Planar power transformer and assembly

Abstract

The invention relates to a planar electrical component (10) comprising a substrate (5), in particular formed from a prepreg sheet, comprising the following bonded into the mass of the substrate (5): at least one primary conductive winding (12) in a first layer of the substrate (5), forming at least part of a primary circuit for the power transformer (1); and additionally, at least one secondary conductive winding (22) in a second layer of the substrate (5), superimposed on the first layer, forming at least part of a secondary circuit for the power transformer (1).

Description

Technical Field

[0001] The present invention relates to the field of power transformers. More particularly, the present invention relates to a planar electrical component for forming a planar power transformer. Background Art

[0002] This power transformer belongs, for example, to a circuit on board an electric vehicle or a hybrid vehicle, which circuit is usually referred to as an “on-board power system”.

[0003] This transformer makes it possible, for example, to transfer a voltage of 12 V or 48 V to a voltage higher than 300 V, for example 400 V or 800 V, and vice versa. As an alternative, this transformer is associated with an inverter / rectifier, so that an energy storage unit belonging to the vehicle, which has a voltage of, for example, 48 V or higher, for example higher than 300 V, such as 400 V, 800 V or higher, can be charged from a power grid external to the vehicle.

[0004] The invention therefore relates to the manufacture of a planar power transformer, that is to say a planar power transformer comprising a planar monolithic electrical component to which a ferromagnetic core is added.

[0005] A series of problems are known in which such power transformers need to be produced in a compact form while still taking into account the associated constraints regarding heating and cooling.

[0006] The most conventional known structure for power transformers consists of a winding of copper wire turns around a ferromagnetic core, which is usually made of ferrite. However, this type of coil is very bulky because the winding extends spatially around the ferromagnetic core as a volume, or in other words, extends substantially uniformly in all three dimensions of space.

[0007] According to the prior art, it is known in practice to produce a coil consisting of thin layers of conductive material, in particular copper, superposed and separated by thin electrically insulating layers. The layers of conductive material are brought into mechanical and electrical contact with one another, in particular by welding, to form a helix capable of acting as a coil. In this way, a substantially planar coil is obtained with a small spatial volume.

[0008] However, in order to form an electric transformer, it is necessary to have a primary circuit and a secondary circuit that are magnetically coupled via a ferromagnetic core. Therefore, in order to produce an electric transformer of reduced volume, even taking into account the above-mentioned techniques for substantially planar coils, in the prior art, a printed circuit board (also called PCB) is produced, this board being formed by a substrate, for example made of pre-impregnated material, incorporating at least one conductive winding forming the secondary or primary circuit of the electric transformer. Next, at least one further winding is added to this PCB, forming the primary or secondary circuit respectively, and a ferromagnetic core is also added in order to produce a complete electric transformer. Therefore, to the PCB incorporating the secondary winding or the primary winding is added another conductive winding, generally made of copper, which is soldered or welded or even adhesively bonded to the PCB.

[0009] Therefore, there is still a need for a planar power transformer with a smaller size, and a corresponding method of manufacturing.An object of the present invention is generally to facilitate industrial-scale manufacturing of planar power transformers. Summary of the invention

[0010] More specifically, the invention relates to a planar electrical component comprising a substrate, in particular formed from a prepreg sheet. The planar electrical component comprises the following items incorporated into the mass of the substrate:

[0011] at least one primary conductive winding in the first layer of the substrate and forming at least a portion of a primary circuit for a power transformer, and on the other hand

[0012] At least one secondary conductive winding is in a second layer of the substrate superimposed on the first layer and forms at least a portion of a secondary circuit for the power transformer.

[0013] It is noteworthy that the secondary conducting winding is held in the planar electrical component only by the material of the substrate, in particular only by assembling prepreg sheets of material forming the substrate. Prepreg sheets is an expression used as a synonym for sheets of preimpregnated material.

[0014] According to one embodiment, the electrical component according to the invention comprises a plurality of first layers and a plurality of second layers which are alternately stacked. According to one embodiment, the at least one primary conductive winding is in the shape of a spiral.

[0015] According to one embodiment, the at least one secondary conductive winding has a wavy shape in the plane of the second layer.According to one embodiment, the planar electrical component comprises a plurality of secondary conductive windings which are connected in parallel to a common secondary electrical connection terminal.

[0016] According to one embodiment, the substrate is obtained from a stack of several pre-impregnated thermosetting material sheets together.

[0017] According to the variant:

[0018] a first layer of the substrate is obtained from at least a first prepreg sheet, wherein the at least one primary conductive winding is etched onto one of the faces of the first prepreg sheet, and

[0019] The second layer of the substrate is obtained by adding the at least one secondary conductive winding to the prepreg face of the first layer and by covering said secondary conductive winding with a second prepreg sheet.

[0020] In particular, in the context of the present application, "prepreg face" refers to the outer surface of a layer, which surface is completely formed by prepreg material.

[0021] According to the subvariant:

[0022] a first layer of the substrate being obtained from a first prepreg sheet, wherein a respective primary conductive winding is etched onto each of the faces of the first prepreg sheet, a third prepreg sheet then covering one face of the first prepreg sheet;

[0023] The second layer of the substrate is obtained by adding the at least one secondary conductive winding to the free face of the third prepreg sheet and by covering the at least one secondary conductive winding with said second prepreg sheet.

[0024] According to one embodiment:

[0025] The primary conductive winding is formed by an electrical track having a thickness in particular less than or equal to 0.25 mm; and

[0026] The secondary conductive winding is formed by conductive blades (or even rigid conductors, such as conductive rods) having a thickness in particular greater than or equal to 0.4 mm and / or less than 2 mm.

[0027] In at least the first layer, the primary conductive winding may be an electrical track defining two spirals connected in series. The two spirals may have the same shape and be symmetrical relative to each other about an axis intersecting the substrate. This axis then intersects the series connection between the two spirals.

[0028] The electrical track defining the primary conductive winding may maintain the same width from one end of one spiral to the other, including at the series connection between the two spirals.

[0029] Each spiral can have a primary connection terminal at its free end, which enables the primary conducting winding to be connected to the outside, for example to the high-voltage part of the on-board power supply.

[0030] From one helix to another there may be the same number of turns, for example between three and ten turns, for example five turns.

[0031] When there are a plurality of first layers, all or some of these first layers may comprise electrical tracks defining two spirals connected in series, and these different series spirals may be connected in parallel from one first layer to another.

[0032] In at least one second layer, the secondary electrical winding may be a conductive vane having a wavy shape.

[0033] In the stacking axis along which the first layer is stacked with the second layer, the conductive blades and the electrical tracks defining the two spirals connected in series may at least partially overlap. This arrangement enables the inductive effect to be further enhanced.

[0034] The conductive vane may have a W-shape when viewed along this stacking axis.

[0035] The blade defines, for example, two undulations, each undulation comprising two straight portions connected to each other by a curved portion.

[0036] The first undulation may extend between a first secondary connection terminal connecting the secondary conductive winding to the outside and a second secondary connection terminal connecting the secondary conductive winding to the outside. This connection is, for example, to a low voltage part of the on-board network.

[0037] The second undulating portion may extend between the second secondary connection terminal and a third secondary connection terminal connecting the secondary conductive winding to the outside. The second secondary connection terminal may enable an intermediate connection to be defined in the secondary electrical winding, for example at a midpoint. As an alternative, only two secondary terminals may be provided: a first secondary terminal and a third secondary terminal.

[0038] When there are primary terminals and secondary terminals, the primary terminals may protrude from the same first side of the substrate, while the secondary terminals may protrude from the same second side of the substrate. These first and second sides of the substrate are, for example, opposite sides. The high voltage part and the low voltage part of the transformer may thus be separated from each other in order to better comply with different electrical isolation constraints.

[0039] Each straight portion of the conducting blade may overlap along the stacking axis with a straight portion of the spiral of the electrical track in the first layer. This then improves the coupling.

[0040] The cumulative width of the turns constituting the straight portion of the helix may be substantially equal to the width of the straight portion of the conductive blade superimposed thereon.

[0041] When there are multiple second layers, all or some of these second layers may comprise conductive vanes as described above.These individual vanes may be connected in parallel from one second layer to another second layer.

[0042] The above-mentioned overlap may exist with respect to all first layers and all second layers.

[0043] The invention also relates to an electric transformer comprising an electric component according to the invention and a ferromagnetic core added to the substrate in order to magnetically couple the primary conductive winding with the secondary conductive winding. In particular, the ferromagnetic core is added to a through opening in the planar electric component.

[0044] In particular, the planar electrical component is tightly pressed against the heat sink or against the fluid-cooled cooling plate, so that one face of the ferromagnetic core is tightly pressed against the heat sink or against the fluid-cooled cooling plate, so as to cool the ferromagnetic core.

[0045] Furthermore, the invention relates to a method for producing an electrical component comprising a primary circuit and a secondary circuit, the method comprising the following steps:

[0046] forming a first layer comprising a first prepreg sheet and etching a primary conductive winding onto one of the faces of said sheet, said primary conductive winding being intended to form at least a part of a primary circuit of an electric transformer;

[0047] providing a monolithic electrical conductor known as a secondary conductive winding;

[0048] placing a secondary conductive winding on the prepreg face of the first layer, the secondary conductive winding being intended to form at least a portion of a secondary circuit of a power transformer;

[0049] placing a second prepreg sheet on top;

[0050] The entity consisting of the prepreg sheets and the primary and secondary conductive windings is pressed and heated so as to assemble the sheets together and form an electrical component comprising a stack of the primary and secondary conductive windings.

[0051] All or part of what has been described above with reference to the planar electrical component also applies to the method, in particular the structure of the primary conductive winding with the electrical track defining two spirals connected in series, and the structure of the secondary conductive winding with a wavy shape.

[0052] According to one embodiment of the method according to the invention:

[0053] As part of the formation of the first layer of the substrate, respective primary conductive windings are etched onto both faces of the first prepreg sheet,

[0054] Then, a third prepreg sheet is placed on one surface of the first prepreg sheet.

[0055] Thereafter, a secondary conductive winding is placed on the free face of the third prepreg sheet.

[0056] According to one embodiment, a primary electrical connector electrically connected to the primary conductive winding is then incorporated into the substrate.

[0057] According to one embodiment, each secondary electrical conductor has, in the continuation of the plane of the second layer, at least an end portion extending beyond the superposition of said substrate to form at least one connection terminal of the secondary circuit.

[0058] According to one embodiment, a ferromagnetic core is added to the substrate in order to magnetically couple the primary conductive winding with the secondary conductive winding and form a power transformer. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] The invention will be better understood by reading the following description, given by way of example only, and with reference to the accompanying drawings, provided by way of non-limiting examples, in which like references are assigned to similar objects and in which:

[0060] Figure 1 An example of an electrical assembly according to the invention is shown in a perspective view;

[0061] Figure 2 depicts a top view of the same example of an electrical assembly according to the present invention;

[0062] Figure 3 depicts a top view of a corresponding power transformer, i.e., a power transformer with a ferromagnetic core added;

[0063] Figure 4 depicts a front view of the same example of a power transformer according to the invention;

[0064] Figure 5 is a diagrammatic representation of a multi-layer architecture of a power transformer according to the present invention;

[0065] Figure 6 An example of a primary conductive winding is depicted;

[0066] Figure 7 An example of a secondary conductive winding is depicted;

[0067] Figure 8 Depicted is a perspective view of a power transformer equipped with a heat sink.

[0068] It should be noted that these drawings illustrate the invention in detail in order to enable the invention to be implemented, and of course, if necessary, said drawings can be used to better define the invention. DETAILED DESCRIPTION

[0069] The invention essentially relates to the production of a planar power transformer which is monolithic except for the addition of a separate ferromagnetic core.

[0070] The invention therefore consists first of all in a substrate which incorporates in its mass a stack of at least a first layer incorporating a primary circuit conductive winding and at least a second layer incorporating a secondary circuit conductive winding. The substrate is obtained from a pre-impregnated material (also called prepreg) impregnated, for example, with an epoxy resin. In particular, the substrate thus forms a printed circuit board, or in other words a PCB.

[0071] The invention also encompasses a corresponding production method.

[0072] refer to Figures 1 to 7 , a power transformer 1 according to one example of the invention therefore firstly comprises a monolithic electrical component 10 , in particular a monolithic electrical component incorporated into a PCB.

[0073] The assembly comprises a substrate 5, in particular obtained from a prepreg. The substrate comprises a second layer into which a secondary conductive winding 22, ie a secondary conductive winding intended to form at least part of a secondary circuit of a power transformer, is incorporated.

[0074] On top of this secondary conductive winding 22, a thickness of a substrate 50, in particular obtained in this case from a prepreg, covers said secondary conductive winding 22 and separates it from a first layer incorporating the primary conductive winding 12, i.e. a primary conductive winding intended to form at least part of the primary circuit of a power transformer.

[0075] On top of this primary conductive winding 12 , a thickness of a substrate 50 obtained, in this case in particular from a prepreg, covers said primary conductive winding 12 .

[0076] The thickness of the substrate 50 obtained from the prepreg provides electrical insulation.

[0077] The primary conductive winding 12 and the secondary conductive winding 22 have in particular a thickness between 0.4 mm and 4 mm, preferably between 0.8 mm and 2 mm.

[0078] According to one embodiment, the primary conductive winding 12 may take the form of, for example Figure 6 The secondary conductive winding 22 may take the form of a planar spiral winding as depicted. Figure 7 The illustrated form of a flat electrical conductor (also called lead frame) has in particular a shape that undulates in the plane of the flat conductor. In particular, the primary conductive winding 12 is formed by an electrical track, in particular with a thickness less than or equal to 0.25 mm, and the secondary conductive winding 22 is formed by a conductive blade with a thickness greater than or equal to 0.4 mm and / or less than or equal to 2 mm.

[0079] At least in the first layer, the primary conductive winding 12 is here an electrical track defining two spirals 30 connected in series. In the example considered, the two spirals 30 have the same shape and are symmetrical to each other about an axis (X) intersecting the substrate 5. Figure 6 As depicted, this axis (X) here intersects the series connection 31 between the two spirals 30 .

[0080] exist Figure 2 and Figure 3 It can also be seen in FIG. 1 that the electrical track defining the primary conductive winding 12 can maintain the same width from one end of one spiral 30 to the other, including at the series connection 31 between two spirals 30 .

[0081] exist Figure 2 , Figure 3 and Figure 6 It can also be seen that each spiral 30 can have a primary connection terminal 32 at its free end. These primary connection terminals 32 here enable the primary conductive winding 12 to be connected to the high-voltage part of the vehicle network. Each primary connection terminal 32 comprises, for example, two terminals for distributing the current associated with the high-voltage part of the vehicle network.

[0082] exist Figure 2 and Figure 3 It can be seen in FIG. 1 that the primary connecting terminals 32 extend here on the same side 33 of the substrate, which side 33 is considered to be rectilinear in this example.

[0083] It can also be seen that from one spiral 30 to the other there is the same number of turns, which here is equal to five.

[0084] In at least the second layer, the secondary conductive winding 22 is, in the example considered, conductive vanes of wavy shape.

[0085] exist Figure 2 , Figure 3 and Figure 5 It can be seen that the first and second layers are stacked along a line perpendicular to Figure 2 and Figure 3 In the plane of the stacking axis, the conductive blades 22 and the electrical tracks defining the two spirals 30 connected in series partially overlap.

[0086] As in Figure 2 , Figure 3 and Figure 7As can be seen in the figure, when viewed along this stacking axis, the conductive blade can have the shape of a W. This blade here defines, for example, two back-and-forth undulations, each of which includes two straight portions 36 connected to each other by a curved portion 37. In this embodiment, the first back-and-forth undulation extends between a first secondary connection terminal 38 connecting the secondary conductive winding to the outside and a second secondary connection terminal 38 connecting this secondary conductive winding to the outside. This connection is, for example, to a low-voltage part of the on-board network. Still in this embodiment, the second back-and-forth undulation extends between the second secondary connection terminal 38 and the third secondary connection terminal 38.

[0087] exist Figures 1 to 3 It can also be seen in FIG. 5 that the secondary connection terminals 38 can protrude from the same side 39 of the substrate 5, which side is rectilinear here. This side 39 is the side opposite to the side 33 relative to which the primary connection terminals 32 protrude.

[0088] exist Figure 2 It can also be noted that each straight portion 36 of the conductive blade overlaps a straight portion of the spiral body 30 along the stacking axis.

[0089] According to one embodiment, such as Figure 5 Depicted schematically, the electrical component 10 of the power transformer 1 has a stacked structure whereby a series of second and first layers, or in other words a series of secondary conductive windings 22 and primary conductive windings 12 , alternate in the mass of the substrate 5 .

[0090] Therefore, reference Figure 5 , the electrical component comprises an alternating body of second layers and first layers incorporated into the mass of a substrate 5. The electrical component 10 and the ferromagnetic core 6 added to the electrical component 10 form an electric transformer 1. Each second layer comprises at least a secondary conductive winding portion 22, and each first layer comprises at least a primary winding portion 12. The primary winding portions 12 together form the primary circuit of the electric transformer 1. The secondary winding portions 22 together form the secondary circuit of the electric transformer 1. The second layers are separated from the first layers by the thickness of the substrate 50. In particular, as previously mentioned, the substrate 5 is obtained from a prepreg. In particular, the primary winding portions 12 are interconnected to each other by superposition and contact. The secondary winding portions 22 are interconnected by superposition and contact outside the volume of the substrate 5.

[0091] By construction, preferably there is no air gap between the first layer and the second layer. Preferably there is no air layer in the mass of the substrate 5.

[0092] For producing the planar electrical component 10 , a production method described below is also proposed.

[0093] First, a first layer comprising a first prepreg sheet is formed, and a primary conductive winding 12 intended to form at least a part of the primary circuit of the power transformer 1 is etched onto one of the faces of the sheet. A secondary conductive winding 22 is arranged on one prepreg face of the first layer. The secondary conductive winding 22 is intended to form at least a part of the secondary circuit of the power transformer 1. A second prepreg sheet is then placed on the secondary conductive winding 22.

[0094] In particular, a primary conductive winding 12 may be etched onto each face of a first prepreg sheet as part of the formation of the first layer of substrate 5. A third prepreg sheet is then placed on one face of the first prepreg sheet. Thereafter, a secondary conductive winding 22 is placed on the free face of the third prepreg sheet.

[0095] For example, the primary circuit has ten turns formed by the primary conductive winding 12 and the secondary circuit has one turn of the secondary conductive winding 122. Of course, the transformation ratio and therefore the number of turns of the primary conductive winding 12 and the secondary conductive winding 22 are suitable for the desired use.

[0096] These operations are repeated as necessary to form a multi-layer substrate base.

[0097] The prepreg layer is pressed together with the primary conductive winding 12 and the secondary conductive winding 22, and the temperature is increased. After being compressed, the electrical component 10 forms a PCB incorporating a stack of the primary conductive winding 12 and the secondary conductive winding 22, which are separated by a thickness 50 obtained from the prepreg and are therefore electrically insulated from each other. At least one free end of the secondary conductive winding 22 protrudes from the substrate 5 to produce an electrical connection terminal 23 for a secondary circuit.

[0098] It should be noted that the material used to manufacture the substrate 5 from a material impregnated with epoxy resin (prepreg) is selected from materials commonly used to form PCB substrates. The selected material has a ductility suitable for the above-mentioned manufacturing method, or in other words, has a viscosity. In particular, the material is able to bind the primary conductive winding 12 and the secondary conductive winding 22 on its face and completely cover them. During the manufacturing stage, the various layers are pressed against each other so that the material of the substrate 5 sneaks in a circuitous manner above and between the conductive windings, especially in fact in the first layer or the second layer, so that there are no air layers or air cavities in the mass of the substrate 5 of the electrical component 10.

[0099] Once a planar electrical component 10 comprising a stack of at least a second layer and a first layer (each having at least a primary conductive winding portion 12 and at least a secondary conductive winding portion 22) has been produced, the ends of the secondary conductive windings forming the secondary electrical connector 23 are brought into contact in order to electrically connect the layers of the stack of secondary conductive windings 22 to one another.

[0100] This then results in a monolithic planar electrical component 10 incorporated into a PCB. To produce a complete power transformer 1, all that is required is to add a ferromagnetic core 6, in particular made of ferrite, to said electrical component 10. The ferromagnetic core 6 may be a one-piece core or may comprise two or more elements.

[0101] The planar electrical component 10 provides the advantage of easier cooling due to its planar structure, i.e. easier cooling of the at least one primary conductive winding 12 and the at least one secondary conductive winding 22. The monolithic electrical component 10 can be easily and effectively pressed tightly against a heat sink 30, in particular a fluid-cooled cooling plate, such as, for example Figure 8 In addition, the planar electrical component 10 also allows one face of the core 8 to be pressed tightly against a heat sink 30 , especially a fluid-cooled cooling plate, to cool the core 8 when it is pressed tightly against the heat sink 30 , especially a fluid-cooled cooling plate.

[0102] Furthermore, in the case of a stacked structure of several second layers and several first layers in which the primary layers are inserted between the secondary layers, better electromagnetic performance is obtained compared to the prior art structure.

Claims

1. A planar electrical component (10) comprising a substrate (5) formed in particular from a prepreg sheet and comprising the following incorporated into the mass of the substrate (5): at least one primary conductive winding (12) which is in the first layer of the substrate (5) and forms at least a part of a primary circuit for the power transformer (1), and on the other hand, at least one secondary conductive winding (22) located in a second layer of the substrate (5) superposed on the first layer and forming at least a part of a secondary circuit for the power transformer (1), The primary conductive winding (12) is formed by an electrical track defining two spirals (30) connected in series, and the secondary conductive winding (22) is formed by conductive blades of wavy shape, In the stacking axis along which the first layer and the second layer are stacked, the conductive blades (22) and the electrical tracks defining the two spirals (30) connected in series at least partially overlap.

2. The planar electrical component (10) of claim 1, the two spirals (30) having the same shape and being symmetrical to each other about an axis (X) intersecting the substrate.

3. The planar electrical component (10) of any one of the preceding claims, the conductive blade (22) having a W-shape when viewed along the stacking axis.

4. The planar electrical component (10) of claim 3, the conductive blade (22) defining two undulations, each undulation comprising two straight portions (36) connected to each other by a curved portion (37).

5. The planar electrical component (10) of claim 4, each straight portion (36) of the conductive vane superimposing along the stacking axis a straight portion of the spiral (30) of the electrical track in the first layer.

6. A planar electrical component (10) as described in claim 4 or 5, wherein the first undulating portion extends between a first secondary connection terminal (38) connecting the secondary conductive winding (22) to the outside and a second secondary connection terminal (38) connecting the secondary conductive winding (22) to the outside, and the second undulating portion extends between the second secondary connection terminal (38) and a third secondary connection terminal (38) connecting the secondary conductive winding (22) to the outside.

7. A planar electrical component (10) as claimed in claims 3 and 6, the primary connection terminals (32) protruding from the same first side (33) of the substrate and the secondary connection terminals (38) protruding from the same second side (39) of the substrate, these first sides (33) and second sides (39) of the substrate being opposite sides.

8. The planar electrical component (10) as claimed in any one of the preceding claims, comprising a plurality of first layers and a plurality of second layers stacked alternately.

9. The planar electrical component (10) as claimed in any one of the preceding claims, wherein: The substrate (5) is obtained from a stack of several pre-impregnated thermosetting material sheets together.

10. The planar electrical component (10) of claim 9, wherein: The first layer of the substrate (5) is obtained from at least a first prepreg sheet, wherein the at least one primary conductive winding (12) is etched onto one of the faces of the first prepreg sheet, and The second layer of the substrate (5) is obtained by adding the at least one secondary conductive winding to the prepreg face of the first layer and by covering the secondary conductive winding with a second prepreg sheet.

11. The planar electrical component (10) of claim 10, wherein: The first layer of the substrate (5) is obtained from the first prepreg sheet, wherein a respective primary conductive winding (12) is etched onto each of the faces of the first prepreg sheet, a third prepreg sheet then covering one face of the first prepreg sheet; The second layer of the substrate (5) is obtained by adding the at least one secondary conductive winding (22) to the free face of the third prepreg sheet and by covering the at least one secondary conductive winding with the second prepreg sheet.

12. The planar electrical component (10) according to any one of the preceding claims, wherein The electric track of the primary conductive winding (12) has a thickness less than or equal to 0.25 mm; and The conductive blades of the secondary conductive winding (22) have a thickness greater than or equal to 0.4 mm and / or less than 2 mm.

13. An electric power transformer (1) comprising an electrical component (10) as claimed in any one of the preceding claims, and a ferromagnetic core (6) added to the substrate (5) in order to magnetically couple the primary conductive winding (12) with the secondary conductive winding (22).

14. A method for manufacturing an electrical component (10) comprising a primary circuit and a secondary circuit, the method comprising the steps of: forming a first layer comprising a first prepreg sheet and etching onto one of the faces of said sheet a primary conductive winding (12), said primary conductive winding being intended to form at least part of a primary circuit of an electric transformer (1), said primary conductive winding (12) being formed by electrical tracks defining two spirals connected in series; providing a monolithic electrical conductor referred to as a secondary conductive winding, said secondary conductive winding (22) being formed of conductive blades having a corrugated shape; placing the secondary conductive winding (22) on the prepreg surface of the first layer, the secondary conductive winding (22) being intended to form at least a part of the secondary circuit of the power transformer (1); placing a second prepreg sheet on top; The entity consisting of the prepreg sheets and the primary conductive winding (12) and the secondary conductive winding (22) is pressed and heated so as to assemble the sheets together along a stacking axis and form an electrical component (10) comprising a stack of primary conductive windings (12) and secondary conductive windings (22), and so that along the stacking axis the conductive blades (22) and the electrical tracks defining the two spirals connected in series at least partially overlap.

15. The method of claim 14, wherein: As part of the formation of the first layer of the substrate (5), respective primary conductive windings (12) are etched into both faces of the first prepreg sheet, Next, a third prepreg sheet is placed on one face of the first prepreg sheet, and thereafter, the secondary conductive winding (22) is placed on the free face of the third prepreg sheet.

16. The method according to claim 14 or 15, wherein: A ferromagnetic core (6) is added to the substrate (5) in order to magnetically couple the primary conductive winding (12) with the secondary conductive winding (22) and form an electrical transformer (1).

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