DE102009060123B4 - Electrical circuit comprising at least one printed circuit board and a number of provided with Bauteilekontaktierungen electrical components - Google Patents

Abstract

Electrical circuit comprising at least one printed circuit board (20, 20 ') and a number of electrical components (22, 30, 34, 36, 36a, 38, 40) provided with component contacts (28, 28', 28 ", 28" a) at least one electrical component to be cooled (34, 36, 36a, 38, 40), wherein the printed circuit board (20, 20 ') with a printed circuit board upper side (58) and a printed circuit board underside (64) is provided and a contacting region (24) and at least one Cooling region (32, 32 ', 32'a, 32 "), wherein the contacting region (24) comprises a number of PCB contacts (26, 26', 26,", 26 "', 26"' a), with which the Device contacts (28, 28 ', 28 ", 28" a) are electrically conductively connected, wherein the cooling region (32, 32', 32'a, 32 ") in the contacting region (24) arranged to be cooled electrical component (34, 36, 36a, 38, 40), and wherein the cooling area (32, 32 ', 32'a, 32 ") is adapted to dissipate heat, which arises at the electrical component (34, 36, 36a, 38, 40) through which an electric current flows during operation of the electrical circuit, wherein the cooling region (32, 32 ', 32'a, 32 ") has at least one cooling hole (42, 42 ', 42 ", 102), wherein the cooling hole (42, 42', 42", 102) is formed so that for dissipating the heat surrounding the cooling region (32, 32 ', 32'a, 32 ") Fluid the cooling hole (42, 42 ', 42 ", 102) from the circuit board bottom side (64) to the circuit board upper side (58) can flow through, characterized in that in the cooling region (32, 32', 32") on the circuit board top side (58) and a number of cooling circuit boards (76, 78) are mounted on the underside of the circuit board (64), the cooling circuit boards (76, 78) each having at least one additional cooling hole (80, 88) shaped and positioned in the cooling hole (42, 42) ', 42 ") corresponds to the printed circuit board (20).

Description

The present invention relates to an electrical circuit having at least one printed circuit board and a number of electrical components provided with component contacts with at least one electrical component to be cooled, wherein the printed circuit board is provided with a printed circuit board top side and a printed circuit board underside and has a contacting region and at least one cooling region Contacting portion having a number of PCB contacts, with which the component contacts are electrically connected, wherein the cooling region is assigned to the arranged in the contacting area to be cooled electrical component, in particular a power semiconductor, and wherein the cooling area is adapted to dissipate heat, which at the Operation of the electrical circuit is formed by an electrical current flowing through electrical component, wherein the cooling area at least one K hlungsloch, said cooling hole is formed so as to dissipate the heat, a cooling of the area surrounding fluid can flow through the cooling hole of the printed circuit board lower side to the circuit board top.

Such an electrical circuit is off DE 93 00 864 U1 known.

Generic electrical circuits are used when in the operation of an electrical circuit such an electric current will flow through an electrical component installed in the circuit, which leads in this component to such a high power loss and resulting strong heating of this component, in which without cooling the component would impair its function or it would even be destroyed. Due to the fact that the circuit board installed in the electrical circuit has a cooling area assigned to the strongly heating electrical component, the heat arising on this component can be dissipated. Consequently, overheating of the electrical component and thus impairment of its function or even its damage can be avoided.

Such electrical circuits are used, for example, in the control of electric motors. This may be, for example, designed as a frequency converter or as an inverter electrical circuits. These circuits are used for example for controlling asynchronous motors. With a frequency converter, a first AC voltage having a first frequency is converted into a second AC voltage. The second AC voltage has a second frequency different from the first frequency and needed for the operation of the motor. With an inverter, a DC voltage is converted into an AC voltage, wherein the AC voltage has a frequency required for the operation of the motor.

To generate the alternating voltage, power semiconductors are preferably used in these circuits. During operation of the electric motors flow through the motor windings sometimes very large electrical currents. These currents lead to a large power loss in the semiconductors, which causes them to heat up considerably. In order to avoid overheating of the power semiconductors and thus the above-mentioned consequences, the power semiconductors are cooled.

As a rule, industrially manufactured electrical circuits are designed as printed circuits. This also applies to electrical circuits that are used for the control of electric motors. Printed circuits can be manufactured using different mounting techniques. In so-called through-hole mounting (through-hole technology, THT), the electrical components used have wire connections. These wire connections are inserted in the assembly of the electrical components by existing contact holes in the circuit board and then connected by appropriate soldering processes with the contact holes. In the so-called surface-mounted technology (SMT), electrical components are used which, instead of wire connections, have solderable connection surfaces which are soldered directly to corresponding contact surfaces of the printed circuit board.

In printed circuits, the cooling of electrical components is difficult. This applies in particular to power semiconductors. In this case, in printed circuits, which are manufactured in the surface mounting technology, the cost for the cooling of power semiconductors inherently greater than in printed circuits, which are manufactured in the through-hole mounting technology.

Regardless of the assembly technique used to fabricate the electrical circuit, cooling of power semiconductors is cumbersome for the following reasons. On the one hand, additional assembly work steps are required in the manufacture of the electrical circuit in addition to the actual assembly work steps. The actual assembly work steps include working steps for the preparation of the circuit board and steps for mounting the electrical components on the circuit board. Both Work steps for the preparation of the printed circuit board are, for example, milling and / or drilling operations, with which, for example printed circuit board contacts are generated. The steps for mounting the electrical components are, for example, the connection of component contacts with PCB contacts and the possibly required fixing of electrical components on the circuit board. On the other hand, the additional assembly work steps are necessary in order to achieve a sufficient thermal transition from this component to a cooling component used for its cooling on an electrical component to be cooled. This is, for example, the attachment of a cooling component to the electrical component to be cooled. The additional assembly work steps usually require very complex movements in the assembly machines used for the production of electrical circuits. Overall, these additional assembly operations increase the manufacturing cost of printed circuits. On the other hand, the cooling components themselves cause not inconsiderable additional material costs, which also leads to an increase in the cost of an electrical circuit. The cooling components can be, for example, heatsinks or heatpipes that are attached to the electrical component to be cooled.

US 5,339,519 proposes a method of attaching a heat sink to a circuit board. The board has a plurality of copper layers which are parallel to each other. Holes are provided orthogonally to the course of the copper layers, in which a connecting means is arranged, which connects the copper layers thermally with each other. A first of the copper layers is thermally connected to an electrical component to be cooled. Another of the layers is thermally connected to the heat sink via electrical insulation. For mechanical attachment of the heat sink with the board, the board has a breakthrough outside the copper layers. A clamping plate is connected to the heat sink by means of a screw which extends through the aperture.

DE 93 00 864 U1 describes an insulating part, which may be made of plastic and having at least one metallized, acting as a cooling surface outer surface. In addition, the insulating part on conductor tracks, which can be connected to an electronic component. The outer surface of the insulating part has at least one recess, whereby cooling fins are formed. The electronic component is thermally conductively connected to the outer surface. It is also contemplated that individual cooling fins have openings containing thermally conductive material.

US 5,929,375 A describes a circuit board which consists of a substantially non-conductive substrate and has at least one first and second rigid plate. The plates are mesh-like and substantially surrounded by the substrate. A part of the plates extends out of the substrate and forms contact devices. Breakthroughs are provided through the substrate to the plates in which a conductive material is disposed. The openings can be arranged below an electrical component.

DE 195 40 814 A1 describes a board, which is composed of a heat conducting plate and a printed circuit board. Surface mounted components are attached to the board. A compound of the heat conducting plate and the printed circuit board is interrupted in a region of the components. In addition, the circuit board has slots which surround the components like a frame. The slots are interrupted to lead away a conductor track.

US 6,212,076 B1 describes a printed circuit board having slot-shaped apertures. The openings are arranged in a region of the printed circuit board which has a heat-conducting layer. The breakthroughs serve to heat sinks can be attached to it.

DE 10 2005 063 281 A1 describes an electrical circuit in which electrical components are mounted on a printed circuit board. The printed circuit board has a cooling region, in which at least one component body is arranged. Below the component body contact openings are arranged. These contact openings are formed either as through holes or as blind holes. When executed as through holes contact openings one end is closed by the electrical component to be cooled. Thus, during operation of the electrical circuit, that is, when a current flows through the electrical component and heats it, the heat from this device can not be dissipated by a fluid flowing through the contact opening. Instead, the resulting heat to the electrical component in the inner layers of the circuit board is initiated via these contact openings. In turn, the heat is dissipated to the edge of the circuit board via these inner layers. From the edge, the heat is dissipated in a housing surrounding the circuit board. For this purpose, a clamping edge is provided, in which the edge of the circuit board is to be inserted during assembly. The clamping edge has in this case from the top and the bottom of the circuit board of the heat radiation serving upstanding free leg. In order to optimize the introduction of heat into the housing, a contact opening may be provided in the region of the circuit board edge which is inserted into the clamping edge. These too Contact opening can be designed either as a through hole or as a blind hole. In the case of a through hole both ends are closed by the clamping edge in the assembled state of the circuit board. Thus, even here, during operation of the electrical circuit, the heat can not be dissipated by a fluid flowing through the contact opening.

A disadvantage of this electrical circuit is the additional required assembly work step, which is required for the insertion of the circuit board in the terminal edge to allow the heat dissipation from the circuit board into the housing and thus the cooling of the electrical component. In addition, a specially prepared housing is needed. Namely, a housing which has to be provided for the purpose of cooling or designed for this purpose clamping edge. Thus, the use of mass produced housings is not possible. Instead, specially designed and specially designed housings must be used. Both the additionally required assembly work step and the use of specially manufactured housing increase the cost of producing an electrical circuit.

The use of a housing for the heat radiation and thus the cooling of an electrical component has a further disadvantage. Any scaling of the cooling component, i. Dimensioning and thus adaptation of the cooling component to the cooling power to be provided in the specific electrical circuit is only conditionally or not at all possible. For example, due to very restrictive space constraints, it may not be possible to size a housing that would be required to achieve the required cooling performance.

Against this background, it is an object of the present invention to further develop an electrical circuit of the type mentioned above with a view to the cooling of electrical components installed in the electrical circuit and to improve that cost-effective and less expensive production of the electrical circuit and at the same time easy adjustment of the components used for the cooling to the required cooling capacity for the specific electrical circuit is made possible.

This object is achieved with an electrical circuit of the aforementioned type, in which a number of cooling circuit boards is mounted in the cooling area on the circuit board top side and / or on the circuit board underside, wherein the cooling circuit boards each have at least one additional cooling hole in the form and location of the cooling hole PCB corresponds.

The electric circuit is based on the idea of providing a cooling hole in the printed circuit board for dissipating the heat which arises during operation of the electrical circuit on an electrical component through which an electrical current flows. The cooling hole is designed such that a fluid surrounding the cooling region can flow through the cooling hole from the underside of the printed circuit board to the upper side of the printed circuit board. The cooling area is that area of the printed circuit board in which the cooling hole is arranged.

By using a cooling hole for cooling an electrical component can be dispensed with the use of additional components. These additional components are the cooling components already mentioned, ie components which are installed in an electrical circuit exclusively for the purpose of cooling an electrical component and which are not required for realizing the actual electrical functionality of the electrical circuit. These additional components may be designed as passive cooling components or as active cooling components. Passive cooling components are, for example, on the cooling element to be cooled to be mounted heat sink or mounted in the circuit board cooling plates. As an example of an active cooling component, let us mention a Peltier element. Accordingly, the electrical circuit is constructed of a printed circuit board and of such electrical components, which are needed only for the realization of the actual electrical functionality, ie the functionality inherent in the electrical circuit. These electrical components are, for example, semiconductors, resistors, capacitors or coils. The fact that an electrical circuit without said additional components can be realized, apart from the costs to be incurred for the circuit board and the said electrical components, no further costs for components. Since said additional components are usually very expensive, thus the component-related costs for an electrical circuit can be significantly reduced.

The fact that the electrical circuit can be realized without said additional components also leads to further cost savings. In an electrical circuit in which said additional components are installed, the already mentioned additional assembly operations are required for the production of the electrical circuit in addition to the already mentioned actual assembly work steps. These additional assembly operations increase the cost of manufacturing an electrical circuit. Since the electrical circuit without said additional components manages, thus also said additional assembly operations are not required. Consequently, the cost of manufacturing electrical circuits can be significantly reduced.

Overall, the electrical circuit thus allows a cost savings in circuits in which cooling of an electrical component is required in two respects. First, a component-related cost savings, as can be dispensed with said additional components. And on the other a montagebedingte cost savings, as said additional assembly operations are not required.

The use of a cooling hole as a cooling component also allows easy scaling, i. Adapting the cooling component to the cooling power required in the concrete electrical circuit for cooling the electrical component. Scaling is possible, for example, by selecting a suitable hole shape or a hole shape uniformly used for various electrical circuits by changing the hole size. Thus, in the fabrication of the electrical circuit, by modifying the steps of preparing the circuit board in a simple manner, a cooling component of desired cooling performance can be generated. The required cooling component can thus be dimensioned and manufactured itself.

According to the invention, a number of cooling circuit boards are mounted in the cooling area on the upper side of the circuit board and / or on the underside of the circuit board, the cooling circuit boards each having at least one additional cooling hole corresponding in shape and location to the cooling hole of the circuit board. This measure enables an improved dissipation of heat. By attaching a cooling circuit board to the circuit board, the enveloping surface is enlarged, can be dissipated via the convection and heat radiation heat. The original envelope surface of the cooling hole located in the circuit board is supplemented by the additional envelope surface of the additional cooling hole located in the cooling circuit board. It is conceivable to install cooling circuit boards at the same time exclusively on the upper side of the printed circuit board or exclusively on the underside of the printed circuit board or on both sides at the same time. Overall, this creates a layered structure of the cooling area.

By using cooling circuit boards, the cooling performance can be easily scaled, i. adapt to the requirements of the electrical circuit. For example, it turns out when operating an electrical circuit that the originally estimated cooling capacity is not sufficient, can be increased by attaching a cooling circuit board to the circuit board, the cooling capacity without much effort. But even in the stage of circuit planning and circuit design can be achieved with the help of the cooling circuit boards, a smooth adjustment of the cooling performance. If, for example, it is not possible to carry out cooling holes of the required length due to limited installation space, then a number of cooling circuit boards can be provided on the circuit board in order to achieve the required cooling capacity. Preferably, the cooling circuit boards are made of the same material as the circuit board itself. As a result, electrical circuits can be carried out particularly inexpensively.

The above object is therefore completely solved.

In a further embodiment of the invention, the cooling region has a plurality of cooling holes, which are arranged so that they have a very small distance from each other in pairs.

This measure has the advantage that within the cooling area, a compact, quasi-contiguous area is created, can be dissipated via the heat, which allows a particularly good cooling of the electrical component. The distance is chosen so that it is much smaller than the diameter of the cooling holes. Preferably, the cooling holes are arranged in a double row, wherein the cooling holes within the two rows have a very small distance from each other. In addition, the two rows have a very small distance from each other at least in one area.

Furthermore, the cooling holes are preferably designed as plated-through holes. As a result, the cooling holes have a metallized envelope surface, which increases the surface available for heat dissipation and thus improves the heat dissipation.

In a further embodiment of the invention, the cooling hole includes a slot.

By this measure, the flow-through behavior of the fluid through the cooling hole is improved. In addition, a slot supports heat dissipation to a defined location of the circuit board due to its propagation direction within the circuit board. Overall, the heat dissipation property of the cooling area is improved.

Furthermore, this measure allows simple scaling, ie adaptation of the cooling hole to the cooling power required for the respective electrical circuit. In an electrical Circuit in which a high cooling capacity is required for cooling an electrical component, the slot is made longer, as in an electrical circuit in which a lower cooling capacity is required. The adaptation of the cooling hole to the required cooling capacity by varying the slot length also means that a cooling hole can be produced inexpensively using fewer tools, for example by milling and drilling.

In a further embodiment of the aforementioned measure, the oblong hole has at least one longitudinal side a number of cooling hole extensions.

This measure has the advantage that the envelope surface of the cooling hole is increased. This improves the removal of heat by means of convection and heat radiation. The Kühllocherweiterungen also correspond cooling holes, especially when production technology in the cooling area initially arranged in a double row vias are introduced and then the located between the vias material of the circuit board is milled out. The cooling hole extensions then represent residual areas of the plated-through holes.

In a further embodiment of the aforementioned measures, the cooling hole extensions are formed in a circular arc.

This measure allows a particularly simple and thus cost-effective production of the cooling hole extensions. Thus, the Kühllocherweiterungen can be made for example by means of a milling cutter or a drill. In the simplest case, the cutter can be used, with which the slot is milled.

In a further embodiment of the aforementioned measures, the slot has a longitudinal axis, wherein the slot is aligned so that the longitudinal axis extends away from the device towards an edge of the circuit board.

This measure allows optimal cooling of the electrical component. The slot extends from the location of the heat source, namely the electrical component to be cooled, to a location of low temperature, namely the edge of the circuit board. Thus, there is a large temperature difference along the longitudinal axis of the elongated hole, which allows effective heat removal by means of conduction.

In a further embodiment of the invention, the cooling region has at least two elongated cooling holes, each having a remote component and a close-fitting hole end, wherein the component near hole ends in pairs have a greater distance from each other than the component distal hole ends.

Compared to an arrangement in which the cooling holes are arranged in pairs parallel to each other, i. at the component-near hole ends and at the component-distant hole ends, in each case the same distance from each other, this measure allows a better heat distribution in the region of the heat source, i. in the area of the component to be cooled. This allows a better dissipation of heat and thus cooling of the electrical component.

In a further measure of the invention, the printed circuit board, at least in the cooling area, has a number of inner layers running within the printed circuit board, wherein the inner layers are connected at least to a first heat conduction layer applied to the upper side of the printed circuit board via a number of plated-through holes.

This measure allows an improved dissipation of heat. Starting from the first heat-conducting layer, the heat can be introduced via the plated-through holes into the inner layers by means of conduction. Thus, heat generated at the electrical component to be cooled can be dissipated not only via the surface of the upper side of the printed circuit board, optionally via an upper conductive layer located on the upper side of the printed circuit board, but also via inner layers running inside the printed circuit board. Preferably, the inner layers are made of a material with good thermal conductivity.

Advantageously, a four-layer printed circuit board is used as the printed circuit board. Such a printed circuit board has a conductive layer both on the upper side of the printed circuit board and on the lower side of the printed circuit board. In addition, it has two inner layers. The electrical components mounted on the printed circuit board are wired to one another via the two conductor layers, as is necessary for realizing the electrical functionality inherent in the electrical circuit. The two inner layers serve to dissipate heat. Preferably, all four layers are made of copper. For this reason, it is also conceivable to realize at least a partial circumference of the wiring using a partial circumference of one or both inner layers. It is also possible to use printed circuit boards with more than four layers.

Preferably, the first heat conduction layer is a partial circumference of the printed circuit board top applied upper line position. Advantageously, all inner layers are connected via the plated-through holes with the first heat-conducting layer. Furthermore, the inner layers are advantageously also connected to each other via the vias.

In a further embodiment of the aforementioned measure, the mounted electrical component further comprises a component body, wherein the component body is arranged in the cooling area and the first heat conduction layer and the plated-through holes are arranged below the component body.

This measure allows a particularly good dissipation of the resulting in the electrical component to be cooled heat. The heat is introduced directly to the component body, ie where it arises, via the plated-through holes in the inner layers. It can preferably be provided that between the component body and the first heat conduction layer, a thin layer of thermal compound is introduced to further improve the heat dissipation. The thermal compound improves the already existing between the device body and the first heat conduction layer, caused by contact contact thermally conductive compound. In a further advantageous embodiment it can be provided that the component body is galvanically connected to the first heat conduction layer. This has the advantage that in addition to the heat-conductive compound in addition there is also an electrical connection.

In a further embodiment of the aforementioned measures, the plated-through holes are filled with a thermally conductive material.

This measure allows a particularly effective introduction of heat into the inner layers. Preferably, the thermally conductive material is copper.

In a further embodiment of the invention, the cooling hole has an enveloping surface running inside the printed circuit board, wherein at least part of the enveloping surface is coated with a second heat conducting layer.

This measure contributes to an improved removal of heat. By coating the envelope surface with a second heat conduction layer, a via with a large inner surface is formed. With this via, the heat present within the board can be particularly effectively dissipated to the outside, i. can be dissipated in the environment of the circuit board by convection and heat radiation. This measure is preferably applied to a printed circuit board which has inner layers. This combination allows a particularly good dissipation of heat. The second heat conduction layer is preferably made of solder or copper.

In a further embodiment of the invention, at least part of the circuit board top side and / or a part of the circuit board underside is coated with a heat radiation layer with a high emissivity in the cooling area.

By this measure, the removal of heat is improved. The heat radiation layer improves the heat radiation property of the circuit board and thus enables better dissipation of heat. Preferably, both the upper side of the printed circuit board and the underside of the printed circuit board is coated with the heat radiation layer. Furthermore, both surfaces are advantageously completely coated with the heat radiation layer. Preferably, the heat radiation layer has a higher emissivity than the circuit board. The use of dark solder resist has proved to be particularly advantageous as material for the heat radiation layer.

In a further embodiment of the invention, the contacting region and the cooling region are separated from one another by an insulation region with a low thermal conductivity, at least in the area of the upper side of the printed circuit board.

This measure improves the removal of heat. It is achieved a directed dissipation of the heat generated at the electrical component away from this device to the cooling hole. It can thus be avoided that areas of the circuit board, which adjoin the mounting region of the electrical component to be cooled, unnecessarily heat up. Preferably, the contacting region and the cooling region are separated from each other by milling into the conductive layer of the printed circuit board surface a channel which no longer contains any conductive material. Advantageously, appropriate measures for the separation of the contacting area and the cooling area are also provided in the area of the underside of the printed circuit board.

For attaching the cooling circuit boards to the circuit board different mounting options are available. Thus, the cooling circuit boards can be soldered or clamped or screwed. Preferably, the cooling circuit boards are soldered, since this requires the least manufacturing effort and also ensures optimum thermal coupling between the circuit board and cooling circuit board. The same applies to the fastening of the cooling circuit boards with each other.

Advantageously, the cooling circuit boards each have a number of running inside the cooling circuit board inner layers, which allows a particularly good dissipation of heat.

In a further embodiment of the invention, the cooling circuit board has: on at least one surface, a third heat conduction layer, and a number of inner layers running within the cooling circuit board.

By using such cooling circuit boards can be realized for a specific electrical circuit cooling performance in a simple manner. The use of cooling circuit boards thus enables a simple and cost-effective scaling of the cooling device.

Preferably, the cooling hole is designed as a through hole over its entire length and over its entire width. The same applies to the additional cooling hole.

The cooling range of the printed circuit board corresponds in its functionality to a passive cooling component. This also applies to the cooling circuit board. The measures presented thus make it possible to realize a simple and cost-effective passive cooling component, which can also be scaled as desired.

The fluid surrounding the cooling region is preferably ambient air. However, it is also conceivable to operate the new electrical circuit in a special atmosphere which contains a gas which has particularly suitable properties for convection and / or thermal radiation. It is also conceivable to use the new electrical circuit in such an environment in which a liquid flows through the cooling hole.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

• 1 eine schematische Darstellung einer Schaltungsanordnung;
• 2 eine Draufsicht auf einen Kühlungsbereich gemäß einem ersten Beispiel;
• 3 eine Schnittdarstellung eines Ausschnitts einer Leiterplatte mit einem Kühlungsbereich;
• 4 eine Schnittdarstellung eines Ausschnitts einer Leiterplatte mit einem Kühlungsbereich gemäß einem Ausführungsbeispiel der Erfindung;
• 5 eine Draufsicht auf einen Kühlungsbereich gemäß einem zweiten Beispiel;
• 6. eine Draufsicht auf einen Kühlungsbereich gemäß einem dritten Beispiel;
• 7 eine Draufsicht auf ein entstehendes Kühlungsloch;
• 8 eine Draufsicht auf ein fertig gestelltes Kühlungsloch;
• 9 eine Draufsicht auf ein fertig gestelltes Kühlungsloch gemäß einer alternativen Ausführungsform.

Embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description. Show it:

• 1 a schematic representation of a circuit arrangement;
• 2 a plan view of a cooling area according to a first example;
• 3 a sectional view of a section of a printed circuit board with a cooling area;
• 4 a sectional view of a section of a printed circuit board with a cooling area according to an embodiment of the invention;
• 5 a plan view of a cooling area according to a second example;
• 6 , a plan view of a cooling area according to a third example;
• 7 a plan view of a resulting cooling hole;
• 8th a plan view of a completed cooling hole;
• 9 a plan view of a completed cooling hole according to an alternative embodiment.

In 1 is a circuit arrangement in its entirety with the reference numeral 10 designated.

The circuit arrangement 10 consists of an electrical circuit 12 in a housing 14 is arranged and one over electrical lines 16 to the electrical circuit 12 connected consumers 18 , In the electrical circuit 12 it may, for example, be a frequency converter. In this case, the consumer 18 For example, designed as an asynchronous motor. But there are also any other applications conceivable. The electrical circuit 12 can be made in through-hole mounting technology or in surface mount technology.

The electrical circuit 12 consists of a printed circuit board 20 and a number of electrical components 22 on printed circuit board 20 are mounted. For this purpose, the circuit board 20 a contacting area 24 on. The contacting area 24 in turn has a number of PCB contacts 26 on. The electrical components 22 have component contacts 28 on that with the PCB contacts 26 are connected. For clarity, in 1 only for a first electrical component 30 , its component contacts with the reference numeral 28 provided and associated with this component PCB contacts with the reference numeral 26 Mistake.

The circuit board 20 has a number of cooling areas. A first cooling area 32 of a second electrical component 34 assigned. A second cooling area 32 ' of a third electrical component 36 assigned. A third cooling area 32 " of a fourth electrical component 38 and a fifth electrical component 40 assigned. For the electrical components 34 . 36 . 38 . 40 they can be power semiconductors, with which for the operation of the electrical consumer 18 required currents are provided. In particular, it is power semiconductors of a frequency converter. The cooling areas 32 . 32 ' . 32 " have the task to dissipate the heat in the electrical components 34 . 36 . 38 . 40 during operation of the electrical circuit 12 due to electrical currents flowing through these components.

The on the circuit board 20 arranged cooling areas have cooling holes. So contains the first cooling area 32 a number of first cooling holes 42 , The second cooling area 32 ' contains a number of second cooling holes 42 ' , The third cooling area 32 " contains a number of third cooling holes 42 " , As the illustration in 1 it can be seen that are in the cooling areas 32 . 32 ' . 32 " arranged cooling holes 42 . 42 ' . 42 " designed as slots. As can further be seen from this illustration, the cooling holes in the individual cooling regions can be arranged differently among one another. In the first cooling area 32 are the first cooling holes 42 arranged parallel to each other. This also applies to the third cooling area 32 " arranged third cooling holes 42 " , In contrast, in the second cooling area 32 ' the second cooling holes 42 ' arranged so that those hole ends of the second cooling holes 42 ' located in the immediate vicinity of the third electrical component 36 have a greater distance from one another than the hole ends of the second cooling holes 42 ' , which is a peripheral area of the circuit board 20 are facing.

The representation in 1 according to which the electrical circuit 12 only a single circuit board 20 is intended to have no limiting effect. Of course, electrical circuits may also be constructed of a plurality of printed circuit boards. Further, in 1 for reasons of clarity on the representation of electrical connections between individual printed circuit board contacts 26 waived.

2 shows in a plan view a first section 44 the circuit board 20 ,

The first part 44 includes a partial extent of the contacting region 24 and the third cooling area 32 " , wherein the third cooling area 32 " is executed according to a first example. The illustrated partial circumference of the contacting region 24 has PCB contacts 26 ' on that the fifth electrical component 40 assigned. Bauelementekontaktierungen 28 ' of the fifth electrical component 40 are with the PCB contacts 26 ' connected. Furthermore, this partial circumference has PCB contacts 26 " on that the fourth electrical component 38 assigned. For the sake of illustration, the fourth electrical component 38 in 2 but not shown.

The third cooling area 32 " has a number of third cooling holes 42 " on. The following comments on the shape and structure of the cooling holes are made on the basis of the upper of the two cooling holes, which are in the region of the fifth electrical component 40 are arranged. These designs apply to all cooling holes of the PCB 20 ,

The cooling holes consist in their basic form of a slot 46 , On its long sides has the slot 46 a number of cooling hole extensions 48 on. These cooling hole extensions 48 are formed in a circular arc. The representation in 2 , according to which the circular arcs are semicircles, should have no limiting effect. Of course, the cooling hole extensions 48 each correspond to an arbitrarily designed circular arc. The third cooling holes 42 " are aligned so that the longitudinal axis of each cooling hole away from the component, in this case from the fifth electrical component 40 away to an edge 50 the circuit board 20 runs.

The third cooling area 32 " has a first heat conduction layer 52 on. The first heat conduction layer 52 has a number of vias 54 on. About the vias 54 is the first heat conduction layer 52 to be described, within the circuit board 20 connected inner layers. In the assembled state of the fourth electrical component 38 are the first heat conduction layer 52 and the vias 54 below the component body of the fourth electrical component 38 arranged. The third cooling area 32 " points in the region of the fifth electrical component 40 a corresponding structure. The fifth electronic component 40 has a component body 56 on, below which also a first heat conduction layer 52 ' is arranged. Also this first heat conduction layer 52 ' has a number of vias 54 ' on that in 2 due to the coverage by the device body 56 however are not visible. The arrangement of a first heat conduction layer below a component body allows a very good dissipation of the heat generated at the electrical component. Through the vias, the heat can be initiated directly at the place where it arises in the running inside the circuit board inner layers. As the illustration in 2 it can be seen, is the component body 56 within the third cooling area 32 " arranged.

The first two heat conduction layers 52 . 52 ' are part of an upper wiring layer that is on a circuit board top 58 the circuit board 20 is arranged. In the production of the electrical circuit 12 , more precisely, when preparing the circuit board 20 the upper cable layer is processed so that the contact area 24 arranged PCB contacts 26 . 26 ' arise. Furthermore, it also creates connections between the individual printed circuit board contacts 26 . 26 ' , These compounds are for clarity in FIG 2 but not shown. When making the circuit board 20 Within the cooling areas, the upper conduction layer is not removed. Thus, the cooling areas are covered by the upper line layer. This allows a good heat dissipation.

Like the one in 2 illustrated first section 44 can be seen, are the contact area 24 and the third cooling area 32 " through an isolation area 60 separated from each other. The isolation area 60 has a low thermal conductivity. This is the third cooling area 32 " opposite the contacting area 24 thermally insulated and it is ensured that, for example, on the fifth electrical component 40 resulting heat mostly to the third cooling holes 42 " and thus the edge 50 the circuit board 20 is derived. The isolation area 60 arises, for example, from the fact that a channel is milled out of the upper line position, in which then no material of the upper line position is present. This approach also has the advantage that also an electrical insulation of the third cooling area 32 " opposite the contacting area 24 is reached. A corresponding isolation area can also be found at the bottom of the circuit board 20 be provided.

Each of the in 2 illustrated third cooling holes 42 " has an envelope surface 61 on. To achieve better heat dissipation is at each of these cooling holes 42 " at least part of the envelope surface 61 with a second heat conduction layer 62 coated. Preferably, the second heat conduction layer 62 only on the surfaces of the cooling hole extensions 48 applied. This is especially the case when it comes to the Kühllocherweiterungen 48 are residual areas of vias. The second heat conduction layer 62 but also on the surface areas between the cooling hole extensions 48 be upset. As material for the second heat conduction layer 62 For example, solder can be used. However, better heat dissipation is achieved when copper is used instead of solder.

As the illustration in 2 it can be seen, have the third cooling holes 42 " a length which is on the order of the length dimension of the electrical components. In this case, a cooling hole may have a length which quite corresponds to the multiple of the length of a component body. The length of the cooling holes is ultimately determined by the cooling capacity to be realized for the respective electrical component to be cooled, wherein the electrical properties of the component are taken into account when determining the cooling power.

3 shows a sectional view through the circuit board 20 along the in 2 drawn cutting line A - A ,

The circuit board 20 points next to the PCB top 58 a circuit board base 64 on. The contacting area 24 and the third cooling area 32 " are separated from each other by the isolation area 60 separated. On the circuit board 20 is the fifth electrical component 40 assembled. For this purpose, one of the component contacts 28 ' with one of the PCB contacts 26 ' in the contacting area 24 is arranged, connected. The fifth electrical component 40 is doing so on the circuit board 20 mounted that the component body 56 over the first heat conduction layer 52 ' is arranged. The first heat conduction layer 52 ' is via vias 54 ' with a first inner layer 66 , with a second inner layer 68 and with one in the area of the PCB underside 64 arranged lower line position 70 connected. About the vias 54 ' are the first heat conduction layer 52 ' , the two inner layers 66 . 68 and the lower line position 70 connected to each other thermally conductive. Thus, heat is transferred to the fifth electrical component 40 arises, starting from the first heat conduction layer 52 ' both in the two inner layers 66 . 68 as well as in the lower line position 70 initiated. This allows a very good heat dissipation. To effectively dissipate the heat and thus achieve the greatest possible cooling capacity are the vias 54 ' filled with a thermally conductive material. Preferably, the two inner layers protrude 66 . 68 and the lower line position 70 not in the contact area 24 into it. This will be a directed dissipation of heat to the edge 50 the circuit board 20 ensured.

The circuit board 20 is on the circuit board top 58 with an upper heat radiation layer 72 coated. Likewise, the circuit board 20 on the PCB bottom 64 with a lower heat radiation layer 74 coated. Both heat radiation layers 72 . 74 have a high emissivity, resulting in a very good thermal radiation and thus a very good Heat dissipation leads. With regard to the coating of the surfaces of the printed circuit board 20 Various embodiments are conceivable with a heat radiation layer. In a first embodiment is applied to the lower heat radiation layer 74 omitted, so that only the upper heat radiation layer 72 is available. In this case, the circuit board top 58 partly or completely with the upper heat radiation layer 72 be covered. In a second embodiment, although both heat radiation layers 72 . 74 available, but only in the third cooling area 32 " , In a third embodiment, both the contacting area 24 as well as the third cooling area 32 " completely with both heat radiation layers 72 . 74 coated. The above statements apply equally to all on the printed circuit board 20 arranged cooling areas.

The third cooling area 32 " has a third cooling hole 42 " on, with cooling hole extensions 48 is provided. The envelope surface 61 of the third cooling hole 42 " is at least in the area of the cooling hole extensions 48 with the second heat conduction layer 62 coated. As the illustration in 3 can be seen, for discharging the on the fifth electrical component 40 resulting heat a third cooling area 32 " surrounding fluid the third cooling hole 42 " from the PCB bottom 64 to the PCB top 58 flow through.

Both the first heat conduction layer 52 ' , as well as the PCB contacts 26 ' are part of an upper line situation 75 , In the production of the electrical circuit 12 , more precisely, when preparing the circuit board 20 These arise through the removal of material of the upper line position 75 ,

The representation in 3 , according to the two inner layers 66 . 68 and the lower line position 70 not in the contact area 24 protrude, should have no limiting effect. It is also conceivable, for example for the realization of wiring in more complex electrical circuits, said layers also in the contacting area 24 protrude. In this case, a separation of the contacting region is also for these layers 24 from the third cooling area 32 " according to the in the area of the circuit board top 58 arranged isolation area 60 provided.

In the 3 chosen representation, according to the first heat conduction layer 52 ' and the upper line position 75 are not connected, should have no limiting effect. It is also conceivable that both are interconnected.

The first heat conduction layer 52 ' , the two inner layers 66 . 68 and the lower line position 70 are separated from each other by not closer designated intermediate layers of an electrical insulation material. The same applies on the one hand for those in the area of the third cooling holes 42 " arranged layers, namely the upper line position 75 , the two inner layers 66 . 68 and the lower line position 70 and the other for the cooling circuit boards to be described.

4 also shows a sectional view of the circuit board 20 along the in 2 drawn cutting line A - A , The in 4 illustrated third cooling area 32 " is executed, however, according to an embodiment of the invention. In the following, only the differences compared to those in 3 illustrated third cooling area 32 " available.

Compared to the in 3 illustrated circuit board has the in 4 illustrated circuit board 20 in the area of the third cooling holes 42 " on the one hand on the PCB top 58 no upper heat radiation layer 72 and on the other side of the circuit board 64 no lower heat radiation layer 74 on. Thus, in the area of the third cooling holes 42 " both the lower line position 70 as well as the upper line position 75 accessible from outside. For this reason, there is the third cooling area 32 " more precisely in the area of the third cooling holes 42 " , between the pipe plate 20 on the one hand and one on the PCB top 58 attached first cooling circuit board 76 and one on the bottom of the PCB 64 attached second cooling circuit board 78 on the other hand, an optimal heat input.

The first cooling circuit board 76 has a first additional cooling hole 80 on. This first additional cooling hole 80 corresponds in shape and location to the third cooling hole 42 " the circuit board 20 , Consequently, the first additional cooling hole is 80 in its basic form also formed as a slot, which on its long sides Kühllocherweiterungen 48 ' having. Advantageously, the number of additional cooling holes corresponds to the first cooling circuit board 76 the number of cooling holes of the circuit board 20 , This also applies to the second cooling circuit board 78 , The first cooling circuit board 76 also has a first inner layer 66 ' and a second inner layer 68 ' on. In addition, the envelope is 61 ' of the first additional cooling hole 80 at least in the area of the cooling hole extensions 48 ' with a second heat conduction layer 62 ' coated. On her cooling circuit board top 82 has the first cooling circuit board 76 a third heat conduction layer 86 on. Correspondingly, the first cooling circuit board 76 on her cooling circuit board base 84 a third heat conduction layer 86 ' on. The on the cooling circuit board top 82 arranged third heat conduction layer 86 is again with a heat radiation layer 72 ' coated.

The first cooling circuit board 76 is on the circuit board 20 preferably fixed by the fact that on the bottom of the cooling circuit board 84 arranged third heat conduction layer 86 ' with the upper line position 75 is soldered. This is an optimal heat input from the circuit board 20 in the cooling circuit board 76 guaranteed. But it is also conceivable, the first cooling circuit board 76 by means of screws or clamps on the circuit board 20 to fix.

The second cooling circuit board 78 is according to the first cooling circuit board 76 built up. Consequently, the second cooling circuit board 78 a second additional cooling hole 88 on. Also the second additional cooling hole 88 corresponds in shape and location to the third cooling hole 42 " , Consequently, the second auxiliary cooling hole has 88 the basic shape of a slot and also has Kühllocherweiterungen 48 " , The second cooling circuit board 78 also has a first inner layer 66 " and a second inner layer 68 " on. Also, the envelope is 61 " of the second additional cooling hole 88 at least in the area of the cooling hole extensions 48 " with a second heat conduction layer 62 " coated. In the area of their cooling circuit board top 82 ' has the second cooling circuit board 78 a third heat conduction layer 86 '' on. In the area of their cooling circuit board base 84 ' has the second cooling circuit board 78 a third heat conduction layer 86 " on that with a lower heat radiation layer 74 ' is coated.

According to the first cooling circuit board 76 is also the second cooling circuit board 78 by soldering the third heat conduction layer 86 '' with the lower cable position 70 on the circuit board 20 attached. Alternatively, the second cooling circuit board 78 on the circuit board 20 also screwed or clamped.

A comparison of the two cooling circuit boards 76 . 78 with the circuit board 20 shows that the construction of the two cooling circuit boards 76 . 78 with the structure of the circuit board 20 in the third cooling area 32 " matches. Consequently, the circuit board can 20 and the two cooling circuit boards 76 . 78 be made from the same circuit board blank. In addition, this means that the third heat conduction layers are also conduction layers.

In the 4 chosen representation, according to both the PCB top 58 the circuit board 20 , as well as on the bottom of the PCB 64 the circuit board 20 each a cooling circuit board is mounted, should have no limiting effect. It is also conceivable, for example, only on the circuit board top 58 or at the bottom of the PCB 64 To install cooling circuit boards. It is also conceivable, both on the PCB top 58 as well as on the bottom of the PCB 64 each to install more than one cooling circuit board.

The above is stated that the circuit board 20 in the area of the third cooling holes 42 " has no heat radiation layer on both the top of the circuit board and on the underside of the circuit board in order to secure cooling circuit boards can. Alternatively it can be provided that the circuit board 20 nevertheless, both on the PCB top 58 as well as on the PCB bottom 64 is in each case provided with a heat radiation layer, wherein, however, are projected into the respective circuit board surface protruding residual rings of the cooling holes extensions and thus are not covered with the heat radiation layer. The same applies to the cooling circuit boards. These exposed by the heat radiation layer surfaces are sufficient to secure the cooling circuit boards to the circuit board or with each other. On the basis of a printed circuit board to be mounted on a cooling circuit board, the procedure used is described. For example, a tin paste is applied to the residual rings. The cooling circuit board is placed on the circuit board and soldered by reflow or vapor phase method.

For illustrative purposes, the number of vias is 54 ' , in the 3 and in 4 is shown, less than the number of in 2 illustrated vias 54 , This is not intended to be limiting.

5 shows in a plan view a second section 90 the circuit board 20 , Here is the second cooling area 32 ' executed according to a second example.

The contacting area 24 and the second cooling area 32 ' are through an isolation area 60 ' separated from each other. The contacting area 24 has PCB contacts 26 '' on. With these PCB contacts 26 '' are component contacts 28 " of the third electrical component 36 connected. The second cooling area 32 ' has a first heat conduction layer 52 " on. The third electrical component 36 is so on the circuit board 20 mounted that his component body 56 ' in the second cooling area 32 ' is arranged so that the first heat conduction layer 52 " below the component body 56 ' located.

In the second cooling area 32 ' are second cooling holes 42 ' arranged. Also the second cooling holes 42 ' correspond in their basic form a slot and have Kühlungslocherweiterungen 48 '' on. The envelope surfaces 61 '' the second cooling holes 42 ' are at least in the area of the cooling hole extensions 48 '' with a second heat conduction layer 62 '' coated.

Compared to the third cooling holes 42 " are the second cooling holes 42 ' not arranged parallel to each other. Relative to the third electrical component 36 to which the two second cooling holes 42 ' assigned for the purpose of cooling, these two have second cooling holes 42 ' in each case via a component-close hole end 92 . 92 ' and over a device-tight hole end 94 . 94 ' , The two second cooling holes 42 ' are now arranged so that the two component near hole ends 92 . 92 ' have a greater distance from each other than the two component hole-distal ends 94 . 94 ' , The two second cooling holes 42 ' are thus arranged at an angle to each other. This type of arrangement of the cooling holes can also be transferred to cooling areas having more than two cooling holes.

6 shows in a plan view again the second section 90 the circuit board 20 , However, here is the second section 90 a cooling area 32'a on, opposite to the in 5 illustrated second cooling area 32 ' is alternatively configured. In 6 Thus, a cooling area according to a third example is shown. The in the alternatively configured second cooling area 32'a arranged cooling holes correspond in construction, location and shape of those cooling holes, in the second cooling area 32 ' are arranged. The two cooling areas 32 ' and 32'a However, they differ from each other in that the second cooling area configured as an alternative 32'a arranged cooling holes correspond in construction, location and shape of those cooling holes, in the second cooling area 32 ' are arranged. The two cooling areas 32 ' and 32'a However, they differ from each other in that the second cooling area configured as an alternative 32'a In addition to the function of the cooling additionally has the function of an electrical connection. The second cooling area 32 ' only the function of cooling comes to you. Hereinafter, the second cooling area configured as an alternative will be described 32'a described. This is done primarily on the basis of the between the two cooling areas 32 ' and 32'a present differences. Components whose reference number is marked with an "a" are components that differ from the corresponding ones in 5 shown components, are alternatively formed. For the sake of simplicity, the term "alternative" will be prefixed below only for the relevant components.

A contacting area 24 and the alternative second cooling area 32'a are through an alternative isolation area 60'a separated, with the alternative isolation area 60'a a first extension 96 having. The contacting area 24 has PCB contacts 26 "'a on. With these PCB contacts 26 "'a are component contacts 28 "a an alternative third electrical component 36a connected. The alternative second cooling area 32'a has an alternative first heat conduction layer 52 "a on. The alternative third electrical component 36a is so on the circuit board 20 mounted that is the alternative first heat conduction layer 52 "a below its component body 56'a located.

The alternative third electrical component 36a has a component lug. This is preferably located on the underside of the component body 56'a and is thus in 6 not visible. But the component flag can also be on the side of the component body 56'a be arranged. With the component flag is an electrical connection one in the component body 56'a built semiconductor substrate electrically connected. The alternative third electrical component 36a is electrically across this component flag with the alternative first heat conduction layer 52 "a connected. For example, this is the component flag on the alternative first heat conduction layer 52 "a soldered. Thus, the alternative third electrical device 36a also thermally conductive with the alternative first heat conduction layer 52 "a connected. The alternative second cooling area 32'a thus not only has a cooling function, it also comes to the function of an electrical connection. The alternative third electrical component 36a is thus at least with its designed as a component flag electrical connection on the alternative first heat conduction layer 52 "a with one of the PCB contacts 26 "'a electrically connected. For this purpose, the alternative first heat conduction layer 52 "a a second extension 98 on, in the first extension 96 of the alternative isolation area 60'a protrudes. This second extension 98 is with one of the PCB contacts 26 "'a electrically connected.

The description of the electric function from a cooling portion having cooling holes arranged at an angle to each other is not intended to be restrictive. Of course, this function can also be implemented in a cooling area, the cooling holes are arranged parallel to each other

Based on 7 . 8th and 9 The steps to be carried out for the production of a cooling hole are described. In a corresponding manner, additional cooling holes can be produced.

7 shows one on an edge 50 ' a circuit board 20 ' located area 100 in which a cooling area with at least one cooling hole is to be created. First, a variety of vias 102 in that area 100 generated. For this purpose, first in a first step, a corresponding plurality of holes 104 in the circuit board 20 ' drilled. Of these holes, one is exemplified by the reference numeral 104 designated.

In a second step, the holes 104 metallized. It is on the envelope surfaces of the holes 104 each galvanized a metal layer. One of these metal layers is exemplified by the reference numeral 106 designated. Through the metal layer 106 All layers of the circuit board are connected to each other thermally conductive. Thus, an upper line layer and a lower line layer are interconnected, and provided the circuit board 20 ' Inner layers, including these. The metal layer 106 is preferably plated so that it is aligned orthogonal to within the circuit board arranged inner layers. The metallization of the envelope surfaces leads to a heat dissipation favoring surface enlargement. Advantageously, the metal layer 106 designed so that this has no smooth, but a significantly rough surface. This causes a further increase in surface area. At the metal layer 106 it is a second heat conduction layer.

In a third step is in a rectangle 108 indicated area material of the circuit board 20 ' removed, preferably milled. The finished cooling hole 42 "' having in mind this means that a slot 46 ' in the circuit board 20 ' is milled. Through the slot 46 ' is the flow behavior of the fluid, which is the final cooling hole 42 '' flows through, improves.

The finished cooling hole 42 '' is thus manufacturing technology from vias 102 and a long hole 46 ' built up. The finished cooling hole 42 '' includes a slot 46 ' and cooling hole extensions 48 "' , The cooling hole extensions 48 '' also correspond to cooling holes, the cooling holes extensions represent residual areas of the vias.

It has been stated above that three work steps are carried out for the production of a cooling hole, which includes a slot and cooling hole extensions. It is also conceivable to carry out only the first two working steps in the production of a cooling region and thus to dispense with the third working step. In this case, the cooling area has a plurality of cooling holes, which are designed as plated-through holes. These cooling holes are in pairs a very small distance from each other. Preferably, the vias are arranged in the form of a double row, wherein the two rows are arranged in a very small distance parallel to each other. The arranged within a row vias have a very small distance from each other. For all these distances applies that these are much smaller than the diameter of the vias. In this case, the cooling area has a plurality of cooling holes, which, as shown in FIG 7 are arranged. Alternatively, the two rows of the double row as shown in FIG 5 be arranged at an angle to each other.

8th shows the finished cooling hole 42 "' , It includes a slot 46 ' and cooling hole extensions. One of these Kühllocherweiterungen is exemplified by the reference numeral 48 "" designated. For the cooling hole extensions 48 "" These are residual areas of the plated-through holes 102 , The finished cooling hole 42 '' has rounded ends 110 on. These arise when the slot 46 ' is made using a single milling cutter, the diameter of the width of the elongated hole 46 ' equivalent. The cooling hole extensions 48 "" have an envelope surface 61 "" on, which is coated with a second heat conduction layer, namely a galvanized metal layer. For a cooling hole extension, this second heat conduction layer is exemplified by a reference numeral 62 "" designated.

9 shows an alternatively configured finished cooling hole 42 "'a , which alternatively configured ends 110a having. These ends 110a arise from the fact that in the first step in addition to the paired vias, two further vias are made. Of these further plated-through holes, one is in each case arranged in the region of the final through-connection pairs, preferably centrally between the two final plated-through holes. In this case, the alternatively configured slot 46'a be milled using a milling cutter having a smaller radius than the cutter used to make the in 8th shown long holes 46 ' is used. The alternatively configured cooling hole 42 "'a has at its ends on vias, more precisely, remaining areas of vias. In view of the manufacturing cost of an electric circuit, the cooling holes are preferably configured as shown in FIG 8th is shown. The reason is that fewer tool changes are required to make such a cooling hole. For milling the oblong hole 46 ' For example, that cutter can be used which is used anyway for milling the outer contour of the printed circuit board.

The basis of the 7 . 8th and 9 described production of a cooling hole has several advantages. On the one hand layout elements are used, which are used anyway in the preparation of a printed circuit board. Such a layout element is, for example, a plated-through hole. On the other hand, manufacturing methods such as milling or drilling are used, which are used anyway in the preparation of a printed circuit board. The cooling holes can thus be produced at a very low cost. Thus, since the cost of a cooling area made up of cooling holes is lower than the cost of a conventional heat sink, such as an aluminum heat sink to be placed on an electrical component, the cost of manufacturing electrical circuits is reduced.

Alternatively, a cooling hole can also be produced in such a way that in a first step, a slot is first milled. In a second step, preferably semi-circular cooling holes extensions are then attached to the two longitudinal sides of the slot. This is done for example by drilling or milling. In a third step, the envelope surfaces of the cooling hole extensions are metallized, i. a metal layer is galvanized on.

The dissipation of heat can be improved by additionally installing in the housing in which the new circuit is installed a fan which is arranged inside the housing in such a way that the passage of the fluid through the cooling hole is assisted.

Claims (14)

Electrical circuit comprising at least one printed circuit board (20, 20 ') and a number of electrical components (22, 30, 34, 36, 36a, 38, 40) provided with component contacts (28, 28', 28 ", 28" a) at least one electrical component to be cooled (34, 36, 36a, 38, 40), wherein the printed circuit board (20, 20 ') with a printed circuit board upper side (58) and a printed circuit board underside (64) is provided and a contacting region (24) and at least one Cooling region (32, 32 ', 32'a, 32 "), wherein the contacting region (24) comprises a number of PCB contacts (26, 26', 26,", 26 "', 26"' a), with which the Device contacts (28, 28 ', 28 ", 28" a) are electrically conductively connected, wherein the cooling region (32, 32', 32'a, 32 ") in the contacting region (24) arranged to be cooled electrical component (34, 36, 36a, 38, 40), and wherein the cooling area (32, 32 ', 32'a, 32 ") is adapted to dissipate heat, which arises at the electrical component (34, 36, 36a, 38, 40) through which an electric current flows during operation of the electrical circuit, wherein the cooling region (32, 32 ', 32'a, 32 ") has at least one cooling hole (42, 42 ', 42 ", 102), wherein the cooling hole (42, 42', 42", 102) is formed so that for dissipating the heat surrounding the cooling region (32, 32 ', 32'a, 32 ") Fluid the cooling hole (42, 42 ', 42 ", 102) from the circuit board bottom side (64) to the circuit board upper side (58) can flow through, characterized in that in the cooling region (32, 32', 32") on the circuit board top side (58) and a number of cooling circuit boards (76, 78) are mounted on the underside of the circuit board (64), the cooling circuit boards (76, 78) each having at least one additional cooling hole (80, 88) shaped and positioned in the cooling hole (42, 42) ', 42 ") corresponds to the printed circuit board (20). Electrical circuit after Claim 1 characterized in that the cooling area comprises a plurality of cooling holes (102) arranged to be a very small distance apart in pairs. Electrical circuit after Claim 1 or 2 , characterized in that the cooling hole (42, 42 ', 42 ", 42"', 42 "'a) includes a slot (46, 46', 46'a). Electrical circuit after Claim 3 , characterized in that the slot (46, 46 ', 46'a) on at least one longitudinal side a number of Kühllocherweiterungen (48, 48 "', 48""). Electrical circuit after Claim 4 , characterized in that the cooling hole extensions (48, 48 "', 48"") are formed in a circular arc. Electrical circuit according to one of Claims 3 to 5 , characterized in that the slot (46) has a longitudinal axis, wherein the slot (46) is aligned so that the longitudinal axis of the device (34, 36, 36 a, 38, 40) away towards an edge (50) of the circuit board (20) runs. Electrical circuit according to one of the preceding claims, characterized in that the cooling region (32 ', 32'a, 32 ") has at least two elongated cooling holes (42'), each one remote from the building element and a close to the building element hole end, wherein the close to the building element hole ends (92, 92 ') in pairs have a greater distance from one another than the component distal hole ends (94, 94'). Electrical circuit according to one of the preceding claims, characterized in that the circuit board (20) at least in the cooling region (32, 32 ', 32'a, 32 ") a number of within the circuit board (20) extending inner layers (66, 68) in that the inner layers (66, 68) are connected at least to a first heat-conducting layer (52, 52 ', 52 ", 52" a) applied to the upper side of the printed circuit board (58) via a number of plated-through holes (54, 54'). Electrical circuit after Claim 8 characterized in that the assembled electrical component (36, 36a, 40) further comprises a component body (56, 56 ', 56'a), wherein the component body (56, 56', 56'a) in the cooling region (32 ', 32'a, 32 ") and the first heat conduction layer (52 ', 52", 52 "a) and the vias (54') are disposed below the device body (56, 56 ', 56'a). Electrical circuit according to one of Claims 8 or 9 , characterized in that the plated-through holes (54, 54 ') are filled with a thermally conductive material. Electrical circuit according to one of the preceding claims, characterized in that the cooling hole (42, 42 ', 42 ", 42'", 42 "'a) has an enveloping surface (61, 61"', 61 "") extending inside the printed circuit board wherein at least a part of the envelope surface (61, 61 "', 61"") is coated with a second heat conduction layer (62, 62"', 62 ""). Electrical circuit according to one of the preceding claims, characterized in that in the cooling region (32, 32 ', 32'a, 32 ") at least a part of the printed circuit board upper side (58) and / or a part of the printed circuit board underside (64) with a heat radiation layer ( 72, 74) is coated with high emissivity. Electrical circuit according to one of the preceding claims, characterized in that at least in the region of the printed circuit board top side (58) of the contacting region (24) and the cooling region (32, 32 ', 32'a, 32 ") by an isolation region (60, 60') are separated from each other with low thermal conductivity. An electrical circuit according to any one of the preceding claims, wherein the cooling circuit board (76, 78) comprises: on at least one surface (82, 82 ', 84, 84') a third heat conduction layer (86, 86 ', 86 ", 86'"), and a number of inner layers (66 ', 66 ", 68', 68") extending within the cooling circuit board (76, 78).

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