Electronic component for limiting inrush current and use of an electronic component

Abstract

The invention relates to an electronic component (1) for limiting inrush currents, comprising at least one NTC element (2) and at least two electrically conductive contact elements (3), wherein the NTC element (2) is electrically conductively connected to the respective contact element (3) via a connecting material (7), and wherein the thermal expansion coefficient of the respective contact element (3) is adapted to the thermal expansion coefficient of the NTC element (2). The invention further relates to the use of an electronic component (1).

Description

[0001] The invention relates to an electronic component for limiting inrush current. The invention further relates to the use of an electronic component.

[0002] Start-stop systems in the automotive sector (cars, trucks) represent a significant opportunity for fuel savings and are therefore installed in almost all new vehicles. In these systems, the starter's inrush current must be limited to prevent a drop in the vehicle's electrical system voltage, ensuring that safety-relevant applications (ABS, ESP) are adequately supplied.

[0003] A thermally controlled inrush current limiter (ICL) can be used for starting an internal combustion engine. When the internal combustion engine restarts after a power-saving shutdown, the starter motor's current draw briefly places a load of up to 1000 A on the 12 V vehicle electrical system. This additional power places such a heavy load on conventional 12 V batteries that the mains voltage drops by several volts. This drop can lead to the failure of other consumers in the vehicle electrical system. To avoid this, the voltage drop must be avoided or reduced. An NTC (Negative Temperature Coefficient) component, for example, can be used to reduce the voltage drop.

[0004] Given the expected dimensions of the NTC component, which have a cross-section of more than 1 cm² and a length of less than 1 mm, a flat contact with low electrical resistance is required. Furthermore, the component is exposed to significant temperature fluctuations during operation, with the thermal expansion coefficient of the ICL ceramic being significantly lower than that of good electrical conductors (e.g., copper). The resulting thermal mechanical stresses can lead to component destruction.

[0005] One problem to be solved is to provide an improved electronic component for inrush current limitation and the use of an improved electronic component.

[0006] This object is achieved by the electronic component according to claim 1 and the use according to claims 17 and 18, respectively.

[0007] According to one aspect, an electronic component, or component for short, is specified. The electronic component is designed to be used in an inrush current limiter or to act as an inrush current limiter. The component has at least one NTC element. The NTC element serves as a functional element or functional layer of the component. The NTC element has an NTC ceramic. The component can have a plurality of NTC elements, for example two, three, five, or ten NTC elements. The NTC element can be disk- or plate-shaped (round). However, the NTC element can also have a rectangular or annular surface.

[0008] A metallization is arranged on the NTC element, preferably on a top side and a bottom side of the NTC element. The metallization preferably comprises silver.

[0009] Alternatively, the metallization can also be copper or gold. The NTC element can be a monolithic component. In this case, the NTC ceramic is manufactured using compression molding technology and then lapped (finely ground on both sides) to the desired shape or thickness (thick-film monolith). Alternatively, the NTC element can also be designed as a multilayer monolith. In this case, ceramic foils are stacked on top of each other and pressed together to create the NTC element.

[0010] The component has at least two electrically conductive contact elements or electrodes. The contact elements are flat. The contact elements are designed and arranged for electrically conductive and thermal connection with the NTC element. The component can have a plurality of contact elements, for example, five, ten, or 15 contact elements, whereby the individual NTC elements must be well thermally coupled.

[0011] The NTC element is electrically connected to the respective contact element via a connecting material. The NTC element is also thermally connected to the respective contact element via the connecting material. The connecting material creates a stable, highly electrically conductive, and mechanically durable connection between the NTC element and the contact elements.

[0012] The thermal expansion coefficient of the respective contact element is adapted to the thermal expansion coefficient of the NTC element. Preferably, the thermal expansion coefficients of the NTC element and the contact elements are approximately the same.

[0013] For example, the NTC element has a thermal expansion coefficient between 7 ppm / K and 10 ppm / K. Preferably, the respective contact element has a corresponding expansion coefficient. The thermal expansion coefficient of the respective contact element is preferably in the range between 5 ppm / K and 10 ppm / K.

[0014] By adjusting the thermal expansion coefficients, the differences in material-induced thermal expansion (CTE) between the NTC element and the contact elements are reduced or adjusted. This reduces or eliminates stresses caused by thermal expansion. This provides a particularly stable, reliable, and durable component.

[0015] According to one embodiment, the NTC element has a top side and a bottom side. The top side and bottom side are opposite each other and are each bounded by the end faces of the NTC element. The top side and bottom side are each at least partially electrically contacted by the respective contact element. Depending on the manufacturing process, a small edge layer or a small edge area of ​​the top side or bottom side may remain uncontacted.

[0016] However, the top and bottom surfaces can also be electrically connected over their entire surface by the respective contact element. In other words, the NTC element is embedded between the two contact elements, so that the top and bottom surfaces are each partially or completely covered by a contact element. This allows for particularly reliable contact between the NTC element and a particularly stable connection between the NTC element and the contact elements.

[0017] According to one embodiment, the contact element comprises a material composite. In other words, the contact element is composed of several materials. The respective contact element preferably comprises copper. Copper is characterized by its very high electrical conductivity and very high thermal conductivity. In addition, the contact element preferably comprises Invar and / or Kovar and / or molybdenum. These materials are characterized by their low thermal expansion coefficients. Preferably, the respective contact element comprises a rolled copper-Invar sheet with a layer structure of copper-Invar-copper. By appropriately selecting the thickness ratio of copper and Invar / Kovar or molybdenum layers of the respective contact element, the expansion coefficient can be adapted to the expansion coefficient of the NTC element. This results in a very stable and durable component.

[0018] According to one embodiment, the contact element has a layer structure of copper - Invar - copper with a thickness ratio of 10% ≤ copper ≤ 30% - 50% ≤ Invar / Kovar / Molybdenum ≤ 80% - 10% ≤ copper ≤ 30%. This means that the contact element has at least three layers. A first layer preferably comprises copper. The first layer has a thickness or vertical extent that is between 1 / 10 and 3 / 10 of the total thickness of the contact element. A second layer preferably comprises Kovar and / or Invar and / or molybdenum. The second layer has a thickness that is between 5 / 10 and 8 / 10 of the total thickness of the contact element. The third layer has a thickness that is between 1 / 10 and 3 / 10 of the total thickness of the contact element.

[0019] The layer of the contact element containing Invar / Kovar / molybdenum is thicker than the layer containing copper. This allows the contact element's coefficient of expansion to be reduced or adapted to the coefficient of expansion of the NTC element.

[0020] The preferred thickness ratio of copper to Invar to copper is 20% - 60% - 20%. Of course, other thickness ratios and layer sequences and numbers of layers, as well as the addition of Kovar or molybdenum, are also conceivable to achieve the desired coefficient of expansion.

[0021] According to one embodiment, the connecting material comprises sintered silver. Sintered silver exhibits high electrical and thermal conductivity. Furthermore, sintered silver can withstand high temperatures of up to 400°C, for example, 300°C, as well as rapid and frequent temperature changes.

[0022] In the operating or hot state of the NTC element, very high temperatures and numerous temperature changes can occur. Therefore, the heat resistance and adaptability of the connecting material are extremely important. The hot state refers to a state at a temperature that is higher than that of the NTC element in its ground state. The temperature range between the ground state and the hot state can, for example, span any temperature range between -55°C and +300°C or extend beyond this range. Preferably, the temperature range between the ground state and the hot state can extend from -40°C to +300°C.

[0023] The bonding material preferably comprises µAg. µAg is particularly characterized by its sufficient porosity.

[0024] According to one embodiment, the NTC element has two, three, five, ten, or more segments. The segments of the NTC element preferably represent rectangular subregions of the NTC element that are spaced apart from one another. The distance between the segments is 0.05 mm to 0.2 mm, for example, 0.1 mm. In other words, there are gaps (expansion joints) between the individual segments. These expansion joints create little or no stress. Additional mechanical stresses can thus be avoided, and consequently, a long-lasting component can be provided.

[0025] According to one embodiment, the NTC element has a nominal resistance R 25 ≤ 1 Ω at a temperature of 25°C (room temperature). Room temperature is understood to be the temperature typically prevailing in occupied rooms. The electrical resistance preferably describes the electrical resistance of the unloaded NTC element between external contacts at an ambient temperature of 25°C.

[0026] For example, at the specified temperature, the NTC element has a nominal resistance R 25 of less than or equal to 0.1 Ω, preferably less than 0.05 Ω. The NTC element therefore has a very low electrical resistance at room temperature or at 25°C and thus a very high electrical conductivity. This makes the NTC element particularly suitable for use in an inrush current limiter with a high current load.

[0027] The low electrical resistance makes it possible, in particular, to ensure that a sufficiently high inrush current is provided to an electrical load, which is connected in series with the electronic component in a corresponding application, for example, but is limited to such an extent that, for example, the electrical voltage during the switch-on process is still sufficiently high to supply electrical power to other important electrical components. With the help of the component, the voltage drop during the load's start-up process is reduced by approximately 1 V compared to a load without the electronic component.

[0028] According to one embodiment, the specific electrical resistance of the NTC element in a ground state of the electronic component is ≤ 2 Ωcm. Preferably, the specific electrical resistance of the NTC element in a ground state of the electronic component is between 0.1 Ωcm and 1.0 Ωcm, for example, 0.3 Ωcm.

[0029] According to one embodiment, the contact element has a thickness d. Preferably, 0.3 mm ≤ d ≤ 0.8 mm applies. Preferably, the thickness d of the respective contact element is less than 0.7 mm, for example, 0.6 mm.

[0030] According to one embodiment, the component comprises a plurality of NTC elements and contact elements. The plurality of NTC elements can be provided by singulation from a substrate. The NTC elements are connected in parallel. The current carrying capacity and / or current-carrying capacity of the component can be increased by connecting several NTC elements in parallel. The NTC elements are preferably arranged in a stacked manner. A contact element is arranged between each two adjacent NTC elements. The NTC elements are thermally well coupled to one another via the contact elements.

[0031] According to one embodiment, the NTC element has the composition La (1-x) EA (x) Mn (1-abc) Fe (a) Co (b) Ni (c) O (3±δ). Where 0 ≤ x ≤ 0.5 and 0 ≤ (a+b+c) ≤ 0.5. EA denotes an alkaline earth element. The alkaline earth element is preferably selected from magnesium, calcium, strontium, or barium. δ denotes the deviation from the stoichiometric oxygen ratio (oxygen excess or oxygen deficit). Preferably, |δ| ≤ 0.5. Particularly preferably, |δ| = 0.

[0032] This composition provides an NTC element characterized by exceptionally high electrical conductivity and a sufficient B value (thermistor constant). The resistance can be further varied and controlled by (a) specific thickness and (a) specific cross-section or area of ​​the NTC element. The NTC element has a thickness d. Preferably, 100 µm ≤ d ≤ 600 µm applies. The thickness d of the NTC element is preferably less than 500 µm, for example 400 µm. The B value B 25 / 100 is in the range between 1000 K and 4000 K, preferably between 1400 K and 2000 K, for example 1500 K.

[0033] According to one embodiment, the component comprises a fastening element. The fastening element is preferably designed and arranged to establish an electrically conductive connection with battery lines. The fastening element is further preferably designed and arranged to establish a mechanical connection with battery lines. The fastening element is further preferably designed and arranged to provide an indirect mechanical connection between the contact elements.

[0034] The fastening element can be designed to form a screw connection. However, the fastening element can also be designed, for example, to form a clamp connection. The fastening element can further comprise a sealing element. The sealing element can be insulating or partially insulating. The fastening element can comprise at least one nut and one screw and / or at least one clamping element, for example, two clamping elements.

[0035] The fastener exhibits an electrical resistance. This electrical resistance is equal to or only slightly higher than the resistance of the NTC element at low operating temperatures. In particular, the electrical resistance of the fastener is equal to or only slightly higher than the resistance of the NTC element at the lowest operating temperature, e.g., -40°C.

[0036] The resistance of the fastening element is not temperature-dependent. This means that even in the event of a fault (e.g., a break in the conductive connection between the NTC element and the contact element), the engine can still be started (depending on the design of the starter system). Voltage drops are also avoided, but the electrical power available for starting is severely limited, which may significantly delay the starting process. In addition to a screw connection, a fixed resistor or another conductive element with a defined electrical resistance can also be used as a fastening element.

[0037] According to a further aspect, the use of an electronic component is described. Preferably, the use of the component described above is specified. All features explained in connection with the component also apply to the use, and vice versa.

[0038] In particular, the use of the component described above for start / stop systems in the automotive sector is specified. The temperature-dependent resistor (NTC element) limits the inrush current during switch-on. Upon switch-on, the NTC element immediately heats up due to the inrush current (e.g., to 250°C), causing the NTC resistance to quickly decrease to a very small residual resistance (e.g., 0.5 mΩ). Due to the specific properties of the NTC element, this dynamic change in resistance reduces the current peak caused by the starter motor, which simultaneously reduces the voltage drop in the battery. This provides an effective component for limiting the inrush current in start / stop systems.

[0039] The contact elements and connecting material provided further enable a very low-resistance electrical connection between the NTC element and the contact elements for repeated switching cycles, where the ambient temperature can fluctuate from -40°C to 120°C. During the switching cycle, the temperature can rise to as much as 300°C. This provides a stable, highly electrically conductive component with a mechanically durable, temperature-resistant, and extremely resilient connection between the NTC element and the contact elements for use in start / stop systems in the automotive sector.

[0040] According to a further aspect, the use of an electronic component, in particular the electronic component described above, for currents up to 1000 A at direct voltage in 12 V and 24 V networks is specified.

[0041] Beneficial aspects are described below. To facilitate referencing, the aspects are numbered consecutively. Aspect features are relevant not only in combination with the specific aspect to which they refer, but also when considered individually. 1. An electronic component for inrush current limiting, comprising at least one NTC element and at least two electrically conductive contact elements, wherein the NTC element is electrically conductively connected to the respective contact element via a connecting material, and wherein the thermal expansion coefficient of the respective contact element is adapted to the thermal expansion coefficient of the NTC element. 2. An electronic component according to aspect 1, wherein the NTC element has a top side and a bottom side, and wherein the top side and the bottom side are at least partially electrically conductively contacted by the respective contact element. 3. An electronic component according to aspect 1 or 2, wherein the contact element comprises a material composite. 4. An electronic component according to one of the preceding aspects, wherein the contact element comprises copper, and wherein the contact element comprises Invar or Kovar. 5.Electronic component according to one of the preceding aspects, wherein the contact element has a layer structure of copper - Invar - copper with a thickness ratio of 10% ≤ copper ≤ 30% - 50% ≤ Invar / Kovar ≤ 80% - 10% ≤ copper ≤ 30%. 6. Electronic component according to one of the preceding aspects, wherein the connecting material comprises sintered silver. 7. Electronic component according to one of the preceding aspects, wherein the NTC element has two, three or more segments. 8. Electronic component according to one of the preceding aspects, wherein the NTC element has a nominal resistance R 25 ≤ 1 Ω at a temperature of 25°C. 9. Electronic component according to one of the preceding aspects, wherein the specific electrical resistance of the NTC element in a ground state of the electronic component is ≤ 2 Ωcm. 10. Electronic component according to one of the preceding aspects, wherein the contact element has a thickness d, and wherein 0.3 mm ≤ d ≤ 0.8 mm.11. The electronic component according to one of the preceding aspects, wherein the NTC element has a thickness d, and wherein 100 µm ≤ d ≤ 600 µm. 12. The electronic component according to one of the preceding aspects, comprising a plurality of NTC elements and contact elements, wherein the NTC elements are connected in parallel to one another. 13. The electronic component according to aspect 12, wherein the NTC elements are arranged one above the other in a stack, wherein a contact element is arranged between each two adjacent NTC elements, and wherein the NTC elements are thermally coupled to one another via the contact elements. 14.Electronic component according to one of the preceding aspects, wherein the NTC element has the composition La (1-x) EA (x) Mn (1-abc) Fe (a) Co (b) Ni (c) O (3±δ), where 0 ≤ x ≤ 0.5 and 0 ≤ (a+b+c) ≤ 0.5 and where EA denotes an alkaline earth element and δ denotes a deviation from a stoichiometric oxygen ratio, where the alkaline earth element (EA) is selected from magnesium, calcium, strontium or barium and / or where |δ| ≤ 0.5. 15. Electronic component according to one of the preceding aspects, wherein the NTC element has a thermal expansion coefficient between 7 ppm / K and 10 ppm / K. 16. An electronic component according to any one of the preceding aspects, comprising a fastening element, wherein the fastening element has an electrical resistance that is equal to or only slightly higher than the resistance of the NTC element at low operating temperatures. 17.Use of an electronic component according to one of aspects 1 to 16 for start / stop systems in the automotive sector. 18. Use of an electronic component according to one of aspects 1 to 16 for currents up to 1000 A at direct voltage in 12 V and 24 V networks.

[0042] The invention is explained in more detail below with reference to exemplary embodiments and the associated figures.

[0043] The drawings described below are not to be considered to scale. Rather, individual dimensions may be enlarged, reduced, or distorted for clarity.

[0044] Elements that are identical or that perform the same function are designated by the same reference symbols. Figure 1 shows a schematic sectional view of an electronic component. Figure 2 shows a perspective view of a possible contacting of the electronic component according toFigure 1 , Figure 3 shows a perspective view of an electronic component according to a further embodiment, Figure 4 shows a schematic sectional view of an electronic component according to a further embodiment, Figure 5 shows a perspective view of a possible contacting of the electronic component according to Figure 4 , Figure 6 shows a schematic sectional view of an electronic component according to a further embodiment, Figure 7 shows a perspective view of an electronic component according to a further embodiment, Figure 8 shows a schematic sectional view of an electronic component according to a further embodiment, Figure 9 shows a plan view of a partial area of ​​the electronic component according to Figure 8, Figure 10 shows a schematic sectional view of an electronic component according to a further embodiment, Figure 11 shows a plan view of a partial area of ​​the electronic component according to Figure 10 , Figure 12 shows a schematic sectional view of an electronic component according to a further embodiment, Figure 13 shows a plan view of a partial area of ​​the electronic component according to Figure 12 .

[0045] The Figure 1 shows an electronic component 1, or component 1 for short. Component 1 is designed to be used as an inrush current limiter or in an inrush current limiter for start / stop systems in 12 V and 24 V networks in the automotive sector. Component 1 is particularly suitable for use with currents up to 1000 A (at direct voltage in 12 V and 24 V networks). Component 1 is suitable for use in typical 12 V starter motors with approximately 1 kW to 3 kW of power.

[0046] Component 1 comprises an NTC element 2 or an NTC ceramic. NTC element 2 represents a functional layer or a functional element of component 1. NTC element 2 is a thermally conductive component with a negative temperature coefficient.

[0047] The NTC element 2 has a material composition which is characterized by high electrical conductivity and low specific resistance.

[0048] The NTC element 2 preferably has the following composition: La (1-x) EA (x) Mn (1-abc) Fe (a) Co (b) Ni (c) O (3±δ) . Here, 0 ≤ x ≤ 0.5 and 0 ≤ (a+b+c) ≤ 0.5. EA stands for an alkaline earth element, for example Mg, Ca, Sr or Ba. δ denotes the deviation from the stoichiometric oxygen ratio (oxygen excess or oxygen deficit). Preferably, |δ| ≤ 0.5, particularly preferably |δ| = 0. For example, the NTC ceramic has the composition La 0.95 Sr 0.05 MnO 3 .

[0049] The specific electrical resistance of the NTC element 2 in a ground state of the NTC element 2 is less than or equal to 2 Ωcm, preferably ≤ 1 Ωcm, for example, 0.5 Ωcm. The ground state describes a temperature of the NTC element 2 of 25°C or at room temperature. The ground state can be an unloaded state in which, for example, no electrical power is applied to the NTC element 2.

[0050] At the specified temperature, the NTC element 2 has an electrical resistance (nominal resistance R 25 ) of less than or equal to 1 Ω, preferably less than 0.1 Ω, for example, 0.05 Ω. The NTC element 2 therefore has a low electrical resistance at room temperature or at 25°C and thus a high electrical conductivity. This makes the NTC element 2 particularly suitable for use in an inrush current limiter.

[0051] NTC element 2 also has a high B value. The B value B 25 / 100 is in the range between 1000 K and 4000 K, preferably between 1400 K and 2000 K, for example, 1500 K. NTC element 2 has a low thermal expansion coefficient. Typically, the thermal expansion coefficient of NTC element 2 is between 7 ppm / K and 10 ppm / K.

[0052] The NTC element 2 is preferably designed as a monolithic component. For example, the NTC element 2 is a thick-film monolith. In this case, the NTC element 2 is manufactured using compression molding technology and then lapped (finely ground on both sides) to the desired thickness. Alternatively, the NTC element 2 can also be designed as a multilayer monolith. In this case, ceramic foils are stacked on top of each other and pressed to create the NTC element 2.

[0053] The Figure 2The NTC element 2 shown has a round shape. The NTC element 2 is disc-shaped or plate-shaped. However, other shapes are also conceivable for the NTC element 2, for example a rectangular shape or a ring shape. The NTC element 2 can be in the form of a substrate. The NTC element 2 has an area between 25 mm 2< and 500 mm 2< , for example 200 mm 2<. The diameter of the NTC element 2 is, for example, less than or equal to 14 mm, e.g. 13.75 mm. The NTC element 2 has a thickness d between 100 µm and 600 µm, for example 400 µm. By varying the thickness d and / or cross-section or area of ​​the NTC element 2, the resistance of the NTC element 2 can be varied and controlled.

[0054] The NTC element 2 has a metallization (not explicitly shown). The metallization is preferably arranged on a top side and a bottom side of the NTC element 2. The metallization preferably comprises baked-on silver.

[0055] The component 1 further comprises two contacts 3 or contact elements 3 (plus contact and minus contact element 12b, 12a, see Figure 3 ). The contact elements 3 serve to make electrical contact with the NTC element 2. In this exemplary embodiment, the contact elements 3 lie fully on the top and bottom of the NTC element 2. Alternatively (not explicitly shown), a narrow edge area of ​​the top and bottom can also remain free of the respective contact element 3.

[0056] The contact elements 3 are each electrically connected to the top and bottom of the NTC element 2. Preferably, the NTC element 2 and the contact elements 3 are sintered.

[0057] For this purpose, the component 1 comprises a connecting material 7. A layer of connecting material 7 is formed between the top side of the NTC element 2 and the first contact element 3, as well as between the bottom side of the NTC element 2 and the second contact element 7. The layer thickness of the connecting material 7 is preferably in the range between 15 µm and 80 µm, for example, 20 µm.

[0058] The connecting material 7 is characterized by high electrical and thermal conductivity. The connecting material 7 is further preferably characterized by high porosity. The connecting material 7 is further characterized by its ability to withstand high temperatures of up to 400°C, e.g., 300°C, as well as the numerous and rapid temperature changes that can occur during operation or when the component 1 is hot.

[0059] The hot state refers to a state of the component 1 at a temperature that is greater than that of the component 1 in the ground state. The temperature range between the ground state and the hot state can, for example, span any temperature range between -55°C and +300°C or extend beyond this range. Preferably, the temperature range between the ground state and the hot state can extend beyond the range from -40°C to +300°C.

[0060] For example, the connecting material 7 comprises sintered silver Ag or µAg. Sintered silver has the advantage of having sufficient porosity. The connecting material 7 creates a stable, highly electrically conductive, and mechanically durable connection between the NTC element 2 and the contact elements 3.

[0061] The respective contact element 3 has high thermal and electrical conductivity. The respective contact element 3 is further configured to reduce thermal stresses between the NTC element 2 and the contact element 3. In particular, the respective contact element 3 is configured to reduce or minimize differences in material-related thermal expansion (CTE).

[0062] The respective contact element 3 preferably comprises a material composite. The respective contact element can, for example, be designed as a composite sheet. The material composite can comprise copper-Invar-copper (CIC). Kovar or molybdenum can also be used instead of Invar. Invar, Kovar, or molybdenum has a low thermal expansion coefficient. Typically, the thermal expansion coefficient of these materials is ≤ 10 ppm / K, for example, 7 ppm / K. Thus, the expansion coefficient of Kovar / Invar / molybdenum is very similar to the expansion coefficient of the NTC element 2. By appropriately selecting the thickness ratio of the layers of the material composite, the expansion coefficient of the contact element 3 can be closely matched to the expansion coefficient of the NTC element 2. Thermal stresses can be reduced or avoided.

[0063] In this embodiment, the respective contact element 3 is a rolled copper-Invar sheet with a layer structure of copper-Invar-copper of 20%-60%-20%. However, other ratios of copper to Invar or Kovar to molybdenum are also conceivable. In particular, depending on the required area of ​​the NTC element 2 and the required thermal resistance, other layer sequences and layer thicknesses can also be used.

[0064] The contact elements 3 enclose the NTC element 2 in a pincer-like manner. A first partial region 3a of the respective contact element 3 rests on the top or bottom of the NTC element 2 and runs parallel to the top or bottom of the NTC element 2 or to a longitudinal axis L of the component 1. A length or horizontal extent of the NTC element 2 is preferably less than or equal to the length or horizontal extent of the first partial region 3a.

[0065] A second partial region 3b of the respective contact element 3 encloses an angle with the longitudinal axis L. The second partial region 3b preferably adjoins the first partial region 3a at an angle of ≤ 20°, for example 15°, to the longitudinal axis L of the component 1. The angle between the second partial region 3b of the first contact element 3 and the second partial region 3b of the second contact element is preferably less than or equal to 40°, for example 30°. A third partial region 3c of the respective contact element 3 adjoins the second partial region 3b and runs parallel to the longitudinal axis L.

[0066] In this exemplary embodiment, the respective subregions 3a, 3b, 3c preferably have the same length. For example, the subregions 3a, 3b, 3c each have a length of 10 mm to 15 mm. The respective subregions 3a, 3b, 3c preferably have the same thickness d. For example, the subregions 3a, 3b, 3c each have a thickness d of less than or equal to 0.8 mm and greater than or equal to 0.3 mm. Consequently, the thickness d of the respective contact element 3 amounts to 0.3 mm ≤ d ≤ 0.8 mm, for example d = 0.7 mm.

[0067] The sub-areas 3a, 3b, and 3c merge into one another. In other words, the sub-areas 3a, 3b, and 3c are not designed as separate areas or components, but rather represent subsections of the respective contact element 3.

[0068] The respective contact element 3, in particular the third partial area 3c, has a recess 8. Preferably, the third partial area 3c has a larger horizontal extent or a larger area than the first and second partial areas 3a, 3b (see, for example, Figure 3 ). The recess 8 is preferably circular. The recess 8 has, for example, a diameter of 8 mm. The recess 8 completely penetrates the contact element 3. The recess 8 serves to connect the component 1 to battery leads by means of a fastening element, for example in connection with Figure 2 is explained in more detail.

[0069] The Figure 2 shows a possible contacting of the component 1 according to the Figure 1 with the battery cables via cable lugs.

[0070] The component 1 has a fastening element for establishing electrical contact with the component 1 and, in particular, for mechanically fastening battery leads to the component 1. The fastening element can be designed to provide a screw connection as described below. Alternatively, the fastening element can also be designed and arranged to establish a clamp connection.

[0071] A spacer 9 is arranged between the first and second contact elements 3. The spacer 9 is arranged between a bottom side of the third partial area 3c of the first or upper contact element 3 and the top side of the third partial area 3c of the second or lower contact element 3. The spacer 9 is cylindrical.

[0072] The spacer 9 is designed to be insulating. The spacer 9 serves to provide electrical insulation between the two contact elements 3 (positive contact element 12b and negative contact element 12a, see Figure 3 ). The spacer 9 comprises, for example, polytetrafluoroethylene (PTFE). PTFE has the advantage of being consistently insulating up to a temperature of approximately 250°C. Preferably, the spacer 9 has a recess (not explicitly shown) that completely penetrates the spacer 9 in the vertical direction. The recess serves to accommodate a connecting element, e.g., a threaded rod 11, for example, a screw.

[0073] A nut 10 is arranged on the top side of the first contact element 3 and the bottom side of the second contact element 3, respectively. Threaded rod 11 and nuts 10 serve to screw the contact elements 3 and to electrically and mechanically connect the component 1 to the battery lines (not explicitly shown). Alternatively, clamping elements, for example, can be provided for clamping the contact elements 3 and / or for electrically and mechanically connecting the component 1 to the battery lines (not explicitly shown).

[0074] Cable lugs 5, to which a copper cable (not shown) is attached, are arranged between the battery cables (not shown) and the contact elements 3. The cable lugs 5 are electrically connected to the contact elements 3. To connect the component 1 to the cable lugs 5, the threaded rod 11 is guided through the nuts 10, the recess 8 in the respective contact element 3, and the recess in the spacer 9.

[0075] The screw connection on an axis avoids additional mechanical stress on the connection between the NTC element 2 and the contact elements 3. The screw connection or fastening must either have a higher resistance than the NTC element 2 or must be designed to be insulating (see for example Figures 12 and 13 ). Alternatively, the screw connection or fastening can also be made directly to a ground contact on the vehicle or the starter motor.

[0076] The temperature-dependent resistance of component 1 limits the inrush current during power-on. Upon power-on, NTC element 2 immediately heats up due to the inrush current (e.g., to 250°C), causing the NTC resistance to rapidly decrease to a very small residual resistance (e.g., 0.5 mΩ). This dynamic resistance change reduces the current peak caused by the starter motor, which simultaneously reduces the voltage drop in the battery. This provides a stable, durable, and efficient component for inrush current limitation.

[0077] Component 1 can also be equipped with a so-called "fail-safe" function. For this purpose, the Figure 2The screw connection shown is designed so that its electrical resistance is equal to or only slightly higher than the resistance of NTC element 2 at the lowest operating temperature, e.g., -40°C. The resistance of this screw connection is not temperature-dependent. This means that even in the event of a fault (e.g., a break in the conductive connection between NTC element 2 and contact element 3), the engine can still be started (depending on the design of the starter system). The voltage drop is also avoided, but the electrical power available for starting is severely limited, which may significantly delay the starting process.

[0078] For example, the specific electrical resistance of NTC element 2 at 25°C is: R spec,25 = 0.2 Ωcm. The nominal resistance R 25 of NTC element 2 at a temperature of 25°C is, for example, R 25 = 10 mΩ. The B value is, for example, 1650 K. This results in a specific electrical resistance of NTC element 2 at a temperature of -40°C of CR spec,-40 = 0.65 Ωcm and a resistance of NTC element 2 of 32 mΩ, resulting in an electrical resistance of the screw connection of preferably 32 to 35 mΩ.

[0079] As an alternative to a screw connection, a fixed resistor or another conductive element with a defined electrical resistance can be used.

[0080] The Figure 3 shows a perspective view of an electronic component according to a further embodiment. In contrast to the component 1 from Figure 1 Component 1 has according to Figure 3several NTC elements 2 and several contact elements 3.

[0081] The component 1 can have up to ten NTC elements 2. The NTC elements 2 are each round or disc-shaped (see explanations on Figure 1 ). The NTC elements 2 are electrically connected in parallel.

[0082] Contact elements 3 are arranged between NTC elements 2. Component 1 preferably has a layer sequence of alternating NTC elements 2 and contact elements 3 (positive contact elements 12b and negative contact elements 12a). The flat, "stacked" sequence of contact element 3 / NTC element 2 / contact element 3 / NTC element 2, etc., achieves a good thermal connection between the individual NTC elements 2. This good thermal connection enables uniform heating of NTC elements 2.

[0083] The diameter of the NTC elements 2 can be smaller than the diameter of the Figure 1NTC element 2 shown. This means that several smaller elements are connected. The stresses decrease with the component size of NTC element 2.

[0084] The fastening to, preferably the screw connection to, the battery terminals is preferably carried out on a common insulating body (for example a spacer 9) in order to avoid additional mechanical stresses on the connection between the NTC elements 2 and the contact elements 3.

[0085] All other features of component 1 according to the Figure 3 , in particular the material, structure and functioning of NTC elements 2 and contact elements 3 as well as their connection via the connecting material 7 and the functioning of the component 1 correspond to the Figure 1 described characteristics.

[0086] The Figure 4shows a schematic sectional view of an electronic component according to a further embodiment.

[0087] In the following, only the differences to component 1 from Figure 1 In particular, the features relating to the design of the NTC element 2 and the connection of NTC element 2 and contact elements 3 are Figure 1 also for component 1 from Figure 4 Application.

[0088] In this embodiment, the contact elements 3 are double-sided. Here, too, each contact element 3 has three sub-areas 3a, 3b, and 3c, with the second sub-area 3b and the third sub-area 3c being similar but oriented in the opposite direction to the first sub-area 3a.

[0089] The first partial region 3a rests on the top or bottom of the NTC element 2 and runs parallel to the top or bottom of the NTC element 2 or to the longitudinal axis L. The length or horizontal extent of the NTC element 2 is less than or equal to the length or horizontal extent of the first partial region 3a. Preferably, the length of the first partial region 3a in this embodiment is greater than the length of the first partial region 3a according to the Figure 1 shown embodiment. The length of the first partial region 3a is, for example, 18 mm. The diameter of the NTC element 2 is, for example, less than or equal to 14 mm, e.g., 13.75 mm.

[0090] The second and third subregions 3b, 3c each adjoin a side region or edge region of the first subregion 3a. In other words, the second subregion 3b and the third subregion 3c are formed to the left and right of the first subregion 3a, respectively.

[0091] The second partial region 3b and the third partial region 3c each enclose an angle with the longitudinal axis L. The second and third partial regions 3b, 3c preferably each enclose an angle of ≤ 90°, for example 60°, with the longitudinal axis L. Both the second partial region 3a and the third partial region 3c extend away from the longitudinal axis L. A vertical distance from an end region 13 of the third partial region 3c or the second partial region 3b to the NTC element 2 is, for example, less than or equal to 18 mm, for example 15 mm.

[0092] The component 1 is designed to be mirror-symmetrical about the axis L. The respective contact element 3 is also designed to be mirror-symmetrical about a vertical axis V.

[0093] The design described above allows, for example, the electrical and thermal resistance of the contact elements 3 to be halved while using the same contact material. A further advantage of this design is the avoidance of different temperatures in the NTC element 2 by "one-sided" heat dissipation via the contact elements 3, as in the design according to Figure 1 .

[0094] All other features of component 1 according to the Figure 4 correspond to those related to the Figure 1 described characteristics.

[0095] The Figure 5 shows a perspective view of a possible contacting of the electronic component according to Figure 4 .

[0096] The component 1 is placed in a housing 6. The housing 6 is frame-shaped. The component 1 is contacted (screwed, clamped, or similar) through the housing 6 by means of an insulated, flexible copper cable (not explicitly shown). The contacting is carried out as in connection with the Figure 2 described via the nuts 10, the threaded rod 11, which is inserted into the recess 8 of the respective contact element 3, and the electrically conductive connection of the contact elements 3 with cable lugs into which the copper cables are inserted. The copper cables are inserted into the housing 6 via recesses 6a on a top and bottom side of the housing 6.

[0097] The housing 6 has a mechanical strain relief 4 for the copper cables. The strain relief 4 can be arranged, for example, on a top side and a bottom side 4 of the housing 6. When mechanical tension is applied to the copper cables, the strain relief 4 ensures that no or only minimal forces act on the component 1 and, in particular, the connecting material 7. The component 1 is therefore preferably held stress-free by the strain relief 4.

[0098] The Figure 6 shows a schematic sectional view of an electronic component according to a further embodiment.

[0099] Essentially, component 1 corresponds to component 1 from Figure 4 However, in this embodiment, the contact elements 3 are not arranged mirror-symmetrically to the longitudinal axis L. Rather, the contact elements 3 are offset from each other by 90°. This allows for different installation situations to be accommodated.

[0100] All other features of component 1 according to the Figure 6 correspond to those related to the Figure 4 described characteristics.

[0101] The Figure 7 shows a perspective view of an electronic component according to a further embodiment.

[0102] Essentially, component 1 corresponds to component 1 from Figure 6 However, the component 1 according to Figure 7 several NTC elements 2 and several contact elements 3. The component 1 can have up to ten NTC elements 2, each of which is round or disc-shaped and electrically connected in parallel. The contact elements 3 are arranged between the NTC elements 2. The component 1 thus has, as already described in connection with the Figure 3 described a layer sequence of alternatingly arranged NTC elements 2 and contact elements 3.

[0103] The Figure 8shows a schematic sectional view of an electronic component according to a further embodiment. Figure 9 further shows a plan view of a portion of the electronic component according to Figure 8 .

[0104] In contrast to the embodiment according to the Figure 1 An NTC element 2 is used, which has been divided or segmented into smaller NTC elements or segments 2a by sawing or scoring. The NTC element 2 has a plurality of segments 2a.

[0105] To form the segments 2a, the NTC element 2 has, unlike in Figure 1 preferably a rectangular shape. For example, the NTC element 2 has a width and a height of less than or equal to 13 mm, for example 12.7 mm. The respective segment 2a is also preferably rectangular. Preferably, the respective segment 2a has a length and a width of approximately 2 mm each.

[0106] The contact elements 3 should also be rectangular for this design. Thus, the respective contact element is Figures 8 and 9 formed from three rectangular sub-areas 3a, 3b, 3c. The three sub-areas preferably have the same length, for example 15 mm.

[0107] Between the individual segments 2a, gaps or expansion joints 15 are formed (see Figure 9 ). The expansion joints 15 have a width of 0.05 mm to 0.2 mm, for example, 0.1 mm. These expansion joints 15 reduce thermal stresses in the NTC element 2 during normal operation.

[0108] For the production of this variant, ceramic multilayer technology is suitable, in which an NTC substrate made of stacked ceramic foils is segmented by so-called "dicing" before or after metallization. All other features correspond to those associated with the Figure 1 described characteristics.

[0109] The Figure 10 shows a schematic sectional view of an electronic component according to a further embodiment. Figure 11 shows a plan view of a portion of the electronic component according to the Figure 10 .

[0110] This embodiment combines features of the embodiments according to the Figures 4 and 8 and 9. In particular, the contact elements 3 - as in connection with the Figure 4 - described double-sided. The NTC element 2 is - as described in connection with the Figures 8 and 9described - separated into individual segments 2a. All other characteristics correspond to those described in connection with the Figures 4 , 8 and 9 described characteristics.

[0111] The Figure 12 shows a schematic sectional view of an electronic component according to a further embodiment. Figure 13 shows a perspective view of a portion of the electronic component according to Figure 12 .

[0112] In this embodiment, the contact elements 3 are as in connection with Figure 4 As described, it is double-sided. The NTC element 2 is arranged between the first partial region 3a of the contact elements 3 and is electrically and thermally connected to the contact elements 3 via the connecting material 7.

[0113] In this embodiment, the screw connection is in contrast to the screw connection according to Figure 2Insulating. For this purpose, the NTC element 2 is designed in a ring shape. In other words, the NTC element 2 has a round, continuous recess. The first partial area 3a of the respective contact element 3 also has a recess in this embodiment. The recesses of contact elements 3 and NTC element 2 are designed and arranged to enable the insulating screw connection of the contact elements 3. In particular, the recesses are provided for the introduction of a threaded rod 11 for screwing the contact elements 3.

[0114] On an outer surface of the first partial area 3a, a spacer 9 is arranged, which has a recess 9a ( Figure 13). The respective spacer is, for example, a PTFE disk. The respective spacer has, for example, a diameter of 15 mm. A spacer 9 is arranged on an upper side of the first partial area 3a of the first or upper contact element 3. Another spacer 9 is arranged on an underside of the first partial area 3a of the second or lower contact element 3. A nut 10 is arranged on each of the spacers 9. The threaded rod 11 is guided through the nuts 10, the recesses in the spacers 9, the NTC element 2 and the contact elements 3 for screwing the contact elements 3. An insulating element 14 is introduced into the recess of the NTC element 2 between the threaded rod 11 and the NTC element 2. The insulating element 14 can, for example, comprise AlO x. For example, the insulating element 14 is an AlO x tube.This enables an insulating screw connection of component 1.

[0115] The electrical contacting of component 1 is again carried out as in connection with the Figure 2 described via the electrically conductive connection of the contact elements 3 with the battery cables via the cable lugs 5. The cable lugs are screwed to the contact elements 3 via the recesses 8 of the contact elements 3.

[0116] The invention is not limited by the description based on the exemplary embodiments. Rather, the invention encompasses any novel feature and any combination of features, including in particular any combination of features in the patent claims, even if this feature or combination itself is not explicitly stated in the patent claims or exemplary embodiments. List of reference symbols

[0117] 1Electronic component 2NTC element / NTC ceramic 2aSegment 3Contact / contact element 3aFirst section 3bSecond section 3cThird section 4Strain relief 5Cable lug 6Housing 6aRecess 7Connecting material 8Recess 9Spacer 9aRecess 10Nut 11Threaded rod 12aMinus contact element 12bPlus contact element 13End section 14Insulating element 15Expansion joint LLongitudinal axis VVertical axis

Claims

1. Electronic component (1) for inrush current limiting comprising - at least one NTC element (2), - at least two electrically conductive contact elements (3), wherein the NTC element (2) is electrically conductively connected to the respective contact element (3) via a connecting material (7) and wherein the thermal expansion coefficient of the respective contact element (3) is adapted to the thermal expansion coefficient of the NTC element (2), wherein the contact element (3) comprises copper and wherein the contact element (3) comprises Invar or Kovar.

2. Electronic component (1) according to claim 1, wherein the NTC element (2) has a top side and a bottom side, and wherein the top side and the bottom side are at least partially electrically conductively contacted by the respective contact element (3).

3. Electronic component (1) according to claim 1 or 2, wherein the contact element (3) comprises a material composite.

4. Electronic component (1) according to one of the preceding claims, wherein the contact element (3) has a layer structure of copper - Invar - copper with a thickness ratio of 10% ≤ copper ≤ 30% -50% ≤ Invar / Kovar ≤ 80% - 10% ≤ copper ≤ 30%.

5. Electronic component (1) according to one of the preceding claims, wherein the connecting material (7) comprises sintered silver.

6. Electronic component (1) according to one of the preceding claims, wherein the NTC element (2) has two, three or more segments (2a).

7. Electronic component (1) according to one of the preceding claims, wherein the NTC element (2) has a nominal resistance R at a temperature of 25°C 25 ≤ 1 Ω.

8. Electronic component (1) according to one of the preceding claims, wherein the specific electrical resistance of the NTC element (2) in a ground state of the electronic component (1) is ≤ 2 Ωcm.

9. Electronic component (1) according to one of the preceding claims, wherein the contact element (3) has a thickness d, and wherein 0.3 mm ≤ d ≤ 0.8 mm.

10. Electronic component (1) according to one of the preceding claims, wherein the NTC element (2) has a thickness d, and wherein 100 µm ≤ d ≤ 600 µm.

11. Electronic component (1) according to one of the preceding claims, comprising a plurality of NTC elements (2) and contact elements (3), wherein the NTC elements (2) are connected in parallel to one another.

12. Electronic component (1) according to claim 11, wherein the NTC elements (2) are arranged one above the other in a stack, wherein a contact element (3) is arranged between each two adjacent NTC elements (2), and wherein the NTC elements (2) are thermally coupled to one another via the contact elements (3).

13. Electronic component (1) according to one of the preceding claims, wherein the NTC element (2) has the composition La (1-x) EA (x) Mn (1-a-b-c) Fe (a) Co (b) No (c) O (3±δ) where 0 ≤ x ≤ 0.5 and 0 ≤ (a+b+c) ≤ 0.5 and where EA denotes an alkaline earth element and δ denotes a deviation from a stoichiometric oxygen ratio, where the alkaline earth element (EA) is selected from magnesium, calcium, strontium or barium and / or where |δ| ≤ 0.

5.

14. Electronic component (1) according to one of the preceding claims, wherein the NTC element (2) has a thermal expansion coefficient between 7 ppm / K and 10 ppm / K.

15. Electronic component (1) according to one of the preceding claims, comprising a fastening element (10, 11), wherein the fastening element (10, 11) has an electrical resistance which is equal to or only slightly higher than the resistance of the NTC element (2) at low operating temperatures.

16. Use of an electronic component (1) according to one of claims 1 to 15 for start / stop systems in the automotive sector.

17. Use of an electronic component (1) according to one of claims 1 to 15 for currents up to 1000 A at direct voltage in 12 V and 24 V networks.

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