CN114650719A - Electromagnetic shielding film and circuit board - Google Patents

Abstract

The invention relates to the technical field of electronics, and discloses an electromagnetic shielding film and a circuit board, wherein the electromagnetic shielding film comprises a shielding layer and an adhesive film layer; the adhesive film layer is arranged on one surface of the shielding layer; wherein, under the condition that the unit of the roughness Rz is micrometer and the unit of the rubber gram weight parameter is gram per square decimeter, the ratio of the roughness Rz of one surface of the shielding layer close to the rubber film layer to the rubber gram weight parameter of the rubber film layer is 2-300. The electromagnetic shielding film and the circuit board provided by the invention have the following advantages at the same time: good shielding effectiveness, good bonding strength with the circuit board and good appearance of the circuit board after being pressed on the circuit board.

Description

Electromagnetic shielding film and circuit board

Technical Field

The invention relates to the technical field of electronics, in particular to an electromagnetic shielding film and a circuit board.

Background

With the rapid development of the electronic industry, electronic products are further miniaturized, light-weighted, and high-density assembled, which greatly promotes the development of flexible circuit boards, thereby realizing the integration of component devices and wire connections. The flexible circuit board can be widely applied to industries such as mobile phones, liquid crystal display, communication, aerospace and the like.

Under the push of the international market, the functional flexible printed circuit board is dominant in the flexible printed circuit board market, and an important index for evaluating the performance of the functional flexible printed circuit board is Electromagnetic Shielding (EMI Shielding). With the integration of the functions of communication equipment such as mobile phones, the internal components thereof are rapidly high-frequency and high-speed. For example: besides the original audio transmission function, the camera function has become a necessary function, and WLAN (Wireless Local Area network), GPS (Global Positioning System) and internet function have become popular, and the integration of the sensing component in the future makes the trend of rapid high-frequency and high-speed of the component unavoidable. Problems of electromagnetic interference inside and outside the device, signal attenuation during transmission, insertion loss, and jitter caused by high-frequency and high-speed driving are becoming serious.

At present, an electromagnetic shielding film commonly used for an existing circuit board comprises a shielding layer and an adhesive film layer, wherein one surface of the shielding layer, which is close to the adhesive film layer, has roughness and can pierce the adhesive film layer to be in contact connection with a stratum of the circuit board, so that interference charges are led into the stratum of the circuit board, and shielding is achieved.

The inventor finds that the following technical problems exist in the prior art in the process of implementing the invention: in the process of laminating the existing electromagnetic shielding film on the circuit board, in order to enable the roughness of one surface of the shielding layer close to the adhesive film layer to effectively pierce the adhesive film layer and contact and connect with the ground layer of the circuit board, a larger laminating force is often required to be applied, and the adhesive of the adhesive film layer is easy to overflow from the edge between the electromagnetic shielding film and the circuit board in the process, so that the circuit board has the problem of poor appearance; in order to avoid that the glue of the glue film layer easily overflows from the edge between the electromagnetic shielding film and the circuit board in the laminating process of the electromagnetic shielding film, the glue amount of the glue film layer can be reduced or smaller laminating force is applied, but the two modes can cause the phenomenon of layering and board explosion between the electromagnetic shielding film and the circuit board easily, especially under the condition that the thickness of the glue film layer is not reduced, the smaller laminating force applied to the electromagnetic shielding film can possibly cause the shielding layer not to effectively puncture the glue film layer, so that the shielding layer cannot be in contact connection with the stratum of the circuit board, and the shielding effectiveness of the electromagnetic shielding film is lower. Therefore, the existing electromagnetic shielding film cannot have the following advantages at the same time: good shielding effectiveness, good bonding strength with the circuit board and good appearance of the circuit board after being pressed on the circuit board.

Disclosure of Invention

In view of the above problems, an object of the present invention is to provide an electromagnetic shielding film and a circuit board, which can simultaneously have the following advantages: good shielding effectiveness, good bonding strength with the circuit board and good appearance of the circuit board after being pressed on the circuit board.

In order to achieve the above object, an embodiment of the present invention provides an electromagnetic shielding film, including a shielding layer and a glue film layer;

the adhesive film layer is arranged on one surface of the shielding layer;

wherein, under the condition that the unit of the roughness Rz is micrometer and the unit of the rubber gram weight parameter is gram per square decimeter, the ratio of the roughness Rz of one surface of the shielding layer close to the rubber film layer and the rubber gram weight parameter of the rubber film layer is 2-300.

As an improvement of the above, the electromagnetic shielding film further includes an insulating layer; the shielding layer is formed on one surface of the insulating layer; the ratio of the roughness Rz of the one surface of the insulating layer to the thickness of the shielding layer is 1.25 to 65.

As a refinement of the above aspect, the electromagnetic shielding film further includes a carrier layer; the carrier layer is arranged on one surface of the insulating layer, which is far away from the shielding layer.

As a modification of the above, the insulating layer is formed on one side of the carrier layer; the ratio of the roughness Rz of the one surface of the carrier layer to the thickness of the insulating layer is 0.3 to 3.

As an improvement of the scheme, the ratio of the roughness Rz of one surface of the shielding layer close to the adhesive film layer to the thickness of the adhesive film layer is 0.1-9.

As an improvement of the scheme, the grammes weight parameter of the adhesive film layer is 0.01-1 g per square decimeter.

As an improvement of the scheme, the roughness Rz of one surface of the shielding layer close to the adhesive film layer is 0.5-20 microns.

As an improvement of the scheme, a conductive protrusion is arranged on one surface of the shielding layer close to the adhesive film layer.

As an improvement of the above scheme, the conductive protrusion comprises a conductive base part and at least one conductive spike part integrally formed with the conductive base part; the conductive base part extends outwards from one surface of the shielding layer close to the film layer, and at least one conductive spine part extends outwards from the surface of the conductive base part.

As an improvement of the scheme, the protruding height of the conductive spine part is 0.1-8 microns.

In order to solve the same technical problem, another embodiment of the present invention further provides a circuit board, which includes a circuit board body and the electromagnetic shielding film according to any one of the above aspects; the electromagnetic shielding film is pressed with the circuit board body through the adhesive film layer; the rough surface of the shielding layer pierces through the adhesive film layer and is electrically connected with the ground layer of the circuit board body.

Compared with the prior art, the electromagnetic shielding film and the circuit board provided by the embodiment of the invention have at least one of the following beneficial effects:

when the electromagnetic shielding film is pressed on a circuit board, one surface of the shielding layer close to the adhesive film layer has roughness, and under the condition that the unit of the roughness Rz is micrometer and the unit of the rubber gram weight parameter is gram per square decimeter, the ratio of the roughness Rz of the surface of the shielding layer close to the adhesive film layer to the rubber gram weight parameter of the adhesive film layer is 2-300, so that the shielding layer can be effectively contacted and connected with the stratum of the circuit board under the condition of applying certain pressing force, the interference charges of the shielding layer can be effectively guided into the stratum of the circuit board, and the shielding efficiency of the electromagnetic shielding film is effectively improved; meanwhile, as the ratio of the roughness Rz of one surface of the shielding layer close to the adhesive film layer to the glue gram weight parameter of the adhesive film layer is 2-300, the glue in the adhesive film layer can be effectively contained by the surface of the shielding layer close to the adhesive film layer, so that the problem of obvious glue overflow at the edge between the electromagnetic shielding film and the circuit board due to the fact that a large amount of glue substances move to the edge of the circuit board is not easy to occur, and the circuit board laminated with the shielding film has good appearance; in addition, the ratio of the roughness Rz of one surface of the shielding layer close to the adhesive film layer to the rubber gram weight parameter of the adhesive film layer is 2-300, so that the adhesive amount of the adhesive film layer and the roughness of the one surface of the shielding layer can have a proper ratio, the shielding layer is effectively contacted with the ground layer of the circuit board and is connected with the circuit board in a pressing mode, the circuit board has a good appearance after the shielding layer is pressed on the circuit board in a pressing mode, meanwhile, the adhesive amount of the adhesive film layer is not required to be too small, or the pressing force on the shielding film is not required to be reduced intentionally, and the shielding film and the circuit board can have good bonding strength. In summary, the embodiments of the present invention can have the following advantages at the same time: good shielding effectiveness, good bonding strength with the circuit board and good appearance of the circuit board after being pressed on the circuit board.

Drawings

In order to more clearly illustrate the technical solution of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

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

fig. 2 is a schematic structural view of a second electromagnetic shielding film according to an embodiment of the present invention;

fig. 3 is a schematic structural view of a third electromagnetic shielding film according to an embodiment of the present invention;

fig. 4 is a schematic structural view of a fourth electromagnetic shielding film according to an embodiment of the present invention;

fig. 5 is a schematic structural diagram of a conductive bump according to an embodiment of the present invention;

fig. 6 is a schematic structural view of a fifth electromagnetic shielding film according to an embodiment of the present invention;

fig. 7 is a schematic structural diagram of a circuit board according to an embodiment of the present invention.

Reference is made to the accompanying drawings in which: 1. a carrier layer; 2. an insulating layer; 3. a shielding layer; 4. a glue film layer; 5. a protective film layer; 6. a conductive bump; 60. a conductive base portion; 61. a conductive spike portion; 7. the circuit board body.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the specification and claims, it is to be understood that the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", and the like, indicate orientations and positional relationships based on those shown in the drawings, are used for convenience in describing embodiments of the present invention, and do not indicate or imply that the referenced devices or components must have a particular orientation, be constructed and operated in a particular orientation, and thus are not to be construed as limiting the embodiments of the present invention.

Furthermore, the terms first, second and the like in the description and in the claims, are used for descriptive purposes only to distinguish the same technical features, and are not to be construed as indicating or implying relative importance or implicit indication of the number of technical features indicated, nor is an order or temporal order necessarily described. The terms are interchangeable where appropriate. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature.

Referring to fig. 1, an embodiment of the present invention provides an electromagnetic shielding film, which includes a shielding layer 3 and a film layer 4;

the adhesive film layer 4 is arranged on one surface of the shielding layer 3;

under the condition that the unit of the roughness Rz is micrometer and the unit of the rubber gram weight parameter is gram per square decimeter, the ratio of the roughness Rz of one surface, close to the rubber film layer 4, of the shielding layer 3 to the rubber gram weight parameter of the rubber film layer 4 is 2-300.

Wherein the shielding layer 3 plays a role of electromagnetic shielding. In addition, the electromagnetic shielding film can be attached to the circuit board through the adhesive film layer 4. In addition, when the shielding layer 3 is used, a layer of insulating material can be arranged on the surface of the shielding layer 3 far away from the adhesive film layer 4, so that the shielding layer 3 is effectively and electrically isolated from the outside.

In the embodiment of the invention, when the electromagnetic shielding film is pressed on a circuit board, as the surface of the shielding layer 3 close to the glue film layer 4 has roughness, and under the condition that the unit of the roughness Rz is micrometer and the unit of the glue gram weight parameter is gram per square decimeter, the ratio of the roughness Rz of the surface of the shielding layer 3 close to the glue film layer 4 to the glue gram weight parameter of the glue film layer 4 is 2-300, the shielding layer 3 can be effectively contacted and connected with the stratum of the circuit board under the condition of applying a certain pressing force, so that the interference charges of the shielding layer 3 can be effectively introduced into the stratum of the circuit board, and the shielding effectiveness of the electromagnetic shielding film is effectively improved; meanwhile, as the ratio of the roughness Rz of one surface of the shielding layer 3 close to the adhesive film layer 4 to the glue gram weight parameter of the adhesive film layer 4 is 2-300, the glue in the adhesive film layer 4 can be effectively contained by the surface of the shielding layer 3 close to the adhesive film layer 4, the problem of obvious glue overflow at the edge between the electromagnetic shielding film and the circuit board due to the fact that a large amount of glue substances move to the edge of the circuit board is not easy to occur, and the circuit board laminated with the shielding film has good appearance; in addition, simultaneously, as the ratio of the roughness Rz of one surface of the shielding layer 3 close to the adhesive film layer 4 to the rubber gram weight parameter of the adhesive film layer 4 is 2-300, the rubber amount of the adhesive film layer 4 and the roughness of the one surface of the shielding layer 3 can have a proper ratio, so that the shielding layer 3 can be effectively contacted with the ground layer of the circuit board and connected with the circuit board in a pressing manner, the circuit board has a good appearance after being pressed on the circuit board, meanwhile, the rubber amount of the adhesive film layer 4 is not required to be too small or the pressing force on the shielding film is not required to be reduced intentionally, and the shielding film and the circuit board can have good bonding strength. In summary, the embodiments of the present invention can have the following advantages at the same time: good shielding effectiveness, good adhesive strength with the circuit board and good appearance of the circuit board after being pressed and combined on the circuit board.

Illustratively, the film layer 4 has a grammage parameter of 0.01-1 grams per square decimeter.

In this embodiment, when the electromagnetic shielding film is pressed onto a circuit board, the glue film layer 4 with a rubber gram weight of 0.01-1 g per square decimeter is easily pierced by the side of the shielding layer 3 close to the glue film layer 4, so that the shielding layer 3 is electrically connected with the ground layer of the circuit board, and thus, the interference charges of the shielding layer 3 can be effectively introduced into the ground layer of the circuit board, and the shielding effectiveness of the electromagnetic shielding layer 3 is effectively improved. In addition, the adhesive film layer 4 with the grammes per square decimeter of 0.01-1 g can effectively maintain the adhesive strength between the electromagnetic shielding film and the circuit board, so that the phenomenon of board explosion between the electromagnetic shielding film and the circuit board is not easy to occur. As an example, the grammes parameter of the adhesive film layer 4 is 0.01, 0.05, 0.1, 0.2, 0.505, 0.7, 1 gram per square decimeter.

Illustratively, the roughness Rz of the surface of the shielding layer 3 close to the adhesive film layer 4 is 0.5-20 μm.

It is understood that the roughness Rz represents: the sum of the average of the 5 largest profile peak heights and the average of the 5 largest profile valley depths over the sample length.

In this embodiment, since the roughness Rz of the side of the shielding layer 3 close to the adhesive film layer 4 is 0.5 to 20 μm, therefore, when the electromagnetic shielding film is pressed on a circuit board, one surface of the shielding layer 3 close to the adhesive film layer 4 can effectively puncture the adhesive film layer 4, thereby electrically connecting the shielding layer 3 with the ground layer of the circuit board, so that the interference charges of the shielding layer 3 can be effectively introduced into the ground layer of the circuit board, thereby effectively improving the shielding effectiveness of the electromagnetic shielding layer 3, and when the roughness Rz of the surface of the shielding layer 3 close to the adhesive film layer 4 is 0.5-20 micrometers, the glue containing effect is better, the problem that glue overflows obviously at the edge of the circuit board due to the fact that a large amount of glue substances move to the edge of the circuit board is not easy to occur, and therefore the circuit board after the shielding film is pressed has good appearance. As an example, the roughness Rz of the surface of the shielding layer 3 close to the adhesive film layer 4 is 0.5, 1.00, 5.00, 10.25, 15, 20.

In the above embodiment, the ratio of the roughness Rz of the surface of the shielding layer 3 close to the adhesive film layer 4 to the thickness of the adhesive film layer 4 is 0.1 to 9.

In this embodiment, the ratio of the roughness Rz of the surface of the shielding layer 3 close to the glue film layer 4 to the thickness of the glue film layer 4 is 0.1-9, so that when the electromagnetic shielding film is laminated on a circuit board, the surface of the shielding layer 3 close to the glue film layer 4 can effectively pierce through the glue film layer 4 and is electrically connected with the ground layer of the circuit board, and then the interference charges of the shielding layer 3 can be effectively introduced into the ground layer of the circuit board, thereby effectively improving the shielding effectiveness of the electromagnetic shielding layer 3.

Wherein, the materials used for the glue film layer 4 are selected from the following materials: modified epoxy resins, acrylic resins, modified rubbers, and modified thermoplastic polyimides. It is understood that, in order to ensure that the shielding layer has good conductivity, the shielding layer 3 includes one or more of a metal shielding layer, a carbon nanotube shielding layer, a ferrite shielding layer, and a graphene shielding layer. Wherein the metal shielding layer comprises a single metal shielding layer and/or an alloy shielding layer; the single metal shielding layer is made of any one of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold, and the alloy shielding layer is made of any two or more of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold.

In the above embodiment, further, referring to fig. 2, the electromagnetic shielding film further includes an insulating layer 2; the insulating layer 2 is arranged on one surface of the shielding layer 3, which is far away from the adhesive film layer 4. The insulating layer 2 can electrically isolate the shielding layer 3 from the outside effectively, so that the electromagnetic shielding effect of the shielding layer 3 can be ensured.

Specifically, the shielding layer 3 is formed on one side of the insulating layer 2; the ratio of the roughness Rz of the one surface of the insulating layer 2 to the thickness of the shielding layer 3 is 1.25 to 65. In the process of forming the shielding layer 3 on the rough surface of the insulating layer 2, the ratio of the roughness Rz of the rough surface of the insulating layer 2 to the thickness of the shielding layer 3 is 1.25-65, so that the shielding layer 3 can undulate along with the rough surface of the insulating layer 2, and the surface of the shielding layer 3 away from the insulating layer 2 can be easily provided with roughness capable of piercing the adhesive film layer 4, so that the shielding layer 3 can be effectively electrically connected with the ground layer of the circuit board.

In the above embodiment, further, referring to fig. 3, the electromagnetic shielding film further includes a carrier layer 1; the carrier layer 1 is arranged on the side of the insulating layer 2 remote from the shielding layer 3. The carrier layer 1 may be for protecting the insulating layer 2 so that the insulating layer 2 is not damaged by external contact or impact, etc. Furthermore, the carrier layer 1 may serve as a base film forming the insulating layer 2, namely: an insulating layer 2 can be formed on one side of the carrier layer 1.

Specifically, the insulating layer 2 is formed on one side of the carrier layer 1; the ratio of the roughness Rz of the one side of the carrier layer 1 to the thickness of the insulating layer 2 is 0.3 to 3. Wherein, in the process of going to form on the one side of carrier layer 1 insulating layer 2, the carrier layer 1 the roughness Rz of the one side with the ratio of the thickness of insulating layer 2 is 0.3-3, can let like this insulating layer 2 follow carrier layer 1 the one side undulates, can let very easily insulating layer 2 keep away from carrier layer 1 one side has certain roughness to finally can let shielding layer 3 be close to the roughness that can pierce through tunica albuginea 4 has the one side of can piercing tunica albuginea 4, make shielding layer 3 can effectively with the stratum electricity of circuit board is connected.

In the above embodiment, further referring to fig. 4, a conductive protrusion 6 is disposed on a surface of the shielding layer 3 close to the adhesive film layer 4, so that the adhesive film layer 4 can be pierced more effectively, thereby further ensuring that the electromagnetic shielding film is electrically connected with the ground layer of the circuit board.

Specifically, the number of the conductive bumps 6 having a longitudinal height of more than 5um on the shielding film provided per square centimeter on average on the one surface of the shielding layer 3 is 1 to 1000. This can more effectively pierce the adhesive film layer 4, thereby further ensuring the electrical connection of the electromagnetic shielding film with the ground layer of the circuit board.

In the embodiment of the present invention, the conductive bumps 6 may be regularly or irregularly distributed on a surface of the shielding layer 3 close to the glue film layer 4. In this embodiment, the shapes of the conductive bumps 6 may be the same or different, and the distances between the conductive bumps 6 may be the same or different. Preferably, the shapes of the conductive bumps 6 are the same, and the conductive bumps 6 are uniformly distributed on the surface of the shielding layer 3 of the conductive base body portion, which is close to the adhesive film layer 4. In a specific implementation, the shielding layer 3 may be formed first, and then the conductive bump 6 may be formed on the shielding layer 3 by another process. Of course, the shielding layer 3 and the conductive bump 6 may also be an integral structure formed by a one-step molding process.

Illustratively, referring to fig. 5, the conductive bump 6 includes a conductive base portion 60 and at least one conductive spike 61; the conductive base portion 60 extends outward from a surface of the shielding layer 3 close to the adhesive film layer 4, and at least one conductive spike portion 61 extends outward from a surface of the conductive base portion 60. The conductive spike part 61 extending from the surface of the conductive base part 60 can pierce the adhesive film layer 4 more effectively, so that the shielding layer 3 can be better electrically connected with the ground layer of the circuit board.

Specifically, the height of the protrusion of the conductive spike part 61 is 0.1 to 8 micrometers, so that the conductive spike part 61 can effectively puncture the glue film layer 4, thereby further ensuring that the electromagnetic shielding film is electrically connected with the ground layer of the circuit board.

Preferably, the conductive bump 6 may have a certain distance with the outer surface of the adhesive film layer 4, and may also contact with the outer surface of the adhesive film layer 4 or extend out of the outer surface of the adhesive film layer 4. In addition, the outer surface of the adhesive film layer 4 may be a flat surface without undulation, or may be an uneven surface with gentle undulation.

It should be noted that the shapes of the conductive bumps 6 in fig. 4 and 5 are only exemplary, and due to differences in process means and parameters, the conductive bumps 6 may also be in other shapes such as clusters, ice-hanging shapes, stalactite shapes, and dendrites. In addition, the conductive bump 6 in the embodiment of the present invention is not limited to the shape shown in the drawings and described above, and any conductive bump 6 having piercing and conductive functions is within the scope of the present invention.

As another example, the conductive bump 6 may be composed of one or more conductive particles. The conductive particles include one or more of metal particles, carbon nanotube particles, and ferrite particles. Further, the metal particles include single metal particles and/or alloy particles; the single metal particles are made of any one of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold, and the alloy particles are made of any two or more of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold. It should be noted that the conductive bump 6 may be the same as or different from the material of the shielding layer 3.

It should be noted that the shielding layer 3 of the present embodiment may have a single-layer structure or a multi-layer structure. When the shielding layer 3 is a single layer, a conductive bump may be disposed on one surface of each shielding layer 3 close to the adhesive film layer 4; when the shielding layer 3 is a plurality of layers, a conductive protrusion may be further disposed on one surface of each shielding layer 3 close to the adhesive film layer 4. In addition, the shielding layer 3 of the present embodiment may be provided in a grid shape, a foam shape, etc. according to the requirements of actual production and application.

In the embodiment of the present invention, in order to further ensure the connection between the electromagnetic shielding film and the ground layer of the circuit board, the adhesive layer 4 in this embodiment includes an adhesive layer containing conductive particles. The adhesive layer 4 comprises an adhesive layer containing conductive particles, so that the conductive capability of the adhesive layer 4 is improved, and the ground connection of the electromagnetic shielding film and the circuit board is further ensured. Of course, in the embodiment of the present invention, the adhesive layer 4 may include an adhesive layer without containing conductive particles, so as to reduce the insertion loss of the circuit board with the electromagnetic shielding film, thereby improving the shielding performance and improving the bending resistance of the circuit board.

Referring to fig. 6, the electromagnetic shielding film in this embodiment further includes a protection film layer 5, and the protection film layer 5 is disposed on a surface of the adhesive film layer 4 away from the shielding layer 3. The protective film layer 5 has a protective effect to ensure that the insulating layer 2 is not scratched or damaged in the using process, so that the high shielding effectiveness of the shielding layer 3 is maintained. The protective film layer 5 comprises a PPS film layer, a PEN film layer, a polyester film layer, a polyimide film layer, a film layer formed after epoxy resin ink is cured, a film layer formed after polyurethane ink is cured, a film layer formed after modified acrylic resin is cured or a film layer formed after polyimide resin is cured.

Specifically, when the electromagnetic shielding film includes the carrier layer 1, the insulating layer 2, the shielding layer 3, the adhesive film layer 4, and the protective film layer 5, the method for preparing the electromagnetic shielding film includes:

1) preparing a carrier layer 1;

2) forming an insulating layer 2 on one side of the carrier layer 1;

3) forming a shielding layer 3 on the side of the insulating layer 2 remote from the carrier layer 1;

4) coating glue on one surface of the shielding layer 3 far away from the insulating layer 2 to form a glue film layer 4;

5) and a protective film layer 5 is attached to one surface of the adhesive film layer 4, which is far away from the shielding layer 3.

To facilitate an understanding of the above-described inventive arrangements, the following five specific examples are provided and tested:

the first embodiment is as follows:

an electromagnetic shielding film comprises a shielding layer and an adhesive film layer; the adhesive film layer is arranged on one surface of the shielding layer; the roughness Rz that is close to of shielding layer the one side of glued membrane layer is 1 micron, the gluey grammes per square decimeter parameter of glued membrane layer is 0.5 gram, the shielding layer be close to the roughness Rz of the one side of glued membrane layer with the proportion of the gluey grammes per square decimeter parameter of glued membrane layer's numerical value between them is 2.

And (3) testing results: after the electromagnetic shielding film of the present embodiment is pressed on the circuit board, through a test, the grounding resistance between the shielding layer of the electromagnetic shielding film of the present embodiment and the ground layer of the circuit board is less than 213m Ω. Moreover, the good peeling strength between the electromagnetic shielding film and the circuit board of the embodiment is greater than 12.23N/cm, and the length of the glue overflow of the adhesive film layer after the electromagnetic shielding film is laminated on the circuit board is less than 70 μm.

Therefore, by applying the electromagnetic shielding film of the embodiment, the interference charges of the shielding layer can be effectively introduced into the ground layer of the circuit board, so that the electromagnetic shielding film has good shielding efficiency, and after being pressed on the circuit board, the electromagnetic shielding film has good adhesive strength with the circuit board, and the circuit board has good appearance.

Example two:

an electromagnetic shielding film comprises a shielding layer and an adhesive film layer; the adhesive film layer is arranged on one surface of the shielding layer; the roughness Rz of the shielding layer close to one surface of the adhesive film layer is 15.1 microns, the adhesive gram weight parameter of the adhesive film layer is 0.1 gram per square decimeter, and the ratio of the roughness Rz of the shielding layer close to one surface of the adhesive film layer to the adhesive gram weight parameter of the adhesive film layer is 151.

And (3) testing results: after the electromagnetic shielding film of the present embodiment is pressed on the circuit board, through a test, the grounding resistance between the shielding layer of the electromagnetic shielding film of the present embodiment and the ground layer of the circuit board is less than 78m Ω. Moreover, the good peeling strength between the electromagnetic shielding film and the circuit board of the embodiment is greater than 10.18N/cm, and the length of the glue overflow of the adhesive film layer after the electromagnetic shielding film is laminated on the circuit board is less than 56 μm.

Therefore, by applying the electromagnetic shielding film of the embodiment, the interference charges of the shielding layer can be effectively introduced into the ground layer of the circuit board, so that the electromagnetic shielding film has good shielding efficiency, and after being pressed on the circuit board, the electromagnetic shielding film has good adhesive strength with the circuit board, and the circuit board has good appearance.

Example three:

an electromagnetic shielding film comprises a shielding layer and an adhesive film layer; the adhesive film layer is arranged on one surface of the shielding layer; the roughness Rz of the surface, close to the glue film layer, of the shielding layer is 0.5 micrometer, the glue gram weight parameter of the glue film layer is 0.01 gram per square decimeter, and the ratio of the roughness Rz of the surface, close to the glue film layer, of the shielding layer to the glue gram weight parameter of the glue film layer is 50.

And (3) testing results: after the electromagnetic shielding film of the present embodiment is pressed on the circuit board, through a test, the ground resistance between the shielding layer of the electromagnetic shielding film of the present embodiment and the ground layer of the circuit board is less than 345m Ω. Moreover, the good peeling strength between the electromagnetic shielding film and the circuit board of the embodiment is greater than 10.21N/cm, and the length of the glue overflow of the adhesive film layer after the electromagnetic shielding film is laminated on the circuit board is less than 90 μm.

Therefore, by applying the electromagnetic shielding film of the embodiment, the interference charges of the shielding layer can be effectively introduced into the ground layer of the circuit board, so that the electromagnetic shielding film has good shielding efficiency, and after being pressed on the circuit board, the electromagnetic shielding film has good adhesive strength with the circuit board, and the circuit board has good appearance.

Example four:

an electromagnetic shielding film comprises a shielding layer and an adhesive film layer; the adhesive film layer is arranged on one surface of the shielding layer; the roughness Rz of the shielding layer close to one surface of the adhesive film layer is 20 micrometers, the adhesive gram weight parameter of the adhesive film layer is 1 gram per square decimeter, and the ratio of the roughness Rz of the shielding layer close to one surface of the adhesive film layer to the adhesive gram weight parameter of the adhesive film layer is 20.

And (3) testing results: after the electromagnetic shielding film of the present embodiment is pressed on the circuit board, through a test, the grounding resistance between the shielding layer of the electromagnetic shielding film of the present embodiment and the ground layer of the circuit board is less than 118m Ω. Moreover, the good peeling strength between the electromagnetic shielding film and the circuit board of the embodiment is larger than 16.79N/cm, and the length of the glue overflow of the adhesive film layer after the electromagnetic shielding film is pressed on the circuit board is smaller than 106 μm.

Therefore, by applying the electromagnetic shielding film of the embodiment, the interference charges of the shielding layer can be effectively introduced into the ground layer of the circuit board, so that the electromagnetic shielding film has good shielding efficiency, and after being pressed on the circuit board, the electromagnetic shielding film has good adhesive strength with the circuit board, and the circuit board has good appearance.

Example five:

an electromagnetic shielding film comprises a shielding layer and an adhesive film layer; the adhesive film layer is arranged on one surface of the shielding layer; the roughness Rz of the shielding layer close to one surface of the adhesive film layer is 3 microns, the adhesive gram weight parameter of the adhesive film layer is 0.01 gram per square decimeter, and the ratio of the roughness Rz of the shielding layer close to one surface of the adhesive film layer to the adhesive gram weight parameter of the adhesive film layer is 300.

And (3) testing results: after the electromagnetic shielding film of the present embodiment is pressed on the circuit board, through a test, the grounding resistance between the shielding layer of the electromagnetic shielding film of the present embodiment and the ground layer of the circuit board is less than 107m Ω. Moreover, the good peeling strength between the electromagnetic shielding film and the circuit board of the embodiment is greater than 10.37N/cm, and the length of the glue overflow of the adhesive film layer after the electromagnetic shielding film is laminated on the circuit board is less than 85 μm.

Therefore, by applying the electromagnetic shielding film of the embodiment, interference charges of the shielding layer can be effectively introduced into the ground layer of the circuit board, so that the electromagnetic shielding film has good shielding efficiency, and after being pressed on the circuit board, the electromagnetic shielding film has good adhesive strength with the circuit board, and meanwhile, the circuit board has good appearance.

The numerical ratio of the roughness Rz to the rubber weight parameter is only an example, and the numerical ratio can be other numerical values, such as 10, 25, 75, 100, 125, 175, 225, 275, and the like.

Referring to fig. 7, another embodiment of the present invention further provides a circuit board, which includes a circuit board body 7 and the electromagnetic shielding film according to any of the above embodiments; the electromagnetic shielding film is pressed with the circuit board body 7 through the adhesive film layer 4; one surface of the shielding layer 3 close to the glue film layer 4 pierces through the glue film layer 4 and is electrically connected with the ground layer of the circuit board body 7.

Preferably, the circuit board body 7 is one of a flexible single-sided board, a flexible double-sided board, a flexible multilayer board and a flex-rigid board.

In the embodiment of the invention, one surface of the shielding layer 3 close to the adhesive film layer 4 can pierce through the adhesive film layer 4 and is connected with the ground layer of the circuit board body 7 when the electromagnetic shielding film is pressed with the circuit board body 7, so that the ground connection between the shielding layer 3 and the circuit board body 7 is ensured, interference charges in the shielding layer 3 and the shielding layer 3 are led into the ground, and the interference source formed by accumulation of the interference charges is prevented from influencing the normal operation of the circuit board.

In the embodiment of the invention, as the surface of the shielding layer 3 close to the glue film layer 4 has roughness, and the ratio of the roughness Rz of the surface of the shielding layer 3 close to the glue film layer 4 to the glue gram weight parameter of the glue film layer 4 is 2-300 under the condition that the unit of the roughness Rz is micrometer and the unit of the glue gram weight parameter is gram per square decimeter, the shielding layer 3 can be effectively contacted and connected with the stratum of the circuit board under the condition of applying a certain pressing force, so that the interference charges of the shielding layer 3 can be effectively introduced into the stratum of the circuit board, and the shielding effectiveness of the electromagnetic shielding film is effectively improved; meanwhile, as the ratio of the roughness Rz of one surface of the shielding layer 3 close to the adhesive film layer 4 to the rubber gram weight parameter of the adhesive film layer 4 is 2-300, the rubber in the adhesive film layer 4 can be effectively contained by one surface of the shielding layer 3 close to the adhesive film layer 4, the problem of obvious rubber overflow at the edge between the electromagnetic shielding film and the circuit board due to the fact that a large amount of rubber substances move to the edge of the circuit board is not easy to occur, and the circuit board after the shielding film is pressed has good appearance; in addition, simultaneously, as the ratio of the roughness Rz of the surface of the shielding layer 3 close to the adhesive film layer 4 to the rubber gram weight parameter of the adhesive film layer 4 is 2-300, the rubber amount of the adhesive film layer 4 and the roughness of the surface of the shielding layer 3 can have a proper ratio, so that the shielding layer 3 can be effectively contacted with the ground layer of the circuit board and connected with the circuit board in a pressing manner, the circuit board has a good appearance after being pressed on the circuit board, and meanwhile, the rubber amount of the adhesive film layer 4 is not required to be too small or the pressing force on the shielding film is not required to be reduced intentionally, and the shielding film and the circuit board can have good bonding strength. In summary, the embodiments of the present invention can have the following advantages at the same time: good shielding effectiveness, good bonding strength with the circuit board and good appearance of the circuit board after being pressed on the circuit board.

The above description is only an embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention disclosed herein are intended to be covered by the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (11)

1. An electromagnetic shielding film is characterized by comprising a shielding layer and a film adhesive layer;

the adhesive film layer is arranged on one surface of the shielding layer;

wherein, under the condition that the unit of the roughness Rz is micrometer and the unit of the rubber gram weight parameter is gram per square decimeter, the ratio of the roughness Rz of one surface of the shielding layer close to the rubber film layer and the rubber gram weight parameter of the rubber film layer is 2-300.

2. The electromagnetic shielding film of claim 1, further comprising an insulating layer; the shielding layer is formed on one surface of the insulating layer; the ratio of the roughness Rz of the one surface of the insulating layer to the thickness of the shielding layer is 1.25 to 65.

3. The electro-magnetic shielding film of claim 2, further comprising a carrier layer; the carrier layer is arranged on one surface of the insulating layer, which is far away from the shielding layer.

4. The electro-magnetic shielding film of claim 3, wherein the insulating layer is formed on one side of the carrier layer; the ratio of the roughness Rz of the one side of the carrier layer to the thickness of the insulating layer is 0.3 to 3.

5. The electromagnetic shielding film according to claim 1, wherein a ratio of a roughness Rz of a surface of the shielding layer adjacent to the adhesive film layer to a thickness of the adhesive film layer is 0.1 to 9.

6. The electromagnetic shielding film of claim 1, wherein the adhesive gram weight parameter of the adhesive film layer is 0.01-1 grams per square decimeter.

7. The electromagnetic shielding film according to claim 1, wherein the roughness Rz of the surface of the shielding layer adjacent to the adhesive film layer is 0.5 to 20 μm.

8. The electromagnetic shielding film according to claim 1, wherein a conductive bump is disposed on a surface of the shielding layer adjacent to the adhesive film layer.

9. The electromagnetic shielding film according to claim 8, wherein the conductive protrusion comprises a conductive base portion and at least one conductive spike portion integrally formed with the conductive base portion; the conductive base part extends outwards from one surface of the shielding layer close to the film layer, and at least one conductive spine part extends outwards from the surface of the conductive base part.

10. The electro-magnetic shielding film of claim 9, wherein the conductive spikes have a protrusion height of 0.1-8 microns.

11. A wiring board comprising a wiring board body and the electromagnetic shielding film according to any one of claims 1 to 10; the electromagnetic shielding film is pressed with the circuit board body through the adhesive film layer; one surface of the shielding layer, which is close to the glue film layer, pierces through the glue film layer and is electrically connected with the ground layer of the circuit board body.

Images