High-current circuit

Abstract

High-current circuit having a printed circuit board comprising a non-conductive substrate 2, a conductor layer 4 applied to the substrate 2 and an insulation layer 6 applied to the conductor layer, contact pads 8, 10, 12, 20, 22, 24 in each case interrupting the insulation layer 6 being arranged on both sides of the conductor plate, and the contact pads 8, 10, 12, 20, 22, 24 making contact with one another via vias 14 through the substrate 2, and the vias 14 being arranged in the area of the contact pads 8, 10, 12, 20, 22, 24, 10, 12, 20, 22, 24, characterized in that at least a first one of the contact pads 8 is arranged on a first side of the printed circuit board and a first semiconductor switch 28 is connected directly to at least a second one of the contact pads 20 on a second side of the printed circuit board, and in that the semiconductor switch 28 is connected to the first contact pad 8 directly via the vias 14 and the second contact pad 20, without further conductor tracks.

Claims

1-20. (canceled)

21. A high-current circuit, in particular motor vehicle high-current circuit, comprising: a printed circuit board made from a non-conductive substrate, a conductor layer applied to the substrate and an insulating layer applied to the conductor layer, wherein contact pads which break through the insulation layer are arranged on both sides of the printed circuit board, and the contact pads are in contact with one another via vias through the substrate, the vias being arranged in the area of the contact pads, wherein at least a first one of the contact pads is arranged on a first side of the printed circuit board; multiple semiconductor switches directly connected to second contact pads on a second side of the printed circuit board, and the semiconductor switch is connected to the first contact pad directly via the vias and the second contact pad, without further conductor tracks; wherein the second contact pads of power terminals of a plurality of the semiconductor switches are arranged on the second side of the printed circuit board isolated from each other and neighbouring each other; and wherein the first contact pad is connected with two or more of the second contact pads via a plurality of vias and arranged with their entire surface on the first side of the printed circuit board.

22. High-current circuit according to claim 21, wherein the areas of the first and second contact pads are arranged one above the other on the two sides of the printed circuit board.

23. High-current circuit according to claim 21, further comprising a flat part, on the first side of the printed circuit board, directly connected to the first of the contact pads.

24. High-current circuit according to claim 21, wherein on the second side of the printed circuit board at least one contact terminal of the semiconductor switch is directly connected to the first of the contact pads.

25. High-current circuit according to claim 21, wherein two of the semiconductor switches are electrically connected in series with one another on the second side of the printed circuit board, a third contact pad on the second side forming an electrical connection between the semiconductors electrically connected in series with one another without a further conductor track.

26. High-current circuit according to claim 25, wherein the areas of the third and a fourth contact pad on the two sides of the printed circuit board are arranged one above the other.

27. High-current circuit according to claim 21, wherein a second semiconductor switch is directly connected to the first contact pad on the first side of the printed circuit board.

28. High-current circuit according to claim 21, wherein the semiconductor switches have power terminals on their wide surfaces.

29. High-current circuit according to claim 27, wherein the first and/or second semiconductor switch is directly connected to a flat part on its side facing away from one of the contact pads, in particular in that the first semiconductor switch is connected to the second contact pad by means of a first wide surface and is connected to a first flat part by means of a second wide surface opposite the first surface, and/or the second semiconductor switch is connected to the first contact pad by means of a first wide surface and is connected to a second flat part by means of a second wide surface opposite the first surface.

30. High-current circuit according to claim 29, wherein the flat part is arranged directly on the second surface of the semiconductor switch.

31. High-current circuit according to claim 21, wherein the semiconductor switches are electrically connected to one another exclusively via the vias.

32. High-current circuit according to claim 21, wherein a contact pad on the first side has an area which is at least equal to the area of all the terminals of the semiconductor switch on the second side.

33. High-current circuit according to claim 21, wherein on the second side a power terminal of the semiconductor switch is directly connected to the contact pad and a switching terminal of the semiconductor switch is connected to a contact pad and a conductor track.

34. High-current circuit according to claim 29, wherein the flat part is connected to the at least one contact pad over the entire surface.

35. High-current circuit according to claim 21, wherein at least three contact pads which are insulated from one another are arranged on the first side, the contact pads each being connected via the vias to power terminals of a plurality of the semiconductor switches, and a flat part being connected to each of the contact pads over the entire surface.

36. High-current circuit according to claim 21, wherein at least one contact pad for each respective one of two power terminals is arranged on the second side for each respective one semiconductor switch.

37. High-current circuit according to claim 21, wherein contact pads of a plurality of power terminals of a plurality of the semiconductor switches are connected to one another over their entire surface on the second side.

38. High-current circuit according to claim 21, wherein the number of vias per contact pad of a power terminal is at least ten, preferably more than thirty.

39. High-current circuit according to claim 29, wherein at least one of the flat parts is led out of the surface of the printed circuit board and forms a terminal lug for a power conductor.

40. High-current circuit according to claim 21 arranged in a first region of the printed circuit board, wherein the conductor layer between two edges of the printed circuit board is completely cut through and divides the printed circuit board into the first region and a second region, wherein a logic circuit is arranged in the second region.

Description

[0037] In the following, the subject matter is explained in more detail with reference to a drawing showing embodiments. In the drawing show:

[0038] FIG. 1 a layered structure of a printed circuit board;

[0039] FIG. 2 a top view of a first side of the printed circuit board;

[0040] FIG. 3 a top view of a second side of the printed circuit board;

[0041] FIG. 4a, b views of a first semiconductor switch;

[0042] FIG. 5a, b views of a second semiconductor switch;

[0043] FIG. 6 an assembled second side of the printed circuit board with semiconductor switch;

[0044] FIG. 7a, b views of flat parts;

[0045] FIG. 8 a top view of a populated first side with flat parts;

[0046] FIG. 9 a sectional view through a populated circuit assembly;

[0047] FIG. 10 a top view of a second side according to an embodiment example;

[0048] FIG. 11 the side according to FIG. 1 equipped with semiconductor switches;

[0049] FIG. 12 the assembled semiconductor circuit according to FIG. 11 with a flat part;

[0050] FIG. 13 a first side corresponding to FIG. 11;

[0051] FIG. 14 a populated first side according to FIG. 13;

[0052] FIG. 15 an assembled circuit covered with a flat part as in FIG. 14;

[0053] FIG. 16 a sectional view through a populated circuit assembly.

[0054] FIG. 1 shows a cross-section of a printed circuit board with a substrate 2. The substrate 2 may be a fibre-reinforced epoxy resin. In particular, the substrate 2 is non-conductive. The substrate 2 is a conventional substrate for printed circuit boards.

[0055] A conductive layer 4 is applied to the substrate 2. The conductor layer 4 is in particular a copper layer. The conductor layer 4 is usually thinner than 1 mm and is brought into the desired topology by exposure and etching during the production of printed circuits. The conductor layer 4 is covered with an insulation layer 6. The insulation layer 6 can be, for example, a solder resist. At places where the conductor layer 4 is to be contacted, the insulation layer 6 can be removed and/or the conductor layer 4 can be led out of the insulation layer 6 there. This allows, for example, a contact pad to be applied to the conductor layer 4. The structure of the printed circuit board according to FIG. 1 is a conventional structure as used in standard printed circuit boards.

[0056] With the help of such a standard structure of a printed circuit board, it is possible to realise the circuit arrangement in question. For this purpose, as shown in FIG. 2, at least one large-area contact pad 8 is arranged on a first side of the printed circuit board. FIG. 2 shows a first contact pad 8, a third contact pad 10 and a fifth contact pad 12. The numbering of the contact pads 8, 10, 12 is merely intended to simplify reading, whereby the numbering is not to be understood as meaning that a second contact pad necessarily requires a first contact pad, a third contact pad necessarily requires first and second contact pads, a fourth contact pad requires third to first contact pads and so on.

[0057] The contact pads 8 to 12 are applied to the conductor layer 4 on the first side of the printed circuit board, in particular by metallic coating of the conductor layer 4 in an opening of the insulation layer 6. The contact pads 8-12 as well as all other contact pads mentioned herein are preferably identical in structure, being formed from the conductor layer 4 and a metallic coating applied thereto. The metallic coating can, for example, be a tin plating. The metallic coating preferably closes plane-parallel with the insulation layer 6, whereby deviations of a few μm are possible.

[0058] The contact pads 8, 10, 12 are interspersed with vias 14, whereby the vias 14 can be holes through the conductor layers 4 and the substrate 2. The vias 14 penetrate the substrate 2 completely and are at least partially metallic or metallically coated. The vias 14 are electrically conductive. As a result, the vias 14 create an electrical short-circuit between the conductor layers 4 facing each other and thus the contact pads applied to the conductor layers 4. By separating the conductor layer 4, it is achieved that the contact pads 8-12 as well as the contact pads mentioned below are each insulated from each other on one side of the printed circuit board, but are short-circuited to each other via the vias on opposite sides of the printed circuit board. The contact pads 8-12 as well as also the following contact pads have a large surface area and are suitable for applying a contact part with a large surface area.

[0059] In FIG. 2 it is further shown that the conductor layer 4 is completely separated at a separation point 16, so that the printed circuit board is divided into two areas. These two areas are, on the one hand, the area with the contact pads and, on the other hand, an area with a logic circuit 18. The logic circuit 18 is thermally decoupled from the high-voltage circuit, as implemented on the printed circuit board by the contact pads, by the separation point 16. The provision of the isolation point 16 and the logic circuit 18 is optional and mentioned here for the sake of completeness.

[0060] FIG. 3 shows a second side of a printed circuit board according to FIG. 1 whose structure corresponds to the structure of the printed circuit board according to FIG. 2. Second contact pads 20a-c, a fourth contact pad 22 and sixth contact pads 24a-c can be seen. The second contact pads 20a-c can be short-circuited to each other via the conductor layer 4. The contact pads 20a-c, 22 and 24a-c are insulated from each other by separating the conductor layer 4 accordingly. Vias 14, which pass through the respective contact pads 20, 22, 24, can be seen.

[0061] It can also be seen that the contact pads 20a-c and the contact pads 24a-c have tongue-like connection areas. This is optional, as full-surface connection areas can also be provided instead of the tongue-like connection areas. The corresponding connection areas serve to connect a first power terminal of a semiconductor switch, as will be shown below. Power terminals of semiconductor switches are attached, in particular soldered, to the contact pads 20a-c, 22, 24, as will be shown below.

[0062] For switching the semiconductor switches, a contact pad 20a′, 20b′, 20c′, 24a′, 24b′, 24c′ is provided in addition to each of the contact pads 20a-c, 24a-c. These additional contact pads 20a′-24c′ serve to connect a switching terminal of a semiconductor switch. The contact pads 20a′-24c′ are electrically insulated from all other contact pads and can be switched together or separately via switching terminals 26. This allows a group of semiconductor switches to be controlled together or each individual semiconductor switch to be controlled individually.

[0063] FIG. 4a, b show a semiconductor switch 28 in a top view and in a side view. The semiconductor switch 28 has contact pins 30 intended for a power terminal and at least one contact pin 32 for a switching terminal. In FIG. 4b it can be seen that the semiconductor switch 28 is of SMD construction, so that it can be placed directly with its contact pins 30, 32 on the contact pads 8-12, 20-24. The semiconductor switch 28 is, for example, a MOSFET or IGBT.

[0064] FIG. 5a, b shows another construction of a semiconductor switch 28, in which contact pads 30′ are provided on opposite broad surfaces of the semiconductor switch 28 to form the power terminals. A contact pin 32 forms the switching terminal. These large-area contact surfaces 30′ enable large-area contacting of the power terminals and thus a high power flow through the semiconductor switch 28.

[0065] A semiconductor switch 28 according to FIG. 4 is applied to the second side of the printed circuit board shown in FIG. 3, as shown in FIG. 6. It can be seen that the contact pins 30 are in contact with the contact pads 20a, b, c on the one hand and with the contact pad 22 on the other hand. The respective contact pins 32 are connected to the respective contact pads 20a′-c′ and thus to the switching terminal 26. Furthermore, semiconductor switches 28 are connected with their contact pins 30 on the one hand to the contact pads 24a-c and on the other hand to the contact pad 22. The respective contact pins 32 are connected to the respective contact pads 24a′-c′ and thus to the switching terminal 26. Thus, the power terminals of the semiconductor switches 28 are each connected via the contact pads 20a-c as well as 24a-c and the contact pad 22.

[0066] With the aid of the semiconductor switches 28, a connection can thus be established between the contact pads 20a-c and the contact pad 22 and between the contact pad 22 and the contact pads 24a-c depending on their switching state.

[0067] The semiconductor switches 28 can be soldered with their contact pins 30, 32.

[0068] Flat parts as shown in FIG. 7 are provided for connecting the circuit as shown in FIG. 6 to cables. On the one hand, a flat part 34 according to FIG. 7a and a flat part 34 according to FIG. 7b are provided. With the aid of the flat part 34 according to FIG. 7a, which is formed as a connection lug, an external connection to the circuit can be made possible. A flat part 34 according to FIG. 7b can be used as a heat sink.

[0069] The flat parts according to FIG. 7a, b are applied to the circuit according to FIG. 2, in particular soldered over the entire surface. A flat part 34, which is formed as a terminal lug according to FIG. 7a, is applied to the first contact pad 8 and the fifth contact pad 12. A flat part 34 is applied to the contact pad 12 as a heat sink. The flat parts 34 are applied, in particular soldered, over the entire surface of the contact pads 8-12.

[0070] The structure of the circuit in the assembled state is shown in FIG. 9. FIG. 9 shows that the vias 14 pass through the substrate 2 and short-circuit the contact pads 8 and 20, 10 and 22 as well as 12 and 24 with each other. Current flows via the flat part 34 to the contact pad 8 and from there via the vias 14 to the contact pad 20. If the left-hand semiconductor switch 28 is closed, the current flows from the contact pad 20 via the semiconductor switch 28 to the contact pad 22. If the right-hand semiconductor switch 28 is closed, the current flows further from the contact pad 22 to the contact pad 24 and from there via the vias 14 to the contact pad 12 and finally onto the flat part 34.

[0071] The central flat part 34, which is applied to the contact pad 10, serves as a heat sink. Heat can be transported from the contact pad 22 to the contact pad 10 via the vias 14 and the flat part 34 can serve as an additional heat sink. This is particularly useful in the case of high currents, which are quite possible in automotive applications.

[0072] FIGS. 10-16 show another embodiment in which the PCB is sandwiched between two flat parts. FIG. 10 shows a first side of a printed circuit board with contact pads 8a-c for a power terminal of a respective semiconductor switch 28 and contact pads 8a′-c′ for a switching terminal of a respective semiconductor switch 28. The contact pads 8a-c can be short-circuited to each other or insulated from each other, whereas the contact pads 8a′-c′ are insulated from each other and from the contact pads 8a-c and are routed to a switching terminal 26.

[0073] In FIG. 11 it is shown that the semiconductor switches 28 with their terminals 30′ are placed over the entire surface of the contact pads 8a-c and are connected to them. The semiconductor switches 28 are connected to the contact pads 8a′-c′ via contact pins 32. The semiconductor switches 28 have a structure as shown in FIG. 5. A flat part 34 is then placed on these semiconductor switches 28, as can be seen in FIG. 12.

[0074] On the other side of the substrate 2 is a corresponding structure with contact pads 20a-c and 20a′-c′ as shown in FIG. 13. Again, semiconductor switches 28 are connected with their power terminals 30′ to the contact pads 20a-c and with their switching terminals 32 to the contact pins 20a′-c′, as shown in FIG. 14. Subsequently, a flat part 34 is also placed over the entire surface of the semiconductor switches 28, as shown in FIG. 15.

[0075] FIG. 16 shows a cross-section through such a sandwich-like structure. Between the flat parts 34 the semiconductor switches 28 with their terminals 30′ are arranged in a sandwich-like manner on the contact pads 8, 20, which are applied to the two conductor layers 4. The contact pads 8-20 are short-circuited to each other via the vias 14. A current flow occurs via the flat part 4, the semiconductor switch 28, the contact pad 8, the vias 14, the contact pad 20 and the semiconductor switch 28 to the flat part 34. A direct short circuit between the semiconductor switches 28 is ensured by the vias 14. Since the flat part 34 rests directly on the semiconductor switches 28, it serves not only as an electrical supply line but also as a heat sink.

LIST OF REFERENCE SIGNS

[0076] 2 Substrate [0077] 4 Conductor layer [0078] 6 insulation layer [0079] 8 first contact pads [0080] 10 third contact pads [0081] 12 fifth contact pads [0082] 14 via [0083] 16 Interface [0084] 18 logic circuit [0085] 20 second contact pads [0086] 22 fourth contact pads [0087] 24 Sixth contact pads [0088] 26 Switching terminals [0089] 28 Semiconductor switches [0090] 30, 32 Contact pins [0091] 34 flat part