Printed circuit board for inductive position sensor equipped with device insensitive to metal environment

Abstract

A printed circuit board for an inductive sensor intended to measure the position of a target, the printed circuit board comprising a plurality of metal layers separated pairwise by respective layers of dielectric material, the printed circuit board comprising:-at least two secondary windings and a primary winding surrounding the secondary windings, windings are formed in at least two of the metal layers; and-a shield (23) in the other of said metal layers, configured to make the primary and secondary windings insensitive to the metal environment, and consisting of a metal surface (231). Each of the metal surfaces (231) is inscribed inside a surface defined by an orthogonal projection of the secondary winding in the plane of the shield.

Description

Technical Field

[0001] The field of the invention is that of detecting the position of a moving mechanical structure, in particular a rotor of a rotating machine, by means of a target integrally mounted on said structure.

[0002] The invention relates more particularly, but in a non-limiting manner, to an inductive sensor configured to enable measurement of the position of a rotating component, in particular a rotating shaft or rotor of a rotating electrical machine, in particular a motor vehicle electric motor. Background Art

[0003] In a manner known per se, an inductive position sensor comprises a fixed part, called “transformer”, comprising a fixed primary winding and at least two fixed secondary windings, and a movable part constituted by a metal target rigidly connected to the mechanical part whose position it is desired to control.

[0004] The operating principle of such sensors is based on electromagnetic coupling between a primary winding and a secondary winding and on the variation of this coupling when the position of the target varies relative to the windings.

[0005] In particular, a high-frequency alternating current is caused to flow in the primary winding. This current generates a magnetic field of the same frequency. This magnetic field generates an induced current in the target by the skin effect, which will modify the voltage induced in the secondary winding by the primary winding. Therefore, the coupling between the primary winding and the secondary winding varies depending on the position of the target. Measuring the voltage at the end of the secondary winding thus allows the position of the target to be determined.

[0006] The primary and secondary windings are typically implemented on a printed circuit board and are each comprised of conductive traces delineated on the board.

[0007] An example of such a sensor is described, for example, in patent application US 2014 / 0167788 A1. In this example, the inductive sensor is configured to measure the angular position by means of a primary winding and a secondary winding arranged in the shape of a disk or a ring.

[0008] exist Figures 1A to 1C 1 shows a printed circuit board 10 of an inductive sensor for measuring an angular position according to the prior art. Here, the printed circuit board 10 comprises two metal layers 101, 102 separated by a dielectric material layer 111 (see Figure 1C ).

[0009] The winding of the inductive sensor comprises a primary winding 11 and two secondary windings 12 a and 12 b . Figure 1A A first secondary winding 12a is shown. Figure 1BA primary winding 11 and a second secondary winding 12b are shown. Each of the secondary windings 12a and 12b consists of a plurality of turns extending one after the other in a ring shape. Here, each turn extends partly in the metal layer 101 of the printed circuit board 10 and partly in the metal layer 102 (wherein the through hole passes through the dielectric material layer 111).

[0010] The primary winding 11 is circular in shape and has ports for inputting and outputting current. It surrounds the secondary windings 12a and 12b and extends in at least one of the first metal layer 101 and the second metal layer 102 in the form of one or more superimposed and / or concentric circles.

[0011] The operating principle of such sensors is therefore based on the skin effect, which is the electromagnetic coupling between a magnetic field (here generated by the primary winding) and an electrically conductive component (here, a metallic target) located in this magnetic field.

[0012] Electromagnetic coupling due to the skin effect can occur as expected in the case of metallic targets, but also in the case of any other conductive components that would be located in close proximity to the secondary winding. If this occurs, the electromagnetic coupling with these conductive components generates induced currents that modify the voltage induced in the secondary winding. Therefore, the voltage measured at the end of the secondary winding is not only affected by the position of the target, but also by these conductive components.

[0013] In the prior art, it is known to associate an inductive sensor with a recommendation with regard to the environment to avoid the presence of metallic parts other than the target in the vicinity of the secondary winding.

[0014] However, it turns out that constraints in terms of geometry and volume prevent compliance with these constraints.The secondary winding of the inductive sensor may then be located in the vicinity of a conductive metal part other than the target.

[0015] Worse still, these constraints may result in the secondary winding of the inductive sensor being placed near metal parts that are different from the target and lack rotational symmetry. In other words, the distance between the metal parts different from the target and the secondary winding varies in space. These metal parts then result in strong nonlinearities in the response of the inductive sensor. The position of the target is then measured with reduced accuracy.

[0016] The object of the present invention is to propose a solution for overcoming this drawback. Summary of the invention

[0017] The object is achieved with a printed circuit board for an inductive sensor intended to measure the position of an object, the printed circuit board comprising a plurality of metal layers separated two by two by respective layers of dielectric material, the printed circuit board comprising:

[0018] at least two secondary windings, each formed by staggered turns, the secondary windings extending together in at least two layers, referred to as winding layers, of said plurality of metal layers;

[0019] A primary winding which surrounds the secondary winding and extends over at least one of the winding layers.

[0020] According to the present invention:

[0021] - the printed circuit board further comprises: a shielding member for making the primary winding and the secondary winding insensitive to a metallic environment;

[0022] - the shielding is constituted by a metal surface situated in a layer called the shielding layer belonging to said plurality of metal layers, the winding layers all extending on the same side of the shielding layer; and

[0023] - Each of said metal surfaces is inscribed in the surface defined by the contour of the orthogonal projection of the secondary winding in the plane of the masking layer.

[0024] The shielding according to the invention is therefore made of metal. It is therefore able to establish an electromagnetic coupling (via the skin effect) with a magnetic field source, in particular the primary winding and the secondary winding of a printed circuit board.

[0025] The shield is located in the shielding layer, wherein the winding layers all extend on the same side of the shielding layer.

[0026] In use, the shield extends between the secondary (and primary) winding and possible metal parts other than the target. In practice, these metal parts are necessarily on the side opposite to the target, since the side receiving the target is left free for any other metal parts for obvious volume reasons.

[0027] Therefore, the electromagnetic coupling that may exist between the secondary winding and these metal parts is hindered by the presence of the shield between the two. Instead, the electromagnetic coupling is generated between the secondary winding and the shield. Therefore, the shield according to the present invention allows the electromagnetic coupling with the shield to be applied to the secondary winding, which blocks the electromagnetic coupling with other metal parts other than the target.

[0028] The shield according to the invention is integrated with the winding on the same printed circuit board. All points on the shield are therefore located at the same distance from the secondary winding. In this way, the parasitic voltage generated at the end of the secondary winding due to the electromagnetic coupling with the shield takes a fixed value that does not vary according to time. The variation of the voltage at the end of the secondary winding is then only a function of the movement of the target.

[0029] Integrating the shield in one of the layers of the multilayer printed circuit board also allows avoiding the problems of volume and mechanical deformation that would be present if the shield were formed from a solid component that is different from the printed circuit board that receives the winding.

[0030] Due to its arrangement on the same printed circuit board as the winding, the shield is in close proximity to the secondary winding. It is therefore possible for very high induced currents to occur there, resulting in large energy losses.

[0031] In order to limit these induced currents, the shield according to the invention is composed of a plurality of metal surfaces which are all different and spaced apart from each other. Dividing the shield into a plurality of small surfaces hinders the generation of excessive induced currents in the shield.

[0032] The invention thus allows avoiding the generation of parasitic measurement signals related to the presence of metallic parts other than the target in the vicinity of the secondary winding.The invention thus provides an improvement in the measurement accuracy of the position of the target, which does not represent a large increase in electrical energy consumption.

[0033] Finally, according to the invention, the metal surfaces forming the shield are each inscribed inside the surface defined by the orthogonal projection of the secondary winding in the plane of the shield. Thus, for optimal accuracy of the position measurement by means of measuring the voltage at the end of the secondary winding, any overlap between the metal surface forming the shield and the secondary winding is avoided.

[0034] This arrangement also offers other advantages, in particular:

[0035] - a uniform distribution of the metal surface forming the shield, obtained automatically by construction; and

[0036] - Additional reduction of the inductive coupling between the primary winding and the shield, the metal surface forming the shield being present only along a reduced portion of the contour of the primary winding.

[0037] Preferably, the shielding according to the invention extends opposite the secondary winding over the entire extent of the secondary winding along the displacement path of the target relative to said secondary winding. This path may be circular in shape, as in the examples represented in the figures, or in the shape of straight line segments, or in the shape of curved line segments, or in any other shape.

[0038] Preferably, the shielding according to the invention is located in one of the two outermost metal layers of the printed circuit board.

[0039] Advantageously, the gap between two adjacent metal surfaces among the metal surfaces forming the shield is less than or equal to D max , where D max Equal to 2mm.

[0040] Preferably, the metal surfaces forming the shield are distributed in a regular pattern.

[0041] Advantageously, the metal surfaces forming the shield all have the same area.

[0042] The metal surfaces forming the shield may all have the same shape.

[0043] The metal surfaces forming the shield may each be located between orthogonal projections of different parts of turns belonging to different secondary windings.

[0044] Preferably, the printed circuit board according to the invention is intended to realize angular position measurement, and both the secondary winding and the primary winding extend in a ring shape.

[0045] Advantageously, the metal surfaces forming the shield each have the shape of a portion of an annulus.

[0046] Advantageously, the printed circuit board according to the invention comprises four metal layers, having:

[0047] - a first metal layer and a second metal layer, which together form a winding layer; and

[0048] - A fourth metal layer, which forms a masking layer, is separated from the winding layer by the third metal layer.

[0049] The shield may be electrically connected to a voltage source of constant and non-zero potential. As a variant, the shield may be electrically connected to ground.

[0050] Advantageously, the printed circuit board according to the invention also comprises electronic components configured to supply the primary winding and / or to measure voltage values ​​at the ends of the secondary winding, said electronic components being laterally offset relative to the primary winding and the secondary winding.

[0051] Preferably, the metal surfaces forming the shield are spaced two by two by a distance greater than or equal to 800 μm.

[0052] The invention also covers an inductive sensor intended to measure the position of an object, comprising a printed circuit board according to the invention and at least one electronic component configured to measure the voltage value at the end of the secondary winding and to derive therefrom a measure of the position.

[0053] The invention also covers an assembly comprising an inductive sensor according to the invention and a metal target, the inductive sensor being configured to measure the position of said target. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Other features and advantages of the present invention will become more apparent upon reading the following description. The description is purely illustrative and should be read with reference to the accompanying drawings, in which:

[0055] [ Figure 1A ] Figure 1A illustrates a first secondary winding of a printed circuit board according to the prior art for an inductive sensor;

[0056] [ Figure 1B ] Figure 1B Pictured Figure 1A A primary winding and a second secondary winding of a printed circuit board;

[0057] [ Figure 1C ] Figure 1C The diagram shows a cross-sectional view in a plane orthogonal to the plane of the winding. Figure 1A printed circuit boards;

[0058] [ Figure 2A ] Figure 2A The diagram illustrates a first secondary winding of a printed circuit board according to the present invention;

[0059] [ Figure 2B ] Figure 2B Pictured Figure 2A A primary winding and a second secondary winding of a printed circuit board;

[0060] [ Figure 2C ] Figure 2C Pictured Figure 2A Shielding of printed circuit boards;

[0061] [ Figure 2D ] Figure 2D The diagram shows a cross-sectional view in a plane orthogonal to the plane of the winding. Figure 2A printed circuit boards;

[0062] [ Figure 2E ] Figure 2E Picture shows Figure 2A The shield of the printed circuit board and the orthogonal projection of the secondary winding in the same plane;

[0063] [ Figure 3 ] Figure 3 Illustrated is a side view and used with a target and in an environment including metal parts Figure 2A printed circuit boards;

[0064] [ Figure 4 ] Figure 4 A shielding member of a first variant of a printed circuit board according to the present invention is illustrated;

[0065] [ Figure 5 ] Figure 5 A shielding member of a second variant of a printed circuit board according to the present invention is illustrated;

[0066] [ Figure 6 ] Figure 6 A third variation of the printed circuit board according to the present invention is illustrated; and

[0067] [ Figure 7 ] Figure 7 An inductive sensor according to the invention is illustrated. DETAILED DESCRIPTION

[0068] Refer to the following FIG. 2A to FIG. 2E , a first embodiment of a printed circuit board 20 according to the invention is described. Here, but in a non-limiting manner, the printed circuit board is intended to constitute part of an angular position sensor.

[0069] exist Figure 2D , a printed circuit board 20 is shown according to a cross-sectional view in a plane orthogonal to the windings. The printed circuit board comprises a first metal layer 201, a second metal layer 202, a third metal layer 203 and a fourth metal layer 204, which are separated by respective dielectric material layers 211, 212, 213.

[0070] The windings which together form the sensitive part of the inductive sensor here comprise a primary winding 21 and two secondary windings 22a and 22b. To facilitate understanding, Figure 2A A first secondary winding 22a is shown, and Figure 2B A primary winding 21 and a second secondary winding 22b are shown.

[0071] As in the related art described in the introduction, each of the secondary windings 22a and 22b is composed of a plurality of turns extending one after another in a toroidal shape.

[0072] Here and in an advantageous manner, each turn extends partially in the first metal layer 201 and partially in the second metal layer 202 of the printed circuit board 20 (with the vias passing at least through the dielectric material layer 211). The first metal layer 201 and the second metal layer 202 may be referred to as "winding layers".

[0073] The primary winding 21 is circular in shape and has ports for inputting and outputting current. It surrounds the secondary windings 22a and 22b. It extends in at least one of the first metal layer 101 and the second metal layer 102 in the form of one or more superimposed and / or concentric circles.

[0074] The printed circuit board also includes a shielding member 23, which is composed of a plurality of different metal surfaces 231 (see Figure 2C), and is located in a metal layer of the printed circuit board 20 that is different from the metal layer that receives the winding. Here, the shielding member 23 is located in the metal layer farthest from the winding (especially the secondary winding), that is, the fourth metal layer 204. The fourth metal layer 204 can be called a "shielding layer".

[0075] As explained in the disclosure of the invention, the shield 23 allows making the secondary winding insensitive to metallic environments other than the target. This involves in particular applying an electromagnetic coupling between the secondary winding and the known metallic element formed by the shield, which replaces the electromagnetic coupling between the secondary winding and the uncontrolled metallic environment.

[0076] In use, the shield 23 extends opposite the secondary windings 22a, 22b over the entire extent of the secondary winding along a displacement path 24 of the target relative to the secondary winding. Here, this path 24 (dashed line) is circular in shape and the shield 23 therefore extends in a generally annular shape.

[0077] Here, but in a non-limiting manner, the metal surfaces 231 forming the shield 23 all have the same area. Furthermore, these metal surfaces all have the same shape here. Here, but in a non-limiting manner, each of the metal surfaces 231 forming the shield 23 has a substantially square shape.

[0078] Furthermore, the metal surfaces 231 forming the shield 23 are here distributed in a regular pattern along the displacement path 24 of the target. Here, but in a non-limiting manner, the metal surfaces 231 are angularly regularly distributed with a constant angular gap between two adjacent metal surfaces 231.

[0079] The conditions advantageously verified by the gap between two adjacent metal surfaces 231 are detailed below.

[0080] at last, Figure 2E The shield 23 and the orthogonal projection 25 of the two secondary windings into the plane of the shield 23 are shown.

[0081] The orthogonal projections 25 define surfaces 251 distributed one after another along the displacement path 24 of the object. The surfaces 251 are closed surfaces all having substantially the same shape.

[0082] In the case where it is possible to define a plurality of series of similarly shaped surfaces distributed along the path 24 , the series is chosen whose surface 251 has the largest area.

[0083] According to the invention, each of the metal surfaces 231 is inscribed in a corresponding one of the surfaces 251. Preferably, each of the surfaces 251 receives a corresponding one of the metal surfaces 251.

[0084] This arrangement automatically ensures a regular distribution of the metal surfaces 231 .

[0085] This arrangement also allows the metal surface 231 not to overlap with the traces of the secondary windings 22a, 22b, thus disturbing the electromagnetic flux received by the secondary windings.Therefore, optimal accuracy of the position measurement by means of measuring the voltage at the ends of the secondary windings is guaranteed.

[0086] This arrangement also allows a large part of the perimeter of the primary winding to lie in the free space between two of the metal surfaces forming the shield, thereby limiting the current induced in the shield by the primary winding.

[0087] This arrangement also allows the metal surface 231 to be constructed to bypass metal vias that pass through the entire thickness of the printed circuit board and connect different parts of the turns of the primary winding (respectively, the secondary winding) together.

[0088] Note that according to the present invention, the distribution of the metal surface 231 is only a function of the arrangement of the secondary windings and is independent of the shape of the target.

[0089] Advantageously, the metal surfaces 231 are each located between orthogonal projections of the parts of the turns belonging respectively to the first secondary winding 22a and the second secondary winding 22b. This is related to the staggered arrangement of the secondary windings 22a and 22b.

[0090] In a non-limiting example, the metal surface 231 is a surface made of copper, for example, with a thickness between 34 μm and 40 μm.

[0091] Next refer to Figure 3 And the printed circuit board 20 is illustrated in a schematic manner for use with the target 330. The axis A1 represents the rotation axis of the target 330 in a schematic manner.

[0092] The first metal layer 201 and the second metal layer 202 receiving the winding are located on the side of the target 330. The fourth metal layer 204 receiving the shield is located on the side opposite to the target. The shield is thus positioned between the windings, in particular the secondary winding, and adjacent metal parts 340 which, without the shield, could interfere with the signal measured at the end of the secondary winding.

[0093] Unlike the shielding element according to the invention, Figure 3In particular, it is shown that the adjacent metal component 340 has a spatially varying distance from the secondary winding, which manifests itself as a parasitic signal at the secondary winding that varies as a function of time.

[0094] Next refer to Figure 4 A shielding member 43 of a first variation of the printed circuit board according to the present invention will be described.

[0095] In this variant, the metal surfaces 431 forming the shield 43 each have the shape of a portion of an annulus. In particular, each metal surface has the shape of an annular arc, or in other words, the shape of a portion of an annulus laterally delimited by two radii of a disk arranged concentrically in an annulus.

[0096] Figure 4 A gap D between two adjacent metal surfaces 341 is also illustrated.

[0097] According to the invention, the gap D is between:

[0098] -Upper limit value D max , exceeding this value D max , there may be electromagnetic coupling between the secondary winding and adjacent metal parts other than the target, through the free space between the metal surfaces 341; and

[0099] -Lower limit D min , in particular defined by the technical constraints of manufacturing.

[0100] Upper limit D max In particular, it is a function of the expected distance between the secondary winding and said adjacent metal part other than the target. Under these current use conditions (i.e. where the distance between the secondary winding and the metal part to be shielded is less than 10 mm), for example with D max＝ 2mm.

[0101] Lower limit D min For example, 125 μm. It is advantageously higher, which allows to relax the manufacturing constraints without affecting the technical effect sought. For example, with D min =800μm, even D min =1mm.

[0102] Next refer to Figure 5 A shielding member 53 of a second variation of the printed circuit board according to the present invention will be described.

[0103] In this variant, the metal surfaces 531 are all connected to the same potential U. To this end, the metal surfaces 531 are advantageously electrically connected to one another by means of an electrical connection track 57. Here, but in a non-limiting manner, the electrical connection track 57 has a circular shape passing through each of the metal surfaces 531. The circular shape is advantageously a circle of minimum diameter that allows passing through each of the metal surfaces 531 (to maximize the distance to the primary winding).

[0104] The potential U may be zero potential, forming the ground of the circuit connected to the (primary and secondary) windings. In this case, the shielding also has a protection function against electromagnetic intrusion (or CEM, for “Compatibilité Electro-Magnétique”, electromagnetic compatibility).

[0105] As a variant, the potential U is a non-zero potential different from the ground of the circuit connected to the winding.

[0106] Figure 6 A variant of a printed circuit board 60 according to the invention is illustrated in a schematic manner, which differs from the example described above in that it also comprises electronic components 68, which are configured to supply power to the primary winding 61 and / or measure voltage values ​​at the ends of the secondary windings 62a, 62b.

[0107] The electronic component 68 is arranged laterally offset relative to the primary winding 61 and the secondary windings 62a, 62b. In other words, the electronic component 68 is not superimposed on the windings. In the top view, the electronic component 68 is then located on the winding side, outside the disk defined by the primary winding 61.

[0108] at last, Figure 7 An inductive sensor 700 according to the invention is illustrated, comprising: a printed circuit board 70 according to the invention; and at least one electronic component 79 configured to measure the voltage value at the end of the secondary winding and to derive therefrom a measurement of the position of the target.

[0109] Here, at least one electronic component 79 comprises:

[0110] a first electronic component 78 configured to supply power to the primary winding 61 and / or to measure the voltage value at the ends of the secondary windings 62a, 62b; and

[0111] A second electronic component 78 ′ configured to receive as input the voltage value at the ends of the secondary windings 62 a , 62 b and to derive therefrom a position value of the target.

[0112] The invention is not limited to the examples described above and may cover many other variants, among which for example:

[0113] -Implemented in Figure 2D A shield in the third metal layer of a printed circuit board having four metal layers as shown in FIG.

[0114] - a different number of metal layers in the printed circuit board, however this number is greater than or equal to 3;

[0115] - a number of secondary coils greater than 2 (e.g. equal to 3);

[0116] - Arrangement of the windings not along a circular trajectory but along a straight or curved trajectory or a trajectory of any other shape;

[0117] - an arrangement of windings in the shape of a disk rather than a ring, associated with an inductive sensor configured to be mounted at the end of a rotating shaft;

[0118] - a shield which does not cover the secondary winding over its entire extent along the trajectory of the target, so that the technical effect is obtained over only a portion of the trajectory of the target;

[0119] - a metal surface forming a shield, having any shape, for example any shape allowing bypassing of metal vias passing through the printed circuit board over the entire thickness of the printed circuit board;

[0120] - a plurality of metal surfaces forming the shield, being in the same plane defined by the orthogonal projections of the secondary winding in the plane of the shield; and so on.

[0121] The invention ultimately allows the realization of inductive sensors of reduced size and facilitates their integration in highly constrained environments, in particular in motors of electric vehicles or in control electronics of electric motors.

[0122] The present invention has no negative impact on CEM.

[0123] In a slightly different variant of the invention, the shielding may extend in the form of different metal surfaces which are distributed in a regular manner and which extend not only opposite the secondary winding but also beyond relative to an orthogonal projection of the secondary winding.

[0124] In other slightly different variants of the invention, the shield may be formed by a regularly distributed metal surface according to a pattern independent of the shape of the turns of the secondary winding. In particular, it is possible to have a metal surface covering the entirety of a plurality of adjacent turns of the secondary winding. As a supplement or variant, the metal surface may be distributed as a series of concentric circular arcs superimposed one on another along an axis orthogonal to the trajectory of the target.

Claims

1. A printed circuit board (20; 60) for an inductive sensor intended to measure the position of a target (330), the printed circuit board comprising a plurality of metal layers (201, 202, 203, 204), the plurality of metal layers (201, 202, 203, 204) being separated in pairs by respective dielectric material layers (211, 212, 213), the printed circuit board comprising: - at least two secondary windings (22a, 22b; 62a, 62b), each formed by staggered turns, the secondary windings extending together in at least two layers, referred to as winding layers (201, 202), of the plurality of metal layers; - a primary winding (21; 61) which surrounds the secondary winding and extends over at least one of the winding layers (201, 202); and - a shield (23; 43; 53) for making the primary winding and the secondary winding insensitive to a metallic environment (340); Features: - the shield (23; 43; 53) consists of a metal surface (231; 431; 531) situated in a layer called masking layer (204) belonging to said plurality of metal layers. 531), the winding layers (201, 202) both extend on the same side of the shielding layer (204); - each of the metal surfaces (231; 431; 531) is inscribed in a surface defined by the contours of the orthogonal projections of the secondary windings (22a, 22b; 62a, 62b) in the plane of the masking layer (204); and The metal surfaces (231; 431; 531) forming the shield are each situated between orthogonal projections of different parts of turns belonging to different secondary windings (22a, 22b; 62a, 62b).

2. The printed circuit board (20; 60) according to claim 1, characterized in that The gap (D) between two adjacent metal surfaces of the metal surfaces forming the shield is less than or equal to D max , where D max Equal to 2mm.

3. The printed circuit board (20; 60) according to claim 1 or 2, characterized in that The metal surfaces (231; 431; 531) forming the shield are distributed in a regular pattern.

4. The printed circuit board (20; 60) according to any one of claims 1 to 3, characterized in that The metal surfaces (231; 431; 531) forming the shielding element all have the same area.

5. The printed circuit board (20; 60) according to claim 4, characterized in that The metal surfaces (231; 431; 531) forming the shielding members all have the same shape.

6. The printed circuit board (20; 60) according to any one of claims 1 to 5, characterized in that It is intended to achieve angular position measurement, and both the secondary winding (22a, 22b; 62a, 62b) and the primary winding (21; 61) extend in a ring shape.

7. The printed circuit board (20; 60) according to claim 6, characterized in that The metal surfaces (231; 431; 531) forming the shielding elements each have the shape of a portion of an annular ring.

8. The printed circuit board (20; 60) according to any one of claims 1 to 7, characterized in that It includes four metal layers (201, 202, 203, 204) having: - a first metal layer (201) and a second metal layer (202), which together form a winding layer; as well as - a fourth metal layer (204), which forms a masking layer, separated from the winding layer by the third metal layer (203).

9. The printed circuit board according to any one of claims 1 to 8, characterized in that: The shield (53) is electrically connected to a voltage source (U) of constant and non-zero potential.

10. The printed circuit board according to any one of claims 1 to 8, characterized in that The shield (53) is electrically connected to ground.

11. The printed circuit board (60) according to any one of claims 1 to 10, characterized in that: It also includes an electronic component (68) configured to supply power to the primary winding (61) and / or measure the voltage value at the end of the secondary winding (62a, 62b), and the electronic component (68) is offset in the transverse direction relative to the primary winding (61) and the secondary winding (62a, 62b).

12. The printed circuit board (20; 60) according to any one of claims 1 to 11, characterized in that The metal surfaces (231; 431; 531) forming the shield are spaced apart from each other by a distance greater than or equal to 800 μm.

13. An inductive sensor (700) for measuring the position of an object, comprising: A printed circuit board as claimed in any one of claims 1 to 12; and at least one electronic component (79) configured to measure the voltage value at the end of the secondary winding and to derive therefrom a measure of the position.

14. An assembly comprising the inductive sensor (700) of claim 13 and a metal target (330), the inductive sensor being configured to measure a position of the target.

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