CN110769668B - 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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- CN110769668B CN110769668B CN201810847403.8A CN201810847403A CN110769668B CN 110769668 B CN110769668 B CN 110769668B CN 201810847403 A CN201810847403 A CN 201810847403A CN 110769668 B CN110769668 B CN 110769668B
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Classifications
-
- 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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B15/00—Layered products comprising a layer of metal
- B32B15/04—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B3/00—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar form; Layered products having particular features of form
- B32B3/26—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar form; Layered products having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer
- B32B3/266—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar form; Layered products having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer characterised by an apertured layer, the apertures going through the whole thickness of the layer, e.g. expanded metal, perforated layer, slit layer regular cells B32B3/12
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B33/00—Layered products characterised by particular properties or particular surface features, e.g. particular surface coatings; Layered products designed for particular purposes not covered by another single class
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B9/00—Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00
-
- 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
-
- 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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2307/00—Properties of the layers or laminate
- B32B2307/20—Properties of the layers or laminate having particular electrical or magnetic properties, e.g. piezoelectric
- B32B2307/212—Electromagnetic interference shielding
-
- 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 embodiment of the invention provides an electromagnetic shielding film, a circuit board and a preparation method of the electromagnetic shielding film, wherein the electromagnetic shielding film comprises a first shielding layer and a glue film layer which are arranged in a laminated mode, a first through hole is formed in the first shielding layer, a metal protrusion is arranged at the first through hole, and the metal protrusion is formed by instantly cooling fusible metal after flowing from one side to the other side of the first through hole at a preset temperature; the metal protrusion extends into the adhesive film layer. Through set up on first shielding layer first through-hole sets up by fusible metal in first through-hole department simultaneously and flows the metal arch that forms in the twinkling of an eye behind the opposite side from one side of first through-hole under the temperature of predetermineeing to make the metal arch stretch into the glued membrane layer, thereby make the metal arch guarantee that first shielding layer can pierce the glued membrane layer smoothly in pressfitting in-process, contact with the circuit board stratum, guarantee that interference charge normally derives, realize the shielding function.
Description
Technical Field
The invention relates to the 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 further develop toward miniaturization, light weight and high-density assembly, 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 displays, communication, aerospace and the like.
Under the push of the international market, the function flexible circuit board is dominant in the flexible circuit board market, and an important index for evaluating the performance of the function flexible circuit board is Electromagnetic shielding ((electric INTERFERENCE SHIELDING, EMI SHIELDING for short). With the integration of functions of communication equipment such as mobile phones, for example, the functions of mobile phones are required functions except the original audio transmission functions, WLAN (Wireless Local Area Networks, wireless local area network), GPS (Global Positioning System ) and internet surfing functions are popularized, and the integration of future sensing components is more unavoidable, so that the problems of Electromagnetic interference, signal attenuation and insertion loss and jitter inside and outside the components caused by the driving of high frequency and high speed are gradually serious.
At present, the shielding film commonly used by the existing circuit board comprises a shielding layer and a conductive adhesive layer, wherein the shielding layer is connected with the circuit board stratum through the conductive adhesive layer, so that interference charges are led into the circuit board stratum to realize shielding. However, at high temperature, the conductive particles originally contacting with each other in the conductive adhesive layer are pulled apart or the conductive particles originally contacting with the stratum of the circuit board are pulled apart due to expansion of the conductive adhesive layer, so that the grounding is invalid, the interference charge cannot be rapidly led out, and the shielding function cannot be realized.
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 realize reliable connection of the shielding film and a circuit board stratum and further realize a high-reliability shielding function.
In order to achieve the above object, an embodiment of the present invention provides an electromagnetic shielding film, including a first shielding layer and a film layer that are stacked, where a first through hole penetrating through an upper surface and a lower surface of the first shielding layer is provided on the first shielding layer, a metal protrusion is provided at the first through hole, and the metal protrusion is formed by instantaneously cooling a fusible metal after flowing from one side to the other side of the first through hole at a preset temperature; the metal protrusion extends into the adhesive film layer.
As an improvement of the above, the fusible metal is any one of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver, and gold, or any of a plurality of alloys.
As an improvement of the above, the preset temperature is 300 ℃ to 2000 ℃.
As an improvement of the above solution, the first shielding layer includes a first surface contacting with the adhesive film layer, and the first surface is a rough non-flat surface.
As an improvement of the scheme, the surface of the metal bulge is provided with convex conductor particles; the conductor particles have a height of 0.1 μm to 30 μm.
As an improvement of the above scheme, the electromagnetic shielding film further includes a second shielding layer, and the second shielding layer is disposed on a side of the first shielding layer, which is close to the metal protrusion, and covers the metal protrusion, so that a protrusion is formed on an outer surface of the second shielding layer at a position corresponding to the metal protrusion.
As an improvement of the above, the surface of the convex portion is provided with convex conductor particles.
As an improvement of the above, the adhesive film layer includes an adhesive layer containing conductive particles; or the adhesive film layer comprises an adhesive layer without conductive particles.
As an improvement of the above solution, the first shielding layer and the second shielding layer include one or more of a metal shielding layer, a carbon nanotube shielding layer, a ferrite shielding layer, and a graphene shielding layer, respectively.
As an improvement of the above, the metal shielding layer comprises a single metal shielding layer and/or an alloy shielding layer; wherein the single metal shielding layer is made of any one material of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold, and the alloy shielding layer is made of any two or more materials of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold.
As an improvement of the scheme, the number of the first through holes in the first shielding layer is 10-1000 per 1cm 2; and/or, the cross-sectional area of the first through hole is 0.1 μm 2-1mm2.
As an improvement of the scheme, the electromagnetic shielding film further comprises a protective film layer, and the protective film layer is arranged on one side, far away from the adhesive film layer, of the first shielding layer.
Compared with the prior art, the embodiment of the invention discloses an electromagnetic shielding film, wherein the first through hole is formed in the first shielding layer, meanwhile, the metal protrusion formed by instantaneously cooling after fusible metal flows from one side to the other side of the first through hole at a preset temperature is arranged at the first through hole, and the metal protrusion stretches into the adhesive film layer, so that the first shielding layer can be ensured to smoothly pierce through the adhesive film layer in the pressing process of the metal protrusion, reliable grounding is realized, normal derivation of interference charges is ensured, and the shielding function is realized.
The embodiment of the invention also correspondingly provides a circuit board, which comprises a printed circuit board and any electromagnetic shielding film, wherein the electromagnetic shielding film is pressed with the printed circuit board through a film layer of the electromagnetic shielding film; the metal protrusion pierces the adhesive film layer and extends to the stratum of the printed circuit board.
Compared with the prior art, the embodiment of the invention discloses a circuit board, which comprises a printed circuit board and any electromagnetic shielding film, wherein the electromagnetic shielding film is pressed with the printed circuit board through a film layer of the electromagnetic shielding film, and the metal protrusion pierces the film layer and is connected with a stratum of the printed circuit board, so that smooth export of interference charges is realized, and a shielding function is further realized.
The embodiment of the invention also correspondingly provides a preparation method of the electromagnetic shielding film, which is suitable for preparing any electromagnetic shielding film, and comprises the following steps:
s1, forming a first shielding layer; the first shielding layer is provided with a first through hole penetrating through the upper surface and the lower surface of the first shielding layer;
S2, forming a metal protrusion at the first through hole; wherein the metal protrusion protrudes out of the first through hole;
s3, forming a glue film layer on one side of the first shielding layer, on which the metal protrusion is formed.
As an improvement of the foregoing solution, in step S2, the forming a metal bump at the first through hole specifically includes:
and arranging fusible metal at the first through hole, and instantly cooling after the fusible metal flows from one side to the other side of the first through hole at a preset temperature, so that the metal protrusion is formed at the first through hole.
As an improvement of the above solution, before forming the adhesive film layer on the side of the first shielding layer where the metal protrusion is formed, the method further includes the following steps:
Conductor particles are formed on the outer surface of the metal bump by one or more of physical roughening, electroless plating, physical vapor deposition, chemical vapor deposition, evaporative plating, sputter plating, electroplating, and hybrid plating.
As an improvement of the above solution, before forming the adhesive film layer on the side of the first shielding layer where the metal protrusion is formed, the method further includes the following steps:
And forming a second shielding layer on one side of the first shielding layer, on which the metal protrusion is formed, and enabling the second shielding layer to cover the metal protrusion, so that a protrusion part is formed on the outer surface of the second shielding layer at a position corresponding to the metal protrusion.
As an improvement of the above solution, in step S3, the forming a glue film layer on the side where the metal protrusion is formed on the first shielding layer specifically includes:
Coating a glue film layer on a release film, and then pressing and transferring the glue film layer to one side of a first shielding layer, on which the metal protrusion is formed, so as to form the glue film layer on one side of the first shielding layer, on which the metal protrusion is formed; or (b)
And directly coating a glue film layer on one side of the first shielding layer, on which the metal protrusion is formed, so that the glue film layer is formed on one side of the first shielding layer, on which the metal protrusion is formed.
Compared with the prior art, the preparation method of the electromagnetic shielding film provided by the embodiment of the invention has the advantages that the metal bulge is formed at the first through hole of the first shielding layer, and the adhesive film layer is formed on one side of the first shielding layer, on which the metal bulge is formed, so that the metal bulge can ensure that the first shielding layer can successfully pierce the adhesive film layer in the pressing process, reliable grounding is realized, and the practicability is high.
Drawings
Fig. 1 is a schematic structural view of one embodiment of an electromagnetic shielding film in example 1 of the present invention;
fig. 2 is a schematic structural view of another embodiment of the electromagnetic shielding film in example 1 of the present invention;
fig. 3 is a schematic view showing the structure of an electromagnetic shielding film in embodiment 1 of the present invention at another angle;
fig. 4 is a schematic structural view of an electromagnetic shielding film in embodiment 2 of the present invention;
fig. 5 is a schematic structural view of an electromagnetic shielding film in embodiment 3 of the present invention;
Fig. 6 is a schematic structural view of a circuit board in embodiment 4 of the present invention;
fig. 7 is a flow chart showing a method for producing an electromagnetic shielding film in example 5 of the present invention.
1, A first shielding layer; 11. a first through hole; 12. a metal bump; 13. conductor particles; 14. a first surface; 15. a second surface; 2. an adhesive film layer; 3. a protective film layer; 4. a second shielding layer; 41. a boss; 5. and a printed wiring board.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Referring to fig. 1 to 3, schematic structural diagrams of an electromagnetic shielding film according to embodiment 1 of the present invention are shown;
Referring to fig. 1 to 3, the electromagnetic shielding film includes a first shielding layer 1 and a glue film layer 2 that are stacked, wherein a first through hole 11 penetrating through the upper and lower surfaces of the first shielding layer 1 is provided on the first shielding layer 1, a metal protrusion 12 is provided at the first through hole 11, and the metal protrusion 12 is formed by instantaneously cooling a fusible metal after flowing from one side to the other side of the first through hole at a preset temperature; the metal protrusion 12 extends into the adhesive film layer 2.
In the embodiment of the present invention, the first through hole 11 is disposed on the first shielding layer 1, and the metal protrusion 12 formed by instantaneously cooling the fusible metal after flowing from one side to the other side of the first through hole 11 at a preset temperature is disposed at the first through hole 11, so that the metal protrusion 12 extends into the adhesive film layer 2, and the metal protrusion 12 ensures that the first shielding layer 1 can smoothly pierce through the adhesive film layer 2 in the lamination process, so as to achieve reliable grounding, further ensure normal derivation of interference charges, and achieve a shielding function. The electromagnetic shielding film of the embodiment does not need to be provided with a conductive adhesive layer, so that the problem of grounding failure caused by expansion of the conductive adhesive layer at high temperature is effectively avoided.
Specifically, the preset temperature is 300 ℃ to 2000 ℃ during the formation of the metal bump 12. Thus, the process of forming the metal bump 12 is embodied as: melting the fusible metal at a temperature of 300 ℃ to 2000 ℃; and after the fusible metal flows from one side of the first through hole 11 away from the adhesive film layer 2 to the other side, the fusible metal is instantaneously cooled, and the fusible metal solidifies, thereby forming the metal protrusion 12 on the side of the first through hole 11 close to the adhesive film layer 2. Wherein the fusible metal is any one single metal or any multiple alloy of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold.
In the embodiments of the present invention, it should be noted that the structure of the metal bump 12 shown in the drawings is merely exemplary. Since the metal protrusion 12 is formed by instantaneously cooling the fusible metal after flowing from one side to the other side of the first through hole 11 at a preset temperature, in one of the cases, the fusible metal flows out of the first through hole 11 almost entirely, there is no residue in the first through hole 11, and thus the metal protrusion 12 formed may be formed at the boundary between the first through hole 11 and the adhesive film layer 2 as shown in the drawings, the metal protrusion 12 entirely extending into the adhesive film layer 2; in another case, the first through hole 11 is filled with a fusible metal, and the first through hole 11 is even filled with the fusible metal, so that one end of the metal protrusion 12 is formed in the first through hole 11, and the other end of the metal protrusion 12 extends out of the first through hole 11 and into the adhesive film layer 2; in still another case, a fusible metal remains on a surface of the first shielding layer 1 on a side away from the adhesive film layer 2, and thus the metal bump 12 may be formed to penetrate the first through hole 11, wherein an end of the metal bump 12 near the adhesive film layer 2 protrudes into the adhesive film layer 2. The metal bump 12 is not limited to the shape shown in the drawings and described above, and any metal bump having piercing and conductive functions is within the scope of the present invention.
In the embodiment of the present invention, in order to ensure that the metal bump 12 can be formed at the first through hole 11, it is preferable that the cross-sectional area of the first through hole 11 in the embodiment is 0.1 μm 2-1mm2.
In addition, in order to ensure that the first shielding layer 1 can successfully pierce the adhesive film layer 2, the number of the first through holes 11 in the first shielding layer 1 is 10-1000 per 1cm 2 in the embodiment. Correspondingly, the number of the metal protrusions 12 in the first shielding layer film 1 is 10-1000 per 1cm 2, so that the metal protrusions 12 can be ensured to smoothly pierce the adhesive film layer 2 in the pressing process of the first shielding layer 1.
In the embodiment of the present invention, the first through holes 11 may be regularly or irregularly distributed on the first shielding layer 1; wherein, the first through holes 11 are regularly distributed on the first shielding layer 1, which means that the shapes of the first through holes 11 are the same and are uniformly distributed on the first shielding layer 1; the first through holes 11 being irregularly distributed on the first shielding layer 1 means that the respective first through holes 11 are different in shape and are randomly distributed on the first shielding layer 1. Preferably, the shapes of the first through holes 11 are the same, and the first through holes 11 are uniformly distributed on the first shielding layer 1. In addition, the first through hole 11 may be a circular through hole, or may be any other through hole, and the present invention is illustrated only in the case that the first through hole 11 is a circular through hole, but any other shape of the first through hole 11 is within the scope of the present invention.
In the embodiment of the invention, the thickness of the first shielding layer 1 is 0.1 μm-45 μm. It will be appreciated that, in order to ensure good electrical conductivity of the first shielding layer 1, the first shielding layer 1 includes one or more of a metal shielding layer, a carbon nanotube shielding layer, a ferrite shielding layer, and a graphene shielding layer. Further, the metal shielding layer includes a single metal shielding layer and/or an alloy shielding layer; wherein the single metal shielding layer is made of any one material of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold, and the alloy shielding layer is made of any two or more materials of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold.
In the embodiment of the present invention, the first shielding layer 1 includes a first surface 14 that contacts the adhesive film layer 2. It should be noted that the first surface 14 may be any shape, for example, a flat surface as shown in fig. 1, a non-flat surface with a wavy shape, or other rough surface; further, the first surface 14 may be a regular surface or an irregular surface. The figures illustrate only the first surface 14 as a planar surface and any other shape of the first surface 14 is within the scope of the present invention.
As shown in fig. 2, in order to ensure that the first shielding layer 1 can pierce the adhesive film layer 2 to ensure reliable grounding of the electromagnetic shielding film, the first surface 14 is preferably a contoured non-planar surface. When the first surface 14 is a rough uneven surface, the first surface 14 includes a plurality of protrusions, and the first through holes 11 are preferably disposed on the protrusions, so that the metal protrusions 12 are distributed on the protrusions, so that the first shielding layer 1 is easier to pierce the adhesive film layer 2 during the lamination process, thereby further ensuring the grounding reliability of the electromagnetic shielding film.
Furthermore, the first shielding layer 1 further includes a second surface 15 disposed opposite to the first surface 14, and the second surface 15 is in contact with the protective film layer 3. It should be noted that the second surface 15 may be any shape, for example, a flat surface as shown in fig. 1, a non-flat surface with a wavy shape, or other rough surface; further, the second surface 15 may be a regular surface or an irregular surface. The drawings only illustrate the second surface 15 as a flat surface, and any other shape of the second surface 15 is within the scope of the present invention.
In the embodiment of the present invention, it should be noted that the first shielding layer 1 in the drawing of the present embodiment may have a single-layer structure or a multi-layer structure. In addition, the first shielding layer 1 of the drawings of the present embodiment may be provided in a mesh shape, a foam shape, or the like, according to the actual production and application requirements.
In the embodiment of the present invention, one of the structures of the adhesive film layer 2 is specifically: the adhesive film layer 2 includes an adhesive layer containing conductive particles. By making the adhesive film layer 2 include an adhesive layer containing conductive particles, the adhesive film layer 2 has an adhesive function to tightly adhere the wiring board and the electromagnetic shielding film, and at the same time, the adhesive film layer 2 also has a conductive function, which cooperates with the first shielding layer 1 and the metal bump 12 to rapidly introduce interference electrons into the ground layer of the wiring board. The conductive particles can be mutually separated conductive particles or large-particle conductive particles formed by agglomeration; when the conductive particles are mutually separated conductive particles, the area of the electrical contact can be further increased, and the uniformity of the electrical contact is improved; and when the conductive particles are large-particle conductive particles formed by agglomeration, the piercing strength can be increased.
In the embodiment of the present invention, the other structure of the adhesive film layer 2 is specifically: the adhesive film layer 2 includes an adhesive layer containing no conductive particles. The adhesive film layer 2 comprises an adhesive layer without conductive particles, so that the adhesive film layer 2 has an adhesive effect, so that the wiring board and the electromagnetic shielding film are tightly adhered, and meanwhile, the adhesive film layer 2 comprises the adhesive layer without conductive particles, so that the insertion loss of the circuit board in the use process is reduced, the shielding efficiency is improved, and the bending property of the circuit board is improved.
In addition, the thickness of the adhesive film layer 2 in this embodiment is 1 μm to 80 μm. The adhesive film layer 2 is made of the following materials: modified epoxy resins, acrylic, modified rubbers, and modified thermoplastic polyimides. In addition, it should be noted that the outer surface of the adhesive film layer 2 may be a flat surface without undulation, or may be a non-flat surface with gentle undulation.
As shown in fig. 1 and 3, in order to protect the first shielding layer 1, the electromagnetic shielding film further includes a protective film layer 3 in this embodiment, where the protective film layer 3 is disposed on a side of the first shielding layer 1 away from the adhesive film layer 2. The protective film layer 3 plays a role in protection, so that the first shielding layer 1 is prevented from being scratched and damaged in the using process, and the high shielding effectiveness of the shielding layer 1 is maintained. In addition, the protective film layer 3 includes a PPS film layer, a PEN film layer, a polyester film layer, a polyimide film layer, a film layer formed after curing an epoxy resin ink, a film layer formed after curing a polyurethane ink, a film layer formed after curing a modified acrylic resin, or a film layer formed after curing a polyimide resin.
In the embodiment of the present invention, it should be noted that the electromagnetic shielding film may be a repetitive multilayer structure. Specifically, the electromagnetic shielding film may include a plurality of first shielding layers 1 stacked in sequence, and one side of the whole formed by the plurality of first shielding layers 1 is provided with the adhesive film layer 2, and the other side is provided with the protective film layer 3; a metal protrusion 12 is arranged at a first through hole 11 on the first shielding layer 1, which is in contact with the adhesive film layer 2, and the metal protrusion 12 extends into the adhesive film layer 2.
Referring to fig. 4, a schematic structural diagram of an electromagnetic shielding film according to embodiment 2 of the present invention is shown;
As shown in fig. 4, the electromagnetic shielding film in the present embodiment is different from embodiment 1 in that the surface of the metal bump 12 is provided with convex conductor particles 13. By arranging the conductor particles 13 on the surface of the metal protrusion 12, it is further ensured that the first shielding layer 1 can be ensured to successfully pierce the adhesive film layer 2 in the pressing process of the metal protrusion 12, and normal export of interference charges is further ensured.
Preferably, the conductor particles 13 are intensively distributed at the outwardly protruded positions of the surface of the metal protrusion 12, so that the adhesive film layer 2 is more easily pierced. In addition, the conductor particles 2 may be distributed at other positions of the first shielding layer 1 near the surface of the adhesive film layer 2, not only on the surface of the metal protrusion 12, as shown in fig. 4. Of course, the conductor particles 2 may also be distributed only on the surface of the metal bump 12.
In an implementation, as shown in fig. 4, the metal protrusion 12 may be formed first, and then the conductor particles 13 may be formed on the outer surface of the metal protrusion 12 through other processes. Of course, the metal bump 12 and the conductor particles 13 may be an integral structure formed by a one-shot molding process.
In this embodiment of the present invention, the conductor particles 13 may have a certain distance from the outer surface of the adhesive film layer 2, or may contact with the outer surface of the adhesive film layer 2 or extend out of the outer surface of the adhesive film layer 2.
In the embodiment of the present invention, in order to further ensure that the metal bump 12 can smoothly pierce the adhesive film layer 2, the height of the conductor particles 13 is preferably 0.1 μm to 30 μm.
In the embodiment of the present invention, the conductor particles 13 include one or more of metal particles, carbon nanotube particles, and ferrite particles. Further, the metal particles include single metal particles and/or alloy particles; wherein the single metal particles are made of any one material of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold, and the alloy particles are made of any two or more materials of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold. In addition, the conductive particles 13 may be the same as or different from the metal bump 12.
In the embodiment of the present invention, it should be noted that the shape of the conductor particles 13 shown in fig. 4 is merely exemplary, and the conductor particles 13 may be in other shapes such as clusters, ice-hanging shapes, stalactites, dendrites, etc. due to differences in process means and parameters. The conductor particles 13 in the present invention are not limited to the shape shown in the drawings and described above, and any conductor particles having piercing and conducting functions are within the scope of the present invention.
In the embodiment of the present invention, it should be noted that the electromagnetic shielding film may be a repetitive multilayer structure; specifically, the electromagnetic shielding film may include a plurality of first shielding layers 1 stacked in sequence, and one side of the whole formed by the plurality of first shielding layers 1 is provided with the adhesive film layer 2, and the other side is provided with the protective film layer 3; a metal protrusion 12 is arranged at a first through hole 11 on the first shielding layer 1, which is in contact with the adhesive film layer 2, the metal protrusion 12 extends into the adhesive film layer 2, and convex conductor particles 13 are arranged on the surface of the metal protrusion 12. In addition, other structures and working principles of the electromagnetic shielding film of the present embodiment are the same as those of embodiment 1, and no further description is given here.
Referring to fig. 5, a schematic structural diagram of an electromagnetic shielding film according to embodiment 3 of the present invention is shown;
As shown in fig. 5, the electromagnetic shielding film in the present embodiment is different from embodiment 1 in that the electromagnetic shielding film further includes a second shielding layer 4, the second shielding layer 4 is provided on a side of the first shielding layer 1 near the metal bump 12 and covers the metal bump 12, so that a bump 41 is formed at a position corresponding to the metal bump 12 on an outer surface of the second shielding layer 4. The second shielding layer 4 is arranged on one side, close to the metal protrusion 12, of the first shielding layer 1, and the second shielding layer 4 is made to cover the metal protrusion 12, so that a protrusion 41 is formed at a position, corresponding to the metal protrusion 12, on the outer surface of the second shielding layer 4, and further, the metal protrusion 12 is further ensured to be capable of successfully penetrating through the adhesive film layer 2 by the first shielding layer 1 in the pressing process, and further, the normal export of interference charges is ensured.
In the embodiment of the present invention, it should be noted that the shape of the protruding portion 41 may be the same as the shape of the metal protrusion 12, or may be different from the shape of the metal protrusion 12, and the shape of the protruding portion 41 shown in the drawings is merely exemplary.
In the embodiment of the present invention, in order to further ensure that the protruding portion 41 can smoothly pierce the adhesive film layer 2, the surface of the protruding portion 41 is provided with the protruding conductor particles 13 in the embodiment. By disposing the conductor particles 13 on the surface of the protruding portion 41, the protruding portion 41 is easier to pierce through the adhesive film layer 2, thereby realizing grounding and improving the shielding performance of the electromagnetic shielding film.
Preferably, the conductor particles 12 are concentrated and distributed at the outwardly convex positions of the surface of the convex portion 41, so that the adhesive film layer 2 is more easily pierced. Of course, the conductor particles 2 may be distributed in a non-convex portion of the surface of the convex portion 41. In addition, the conductor particles 7 may be distributed at other positions of the second shielding layer 4 near the surface of the adhesive film layer 2, not only on the surface of the protruding portion 41, as shown in fig. 5. Of course, the conductor particles 2 may also be distributed only on the surface of the protruding portion 41.
In an implementation, as shown in fig. 5, the second shielding layer 4 may be formed first, and then the conductor particles 13 may be formed on a side of the second shielding layer 4 away from the first shielding layer 1 through other processes; of course, the second shielding layer 4 and the conductor particles 13 may be an integral structure formed by a one-step molding process; the conductor particles 13 are concentrated and distributed on the protruding portion 41.
In this embodiment of the present invention, the conductor particles 13 may have a certain distance from the outer surface of the adhesive film layer 2, or may contact with the outer surface of the adhesive film layer 2 or extend out of the outer surface of the adhesive film layer 2.
In the embodiment of the present invention, in order to further ensure that the protruding portion 41 can smoothly pierce the adhesive film layer 2, the height of the conductor particles 13 is preferably 0.1 μm to 30 μm.
In the embodiment of the present invention, the conductor particles 13 include one or more of metal particles, carbon nanotube particles, and ferrite particles. Further, the metal particles include single metal particles and/or alloy particles; wherein the single metal particles are made of any one material of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold, and the alloy particles are made of any two or more materials of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold. The conductor particles 13 may be the same as or different from the material of the second shielding layer 4.
In the embodiment of the present invention, it should be noted that the shape of the conductor particles 13 shown in fig. 5 is merely exemplary, and the conductor particles 13 may be in other shapes such as clusters, ice-hanging shapes, stalactites, dendrites, etc. due to differences in process means and parameters. The conductor particles 13 in the present invention are not limited to the shape shown in the drawings and described above, and any conductor particles having piercing and conducting functions are within the scope of the present invention.
In the embodiment of the present invention, the thickness of the second shielding layer 4 is 0.1 μm to 45 μm. It will be appreciated that, in order to ensure good electrical conductivity of the second shielding layer 4, the second shielding layer 4 includes one or more of a metal shielding layer, a carbon nanotube shielding layer, a ferrite shielding layer, and a graphene shielding layer. Further, the metal shielding layer includes a single metal shielding layer and/or an alloy shielding layer; wherein the single metal shielding layer is made of any one material of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold, and the alloy shielding layer is made of any two or more materials of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold.
In the embodiment of the present invention, it should be noted that the second shielding layer 4 in the drawing of the present embodiment may have a single-layer structure or a multi-layer structure. In addition, the second shielding layer 4 of the drawings of the present embodiment may be provided in a mesh shape, a foam shape, or the like, according to the actual production and application requirements.
In the embodiment of the present invention, it should be noted that the electromagnetic shielding film may be a repetitive multilayer structure; specifically, the electromagnetic shielding film may include a plurality of first shielding layers 1 stacked in sequence, and one side of the whole formed by the plurality of first shielding layers 1 is provided with the adhesive film layer 2, and the other side is provided with the protective film layer 3; a metal protrusion 12 is arranged at a first through hole 11 on the first shielding layer 1 contacted with the adhesive film layer 2; the second shielding layer 4 is disposed on a side of the first shielding layer 1 near the metal protrusion 12 and covers the metal protrusion 12, so that a protrusion 41 is formed on an outer surface of the second shielding layer 4 at a position corresponding to the metal protrusion 12. In addition, other structures and working principles of the electromagnetic shielding film of the present embodiment are the same as those of embodiment 1, and no further description is given here.
Referring to fig. 6, a schematic structural diagram of a circuit board according to embodiment 4 of the present invention is shown;
as shown in fig. 6, in order to solve the same technical problem, an embodiment of the present invention further provides a circuit board, which includes a printed circuit board 5 and the electromagnetic shielding film of embodiment 1, wherein the electromagnetic shielding film is pressed together with the printed circuit board 5 through the adhesive film layer 2 thereof; the metal bumps 12 pierce the glue film layer 2 and extend to the ground layer of the printed wiring board 5.
In the embodiment of the present invention, it should be noted that the metal bumps 12 on the electromagnetic shielding film may all contact the ground layer of the printed circuit board 5, or may partially contact the ground layer of the printed circuit board 5.
In this embodiment, reference may be made to the description of embodiment 1 above for implementation of the electromagnetic shielding film, and the description is omitted here.
Preferably, the printed circuit board 5 is one of flexible single-sided, flexible double-sided, flexible multi-layer board and rigid-flex board.
In the embodiment of the present invention, through the above structure, during the lamination process, the metal protrusion 12 provided on the first shielding layer 1 is utilized to pierce the adhesive film layer 2, so that at least a portion of the outer surface of the first shielding layer 1 is connected with the ground layer of the printed circuit board 5, and thereby the interference charge in the first shielding layer 1 is introduced into the ground, and the shielding function is realized. In addition, it should be noted that, the circuit board of the present embodiment may replace the electromagnetic shielding film of embodiment 1 adopted in the structure of the circuit board with the electromagnetic shielding film of embodiment 2 or 3, and no further description is given here.
Referring to fig. 7, a schematic flow chart of a method for preparing an electromagnetic shielding film according to embodiment 5 of the present invention is shown;
as shown in fig. 7, the method is suitable for the preparation of the electromagnetic shielding film described in example 1, and includes the steps of:
s1, forming a first shielding layer; the first shielding layer is provided with a first through hole penetrating through the upper surface and the lower surface of the first shielding layer;
Wherein the first shielding layer is formed in step S1 by:
Forming a protective film layer on a carrier film, and forming the first shielding layer on one side of the protective film layer; or alternatively, the first and second heat exchangers may be,
And forming a peelable layer on the carrier film, forming the first shielding layer on the surface of the peelable layer, and peeling the carrier film after forming a protective film layer on the side of the first shielding layer away from the peelable layer.
In the embodiment of the invention, the cross-sectional area of the first through hole is 0.1 μm 2-1mm2; the number of the first through holes in the first shielding layer is 10-1000 per 1cm 2.
S2, forming a metal protrusion at the first through hole; wherein the metal protrusion protrudes out of the first through hole;
in step S2, the forming a metal bump at the first through hole specifically includes: and arranging fusible metal at the first through hole, and instantly cooling after the fusible metal flows from one side to the other side of the first through hole at a preset temperature, so that the metal protrusion is formed at the first through hole. Wherein the fusible metal is any one single metal or any plurality of alloys of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold; the preset temperature is 300 ℃ to 2000 ℃.
S3, forming a glue film layer on one side of the first shielding layer, on which the metal protrusion is formed.
Specifically, a film layer is coated on a release film, and then the film layer is pressed and transferred to one side of a first shielding layer, on which the metal protrusions are formed, so that the film layer is formed on one side of the first shielding layer, on which the metal protrusions are formed; or (b)
And directly coating a glue film layer on one side of the first shielding layer, on which the metal protrusion is formed, so that the glue film layer is formed on one side of the first shielding layer, on which the metal protrusion is formed.
In another preferred embodiment suitable for preparing the electromagnetic shielding film described in embodiment 2, the method further comprises, before step S3:
Conductor particles are formed on the outer surface of the metal bump by one or more of physical roughening, electroless plating, physical vapor deposition, chemical vapor deposition, evaporative plating, sputter plating, electroplating, and hybrid plating.
In another preferred embodiment suitable for preparing the electromagnetic shielding film described in embodiment 3, the method further comprises the step of, prior to step S3:
Forming a second shielding layer on one side of the first shielding layer, on which the metal protrusion is formed, and enabling the second shielding layer to cover the metal protrusion, so that a protrusion part is formed on the outer surface of the second shielding layer at a position corresponding to the metal protrusion;
Conductor particles are formed on the outer surface of the raised portion by one or more of physical roughening, electroless plating, physical vapor deposition, chemical vapor deposition, evaporative plating, sputter plating, electroplating, and hybrid plating.
In the embodiment of the invention, the metal protrusion is formed at the first through hole of the first shielding layer, and the adhesive film layer is formed at one side of the first shielding layer where the metal protrusion is formed, so that the metal protrusion can ensure that the first shielding layer can successfully pierce the adhesive film layer in the pressing process, reliable grounding is realized, and the practicability is high.
In summary, the embodiment of the invention provides an electromagnetic shielding film, a circuit board and a preparation method of the electromagnetic shielding film, wherein the electromagnetic shielding film comprises a first shielding layer 1 and a glue film layer 2 which are stacked, a first through hole 11 penetrating through the upper surface and the lower surface of the first shielding layer 1 is formed in the first shielding layer 1, a metal protrusion 12 is arranged at the first through hole 11, and the metal protrusion 12 is formed by instantly cooling after fusible metal flows from one side to the other side of the first through hole 11 at a preset temperature; the metal protrusion 12 extends into the adhesive film layer 2. Through set up on the first shielding layer 1 first through-hole 11, simultaneously in first through-hole 11 department sets up by fusible metal flows to the opposite side from one side of first through-hole 11 after the transient cooling formation under the temperature of predetermineeing the metal protruding 12, and make the metal protruding 12 stretches into the glued membrane layer, thereby make the metal protruding 12 guarantee at the in-process of pressfitting first shielding layer 1 can puncture smoothly glued membrane layer 2 to realize reliable ground connection, and then guarantee that the interference charge is normally derived, realize the shielding function.
While the foregoing is directed to the preferred embodiments of the present invention, it will be appreciated by those skilled in the art that changes and modifications may be made without departing from the principles of the invention, such changes and modifications are also intended to be within the scope of the invention.
Claims (18)
1. The electromagnetic shielding film is characterized by comprising a first shielding layer and an adhesive film layer which are arranged in a stacked manner, wherein a first through hole penetrating through the upper surface and the lower surface of the first shielding layer is formed in the first shielding layer, a metal protrusion is arranged at the first through hole, and the metal protrusion is formed by instantaneously cooling after fusible metal flows from one side to the other side of the first through hole at a preset temperature; the metal protrusion extends into the adhesive film layer, so that the metal protrusion pierces the adhesive film layer and extends to the stratum of the printed circuit board in the process of pressing the electromagnetic shielding film and the printed circuit board.
2. The electromagnetic shielding film of claim 1, wherein the fusible metal is any one of a single metal or any plurality of alloys of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver, and gold.
3. The electromagnetic shielding film of claim 1, wherein the predetermined temperature is 300 ℃ to 2000 ℃.
4. The electromagnetic shielding film of claim 1, wherein the first shielding layer comprises a first surface in contact with the adhesive film layer, the first surface being a contoured non-planar surface.
5. The electromagnetic shielding film according to claim 1, wherein the surface of the metal protrusion is provided with convex conductor particles; the conductor particles have a height of 0.1 μm to 30 μm.
6. The electromagnetic shielding film according to claim 1, further comprising a second shielding layer provided on a side of the first shielding layer close to the metal protrusion and covering the metal protrusion, thereby forming a protrusion portion at a position of an outer surface of the second shielding layer corresponding to the metal protrusion.
7. The electromagnetic shielding film of claim 6, wherein the surface of the boss is provided with convex conductor particles.
8. The electromagnetic shielding film of claim 1, wherein the adhesive film layer comprises an adhesive layer comprising conductive particles; or alternatively, the first and second heat exchangers may be,
The adhesive film layer comprises an adhesive layer without conductive particles.
9. The electromagnetic shielding film of claim 6, wherein the first and second shielding layers comprise one or more of a metal shielding layer, a carbon nanotube shielding layer, a ferrite shielding layer, and a graphene shielding layer, respectively.
10. The electromagnetic shielding film of claim 9, wherein the metallic shielding layer comprises a single metallic shielding layer and/or an alloy shielding layer; wherein the single metal shielding layer is made of any one material of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold, and the alloy shielding layer is made of any two or more materials of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold.
11. The electromagnetic shielding film according to any one of claims 1 to 10, wherein the number of the first through holes in the first shielding layer is 10 to 1000 per 1cm 2; and/or, the cross-sectional area of the first through hole is 0.1 μm 2-1mm2.
12. The electromagnetic shielding film of any one of claims 1-10, further comprising a protective film layer disposed on a side of the first shielding layer remote from the adhesive film layer.
13. A circuit board, characterized by comprising a printed circuit board and the electromagnetic shielding film according to any one of claims 1-12, wherein the electromagnetic shielding film is pressed with the printed circuit board through a glue film layer thereof; the metal protrusion pierces the adhesive film layer and extends to the stratum of the printed circuit board.
14. A method for producing an electromagnetic shielding film, characterized by being suitable for producing the electromagnetic shielding film according to any one of claims 1 to 12, comprising the steps of:
s1, forming a first shielding layer; the first shielding layer is provided with a first through hole penetrating through the upper surface and the lower surface of the first shielding layer;
S2, forming a metal protrusion at the first through hole; wherein the metal protrusion protrudes out of the first through hole;
S3, forming a glue film layer on one side of the first shielding layer, on which the metal protrusion is formed, wherein the metal protrusion pierces the glue film layer and extends to the stratum of the printed circuit board in the process of pressing the electromagnetic shielding film and the printed circuit board.
15. The method of manufacturing an electromagnetic shielding film according to claim 14, wherein in step S2, the forming a metal bump at the first through hole is specifically:
and arranging fusible metal at the first through hole, and instantly cooling after the fusible metal flows from one side to the other side of the first through hole at a preset temperature, so that the metal protrusion is formed at the first through hole.
16. The method of manufacturing an electromagnetic shielding film according to claim 14, further comprising, before forming a glue film layer on a side of the first shielding layer on which the metal bump is formed, the steps of:
Conductor particles are formed on the outer surface of the metal bump by one or more of physical roughening, electroless plating, physical vapor deposition, chemical vapor deposition, evaporative plating, sputter plating, electroplating, and hybrid plating.
17. The method of manufacturing an electromagnetic shielding film according to claim 14, further comprising, before forming a glue film layer on a side of the first shielding layer on which the metal bump is formed, the steps of:
And forming a second shielding layer on one side of the first shielding layer, on which the metal protrusion is formed, and enabling the second shielding layer to cover the metal protrusion, so that a protrusion part is formed on the outer surface of the second shielding layer at a position corresponding to the metal protrusion.
18. The method for manufacturing an electromagnetic shielding film according to claim 14, wherein in step S3, the adhesive film layer is formed on the side of the first shielding layer where the metal protrusion is formed, specifically:
Coating a glue film layer on a release film, and then pressing and transferring the glue film layer to one side of a first shielding layer, on which the metal protrusion is formed, so as to form the glue film layer on one side of the first shielding layer, on which the metal protrusion is formed; or (b)
And directly coating a glue film layer on one side of the first shielding layer, on which the metal protrusion is formed, so that the glue film layer is formed on one side of the first shielding layer, on which the metal protrusion is formed.
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