Printed circuit board with NFC antenna

Abstract

The present invention relates to a printed circuit board for mechanically supporting a plurality of electrical and / or electronic components for an electronic smoking article, electrically connected via conductive tracks. The printed circuit board comprises at least one flexible part and at least one rigid part, the flexible part and the rigid part comprising a common flexible layer stack comprising at least one structured metal layer forming the conductive tracks and / or the electrical components. The rigid part further comprises at least one rigid layer stack comprising at least one structured metal layer forming the conductive tracks and / or the electrical components, the rigid layer stack being disposed on at least one surface of the common flexible layer stack. The printed circuit board is characterized in that at least a portion of the structured metal layer of the common flexible layer stack in the flexible part is structured as an electromagnetic coil forming an NFC antenna, and at least a portion of the structured metal layer of each of the common flexible layer stack and the rigid layer is structured to work together as an electromagnetic induction coil suitable for wireless charging.

Description

[Technical Field]

[0001] The present invention relates to a printed circuit board that mechanically supports a plurality of electrical and / or electronic components and that is insertable into an electronic smoking system, the printed circuit board comprising at least one flexible portion that includes an NFC antenna and at least one rigid portion, both portions being attached to a common flexible layer stack. [Background technology]

[0002] Electronic smoking devices have become increasingly popular, particularly for the consumption of nicotine, tobacco, liquid flavorings, and other smokable plant-based materials. These devices often have anatomically shaped housings that provide comfort, particularly in the user's hand. As such, electric smoking devices are handheld and portable. To achieve wireless functionality, a tuned antenna is typically connected to a flexi-rigid PCB via a connector and / or flying leads. For example, U.S. Patent Application Publication No. 2014 / 224267 describes an inductive charging system for wirelessly charging an electric cigarette. The described electric cigarette thus includes a flexible laminate printed circuit board (PCB) on which a receiving coil is printed. Another example of a wireless module for a handheld electronic device with a wireless charging module is found in U.S. Patent Application Publication No. 2015 / 116156. However, typical PCBs are not flexible enough for use in particularly thin and delicate embodiments of handheld electric cigarettes. Furthermore, such implementation of a wireless charging module increases manufacturing costs and reduces design variability due to additional assembly steps.

[0003] It would be desirable to provide a flexible printed circuit board for installation within an electronic smoking system in which the antenna is incorporated as part of a single flexible printed circuit board. In particular, it would be desirable to reduce the manufacturing costs and assembly steps of such flexible printed circuit boards. Summary of the Invention

[0004] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a flexible printed circuit board in which all radio antennas are integrated onto the flexible printed circuit board.

[0005] The above-mentioned problems are solved by a printed circuit board that mechanically supports multiple electrical and / or electronic components for an electronic smoking article, electrically connected via conductive tracks. The printed circuit board includes at least one flexible portion and at least one rigid portion, where the flexible portion and the rigid portion include a common flexible layer stack including at least one structured metal layer forming the conductive tracks and / or electrical components. The rigid portion further includes at least one rigid layer stack including at least one structured metal layer forming the conductive tracks and / or electrical components, where the rigid layer stack is disposed on at least one surface of the common flexible layer stack. According to the present invention, at least a portion of the structured metal layer of the common flexible layer stack in the flexible portion is structured as an electromagnetic coil forming an NFC antenna, and at least a portion of the structured metal layers of the common flexible layer stack and each of the rigid layers are structured to operate together as an electromagnetic induction coil suitable for wireless charging.

[0006] Preferably, the rigidity of the printed circuit board can be defined by the number of layers. It is possible to provide a two-layer section on each surface of the printed circuit board, which is preferably flexible. It is also conceivable to provide a four-layer section on each surface of the printed circuit board, which is particularly less flexible than the two-layer section. The term flexible in this context means, in particular, bendable. A flexible printed circuit board is particularly advantageous when it is mounted in the housing of an electric smoking device. Thus, when the housing has a rectangular shape, particularly large space is available at the edges of the housing. Furthermore, when the housing has a rounded shape or a shape tailored to the user, it is very advantageous for the flexible section of the printed circuit board to be flexible.

[0007] Attaching the NFC antenna to the flexible portion of the common flexible layer stack is particularly advantageous when the manufacturing process of the entire printed circuit board is automated. The coil can be prepared by stacking multiple layers of the flexible portion of the printed circuit board while leaving them empty. This eliminates the need to add a separate electromagnetic coil to the printed circuit board, particularly reducing manufacturing costs. The flexible portion of the common flexible layer stack preferably includes at least two layers. The first flexible layer, preferably an upper paste and / or a lower paste, is attached to the second flexible layer. The second layer is preferably a dielectric layer, more preferably a second and / or a fourth dielectric layer, which are attached to the common flexible layer stack. The common flexible layer stack preferably includes a flexible core containing polyimide. The upper flex and the lower flex can be designed as antenna artwork. For example, a coil pattern can be generated on the flexible portion using a design tool before or during printing of the printed circuit board. It is envisioned that during the design, the physical values ​​of the coil (e.g., coil length and width), track width, inter-track gap size, track thickness, and number of windings may be varied. It is envisioned that the coil so formed may be further coated with at least one dielectric layer and / or top paste on each surface of the printed circuit board. The dielectric layer is preferably prepreg 1080.

[0008] The coil pattern generated by the design tool may not automatically behave as desired. To provide a promising pattern, it is envisioned to connect the pattern to a Vector Network Analyser tool to measure the actual values ​​(impedance, etc.) of the antenna. Preferably, the values ​​of the antenna pattern are calculated for the desired frequency. This calculation allows for consistency and homogeneity in the coil performance, reducing manufacturing costs.

[0009] In a preferred embodiment, the NFC antenna has a square shape. The antenna preferably has a lateral length and width in the range of 30 to 90 mm, preferably 65 mm. The antenna preferably has a track width in the range of 300 to 600 μm, preferably 500 μm. The NFC antenna may further have at least one gap between the tracks in the range of 300 to 600 μm, preferably 500 μm. It is recalled that the track thickness is 35 μm and the number of windings is two. Such an NFC antenna is preferably suitable for high-frequency transmission, preferably in the range of 10 to 90 MHz, more preferably 13.56 MHz. The NFC antenna preferably enables a data transfer rate of up to 424 kbps.

[0010] It is also advantageous to mount at least a portion of the electromagnetic induction coil on a rigid layer, making it suitable for wireless charging. The electromagnetic induction coil is preferably capable of transmitting low frequencies in the range of 100 to 300 kHz for wireless charging. For this reason, it is envisioned that the electromagnetic induction coil, unlike an NFC antenna, requires a thicker and longer copper gauge. To achieve this, all layers of the flexible printed circuit board can be used and copper stitched together to obtain a 3D conductor similar to a trace. To achieve transmission and reception at frequencies up to 100 kHz, the rigid portion of the printed circuit board may include at least six layers on each surface. The rigid portion preferably includes upper and lower solder layers, upper and lower overlays, upper and lower rigid layers, first and fifth dielectric layers, a ground (GND) layer, a power (Vsupp) layer, and a second and fourth dielectric layer. Both the rigid and flexible portions of the printed circuit board preferably include upper and lower pastes.

[0011] According to another embodiment, the printed circuit board is characterized in that the common flexible layer stack and the rigid layers are interconnected by vias. In particular, interconnections by vias are cheap and easy to implement. Due to the fact that the flexible printed circuit board carries at least a few electrical components, there is preferably sufficient space for stitching with vias in the rigid parts.

[0012] According to another embodiment, the printed circuit board further includes a wireless protocol antenna suitable for transmitting and receiving electromagnetic signals including frequencies up to 2.4 GHz. The wireless protocol antenna preferably transmits and receives Bluetooth, Wi-Fi, Zigbee, Thread, or other wireless protocols. The wireless protocol antenna is preferably applied to at least one surface of the rigid portion of the printed circuit board. The wireless protocol antenna is preferably a UHF chip antenna.

[0013] According to another embodiment, the printed circuit board is foldable into a rectangular shape having two short sides and two long sides, with the NFC antenna bordering one of the short sides. The most commonly used shape of an electronic smoking article preferably resembles a rectangular pen. It is recalled that in order to achieve the mounting of the printed circuit board including the component group in the housing, the printed circuit board can be foldable into a rectangular shape having two short sides and two long sides. Therefore, it is advantageous to mount the NFC antenna on the short side of the rectangular pen. In this case, the NFC antenna is preferably close to the replaceable mouthpiece. The replaceable mouthpiece can communicate with the electronic smoking article via the NFC antenna. The mouthpiece preferably includes a replaceable cartridge containing smokable liquid.

[0014] According to another embodiment, the printed circuit board is foldable into a rectangular shape having two short sides and two long sides, with the induction coil located in the center between the short sides. It is particularly advantageous to prepare or configure the induction coil for wireless charging in the center of the rigid part and / or between the two short sides. In this case, the assembled electronic smoking article can be charged in the center of the charging station. The user preferably does not need to pay attention to the positioning of the electric smoking article (e.g., whether the induction coil contacts a specific location on the charging station) and will still intuitively center the device. Additionally or alternatively, it is conceivable to configure or configure the NFC antenna to match one of the short sides.

[0015] According to another embodiment, the printed circuit board is characterized in that the vias are stitching vias. The stitching vias preferably stitch at least two metal layers. The stitching vias are advantageous in terms of shortening the signal return path. It is recalled that the stitching vias distribute heat on the printed circuit board, particularly in the area containing the induction coil. In this case, the printed circuit board has a higher horizontal thermal conductivity, and heat is transferred at least laterally outward. This allows the common flexible layer stack to be cooler than the traces, and the stitching vias through the rigid sections provide a higher cross-plane thermal conductivity, thereby transporting heat to the common flexible layer stack for dissipation. It is also recalled that the effect of fencing electromagnetic waves emitted from the tracks at high frequencies is utilized. The vias are preferably spaced apart from one another by at least 1 / 10 of the wavelength of the frequency of interest. In this case, this spacing is small enough to fence off impinging waves.

[0016] According to another embodiment, the printed circuit board is characterized in that the rigid portion further includes a second rigid layer stack including at least one structured metal layer forming conductive tracks and / or electrical components, and the common flexible layer stack and at least a portion of the structured metal layer of each of the two rigid layers are interconnected by vias and structured to operate together as an induction coil. It is recalled that the conductive tracks electrically connect the electrical components to each other and / or to at least one antenna. Preferably, the induction coil is at least partially disposed on the flexible layer stack. The induction coil disposed on the at least two rigid layer stacks and the flexible layer stack can be bent to an angle ranging from 25 to 160 degrees. An electric smoking article having such a prepared printed circuit board may include a wireless charging induction coil on at least one edge.

[0017] According to another embodiment, the printed circuit board is characterized by a common flexible layer stack and two rigid layer stacks each including two structured metal layers, all interconnected by vias and structured to operate together as an induction coil. Such induction coils are preferably foldable at angles ranging from 30 to 130 degrees. When using multiple different frequencies for communication with other devices and / or wireless power transmission, it may be desirable to mount at least three, more preferably four, antennas. The number of induction coils used, structured into the at least two rigid layer stacks, varies depending on the required number of communication frequencies and / or wireless power transmission frequencies.

[0018] According to another embodiment, the printed circuit board is characterized in that the surface area of ​​the induction coil is 400 to 500 mm 2 and preferably 430 to 470 mm 2 and most preferably 450 mm 2The induction coil is preferably designed to have a width of 15 mm and a length of 30 mm. The induction coil may also be designed to have a width in the range of 5 to 30 mm and a length in the range of 10 to 47 mm.

[0019] According to another embodiment, the printed circuit board is characterized in that the total cross-sectional area of ​​the effective wiring of the induction coil formed by the interconnected structured metal layers is 0.05 to 0.3 mm 2 and preferably 0.01 to 0.25 mm 2 and most preferably 0.2 mm 2 The induction coil has a diameter of 0.5 mm and a cross-sectional area of ​​0.2 mm. 2 For such a coil, the tracks should be 1 mm wide on all layers (preferably 6 layers) and 0.1 mm high.

[0020] According to another embodiment, the printed circuit board is characterized in that the metal layer is a copper layer, although other conductive metals can also be used.

[0021] According to another embodiment, the printed circuit board is characterized in that the copper layers are 0.5 oz copper layers, i.e., have a thickness of 18 μm. It is envisioned that these copper layers may be combined into a 3 oz copper layer.

[0022] The thickness of the upper and lower flex layers is preferably in the range of 0.01 to 0.03 mm, more preferably 0.018 mm, and the thickness of the flexible core is preferably in the range of 0.01 to 0.1 mm, more preferably 0.05 mm.

[0023] The thickness of the upper solder and lower solder is preferably in the range of 0.02 to 0.03 mm, more preferably 0.025 mm. The thickness of the upper rigid and lower rigid including the copper layer is preferably in the range of 0.01 to 0.03 mm, more preferably 0.018 mm. The thickness of the first and fifth dielectric layers is preferably in the range of 0.1 to 0.2 mm, more preferably 0.15 mm. The thickness of the GND layer and Vsupp layer is preferably in the range of 0.01 to 0.03 mm, more preferably 0.018 mm. The thickness of the second and fourth dielectric layers is preferably in the range of 0.05 to 0.09 mm, more preferably 0.068 mm.

[0024] According to another embodiment, the printed circuit board is characterized in that the surface area of ​​the NFC antenna is 200-250 mm 2 and preferably 215 to 235 mm 2 and most preferably 225 mm 2 The surface area of ​​the NFC antenna may vary depending on the given area of ​​the flexible portion or other values.

[0025] According to another embodiment, the printed circuit board is characterized in that the width of the NFC antenna, measured parallel to the short side, is between 10 and 20 mm, preferably between 13 and 17 mm, and most preferably 15 mm. The width of the NFC antenna may vary depending on the individual requirements (e.g., the desired frequency and / or the given area of ​​the flexible part). It is also envisaged that the width of the NFC antenna, measured parallel to the short side, is 65 mm.

[0026] According to another embodiment, the printed circuit board is characterized in that the width of the induction coil, measured parallel to the short side, is 10 to 20 mm, preferably 13 to 17 mm, and most preferably 15 mm. The width of the induction coil may vary depending on individual requirements (e.g., a given footprint). [Brief explanation of the drawings]

[0027] Further advantages, objects and features of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which similar elements in different embodiments may be given the same reference numerals, and in which:

[0028] [Figure 1] FIG. 1 is a plan view of a printed circuit board having an induction coil, a wireless protocol antenna, and an NFC antenna. [Figure 2a] FIG. 2 is a side view of a rigid portion and a flexible portion of a printed circuit board. [Figure 2b] FIG. 1 is a side view of a rigid portion and a flexible portion of a printed circuit board having stitching vias. [Figure 3] FIG. 1 is a schematic diagram of an electronic smoking article including a printed circuit board. DETAILED DESCRIPTION OF THE INVENTION

[0029] FIG. 1 shows a plan view of a printed circuit board 1 having an induction coil 10, a wireless protocol antenna 11a, and an NFC antenna 8. The illustrated printed circuit board 1 is foldable and can be inserted into a housing of an electronic smoking article (see FIG. 3). Preferably, the printed circuit board 1 further has two short sides 12a, b and two long sides 12c, d, and a mouthpiece (not shown here) can be placed on at least one of the short sides 12a, b. The printed circuit board 1 includes a rigid portion 3 and a flexible portion 2, both of which are disposed on at least one surface 4a, b of a common flexible layer stack.

[0030] The flexible part 2 and the rigid part 3 further include structured metal layers 5, 7 that act as an NFC antenna 8 and an induction coil 10. The structured metal layers 5, 7 preferably comprise copper. In the illustrated embodiment, one metal layer 5, 7 included in the flexible part 2 is shaped like an Ulam spiral, and the metal layer 5, 7 includes at least one track bent at a 90° angle and extending around a central portion. It is recalled that the width W2 of the NFC antenna measured along the short sides 12a, b is in the range of 10 to 30 mm. The structured metal layers 5, 7 included in the rigid part 3 are preferably shaped like a spiral. The metal layers 5, 7 include at least one track extending around a central portion. The width W1 of the induction coil measured along the short sides 12a, b can be in the range of 10 to 30 mm.

[0031] In most embodiments, the printed circuit board 1 supports multiple electrical and / or electronic components 11 in addition to the antennas 8, 10, 11a. Preferably, all of the components 11, 8, 10, 11a work together to enable various functions such as wireless charging, UHF transmission and reception, and / or near field communication. Preferably, some layers of the rigid layer stack 6 and the flexible layer stack 4 include vias that stitch together the inner metal layers. Also preferably, the induction coil 10 is prepared and stitched together with vias 9 that form 3D conductors (preferably traces).

[0032] The wireless protocol antenna 11a can preferably be arranged on at least one surface 4a, b of the printed circuit board 1. In Fig. 1, the wireless protocol antenna 11a is arranged towards a short side 12a of the first rigid layer stack 6a. The NFC antenna 8 is preferably arranged towards a short side 12b on the flexible layer stack 4 of the printed circuit board 1. The induction coil 10 is arranged towards a short side 12a on the second rigid layer stack 6b. It is also recalled that the induction coil 10 can be arranged centrally between the two short sides 12a, b (see Fig. 3).

[0033] 2a shows a side view of the rigid portion 3 and flexible portion 2 of a printed circuit board 1. The illustrated printed circuit board 1 includes a layered structure on a top surface 4a and a bottom surface 4b. The rigid portion 3 and flexible portion 2 are attached to a common flexible layer stack 4. Preferably, the top surface 4a of the rigid portion 3 includes top paste 100, top overlay 101, top solder 102, top rigid 103, dielectric 1 104, GND layer 105, and dielectric 2 106. Also, preferably, the bottom surface 4b of the rigid portion 3 includes bottom paste 113, bottom overlay 112, bottom solder 111, bottom rigid 110, dielectric 5 109, Vsupp layer 108, and dielectric 4 107.

[0034] The upper solder 102 and the lower solder 111 preferably comprise solder resist. The thickness of the upper solder 102 and the lower solder 111 is preferably 0.025 mm. The upper rigid 103 and the lower rigid 110 preferably comprise copper. The thickness of the upper rigid 103 and the lower rigid 110 is preferably 0.018 mm. The dielectric 1 104 and the dielectric 5 109 comprise a high Tg FR4 core. The thickness of the dielectric 1 104 and the dielectric 5 109 is preferably 0.150 mm. The GND layer and the Vsupp layer preferably comprise copper or other metal layers. The thickness of the GND layer and the Vsupp layer is preferably 0.018 mm. The dielectric 2 106 and the dielectric 4 107 preferably comprise prepreg 1080. The thickness of the dielectric 2 106 and the dielectric 4 107 is preferably 0.068 mm. A common flexible layer stack 4 includes a flex core, an upper flex 4c, and a lower flex 4d. The thickness of the upper flex 4c and the lower flex 4d is preferably 0.018 mm, and the thickness of the flex core 4 is preferably 0.05 mm. The upper flex 4c and the lower flex 4d preferably include copper or other metal layers. The flex core 4 preferably includes polyimide.

[0035] FIG. 2b shows a side view of the rigid portion 3 and flexible portion 2 of the printed circuit board 1 with stitching vias 9. This printed circuit board 1 includes the same layer structure as that shown in FIG. 2a. Additionally, each layer is stitched together with vias 9. The rigid portion 3 and / or flexible portion 2 preferably include blind holes with diameters ranging from 50 to 10 μm. These holes are preferably laser-made or plasma-etched into at least one of the surfaces 4a, 4b. These holes preferably extend to the GND layer 105, the upper flex 4c, the lower flex 4d, the Vsupp layer 108, or the lower rigid 110. These holes are preferably cleaned of residual resin and filled with metal (preferably copper) to electrically interconnect multiple layers. For this purpose, stitching vias are preferably electroplated, with metal-filled holes penetrating multiple layers of the printed circuit board 1.

[0036] FIG. 3 shows a schematic diagram of an electronic smoking article including a printed circuit board 1. The printed circuit board 1 further includes an induction coil 10 and an NFC antenna 8. Both antennas 10, 8 are preferably structured into multiple layers 5, 7 of the printed circuit board 1, including metal and vias (not shown). The induction coil 10 is preferably disposed on at least one rigid portion 3, which is the first rigid layer stack 6a and / or the second rigid layer stack 6b. The NFC antenna 8 is preferably disposed on at least one flexible portion 2, which is the flexible layer stack 4. In this embodiment, the induction coil 10 is disposed between two flexible portions 2. The NFC antenna 8 is preferably disposed on at least one flexible portion 2 of the printed circuit board 1.

[0037] The induction coil 10 has a width W1 and a length L1. Preferably, the width W1 is in the range of 5 to 35 mm and the length L1 is in the range of 10 to 45 mm. The NFC antenna 8 has a width W2 and a length L2. Preferably, the width W2 is in the range of 5 to 35 mm and the length L2 is in the range of 10 to 45 mm. It is also envisioned that the width W1 or W2 and the length L1 or L2 will vary depending on variables such as the number of layers and the number of track windings required. It is envisioned that the length L2 and the width W2 are similar to the length L1 and the width W1 of the induction coil 10.

[0038] The applicant reserves the right to claim all features disclosed herein as essential features of the invention, to the extent that they are novel, individually or in combination, in light of the prior art. Furthermore, it should be noted that each drawing describes features that may be advantageous individually. As those skilled in the art will readily recognize, a particular feature disclosed in a drawing may be advantageous even without the adoption of other features present in that drawing. Furthermore, as those skilled in the art will recognize, advantages may arise from combining various features disclosed in one drawing or in different drawings. [Explanation of symbols]

[0039] 1 printed circuit board 2 Flexible section 3 Rigid part 4 Common Flexible Layer Stacks / Flex Cores 4a, b Surface of a common flexible layer stack 4c, d upper flex and lower flex 5 Structured metal layer 6 Rigid Layer Stack 6a First Rigid Layer Stack 6b Second Rigid Layer Stack 7 Structured metal layer 8 NFC antenna 9 Via 10 Electromagnetic Coil / Induction Coil 11 Electrical and / or electronic components 11a wireless protocol antenna 12 Rectangular shape 12a, b two short sides 12c, d two long sides W1 Induction coil width W2 NFC antenna width L1 Induction coil length L2 NFC antenna length 100 Upper Paste 101 Top Overlay 102 Top solder 103 Upper Rigid 104 Dielectric 1 105 GND layer 106 Dielectric 2 107 Dielectric 4 108 Vsupp layer 109 Dielectric 5 110 Lower Rigid 111 Bottom solder 112 Bottom Overlay 113 Lower Paste

Claims

1. A printed circuit board (1) for mechanically supporting a plurality of electrical and / or electronic components for an electronic smoking article, electrically connected via conductive tracks, said printed circuit board comprising at least one flexible part (2) and at least one rigid part (3), said flexible part (2) and said rigid part (3) comprising a common flexible layer stack (4) comprising at least one structured metal layer (5) forming conductive tracks and / or electrical components, said rigid part (3) further comprising at least one rigid layer stack (6a) comprising at least one structured metal layer (7) forming conductive tracks and / or electrical components, said rigid layer stack (6a) being arranged on at least one surface (4a, b) of said common flexible layer stack (4); At least a portion of the structured metal layer (5) of the common flexible layer stack (4) in the flexible part (2) is structured as an electromagnetic coil forming an NFC antenna (8), and at least a portion of the structured metal layers (5, 7) of the common flexible layer stack (4) and of the rigid layer stack (6a) are structured to act together as an electromagnetic induction coil (10) suitable for wireless charging. Printed circuit board (1).

2. The common flexible layer stack (4) and the rigid part (6a) are interconnected by vias (9). A printed circuit board (1) according to claim 1, characterized in that

3. and a wireless protocol antenna (11) suitable for transmitting and receiving electromagnetic signals including frequencies of 2.4 GHz. A printed circuit board (1) according to claim 1 or 2, characterized in that it is

4. foldable into a rectangular shape (12) having two short sides (12a, b) and two long sides (12c, d), the NFC antenna (8) bordering one of the short sides (12a, b); A printed circuit board (1) according to any one of claims 1 to 3, characterized in that it

5. The device is foldable into a rectangular shape (12) having two short sides (12a, b) and two long sides (12c, d), and the electromagnetic induction coil (10) is positioned in the center (12e) between the short sides (12a, b). A printed circuit board (1) according to any one of claims 2 to 4, characterized in that

6. The via (9) is a stitching via (9).

3. A printed circuit board (1) according to claim 2, characterized in that

7. The rigid part (3) further comprises a second rigid layer stack (6b) comprising at least one structured metal layer (7) forming conductive tracks and / or electrical components, and at least a portion of the structured metal layers (5, 7) of the common flexible layer stack (4) and of each of the two rigid layers (6) are interconnected by vias (9) and structured to act together as the electromagnetic induction coil (10). A printed circuit board (1) according to any one of claims 2 to 6, characterized in that

8. The common flexible layer stack (4) and the two rigid layer stacks (6a, b) each comprise two structured metal layers (5, 7), all interconnected by vias (9) and structured to act together as the electromagnetic induction coil (10). A printed circuit board (1) according to claim 7, characterized in that

9. The electromagnetic induction coil (10) is 400 to 500 mm ２ having a surface area of A printed circuit board (1) according to any one of claims 2 to 8, characterized in that

10. The electromagnetic induction coil (10) has a diameter of 0.05 to 0.3 mm. ２ having a total cross-sectional area of ​​effective wiring formed by the interconnected structured metal layers (5, 7) of A printed circuit board (1) according to any one of claims 2 to 9, characterized in that

11. said structured metal layer (5, 7) being a copper layer; A printed circuit board (1) according to any one of claims 1 to 10, characterized in that

12. The copper layer is a 0.5 oz copper layer, i.e., has a layer thickness of 18 μm. A printed circuit board (1) according to claim 11, characterized in that

13. The NFC antenna (8) is 200 to 250 mm ２ having a surface area of A printed circuit board (1) according to any one of claims 1 to 12, characterized in that

14. The NFC antenna (8) has a width (w) measured parallel to the short sides (12a, b) of 10 to 20 mm. A printed circuit board (1) according to claim 4, characterized in that

15. The electromagnetic induction coil (10) has a width (w) measured parallel to the short sides (12a, b) of 10 to 20 mm. A printed circuit board (1) according to claim 5, characterized in that

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