Resistor and method for determining the temperature of a resistor - Patents.com

Abstract

The present invention relates to a resistor (2) having at least one connection element (3, 3') and at least one resistive element (4), wherein at least a portion (411) of the surface (41) of the resistive element (4) as a substrate or at least a portion (311) of the surface (31) of the connection element (3, 3') as a substrate is coated with a coating (5) having at least one layer (50, 51, 52, 53). According to the present invention, the coating (5) is implemented in such a way that at an interface (61) between the substrate and the coating (5) there is direct metal-semiconductor contact, thereby forming a pn junction at the interface (61), and / or at least at an interface (62) between a first layer (50, 51) and a second layer (52) of the coating (5) there is direct metal-semiconductor contact or a first semiconductor-second semiconductor contact, thereby forming a pn junction at the interface (62). The resistor 2 is configured such that either one layer (50, 51, 52, 53) of the coating (5) on the one hand, or the uncoated portion (412, 412') of the surface (41) of the resistive element (4) on the other hand or the uncoated portion (312) of the surface (31) of the connecting element (3, 3') on the other hand, or either the first layer (50, 51) of the coating (5) on the one hand, or the further layer (52, 53) on the other hand, is contactable to detect a measurement signal for determining the temperature of the resistor (2).

Description

[Technical Field]

[0001] The present invention relates to a resistor with a coating for measuring the temperature of the resistor, as well as a method for determining the temperature of the resistor. [Background technology]

[0002] Current measurements in electronic circuits use a measuring resistor connected in series with the component to be monitored. The current value is determined from the voltage drop across the measuring resistor, known as a shunt resistor, according to Ohm's law. The resistor's value is assumed to be known. Accurate and reliable current measurement is particularly important, for example, in battery management systems for electric or hybrid vehicles. Resistors with low ohmic values ​​of approximately 10-50 μOhm, as well as connecting elements for connecting the resistor to a current circuit, can be manufactured from a longitudinally welded composite material. This is known, for example, from Patent Document 1. This composite material is manufactured from three metal strips, each of which is connected to each other by a longitudinal joint using an electron beam or laser welding method. The central metal strip is made of a metal with a very low temperature coefficient of resistance. This material forms the actual resistive element of the measuring resistor. The two outer strips are typically made of a highly conductive material, such as copper. Such materials often have a higher temperature coefficient of resistance than the material of the resistive element. These two outer strips form connection elements via which the measuring resistor can be connected to the current circuit.

[0003] Determining the current value from the voltage drop across a measuring resistor requires accurate knowledge of the resistance value. The effect of temperature on the resistivity of the material used plays a key role here. Therefore, to be able to perform a correction for the temperature-dependent resistance behavior, the resistor's temperature, which can range from -40 to +170 °C during operation, must be known. The resistor's temperature can be measured by a temperature sensor, and this information can be used to correct the resistance value. This is known, for example, from Patent Documents 2 and 3. Resistor temperature determination is typically performed either by passive analog sensors, such as NTCs, PT100 temperature probes, or thermocouples, or by active sensors (ICs) with sensor data evaluation and a communication interface. The temperature sensor is an additional component that increases costs and design effort. Furthermore, temperature sensors react to temperature changes with a time delay, which can negatively affect accuracy. This is particularly important when detecting heat generation during short-term peak currents, such as those that occur during extreme acceleration in electric vehicles. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] European Patent Application Publication No. 0605800 [Patent Document 2] DE 19906276 [Patent Document 3] European Patent No. 2793034 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention is based on the problem of providing a resistor that overcomes the above-mentioned drawbacks. In particular, the temperature measurement must react quickly to changes in the resistor temperature. Furthermore, the present invention is based on the problem of providing a method for measuring the temperature of a resistor. [Means for solving the problem]

[0006] The invention is described with respect to the resistor by the features of claim 1 and with respect to the measuring method by the features of claim 17. The other related claims are advantageous embodiments and developments of the invention.

[0007] The present invention relates to a resistor having at least one connection element for connecting the resistor to a current circuit and at least one resistive element. The resistive element is conductively connected to the connection element via a contact surface. The extent of the resistive element in a direction perpendicular to the contact surface is called the length. The at least one resistive element and the at least one connection element are made of different conductive materials, preferably metallic materials. In this case, the specific electrical resistance of the material of the resistive element can be at least 10 times greater than the specific electrical resistance of the material of the connection element. On the other hand, the value of the temperature coefficient of resistance of the material of the connection element is much greater than the value of the temperature coefficient of resistance of the material of the resistive element, usually at least 80 times greater. In particular, the value of the temperature coefficient of resistance of the material of the resistive element is 5-10 -5 The temperature coefficient of resistance of the material of the connecting element can be less than 1 / K, and the temperature coefficient of resistance of the material of the connecting element can be about 4·10 -3 The resistance of the resistor may be 1 / K. The connection elements of the resistor may be made of copper, preferably a low-alloy copper alloy, or aluminum, preferably a low-alloy aluminum alloy, or may contain at least one of these materials. The resistive elements may be made of a copper alloy commonly used as a resistive alloy. At least one connection element may have a means, such as a hole, for connecting the resistor to an external current circuit. The resistor may preferably have two connection elements, between which the resistive element is located.

[0008] At least a portion of the surface of the resistor element as a substrate or at least a portion of the surface of the connecting element as a substrate is coated with a coating having at least one layer, which can have one or more layers, where the term "layer" refers to a spatial distribution of a uniform material, where the extent of the material perpendicular to the surface of the substrate, i.e., the thickness of the layer, is significantly smaller than the extent of the material parallel to the surface of the substrate.

[0009] According to a first aspect of the present invention, the coating is implemented so that there is direct metal-semiconductor contact at the interface between the substrate and the coating, thereby forming a pn junction at this interface. Preferably, the substrate material is metal, and the layer of the coating directly in contact with the substrate is implemented as a semiconductor. Both one coating layer and the other substrate, i.e., the uncoated portion of the surface of the resistive element or the connecting element, are contactable to detect a measurement signal for determining the resistor temperature. If the coating is applied to a resistive element, at least one layer of one coating and the uncoated portion of the surface of the other resistive element are contactable to detect a measurement signal for determining the resistor temperature. If the coating is applied to a connecting element, at least one layer of one coating and the uncoated portion of the surface of the other connecting element are contactable to detect a measurement signal for determining the resistor temperature. Preferably, the layer of the coating directly in contact with the substrate is contactable.

[0010] According to a second aspect of the invention, at least the interface between the first and second layers of the coating is in direct metal-semiconductor contact or in direct contact between the first and second semiconductors, so that a pn junction is formed at this interface. Both the first layer of the coating on the one hand and at least one further layer of the coating on the other hand, in particular the second layer of the coating directly contacting the first layer, are directly or indirectly contactable to detect a measurement signal for determining the temperature of the resistor.

[0011] The present invention is based on the idea of ​​directly determining temperature using the temperature behavior of the current-voltage characteristic curve of a pn junction. The current-voltage characteristic curve of a pn junction can be expressed using the Shockley equation, similar to the diode characteristic curve. The Shockley equation includes temperature-dependent values, namely, the temperature voltage and the reverse current. Therefore, the current-voltage characteristic curve of a pn junction varies with temperature. If the current flowing through the pn junction and the voltage dropping across it are known, the temperature prevailing at the pn junction can be calculated based on the temperature dependence of the known current-voltage characteristic curve. Metrological detection of such a pn junction as a temperature sensor can be implemented using discrete components, such as a constant current source, an operational amplifier, or an analog-to-digital converter (ADC), or alternatively, in an integrated circuit (IC).

[0012] According to the present invention, such a pn junction is realized by a coating on the resistor. This coating is thin compared to the substrate and has only a small thermal mass. On the other hand, the thermal coupling between the coating and the substrate is achieved over a large area. Therefore, the temperature of the pn junction is always very close to the temperature of the substrate. Even sudden changes in temperature are detected without any noticeable time lag. The coating can be applied either to the resistive element or to the connecting element. This makes it possible to determine the temperature of either the resistive element or the connecting element.

[0013] The pn junction can be realized directly at the interface between the substrate and the coating. In this case, the conductive substrate, preferably a metallic substrate, functions as the n-portion of the pn junction due to its free electrons. The layer of the coating that directly contacts the substrate must be selected so that it functions like a semiconductor in combination with the substrate, i.e., has a lack of free electrons compared to the substrate. This layer then forms the p-portion of the pn junction. Resistors with such pn junctions can be manufactured by depositing or building up, for example, a copper-based material, preferably an oxide, as a layer on the surface of the resistor. The selected material pair forms a pn junction with a unique current-voltage characteristic curve.

[0014] Alternatively, the pn junction can be realized at the interface between the first and second layers of the coating, i.e. by a suitable layer structure of the coating, where either the metal and the semiconductor, or the first and second semiconductor, are in direct contact with each other.

[0015] The described semiconducting properties are well known, and suitable material combinations using copper as the starting material are, for example, Cu / Cu(I)O, p-CuO / n-ZnO, SnF:SnO / CuAlO, or p-CuO / n-CuO. The oxides mentioned as examples have semiconducting properties. They can be called "oxide semiconductors." In such oxides, the energy difference between the valence band and the conduction band (band gap) is of the same order of magnitude as in semiconductors, i.e., in the region of a few electron volts (eV). Thermal excitation lifts electrons from the valence band to the conduction band. Thus, the electrical conductivity of oxides increases with temperature. The mentioned material pairs form material transitions with current-voltage characteristic curves that can be described by the Shockley equation, as in the case of semiconductor diodes. Starting from the mentioned examples, further material pairs with similar properties can be found. In such material pairs, the oxides function like semiconductors, and therefore can be included in the term "semiconductor" in the present invention.

[0016] A particular advantage of the present invention is that the temperature sensor formed by the coating is attached to the resistor over a large area, rather than at a point. Therefore, there is a good thermal connection between the sensor and the object whose temperature is to be measured. Furthermore, since the coating has very little heat capacity of its own, the temperature sensor responds very quickly to temperature changes in the substrate. In other words, due to its very small thermal mass, the coating has very little thermal inertia and can therefore detect temperature changes in the substrate very quickly.

[0017] In one embodiment of the present invention, the coating can have at least one layer made of or containing a doped semiconductor. Doping allows the properties of the semiconductor to be tailored. In particular, doping can influence the current-voltage characteristic curve of the pn junction. In this way, the accuracy of temperature measurement can be improved, for example. Both p-doping and n-doping of the same base material can be considered, for example in the case of p-CuO / n-CuO. Doping can be carried out during the coating process.

[0018] In a further embodiment of the present invention, the coating can have at least two layers, which are selected so that the pn junction is part of an npn junction or a pnp junction. In this way, a bipolar layer sequence is realized. The third material of the layer sequence can be the third layer of the coating or the substrate, i.e., the substrate of one of the conductive materials of the resistor. Such an arrangement can significantly improve measurement accuracy, since npn junctions or pnp junctions have significantly higher temperature consistency than pn junctions. In a particularly preferred configuration of this embodiment, all three materials of the bipolar layer sequence, in particular all three layers of the bipolar layer sequence, can be contactable to detect a measurement signal for determining the temperature of the resistor. This allows for the realization of a circuit equivalent to a bipolar transistor connected as a diode.

[0019] In a further embodiment of the invention, the coating may be applied only to a portion of the surface of the resistor element, thus making it possible to detect the temperature of critical points of the resistor element, for example particularly hot points.

[0020] In particular, in this embodiment, the resistive element may have a length perpendicular to the contact surface between the resistive element and the connecting element, and the coating may be applied to the center of the surface of the resistive element relative to the length of the resistive element. The coating is therefore positioned in the region of the resistive element that is furthest from the contact surface with the connecting element. The highest temperature occurs in this region. The average temperature of the resistor can be inferred from the highest temperature.

[0021] Preferably, the coating extends perpendicularly to the contact surface by at least 1 mm, particularly preferably at least 1.5 mm, and at most 4 mm, particularly preferably at most 2.5 mm. By selecting the dimensions of the coating in this region, the electrical quantity to be measured is set in an advantageous range.

[0022] Furthermore, in a special configuration of the aforementioned embodiment of the invention, the coating may be applied over the entire width of the resistor element, where the width of the resistor element is understood to be the extent of the resistor element longitudinally relative to the contact surface, i.e. transversely to the direction of current flow, and in this special configuration of the invention, the temperature is measured averaged over the entire width of the resistor element.

[0023] In a further special configuration of the aforementioned embodiment of the present invention, the first measuring tap can be in contact with the coating, i.e., the layer of the coating, and the second measuring tap can be in contact with the uncoated part of the surface of the resistive element, i.e., can be attached to the uncoated part of the surface of the resistive element. This arrangement of the measuring taps makes it possible to detect the voltage drop occurring at the pn junction at the interface between the resistive element as a substrate and the coating.

[0024] In an alternative embodiment of the invention, the coating may be applied only to a portion of the surface of the connection element, directly adjacent to the contact surface for the resistive element. With this positioning of the coating, the temperature of the connection element is measured in the immediate vicinity of the resistive element. From this measured temperature, the temperature of the resistive element can then be determined with sufficient accuracy. Depending on the choice of material, it may be easier to apply the coating to the connection element than to the resistive element.

[0025] In a particular configuration of this embodiment of the invention, the first measuring tap can be in contact with the coating, i.e., the layer of the coating, and the second measuring tap can be in contact with the uncoated part of the surface of the connection element, i.e., can be attached to the uncoated part of the surface of the connection element. This arrangement of the measuring taps makes it possible to detect the voltage drop occurring at the pn junction at the interface between the connection element as substrate and the coating.

[0026] In a further embodiment of the present invention, the coating can have a layer that is in direct contact with the substrate and that contains or is an oxide of the substrate material. Material compatibility between the substrate and the coating material that is in direct contact with the substrate creates particularly favorable conditions for the formation of a pn junction. For example, if the coating is applied to a connecting element made of copper, the layer that is in direct contact with the connecting element can be or contain Cu(I)O. Similarly, if a coating made of a copper-manganese alloy is applied to a resistive element, the layer that is in direct contact with the resistive element can be or contain CuMnO2.

[0027] In an alternative embodiment of the present invention, a barrier layer may be present between the substrate and the coating. In this case, the first measuring tap contacts one layer of the coating, and the second measuring tap contacts another layer of the coating. The barrier layer provides material separation between the substrate and the coating, but not thermal separation. Therefore, the substrate does not materially affect the coating process. This means that the coating can be selected from a wide range of materials, regardless of the substrate material. This allows the coating to be optimized for its function as a temperature sensor. For example, the barrier layer can be made of nickel.

[0028] In a further embodiment of the present invention, the coating may further comprise a layer used for passivation of the coating and for electrical contact of non-metallic layers of the coating. Preferably, this passivation layer is a metallic layer. Such a layer may be the layer of the coating that is furthest from the substrate.

[0029] In a further embodiment of the invention, the coating can have at least one layer with a thickness of at least 50 nm, preferably at least 70 nm, and at most 100 μm, preferably at most 10 μm. In particular, each layer of the coating can have a thickness in the ranges detailed above and in particular in the preferred sub-ranges thereof. Coatings comprising one or more layers in the ranges detailed above are particularly well suited for realizing temperature sensors based on pn junctions.

[0030] In a further embodiment of the present invention, the coating may be applied by CVD or PVD methods. CVD and PVD methods are well suited for applying coatings of the aforementioned type. In particular, these methods allow doping of semiconductor layers applied using these methods.

[0031] In further embodiments of the present invention, the coating may be applied in recesses in the surface of the substrate or on raised areas of the surface of the substrate. In some applications, it may be advantageous to apply the coating in recesses in the surface of the substrate to protect the surface from environmental influences, for example mechanical attack. In contrast, in some applications, it may be advantageous to apply the coating on raised areas of the surface of the substrate, which allows for advantageous contact with, for example, a measuring tap.

[0032] In a further embodiment of the invention, the resistor can be contacted by means of a plug, a printed circuit board or a cable to sense the measurement signal, which components make it possible in a simple and inexpensive way to read the measurement signal that needs to be sensed to determine the temperature.

[0033] Further technical features and advantages of the resistor according to the invention will now be explicitly explained with reference to the description relating to the method according to the invention for determining the temperature of a resistor, as well as the drawings, the description of the drawings and the examples.

[0034] A further aspect of the present invention relates to a method for determining the temperature of a resistor, the resistor having a coating as described above. The coating is selected so that a pn junction is formed at the interface between the substrate and the coating or between two layers of the coating. According to the invention, the current flowing through the pn junction and the voltage dropping across the pn junction are detected. From these two measurements, the temperature of the resistor is determined using the temperature-dependent current-voltage characteristic curve of the pn junction. According to a further aspect of the invention, the coating described above is used to determine the temperature of the resistor.

[0035] Further technical features and advantages of the method according to the invention for determining the temperature of a resistor and the use according to the invention of a coating for determining the temperature of a resistor will now be explicitly explained with reference to the description relating to the resistor according to the invention as well as the drawings, the description of the drawings and examples.

[0036] An embodiment of the invention will now be explained in more detail on the basis of a schematic diagram not to scale. [Brief explanation of the drawings]

[0037] [Figure 1] FIG. 1 is a diagram of a resistor with a coating on the resistive element. [Figure 2] FIG. 10 is a diagram of a resistor with a coating in a recess in the resistive element. [Figure 3] FIG. 10 is a diagram of a resistor with a coating on the raised areas of the resistive element. [Figure 4] FIG. 10 is a diagram of a resistor with a coating on the connection element. [Figure 5] FIG. 2 is a diagram of a resistive element with a coating having a first layer structure. [Figure 6] FIG. 10 is a diagram of a resistive element with a coating having a second layer structure. [Figure 7] FIG. 10 is a diagram of a resistive element with a coating having a third layer structure. DETAILED DESCRIPTION OF THE INVENTION

[0038] In all the figures, corresponding parts are given the same reference numerals.

[0039] FIG. 1 shows a resistor 2 comprising two connection elements 3, 3' and a resistive element 4 disposed between the two connection elements 3, 3'. The resistive element 4 is conductively connected to the two connection elements 3, 3' via contact surfaces 34, 34'. The extent of the resistive element 4 between the two contact surfaces 34, 34' is referred to as the length L. In the illustrated embodiment, for reasons of simplicity, the resistive element 4 is depicted as having a width B, i.e., its longitudinal extent relative to the contact surfaces 34, 34', the same size as the extent of the connection elements 3, 3' in this direction. Typically, the longitudinal extent of the resistive element 4 relative to the contact surfaces 34, 34' is somewhat smaller than the extent of the connection elements 3, 3' in this direction. For reasons of simplicity, the means for connecting the resistor 2 to an external current circuit, such as holes in the connection elements 3, 3', are not shown.

[0040] The resistive element 4 has a freely accessible surface 41. A thin strip of coating 5 is applied to a portion 411 of the surface 41 of the resistive element 4. This coating 5 is applied centrally between the two contact surfaces 34, 34', so that there is an uncoated portion 412, 412' of the surface 41 of the resistive element 4 between the coating 5 and each of the connection elements 3, 3'. The coating extends over the entire width B of the resistive element 4. Alternatively, the coating 5 could extend only over a portion of the width B of the resistive element 4. A pn ​​junction (not shown in detail) is formed at the interface 61 between the coating 5 and the resistive element 4.

[0041] The first measuring tap 71 is mounted so that it is in direct contact with the coating 5. The second measuring tap 72 is mounted so that it is in contact with the uncoated portion 412 of the surface 41 of the resistive element 4. These two measuring taps 71, 72 can be used to detect the voltage dropped across the pn junction.

[0042] In the case not shown in FIG. 1 where the coating 5 extends only over a portion of the width B of the resistive element 4, the uncoated portion 412, 412' of the surface 41 of the resistive element 4 also has a region that is as far away from the connection elements 3, 3' as the coating 5. This region will therefore be at the same potential as the coating 5 when a current flows through the resistive element 4. In this case, the second measuring tap 72 can advantageously be attached to this region of the uncoated portion 412, 412' of the surface 41 of the resistive element 4. Particularly preferably, the second measuring tap 72 can be positioned so that it is at the same distance from the two connection elements 3, 3' as the first measuring tap 71, which is in contact with the coating 5. This reduces measurement errors.

[0043] FIG. 2 shows a preferred embodiment of the resistor 2. The embodiment shown in FIG. 2 differs from the embodiment shown in FIG. 1 in that the coating 5 is located in a recess 8 of the resistive element 4. All other features of the resistor 2 shown in FIG. 2 correspond to those of the resistor 2 shown in FIG. 1. Furthermore, as described in connection with FIG. 1, it is also possible for the coating 5 and recess 8 to extend over only a portion of the width B of the resistive element 4, or for only the coating 5 to extend over only a portion of the width B of the resistive element 4, while the recess 8 extends over the entire width B of the resistive element 4. In these cases, the second measurement tap 72 may advantageously be positioned as described in connection with FIG. 1.

[0044] 3 shows a further preferred embodiment of resistor 2, in which coating 5 is applied to raised regions 9 of resistive element 4. All other features of resistor 2 shown in FIG. 3 correspond to those of resistor 2 shown in FIG. 1. Furthermore, as described in connection with FIG. 1, it is also possible for coating 5 and raised regions 9 to extend over only a portion of width B of resistive element 4, or for coating 5 alone to extend over only a portion of width B of resistive element 4, while raised regions 9 extend over the entire width B of resistive element 4. In these cases, second measurement tap 72 may advantageously be positioned as described in connection with FIG. 1.

[0045] FIG. 4 shows an alternative embodiment of a resistor 2. The basic structure of this resistor 2 with respect to the connection elements 3, 3′ and the resistive element 4 corresponds to the embodiment shown in FIG. 1. The connection element 3 has a freely accessible surface 31. A thin strip of coating 5 is applied to a portion 311 of the surface 31 of the connection element 3 directly at the transition to the resistive element 4. The surface 31 of the connection element 3 therefore has an uncoated portion 312. This coating extends over the entire area of ​​the connection element 3 in the longitudinal direction of the contact surfaces 34, 34′. Alternatively, the coating 5 can extend only over a portion of the connection element 3 in the longitudinal direction of the contact surfaces 34, 34′. A pn ​​junction (not shown in detail) is formed at the interface 61 between the coating 5 and the connection element 3. A first measuring tap 71 is attached so that it is in direct contact with the coating 5. A second measuring tap 72 is attached so that it is in contact with the uncoated portion 312 of the surface 31 of the connection element 3. These two measurement taps 71, 72 can be used to detect the voltage dropped across the pn junction.

[0046] In the case not shown in FIG. 4 , where the coating 5 extends only over part of the width B of the connection element 3, the uncoated part 312 of the surface 31 of the connection element 3 also comprises a region that is as far away from the resistive element 4 as the coating 5. This region will therefore be at the same potential as the coating 5 when a current flows through the resistor 2. In this case, the second measuring tap 72 can advantageously be attached to this region of the uncoated part 312 of the surface 31 of the connection element 3. Particularly preferably, the second measuring tap 72 can be positioned so that it has the same distance from the resistive element 4 as the first measuring tap 71, which is in contact with the coating 5.

[0047] 4 of the resistor 2 can be modified by applying a thin strip of coating 5 on the two connection elements 3, 3' directly at their respective transitions to the resistive element 4. The temperature of each of the two connection elements 3, 3' can therefore be measured in the immediate vicinity of their respective contact surfaces 34, 34'. Based on these temperatures, the thermal voltage occurring at each transition between the resistive element 4 and the connection element 3, 3' can be estimated.

[0048] FIG. 5 shows a resistive element 4 with a coating 5 having a first layer structure. The resistive element 4 shown can be part of the resistor 2 according to FIGS. 1 to 3. For simplicity's sake, the connection elements 3, 3', which contact both sides of the resistive element 4, are not shown. The coating 5 consists of a first layer 50, which is in direct contact with the resistive element 4, and an additional layer 59, which serves to passivate the coating 5 and electrically connect the first layer 50. The first layer 50 is preferably made of or may contain an oxide of the material of the resistive element 4. The additional layer 59 is made of metal and constitutes the top layer 59 of the coating 5, i.e., the layer furthest from the substrate. A pn ​​junction (not shown) is formed at the interface 61 between the first layer 50 of the coating 5 and the resistive element 4. A first measuring tap 71 contacts the coating 5 by contacting the top layer 59 of the coating 5. In this way, the first layer 50 of the coating 5 is electrically connected. A second measurement tap 72 contacts the resistive element 4 in an uncoated area 412 of the surface 41. These two measurement taps 71, 72 can be used to detect the voltage dropped across the pn junction.

[0049] FIG. 6 shows a resistive element 4 with a coating 5 having a second layer structure. The resistive element 4 shown can be part of the resistor 2 according to FIGS. 1 to 4. For simplicity's sake, the connection elements 3, 3' that contact the resistive element 4 on both sides are not shown. The coating 5 consists of a barrier layer 58 applied directly to the resistive element 4, a top layer 59 used for passivation and contact of the coating 5, and two further layers 51, 52 arranged between the barrier layer 58 and the top layer 59. The first of these two layers, layer 51, is applied on top of the barrier layer 58. The second of these two layers, layer 52, is in direct contact with the top layer 59. The first layer 51 can be a p-doped semiconductor. In this case, the second layer 52 is an n-doped semiconductor. However, it is also possible for the first layer 51 to be an n-doped semiconductor and the second layer 52 a p-doped semiconductor. In both cases, a pn junction (not shown) is formed at the interface 62 between the first 51 and second 52 of the two further layers. The first measuring tap 71 contacts the first 51 of the two further layers. The second measuring tap 72 contacts the coating 5 by contacting the top layer 59 of the coating 5. In this way, the second 52 of the further layers of the coating 5 is in electrical contact. These two measuring taps 71, 72 can be used to detect the voltage drop across the pn junction.

[0050] FIG. 7 shows a resistive element 4 with a coating 5 having a third layer structure. The resistive element 4 shown can be part of the resistor 2 according to FIGS. 1 to 4. For simplicity's sake, the connecting elements 3, 3' that contact the resistive element 4 on both sides are not shown. The coating 5 consists of a barrier layer 58 applied directly to the resistive element 4, a top layer 59 used for passivation and contact of the coating 5, and three additional layers 51, 52, and 53 arranged between the barrier layer 58 and the top layer 59. The first of these three layers, layer 51, is applied on top of the barrier layer 58. The third of these three layers, layer 53, is in direct contact with the top layer 59. The second of these three layers, layer 52, is arranged between the first layer 51 and the third layer 53. The first layer 51 can be a p-doped semiconductor. In this case, the second layer can be an n-doped semiconductor, and the third layer 53 can be a p-doped semiconductor. However, it is also possible for the first layer 51 to be an n-doped semiconductor, the second layer 52 to be a p-doped semiconductor, and the third layer 53 to be an n-doped semiconductor. A p-n junction (not shown) is formed at the interface 62 between the first layer 51 and the second layer 52 of the three additional layers. A p-n junction (not shown) is also formed at the interface 62' between the second layer 52 and the third layer 53 of the three additional layers, thereby forming an npn or pnp bipolar layer sequence for the three additional layers 51, 52, and 53. The first measurement tap 71 contacts the first layer 51 of the three additional layers. The second measurement tap 72 contacts the coating 5 by contacting the top layer 59 of the coating 5. In this way, the third layer 53 of the additional layer of the coating 5 is electrically contacted. Furthermore, an optional third measurement tap 73 contacts the second layer 52. The combination of the three measuring taps 71, 72, 73 creates a circuit that can sense the temperature using two pn junctions. Such a circuit corresponds to a bipolar transistor connected as a diode (English: diode connected bipolar transistor).

[0051] The coating 5 shown in Figures 5, 6 and 7 can be applied not only to the resistive element 4, but also to the connecting element 3 shown in Figure 4, or in a similar manner to the two connecting elements 3, 3' as described in connection with Figure 4. [Explanation of symbols]

[0052] 2 resistor 3,3' connecting element 31 Surface 311 Coated parts 312 Uncoated parts 34,34' contact surface 4 Resistive elements 41 Surface 411 Coated parts 412,412' Uncoated area 5. Coating 50,51,52,53 layers 58 Barrier Layer 59 layers 61,62,62' Boundary 71, 72, 73 Measuring tap 8 recess 9. Raised Areas L length B Width

Claims

1. A resistor (2) having at least one connection element (3, 3') for connecting the resistor (2) to a current circuit and at least one resistive element (4), the resistive element (4) being conductively connected to the connection element (3, 3') via contact surfaces (34, 34'), the at least one resistive element (4) and the at least one other connection element (3, 3') being made of different conductive materials, and a coating (5) having at least one layer (50, 51, 52, 53) is applied to at least a portion (411) of the surface (41) of the resistive element (4) as a substrate or to at least a portion (311) of the surface (31) of the connection element (3, 3') as a substrate, The coating (5) is implemented in such a way that at the interface (61) between the substrate and the coating (5) there is a direct metal-semiconductor contact, thereby forming a pn-junction at the interface (61), and / or at least at the interface (62, 62') between the first layer (50, 51) of the coating (5) and the second layer (52) of the coating (5) there is a direct metal-semiconductor contact or a direct first semiconductor-second semiconductor contact, thereby forming a pn-junction at the interface (62, 62'). and wherein at least one layer (50, 51, 52, 53) of the coating (5) on the one hand, and the uncoated portion (412, 412') of the surface (41) of the resistive element (4) on the other hand or the uncoated portion (312) of the surface (31) of the connecting element (3, 3') on the other hand, or the first layer (50, 51) of the coating (5) on the one hand, and at least one further layer (52, 53) on the other hand, are accessible to detect a measurement signal for determining the temperature of the resistor (2). A resistor (2) characterized in that

2. 2. The resistor (2) according to claim 1, characterized in that the coating (5) has at least one layer (51, 52, 53), which is made of or contains a doped semiconductor.

3. 3. Resistor (2) according to claim 1 or 2, characterized in that the coating (5) has at least two layers (50, 51, 52, 53), said layers (50, 51, 52, 53) being selected so that the pn junction is part of an npn junction or a pnp junction.

4. 4. The resistor (2) according to any one of claims 1 to 3, characterized in that the coating (5) is applied only to a portion (411) of the surface (41) of the resistive element (4).

5. 5. The resistor (2) according to claim 4, characterized in that the resistive element (4) has a length (L) perpendicular to the contact surface (34, 34') and the coating (5) is applied to the center of the surface (41) of the resistive element (4) relative to the length (L) of the resistive element (4).

6. 6. The resistor (2) according to claim 4 or 5, characterized in that the resistive element (4) has a width (B) in the longitudinal direction of the contact surface (34, 34'), and the coating (5) is applied across the width (B) of the resistive element (4).

7. 7. The resistor (2) according to claim 4, wherein a first measuring tap (71) is in contact with the coating (5) and a second measuring tap (72) is in contact with the uncoated portion (412, 412') of the surface (41) of the resistive element (4).

8. 4. The resistor (2) according to claim 1, wherein the coating (5) is applied to a portion (311) of the surface (31) of the connection element (3, 3') directly adjacent to the contact surface (34, 34') for the resistive element (4).

9. 9. The resistor (2) according to claim 8, characterized in that a first measuring tap (71) is in contact with the coating (5) and a second measuring tap (72) is in contact with the uncoated part (312) of the surface (31) of the connection element (3, 3').

10. 10. Resistor (2) according to any one of claims 1 to 9, characterized in that the coating (5) has a layer (50) in direct contact with the substrate and comprising or being an oxide of the material of the substrate.

11. 9. The resistor (2) according to claim 1, wherein a barrier layer (58) is present between the substrate and the coating (5), and wherein a first measuring tap (71) is in contact with a first layer (51) of the coating (5) and a second measuring tap (72) is in contact with a further layer (52, 53) of the coating (5).

12. 12. Resistor (2) according to any one of claims 1 to 11, characterized in that the coating (5) has a layer (59) used for passivation of the coating (5) and for electrical contact of the non-metallic layers (50, 51, 52, 53) of the coating (5).

13. 13. Resistor (2) according to any one of claims 1 to 12, characterized in that the coating (5) comprises at least one layer (50, 51, 52, 53) with a thickness of at least 50 nm and at most 100 μm.

14. Resistor (2) according to any one of claims 1 to 13, characterized in that the coating (5) is applied by CVD or PVD methods.

15. 15. A resistor (2) according to any one of claims 1 to 14, characterized in that the coating (5) is applied in recesses (8) of the surface (31, 41) of the substrate or on raised areas (9) of the surface (31, 41) of the substrate.

16. 16. Resistor (2) according to any one of claims 1 to 15, characterized in that the resistor (2) is contacted by means of a plug, a printed circuit board or a cable to detect the measurement signal.

17. 17. A method for determining the temperature of a resistor (2) according to any one of claims 1 to 16, characterized in that the current flowing through the pn junction and the voltage dropping across the pn junction are detected and the temperature of the resistor (2) is determined therefrom.

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