Printed circuit board with passive vibration damping

Abstract

The invention relates to a passive damper for damping, preferably for damping a printed circuit board, and to a printed circuit board with passive damping.

Description

Technical Field

[0001] The invention generally relates to a passive vibration damper for vibration damping, preferably for vibration damping of a printed circuit board, and to a printed circuit board with passive vibration damping. Background Art

[0002] Electronic devices or control units are often used in motor vehicles. If these control units are connected to moving or movable components, such as drive units, these control units may be subject to strong vibrations during operation. Shocks during driving may lead to oscillations and thus vibrations. The reliability of the electronic devices is therefore challenged by vibrations which may negatively affect the reliability of these devices during operation or also over time.

[0003] Furthermore, vibrations can also sensitively disturb or influence components on or in electronic devices. For example, driving dynamics sensors that can detect the acceleration or roll of a motor vehicle or motorcycle are therefore very sensitive to vibrations. Oscillations or mechanical vibrations can be transmitted, for example, to a printed circuit board carrying these sensors. In this case, the functionality can be adversely affected, for example even making the measurements and signals obtained from the sensors unusable. In addition, electronic components on the printed circuit board itself can also cause unwanted vibrations.

[0004] Therefore, there are various attempts to reduce such vibrations. As an example, DE 10 2020 205 243 A1 of the applicant is cited here, which describes an electronic component with a vibration absorber for this purpose. The vibration damper or vibration absorber described in this document is made of a composite material containing particles embedded in a binder. In this case, the binder is an epoxy resin.

[0005] This vibration absorber does provide good damping, but is rather light due to the material chosen, so that sufficient installation space must be provided for the corresponding mass. Summary of the invention

[0006] The present invention therefore seeks to provide a vibration absorber which does not have or at least reduces the above-mentioned disadvantages.

[0007] The inventors have worked towards this end.

[0008] This object is achieved in a surprisingly simple manner by a vibration absorber, in particular for damping vibrations of a printed circuit board, and a printed circuit board having such a vibration absorber, each according to the independent claim. Preferred embodiments and developments of the invention can be inferred from the respective dependent claims.

[0009] In a first aspect, the invention accordingly relates to a vibration absorber, in particular for damping vibrations of a printed circuit board, comprising:

[0010] - a chamber having a surrounding wall which delimits the cavity and in this case preferably completely surrounds the cavity, wherein

[0011] the volume of the cavity is at least 2%, preferably at least 5% and particularly preferably at least 10% of the volume of the vibration absorber, and wherein,

[0012] The volume of the cavity does not exceed 95%, preferably does not exceed 90%, and particularly preferably does not exceed 80% or 70% of the volume of the vibration absorber, wherein

[0013] - the chamber comprises particles, and wherein,

[0014] - The wall and the particles have the same material composition.

[0015] According to the invention, an electronic device can therefore be provided, which comprises at least one printed circuit board which can be accommodated in a housing and wherein the printed circuit board can also comprise at least one such vibration absorber in addition to other electronic components. The electronic device is preferably provided for a motor vehicle and can be embodied, for example, as a control unit for a brake system.

[0016] Thus, the invention can be used, for example, in or on an electronic device of an electronic control unit for a brake system of a motor vehicle. When, for simplicity's sake, reference is made to a motor vehicle hereinafter, the person skilled in the art will understand that a motor vehicle is also to be understood as meaning other driven vehicles, such as motorcycles or also rail vehicles.

[0017] Vibrations are considered to be mechanical vibrations in materials or bodies, which can themselves be elastic or can be formed by elastically connected parts. Vibrations can occur periodically or spontaneously during operation, for example when driving. Depending on the frequency range and duration of the vibrations, the signal quality can be negatively affected when detecting vehicle dynamics with the aid of corresponding sensors (e.g. inertial sensors or accelerometers) if these vibrations are transmitted to the sensors or to a printed circuit board located below the sensors. If mechanical vibrations occur over a long period of time, material fatigue can also occur.

[0018] Therefore, it is advantageously proposed to provide a vibration absorber directly at or on the printed circuit board of the electronic device in order to dampen / attenuate mechanical vibrations occurring during operation. The vibration absorber thus makes it possible to reduce mechanical vibrations transmitted to the electronic device, in particular the printed circuit board, during operation. The electronic components arranged on the printed circuit board may also cause vibrations. Therefore, the vibration absorber can be arranged so that vibrations originating from these components can be damped directly. Furthermore, it can be particularly advantageous if the vibration absorber is arranged as close as possible to vibration-sensitive electronic parts or components, such as sensors.

[0019] Especially in motorcycles, for example, vibrations can occur with greater intensity; in addition, due to the very limited space conditions, installation space problems can increase here. The batch sizes are also relatively low.

[0020] Therefore, such damping masses or vibration absorbers are usually manufactured from metal parts and installed as a fixed metal block. For example, stampings made of copper or other metals that can be assembled to form a metal block are known. However, the specified thickness or minimum thickness and dimensions of these stampings are disadvantageous here, especially in the case of installation space problems and small batch sizes, which can be cost-prohibitive, especially because post-processing can also be laborious.

[0021] According to the invention, it can therefore be provided that the vibration absorber is not produced from a prefabricated metal part, but rather from a metal powder, from which it can be produced by laser beam melting.

[0022] In this powder-based method, the vibration absorber can be produced in a single manufacturing step. In addition, selective laser beam melting offers the advantage that unmelted powder can be left inside the vibration absorber.

[0023] In this way, on the one hand, the damping properties can be improved and, on the other hand, manufacturing time can also be saved, since not all of the powder has to be melted. Thus, by laser beam melting, a vibration absorber can be provided which comprises a chamber with a surrounding wall which delimits the cavity and in this case preferably completely surrounds the cavity. It is assumed that laser beam melting, also known as a 3D printing method, is basically known and will therefore not be described in more detail here.

[0024] The chamber may comprise unmelted particles or metal grains. Thus, the wall and the particles may also have the same material composition.

[0025] If the vibration absorber is fastened directly to the printed circuit board or is connected to the printed circuit board in a mechanically fixed manner, shocks or mechanical vibrations lead to vibrations of the printed circuit board and thus to vibrations of the vibration absorber, wherein the kinetic energy from the vibrating printed circuit board can be absorbed by the interaction of the particles with one another and / or with the surrounding walls. In this way, effective vibration damping of the printed circuit board can be achieved.

[0026] The vibration absorber according to the invention is therefore a passive buffer and does not require energy to be supplied. It can therefore be arranged very easily at different points on a printed circuit board, in particular on the same side of the printed circuit board where the vibration-sensitive components are located and on the opposite side. The vibration absorber according to the invention thus offers multi-purpose usability.

[0027] The arrangement of the vibration absorber on the printed circuit board is therefore highly flexible, especially due to the production method, as different geometries of the vibration absorber can also be realized very easily.

[0028] The invention therefore also comprises a printed circuit board, for example for a control unit of a motor vehicle brake system, comprising a vibration absorber of the type according to the invention.

[0029] The printed circuit board may include vibration-sensitive components, such as specific sensors, for example inertial sensors or acceleration sensors.

[0030] According to an advantageous design of the invention, the volume of the cavity of the vibration absorber can be at least 2%, preferably at least 5%, and particularly preferably at least 10% of the volume of the vibration absorber, so that there is enough space for these particles. In addition, the volume of the cavity can not exceed 95%, preferably not exceed 90%, and particularly preferably not exceed 80% or 70% of the volume of the vibration absorber, so that the surrounding wall can still be made sufficiently stable and rigid.

[0031] It is assumed that smaller particles can lead to a greater damping effect. Since the bonding forces between the particles (for example in the case of aluminum particles) may also have an influence on the damping properties, the particles should not be too small. It is therefore considered advantageous for the invention if the particles of the vibration absorber have an average particle size of at least 5 μm, preferably at least 10 μm and particularly preferably at least 20 μm. In addition, it is considered advantageous if the particles have an average particle size of at most 200 μm, preferably at most 150 μm and particularly preferably at most 100 μm.

[0032] Furthermore, it is assumed that spherical particles may be more suitable for cushioning. Therefore, a preferred embodiment of the invention provides that the particles have a round, spherical or rounded surface.

[0033] However, according to another embodiment of the invention, it can also be provided that the particles have angular or edged surfaces. As a result, the particles can interlock during vibration, thereby being able to cope with other excitation frequencies.

[0034] It is assumed that the material of the particles themselves has a relatively small influence on the damping effect, which enables the selection of particles with good properties with respect to laser beam welding. However, it is generally assumed that particles with a higher density have a better damping effect than particles with a lower density. In addition, particles made of harder materials or particles with a harder surface may lead to a better damping effect.

[0035] Therefore, metal alloy powders or metal particles are preferably selected for the particles, which have good properties with respect to laser beam welding and are not too cost-intensive. These particles can preferably be produced based on iron, copper, or aluminum, or can include corresponding alloys based on iron, copper, or aluminum. However, other materials may also be suitable, such as titanium alloys.

[0036] The vibration absorber and the chamber can have the same geometry, which is advantageous because in this way a uniform wall thickness and uniform damping properties of the wall can be achieved. In this way, the vibration absorber can be made correspondingly stable and stiff.

[0037] However, it is also possible to provide the cavity only in certain areas of the vibration absorber, for example in a thickened area with adjoining lateral projections for better fastening, in order to improve the fastening operation to the printed circuit board. Thus, the cavity can also have a different geometry than the vibration absorber itself, for example a rounded shape similar to a bubble.

[0038] The invention enables the vibration absorber to be particularly easily adapted geometrically to the corresponding conditions. Thus, it is possible to produce, for example, small cuboid vibration absorbers which can be flexibly attached in or on a printed circuit board. According to one embodiment of the invention, a cuboid vibration absorber is provided, for example, wherein the occupied area is a maximum of 20 mm*20 mm, preferably a maximum of 15 mm*15 mm, and particularly preferably a maximum of 10 mm*10 mm, and / or wherein the height is a maximum of 10 mm, preferably a maximum of 8 mm, and particularly preferably a maximum of 5 mm. Thus, very small vibration absorbers are also possible.

[0039] Obviously, a plurality of vibration absorbers with different sizes and different geometries can also be provided on a printed circuit board, also on both sides of the printed circuit board. It is obvious to those skilled in the art that the geometry can be selected according to the intended use.

[0040] Vibrations can be damped particularly well if the largest surface of the vibration absorber is in plane with the vibration plane of the element to be damped (in particular a printed circuit board) or the element causing the vibrations.

[0041] The filling volume of the chamber, and therefore the volume fraction of the cavity filled with unmelted particles, can be set as desired during the production process of the vibration absorber. Good damping properties can already be achieved if 30%, at least 40%, preferably at least 50%, particularly preferably at least 60%, 70%, 80%, or even 90%, 95%, 98%, or 99% of the chamber is filled with particles. The filling degree can be selected as a function of the excitation frequency to be damped and the particles. At lower frequencies, for example below 1 kHz, a lower filling degree is advantageous, at higher frequencies, for example above 1 kHz, a higher filling degree is advantageous.

[0042] Therefore, at lower excitation frequencies it may be advantageous that the chamber is not completely filled with particles. According to one embodiment of the invention, it is therefore provided that at least 1%, preferably at least 5% and particularly preferably at least 10% or even 20% of the chamber volume in the chamber is unfilled.

[0043] According to one embodiment of the invention, the vibration absorber is advantageously designed to damp excitation frequencies in a frequency range of 5 kHz to at least 200 kHz. According to another embodiment of the invention, the vibration absorber is designed such that the vibration absorber can damp excitation frequencies in a first frequency range below 100 kHz and / or in a second frequency range above 100 kHz. For this purpose, particles of different sizes can also be combined with one another.

[0044] In another aspect, the invention also comprises an electronic device, for example an electronic control unit for a braking system of a motor vehicle or motorcycle, comprising at least one printed circuit board having at least one vibration absorber as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Further details of the invention will become apparent from the description of the illustrated exemplary embodiments and the appended claims.

[0046] In the attached picture:

[0047] Figure 1 An oblique view showing an exemplary vibration absorber according to the present invention,

[0048] Figure 2 A semi-transparent view shows the Figure 1 Another oblique view of the vibration absorber,

[0049] Figure 3 shows an oblique view of a real vibration absorber,

[0050] Figure 4 An oblique view of a real vibration absorber is shown in cross-sectional view, and

[0051] Figure 5 A top view of a schematically illustrated exemplary printed circuit board is shown. DETAILED DESCRIPTION

[0052] In the following detailed description of preferred embodiments, for the sake of clarity, the same reference numerals represent substantially the same parts in or on these embodiments. However, in order to better illustrate the present invention, the preferred embodiments shown in the drawings are not always drawn to scale.

[0053] Figure 1 An oblique view of an exemplary vibration absorber 10 according to the present invention is shown, specifically for use as Figure 5 The vibration damping of the printed circuit board 20 is shown. Figure 2 A semi-transparent view shows the Figure 1 Another oblique view of the vibration absorber.

[0054] The vibration absorber 10 comprises a chamber 11 with a surrounding wall 12 which delimits a cavity 13 and in this case completely surrounds the cavity 13 .

[0055] The volume of the chamber 11 is at least 2%, preferably at least 5%, and particularly preferably at least 10% of the volume of the vibration absorber 10. In addition, the volume of the chamber 11 does not exceed 95%, preferably does not exceed 90%, and particularly preferably does not exceed 80% or 70% of the volume of the vibration absorber 10. In the present exemplary embodiment, the volume of the chamber 11 is approximately 40% of the volume of the vibration absorber 10.

[0056] The chamber 11 comprises particles 30. The wall 12 and the particles 30 have the same material composition.

[0057] Figure 3 An oblique view of a real vibration absorber is shown. Figure 4 Another oblique view of a real vibration absorber is shown in cross-sectional view. The particles are partially visible in the chamber 11.

[0058] Figure 5 2 shows a schematically illustrated exemplary printed circuit board 20 in a top view. The printed circuit board 20 comprises a sensor 21, which in the exemplary embodiment is designed as an acceleration sensor, and a semiconductor module 22. Obviously, this only represents an exemplary arrangement of the printed circuit board 20 for illustrative purposes. Figure 5In the example of FIG. 1 , the vibration absorber 10 is arranged on the same side of the printed circuit board 20 as the sensor 21 and the semiconductor module 22 . The vibration absorber 10 or an additional vibration absorber 10 may also be arranged on the side of the printed circuit board 20 opposite to the sensor 21 .

[0059] According to a refinement of the invention, the vibration absorber 10 can also be geometrically shaped with respect to the intended use. Thus, for example, an L-shaped, U-shaped, or even a toroidal or disk-shaped design of the vibration absorber 10 is also possible in order to surround the sensor 21 with the vibration absorber 10 on more than one side and improve the damping in this way. In particular, a U-shaped or toroidal vibration absorber 10 that can also be produced cost-effectively due to the production method can surround the sensor 21 on multiple sides or even completely surround the sensor, which can have a very positive effect on the damping properties.

[0060] The vibration absorber 10 can be placed at a small distance from the sensor 21, which is also considered to be beneficial for damping. It is possible to make contact with the sensor 21 from the opposite side of the printed circuit board, so that the vibration absorber 10 can be almost directly adjacent to the sensor 21.

[0061] The directly opposite arrangement of the sensor 21 on the side opposite the sensor 21 can also be advantageous, since in this way a small distance to the sensor 21 can also be achieved. It is obvious to the person skilled in the art that the sensor 21 mentioned here is only selected as an illustration for the sake of simplicity and that other vibration-sensitive components or electronic components are also conceivable here instead of the sensor 21.

[0062] The particles 30 of the vibration absorber 10 have an average particle size of at least 5 μm, preferably at least 10 μm, and particularly preferably at least 20 μm. In addition, the particles 30 have an average particle size of at most 200 μm, preferably at most 150 μm, and particularly preferably at most 100 μm. In an example, the average particle size of the particles is between 40 μm and 100 μm, for example approximately 50 μm, 60 μm, 70 μm, or 80 μm.

[0063] Furthermore, the particles 30 have a round, spherical or rounded surface.

[0064] In other embodiments, it can also be provided that the particles 30 have an angular or edged surface. A mixture of different surfaces is also conceivable.

[0065] Furthermore, the particles comprise metal alloy powders or metal particles, preferably based on iron, copper, or aluminum, or on alloys of these materials. Figure 3 The example shows a vibration absorber 10 based on an aluminum alloy.

[0066] exist Figure 2 In the exemplary embodiment of , the vibration absorber 10 and the chamber 11 have the same geometry, however, this is not mandatory for the invention.

[0067] exist Figure 2 or Figure 3 In the exemplary embodiment of the present invention, the vibration absorber 10 is formed in the shape of a cuboid, wherein the occupied area is less than 20 mm*20 mm, preferably less than 15 mm*15 mm, and particularly preferably less than 10 mm*10 mm. In addition, the height of the vibration absorber 10 is a maximum of 10 mm, preferably a maximum of 8 mm, and particularly preferably a maximum of 5 mm. According to the invention, a particularly small and compact vibration absorber 10 can be produced, which has dimensions of, for example, 5 mm x 10 mm x 10 mm.

[0068] At least 40%, preferably at least 50%, and particularly preferably at least 60% of the chamber 11 is filled with particles 30. Furthermore, the chamber 11 is not completely filled with particles 30, so that the particles can still move. According to one embodiment of the invention, at least 1%, preferably at least 5%, and particularly preferably at least 10% or even 20% of the volume of the chamber 11 is unfilled. Figure 3 In the exemplary embodiment of FIG. 5 , approximately 90% of the chamber is filled with particles 30 .

[0069] The vibration absorber 10 according to the present invention can damp vibrations in a frequency range of 5 kHz to at least 200 kHz. The excitation frequency can be in a first frequency range below 100 kHz and / or in a second frequency range above 100 kHz.

[0070] List of reference numerals:

[0071] 10. Vibration absorber

[0072] 11 Chamber

[0073] 12 walls

[0074] 13 Cavity

[0075] 20. PCB

[0076] 21 Acceleration sensor

[0077] 22IC

[0078] 30 capsules

Claims

1. A vibration absorber (10), in particular for damping vibrations of a printed circuit board (20), comprising a chamber (11) with a surrounding wall (12), which defines a cavity (13) and in this case preferably completely surrounds the cavity (13), wherein: the volume of the cavity (13) is at least 2%, preferably at least 5%, and particularly preferably at least 10% of the volume of the vibration absorber (10), wherein The volume of the cavity (13) does not exceed 95%, preferably does not exceed 90%, and particularly preferably does not exceed 80% or 70% of the volume of the vibration absorber (10), wherein - the chamber (11) contains particles (30), wherein The wall (12) and the particles (30) have the same material composition.

2. A printed circuit board (20), in particular for a control unit of a motor vehicle brake system and comprising a vibration absorber (10) according to claim 1.

3. The printed circuit board (20) according to claim 2, characterized in that: The printed circuit board (20) comprises at least one sensor (21), in particular an inertial sensor or an acceleration sensor.

4. A printed circuit board (20) according to any one of the preceding claims, characterized in that The vibration absorber (10) is arranged on a side of the printed circuit board (20) opposite to the sensor (21), preferably directly opposite to the sensor (21).

5. The printed circuit board (20) according to claim 2 or 3, characterized in that The vibration absorber (10) is arranged on the same side of the printed circuit board (20) as the sensor (21), preferably directly adjacent to the sensor (21).

6. A printed circuit board (20) according to any one of the preceding claims, characterized in that The particles (30) of the vibration absorber (10) have an average particle size of at least 5 μm, preferably at least 10 μm, and particularly preferably at least 20 μm, and / or the particles (30) have an average particle size of at most 200 μm, preferably at most 150 μm, and particularly preferably at most 100 μm.

7. A printed circuit board (20) according to any one of the preceding claims, characterized in that These particles (30) have a round, spherical or rounded surface.

8. The printed circuit board (20) according to any one of the preceding claims 2 to 6, characterized in that The particles (30) have angular or edged surfaces.

9. A printed circuit board (20) according to any one of the preceding claims, characterized in that These particles (30) consist of metal alloy powders or metal particles, preferably based on iron, copper or aluminium, or on alloys of these materials.

10. The printed circuit board (20) according to any one of the preceding claims, characterized in that The vibration absorber (10) and the chamber (11) have the same geometric shape.

11. The printed circuit board (20) according to any one of the preceding claims, characterized in that The vibration absorber (10) is made into a rectangular parallelepiped, wherein the occupied area is preferably at most 20mm*20mm, preferably at most 15mm*15mm, and particularly preferably at most 10mm*10mm, and / or wherein the height is at most 10mm, preferably at most 8mm, and particularly preferably at most 5mm.

12. The printed circuit board (20) according to any one of the preceding claims 2 to 10, characterized in that The vibration absorber (10) is formed into an L-shape, a U-shape, a ring shape, or a disc shape.

13. The printed circuit board (20) according to any one of the preceding claims, characterized in that The largest surface of the vibration absorber (10) is in plane with the vibration plane of the element to be damped or the element causing the vibrations.

14. A printed circuit board (20) according to any one of the preceding claims, characterized in that At least 40%, preferably at least 50%, particularly preferably at least 60% of the chamber (11) is filled with particles (30).

15. The printed circuit board (20) according to any one of the preceding claims, characterized in that The chamber (11) is not completely filled with particles (30), wherein at least 1%, preferably at least 5%, and particularly preferably at least 10% or even 20% of the volume of the chamber (11) is unfilled.

16. A printed circuit board (20) according to any one of the preceding claims, characterised in that The vibration absorber (10) is capable of damping vibrations in a frequency range of 5 kHz to at least 200 kHz, and / or wherein: The vibration absorber (10) is capable of buffering excitation frequencies within a first frequency range below 100 kHz and / or within a second frequency range above 100 kHz.

Images