which in Figure 2 is shown as a broken rectangle. This corresponds to an enlargement of the base body (1), the fixing material (10), and the end face (50) of the metal pin (5). For the sake of simplicity, the ignition wire (9) is not shown.

[0073] However, evident in Figure 3is the trench (55) located between the base body (1) and the fixing material (10). The trench has a width B and a depth T. The trench (55) can be designed, in particular, as a meniscus-shaped formation of the fixing material (10) on the base body (1). The width B of the trench is at most 0.13 mm, in particular from 0.005 mm to 0.13 mm or from 0.01 to 0.13 mm, and a depth T of at most 0.03 mm, in particular from 0.015 mm to 0.05 mm, in particular the depth T is between 0.025 mm and 0.05 mm.

[0074] In particular, the radius of the transition between the surface (11) of the base body and the inner wall (100) of the through-hole can be larger than the radius of the transition between the outer wall of the fused metal pin (5) and its end face (50). For the sake of simplicity, this radius is not shown in Figure 3This ratio, however, contributes in particular to the fact that the trench (55) is present at the transition to the base body (1), but not at the transition to the metal pin (5).

[0075] Also shown in Figure 3 is the glass skin (40), which has a significantly lower bubble content than the volume of the fixation material (10). Figure 3 A glass skin (40) is located on the top side (11) of the metal fixing material feedthrough. It is also possible, and encompassed by the invention, for a glass skin to be present on the bottom side (12) as well. This is particularly the case if the fixing material (10) on the bottom side (12) is also melted free.

[0076] The glass skin is visible by optical methods, especially with a microscope, although its thickness can be in the atomic layer range.

[0077] The inner wall (100) of the through-hole (4) is in direct contact with the fixing material (10), and the fixing material (10) is glazed onto the inner wall (100). It is also possible for a glass skin with a reduced bubble content to be present between the inner wall (100) of the through-hole and the fixing material (10). The same applies to the interface between the fixing material (10) and the outer wall of the metal pin (5).

[0078] Figure 4shows a photograph of a top view of a metal fixing material penetration according to the invention and the measurement curve of the trench survey. The penetration opening is circular and filled with the fixing material (10). The metal pin (5) is encased in the opening, and its end face (50) is visible. The inner wall (110) of the penetration opening is highlighted again by the broken line. As described, this is an unpolished surface; the fixing material surface has been melted free. No exposed bubbles are visible. The glass skin is, so to speak, smooth or dense.

[0079] Also shown is the measurement of the trench (55) with regard to its depth T and width B. The measurement was carried out using a digital measuring microscope.

[0080] Until now, the metal-to-fixing material feedthroughs, particularly in industrial mass production for airbag igniters and / or seat belt pretensioners, were ground on their upper surface, with both the metal and the fixing material surfaces being ground. This is usually followed by a cleaning step.

[0081] In contrast, the metal-fixing material feedthroughs according to the invention have the advantage that their fixing material surface is melted free. This results in the metal surface being unpolished, thus eliminating processing steps. Furthermore, the glassy or glass-ceramic fixing material according to the invention has the property of forming a surface that is at least largely free of bubbles upon melting, thus significantly reducing the risk of exposed bubbles. Exposed bubbles should be avoided, as they are undesirable when attaching an ignition wire. List of reference symbols

[0082] 1Base body 2Cap 4Through opening 5Functional element, 1st metal pin 6Conductor, 2nd metal pin, ground pin 7Metallic solder material 9Bridge wire, ignition conductor 10Electrically insulating fixing material 11Surface of the base body, top side 12Surface of the base body, bottom side 25Propellant charge 50End face of the 1st metal pin 55Trench 40Glass skin 100Inner wall of the through opening 110Surface of the fixing material BBreadth of the trench TTepth of the trench

Claims

1. Metal fixing material feedthrough for airbag igniters and / or seat belt tensioner igniters, having at least one metal pin (5) which is melted into a through-opening (4) of a base body (1) in a vitreous or glass-ceramic fixing material (10), wherein the surface (110) of the vitreous or glass-ceramic fixing material (10) is a free-flowing surface which forms by itself when the molten glass material cools, characterized in that the surface of the vitreous or glass-ceramic fixing material lies in the same plane as the end face (50) of the at least one metal pin (5).

2. Metal fixing material feedthrough according to claim 1, characterized in that an electrical conductor (9) or ignition conductor (9) is arranged between the base body (1) and the at least one metal pin (5), which electrically connects the base body (1) and the at least one metal pin (5), and the surface (110) of the vitreous or glass-ceramic fixing material (10) in the area of the conductor (9) or ignition conductor (9) is free of exposed bubbles.

3. Metal fixing material feedthrough according to at least one of the preceding claims, characterized in that the vitreous or glass-ceramic fixing material (10) has bubbles with a bubble content BV in its volume and has a glass skin (40) on its surface (110) which has a bubble content that is considerably smaller than BV or which has at most 5 bubbles or which is bubble-free.

4. Metal-fixing material feedthrough according to at least one of the preceding claims, characterized in that the center roughness Ra according to DIN EN ISO 4287 of the surface (110) of the vitreous or glass-ceramic fixing material (10) is less than 0.1 µm or is in the range from 0.015 µm to 0.05 µm.

5. Metal fixing material feedthrough according to at least one of the preceding claims, characterized in that there is a continuous transition from the surface (11) of the base body to the inner wall (100) of the through-opening (4), preferably with an increasing gradient toward the inner wall (100) of the through-opening (4).

6. Metal fixing material feedthrough according to at least one of the preceding claims, characterized in that a groove (55) is located between the inner wall of the through-opening (4) and the vitreous or glass-ceramic fixing material (10) in the region of its surface (110).

7. Metal fixing material feedthrough according to claim 6, characterized in that the groove (55) has a width B which is at most 0.13 mm or from 0.005 mm to 0.13 mm or from 0.01 to 0.13 mm, and / or wherein the groove (55) has a depth T which is at most 0.03 mm or at most 0.015 mm or the depth T is between 0.05 mm and 0.025 mm.

8. Metal-fixing material feedthrough according to at least one of the preceding claims, characterized in that the vitreous or glass-ceramic fixing material (10) lies against the surface of the at least one metal pin (5) without forming a groove.

9. Metal-fixing material feedthrough according to at least one of claims 6 to 8, characterized in that the through-opening (4) is circular in plan view and the groove (55) circularly follows the inner wall (100) of the through-opening (4).

10. Metal fixing material feedthrough according to at least one of claims 6 to 9, characterized in that an electrical conductor (9) or ignition conductor (9) is attached between the base body (1) and the at least one metal pin (5), which connects the base body (1) and the at least one metal pin (5) in an electrically conductive manner, wherein the conductor (9) or ignition conductor (9) rests at least in some areas on the surface (110) of the vitreous or glass-ceramic fixing material (10) and bridges the groove (55).

11. Metal fixing material feedthrough according to at least one of the preceding claims, characterized in that the base body (1) is made of steel, in particular stainless steel, at least at the interface with the vitreous or glass-ceramic fixing material (10); preferably, the at least one metal pin (5) is made of steel, in particular stainless steel, at least at the interface with the vitreous or glass-ceramic fixing material (10); in particular, the steel and / or stainless steel of the base body (1) has a wetting and / or adhesion to glass which at least supports the formation of the groove (55).

12. Metal fixing material feedthrough according to at least one of the preceding claims, characterized in that the coefficient of thermal expansion of the vitreous or glass-ceramic fixing material is lower than that of the base body, in particular the metallic base body.

13. Method for producing a metal fixing material feedthrough according to at least one of claims 1-12, in particular for airbag igniters and / or seat belt tensioner igniters, having at least one metal pin (5) which is melted into a through-opening (4) of a base body (1) in a vitreous or glass-ceramic fixing material (10), which has a surface (110) between the at least one metal pin (5) and the base body (1), characterized in that when the at least one metal pin (5) is melted into the vitreous or glass-ceramic fixing material (10), the heated fixing material is melted away at its surface (110) by the surface forming itself as the molten glass material cools.

14. Method according to claim 13, characterized in that the coefficient of thermal expansion of the vitreous or glass-ceramic fixing material is lower than that of the base body, in particular the metallic base body, so that during melting and subsequent cooling, the base body shrinks onto the solidified fixing material, resulting in pressure glazing.

15. Use of a metal-fixing material feedthrough according to at least one of claims 1 to 12 in airbag igniters and / or seat belt tensioners or for the production of airbag igniters and / or seat belt tensioners.