CN213426791U - Shielding film and circuit board - Google Patents

Abstract

The utility model discloses a shielding film and circuit board, wherein, the shielding film includes: the contrast structure layer comprises a first film layer, a contrast structure layer and an electromagnetic shielding layer; the first film layer is arranged on the first side of the electromagnetic shielding layer; the contrast structure layer is arranged on the first side of the electromagnetic shielding layer; and the gray value of the color of the contrast structure layer is greater than that of the first film layer. The utility model provides a shielding film and circuit board to the realization sets up the identification code on the screen membrane, thereby improves the definition and the resolution ratio of identification code.

Description

Shielding film and circuit board

Technical Field

The utility model relates to the field of electronic technology, especially, relate to a shielding film and circuit board.

Background

With the rapid development of the electronic industry, electronic products are further developed toward miniaturization, light weight and high-density assembly, which greatly promotes the development of flexible circuit boards and gradually realizes the integration of component devices and wire connection. The flexible circuit board can be widely applied to industries such as mobile phones, liquid crystal display, communication, aerospace and the like.

With the integration of various functions of electronic products such as mobile phones, the internal components thereof are becoming high frequency and high speed. For example, in addition to the original audio transmission function, the camera function is an essential function in the mobile phone, and Wireless Local Area Networks (WLAN), Global Positioning System (GPS) and internet access functions are also popular, and in addition, the future sensing components will be gradually integrated, and the trend of rapid high-frequency and high-speed of the internal components of the mobile phone is inevitable.

Among present electronic product, various components and parts have been integrateed to electronic product's inside, for this electronic product of better traceing back or the inside certain components and parts of better traceing back electronic product, often be provided with the identification code in electronic product, through sweeping this identification code of sign indicating number, can carry out electronic product or the information of its inside certain unitary device and trace back. In the prior art, an identification code (for example, a two-dimensional code) is printed on a steel plate, but the size of the steel plate is limited due to the lightness and thinness of an electronic product, so that the two-dimensional code is not easy to print on the steel plate. In the prior art, the identification code can be printed on a soft board of an electronic product in a printing mode, but the printed identification code is not clear due to the small size of the soft board, the accuracy cannot meet the identification requirement, and the condition that the identification code cannot be printed on the soft board with the small size exists.

SUMMERY OF THE UTILITY MODEL

The embodiment of the utility model provides a shielding film and circuit board to the realization sets up the identification code on the shielding film, thereby improves definition and the resolution ratio of identification code.

In a first aspect, an embodiment of the present invention provides a shielding film, including: the contrast structure layer comprises a first film layer, a contrast structure layer and an electromagnetic shielding layer;

the first film layer is arranged on the first side of the electromagnetic shielding layer;

the contrast structure layer is arranged on the first side of the electromagnetic shielding layer;

and the gray value of the color of the contrast structure layer is greater than that of the first film layer.

In a second aspect, an embodiment of the present invention provides a shielding film, including: the contrast structure layer comprises a first film layer, a contrast structure layer and an electromagnetic shielding layer;

the first film layer is arranged on the first side of the electromagnetic shielding layer;

the contrast structure layer is arranged on the first side of the electromagnetic shielding layer;

the gray value of the color of the contrast structure layer is larger than that of the first film layer; and in the comparison structure layer and the first film layer, a layer far away from the electromagnetic shielding layer forms a hollow-out pattern of the identification code.

In a third aspect, an embodiment of the present invention provides a circuit board, where the circuit board includes a printed circuit board and a shielding film provided in any embodiment of the present invention; an adhesive film layer is arranged on one side, away from the first film layer, of the electromagnetic shielding layer of the shielding film;

one side of the adhesive film layer of the shielding film is attached to the printed circuit board.

The utility model discloses in, the shielding film is including the electromagnetic shield layer that is used for shielding electromagnetic interference, the first side of electromagnetic shield layer is provided with first rete and contrast structural layer, can set up first rete between electromagnetic shield layer and contrast structural layer, also can set up the contrast structural layer between electromagnetic shield layer and first rete, the grey scale value of the colour of contrast structural layer needs to be greater than the grey scale value of the colour of first rete for can form comparatively obvious light and shade luminance contrast between contrast structural layer and the first rete. This embodiment can form the fretwork figure of identification code with the one deck far away from the electromagnetic shield layer in contrast structural layer and the first rete for under the contrast of the strong light and shade or the color of contrast structural layer and first rete, the user can acquire the higher identification code of definition, improves the discernment precision and the degree of accuracy to the identification code, is convenient for trace back the components and parts or the electronic product that the identification code was identified.

Drawings

Fig. 1 is a schematic structural diagram of a shielding film according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of another shielding film provided by an embodiment of the present invention;

fig. 3 is a schematic structural diagram of another shielding film provided by an embodiment of the present invention;

fig. 4 is a schematic structural diagram of another shielding film provided by the embodiment of the present invention;

fig. 5 is a schematic structural diagram of another shielding film provided by an embodiment of the present invention;

fig. 6 is a schematic structural diagram of another shielding film provided by an embodiment of the present invention;

fig. 7 is a schematic plan view of an electromagnetic shielding layer according to an embodiment of the present invention;

fig. 8 is a schematic structural diagram of another shielding film provided by an embodiment of the present invention;

fig. 9 is a schematic structural diagram of another shielding film provided by the embodiment of the present invention;

fig. 10 is a schematic structural diagram of another shielding film provided by an embodiment of the present invention;

fig. 11 is a schematic structural diagram of a circuit board according to an embodiment of the present invention;

fig. 12 is a schematic structural diagram of an electronic device according to an embodiment of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.

With the development of flexible circuit boards, an important index for evaluating the performance of flexible circuit boards is Electromagnetic Shielding (EMI Shielding). Electromagnetic interference inside and outside the module caused by high-frequency and high-speed driving, and attenuation, insertion loss and jitter of signals in the transmission process are gradually serious, and common electronic products need to attach a shielding film on a printed circuit board to shield the electromagnetic interference. Combine present identification code because of the difficult condition that sets up of electronic product specification, the embodiment of the utility model provides a creative setting the identification code on the barrier film to improve the definition and the resolution ratio of identification code.

Specifically, the embodiment of the utility model provides a shielding film, include: the contrast structure layer comprises a first film layer, a contrast structure layer and an electromagnetic shielding layer;

the first film layer is arranged on the first side of the electromagnetic shielding layer;

the contrast structure layer is arranged on the first side of the electromagnetic shielding layer;

the gray value of the color of the contrast structure layer is larger than that of the first film layer.

The embodiment of the utility model provides an in, be greater than the grey value of the colour of first rete to the grey value of the colour of contrast structural layer, as long as form behind the identification code, equipment can with colour discernment between them and further processing form clear distinguishable identification code can, it is not limited to what the grey value that the grey value of the colour of contrast structural layer specifically should be greater than the grey value of the colour of first rete.

The embodiment of the utility model provides an in, the shielding film is including the electromagnetic shield layer that is used for shielding electromagnetic interference, the first side of electromagnetic shield layer is provided with first rete and contrast structural layer, can set up first rete between electromagnetic shield layer and contrast structural layer, also can set up the contrast structural layer between electromagnetic shield layer and first rete, the grey scale value of the colour of contrast structural layer needs to be greater than the grey scale value of the colour of first rete for can form comparatively obvious light and shade luminance contrast between contrast structural layer and the first rete. This embodiment can form the fretwork figure of identification code with the one deck far away from the electromagnetic shield layer in contrast structural layer and the first rete for under the contrast of the strong light and shade or the color of contrast structural layer and first rete, the user can acquire the higher identification code of definition, improves the discernment precision and the degree of accuracy to the identification code, is convenient for trace back the components and parts or the electronic product that the identification code was identified.

Above is the core thought of the utility model, will combine the attached drawing in the embodiment of the utility model below, to the technical scheme in the embodiment of the utility model clearly, describe completely. Based on the embodiments in the present invention, under the premise that creative work is not done by ordinary skilled in the art, all other embodiments obtained all belong to the protection scope of the present invention.

Fig. 1 is a schematic structural diagram of a shielding film according to an embodiment of the present invention, as shown in fig. 1, the shielding film includes a first film layer 11, a contrast structure layer 12, and an electromagnetic shielding layer 13. The material of the electromagnetic shielding layer 13 is a conductive material with good shielding performance, which can realize effective electromagnetic interference shielding, and optionally, the material of the electromagnetic shielding layer 13 may be copper, so that while the cost is ensured to be low, the electromagnetic shielding layer has the characteristics of good electrical characteristics, high shielding performance, high transmission quality, good reliability and the like, and certainly, the material of the electromagnetic shielding layer 13 may also be a metal material such as aluminum, silver and the like, which is not limited in this embodiment. Optionally, as shown in fig. 2, fig. 2 is a schematic structural diagram of another shielding film provided in the embodiment of the present invention, the shielding film may further include a glue film layer 14, and the glue film layer 14 is disposed on one side of the electromagnetic shielding layer 13 away from the first film layer 11, and is used for realizing connection between the electromagnetic shielding layer 13 and the circuit board.

The first film layer 11 is used for insulating and supporting the electromagnetic shielding layer 13, and blocking water and oxygen from invading into the electromagnetic shielding layer 13 to a certain extent, the first film layer 11 is preferably black, or a color with gray value closer to black, such as dark blue, etc., and the specific color of the first film layer 11 is not limited in this embodiment. Alternatively, the first film layer 11 may include at least one of epoxy resin, rubber, modified epoxy resin, polyimide, polyurethane resin, acrylic resin, modified acrylic resin, polyester, polyphenylene sulfide, polyethylene glycol phthalate, liquid crystal polymer, and ink, and at least one of the above materials is mixed by adding other materials to form a dark color with a low gray scale value.

Optionally, the color of the first film layer 11 may be black; first rete 11 can include at least one of black polyimide and black printing ink, and black polyimide aqueous vapor separation is effectual, and black printing ink has stronger flame retardant efficiency, and first rete 11 can set up to black polyimide material, also can set up to black printing ink material, and in addition, first rete 11 can include black polyimide and black printing ink simultaneously to the reinforcing is to electromagnetic shield 13's guard action. Optionally, in order to adapt to the thinning trend of electronic products, the thickness range of the first film layer 11 is 0.5 μm to 40 μm, so as to reduce the thickness of the first film layer 11 as much as possible, optionally, the thickness of the first film layer 11 may be 4 μm, and on the premise of having good insulation and protection properties, the first film layer 11 is thinned.

The contrast structure layer 12 is used for forming an obvious color or brightness difference with the first film layer 11, and the gray value of the color of the contrast structure layer 12 is greater than that of the first film layer 11. In the present embodiment, the gray scale parameter is used to convert the color into high-quality gray scale gradient to detect the contrast of the brightness of the contrast structure layer 12 and the first film layer 11. The gray scale uses black tone to represent various colors, that is, black is used as a reference color, and different colors are displayed by black with different saturation. And dividing black and white into 0-255 gray levels. The gray value of white is 255, the gray value of black is 0, in this embodiment, the gray value of the color of the contrast structure layer 12 is defined to be greater than the gray value of the color of the first film layer 11, and preferably, the gray value of the color of the contrast structure layer 12 is defined to be greater than the gray value of the color of the first film layer 11. For example, the color of the contrast structure layer 12 is silver, and the gray value of the silver is larger, so that the silver of the contrast structure layer 12 is clearly contrasted with the dark color of the first film layer 11.

The contrast structure layer 12 and the first film layer 11 are located on the same side of the electromagnetic shielding layer 13, and the arrangement order of the contrast structure layer 12 and the first film layer 11 is variable, for example, as shown in fig. 2, the contrast structure layer 12 may be arranged between the first film layer 11 and the electromagnetic shielding layer 13, or, as shown in fig. 3, fig. 3 is a schematic structural diagram of another shielding film provided by an embodiment of the present invention, and the first film layer 11 may be arranged between the contrast structure layer 12 and the electromagnetic shielding layer 13. As long as the contrasting structural layer 12 and the first film layer 11 are superimposed on each other in sharp contrast. No matter the contrast structure layer 12 and the first film layer 11 are the arrangement sequence in fig. 1 or the arrangement sequence in fig. 3, the layer located at the outermost side is used for forming the hollow-out pattern of the identification code, and the color of the other layer exposed by the hollow-out pattern can form a larger brightness difference with the layer at the outermost side, so that the identification code is clearer, and a user can conveniently and accurately recognize the hollow-out pattern. Specifically, as shown in fig. 2, when the first film layer 11 is disposed on the outermost side, the hollow pattern of the identification code needs to be formed on the first film layer 11, and the hollow pattern of the first film layer 11 exposes the contrast structure layer 12 with a lighter color (higher brightness), so as to form a clearer identification code. As shown in fig. 3, when the contrast structure layer 12 is disposed on the outermost side, the hollow pattern of the identification code needs to be formed on the contrast structure layer 12, and the dark first film layer 11 is exposed from the hollow pattern on the contrast structure layer 12, so as to form a clear identification code. Alternatively, the hollow-out pattern may be formed by laser ablation, for example, the hollow-out pattern may be ablated by using an ultraviolet laser and a carbon dioxide laser.

Optionally, the difference between the gray value of the color of the contrast structure layer 12 and the gray value of the color of the first film layer 11 is greater than or equal to a first gray threshold; if the first gray threshold is greater than or equal to 10, the difference between the gray value of the color of the contrast structure layer 12 and the gray value of the color of the first film layer 11 is at least 10, so that a relatively obvious light-dark difference is formed between the contrast structure layer 12 and the first film layer 11, and the accuracy of the identification code identification device in identifying the identification code formed by the contrast structure layer 12 and the first film layer 11 is improved.

In order to further increase the brightness difference between the contrast structure layer 12 and the first film 11, the first grayscale threshold may be defined as 50, and the difference between the grayscale value of the color of the contrast structure layer 12 and the grayscale value of the color of the first film 11 is at least 50, the color brightness of the contrast structure layer 12 is stronger, and the color brightness of the first film 11 is smaller, so as to further increase the light-dark contrast between the contrast structure layer 12 and the first film 11, and improve the identification precision and accuracy of the identification code.

Based on the above embodiments, in this embodiment, it may be further defined that the first gray threshold is 100, and the difference between the gray value of the color of the contrast structure layer 12 and the gray value of the color of the first film layer 11 is at least 100, for example, if the gray value of the color of the first film layer 11 is 0, and the gray value of the color of the contrast structure layer 12 and the gray value of the color of the first film layer 11 are at least different from 100, even different from 255, the gray value of the contrast structure layer 12 may be greater than or equal to 100. In the case of the difference of the gray values of 255, one of the contrast structure layer 12 and the first film layer 11 is pure black, and the other is pure white, that is, the gray values of the two are 255 and 0, so that the difference of the brightness or the color is large, and the definition of the identification code is further enhanced.

It should be noted that the shielding film in this embodiment is attached to the printed circuit board through the side provided with the adhesive film layer 14, so as to rapidly guide the interference signal generated by the electronic device out of the electromagnetic shielding layer 13 to the ground plate or the ground line of the printed circuit board. Fig. 4 is a schematic structural diagram of another shielding film according to an embodiment of the present invention, and optionally, one side of the electromagnetic shielding layer 13 close to the adhesive film layer 14 may be roughened to form a plurality of coarse protruding structures 131; the protruding structure 131 is used for piercing the grounding end of the adhesive film layer 14 and the printed circuit board and is connected, the protruding structure 131 can realize the connection between the electromagnetic shielding layer 13 and the grounding end, and the protruding structure 131 makes the electromagnetic shielding layer 13 and the adhesive film layer 14 closely attached to each other, avoid the electromagnetic shielding layer 13 and the adhesive film layer 14 to separate, furthermore, when the glue amount of the adhesive film layer 14 is not enough, the separation between the shielding film and the printed circuit board can be generated, when the glue amount of the adhesive film layer 14 is too much, the edge of the printed circuit board is easily caused to generate the glue overflow condition, the setting of the protruding structure 131 in the embodiment makes the shielding film and the printed circuit board pressed together, the glue overflow pushed up by the protruding structure 131 can be extruded to the depressed part of the adhesive film layer 14, the glue containing amount between the electromagnetic shielding layer 13 and the printed circuit board is increased.

It should be noted that, in the production process of the shielding film, the first film layer 11, the contrast structure layer 12, the electromagnetic shielding layer 13, and the adhesive film layer 14 are all disposed on a carrier film, the carrier film supports the film layers, after the first film layer 11, the contrast structure layer 12, and the electromagnetic shielding layer 13 are formed on the carrier film, the electromagnetic shielding layer 13 is roughened to form the protruding structure 131, and the adhesive film layer 14 is pressed onto the protruding structure 131 of the electromagnetic shielding layer 13 to form the base film material of the shielding film. Thereafter, the base film of the shielding film needs to be peeled off from the carrier film, and the hollowed-out pattern of the identification code is formed on the side of the shielding film far away from the adhesive film layer 14 by ablation.

Fig. 5 is a schematic structural diagram of another shielding film according to an embodiment of the present invention, in this embodiment, one side of the electromagnetic shielding layer 13 close to the adhesive film layer 14 may not be selected to be roughened, and optionally, a plurality of conductive particles 141 may be disposed in the adhesive film layer 14; the conductive particles 141 are used to pierce the adhesive film layer 14 to connect the ground terminal of the printed circuit board and the electromagnetic shielding layer 13. Comparing fig. 4, the inside of the adhesive film layer 14 shown in fig. 5 includes a plurality of conductive particles 141, the conductive particles 141 are agglomerated to form larger particles, and the larger particles can pierce through the adhesive film layer 14 to connect the grounding end of the printed circuit board and the electromagnetic shielding layer 13, so that the embodiment can tightly attach the adhesive film layer 14 and the electromagnetic shielding layer 13 without roughening the electromagnetic shielding layer 13 during the manufacturing process, thereby forming a basic film material of the shielding film.

In addition, also can be earlier to electromagnetic shield layer 13 be close to the one side of glued membrane layer 14 and form the glued membrane layer 14 that has conductive particle 141 after the protruding structure through the alligatoring processing, as shown in fig. 6, fig. 6 is the structural schematic diagram of another kind of shielding film that the embodiment provides, when this embodiment can form protruding structure 131 with the alligatoring processing on the electromagnetic shield layer 13, be provided with a plurality of conductive particle 141 in glued membrane layer 14, conductive particle 141 can pierce through glued membrane layer 14 and protruding structure 131 electricity and be connected to further strengthen the conductivity of electromagnetic shield layer 14 and circuit board stratum, and solve the problem of the shielding film that current causes because of the volume of glue is not enough and circuit board layering.

Optionally, as shown in fig. 7, fig. 7 is a planar structure schematic diagram of an electromagnetic shielding layer that the embodiment of the utility model provides, electromagnetic shielding layer 13 is equipped with a plurality of through-holes 132, be favorable to the volatile matter of tunica mucosa at the high temperature to exhaust through-hole 132 of electromagnetic shielding layer 13, in order to avoid tunica mucosa volatiles to be difficult to discharge when the high temperature, thereby avoided electromagnetic shielding layer 13 to bubble the layering and led to the fact to peel off between the stratum of electromagnetic shielding film and circuit board, and then ensured electromagnetic shielding film ground connection and derive the interference electric charge.

Alternatively, the through holes 132 may be regularly or irregularly distributed on the electromagnetic shielding layer 13; as shown in fig. 7, the through holes 132 are regularly distributed on the electromagnetic shielding layer 13, which means that the through holes 132 have the same shape and are uniformly distributed on the electromagnetic shielding layer 13; the through holes 132 are irregularly distributed on the electromagnetic shielding layer 13, which means that the shapes of the through holes 132 are different and are irregularly distributed on the electromagnetic shielding layer 13. Preferably, as shown in fig. 7, the through holes 132 have the same shape, and the through holes 132 are uniformly distributed on the electromagnetic shielding layer 13. In addition, the through hole 132 may be a circular through hole, or may be a through hole of any other shape, and fig. 7 only illustrates that the through hole 132 is a circular through hole, but the through hole 132 of any other shape is within the scope of the embodiments of the present invention.

The shielding films will be described in detail below in two types according to the arrangement order of the first film layer 11 and the comparative structure layer 12:

first, with continued reference to fig. 3, in this embodiment, optionally, the contrast structure layer 12 may be disposed on a side of the first film layer 11 away from the electromagnetic shielding layer 13; the contrast structure layer 12 forms hollow patterns of the identification codes. As shown in fig. 3, the material of the contrast structure layer 12 in this embodiment may be a metal, the gray value of the color of the metal is greater than the gray value of the color of the first film layer 11, and the difference is preferably greater than or equal to 10. It should be noted that the metal layer may include at least one of a simple metal and a metal alloy, which is not limited in this embodiment. When contrast structural layer 12 is the metal level, after the user formed the fretwork pattern on the metal level, optionally, set up one side insulating film in the metal level and kept away from electromagnetic shield layer 13, and be formed with the opening in the position that this insulating film corresponds with the fretwork pattern of identification code to expose the identification code and supply the user to discern, thereby prevent that the condition of short circuit from appearing in metal level and the contact of outside electronic components. In addition, if the insulating film is a colorless and transparent insulating film, the insulating film may not have the opening, and the identification code can be exposed for the user to recognize.

In addition, optionally, the contrast structure layer 12 may be a glue layer or an ink layer with a gray value greater than that of the first film layer 11. When the electromagnetic shielding layer 13 is protected, the clear identification code is formed by comparing the structural layer 12 and the first film layer 11 exposed by the hollow pattern. In this embodiment, the adhesive layer may be a thermosetting adhesive.

Alternatively, the contrast structure layer 12 may be a white glue layer or a white ink layer. In this embodiment, the contrast structure layer 12 is a white glue layer or a white ink layer, the gray value of the color of the contrast structure layer 12 is 255, the color of the first film layer 11 is preferably black, the gray value of the color of the first film layer 11 is 0, the contrast between black and white is strong, and a clearer identification code is easily formed. In addition, the adhesive layer or the ink layer may also be other colors with higher gray value, such as gray, yellow, and the like, which is not limited in this embodiment.

Secondly, with continued reference to fig. 2, optionally, the first film layer 11 may be disposed on a side of the contrast structure layer 12 away from the electromagnetic shielding layer 13; the first film layer 11 forms a hollow pattern of the identification code. Optionally, the contrast structure layer 12 may be a glue layer or an ink layer, and the gray scale value of the color of the glue layer or the ink layer is greater than the gray scale value of the color of the first film layer 11, and the gray scale value of the color of the glue layer or the ink layer is preferably greater than or equal to 160.

Optionally, the contrast structure layer 12 may be a white or colorless glue layer; alternatively, the contrast structure layer 12 is a white ink layer. The material of the contrast structure layer 12 may be selected from at least one of modified epoxy resin, modified acrylic, modified rubber, modified thermoplastic polyimide, modified polyester, thermoplastic resin, thermosetting resin, and sub-sensitive adhesive. In this embodiment, the contrast structure layer 12 is a white glue layer or a white ink layer, the gray value of the color of the contrast structure layer 12 is 255, the gray value of the color of the first film layer 11 is preferably 0, the contrast between black and white is stronger, and a clearer identification code is easily formed. In addition, the adhesive layer or the ink layer may also be other colors with higher gray value, such as gray, yellow, and the like, which is not limited in this embodiment. It should be noted that, when the contrast structure layer 12 is disposed between the first film layer 11 and the electromagnetic shielding layer 13, the contrast structure layer 12 may be a colorless glue layer, and the colorless glue layer effectively protects the electromagnetic shielding layer 13 and prevents the electromagnetic shielding layer 13 from being exposed in the hollow pattern. And contrast structural layer 12 is colourless, so electromagnetic shield layer 13 exposes through the fretwork figure, and the black of first rete 11 forms the contrast with electromagnetic shield layer 13's colour equally, forms comparatively clear identification code, and if electromagnetic shield layer 13 chooses for use the material for use to be copper, then electromagnetic shield layer 13's colour is the red copper colour, distinguishes easily between red copper colour and the black, effectively protects copper through colourless contrast structural layer 12, prevents to expose in the air by oxidation and makes follow-up and first rete 11 between the colour be difficult to distinguish.

Optionally, the contrast structure layer 12 may also be a metal layer. The grey value of the color of the metal is greater than the grey value of the color of the first film layer 11 and preferably greater than or equal to 10.

Optionally, the material of the comparative structure layer 12 is at least one simple substance of nickel, silver, platinum, titanium, aluminum, cobalt and chromium; or the material of the contrast structure layer is an alloy formed by at least two of nickel, silver, platinum, titanium, aluminum, cobalt and chromium; alternatively, the material of the contrast structure layer is a combination of alloys formed by at least two of nickel, silver, platinum, titanium, aluminum, cobalt and chromium. It will be readily appreciated that the identification code is more clearly black and white, and therefore the metallic material of the contrasting structural layer 12 needs to be light enough, preferably silver or silvery white. In this embodiment, at least one simple substance of nickel, silver, platinum, titanium, aluminum, cobalt, and chromium, or an alloy formed by at least two of nickel, silver, platinum, titanium, aluminum, cobalt, and chromium is selected to form the comparative structure layer 12, or the material of the comparative structure layer is a combination of alloys formed by at least two of nickel, silver, platinum, titanium, aluminum, cobalt, and chromium. The above materials are all white, silver or a color close to silver, and for example, nickel may be selected as the material of the contrast structure layer 12 in this embodiment, or nichrome may be selected as the material of the contrast structure layer 12. In addition, the contrast structure layer 12 may also be other light-colored metals with lower gray-scale values, which is not limited in this embodiment.

Fig. 8 is a schematic structural diagram of another shielding film provided in the embodiment of the present invention, and optionally, the comparative structural layer 12 may include a first metal layer 121 and a second metal layer 122; the first metal layer 121 is formed on one side of the first film layer 11 close to the electromagnetic shielding layer 13 by a sputtering process; the second metal layer 122 is formed on the side of the first metal layer 121 far from the first film layer 11 by an electroplating process.

In addition to the gray value limitation, the present embodiment also has certain requirements on the flatness of the contrast structure layer 12. Because the surface of the contrast structure layer 12 is rougher, the light on the surface of the contrast structure layer 12 is darker and darker, and the resolution between the contrast structure layer and the first film layer 11 is reduced, the contrast structure layer 12 can be divided into two layers in the present embodiment, that is, a first metal layer 121 is formed on the first film layer 11 through a sputtering process, the sputtering process forms a dense and flat metal surface, which is convenient for forming contrast with the first film layer 11, and then a second metal layer 122 is formed on the flat first metal layer 121 through an electroplating process. Optionally, the thickness of the first metal layer 121 may be in the range

The thickness of the second metal layer 122 may range from 0.1 μm to 10 μm. Alternatively, if the thickness of the second metal layer 122 is in the range of 0.2 μm to 0.4 μm, the resistance of the second metal layer 122 per unit area (1cmx1cm) may be set in the range of 15m Ω to 200m Ω, and preferably, may be set at 30m Ω.

In addition, in addition to the sputtering process, the first metal layer 121 may also be formed by another process, for example, one or more processes of electroless plating, physical vapor deposition, chemical vapor deposition, evaporation plating, sputtering plating, electroplating and hybrid plating, the process for forming the first metal layer 121 is not limited in this embodiment, and optionally, the sputtering process is preferably used for the first metal layer 121.

In the embodiment shown in fig. 8, when the identification code is to be formed by ablation, the laser energy forms a hollowed pattern on the first film layer, so that the color of the first metal layer 121 is exposed, and therefore the gray scale value corresponding to the color of the first metal layer 121 is preferably lower than the gray scale value corresponding to the color of the second metal layer 122, for example, the first metal layer 121 may be selected to be Ag, and the second metal layer 122 may be selected to be Ni.

Fig. 9 is a schematic structural diagram of another shielding film provided in an embodiment of the present invention, and optionally, the first metal layer may include a first sputtered metal layer 1211 and a second sputtered metal layer 1212; the first sputtered metal layer 1211 is disposed between the first film layer 11 and the second sputtered metal layer 1212; the gray scale value of the color of the first sputtered metal layer 1211 is greater than the gray scale value of the color of the second sputtered metal layer 1212.

In this embodiment, two sputtered metal layers may be provided, because when the first film 11 is actually ablated to form the hollow pattern of the identification code, the laser energy may possibly punch through the first sputtered metal layer 1211, and then the guarantee may be increased by the second sputtered metal layer 1212, so as to keep the sputtered metal layer with higher flatness exposed by the hollow pattern. In addition, the gray scale value of the color of the first sputtered metal layer 1211 can be set to be greater than the gray scale value of the color of the second sputtered metal layer 1212, for example, if the first sputtered metal layer 1211 is silver and the second sputtered metal layer 1212 is nickel, the metal surface of silver can form a sharp color contrast with the dark first film layer 11, thereby improving the definition of the identification code.

Fig. 10 is a schematic structural diagram of another shielding film provided in the embodiment of the present invention, and optionally, the comparative structural layer 12 may further include a second film layer 15; the second film layer 15 is disposed between the first film layer 11 and the first metal layer 121; the difference value between the gray value of the color of the second film layer 15 and the gray value of the color of the first film layer 11 is greater than or equal to a first gray threshold value; the first grayscale threshold is greater than or equal to 10. The second film layer 15 is disposed between the first film layer 11 and the first metal layer 121, and when the first metal layer 121 includes the first sputtered metal layer and the second sputtered metal layer, the second film layer 15 is disposed between the first film layer 11 and the first sputtered metal layer, so as to further enhance protection of the first metal layer 121. The gray value of the color of the second film layer 15 also needs to be greater than the gray value of the first film layer 11, and the difference between the gray value of the second film layer 15 and the gray value of the color of the first film layer 11 is preferably greater than or equal to the first gray threshold; the first grayscale threshold is greater than or equal to 10. The difference value between the gray value of the color of the second film layer 15 and the gray value of the color of the first film layer 11 is at least 10, so that a relatively obvious light and shade difference is formed between the second film layer 15 and the first film layer 11, and the accuracy of the identification code identification device for identifying the identification code formed by the second film layer 15 and the first film layer 11 is improved. Preferably, the first grayscale threshold may be 50 or 100, and the contrast between the second film layer 15 and the first film layer 11 may be further increased, so as to improve the identification precision and accuracy of the identification code. Optionally, the second film layer 15 may be white or colorless; the thickness of the second film layer 15 may range from 0.5 μm to 30 μm. The white second film layer 15 is stronger in contrast with the dark first film layer 11, and a clearer identification code is easily formed. And the second film layer 15 may be colorless, so that the color of the first metal layer 121 can be exposed by the hollow pattern through the second film layer 15.

On the basis of the above embodiment, the embodiment of the present invention further provides a shielding film, with continued reference to fig. 1, including: a first film layer 11, a contrast structure layer 12 and an electromagnetic shielding layer 13;

the first film layer 11 is arranged on a first side of the electromagnetic shielding layer 13;

the contrast structure layer 12 is arranged on a first side of the electromagnetic shielding layer 13;

wherein, the gray value of the color of the contrast structure layer 12 is greater than the gray value of the color of the first film layer 11; comparing the structural layer 12 and the first film layer 11, the layer far away from the electromagnetic shielding layer 13 forms a hollow pattern of the identification code.

The embodiment of the utility model provides an in, the shielding film is including the electromagnetic shield layer that is used for shielding electromagnetic interference, the first side of electromagnetic shield layer is provided with first rete and contrast structural layer, can set up first rete between electromagnetic shield layer and contrast structural layer, also can set up the contrast structural layer between electromagnetic shield layer and first rete, the grey scale value of the colour of contrast structural layer needs to be greater than the grey scale value of the colour of first rete for can form comparatively obvious light and shade luminance contrast between contrast structural layer and the first rete. This embodiment will contrast the one deck far away from the electromagnetic shield layer in structural layer and the first rete and form the fretwork figure of identification code for under the contrast of the strong light and shade or the color of structural layer and first rete of contrast, the user can acquire the higher identification code of definition, improves the discernment precision and the degree of accuracy to the identification code, is convenient for trace back the components and parts or the electronic product that the identification code was identified.

Alternatively, the identification code may include at least one of a bar code, a two-dimensional code, and a character. The identification code is a unique corresponding identification mark for identifying the component or the electronic product. The identification code may include figures of characters such as numbers and letters, and may also be a bar code or a two-dimensional code, and the shielding film of the embodiment may include at least one of the bar code, the two-dimensional code, and the characters, so as to identify a corresponding component or an electronic product. For example, the shielding film needs to be attached to a printed circuit board of the electronic device, and the identification code of the component may be set at a position of the shielding film corresponding to the component. A plurality of identification codes and a plurality of components can be arranged on the shielding film in a one-to-one correspondence mode, so that the problem that printed identification codes are not clear due to the fact that the identification codes are arranged on steel plates with insufficient sizes of electronic products is solved, and the resolution and the identification accuracy of the identification codes are effectively improved. Optionally, the hollowed-out pattern is formed by laser ablation. For example, ablation of the hollowed-out pattern may be performed using an ultraviolet laser and a carbon dioxide laser.

It should be noted that when the hollow pattern is ablated, there may be two situations:

first, only burn through the layer far away from the electromagnetic shielding layer 13 in the contrast structure layer 12 and the first film layer 11 to form the hollow pattern of the identification code, and not ablate the layer near the electromagnetic shielding layer 13, that is, the ablation depth of the hollow pattern is: comparing the thickness of the structural layer 12 and the layer farther from the electromagnetic shield layer 13 in the first film layer 11. The hollowed pattern just exposes a layer of structure which is not etched and is close to the electromagnetic shielding layer 13, and the identification code is formed by comparing the structural layer 12 and the first film layer 11.

Secondly, when the layer farther from the electromagnetic shielding layer 13 in the contrast structure layer 12 and the first film layer 11 is burned through to form the hollow pattern of the identification code, the layer closer to the electromagnetic shielding layer 13 may be partially ablated. In this embodiment, the layer closer to the electromagnetic shielding layer 13 is partially ablated but not completely ablated, and after the identification code is ablated, the hollowed-out pattern can expose the layer closer to the electromagnetic shielding layer 13 in the contrast structure layer 12 and the first film layer 11, so that the contrast structure layer 12 and the first film layer 11 form the identification code. Specifically, a groove pattern is formed on one layer of the contrast structure layer 12 and the first film layer 11, which is closer to the electromagnetic shielding layer 13; the vertical projection of the hollow pattern on the plane of the electromagnetic shielding layer is completely superposed with the groove pattern. And (3) partially ablating a layer, which is closer to the electromagnetic shielding layer 13, in the contrast structure layer 12 and the first film layer 11 to form a groove pattern, wherein the groove pattern and the hollow pattern are formed by the same process, so that the vertical projection of the hollow pattern on the plane of the electromagnetic shielding layer is completely superposed with the groove pattern.

Alternatively, with continued reference to fig. 3, the contrast structure layer 12 may be disposed on a side of the first film layer 11 away from the electromagnetic shielding layer 13; the contrast structure layer 12 forms hollow patterns of the identification codes. In the embodiment, when the comparison structure layer 12 is ablated to form the hollow-out pattern of the identification code, only the comparison structure layer 12 can be ablated, and the first film layer 11 is not ablated; or when the ablation contrast structure layer 12 forms the hollow-out pattern of the identification code, the first film layer 11 can be partially ablated to form a groove pattern, and the vertical projection of the hollow-out pattern on the plane where the electromagnetic shielding layer is located completely coincides with the groove pattern.

As shown in fig. 3, the material of the contrast structure layer 12 in this embodiment may be a metal, the gray value of the color of the metal is greater than the gray value of the color of the first film layer 11, and the difference between the gray value of the color of the metal and the gray value of the color of the first film layer 11 is preferably greater than or equal to 10.

Alternatively, the contrast structure layer 12 may be a glue layer or an ink layer. The contrast structure layer 12 may be a glue layer or an ink layer with a gray value greater than that of the first film layer 11. When the electromagnetic shielding layer 13 is protected, the clear identification code is formed by comparing the structural layer 12 and the first film layer 11 exposed by the hollow pattern. In this embodiment, the adhesive layer may be a thermosetting adhesive.

Alternatively, the contrast structure layer 12 may be a white glue layer or a white ink layer. In this embodiment, the contrast structure layer 12 is a white glue layer or a white ink layer, the gray value of the color of the contrast structure layer 12 is 255, the color of the first film layer 11 is preferably black, the gray value of the color of the first film layer 11 is 0, the contrast between black and white is strong, and a clearer identification code is easily formed. In addition, the adhesive layer or the ink layer may also be other colors with higher gray value, such as gray, yellow, and the like, which is not limited in this embodiment.

Optionally, with continued reference to fig. 1, the first film layer 11 may also be disposed on a side of the contrast structure layer 12 away from the electromagnetic shielding layer 13; the first film layer 11 forms a hollow pattern of the identification code. In the embodiment, when the first film layer 11 is ablated to form the hollow-out pattern of the identification code, only the first film layer 11 can be ablated, and the contrast structure layer 12 is not ablated; or when the first film layer 11 is ablated to form the hollow-out pattern of the identification code, the contrast structure layer 12 can be partially ablated to form a groove pattern, and the vertical projection of the hollow-out pattern on the plane of the electromagnetic shielding layer is completely overlapped with the groove pattern. Optionally, the contrast structure layer 12 may be one or a combination of two or more of a glue layer, an ink layer, and a metal layer.

Optionally, the contrast structure layer 12 may be an adhesive layer or an ink layer, and the gray scale value of the color of the adhesive layer or the ink layer is greater than the gray scale value of the color of the first film layer 11, and the difference between the gray scale value of the color of the adhesive layer or the ink layer and the gray scale value of the color of the first film layer 11 is preferably greater than or equal to 10. Optionally, the contrast structure layer 12 may be a white or colorless glue layer; alternatively, the contrast structure layer 12 is a white ink layer. The material of the contrast structure layer 12 may be selected from at least one of modified epoxy resin, modified acrylic, modified rubber, modified thermoplastic polyimide, modified polyester, thermoplastic resin, thermosetting resin, and sub-sensitive adhesive. In this embodiment, the contrast structure layer 12 is a white glue layer or a white ink layer, the gray value of the color of the contrast structure layer 12 is 255, the gray value of the color of the first film layer 11 is preferably 0, the contrast between black and white is stronger, and a clearer identification code is easily formed. In addition, the adhesive layer or the ink layer may also be a color with a lower gray value, such as gray, yellow, etc., which is not limited in this embodiment. It should be noted that, when the contrast structure layer 12 is disposed between the first film layer 11 and the electromagnetic shielding layer 13, the contrast structure layer 12 may be a colorless glue layer, and the colorless glue layer effectively protects the electromagnetic shielding layer 13 and prevents the electromagnetic shielding layer 13 from being exposed in the hollow pattern. And contrast structural layer 12 is colourless, so electromagnetic shield layer 13 exposes through the fretwork figure, and the black of first rete 11 forms the contrast with electromagnetic shield layer 13's colour equally, forms comparatively clear identification code, and if electromagnetic shield layer 13 chooses for use the material for use to be copper, then electromagnetic shield layer 13's colour is the red copper colour, distinguishes easily between red copper colour and the black, effectively protects copper through colourless contrast structural layer 12, prevents to be oxidized in exposing the air and make follow-up and first rete 11 between the colour be difficult to distinguish.

Optionally, the contrast structure layer 12 may also be a metal layer. The grey value of the color of the metal is greater than the grey value of the color of the first film layer 11 and the difference is preferably greater than or equal to 10. Optionally, the material of the comparative structure layer 12 is at least one simple substance of nickel, silver, platinum, titanium, aluminum, cobalt and chromium; or the material of the contrast structure layer is an alloy formed by at least two of nickel, silver, platinum, titanium, aluminum, cobalt and chromium; alternatively, the material of the contrast structure layer is a combination of alloys formed by at least two of nickel, silver, platinum, titanium, aluminum, cobalt and chromium. It will be readily appreciated that the identification code is more clearly black and white, and therefore the metallic material of the contrasting structural layer 12 needs to be light enough, preferably silver or silvery white. In this embodiment, at least one simple substance of nickel, silver, platinum, titanium, aluminum, cobalt, and chromium, or an alloy formed by at least two of nickel, silver, platinum, titanium, aluminum, cobalt, and chromium is selected to form the comparative structure layer 12, or the material of the comparative structure layer is a combination of alloys formed by at least two of nickel, silver, platinum, titanium, aluminum, cobalt, and chromium. The above materials are all white, silver or a color close to silver, and for example, nickel may be selected as the material of the contrast structure layer 12 in this embodiment, or nichrome may be selected as the material of the contrast structure layer 12. In addition, the contrast structure layer 12 may also be other light-colored metals with lower gray-scale values, which is not limited in this embodiment.

Optionally, the contrast structure layer 12 may include a first metal layer 121 and a second metal layer 122; the first metal layer 121 is formed on one side of the first film layer 11 close to the electromagnetic shielding layer 13 by a sputtering process; the second metal layer 122 is formed on the side of the first metal layer 121 far from the first film layer 11 by an electroplating process.

In addition to the gray value limitation, the present embodiment also has certain requirements on the flatness of the contrast structure layer 12. Because the surface of the contrast structure layer 12 is rougher, the light on the surface of the contrast structure layer 12 is darker and darker, and the resolution between the contrast structure layer and the first film layer 11 is reduced, the contrast structure layer 12 can be divided into two layers in the present embodiment, that is, a first metal layer 121 is formed on the first film layer 11 through a sputtering process, the sputtering process forms a dense and flat metal surface, which is convenient for forming contrast with the first film layer 11, and then a second metal layer 122 is formed on the flat first metal layer 121 through an electroplating process. Optionally, the thickness of the first metal layer 121 may be in the range

The thickness of the second metal layer 122 may range from 0.1 μm to 10 μm. Alternatively, if the thickness of the second metal layer 122 is in the range of 0.2 μm to 0.4 μm, the resistance of the second metal layer 122 per unit area (1cmx1cm) may be set in the range of 15m Ω to 200m Ω, and preferably, may be set at 30m Ω.

In the embodiment shown in fig. 7, when the identification code is to be ablated, the laser energy forms a hollowed pattern on the first film layer, thereby exposing the color of the first metal layer, so that the gray value corresponding to the color of the first metal layer is preferably lower than the gray value corresponding to the color of the second metal layer, for example, the first metal layer may be selected to be Ag and the second metal layer may be selected to be Ni.

As shown in fig. 9, optionally, the first metal layer may include a first sputtered metal layer 1211 and a second sputtered metal layer 1212; the first sputtered metal layer 1211 is disposed between the first film layer 11 and the second sputtered metal layer 1212; the gray scale value of the color of the first sputtered metal layer 1211 is greater than the gray scale value of the color of the second sputtered metal layer 1212.

In this embodiment, two sputtered metal layers may be provided, because when the first film 11 is actually ablated to form the hollow pattern of the identification code, the laser energy may possibly punch through the first sputtered metal layer 1211, and then the guarantee may be increased by the second sputtered metal layer 1212, so as to keep the sputtered metal layer with higher flatness exposed by the hollow pattern. In addition, the gray scale value of the color of the first sputtered metal layer 1211 can be set to be greater than the gray scale value of the color of the second sputtered metal layer 1212, for example, if the first sputtered metal layer 1211 is silver and the second sputtered metal layer 1212 is nickel, the metal surface of silver can form a sharp color contrast with the dark first film layer 11, thereby improving the definition of the identification code.

Based on the same concept, the embodiment of the present invention further provides a circuit board, as shown in fig. 11, fig. 11 is a schematic structural diagram of the circuit board provided by the embodiment of the present invention, and the circuit board includes a printed circuit board 2 and a shielding film 1 provided by any embodiment of the present invention; an adhesive film layer is arranged on one side, away from the first film layer, of the electromagnetic shielding layer of the shielding film 1; one side of the adhesive film layer of the shielding film 1 is attached to the printed circuit board 2. This embodiment circuit board includes the utility model discloses the technical characteristic of the barrier film that arbitrary embodiment provided possesses the utility model discloses the beneficial effect of the barrier film that arbitrary embodiment provided.

The printed circuit board 2 is integrated with a plurality of components with different functions, and the positions of the shielding films 1 corresponding to the components in the embodiment can be provided with identification codes of the components. The shielding film 1 may cover the printed circuit board in a whole layer for realizing electromagnetic shielding in the whole layer, and the shielding film 1 may also include a plurality of sub-shielding films with smaller sizes, where each sub-shielding film is used to cover a corresponding area of the printed circuit board, and this embodiment does not limit this. In addition, the identification code of the electronic device where the circuit board is located may also be provided on the shielding film 1, and for example, the identification code of the electronic device may be provided in the edge area of the shielding film 1.

The embodiment of the utility model provides a still provide an electronic equipment. Fig. 12 is a schematic structural diagram of an electronic device according to an embodiment of the present invention, as shown in fig. 12, an embodiment of the present invention provides an electronic device including the circuit board 3 according to any embodiment of the present invention. The electronic device may be a mobile phone as shown in fig. 12, or may be a computer, a television, an intelligent wearable device, and the like, which is not particularly limited in this embodiment.

It should be noted that the foregoing is only a preferred embodiment of the present invention and the technical principles applied. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail with reference to the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the scope of the present invention.

Claims (26)

1. A shielding film, comprising: the contrast structure layer comprises a first film layer, a contrast structure layer and an electromagnetic shielding layer;

the first film layer is arranged on the first side of the electromagnetic shielding layer;

the contrast structure layer is arranged on the first side of the electromagnetic shielding layer;

and the gray value of the color of the contrast structure layer is greater than that of the first film layer.

2. The shielding film of claim 1, further comprising: a glue film layer;

the adhesive film layer is arranged on one side, far away from the first film layer, of the electromagnetic shielding layer.

3. The shielding film of claim 1,

the thickness range of the first film layer is 0.5-40 μm.

4. The shielding film of claim 1, wherein a difference between a gray scale value of a color of the contrast structure layer and a gray scale value of a color of the first film layer is greater than or equal to a first gray scale threshold value, the first gray scale threshold value being greater than or equal to 10.

5. The shielding film of claim 4, wherein the first grayscale threshold is 50.

6. The shielding film of claim 4, wherein the first grayscale threshold is 100.

7. The shielding film of claim 1, wherein the contrast structure layer is disposed on a side of the first film layer away from the electromagnetic shielding layer.

8. The shielding film of claim 7, wherein the contrast structure layer is a glue layer or an ink layer.

9. The shielding film of claim 8, wherein the contrast structure layer is a white glue layer or a white ink layer.

10. The shielding film of claim 1, wherein the first film layer is disposed on a side of the contrast structure layer away from the electromagnetic shielding layer.

11. The shielding film of claim 10, wherein the contrast structure layer is a glue layer or an ink layer.

12. The shielding film of claim 11, wherein the contrast structure layer is a white or colorless glue layer; or, the contrast structure layer is a white ink layer.

13. The shielding film of claim 7 or 10, wherein the contrast structure layer is a metal layer.

14. The shielding film of claim 13, wherein the contrast structure layer comprises at least two metal layers.

15. The shielding film of claim 13, wherein the contrast structure layer further comprises: a second film layer; the second film layer is arranged between the first film layer and the metal layer;

the difference value between the gray value of the color of the second film layer and the gray value of the color of the first film layer is greater than or equal to a first gray threshold value; the first grayscale threshold is greater than or equal to 10.

16. The shielding film of claim 15, wherein the second film layer is white or colorless; the thickness range of the second film layer is 0.5-30 mu m.

17. The shielding film of claim 2, wherein a plurality of protruding structures are formed on one side of the electromagnetic shielding layer close to the adhesive film layer by roughening treatment;

the protruding structure is used for penetrating the adhesive film layer and is connected with the grounding end of the printed circuit board.

18. The shielding film of claim 2 or 17, wherein a plurality of conductive particles are disposed within the glue film layer;

the conductive particles are used for penetrating the adhesive film layer so as to connect the grounding end of the printed circuit board and the electromagnetic shielding layer.

19. The shielding film of claim 1, wherein the electromagnetic shielding layer is provided with a plurality of through holes.

20. A shielding film, comprising: the contrast structure layer comprises a first film layer, a contrast structure layer and an electromagnetic shielding layer;

the first film layer is arranged on the first side of the electromagnetic shielding layer;

the contrast structure layer is arranged on the first side of the electromagnetic shielding layer;

the gray value of the color of the contrast structure layer is larger than that of the first film layer; and in the comparison structure layer and the first film layer, a layer far away from the electromagnetic shielding layer forms a hollow-out pattern of the identification code.

21. The shielding film of claim 20, wherein a layer of the contrast structure layer and the first film layer closer to the electromagnetic shielding layer forms a groove pattern; and the vertical projection of the hollow pattern on the plane of the electromagnetic shielding layer is completely superposed with the groove pattern.

22. The shielding film of claim 20 or 21, wherein the contrast structure layer is disposed on a side of the first film layer away from the electromagnetic shielding layer; the contrast structure layer forms a hollow-out pattern of the identification code.

23. The shielding film of claim 22, wherein the contrast structure layer is a glue or ink layer.

24. The shielding film of claim 20 or 21, wherein the first film layer is disposed on a side of the contrast structure layer away from the electromagnetic shielding layer; the first film layer forms a hollow pattern of the identification code.

25. The shielding film of claim 24, wherein the contrast structure layer is one or a combination of two or more of a glue layer, an ink layer and a metal layer.

26. A circuit board, comprising: a printed circuit board and the shielding film of any one of claims 1-25; an adhesive film layer is arranged on one side, away from the first film layer, of the electromagnetic shielding layer of the shielding film;

one side of the adhesive film layer of the shielding film is attached to the printed circuit board.

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