EMC Contact Spring

Abstract

The present invention relates to an EMC contact spring (1) for establishing an electrical contact with improved electromagnetic compatibility, comprising a leg region (2) with a first number of turns W1, a top region (3) with a second number of turns W2, and a resilient region (4) arranged between the leg region (2) and the top region (3), wherein the leg region (2), the top region (3), and the resilient region (4) are made from a single spring wire (10), wherein a first maximum diameter D1 of the leg region (2) is greater than a second maximum diameter D2 of the top region (3), the resilient region (4) has a third number of turns W3, with 1≦W3≦2, and wherein an aspect ratio A between the overall length L of the EMC contact spring (1) and the maximum diameter satisfies 1≦A≦2.

Description

[Technical Field]

[0001] The present invention relates to an EMC contact spring with significantly reduced inductance, and to a printed circuit board or component equipped with such an EMC contact spring. [Background technology]

[0002] In the prior art, EMC contact springs are manufactured, for example, from spring steel, copper alloys, or coated plastics. To improve electromagnetic compatibility (EMC), it is desirable for EMC contact springs to have as low an inductance as possible. Here, EMC contact springs provide electrical contact between a printed circuit board or other circuit carrier and a housing, etc., in order to dissipate unwanted voltages in particular. Here, EMC contact springs represent a significant cost factor. EMC contact springs are usually formed springs with a relatively wide contact surface, i.e., C-springs with a C-shaped cross section. However, these have a relatively low inductance in the range of a few nH. Summary of the Invention [Means for solving the problem]

[0003] On the other hand, the EMC contact spring according to the present invention for electrical contact with improved electromagnetic compatibility, having the features of claim 1, has the advantage of significantly reduced inductance. In particular, the EMC contact spring according to the present invention preferably has an inductance of less than 1.8 nH, in particular less than 0.9 nH. Furthermore, the EMC contact spring according to the present invention can be very easily and reliably connected to a printed circuit board or the like, for example by soldering. According to the present invention, this is achieved by the EMC contact spring having a leg region with a first number of turns W1 and a top region with a second number of turns W2. The EMC contact spring also includes an elastic region disposed between and connecting the leg region and the top region. The leg region, the top region, and the elastic region are made from a single spring wire. Therefore, the EMC contact spring according to the present invention is a type of helical spring. Furthermore, the first maximum diameter D1 of the leg region is greater than the second maximum diameter D2 of the top region. The elastic region has a third number of turns W3, where 1≦W3≦2. Furthermore, the aspect ratio A of the total length L of the EMC contact spring to the maximum diameter of the EMC contact spring is 1≦A≦2. These methods significantly reduce the inductance of the EMC contact spring, and also significantly reduce the manufacturing cost of the EMC contact spring.

[0004] The dependent claims show preferred refinements of the invention. Preferably, the largest diameter of the EMC contact spring is in the leg region, and thus the largest diameter of the EMC contact spring is the first diameter D1, which in particular allows for very good fixing of the EMC contact spring to a printed circuit board or the like.

[0005] More preferably, the number of turns W1 in the leg region is greater than the number of turns W2 in the top region. Preferably, the number of turns W3 in the elastic region is less than the number of turns W1 in the leg region and / or less than the number of turns W2 in the top region.

[0006] The leg region of the EMC contact spring preferably has a fixing base winding located on the leg surface E1. The base winding is spirally arranged on the leg surface E1 and comprises at least one complete turn. Preferably, the leg region comprises at least two complete turns. In the region of the leg surface, the leg region preferably also has a first maximum diameter D1 of the EMC contact spring.

[0007] According to a particularly preferred embodiment of the invention, the elastic region has just 1.3 turns, whereby preferably the axial extension (length) of the windings of the elastic region is in the range of 2 mm to 2.5 mm, in particular 2.15 mm.

[0008] Preferably, the axial extension of the elastic regions is greater than the axial extension of the leg regions, which is greater than the axial extension of the top region. To allow for reliable electrical contact at the top region, the top region has at least one complete turn at the top surface E2.

[0009] The spring wire of the EMC contact spring preferably has a constant diameter and can be made from different materials, preferably copper, copper alloys, spring steel or coated plastic.

[0010] According to a particularly preferred embodiment for reducing inductance, the ratio of the first maximum diameter D1 of the leg region to the second maximum diameter D2 of the top region is in the range of 1≦D1 / D2≦1.5. Particularly preferably, the ratio D1 / D2 is in the range of 1.1≦D1 / D2≦1.2.

[0011] The invention also relates to a printed circuit board, an electrical component or an electronic component comprising an EMC contact spring according to the invention, which is fixed to the printed circuit board by means of its leg regions, whereby the fixing to the printed circuit board can take place, for example, by a soldering process or by pressure and / or form-fitting.

[0012] Here, the EMC contact spring preferably provides an electrical contact between the printed circuit board and a housing or shield or the like. [Brief explanation of the drawings]

[0013] Preferred embodiments of the invention will now be described in detail with reference to the accompanying drawings. [Figure 1] 1 is a schematic side view of an EMC contact spring according to a preferred embodiment of the invention; [Figure 2] Top view of the EMC contact spring in Figure 1. [Figure 3] Bottom view of the EMC contact spring in Figure 1. [Figure 4] Perspective view of the EMC contact spring in Figure 1. DETAILED DESCRIPTION OF THE INVENTION

[0014] In the following, an EMC contact spring 1 according to a preferred embodiment of the invention will be described in detail with reference to FIGS. The EMC contact spring 1 is made from a single piece of spring wire 10 and has substantially the shape of a specially shaped helical spring.

[0015] The EMC contact spring 1 comprises a leg region 2, a top region 3 and a resilient region 4 arranged between the leg region 2 and the top region 3. 2, 3 and 4, the end 5 of the spring wire 10 is shown in the top region 3 and the end 6 of the spring wire 10 is shown in the leg region 2. XX indicates the central axis of the EMC contact spring 1 and defines the direction of axial extension.

[0016] In the direction of the central axis XX, the EMC contact spring 1 has a maximum overall length L. As shown in Figure 1, the elastic region 4 has a first axial length L1, the leg region 2 has a second axial length L2, and the top region 3 has a third axial length L3.

[0017] The first length L1 of the elastic region 4 is greater than the second length L2 of the leg region and greater than the third length L3 of the top region 3. Additionally, the second length L2 of the leg region 2 is greater than the third length L3 of the top region 3.

[0018] The leg region 2 preferably contains twice as many turns as the top region 3 . As can be seen particularly from Figures 1 and 4, the leg region 2 has a base winding 20 for fixing the EMC contact spring to a printed circuit board or the like. The base winding 20 is located on the leg face E1, and the base winding 20 is helically located on the leg face E1. In this embodiment, the base winding 20 includes exactly two complete turns located in the leg face E1. The end 6 of the spring wire 10 is located within the maximum diameter D1 of the leg region 2.

[0019] Similarly, the end 5 of the apex region 3 of the spring wire 10 is located within the diameter D2 of the apex region 3. As can be seen in Figure 1, the elastic region 4 has a total of 1.3 turns. The axial length L0 of a complete turn of the elastic region 4 is approximately 2.15 mm, where the length L0 preferably corresponds to approximately half the total axial length L of the EMC contact spring.

[0020] The top region 3, like the leg region 2, has at least one complete turn located in the top plane E2, which can be seen best in Figure 2. At the top plane E2, this turn is located within a second diameter D2 of the top region 3 and is arranged helically within the top plane E2.

[0021] The aspect ratio A of the total length L of the EMC contact spring 1 to its maximum diameter, the first diameter D1, is in the range of 1≦A≦2. In this embodiment, the aspect ratio A is approximately 1.5. In other words, the total length L of the EMC contact spring 1 is approximately 1.5 times the first maximum diameter D1 in the leg region 2.

[0022] 1 to 4 has an inductance of less than 1.8 nH with 1.3 free turns, allowing the EMC contact spring 1 to be manufactured very cost-effectively. Furthermore, with the ends 5, 6 of the spring wire 10 located within the first maximum diameter D1 in the leg region 2 and within the second maximum diameter D2 in the top region 3, a very compact construction can be achieved, which reduces the space requirements of the EMC contact spring 1 during use.

[0023] Furthermore, the EMC contact spring 1 according to the present invention allows for a large tolerance compensation in the direction of the central axis XX. The presence of the base winding 20 in the leg region 2 creates a kind of solder foot, which allows the EMC contact spring 1 to be soldered very well to a printed circuit board or the like. This achieves maximum strength of the solder joint to the printed circuit board. Furthermore, the base winding 20 in the leg region 2 prevents tilting when the EMC contact spring 1 is placed on the printed circuit board before the soldering process. This allows for a very precise soldering process. In particular, this also makes it possible to easily, quickly and mechanically fix the EMC contact spring 1 to the printed circuit board.

[0024] The spring force of the elastic region 4 is preferably determined by the choice of material and diameter of the spring wire 10 . The design of the EMC contact spring 1 according to the invention also allows for large tolerance compensation for further components, such as shields or housings, after the EMC contact spring 1 has been fixed on the printed circuit board. In particular, electrical contact with the shield or housing is automatically established upon installation. The elastic region 4 has a relatively large axial length L1, which allows for large tolerance compensation.

Claims

1. An EMC contact spring (1) for establishing an electrical contact with improved electromagnetic compatibility, comprising: a leg region (2) with a first number of turns W1; a top region (3) with a second number of turns W2; - an elastic region (4) arranged between said leg region (2) and said top region (3), - said leg region (2), said top region (3) and said elastic region (4) are made from one spring wire (10); - the first maximum diameter D1 of said foot region (2) is greater than the second maximum diameter D2 of said top region (3); - said elastic region (4) has a third number of turns W3, with 1≦W3≦2; the aspect ratio A between the total length L and the maximum diameter of said EMC contact spring (1) is 1≦A≦2; EMC contact spring (1).

2. 2. An EMC contact spring (1) according to claim 1, wherein said maximum diameter is said first diameter D1 of said leg region (2).

3. 3. An EMC contact spring (1) according to claim 1 or 2, wherein the first number of turns W1 of the leg region (2) is greater than the second number of turns W2 of the top region (3), in particular W1 ≥ 2 x W2.

4. 4. The EMC contact spring (1) according to claim 1, wherein the third number of turns W3 of the elastic region (4) is smaller than the first number of turns W1 of the leg region (1) and / or the third number of turns W3 of the elastic region (4) is smaller than the second number of turns W2 of the top region (3).

5. 5. An EMC contact spring (1) according to claim 1, wherein the leg region (2) has a base winding (20) for fixing the EMC contact spring (1), the base winding (20) being located on the leg face E1, the base winding (20) being located in a spiral manner on the leg face E1 and having at least one complete turn, in particular two complete turns, within the first maximum diameter D1 of the leg region (2).

6. An EMC contact spring (1) according to any one of claims 1 to 5, wherein the elastic region (4) has between 1 and 2 turns, in particular just 1.3 turns.

7. An EMC contact spring (1) according to any one of claims 1 to 6, wherein the top region (3) has at least one complete turn on the top surface E2.

8. An EMC contact spring (1) according to any one of claims 1 to 7, wherein the spring wire (10) has a constant diameter.

9. 9. An EMC contact spring (1) according to any one of claims 1 to 8, wherein the ratio of the first maximum diameter D1 of the foot region (2) to the second maximum diameter D2 of the top region (3) is in the range 1≦D1 / D2≦1.5, in particular in the range 1.1≦D1 / D2≦1.

2.

10. 10. A printed circuit board, electrical or electronic component comprising an EMC contact spring (1) according to any one of claims 1 to 9, wherein the EMC contact spring (1) is fixed to the leg region (2) by pressure, form and / or material bonding.

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