CN110691499A - Electromagnetic shielding film, circuit board and preparation method of electromagnetic shielding film - Google Patents
Electromagnetic shielding film, circuit board and preparation method of electromagnetic shielding film Download PDFInfo
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- CN110691499A CN110691499A CN201810743107.3A CN201810743107A CN110691499A CN 110691499 A CN110691499 A CN 110691499A CN 201810743107 A CN201810743107 A CN 201810743107A CN 110691499 A CN110691499 A CN 110691499A
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K9/00—Screening of apparatus or components against electric or magnetic fields
- H05K9/0073—Shielding materials
- H05K9/0081—Electromagnetic shielding materials, e.g. EMI, RFI shielding
- H05K9/0088—Electromagnetic shielding materials, e.g. EMI, RFI shielding comprising a plurality of shielding layers; combining different shielding material structure
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J7/00—Adhesives in the form of films or foils
- C09J7/20—Adhesives in the form of films or foils characterised by their carriers
- C09J7/29—Laminated material
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/0213—Electrical arrangements not otherwise provided for
- H05K1/0216—Reduction of cross-talk, noise or electromagnetic interference
- H05K1/0218—Reduction of cross-talk, noise or electromagnetic interference by printed shielding conductors, ground planes or power plane
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J2301/00—Additional features of adhesives in the form of films or foils
- C09J2301/10—Additional features of adhesives in the form of films or foils characterized by the structural features of the adhesive tape or sheet
- C09J2301/16—Additional features of adhesives in the form of films or foils characterized by the structural features of the adhesive tape or sheet by the structure of the carrier layer
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
- H05K2201/07—Electric details
- H05K2201/0707—Shielding
- H05K2201/0715—Shielding provided by an outer layer of PCB
Abstract
The invention relates to the technical field of electronics, and discloses an electromagnetic shielding film, a circuit board and a preparation method of the electromagnetic shielding film, wherein the electromagnetic shielding film comprises a plurality of convex particles, a first shielding layer, a second shielding layer, a third shielding layer and an adhesive film layer which are sequentially stacked, one surface of the first shielding layer, which is close to the adhesive film layer, is set to be a flat surface, and the plurality of convex particles are distributed between the first shielding layer and the second shielding layer and between the second shielding layer and the third shielding layer, so that the surface, which is close to the adhesive film layer, of the third shielding layer forms a non-flat surface, the non-flat surface of the third shielding layer can pierce through the adhesive film layer and is connected with the ground layer of the circuit board when the electromagnetic shielding film is laminated with the circuit board, and the conductive particles of the adhesive film layer are pulled to cause grounding failure when the adhesive film layer of the existing electromagnetic shielding film expands at high temperature, thereby ensuring the ground connection of the electromagnetic shielding film and the circuit board.
Description
Technical Field
The invention relates to the technical field of electronics, in particular to an electromagnetic shielding film, a circuit board and a preparation method of the electromagnetic shielding film.
Background
With the rapid development of the electronic industry, electronic products are further miniaturized, light-weighted and densely assembled, and the development of flexible circuit boards is greatly promoted, so that the integration of element devices and wire connection is realized. 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 for short). 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 containing conductive particles, wherein the shielding layer is grounded and conducted with a ground layer of the circuit board through the adhesive film layer containing the conductive particles, but the adhesive film layer is easy to expand and the conductive particles of the adhesive film layer are pulled apart under high-temperature pressing, so that the shielding layer cannot be grounded and conducted with the ground layer of the circuit board through the adhesive film layer, and the grounding reliability is affected.
Disclosure of Invention
The embodiment of the invention aims to provide an electromagnetic shielding film, a circuit board and a preparation method of the electromagnetic shielding film, which can effectively avoid grounding failure caused by pulling apart of conductive particles of an adhesive film layer when the adhesive film layer of the conventional electromagnetic shielding film expands at high temperature so as to ensure that the electromagnetic shielding film is grounded and interference charges are led out.
In order to solve the above technical problem, an embodiment of the present invention provides an electromagnetic shielding film, including a first shielding layer, N second shielding layers, a third shielding layer, a glue film layer, and a plurality of convex particles; the first shielding layer, the N second shielding layers, the third shielding layer and the adhesive film layer are sequentially stacked; the surface of the first shielding layer, which is close to the adhesive film layer, is a flat surface, the convex particles are distributed between the first shielding layer and the second shielding layer and between the second shielding layer and the third shielding layer, the surface of the third shielding layer, which is close to the adhesive film layer, is a non-flat surface, and the adhesive film layer is arranged on the third shielding layer; wherein N is greater than or equal to 1.
Preferably, the second shielding layer covers the convex particles between the first shielding layer and the second shielding layer to form convex portions, and the second shielding layer covers the convex particles to form concave portions;
the third shielding layer coats the convex particles between the second shielding layer and the third shielding layer to form convex parts, and the third shielding layer coats other positions except the convex particles to form concave parts.
Preferably, the convex portions of the second shielding layer correspond to the convex portions of the third shielding layer one to one, and the concave portions of the second shielding layer correspond to the concave portions of the third shielding layer one to one.
Preferably, a plurality of convex particles are attached to one surface of one or more second shielding layers close to the adhesive film layer.
As a preferred scheme, a conductive protrusion is arranged on one surface of the first shielding layer, which is close to the adhesive film layer; and/or one or more surfaces of the second shielding layers close to the adhesive film layer are provided with conductive protrusions; and/or a conductive protrusion is arranged on one surface, close to the adhesive film layer, of the third shielding layer.
Preferably, the convex particles include one or more of conductor particles, semiconductor particles, insulator particles, and coated composite particles.
Preferably, the adhesive layer comprises an adhesive layer containing conductive particles; or the adhesive film layer comprises an adhesion layer without conductive particles.
The electromagnetic shielding film further comprises a protective film layer, and the protective film layer is arranged on one surface, far away from the adhesive film layer, of the first shielding layer.
In order to solve the same technical problem, an embodiment of the present invention further provides a circuit board, including a circuit board body and the electromagnetic shielding film, wherein the electromagnetic shielding film is laminated with the circuit board body through the adhesive film layer; the third shielding layer pierces through the glue film layer and is electrically connected with the ground layer of the circuit board body.
The embodiment of the invention provides an electromagnetic shielding film and a circuit board, wherein the electromagnetic shielding film comprises a plurality of convex particles, and a first shielding layer, N second shielding layers, a third shielding layer and an adhesive film layer which are sequentially stacked, one surface of the first shielding layer, which is close to the adhesive film layer, is set to be a flat surface, and a plurality of convex particles are distributed between the first shielding layer and the second shielding layer and between the second shielding layer and the third shielding layer, so that the surface of the third shielding layer close to the adhesive film layer forms a non-flat surface, thereby facilitating the uneven surface of the third shielding layer to pierce the adhesive film layer and be connected with the ground layer of the circuit board when the electromagnetic shielding film is laminated with the circuit board, the grounding failure caused by pulling apart of conductive particles of the adhesive film layer when the adhesive film layer of the existing electromagnetic shielding film expands at high temperature is avoided, so that the ground connection of the electromagnetic shielding film and the circuit board is ensured; in addition, when the electromagnetic shielding film is laminated with the circuit board, glue substances forming the glue film layer are extruded into the concave position of the third shielding layer to increase glue capacity, so that the phenomenon of board explosion is not easy to occur, the problem that the high-temperature board explosion is caused due to insufficient glue capacity of the existing electromagnetic shielding film is avoided, and then the grounding of the electromagnetic shielding film is effectively ensured, so that interference charges are led out.
In order to solve the same technical problem, an embodiment of the present invention further provides a method for preparing an electromagnetic shielding film, including the following steps:
forming a first shielding layer; one surface of the first shielding layer is a flat surface;
forming a plurality of convex particles on a flat surface of the first shielding layer;
forming N second shield layers on the first shield layer on which the plurality of convex particles are formed; wherein N is greater than or equal to 1;
forming a plurality of convex particles on the second shielding layer;
forming a third shielding layer on the second shielding layer on which the plurality of convex particles are formed; one surface of the third shielding layer is a non-flat surface;
and forming an adhesive film layer on the non-flat surface of the third shielding layer.
Preferably, after the first shielding layer is formed, the method further includes:
and forming a conductive bump on the flat surface of the first shielding layer.
Preferably, a plurality of convex particles are attached to one surface of one or more second shielding layers close to the adhesive film layer.
Preferably, one or more surfaces of the second shielding layers close to the adhesive film layer are provided with conductive protrusions.
Preferably, after forming a third shielding layer on the second shielding layer on which the plurality of convex particles are formed, the method further includes:
and forming a conductive bump on the non-flat surface of the third shielding layer.
The embodiment of the invention provides a preparation method of an electromagnetic shielding film, which comprises the following steps of firstly, forming a first shielding layer; wherein, one side of the first shielding layer is a flat surface; then, forming a plurality of convex particles on the flat surface of the first shielding layer; forming N second shielding layers on the first shielding layer on which the convex particles are formed; next, forming a plurality of convex particles on the second shield layer, and forming a third shield layer on the second shield layer on which the plurality of convex particles are formed; one surface of the third shielding layer is a non-flat surface; finally, forming an adhesive film layer on the non-flat surface of the third shielding layer, so that the prepared electromagnetic shielding film comprises a plurality of convex particles, and a first shielding layer, N second shielding layers, a third shielding layer and the adhesive film layer which are sequentially stacked, wherein one surface of the first shielding layer, which is close to the adhesive film layer, is set as a flat surface, and a plurality of convex particles are distributed between the first shielding layer and the second shielding layer and between the second shielding layer and the third shielding layer, so that the surface of the third shielding layer close to the adhesive film layer forms a non-flat surface, thereby facilitating the uneven surface of the third shielding layer to pierce the adhesive film layer and be connected with the ground layer of the circuit board when the electromagnetic shielding film is laminated with the circuit board, the grounding failure caused by pulling apart of conductive particles of the adhesive film layer when the adhesive film layer of the existing electromagnetic shielding film expands at high temperature is avoided, so that the ground connection of the electromagnetic shielding film and the circuit board is ensured; in addition, when the electromagnetic shielding film is laminated with the circuit board, glue substances forming the glue film layer are extruded into the concave position of the third shielding layer to increase glue capacity, so that the phenomenon of board explosion is not easy to occur, the problem that the high-temperature board explosion is caused due to insufficient glue capacity of the existing electromagnetic shielding film is avoided, and then the grounding of the electromagnetic shielding film is effectively ensured, so that interference charges are led out.
Drawings
Fig. 1 is a schematic structural view of an electromagnetic shielding film according to a first embodiment of the present invention;
fig. 2 is a schematic structural view of an electromagnetic shielding film according to a second embodiment of the present invention;
fig. 3 is a schematic structural view of an electromagnetic shielding film according to a third embodiment of the present invention;
fig. 4 is a schematic structural view of an electromagnetic shielding film according to a fourth embodiment of the present invention;
FIG. 5 is a schematic structural diagram of a circuit board in an embodiment of the present invention;
FIG. 6 is a schematic structural diagram of another embodiment of a wiring board in an example of the present invention;
fig. 7 is a schematic flow chart of a method for manufacturing an electromagnetic shielding film according to an embodiment of the present invention;
wherein, 1, a first shielding layer; 2. a second shielding layer; 3. a third shielding layer; 4. a glue film layer; 5. a convex particle; 6. a convex portion; 7. a recessed portion; 8. a conductive bump; 9. a protective film layer; 11. 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.
Example one
Referring to fig. 1, an electromagnetic shielding film according to a preferred embodiment of the present invention includes a first shielding layer 1, N second shielding layers 2, a third shielding layer 3, an adhesive film layer 4, and a plurality of convex particles 5; the first shielding layer 1, the N second shielding layers 2, the third shielding layer 3 and the adhesive film layer 4 are sequentially stacked; the surface of the first shielding layer 1 close to the adhesive film layer 4 is a flat surface, the plurality of convex particles 5 are distributed between the first shielding layer 1 and the second shielding layer 2 and between the second shielding layer 2 and the third shielding layer 3, the surface of the third shielding layer 3 close to the adhesive film layer 4 is a non-flat surface, and the adhesive film layer 4 is arranged on the third shielding layer 3; wherein N is greater than or equal to 1. In this embodiment, N is 1, that is, the number of the second shielding layers 2 is 1.
In the embodiment of the invention, one surface of the first shielding layer 1, which is close to the adhesive film layer 4, is set to be a flat surface, and the plurality of convex particles 5 are distributed between the first shielding layer 1 and the second shielding layer 2 and between the second shielding layer 2 and the third shielding layer 3, so that one surface of the third shielding layer 3, which is close to the adhesive film layer 4, forms a non-flat surface, and thus the non-flat surface of the third shielding layer 3 can pierce through the adhesive film layer 4 and is connected with the stratum of the circuit board when the electromagnetic shielding film is laminated with the circuit board, so that the conductive particles of the adhesive film layer 4 are prevented from being pulled apart to cause grounding failure when the adhesive film layer 4 of the existing electromagnetic shielding film expands at high temperature, and the electromagnetic shielding film is ensured to be connected with the stratum; in addition, when the electromagnetic shielding film is laminated with the circuit board, the glue substances forming the glue film layer 4 are extruded into the concave position of the third shielding layer 3 to increase the glue capacity, so that the board explosion phenomenon is not easy to occur, the problem that the high-temperature board explosion is caused due to insufficient glue capacity of the existing electromagnetic shielding film is avoided, the grounding of the electromagnetic shielding film is effectively ensured, and the interference charges are led out.
In an embodiment of the present invention, the uneven surface is a regular uneven surface or an irregular uneven surface. Specifically, when the uneven surface is a regular uneven surface, the uneven surface is a structure with periodic fluctuation, and the amplitude of the fluctuation and the interval of the fluctuation on the uneven surface are the same; when the non-flat surface is an irregular non-flat surface, the non-flat surface is a structure with non-periodic fluctuation, and the amplitude and/or interval of the fluctuation on the non-flat surface are different.
Preferably, the thickness of the first shielding layer 1 is 0.1 μm to 45 μm, the thickness of the second shielding layer 2 is 0.1 μm to 45 μm, the thickness of the third shielding layer 3 is 0.1 μm to 45 μm, and the thickness of the glue film layer 4 is 1 μm to 80 μm. The material used for the glue film layer 4 is selected from the following materials: modified epoxy resins, acrylic resins, modified rubbers, and modified thermoplastic polyimides. It can be understood that, in order to ensure that the first shielding layer 1, the second shielding layer 2 and the third shielding layer 3 have good electrical conductivity, the first shielding layer 1, the second shielding layer 2 and the third shielding layer 3 respectively include 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.
It should be noted that the first shielding layer 1, the second shielding layer 2, and the third shielding layer 3 of this embodiment may be respectively of a single-layer structure or a multi-layer structure. In addition, the first shielding layer 1, the second shielding layer 2, and the third shielding layer 3 of the present embodiment may be arranged in a grid shape, a foaming shape, etc. according to the actual production and application requirements.
Preferably, the undulation degree of the side of the third shielding layer 3 close to the adhesive film layer 4 (i.e. the distance between the highest point and the lowest point of the side of the third shielding layer 3 close to the adhesive film layer 4) is 0.1 μm to 30 μm, and the undulation degree of the side of the third shielding layer 3 close to the adhesive film layer 4 is set within the above range, so that the piercing function of the third shielding layer 3 can be enhanced, thereby ensuring that the interference charges in the first shielding layer 1, the second shielding layer 2 and the third shielding layer 3 are smoothly introduced into the ground, and further avoiding the accumulation of the interference charges to form an interference source.
Referring to fig. 1, in order to make the third shielding layer 3 pierce the adhesive layer 4 more easily during the lamination process, in this embodiment, the second shielding layer 2 covers the convex particles 5 between the first shielding layer 1 and the second shielding layer 2 to form convex portions 6, and the second shielding layer 2 covers the convex particles 5 to form concave portions 7; the third shielding layer 3 covers the convex particles 5 between the second shielding layer 2 and the third shielding layer 3 to form convex portions 6, and the third shielding layer 3 covers the convex particles 5 and forms concave portions 7 at other positions. The convex particles 5 are coated by the second shielding layer 2 to form the convex parts 6, and the convex particles 5 are coated by the third shielding layer 3 to form the convex parts 6, so that the third shielding layer 3 can pierce the adhesive film layer 4 more easily in the pressing process, and the reliability of connection among the first shielding layer 1, the second shielding layer 2, the third shielding layer 3 and the ground layer of the circuit board is ensured; in addition, when the electromagnetic shielding film is laminated with the circuit board, the glue substances forming the glue film layer 4 are extruded into the concave part 7 of the third shielding layer 3 to increase the glue capacity, so that the board explosion phenomenon is not easy to occur, the problem that the high temperature causes the board explosion of the existing electromagnetic shielding film due to insufficient glue capacity is avoided, the grounding of the electromagnetic shielding film is effectively ensured, and the interference charges are led out. In addition, the plurality of protrusions 6 of the third shielding layer 3 may have a certain distance from the outer surface of the adhesive film layer 4, and may also contact the outer surface of the adhesive film layer 4 or extend out of the outer surface of the adhesive film layer 4.
Referring to fig. 1, in order to improve the piercing strength of the third shielding layer 3, in this embodiment, the protrusions 6 of the second shielding layer 2 correspond to the protrusions 6 of the third shielding layer 3 one by one, and the recesses 7 of the second shielding layer 2 correspond to the recesses 7 of the third shielding layer 3 one by one. Through with the convex part 6 of second shielding layer 2 with the convex part 6 one-to-one of third shielding layer 3, the depressed part 7 of second shielding layer 2 with the depressed part 7 one-to-one of third shielding layer 3 to make the convex part 6 of second shielding layer 2 with the convex part 6 of third shielding layer 3 is together laminated, thereby is favorable to increasing third shielding layer 3 is close to the undulation degree of one side of glued membrane layer 4, and then has improved effectively the puncture intensity of third shielding layer 3. Preferably, the plurality of convex particles 5 distributed between the second shielding layer 2 and the third shielding layer 3 are distributed on the convex portions 6 of the second shielding layer 2 in a concentrated manner.
The convex particles 5 include one or more of conductor particles, semiconductor particles, insulator particle-coated composite particles (conductor-coated insulator particles, insulator-coated insulator particles, or the like), and also include large particles formed by agglomeration of small particles. In practical application, the convex particles 5 are diamond powder, titanium dioxide powder, silicon powder, silicide powder, silicon dioxide powder, aluminide powder, graphene powder, iron powder, nickel powder, copper powder, nickel-plated diamond powder, metal-plated inorganic powder and the like. The shape of the convex particles 5 in the present invention is not limited to the shape shown in the drawings, and the material thereof is not limited to the above-mentioned material, and any particles having the convex portions 6 formed by the second shield layer 2 and the third shield layer 3 are within the scope of the present invention.
In order to satisfy the requirement that the third shielding layer 3 forms the protruding portions 6 which can penetrate the adhesive film layer 4, the height of the protruding particles 5 in the present embodiment is 0.1 μm to 30 μm. In addition, the thickness of the adhesive film layer 4 and the undulation degree of the third shielding layer 3 on the side close to the adhesive film layer 4 satisfy a proportional relationship, preferably: 0.8 ~ 2 to guarantee sufficient puncture strength and glue containing amount, the concrete embodiment is: on one hand, the phenomenon that the thickness of the adhesive film layer 4 is too small relative to the undulation degree of the third shielding layer 3 close to one side of the adhesive film layer 4, so that the adhesive capacity is insufficient and the plate explosion phenomenon is caused is prevented, and on the other hand, the phenomenon that the undulation degree of the third shielding layer 3 close to one side of the adhesive film layer 4 is too small relative to the thickness of the adhesive film layer 4, so that the puncture strength is insufficient and the grounding failure phenomenon is caused is prevented. It should be noted that the undulation degree of the third shielding layer 3 on the side close to the adhesive film layer 4 is the distance between the highest point and the lowest point of the third shielding layer 3 on the side close to the adhesive film layer 4.
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 electromagnetic shielding film can be tightly bonded with the circuit board through the adhesion layer; in addition, the adhesive layer 4 comprises an adhesive layer containing conductive particles, so that the conductivity of the adhesive layer 4 is improved, and the ground connection between the electromagnetic shielding film and the circuit board is further ensured. Of course, the adhesive layer 4 may include an adhesive layer without conductive particles to reduce the eddy current loss of the circuit board with the electromagnetic shielding film, so as to ensure the integrity of transmission and improve the flexibility of the circuit board while improving the shielding performance. The conductive particles may be conductive particles separated from each other, or may be large-particle conductive particles formed by aggregation; when the conductive particles are mutually separated conductive particles, the grounding conductivity of the adhesive film layer 4 can be further improved; and when the conductive particles are agglomerated large conductive particles, the piercing strength can be increased.
Referring to fig. 1, the electromagnetic shielding film of the present embodiment further includes a protection film layer 9, and the protection film layer 9 is disposed on a surface of the first shielding layer 1 away from the adhesive film layer 4. The protective film layer 9 has an insulating effect, so that the shielding effectiveness of the first shielding layer 1, the second shielding layer 2 and the third shielding layer 3 is ensured; in addition, the protective film 9 also has a protective effect to ensure that the first shielding layer 1 is not scratched or damaged in the using process, so as to maintain the high shielding effectiveness of the first shielding layer 1. The protective film layer 9 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. A carrier film may be further disposed on a surface of the protective film layer 9 away from the first shielding layer 1, and the carrier film supports the protective film layer 9, which is beneficial to subsequent processing.
Referring to fig. 5, in order to solve the same technical problem, an embodiment of the present invention further provides a circuit board, including a circuit board body 11 and the electromagnetic shielding film, where the electromagnetic shielding film is pressed with the circuit board body 11 through the adhesive film layer 4; the third shielding layer 3 pierces the glue film layer 4 and is electrically connected with the ground layer of the circuit board body 11.
In the embodiment of the present invention, when the electromagnetic shielding film is pressed on the circuit board body 11, the third shielding layer 3 can pierce through the glue film layer 4 and is connected to the ground layer of the circuit board body 11, so as to ensure that the first shielding layer 1, the second shielding layer 2, and the third shielding layer 3 are connected to the ground layer of the circuit board body 11, thereby guiding the interference charges in the first shielding layer 1, the second shielding layer 2, and the third shielding layer 3 into the ground, and avoiding the interference source formed by the accumulation of the interference charges from affecting the normal operation of the circuit board.
Preferably, the circuit board body 11 is one of a flexible single-sided board, a flexible double-sided board, a flexible multilayer board, and a flex-rigid board.
Example two
Referring to fig. 2, the difference between the electromagnetic shielding film of the present embodiment and the first embodiment is that a plurality of convex particles 5 are attached to one surface of one or more second shielding layers 2 close to the adhesive film layer 4 in the present embodiment. The convex particles 5 are attached to one surface, close to the adhesive film layer 4, of one or more second shielding layers 2, so that the undulation degree of one surface, close to the adhesive film layer 4, of the third shielding layer 3 is increased, and the puncture strength of the third shielding layer 3 is effectively improved. Preferably, a plurality of convex particles 5 attached to one side of one or more second shielding layers 2 close to the adhesive film layer 4 are collectively attached to the convex portions 6 of the second shielding layer 2. In this embodiment, N is 2, that is, the number of the second shielding layers 2 is 2.
Referring to fig. 2, in order to further ensure that the electromagnetic shielding film is electrically connected to the ground layer of the circuit board, a conductive protrusion 8 is disposed on a surface of the third shielding layer 3 close to the adhesive film layer 4 in this embodiment. Through be in third shielding layer 3 is close to be equipped with electrically conductive arch 8 on the one side of rete 4 of glue to in the impale glue film layer 4 is in order to further ensure the electromagnetic shield membrane is connected with the stratum electricity of circuit board. Preferably, the conductive bumps 8 are distributed on the convex portions 6 of the third shielding layer 3 in a concentrated manner, so that the third shielding layer 3 can pierce the adhesive film layer 4 more easily in the pressing process, thereby achieving grounding and improving the quality of electromagnetic shielding. In a specific implementation, the third shielding layer 3 may be formed first, and then the conductive bump 8 may be formed on the third shielding layer 3 through another process. Of course, the third shielding layer 3 and the conductive bump 8 may also be an integral structure formed by a one-step molding process.
Referring to fig. 2, in order to further improve the piercing strength of the third shielding layer 3, in this embodiment, a conductive protrusion 8 is disposed on a surface of the first shielding layer 1 close to the adhesive film layer 4. Through first shielding layer 1 is close to be equipped with electrically conductive arch 8 on the one side of rete 4 of glue to be favorable to increasing third shielding layer 3 is close to the undulation degree of the one side of rete 4 of glue, and then improved effectively the puncture strength of third shielding layer 3. In a specific implementation, the first shielding layer 1 may be formed first, and then the conductive bump 8 may be formed on the first shielding layer 1 by another process. Of course, the first shielding layer 1 and the conductive bump 8 may also be an integral structure formed by a one-step molding process. In this embodiment, the first shielding layer 1 is provided with a plurality of convex particles 5 and conductive bumps 8 on a surface thereof close to the adhesive film layer 4, and preferably, the plurality of convex particles 5 are attached to the conductive bumps 8.
Preferably, the height of the conductive bump 8 is 0.1 μm to 30 μm; the conductive bump 8 on the third shielding layer 3 may have a certain distance from 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 shape of the conductive bump 8 in the drawings of the present invention is merely exemplary, and due to differences in process means and parameters, the conductive bump 8 may also be in other shapes such as cluster, ice-hanging, stalactite, and dendritic shapes. In addition, the conductive bump 8 in the embodiment of the present invention is not limited to the shape shown in the drawings and described above, and any conductive bump 8 having piercing and conductive functions is within the scope of the present invention.
In the embodiment of the present invention, the conductive bump 8 includes 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 8 may be the same as or different from the material of the first shielding layer 1, the second shielding layer 2, or the third shielding layer 3.
Other structures and working principles of this embodiment are the same as those of the first embodiment, and will not be further described herein.
EXAMPLE III
Referring to fig. 3, the difference between the electromagnetic shielding film of the present embodiment and the second embodiment is that a conductive protrusion 8 is disposed on one surface of one or more second shielding layers 2 close to the adhesive film layer 4 in the present embodiment. The conductive protrusions 8 are arranged on one surface, close to the adhesive film layer 4, of one or more second shielding layers 2, so that the undulation degree of one surface, close to the adhesive film layer 4, of the third shielding layer 3 is increased, and the puncture strength of the third shielding layer 3 is effectively improved. Preferably, one or more conductive bumps 8 on the surface of the second shielding layer 2 close to the adhesive film layer 4 are concentrated on the convex part 6 of the second shielding layer 2.
In a specific implementation, the second shielding layers 2 may be formed first, and then the conductive bumps 8 may be formed on the second shielding layers 2 formed by other processes after each second shielding layer 2 is formed. Of course, the second shielding layer 2 and the conductive bump 8 may also be an integral structure formed by a one-step molding process.
Other structures and working principles of this embodiment are the same as those of the embodiment, and will not be further described herein.
Example four
With reference to fig. 4 and fig. 6, the difference between the electromagnetic shielding film of the present embodiment and the third embodiment is that a plurality of convex particles 5 and conductive bumps 8 are simultaneously attached to one surface of the second shielding layer 2 close to the adhesive film layer 4 in the present embodiment, and preferably, a plurality of convex particles 5 are attached to the conductive bumps 8.
As shown in fig. 4 and 6, the conductive protrusion 8 may include a plurality of conductive protrusions, and the plurality of conductive protrusions 8 may be regularly or irregularly distributed on the first shielding layer 1, the second shielding layer 2, and the third shielding layer 3; wherein, the plurality of conductive bumps 8 are regularly distributed on the first shielding layer 1, the second shielding layer 2 and the third shielding layer 3, which means that the plurality of conductive bumps 8 have the same shape and are uniformly distributed on the first shielding layer 1, the second shielding layer 2 and the third shielding layer 3; the plurality of conductive bumps 8 are irregularly distributed on the first shield layer 1, the second shield layer 2, and the third shield layer 3, which means that the plurality of conductive bumps 8 are irregularly distributed on the first shield layer 1, the second shield layer 2, and the third shield layer 3. Preferably, the conductive bumps 8 have the same shape, and the conductive bumps 8 are distributed on the first shield layer 1, the convex portion 6 of the second shield layer 2, and the convex portion 6 of the third shield layer 3. In addition, the surface of the first shielding layer 1 away from the adhesive film layer 4 may be a surface of any shape, for example, a flat surface, an uneven surface with a wavy shape, or other rough surface. The figure of the present invention only illustrates that the side of the first shielding layer 1 away from the adhesive film layer 4 is a flat surface, but any other shape is within the protection scope of the present invention.
Other structures and working principles of this embodiment are the same as those of this embodiment, and further description is omitted here.
Referring to fig. 7, in order to solve the same technical problem, an embodiment of the present invention further provides a method for manufacturing an electromagnetic shielding film, including the following steps:
s11, forming a first shielding layer 1; one surface of the first shielding layer 1 is a flat surface;
s12, forming a plurality of convex particles 5 on the flat surface of the first shield layer 1;
s13, forming N second shield layers 2 on the first shield layer 1 on which the plurality of convex particles 5 are formed; wherein N is greater than or equal to 1;
s14, forming a plurality of convex particles 5 on the second shield layer 2;
s15, forming a third shield layer 3 on the second shield layer 2 on which the plurality of convex particles 5 are formed; one surface of the third shielding layer 3 is a non-flat surface;
s16, forming an adhesive film layer 4 on the non-flat surface of the third shielding layer 3.
In step S11, the forming of the first shielding layer 1 specifically includes:
s21, forming a protective film layer 9 on the carrier film;
s22, forming a first shielding layer 1 on the protective film layer 9; wherein the first shielding layer 1 may be formed on the protective film layer 9 by one or more processes of physical roughening, electroless plating, physical vapor deposition, chemical vapor deposition, evaporation plating, sputter plating, electroplating, and hybrid plating; or the like, or, alternatively,
s31, forming a first shielding layer 1 on the surface of the strippable layer with the carrier;
s32, forming a protective film on the first shield layer 1;
s33, peeling the peelable layer of the tape carrier; wherein the first shield layer 1 may be formed on the surface of the peelable layer of the tape carrier by one or more processes of physical roughening, electroless plating, physical vapor deposition, chemical vapor deposition, evaporation plating, sputtering plating, electroplating, and hybrid plating.
In the embodiment of the present invention, after the first shielding layer 1 is formed, the method further includes: conductive bumps 8 are formed on the flat surface of the first shield layer 1. Forming a conductive bump 8 on the flat surface of the first shielding layer 1, specifically including: the convex conductive bumps 8 are formed on the flat surface of the first shield layer 1 by one or more processes of physical roughening, chemical plating, physical vapor deposition, chemical vapor deposition, evaporation plating, sputtering plating, electroplating, and hybrid plating.
In step S12, a plurality of convex particles 5 are formed on the flat surface of the first shielding layer 1, and specifically, the plurality of convex particles 5 may be formed on the flat surface of the first shielding layer 1 by using an electroless plating method, PVD, CVD, evaporation plating, sputtering plating, electroplating or a composite process thereof.
In step S13, N second shielding layers 2 are formed on the first shielding layer 1 on which the plurality of convex particles 5 are formed, and specifically, N second shielding layers 2 may be formed on the first shielding layer 1 on which the plurality of convex particles 5 are formed through one or more processes of physical roughening, electroless plating, physical vapor deposition, chemical vapor deposition, evaporation plating, sputter plating, electroplating, and hybrid plating.
In the embodiment of the present invention, one or more surfaces of the second shielding layers 2 close to the adhesive film layer 4 are provided with conductive bumps 8. The conductive bump 8 may be formed by one or more processes of physical roughening, electroless plating, physical vapor deposition, chemical vapor deposition, evaporation plating, sputter plating, electroplating, and hybrid plating.
In the embodiment of the present invention, a plurality of convex particles 5 are attached to one surface of one or more second shielding layers 2 close to the adhesive film layer 4. The convex particles 5 may be formed by one or more of electroless plating, PVD, CVD, evaporation plating, sputtering, and electroplating.
In step S14, a plurality of convex particles 5 are formed on the second shielding layer 2, specifically, the plurality of convex particles 5 may be formed on the second shielding layer 2 by using an electroless plating method, PVD, CVD, evaporation plating, sputtering plating, electroplating or a composite process thereof.
In step S15, the third shielding layer 3 is formed on the second shielding layer 2 on which the plurality of convex particles 5 are formed, and specifically, the third shielding layer 3 may be formed on the second shielding layer 2 on which the plurality of convex particles 5 are formed by one or more processes of physical roughening, electroless plating, physical vapor deposition, chemical vapor deposition, evaporation plating, sputtering plating, electroplating, and hybrid plating.
In the embodiment of the present invention, after forming the third shielding layer 3 on the second shielding layer 2 on which the plurality of convex particles 5 are formed, the method further includes: conductive bumps 8 are formed on the non-flat surface of the third shield layer 3. Forming the conductive bump 8 on the non-flat surface of the third shielding layer 3 specifically includes: the convex conductive bumps 8 are formed on the non-flat surface of the third shield layer 3 by one or more processes of physical roughening, chemical plating, physical vapor deposition, chemical vapor deposition, evaporation plating, sputtering plating, electroplating, and hybrid plating.
In step S16, forming an adhesive film layer 4 on the non-flat surface of the third shielding layer 3, specifically including:
s61, coating a glue film layer 4 on the release film;
s62, pressing and transferring the adhesive film layer 4 to the non-flat surface of the third shielding layer 3; or the like, or, alternatively,
and S71, coating a glue film layer 4 on the non-flat surface of the third shielding layer 3.
To sum up, the embodiment of the present invention provides an electromagnetic shielding film, a circuit board and a method for manufacturing the electromagnetic shielding film, wherein the electromagnetic shielding film comprises a plurality of convex particles 5, and a first shielding layer 1, N second shielding layers 2, a third shielding layer 3 and an adhesive film layer 4 which are sequentially stacked, one surface of the first shielding layer 1 close to the adhesive film layer 4 is set to be a flat surface, and the plurality of convex particles 5 are distributed between the first shielding layer 1 and the second shielding layer 2 and between the second shielding layer 2 and the third shielding layer 3, so that one surface of the third shielding layer 3 close to the adhesive film layer 4 forms a non-flat surface, thereby the non-flat surface of the third shielding layer 3 pierces through the adhesive film layer 4 and is connected with a ground layer of the circuit board when the electromagnetic shielding film is laminated with the circuit board, so as to prevent conductive particles of the adhesive film layer 4 of the existing electromagnetic shielding film from being pulled apart to cause grounding failure when the adhesive film layer 4 expands at a high temperature, thereby ensuring the ground connection of the electromagnetic shielding film and the circuit board; in addition, when the electromagnetic shielding film is laminated with the circuit board, the glue substances forming the glue film layer 4 are extruded into the concave position of the third shielding layer 3 to increase the glue capacity, so that the board explosion phenomenon is not easy to occur, the problem that the high-temperature board explosion is caused due to insufficient glue capacity of the existing electromagnetic shielding film is avoided, the grounding of the electromagnetic shielding film is effectively ensured, and the interference charges are led out.
The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and substitutions can be made without departing from the technical principle of the present invention, and these modifications and substitutions should also be regarded as the protection scope of the present invention.
Claims (14)
1. An electromagnetic shielding film is characterized by comprising a first shielding layer, N second shielding layers, a third shielding layer, an adhesive film layer and a plurality of convex particles; the first shielding layer, the N second shielding layers, the third shielding layer and the adhesive film layer are sequentially stacked; the surface of the first shielding layer, which is close to the adhesive film layer, is a flat surface, the convex particles are distributed between the first shielding layer and the second shielding layer and between the second shielding layer and the third shielding layer, the surface of the third shielding layer, which is close to the adhesive film layer, is a non-flat surface, and the adhesive film layer is arranged on the third shielding layer; wherein N is greater than or equal to 1.
2. The electromagnetic shielding film according to claim 1, wherein the second shielding layer covers the convex particles between the first shielding layer and the second shielding layer to form convex portions, and the second shielding layer covers the convex particles to form concave portions;
the third shielding layer coats the convex particles between the second shielding layer and the third shielding layer to form convex parts, and the third shielding layer coats other positions except the convex particles to form concave parts.
3. The electro-magnetic shielding film of claim 2, wherein the convex portions of the second shielding layer correspond one-to-one to the convex portions of the third shielding layer, and the concave portions of the second shielding layer correspond one-to-one to the concave portions of the third shielding layer.
4. The EMI shielding film of claim 1, wherein a plurality of said convex particles are attached to one or more of said second shielding layers adjacent to said adhesive layer.
5. The electromagnetic shielding film according to claim 1, wherein a conductive bump is formed on a surface of the first shielding layer adjacent to the adhesive film layer; and/or one or more surfaces of the second shielding layers close to the adhesive film layer are provided with conductive protrusions; and/or a conductive protrusion is arranged on one surface, close to the adhesive film layer, of the third shielding layer.
6. The electromagnetic shielding film of any one of claims 1-5, wherein the convex particles comprise one or more of conductor particles, semiconductor particles, insulator particles, and coated composite particles.
7. The electromagnetic shielding film according to any one of claims 1 to 5, wherein the adhesive layer comprises an adhesive layer containing conductive particles; or the adhesive film layer comprises an adhesion layer without conductive particles.
8. The electromagnetic shielding film according to any one of claims 1 to 5, further comprising a protective film layer disposed on a surface of the first shielding layer away from the adhesive film layer.
9. A circuit board, comprising a circuit board body and the electromagnetic shielding film according to any one of claims 1 to 8, wherein the electromagnetic shielding film is laminated with the circuit board body through the adhesive film layer; the third shielding layer pierces through the glue film layer and is electrically connected with the ground layer of the circuit board body.
10. The preparation method of the electromagnetic shielding film is characterized by comprising the following steps of:
forming a first shielding layer; one surface of the first shielding layer is a flat surface;
forming a plurality of convex particles on a flat surface of the first shielding layer;
forming N second shield layers on the first shield layer on which the plurality of convex particles are formed; wherein N is greater than or equal to 1;
forming a plurality of convex particles on the second shielding layer;
forming a third shielding layer on the second shielding layer on which the plurality of convex particles are formed; one surface of the third shielding layer is a non-flat surface;
and forming an adhesive film layer on the non-flat surface of the third shielding layer.
11. The method for preparing an electro-magnetic shielding film according to claim 10, further comprising, after forming the first shielding layer:
and forming a conductive bump on the flat surface of the first shielding layer.
12. The method of claim 10, wherein a plurality of the convex particles are attached to one surface of the one or more second shielding layers adjacent to the adhesive layer.
13. The method of claim 10, wherein one or more of the second shielding layers has a conductive bump on a surface thereof adjacent to the adhesive layer.
14. The method of manufacturing an electro-magnetic shielding film according to any one of claims 10 to 13, further comprising, after forming a third shielding layer on the second shielding layer on which the plurality of convex particles are formed:
and forming a conductive bump on the non-flat surface of the third shielding layer.
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| JP2014049498A (en) * | 2012-08-29 | 2014-03-17 | Shin Etsu Polymer Co Ltd | Electromagnetic wave shield film, production method of electromagnetic wave shield film, flexible printed wiring board, and manufacturing method of flexible printed wiring board |
| CN103763893A (en) * | 2014-01-14 | 2014-04-30 | 广州方邦电子有限公司 | Electromagnetic wave shielding film and method for manufacturing circuit board with same |
| CN203722915U (en) * | 2014-01-14 | 2014-07-16 | 广州方邦电子有限公司 | Electromagnetic wave shielding film used for printed circuit board and printed circuit board containing shielding film |
| CN107426957A (en) * | 2017-08-16 | 2017-12-01 | 苏州城邦达力材料科技有限公司 | Conducting resinl film layer, preparation method and electromagnetic shielding film |
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| JP2014049498A (en) * | 2012-08-29 | 2014-03-17 | Shin Etsu Polymer Co Ltd | Electromagnetic wave shield film, production method of electromagnetic wave shield film, flexible printed wiring board, and manufacturing method of flexible printed wiring board |
| CN103763893A (en) * | 2014-01-14 | 2014-04-30 | 广州方邦电子有限公司 | Electromagnetic wave shielding film and method for manufacturing circuit board with same |
| CN203722915U (en) * | 2014-01-14 | 2014-07-16 | 广州方邦电子有限公司 | Electromagnetic wave shielding film used for printed circuit board and printed circuit board containing shielding film |
| CN107426957A (en) * | 2017-08-16 | 2017-12-01 | 苏州城邦达力材料科技有限公司 | Conducting resinl film layer, preparation method and electromagnetic shielding film |
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