This application claims the benefit of Japanese Patent Application No. 2022-029828, filed on Feb. 28, 2022, the entire disclosure of which is incorporated by reference herein.
The present disclosure relates to an antenna module. JP 2013-236267A discloses a method of manufacturing an antenna module. The method includes attaching an adhesive layer to a coil pattern formed on the surface of a substrate, removing the substrate, and attaching a magnetic member in place of the substrate. Accordingly, a final product does not include the substrate, thereby achieving thinning of the antenna module.
However, in the antenna module described in JP 2013-236267A, a large irregularity occurs in the adhesive layer, so that when the antenna module is attached to an object, flatness is lost.
An antenna module according to the present disclosure includes: a coil pattern planarly wound in a plurality of turns; a first adhesive layer attached to one surface of the coil pattern in the axial direction of the coil pattern; a second adhesive layer attached to the other surface of the coil pattern in the axial direction of the coil pattern; and a magnetic member attached to the first adhesive layer and disposed on the side opposite to the coil pattern with respect to the first adhesive layer. The first and second adhesive layers bulge to a gap between the patterns of the coil pattern. This makes it possible to ensure high flatness and to prevent a progressive short-circuit failure.
The above features and advantages of the present disclosure will be more apparent from the following description of certain preferred embodiments taken in conjunction with the accompanying drawings, in which:
An object of the present disclosure to provide an antenna module capable of ensuring flatness.
Preferred embodiments of the present disclosure will be explained below in detail with reference to the accompanying drawings.
As illustrated in
The antenna module 1 is connected to, for example, a not-shown near field wireless communication (NFC) circuit to function as an NEC antenna coil that performs near field wireless communication with a communication target device. The antenna module 1 also functions as a wireless power transmission coil that performs wireless power feeding using a frequency band (e.g., 13.56 MHz) of the near field wireless communication. Further, the antenna module 1 can be made to function as a coil that performs both the near field wireless communication and wireless power feeding.
As illustrated in
As illustrated in
The second adhesive layer 20 has an adhesive surface 21 attached to the coil pattern C and an adhesive surface 22 attached to the liner layer 50. This allows the coil pattern C and liner layer 50 to be fixed to each other by the second adhesive layer 20. The second adhesive layer 20 may be a pressure sensitive adhesive having heat resistance, such as an acrylic adhesive, a silicon adhesive, a urethane adhesive, or a rubber adhesive. The liner layer 50 is removed when the antenna module 1 according to the present embodiment is mounted on a communication device. That is, the liner layer 50 plays a role of covering the adhesive surface 22 of the second adhesive layer 20 in a state before the antenna module 1 is mounted on a communication device. Then, the liner layer 50 is removed upon mounting of the antenna module 1 according to the present embodiment on the communication device to expose the adhesive surface 22 of the second adhesive layer 20, and the exposed adhesive surface 22 is attached to the communication device.
As described above, the antenna module 1 according to the present embodiment has a structure in which the coil pattern C is sandwiched between the first and second adhesive layers 10 and 20 from both sides in the coil axis direction. Further, as illustrated in
The coil pattern C has such a sectional shape that the pattern width thereof increases toward the first adhesive layer 10. However, the coil pattern C need not necessarily vary in pattern width over the entire cross section but may partly include a portion whose pattern width does not vary. This is due to a manufacturing process. That is, in manufacturing of the antenna module 1 according to the present embodiment, first the coil pattern C is formed on the surface of an insulating substrate 70 made of PET (Poly Ethylene Terephthalate) or the like as illustrated in
At the time when the first adhesive layer 10 is attached to one surface of the coil pattern C, the second adhesive layer 20 already exists on the other surface of the coil pattern C, so that displacement is distributed vertically so as to be the deformation of the first adhesive layer 10 and the deformation of the second adhesive layer 20, thereby ensuring high flatness of the antenna module 1.
The coil pattern C decreases in pattern width as it approaches the second adhesive layer 20, so that even when the first and second adhesive layers 10 and 20 are made of the same material, the second adhesive layer 20 is larger in the bulging amount than the first adhesive layer 10, with the result that the flatness of the adhesive surface 22 of the second adhesive layer 20 deteriorates. To suppress this, the first adhesive layer 10 may be made smaller in thickness than the second adhesive layer 20. This allows a sufficient degree of flatness of the adhesive surface 22 to be ensured even when the bulging amount of the second adhesive layer 20 is large. On the other hand, the first adhesive layer 10 is small in bulging amount, so that even when it is smaller in thickness than the second adhesive layer 20, the flatness of the adhesive surface 12 is ensured, whereby a variation in the distance between the coil pattern C and the magnetic member 30 can be suppressed. The bulging amount of the first adhesive layer 10 refers to the protruding amount from the interface between the adhesive surface 11 of the first adhesive layer 10 and the coil pattern C toward the second adhesive layer 20, and the bulging amount of the second adhesive layer 20 refers to the protruding amount from a part of the interface between the adhesive surface 21 of the second adhesive layer 20 and the coil pattern C that is closest to the liner layer 50 toward the first adhesive layer 10.
As described above, the antenna module 1 according to the present embodiment does not include a substrate, thereby achieving thinning. Further, in the antenna module 1 according to the present embodiment, the coil pattern C is sandwiched between the first and second adhesive layers 10 and 20 from both sides in the axial direction of the coil, so that it is possible to ensure high flatness and to prevent a progressive short-circuit failure caused by metal residue.
To further achieve higher flatness, a non-conductive member 60 may be disposed in the opening of the coil pattern C, as illustrated in
When there is a need for the antenna module 1 to have sufficient flexibility, a material having a Young's modulus lower than that of a metal material constituting the coil pattern C may be used. This makes it possible to suppress deterioration in flexibility due to the use of the non-conductive member 60.
When the planar size of the non-conductive member 60 is made substantially the same as that of the opening area of the coil pattern C, a higher degree of flatness can be obtained.
Alternatively, like an antenna module 2 according to a second embodiment illustrated in
In the recess 42, the first adhesive layer 10 and magnetic member 30 are deformed toward the metal member 40 into a mountain shape, so that by forming the recess in a wider area than the winding width from the inner edge of the innermost turn to the outer edge of the outermost turn of the coil pattern C, the entire deformed part of each of the first adhesive layer 10 and magnetic member 30 can be absorbed.
The antenna module 3 according to the third embodiment illustrated in
The antenna module 4 according to the fourth embodiment illustrated in
While the preferred embodiment of the present disclosure has been described, the present disclosure is not limited to the above embodiment, and various modifications may be made within the scope of the present disclosure, and all such modifications are included in the present disclosure.
The technology according to the present disclosure includes the following configuration examples but not limited thereto.
An antenna module according to the present disclosure includes: a coil pattern planarly wound in a plurality of turns; a first adhesive layer attached to one surface of the coil pattern in the axial direction of the coil pattern; a second adhesive layer attached to the other surface of the coil pattern in the axial direction of the coil pattern; and a magnetic member attached to the first adhesive layer and disposed on the side opposite to the coil pattern with respect to the first adhesive layer. The first and second adhesive layers bulge to a gap between the patterns of the coil pattern. This makes it possible to ensure high flatness and to prevent a progressive short-circuit failure.
The antenna module according to the present disclosure may further include a non-conductive member disposed in the opening of the coil pattern and attached to at least one of the first and second adhesive layers. This makes it possible to prevent a recess from occurring at a part overlapping the opening of the coil pattern. The non-conductive member may be attached to both the first and second adhesive layers. This allows the coil pattern and the first and second adhesive layers to be fixed to each other more firmly. The thickness of the non-conductive member may be equal to the thickness of the coil pattern. This makes it possible to achieve a higher degree of flatness. Further, the Young's modulus of the non-conductive member may be lower than that of a metal material constituting the coil pattern. This makes it possible to ensure the flexibility of the entire antenna module.
The coil pattern may have such a sectional shape that the pattern width thereof increases toward the first adhesive layer, and the first adhesive layer may be smaller in thickness than the second adhesive layer. This makes it possible to suppress deterioration in flatness due to the presence of the bulging part. In this case, the bulging amount of the second adhesive layer between the patterns may be larger than the bulging amount of the first adhesive layer between the patterns. This makes it possible to suppress a variation in the distance between the coil pattern and the magnetic member.
The antenna module according to the present disclosure may further include a metal member disposed on the side opposite to the first adhesive layer with respect to the magnetic member. This makes it possible to reflect electromagnetic wave noise mainly in a high frequency region. In this case, a recess corresponding to the pattern shape of the coil pattern may be formed in the inner surface of the metal member on the magnetic member side. This makes it possible to prevent a recess from occurring at a part overlapping the opening of the coil pattern. Further, a slit may be formed in the metal member. This suppresses the generation of a demagnetizing field and which in turn can suppress deterioration in communication characteristics.
Number | Date | Country | Kind |
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2022-029828 | Feb 2022 | JP | national |