Circuit board and fluid heater

Description

[0001] The invention relates to a circuit board according to the preamble of claim 1 and a fluid heater equipped with such a circuit board.

[0002] Such fluid heaters are preferably used for heating gaseous or liquid media, for example, air or water. The basic design of these fluid heaters is explained, for example, in the applicant's patent application DE 10 2016 122 767 A1. This fluid heater, designed for heating air, has a heating element in the form of a tubular heating element, the heat from which is transferred to the fluid to be heated via a heat exchanger, also called a heat distribution element. In the specific fluid heater described in DE 10 2016 122 767 A1, this heat distribution element is designed as a metal sponge or wire mesh / wire netting, with the fluid flowing through the pores or channels formed thereby. Of course, other heat distribution elements, such as extruded profiles or corrugated fins, can also be used for heat exchange.The heating element is controlled by control and power electronics, the circuitry of which is mounted on a circuit board / printed circuit board and housed in an electronics enclosure. This enclosure is attached to a housing that contains the heating element and the heat distribution element. The enclosure also features an inlet and outlet for the fluid to be heated.

[0003] German patent application DE 10 2012 209 936 A1 describes a thick-film heater in which conductive traces are applied to a substrate using an additive manufacturing process. These conductive traces form a heating element.

[0004] In DE 10 2018 106 354 A1, which also originates from the applicant, it is proposed to use power semiconductors arranged on the circuit board as heating elements, so that the heat generated during the operation of the power semiconductors is transferred to the fluid to be heated via a heat distribution element.

[0005] The problem with this solution is that the heat generated by the power semiconductors is only produced at specific points relative to the total heat exchange surface. Therefore, considerable effort is required to achieve a more even heat transfer through the appropriate design of the heat distribution element. Furthermore, the technical complexity of this solution is substantial, as the interconnection of the power semiconductors, which are primarily used for heating, is more complex and expensive compared to conventional solutions with tubular heaters or PTC heating elements, due to the comparatively high price of the semiconductors.

[0006] In contrast, the invention is based on the objective of further developing the circuit board provided with a circuit forming control or power electronics and a heater implemented therein in such a way that effective heating of a fluid is made possible with reduced effort, in particular reduced circuit engineering effort.

[0007] This problem is solved with regard to the circuit board by the combination of features of claim 1 and with regard to the heater by the features of dependent claim 10.

[0008] Advantageous further developments of the invention are the subject of the dependent claims.

[0009] The circuit board / printed circuit board according to the invention is equipped with at least one heating element designed for a predetermined heating power for heating a fluid. This heating element is formed by conductor tracks shaped by a subtractive process, for example by etching, the cross-section, length, and material of which are designed according to the heating resistance required for the heating power. The material is accordingly selected so that it can be machined by a subtractive process, for example by etching or milling.

[0010] According to the invention, the circuit board / printed circuit board is thus initially designed with a continuous layer / layer formed from the material of the conductor track, from which the areas not forming a conductor track are then removed by etching or milling.

[0011] Such a solution makes it possible to easily adapt to different heating power levels by appropriately selecting the cross-section and geometry of the heating element, thereby significantly reducing the circuitry complexity compared to the solution described above with power semiconductors specifically designed for heating. According to the invention, such power semiconductors are only required for controlling or regulating the heating circuit. Thus, the invention utilizes the parasitic side effect of the conductor track heating up when it is energized.

[0012] According to the invention, the circuit board is designed with a heat distribution layer for heat transfer to the fluid. This heat distribution layer can, for example, be designed as a molded part that is integrated into the layer structure of the circuit board and is optimized with regard to fluid flow and heat transfer. By integrating the heat distribution layer into the circuit board / printed circuit board structure, the tooling effort is reduced compared to conventional solutions where a separate heat distribution element, such as heat exchange surfaces or the like, is required.

[0013] The circuit board is preferably designed as an IMS (Insulated Metal Substrate) printed circuit board, in which a heat distribution layer is already conceptually integrated.

[0014] Another significant advantage of the solution according to the invention is that the suitable surface area of ​​the heating strands / conductor tracks ensures a uniform heat distribution for heating the fluid.

[0015] In one embodiment of the invention, in addition to the heating element on the circuit board / printed circuit board, a control circuit and / or power electronics are provided, which are designed, for example, to control the heating element or other electronic components.

[0016] According to a preferred embodiment of the invention, several heating elements are formed on the circuit board, which can be individually controlled.

[0017] Each IMS board can be multilayered with at least two functional layers, each containing a heating element and / or control circuitry and / or power electronics. Accordingly, one layer of the IMS board can function as a heating element, while another layer can house control circuitry or power electronics. Hybrid configurations are also possible, where one layer functions both as a heating element and as the control circuitry for components. In principle, the IMS board can also be a single layer, with this layer fulfilling the function of both a heating element and control circuitry / power electronics.

[0018] Heat transfer is further improved if the heating element is implemented, at least in sections, with meandering conductor tracks. Alternatively, the conductor tracks can also be arranged in parallel or in series and / or parallel configurations.

[0019] Manufacturing the circuit board and its connection elements is particularly simple when the latter and other functional elements are formed by bending tabs or edge sections of the IMS circuit board. For example, it is possible to guide a conductor track end section to such an edge section and then form a contact tab or the like by bending it.

[0020] Furthermore, it is possible that at least one heating element is formed in the bent section, which is contacted via sections of the conductor track that extend over the bent areas. It is also possible to have at least one heating element run section by section within the bent area.

[0021] The heater according to the invention has a heating element implemented with a circuit board of the type described above.

[0022] The conductor track can be meandering or bifilar.

[0023] It is particularly preferred if the circuit board at least partially delimits a fluid channel through which the fluid flows or a fluid chamber containing the fluid. In such a variant, the circuit board forms part of the fluid channel / fluid chamber. This concept, with a fluid chamber partially delimited by the circuit board, is the subject of a parallel patent application filed by the applicant.

[0024] Preferred embodiments of the invention are explained in more detail below with reference to schematic drawings. These show: Figure 1 a three-dimensional representation of a first embodiment of a fluid heater according to the invention; Figure 2 the fluid heater according to Figure 1 with the lid removed; Figure 3 a schematic diagram of an IMS circuit board of the fluid heater according to the Figures 1 and 2 ; Figure 4 a detailed representation of the IMS circuit board according to Figure 3 ; Figure 5a schematic representation of the cross-section of such an IMS printed circuit board; Figure 6 A diagram illustrating the geometry of two heating elements on an IMS circuit board according to the Figures 4 and 5 ; Figure 7 a section along line AA in Figure 1 ; Figure 8 a corresponding section of another embodiment of a fluid heater; Figure 9 a single illustration of a molded part for fluid guidance in a heater according to the invention and Figures 10a, 10b Highly schematic representations of exemplary embodiments in which the circuit board according to the invention forms connecting elements and / or a fluid space by bending.

[0025] Figure 1Figure 1 shows a three-dimensional representation of a first embodiment of a fluid heater 1 according to the invention, for example a high-voltage heater, which is used, for example, for heating water or another liquid. The fluid heater 1 has a multi-part housing 2 with a central part 4 and a [missing information] in the view shown in Figure 1. Figure 1 The upper and lower covers 6 and 8. This housing 2 defines a fluid chamber for the fluid to be heated, which will be discussed in more detail later. Two fluid connections 10 and 12 open into this fluid chamber, with, for example, fluid connection 10 serving as an inlet and fluid connection 12 as an outlet. Both connections 10 and 12 are connected to a piping system that carries the fluid to be heated. In the illustrated embodiment, the fluid connections 10 and 12 are designed as connection nozzles on the central part 4. Of course, these connections can also be provided on the cover side.

[0026] The housing 2 according to the invention further accommodates at least one circuit board 14 (see Figure 2 ) which is equipped with at least one heating circuit for heating the fluid and may include additional electronic components for controlling this heating circuit and other heater components. For the power supply of this control and / or power electronics as well as the electronic components, the following is required in the Figure 1 In the illustrated embodiment, a low-voltage connector 16 and a high-voltage connector 18 are formed on the central part 4, the latter serving for the high-voltage power supply and the low-voltage connector also for signal transmission. To compensate for pressure fluctuations occurring during operation, a [missing information] is provided in the electronics compartment housing the control and power electronics. Figure 1A pressure equalization element designated with reference numeral 20 is provided. The housing components can be made of suitable coated plastic or a suitable metal alloy, for example, to address EMC issues.

[0027] Figure 2 The housing shows 2 according to Figure 1 , with the upper cover 6 removed. The aforementioned electronics compartment 22 is then visible, in which the circuit board 14 is located. This circuit board can house, on the one hand, control and / or power electronics and, on the other hand, the actual heating element of the fluid heater 1. In the illustrated embodiment, the circuit board 14 is configured with two heating circuits 24, 26, the specific structure of which will be described later with reference to the Figures 3 to 6 is explained. According to the presentation in Figure 2The electronics compartment 22 does not fill the entire interior of the housing 2, but is, for example, surrounded by an outer compartment 28 which in this embodiment is approximately L-shaped, in which further components of the fluid heater, for example wiring, may be accommodated.

[0028] Between the removed upper cover 6 and the circuit board 14, as well as between the lower cover 8 and, if applicable, another circuit board or the circuit board 14, a gap remains in each case. Figure 2 Invisible free space in which, for example, an additional control board or other components, such as a temperature sensor or the like, may be accommodated.

[0029] In a manner that is known in itself, the following are Figure 2The visible end faces of the central part 4 have sealing contours 30, which serve to fix the position of a seal. Corresponding contours are also formed on the upper cover 6 and the lower cover 8, so that the housing 2 can be closed fluid-tight. The central part 4 is clamped to the two covers 6, 8 by means of screws that are screwed into corresponding threaded bores 32 in the central part 4. Of course, instead of such a screw connection, the housing 2 can also be joined by a material bond.

[0030] Figure 3 Figure 1 shows a detailed view of the circuit board 14 housed in the enclosure 2. This board is designed as an IMS circuit board – the basic structure of such IMS circuit boards 14 will be explained later. Figure 5 explained.

[0031] In the illustrated embodiment (see also Figure 4As mentioned above, circuit board 14 is configured with two heating circuits, 24 and 26, where heating circuit 24 is designed for a heating output of, for example, 2 kW and heating circuit 26 for a heating output of, for example, 1 kW. The power supply to the two heating circuits, 24 and 26, is provided via terminals 34 and 36 (heating circuit 24) and 38 and 40 (heating circuit 26), respectively, which protrude from the plane of the circuit board. Switching the heating circuits, which will be described in more detail below, is accomplished via switching elements 42 and 44, which are implemented, for example, as IGBT modules and are part of the circuit formed by circuit board 14. The connections of these switching elements 42 and 44 are shown in the diagram. Figure 3 with the reference numbers 46, 48, 50, 52, 53. On circuit board 14, according to Figure 3Further electronic components 54, 56 of the control and / or power electronics are implemented. In principle, a sensor for measuring the fluid temperature can also be integrated into the circuit implemented by the circuit board 14.

[0032] As explained above, the components described are located on the circuit board 14, so that their power loss is also transferred to the fluid in the form of heat. A solution of this kind, in which the electronic components, for example semiconductor components, are designed as heating elements, is described in DE 10 2018 106 354 A1, which was described at the outset. In contrast to this solution, the heating strands of the two heating circuits 24, 26, formed by conductor tracks, are designed with regard to the heating power to be transferred. As explained at the outset, however, the circuit board according to the invention is not limited to an embodiment in which the conductor tracks are provided together with control elements and / or power electronics – in principle, it is sufficient if the circuit board 14 only has a heating strand formed by at least one conductor track, which is designed with regard to heating a fluid.

[0033] Figure 4 shows the area of ​​circuit board 14 occupied by the aforementioned electronic components. Figure 3 in a detailed view. This illustration clearly shows that, in this embodiment, the two heating circuits 24, 26 – as mentioned above – are implemented by heating strands 58, 60 formed from conductor tracks, with the conductor tracks each arranged in a meandering pattern on the circuit board 14. This will be explained later using Figure 6 clarifies.

[0034] As mentioned at the beginning, board 14 is designed as an IMS board. According to this, Figure 5 A heat distribution layer 62, typically made of a metal such as aluminum or copper, is formed in a manner known per se, and its thickness can vary between 0.3 mm and 10 mm. A layer thickness of approximately 1.5 mm has become the standard.

[0035] On this heat distribution layer 62, which is designed for optimal heat transfer to the fluid to be heated, an integrated insulating layer 64 is applied. This insulating layer typically has a thickness of 75 µm to 200 µm and consists of a good electrical insulating material, preferably plastic. The conductor track 66, which forms the actual heating element 58, 60, is then applied to this insulating layer 64. This conductor track consists of a material that can be machined by etching or milling, such as copper, zinc, silver, gold, or nickel, with copper being preferred.

[0036] As explained in DE 10 2018 106 354 A1, a conductor layer is first applied over the entire surface, and then the meandering or bifilar structure of the heating strands 58, 60 and the conductor track sections leading to the aforementioned components / switching elements, which will be explained in more detail below, is created by an etching process, so that the in the Figures 4and 6 The heating circuit structure is indicated.

[0037] For electrical insulation and moisture protection, an insulating layer, for example a layer of solder mask 68, can then be applied to this etched IMS circuit board 14 in a further step, covering the conductor track structure. Areas are left uncoated for the placement of the aforementioned switching elements 42, 44 and electronic components 54, 56 in a subsequent assembly operation – for example, using SMD technology. After this assembly according to a placement plan, the outer shape of the IMS circuit board 14 is then formed in a fourth step by punching, milling, and / or sawing.

[0038] The structure of the heating strands 58, 60 is designed with regard to the desired heating power. The heating resistance of the two heating strands 58, 60 is essentially determined by the material, length, and cross-section of the conductor tracks 66, which are arranged, for example, in a meandering or bifilar pattern. Accordingly, the conductor track width b, the layer thickness d of the conductor track 66, and its length are selected such that the heating resistance required for the predetermined heating power is achieved. The heating resistance can also be locally varied by varying the cross-section (b, d). This local variation of the heating resistance allows for the deliberate creation of hotspots, which act as a kind of fuse and melt in the event of excessive temperature or current. Similarly, zones with fewer conductor tracks, and thus lower power density, can be created locally.The spacing a of the individual conductor tracks 66 of the meander structure also has an influence on the power density.

[0039] Figure 6 Figure 1 shows the basic structure of the heating circuit 24, which is designed with a higher heating capacity and essentially consists of two heating strands 58a, 58b. These strands can be controlled individually or together via the aforementioned switching elements 42, 44 and electronic components 54, 56. As explained, in this embodiment, each heating strand 58a, 58b is formed by a meandering conductor track 66, with longer conductor track sections 70, 72 being connected to each other via deflections 74.

[0040] Of course, as mentioned above, other structures can be used instead of the meandering structure, for example, parallel conductor tracks arranged in parallel or series, bifilar structures, or hybrid forms of these structures. In the case of the Figure 6In the illustrated embodiment, the deflections 74 are designed as straight elements running transversely to the conductor track sections 70, 72. In the embodiment shown Figure 4 In the illustrated embodiment, the deflections 74 are rounded (see also the dashed line in Figure 6 ).

[0041] The individual heating circuit 60 of the second heating circuit 26 has a corresponding structure, wherein the heating output of the individual heating circuits 58a, 58b and 60 is designed according to the desired maximum heating output in the illustrated embodiment.

[0042] Figure 7 shows a section along line AA in Figure 1This sectional view shows the circumferential walls of the central part 4, onto which the upper cover 6 and the lower cover 8 are sealed. In the illustrated embodiment, the central part 4 carries an IMS circuit board 14 designed according to the preceding descriptions, which is equipped with at least one heating circuit and can additionally carry components of the control and power electronics. This circuit board 14 is arranged in the area that is extended by the upper cover 6.

[0043] In the area extending beyond the lower cover 8, another circuit board 14' is formed, which, like circuit board 14, can be equipped with a heating circuit and / or other components of the control and / or power electronics. In principle, it is also possible to design circuit board 14 with several heating circuits as a "heating circuit board," while the other circuit board 14' houses the electronic components required for control and regulation, i.e., the components of the control and power electronics, so that each circuit board 14, 14' is optimized with regard to its respective function (heating - control, regulation). The circuit boards 14, 14' are held in a sealing manner on the central part 4 by suitable sealing elements 76, 78, so that a fluid chamber 80 is formed by the circuit boards 14, 14' and the central part 4, through which the fluid to be heated flows or in which the fluid to be heated is contained. The circuit boards 14, 14' according to the invention thus directly delimit the fluid space 80.This is a significant difference to the solution according to DE 10 2018 106 354 A1, in which the circuit board is attached to the circumferential walls of the fluid space, so that no direct heat input from the circuit board into the fluid occurs.

[0044] At the in Figure 7 In the illustrated embodiment, the aforementioned temperature sensor 82 protrudes into the fluid chamber 80. The pressure equalization element 20 is also visible, as shown in the illustration. Figure 7 The pressure equalization element 20 is shown as an example running coaxially to the axis of the temperature sensor 82. As explained at the beginning, this optional pressure equalization element 20 ensures that pressure fluctuations in the free spaces 85, 87 located above and below the fluid chamber 80, which form a kind of electronics compartment, are compensated.

[0045] The circuit boards 14, 14' are arranged such that the aforementioned heat distribution layers 62 sectionally delimit the fluid space, while the electronic components and the heating elements 58a, 58b, 60 are arranged with the conductor tracks 66 pointing towards the two free spaces 85, 87. As mentioned above, further circuit boards or other control / power electronics elements, not shown here, can be arranged in these free spaces 85, 87.

[0046] In the cut according to Figure 7 One can also see part of the based Figure 2 The external space 28, in which, for example, cabling may be routed and which is connected to the two free spaces 85, 87, is described. In the case where the fluid space 80 is flowed through by the fluid, fluid guidance elements 84 can be provided in the area of ​​the fluid space 80 (see Figure 8 ).

[0047] At the in Figure 7In the illustrated embodiment, the fluid chamber 80 is arranged centrally between the two circuit boards 14, 14'. In principle, it is also possible to mount the circuit boards rotated 180° so that the heat distribution layers 62 point towards the upper cover 6 and the lower cover 8, respectively, and thus each cover 6, 8 defines two fluid chambers that are in fluid communication with each other. In such a variant (not shown), the components of the control or power electronics and also the heating elements 58a, 58b, 60 are arranged pointing towards the common central chamber between the circuit boards 14, 14'. Accordingly, the pressure equalization element 20 would then have to be in operative communication with the central chamber, while the temperature sensor 82 would have to be arranged in at least one of the chambers defined by the covers 6, 8.

[0048] Figure 8 shows a variant of the embodiment according to Figure 7, in which the two plates 14, 14' sectionally delimit the central fluid chamber 80 and the two covers 6, 8, together with the plates 14, 14', each form a free space 85, 87. In this respect, the embodiment corresponds to Figure 8 according to that one Figure 7 Unlike Figure 7 is in the embodiment according to Figure 8 A fluid guidance element 84, 84' is attached to each of the circuit boards 14, 14', which faces the fluid chamber 80. This element improves the heat transfer from the previously described heating elements 58a, 58b to the fluid and also serves to guide the flow. In the illustrated embodiment, the fluid guidance elements 84, 84' are made of a material with good thermal conductivity, for example, aluminum, and are attached directly to the heat distribution layer 62 of the respective circuit board 14, 14' in a thermally conductive manner.

[0049] In the illustrated embodiment, the fluid guidance element 84, 84' is designed with a continuous base plate 86 facing the fluid chamber 80, from which projections 88 extend towards the circuit board 14, 14', so that fluid-guiding channels 90 are formed between adjacent projections. The flow path is selected such that, for example, the inlet to the fluid heater 1 is in fluid contact with the channels 90, so that the flow in the channels 90 – as in Figure 8 As indicated, the flow initially occurs away from the viewer and is then deflected via suitable deflection elements (not shown) so that the flow in fluid chamber 80 flows towards the viewer. Of course, other flow patterns are also possible. As explained, the heat Q to be transferred to the fluid is transferred in the direction of the arrow from the circuit board 14, 14' via the respective fluid guide element 84, 84' to the fluid contained in fluid chamber 80.

[0050] As already mentioned in connection with Figure 7 As explained, the circuit boards 14, 14' can also be installed rotated by 180° so that the fluid guide elements 84, 84' are arranged pointing towards the respective free space 85 or 87 and these then form corresponding fluid spaces, while the central space 80 is the electronics space, which is sealed off from the fluid spaces.

[0051] Figure 9 Figure 1 shows a specific embodiment of a fluid guidance element 84. As shown, this element has a base plate 86 from which the projections 88 extend. In the illustrated embodiment, these projections each have an approximately teardrop-shaped cross-section 94 that optimizes the flow around them. The in Figure 9 The fluid guidance element 84 shown is made of an aluminum alloy, for example by die casting or extrusion.

[0052] As explained above, the projections 88, with their teardrop-shaped end faces, rest on the heat distribution layer 62 of the respective circuit board 14, 14', preferably using a sealing system to ensure a defined flow within the channels 90. A certain degree of leakage is, in principle, unproblematic. In this embodiment as well, the fluid chamber 80 is sealed against the free spaces 85, 87 and the external space 28 by suitable sealing elements 76, 78.

[0053] As explained above, a special feature of the invention is that, firstly, the circuit boards 14, preferably IMS circuit boards 14, 14', are designed as heating elements and, secondly, define a portion of a fluid space that receives the heating fluid. Based on the Figures 10a, 10b Further training courses based on this concept will be explained.

[0054] Figure 10aFigure 1 shows a variant in which the heat distribution layer 62 is slightly recessed in the edge areas of a circuit board 14, so that this recessed area, as in Figure 2, Figure 10a The dashed line indicates that the conductor track end section 66 can be bent upwards towards the side receiving the conductor track 66 to form connection tabs or other functional elements. This bending is preferably carried out partially, only in those areas where such functional elements, for example connection tabs, must be formed. In the latter case, a conductor track end section 66' can extend into the area cut out or delimited according to the connection tab to be formed, which is then bent into the connection tab in a subsequent operation.

[0055] In a further development of the invention, a heating element can also be formed completely or partially within the bent area, with contact preferably being made via the conductor track 66. In such an embodiment, the heating element is thus also formed in the narrower bent side walls of the fluid channel. Naturally, in such an embodiment, contact can also be made via contact tabs bent out from this bent side wall, in the area of ​​which a conductor track end section (66') then terminates.

[0056] In Figure 10bThis concept is further developed in such a way that the weakened edge regions of the heat distribution layer 62 have significantly larger dimensions, so that by corresponding double bending by 90°, side walls 96 and cover walls 98, 100 are formed, which then together form at least partial circumferential walls of the fluid chamber 80. In such an embodiment, only one circuit board 14 with a heating circuit 24, 26 according to the invention would be implemented. In this embodiment, the circumference of a fluid channel is formed at least partially by the described bending. Of course, it is also possible to form an open structure, for example by bending side walls 96 and then designing the cover wall as a separate component.As explained above, conductor track sections or conductor track end sections can also extend into the bent areas to enable contact with other components.

[0057] The IMS circuit boards can also be designed with multiple layers, forming superimposed conductor layers separated by insulating layers. These layers then each form part of a heating circuit and / or the control or power electronics. For example, a passive sensor element can be integrated, with one conductor layer used for current distribution and the other essentially functioning as a heating circuit. In principle, however, several layers can also be configured as a heating circuit, with the respective heating power being adjusted by varying the cross-section, particularly the conductor thickness d.

[0058] In principle, the fluid space 80 in such variants can also be limited on the one hand by a single-layer circuit board and on the other hand by a multi-layer circuit board with heating or current distribution function.

[0059] A circuit board with a heating element formed from conductor tracks and a heater made with such a circuit board are revealed. Reference symbol list:

[0060] 1 Fluid heater 2 Housing 4 Middle section 6 Top cover 8 Bottom cover 10 Fluid connection 12 Fluid connection 14 Circuit board 16 Low-voltage connector 18 High-voltage connector 20 Pressure equalization element 22 Electronics compartment 24 Heating circuit 26 Heating circuit 28 Outer compartment 30 Sealing contour 32 Threaded hole 34 Connection tab 36 Connection tab 38 Connection tab 40 Connection tab 42 Switching element 44 Switching element 46 Connection 48 Connection 50 Connection 52 Connection 53 Connection 54 Electronic component 56 Electronic component 58 Heating element 60 Heating element 62 Heat distribution layer 64 Insulation layer 66 Conductor trace 66' Conductor trace end section 68 Solder mask 70 Conductor trace section 72 Conductor trace section 74 Deflection 76 Sealing element 78 Sealing element 80 Fluid chamber 82 Temperature sensor 84 Fluid guide element 85 Clearance 86 Base plate 87 Clearance 88 Projection 90 Channel 94 Cross section 96 Side wall 98 Ceiling wall 100 Ceiling wall

Claims

1. A printed circuit board having at least one conducting path (66), characterized by at least one heating line (58, 60) formed by the conducting path (66) shaped via a subtractive method and designed to have a predetermined heating power for heating a fluid and having a heat dispersion layer (62) for transferring heat to the fluid.

2. The printed circuit board according to patent claim 1, having a control circuit and / or power electronics which is in operative connection with the heating line (58, 60) or to which a further conducting path is assigned.

3. The printed circuit board according to patent claim 1 or 2, wherein the heating line (58, 60) is formed by conducting paths (66), the cross-section, length and material of which are designed according to the heating resistance required for the heating power.

4. The printed circuit board according to one of the preceding patent claims, wherein a fluid guiding element (84) is formed adjacent to the heat dispersion layer (62).

5. The printed circuit board according to one of the preceding patent claims, wherein a plurality of heating lines (58, 60) are formed thereon.

6. The printed circuit board according to one of the preceding patent claims, wherein the printed circuit board is formed in multiple layers and wherein at least one heating line (58, 60) and / or a circuit forming the control circuit or the power electronics are provided in each layer.

7. The printed circuit board according to one of the preceding patent claims, wherein the heating line (58, 60) is formed by at least one meander-shaped or bifilar conducting path (66).

8. The printed circuit board according to one of the preceding patent claims, wherein it is an IMS-printed circuit board (14, 14').

9. The printed circuit board according to patent claim 8, wherein functional elements are formed by bending tabs or edge portions of the printed circuit board (14, 14'), wherein at least the conducting path (66) or a conducting-path terminal portion (66') for forming a contact tab or a heating line / heating line portion is led into the bent region.

10. A heater comprising a heating element adapted to heat a fluid flowing through or contained in a fluid compartment (80), characterized by at least one printed circuit board (14) according to one of the preceding patent claims.

11. The heater according to patent claim 10, wherein the printed circuit board (14) bounds the fluid compartment (80) in sections.