EMV contact spring

Abstract

The invention relates to an EMV contact spring (1) for producing an electrical contact with better electromagnetic compatibility, comprising a foot region (2) having a first number of turns W1, a head region (3) having a second number of turns W2, and an elastic region (4) arranged between the foot region (2) and the head region (3), the foot region (2), the head region (3) and the elastic region (4) being made of a spring wire (10), wherein a maximum first diameter D1 of the foot region (2) is greater than a maximum second diameter D2 of the head region (3), and wherein the elastic region (4) has a third number of turns W3, where 1 < = W3 < = 2, and wherein for an aspect ratio A of the total length L to the maximum diameter of the EMV contact spring (1): 1 < = A < = 2.

Description

Technical Field

[0001] The invention relates to an EMC contact spring having a significantly reduced inductance and to a circuit board or a component having such an EMC contact spring. Background Art

[0002] In the prior art, EMC contact springs are made of spring steel or copper alloys or coated plastic, for example. In order to improve electromagnetic compatibility (EMC), EMC contact springs should have as low an inductance as possible. In particular, the EMC contact springs provide electrical contact between a circuit board or another circuit carrier and a housing or the like in order to conduct away undesired voltages. In this case, the EMC contact springs are a huge cost factor. EMC contact springs are usually C-shaped springs with a C-shaped cross section as shaped springs with a relatively wide contact surface. However, they have a relatively poor inductance in the range of a few nH. Summary of the invention

[0003] In contrast, the EMC contact spring according to the invention for electrical contact with improved electromagnetic compatibility having the features of claim 1 has the advantage that a significantly reduced inductance can be achieved. In particular, the EMC contact spring according to the invention has an inductance that is preferably less than 1.8 nH and in particular less than 0.9 nH. In addition, the EMC contact spring according to the invention can be connected to a circuit board or the like very simply and reliably, for example by means of a solder connection. This is achieved according to the invention in that the EMC contact spring has a foot region with a first number of turns W1 and a head region with a second number of turns W2. In addition, the EMC contact spring comprises an elastic region, which is arranged between the foot region and the contact region and connects the foot region to the contact region. The foot region, the head region and the elastic region are made of a one-piece spring wire. The EMC contact spring according to the invention is therefore a helical spring. In addition, the maximum first diameter D1 of the foot region is greater than the maximum second diameter D2 of the head region. The elastic region has a third number of turns W3, where 1≤W3≤2 applies. Furthermore, for the aspect ratio A of the total length L of the EMC contact spring to the maximum diameter of the EMC contact spring, the following applies: 1≤A≤2. These measures result in a significantly reduced inductance of the EMC contact spring, which in turn leads to significantly reduced production costs for the EMC contact spring.

[0004] The dependent claims reveal preferred developments of the invention.

[0005] Preferably, the maximum diameter of the EMC contact spring is present in the foot region. The maximum diameter of the EMC contact spring is therefore the first diameter D1. This makes it possible to fix the EMC contact spring particularly well on a circuit board or the like.

[0006] It is further preferred that the number of turns W1 in the foot region is greater than the number of turns W2 in the head region.

[0007] Preferably, the number of turns W3 of the elastic region is smaller than the number of turns W1 of the foot region and / or smaller than the number of turns W2 of the head region.

[0008] The foot region of the EMC contact spring preferably has a base turn for fixing, which is located in the foot plane E1. The base turn is arranged helically in the foot plane E1 and includes at least one complete turn. Preferably, the foot region includes at least two complete turns. In the region of the foot plane, the foot region also preferably has the largest first diameter D1 of the EMC contact spring.

[0009] According to a particularly preferred embodiment of the invention, the elastic region has exactly 1.3 windings. Preferably, the axial extension (length) of the windings of the elastic region is in the range of 2 mm to 2.5 mm, and in particular 2.15 mm.

[0010] Preferably, the axial extension of the elastic region is greater than the axial extension of the foot region and greater than the axial extension of the head region.

[0011] In order to be able to achieve reliable electrical contact at the head region, the head region has at least one complete wire turn in the head plane E2 .

[0012] The spring wire of the EMC contact spring preferably has a constant diameter. The spring wire can be made of different materials, preferably copper or a copper alloy or spring steel or coated plastic.

[0013] According to a particularly preferred embodiment for reducing the inductance, the ratio of the first maximum diameter D1 of the foot region to the second maximum diameter D2 of the head 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.

[0014] The invention further relates to a circuit board or an electrical or electronic component comprising an EMC contact spring according to the invention, wherein the EMC contact spring is fixed to the circuit board by means of a foot region. In this case, the fixing to the circuit board can be achieved, for example, by a welding process or by force-locking and / or form-locking means.

[0015] In this case, the EMC contact spring preferably provides the electrical contact between the printed circuit board and the housing or the shield or the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. In the drawings:

[0017] Figure 1 is a schematic side view of an EMV contact spring according to a preferred embodiment of the present invention;

[0018] Figure 2 yes Figure 1 Top view of the EMV contact spring;

[0019] Figure 3 yes Figure 1 A bottom view of the EMV contact spring; and

[0020] Figure 4 yes Figure 1 A perspective view of an EMV contact spring. DETAILED DESCRIPTION

[0021] Refer to the following Figures 1 to 4 The EMC contact spring 1 according to a preferred embodiment of the present invention is described in detail.

[0022] The EMC contact spring 1 is produced from a one-piece spring wire 10 and has essentially the shape of a specially shaped helical spring.

[0023] The EMC contact spring 1 comprises a foot region 2 , a head region 3 and a spring region 4 arranged between the foot region 2 and the head region 3 .

[0024] exist Figure 2 , 3 In FIGS. 4 and 5 , the end 5 of the spring wire 10 at the head region 3 and the end 6 of the spring wire 10 at the foot region 2 are shown. XX denotes the center axis of the EMC contact spring 1 and defines the direction of the axial extension.

[0025] In the direction of the central axis XX, the EMC contact spring 1 has a maximum total length L. Figure 1 As shown, the elastic region 4 has a first axial length L1 , the foot region 2 has a second axial length L2 , and the head region 3 has a third axial length L3 .

[0026] The first length L1 of the elastic region 4 is greater than the second length L2 of the foot region and also greater than the third length L3 of the head region 3 .

[0027] Furthermore, the second length L2 of the foot region 2 is also greater than the third length L3 of the head region 3 .

[0028] The foot region 2 preferably comprises twice as many turns as the head region 3 .

[0029] Especially from Figure 1 and Figure 4, it can be seen that the foot region 2 has a base turn 20, which serves to fix the EMC contact spring on a circuit board or the like. The base turn 20 is located in the foot plane E1, wherein the base turn 20 is located helically in the foot plane E1. In this embodiment, the base turn 20 includes exactly two complete turns, which are located in the foot plane E1. The end 6 of the spring wire 10 is located in the maximum diameter D1 of the foot region 2.

[0030] The end 5 of the spring wire 10 at the head region 3 is likewise located within the diameter D2 of the head region 3 .

[0031] In addition, from Figure 1 It can be seen that the spring region 4 has a total of 1.3 turns. The axial length L0 of one complete turn of the spring region 4 is approximately 2.15 mm. The length L0 preferably corresponds to approximately half of the total length L of the EMC contact spring in the axial direction.

[0032] The head region 3 has, similarly to the foot region 2, at least one complete winding which is located in the head plane E2. Figure 2 In the head plane E2 , the turns are again located within the second diameter D2 of the head region 3 and are arranged helically in the head plane E2 .

[0033] The aspect ratio of the total length L of the EMV contact spring 1 to the maximum diameter, ie, the first diameter D1 A is in the range of 1≤A≤2. In the present 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 maximum first diameter D1 at the foot region 2 .

[0034] Figures 1 to 4 The EMC contact spring 1 shown in FIG. 1 has an inductance of less than 1.8 nH with 1.3 free turns. The EMC contact spring 1 can be produced very cost-effectively. Due to the ends 5 , 6 of the spring wire 10 being arranged within the first maximum diameter D1 of the foot region 2 and within the second maximum diameter D2 of the head region 3 , a very compact design can also be achieved, which reduces the space requirement of the EMC contact spring 1 during use.

[0035] Furthermore, the EMC contact spring 1 according to the invention can achieve large tolerance compensation in the direction of the center axis XX. By providing the base turns 20 in the foot region 2, a welding foot is formed, with which the EMC contact spring 1 can be very well welded to a circuit board or the like. In this case, the maximum strength of the welded connection on the circuit board can be achieved. Furthermore, the base turns 20 in the foot region 2 can prevent the EMC contact spring 1 from tilting when it is placed on the circuit board before the welding process. This makes it possible to achieve a very precise welding process. In particular, this also makes it possible to simply and quickly mechanically fix the EMC contact spring 1 on the circuit board.

[0036] The spring force of the elastic region 4 is preferably determined by the choice of the material and the diameter of the spring wire 10 .

[0037] The design of the EMC contact spring 1 according to the invention makes it possible to achieve greater tolerance compensation with respect to other components, such as shields or housings, even after the EMC contact spring 1 has been fixed to the circuit board. In particular, electrical contact with the shield and the housing is automatically established simply by assembly. Since the elastic region 4 has a relatively large axial length L1, greater tolerance compensation can be achieved.

Claims

1. An EMC contact spring (1) for establishing an electrical contact with improved electromagnetic compatibility, the EMC contact spring comprising: a foot region (2) having a first number of turns W1, a head region (3) having a second number of turns W2, - an elastic region (4) arranged between the foot region (2) and the head region (3), - wherein the foot region (2), the head region (3) and the elastic region (4) are made of spring wire (10), - wherein the maximum first diameter D1 of the foot region (2) is greater than the maximum second diameter D2 of the head region (3), - wherein the elastic region (4) has a third number of turns W3, where 1≤W3≤2, and - wherein for the aspect ratio A of the total length L to the maximum diameter of the EMC contact spring (1) the following applies: 1≤A≤2.

2. The EMC contact spring (1) according to claim 1, wherein the maximum diameter is a first diameter D1 at the foot region (2).

3. The EMC contact spring (1) according to any one of the preceding claims, wherein a first number of turns W1 of the foot region (2) is greater than a second number of turns W2 of the head region (3), and wherein in particular W1 ≥ 2×W2.

4. An EMC contact spring (1) according to any one of the preceding claims, wherein the third number of turns W3 of the elastic region (4) is smaller than the first number of turns W1 of the foot region (1), and / or wherein the third number of turns W3 of the elastic region (4) is smaller than the second number of turns W2 of the head region (3).

5. An EMC contact spring (1) according to any of the preceding claims, wherein the foot area (2) has a base turn (20) for fixing the EMC contact spring (1), wherein the base turn (20) is located in a foot plane E1, wherein the base turn (20) is spirally located in the foot plane E1 and has at least one complete turn, in particular two complete turns, within a maximum first diameter D1 of the foot area (2). 6 . The EMC contact spring ( 1 ) according to claim 1 , wherein the spring region ( 4 ) has between 1 and 2 turns, and in particular has exactly 1.3 turns.

7. The EMC contact spring (1) according to claim 1, wherein the head region (3) has at least one complete turn in the head plane E2.

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

9. The EMC contact spring (1) according to any one of the preceding claims, wherein: The ratio of the maximum first diameter D1 of the foot region (2) to the maximum second diameter D2 of the head region (3) is within the range of 1≤D1 / D2≤1.5, and in particular within the range of 1.1≤D1 / D2≤1.

2.

10. A circuit board or an electronic or electrical component comprising an EMC contact spring (1) according to any one of the preceding claims, wherein the EMC contact spring (1) is fixed with a foot region (2) in a force-fitting and form-fitting and / or material-locking manner.

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