Printed circuit board-heat sink assembly and method for producing a printed circuit board-heat sink assembly

Abstract

The invention relates to a printed circuit board-heat sink assembly (100), at least comprising a printed circuit board (10) with a plurality of metal layers (21, 22, 23, 24, 25, 26) between a front side (12) and a rear side (14), wherein the metal layers (21, 22, 23, 24, 25, 26) are spaced apart in a vertical extension (16) of the printed circuit board (10), wherein the vertical extension (16) is oriented transversely to a main extension plane of the printed circuit board (10), and wherein the printed circuit board (10) has at least one vertically extending insulation layer (20) which runs circumferentially in an outer edge region (34) and forms an electrically insulating edge region (34). At least one circumferential protective ring (30) is arranged within the edge region (34), which extends in a plane of one of the metal layers (21, 22, 23, 24, 25, 26).Furthermore, the printed circuit board-heat sink assembly (100) comprises a flat, extended heat sink (40), which is arranged on the rear side (14) of the printed circuit board (10) by means of a sintered layer (29). The invention further relates to a method for producing a printed circuit board-heat sink assembly (100).

Description

[0001] The invention relates to a printed circuit board-heat sink assembly and a method for producing a printed circuit board-heat sink assembly.

[0002] During the manufacturing process, printed circuit boards are typically first formed on a base plate and then milled out as a smaller unit. The milled unit is then sintered onto the heat sink. During milling, damage in the form of microcracks can occur in the outer edges of the printed circuit board, which can limit or destroy the insulation properties of the circuit elements and / or conductor tracks of the printed circuit board with respect to the heat sink. For example, this can lead to unwanted voltage breakdowns between the electrically conductive layers and the heat sink.

[0003] This problem is particularly relevant for the aforementioned combination of circuit board and heat sink, since the heat sink is usually made of metal due to thermal conductivity, and a high-voltage potential from the vehicle's high-voltage electrical system is typically present between the circuit board's conductor tracks and the heat sink. The heat sink is usually at ground potential. Thus, under normal operating conditions, a much higher voltage or potential difference exists between the heat sink and the conductor tracks (up to 4000V) than between adjacent circuit board conductor tracks (up to 1000V).

[0004] CN 209767903 U, for example, discloses a multilayer printed circuit board structure. The printed circuit board comprises an upper layer board, a double-sided board, and a lower layer board, arranged sequentially from top to bottom. The edge of the printed circuit board is provided with an aluminum alloy frame. A first heat dissipation layer is arranged between the upper layer board and the double-sided board. A second heat dissipation layer is arranged between the lower layer board and the double-sided board. A plurality of first so-called prepreg sheets are arranged in the first heat dissipation layer and the second heat dissipation layer. The edges of the first heat dissipation layer and the second heat dissipation layer are each provided with a second prepreg sheet. A first heat-conducting strip is connected between every two first prepreg sheets.A first thermal conduction strip is connected between each first prepreg sheet and the corresponding second prepreg sheet, and a second thermal conduction strip is connected between each second prepreg sheet and the aluminum alloy frame.

[0005] CN 207652773 U describes a printed circuit board with blind holes and buried holes. The printed circuit board comprises a base plate. The central part of the printed circuit board is equipped with a plurality of blind holes. The lower part of an inner coating is equipped with a semi-rigid preparation plate and a protective frame. The central part of the protective frame is equipped with several fins and a printed circuit board through-hole. Both ends are equipped with through-hole connectors, each arranged around the printed circuit board through-hole and the component mounting surface.

[0006] An object of the invention is to create an improved circuit board-heat sink assembly.

[0007] A further object is to provide a method for producing such a circuit board-heat sink assembly.

[0008] The above-mentioned objects are solved by the features of the independent claims.

[0009] Advantageous embodiments and advantages of the invention emerge from the further claims, the description and the drawing.

[0010] According to one aspect of the invention, a printed circuit board-heat sink assembly is proposed, at least comprising a printed circuit board with a plurality of metal layers between a front side and a back side of the printed circuit board, wherein the metal layers are spaced apart in a vertical extension of the printed circuit board, wherein the vertical extension is oriented transversely and in particular perpendicular to a main extension plane of the printed circuit board, and wherein the printed circuit board has at least one vertically extending insulation layer extending circumferentially in an outer edge region, which forms an electrically insulating edge region. At least one circumferential protective ring is arranged within the edge region, which extends in a plane of one of the metal layers. The printed circuit board-heat sink assembly further comprises a flat heat sink, which is arranged on the back side of the printed circuit board by means of a sintered layer.

[0011] The proposed PCB-heat sink assembly provides a vertical insulation layer positioned at the edge of the PCB, forming an insulated edge region. The PCB itself is designed as a multilayer PCB with a plurality of vertically spaced metal layers.

[0012] This insulation layer preferably extends vertically between the uppermost metal layer arranged on the front side of the circuit board and the thermally conductive electrical insulation layer arranged on the back side. The insulation layer runs along the outer circumference or edge region of the circuit board and surrounds and / or encloses the inner region for circuit elements with respect to two of three spatial directions in the lateral extension of the circuit board. For example, several spaced-apart, vertical insulation layers can be provided in the edge region, for example one directly at the edge of the circuit board and another spaced from the edge, but still in the edge region of the circuit board, or a continuous, wide insulation layer that extends from the edge into the interior of the circuit board in the edge region.

[0013] Furthermore, at least one guard ring is provided, which is arranged within the insulated edge region formed by the insulation layer. The guard ring can, for example, be arranged adjacent to the one or more insulation layers and / or be surrounded by or embedded in an insulation layer. This guard ring extends in a plane in which an electrically conductive metal layer also lies, i.e., in a plane parallel to the main extension plane of the circuit board.

[0014] The microcracks described above at the edge of the circuit board, which arise during milling, generally form despite the presence of a protective ring and / or insulation layer. However, the effects of these microcracks described above can advantageously be prevented, or the formation of the microcracks can be mitigated or stopped, using at least one protective ring and the insulation layer. The protective ring acts as a crack stopper during or after milling. Voltage breakdowns between the circuit elements in the interior of the circuit board and the heat sink can be prevented, thereby increasing the reliability of the circuit board-heat sink assembly.

[0015] According to an advantageous embodiment of the circuit board-heat sink assembly, the at least one protective ring can be adjacent to the at least one insulation layer and / or surrounded by the at least one insulation layer, and / or embedded in the at least one insulation layer. Microcracks can advantageously be absorbed in this way, and reliable electrical insulation from the area of ​​the circuit elements on the circuit board can be ensured. The protective ring can thus advantageously be electrically insulated from the inner area of ​​the circuit board for circuit elements by means of the aforementioned insulation layer.

[0016] According to an advantageous embodiment of the circuit board-heat sink assembly, a plurality of protective rings can be arranged within the edge region, which are spaced apart along the vertical extent of the circuit board and extend in a plane of a corresponding metal layer. Preferably, several protective rings can be provided, which are spaced apart along the vertical extent of the circuit board and are each assigned to an electrically conductive metal layer or extend at its level. Advantageously, the protective rings can be part of the corresponding metal layer.

[0017] According to an advantageous embodiment of the circuit board-heat sink assembly, the at least one protective ring can be made of an electrically conductive material, in particular a metallic material. Preferably, the protective ring can be made of copper, a particularly highly conductive material.

[0018] According to an advantageous embodiment of the printed circuit board-heat sink assembly, the at least one protective ring can have a width of at least 100 µm in the main extension plane of the printed circuit board and a thickness of at least 15 µm and in particular at least 17 µm in the vertical extension. Alternatively or additionally, a distance of the at least one protective ring from an outer edge of the printed circuit board can be at least 100 µm. Alternatively or additionally, a distance of the at least one protective ring from an inner edge of the edge region can be at least 1500 µm. In this way, a particularly favorable protective effect of the protective ring and the insulation layer against the effects of microcracks can be ensured.

[0019] Advantageously, a minimum width of the technology used in structuring the circuit board can be used as the width of the guard ring, but a larger width can also be used.

[0020] According to an advantageous embodiment of the printed circuit board-heat sink assembly, a continuous, particularly thermally conductive, electrical insulation layer can be arranged on the back of the printed circuit board in the main extension plane of the printed circuit board, followed by a final metal layer, followed by a sintered layer, and followed by the heat sink. The second-to-last metal layer in the vertical extension and / or the corresponding protective ring can be adjacent to the electrical insulation layer. This advantageously ensures reliable electrical insulation from the inner area for circuit elements on the printed circuit board, while simultaneously ensuring good heat dissipation from the circuit elements to the heat sink.

[0021] According to an advantageous embodiment of the circuit board-heat sink assembly, at least two of the plurality of guard rings can be electrically connected to one another along their vertical extension by means of vertical vias. This allows for reliable electrical shielding of the inner area for circuit elements.

[0022] A through-hole plating, or via, is a vertical electrical connection between the metal layers of a printed circuit board. The connection is usually realized through an internally metallized hole in the substrate. Rivets and pins are also used in rare cases.

[0023] According to an advantageous embodiment of the circuit board-heat sink assembly, at least one of several guard rings can be electrically connected to the heat sink. Optionally, the guard ring can also be electrically connected directly to the heat sink, for example, via appropriate vias. This results in a defined potential state for the guard ring, since it then assumes the same potential state as the heat sink.

[0024] The guard ring runs along the outer edges of the circuit board. Optionally, all metal layers of the guard ring can be electrically connected to each other. If an electrical connection occurs due to microcracks or other failure mechanisms at the edge, the guard ring is at the same potential as the heat sink. Optionally, the guard ring can also be electrically connected directly to the heat sink.

[0025] According to an advantageous embodiment of the circuit board-heat sink assembly, a monitoring device can be provided for determining leakage currents between circuit elements arranged on the circuit board and / or the at least one guard ring and / or the heat sink. A monitoring circuit can advantageously be implemented that checks the electrical connection between the guard ring and the heat sink and reports the status to a control unit.

[0026] According to a further aspect of the invention, a method for producing a printed circuit board-heat sink assembly is proposed, at least comprising providing a printed circuit board which has a plurality of metal layers between a front side and a back side of the printed circuit board, wherein the metal layers are spaced apart in a vertical extension of the printed circuit board and wherein the vertical extension is oriented transversely and in particular perpendicular to a main extension plane of the printed circuit board; introducing at least one vertically extending insulation layer into the printed circuit board, which insulation layer runs circumferentially in an outer edge region and forms an electrically insulating edge region; arranging at least one protective ring within the edge region, which extends in a plane of a metal layer; providing a flatly extended heat sink;Applying a sintered layer to the back of the circuit board and / or a side of the heat sink facing the circuit board; bringing the circuit board and heat sink together and pressing them together at a predefined temperature and pressure.

[0027] Further advantages will become apparent from the following description of the drawings. The drawings illustrate an exemplary embodiment of the invention. The drawings, the description, and the claims contain numerous features in combination. Those skilled in the art will also expediently consider the features individually and combine them into useful further combinations.

[0028] Showing: Fig. 1 a plan view of a printed circuit board-heat sink assembly according to an embodiment of the invention; and Fig. 2 a sectional view through the circuit board-heat sink assembly in the section plane AA according to Fig. 1.

[0029] In the figures, identical or similar components are numbered with the same reference numerals. The figures show only examples and are not to be understood as limiting.

[0030] Fig. 1 shows a plan view of a printed circuit board-heat sink assembly 100 according to an embodiment of the invention. Fig. 2 is a sectional view through the circuit board-heat sink assembly 100 in the section plane AA according to Fig. 1 shown.

[0031] The printed circuit board-heat sink assembly 100 comprises a printed circuit board 10 with a plurality of metal layers 21, 22, 23, 24, 25, 26 between a front side 12 and a rear side 14. The metal layers 21, 22, 23, 24, 25, 26 are spaced apart in a vertical extension 16 of the printed circuit board 10, wherein the vertical extension 16 is oriented transversely and in particular perpendicularly to a main extension plane of the printed circuit board 10.

[0032] The printed circuit board 10 is formed from printed circuit board material 18, for example a flame-retardant composite material consisting of epoxy resin and glass fiber fabric, in which the metal layers 21, 22, 23, 24, 25 are embedded.

[0033] The metal layers 21, 22, 23, 24, 25, 26 can be formed, for example, from copper and serve to form conductor tracks in the printed circuit board 10 for electrically contacting circuit components, which can be arranged in the area 56 for circuit elements on the front side 12 of the printed circuit board 10.

[0034] The printed circuit board 10 has a vertically extending insulation layer 20 which runs around an outer edge region 34 and forms an electrically insulating edge region 34.

[0035] A plurality of protective rings 30 are arranged within the edge region 34. The protective rings 30 are spaced apart along the vertical extent 16 of the circuit board 10 and each extend in a plane of a corresponding metal layer 21, 22, 23, 24, 25.

[0036] Furthermore, the printed circuit board-heat sink assembly 100 comprises a flat heat sink 40, which is arranged on the back side 14 of the printed circuit board 10 by means of a sintered layer 29.

[0037] In the Fig. 1 and Fig. In the embodiment shown in Figure 2, the protective rings 30 are surrounded by the insulation layer 20 and embedded in the insulation layer 20.

[0038] The guard rings 30 are formed from an electrically conductive material, in particular a metallic material. Advantageously, the guard rings 30 can be formed from the same material as the metal layers 21, 22, 23, 24, 25, 26 from which the conductor tracks of the circuit board 10 are formed. Advantageously, the guard rings 30 can be formed from the metal layers 21, 22, 23, 24, 25 from which the conductor tracks of the circuit board 10 are also formed.

[0039] For typical dimensions of printed circuit boards 10 for electronic components, the protective rings 30 can, for example, have a width 54 of at least 100 µm in the main extension plane of the printed circuit board 10 and a thickness of at least 15 µm in the vertical extension 16. A distance 50 of the protective rings 30 from an outer edge 36 of the printed circuit board 10 can be at least 100 µm. A distance 52 of the protective rings 30 from an inner edge 38 of the edge region 34 can be at least 1500 µm.

[0040] In this way, a particularly favorable protective effect of the protective rings 30 and the insulation layer 20 against the effects of microcracks when milling out the printed circuit board 10 can be ensured.

[0041] Advantageously, a minimum width of the technology used in structuring the printed circuit board 10 can be used as the width of the protective rings 30, but a larger width can also be used advantageously.

[0042] As in Fig. As can be seen in Figure 2, a continuous, particularly thermally conductive, electrical insulation layer 28 can be arranged on the rear side 14 of the circuit board 10 in the main extension plane of the circuit board 10. This can be followed by a final continuous metal layer 26. A sintered layer 29 can be applied to this final metal layer 26, by means of which the heat sink 40 can be sintered onto the circuit board 10.

[0043] The penultimate metal layer 25 in the vertical extension 16 and / or the corresponding protective ring 30 can advantageously adjoin the electrical insulation layer 28.

[0044] As shown in the illustrated embodiment, the protective rings 30 can be electrically conductively connected to one another in the vertical extension by means of vertical vias 31.

[0045] Optionally, at least one protective ring 30 of a plurality of protective rings 30 can be electrically connected to the heat sink 40.

[0046] Furthermore, a monitoring device for determining leakage currents between circuit elements arranged on the circuit board 10 and / or the at least one protective ring 30 and / or the heat sink 40 can optionally be provided.

[0047] According to the proposed method, the illustrated circuit board-heat sink assembly 100 can be manufactured by first providing the circuit board 10, which has a plurality of metal layers 21, 22, 23, 24, 25, 26 between the front side 12 and the back side 14 of the circuit board 10.

[0048] The metal layers 21, 22, 23, 24, 25, 26 are spaced apart in the vertical extension 16 of the circuit board 10.

[0049] In this case, at least one insulation layer 20 extending vertically around the outer edge region 34 is introduced into the circuit board 10, which forms an electrically insulating edge region 34.

[0050] Furthermore, at least one protective ring 30 is arranged within the edge region 34, which extends in a plane of a metal layer 21, 22, 23, 24, 25, 26.

[0051] A flat heat sink 40 is provided.

[0052] A sintered layer 29 is applied to the back side 14 of the circuit board 10 and / or the side 42 of the heat sink 40 facing the circuit board 10.

[0053] The printed circuit board 10 and the heat sink 40 are then brought together and pressed together in the sintering process at a predeterminable temperature and a predeterminable pressure. List of reference symbols 10 circuit board 12 Front 14 Back 16 vertical extension 18 PCB material 20 insulation layer 21 metal layers 22 metal layers 23 metal layers 24 metal layers 25 metal layers 26 metal layers 28 Insulation layer 29 Sinter layer 30 protective ring 31 vias 34 Marginal area 36 outer edge 38 inner edge 40 heat sinks 42 pages 50 distance 52 distance 54 width 56 Area for circuit elements 100 PCB heatsink assembly QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] CN 209767903 U

[0004] CN 207652773 U

[0005]

Claims

[1] Printed circuit board heat sink assembly (100), comprising at least a printed circuit board (10) having a plurality of metal layers (21, 22, 23, 24, 25, 26) between a front side (12) and a rear side (14) of the printed circuit board (10), wherein the metal layers (21, 22, 23, 24, 25, 26) are spaced apart in a vertical extension (16) of the printed circuit board (10), wherein the vertical extension (16) is oriented transversely to a main extension plane of the printed circuit board (10), wherein the printed circuit board (10) has at least one vertically extending insulation layer (20) extending around an outer edge region (34) and forming an electrically insulating edge region (34), wherein at least one circumferential protective ring (30) is arranged within the edge region (34), which extends in a plane of one of the metal layers (21, 22, 23, 24, 25, 26), and a flat heat sink (40) which is arranged on the back (14) of the printed circuit board (10) by means of a sintered layer (29). [2] Printed circuit board heat sink assembly according to claim 1, wherein the at least one protective ring (30) adjoins the at least one insulation layer (20) and / or is surrounded by the at least one insulation layer (20), and / or is embedded in the at least one insulation layer (20). [3] Printed circuit board heat sink assembly according to claim 1 or 2, wherein a plurality of protective rings (30) are arranged within the edge region (34), which are spaced apart along the vertical extent (16) of the printed circuit board (10) and which extend in a plane of a corresponding metal layer (21, 22, 23, 24, 25, 26). [4] Printed circuit board heat sink assembly according to one of the preceding claims, wherein the at least one protective ring (30) is formed from an electrically conductive material, in particular a metallic material. [5] Printed circuit board heat sink assembly according to one of the preceding claims, wherein the at least one protective ring (30) has a width (54) of at least 100µm in the main extension plane of the printed circuit board (10) and a thickness of at least 15µm in the vertical extension (16), and / or wherein a distance (50) of the at least one protective ring (30) from an outer edge (36) of the printed circuit board (10) is at least 100µm, and / or wherein a distance (52) of the at least one protective ring (30) to an inner edge (38) of the edge region (34) is at least 1500µm. [6] Printed circuit board-heat sink assembly according to one of the preceding claims, wherein on the rear side (14) of the printed circuit board (10) there is arranged an electrical insulation layer (28) which is continuous in the main extension plane of the printed circuit board (10), in particular a thermally conductive one, followed by a last metal layer (26), followed by a sintered layer (29), followed by the heat sink (40), wherein the penultimate metal layer (25) in the vertical extension (16) and / or the corresponding protective ring (30) adjoins the electrical insulation layer (28). [7] Printed circuit board heat sink assembly according to one of claims 3 to 6, wherein at least two protective rings (30) of the plurality of protective rings (30) are electrically conductively connected to one another in the vertical extension by means of vertical vias (31). [8] Printed circuit board heat sink assembly according to one of the preceding claims, wherein at least one protective ring (30) of a plurality of protective rings (30) is electrically connected to the heat sink (40). [9] Printed circuit board-heat sink assembly according to one of the preceding claims, wherein a monitoring device is provided for determining leakage currents between circuit elements arranged on the printed circuit board (10) and / or the at least one protective ring (30) and / or the heat sink (40). [10] Method for producing a printed circuit board heat sink assembly (100) according to one of the preceding claims, at least comprising Providing a printed circuit board (10) having a plurality of metal layers (21, 22, 23, 24, 25, 26) between a front side (12) and a back side (14), wherein the metal layers (21, 22, 23, 24, 25, 26) are spaced apart in a vertical extension (16) of the printed circuit board (10) and wherein the vertical extension (16) is oriented transversely to a main extension plane of the printed circuit board (10); Introducing at least one vertically extending insulation layer (20) into the printed circuit board (10) which extends circumferentially in an outer edge region (34) and forms an electrically insulating edge region (34); Arranging at least one protective ring (30) within the edge region (34) which extends in a plane of a metal layer (21, 22, 23, 24, 25, 26); Providing a flat heat sink (40); Applying a sintered layer (29) to the back side (14) of the circuit board (10) and / or a side (42) of the heat sink (40) facing the circuit board (10); Bringing together the printed circuit board (10) and the heat sink (40) and pressing them together under a predeterminable temperature and a predeterminable pressure.

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