KR102093893B1 - High current circuit board - Google Patents

Abstract

The present invention relates to a high current circuit board 10 suitable for handling current exceeding 100A. To this end, the high-current circuit board is constructed with two or more copper layers 11 of greater thickness arranged above and below each other, the copper layers comprising conductor tracks 1; 4 having a geometrically complex design. . The copper layers 11 arranged above and below each other are arranged above and below each other to reduce leakage inductance and are connected to each other through the connecting element 12. In addition, in the case of the configuration according to the present invention, a copper insert or a busbar may be omitted. Through the connecting element 12, a connection with the heat sink 15 may also be made to enable cooling of the high current circuit board 10. Overall, the high current circuit board 10 can be manufactured more cost-effectively and more quickly and can be more diversely matched to the required conditions.

Description

High current circuit board {HIGH CURRENT CIRCUIT BOARD}

The present invention relates to a high current circuit board that can be used in a variety of electronic devices, particularly in a vehicle electronic device system. However, it is also contemplated to be used in vehicles, ships, or larger fixed electronic devices.

According to the standard, the circuit board has a copper thickness of 105 μm per layer. In addition, if the circuit board must be capable of guiding high currents, as is the case for example for power inverters, the electrical resistance of the conductor tracks and the resulting power losses and associated heating must be reduced. do. For this, additional measures are needed, for example copper inserts or busbars.

Inserts or busbars only allow conductor tracks in the form of relatively simple geometry due to manufacturing and cost. This hinders the complex design of the conductor track, in particular the shape of the complex and geometrically expensive conductor track in the x-y-direction. However, such a complex design is needed for optimization of electromagnetic compatibility (EMV) or for optimization of leakage inductance. In devices where direct high current gradient di / dt occurs, leakage inductance causes overvoltage peaks, which can damage electrical components or cause flashover by insulation.

In addition, circuit boards with larger copper thickness are well known to prevent power loss and associated heating. Nevertheless, even in known circuit boards with larger copper thicknesses, copper inserts and busbars with relatively simple geometry of conductor tracks are additionally used.

An object of the present invention is to provide a high-current circuit board that is suitable for guiding a higher current, but has a design to be manufactured simply in this case and can be optimally configured in terms of electromagnetic compatibility.

This problem is solved by an object having the characteristics according to claim 1. Other improvements are described in the dependent claims.

The high current circuit board includes a component mounted on a surface and a conductor track connecting the components, wherein the conductor track is disposed on two or more copper layers having a thickness of 200 µm or more. The conductor track and conductive side have a design produced in the x-y-direction by a photolithography process, for example a photo-resist process. Conductor tracks and conductive faces of copper layers disposed above and below each other are connected electrically and / or thermally by a connecting element, whereby a plurality of connecting elements are provided.

The manufacturing method by the photolithography process enables a complex geometry of conductor tracks and conductivity in the xy-direction, thereby enabling a high number and density of conductor tracks in individual copper layers of the circuit board, and conductor tracks. And such a complex design of the conductive side can be produced relatively simply, quickly and cost effectively by photolithography. For example, time-intensive and cost-intensive installations for tools such as those required for punching inserts or busbars are omitted, since these members can be omitted entirely. Design changes can be implemented quickly and simply in the photolithography process, and as a result, while the circuit board is deployed, multiple iterative loops can be made more easily than in the case of a tool-related process. Here, since the matching of the copper insert and the busbar must be made according to the change of the circuit board, a much higher complex design can be recorded as a result.

In an embodiment of a high current circuit board according to the present invention, a plurality of copper layers are disposed in a congruent up and down relationship with each other in a high current circuit board. This allows congruent placement of conductor tracks with different potentials in adjacent layers, which certainly improves the electromagnetic compatibility of the circuit. If the conductor tracks for the supply current and return current are congruent in two adjacent layers, the magnetic field is optimally compensated and the leakage inductance is kept low.

As is common in solutions with busbars or inserts, when conductor tracks are placed side by side next to each other, for example, two flat conductor tracks are about 4 nH for a distance of 1 mm, a width of 30 mm, and a length of 10 cm. Inductance is provided. When such conductor tracks are arranged to be congruent in two adjacent layers of the circuit board, the leakage inductance is calculated as follows:

0.004*l*π*d/B in μH L

0.004 * l * π * d / B in μH

Here, ℓ is the length of the conductor track, d is the spacing of the conductor track, B is the width of the conductor track, and all sizes are in cm each.

For d of 0.5 mm for the same conductor track (B = 30 mm, l = 10 cm), the leakage inductance L is only 2.1 nH, resulting in almost half. Therefore, the overvoltage peak U induced by the current fluctuation is also reduced by almost half according to U = L × di / dt. Therefore, the vibration propensity is also reduced by the parasitic LC-resonance circuit. In multi-layer circuit boards, overall spacing smaller than 0.5 mm is possible, so the leakage inductance can be even lowered as a result.

In the case of using a copper layer having a copper thickness exceeding 200 μm per layer, a high current exceeding 100 A can be guided in another embodiment of the high current circuit board according to the present invention.

According to another embodiment of the high current circuit board, a plurality of copper layers are connected in parallel. Thus, the electrical resistance of the conductor track can be reduced by parallel circuits in different layers. To this end, the layers are electrically and / or thermally connected to each other and connected in parallel by means of connecting elements, so that the requested current strength exceeding 100 A can be reached as a result.

In one embodiment of the high current circuit board, the components mounted on the surface are likewise connected to the copper layer by means of connecting elements. This connecting element connects the components mounted on the surface perpendicular to each other with different layers of the circuit board. In this case, electrical connection is considered first.

However, the connecting element can also be provided to connect the component mounted on the surface with the heat sink. This thermal connection also contributes to the release of thermal energy from the conductor printing plate. Therefore, a separate cooling body for each power semiconductor is also unnecessary.

Through the connecting elements, not only electrical connection but also heat dissipation of the power semiconductor occurs. In addition, connecting elements are preferred because the mechanical assembly is very simple. Fixing the power semiconductor to the heat sink by screwing or clamping is omitted. This contributes to the simplification of the conductor printing plate during manufacturing.

The connecting element, also referred to as the via, can be a bore through the conductor printing plate, provided with a copper clad foil. However, it is also possible to fill the coated bore with a material, which is an epoxy resin or a metal-containing paste or a material comparable thereto. The only important point in this regard is that it does not lose the effect of electrical conductivity or thermal conductivity when charging.

In another embodiment of the high-current circuit board according to the present invention, the thicknesses of the copper layers arranged above and below each other are different. Thus, material savings can be made if necessary, and in some cases, price and space demands can be reduced.

According to another embodiment of the high-current circuit board according to the present invention, the high-current circuit board is a part of a vehicle electronic system, especially a part of an inverter. Particularly in the case of electronic devices requiring high current strength, placing them in very narrow spaces, for example in a vehicle, is associated with demanding requirements. When used in automobiles, currents exceeding 100 A may flow. When the power switch is connected in a half bridge, a high current gradient di / dt occurs. At the same time, very compact and complex designs are required in the vehicle due to the limited structure size and high EMV requirements. In order to keep the leakage inductance and associated overvoltage as small as possible, the rectifier circuit of the inverter must be kept small. It is also advantageous that the high supply current and return current are guided jointly with each other in an ideal way in different layers of the circuit board. The use of inserts or busbars on individual layers will not allow complex shapes to be realized.

Other details, features and advantages of the embodiments of the present invention are set forth from the description of the embodiments with reference to the accompanying drawings below.

1 is a view showing the arrangement of a conductor in a copper insert or bus bar according to the prior art,
2 is a view showing the arrangement of the conductors of the conductor printing plate of a plurality of layers,
3 is a cross-sectional view of a high current circuit board according to the present invention,
4 is a plan view of individual layers of a high current circuit board according to the present invention.

The circuit board of the type according to the prior art shown in Fig. 1 represents a circuit board as used when copper inserts and busbars are used. The first conductor track 1 guides the current 2 applied in the direction of the component 3 mounted on the surface, not shown in detail. Then, the current 5 emitted from the second conductor track 4 is again released. To this end, the circuit board device has a width 6 and a length 7. In addition, the width 6 also maintains the insert spacing 8 where the two conductor tracks are spaced apart.

For the construction according to the invention according to Fig. 2, the two conductor tracks 1, 4 are arranged spaced apart from one another above and below the height gap 9, not into the insert gap 8, side by side. This high spacing 9 can certainly be set smaller than the width spacing 8. Nevertheless, it does not cause interference between the applied current 2 and the emitted current 5. In addition, if the length 7 remains the same, a reduction in width of more than half can be achieved to reach the width 6.

According to FIG. 3, in which a high-current circuit board 10 according to an embodiment of the present invention is shown in cross-section, a plurality of copper layers 11 are disposed above and below each other. These layers are connected to the surfaces 13a, 13b of the conductor circuit board via connecting elements 12, so-called vias. A component 3 mounted on the surface is disposed on the surface 13a of the first upper conductor circuit board, and the component also includes individual components 14 mounted on the surface. Components 3 mounted on the surface are similarly arranged on the surface 13b of the second lower conductor circuit board. The connecting element 12 not only connects the component 3 or the power semiconductor 14 mounted on the surface with the copper layer 11, but also connects the power semiconductor 14 with the heat sink 15. To this end, between the lower conductor circuit board surface 13b facing the heat sink 15 and the heat sink 15, a thermally conductive material 16, for example a thermally conductive paste, is provided.

4 is a plan view of sections of the individual copper layers 11 arranged above and below each other in a high current circuit board, shown in the schematically illustrated figures A) to D). As shown in FIG. 4, the copper layers disposed above and below each other in the high current circuit board 10 include one layer structure each congruent with the maximum portion with respect to the other copper layer 11. The individual copper layers 11 are connected to each other by means of connecting elements 12 (vias).

1: first conductor track
2: Current applied
3: Components mounted on the surface
4: Second conductor track
5: current emitted
6: width
7: Length
8: Insert spacing, width spacing
9: Height spacing
10: high current circuit board
11: copper layer
12: connecting element (via)
13a: conductor circuit board surface
13b: conductor circuit board surface
14: power semiconductor, components
15: heat sink
16: Thermally conductive material

Claims (8)

A high current circuit board comprising a component (3; 14) mounted on a surface and a conductor track (1; 4) connecting the components (3; 14) and a conductive surface, wherein the conductor track (1; 4) In the high-current circuit board 10 is disposed on two or more copper layers 11 having a silver thickness of 200 μm or more,
The conductor tracks 1 and 4 and the conductive surfaces have a design created by a photolithography process in the xy-direction, and the conductive tracks 1 and 4 and the conductive surfaces of the copper layers 11 disposed above and below each other are connected. It is electrically and thermally connected by the element 12, wherein a plurality of connecting elements 12 are provided,
High current circuit board 10, characterized in that the components 3; 14 mounted on the surface are electrically and thermally connected to the copper layer 11 by the connecting element 12. The high-current circuit board (10) according to claim 1, characterized in that the plurality of copper layers (11) are arranged in a joint with each other up and down in the high-current circuit board (10). The high current circuit board (10) according to claim 1, characterized in that two or more of the copper layers (11) are connected in parallel. delete A high current circuit board comprising a component (3; 14) mounted on a surface and a conductor track (1; 4) connecting the components (3; 14) and a conductive surface, wherein the conductor track (1; 4) In the high-current circuit board 10 is disposed on two or more copper layers 11 having a silver thickness of 200 μm or more,
The conductor tracks 1 and 4 and the conductive surfaces have a design created by a photolithography process in the xy-direction, and the conductive tracks 1 and 4 and the conductive surfaces of the copper layers 11 disposed above and below each other are connected. It is electrically and thermally connected by the element 12, wherein a plurality of connecting elements 12 are provided,
High-current circuit board 10, characterized in that the component (3; 14) mounted on the surface is connected to the heat sink 15 by the connecting element (12). The high current circuit board (10) according to claim 1, characterized in that the copper layers (11) disposed above and below each other have different thicknesses. The high current circuit board (10) according to any one of claims 1 to 3, 5 to 6, characterized in that the high current circuit board (10) is a component of a vehicle electronic system. The high current circuit board (10) according to claim 7, characterized in that the high current circuit board (10) is a component of an inverter.

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