Emc contact spring

Abstract

The present invention relates to an EMC contact spring (1) for producing an electrical contact with improved electromagnetic compatibility, comprising a foot region (2) with a first number W1 of windings, a head region (3) with a second number W2 of windings, a sprung region (4) that is arranged between the foot region (2) and the head region (3), wherein the foot region (2), the head region (3) and the sprung region (4) are produced from a spring wire (10), wherein a maximum first diameter D1 of the foot region (2) is larger than a maximum second diameter D2 of the head region (3), wherein the sprung region (4) has a third number W3 of windings, wherein 1 ≤ W3 ≤ 2 and wherein for an aspect ratio A of a total length L to a maximum diameter of the EMC contact spring (1) the following applies: 1 ≤ A ≤ 2.

Description

[0001] Description

[0002] title

[0003] EMC contact spring

[0004] State of the art

[0005] The present invention relates to an EMC contact spring with a significantly reduced inductance and to a printed circuit board or a component with such an EMC contact spring.

[0006] EMC contact springs are currently manufactured from spring steel, copper alloys, or coated plastic, for example. To improve electromagnetic compatibility (EMC), the EMC contact springs should exhibit as low an inductance as possible. EMC contact springs, in particular, provide electrical contact between a printed circuit board or other circuit carrier and a housing or the like for dissipating unwanted electrical voltages. In this case, EMC contact springs represent a significant cost factor. EMC contact springs are typically C-shaped springs with a C-shaped cross-section and relatively wide contact surfaces. However, these have relatively poor inductance in the range of a few nH.

[0007] Disclosure of the invention

[0008] The inventive EMC contact spring for electrical contacting with improved electromagnetic compatibility with the features of claim 1 has the advantage that a significantly reduced inductance can be achieved. In particular, the inventive EMC contact spring has an inductance of preferably less than 1.8 nH and in particular less than 0.9 nH. Furthermore, the inventive EMC contact spring can be very easily and securely connected to a circuit board or the like, for example by means of a soldered connection. This is achieved according to the invention in that the EMC contact spring has a base region with a first number W1 of turns and a head region with a second number W2 of turns. Furthermore, the EMC contact spring comprises a resilient region which is arranged between the base region and the contact region and connects the base region to the contact region.The base region, the head region, and the resilient region are made from a single-piece spring wire. The EMC contact spring according to the invention is thus a type of spiral spring. Furthermore, a maximum first diameter D1 of the base region is greater than a maximum second diameter D2 of the head region. The resilient region has a third number W3 of windings, where: 1 < W3 < 2. Furthermore, the aspect ratio A of a total length L of the EMC contact spring to a maximum diameter of the EMC contact spring is: 1 < A < 2. Through these measures, a significantly reduced inductance of the EMC contact spring has been achieved, which also results in a significant reduction in the manufacturing costs of the EMC contact spring.

[0009] The subclaims show preferred developments of the invention.

[0010] Preferably, the maximum diameter of the EMC contact spring is located at the base. Thus, the maximum diameter of the EMC contact spring is the first diameter D1. This allows for particularly good fixation of the EMC contact spring to a circuit board or the like.

[0011] Further preferably, the number W1 of turns of the foot region is greater than the number W2 of turns of the head region.

[0012] Preferably, the number W3 of turns of the resilient region is smaller than the number W1 of turns of the foot region and / or smaller than the number W2 of turns of the head region.

[0013] The base region of the EMC contact spring preferably has a base winding for fixation, which lies in a base plane E1. The base winding is arranged spirally in the base plane E1 and comprises at least one complete winding. The base region preferably comprises at least two complete windings. In the area of ​​the base plane, the base region also preferably has the maximum first diameter D1 of the EMC contact spring.

[0014] According to a particularly preferred embodiment of the invention, the resilient region has exactly 1.3 turns. The axial extension (length) of a turn of the resilient region is preferably in a range from 2 mm to 2.5 mm, and in particular is 2.15 mm.

[0015] Preferably, the axial extension of the resilient region is greater than an axial extension of the foot region and greater than an axial extension of the head region.

[0016] In order to enable secure electrical contact at the head area, the head area has at least one complete turn in a head plane E2.

[0017] The spring wire of the EMC contact spring preferably has a constant diameter. The spring wire can be made of various materials, preferably copper or a copper alloy, spring steel, or a coated plastic.

[0018] According to a particularly preferred embodiment for reducing the inductance, a ratio of the maximum first diameter D1 of the base region to a maximum second diameter D2 of the head region is in a range of 1 < D1 / D2 < 1.5. Particularly preferably, the ratio D1 / D2 is in a range of 1.1 < D1 / D2 < 1.2.

[0019] Furthermore, the present invention relates to a printed 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 printed circuit board by its base region. The fixing to the printed circuit board can be achieved, for example, by means of a soldering process or by force-fitting and / or positive-locking.

[0020] The EMC contact spring preferably provides electrical contact between the circuit board and a housing or shielding, or the like. Brief description of the drawing

[0021] A preferred embodiment of the invention will be described in detail below with reference to the accompanying drawings. In the drawing:

[0022] Figure 1 is a schematic side view of an EMC contact spring according to a preferred embodiment of the invention,

[0023] Figure 2 is a top view of the EMC contact spring of Figure 1,

[0024] Figure 3 is a bottom view of the EMC contact spring of Figure 1 and

[0025] Figure 4 is a perspective view of the EMC contact spring of Figure

[0026] 1.

[0027] Preferred embodiment of the invention

[0028] An EMC contact spring 1 according to a preferred embodiment of the invention is described in detail below with reference to Figures 1 to 4.

[0029] The EMC contact spring 1 is made of a one-piece spring wire 10 and essentially has the shape of a specially shaped spiral spring.

[0030] The EMC contact spring 1 comprises a foot region 2, a head region 3 and a resilient region 4 arranged between the foot region 2 and the head region 3.

[0031] Figures 2, 3, and 4 show one end 5 of the spring wire 10 at the head region 3 and one end 6 of the spring wire 10 at the foot region 2. XX denotes a central axis of the EMC contact spring 1 and defines the direction of the axial extension.

[0032] In the direction of the central axis XX, the EMC contact spring 1 has a maximum total length L. As shown in Figure 1, the resilient region 4 has a first axial length L1, the base region 2 has a second axial length L2, and the head region 3 has a third axial length L3.

[0033] The first length L1 of the resilient 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.

[0034] Furthermore, the second length L2 of the foot region 2 is also greater than the third length L3 of the head region 3.

[0035] The foot section 2 preferably comprises twice as many turns as the head section 3.

[0036] As can be seen particularly from Figures 1 and 4, the base region 2 has a base winding 20 for fixing the EMC contact spring to a circuit board or the like. The base winding 20 lies in a base plane E1, with the base winding 20 spiraling within the base plane E1. In this exemplary embodiment, the base winding 20 comprises exactly two complete windings, which lie within the base plane E1. One end 6 of the spring wire 10 lies within the maximum diameter D1 of the base region 2.

[0037] The end 5 of the spring wire 10 at the head area 3 also lies within the diameter D2 of the head area 3.

[0038] As can be further seen from Figure 1, the resilient region 4 has a total of 1.3 turns. The axial length L0 of a complete turn of the resilient region 4 is approximately 2.15 mm. The length L0 preferably corresponds to approximately half the total length L of the EMC contact spring in the axial direction.

[0039] Similar to the base region 2, the head region 3 has at least one complete turn, which lies in a head plane E2. This is best seen in Figure 2. In the head plane E2, the turn again lies within the second diameter D2 of the head region 3 and is arranged spirally in the head plane E2. An aspect ratio A of the total length L to a maximum diameter of the EMC contact spring 1, which is the first diameter D1, lies in a range of 1 < A < 2. In this exemplary 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 as large as the maximum first diameter D1 at the base region 2.

[0040] The EMC contact spring 1 shown in Figures 1 to 4 has an inductance of less than 1.8 nH with 1.3 free turns. The EMC contact spring 1 can be manufactured very cost-effectively. The ends 5, 6 of the spring wire 10 are arranged inside the maximum first diameter D1 of the base region 2 and inside the maximum second diameter D2 of the head region 3, allowing a very compact design to be realized, resulting in a reduced space requirement for the EMC contact spring 1 during use.

[0041] Furthermore, the EMC contact spring 1 according to the invention enables large tolerance compensation in the direction of the central axis XX. The provision of the base windings 20 in the foot region 2 results in a type of soldering foot, with which the EMC contact spring 1 can be very easily soldered to a circuit board or the like. This allows for maximum strength of the soldered connection to the circuit board. Furthermore, the base windings 20 of the foot region 2 prevent tilting when placing the EMC contact spring 1 on the circuit board before the soldering process. This enables a very precise soldering process. In particular, this also results in simple and quick mechanical fixing of the EMC contact spring 1 to the circuit board.

[0042] A spring force of the resilient region 4 is preferably determined by selecting the material and the diameter of the spring wire 10.

[0043] The inventive design of the EMC contact spring 1 makes it possible to achieve a large tolerance compensation with another component, such as a shield or a housing, or the like, after the EMC contact spring 1 is fixed to the circuit board. In particular, the electrical contact with the shield and the housing is established automatically simply by assembly. Since the resilient region 4 has a relatively large axial length L1, a large tolerance compensation is possible.

Claims

Claims 1. EMC contact spring (1) for establishing an electrical contact with improved electromagnetic compatibility, comprising: - a foot region (2) with a first number W1 of turns, - a head region (3) with a second number W2 of turns, - a resilient region (4) arranged between the foot region (2) and the head region (3), - wherein the foot region (2), the head region (3) and the resilient region (4) are 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), - wherein the resilient region (4) has a third number W3 of turns, where 1 < W3 < 2 and - where for an aspect ratio A of a total length L to a maximum diameter of the EMC contact spring (1) the following applies: 1 < A < 2.

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

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

4. EMC contact spring (1) according to one of the preceding claims, wherein the third number W3 of turns of the resilient region (4) is smaller than the first number W1 of turns of the foot region (1) and / or wherein the third number W3 of turns of the resilient region (4) is smaller than the second number W2 of turns of the head region (3). EMC contact spring (1) according to one of the preceding claims, wherein the foot region (2) has a base turn (20) for fixing the EMC contact spring (1), wherein the base turn (20) lies in a foot plane E1, wherein the base turn (20) lies spirally in the foot plane E1 and has at least one complete turn, in particular two complete turns, within the maximum first diameter D1 of the foot region (2). EMC contact spring (1) according to one of the preceding claims, wherein the resilient region (4) has a number of turns between 1 and 2 and in particular has exactly 1.3 turns. EMC contact spring (1) according to one of the preceding claims, wherein the head region (3) has at least one complete turn in a head plane E2. EMC contact spring (1) according to one of the preceding claims, wherein the spring wire (10) has a constant diameter.EMC contact spring (1) according to one of the preceding claims, wherein a ratio of the maximum first diameter D1 of the base region (2) to the maximum second diameter D2 of the head region (3) lies in a range of 1 < D1 / D2 < 1.5 and in particular in a range of 1.1 < D1 / D2 < 1.

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

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