CN114736620B

CN114736620B - Shielding adhesive tape, preparation method thereof and shielding structure

Info

Publication number: CN114736620B
Application number: CN202210671033.3A
Authority: CN
Inventors: 陈木久; 陈巧; 刘晶云
Original assignee: Shenzhen Johan Material Tech Co ltd
Current assignee: Zhuohan (Hunan) New Material Technology Co.,Ltd.
Priority date: 2022-06-15
Filing date: 2022-06-15
Publication date: 2022-11-15
Anticipated expiration: 2042-06-15
Also published as: CN114736620A

Abstract

The application discloses shielding sticky tape, this shielding sticky tape's preparation method and shielding structure, shielding sticky tape includes: the adhesive film layer is arranged on one side of the copper foil layer in a laminated mode and comprises an adhesive main body and conductive fillers, the conductive fillers account for 3-10 wt% of the adhesive film layer, the conductive fillers comprise conductive particles and conductive fibers, the conductive particles are spherical or quasi-spherical, the conductive fibers are in a flat lying state, the conductive particles and the conductive fibers are staggered with each other and are arranged in the adhesive main body in a single-layer mode, and at least 90% of all the conductive fibers and a preset direction form an included angle of 0-30 degrees; the film layer satisfies the following relation: h =5 to 15 μm, D = h ± 2 μm, and D = h ± 2 μm; wherein h is the thickness of the adhesive film layer, D is the particle size of the conductive particles, and D is the diameter of the conductive fibers; the beneficial effect of this application does: a good shielding effect can be ensured and at the same time a good adhesion can be ensured.

Description

Shielding adhesive tape, preparation method thereof and shielding structure

Technical Field

The application relates to the technical field of electromagnetic shielding, in particular to a shielding adhesive tape, a preparation method of the shielding adhesive tape and a shielding structure.

Background

In the smart phone industry, due to height limitation or the need of a subsequent dispensing process, a shielding tape is often used for replacing a shielding cover on a shielding bracket of a Printed Circuit Board (PCB) to form a faraday cage or a shielding body, so that the inside and outside isolation and shielding of a signal source are realized.

Generally, a shielding tape includes a shielding layer and an adhesive film layer, the shielding layer is usually a copper foil or a metalized non-woven fabric, and can reflect and absorb signals, the single adhesive film layer does not have a shielding function, and generally, a conductive filler is added into the adhesive film layer. In the prior art, in order to prevent a signal from leaking through a shielding layer, conductive particles and conductive fibers are used as conductive fillers, and a conductive network structure is formed by utilizing the lap joint between the conductive particles and the conductive fibers, but more conductive fillers are required to be added in order to ensure the sufficient lap joint between the conductive particles and the conductive fibers, so that the cohesiveness is greatly reduced, the adhesion stability of a frame of a bracket is poor, particularly, when the width of the frame is small, the adhesion stability is poor, gaps are easily caused, even slight gaps can cause serious signal leakage, and the shielding effect is poor; if the filling amount of the conductive filler is too small, the resistance of the adhesive film layer is large, the grounding is insufficient, and the adhesive film layer is easy to leak signals to affect the shielding effect.

Disclosure of Invention

An object of the present application is to provide a shielding tape which can effectively secure a shielding effect while ensuring good adhesive properties. Another object of the present application is to provide a shielding structure, and a method for preparing the shielding tape.

The purpose of the application is realized by the following technical scheme:

a shielding tape, comprising:

a copper foil layer; and

the adhesive film layer is arranged on one side of the copper foil layer in a stacked mode and comprises an adhesive main body and conductive fillers, the conductive fillers account for 3wt% -10 wt% of the adhesive film layer, the conductive fillers comprise conductive particles and conductive fibers, the conductive particles are spherical or quasi-spherical, the conductive fibers are in a flat lying state, the conductive particles and the conductive fibers are staggered with each other and are arranged in the adhesive main body in a single-layer mode, and at least 90% (accounting for the total amount) of the conductive fibers and a preset direction form an included angle of 0-30 degrees; the adhesive film layer satisfies the following relational expression:

h=5~15μm， d=h±2μm，D=h±2μm；

wherein h is the thickness of the adhesive film layer, D is the particle size of the conductive particles, and D is the diameter of the conductive fibers.

In some embodiments of the present application, the ratio of the conductive particles in the adhesive film layer is 2wt% to 5wt%, and the ratio of the conductive fibers in the adhesive film layer is 2wt% to 5wt%.

In some embodiments of the present application, the conductive particles include at least one of Ni, ni — C composite, and Ag, and the conductive fibers include at least one of carbon fibers, carbon tubes, and carbon fibers, each of which has a nickel layer on an outer surface thereof.

In some embodiments of the present application, the thickness of the copper foil layer is 9 to 18 μm.

In some embodiments of the present application, the preset direction is a length direction of the shielding tape.

In some embodiments of the present application, the shielding tape further comprises:

from the type membrane, locate from the type membrane the glue film layer deviates from one side of copper foil layer.

A preparation method of the shielding adhesive tape comprises the following steps:

adding conductive particles, conductive fibers, an adhesive and a curing agent into a solvent, and stirring to obtain slurry with fluid viscosity of 1000-5000 cps;

coating the slurry on one side of a copper foil layer along a preset direction by using a scraper so as to form a wet film on the copper foil layer;

and baking to enable the wet film to be solidified into a gel film layer on the copper foil layer, so that the shielding adhesive tape is obtained.

In some embodiments of the application, stirring is performed in a mechanical dispersion disc, the rotating speed is 600 to 1000rpm, and the stirring time is 20 to 40min.

In some embodiments of the present application, the baking is performed at 60 to 100 ℃, and the baking time is 10 to 30min.

In some embodiments of the present application, after the wet film is cured to a film layer on the copper foil, the method further comprises the steps of:

the adhesive film layer deviates from the adhesive film layer attached to one side of the copper foil layer.

A shielding structure, comprising:

the shielding bracket is provided with a frame on the top; and

the shielding adhesive tape is formed by die cutting of the shielding adhesive tape, included angles of 40-60 degrees are formed between the edges of the shielding adhesive tape and the preset direction, the outer contour of the shielding adhesive tape is matched with that of the frame, and one surface of the adhesive tape layer, which is deviated from the copper foil layer, is aligned and adhered to the frame;

satisfies the relation: l is more than w, wherein L is the length of the conductive fiber in the shielding adhesive tape, and w is the width of the frame.

In some embodiments of the present application, the relationship:

。

in some embodiments of the present application, each edge of the shielding tape block intersects with the predetermined direction at an included angle of 40 ° to 50 °.

In some embodiments of the present application, the relationship is satisfied: w is less than or equal to 2 mm.

In some embodiments of the present application, the relationship is satisfied: l is more than or equal to 3 mm and less than or equal to 10 mm.

According to the shielding tape, the preparation method and the shielding structure, the adhesive film layer in the shielding tape is thin, the thickness is only 5 to 15 micrometers, and the whole leakage at the position of the adhesive film layer can be ensured to be less; in addition, the diameter of the conductive fiber and the particle size of the conductive particles are approximately consistent with the thickness of the adhesive film layer and are distributed in a single layer in the adhesive film layer, the conductive fibers are in a flat lying shape and are approximately arranged in the same direction in a controlled manner, the slot antenna and the cut-off waveguide effect can be superposed, and the leakage of signals through the adhesive film layer is very limited; on this basis, only need set up about 3wt% ~10wt% electrically conductive filler just can realize better shielding effect, guarantee reliable stable adhesion simultaneously, avoid producing the signal that the space leads to because of the adhesion is unstable and reveal, further guarantee the stability of shielding effect, especially use the narrower situation of frame of shielding support.

Drawings

The present application is described in further detail below with reference to the drawings and preferred embodiments, but those skilled in the art will appreciate that the drawings are only drawn for the purpose of illustrating the preferred embodiments and should not be taken as limiting the scope of the present application. Furthermore, unless specifically stated otherwise, the drawings are intended to be conceptual in nature of the described objects or configurations and may contain exaggerated displays, and are not necessarily drawn to scale.

FIG. 1 is a schematic structural view of a masking tape according to some embodiments of the present application;

FIG. 2 is a schematic structural view of a masking tape according to other embodiments of the present application;

FIG. 3 is a perspective view of a masking tape according to some embodiments of the present application;

FIG. 4 is a schematic structural view of a shielding structure according to some embodiments of the present application;

fig. 5 is a schematic perspective view of a shielding rubber block and a frame in a shielding structure according to some embodiments of the present application;

FIG. 6 is a flow chart of a method of making a masking tape according to some embodiments of the present application;

FIG. 7 is a shielding effectiveness testing platform for testing shielding effectiveness of shielding tape according to some embodiments of the present application;

in the figure, 100, shielding tape; 10. a copper foil layer; 20. a glue film layer; 21. gluing a main body; 22. a conductive filler; 221. conductive particles; 222. a conductive fiber; 30. a release film;

200. a shield support; 201. a frame; 300. shielding the rubber block; 400. an electronic component; 500. a substrate; 600. a ground terminal;

700. a shielding effectiveness test platform; 701. a radio frequency analog antenna assembly; 7011. a transmitting module; 7012. a receiving module; 702. a network analyzer;

w, width of the frame; x, the preset direction.

Detailed Description

Hereinafter, preferred embodiments of the present application will be described in detail with reference to the accompanying drawings. Those skilled in the art will appreciate that the descriptions are illustrative only, exemplary, and should not be construed as limiting the scope of the application.

First, it should be noted that the orientations of top, bottom, upward, downward, and the like referred to herein are defined with respect to the orientation in the respective drawings, are relative concepts, and thus can be changed according to different positions and different practical states in which they are located. These and other orientations, therefore, should not be used in a limiting sense.

It should be noted that the term "comprising" does not exclude other elements or steps and the "a" or "an" does not exclude a plurality.

Furthermore, it should also be noted that any single technical feature described or implied in the embodiments herein, or any single technical feature shown or implied in the figures, can still be combined between these technical features (or their equivalents) to obtain other embodiments of the present application that are not directly mentioned herein.

It will be further understood that the terms "first," "second," and the like, are used herein to describe various information and should not be limited to these terms, which are used only to distinguish one type of information from another. For example, "first" information may also be referred to as "second" information, and similarly, "second" information may also be referred to as "first" information, without departing from the scope of the present application.

It should be noted that in different drawings, the same reference numerals denote the same or substantially the same components.

As shown in fig. 1 and 3, a first aspect of the embodiments of the present application provides a shielding tape 100, which includes: the copper foil layer 10 and the adhesive film layer 20, the adhesive film layer 20 is stacked on one side of the copper foil layer 10, the adhesive film layer 20 includes an adhesive main body 21 and a conductive filler 22, the adhesive main body 21 can be acrylic acid glue or silica gel glue, the proportion of the conductive filler 22 in the adhesive film layer 20 is 3wt% -10 wt%, the conductive filler 22 includes conductive particles 221 and conductive fibers 222, the conductive particles 221 are spherical or quasi-spherical (i.e. the outline is roughly spherical), the conductive fibers 222 are in a flat lying state, the conductive particles 221 and the conductive fibers 222 are staggered with each other and arranged in the adhesive main body 21 in a single layer, and at least 90% (i.e. 90% or more of the total amount) of all the conductive fibers 222 and a preset direction form an included angle of 0-30 degrees; the adhesive film layer 20 satisfies the following relationship: h =5 to 15 μm, D = h ± 2 μm; wherein h is the thickness of the adhesive film layer 20, D is the particle size of the conductive particles 221, and D is the diameter of the conductive fibers 222.

In addition, in some embodiments, shielding tape 100 further comprises: from type membrane 30, leave the one side that the glued membrane layer 20 deviates from copper foil layer 10 from the type membrane 30 stack, can refer to specifically that shown in fig. 2, it is convenient for rolling up to preserve and transport from attached type membrane 30.

A second aspect of the embodiments of the present application provides a shielding structure, specifically referring to fig. 4 and 5, including: the shielding bracket 200 is arranged around the periphery of the electronic component 400 and connected with a grounding terminal 600 on the substrate 500, and the top of the shielding bracket 200 is provided with a frame 201; the shielding rubber block 300 is formed by die-cutting the shielding adhesive tape 100 (see fig. 3 specifically) and tearing off the release film 30, each edge of the shielding rubber block 300 intersects with the preset direction, the intersection angle is 40 to 60 degrees, the outer contour of the shielding rubber block 300 is matched with the outer contour of the frame 201, and the surface of the rubber film layer 20 departing from the copper foil layer 10 is aligned and adhered to the frame 201.

Based on the shielding structure, the adhesive film layer 20 is thin, the thickness is only 5 to 15 μm, according to the leakage principle of the metal shielding body, the smaller the gap is, the less the leakage is, and the thickness of the adhesive film layer 20 is equivalent to the width of the gap, so that the thinner adhesive film layer 20 is selected in the embodiment to ensure that the leakage is less overall; in addition, the diameter of the conductive fiber 222 and the particle size of the conductive particle 221 are substantially consistent with the thickness of the adhesive film layer 20, the adhesive main body 21 is filled outside the conductive filler 22, not only is connected with the conductive filler 22, but also provides the adhesive force between the copper foil layer 10 and the frame 201, if the adhesive film layer 20 is regarded as a slit between the copper foil layer 10 and the shielding bracket 200, the slit can be regarded as a slot antenna by utilizing the babinet principle, the conductive fillers 22 are conducted up and down, so that a long slot antenna is divided into a plurality of short slot antennas, and the radiation or leakage of the slot is reduced; furthermore, the conductive fibers 222 and the conductive particles 221 are staggered with each other and arranged in a single layer in the adhesive main body, that is, the conductive fibers 222, the conductive particles 221, and the conductive fibers 222 and the conductive particles 221 are not overlapped in the height direction, so that agglomeration between the conductive fillers 22 can be avoided, the conductive fibers 222 in the shielding tape 100 lie flat (i.e., are kept substantially parallel to the plane where the frame 201 is located), and an included angle of 0 to 30 ° is ensured between most of the conductive fibers 222 (accounting for 90% of the total number) and the preset direction, that is, the conductive fibers 222 can be controlled to be arranged substantially along the preset direction, after the shielding tape 100 is die-cut into the shielding adhesive block 300, so that each edge of the shielding adhesive block 300 forms 40 to 60 ° with the preset direction, therefore, it can be ensured that most of the conductive fibers 222 in the shielding adhesive block 300 are intersected with each edge, at this time, by setting up the longer conductive fibers 222, the shielding adhesive block 300 can cross over the shielding adhesive block 201, when the shielding adhesive block 300 is adhered to the frame 201, most of the shielding adhesive block 201 can cross over the shielding adhesive film layer, so that the two side walls of the shielding adhesive film can form a very good signal leakage effect, and the short waveguide tube, so that the two side gaps can be further referred to the two side slots of the antenna waveguide tube, and the short waveguide tube can be formed by the short waveguide tube, and the short waveguide tube, so that the short waveguide tube can be further referred to form a very good effect; moreover, because the stack of above-mentioned effect only needs to set up less conductive filler 22 in the glued membrane layer 20, only needs to set up about 3wt% ~10wt% conductive filler 22 just can realize better shielding effect to guarantee reliable stable adhesion, avoid producing the signal that the space leads to because of the adhesion is unstable and reveal, further guarantee the stability of shielding effect, be particularly useful for when the narrower situation of frame 201 of shield support 200.

Preferably, in order to enable more shielding adhesive blocks 300 meeting the above requirements to be die-cut and formed in the shielding adhesive tape 100, the predetermined direction is the length direction of the shielding adhesive tape 100, which can be specifically referred to as fig. 2. However, the predetermined direction is not limited to the longitudinal direction of the shield tape 100.

In some embodiments, in the shielding tape 100, the percentage of the conductive particles 221 in the adhesive film layer 20 is 2wt% to 5wt%, and the percentage of the conductive fibers 222 in the adhesive film layer 20 is 2wt% to 5wt%, so that the shielding effect can be better achieved, and better adhesion can be ensured.

In some embodiments of the present disclosure, the conductive particles 221 include at least one of Ni, ni — C composite, and Ag, the conductive fibers 222 include at least one of carbon tubes, carbon fibers, and carbon fibers with a nickel layer on the outer surface, and the conductive fibers 222 are in a cylindrical strip shape.

Specifically, in some embodiments, the copper foil layer 10 is preferably electrolytic copper.

For high frequency signals (> 1 Ghz), the shielding effectiveness of the copper foil layer 10 is mainly manifested in reflection and absorption. Considering that the skin depth of the 1Ghz copper foil layer 10 is 2 μm, and the 9 μm copper foil layer 10 is more than 3 times the skin depth, the absorption loss in the vertical direction is sufficiently large, and high-frequency signals cannot penetrate from the vertical plane. The higher the frequency, the smaller the skin depth, 9 μm is sufficient for vertical shielding of high frequency signals, so in some embodiments of the thickness of the copper foil layer 10, in order to ensure a good shielding effect, the thickness of the copper foil layer 10 is greater than or equal to 9 μm. Meanwhile, the cost and the conformability to the curved surface are also influenced by the excessive thickness of the copper foil layer 10, and the thickness of the copper foil layer 10 is less than or equal to 18 microns.

In another aspect of the embodiments of the present application, a method for manufacturing the shielding tape 100 is further provided, and specifically refer to fig. 6, which includes the following steps:

s1, adding conductive particles 221, conductive fibers 222, an adhesive and a curing agent into a solvent, and stirring to obtain slurry with the fluid viscosity of 1000-5000 cps;

s2, coating the slurry on one side of the copper foil layer 10 along a preset direction by using a scraper so as to form a wet film on the copper foil layer 10;

and S3, baking to enable the wet film to be solidified into a gel film layer 20 on the copper foil layer 10, and thus obtaining the shielding adhesive tape 100.

In this embodiment, the adhesive film layer 20 is prepared by a doctor blade coating method, the viscosity of the slurry is low, the conductive fibers 222 can be kept lying under the action of gravity during the blade coating process, and when the blade coating is performed along the preset direction, the conductive fibers 222 are roughly arranged along the blade coating direction under the action of the fluid shearing to form directional arrangement, so that at least 90% (accounting for the total amount) of all the conductive fibers 222 and the preset direction form an included angle of 0-30 degrees.

Alternatively, in some embodiments, the adhesive is acrylic resin, the curing agent is epoxy curing agent, and the solvent is ethyl acetate; and the viscosity is adjusted by the solvent and the flatting agent, so that the uniformly dispersed slurry can be obtained, and the solid content of the slurry is 20-40%.

Specifically, in some embodiments of the present application, in step S2, a mechanical dispersion disc is used for stirring and dispersing, the rotation speed is set to 600 to 1000rpm, and the stirring time is 20 to 40min. Illustratively, the rotation speed is 800 rpm and stirring is for 30min.

In some embodiments, in the step S3, the baking is performed in an environment of 60 to 100 ℃, and the baking time is 10 to 30min.

Illustratively, the raw materials are selected specifically and the corresponding parts by weight are as follows: 5 parts of nickel powder as conductive particles 221, 5 parts of nickel-plated carbon fiber as conductive fiber 222, 90 parts of acrylic resin as adhesive, 1 part of epoxy curing agent as curing agent, 150 parts of ethyl acetate as solvent and 0.5 part of flatting agent.

The method of making shielding tape 100 in some embodiments, after curing the wet film on copper foil layer 10 to form film layer 20, further comprises the steps of:

and S4, attaching a release film 30 to one side of the adhesive film layer 20, which is far away from the copper foil layer 10.

The shielding tape 100 is convenient to roll, store, transport and the like by attaching the release film 30 to the side of the adhesive film layer 20 away from the copper foil layer 10.

In the shielding structure of the embodiment of the present application, in order to make the shielding tape 100 die-cut into the shielding rubber block 300, the conductive fiber 222 in the shielding rubber block 300 can substantially cross over the frame 201, so as to achieve the above cut-off waveguide effect, and the relationship is required to be satisfied: l is greater than w, wherein L is the length of the conductive fibers 222 in the shielding tape 100 (not die-cut), and w is the width of the frame 201.

More preferably, in order to ensure that more conductive fibers 222 in the die-cut shielding adhesive block 300 cross over the frame 201, on the premise that the general orientation arrangement of the conductive fibers 222 is satisfied,

。

specifically, in some embodiments, when the shielding tape 100 is die-cut into the shielding adhesive block 300, the shielding adhesive block 300 is generally in a square frame shape, so that each edge of the shielding adhesive block 300 is intersected with the preset direction at an included angle of 40-50 degrees, and more conductive fibers 222 in the shielding adhesive block 300 can be ensured to cross the frame 201. Taking the rectangular shielding rubber block 300 as an example, during die cutting, it is generally required to set an angle between a die cutting angle and a preset direction to be β, specifically as shown in fig. 3, where β is specifically 40 ° -50 °.

Illustratively, the die cutting angle is 45 ° ± 2 ° to the predetermined direction, i.e. β ≈ 45 °.

In the prior art, when the frame 201 is very narrow, especially when the width w of the frame 201 is not greater than 2 mm, it is very difficult to combine the shielding effect and the bonding stability of the adhesive film layer 20, and when the frame is very narrow, the situation of signal leakage caused by unstable bonding is very easy to occur; in the shielding structure in this embodiment, by using the shielding rubber block, a good shielding effect and good bonding stability can be ensured when the frame 201 is narrow.

In some embodiments, the longer the conductive fibers 222 in the adhesive film layer 20 (before die cutting) is theoretically as long as possible based on the narrow frame 201 having a width of less than or equal to 2 mm, but in order to achieve the shielding effect and the preparation process of the shielding tape 100 easily, the conductive fibers 222 in the adhesive film layer 20 (before die cutting) are preferably: l is more than or equal to 3 mm and less than or equal to 10 mm.

The shielding tape 100 and the shielding structure of the present application are further described in detail with specific embodiments, the shielding tape 100 is manufactured by the above-mentioned doctor blade coating method, the shielding structure includes a shielding adhesive block 300, and the shielding adhesive block 300 is manufactured by die cutting the shielding tape 100; the following examples are illustrative and not limiting of the present application.

Meanwhile, relevant comparative examples are listed for comparison, the shielding tapes in the following comparative examples are also manufactured by means of knife coating, and the shielding structure in the comparative examples also includes shielding adhesive blocks, and the shielding adhesive blocks are formed by die cutting of the shielding tapes in the comparative examples.

Example 1

Referring to fig. 1, the shielding tape 100 of the embodiment includes a copper foil layer 10 and an adhesive film layer 20 stacked on each other, the copper foil layer 10 has a thickness of 12 μm, the adhesive film layer 20 has a thickness of 10 μm, conductive particles 221 and conductive fibers 222 in the adhesive film layer 20 are arranged in a single-layer staggered manner, the content of the conductive particles 221 in the adhesive film layer 20 is 5wt%, the content of the conductive fibers 222 in the adhesive film layer 20 is 5wt%, the particle size of the conductive particles 221 is 10 μm, the diameter of the conductive fibers 222 is 10 μm, and the length of the conductive fibers 222 is 1.2 mm.

Example 2

The shielding tape 100 of the present embodiment is different from embodiment 1 only in that: wherein the length of the conductive fibers 222 is 3.0 mm. The rest is the same as example 1, and is not described herein.

Comparative example 1

The masking tape 100 of this comparative example differs from example 1 only in that: wherein the conductive fibers 222 have a length of 0.8 mm. The rest is the same as example 1, and is not described herein.

Comparative example 2

The shielding tape 100 of the present comparative example is different from example 1 only in that: the content of the conductive particles 221 in the adhesive film layer 20 is 10wt%, and the content of the conductive fibers 222 in the adhesive film layer 20 is 5wt%. The rest is the same as embodiment 1, and the description is omitted here.

Comparative example 3

The masking tape 100 of this comparative example differs from example 1 only in that: the content of the conductive particles 221 in the adhesive film layer 20 is 5wt%, and the content of the conductive fibers 222 in the adhesive film layer 20 is 10wt%. The rest is the same as example 1, and is not described herein.

Comparative example 4

The masking tape 100 of this comparative example differs from example 1 only in that: the diameter of the conductive fiber 222 is 4 μm, and the conductive particles 221 and the conductive fiber 222 are not arranged in a single layer in the adhesive film layer 20, and partially overlap in height. The rest is the same as embodiment 1, and the description is omitted here.

Comparative example 5

The masking tape 100 of this comparative example differs from example 1 only in that: the conductive particles 221 have a particle size of 3 μm, and the conductive particles 221 and the conductive fibers 222 are not arranged in a single layer in the adhesive film layer 20, and partially overlap in height. The rest is the same as embodiment 1, and the description is omitted here.

In order to evaluate the shielding tapes 100 of the above examples and comparative examples, the peeling force of the shielding tapes 100 of the examples and comparative examples and the shielding effectiveness thereof when applied to the shielding structure were tested.

And (3) testing the peeling force:

refer to "test method for 180 ° peel strength of pressure sensitive adhesive tape" GB/T2792-1998; the main test steps comprise: firstly, sampling and cutting a to-be-detected sample with the width of 25 mm; secondly, according to the number of samples, wiping a corresponding number of steel plates and press rollers by using absolute ethyl alcohol, keeping the steel plates and the press rollers clean, and smoothly attaching the samples to the cleaned steel plates at a constant speed by using a 2KG press roller; thirdly, the attached sample to be tested is required to be free of bubbles and is placed in a standard environment (the temperature is 23 +/-2 ℃ and the humidity is 50 +/-5%) for standing for 20 to 30min; fourthly, one end of the torn sample is a free end, the free end is folded in half by 180 degrees relative to the bonding surface, and the free end of the sample and the steel plate are respectively connected to the upper clamp holder and the lower clamp holder; fifthly, continuously stripping the upper gripper at a certain descending speed, and automatically recording a stripping curve.

And (3) testing shielding effectiveness:

to better verify the performance of the shielding tape 100 in practical applications, the shielding effectiveness of the shielding tape is tested by using a shielding effectiveness testing platform 700 shown in fig. 7. The shielding effectiveness testing platform 700 includes: the radio frequency simulation antenna assembly 701 and the network analyzer 702, wherein the network analyzer 702 is specifically selected to be Keysight E5071C; the radio frequency analog antenna module 701 includes a transmitting module 7011 and a receiving module 7012 which are arranged in opposite intervals; the transmitting module 7011 includes a substrate and a radio frequency antenna disposed on the substrate, the radio frequency antenna is disposed on a side facing the receiving module, a shielding support is soldered around the radio frequency antenna, a frame is disposed on a top of the shielding support, and as shown in fig. 4, the frame has a width of 1 mm; the receiving module 7012 includes a substrate and a receiving antenna (not specifically shown in the drawings) disposed on the substrate, the receiving antenna being disposed on a side facing the transmitting module; the substrate of the transmitting module 7011 and the substrate of the receiving module 7012 are both made of FR4 epoxy resin, and the two are fixed by a low-loss plastic material, so that a distance between the two is 10 mm, the transmitting module 7011 is connected to an output port of the network analyzer 702, and the receiving module 7012 is connected to an input port of the network analyzer.

In each set of experiments, the specific steps included:

firstly, when no shielding material is attached to the frame of the shielding bracket, the network analyzer 702 outputs a signal with a test analog frequency of 1GHz to the transmitting module 7011, and the sweep frequency test S is performed through network analysis ₁₂ A parameter, the test result being the radiation intensity of the radio frequency antenna;

secondly, cutting a shielding rubber block with the size consistent with the outline of the frame on the shielding adhesive tape, adhering the shielding rubber block on the frame, rolling the shielding rubber block once back and forth by using a rubber compression roller with the mass of 500g to accelerate the infiltration of a rubber film layer on the frame so as to achieve ideal bonding strength and Z-direction conductivity, and placing for 20 minutes at room temperature; and testing S when the shielding rubber block is attached according to the first step ₁₂ A parameter;

and thirdly, calculating the difference obtained by subtracting the initial radiation intensity measured in the first step from the parameter obtained in the second step, so as to represent the shielding effectiveness of the shielding adhesive tape.

Specific test results are shown in table 1.

[ TABLE 1 ]

From table 1, it can be seen that:

the peel force of the shield tape 100 of examples 1 and 2 and comparative example 1 was substantially the same; when the shielding tape 100 of example 1 is applied to a shielding structure, the shielding effectiveness is significantly better than that of comparative example 1, and the shielding effectiveness of example 2 is further better than that of example 1. It can be seen that, under the premise of keeping the content of the conductive fillers 22 the same, the conductive fibers 222 being arranged in a single layer, and the conductive fibers 222 being arranged in a substantially controlled manner, the adhesive properties of the adhesive film layer 20 are substantially the same, and when the length of the conductive fibers 222 is greater than the width w of the frame, the shielding effectiveness can be substantially ensured, and as the length of the conductive fibers 222 is further increased to the width w of the frame, the shielding effectiveness can be further ensured

In this case, the excellent shielding performance can be further ensured.

In addition, compared with example 1, the shielding effectiveness of comparative examples 2 and 3 is substantially equivalent, while the peeling force of comparative examples 2 and 3 is significantly lower than that of example 1; therefore, on the premise of ensuring that the conductive particles 221 and the conductive fibers 222 are arranged in a single layer in the adhesive film layer 20 and that the conductive fibers 222 are arranged in a substantially controlled manner, increasing the content of the conductive particles 221 or the conductive fibers 222 in the adhesive film layer 20 does not correspondingly affect the shielding performance greatly, but rather greatly reduces the peeling force, i.e., the conductive filler 22 with a high content is not required to maintain the shielding performance and the bonding force.

In addition, compared with example 1, the peeling force of comparative examples 4 and 5 is substantially equivalent, but the shielding effectiveness is significantly worse than that of example 1; therefore, on the premise of ensuring the same content of the conductive particles 221 and the conductive fibers 222 in the adhesive film layer 20, the shielding effectiveness is greatly improved compared to the case where the conductive particles 221 and the conductive fibers 222 are overlapped in the height direction.

In summary, according to the shielding tape 100, the preparation method thereof and the shielding structure of the embodiment of the application, the adhesive film layer 20 in the shielding tape 100 is thin, and the thickness is only 5 to 15 μm, so that it can be ensured that the overall leakage at the position of the adhesive film layer 20 is less; in addition, the diameter of the conductive fiber 222 and the particle size of the conductive particle 221 are substantially consistent with the thickness of the adhesive film layer 20, and are arranged in a single layer in the adhesive film layer 20, the conductive fiber 222 is in a flat shape and is controlled and arranged substantially along the same direction, and a section of slot antenna and a cut-off waveguide effect can be superposed, so that the signal leakage through the adhesive film layer 20 is very limited; on this basis, only need set up about 3wt% ~10wt% electrically conductive filler 22 and just can realize better shielding effect to guarantee reliable stable adhesion, avoid producing the signal that the space leads to because of the adhesion is unstable and reveal, further guarantee the stability of shielding effect, the narrower situation of frame 201 of specially adapted shield support 200.

This written description discloses the application with reference to the drawings, and also enables one skilled in the art to practice the application, including making and using any devices or systems, using suitable materials, and using any incorporated methods. The scope of the present application is defined by the claims and includes other examples that occur to those skilled in the art. Such other examples are to be considered within the scope of the claims as long as they include structural elements that do not differ from the literal language of the claims, or that they include equivalent structural elements with insubstantial differences from the literal language of the claims.

Claims

1. A shielding structure, comprising:

the shielding bracket is provided with a frame on the top; and

the shielding rubber block is formed by die cutting of a shielding rubber tape;

the shielding tape includes:

a copper foil layer; and

the adhesive film layer is arranged on one side of the copper foil layer in a laminated mode, the adhesive film layer comprises an adhesive main body and conductive fillers, the conductive fillers account for 3wt% -10 wt% of the adhesive film layer, the conductive fillers comprise conductive particles and conductive fibers, the conductive particles are spherical or quasi-spherical, the conductive fibers are in a flat lying state, the conductive particles and the conductive fibers are mutually staggered and arranged in the adhesive main body in a single-layer mode, and at least 90% of the conductive fibers and a preset direction form an included angle of 0-30 degrees; the glue film layer satisfies the following relational expression:

h=5~15μm，d=h±2μm，D=h±2μm；

wherein h is the thickness of the adhesive film layer, D is the particle size of the conductive particles, and D is the diameter of the conductive fibers;

the edges of the shielding rubber blocks intersect with the preset direction in included angles of 40-60 degrees, the outer contour of each shielding rubber block is matched with the outer contour of the frame, and one surface of the rubber film layer, which is far away from the copper foil layer, is aligned and stuck on the frame;

satisfy the relation: and L is more than w, and w is less than or equal to 2 mm, wherein L is the length of the conductive fibers in the shielding tape, and w is the width of the frame.

2. The shielding structure of claim 1, wherein the conductive particles are present in an amount of 2wt% to 5wt% in the adhesive film layer, and the conductive fibers are present in an amount of 2wt% to 5wt% in the adhesive film layer.

3. The shielding structure of claim 1, wherein the conductive particles comprise at least one of Ni, ni-C composite, ag, and the conductive fibers comprise at least one of carbon fibers and carbon tubes with a nickel layer on the outer surface.

4. The shielding structure of claim 1, wherein the copper foil layer has a thickness of 9 to 18 μm.

5. The shielding structure of claim 1, wherein the relationship:

。

6. the shielding structure of claim 5, wherein each edge of the shielding tape block intersects the predetermined direction at an angle of 40 ° to 50 °.

7. The shielding structure of claim 6, wherein the relationship: l is more than or equal to 3 mm and less than or equal to 10 mm.