Inductor with grounded core on a printed circuit board

Abstract

device comprising an inductive component (2) with a ferromagnetic core (3), a printed circuit board (1) on which the inductive component (2) is soldered, and a contact element (7, 16) that is electrically connected to a potential of the circuit board (1) and that rests against the ferromagnetic core (3) in order to electrically contact the ferromagnetic core (3) and connect it to the potential, wherein a first end of the contact element (7, 16) engages at least in a recess (11) of the circuit board (1), a second end is bent out of the plane of the first end in such a way that the contact element (7, 16) in the area of ​​the second end rests resiliently against the ferromagnetic core (3) after the contact element (7, 16) has been inserted into the recess (11), and at least one hook (8, 18) is arranged at the first end of the contact element (7, 16), which fixes the contact element (7, 16) in the inserted state.

Description

[0001] The present invention relates to a device with an inductive component, such as a coil, a transmitter or transformer, which has a ferromagnetic core and is part of an electrical circuit on a printed circuit board (PCB).

[0002] In such a device, the terminals of the inductive components are soldered to the circuit board, whereas their cores often have no electrical connection to a circuit potential. This potential-free state (isolation) of the core can lead to unwanted electrical or electromagnetic effects, particularly at high frequencies, which can interfere with other components or impair electromagnetic compatibility. An additional terminal can be provided on the inductive component to connect the ferromagnetic core to a circuit potential. However, this leads to high manufacturing costs for the component if the terminal has to be attached to the core by hand.

[0003] The invention is based on the object of providing a device that mitigates the described problems without increasing production costs. In particular, the object is to provide a device and an operating device with which electromagnetic compatibility can be improved with a simple and cost-effective design.

[0004] This object is achieved according to the features of the independent claims. The invention is further developed by the features of the dependent claims.

[0005] According to the present invention, the device comprises an inductive component with a ferromagnetic core, a contact element for the ferromagnetic core, and a circuit board to which the inductive component is soldered. The contact element is electrically connected to a potential of the circuit board and bears against the ferromagnetic core in order to electrically contact the ferromagnetic core and connect it to the potential. The contact element is mechanically supported at least on the circuit board, with a first end of the contact element at least engaging into a recess in the circuit board and a second end being bent out of the plane of the first end such that the contact element, in the region of the second end, rests resiliently against the ferromagnetic core after the contact element has been inserted into the recess. At least one hook arranged on the first end of the contact element fixes the contact element in the inserted state.For this purpose, the hook or the second end can be inserted into the recess.

[0006] The contact element is not an integral part of the inductive component. It does not need to be soldered to the circuit board and can be installed after the inductive component has been connected to the circuit board.

[0007] This offers greater manufacturing flexibility, reduces manufacturing costs, and improves electromagnetic compatibility. The ferromagnetic core is electrically conductive at least at its surface / contact surface. It can be an iron or ferrite core.

[0008] The second end of the contact element can be supported on or contacted by the ferromagnetic core in a horizontal or vertical direction with respect to the circuit board.

[0009] The hook can be designed as an elastic element which engages behind the recess when inserted and automatically snaps back.

[0010] The first end of the contact element can be bent to form the hook. Alternatively, the hook is a tear-out at the first end that has been bent out.

[0011] Alternatively or additionally, at least one tear-out portion can be bent out on the contact element between the first and second ends. This tear-out portion rests vertically on the circuit board after insertion of the contact element and, with respect to the hook, comes to rest on the opposite side surface of the circuit board. Preferably, both the hook and the tear-out portion rest on the circuit board. In particular, at least the hook or the tear-out portion can rest resiliently against the circuit board after insertion, so that the circuit board is elastically clamped between the hook and the tear-out portion.

[0012] The contact element can electrically contact the circuit board in the recess and / or at another location. In particular, the contact element can electrically contact a tinned or non-tinned soldering surface of the circuit board or a tinned or non-tinned soldering pad of the circuit board that is electrically connected to the potential. Tinning the contact surface prevents poor electrical connections caused by corrosion.

[0013] The contact element can be formed from a drawn wire or a sheet metal stamping, whereby the recess can be circular or slot-like.

[0014] The device may have a metallic housing, wherein the contact element also rests resiliently against an inner side of the housing in order to also contact the housing or to electrically connect it to the potential of the circuit board.

[0015] According to the present invention, an operating device for lighting means comprises the device in one of the described embodiments.

[0016] The invention is explained in more detail below with reference to the accompanying drawings. They show: Fig. 1 a device with an inductive component and a contact element according to a first embodiment according to the present invention in a side view, Fig. 2 the contact element of the Fig. 1 shown device, Fig. 3 an area of Fig. 1 shown circuit board 1 in a view from below, Fig. 4 shows a device with an inductive component and a contact element according to a second embodiment of the present invention in a side view, Fig. 5 shows a device with an inductive component and a sheet metal stamping as a contact element according to a third embodiment of the present invention in a side view, and Fig. 6 that in Fig. 5 shows the sheet metal stamping in the unbent state in a pure top view.

[0017] Components with identical functions are identified by identical reference numerals in the figures. For the sake of a concise presentation of the invention, a repeated description of the corresponding elements is omitted.

[0018] Fig. 1 shows a simplified schematic representation of a printed circuit board 1 with an inductive component 2 according to the present invention in a side view. Fig. The inductive component 2 shown in Figure 1 comprises a ferromagnetic core 3, a coil former 4 with coil windings (not shown), and two electrical terminals 5, 6 that extend laterally from the coil former 4 and are electrically connected to the coil windings. The ferromagnetic core 3 may have a square shape when viewed from above.

[0019] The inductive component 2 is part of an electrical circuit (not shown) on the printed circuit board 1, wherein the electrical connections 5, 6 are soldered into solder pads provided for the connections 5, 6 on the printed circuit board 1. The electrical circuit or its components extend on the printed circuit board 1 in the area (horizontal plane) in the X and Z directions and in the height in the Y direction (vertical).

[0020] The printed circuit board 1 can be part of an operating device for lamps, in particular LEDs, and the electrical circuit can be the circuit of a DC-DC converter of the operating device.

[0021] To the left of the inductive component 2 on the circuit board 1 is a wire 7 serving as a contact element. The wire 7, made of an electrically conductive material, runs in the Y direction through a soldering pad on the circuit board 1, which is electrically connected to a specific circuit point of the electrical circuit, and touches the ferromagnetic core 3 to contact it or to establish an electrical connection from the ferromagnetic core 3 to the circuit point. This prevents isolation of the ferromagnetic core 3 or parts thereof from the electrical circuit. The circuit point can depend on the circuit type and can be the device earth, ground, a reference potential, or another circuit point, for example, in circuits with potential isolation.

[0022] Fig. Figure 2 shows the wire 7 in the unmounted or unplugged state. The wire 7 extends in the Y direction (vertical) and has a hook 8 (protrusion) at its lower end and a U-shaped bend 9 at its upper end. The hook 8 rests on the underside of the circuit board 1 and prevents the wire 7 from sliding out of the soldering pad toward the inductive component 2. As shown in Fig. As shown in Figure 1, the arc 9 extends over the ferromagnetic core 3, with the end of the arc 9 touching and contacting the ferromagnetic core 3 on its upper side. The arc 9 or the entire wire 7 is elastic, so that the wire 7 forms an elastic clamp that clamps between the circuit board 1 and the inductive component 2. The dashed line in Fig. Figure 1 shows the shape of the arc 9 in the relaxed state. The hook 8 and the end of the arc 9 thus rest springily against the soldering pad or the ferromagnetic core 3, respectively, for secure electrical contact. Furthermore, no additional fixation, such as soldering the wire 9 in the soldering pad, is necessary. However, tinning the soldering pad or the contact surface can be advantageous to prevent high contact resistance due to corrosion.

[0023] The wire 7 can be mounted after the inductive component 2 has been soldered to the circuit board 1, with the arc 9 being guided from below through the recess of the circuit board or the soldering pad and pulled over the ferromagnetic core 3. Alternatively, the soldering pad can be shaped so that the hook 8 can be guided through the soldering pad from above.

[0024] Fig. Figure 3 shows a section of the circuit board 1 with the soldering pad 10 in a bottom view. The opening 11 (recess) of the soldering pad 10 is shaped such that the hook 8 can be passed through the opening 11 from above and, after moving in the direction X, engages behind the soldering pad 10 and makes electrical contact. The soldering pad 10 is electrically connected to a conductor track 12 of the circuit board 1.

[0025] Alternatively, the opening 11 in the circuit board 1 can be slot-like and / or not have a soldering pad 10, wherein the hook 8 can be shaped such that it contacts the conductor track 12 directly or a larger contact surface electrically connected to it.

[0026] Fig. 4 shows a device according to a second embodiment of the present invention in a side view, in which the wire 7 or the contact element, in addition to the ferromagnetic core 3, also rests against the housing of the device and contacts it. The housing consists of a housing base 13 supporting the circuit board 1 and a housing cover 14, which closes the housing and fixes the circuit board 1 in the housing base 13. The front housing sides of the housing base 13 and the housing cover 14 are not shown in the view. At least the housing cover 14 is electrically conductive and is electrically connected to the circuit point or another reference potential via the wire 7.

[0027] In the central region of the wire 7, a tear-out 15 is bent out, which serves on the one hand to contact the soldering pad 10 arranged at least on the upper side of the circuit board 1 and on the other hand to support the wire 7 against the circuit board 1. When the housing cover 14 is open, the hook 8 and the end of the arc 9 rest resiliently on the soldering pad or the ferromagnetic core 3, as described above. When the housing cover 14 is closed, it presses on the elastic arc 9 and the tear-out 15 against the circuit board 1 or the soldering pad 10, so that the tear-out 15 rests flat on the soldering pad 10. In particular, if the wire 7 is inserted shortly before the housing cover 14 is closed, the hook 8 can be omitted and only the tear-out 15 remains.

[0028] Fig. 5 shows a device according to a third embodiment of the present invention in a side view, in which the contact element is a sheet metal stamping 16 and the recess in the circuit board 4 is slot-shaped. The sheet metal stamping 16 inserted into the recess (not shown) is bent twice in the upper part in the direction of the ferromagnetic core 3, so that the upper end 17 rests resiliently against the ferromagnetic core. At the lower end and in the central region, a tear-out 18, 19 is bent out. The tear-outs 18, 19 are each supported on the bottom or top of the circuit board 1. Thus, the sheet metal stamping 16 is fixed in its installed position on both sides with respect to the circuit board 1. At least one of the tear-outs 18, 19 is supported on a contact surface (not shown) of the circuit board 1, which is electrically connected to the circuit point.

[0029] Fig. 6 shows the sheet metal stamping 16 in its initial state, ie as an unbent sheet metal stamping strip, in particular made of bronze or spring steel. Fig. 6 shows that the upper end 17 of the sheet metal stamping 16, which contacts the ferromagnetic core 3, preferably has pointed edges 20, 21. This configuration of the upper end 17 ensures that a good electrically conductive connection is established between the core 3 and the sheet metal stamping 16, since the pointed edges 20, 21 can pierce dirt, oxide, and / or paint layers.

[0030] The sheet metal stamping 16 can be used as an alternative to the wire 7 in the Fig. 4 can be used to contact the housing cover 14. It is also possible to bend the wire 7 or the sheet metal stamping 16 into an S shape at the upper end, so that one arc resiliently contacts the ferromagnetic core 3 and the other arc or the pointed edges 20, 21 contacts the housing cover 14.

[0031] In the Fig. 1, Fig. 4 and Fig. In the embodiments shown in Figure 5, the contact element contacts the upper side of the ferromagnetic core 3 or the side facing away from the circuit board 1. However, it is also possible for the contact element to additionally or alternatively contact the ferromagnetic core 3 laterally.

Claims

[1] Device comprising an inductive component (2) with a ferromagnetic core (3), a printed circuit board (1) on which the inductive component (2) is soldered, and a contact element (7, 16) which is electrically connected to a potential of the circuit board (1) and which bears against the ferromagnetic core (3) in order to electrically contact the ferromagnetic core (3) and to connect it to the potential, wherein a first end of the contact element (7, 16) at least engages into a recess (11) of the printed circuit board (1), a second end is bent out of the plane of the first end such that the contact element (7, 16) rests resiliently against the ferromagnetic core (3) in the region of the second end after the contact element (7, 16) has been inserted into the recess (11), and at least one hook (8, 18) is arranged on the first end of the contact element (7, 16), which fixes the contact element (7, 16) in the inserted state. [2] Device according to claim 1, wherein the second end is supported on the ferromagnetic core (3) in the horizontal direction (X) or in the vertical direction (Y) with respect to the circuit board (1). [3] Device according to claim 1 or 2, wherein the hook (8, 18) is designed as an elastic element which, when inserted into the recess (11) of the circuit board, engages behind the latter and automatically snaps back. [4] Device according to one of the preceding claims, wherein the hook (8, 18) is a tear-out bent out at the first end of the contact element (7, 16). [5] Device according to one of the preceding claims, wherein at least one tear-out (15, 19) is bent out on the contact element (7, 16) between the first and second ends, which is supported in the vertical direction (Y) on the circuit board (1) after insertion of the contact element (7, 16) and comes to lie on the opposite side surface of the circuit board (1) with respect to the hook (8, 18). [6] Device according to claim 5, wherein at least the hook (8, 18) or the tear-out (15, 19) bent out on the contact element (7, 16) between the first and second ends rests resiliently on the circuit board (1) after insertion of the contact element (7, 16), so that the circuit board (1) is clamped between the hook (8, 18) and the tear-out (15, 19). [7] Device according to one of the preceding claims, wherein the contact element (7, 16) electrically contacts a tinned or non-tinned soldering surface of the circuit board (1) or a tinned or non-tinned soldering eyelet of the circuit board (1) which is electrically connected to the potential. [8] Device according to one of the preceding claims, wherein the contact element (7, 16) is a sheet metal stamping, and the recess (11) is slot-like. [9] Device according to one of the preceding claims, wherein the device has a housing (13, 14) and the contact element (7, 16) rests resiliently against an inner side of the housing (13, 14). [10] Operating device for lighting means, comprising a device according to one of the preceding claims.

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