Printed circuit board arrangement for a motor vehicle headlamp

Description

[0001] The invention relates to a printed circuit board arrangement for a motor vehicle headlight, comprising a printed circuit board and a heat sink which is in thermal contact with the printed circuit board and is designed to dissipate heat from the printed circuit board, wherein the printed circuit board and the heat sink are spaced apart from one another at least in regions such that a gap is formed between the printed circuit board and the heat sink, wherein the printed circuit board is fastened to the heat sink with at least one fastening device while maintaining the gap, which fastening device comprises at least the following: a fastening opening with an opening size which completely penetrates the circuit board, a recess which is arranged on the heat sink and which has an insertion opening, and a fastening element with a longitudinal axis, wherein the fastening element has an engagement portion and a contact portion opposite along the longitudinal axis,

[0002] The invention further relates to a motor vehicle headlight comprising at least one printed circuit board arrangement according to the invention.

[0003] In order to thermally connect a printed circuit board and an associated heat sink, the printed circuit board is mechanically applied to the heat sink. Manufacturing errors, among other things, can result in the printed circuit board not being flush with the heat sink in every area and a gap or gap space being present between the printed circuit board and the heat sink in some areas.

[0004] Common state-of-the-art fastening methods for attaching circuit boards to heat sinks include screws or rivets.

[0005] DE112019001810T5, US2019 / 223318 A1, DE102007034123 A1 and WO2004 / 070839 A2 show such printed circuit board arrangements.

[0006] However, the use of such fastening devices can lead to the circuit board being bent in the fastening area due to the constant contact pressure of the screws or rivets, which can cause components and their electrical connections to the circuit board to either break or disrupt or destroy the conductor tracks and components arranged on the circuit board.

[0007] Due to this deformation, which is particularly pronounced near the mounting points, electronic components can only be assembled at a greater distance from the mounting points. Thus, a mounting device that reduces the contact pressure and thus also the deformation of the circuit board would allow the distance between the electronic component and the mounting point to be reduced, thus minimizing the overall size of the circuit board.

[0008] It is an object of the invention to provide an improved printed circuit board assembly.

[0009] This object is achieved in that the fastening opening and the insertion opening are arranged in such a way that they overlap, that the fastening element is received by the fastening opening and the insertion opening, wherein the fastening element penetrates the printed circuit board via the fastening opening, and wherein the fastening element is deformed by exerting a force on the engagement portion and a counter-force directed against it on the contact portion such that the fastening element is positively clamped in the recess and a first and a second widening portion of the fastening element are formed, wherein the first widening portion extends into the gap between the circuit board and the heat sink radially to the longitudinal axis of the fastening element, wherein the first widening portion extends beyond the opening size of the fastening opening into the gap such that the first widening portion supports the circuit board in order to maintain the distance between the circuit board and the heat sink in the region of the fastening opening, and wherein the second widening portion extends radially to the longitudinal axis of the fastening element,wherein the second widening portion extends beyond the opening size of the fastening opening in order to maintain the distance between the circuit board and the heat sink in the region of the fastening opening, and wherein the circuit board is positively clamped between the first and second widening portions of the fastening element in the region of the fastening opening.

[0010] It can be provided that the fastening element is pin-shaped.

[0011] It can be provided that the fastening element is made of plastic or of a metal, preferably of aluminum or an aluminum alloy.

[0012] In general, it should be noted that the material of the fastening element should be selected such that its modulus of elasticity is lower than that of the heat sink. Furthermore, the expansion coefficients of the different materials should be selected such that the connection cannot break apart within the application temperature range, even under severe temperature fluctuations. Furthermore, the environmental influences encountered in the automotive sector, such as significant temperature fluctuations and vibrations, should be considered when selecting the material of the fastening element.

[0013] It can be provided that a heat-conducting material is arranged in the gap to enable a better thermal connection between the circuit board and the heat sink.

[0014] It can be provided that the recess comprises at least one undercut, so that the fastening element is secured against movement along the longitudinal axis by the positive connection between the fastening element and the recess.

[0015] It can be provided that the recess is designed as a blind hole on the heat sink, wherein the blind hole has an abutment section, against which abutment section the contact section of the fastening element rests and is provided for exerting the counterforce.

[0016] It can be provided that the recess is designed as a recess that completely penetrates the heat sink.

[0017] It can be provided that the printed circuit board assembly comprises an abutment element against which the contact section of the fastening element rests and is intended to exert the counterforce. The abutment element is formed by a component separate from the heat sink. It can also be provided that after the force has been applied to the fastening element and after the resulting positive connection has been established, said abutment element can be removed from the heat sink again if necessary.

[0018] It can be provided that the fastening element is trapezoidal in cross section parallel to the longitudinal axis, wherein preferably two leg elements are arranged at a distance transverse to the longitudinal axis from one another at the base of the trapezoid.

[0019] The fastening element may be formed by extrusion. The term "extrusion" refers to the process whereby a force acting on a material creates a compressive stress within the material. If the force exceeds the material's yield point, it causes the material to yield. When the force is removed from the component, a plastic deformation of the component remains after elastic recovery.

[0020] It can be provided that at least one spacer is arranged in the gap between the heat sink and the circuit board in order to ensure that the gap is maintained, preferably in order to ensure that a minimum gap height is maintained between the heat sink and the circuit board.

[0021] Furthermore, the object is also achieved by a motor vehicle headlight comprising at least one printed circuit board arrangement according to the invention.

[0022] The invention is explained in more detail below with reference to exemplary drawings. Fig. 1 an exemplary circuit board assembly in a view from above, wherein the circuit board assembly comprises a heat sink and a circuit board fastened thereto by means of fastening devices, Fig. 2A an exemplary fastening device in a cross-section of the printed circuit board arrangement, wherein the fastening device comprises a fastening opening in the printed circuit board, a recess in the heat sink and a fastening element, which fastening element is deformed by exerting a force and counterforce, Fig. 2B the exemplary fastening device from Fig. 2A before the force and counterforce have been applied to the fastener, Fig. 3A the exemplary fastening device from Fig. 3B after the force and counterforce have been applied to the fastener, Fig. 3Banother exemplary fastening device in a state before force has been exerted on the fastening element, Fig. 4A another example of a fastening device before force is applied to deform the fastening element, Fig. 4B the example from Fig. 4A after deformation of the fastener, Fig. 5 another example of a fastening device, wherein the fastening device further comprises spacers, and Fig. 6 several examples of possible fastening elements.

[0023] Fig. 1 shows an example circuit board arrangement 10 for one

[0024] Motor vehicle headlight, comprising a printed circuit board 50 and a heat sink 60 in a top view, with the heat sink aligned with the circuit board 50 in thermal contact and is designed to transfer the heat generated by the operation of the circuit board 50heat generated by the circuit board 50 to be paid.

[0025] As in Fig. 2a or Fig. 2b As can be seen, the circuit board 50 and the heat sink 60 at least in some areas with a distance X spaced apart so that between the circuit board 50 and the heat sink 60 a gap 70 is formed, whereby the circuit board 50 on the heat sink 60 with multiple fastening devices 80 while maintaining the gap space 70 Examples of possible designs of fastening devices 80 are shown in the following figures.

[0026] The fastening devices 80 each include a mounting hole 100 with an opening size which mounting opening 100 the circuit board 50 completely penetrated, a recess 200,which on the heat sink 60 is arranged and an insertion opening 210 has a fastening element 300 with a longitudinal axis A, whereby the fastening element 300 an intervention section 310 and one along the longitudinal axis A opposite section of the facility 320 as exemplified in Fig. 2A can be seen. In the example shown, the fastening element 300 pin-shaped, although other shapes are also conceivable, such as a cross-section parallel to the longitudinal axis A trapezoidal fastener. Other shapes are also available in Fig. 6 shown.

[0027] The fastening element 300 In the examples shown, it is made of aluminum or an aluminum alloy.

[0028] The mounting opening 100 and the insertion opening 210arranged in such an overlapping manner that the fastening element 300 through the mounting hole 100 and the insertion opening 210 is accommodated, whereby the fastening element 300 the circuit board 50 via the mounting hole 100 enforced.

[0029] The fastening element 300 is by exerting a force F at the intervention section 310 and an opposing counterforce on the system section 320 formed in such a way that the fastening element 300 in the recess 200 is clamped positively and a first and a second widening section 330a, 330b of the fastener 300 is formed. In the examples shown, the forming was carried out by extrusion.

[0030] In the example shown in Fig. 2A is the recess 200 as a blind hole on the heat sink 60formed, wherein the blind hole has an abutment section 230 has, at which abutment section 230 the investment section 320 of the fastener 300 and is intended to exert the counterforce.

[0031] The first widening section 330a extends into the gap space 70 between the circuit board 50 and the heat sink 60 radial to the longitudinal axis A of Fastening element 300, The first widening section 330a about the opening size of the mounting hole 100 out into the gap space 70 extends so that the first widening section 330a the circuit board 50 supports to maintain the distance X between the circuit board 50 and the heat sink 60 in the area of the mounting opening 100 to maintain.

[0032] The second widening section 330b extends radially to the longitudinal axis A of Fastening element 300, The second widening section 330b about the opening size of the mounting hole 100 extends beyond to determine the distance X between the circuit board 50 and the heat sink 60 in the area of the mounting opening 100 and to maintain the circuit board 50 against movement in the direction opposite to the recess 200 to secure.

[0033] The circuit board is 50 between the first and second widening sections 330a, 330b of the fastener 300 positively clamped.

[0034] Fig. 2B shows the fastening device 80 out of Fig. 2A in a state before the fastener 300 is formed or deformed by means of extrusion.

[0035] Fig. 3A shows another example of a fastening device 80, where the above statement also applies. The difference to the previous example is that the recess 200 as a heat sink 60 fully penetrating recess 200 is formed, and that the recess 200 an undercut 220 so that the fastening element 300 through the positive connection between the fastening element 300 and the recess 200 against movement along the longitudinal axis A is additionally secured against jamming.

[0036] Fig. 3B shows the fastening device 80 out of Fig. 3A in a state before the fastener 300 is formed or deformed by means of extrusion, whereby a temporarily arranged counterholder or abutment element is used to generate the counterforce 500is intended.

[0037] Fig. 4A and Fig. 4B show another example of a fastening device 80, To generate the counterforce, the recess 200 an abutment section 230 which also functions as an undercut in the sense of the previous example.

[0038] Fig. 5 shows another example of an exemplary fastening device 80, The above also applies to this example. The difference to the previous examples, especially the example shown in Fig. 2A or Fig. 2B is that the fastening device 80 spacers 400 which in the gap space 70 between the heat sink 60 and the circuit board 50 are arranged to maintain the gap space 70 to further improve or ensure.

[0039] Fig. 6shows possible designs of the fastening element 300, The scope of protection does not refer exclusively to the geometric shapes shown here. A particularly favorable shape for the fastening element is the first shape from the right in Fig. 6 In this case, the fastening element is trapezoidal in cross section parallel to the longitudinal axis, with two leg elements being arranged at a distance transverse to the longitudinal axis from one another at the base of the trapezoid. LIST OF REFERENCE SYMBOLS

[0040] PCB layout 10 circuit board 50 heat sink 60 gap space 70 Fastening devices 80 Mounting opening 100 recess 200 insertion opening 210 undercut 220 Abutment section 230 Fastening element 300 Intervention section 310 Investment section 320 First widening section 330a Second widening section 330b spacers 400 Counterholder 500 Longitudinal axis A Distance X

Claims

1. Printed circuit board arrangement (10) for a motor vehicle headlight, comprising a printed circuit board (50) and a heat sink (60) which is in thermal contact with the printed circuit board (50) and is designed to dissipate heat from the printed circuit board (50), the printed circuit board (50) and the heat sink (60) being spaced apart from one another by a distance (X) at least in some regions in such a way so that a gap space (70) is formed between the printed circuit board (50) and the heat sink (60), the printed circuit board (50) being fastened to the heat sink (60) by at least one fastening device (80) while maintaining the gap space (70), which at least one fastening device (80) comprises - a fastening opening (100) with an opening size, which fastening opening (100) completely penetrates the printed circuit board (50), - a recess (200) which is arranged on the heat sink (70) and which has an insertion opening (210), and - a fastening element (300) having a longitudinal axis (A), the fastening element (300) having an engagement section (310) and an abutment section (320) located opposite along the longitudinal axis (A), characterized in that the fastening opening (100) and the insertion opening (210) are arranged to overlap in such a way that the fastening element (300) is received by the fastening opening (100) and the insertion opening (210), the fastening element (300) passing through the printed circuit board (50) via the fastening opening (100), and wherein the fastening element (300) is deformed by exerting a force (F) at the engagement portion (310) and an opposing force at the contact portion (320) in such a way that the fastening element (300) is positively clamped in the recess (200) and a first and a second widening portion (330a, 330b) of the fastening element (300) are formed, wherein the first widening portion (330a) extends into the gap space (70) between the printed circuit board (50) and the heat sink (60) radially to the longitudinal axis (A) of the fastening element (300), wherein the first widening portion (330a) extends into the gap space (70) beyond the opening size of the fastening opening (100) in such a manner so that the first widening section (330a) supports the printed circuit board (50) in order to maintain the distance (X) between the printed circuit board (50) and the heat sink (60) in the region of the fastening opening (100), and wherein the second widening portion (330b) extends radially to the longitudinal axis (A) of the fastening element (300), wherein the second widening portion (330b) extends beyond the opening size of the fastening opening (100) to maintain the distance (X) between the printed circuit board (50) and the heat sink (60) in the region of the fastening opening (100), and to secure the printed circuit board (50) against movement in the direction opposite to the recess (200), and wherein the printed circuit board (50) is positively clamped between the first and the second widening portion (330a, 330b) of the fastening element (300).

2. Printed circuit board arrangement according to claim 1, characterized in that the fastening element (300) is pin-shaped.

3. Printed circuit board arrangement according to claim 1 or 2, characterized in that the fastening element (300) is made of plastic or of a metal, preferably made of aluminium or an aluminium alloy.

4. Printed circuit board arrangement according to one of claims 1 to 3, characterized in that the recess (200) comprises at least one undercut (220), so that the fastening element (300) is secured against movement along the longitudinal axis (A) by the positive connection between the fastening element (300) and the recess (200).

5. Printed circuit board arrangement according to one of claims 1 to 4, characterized in that the recess (200) is designed as a blind hole on the heat sink (60), the blind hole having an abutment section (230), against which abutment section (230) the contact section (320) of the fastening element (300) bears and is provided for exerting the counterforce.

6. Printed circuit board arrangement according to one of claims 1 to 4, characterized in that the recess (200) is designed as a recess (200) completely penetrating the heat sink (60).

7. Printed circuit board arrangement according to one of claims 1 to 6, characterized in that the fastening element (300) is trapezoidal in cross-section parallel to the longitudinal axis (A), two leg elements preferably being arranged at a distance from one another transversely to the longitudinal axis (A) at the base of the trapezoid.

8. Printed circuit board arrangement according to one of claims 1 to 7, characterized in that the fastening element (300) is formed by extrusion.

9. Printed circuit board arrangement according to one of claims 1 to 8, characterized in that at least one spacer (400) is arranged in the gap space (70) between the heat sink (60) and the printed circuit board (50) in order to ensure that the gap space (70) is maintained.

10. Printed circuit board arrangement according to one of claims 1 to 9, characterized in that the printed circuit board arrangement (10) comprises an abutment element (500) against which the abutment portion (320) of the fastening element (300) bears and is provided for exerting the counterforce, the abutment element (500) being formed by a component separate from the heat sink, the abutment element (500) being removable from the heat sink after the force has been exerted on the fastening element (300) and after the resulting form fit has been created.

11. Motor vehicle headlamp, comprising at least one printed circuit board arrangement (10) according to one of claims 1 to 10.