CN117395977B - Electromagnetic shielding film and application thereof - Google Patents
Electromagnetic shielding film and application thereof Download PDFInfo
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- CN117395977B CN117395977B CN202311553601.0A CN202311553601A CN117395977B CN 117395977 B CN117395977 B CN 117395977B CN 202311553601 A CN202311553601 A CN 202311553601A CN 117395977 B CN117395977 B CN 117395977B
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Classifications
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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
-
- 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
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
Abstract
The invention relates to the technical field of electronics, in particular to an electromagnetic shielding film and application thereof. An electromagnetic shielding film comprises a shielding layer, wherein the electromagnetic shielding film is covered on a circuit board and meets the following formula (1): r=a×Φ+b×d+c (1); r is the grounding resistance of the circuit board covered with the electromagnetic shielding film, mΩ, phi is the grounding window aperture of the electromagnetic shielding film, mm, d is the step-resistant height of the electromagnetic shielding film, mu m, -210-95, -2-45, -154-350. According to the invention, a large number of experiments show that the grounding resistance of the electromagnetic shielding film covered on the circuit board is positively correlated with the aperture of the grounding window with step resistance, and the electromagnetic shielding effect satisfying the functional relation is good.
Description
Technical Field
The invention relates to the technical field of electromagnetic shielding films, in particular to an electromagnetic shielding film and application thereof.
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.
With the integration of functions of communication devices such as mobile phones, internal components thereof are rapidly increased in frequency and speed. For example: in addition to the original audio transmission function, the camera function has become a necessary function, and the WLAN (Wireless Local Area Networks, wireless local area network), GPS (Global Positioning System ) and internet function have become popular, and the trend of rapid high frequency and high speed of the components is more unavoidable in addition to the integration of the future sensing components. However, electromagnetic interference, attenuation of signals during transmission, insertion loss and jitter problems inside and outside the components caused by high frequency and high speed driving are increasingly serious, and thus, the electromagnetic shielding performance of the flexible circuit board is increasingly important.
The prior art discloses a conductive adhesive film layer, a preparation method and an electromagnetic shielding film, and improves electromagnetic shielding performance by limiting the material and thickness of the shielding film, but the grounding resistance of the existing shielding film in a scene of using a high step is large, or the grounding of a circuit board with a grounding window with a smaller aperture cannot be met, so that the shielding effect of the shielding film applied to circuit boards with different sizes cannot be controlled.
Disclosure of Invention
Therefore, the technical problem to be solved by the invention is to overcome the defect that the shielding performance of the electromagnetic shielding film covered on the circuit board is not required to be accurately evaluated in the prior art, so that the electromagnetic shielding film and the application thereof are provided, the covering effect of the electromagnetic shielding film covered on different circuit boards can be evaluated through the relation of the grounding window aperture resistance of the electromagnetic shielding film, the step height resistance of the electromagnetic shielding film and the grounding resistance, and further, the optimization of each parameter is realized quickly, and the production efficiency of the shielding film is improved on the basis of ensuring the shielding efficiency.
In one aspect, the present invention provides an electromagnetic shielding film including a shielding layer, the electromagnetic shielding film satisfying the following formula (1):
R＝A×φ+B×d+C(1)；
r is the grounding resistance of the electromagnetic shielding film, mΩ, phi is the aperture of the grounding-resistant window of the electromagnetic shielding film, mm, d is the step-resistant height of the electromagnetic shielding film, mu m, -210-95, -2-45, -154-350.
The grounding-resistant window hole diameter phi of the electromagnetic shielding film is a stepped hole diameter of the electromagnetic shielding film on the circuit board, so that the circuit board can be normally used.
The step-resistant height is a gap between the electromagnetic shielding film and the grounding window. The aperture of the grounding-resistant window is the diameter of the grounding window on the circuit board. Specifically, the minimum distance between two adjacent grounding windows is 2 cm-4 cm. For example, the minimum distance is 2cm. The shape of the grounding window can be round, square, rectangular or regular polygon. The aperture diameter refers to the diameter of the circumscribed circle of the outer contour of the grounding window.
In one embodiment, the grounding-resistant window aperture of the electromagnetic shielding film is 0.2mm-3mm.
In one embodiment, the electromagnetic shielding film has a step-resistant height of 10 μm to 200 μm.
In one embodiment, the electromagnetic shielding film further comprises a connection layer, wherein one side of the connection layer is connected with the circuit board, and the other side of the connection layer is connected with the shielding layer.
In one embodiment, the thickness of the shielding layer is 0.1 μm to 10 μm.
In one embodiment, the tie layer has a thickness of 1 μm to 8 μm.
In one embodiment, when the connection layer is made of a non-conductive material, a protruding structure is arranged on the shielding layer, and the protruding structure is used for penetrating through the connection layer and grounding the circuit board; when the connecting layer is made of conductive materials, the shielding layer is grounded to the circuit board through the convex structures arranged on the shielding film and/or the conductive materials of the connecting layer.
In one embodiment, the conductive material includes a glue film layer and conductive particles.
In one embodiment, the electromagnetic shielding film further includes a protective layer, and the protective layer is connected to the shielding layer and disposed opposite to the connection layer.
In one embodiment, the protective layer includes a reinforcing layer and a filler layer, the filler layer being coupled to the shielding film.
Optionally, the enhancement layer is any one of PI, PET, PP.
In one embodiment, at least two protective layers are connected to the shielding layer, where each filling layer and each reinforcing layer are alternately arranged.
In one embodiment, the thickness of the reinforcement layer is 0.5 μm to 7 μm.
In one embodiment, the filling layer is at least one of polyimide, polyurethane, isocyanate, epoxy, ink, polypropylene, cross-linked polyethylene, polyester, polybenzimidazole, epoxy, phenolic, amino, alkyd, polyurethane, acrylate, amide, synthetic rubber, and modified rubber.
In another aspect, the present invention provides a circuit board covered with the electromagnetic shielding film.
The electromagnetic shielding film and/or the circuit board provided by the invention can be applied to electronic products.
The technical scheme of the invention has the following advantages:
1. the electromagnetic shielding film provided by the invention comprises a shielding layer, wherein the shielding layer meets the following formula (1): r=a×Φ+b×d+c (1); r is the grounding resistance of the electromagnetic shielding film, mΩ, phi is the aperture of the grounding-resistant window of the electromagnetic shielding film, mm, d is the step-resistant height of the electromagnetic shielding film, mu m, -210-95, -2-45, -154-350. By providing the functional relation, the grounding resistance of the electromagnetic shielding film conforming to the shielding effect can be quickly adjusted, and the production efficiency is improved, so that the grounding requirements of the step heights and the grounding apertures on different circuit boards are met, and the applicability of the electromagnetic shielding film is improved.
2. The electromagnetic shielding film provided by the invention limits the range value of the grounding window diameter and the range value of the step height, meets the requirements of limiting the range value of the grounding window diameter and the range value of the step height, and can be suitable for use of more types of flexible circuit boards under the condition of ensuring the shielding effect.
3. The thickness of the shielding layer of the electromagnetic shielding film provided by the invention is 0.1-10 mu m, and the shielding layer can adapt to the covering effects of components with different heights and different sizes, so that the electromagnetic shielding effectiveness is ensured.
4. The electromagnetic shielding film provided by the invention further comprises the reinforcing layer and the filling layer, the strength of the protective layer is reinforced through the reinforcing layer, the bending resistance and the step resistance are improved, the electromagnetic shielding film is suitable for shielding effect of FPC circuit boards with different heights, and the chemical corrosion resistance and the ultraviolet resistance of the electromagnetic shielding film can be improved and the service life of the electromagnetic shielding film is prolonged through the arrangement of the filling layer.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic view of an electromagnetic shielding film and circuit board structure according to a first embodiment of the present invention;
FIG. 2 is a schematic view of an electromagnetic shielding film according to a second embodiment of the present invention;
FIG. 3 is a schematic view of an electromagnetic shielding film according to a third embodiment of the present invention;
FIG. 4 is a schematic view of an electromagnetic shielding film according to a fourth embodiment of the present invention;
FIG. 5 is a schematic view showing the structure of an electromagnetic shielding film according to a fifth embodiment of the present invention;
FIG. 6 is a schematic view of the structure of an electromagnetic shielding film according to a sixth embodiment of the present invention;
reference numerals:
1-a shielding layer; 2-a cover film; 3-a circuit board; 4-a protective layer; 41-an enhancement layer; 42-a filling layer; a 5-connection layer; 6-electromagnetic shielding film; 7-a bump structure; 8-conductive particles; 9-ground window.
Detailed Description
The following examples are provided for a better understanding of the present invention and are not limited to the preferred embodiments described herein, but are not intended to limit the scope of the invention, any product which is the same or similar to the present invention, whether in light of the present teachings or in combination with other prior art features, falls within the scope of the present invention.
The specific experimental procedures or conditions are not noted in the examples and may be followed by the operations or conditions of conventional experimental procedures described in the literature in this field. The reagents or apparatus used were conventional reagent products commercially available without the manufacturer's knowledge.
An embodiment of the present invention provides an electromagnetic shielding film including a shielding layer, the electromagnetic shielding film satisfying the following formula (1):
R＝A×φ+B×d+C(1)；
r is the grounding resistance of the electromagnetic shielding film, mΩ, phi is the aperture of the grounding-resistant window of the electromagnetic shielding film, mm, d is the step-resistant height of the electromagnetic shielding film, mu m, -210-95, -2-45, -154-350.
The grounding-resistant window hole diameter phi of the electromagnetic shielding film is a stepped hole diameter of the electromagnetic shielding film on the circuit board, so that the circuit board can be normally used.
The step-resistant height is a gap between the electromagnetic shielding film and the grounding window. The aperture of the grounding-resistant window is the diameter of the grounding window on the circuit board. Specifically, the minimum distance between two adjacent grounding windows is 2 cm-4 cm. For example, the minimum distance is 2cm. The shape of the grounding window can be round, square, rectangular or regular polygon. The aperture diameter refers to the diameter of the circumscribed circle of the outer contour of the grounding window.
With continued reference to fig. 1, it should be noted that the circuit board 3 uses an FPC board, i.e., a flexible circuit board, as a connection line in an electronic device, and mainly plays roles of conducting current and transmitting signals. When the signal transmission lines are distributed on the outermost layer of the flexible circuit board, in order to avoid signal distortion caused by electromagnetic interference in the signal transmission process, the flexible circuit board is pressed with an electromagnetic shielding film 6 after the cover film 2 is pressed, so that a grounding window 9 is formed. The covering film has the function of covering all or part of components such as copper foil etched circuits, embedded resistors, embedded capacitors and the like under the covering film, so that the service life and the working reliability of the circuit board are improved. And, set up the ground window on the covering film, the ground connection of electromagnetic shielding film. The electromagnetic shielding film can play a role in shielding electromagnetic interference outside. Among them, the most common is an FPC film for image signal transmission in a lens module of each electronic device.
According to the invention, the functional relation between the step height resistance, the aperture of the grounding window and the low resistance of the shielding film is established, so that the electromagnetic shielding film with smaller grounding resistance and higher shielding efficiency can be obtained, and the electromagnetic shielding film is suitable for electromagnetic shielding of circuit boards with high step height and small size grounding windows.
The step-resistant height is a gap between the electromagnetic shielding film and the grounding window. The aperture of the grounding-resistant window is the diameter of the grounding window on the circuit board.
Optionally, the shielding layer may be 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; 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.
Optionally, the thickness of the shielding layer is 0.1 μm to 10 μm. The above conditions can ensure excellent shielding performance, and are favorable for improving the bending resistance of the electromagnetic shielding film at the thickness.
In one embodiment, the grounding-resistant window aperture of the electromagnetic shielding film is 0.2mm-3mm. The grounding resistance value is smaller in the range, the resistance value of the whole grounding resistance is within 3000mΩ, the grounding requirement of most of the terminal parts on the soft board is met, and the electromagnetic shielding effect is ensured.
In one embodiment, the electromagnetic shielding film has a step-resistant height of 10 μm to 200 μm. The width of the gap between the shielding layer of the electromagnetic shielding film and the grounding window is smaller in the range, the contact area between the shielding layer and the grounding layer is large, the use requirement is met, leakage waves are avoided, and the electromagnetic shielding film is suitable for high-frequency circuits. If the step height is higher than this range, on the one hand, the strength of the electromagnetic shielding film is insufficient and breakage is liable to occur. On the other hand, too thick electromagnetic shielding films may reduce bending resistance.
In one embodiment, referring to fig. 2, the electromagnetic shielding film further includes a connection layer 5, where one side of the connection layer is connected to the circuit board, and the other side of the connection layer is connected to the shielding layer 1. The shielding layer is connected with the circuit board through the connecting layer, so that the electromagnetic shielding film is prevented from falling off.
Optionally, the thickness of the connection layer is 1 μm to 20 μm. In this range, the problem that too thick electromagnetic shielding film can cause glue overflow and too thin electromagnetic shielding film can cause insufficient binding force can be avoided.
In one embodiment, referring to fig. 3, the connection layer 5 is made of a non-conductive material, and the shielding layer 1 is provided with a bump structure 7, which is used to pierce the connection layer and ground the circuit board. Therefore, the grounding structure is grounded through the protruding structure, so that the grounding reliability is improved, and the grounding resistance is reduced.
Alternatively, the connection layer of the non-conductive material may be a modified epoxy resin, an acrylic, a modified rubber, a modified thermoplastic polyimide.
In another embodiment, the connection layer is made of a conductive material, and the shielding layer is grounded to the circuit board through a bump structure and/or the conductive material of the connection layer disposed on the shielding film. Specifically, referring to fig. 4, the conductive material includes a film layer and conductive particles 8.
The material of the conductive particles may be metal particles, metal-coated resin particles, carbon-based filler, or the like, and the metal particles may be at least one of silver, copper, gold, aluminum, tungsten, zinc, nickel, iron, platinum, and titanium. The conductive particles may have a shape with an arc such as a circle, an ellipse, an egg shape, or any one of a dendritic shape, a flake shape, a needle shape, a chain shape, and a spike shape.
The electromagnetic shielding film is grounded with the circuit board by means of conductive particles arranged in the connecting layer, so that excellent electromagnetic shielding performance of the flexible circuit board is realized. In one embodiment, referring to fig. 3, the electromagnetic shielding film further includes a protective layer 4, where the protective layer is connected to the shielding layer and is disposed opposite to the connection layer. The protective layer has an isolation effect, so that the shielding effect of the shielding layer is guaranteed; in addition, the protective layer also has a protective effect so as to ensure that the shielding layer is not scratched and damaged in the use process, thereby being beneficial to maintaining the high shielding effectiveness of the shielding layer.
Optionally, the protective layer is any one of PPS film layer, PEN film layer, polyester film layer, polyimide film layer, film layer formed by curing epoxy resin ink, film layer formed by curing polyurethane ink, film layer formed by curing modified acrylic resin, or film layer formed by curing polyimide resin. Wherein, the protection rete is kept away from can also be equipped with the carrier film in this within range on the one side of shielding layer, on the one hand can guarantee the roughness of first test structure to make electromagnetic shield film laminate on organic rete surface closely, when simulating true service scenario, can guarantee the coverage effect, avoid the wave leakage.
Further, referring to fig. 5, the protective layer 4 includes a reinforcing layer 41 and a filling layer 42, and the filling layer is connected to the shielding layer. The integral lamination structure of the protective layer is changed, so that the strength of the protective layer is reinforced, the bending resistance and the step resistance are improved, and the shielding effect of FPC circuit boards with different heights is improved.
Optionally, the filling layer is at least one of polyimide, polyurethane, isocyanate, ink, polypropylene, crosslinked polyethylene, polybenzimidazole, epoxy resin, phenolic resin, amino resin, alkyd resin, polyurethane resin, acrylic resin, amide resin, synthetic rubber and modified rubber.
The filling layer is preferably epoxy resin, and the epoxy resin ink has the following advantages: the durability is strong: the epoxy resin ink has excellent chemical corrosion resistance, can resist corrosion of substances such as acid, alkali, solvent and the like, and therefore has longer service life. The wear resistance is good: the epoxy resin ink has higher hardness and wear resistance, and can keep bright color and brightness in long-term use. High temperature resistance: the epoxy resin ink can bear higher temperature and still can be kept stable in high-temperature environment. The adhesive force is strong: the epoxy resin ink coating has good adhesive force with the base material, and is not easy to peel off. The color stability is good: the epoxy resin ink has better ultraviolet resistance and is not easy to fade or change color. In general, the epoxy resin ink has the advantages of durability, wear resistance, good temperature resistance, strong adhesive force, stable color and the like, and is suitable for various application fields requiring high-quality ink coatings.
Optionally, the enhancement layer is any one of PI, PET, PP.
Specifically, the reinforcing layer is preferably a polyimide film, which has (1) excellent heat resistance. Polyimide generally has a decomposition temperature exceeding 500 ℃ and sometimes even higher, and is one of the most thermally stable varieties of known organic polymers, mainly because of the large number of aromatic rings contained in the molecular chain. (2) excellent mechanical properties. The tensile strength of the unreinforced matrix material is 100MPa or more. The tensile strength of the Kapton film prepared by using the homoanhydride is 170MPa, and the tensile strength of the biphenyl polyimide (Upilex S) can reach 400MPa. The elastic modulus of the polyimide fiber can reach 500MPa, which is inferior to that of the carbon fiber. (3) good chemical stability and resistance to moist heat. Polyimide materials are generally insoluble in organic solvents and resistant to corrosion and hydrolysis. The variety with different structures can be obtained by changing the molecular design. Some varieties can withstand 2 atmospheres and 120 ℃ for 500 hours of water boiling. (4) good radiation resistance. Polyimide film at 5×10 9 After radiation at the rad dose, the intensity remains 86%; some polyimide fibers are 1 x 10 10 After rad fast electron irradiation, the intensity retention is 90%. (5) good dielectric properties. The dielectric constant is less than 3.5, if fluorine atoms are introduced into the molecular chain, the dielectric constant can be reduced to about 2.5, the dielectric loss is 10, the dielectric strength is 100-300 kV/mm, and the volume resistance is 1015-17 omega cm.
The above properties are stable over a wide temperature range and frequency range. In addition, polyimide has the characteristics of low temperature resistance, low expansion coefficient, flame retardance, good biocompatibility and the like. Polyimide has excellent comprehensive performance and chemical diversity, and may be used widely in various fields. Therefore, the protective layer has better ductility and protective effect, is suitable for use scenes with high steps and high bending angles, has longer service life, has good integral shielding effect of the electromagnetic shielding film and effectively reduces leakage waves.
Optionally, the thickness of the reinforcing layer is 0.5 μm to 7 μm. The enhancement layer with the thickness can be suitable for shielding films with common thickness, fully reinforce the protective layer and improve the step resistance and bending resistance. Within this range, it is advantageous to enable the electromagnetic shielding film to satisfy high step resistance, and if it is below this range, it may cause the FPC to be subjected to excessive stress during bending or unable to recover to the original state, thereby affecting its reliability and life.
More specifically, the reinforcing layer may be disposed at the topmost layer, may be sandwiched between the filling layers, and may be disposed at the bottommost layer. Different protective layer properties can be adjusted by setting different enhancement layers, so that the shielding effect is ensured and the shielding device is suitable for more use scenes.
Further, at least two protective layers (not shown) are connected to the shielding layer, wherein each filling layer and each reinforcing layer are alternately arranged. Therefore, the protection effect and the insulation effect on the shielding layer are further improved, the damage of the shielding film is avoided, and the use reliability is improved.
In another aspect, the present invention provides a circuit board (not shown in the drawings) covered with the electromagnetic shielding film described above.
The electromagnetic shielding film and/or the circuit board provided by the invention can be applied to electronic products.
When the electromagnetic shielding film is used, the covering effect of components and covering films with different heights and different sizes on the flexible circuit board needs to be met, and when the functional relation is met, the covering effect of components with higher sizes and heights can be met, the electromagnetic shielding efficiency is improved, leakage waves are avoided, and the overall use quality of the electromagnetic shielding film is further improved.
Example 1
Referring to fig. 3, the present embodiment provides an electromagnetic shielding film, which includes a protective layer 4, a shielding layer 1, and a connection layer 5, wherein the protective layer is 7 μm, the connection layer is 5 μm, and the shielding layer is 0.5 μm. The shielding layer is provided with a plurality of protruding structures 7 towards the side of the connection layer, and no conductive particles are arranged in the connection layer. The relation between the step height resistance, the grounding window aperture resistance and the grounding resistance is consistent with the functional relation (1) by measuring the grounding resistance under different step heights and different grounding window apertures, wherein A is-180.44, B is 36.63 and C is-5.86.
Example 2
Referring to fig. 6, the present embodiment provides an electromagnetic shielding film, which includes a protective layer 4, a shielding layer 1, and a connection layer 5, wherein the protective layer is 7 μm and includes a PI enhancement layer 41 of 2 μm; the connection layer was 6 μm and the shielding layer was 3.5 μm. The shielding layer is provided with a protruding structure, and no conductive particles are arranged in the connecting layer. The relation between the step height resistance, the grounding window aperture resistance and the grounding resistance is consistent with the functional relation (1) by measuring the grounding resistance under different step heights and different grounding window apertures, wherein A is-33.29, B is 13.32 and C is-3.78.
Example 3
Referring to fig. 3, the present embodiment provides an electromagnetic shielding film, which includes a protective layer 4, a shielding layer 1, and a connection layer 5, wherein the protective layer is 11 μm, the connection layer is 5 μm, and the shielding layer is 2 μm. The shielding layer is provided with a protruding structure, and no conductive particles are arranged in the connecting layer. The relation between the step height resistance, the aperture of the grounding window and the grounding resistance is in accordance with the functional relation (1) as shown above, wherein A is 1.30, B is-0.01 and C is 286.42.
Example 4
Referring to fig. 3, the present embodiment provides an electromagnetic shielding film, which includes a protective layer, a shielding layer 1, and a connection layer 5, wherein the protective layer is 10 μm, the connection layer is 7 μm, and the shielding layer is 3.5 μm. The shielding layer is provided with a protruding structure, and no conductive particles are arranged in the connecting layer. The relation between the step height resistance, the grounding window aperture resistance and the grounding resistance is in accordance with the functional relation (1) by measuring the grounding resistance under different step heights and different grounding window apertures, wherein A is 1.90, B is 0.02 and C is-141.84.
Comparative example 1
The embodiment provides an electromagnetic shielding film, which comprises a protective layer, a shielding layer 1 and a connecting layer 5, wherein the protective layer is 6 μm, the connecting layer is 9 μm, conductive particles are contained in the connecting layer, and the shielding layer is 0.5 μm. The relation between the step height resistance, the aperture of the grounding window and the grounding resistance is not in accordance with the functional relation (1) by measuring the grounding resistance under different step heights and different grounding window diameters, wherein A is 104.1, B is 61.04 and C is 560.
Comparative example 2
The embodiment provides an electromagnetic shielding film, which comprises a protective layer, a shielding layer 1 and a connecting layer 5, wherein the protective layer is 5 mu m, the connecting layer is 3 mu m, and the connecting layer comprises conductive particles. The shielding layer was 0.1 μm. The grounding resistance under different step heights and different grounding window diameters can be known by measuring the grounding resistance under different grounding window diameters, and the functional relation between the step height resistance, the grounding window aperture resistance and the grounding resistance is obtained, wherein A is-110.21, B is-3.2, C is-187.45, and the functional relation (1) is not satisfied.
Experimental example
The grounding resistance, shielding effectiveness and bending resistance were measured according to GB/T30142-2013 test standard by using the above examples and comparative examples, and the lamination method of covering the circuit board with the electromagnetic shielding film was that 120kg/cm was used at 185 ℃ 2 Pressing the electromagnetic shielding films on the circuit board for 3min. The detection results are shown in Table 1.
TABLE 1 electromagnetic shielding effectiveness and bending times of the electromagnetic shielding films
| Experimental objects | Shielding effectiveness (dB) | Number of times of bending resistance |
| Example 1 | ≥60 | 5638 |
| Example 2 | ≥60 | 7836 |
| Example 3 | ≥60 | 10578 |
| Example 4 | ≥60 | 5140 |
| Comparative example 1 | ≈55 | 1554 |
| Comparative example 2 | ≈55 | 1467 |
It can be seen that the relation among the step height resistance, the grounding window aperture resistance and the grounding resistance of the electromagnetic shielding films in embodiments 1-4 of the invention accords with the functional relation of the formula (1), the grounding resistance is smaller, the good line electromagnetic shielding efficiency can be ensured, the bending resistance performance is excellent, and the electromagnetic shielding films can be applied to electronic products with extremely thin equipment and high-frequency and high-speed circuit boards.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. While still being apparent from variations or modifications that may be made by those skilled in the art are within the scope of the invention.
Claims (10)
1. An electromagnetic shielding film, characterized by comprising a shielding layer, and the electromagnetic shielding film satisfies the following formula (1):
R＝A×φ+B×d+C(1)；
r is the grounding resistance, mΩ,
phi is the diameter of the grounding-resistant window hole of the electromagnetic shielding film, mm,
d is the step-resistant height of the electromagnetic shielding film, mum,
-210≤A≤95，-2≤B≤45，-154≤C≤350。
2. the electromagnetic shielding film according to claim 1, wherein the grounding-resistant window aperture of the electromagnetic shielding film is 0.2mm to 3mm; and/or the number of the groups of groups,
the step-resistant height of the electromagnetic shielding film is 10-200 mu m.
3. The electromagnetic shielding film according to claim 1, further comprising a connection layer, wherein one side of the connection layer is connected to a wiring board, and the other side is connected to the shielding layer; and/or the number of the groups of groups,
the thickness of the shielding layer is 0.1-10 mu m.
4. An electromagnetic shielding film according to claim 3, wherein the thickness of the connection layer is 1 μm-20 μm.
5. The electromagnetic shielding film according to claim 3, wherein when the connection layer is made of a non-conductive material, a protrusion structure is provided on the shielding layer, and the protrusion structure is used for penetrating through the connection layer and grounding with the circuit board;
when the connecting layer is made of conductive materials, the shielding layer is grounded with the circuit board through a protruding structure arranged on the shielding layer and/or the connecting layer.
6. The electromagnetic shielding film according to claim 5, wherein the connection layer comprises a film layer, the film layer is connected with the circuit board, and a plurality of conductive particles are arranged in the film layer.
7. The electromagnetic shielding film according to any one of claims 3 to 6, further comprising a protective layer connected to the shielding layer and disposed opposite the connection layer.
8. The electromagnetic shielding film of claim 7, wherein the protective layer comprises a reinforcing layer and a filler layer, the filler layer being coupled to the shielding layer.
9. The electromagnetic shielding film of claim 8, wherein at least two protective layers are connected to the shielding layer, wherein each of the filling layers is alternately arranged with each of the reinforcing layers; and/or
The thickness of the reinforcing layer is 0.5-7 mu m; and/or the number of the groups of groups,
the filling layer is at least one of polyimide, polyurethane, isocyanate, ink, polypropylene, crosslinked polyethylene, polybenzimidazole, epoxy resin, phenolic resin, amino resin, alkyd resin, polyurethane resin, acrylic ester resin, amide resin, synthetic rubber and modified rubber.
10. Use of an electromagnetic shielding film according to any one of claims 1-9 in an electronic product.
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| JPH10322082A (en) * | 1997-03-19 | 1998-12-04 | Central Japan Railway Co | Electromagnetic shielding window unit for railway vehicles |
| WO2020090727A1 (en) * | 2018-10-29 | 2020-05-07 | タツタ電線株式会社 | Electromagnetic wave shielding film, method of manufacturing shielded printed wiring board, and shielded printed wiring board |
| WO2020090726A1 (en) * | 2018-10-29 | 2020-05-07 | タツタ電線株式会社 | Electromagnetic shielding film, method for producing shielded printed wiring board, and shielded printed wiring board |
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| WO2022065380A1 (en) * | 2020-09-23 | 2022-03-31 | タツタ電線株式会社 | Electromagnetic wave shielding film and shielded printed wiring board |
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| JPH10322082A (en) * | 1997-03-19 | 1998-12-04 | Central Japan Railway Co | Electromagnetic shielding window unit for railway vehicles |
| WO2020090727A1 (en) * | 2018-10-29 | 2020-05-07 | タツタ電線株式会社 | Electromagnetic wave shielding film, method of manufacturing shielded printed wiring board, and shielded printed wiring board |
| WO2020090726A1 (en) * | 2018-10-29 | 2020-05-07 | タツタ電線株式会社 | Electromagnetic shielding film, method for producing shielded printed wiring board, and shielded printed wiring board |
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