NFC antenna and terminal

Abstract

The present invention provides an NFC antenna, comprising a magnetic isolation component and an FPC component stacked in sequence; the magnetic isolation component comprises a magnetic isolation adhesive layer, a ferrite layer, and a cover film layer stacked in sequence; the FPC component comprises an adhesive layer, a base layer, and a coil layer stacked in sequence; the coil layer comprises a first routing line and a second routing line; the first routing line is provided with a first feeding point at one end close to the inner side of the coil layer; the second routing line is provided with a second feeding point at one end close to the inner side of the coil layer; a spring is provided in the middle of the adhesive layer; the spring is provided with a conductive member at positions corresponding to the first feeding point and the second feeding point; when an extra layer of FPC is attached, the first feeding point and the second feeding point will be short-circuited, and the inductance and frequency of the NFC antenna will be greatly changed, which is easy to detect. This solves the problem of difficulty in detecting extra FPC during NFC antenna processing in the past.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology, and in particular to the design of an NFC antenna that is more easily detectable during a production process. Background Art

[0002] Near-field communication (NFC) technology has become increasingly widespread in recent years, and the number of devices capable of NFC communication has also increased. NFC-enabled devices require an NFC chip and an NFC antenna. NFC antennas are near-field coupling antennas that implement NFC through magnetic coupling, i.e., coil coupling.

[0003] NFC antennas are generally composed of FPC coils bonded to ferrite, and the bonding is mostly done manually.

[0004] During the lamination process, one ferrite coil (or FPC coil) is fixed before another FPC coil (or ferrite coil) is attached. There's a high probability that production line workers will over-attach one FPC or one ferrite. Even with automated lamination, over-attachment can still occur. Over-attaching ferrite significantly increases the antenna's inductance, thereby lowering its resonant frequency. This can be detected and intercepted using a jig and mesh interception method, or by directly testing the inductance with an LCR meter. However, over-attaching an FPC coil significantly increases the antenna's inductance, significantly lowering the antenna's resonant frequency. However, since the two layers of FPC traces almost completely overlap, the impact on the antenna's resonant frequency is minimal, making it difficult to completely intercept using a jig and mesh interception method. The frequency waveform of some NFC antennas with two layers of FPC can differ minimally or even overlap with that of a standard single-layer FPC antenna, making interception impossible.

[0005] According to Thomson's formula, the frequency of the NFC antenna is related to the resistance and inductance of the coil. When the coil is short-circuited, the resistance of the coil decreases, and accordingly, the inductance decreases significantly and the frequency increases significantly. Summary of the Invention

[0006] The present invention aims to provide an NFC antenna and a terminal to solve the problem of difficulty in detecting a double-layer FPC during NFC antenna processing.

[0007] To solve the above problems, the present invention provides an NFC antenna, comprising a magnetic isolation component and an FPC component stacked in sequence; the magnetic isolation component comprises a magnetic isolation adhesive layer, a ferrite layer and a cover film layer stacked in sequence; the FPC component comprises an adhesive layer, a base layer and a coil layer stacked in sequence; the coil layer comprises a first trace and a second trace; the first trace is provided with a first feeding point at one end close to the inner side of the coil layer; the second trace is provided with a second feeding point at one end close to the inner side of the coil layer; a spring is provided in the middle of the adhesive layer; and the spring is provided with a conductive member at positions corresponding to the first feeding point and the second feeding point.

[0008] Optionally, in the NFC antenna, a clearance groove is provided in the middle of the FPC component.

[0009] Optionally, in the NFC antenna, the adhesive layer and the magnetic isolation adhesive layer are made of acrylic adhesive or double-sided adhesive.

[0010] Optionally, in the NFC antenna, the base layer is made of PET or PI.

[0011] Optionally, in the NFC antenna, the conductive member is a metal patch, a metal coil, a metal spring, a metal convex bump, or a conductive adhesive coating area.

[0012] Optionally, in the NFC antenna, the conductive element is circular, curved, polygonal, or has a special-shaped structure.

[0013] Optionally, in the NFC antenna, a metal flying wire is attached to the outermost side of the adhesive layer, and the first routing wire and the second routing wire are connected through the metal flying wire.

[0014] Optionally, in the NFC antenna, the first wiring, the second wiring, and the metal flying wire are made of copper or silver.

[0015] Optionally, in the NFC antenna, surfaces of the first trace and the second trace are covered with ink or adhesive.

[0016] The present invention further provides a terminal, which includes the NFC antenna.

[0017] The present invention provides an NFC antenna, comprising a magnetic shielding assembly and an FPC assembly stacked in sequence; the magnetic shielding assembly comprising a magnetic shielding adhesive layer, a ferrite layer, and a cover film layer stacked in sequence; the FPC assembly comprising an adhesive layer, a base layer, and a coil layer stacked in sequence; the coil layer comprising a first trace and a second trace; the first trace having a first feeding point at one end proximate to the inner side of the coil layer; the second trace having a second feeding point at one end proximate to the inner side of the coil layer; a spring sheet disposed in the middle of the adhesive sheet; and a conductive member disposed on the spring sheet at positions corresponding to the first and second feeding points. When the NFC antenna is attached to a double layer of FPC, the first feeding point, the second feeding point, and the conductive member are attached together to form a short circuit, thereby significantly affecting the inductance and frequency of the NFC antenna, making it easy to detect an NFC antenna with an extra FPC layer using an LCR meter or a network analyzer. By redesigning the structure of the NFC antenna coil layer and adhesive sheet, the problem of the previous NFC antenna manufacturing process being difficult to detect with a network analyzer alone due to the extra FPC layer being attached is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 This is a structural diagram of the coil layer and adhesive layer of the NFC antenna FPC assembly provided in Example 1;

[0020] Figure 2 This is a structural diagram of the coil layer and adhesive layer of the NFC antenna FPC assembly provided in Example 2;

[0021] Figure 3 Cross-sectional comparison diagrams of the NFC antenna provided in Example 1 when attached to a single-layer FPC and when attached to a double-layer FPC;

[0022] Figure 4 Cross-sectional comparison diagrams of the NFC antenna provided in Example 2 when attached to a single-layer FPC and when attached to a double-layer FPC;

[0023] Figure 5 A front view of the substrate layer of the NFC antenna provided in this embodiment;

[0024] Figure 6 A front view of the magnetic shielding component of the NFC antenna provided in this embodiment;

[0025] Figure 7This is a frequency test diagram of the traditional NFC structure with a single-layer FPC attached;

[0026] Figure 8 This is a frequency test diagram of the traditional NFC structure with a double-layer FPC attached;

[0027] Figure 9 This is a frequency test diagram of the surface PFC contact point when the NFC antenna provided in this embodiment is attached with a double-layer FPC;

[0028] Figure 10 This is a frequency test diagram of the bottom PFC contact point when the NFC antenna provided in this embodiment is attached with a double-layer FPC;

[0029] The descriptions of the reference numerals are as follows:

[0030] 1-coil layer; 2-adhesive layer; 3-clearance slot; 4-base layer; 5-magnetic isolation component; 11-first routing line; 12-second routing line; 21-metal flying lead; 22-spring; 51-covering film layer; 52-ferrite layer; 53-magnetic isolation adhesive layer; 111-first feeding point; 121-second feeding point; 221-conductive part. DETAILED DESCRIPTION

[0031] The following is a further detailed description of an NFC antenna proposed by the present invention in conjunction with the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not in exact proportions. They are only used to conveniently and clearly assist in illustrating the purpose of the embodiments of the present invention. In addition, the structures shown in the drawings are often part of the actual structure. In particular, different drawings may need to show different focuses and sometimes use different proportions.

[0032] It should be noted that the terms "first", "second", etc. in the specification, claims, and accompanying drawings of the present invention are used to distinguish similar objects in order to describe the embodiments of the present invention, and are not used to describe a specific order or sequence. It should be understood that the structures used in this way can be interchanged under appropriate circumstances. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or are inherent to these processes, methods, products, or apparatuses.

[0033] The NFC antenna of this embodiment includes a magnetic isolation component 5 and an FPC component stacked in sequence; the magnetic isolation component 5 includes a magnetic isolation adhesive layer 53, a ferrite layer 52 and a covering film layer 51 stacked in sequence; the FPC component includes an adhesive layer 2, a base layer 4 and a coil layer 1 stacked in sequence; the coil layer includes a first trace 11 and a second trace 12; a first feeding point 111 is provided at one end of the first trace 11; a second feeding point 121 is provided at one end of the second trace 12; a spring 22 is provided in the middle of the adhesive layer 2; and a conductive member 221 is provided on the spring 22 at positions corresponding to the first feeding point 111 and the second feeding point 121.

[0034] Preferably, the magnetic isolation adhesive layer 53 and the adhesive layer 2 are made of acrylic adhesive. Acrylic adhesive has good insulation properties and is chemically stable, not easily corroded by acidic and alkaline substances. It also has good heat and cold resistance, allowing it to better adhere to objects in different environments.

[0035] Figure 5 This is a front view of the substrate layer of the NFC antenna provided in this embodiment. The substrate layer 3 is made of PET. PET has excellent mechanical properties, stronger impact resistance, good high and low temperature resistance, and good corrosion resistance, which can effectively protect the coil layer 1 from corrosion. PET also has a good barrier effect when used as a protective material, can isolate water vapor, air, oily substances and ultraviolet rays, and can protect the coil layer 1 from oxidation.

[0036] Figure 6 This is a front view of the magnetic isolation component of the NFC antenna provided in this embodiment. The magnetic isolation component 5 can provide a relatively stable magnetic environment for the coil layer 1 to prevent other metal devices from affecting the NFC antenna.

[0037] More preferably, the first wiring 11 , the second wiring 12 and the metal flying wire 21 are made of copper or silver.

[0038] The NFC antenna of this embodiment is attached as follows:

[0039] 1. For the FPC component, first adhere the coil layer to any side of the base layer, then adhere the adhesive layer 2 to the other side of the base layer 4, with the first trace 11 and the second trace 12 having the feeding point at the end as the starting end and the other end as the end. When adhering, the end of the first trace 11 and the end of the second trace 12 are connected together through the metal flying wire 21.

[0040] 2. For the magnetic isolation component 5 , first adhere the cover film layer 51 to any one side of the ferrite layer 52 , and then adhere the magnetic isolation adhesive layer 53 to the other side of the ferrite layer 52 .

[0041] 3. As for the overall NFC antenna part, the side of the FPC component having the adhesive layer 2 is attached to the side of the magnetic isolation component 5 having the cover film layer 51 .

[0042] Preferably, the clearance groove 3 is provided in the middle of the FPC assembly, so that after bonding, the torsional resistance of the entire NFC antenna can be increased and it is not easy to break when bent.

[0043] Preferably, the conductive member 221 is circular, curved, polygonal or irregular in shape.

[0044] Example 1:

[0045] Figure 1 The structure diagram of the coil layer and adhesive layer of the NFC antenna FPC component provided in Example 1 is as follows: Figure 1 As shown, it includes a coil layer 1 and a backing adhesive layer 2; the coil layer 1 includes a first trace 11 and a second trace 12, a first feeding point 111 is provided at one end of the first trace 11, and a second feeding point 121 is provided at one end of the second trace 12; the backing adhesive layer 2 is provided with a conductive member 221 at a position corresponding to the first feeding point 111 and the second feeding point 121. In this embodiment, the conductive member 221 is a metal patch.

[0046] In order to prevent some metals from being oxidized or corroded, the common practice is:

[0047] 1. When the metal surface is not used as a direct contact conductor, paint, room temperature solid glue, etc. can be applied to the surface of the protected metal to prevent the protected metal from direct contact with the external environment, thereby reducing the risk of corrosion or oxidation.

[0048] 2. When the metal surface is used as a direct contact conductor, but the conductivity requirements are not particularly high, other metals can be plated on the metal surface or conductive adhesive with general conductivity can be coated on it, such as zinc, nickel, zinc-based conductive adhesive, etc. The other metals or conductive adhesive are directly exposed to the external environment, and the electroplated metal can form anodic protection. The time for the conductive adhesive to be corroded or oxidized is much longer than that of the protected metal, thereby achieving the effect of protecting the entire part.

[0049] 3. When the metal surface is used as a direct contact conductor and has very high requirements for conductivity, the metal surface can be plated with an inert metal with good conductivity or coated with a conductive adhesive with good conductivity, such as gold, silver, gold-based conductive adhesive, carbon-based conductive adhesive, etc. The inert metal or conductive adhesive is in direct contact with the external environment, and the inert metal and conductive adhesive are corroded or oxidized for a much longer time than the protected metal. Therefore, the entire part can be protected, and the conductivity of the entire component will not decrease.

[0050] 4. Passivate the surface of metal parts.

[0051] 5. Use new alloy materials as the base materials of parts.

[0052] In this embodiment, since the conductive member 221 is easily corroded or oxidized, which affects the performance and service life of the NFC antenna, and the NFC antenna coil has high requirements for conductivity, the surface of the conductive member 221 is gold-plated to increase conductivity and prevent corrosion or oxidation.

[0053] Figure 3 The cross-sectional comparison diagrams of the NFC antenna provided in Example 1 when attached to a single-layer FPC and when attached to a double-layer FPC show that when the NFC antenna is mistakenly attached to two layers of FPC during processing, the metal patch portion of the upper FPC will attach to the first feeding point 111 and the second feeding point 121 of the lower FPC. Since all three parts are conductive, the first feeding point 111 and the second feeding point 121 of the lower FPC will form a short circuit. When a short circuit occurs, the inductance of the NFC antenna is significantly reduced and the frequency is significantly increased. Whether using an LCR instrument to test inductance or a network analyzer to test frequency, defective products attached to the double-layer FPC can be easily detected. On the other hand, for the upper FPC, the lower FPC is now equivalent to a large metal coil or metal block, physically isolating the effect of the ferrite. At this time, the inductance of the upper FPC is also greatly reduced, thereby significantly increasing the frequency of the NFC antenna.

[0054] Example 2:

[0055] Figure 2 The structural diagram of the NFC antenna provided in Example 2 is as follows: Figure 2As shown, it includes a coil layer 1 and a backing glue layer 2; the coil layer 1 includes a first trace 11 and a second trace 12, a first feeding point 111 is provided at one end of the first trace 11, and a second feeding point 121 is provided at one end of the second trace 12; the backing glue layer 2 is provided with a conductive member 221 at a position corresponding to the first feeding point 111 and the second feeding point 121. In this embodiment, the conductive member 221 is a conductive backing glue coating area.

[0056] Preferably, the conductive adhesive coated on the conductive member 221 of this embodiment is an isotropic silver-based conductive adhesive. Isotropic conductive adhesives have good conductivity in all directions in the three-dimensional space. Furthermore, since the conductive member 221 of this embodiment has high conductivity requirements, a silver-based conductive adhesive with better conductivity is selected.

[0057] It should be further explained that the conductive adhesive used in this embodiment, which is an isotropic silver-based conductive adhesive, is merely a preferred embodiment. It is well known to those skilled in the art that conductive adhesives with y-axis anisotropy can also achieve the effect of short-circuiting uncovered coils. Conductive adhesives made of other materials, such as gold-based conductive adhesives and copper-based conductive adhesives, can also achieve the same effect. Therefore, the scope of protection of the present invention should not be limited to the specific contents of the above-mentioned embodiment; other materials or conductive adhesives, provided they do not violate the main purpose of the present invention, are also within the scope of protection of the present invention.

[0058] Figure 4 The cross-sectional comparison diagrams of the NFC antenna provided in Example 2 when attached to a single-layer FPC and when attached to a double-layer FPC show that when the NFC antenna is processed and two layers of FPC are attached due to misoperation, the conductive adhesive-coated area of ​​the upper FPC will be attached to the first feeding point 111 and the second feeding point 121 of the lower FPC. Because the conductive adhesive coating area is conductive, when it is attached to the first feeding point 111 and the second feeding point 121, a short circuit is formed between the first feeding point 111 and the second feeding point 121 of the lower FPC. When the first feeding point 111 and the second feeding point 121 of the lower FPC are short-circuited, the inductance of the NFC antenna is significantly reduced and the frequency is significantly increased. Whether using an LCR instrument to test inductance or a network analyzer to test frequency, defective products with double-layer FPC can be easily detected. On the other hand, for the upper FPC, the lower FPC is equivalent to a large metal coil or metal block, which physically isolates the effect of the ferrite. At this time, the inductance of the upper FPC is also greatly reduced, thereby significantly increasing the frequency of the NFC antenna.

[0059] It should be noted that this embodiment only provides a frequency test diagram for the NFC antenna, and does not provide an inductive sensing diagram. In this embodiment, the inductance of the NFC antenna is significantly reduced when an FPC is attached. The inductance testing method is well known to those skilled in the art and will not be described in detail here.

[0060] Figure 6 This is a frequency test diagram of a traditional NFC structure with a single-layer FPC attached. The frequency test value after adding the fixture is approximately 13.5MHz.

[0061] Figure 7 This is a frequency test diagram of a traditional NFC structure with a double-layer FPC. As can be seen from the figure, when the traditional NFC structure is tested by a network analyzer, the return loss difference between a good single-FPC product and a defective dual-FPC product is only about 1dB, and the frequency is almost the same, making it difficult for the network analyzer to identify the defective products.

[0062] Figure 8 The frequency test diagram of the surface PFC contact point of the NFC antenna provided in this embodiment when a double-layer FPC is attached is shown. As can be seen from the figure, the test value of the surface PFC contact point when the NFC antenna is attached with a double-layer FPC is approximately 59MHz, which is much higher than the normal value of 13.5MHz for a single-layer FPC.

[0063] Figure 9 The frequency test diagram of the bottom PFC contact point of the NFC antenna provided in this embodiment when a double-layer FPC is attached is shown. As can be seen from the figure, the test value of the surface PFC contact point when the NFC antenna is attached with a double-layer FPC is about 53MHz, which is much higher than the normal value of 13.5MHz for a single-layer FPC.

[0064] Combine Figure 6 and Figure 7 The analysis shows that in actual processing, regardless of whether an additional layer of PFC is applied above or below the normal PFC, it is possible to simply and directly test whether the current product is good or defective using a network analyzer alone. At the same time, the requirements for the fixture used in network analyzer testing are also relaxed, and good or defective products can be tested on both the bottom and upper NFC layers.

[0065] It should be noted that the shape, structure, and dimensions of the NFC antenna in this embodiment are based on actual products. Clearly, this solution can be applied to any NFC antenna with a two-layer laminated structure consisting of an FPC component and a magnetic shielding component, and there are no restrictions on the choice of conductive material. Therefore, other NFC antenna shapes, structures, dimensions, and choices of conductive materials, as long as they do not violate the spirit of the present invention, are also within the scope of protection of this invention.

[0066] In summary, this embodiment provides an NFC antenna, comprising a magnetic isolation component and an FPC component stacked in sequence; the magnetic isolation component comprises a magnetic isolation adhesive layer, a ferrite layer and a cover film layer stacked in sequence; the FPC component comprises an adhesive layer, a base layer and a coil layer stacked in sequence; the coil layer comprises a first trace and a second trace; the first trace is provided with a first feeding point at one end close to the inner side of the coil layer; the second trace is provided with a second feeding point at one end close to the inner side of the coil layer; a spring is provided in the middle of the adhesive layer; the spring is provided with a conductive member at a position corresponding to the first feeding point and the second feeding point; when the NFC antenna is affixed with a double-layer FPC, the first feeding point, the second feeding point and the conductive member are affixed together to form a short circuit, thereby greatly affecting the inductance and frequency of the NFC antenna, so that an LCR instrument or a network analyzer can easily determine the NFC antenna with multiple FPCs affixed. By redesigning the structure of the NFC antenna coil layer and the adhesive layer, the problem of an extra FPC layer being difficult to detect using a network analyzer during NFC antenna processing was solved.

[0067] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other. In addition, the different parts between the various embodiments can also be used in combination with each other, and the present invention is not limited to this.

[0068] The above description is only a description of the preferred embodiments of the present invention and does not limit the scope of the present invention. Any changes and modifications made by ordinary technicians in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. An NFC antenna, comprising a magnetic shielding component and an FPC component stacked in sequence; the magnetic shielding component comprises a magnetic shielding adhesive layer, a ferrite layer, and a cover film layer stacked in sequence; the FPC component comprises an adhesive layer, a base layer, and a coil layer stacked in sequence; the coil layer comprises a first trace and a second trace; the first trace is provided with a first feeding point at one end close to the inner side of the coil layer; the second trace is provided with a second feeding point at one end close to the inner side of the coil layer; a spring sheet is provided in the middle of the adhesive sheet; the spring sheet is provided with a conductive member at positions corresponding to the first feeding point and the second feeding point; a clearance slot is provided in the middle of the FPC component; a metal flying lead is attached to the outermost side of the adhesive sheet, and the ends of the first trace and the second trace are connected by the metal flying lead; When two layers of FPC are attached due to an error during NFC antenna processing, the conductive member of the upper FPC will adhere to the first feeding point and the second feeding point of the lower FPC, thereby causing a short circuit between the first feeding point and the second feeding point of the lower FPC.

2. The NFC antenna according to claim 1, wherein: The back adhesive layer and the magnetic isolation back adhesive layer are made of acrylic adhesive or double-sided adhesive.

3. The NFC antenna according to claim 1, wherein: The base layer is made of PET or PI material.

4. The NFC antenna according to claim 1, wherein: The conductive member is a metal patch, a metal coil, a metal spring, a metal convex bump, or a conductive adhesive coating area.

5. The NFC antenna according to claim 1, wherein: The conductive member is circular, curved, polygonal or has a special-shaped structure.

6. The NFC antenna according to claim 1, wherein: The first wiring, the second wiring and the metal flying wire are made of copper or silver.

7. The NFC antenna according to claim 1, wherein: Surfaces of the first wiring and the second wiring are covered with ink or adhesive.

8. A terminal, characterized in that: The terminal comprises the NFC antenna according to any one of claims 1 to 7.

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