Electronic device with integrated power assembly and production method

Abstract

The invention relates to an electronic device (100) which has a printed circuit board arrangement (1, 20) comprising a plurality of layers of printed circuit boards (2a-2f, 21a-21d), wherein the printed circuit board arrangement (1, 20) has a recess (3) extending from the top side of the printed circuit board arrangement (1, 20) into the printed circuit board arrangement (1, 20). The electronic device (100) additionally comprises a power assembly (4, 25) which is insertable into the recess (3) and is fixedly connectable to the recess (3). The top side of the power assembly (4, 25) has a first metallization (11), on which at least one power component (12, 13a, 13b) is mountable or is mounted. In addition, the power assembly (4, 25) has a cooling structure (16) designed to cool the first metallization (11) by means of a coolant. The printed circuit board arrangement (1, 20) comprises at least one coolant supply line (18) and at least one coolant discharge line (19), wherein the at least one coolant supply line (18) is designed to supply the coolant to the recess (3), and wherein the at least one coolant discharge line (19) is designed to discharge the coolant from the recess (3). The electronic device (100) is designed such that the cooling structure (16) is in thermal contact with the coolant when the power assembly (4, 25) is inserted into the recess (3) and is fixedly connected to the recess (3).

Description

[0001] Electronic device with integrated power module and manufacturing method

[0002] Description

[0003] The invention relates to an electronic device comprising a printed circuit board assembly and a power module. Furthermore, the invention relates to a method for manufacturing an electronic device.

[0004] The invention also relates to an electrical power converter for an industrial process arrangement, preferably a plasma process arrangement or heating arrangement, comprising in particular a radio-frequency (RF) amplifier arrangement. Such an RF amplifier arrangement comprises an aforementioned electronic device and is designed to generate an RF output power, in particular for plasma excitation, such as plasma coating processes, preferably for the production of semiconductor structures.

[0005] Electronic components and assemblies, especially in the field of power electronics, generate heat loss during operation. This heat loss often occurs in a very limited area of ​​just a few mm 2 . It is a particular challenge to dissipate this waste heat in order to protect the components and / or assemblies from destruction due to overheating.

[0006] Cooling poses particular challenges, particularly in the field of electrical power conversion for specific power-intensive and instability-prone industrial processes, such as plasma excitation, plasma coating processes, gas laser excitation, particle accelerators, charging and discharging devices for large batteries, such as flow batteries, melting of solids, heating and / or gasification of liquids using, for example, microwave energy or induction heating, or plasma torches. This can be a process for generating radiation, such as microwave radiation, X-rays, or particle accelerators. What all these processes have in common is that they are designed to generate and accelerate charged atomic or subatomic particles in a gas and / or plasma environment or liquid.What all of these processes also have in common is that they have a high power consumption in the range of 1 kW or more, in particular 10 kW or more, preferably 100 kW or more. For this power range, frequencies > 20 kHz, preferably > 200 kHz, in particular > 2 MHz are generated internally or for external applications. Many of these processes also have very high requirements for the stability of the power supply because the processes are highly complex, such as semiconductor production using plasma processes and / or heating by electromagnetic fields. Typically, power is converted from a mains frequency in the range of approximately 50 Hz to 60 Hz to different frequencies that can be in the above-mentioned range. Conversion to direct current power, also known as DC power, is also conceivable.Even when converting to direct current power, a frequency in the above-mentioned range is often generated within the power converter for the power signal, which is then rectified again according to the requirements for voltage, current and power. This conversion of electrical power into other frequencies requires a large number of electronic components and assemblies, in particular power semiconductor components such as transistors or diodes, particularly PIN diodes, for example for switching RF power between different paths, or a combination of transistor and diode designed for currents > 10 A and voltages > 400 V. These electronic components and assemblies generate heat loss during operation. This heat loss is often generated in a very limited area of ​​just a few mm. 2 , e.g. < 8 mm 2Dissipating this waste heat to protect components and / or assemblies from damage due to overheating presents a particular challenge. Often, very large and material-intensive heat sinks are used for this purpose, and their production is very costly.

[0007] In the prior art, the heat is dissipated by cooling using a cold plate. When cooling with such a conventional cold plate, the heat transfer from the electrical component, which may have a copper layer, to the cooling medium is achieved by applying a material such as thermal paste to the thermal interface, which dissipates the generated heat. However, such thermal interface material proves to be disadvantageous. On the one hand, it represents an additional heat transfer with thermal resistance, and on the other hand, it is subject to wear, which gradually deteriorates its effectiveness during operation. The surface area of ​​the cold plate is also increased or the number and performance of the components is reduced in order to dissipate a greater amount of heat. Both options prove to be inadequate. Since the installation space in the housing of such a power supply is limited, expanding the cooling surface is not possible indefinitely.Reducing the performance of individual components is also not effective. Overall, inadequate cooling of electrical components results in costs.

[0008] A particularly demanding area is a process for plasma excitation, especially plasma processing such as coating, e.g. PVD, CVD, or etching. Such processes are used in the manufacture of semiconductors such as microprocessor components and / or memory chips. Here, the requirements for reliability, longevity, and process repeatability are particularly high. At the same time, the required power levels are also very high. Furthermore, the required output modulations, e.g. in modern electrical power converters with an RF amplifier arrangement or pulsed high-voltage power supplies with pulse shaping, have recently increased steadily. One requirement for an RF amplifier arrangement can, for example, be the ability to be pulsed with several different power levels, which is called multi-level pulsing (MLP). Another requirement for an RF amplifier arrangement can, for example,the ability to adjust the frequency and thus, for example, to be able to react quickly to load changes, which is called auto-frequency tuning (AFT). A further requirement can be, for example, the ability to provide a very high DC voltage, e.g. greater than or equal to 2 kV, in particular greater than or equal to 7 kV, in pulsed form, with pulse frequencies greater than or equal to 1 kHz, in particular greater than or equal to 10 kHz, particularly preferably greater than or equal to 200 kHz. With all of these requirements, the demands on power semiconductor components that are installed in the RF amplifier arrangement and used to generate the RF power also increase. In particular, the demand on these components to convert power that cannot be delivered to the load in certain conditions into heat also increases. These losses that are converted into heat can be > 500 W, in particular > 1 kW in some applications.This heat must be dissipated by the power semiconductor components, otherwise they will be destroyed by overheating.

[0009] The object of the invention is to provide an electronic device, a power converter comprising such an electronic device, and a method for producing an electronic device, which enable improved dissipation of the heat generated during operation of power components within the electronic device. This object is achieved by an electronic device having a printed circuit board arrangement comprising a plurality of layers of printed circuit boards, wherein the printed circuit board arrangement has a recess extending from the top side of the printed circuit board arrangement into the printed circuit board arrangement. The electronic device also comprises a power module that can be inserted into the recess and firmly connected to the recess.The power module has a first metallization on its upper side, on which at least one power component is or can be attached. The power module has a cooling structure designed to cool the first metallization using a coolant. The printed circuit board arrangement comprises at least one coolant supply line and at least one coolant discharge line, wherein the at least one coolant supply line is designed to supply the coolant to the recess, and wherein the at least one coolant discharge line is designed to discharge the coolant from the recess. The device is designed such that the cooling structure is in thermal contact with the coolant when the power module is inserted into the recess and firmly connected to the recess.

[0010] To describe the structure of the electronic device, terms such as “on1 , "top," and "bottom" are used to describe the geometric arrangement of the components of the electronic device. These specifications refer to an electronic device placed on a horizontal surface. The use of these terms is not intended to be restrictive with regard to the spatial orientation of the electronic device. Rather, the electronic device can be used in any spatial orientation. In particular, the electronic device can be used in any installation position.

[0011] The electronic device according to the embodiments of the present application enables the structural and functional integration of a power module into a printed circuit board arrangement. For this purpose, the printed circuit board arrangement has a recess, wherein the power module can be inserted into the recess and firmly connected to the recess. The power module comprises a first metallization, on which one or more power components can be attached. The first metallization serves for the thermal and electrical contacting of one or more power components. To dissipate the heat generated by the at least one power component, the power module comprises a cooling structure. The heat generated by the at least one power component during operation can be dissipated to the cooling structure via the first metallization.The coolant required to cool the cooling structure can be provided by the printed circuit board assembly. For this purpose, the printed circuit board assembly comprises at least one coolant supply line and at least one coolant discharge line. When the power module is inserted into the recess and firmly connected to the recess, the cooling structure is in thermal contact with the coolant. For example, the coolant can flow around or through the cooling structure to dissipate the heat generated by the at least one power component. In this way, effective cooling of the power module inserted into the recess can be achieved.

[0012] In one aspect, the recess is open toward the top of the circuit board assembly. This allows access to the power component for measurement purposes, allowing voltages or temperatures, for example, to be easily determined. Furthermore, the power component can be replaced.

[0013] The electronic device enables close structural and functional integration of the printed circuit board assembly and the power module. By providing at least one coolant supply line and at least one coolant discharge line in the printed circuit board assembly, additional coolant connections or coolant feeds on the power module can be dispensed with, for example. In particular, the electronic device enables close functional integration of power components mounted on the power module and other components and assemblies that can be accommodated, for example, on the printed circuit board assembly. The structural integration enables, for example, short signal paths, short signal propagation times, and allows for the reduction of interference.In addition, the structural integration of the power module into the printed circuit board arrangement reduces the space required by the electronic device.

[0014] The application also relates to a method for producing an electronic device. The starting point for the method is a printed circuit board arrangement comprising a plurality of layers of printed circuit boards, wherein the printed circuit board arrangement has a recess extending from the top side of the printed circuit board arrangement into the printed circuit board arrangement. The printed circuit board arrangement comprises at least one coolant supply line and at least one coolant discharge line, wherein the at least one coolant supply line is designed to supply a coolant to the recess, and wherein the at least one coolant discharge line is designed to discharge the coolant from the recess. The starting point for the method is also a power module having a first metallization on its top side, to which at least one power component can be or is mounted.The power module has a cooling structure configured to cool the first metallization using the coolant. The method includes inserting the power module into the recess of the printed circuit board assembly such that the cooling structure is oriented toward the bottom of the recess. Furthermore, the method includes performing a first thermal process for mechanically connecting the power module to the printed circuit board assembly.

[0015] The method for manufacturing an electronic device provides for inserting the power module into the recess of the printed circuit board assembly and performing a thermal process to connect the power module and the printed circuit board assembly. By means of the thermal process, for example, a fluid-tight seal can be achieved in the region of the recess through which coolant flows. In particular, fluid-tight fluidic connections can be formed between the at least one coolant supply line, the regions of the recess through which coolant flows, and the at least one coolant discharge line.

[0016] Advantageous training and further developments, which can be used individually or in combination with one another, are the subject of the dependent claims and the following description.

[0017] In one aspect, the printed circuit board assembly comprises at least one of the following components: at least one single-sided printed circuit board, at least one double-sided printed circuit board, and at least one prepreg. Single-sided printed circuit boards comprise an insulating layer and a conductive layer, in particular a copper layer, applied to one side of the insulating layer. Double-sided printed circuit boards comprise an insulating layer and conductive layers, in particular copper layers, applied to both sides of the insulating layer. Prepregs are flat textile semi-finished products, such as woven fabrics or scrims with perpendicularly arranged threads or unidirectional layers of threads that are pre-impregnated with a thermoplastic or thermosetting matrix. Prepregs are cured under temperature and pressure, for example, during the production of components.Prepregs can be used, for example, as intermediate layers in multilayer printed circuit boards, for example, to provide electrical insulation between adjacent printed circuit boards. To produce the printed circuit board assembly, the single-sided and / or double-sided printed circuit boards, and any prepregs provided, can be bonded together to form the printed circuit board assembly, for example, under pressure and high temperature. The resulting printed circuit board assembly comprises a plurality of mutually insulated conductive layers, in particular copper layers. Vias or through-holes, for example, can be provided to create electrical connections between different copper layers.

[0018] It is advantageous if the recess extends from the top of the circuit board assembly into the circuit board assembly, but does not penetrate the circuit board assembly. When the power module is inserted into the recess, it can be supported, for example, by the bottom of the recess. Preferably, the power module is inserted into the recess such that the cooling structure is oriented toward the bottom of the recess.

[0019] In one aspect, the recess for the power module extends through several, but not all, circuit boards of the circuit board assembly. The stability of the device is particularly improved by the circuit boards through which the recess does not extend.

[0020] In a further aspect, one or more recesses are provided in at least one circuit board in the circuit board assembly for forming at least one of the coolant supply lines and / or at least one of the coolant discharge lines. Preferably, such recesses are introduced into at least one of the circuit boards before the circuit boards are connected to one another.

[0021] In a further aspect, the power module comprises an electrically insulating substrate having the first metallization on its top side and a second metallization on its bottom side, wherein the cooling structure is thermally and mechanically connected to the second metallization. The first metallization can serve, for example, for attaching and electrically contacting the power components. The first metallization can, for example, comprise one or more conductor structures, which are structured, for example, by means of an etching process. The second metallization preferably serves to establish a thermal and mechanical connection to the cooling structure.

[0022] In another aspect, the power package substrate is one of the following: ceramic substrate, direct bonded copper (DBC), insulated metal substrate (IMB), active metal brazed (AMB), thick film substrate.

[0023] In another aspect, the substrate of the power module is arranged substantially parallel to the top surface of the printed circuit board assembly. For example, the substrate of the power module can be populated with power components, while further electrical and electronic components are mounted on the printed circuit board assembly.

[0024] In a further aspect, at least one of the power components is a MOSFET, in particular LDMOS, or an IGBT. Such power components can be designed for switching and conducting very high power, a very high current, and / or a very high voltage. The power can be, for example, 10 kW or more. The voltage can be, for example, 400 V or more, in particular 1 kV or more. The current can be, for example, 10 A or more, in particular 50 A or more. The switching frequency can be, for example, 10 kHz or more, preferably 100 kHz or more, in particular 1 MHz or more.

[0025] In a further aspect, at least one of the power components is embodied as a bare die. A "bare die," also referred to as a "bare chip," "die," or "chip," refers to integrated electronic components that are not conventionally installed in a plastic or ceramic housing, but are further processed without a housing. They are applied directly to the conductor structure of the substrate and can be electrically connected to surrounding components or conductor structures by bonding, in particular by chip bonding. Bonding here refers to the connection of bare dies to other components or conductor structures.

[0026] In a further aspect, the at least one power component is mounted on the first metallization and has at least one terminal that is thermally and electrically connected to at least one region of the first metallization. In one aspect, at least one region of the first metallization is electrically connected to at least one contact surface of a printed circuit board of the printed circuit board arrangement by means of at least one terminal lug. Such terminal lugs can be used, for example, to form electrical connections between conductor structures of the first metallization and contact surfaces of a printed circuit board of the printed circuit board arrangement.

[0027] Such terminal lugs can be subsequently inserted, for example, after the power module has been inserted into the recess. The terminal lugs can be soldered to the corresponding contact surfaces, for example.

[0028] In one aspect, the terminal lugs are connected, in particular soldered, to contact surfaces on the top side of the printed circuit board assembly.

[0029] In a further aspect, the device is configured such that the cooling structure is in direct contact with the coolant when the power component is inserted into the recess and firmly connected to the recess. The coolant can be supplied to the recess via the coolant supply line, can then be in direct contact with the cooling structure, and can then be removed via the coolant removal line. Due to the direct contact between the cooling structure and the coolant, the heat generated by the power components can be efficiently dissipated.

[0030] In another aspect, the cooling structure is made entirely or partially of copper. Copper exhibits very good thermal and electrical conductivity.

[0031] In one aspect, the cooling structure forms a monolithic structure with the second metallization. It is particularly advantageous if the cooling structure is connected to the second metallization using a metal layer connection method, in particular using direct copper bonding (DCB).

[0032] In one aspect, the cooling structure is at least partially manufactured by means of an additive manufacturing process, preferably by means of selective laser melting. Such an additive manufacturing process is disclosed, for example, in EP 1 672 690 B1 "Micro heat sink." The term "additive manufacturing process" is described there using the method of selective laser melting. However, "additive manufacturing processes" can also include processes other than selective laser melting. An additive manufacturing process is characterized by the fact that the structure is gradually applied from the same material. The material can be melted during application. Lasers are currently suitable for this purpose, allowing particularly fine structures to be achieved.

[0033] In another aspect, the cooling structure comprises at least one cooling pin. Cooling pins can, for example, be surrounded by coolant, thus ensuring efficient heat transfer.

[0034] In one aspect, the cooling structure comprises at least one heat sink having at least one cooling channel through which the coolant can flow.

[0035] In a further aspect, the power module can be connected to the printed circuit board assembly in such a way that fluid-tight fluidic connections are formed between the at least one coolant supply line, the at least one cooling channel, and the at least one coolant discharge line. The coolant flows via the at least one coolant supply line provided in the printed circuit board assembly into the at least one cooling channel, flows through the at least one cooling channel, and is then discharged via the at least one coolant discharge line. Continuous heat dissipation can be achieved through the continuous flow through the heat sink.

[0036] In one aspect, the heat sink is at least partially realized in the form of a layered structure of thermally bonded metal foils, preferably copper foils. For example, metal foils can be at least partially structured by laser processing and / or punching and / or manufactured by electroplating processes and subsequently joined together. Such a production of a monolithic heat sink is disclosed, for example, in DE 43 15 580 A1. Such a method is hereinafter referred to as a "metal layer bonding method." Preferably, the heat sink is at least partially produced by a metal layer bonding method. Preferably, the metal foils are bonded together by a bonding method under high pressure and at high temperature.

[0037] In a further aspect, the metal foils are combined to form a monolithic heat sink. For this purpose, metal foils can be pressed together under pressure and, in particular, also bonded to the metallization. In a further aspect, the metal foils are copper foils. Copper has very high thermal conductivity and electrical conductivity. For example, oxide layers can be formed on the surfaces of copper layers, which are then welded together, with the temperature preferably being selected high enough that the oxide layers melt but the metal foils do not. This also bonds the metal foils to form a monolithic heat sink. If the metal foils are made of copper, for example, this is also referred to as direct copper bonding, or DCB for short.

[0038] In a further aspect, the at least one cooling channel is realized in the form of at least one recess provided in the metal foils.

[0039] In a further aspect, the heat sink is at least partially manufactured by means of a metal layer bonding process, in particular a DCB process.

[0040] In a further aspect, the at least one coolant supply line and the at least one coolant discharge line fluidically contact the recess from the underside of the recess. Particularly when a heat sink is used as the cooling structure, the fluidic contact from the underside of the recess can achieve advantageous sealing of the areas through which the coolant flows.

[0041] In a further aspect, the at least one coolant supply line and the at least one coolant discharge line fluidically contact the recess from the sides of the recess.

[0042] In another aspect, the recess is fluidically contacted from opposite sides of the recess. This allows the coolant to flow through the recess as completely as possible.

[0043] In one aspect, the power assembly is inserted into the recess and fixedly connected to the recess.

[0044] In one aspect, the power module is connected to the recess by soldering. For example, the solder can be introduced into the recess beforehand. After inserting the power module into the recess, the soldering can be performed, for example, using a thermal process.

[0045] In a further aspect, the solder seals the areas through which the coolant flows within the recess and the power module. By soldering the power module to the recess, the areas through which the coolant flows can be sealed, for example. For example, the solder can be distributed around openings of channels and lines due to capillary forces, thus creating, for example, a fluid-tight transition between the cooling channel and the coolant supply line or between the cooling channel and the coolant discharge line.

[0046] In one aspect, the power module is soldered to the recess using the first thermal process. In particular, the soldering can, for example, seal the coolant-flowing areas of the recess.

[0047] In a further aspect, components are also soldered onto at least one circuit board of the circuit board arrangement by means of the first thermal process.

[0048] In a further aspect, the method comprises a step of preheating the cooling structure before performing the first thermal process. The cooling structure of the power component can have a comparatively high heat capacity. This is particularly true if the cooling structure comprises a heat sink. In order to be able to perform the first thermal process in a short time and to reduce the thermal load on the power components, it may be expedient to preheat the cooling structure before performing the first thermal process.

[0049] In one aspect, at least one power component is applied to the first metallization of the power assembly by means of the first thermal process.

[0050] In a further aspect, the method comprises performing a second thermal process for applying at least one power component to the first metallization, wherein the second thermal process is performed before or after the first thermal process. For example, the power components can be applied to the first metallization only after the first thermal process in order to thus reduce the thermal load on the power components. The object is also achieved by an electrical power converter for an industrial process arrangement, preferably a plasma process arrangement or heating arrangement, comprising an electronic device as described above or below. The electrical power converter can be designed in particular to generate an RF output power.RF output power here means an output power in the range of 1 kW or more, in particular 10 kW or more, preferably 100 kW or more at frequencies > 20 kHz, preferably > 200 kHz, in particular > 2 MHz.

[0051] As mentioned at the beginning, such a power converter is particularly dependent on very powerful and reliable cooling, which can be achieved particularly well with such an electronic device.

[0052] EP 3 317 966 B1 describes an arrangement with a printed circuit board for cooling on a metallic cooling plate. The printed circuit board has a bottom layer, with the bottom layer being a metallic layer that serves as a reference ground. However, the heat transfer from the printed circuit board to the cooling plate is not optimal. The card often does not lie flat on the cooling plate. To counteract the lack of heat transfer caused by this disadvantage, thermal paste is used. However, this is disadvantageous in the manufacturing process and can age, which can further deteriorate the heat transfer.

[0053] In one aspect, the electronic device comprises two power semiconductor components, in particular transistors, each having a first and a second power terminal and a control terminal. Both power semiconductor components, in particular transistors, are connected to one of their power terminals in a series circuit, with a direct current or a direct voltage being connected to the remaining power terminals. This can be done, for example, directly or via a filter or an inductor.Furthermore, control electronics can be provided, which is connected to the control terminals of the power semiconductor components and is designed to control the power semiconductor components, in particular transistors, in such a way that they can generate RF power by switching these transistors from a first conducting state to a second conducting state, with the conductivity of the two states being different. Such an arrangement can be operated very efficiently, e.g., in Class D, Class E, Class F, or Class F'. 1Operation of this type generates less power loss than, for example, Class A or Class B operation. In combination with the excellent cooling provided by the described electronic device, an even better supply to industrial processes can be achieved, for example, by allowing them to be operated at higher power. Typical operating classes for generating RF power are described, for example, in EP 1 601 098 B1.

[0054] In one aspect, the two power semiconductor components, in particular transistors, can each be connected by their first power terminal to a common connection point, in particular a ground connection point, wherein the power semiconductor components, in particular transistors, are in particular of similar design and are arranged on the multilayer circuit board. This allows cooling to be further improved and the power yield to be further increased.

[0055] In one aspect, one of the two power semiconductor components, in particular transistors, can be connected by its first power terminal to the other power semiconductor component, in particular transistor, with its second power terminal at a common connection point, wherein the power semiconductor components, in particular transistors, are in particular of similar design and are arranged on the multilayer circuit board. This allows cooling to be further improved and the power yield to be further increased.

[0056] In one aspect, a power transformer with a primary winding and a secondary winding can be arranged on the circuit board, wherein the primary winding is connected to the at least one power terminal of the power semiconductor components, in particular transistors. The primary winding and the secondary winding of the power transformer can each be designed as planar conductor tracks arranged in different layers of the circuit board. The circuit board can have a thermal connection to the heat sink. This can further improve cooling and further increase power output.

[0057] In one aspect, the thermal connection of the heat sink may comprise a thermally conductive leveling layer, the first surface of which is firmly connected to the first surface of the circuit board. Furthermore, the thermal connection may alternatively or additionally comprise a connecting layer, the first surface of which is firmly connected to the second surface of the thermally conductive leveling layer, and the second surface of which is firmly connected to the heat sink.

[0058] The heat sink can have heat dissipating characteristics.

[0059] By “firmly connected” is meant preferably in this application generally that the connection is firm and durable, such as gluing, welding, soldering or pressing and preferably only detachable with high heat and / or mechanical pressure.

[0060] In one aspect, the connection can be designed with a form-fitting design. This prevents air pockets and ensures good heat conduction.

[0061] The thermally conductive leveling layer is designed to conduct heat from the circuit board toward the heat sink. It can compensate for unevenness caused by traces, windings, or contact pads on the underside of the circuit board, for example, and provide a homogeneous and flat surface toward the heat sink.

[0062] The thermally conductive compensating layer can consist of a prepreg or unreinforced adhesive. The insulating circuit board and the thermally conductive compensating layer can be bonded by heating and pressing together a prepreg sandwiched between them. "Prepreg" is a common material name, short for "preimpregnated." This typically refers to pre-impregnated, usually flat, sheet-like textile semi-finished products with a thermoplastic or thermosetting matrix, such as unidirectional layers of threads, fabrics, or scrims, often with perpendicularly arranged threads.

[0063] Prepregs are cured under heat and pressure to produce components. They are prefabricated, for example, in sheet form or wound on rolls. The term prepreg encompasses not only unidirectionally reinforced or flat semi-finished products, but also other preforms of essentially any shape, consisting, in the broadest sense, of a fiber-filled, uncured thermoset matrix. The matrix is ​​in a partially cross-linked state and is pasty to solid, but can be liquefied again by heating.

[0064] Prepregs are machine-processable and are therefore frequently used in automated processes. They produce consistent, high-quality products. Advantages include their low undulation and high fiber volume fraction. Curing at high temperatures enables short cycle times in further processing. Processing requires significant investment, e.g., for autoclaves, placement robots, and refrigerated storage. Such prepregs are generally used to join several circuit boards together to form a multilayer circuit board. To ensure secure and long-lasting joining, the materials to be joined should have very similar properties regarding their expansion under heating. However, this is not necessarily the case for the circuit board and the thermally conductive compensation layer, especially if the thermally conductive compensation layer is made of ceramic. This initially spoke against such a bond.However, ceramic exhibits very good thermal conductivity and, at the same time, very good electrical insulation properties, as well as low dielectric losses when isolating high-frequency signals at high voltages. Contrary to expectations, however, tests have shown that, even with small dimensions, a secure and long-lasting bonding of materials with different properties, such as ceramic with FR-4 and / or ceramic with PTFE material, is possible. "Small dimensions" here means a bonding area of ​​less than 400 cm. 2 and / or with a maximum length of 20 cm.

[0065] The bonding layer may comprise a resin-based adhesive. It may be thinner than the thermally conductive compensating layer.

[0066] The connecting layer may comprise an adhesive film.

[0067] Together, the two layers can form a solid connection with good thermal conduction to the heat sink.

[0068] In one aspect, such an electrical power converter will improve the properties of a power supply system that has LDMOS transistors as the element to be cooled, as disclosed, for example, in DE 102013226 537 A1, EP 3 317 964 B1, EP3 317 965 B1. The load capacity of the LDMOS transistors in such power supply systems often reaches its limits because they get too hot, even though neither their maximum voltage load capacity nor their maximum current load capacity has been reached. This means that with an improvement in cooling as described above and below, such power supply systems can be operated much more reliably. In one aspect, such an electrical power converter will improve the properties of a power supply system that provides very high voltages at its output, in particular voltages greater than or equal to 1 kV, particularly preferably greater than or equal to 2 kV, in particular greater than or equal to 4 kV.It is particularly preferred if these are also provided in pulsed form, as described, for example, in EP 4235 737 A1 as a "high-power generator." Since the switching elements described therein must switch on even when a voltage is applied to their power terminals, these switching processes are particularly lossy. EP 4235 737 A1 describes a very complex cooling process, which can be improved with the device and / or method described here.

[0069] In one aspect, such an electrical power converter will improve the properties of a power supply system having a coupler unit, in particular a phase-shifting coupler unit, preferably a 90° hybrid coupler, as described, for example, in DE 102013226537 A1 or WO 2020 / 025547 A1. This coupler unit described therein can be used independently of further features as described in DE 102013226537 A1 or WO 2020 / 025547 A1. The coupler unit can preferably have a first and a second planar inductance, as also described in DE 102013226537 A1.

[0070] In one aspect, such an electrical power converter will improve the properties of a power supply system that includes GaN transistors as the element to be cooled. Such power converters are described, for example, in WO 2010 / 091696 A1 or WO 2010 / 091697 A1.

[0071] Such an electrical power converter will particularly preferably improve the properties of a power supply system that has SiC transistors as the element to be cooled. Such power converters are described, for example, in WO 2020 / 025547 A1.

[0072] In one aspect, such an electrical power converter will improve the properties of a high-power generator, in particular for generating a pulsed high voltage, as described, for example, in WO 2023 / 161522 A1.

[0073] The publications DE 10 2013226 537 A1 , EP 3 317 964 B1, EP3 317 965 B1 , WO 2010 / 091696 A1 , WO 2010 / 091697 A1, WO 2020 / 025547 A1 , WO 2023 / 161522 A 1 and EP 4235 737 A1 are incorporated in their entirety by reference into this application.

[0074] Further advantageous embodiments are described in more detail below with reference to several exemplary embodiments shown in the drawings, to which, however, the application is not limited.

[0075] Fig. 1 shows an electronic device comprising a printed circuit board assembly and a power module insertable into a recess of the printed circuit board assembly.

[0076] Fig. 2 shows the structure of the circuit board assembly consisting of single- and double-sided circuit boards and prepregs.

[0077] Fig. 3 shows a power module according to a first embodiment, which comprises a cooling structure manufactured by means of an additive manufacturing process.

[0078] Fig. 4 shows a power module according to a second embodiment, which has a heat sink manufactured by means of a metal layer bonding process.

[0079] Fig. 5 shows a printed circuit board arrangement and a power module inserted into a recess of the printed circuit board arrangement, wherein the fluidic contact of the power module takes place from the sides of the recess.

[0080] Fig. 6 shows a printed circuit board arrangement and a power module inserted into a recess of the printed circuit board arrangement, wherein the fluidic contact is made from the underside of the recess.

[0081] Fig. 7 shows a power supply system with one or more electronic devices described above or below.

[0082] In the following description of preferred embodiments of the present application, like reference numerals designate like or comparable components.

[0083] Fig. 1 shows an electrical device 100 according to an embodiment of the present application. The electrical device 100 comprises a printed circuit board assembly 1 comprising a plurality of interconnected printed circuit boards 2a to 2f. A recess 3 is provided in the printed circuit board assembly 1, extending from the top side of the printed circuit board assembly 1 into the printed circuit board assembly 1, but not completely penetrating the printed circuit board assembly 1. The recess 3 is provided and suitably dimensioned to accommodate a power module 4.

[0084] The power module 4 comprises an electrically insulating substrate 6, for example, a ceramic substrate. The substrate 6 has a first metallization 11 on its top side and a second metallization 9 on its bottom side. The first metallization 11 can comprise a plurality of electrically separated conductor structures 11a to 11c, which are structured, for example, by means of an etching process. The conductor structures 11a to 11c are clearly visible in particular in Fig. 3 and Fig. 4. A plurality of semiconductor components 12, 13a, 13b are arranged on the first metallization 11. The semiconductor components 12, 13a, 13b can be mechanically, electrically, and also thermally connected to the conductor structures 11a to 11c, for example, by means of chip bonding. The semiconductor components 12, 13a, 13b can be bare-die semiconductor elements, for example.Such semiconductor components, which may be designed for currents of more than 10 A and voltages of more than 400 V, for example, generate high levels of heat loss during operation, which must be dissipated. To dissipate the resulting heat, the second metallization 9 provided on the underside of the substrate 6 is mechanically and thermally connected to a cooling structure 16. When the power module 4 is inserted in the direction of arrow 17 into the recess 3 of the printed circuit board assembly 1, the cooling structure 16 is oriented toward the bottom of the recess 3. The power module 4 is inserted into the recess 3 and firmly connected there to the printed circuit board assembly 1.

[0085] A coolant supply line 18 is provided within the printed circuit board assembly 1. The coolant supply line 18 can, for example, be provided in the form of a recess in one of the printed circuit boards, for example in the printed circuit board 2c. Coolant can be supplied to the recess 3 via the coolant supply line 18. Furthermore, a coolant discharge line 19 is provided in the printed circuit board assembly 1, which can, for example, be provided as a recess in one of the printed circuit boards, for example in the printed circuit board 2c. The coolant discharge line 19 is designed to discharge coolant from the recess 3. When the power module 4 is inserted into the recess 3, the cooling structure 16 is in thermal contact with the coolant, which is supplied via the coolant supply line 18 and discharged via the coolant discharge line 19.The coolant flowing in thermal contact with the cooling structure 16 allows the heat generated by the semiconductor components 12, 13a, 13b during operation to be dissipated.

[0086] Fig. 2 shows the structure of a printed circuit board assembly 20 according to another embodiment. The printed circuit board assembly 20 comprises a sequence of single-sided printed circuit boards and / or double-sided printed circuit boards. Single-sided printed circuit boards have a conductive layer on only one side of the insulating layer, while double-layer printed circuit boards are provided with a conductive layer on both the top and bottom of the insulating layer. The printed circuit board assembly 20 can additionally have one or more prepreg layers.

[0087] A prepreg is a flat textile semi-finished product that can, for example, comprise woven or non-woven fabrics with perpendicularly arranged threads or unidirectional layers of threads pre-impregnated with a thermoplastic or thermosetting matrix. The prepreg matrix consists of a mixture of resin and hardener and can also contain an accelerator. During component production, prepregs can be cured under temperature and pressure, for example. Such prepregs can, for example, be inserted between adjacent conductive layers to electrically insulate the conductive layers from each other.

[0088] In the example shown in Fig. 2, the printed circuit board arrangement 20 comprises a first printed circuit board 21a. The first printed circuit board 21a is a single-sided printed circuit board which comprises a first insulating layer 22a and a first copper layer 23a applied thereto. A second printed circuit board 21b is adjacent to the first printed circuit board 21a. The second printed circuit board 21b is a double-sided printed circuit board which comprises a second insulating layer 22b, a second copper layer 23b and a third copper layer 23c. The subsequent third printed circuit board 21c is a double-sided printed circuit board which comprises a third insulating layer 22c, a fourth copper layer 23d and a fifth copper layer 23e. The fourth printed circuit board 21d is again a single-sided printed circuit board which comprises a fourth insulating layer 22d and a sixth copper layer 23f.In order to electrically insulate the third copper layer 23c of the second circuit board 21b from the fourth copper layer 23d of the third circuit board 21c in the circuit board arrangement 20 shown in Fig. 2, an insulating intermediate layer 24 is provided between the third copper layer 23c and the fourth copper layer 23d, which intermediate layer can be realized, for example, by means of a prepreg.

[0089] During the production of the printed circuit board assembly 20, the stacked printed circuit boards 21a to 21d, together with the intermediate layer 24 formed as a prepreg, are pressed together under heat and pressure to bond the individual layers together to form the multilayer printed circuit board assembly 20. In the example shown in Fig. 2, the printed circuit board assembly 20 comprises a total of six copper layers 23a to 23f.

[0090] Before the layers are pressed together, recesses for the coolant supply line 18 and the coolant discharge line 19 can be made in one or more of the circuit boards 21a to 21d, for example in the circuit board 21c. When the layers are pressed together, a coolant-tight coolant supply line 18 and a coolant-tight coolant discharge line 19 can be formed in this way.

[0091] The recess 3 shown in Fig. 1 can be structured either before or after the layers are pressed together. For example, suitable cutouts can be introduced into individual circuit boards before the layers are pressed together, which result in the recess 3 after the layers are pressed together. However, it is equally possible to form the recess 3 only after the layers have been pressed together, for example, by milling the finished pressed circuit board assembly 1 or 20.

[0092] Preferably, the recess 3 is structured such that the bottom of the recess is formed by one of the copper layers of the printed circuit board arrangement 1 or 20.

[0093] Through-contacts or vias can be provided in the insulating layers 22a to 22d of the circuit boards 21a to 21d in order to form electrical connections between the various copper layers 23a to 23f of the circuit boards. If crossovers were to occur in one copper level, this could, for example, be redirected to another copper level. Fig. 3 shows the structure of a power module 4 according to one embodiment. The insulating substrate 6 can be seen, on the upper side of which the first metallization 11 is applied and on the underside of which the second metallization 9 is applied. The substrate 6 can preferably be a ceramic substrate. Possible ceramic materials include, for example, aluminum oxide ceramic, beryllium oxide ceramic, aluminum nitride ceramic, and sapphire. The first metallization 11 can be applied to the substrate 6 using a bonding process, for example using direct-bonded copper (DBC).In this process, a copper foil is bonded to the substrate, such as a ceramic substrate, under pressure and high temperature. Such a positive connection exhibits very good and stable heat transfer.

[0094] Alternatively, metallizations such as IMS (Insulated Metal Substrate) or AMB (Active Metal Brazed) are possible. Insulated Metal Substrates (IMS) are circuit boards in which the dielectric layer consists of a polymer filled with ceramic powder. The heat-dissipating plate in IMS is usually made of aluminum. With AMB (Active Metal Brazed) substrates, one or more metal foils are soldered to a ceramic substrate using high-temperature soldering (800°C to 1000°C). AMB is particularly suitable for low-volume production.

[0095] The second metallization 9 is applied to the side of the substrate 6 facing away from the first metallization 11. The second metallization 9 can also be applied to the substrate 6 using a bonding process, for example, using direct-bonded copper.

[0096] The first metallization 11 can comprise electrically separated conductor structures 11a to 11c, as shown in Fig. 3. The formation of the first metallization 11 into the conductor structures 11a to 11c can be carried out, for example, by means of an etching process. The semiconductor components 12, 13a, 13b are attached to the conductor structures 11a to 11c. The semiconductor component 12 can be, for example, a three-terminal semiconductor component, for example a transistor. The semiconductor components 13a, 13b can be, for example, two-terminal semiconductor components, for example diodes. The semiconductor components 12, 13a, 13b can be designed, in particular, as power semiconductor components, for example as transistors and / or diodes for switching and conducting very high power, a very high current and / or a very high voltage.One or more, in particular all, semiconductor components 12, 13a, 13b can be embodied as bare dies, which are also referred to as bare chips, dies or chips. This refers to integrated electronic components that are not conventionally installed in a plastic or ceramic housing, but are further processed without a housing. They are applied directly to the conductor structures 11a to 11c of the substrate 6 and can be electrically connected to surrounding components or conductor structures by bonding, in particular by chip bonding. Bonding here refers to the connection of bare dies to other components or conductor structures. The semiconductor components 12, 13a, 13b can be positively and firmly connected to the conductor structures 11a to 11c of the first metallization 11 on their underside.The semiconductor components 12, 13a, 13b and the first metallization 11 can be connected to one another, for example, by means of at least one soldered connection, in particular a silver solder connection, at least one welded connection, by sintering, or a comparable process. Such a positive connection exhibits very good and stable heat transfer.

[0097] On the side of the substrate 6 facing away from the semiconductor components 12, 13a, 13b, the cooling structure 16 is molded onto the second metallization 9 or firmly connected to the second metallization 9. In the example of Fig. 3, the cooling structure 16 comprises a plurality of cooling fingers 65. The cooling fingers 65 are provided so that coolant flows around them within the recess 3 and thus dissipates the heat generated by the semiconductor components 12, 13a, 13b. The cooling fingers 65 can preferably be produced using an additive manufacturing process. To produce the cooling structure 16 shown in Fig. 3, for example, the second metallization 9 applied to the substrate 6 can be further built up using an additive manufacturing process, for example using selective laser melting. However, additive manufacturing processes can also include processes other than selective laser melting.An additive manufacturing process is characterized by the fact that the structure is gradually applied from the same material. The material can be melted during application. Lasers are currently suitable for this purpose, allowing for particularly fine structures.

[0098] Fig. 4 shows a power module 25 according to an alternative embodiment, in which the cooling structure 16 is realized in the form of a heat sink 5. In the embodiment shown in Fig. 4, the heat sink 5 is manufactured using a metal layer joining process. Individual metal foils 27a to 27h, preferably copper foils, are at least partially structured by laser processing and / or punching and / or manufactured by electroplating processes and then joined together. The structuring or manufacturing is carried out in such a way that after the layers have been joined together, a closed cooling channel 35 is created through which the coolant can flow. As an alternative to the embodiment shown in Fig. 4, several cooling channels could also be provided within the heat sink 5.Within the heat sink 5, the cooling channel 35 is arranged such that after the heat sink 5 is inserted into the recess 3, a continuous fluidic connection is formed between the coolant supply line 18, the cooling channel 35 of the heat sink 5 and the coolant discharge line 19.

[0099] The structured metal foils 27a to 27h are preferably bonded to one another using a bonding process under high pressure and at high temperature. For this purpose, oxide layers, for example, can be formed on the surfaces of the copper layers, which are then welded together, with the temperature preferably being selected so high that the oxide layers melt but the metal foils do not. In this way, the metal foils bond to form a monolithic heat sink. If the metal foils are made of copper, for example, this is also referred to as direct copper bonding, abbreviated to DCB. The metal foils 27a to 27h preferably have a thickness of 0.4 mm or less, in particular of 0.25 mm or less.

[0100] There are various options for manufacturing the power module 25 shown in Fig. 4. According to a first option, the substrate 6 provided with the metallizations 9 and 11 and the heat sink 5 are each manufactured in separate steps. The heat sink 5 is then firmly connected to the second metallization 9, for example, by means of a bonding process, in particular by means of direct copper bonding. In this way, the second metallization 9 can become part of the heat sink 5, in particular of the monolithic heat sink. Other forms of connection of the heat sink 5 to the second metallization 9 can be, for example, soldering, welding, or sintering.

[0101] According to a second, alternative manufacturing method, all layers—that is, the substrate 6, the second metallization 9, and the metal foils 27a to 27h from which the heat sink 5 is formed—are bonded together in a bonding process under high pressure and at high temperature, preferably using direct copper bonding and direct bonded copper. More preferably, the first metallization 11 is also applied to the top side of the substrate 6 in the same step.

[0102] Fig. 5 shows how a power module 4 according to the embodiment shown in Fig. 3 is inserted into the recess 3 of the printed circuit board arrangement 1. To fasten the power module 4 within the recess 3, a thermal process can preferably be carried out, wherein during this thermal process, for example, a soldered connection is formed between the power module 4 and the printed circuit board arrangement 1. Preferably, a fluid-tight seal can be created between the coolant supply line 18, the region of the recess 3 through which the coolant flows, and the coolant discharge line 19 by means of the soldered connection. For example, the solder can distribute itself around openings of channels and lines as a result of capillary forces, thus creating a fluid-tight transition between the coolant supply line 18, the region through which the coolant flows, and the coolant discharge line 19.It may be advantageous to preheat the cooling structure 16 before carrying out this thermal process in order to be able to carry out the thermal process in a shorter time and thus to keep the thermal load on the power unit 4 during the thermal process as low as possible.

[0103] The thermal process performed to connect the power module 4 to the printed circuit board assembly 1 can also be used to solder the semiconductor components 12, 13a, 13b onto the first metallization 11 of the substrate 6. Alternatively, the semiconductor components 12, 13a, 13b can be soldered in a separate thermal process, which is performed before or after soldering the power module 4 to the printed circuit board assembly 1.

[0104] Likewise, the thermal process provided for fastening the power module 4 in the recess 3 can also serve to solder components 28 onto the conductive structures on the top side of the printed circuit board arrangement 1. Alternatively, the soldering of the components 28 can take place in a separate step, which is carried out before or after the fastening of the power module 4. To form electrical connections between the conductor structures 11a to 11c on the substrate 6 of the power module 4 and contact areas on the top side of the printed circuit board arrangement 1, connection lugs 29 can be provided, which can be seen in Fig. 5. These connection lugs 29 are soldered, on the one hand, to the respective conductor structure 11a to 11c of the first metallization 11 and, on the other hand, to the relevant contact areas on the top side of the printed circuit board arrangement 1.

[0105] Fig. 6 shows how the power module 25, which comprises a heat sink 5 constructed from a plurality of metal foils 27a to 27h, is inserted into the recess 3 of the printed circuit board assembly 1. In Fig. 6, the coolant supply line 18 and the coolant discharge line 19 are routed to the underside of the recess 3, where they establish fluidic contact with the cooling channel 35 of the heat sink 5.

[0106] Fig. 7 shows a power supply system 500 with an electrical power converter 400, preferably a plasma processing arrangement or heating arrangement. The power converter 400 comprises one or more of the previously described electronic devices 100, for example, as shown in Fig. 4 and / or Fig. 5.

[0107] The power converter 400 may in particular be designed to generate an RF output power as previously described.

[0108] The power converter 400 may in particular be designed to generate a pulsed high voltage, as previously described.

[0109] The power supply system 500 further shows an impedance matching circuit 300 and a load 200. The load can be, for example: a plasma processing process, a laser excitation, a heating system, e.g. an inductive, a dielectric or a plasma torch operated heating system.

[0110] The power converter 400 is connected to the load 200 via the optional impedance matching circuit 300 and can thus supply the electrical power to the load 200.

[0111] The features disclosed in the above description, the claims and the drawings may be important both individually and in any combination for the realisation of the application in its various forms.

Claims

PATENT CLAIMS 1. Electronic device (100) comprising: - a printed circuit board assembly (1, 20) comprising a plurality of layers of printed circuit boards (2a-2f, 21a-21d), wherein the printed circuit board assembly (1, 20) has a recess (3) extending from the top side of the printed circuit board assembly (1, 20) into the printed circuit board assembly (1, 20), - a power module (4, 25) which can be inserted into the recess (3) and can be firmly connected to the recess (3), wherein the power module (4, 25) has a first metallization (11) on its upper side, on which at least one power component (12, 13a, 13b) can be or is attached, and wherein the power module (4, 25) has a cooling structure (16) which is designed to cool the first metallization (11) by means of a coolant, - wherein the printed circuit board arrangement (1, 20) comprises at least one coolant supply line (18) and at least one coolant discharge line (19), wherein the at least one coolant supply line (18) is designed to supply the coolant to the recess (3), wherein the at least one coolant discharge line (19) is designed to discharge the coolant from the recess (3), and - wherein the device is designed such that the cooling structure (16) is in thermal contact with the coolant when the power unit (4, 25) is inserted into the recess (3) and is firmly connected to the recess (3).

2. Electronic device (100) according to claim 1, characterized in that in the circuit board arrangement (1, 20) in at least one circuit board (2a-2f, 21a-21d) one or more recesses for forming at least one of the coolant supply lines (18) and / or at least one of the coolant discharge lines (19) are provided.

3. Electronic device (100) according to one of the preceding claims, characterized in that the recess (3) extends from the top side of the circuit board arrangement (1, 20) into the circuit board arrangement (1, 20), but does not penetrate the circuit board arrangement (1, 20), and / or is open towards the top side of the circuit board arrangement (1, 20).

4. Electronic device (100) according to one of the preceding claims, characterized in that the power module (4, 25) comprises an electrically insulating substrate (6) which has the first metallization (11) on its upper side and a second metallization (9) on its lower side, wherein the cooling structure (16) is thermally and mechanically connected to the second metallization (9).

5. Electronic device (100) according to claim 4, characterized in that the substrate (6) of the power package (4, 25) is one of the following: ceramic substrate, direct bonded copper (DBC), insulated metal substrate (IMB), active metal brazed (AMB), thick film substrate.

6. Electronic device (100) according to one of the preceding claims, characterized in that at least one of the power components (12, 13a, 13b) is designed as a bare die.

7. Electronic device (100) according to one of the preceding claims, characterized in that the at least one power component (12, 13a, 13b) is mounted on the first metallization (11) and has in each case at least one terminal which is thermally and electrically connected to at least one region of the first metallization (11).

8. Electronic device (100) according to one of the preceding claims, characterized in that at least one region of the first metallization (11) is electrically connected to at least one contact surface of a printed circuit board of the printed circuit board arrangement (1, 20) by means of at least one connection lug (29).

9. Electronic device (100) according to one of the preceding claims, characterized in that the device is designed such that the cooling structure (16) is in direct contact with the coolant when the power module (4, 25) is inserted into the recess (3) and is firmly connected to the recess (3).

10. Electronic device (100) according to one of the preceding claims, characterized in that the cooling structure (16) forms a monolithic structure with the second metallization (9).

11. Electronic device (100) according to one of the preceding claims, characterized in that the cooling structure (16) is at least partially formed by means of an additive manufacturing process, preferably by means of selective laser melting.

12. Electronic device (100) according to one of the preceding claims, characterized in that the cooling structure (16) comprises at least one cooling pin (65).

13. Electronic device (100) according to one of the preceding claims, characterized in that the cooling structure (16) comprises at least one heat sink (5) which has at least one cooling channel (35) through which the coolant can flow.

14. Electronic device (100) according to claim 13, characterized in that the power module (4, 25) can be connected to the printed circuit board arrangement (1, 20) in such a way that fluid-tight fluidic connections are formed between the at least one coolant supply line (18), the at least one cooling channel (35) and the at least one coolant discharge line (19).

15. Electronic device (100) according to claim 13 or claim 14, characterized in that the heat sink (5) is at least partially realized in the form of a layer structure of thermally bonded metal foils (27a-27h), preferably copper foils.

16. Electronic device (100) according to one of the preceding claims, characterized in that the at least one coolant supply line (18) and the at least one coolant discharge line (19) fluidically contact the recess (3) from the underside of the recess (3).

17. Electronic device (100) according to one of claims 1 to 15, characterized in that the at least one coolant supply line (18) and the at least one coolant discharge line (19) fluidically contact the recess (3) from the sides of the recess (3).

18. Electronic device (100) according to one of the preceding claims, characterized in that the power module (4, 25) is inserted into the recess (3) and is firmly connected to the recess (3).

19. Electronic device (100) according to claim 18, characterized in that the power module (4, 25) is connected to the recess (3) by soldering.

20. Electronic device (100) according to claim 19, characterized in that the solder seals the areas through which the coolant flows within the recess (3) and the power unit (4, 25).

21. A method for manufacturing an electronic device (100) starting from: - a printed circuit board arrangement (1, 20) comprising a plurality of layers of printed circuit boards (2a-2f, 21a-21d), wherein the printed circuit board arrangement (1, 20) has a recess (3) extending from the top side of the printed circuit board arrangement (1, 20) into the printed circuit board arrangement (1, 20), wherein the printed circuit board arrangement (1, 20) comprises at least one coolant supply line (18) and at least one coolant discharge line (19), wherein the at least one coolant supply line (18) is designed to supply a coolant to the recess (3), and wherein the at least one coolant discharge line (19) is designed to discharge the coolant from the recess (3), and - a power module (4, 25) having on its upper side a first metallization (11) on which at least one power component (12, 13a, 13b) can be or is mounted, wherein the power module (4, 25) has a cooling structure (16) designed to cool the first metallization (11) by means of the coolant, the method comprising the following steps: - inserting the power module (4, 25) into the recess (3) of the printed circuit board arrangement (1, 20) in such a way that the cooling structure (16) is oriented towards the bottom of the recess (3), - Carrying out a first thermal process for mechanically connecting the power module (4, 25) to the printed circuit board arrangement (1, 20).

22. Method according to claim 21, characterized in that the power module (4, 25) is soldered to the recess (3) by means of the first thermal process.

23. A method according to claim 21 or claim 22, characterized in that the method comprises the following step: - Preheating the cooling structure (16) before carrying out the first thermal process.

24. Method according to one of claims 21 to 23, characterized in that the method comprises the following step: - Making recesses in at least one of the circuit boards (2a-2f, 21a-21d) to form at least one of the coolant supply lines (18) and / or at least one of the coolant discharge lines (19), in particular before the circuit boards (2a-2f, 21a-21d) are connected to one another.

25. Electrical power converter (400) for an industrial process arrangement (500), preferably a plasma process arrangement or heating arrangement, comprising an electronic device (100) according to one of the preceding claims 1 to 20, in particular designed to generate an RF output power.

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