Patent Publication Number: US-2021190473-A1

Title: Stator package, rotor package and inductive angle sensor

Description:
FIELD 
     The present concept relates to a stator package for use in an inductive angle sensor and to an associated rotor package for use in an inductive angle sensor. The present concept also relates to an inductive angle sensor with such a rotor package and such a stator package and to corresponding methods for producing the packages and the inductive angle sensor. 
     BACKGROUND 
     Position sensors are used to determine the position between two components rotating in relation to one another, such as for example a rotor and a stator. Such angle sensors are used for example for determining a steering angle or for determining the position of an engine shaft and the like. 
     There are various methods and devices for determining the angle between two components. The concept described here is concerned with sensors in the technical field of inductive angle measurement. 
     SUMMARY 
     In the case of sensors which use the inductive measuring principle, an excitation coil is arranged on a first sensor component, for example on a stator. The excitation coil is excited by an alternating current and then generates a corresponding induction field or magnetic field. A second sensor component, for example a rotor, is rotatable in relation to the first sensor component. A so-called inductive target is provided on the second sensor component. This inductive target receives the induction field or magnetic field generated by the excitation coil. The inductive target is electrically conductive, so that an induction current forms in the inductive target in response to the received induction field or magnetic field. This induced induction current in turn causes a corresponding induction field or magnetic  field in the target. The first sensor component, that is to say for example the stator, has a receiving coil, which receives the induction field or magnetic field generated by the target and in response to this generates an induction signal, for example a corresponding induction current or an induction voltage. The signal strength of this induction signal in this case depends primarily on the position of the two sensor components in relation to one another, and consequently varies in dependence on the position of the two sensor components in relation to one another. Consequently, on the basis of an evaluation of the signal strength of the induction signal induced in the receiving coil, the position of the two sensor components in relation to one another can be determined. 
     This inductive sensor principle consequently differs from conventional magnetic field sensors, which measure the magnetic field strength of a magnetic field, in particular a permanent magnetic field. In this case, the magnetic field strength varies in dependence on the position of the two sensor components in relation to one another. Another difference is for example in the selection of the materials. While in the case of a magnetic field sensor ferromagnetic materials are used, in the case of inductive sensors non-ferromagnetic materials with electrical conductivity, for example aluminum, can also be used. 
     Magnetic field sensors can be produced with very small dimensions. However, magnetic field sensors are susceptible to the effect of external disturbances, which may result in particular from the presence of ferromagnetic materials. Consequently, the reliability of magnetic field sensors can vary, sometimes greatly, in environments with many magnetic components. 
     By contrast, inductive angle and/or position sensors are insensitive to ferromagnetic materials. The area of use of inductive sensors is consequently significantly extended in comparison with the area of use of previously described magnetic field sensors. Furthermore, inductive sensors are essentially unsusceptible to external influences, such as for example dust, dirt or liquids. 
     Depending on how sensitive the inductive sensor is intended to be, or how great the desired measuring distances of the inductive sensor are, sometimes high currents are induced in the respective coils. In order to ensure the desired high sensitivity of an inductive sensor, the losses and parasitic inductances should in this case be kept as low as possible. Accordingly, the dimensions of the windings of the respective coils should be designed for the sometimes high currents. The coils are therefore usually produced in the form of structured conductor tracks on printed boards, known as PCBs (PCB: Printed Circuit Board). Additionally arranged laterally alongside the structured conductor track coils on the PCB is a chip package with a corresponding circuit for operating the inductive sensor on the PCB. It is desirable for such inductive sensors to be as small as possible. However, both the structured conductor track coil on the PCB and the chip package placed alongside it require a certain minimum mounting area. Moreover, the minimum conductor track thickness that can be realized on a PCB is also an additional limiting factor in the degree of miniaturization of the sensor. 
     The coils on the PCB should in principle be produced very exactly, even small deviations from the desired layout potentially leading to errors in the angle measurement. For example, individual coils may be connected to one another by means of vias in the PCB. These vias may be arranged along the outer circumference and along the inner circumference of the coils. However, deviations in the arrangement and size of the vias may lead to errors of a higher order (in the angle domain), it being very difficult in turn to be able to compensate for these errors. The diameters of such vias in a PCB are also usually much greater than the width of individual conductor tracks on the PCB. Thus, for example, in the case of a coil with an inside diameter of 15 mm, the vias arranged on the inside diameter may be arranged so close together that for example there is no longer any space for a rotatable shaft required for the rotation, or a further reduction in size of the inside diameter is no longer possible. In addition to this there is the fact that the relatively high amount of metallization accounted for by all of the vias may lead to noticeable errors in the angle measurement, for example on account of undesired eddy currents in the vias or on account of capacitive coupling. 
     Inductive sensor systems with multiple components, for example with multiple coils, can be easily produced by PCB technology. For example, multilayer PCBs with multiple integrated metal layers may be used for this. However, an increase in the number of metal layers required for this leads to an increase in the production costs. As an alternative, the metal layers may be arranged on the front side and back side of a PCB, which is less expensive than the use of multilayer PCBs. However, this has the effect of increasing the vertical distance between the coils on the front side and the back side. This distance may be for example 0.5 mm, which corresponds to approximately 40% of the nominal air gap between the rotor and the stator, which in turn can have noticeable effects on the measuring accuracy. Furthermore, the restricted accuracy of the alignment of metal layers in the PCB can lead to angular errors. 
     Apart from this, PCBs may be susceptible to delamination on account of thermo-mechanical or hygro-mechanical stress, which may also lead to ruptures in the copper conductor tracks. It may therefore be necessary to test the coil integration in the field, for which purpose for example precise resistances may be used in the coil windings, it then being possible to check while operation is in progress whether these resistances are still present between various terminals. These resistances may take the form of SMD components, which are placed very precisely on the coil conductor tracks. Moreover, these SMD components have a height of 1 mm to 2 mm. This can also lead to angular errors, in particular in the case of small coils. Moreover, as a result there is a potential risk of collision between the rotor and the stator, which could damage the coils. 
     The production of inductive angle sensors or their individual components by PCB technology can therefore be easily carried out and is inexpensive, but with the increasing degree of miniaturization of the coils can lead to the aforementioned problems and to the associated measuring inaccuracies 
     It would accordingly be desirable to provide an inductive angle sensor or individual sensor components for such an inductive angle sensor that have the smallest possible dimensions but nevertheless produce precise measurement results and at the same time can be produced inexpensively. 
     Therefore, a stator package with the features of claim  1  is proposed as such a sensor component. Furthermore, a rotor package with the features of claim  16  is proposed as a further sensor component. Moreover, an angle sensor according to claim  17  with such a stator package and such a rotor package is proposed. Embodiments and further advantageous aspects of the respective devices are specified in the respectively dependent patent claims 
     According to one aspect, a stator package for use in an inductive angle sensor is proposed, wherein the stator package includes, inter alia, a substrate on which at least two metallization layers arranged at different levels may be arranged. The stator package may also include a receiving coil arrangement with at least two electrically conductive receiving coils, which are designed to receive a magnetic field emitted by an inductive target arrangement that is rotatable in relation to the stator package and to generate induction signals in response thereto. The stator package may also include a semiconductor chip, which is connected in an electrically conducting manner to the receiving coil arrangement, wherein the semiconductor chip includes an integrated circuit which is designed to evaluate the induction signals and to ascertain on the basis of the induction signals a rotation angle between the receiving coils and the inductive target arrangement rotatable in relation thereto. An electrically insulating potting compound may surround the substrate including the semiconductor chip and the receiving coils. According to the innovative concept described here, the two receiving coils may be implemented in the two metallization layers by thin-film technology. 
     According to a further aspect, a method for producing such a stator package is proposed, wherein the method includes, inter alia, a step of providing a substrate and arranging at least two metallization layers arranged at different levels on the substrate. The method may be devised in such a way as to produce a receiving coil arrangement with at least two electrically conductive receiving coils, which are designed to receive a magnetic field emitted by an inductive target arrangement that is rotatable in relation to the stator package and to generate induction signals in response thereto. A semiconductor chip may be arranged on or alongside the substrate and brought into electrical contact with the receiving coil arrangement, wherein the semiconductor chip may include a circuit which is designed to evaluate the induction signals and to ascertain on the basis of the induction signals a rotation angle between the receiving coils and the inductive target arrangement rotatable in relation thereto. The method may also be devised in such a way as to apply an electrically insulating potting compound, which surrounds the substrate including the semiconductor chip and the receiving coils. According to the innovative concept described here, the two receiving coils may be implemented in the two metallization layers by thin-film technology. 
     According to a further aspect, a rotor package for use in an inductive angle sensor is proposed, wherein the rotor package includes, inter alia, a substrate on which at least one metallization layer may be arranged. The rotor package may also include an inductive target arrangement with at least one electrically conductive inductive target, which is designed to generate an induction current in response to a magnetic field emitted by an excitation coil and to generate a magnetic field corresponding to the induction current and to emit it in the direction of the stator package. Furthermore, the rotor package may include an electrically insulating sealing or potting compound, which surrounds the substrate including the target arrangement. The rotor package may be arranged on a rotatable shaft for conjoint rotation and be rotatable in relation to the stator package. Furthermore, the at least one inductive target of the target arrangement may be implemented in the at least one metallization layer. 
     According to a further aspect, a method for producing such a rotor package is proposed, wherein the method includes, inter alia, a step of providing a substrate and arranging at least one metallization layer on the substrate. The method may be devised in such a way as to produce an inductive target arrangement with at least one electrically conductive inductive target, which is designed to generate an induction current in response to a magnetic field emitted by an excitation coil and to generate a magnetic field corresponding to the induction current and to emit it in the direction of the stator package. The at least one inductive target of the target arrangement may be implemented in the at least one metallization layer. In a further method step, an electrically insulating sealing or potting compound, which surrounds the substrate including the target arrangement, may be applied. Furthermore, the rotor package may be arranged on a rotatable shaft for conjoint rotation, so that the rotor package is rotatable in relation to the stator package. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Some exemplary embodiments are explained below and are represented by way of example in the drawing, in which: 
         FIG. 1  shows a lateral sectional view of an inductive angle sensor with a stator package and a rotor package according to an exemplary embodiment, 
         FIG. 2  shows a plan view of a stator package according to an exemplary embodiment, 
         FIG. 3A  shows a lateral sectional view of an inductive angle sensor with a stator package and a rotor package according to a further exemplary embodiment, 
         FIG. 3B  shows a lateral sectional view of an inductive angle sensor with a stator package and a rotor package according to a further exemplary embodiment, 
         FIG. 4  shows a lateral sectional view of an inductive angle sensor in an end-of-shaft configuration with a stator package, a rotor package and a separate component board according to an exemplary embodiment, 
         FIG. 5  shows a lateral sectional view of an inductive angle sensor in a through-shaft configuration with a stator package, a rotor package and a separate component board according to an exemplary embodiment, 
         FIG. 6  shows a schematic block diagram to illustrate a method for producing a stator package according to an exemplary embodiment, and 
         FIG. 7  shows a schematic block diagram to illustrate a method for producing a rotor package according to an exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Exemplary embodiments are described in more detail below with reference to the figures, wherein elements with the same or a similar function are provided with the same reference signs. 
     Method steps that are shown in one block diagram and explained with reference to the same can also be carried out in a sequence other than that depicted or described. In addition, method steps that relate to a specific feature of a device can be exchanged with this very feature of the device, and the opposite is equally true. 
     The terms stator package and rotor package are used here mainly for better understanding. The two packages can rotate in relation to one another. Whether the rotor package rotates and the stator package is fixed in place, or whether perhaps the stator package rotates and the rotor package is fixed in place is immaterial here. 
       FIG. 1  shows an exemplary embodiment of an inductive angle sensor  1000  with a stator package  10  according to an embodiment that is given by way of example and is not limiting and also with a rotor package  100  according to an embodiment that is given by way of example and is not limiting. 
     The stator package  10  depicted here comprises a receiving coil arrangement  30  with at least two electrically conductive receiving coils  31 ,  32 . The receiving coil arrangement  30  may however also comprise more than two electrically conductive receiving coils. Preferably, the receiving coil arrangement  30  may comprise an even number of receiving coils. 
     The rotor package  100 , which is rotatable in relation to the stator package  10 , comprises an inductive target arrangement  130 . The inductive target arrangement  130  may comprise at least one electrically conductive inductive target  131 . The inductive target arrangement  130  may however also comprise multiple electrically conductive inductive targets. For example, the inductive target arrangement  130  in the case of inductive angle sensors that use the vernier principle may comprise two electrically conductive inductive targets. The target arrangement  130  may however in principle also comprise more than two electrically conductive inductive targets. The number of electrically conductive inductive targets of the target arrangement  130  may for example be dependent on the number of receiving coils  31 ,  32  in the receiving coil arrangement  30 . For example, an electrically conductive inductive target may be provided for every two receiving coils  31 ,  32 . 
     An excitation coil (not depicted here), which may for example be arranged in the stator package  10  or on an additional component board (see  FIGS. 4 and 5 ), may emit a magnetic field in the direction of the inductive target  131 . The inductive target  131  may be designed to generate an induction current in response to the magnetic field emitted by the excitation coil and to generate a magnetic field corresponding to the induction current, which is then in turn emitted in the direction of the stator package  10 , and in particular in the direction of the receiving coil arrangement  30 . 
     The receiving coils  31 ,  32  may be designed to receive the magnetic field emitted by the inductive target arrangement  131  that is rotatable in relation to the stator package  10  and to generate induction signals in response thereto. On the basis of these induction signals, the rotation angle between the stator package  10  and the rotor package  100  can be determined. 
     For this purpose, the stator package  10  may comprise a semiconductor chip  21 . The semiconductor chip  21  may be connected in an electrically conducting manner, for example by means of bonding wires  22 , to the receiving coil arrangement  30  and comprise an integrated circuit, for example an ASIC (Application Specific Integrated Circuit). The integrated circuit may be designed to evaluate the aforementioned induction signals, received from the receiving coil arrangement  30 , and to ascertain on the basis of these induction signals the rotation angle between the receiving coil arrangement  30  that is arranged in the stator package  10  and the inductive target arrangement  130  that is rotatable in relation thereto and is arranged in the rotor package  100 . 
     The stator package  10  may comprise a substrate  20 . The substrate  20  may for example comprise at least one inorganic material from the group comprising silicon, glass or ceramic, or be produced therefrom. The substrate may have a thickness of between 50 μm and 800 μm, and preferably between 200 μm and 500 μm. 
     At least two metallization layers  11 ,  12  may be arranged on the substrate  20 . At least one of the at least two metallization layers  11 ,  12  may also be, at least partially, integrated in the substrate  20 . The metallization layers  11 ,  12  may be metal layers integrated in the substrate, for example inorganic substrates. It would likewise be conceivable that the substrate  20  is configured in the form of a WLB substrate or eWLB substrate ((e)WLB: (Embedded) Wafer Level Ball Grid Array). Here, the metallization layers  11 ,  12  may be for example in the so-called redistribution layer, RDL for short. 
     The at least two metallization layers  11 ,  12  may be arranged on two different levels. The cross section of the stack of layers may be such that the at least two metallization layers  11 ,  12  are provided on the base substrate  20 . In other words, the stator package  10  may comprise a vertical stack of layers with at least two levels lying vertically one above the other, wherein at least one metallization layer  11 ,  12  is respectively arranged at each level. Consequently, the stack of layers comprises at least two metallization layers  11 ,  12  vertically spaced apart from one another. That is to say that the at least two metallization layers  11 ,  12  are not arranged laterally alongside one another but vertically one above the other. 
     According to the innovative concept described here, the at least two aforementioned receiving coils  31 ,  32  of the receiving coil arrangement  30  may be implemented in the aforementioned at least two metallization layers  11 ,  12  of the vertical stack of layers by thin-film technology. 
     For example, the at least two spaced-apart metallization layers  11 ,  12  may be structured by means of thin-film technology for producing the receiving coils  31 ,  32 . The term thin-film technology may be understood as meaning structured metallization deposition (for example by means of sputtering or vapor depositing—with structuring by lithography). The term thin-film technology may likewise include when a thin so-called seed layer produced in this way is subsequently reinforced by a plating process—this may take place electrolytically or electrolessly. Dielectric layers may be produced or laminated by spin-on technology. Among the production methods that are used in thin-film technology are those known from microelectronics. 
     By contrast, the term thick-film technology would include for example subtractive techniques, such as for example in circuit board production (for example etching of copper-laminated layers) or else the printing of conductive pastes with subsequent curing. Structurally, metallization layers that have been produced by thin-film technology can consequently be distinguished from metallization layers produced by thick-film technology. 
     The advantages of thin-film technology lie in the possibility of realizing smaller structures (both structure widths and structure spacings). In the case of coils, for example, consequently more turns can be provided on the same surface area. 
     The application of thin-film technology described in the present disclosure in the production of inductive angle sensors accordingly allows the aforementioned receiving coils  31 ,  32  of the receiving coil arrangement  30  to be produced in a very miniaturized form, but nevertheless with very high accuracy. The entire stator package  10  can for example have a footprint (i.e. outer dimensions) of less than 15 mm, or of less than 10 mm. 
     According to an exemplary embodiment, the metallization layers  11 ,  12  may have in each case a layer thickness of 100 nm to 5 μm. Furthermore, the receiving coils  31 ,  32  of the receiving coil arrangement  30  that can be produced from the metallization layers  11 ,  12  by thin-film technology may comprise one or more turns with a width of 10 μm or less. 
     At least one electrically insulating layer  13  may be arranged between the at least two spaced-apart metallization layers  11 ,  12 . On account of the thin-film technology that can be applied, there may also be the advantage here that this electrically insulating layer  13  can be very thin. The electrically insulating layer  13  may for example have a layer thickness of approximately 100 nm to approximately 10 μm, preferably of approximately 300 nm. This may be conducive to the matching, that is to say the pairing tolerance, of the two receiving coils  31 ,  32 . 
     According to the innovative concept described here, the stator package  10  may also comprise an electrically insulating sealing or potting compound  23 . The potting compound  23  may surround the substrate  20  including the semiconductor chip  21  and the receiving coils  31 ,  32 . This offers a further decisive advantage. By means of the potting compound  23 , the numerous connections (for example bonding wires  22 ) between the receiving coils  31 ,  32  and the semiconductor chip  21 , or the integrated circuit, can be encapsulated. The entire stator package  10  can consequently be of a much more reliable and robust configuration than in the prior art. In the case of conventional angle sensors according to the prior art, soldered conductor tracks are provided on a printed board. These conductor tracks can become detached and they have a tendency to corrode. Furthermore, there is the risk of so-called cold solder joints. Printed boards also have a tendency for the individual layers to delaminate on account of thermal or mechanical stress. 
     In comparison, the fully encapsulated stator package  10  described here has significant advantages. The individual elements of the stator package  10  are to the greatest extent protected from external influences by the potting compound  23 . In combination with the application of thin-film technology for producing the individual receiving coils  31 ,  32  of the receiving coil arrangement  30 , it is consequently possible to produce a very miniaturized, high-precision and robust stator package  10 , which moreover can be produced inexpensively. 
     The same also applies incidentally to the rotor package  100  described here. The rotor package  10  may also comprise a substrate  120 , on or in which at least one metallization layer  111  may be arranged. Here, too, the substrate  120  may for example comprise at least one inorganic material from the group comprising silicon, glass or ceramic or be produced therefrom. The substrate  120  may have a thickness of between 50 μm and 800 μm, and preferably between 200 μm and 500 μm. 
     The rotor package  100  can also be produced in a miniaturized form. The entire rotor package  100  can for example have a footprint (i.e. outer dimensions) of less than 15 mm, or of less than 10 mm, or even of less than 5 mm. In one embodiment, the rotor package  100  may have outer dimensions of approximately 5×5 mm. The rotor package  100  may be designed as ring-shaped or round or oval. The rotor package  100  may in this case have a diameter of approximately 6 mm to 12 mm. 
     The previously mentioned inductive target arrangement  130  may be implemented in the at least one metallization layer  111 . Here, too, thin-film technology may possibly be applied for producing the target arrangement  130 . The target arrangement  130  may have the form of a coil or be designed in the form of a solid shaped metal part. For example, the target arrangement  130  may be produced from a thin metal sheet, for example a copper sheet. The target arrangement  130  may for example be stamped or etched from the metal sheet. In this case it is possible to dispense with the application of thin-film technology, so that a relatively thicker target arrangement  130 , with a thickness of approximately 0.1 mm to 0.5 mm, may be produced. Such a target arrangement  130  would be more resistant to greater electrical currents. 
     This is relevant because the electrical induction currents occurring in the case of an inductive angle sensor  1000  may be much higher in the excitation coil and in the inductive target  130  than the currents induced in the receiving coils  31 ,  32  of the receiving coil arrangement  30 . This is one reason why the receiving coils  31 ,  32  according to the concept described here can be produced particularly advantageously by thin-film technology. 
     As mentioned above, it is possible to dispense with the application of thin-film technology in the production of the target arrangement  130 , in order to be able to conduct better the sometimes high electrical currents. For example, a metal sheet (for example a toothed disk or lead frame) may be preferred for the production of the target arrangement  130 . For Vernier principles, for example, a target arrangement  130  with at least two inductive targets with different pole pitch is required (for example 3 and 4 teeth or loops of the turn). In such a case, on the other hand, it may be advantageous to use a substrate and to apply thicker metal layers to it, for example electrolytically. For example, first a thin layer may be applied by means of a sputtering technique, and then this layer can be made to become thicker, for example by electrolytic deposition. 
     In terms of the form, the target arrangement  130  may be designed as a coil, while it would then in turn be possible for example for it to be produced by means of thin-film technology. The geometrical form of the target arrangement  130  may for example be similar or identical to the geometrical form of the receiving coils  31 ,  32  of the receiving coil arrangement  30 . In particular if the target arrangement  130  is designed as a coil, it would be an option to configure the substrate  120  in the form of a WLB substrate or eWLB substrate ((e)WLB: (Embedded) Wafer Level Ball Grid Array). Here, the metallization layer  111  from which the target arrangement  130  can be produced may be for example a metallization layer in the so-called redistribution layer, RDL for short. 
     The rotor package  100  may also be potted by means of a sealing or an electrically insulating potting compound  123 . That is to say that the potting compound  123  may surround the substrate  120  including the metallization  111  or the inductive target arrangement  130  that can be produced therefrom. Consequently, the rotor package  100  can also be reliably protected from external influences. The rotor package  100  may in its outer appearance essentially resemble a pill. 
     Such a pill-shaped rotor package  100  may for example also be intentionally made somewhat thicker and have a thickness of approximately 5 mm. This could ensure a sufficiently great distance between the coils and a metallic rotatable shaft  200  in a so-called end-of-shaft system (see  FIG. 4 ), or this could allow the coils to be arranged at right angles to the axis of rotation  201 . 
     Such a rotatable shaft  200  is likewise shown in  FIG. 1 . The rotatable shaft  200  may rotate about its axis of rotation  201 . The inductive angle sensor  1000  that is depicted here by way of example is a so-called through-shaft system. In this case, the rotatable shaft  200 , seen in the running direction of its axis of rotation  201 , runs rotatably through the entire stator package  10 . 
     For example, for this purpose the stator package  10  may comprise a through-opening  25  extending through the substrate  20 . The shaft  200  can then extend through this through-opening  25 . Consequently, the shaft  200  can rotate independently of the stator package  10 . Or in other words, the shaft  200  extending through the stator package  10  can rotate, while the stator package  10  remains stationary and does not rotate along with the shaft  200 . The shaft  200  can in the same way also extend through the potting compound  23 . 
       FIG. 2  shows schematically, and not to scale, a plan view of the stator package  10  with the shaft  200  running through. The shaft  200  extends through the through-opening  25  in the substrate  20 . The through-opening  25  may for example have a diameter of between 2 mm and 5 mm. The shaft  200  may have a diameter that is slightly smaller, for example by a few tenths of a millimeter, so that it can be led rotatably through the through-opening  25 . The shaft  200  may for example have a diameter of 1 mm to 4 mm. 
     Also shown in  FIG. 2 , likewise purely schematically and not to scale, is a detail of two metallization layers  11 ,  12 , which are vertically spaced apart from one another and in which the receiving coils  31 ,  32  of the receiving coil arrangement  30  can be produced. The receiving coil arrangement  30  may be designed as ring-shaped and enclose or form a ring around the through-opening  25 . 
     The different levels of the metallization layers  11 ,  12  are indicated here purely schematically by means of solid and dashed lines. This is intended to indicate that the individual receiving coils  31 ,  32  extend alternately over the two metallization layers  11 ,  12  or over the two levels, and are consequently woven within one another. That is to say that it should not necessarily be understood that the first receiving coil  31  is produced exclusively in a first metallization layer  11 , and the second receiving coil  32  is produced exclusively in a second metallization layer  12 . Rather, the two metallization layers  11 ,  12  may be used for producing both receiving coils  31 ,  32 , wherein individual coil segments alternate between the first (upper) metallization layer  11  and the second (lower) metallization layer  12 , so that the two receiving coils  31 ,  32  end up being woven within one another. That is to say that the wire of one coil  31  threads through a loop of the other coil  32 , respectively. Thus, for example, also four coils may be produced in only two layers. 
     This alternation of the coil segments between the two levels of the metallization layers  11 ,  12  may for example take place in vertical plated-through holes or vias  210 ,  220  provided specifically for this purpose. That is to say that, in these vias  210 ,  220 , the coil structure of a receiving coil  31 ,  32  changes between a first (upper) level and a second (lower) level. The two receiving coils  31 ,  32  cross one another as it were in these vias  210 ,  220 , and change their respective level, so that there is no intersection of the receiving coils  31 , 32  with one another. 
     The vias  210 ,  220  may be arranged both at the outer circumference of the receiving coil arrangement  30  (see the vias  220 ) and at the inner circumference of the receiving coil arrangement  30  (see the vias  210 ). The production of the receiving coils  31 ,  32  by thin-film technology offers a further advantage here for the miniaturization of the stator package  10 . This is so because the vias  210 ,  220  can likewise be produced by thin-film technology. The vias  210 ,  220  may have here a diameter of less than 10 μm. This offers the advantage that the vias  210  arranged at the inner circumference of the receiving coil arrangement  30  in particular can be arranged very close together. That is to say that the vias  210  need much less space in comparison with conventional vias in printed circuit boards as they have previously been configured in the prior art. Accordingly, the inside diameter of the receiving coil arrangement  30  described here, produced by thin-film technology, can be reduced significantly in comparison with conventional systems produced by PCB technology. 
     So the more the inside diameter of a receiving coil arrangement is reduced, the closer the vias distributed along the inside diameter move together. Vias in printed circuit boards have a diameter of 100 μm or more. That is to say that the more the inside diameter of a receiving coil arrangement is reduced in size, the more the individual vias distributed along the inside diameter are adjacent to one another and thereby restrict the reduction in size of the inside diameter of the receiving coil arrangement that is possible at all. Thus, for example, the inside diameter of a receiving coil arrangement that can be produced by PCB technology is restricted to approximately 15 mm. The outside diameter runs here to approximately 25 mm. In this case, the inside diameter of the receiving coil arrangement is populated with such a high density of vias that a further reduction in size is no longer possible, and there is also no space any longer for a rotatable shaft to be led through. 
     By contrast, the stator package  10  disclosed here, in which the receiving coils  31 ,  32  can be produced by thin-film technology, avoids this problem. As mentioned at the beginning, the vias  210 ,  220  can also be produced by thin-film technology with a diameter of approximately 10 μm or less. This allows the inside diameter of the receiving coil arrangement  30  to be reduced down to 5 mm, while nevertheless a shaft  200  still fits through the stator package  10 . Also, the outside diameter can be reduced to approximately 16 mm or less, so that altogether a much smaller stator package  10  can be produced. 
     As shown by way of example in  FIG. 2 , the receiving coil arrangement  30  may be designed as ring-shaped and extend around the shaft  200 . The vias  210  arranged at the inside diameter of the receiving coil arrangement  30  can accordingly likewise extend around the shaft  200  in a ring-shaped manner. Here the vias  210  can be brought very close to the through-opening  25 . 
     The through-opening  25  may have a form that allows the shaft  200  (with a diameter of for example 1 mm to 5 mm) to be inserted through and still leave at least several tenths of a millimeter of air, in order to prevent direct contact and abrasion. The through-opening  25  may be circular, or else however square, oval or polygonal, for example triangular, rectangular, pentagonal, hexagonal, etc., perhaps with or without rounding of the corners. It is possible that such a through-opening  25  can be difficult to produce in some substrates, then resulting for example in one of the aforementioned special geometrical forms (for example a hexagon), which may deviate from a circular form shown here purely by way of example. 
       FIGS. 3A and 3B  respectively show a further conceivable exemplary embodiment of an inductive angle sensor  1000 . These embodiments are similar to the embodiment discussed above with reference to  FIG. 1 , for which reason elements with a similar or the same function are provided with the same reference signs. While in the exemplary embodiment shown in  FIG. 1  the semiconductor chip  21  is arranged asymmetrically, i.e. laterally, in relation to the receiving coil arrangement  30 , the semiconductor chip  21  in the case of the exemplary embodiments shown in  FIGS. 3A and 3B  may be arranged essentially centrally or in the middle. 
       FIG. 3A  shows an exemplary embodiment in which the semiconductor chip  21  is arranged on the receiving coil arrangement  30 . A dielectric layer (not shown here) may for example be provided between the semiconductor chip  21  and the receiving coil arrangement  30 . The shaft  200  may extend through the semiconductor chip  21 . That is to say that the semiconductor chip  21  may also have a through-opening  25 , through which the shaft  200  extends. Seen in plan view, the receiving coil arrangement  30  would be arranged here, at least with its outside diameter, around the semiconductor chip  21 . The semiconductor chip  21  may be arranged centrally with reference to the shaft  200  or the receiving coil arrangement  30 . 
       FIG. 3B  shows an alternative exemplary embodiment. Here, the inside diameter of the receiving coil arrangement  30  may be increased in size, so that the semiconductor chip  21  can be arranged within the receiving coil arrangement  30  on the substrate  20 . Here, too, the shaft  200  can again extend through the semiconductor chip  21 . Seen in plan view, the receiving coil arrangement  30  would be arranged here, both with its outside diameter and with its inside diameter, around the semiconductor chip  21 . The semiconductor chip  21  may be arranged centrally with reference to the shaft  200  or the receiving coil arrangement  30 . 
     As already mentioned at the beginning, the inductive angle sensors  1000  presented here may be so-called end-of-shaft systems or through-shaft systems. So far, through-shaft systems have been described purely by way of example. 
       FIG. 4  shows an example of an end-of-shaft system. In addition to the previously discussed embodiments, here an external component board  300  is shown. The component board  300  may be for example a PCB. An excitation coil  40  may be arranged in, at or on the component board  300 . The excitation coil  40  may be connected in an electrically conductive manner to the semiconductor chip  21  or integrated circuit arranged in the stator package  10  by means of suitable galvanic connections, for example by means of bonding wires  220 . 
     Alternatively, it would be conceivable that the excitation coil  40  is provided in the stator package  10 . Here, the excitation coil  40  could be formed by thin-film technology in at least one of the at least two metallization layers  11 ,  12 , or the excitation coil  40  could be formed by thin-film technology in at least one third metallization layer arranged on the substrate  20 . In this case, the excitation coil  40  could also be potted in the potting compound  23  and connected in an electrically conducting manner to the semiconductor chip  21  and be able to be induced by an alternating current to generate a magnetic field. 
     As can be seen in  FIG. 4 , the stator package  10  may be arranged on the component board  300  and optionally fixed on it. For example, the stator package  10  may be bonded on the component board  300 , adhesively attached or otherwise fastened on the component board  300 . The stator package  10  itself may therefore be configured without a circuit board. Optionally, for example if the excitation coil  40  should be provided in the external component board  300 , as shown in  FIG. 4 , the circuit board-less stator package  10  may be arranged on such an external circuit board (or component board)  300 . Nevertheless, the stator package  10  itself would in this case be formed without a circuit board. 
     The stator package  10  may be immovable or non-rotatable. By contrast, the rotor package  100  may be movable or rotatable and rotate in relation to the non-rotatable stator package  10 . For this purpose, the rotor package  100  may be arranged on an end portion of a rotatable shaft  200 . For example, the rotor package  100  may be mounted on the end of the shaft  200  by means of an adhesive  28 . The rotor package  100  can consequently rotate together with the rotatable shaft  200 . In this case, the rotor package  100  and the stator package  10  may be spaced apart from one another, so that they cannot touch. That is to say that between the stator package  10  and the rotor package  100  there is an axial air gap  29 , which prevents unwanted direct contact between the stator package  10  and the rotor package  100 . 
       FIG. 5  shows an exemplary embodiment of an inductive angle sensor  1000  according to the through-shaft principle. The rotatable shaft  200  may extend both through the stator package  10  and through the rotor package  100  and also optionally through the component board  300 . In this case, the component board  300 , including the excitation coil  40  provided therein, may in each case comprise a through-opening  25 , through which the rotatable shaft  200  extends. 
     The through-opening  25  may have a slightly greater diameter than the rotatable shaft  200 , so that the shaft  200  can rotate within the through-opening  25 . That is to say that the stator package  10  and the component board  300  may have between the shaft  200  and the through-opening a radial air gap  27 , which prevents direct contact between the shaft  200  and the stator package  10  or between the shaft  200  and the component board  300 . 
     The rotor package  100  may also have a through-opening  25 , the diameter of which may be slightly greater than the diameter of the shaft  200 . The rotor package  100  may be mounted on the shaft  200  for conjoint rotation. For example, the rotor package  100  may be adhesively attached onto the shaft  200  by means of an adhesive  26 . Consequently, the rotor package  100  rotates together with the shaft  200 , while the shaft  200  rotates in the stationary stator package  10 . 
     The stator package  10  and the rotor package  100  are preferably always contactless. Furthermore, the stator package  10  may advantageously be aligned such that it is centered in relation to the axis of rotation  121  of the rotatable shaft  120 . In the end-of-shaft configuration ( FIG. 4 ), the rotor package  100  may be adhesively attached on the end face of a shaft end and the stator package  10  may be arranged ahead of it at an axial distance of approximately 1 mm to 2 mm. In the through-shaft configuration ( FIG. 5 ), the shaft  120  may for example be “infinitely long”, i.e. the shaft end is not available for the angle sensor  100 . Then, the rotor package  100  and the stator package  10  could both have a hole  25 , through which the shaft  120  runs. The rotor package  100  may be ring-shaped and fixed on the shaft  120 . The stator package  10  may likewise be ring-shaped and arranged away from the rotor package  100  by a distance of 1 mm to 2 mm. 
       FIG. 6  shows a schematic block diagram to show a method for producing a stator package  10  described here. 
     In step  601 , a substrate  20  is provided and at least two metallization layers  11 ,  12  arranged at different levels are arranged on the substrate  20 . 
     In step  602 , a receiving coil arrangement  30  with at least two electrically conductive receiving coils  31 ,  32  is produced, designed to receive a magnetic field emitted by an inductive target arrangement  130  that is rotatable in relation to the stator package  10  and to generate induction signals in response thereto. 
     In step  603 , a semiconductor chip  21  is arranged on or alongside the substrate  20  and the semiconductor chip  21  is brought into electrical contact with the receiving coil arrangement  30 , wherein the semiconductor chip  21  comprises a circuit which is designed to evaluate the induction signals and to ascertain on the basis of the induction signals a rotation angle between the receiving coils  31 ,  32  and the inductive target arrangement  130  rotatable in relation thereto. 
     In step  604 , an electrically insulating potting compound  23  is applied, so that it surrounds the substrate  20  including the semiconductor chip  21  and the receiving coils  31 ,  32 . 
     According to the innovative concept described here, the two receiving coils  31 ,  32  are implemented in the two metallization layers  11 ,  12  by thin-film technology when producing the stator package  10 . 
       FIG. 7  shows a schematic block diagram to show a method for producing a rotor package  100  described here. 
     In step  701 , a substrate  120  is provided and at least one metallization layer  111  is arranged on the substrate  120 . 
     In step  702 , an inductive target arrangement  130  with at least one electrically conductive inductive target  131  is produced, designed to generate an induction current in response to a magnetic field emitted by an excitation coil  40  and to generate a magnetic field corresponding to the induction current and to emit it in the direction of the stator package  10 . In this case, the at least one inductive target  131  of the target arrangement  130  is implemented in the at least one metallization layer  111 . 
     In step  703 , an electrically insulating sealing or potting compound  123  is applied, so that it surrounds the substrate  120  including the target arrangement  130 . 
     In step  704 , the rotor package  100  is arranged on a rotatable shaft  200  for conjoint rotation, so that the rotor package  100  is rotatable in relation to the stator package  10 . 
     The innovative concept described here is to be summarized once again below in other words and its advantages specified. 
     One aim of the concept described here is to produce a stator package  10  with a size of approximately 5 mm to 15 mm, preferably of less than 10 mm, which comprises a chip  21  with a circuit and receiving coils  31 ,  32  (and optionally also with an excitation coil  40 ). Another aim of the concept described here is to produce a rotor package  100  with a size of approximately 5 mm to 15 mm, preferably of less than 10 mm, which comprises a target arrangement  130  with one or more inductive targets  131 . The inductive target  131  may be for example a simple conducting component or a planar coil within each case n-fold symmetry (with n&gt;1, i.e. with at least two radial projections with 360°/n symmetry). 
     No high currents are induced in the receiving coils  31 ,  32 . For this reason, the receiving coils  31 ,  32  can have very small line dimensions without making any significant sacrifices in terms of signal quality. Only the impedance may slightly suffer as a result. However, this can be counteracted by the effective bandwidth of the sensor. Parasitic effects such as leakage currents, electrostatic discharges and inductances at the coils or at the connections between the coils and the semiconductor chip are less critical. 
     The production of the coils  31 ,  32  by thin-film technology allows the high-precision production process of the receiving coils  31 ,  32  to be kept fully under control. The application of thin-film technology allows better control over the purity of the materials to be used and the process parameters, which in turn leads to increased reliability in the production of the coils  31 ,  32  in comparison with conventional PCB technologies. An end-of-line test can be carried out on the complete subsystem comprising the chip  21  and the receiving coils  31 ,  32 . In addition, the coils  31 ,  32  can be surrounded by the potting compound  23 , which reliably protects the coils  31 ,  32  from external influences. For these reasons, the coils  31 ,  32  do not require resistances in order to carry out integrity checks while operation is in progress, which in turn increases the accuracy and reduces the production costs. The individual metallization layers  11 ,  12  are aligned better in relation to one another than in PCB technology. The more exact geometry of the coils  31 ,  32  improves the accuracy and reduces process variation. The smaller overall size of the stator package  10  reduces the inductances as a whole. 
     The coils  31 ,  32  may be arranged on one and the same side of the substrate  20  and can be stacked one above the other. This leads to highly precise alignment. The stator package  10  may be arranged in such a way that the coils  31 ,  32  provided in it face in the direction of the rotor package  100 , or that the coils  31 ,  32  face away from the rotor package  100 . The last-mentioned arrangement does increase the vertical distance between the receiving coils  31 ,  32  in the stator package  10  and the target arrangement in the rotor package  100 . However, as a result the dependability and robustness of the angle sensor  1000  can be increased, since the risk of collision is reduced. 
     In the case of PCBs, an increased number of metallization layers leads to splaying of the substrate. This is not the case in the concept described here, for which reason the provision of a much greater number of metallization layers is conceivable. Consequently, for example, redundant coils and electrostatic shields could be produced, which would be much more difficult to put into practice in PCB technology. 
     In spite of the relatively small size of the receiving coils  31 ,  32 , with an outside diameter of for example 12 mm, it is possible to provide a hole  25  with a diameter of approximately 2 mm to 4 mm, through which a rotatable shaft  200  can be led. Even if the coils  31 ,  32  are produced on a silicon substrate  20 , such a hole  25  could be made in the silicon. In this respect, it would be advantageous to produce the silicon substrate  20  thinner than usual. The starting thickness of a wafer is approximately 750 μm, and the wafer is often thinned back to 220 μm. In order to produce the hole  25  mentioned at the beginning, it would be conceivable to thin back the substrate 20 to 50 μm. This would allow a passing-through shaft  200  with a diameter of approximately 2-3 mm to be received. 
     If the substrate  20  is a silicon substrate, it can be produced in an inexpensive semiconductor process, wherein for example only two metallization layers  11 ,  12  are applied to a raw wafer with a coarse resolution of for example approximately 1 μm to approximately 2 μm and an insulating layer  13  arranged in between and also optionally a final passivation layer. This would be much less expensive than usual, expensive semiconductor processes with a resolution of 125 nm, in which around 20 to 35 layers are applied for the circuit. 
     For the reasons stated further above, it may be advantageous for the production of receiving coils  31 ,  32  with an outside diameter of less than 15 mm to apply a production technology that is more intricate than PCB technology. The production of the receiving coils  31 ,  32  by thin-film technology that is described here may for example envisage using for example the metal layers in the redistribution layer of a wafer level package, for example of an (e)WLB package, or else applying microelectronic production techniques, wherein the receiving coils  31 ,  32  are for example produced in the metallization layers of inorganic substrates, such as for example glass, ceramic or silicon, for example by the same techniques as for producing connections in microelectronic circuits. Both technologies allow lines and vias in the size range of 10 μm or less (in comparison with vias over 100 μm thick in the case of PCB technology). 
     The previously mentioned (e)WLB packages are susceptible to mechanical stress exerted on the solder balls, in particular if the package is larger than 15×15 mm and the temperature profile is challenging. In such a case, it would be conceivable to lead electrical connections only to a few solder balls in a small region, i.e. other solder balls would nevertheless continue to be present but could then only serve for mechanical support, i.e. they would not be used for electrical contacts and could also not be soldered on solder points on a component board  300  (they would only be present to prevent tilting of the stator package  10  before soldering on). 
     The excitation coil  40  could also be provided within the stator package  10 , for example on the same substrate  20  (for example a silicon substrate in the case of (e)WLB packages) as the receiving coils  31 ,  32 . The production of the excitation coil  40  is less tricky. Often, just a few turns of wire around the receiving coils  31 ,  32  are sufficient for this. Furthermore, the wire of the excitation coil  40  is usually thicker than the wire of the receiving coils  31 ,  32 . It is therefore possible to implement the excitation coil  40  (or else multiple excitation coils) on the component board  300 , on which the stator package  10  can also be arranged (see  FIGS. 4 and 5 ). This offers the advantage of an easy kind of implementation. On the other hand, it may be advantageous to integrate the excitation coil(s)  40  into the stator package  10 . This offers the advantage of fewer statistical outliers with respect to (capacitive and/or inductive) cross coupling between the excitation coil  40  and the receiving coils  31 ,  32  and offers the possibility of increasing the reliability of the process in the production of the excitation coil  40 . 
     It would also be conceivable to add further discrete electronic components to the stator package  10 . For example, the inductive angle sensor  1000  may be extended by adding a capacitor, in order to operate the excitation coil  40  in a resonating manner. It would in this case for example be less expensive to integrate the capacitor into the stator package  10  (for example into an (e)WLB package). If the inductive target  130  were designed as a coil, a series capacitance could be added, in order to operate the target  130  in a resonating manner. If the receiving coils  31 ,  32  have n-fold symmetry, it would be advantageous if the target  130  also had the same n-fold symmetry. 
     As mentioned further above, the rotor package  100  may have essentially the form of a pill. The approximately pill-shaped rotor package  100  may have a diameter of approximately 6 mm bis 12 mm and be fixed on the rotatable shaft  200 . 
     With the concept described here, various types of inductive angle sensors  1000  can be produced. The at least two receiving coils  31 ,  32  may be designed for two-phase angle sensors  1000  for example as sine and cosine coils. In the case of three-phase angle sensors  1000 , at least three receiving coils  31 ,  32  may be provided, for example u-, v- and w coils. For example, it is also possible for multiple receiving coil arrangements each with two or more receiving coils to be provided. For example, the stator package  10  may comprise two receiving coil arrangements, wherein the receiving coils of a first receiving coil arrangement may have n-fold symmetry and the receiving coils of a second receiving coil arrangement may have m-fold symmetry, for example with n=1, m&gt;&gt;1, (for example 11), or with n&gt;&gt;1 (for example 11) and m=n+1. A combination of the signals of the two receiving coil arrangements can produce an angle measurement result that is definite over an angular rotation of the full 360°. By contrast with this, angle sensors  1000  with a single receiving coil arrangement with n-fold symmetry can produce angle measurement results that are definite at least over 360°/n. However, it is also possible for reasons of redundancy to revert to two receiving coil arrangements. 
     Both the substrate  20  in the stator package  10  and the substrate  120  in the rotor package  100  may be for example a glass substrate with a thickness of 500 μm to 750 μm (for example Borofloat). The metallization layers  11 ,  12  may for example be applied to the substrate  20  by means of titanium metallization and be structured by means of radio-frequency etching. Oxide or nitride insulating layers may be arranged between the metallization layers  11 ,  12 . In the rotor substrate  120 , a target arrangement  130  with one or two inductive targets may for example be implemented in two metallization layers. 
     The rotor package  100  may for example have an essentially round or oval form. The stator substrate  20  may preferably be rectangular and two or four receiving coils, and optionally one excitation coil, may be implemented in two or four metallization layers. 
     Depending on the embodiment (through-shaft or end-of-shaft), optionally a centrally arranged hole  25 , through which the rotatable shaft  200  can be led, may be provided in the stator package  10  and/or the rotor package  100 . The semiconductor chip  21  may be arranged on the stator substrate  20  and be electrically connected to the receiving coils, and also to the excitation coil. Both the stator package  10  and the rotor package  100  may in each case be potted by means of a potting compound  23 ,  123 . On those sides of the packages  10 ,  100  that lie opposite during operation, corresponding markings may be provided on the potting compound. 
     The exemplary embodiments described above merely represent an illustration of the principles of the present concept. It goes without saying that modifications and variations of the arrangements and details described here will be apparent to others skilled in the art. It is therefore intended that the concept described here should only be restricted by the scope of protection of the following patent claims and not by the specific details that have been presented here on the basis of the description and the explanation of the exemplary embodiments. 
     Although some aspects have been described in connection with a device, it goes without saying that these aspects also represent a description of the corresponding method, so that a block or a component of a device can also be understood as meaning a corresponding method step or a feature of a method step. By analogy, aspects which have been described in connection with a method step or as a method step also represent a description of a corresponding block or detail or feature of a corresponding device.