Sheet-shaped inductor, flexible printed wiring board, module, and method of using laminate

Abstract

To provide a sheet-shaped inductor that can be thinned. [Solution] A transparent release film 13 and a white release film 14 are peeled off from a sheet-like inductor product 1, and the sheet-like inductor product 1 is used as a sheet-like inductor 10. The sheet-like inductor 10 comprises a conductive adhesive layer 11 and an insulating layer 12 directly or indirectly superimposed on the conductive adhesive layer 11. The conductive adhesive layer 11 functions as an inductance by connecting a first conductive pattern and a second conductive pattern that are spaced apart from each other and formed on a flexible printed wiring board.

Description

[Technical Field]

[0001] The present invention relates to a sheet-type inductor, a flexible printed wiring board, and a , Mo Joules and a method for using the laminate Regarding. [Background technology]

[0002] Inductors used in various circuits typically have a coil shape, and are soldered to a circuit board when in use. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-150179 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-243330 Summary of the Invention [Problem to be solved by the invention]

[0004] Coil-shaped inductors are difficult to miniaturize, and naturally cannot be made thin. Patent Documents 1 and 2 describe sheet-shaped inductors. However, the sheet-shaped inductors described in Patent Documents 1 and 2 have a magnetic core and a coil within the substrate, and a spiral wiring pattern that functions as an inductor within the substrate, so they cannot be made thin in practice.

[0005] One or more embodiments provide a sheet-shaped inductor that can be thinned, and provide a flexible printed wiring board and a module that can eliminate the problems of coil-shaped inductors by including a thin-film sheet-shaped inductor. and a method for using a laminate that can function as a sheet-like inductor, the method comprising: providing a conductive adhesive layer and an insulating layer; The purpose is to [Means for solving the problem]

[0006] A first aspect of one or more embodiments provides a sheet-like inductor comprising a conductive adhesive layer and an insulating layer directly or indirectly superimposed on the conductive adhesive layer, the conductive adhesive layer functioning as an inductance by connecting a first conductive pattern and a second conductive pattern that are spaced apart from each other and formed on a flexible printed wiring board.

[0007] A second aspect of one or more embodiments provides a flexible printed wiring board comprising: a first conductive pattern formed on a base film; a second conductive pattern formed on the base film so as to be spaced apart from the first conductive pattern; openings formed to expose a first end of the first conductive pattern on the second conductive pattern side and a second end of the second conductive pattern on the first conductive pattern side; a coverlay bonded to cover the first conductive pattern excluding the first end, the second conductive pattern excluding the second end, and the base film; and a sheet-like inductor of the first aspect attached to the coverlay by the conductive adhesive layer, wherein the conductive adhesive layer is bonded to the first and second ends exposed in the openings, thereby connecting the first conductive pattern and the second conductive pattern and forming an inductance between the first end and the second end.

[0008] A third aspect of one or more embodiments provides a module comprising a circuit board carrying a predetermined circuit, and the flexible printed wiring board of the second aspect connected to the circuit board. A fourth aspect of one or more embodiments is a method of using a laminate comprising a conductive adhesive layer and an insulating layer directly or indirectly superimposed on the conductive adhesive layer, in which the conductive adhesive layer is adhered to a first end of a first conductive pattern and a second end of a second conductive pattern that are spaced apart from each other and formed on a flexible printed wiring board, without being connected to a ground conductive pattern formed on the flexible printed wiring board, thereby connecting the first end and the second end, thereby causing the laminate to function as a sheet-like inductor. [Effects of the Invention]

[0009] According to one or more embodiments of the sheet inductor, a thin film can be achieved. According to one or more embodiments of the flexible printed wiring board and module, by including a thin film sheet inductor, the problems of coil-shaped inductors can be resolved. According to one or more embodiments of the method for using the laminate, the laminate including the conductive adhesive layer and the insulating layer can be made to function as a sheet-like inductor. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram illustrating a stack of sheet inductor products including one or more embodiments of a sheet inductor. [Figure 2] FIG. 2 is a perspective view showing a sheet-shaped inductor product wound in a roll. [Figure 3] FIG. 3 illustrates a stack of sheet inductor products including sheet inductors of other configurations according to one or more embodiments. [Figure 4] FIG. 4 is a partial plan view showing a base film on which a conductive pattern is formed, which constitutes a flexible printed wiring board according to one or more embodiments. [Figure 5] FIG. 5 is a partial plan view showing a state in which a coverlay having a rectangular opening formed therein is adhered to the base film shown in FIG. [Figure 6] FIG. 6 is a partial plan view showing a flexible printed wiring board according to one or more embodiments in which a sheet-like inductor is attached to the coverlay shown in FIG. [Figure 7] FIG. 7 is a cross-sectional view taken along line AA in FIG. [Figure 8] FIG. 8 is a perspective view showing the flexible printed wiring board shown in FIG. 6 in a state where the base film, the coverlay, and the sheet-like inductor (conductive adhesive layer) are shifted in the height direction. [Figure 9] FIG. 9 is a characteristic diagram showing the relationship between frequency and transmission loss in the conductive adhesive layer when AC signals with frequencies from 0 GHz to 20 GHz are applied to a pair of conductive patterns formed on the flexible printed wiring board shown in FIG. 6. [Figure 10A] FIG. 10A is an enlarged view of the portion from 0.0 GHz to 0.5 GHz in FIG. [Figure 10B] FIG. 10B is an enlarged view of the portion from 1 GHz to 10 GHz in FIG. [Figure 11] FIG. 11 is a partial plan view illustrating inductance and capacitance regions formed on a flexible printed wiring board according to one or more embodiments. [Figure 12] 12 is a circuit diagram showing a low-pass filter configured by the inductance region and capacitance region shown in FIG. 11. [Figure 13A] FIG. 13A is a partial perspective view showing a state in which a pair of conductive patterns are connected by a thin sheet-like inductor. [Figure 13B] FIG. 13B is a partial perspective view showing a state in which a pair of conductive patterns are connected by a thick sheet-like inductor. [Figure 14] FIG. 14 is a characteristic diagram showing the relationship between frequency and impedance when the sheet-shaped inductor has a predetermined length and the width is changed to 2 mm, 5 mm, 10 mm, and 15 mm. [Figure 15A] FIG. 15A is a partial perspective view showing a pair of conductive patterns connected by a short sheet-like inductor. [Figure 15B] FIG. 15B is a partial perspective view showing a pair of conductive patterns connected by a long sheet-like inductor. [Figure 16] FIG. 16 is a characteristic diagram showing the relationship between frequency and impedance when the sheet inductor has a predetermined width and its length is changed to 5 cm, 10 cm, and 15 cm. [Figure 17] FIG. 17 is a perspective view of a module according to one or more embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0011] The following describes a sheet-like inductor and a flexible printed wiring board according to one or more embodiments. , Mo Joules and a method for using the laminate This will be described with reference to the accompanying drawings.

[0012] <Sheet-type inductor> FIG. 1 shows a sheet inductor product 1 in the form in which a sheet inductor according to one or more embodiments is sold to a user. As shown in FIG. 1, an insulating layer 12 is overlaid on a conductive adhesive layer 11. A transparent release film 13 is attached to the conductive adhesive layer 11, and a white release film 14 is attached to the insulating layer 12. The insulating layer 12 is, for example, a black insulating layer. The adhesive strength of the transparent release film 13 to the conductive adhesive layer 11 is weaker than the adhesive strength of the white release film 14 to the insulating layer 12.

[0013] As shown in FIG. 2, the sheet inductor product 1 is wound into a roll. The transparent release film 13 and the white release film 14 are protective films that prevent contact between the conductive adhesive layer 11 and the insulating layer 12 of the rolled sheet inductor product 1. As described below, the transparent release film 13 and the white release film 14 are peeled off from the conductive adhesive layer 11 and the insulating layer 12, respectively. What is needed for a sheet inductor are the laminated conductive adhesive layer 11 and the insulating layer 12. The laminated conductive adhesive layer 11 and the insulating layer 12 will be referred to as a sheet inductor 10. The thicknesses of the conductive adhesive layer 11 and the insulating layer 12 are about 20 μm.

[0014] As in the sheet inductor product 1' shown in FIG. 3, a metal layer 15 may be disposed between the conductive adhesive layer 11 and the insulating layer 12. The laminated conductive adhesive layer 11, metal layer 15, and insulating layer 12 will be referred to as a sheet inductor 10'. The metal of the metal layer 15 is a conductive metal such as gold, silver, copper, iron, aluminum, or nickel. As can be seen from FIGS. 1 and 3, the sheet inductor according to one or more embodiments may be a laminate including the conductive adhesive layer 11 and the insulating layer 12 directly or indirectly superimposed on the conductive adhesive layer 11.

[0015] The sheet-like inductor 10 or 10' is attached to a flexible printed wiring board for use. A first conductive pattern and a second conductive pattern spaced apart from each other are formed on a base film of the flexible printed wiring board. The conductive adhesive layer 11 functions as an inductance by connecting the first conductive pattern and the second conductive pattern. Details of how the conductive adhesive layer 11 functions as an inductance and the flexible printed wiring board will be described later.

[0016] The conductive adhesive layer 11 contains a resin component for adhering the conductive adhesive layer 11 to the first and second conductive patterns, and a conductive powder for providing electrical continuity between the first and second conductive patterns. The proportion of conductive powder contained in the conductive adhesive layer 11 is preferably 40 weight percent or more and 70 weight percent or less. If the proportion is less than 40 weight percent, the conductive adhesive layer 11 hardly functions as an inductance. If the proportion exceeds 70 weight percent, the peak of the characteristic formed by frequency and impedance shifts too far to the high-frequency side, making it difficult to block high-frequency components. Details of the peak of the characteristic formed by frequency and impedance will be described later.

[0017] The conductive powder may be dendritic, leaf-like, flake-like, plate-like, needle-like, or grape-like. The conductive adhesive layer 11 preferably does not contain spherical conductive powder. If the conductive powder is spherical, the conductive adhesive layer 11 will function as a capacitance rather than an inductance.

[0018] It is necessary to appropriately configure the conductive adhesive layer 11 for each of the sheet-shaped inductor 10 in which the insulating layer 12 is directly superimposed on the conductive adhesive layer 11, and the sheet-shaped inductor 10' in which the insulating layer 12 is superimposed on the conductive adhesive layer 11 via the metal layer 15. The proportion or shape of the conductive powder contained in the conductive adhesive layer 11, or both the proportion and shape of the conductive powder, are appropriately set for the sheet-shaped inductor 10 and the sheet-shaped inductor 10'.

[0019] The sheet-shaped inductor 10 or 10' has a thickness of about several tens of micrometers, making it possible to make the inductor thin. The sheet-shaped inductor 10 or 10' can also be made significantly lighter than a coil-shaped inductor.

[0020] <Flexible printed wiring board> Using Figures 4 to 8, we will explain how the sheet-type inductor 10 or 10' is used in a flexible printed wiring board. Here, we will take the case where the sheet-type inductor 10 is used as an example. Figure 4 partially shows a base film 20 that constitutes a part of the flexible printed wiring board. The base film 20 is made of a polyimide film. On the base film 20, a first conductive pattern 21 made of, for example, copper, and a second conductive pattern 22 are formed at a predetermined distance from the first conductive pattern 21.

[0021] Furthermore, on the base film 20, a third conductive pattern 23 for grounding is formed, which is made of, for example, copper.

[0022] 5, a coverlay 24 is bonded to a base film 20 on which a first conductive pattern 21, a second conductive pattern 22, and a third conductive pattern 23 are formed. An opening 240, for example, having a rectangular shape, is formed in the coverlay 24. The opening 240 exposes a first end 210 of the first conductive pattern 21 on the second conductive pattern 22 side and a second end 220 of the second conductive pattern 22 on the first conductive pattern 21 side. Therefore, the coverlay 24 is bonded so as to cover the first conductive pattern 21 excluding the first end 210, the second conductive pattern 22 excluding the second end 220, the third conductive pattern 23, and the base film 20.

[0023] 7 and 8, which will be described later, the coverlay 24 has a laminated structure of an adhesive sheet 241 and a polyimide film 242. The coverlay 24 is adhered by the adhesive sheet 241 to the base film 20, on which the first conductive pattern 21, the second conductive pattern 22, and the third conductive pattern 23 are formed. The coverlay 24 functions as a circuit protection film.

[0024] 6, a sheet-like inductor 10 of a predetermined size is attached to the coverlay 24. The sheet-like inductor 10 is larger than the opening 240, and a conductive adhesive layer 11 is attached to the first end 210 and the second end 220 exposed in the opening 240. The sheet-like inductor 10 covers the coverlay 24 to both outside of the first end 210 and the second end 220. The sheet-like inductor 10 is attached to the coverlay 24 so as to partially cover the third conductive pattern 23 via the coverlay 24.

[0025] The flexible printed wiring board in the state shown in Figure 6 can be constructed as follows. The sheet-shaped inductor product 1 shown in Figures 1 and 2 is cut to a predetermined size. The transparent release film 13 is peeled off from the cut sheet-shaped inductor product 1, and the cut sheet-shaped inductor product 1 is attached to the coverlay 24 in the position shown in Figure 6. The flexible printed wiring board with the sheet-shaped inductor product 1 attached to the coverlay 24 is heated and pressure is applied using a heat press. This causes the conductive adhesive layer 11 to firmly adhere to the flexible printed wiring board. Finally, the white release film 14 is peeled off, leaving the flexible printed wiring board in the state shown in Figure 6.

[0026] 7 shows the AA cross section of FIG. 6. The sheet-like inductor 10 is in close contact with the base film 20, the first end 210, the second end 220, and the coverlay 24. The conductive adhesive layer 11 is in close contact with the first end 210 and the second end 220, and therefore connects the first conductive pattern 21 and the second conductive pattern 22. When a current flows through the first conductive pattern 21, as shown by the dashed dotted line, the first conductive pattern 21 and the second conductive pattern 22 are electrically connected via the conductive adhesive layer 11, and the current flows to the second conductive pattern 22.

[0027] 8 shows the flexible printed wiring board shown in FIG. 6 with the base film 20, coverlay 24, and sheet-like inductor 10 shifted in the height direction. Fig. 8 shows only the conductive adhesive layer 11 of the sheet-like inductor 10. The current flowing in the first conductive pattern 21, indicated by the dashed dotted line, flows into the conductive adhesive layer 11 because an opening 240 is formed in the coverlay 24, and then flows from the conductive adhesive layer 11 to the second conductive pattern 22.

[0028] Fig. 9 shows the relationship between frequency and transmission loss in the conductive adhesive layer 11 when an AC signal with a frequency of 0 GHz to 20 GHz is applied between the first conductive pattern 21 and the second conductive pattern 22 formed on the flexible printed wiring board formed as shown in Fig. 6. Fig. 10A is an enlarged view of the portion from 0.0 GHz to 0.5 GHz in Fig. 9, and Fig. 10B is an enlarged view of the portion from 1 GHz to 10 GHz in Fig. 9.

[0029] 9 to 10B, the higher the frequency, the greater the transmission loss in the conductive adhesive layer 11, and so the conductive adhesive layer 11 has the property of not allowing AC signals to pass as the frequency increases. In other words, the sheet-like inductors 10 and 10' can be used as low-pass filters that block high-frequency components of AC signals and pass DC components or low-frequency components of AC signals. Also, as can be seen from FIGS. 9 to 10B, the conductive adhesive layer 11 functions as an inductance that allows signals to flow more easily at lower frequencies and less easily at higher frequencies.

[0030] 11, an inductance region 25L where an inductance is formed is defined between the first conductive pattern 21 and the second conductive pattern 22 on the conductive adhesive layer 11. It is not essential that the sheet-like inductor 10 partially cover the third conductive pattern 23 via the coverlay 24, but it is preferable that it do. When the sheet-like inductor 10 covers the third conductive pattern 23 via the coverlay 24, a polyimide film 242, which is a dielectric, is present between the third conductive pattern 23 and the conductive adhesive layer 11. Therefore, a capacitance region 26C where a capacitance is formed is defined between the third conductive pattern 23 and the conductive adhesive layer 11.

[0031] If the sheet-like inductor 10 does not cover the third conductive pattern 23 via the coverlay 24, the flexible printed wiring board will have only the inductance region 25L. If the sheet-like inductor 10 covers the third conductive pattern 23 via the coverlay 24, the flexible printed wiring board will have the inductance region 25L and the capacitance region 26C.

[0032] The inductance region 25L and the capacitance region 26C constitute the low-pass filter shown in Fig. 12. Although the inductance provided by the inductance region 25L alone can remove high-frequency noise, the low-pass filter shown in Fig. 12 has a greater effect of removing high-frequency noise than the inductance alone. The low-pass filter shown in Fig. 12 can attenuate AC signals by rapidly reducing the gain above a predetermined cutoff frequency.

[0033] 13A and 13B show two types of sheet inductors 10 with the same length but different widths. The length of the sheet inductor 10 is the dimension in the direction connecting the first conductive pattern 21 and the second conductive pattern 22, and the width of the sheet inductor 10 is the dimension in the direction perpendicular to the direction connecting the first conductive pattern 21 and the second conductive pattern 22. FIG. 14 shows the relationship between frequency and impedance when the sheet inductor 10 has a predetermined length and the width is changed to 2 mm, 5 mm, 10 mm, and 15 mm. The narrower the width of the sheet inductor 10, the more the peak of the characteristics can be shifted to a lower frequency.

[0034] Figures 15A and 15B show two types of sheet inductors 10 with the same width but different lengths. Figure 16 shows the relationship between frequency and impedance when the sheet inductor 10 has a given width and its length is changed to 5 cm, 10 cm, and 15 cm. The longer the length of the sheet inductor 10, the more the characteristic peak can be shifted to the lower frequency side.

[0035] 14 and 16, by using the sheet inductor 10, the characteristics of the low-pass filter can be changed simply by changing the length or width of the sheet inductor 10. When using a conventional inductor with a coil shape, one must select one of several types of inductors depending on the required low-pass filter characteristics. With the sheet inductor 10, the length or width can be appropriately set depending on the required low-pass filter characteristics, greatly improving design freedom.

[0036] If the proportion of conductive powder contained in the above-mentioned conductive adhesive layer 11 exceeds 70 weight percent, it becomes difficult to block high-frequency components, because the peak of the characteristics shown in Figure 14 or Figure 16 shifts too far to the high-frequency side.

[0037] <module> 17 shows a module 100, which is an example of a module according to one or more embodiments. The module 100 is, for example, a battery module. The module according to one or more embodiments is not limited to a battery module. The module according to one or more embodiments is any module including a circuit board on which a predetermined circuit is mounted and a flexible printed wiring board connected to the circuit board.

[0038] 17, the module 100 includes battery cells 30a-30h, a circuit board 32, and a flexible printed wiring board 200. The number of battery cells included in the module 100 is not limited to eight. Terminals 31a-31h provided corresponding to the battery cells 30a-30h, respectively, are connected to conductive patterns 21a-21h formed on the flexible printed wiring board 200. The conductive patterns 21a-21h correspond to the first conductive pattern 21 shown in FIG. 11. In FIG. 17, the coverlay 24 and the third conductive pattern 23 are not shown.

[0039] Conductive patterns 22a to 22h are connected to the circuit board 32. The conductive patterns 22a to 22h correspond to the second conductive pattern 22 shown in FIG. 11. The conductive patterns 21a to 21h are spaced a predetermined distance from the opposing conductive patterns 22a to 22h. Sheet inductors 10a to 10h are provided to connect the conductive patterns 21a to 21h and the conductive patterns 22a to 22h, respectively. The sheet inductors 10a to 10h correspond to the sheet inductor 10 shown in FIG. 11.

[0040] As an example, the circuit board 32 is a control board that controls the voltage of the module 100. A voltage monitoring signal that monitors the voltage of each of the battery cells 30a to 30h is supplied to a control circuit formed on the circuit board 32 via the conductive patterns 21a to 21h, the sheet-like inductors 10a to 10h, and the conductive patterns 22a to 22h.

[0041] 17, let us assume that module 100 does not include sheet-like inductors 10a-10h, but has a conductive pattern that connects terminals 31a-31h to circuit board 32. In this case, a coil-shaped inductor needs to be mounted on the circuit formed on circuit board 32. That is, a typical circuit board has a soldered coil-shaped inductor. With soldered inductors, there is a risk that the solder will be damaged by vibrations applied to the circuit board due to aging, causing the inductor to fall off. As described above, sheet-like inductors 10a-10h (sheet-like inductors 10) are firmly adhered to flexible printed wiring board 200 by conductive adhesive layer 11, and therefore there is little risk of them falling off.

[0042] In this way, module 100 including sheet-shaped inductors 10a-10h does not include a coil-shaped inductor, and therefore can eliminate the problems that coil-shaped inductors have. Module 100 can significantly improve adhesion reliability during vibration.

[0043] The flexible printed wiring board 200 included in the module 100 includes sheet-like inductors 10a to 10h instead of the coil-shaped inductors mounted on the circuit board 32. Therefore, by using the flexible printed wiring board 200 in the module 100, it is possible to eliminate the problems that arise from mounting the coil-shaped inductors on the circuit board 32.

[0044] Generally, in a circuit board on which a coil-shaped inductor is mounted, the inductor is larger than other circuit components and has the largest height dimension. Therefore, the height dimension of the module increases depending on the height of the inductor. In contrast, module 100 includes a circuit board 32 on which a coil-shaped inductor is not mounted, allowing for a smaller height dimension.

[0045] The present invention is not limited to one or more of the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. [Explanation of symbols]

[0046] 1,1' Sheet inductor products 10, 10', 10a~10h sheet inductor 11 Conductive adhesive layer 12 Insulating layer 13 Transparent release film 14 White release film 15 metal layer 20 base film 21 First conductive pattern 21a~21h, 22a~22h Conductive patterns 22 Second conductive pattern 23 Third conductive pattern 24 Coverlay 25L Inductance Area 26C Capacitance Area 30a~30h battery cell 31a~31h terminals 32 Circuit Board 100 modules 200 Flexible printed wiring board 210 first end 220 second end 240 aperture 241 Adhesive Sheet 242 Polyimide film

Claims

1. a conductive adhesive layer; an insulating layer directly or indirectly superposed on the conductive adhesive layer; Equipped with The conductive adhesive layer is not connected to a conductive pattern for ground formed on the flexible printed wiring board, but functions as an inductance by connecting a first conductive pattern and a second conductive pattern that are spaced apart from each other and are formed on the flexible printed wiring board. Sheet inductor.

2. The conductive adhesive layer is a resin component for adhering the conductive adhesive layer to the first and second conductive patterns; a conductive powder for providing electrical continuity between the first and second conductive patterns; Contains The sheet inductor according to claim 1 .

3. 3. The sheet inductor according to claim 2, wherein the conductive powder is contained in the conductive adhesive layer in a proportion of 40 weight percent or more and 70 weight percent or less.

4. 4. The sheet inductor according to claim 2, wherein the conductive powder has any one of a dendritic, leaf-like, flake-like, plate-like, needle-like, and grape-like shape.

5. The sheet inductor according to claim 1 or 2, further comprising a metal layer between the conductive adhesive layer and the insulating layer.

6. a first conductive pattern formed on a base film; a second conductive pattern formed on the base film so as to be spaced apart from the first conductive pattern; a coverlay having openings that expose a first end of the first conductive pattern on the second conductive pattern side and a second end of the second conductive pattern on the first conductive pattern side, the coverlay being bonded to cover the first conductive pattern excluding the first end, the second conductive pattern excluding the second end, and the base film; the sheet inductor according to claim 1 attached to the coverlay by the conductive adhesive layer; Equipped with The conductive adhesive layer is bonded to the first and second ends exposed in the opening, thereby connecting the first conductive pattern and the second conductive pattern, and forming an inductance between the first end and the second end. Flexible printed wiring board.

7. a third conductive pattern for ground formed on the base film; the coverlay is adhered to cover the third conductive pattern, the sheet-like inductor is attached to the third conductive pattern via the coverlay by the conductive adhesive layer so as to partially cover the third conductive pattern; A capacitance is formed between the third conductive pattern and the conductive adhesive layer. The flexible printed wiring board according to claim 6 .

8. a circuit board on which a predetermined circuit is mounted; The flexible printed wiring board according to claim 6 or 7, which is connected to the circuit board; A module comprising:

9. A method of using a laminate comprising a conductive adhesive layer and an insulating layer directly or indirectly superimposed on the conductive adhesive layer, The conductive adhesive layer is bonded to a first end of a first conductive pattern and a second end of a second conductive pattern that are spaced apart from each other and are formed on the flexible printed wiring board, without being connected to a conductive pattern for ground formed on the flexible printed wiring board, thereby connecting the first end and the second end, thereby causing the laminate to function as a sheet-like inductor. How to use the laminate.

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