Electronic module

Abstract

The electronic module comprises a MEMS switch (60, 70, 80, 90) formed by layers less than 100 micrometers thick on at least one substrate and a load current path (100), as well as a magnetic field sensor device (120, 180) formed by layers less than 100 micrometers thick. The magnetic field sensor device (120, 180) in the electronic module is arranged to detect an electrical load current (IA) flowing through the load current path (100) of the MEMS switch.

Description

[0001] The invention relates to an electronic module. DE 199 27 762 A2 discloses an electronic module comprising a MEMS switch formed on at least one substrate with a load current path and a magnetic field sensor device, in which the magnetic field sensor device is arranged to detect an electrical load current of the MEMS switch flowing through the load current path. US 5 070 317 A discloses an electromagnetic device comprising a semiconductor substrate with one or more electrical circuits integrally defined therein, a magnetic shielding layer over the substrate, a first layer of spaced-apart conductive strips over the shielding layer, a magnetic core layer superimposed on the first layer of conductive strips and patterned to define first and second transverse magnetic paths, a second layer of spaced-apart conductive strips,which is superimposed on the magnetic core layer, wherein portions of the conductive strips of the second layer are connected to portions of the conductive strips of the first layer to form first and second substantially spiral electrical paths, each spiraling around at least a portion of the magnetic core layer for generating or detecting magnetic flux in that one portion of the magnetic core layer, said portion of the magnetic core layer comprising at least one of the first and second transverse magnetic paths, and wherein the magnetic shielding layer shields one or more of the electrical circuits from the flux generated or detected by the first and second spiral electrical paths.

[0002] It is common practice to design electronic modules with power switches. Power switches typically provide simple switching functions.

[0003] It is also known to use electronic modules with current switches in industrial control devices or motor starters.

[0004] However, there is often a need to be able to monitor the current flowing through the current switch. This is particularly necessary to protect the switch itself. There is also a need to protect a load from overcurrent or to detect wear on the current switch and the associated increased contact resistance.

[0005] In principle, such functionalities can be incorporated into industrial control devices or motor starters. However, this requires more space, for example, for ferrite toroidal cores for current measuring devices or for Rogowski coils or shunts. Furthermore, shunt current meters often suffer from resistance losses and parasitic inductances. Another problem with the use of shunts is that the control and load circuits cannot be easily galvanically isolated. Furthermore, the additional functionalities require more components, which further increases costs.

[0006] It is therefore an object of the invention to provide an improved electronic module that preferably reduces and overcomes the aforementioned disadvantages. It is also an object of the invention to provide an improved control device and an improved motor starter that is improved over the prior art, preferably with regard to the aforementioned disadvantages.

[0007] This object of the invention is achieved with an electronic module having the features specified in claim 1 and with a control device and a motor starter having the features specified in claim 13. Preferred developments of the invention are specified in the associated subclaims, the following description, and the drawing.

[0008] The electronic module according to the invention comprises a MEMS switch with a load current path formed by at least one layer with a thickness of less than 100 micrometers on at least one substrate, and a magnetic field sensor device formed by at least one layer with a thickness of less than 100 micrometers. In the electronic module according to the invention, the magnetic field sensor device is arranged to detect an electrical current of the MEMS switch flowing through the load current path.

[0009] Advantageously, the electronic module according to the invention with an ammeter in the form of a magnetic field sensor device can be manufactured directly using a layer with a thickness of less than 100 micrometers. In particular, the electronic module with the magnetic field sensor device can be manufactured using MEMS technology (MEMS = "Micro-Electro-Mechanical Systems"), so that the MEMS switch and magnetic field sensor device can be manufactured in an integrated manner using the same process technology and preferably with at least partially identical manufacturing steps. Consequently, the electronic module according to the invention can be manufactured with fewer process steps, since process steps can be performed simultaneously for both the MEMS switch and the magnetic field sensor device. The electronic module according to the invention can therefore be manufactured more cost-effectively and quickly.

[0010] Using the magnetic field sensor device, the magnetic field of a load current flowing through the load circuit can be measured contactlessly due to the resulting Lorentz force. The Lorentz force results in a voltage in the form of a magnetic field voltage that can be measured in a conventional manner. This voltage is proportional to the load current and thus allows a direct conclusion to be drawn about the magnitude of the load current.

[0011] In a further development of the electronic module according to the invention, the MEMS switch is expediently designed with a bending element, preferably with a bending beam. Bending elements such as bending beams can advantageously be manufactured using layers with a thickness of less than 100 micrometers. In this further development of the invention, the electronic module according to the invention can therefore be manufactured particularly simply, with a reduced number of manufacturing steps, and at a low cost.

[0012] Advantageously, the load current of the MEMS switch can be measured in a galvanically isolated manner using the magnetic field sensor device. Since the load current is detected according to the invention using the magnetic field generated by the load current, an electrically conductive connection of an ammeter is unnecessary in the electronic module according to the invention.

[0013] Advantageously, in the electronic module according to the invention, wear of the MEMS switch can be detected by an increase in resistance losses and, consequently, by a corresponding change in current. Thus, the service life of the electronic module according to the invention can be reliably estimated using the magnetic field sensor device.

[0014] Another advantage is that the electronic module can be manufactured in a spatially compact and cost-effective manner thanks to the ability to manufacture layers less than 100 micrometers thick, preferably using MEMS technology. Additional components do not need to be specifically provided for the electronic module according to the invention.

[0015] Preferably, in the electronic module according to the invention, the at least one or more layers have a thickness of less than 50 micrometers. In particular, MEMS technology can be advantageously used in this development, in particular the deposition of thin layers by sputtering, vapor deposition, or electroplating, or the structuring of layers with a thickness of less than 50 micrometers by photolithography.

[0016] In the electronic module according to the invention, the magnetic field sensor device is formed on the substrate on which the MEMS switch is formed. When arranged jointly on the same substrate, at least parts of the MEMS switch and parts of the magnetic field sensor device can be manufactured in parallel in one and the same manufacturing step.

[0017] In the electronic module according to the invention, the magnetic field sensor device preferably comprises at least one magnetic field sensor element, which is / are arranged and aligned obliquely, preferably transversely, in particular perpendicularly, to a magnetic field excited by a current flowing through the load current path. In this orientation, the magnetic field sensor element is particularly sensitive to exciting a magnetic field voltage and thus particularly sensitive to current measurement.

[0018] In a preferred development of the electronic module according to the invention, the magnetic field sensor element is a Hall sensor element or a magnetoresistive sensor element.

[0019] In the electronic module according to the invention, the magnetic field sensor element and / or the load current path is / are formed with semiconductor material, in particular silicon, and / or with an electrical conductor, preferably metal. In an advantageous development of the electronic module according to the invention, the load current path is routed at least partially around the magnetic field sensor element. In this development of the invention, as a result of the at least partial circumferential routing of the load current path, the magnetic field can be efficiently concentrated at the location of the magnetic field sensor element, so that a particularly precise current measurement is possible with this arrangement of the load current path and the magnetic field sensor element.

[0020] In the electronic module according to the invention, the magnetic field sensor device preferably has at least one magnetic flux density concentrator, which concentrates the flux density at the location of the magnetic field sensor element. By concentrating the flux density at the location of the magnetic field sensor element, a particularly precise current measurement can be performed in the electronic module according to the invention.

[0021] In the electronic module according to the invention, the flux density concentrator preferably surrounds the load current path at least partially. In this embodiment of the invention, the magnetic field is concentrated along a portion of the circumference, preferably along a predominant portion of the circumference, thus further increasing the accuracy of the current measurement.

[0022] In the electronic module according to the invention, the at least one layer comprises, in expedient developments, at least one sputter layer and / or vapor-deposited layer and / or electroplating layer and / or adhesive layer and / or laminate layer.

[0023] In the electronic module according to the invention, the layer preferably comprises a ferromagnetic metal, in particular iron and / or cobalt and / or nickel and / or alloys of one or more of the aforementioned metals, and / or semiconductor material, preferably silicon, and / or insulating material, preferably glass.

[0024] In a preferred embodiment of the invention, the at least one layer in the electronic module comprises at least one structured layer, preferably a silicon-on-insulator substrate. Silicon-on-insulator substrates advantageously already have silicon layers with a thickness of less than 50 micrometers. In this embodiment, layers can therefore be provided by structuring the silicon-on-insulator substrate, in particular by photolithography, so that the electronic module according to the invention can be manufactured particularly easily, efficiently, and cost-effectively.

[0025] Preferably, the electronic module according to the invention comprises an evaluation device for evaluating a magnetic field voltage of the Hall sensor element, preferably for determining a load current value. In this way, the electronic module can provide the current measurement of the load current without the need for additional components.

[0026] The invention is explained in more detail below using exemplary embodiments illustrated in the drawings. They show: Fig. 1 shows an electronic module according to the invention with a MEMS switch with a load current path and a Hall sensor device with a Hall sensor element schematically in a plan view, Fig. 2 shows the electronic module according to the invention according to Fig. 1 schematically in cross section, Fig. 3 a further electronic module according to the invention with a MEMS switch with a load current path and a Hall sensor device with a Hall sensor element, in which the load current path is partially guided around the Hall sensor element, schematically in a top view, Fig. 4 a further electronic module according to the invention with two substrates with a MEMS switch with a load current path and a Hall sensor device with a Hall sensor element and a magnetic flux density concentrator, schematically in cross section, Fig. 5 a further electronic module according to the invention with two substrates with a MEMS switch with a load current path and a Hall sensor device with a Hall sensor element and a magnetic flux density concentrator, which is guided approximately a quarter of the circumference around the load current path, schematically in cross section, Fig.6 shows a further electronic module according to the invention with two substrates, comprising a MEMS switch with a load current path and a Hall sensor device with a Hall sensor element and a magnetic flux density concentrator, which is guided approximately halfway around the load current path, schematically in cross section. Fig. 7 shows a further electronic module according to the invention with two substrates, comprising a MEMS switch with a load current path and a Hall sensor device with two Hall sensor elements and a magnetic flux density concentrator, which is guided approximately halfway around the load current path, schematically in cross section. Fig. 8 shows a further electronic module according to the invention with two substrates, comprising a MEMS switch with a load current path and a Hall sensor device with two Hall sensor elements and a magnetic flux density concentrator, which is guided almost completely around the load current path, schematically in cross section.9A further electronic module according to the invention with two substrates with a MEMS switch with a load current path and a Hall sensor device with two Hall sensor elements and a magnetic flux density concentrator, which is guided almost completely around the load current path, schematically in cross section. .

[0027] The Fig. 1 The electronic module 10 shown has two substrates 20, 30 (in the Figuren 1 bis 3 not explicitly shown), which are bonded to one another in a planar manner and which have spaced-apart, facing, and parallel planar surfaces on which the elements described below are arranged, unless expressly stated otherwise. The first substrate 20 has a planar silicon surface 40, while the second substrate 30 is made of glass and has a glass surface 50 which is parallel and planar and spaced apart by less than 100 micrometers, in the illustrated embodiment by 50 micrometers. The glass surface 50 is formed and spaced apart in such a way that the second substrate 30 is made entirely of glass and has a recess in the form of a trench with a rectangular profile, the bottom of which forms the glass surface 50. In principle, the profile of the trench does not have to be rectangular, but can also have rounded corners.In further embodiments not specifically shown, the second substrate 30 may also consist of other materials, for example silicon, and may have another surface, such as a second silicon surface 50, instead of a glass surface 50.

[0028] The electronics module 10 has a MEMS switch 15, which has a bending element in the form of a bending beam 60. The bending beam 60 is hinged to the silicon surface 40 of the first substrate 20 and has a free end provided with an electrically conductive metallization 70. With this metallization 70, in a deflected position, it can bridge two spaced-apart switching contacts 80, 90 of a load current path 100. In its deflected position, the bending beam 60 rests against the two switching contacts 80, 90 with its metallization 70, so that the bending beam 60 can switch an electrical current. The bending beam 10 can be controlled with an electrical control voltage, which electrostatically applies force to the bending beam 10 to deflect it into the deflected position.The control voltage is applied via two electrodes G+, G-, with one electrode G+ being in contact with the flexural beam 60 and one electrode G- being in contact with the substrate to which the flexural beam 10 is hinged. In this way, by applying voltage to the electrodes G+, G-, the flexural beam 60 can be moved into its deflected position. The MEMS switch 15 thus comprises the flexural beam 60 with the metallization 70, the switching contacts 80, 90, and the electrodes G+, G-.

[0029] The switching contacts 80, 90 are spaced apart in a direction perpendicular to the longitudinal extent of the flexural beam 60 and parallel to the silicon surface 40. The load current path 100 is formed with electrically conductive metal tracks S, D, which are electrically conductively connected to the switching contacts 80, 90 and which extend in a direction perpendicular to the longitudinal extent of the flexural beam 60 and parallel to the silicon surface 40. In addition, the load current path 100 comprises the switching contacts themselves as well as the metallization 70 of the free end of the flexural beam 60. A load current IA now flows from one metal track D of the metal tracks S, D via the switching contacts 80, 90 and the metallization 70 of the free end of the flexural beam 60 to the other metal track S of the metal tracks S, D.

[0030] If the load current IA flows from one D of the metal tracks S, D to the other S of the metal tracks S, D, then a voltage is formed around the metal tracks S, D, in Fig. 1 As shown by way of example using the metal track D, a magnetic field whose magnetic field lines 110 circumferentially and annularly surround the direction of travel of the metal track D. At locations on the surface of the first substrate 20, to which the bending beam 60 is hinged, the magnetic field lines 110 are oriented essentially along a plane perpendicular to the silicon surface 40 and parallel to the longitudinal extent of the bending beam 60.

[0031] The electronic module 10 also comprises, on a surface of the first substrate 20 parallel to the silicon surface 40, a magnetic field sensor element in the form of a Hall sensor element, which is implemented as a, for example, square, silicon sensor layer 120 on the first substrate 20. In the illustrated embodiment, the silicon sensor layer 120 is implemented by exposing a silicon cover layer 130 of the first substrate 20, which forms a silicon-on-insulator substrate 135. The silicon-on-insulator substrate 135 consists of a silicon substrate 140 with a thickness of several hundred micrometers and a silicon dioxide layer 150 applied flatly thereon with a thickness of less than 20 micrometers, approximately 2 micrometers in the illustrated embodiment, and the silicon cover layer 130 deposited thereon with a thickness of less than 50 micrometers, 20 micrometers in the illustrated embodiment.

[0032] The square silicon sensor layer 120 is exposed from the silicon cover layer 130 by photolithography in such a way that a square frame is removed around the square silicon sensor layer 120, from the surface of the silicon cover layer 130 to the silicon dioxide layer 150 of the silicon-on-insulator substrate. This means that the square silicon sensor layer 120 is separated from the remaining silicon cover layer 130 by a surrounding trench 175, which is square in this case. The square silicon sensor layer 120 is then electrically contacted by means of layered conductor tracks 180, wherein the conductor tracks 180 lead along the surface of the silicon cover layer 130 and along the surfaces of the trench 170 perpendicular to the course of the trench 170 to the silicon sensor layer 120 and end at or on the silicon sensor layer 120.

[0033] The bending beam 60 is also formed by exposing a portion of the silicon cover layer 130. A portion of the silicon cover layer 130 is exposed by removing an adjacent portion of the silicon cover layer 130 and a portion of the silicon dioxide layer 150, so that the exposed portion of the silicon cover layer 130 forms a free end. Alternatively, in further embodiments not specifically illustrated, the silicon sensor layer 120 and the bending beam 60 can be applied as a sputter layer, a vapor deposition layer, an adhesive layer, or a laminate layer.

[0034] The conductor tracks 180 and the metal tracks S, D are each applied as a vapor-deposited layer. In further exemplary embodiments not specifically shown, the conductor tracks 180 and the metal tracks S, D can also be applied as a galvanic layer and / or adhesive layer and / or laminate layer. The conductor tracks 180 and the metal tracks S, D and the bending beam 60 as well as the silicon sensor layer 120 each have a thickness of less than 50 micrometers in the direction perpendicular to the glass surface 50 or the silicon surface 40, and in the exemplary embodiment shown, a thickness of at most 20 micrometers each. The conductor tracks 180 have a thickness of 5 micrometers; the load current path and the silicon sensor layer 120 as well as the bending beam 60 each have a thickness of 20 micrometers. The conductor tracks 180 can also have other thicknesses in further exemplary embodiments not specifically shown.

[0035] Two of the conductor tracks 180 each lead toward one of two mutually parallel sides of the square silicon sensor layer 120 and serve to apply supply voltages UB+, UB-. Two further conductor tracks 180 each lead toward one of the remaining sides of the square silicon sensor layer 120 and function as signal voltage contacts for detecting the Hall voltages UH+, UH-.

[0036] The magnetic field lines 110 due to the load current IA pass through the load current path 100 as shown in Fig. 2 The surface of the silicon sensor layer 120 is almost vertical, so that the silicon sensor layer 120 is almost maximally sensitive to the load current IA through the load current path 100. In Fig. 1 In the illustrated embodiment, the load current path 100 passes along a straight line G past the silicon sensor layer 120. In a further embodiment, Fig. 3 In the embodiment shown, however, the load current path 100 bends from the straight line G and follows a U-shaped course U around the silicon sensor layer 120 before the load current path 100 leads back to the straight line G.

[0037] The Fig. 4 The further embodiment shown essentially corresponds to the previously shown embodiment, but differs from it in that in addition to the silicon sensor layer 120, a field line concentrator in the form of an iron yoke 190 is present. Fig. 4 In the illustrated embodiment, the iron yoke 190 is designed as an iron cuboid which, in the plane parallel to the silicon surface 40 on which the silicon sensor layer 120 is arranged, has a square cross-section which, for example, has an edge length approximately 5 percent larger than the square cross-section of the silicon sensor layer 120. The iron yoke 190 is arranged on the second substrate 30 on the glass surface 50 in such a way that the iron yoke 190 and the silicon sensor layer 120, viewed in the direction perpendicular to the glass surface 50 and thus also to the silicon surface 40, overlap, for example, in such a way that the intersection point of the diagonals of the square cross-sections of the iron yoke 190 and the silicon sensor layer 120 coincide. In this development, the magnetic field lines 110 are therefore concentrated at the location of the silicon sensor layer 120.

[0038] The Fig. 5 The embodiment shown corresponds to the one in Fig. 4 The embodiment shown differs, however, in the design of the iron yoke 190: This is not merely designed as an iron cuboid, but also includes an iron web 200, which extends from the iron cuboid, viewed in a direction perpendicular to the glass surface 50 and the silicon surface 40, to the load current path 100. For this purpose, the iron web 200 extends along the glass surface 50. In this further development, an even larger portion of the magnetic field lines 110 is concentrated at the location of the silicon sensor layer 120.

[0039] The Fig. 6 The embodiment shown corresponds to the one in Fig. 5 shown embodiment, but differs again in the design of the iron yoke 190: This is in Fig. 6 with an even longer iron web 200, which continues mirror-symmetrically when reflected on a plane that extends perpendicular to the longitudinal extent of the bending beam 60 and perpendicular to the glass surface 50 and thus also perpendicular to the silicon surface 40 and which extends centrally through the load current path 100. In addition, in Fig. 6 In the illustrated embodiment, the iron cuboid of the yoke 190 is also present twice in mirror symmetry. In this further development, the portion of the magnetic field lines 110 that is concentrated at the location of the silicon sensor layer 120 is further increased.

[0040] The Fig. 7 The embodiment shown corresponds to the one in Fig. 6 Deviating from the embodiment shown in Fig. 6 However, a further silicon sensor layer 120 is also present in a mirror image, ie, mirrored on a plane that extends perpendicular to the longitudinal extent of the bending beam 60 and perpendicular to the glass surface 50, and thus also perpendicular to the silicon surface 40, and which extends centrally through the load current path 100. Consequently, in this exemplary embodiment, the measurement accuracy of the load current IA is further increased.

[0041] In Fig. 8 In the illustrated embodiment, a second iron bar 210 is arranged, which is arranged on a side of the first substrate facing away from the silicon surface 40 and which extends with its longitudinal extent, ie with its longest extent, parallel to the iron bar 200. In this embodiment, the magnetic field lines are therefore concentrated almost entirely around the load current path 100.

[0042] In the Fig. 9In the illustrated embodiment, the web 200 is not arranged on the glass surface 50, but rather on a side of the second substrate 30 facing away from the glass surface 50. In principle, the field line concentrators 190, 200, 210 can be arranged flexibly to concentrate the magnetic field lines 110.

[0043] A control unit according to the invention, not specifically shown in the drawing, comprises one or more electronic modules 10 according to the invention, as described above. A motor starter according to the invention, not specifically shown, comprises one or more electronic modules 10 according to the invention, as described above.

[0044] In further embodiments not specifically shown, instead of a Hall sensor element in the form of a silicon sensor layer 120, another magnetic field sensor element, such as a magnetoresistive sensor, may also be present.

Claims

1. Electronics module (10), comprising a MEMS switch (15) formed by means of layers with a thickness of less than 100 micrometres on at least one substrate (20) and having a load current path (100) and also a magnetic field sensor device (120, 180) formed by means of layers with a thickness of less than 100 micrometres, in which electronics module the magnetic field sensor device (120, 180) is arranged for detecting an electric load current (IA) of the MEMS switch (15) flowing through the load current path (100), characterized in that the magnetic field sensor device (120, 180) is formed on a top side of the substrate (20) on which the MEMS switch (15) is formed, in which electronics module the electronics module (10) has an additional substrate (30) and the load current path (100) is formed on a top side of the additional substrate (30), wherein the substrate (20) and the additional substrate (30) are bonded to each other surface-to-surface by way of their top sides, wherein the additional substrate (30) has a recess on its top side, and wherein the magnetic field sensor device (120, 180) is arranged beneath the recess and the load current path (100) is arranged at the bottom of the recess.

2. Electronics module (10) according to the preceding claim, in which the layers have a thickness of less than 50 micrometres.

3. Electronics module (10) according to either of the preceding claims, in which the magnetic field sensor device (120, 180) comprises at least one magnetic field sensor element (120) which is or are arranged and oriented obliquely, preferably transversely, in particular perpendicularly, to a magnetic field (110) excited by a load current flowing through the load current path (100).

4. Electronics module (10) according to any of the preceding claims, in which the magnetic field sensor element (120) is a Hall sensor element or a magnetoresistive sensor element.

5. Electronics module (10) according to Claim 4, in which the magnetic field sensor element (120) and / or the load current path (100) are / is formed with semiconductor material, in particular with silicon, and / or with an electrical conductor, preferably a metal.

6. Electronics module (10) according to one of the two preceding claims, in which the load current path (100) is guided at least partially circumferentially around the magnetic field sensor element (120).

7. Electronics module (10) according to any of the preceding claims, in which the magnetic field sensor device (120, 180) has at least one magnetic flux density concentrator (190) within the recess, the magnetic flux density concentrator concentrating the flux density at the site of the magnetic field sensor element (120).

8. Electronics module (10) according to the preceding claim, in which the flux density concentrator (190) at least partially circumferentially surrounds the load current path (100).

9. Electronics module (10) according to any of the preceding claims, in which the at least one layer has at least one sputtering layer and / or vapour-deposited layer and / or electroplating layer and / or adhesive layer and / or laminate layer.

10. Electronics module (10) according to any of the preceding claims, in which the layer contains ferromagnetic metal, in particular iron and / or nickel and / or cobalt and / or alloys of one or more of the abovementioned metals and / or iron alloys and / or iron-nickel alloys, and / or semiconductor material, preferably silicon, and / or insulating material, preferably glass.

11. Electronics module (10) according to any of the preceding claims, in which the at least one layer has at least one structured layer (130), preferably a silicone-on-insulator substrate (135).

12. Electronics module (10) according to any of the preceding claims, having an evaluation device for evaluating a magnetic field voltage (UH+, UH-) of the magnetic field sensor element.

13. Control device and / or motor starter, having one or more electronics modules (10) according to any of the preceding claims.

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