CN114938618A

CN114938618A - Electromagnetic shielding cover, circuit board, electronic equipment and preparation method of electromagnetic shielding cover

Info

Publication number: CN114938618A
Application number: CN202210613133.0A
Authority: CN
Inventors: 周街胜; 李勇; 张美娟; 杨伟帆; 苏陟
Original assignee: Guangzhou Fangbang Electronics Co Ltd
Current assignee: Guangzhou Fangbang Electronics Co Ltd
Priority date: 2022-05-31
Filing date: 2022-05-31
Publication date: 2022-08-23

Abstract

The invention relates to the technical field of electronics, and discloses an electromagnetic shielding cover, a circuit board, electronic equipment and a preparation method of the electromagnetic shielding cover, wherein the electromagnetic shielding cover comprises a carrier layer, a metal layer and a glue film layer; the carrier layer is arranged on one surface close to the metal layer, and the adhesive film layer is arranged on the other surface close to the metal layer; the metal layer has a first shrinkage stress, and when the electromagnetic shielding case is attached to the surface of the electronic component, the first shrinkage stress is used for providing a reducing force for resisting deformation/fracture of the metal layer. The invention can effectively solve the technical problem that the metal layer is easy to deform/break when the electromagnetic shielding cover is attached to the surface of the electronic component, and the metal layer has shrinkage stress to resist the deformation/break of the metal layer in the using process, thereby effectively improving the elongation of the metal layer and ensuring the shielding performance of the electromagnetic shielding cover.

Description

Electromagnetic shielding cover, circuit board, electronic equipment and preparation method of electromagnetic shielding cover

Technical Field

The invention relates to the technical field of electronics, in particular to an electromagnetic shielding cover, a circuit board, electronic equipment and a preparation method of the electromagnetic shielding cover.

Background

Electronic components in the electronic equipment can continuously emit useless electromagnetic wave signals under the working state, and the useless electromagnetic wave signals can influence the normal work of other adjacent electronic components to generate electromagnetic interference. In this regard, a common solution is to encapsulate electronic components to be shielded with a shield case made of a metal material to suppress leakage of unwanted electromagnetic wave signals to the outside.

A typical shield case includes a shield frame and a shield cover, and the thickness of the shield frame, the thickness of the shield cover, the step height of the electronic component, and the gap between the shield case and the electronic component may make the volume of the electronic device having the shield case large. In recent years, electronic devices have been increasingly miniaturized and thinned, and for example, microelectronic devices that are small in size, highly integrated, and have a high-density flexible printed circuit board built therein are often used as electronic components in smart mobile devices represented by mobile phones, which has made higher demands for processing and manufacturing of electronic devices.

In order to shield the electromagnetic interference of the microelectronic device, the closely-fitted shielding case on the electronic component can greatly reduce the volume of the shielding case, however, the shielding case is required to have excellent electrical and magnetic properties, and the metal layer in the electromagnetic shielding case is also required to bear certain mechanical stress, so that the metal layer is prevented from being deformed and broken when the electromagnetic shielding case is fitted on the electronic component.

Currently, there is less research on the problems of deformation and fracture of the metal layer of the shielding case on the microelectronic device during the bonding process. How to guarantee the stability of metal level in the laminating in-process, improve the percentage elongation of metal level, prevent the metal level fracture, guarantee subsequent shielding performance is the problem that the pendulum need to solve in the face of this trade technical staff urgently.

Disclosure of Invention

The invention provides an electromagnetic shielding cover, which can effectively solve the problem that a metal layer is easy to deform/break when the electromagnetic shielding cover is attached to the surface of an electronic component by designing the metal layer with shrinkage stress, effectively improve the elongation of the metal layer and ensure the shielding performance of the electromagnetic shielding cover.

In order to solve the above technical problem, an embodiment of the present invention provides an electromagnetic shielding case, including a carrier layer, a metal layer, and a glue film layer;

the carrier layer is arranged on one surface close to the metal layer, and the adhesive film layer is arranged on the other surface close to the metal layer;

the metal layer has a first shrinkage stress, and when the electromagnetic shielding case is attached to the surface of the electronic component, the first shrinkage stress is used for providing a reducing force for resisting deformation/fracture of the metal layer.

Preferably, the carrier layer has a second shrinkage stress, and the first shrinkage stress of the metal layer is obtained by force transmission of the carrier layer to the metal layer under the influence of the second shrinkage stress.

As one preferable scheme, the electromagnetic shielding case further comprises an adhesive layer;

the adhesive layer is arranged between the carrier layer and the metal layer.

As a preferable scheme, a convex structure is formed on one surface of the adhesive layer close to the metal layer.

As one of preferable solutions, the protruding structure includes conductive particles; alternatively, the raised structures comprise non-conductive particles.

As one preferable scheme, the electromagnetic shielding case further comprises a black film layer;

the black film layer is arranged between the carrier layer and the adhesive layer.

As a preferable scheme, the carrier layer is a metal material, wherein the metal material is one of copper, aluminum, nickel, titanium, chromium and silver; or the metal material is an alloy formed by at least two of copper, aluminum, nickel, titanium, chromium and silver.

As a preferable scheme, the carrier layer is made of a non-metal material, wherein the non-metal material is a PET film, an epoxy resin film or a polyamide resin film.

Preferably, the support layer has a thickness of 8 to 12 μm.

Preferably, the metal layer has a thickness of 0.2 to 5 μm.

Preferably, the thickness of the adhesive film layer is 5-15 microns.

Another embodiment of the present invention provides a circuit board, including a printed circuit board and the electromagnetic shield as described above;

the printed circuit board is provided with an electronic component, and the electromagnetic shielding cover is attached to the surface of the electronic component.

Yet another embodiment of the present invention provides an electronic device including the wiring board as described above.

Another embodiment of the present invention provides a method for manufacturing an electromagnetic shielding case, including:

preparing and forming a carrier layer;

processing and forming a metal layer on one surface of the carrier layer, wherein the metal layer has a first shrinkage stress, and the first shrinkage stress is used for providing a reducing force for resisting deformation/fracture of the metal layer when the electromagnetic shielding case is attached to the surface of an electronic component;

and forming an adhesive film layer on one surface of the metal layer, which is far away from the carrier layer.

As one preferable scheme, a metal layer is processed and formed on one surface of the carrier layer, wherein the metal layer has a first shrinkage stress, and when the electromagnetic shielding case is attached to the surface of an electronic component, the first shrinkage stress is used for providing a reducing force for resisting deformation/fracture of the metal layer, and the method specifically includes:

exerting pre-tensioning stress on the carrier layer to form the carrier layer in a stretching state;

and after the metal layer and the adhesive film layer are sequentially processed and formed, releasing the pre-stretching stress to enable the carrier layer to generate a shrinkage stress corresponding to the pre-stretching stress and transmit the shrinkage stress to the metal layer.

Compared with the prior art, the embodiment of the invention has the advantages that at least one point is as follows:

(1) structural designs of a shielding frame and a shielding cover of a shielding case in the prior art are abandoned, and the electromagnetic shielding case is tightly attached to the surface of an electronic component, so that the volume of electronic equipment with the shielding case is greatly reduced, and the development process of miniaturization and lightness and thinness of the electronic equipment is further promoted;

(2) designing shrinkage stress on the metal layer to be in a tightening state, wherein when the electromagnetic shielding cover is attached to the surface of the electronic component, the shrinkage stress in the metal layer corresponds to tensile stress of the metal layer caused by pressing the electromagnetic shielding cover in the attaching process, and the shrinkage stress and the tensile stress compensate each other to reduce the metal layer without generating deformation and fracture of the metal layer, so that the shielding performance of the electromagnetic shielding cover is ensured;

(3) when the step height of the electronic component is large (for example, the step height is 0.3-1mm), the metal layer with the shrinkage stress can ensure that the electromagnetic shielding cover is stably attached to the surface of the electronic component, so that the phenomenon that the shielding effect is weakened or fails due to the fact that the metal layer is broken at the step is effectively prevented, and the elongation of the metal layer is relatively improved.

Drawings

Fig. 1 is a schematic structural view of an electromagnetic shield in one embodiment of the present invention;

fig. 2 is a schematic flow chart of a method for manufacturing an electromagnetic shielding can according to one embodiment of the present invention;

fig. 3 is a schematic flow chart of a portion of a method for manufacturing an electromagnetic shield in accordance with one embodiment of the present invention;

fig. 4 is a schematic structural diagram of an electromagnetic shielding case according to a first embodiment of the present invention;

fig. 5 is a schematic structural diagram of an electromagnetic shield according to a second embodiment of the present invention;

fig. 6 is a schematic structural diagram of an electromagnetic shield according to a third embodiment of the present invention;

reference numerals:

wherein, 1, a carrier layer; 2. a metal layer; 3. a glue film layer; 4. an adhesive layer; 5. and (5) a black film layer.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is to be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments, and the embodiments are provided for the purpose of making the disclosure of the present invention more thorough and complete. 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 are used in an orientation or positional relationship indicated based on the orientation or positional relationship shown in the drawings, which is for convenience in describing the embodiments of the present invention, and do not indicate or imply that the device or component being referred to must have a particular orientation, be constructed in a particular orientation, and be operated in a particular manner, and therefore, should not 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 one technical feature from another, and are not to be construed as indicating or implying relative importance or to imply that the indicated technical features are in number, nor necessarily order or temporal order. The terms are interchangeable where appropriate. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the feature.

In the description of the present application, it is to be noted that, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention, as those skilled in the art will recognize the specific meaning of the terms used in the present application in a particular context.

Specifically, referring to fig. 1, fig. 1 shows a schematic structural diagram of an electromagnetic shielding case in one embodiment of the present invention, which includes a carrier layer 1, a metal layer 2, and a film layer 3.

Wherein, carrier layer 1 is located on the one side that is close to metal level 2, and glue film layer 3 is located and is close to on the another side of metal level 2, promptly, top-down, electromagnetic shield cover includes carrier layer 1, metal level 2 and glue film layer 3 in proper order.

For the metal layer 2, because the metal layer is made of a metal material, the metal material has certain rigidity and toughness, and can only be bent and deformed within a small scale range and keep the structural integrity of the metal layer, if the acting force applied to the metal layer 2 is too high, the metal layer 2 is easy to deform and even break, especially when the step height of an electronic component on a circuit board is large, for example, the step height is 0.3-1mm, if the electromagnetic shielding cover is directly attached to the surface of the component, a large gap is inevitably left between the electromagnetic shielding cover and the component, and under the influence of the external attaching acting force, the phenomenon is easy to cause the metal layer 2 to deform greatly in the gap to break, so that the whole shielding cover is not conducted, and the shielding effect is invalid or weakened.

Therefore, in the embodiment of the invention, the metal layer 2 is improved, wherein the metal layer 2 has the first shrinkage stress, when the electromagnetic shielding case is attached to the surface of the electronic component, the first shrinkage stress in the metal layer 2 corresponds to the tensile stress of the metal layer 2 caused by pressing the electromagnetic shielding case in the attaching process, and the first shrinkage stress and the tensile stress compensate each other, so that the metal layer 2 is reduced, and the phenomena of deformation and breakage of the metal layer 2 are not generated, thereby ensuring the shielding performance of the electromagnetic shielding case.

Correspondingly, an embodiment of the present invention provides a method for manufacturing an electromagnetic shielding case, specifically, referring to fig. 2, fig. 2 is a schematic flow chart of the method for manufacturing an electromagnetic shielding case according to an embodiment of the present invention, which includes:

s1, preparing and forming a carrier layer;

s2, processing and forming a metal layer on one surface of the carrier layer, wherein the metal layer has a first shrinkage stress, and the first shrinkage stress is used for providing a reducing force for resisting the deformation/fracture of the metal layer when the electromagnetic shielding case is attached to the surface of an electronic component;

and S3, forming a film adhesive layer on one surface of the metal layer far away from the carrier layer.

The metal layer has a first shrinkage stress as a core improvement point of the present invention, which is implemented in various ways, and a principle description of a preferred embodiment is provided herein:

considering that the electromagnetic shielding case is a compact structure, the carrier layer and the metal layer are bound to each other tightly, so the carrier layer can have the second shrinkage stress at first, and the carrier layer, the metal layer and the adhesive film layer are all tightly connected, so the second shrinkage stress can be stably transmitted to the middle metal layer, and the metal layer also has the shrinkage stress, that is, the metal layer has the first shrinkage stress.

Correspondingly, in order to achieve the effect that the carrier layer has the second shrinkage stress at the beginning, in the actual manufacturing process, it is preferable to achieve the step shown in fig. 3, and fig. 3 is a schematic flow chart of a part of the method for manufacturing the electromagnetic shielding case in one embodiment of the present invention, which includes:

s21, exerting pre-stretching stress on the carrier layer to form the carrier layer in a stretching state;

s22, sequentially processing the metal layer and the adhesive film layer on the carrier layer in a stretching state;

and S23, releasing the pre-tensioning stress.

After the carrier layer is prepared, exerting a pretension stress on the carrier layer, wherein the carrier layer is in a non-conservative state of force and takes on a state such as stretching, on the basis of which the pretension stress is kept, processing and forming the metal layer and the rubber film layer on the carrier layer in the stretching state in sequence, wherein the metal layer and the rubber film layer are in a conservative state of force because of not receiving the force, releasing the pretension stress after processing and finishing the three-layer structure, wherein the acting force and the reacting force between the objects are always equal in magnitude and opposite in direction according to Newton's third law, so that the carrier layer can generate a shrinkage stress (namely the second shrinkage stress) opposite to the pretension stress, and the metal layer is tightly combined with the carrier layer in the stretching state because the metal layer is processed on the carrier layer in the stretching state, the force is transmitted to the metal layer of the lower layer according to the force transmission function, so that the metal layer also generates a shrinkage stress (namely, the first shrinkage stress).

Of course, in addition to the above-mentioned "applying a pre-stretching stress to the carrier layer, and obtaining the first shrinkage stress by the subsequent force cancellation and the force transmission action", those skilled in the art may also apply a pressing process to the metal layer in advance to generate a shrinkage stress therein, which is not described herein again.

In the above embodiments, the tight connection between the carrier layer and the metal layer is an important guarantee for achieving the force transmission, and therefore, preferably, the electromagnetic shielding can further comprises an adhesive layer disposed on a side of the carrier layer close to the metal layer, that is, the adhesive layer is disposed at a position between the carrier layer and the metal layer.

To facilitate understanding, the following description describes four specific embodiments to further explain the principles of the present invention, and it should be noted that the carrier layer and the metal layer in this embodiment are deformed under the influence of an applied force, and different applied force directions can generate different deformation states (stretching or tightening) to cause the length of the carrier layer or the metal layer to change. Of course, the length variation is only for the purpose of more conveniently explaining the principle in the present embodiment, and it should be noted that, as electronic components are going to be ultra-thin and ultra-small, the thickness of the metal layer involved therein is also reduced from the micrometer scale level to the submicron or even nanometer scale level, so that some metal layers may not be deformed visible to the naked eye under the influence of external force, that is, the length of the metal layer may not be changed, and those skilled in the art can know that the present invention is an improved form taking "force" rather than "length change" as a core.

The first embodiment is as follows:

referring to fig. 4, fig. 4 is a schematic structural diagram of an electromagnetic shielding case according to a first embodiment of the present invention, where the electromagnetic shielding case includes a four-layer structure, which includes a carrier layer 1, an adhesive layer 4, a metal layer 2, and an adhesive layer 3 from top to bottom.

The actual preparation process comprises the following steps:

the carrier layer 1 is obtained through a carrier layer preparation process, the raw material of the carrier layer 1 is a metal material, the metal material is one of copper, aluminum, nickel, titanium, chromium and silver, and the preparation thickness of the carrier layer 1 is 10 microns;

after the solid carrier layer 1 is obtained, a stretching force (pre-stretching stress) is applied to the carrier layer 1 through a stretching mechanism, specifically, the stretching force is used for stretching the two end parts of the carrier layer 1 to the outside, at this time, the length of the carrier layer 1 is lengthened under the action of force, and a stretching state is presented, it should be noted that the specific value of the stretching force needs to be selected according to factors such as the material and the actual length of a product.

After that, an adhesive layer 4 is provided under the carrier layer 1, the adhesive layer 4 having a thickness of 0.8 micrometer. Specifically, the material of the adhesive layer 4 may be bisphenol a type epoxy resin, acrylic resin, polyester resin, or the like. In addition, the resin used may be any one or a mixture of at least two selected from the group consisting of epoxy resin, cyanate resin, polyphenylene ether resin, polybutadiene resin, styrene-butadiene resin, bismaleimide-triazine resin (BT), bismaleimide resin, polytetrafluoroethylene resin, polyimide resin, phenol resin, acrylic resin, liquid crystal resin, benzoxazine resin, phenoxy resin, nitrile rubber, carboxyl-terminated nitrile rubber, and hydroxyl-terminated nitrile rubber, but not limited thereto, and all of the resin materials disclosed in the prior art may be used. Such as a mixture of an epoxy resin and a cyanate resin, a mixture of a polyphenylene ether resin and a polybutadiene resin, a mixture of a styrene-butadiene resin and a BT resin, a mixture of a polytetrafluoroethylene resin and a polyimide resin, a mixture of a phenol resin and an acrylic resin, a mixture of an epoxy resin, a cyanate resin and a polyphenylene ether resin, a polybutadiene resin, a styrene-butadiene resin and a BT resin, and a mixture of a polytetrafluoroethylene resin, a polyimide resin, a phenol resin and an acrylic resin, that is, a mixture of two or more resins may be used.

And then, covering a metal layer 2 on the bottom of the adhesive layer 4, wherein the thickness of the metal layer 2 is 0.8 microns, and the metal layer 2 can be copper, aluminum and other metals with better ductility and thermal conductivity. The metal layer 2 may be sputtered, plated or otherwise applied to the adhesive layer 4 at a bottom position thereof.

And then, a glue film layer 3 is adhered to the bottom of the metal layer 2, and the thickness of the glue film layer 3 is 5 microns.

After the carrier layer 1, the adhesive layer 4, the metal layer 2 and the adhesive film layer 3 are obtained, the tensile acting force applied to the carrier layer 1 is removed, at the moment, the shrinkage stress can appear in the carrier layer 1 due to the interaction of the forces, specifically, the shrinkage stress is 0.03-2.93N/cm, and the carrier layer 1, the adhesive layer 4 and the metal layer 2 are tightly combined, so that the shrinkage stress can be gradually transmitted downwards, namely, the adhesive layer 4 also has the shrinkage stress, and then the metal layer 2 also has the shrinkage stress, so that the preparation process of the electromagnetic shielding cover is completed, wherein the metal layer 2 of the electromagnetic shielding cover has certain shrinkage stress, the length of the metal layer is shortened, and the electromagnetic shielding cover presents a tightening state.

In the practical use process, the electromagnetic shielding cover needs to be pressed on the surface of the electronic component on the circuit board, at the moment, under the external pressing process, the metal layer 2 in the shrinkage state is attached to the surface of the component and is affected by the pressing process, and the metal layer 2 in the electromagnetic shielding cover can be subjected to the external pressure, so that the length of the metal layer 2 develops towards the trend of lengthening.

The second embodiment is as follows:

referring to fig. 5, fig. 5 is a schematic structural diagram of an electromagnetic shielding case according to a second embodiment of the present invention, where the electromagnetic shielding case includes five layers, which are, from top to bottom, a carrier layer 1, a black film layer 5, an adhesive layer 4, a metal layer 2, and an adhesive layer 3. The actual preparation process comprises the following steps:

the carrier layer 1 is obtained through a carrier layer preparation process, the raw material of the carrier layer 1 is a metal material, the metal material is an alloy formed by at least two of copper, aluminum, nickel, titanium, chromium and silver, and the preparation thickness of the carrier layer 1 is 12 micrometers.

After obtaining the solid carrier layer 1, a stretching force is applied to the carrier layer 1 by a stretching mechanism as in the first embodiment, which is described in detail in the first embodiment.

And then, arranging a black film layer 5 below the carrier layer 1, wherein the thickness of the black film layer 5 is 15 microns, and the black film layer 5 is a protective layer and plays a further role in structural support for the whole electromagnetic shielding case. The black film layer 5 is made of thermoplastic adhesive, thermosetting adhesive or pressure-sensitive adhesive.

The adhesive layer 4, the metal layer 2 and the adhesive film layer 3 can be seen from the specific process of the first embodiment. Different from the first embodiment, the thickness of the adhesive layer 4 in the present embodiment is 1.0 micron, the thickness of the metal layer 2 is 5 micron, and the thickness of the adhesive film layer 3 is 15 micron

After the carrier layer 1, the black film layer 5, the adhesive layer 4, the metal layer 2 and the adhesive film layer 3 are obtained, the tensile acting force applied to the carrier layer 1 is removed, at the moment, shrinkage stress can occur in the carrier layer 1 due to the interaction of forces, and the carrier layer 1, the black film layer 5, the adhesive layer 4 and the metal layer 2 are tightly combined, so that the shrinkage stress can be gradually transmitted downwards, namely, the black film layer 5 also has the shrinkage stress, the adhesive layer 4 also has the shrinkage stress, and then the metal layer 2 also has the shrinkage stress, so far, the preparation process of the electromagnetic shielding cover is completed, wherein the metal layer 2 of the electromagnetic shielding cover has certain shrinkage stress, the length of the metal layer is shortened, and a tightening state is presented.

In the actual use process, as in the first embodiment, the length of the metal layer 2 returns to normal under the action of one drawing and one retracting, and the metal layer 2 is restored without deformation or fracture, so that the shielding performance of the electromagnetic shielding case is guaranteed.

The third concrete embodiment:

referring to fig. 6, fig. 6 is a schematic structural diagram of an electromagnetic shielding case according to a third embodiment of the present invention, and like the second embodiment, in the present embodiment, the electromagnetic shielding case includes five layers, which are, from top to bottom, a carrier layer 1, a black film layer 5, an adhesive layer 4, a metal layer 2, and an adhesive layer 3.

The carrier layer 1 is obtained through a carrier layer preparation process, the raw material of the carrier layer 1 is a non-metal material, and the non-metal layer can be a PET film, an epoxy resin film or a polyamide resin film. The support layer 1 in this example was prepared to a thickness of 11 microns.

After the carrier layer 1 in a solid state is obtained, a stretching force is applied to the carrier layer 1 by a stretching mechanism, as in the second embodiment, which is described in detail in the second embodiment.

Then, the black film layer 5 and the adhesive layer 4 are processed, and the preparation of the black film layer and the adhesive layer is the same as that of the example, which is not described herein again.

Then, processing the bottom surface of the adhesive layer 4 to form a protruding structure, where the protruding structure may be achieved by adding a filler, and the added filler may be a conductive material or a non-conductive filler, where the conductive filler may be one or more of carbon nanotubes, nanowires, graphene, metal particles, carbon nanotube particles, and ferrite particles, and 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. The non-conductive material may be any one of silicon dioxide, titanium dioxide, aluminum oxide, titanic acid, or a mixture of at least two thereof. Of course, the conductive filler and the non-conductive filler are not limited to the above-described fillers, and all the fillers disclosed in the prior art that can make the adhesive layer have a convex structure may be used.

Furthermore, the raised structure may also be formed by means of etching. The specific corrosive liquid is as follows: dichromate, permanganate, ozone, oxidizing agents such as hydrogen peroxide/sulfuric acid and nitric acid, organic solvents such as N-methyl-2-pyrrolidone, N-dimethylformamide and methoxypropanol, and various alkalis such as sodium hydroxide and caustic potash.

Because the bottom of the adhesive layer 4 is provided with a convex structure, the metal layer 2 can also form the convex structure at the bottom after being connected with the adhesive layer 4, the bottom surface of the metal layer 2 containing the convex structure is adhered with the adhesive film layer 3, and the adhesive film layer 3 is tightly attached to the surface of a component in use.

In addition to the same technical effects as those of the above embodiments, in this embodiment, the shielding cover is pressed on the circuit board with a step height of 0.3-1.0mm by using a special mold under a pressure of less than or equal to 0.5MPa, and the protruding conductive particles of the protruding structure pierce the resin layer, thereby achieving the connection and conduction between the electromagnetic shielding cover and the circuit board.

The fourth concrete embodiment:

in this embodiment, the description will be focused on the manufacturing method of the electromagnetic shielding case, and the specific steps are as follows:

step one, preparing a carrier layer, wherein the thickness of the carrier layer is about 10 microns (the application process of the tensile stress is the same as that of the third embodiment, and the description is omitted);

step two, preparing a black film layer at the bottom of the carrier layer, wherein the thickness of the black film is about 15 microns;

coating an adhesive layer on one side of the black film layer, which is far away from the carrier layer, wherein the surface layer of the dried adhesive layer is a microstructure forming a concave-convex structure; wherein, the adhesive layer is formed by adding resin, solvent and filler together and curing, wherein the filler comprises 30-50 wt%; the thickness of the adhesive layer is 30-70 microns, preferably 35 microns or 65 microns; in addition, the adhesive layer needs to be dried to remove the solvent and volatile components, and the drying temperature is controlled to be 70-140 ℃ for 3-15 min. The adhesive layer may be applied by die coating, bar coating, roll coating, or gravure coating. Preferably, the adhesive layer is coated by a gravure coating method;

and step four, forming a metal layer on one side of the adhesive layer, which is far away from the black film layer, so as to shield the electromagnetic wave. Specifically, the metal layer is directly formed on the adhesive layer by one or more processes of chemical plating, physical vapor deposition, chemical vapor deposition, evaporation plating, sputtering plating, electroplating and mixed plating. Preferably, the thickness of the metal layer is chosen to be 0.8-2 microns.

And step five, adding and mixing the resin, the solvent and the filler together, and coating the mixture on the side of the metal layer far away from the adhesive layer in the step 4 to form an adhesive film layer, wherein the thickness of the adhesive film layer is controlled to be 5-15 micrometers, and preferably 10 micrometers.

And step six, removing the tensile stress, and fixing the electromagnetic shielding cover on the circuit board in a bonding, clamping or screw fixing mode to ensure that the electromagnetic shielding cover is tightly connected without gaps, so that electromagnetic shielding is realized, the overall shielding performance is good, the overall film thickness of the electromagnetic shielding cover is preferably 25-100 micrometers, the size and the occupied space are greatly reduced, and the development process of miniaturization and lightness and thinness of the circuit board is promoted.

Another embodiment of the present invention further provides a circuit board, comprising a printed circuit board and the electromagnetic shielding case according to any one of the above embodiments; the printed circuit board is provided with an electronic component, and the electromagnetic shielding cover is attached to the surface of the electronic component.

Still another embodiment of the present invention further provides an electronic device, which includes the circuit board as described above.

Specifically, the electromagnetic shielding cover is applied to the circuit board in the embodiment of the invention, and the electromagnetic shielding cover abandons the structural design of a shielding frame and a shielding cover of the shielding cover in the prior art, and the electromagnetic shielding cover is tightly attached to the surface of an electronic component, so that the volume of electronic equipment with the shielding cover is greatly reduced, and the development process of miniaturization and lightness and thinness of the electronic equipment is further promoted; more importantly, the metal layer is designed with shrinkage stress to be in a tightening state, when the electromagnetic shielding cover is attached to the surface of an electronic component, the shrinkage stress in the metal layer corresponds to tensile stress of the metal layer caused by pressing the electromagnetic shielding cover in the attaching process, the shrinkage stress and the tensile stress compensate each other, the metal layer is reduced, the metal layer is not deformed and broken, and the shielding performance of the electromagnetic shielding cover is ensured; for the condition that the step height of the electronic component on the circuit board is larger, for example, the step height is 0.3-1mm, the electromagnetic shielding cover in the embodiment of the invention has the metal layer with the shrinkage stress, and can ensure that the electromagnetic shielding cover is stably attached to the surface of the electronic component, so that the phenomenon that the shielding effect is weakened or loses efficacy due to the breakage of the metal layer at the step is effectively prevented, and the elongation of the metal layer is relatively improved.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that various changes and modifications can be made by those skilled in the art without departing from the spirit of the invention, and these changes and modifications are all within the scope of the invention. Therefore, the protection scope of the present patent should be subject to the appended claims.

Claims

1. An electromagnetic shielding case is characterized by comprising a carrier layer, a metal layer and a film adhesive layer;

the metal layer has a first shrinkage stress, and the first shrinkage stress is used for providing a reducing force for resisting deformation/fracture of the metal layer when the electromagnetic shielding case is attached to the surface of an electronic component.

2. The electromagnetic shield of claim 1 wherein said carrier layer has a second shrinkage stress, said first shrinkage stress of said metal layer resulting from the transfer of force of said carrier layer to said metal layer under the influence of said second shrinkage stress.

3. The electromagnetic shield of claim 1, further comprising an adhesive layer;

the adhesive layer is arranged between the carrier layer and the metal layer.

4. The electromagnetic shield of claim 3 wherein said adhesive layer has a raised structure formed on a side thereof adjacent to said metal layer.

5. The electromagnetic shield of claim 4, wherein the raised structures comprise conductive particles; alternatively, the raised structures comprise non-conductive particles.

6. The electromagnetic shield of claim 3, further comprising a black film layer;

7. The electromagnetic shield of claim 1 wherein said carrier layer is a metallic material, wherein said metallic material is one of copper, aluminum, nickel, titanium, chromium, and silver; or the metal material is an alloy formed by at least two of copper, aluminum, nickel, titanium, chromium and silver.

8. The electromagnetic shield of claim 1 wherein said carrier layer is a non-metallic material, wherein said non-metallic material is a PET film, an epoxy film, or a polyamide film.

9. The electromagnetic shield of claim 1 wherein the carrier layer has a thickness of 8-12 microns.

10. The electromagnetic shield of claim 1, wherein the metal layer has a thickness of 0.2-5 microns.

11. The electromagnetic shield of claim 1, wherein the adhesive film layer has a thickness of 5-15 microns.

12. A wiring board comprising a printed wiring board and the electromagnetic shield according to any one of claims 1 to 11;

13. An electronic device characterized in that it comprises the wiring board of claim 12.

14. A method of making an electromagnetic shield, comprising:

preparing and forming a carrier layer;

15. The method for manufacturing an electromagnetic shielding case according to claim 14, wherein a metal layer is formed on one surface of the carrier layer, wherein the metal layer has a first shrinkage stress, and the first shrinkage stress is used to provide a reducing force against deformation/fracture of the metal layer when the electromagnetic shielding case is attached to a surface of an electronic component, and specifically includes: