WO2016117718A1

WO2016117718A1 - Electromagnetic wave shielding and absorbing sheet and manufacturing method of the same

Info

Publication number: WO2016117718A1
Application number: PCT/KR2015/000588
Authority: WO
Inventors: Yoon Hyun Kim; Kyu Jae Lee; Seung Jin Yang
Original assignee: Chang Sung Co., Ltd.
Priority date: 2015-01-20
Filing date: 2015-01-20
Publication date: 2016-07-28
Also published as: KR101661583B1

Abstract

The present invention relates to an electromagnetic wave shielding and absorbing sheet, and more particularly, by adding an electromagnetic wave shielding/thermally conductive adhesive layer including graphene on an electromagnetic wave absorbing layer, it is possible to emit heat generated from the electromagnetic wave absorbing layer to the outside and thus possible to increase electromagnetic wave absorbing efficiency.

Description

ELECTROMAGNETIC WAVE SHIELDING AND ABSORBING SHEET AND MANUFACTURING METHOD OF THE SAME

Embodiments of the inventive concept relates to an electromagnetic wave shielding and absorbing sheet having excellent thermal diffusivity and thermal conductivity and a manufacturing method of the same, and more particularly, to an electromagnetic wave shielding and absorbing sheet and a manufacturing method of the electromagnetic wave shielding and absorbing sheet integrated from an electromagnetic wave shielding/thermally conductive adhesive layer with an electromagnetic wave absorbing layer by way of hot pressing.

A printed circuit board (PCB) is a key component known as one of the four electronic components along with a semiconductor display and a secondary cell, and has been widely used in various electronic products such as computers, mobile phones, displays, communication networks, semiconductor modules as well as TVs. Particularly, a flexible printed circuit board (FPCB), which is a kind of printed circuit board, has been extensively used in recent years.

Due to advances in modern technology, the uses of small mobile phones, high-performance home appliances, and high-tech medical devices, which offer convenience of life, have increased. Within the above-mentioned electronic devices, electromagnetic waves interfere in operations of the electronic devices and thus cause malfunction thereof. In order to prevent electromagnetic interference between the electronic devices, a method for shielding electromagnetic waves has been actively studied.

A shielding effect of shielding electromagnetic waves may use loss characteristics caused by electromagnetic wave reflection on a surface of a material, electromagnetic wave absorption within the material, and multiple reflection in the material.

The present invention is conceived to solve the above-described problems, and provided to solve problems about electromagnetic wave absorption performance and heat emission caused by conversion of absorbed electromagnetic wave into heat by maximizing electromagnetic wave absorption by an induced magnetic field, arranging a material having an excellent heat transfer characteristic on an electromagnetic wave shielding layer and integrating the electromagnetic wave shielding layer and an electromagnetic wave absorbing layer to solve a problem about heat radiation caused by the induced magnetic field.

In an exemplary embodiment of the present invention, an electromagnetic wave shielding and absorbing sheet containing metal powder and a binder resin includes: an electromagnetic wave shielding/thermally conductive adhesive layer having electrical conductivity; and an electromagnetic wave absorbing layer formed on the other surface of the electromagnetic wave shielding/thermally conductive adhesive layer, wherein the electromagnetic wave shielding/thermally conductive adhesive layer and the electromagnetic wave absorbing layer are integrated with a conductive adhesive by way of hot pressing.

In an exemplary embodiment of the present invention, a manufacturing method of an electromagnetic wave shielding and absorbing sheet includes: a step of forming an electromagnetic wave absorbing layer containing metal powder on a coverlay film to be brought into contact with an electronic device (S10); a step of forming an electromagnetic wave shielding/thermally conductive adhesive layer on the electromagnetic wave absorbing layer (S20); and a step of integrating the coverlay film, the electromagnetic wave shielding/thermally conductive adhesive layer, and the electromagnetic wave absorbing layer by way of hot pressing at 100 to 150C under 30 to 50 kgf/cm²(S30), wherein the electromagnetic wave shielding/thermally conductive adhesive layer may include graphene which is a carbonaceous substance.

The electromagnetic wave shielding and absorbing sheet of the present invention is configured as being divided into an electromagnetic wave shielding layer and an electromagnetic wave absorbing layer to increase an electromagnetic wave shielding effect, and the electromagnetic wave shielding layer contains graphene having an excellent thermal conductivity. Therefore, heat generated from the electromagnetic wave absorbing layer can be emitted to the outside at a high speed, and, thus, it is possible to optimize efficiency for electromagnetic wave shielding and absorption.

Further, the electromagnetic wave shielding and absorbing sheet of the present invention satisfies an impedance matching condition by adjusting impedance through the graphene layer servingas the electromagnetic wave shielding/thermally conductive adhesive layer, and, thus, it is possible to maximize efficiency for electromagnetic wave absorption.

Figure 1 is a schematic diagram showing a configuration of an electromagnetic wave shielding and absorbing sheet according to an exemplary embodiment of the present invention.

Figure 2 is a schematic diagram showing a configuration of an electromagnetic wave shielding and absorbing sheet according to another exemplary embodiment of the present invention.

Figure 3 is a schematic diagram showing an impedance matching process in an electromagnetic wave shielding sheet.

Figure 4 provides photos showing data measured by a thermal imaging camera according to an exemplary embodiment of the present invention.

Advantages and features of the present invention, and inventions for accomplishing the same will be more clearly understood from exemplary embodiments described below with reference to the accompanying drawings.

However, the present invention is not limited to the following exemplary embodiments but may be implemented in various different forms. The exemplary embodiments are defined only to complete disclosure of the present invention and to fully provide those skilled in the art to which the present invention pertains with the category of the invention. In the accompanying drawings, respective layers and regions may be exaggerated in size and relative size for clarity of explanation.

Hereinafter, an electromagnetic wave shielding and absorbing sheet will be described in detail.

An electromagnetic wave shielding and absorbing sheet according to an exemplary embodiment of the present invention may include a graphene layer. The graphene layer may be a mixture of graphene, which is a carbonaceous substance, on a polymer resin.

The graphene may have a thermal conductivity of 6000 W/mk and an electrical conductivity of 6000 S/cm or more.

The graphene is a carbonaceous substance and has an excellent thermal conduction characteristic and also functions to increase an heat radiation effect by forming micro pores in an inorganic compound and thus increasing a surface area. If the content of the graphene is not enough, heat radiation may decrease, and if the content of the graphene is excessive, internal adhesion of an electromagnetic wave shielding/thermally conductive adhesive layer may decrease.

The polymer resin may include an adhesive bisphenolA-type epoxy resin, a CTBN modified epoxy resin, and a thermoplastic polyurethane resin.

Bisphenol A is an organic compound prepared by condensation of one molecule of acetone and two molecules of phenol. The bisphenol A has been mainly used as a synthetic material of polycarbonate plastic and epoxy resins. The bisphenol A has a low resistance since it is greatly contracted during curing, and may impart adhesion when the electromagnetic wave shielding and absorbing sheet adheres to an electromagnetic wave absorbing layer.

The polyurethane resin may be a polyurethane prepolymer which is obtained by reacting organic isocyanate with polyol in the presence of a silicon modifier. The organic isocyanate may include those known in the art for preparing polyurethane and may be selected from aromatic, aliphatic, cycloaliphatic, and aromatic polyisocyanates. The polyol has a molecular weight Mw of 400 to 6000, preferably, 1000 to 4000, in order for the polyurethane resin to maintain viscosity at a certain level. Further, it is desirable to use a product having OH of 35 to 250, preferably, 35 to 180. The polyurethane resin may improve the adhesion of the electromagnetic wave shielding/thermally conductive adhesive layer according to the exemplary embodiment of the present invention.

The CTBN (Carboxylic Terminated Butadiene Acryylonitrile) modified epoxy resin is compatible with a typical epoxy resin and has an excellent adhesion strength and may have an excellent elasticity. The CTBN modified epoxy resin may improve workability of the electromagnetic wave shielding and absorbing sheet including the graphene layer.

Since the composition of the polymer resin includes graphene, the electrical conductivity of the electromagnetic wave shielding/thermally conductive adhesive layer can be improved.

A shielding principle of the electromagnetic wave shielding and absorbing sheet in which graphene is deposited will be described in detail as follows.

If an electromagnetic wave is incident to the shielding and absorbing sheet, the electromagnetic wave is absorbed, reflected, diffracted, or penetrated. In this case, the total of shielding effects is referred to as shielding efficiency and expressed by the following (Equation 1).

(Equation 1)

SE = SER + SEA + SEB

Herein, SER represents a diminution dB caused by reflection, SEA represents a diminution dB caused by absorption, and SEB represents a diminution dB caused by reflection within the shielding sheet. In the above (Equation 1), if SEA is 1 or more, SEB can be neglected. Further, SER (diminution caused by reflection) and SEA (diminution caused by absorption) can be expressed by the following (Equations 2 and 3).

(Equation 2)

SER =50+ 10 log(ρF) - 1

(Equation 3)

SEA = 1.7t( F/ρ)½

In the above Equations 2 and 3, ρ represents volume resistivity (W cm), F represents a frequency (MHz), and t represents a thickness (cm) of the shielding sheet.

Referring to the Equations 2 and 3, it can be seen that the shielding efficiency increases as the thickness of the shielding sheet increases or the volume resistivity decreases.

Generally, the following standard is applied to a level of a shielding effect. In a range from about 0 dB to about 10 dB, there is little shielding effect, and in a range from about 10 dB to about 30 dB, there is a shielding effect to a certain extent or more. Further, in a range from about 30 dB to about 60 dB, an average shielding effect can be expected, in a range from about 60 dB to about 90 dB, a shielding effect is above the average, and in a range of about 90 dB or more, almost all of electromagnetic waves can be shielded. Generally, it is known that electromagnetic wave shielding sheets using metals have a shielding effect of about 60 dB or more.

Figure 1 is a diagram showing a configuration of an electromagnetic wave shielding and absorbing sheet according to an exemplary embodiment of the present invention.

Referring to Figure 1, an electromagnetic wave shielding and absorbing sheet may include an electromagnetic wave shielding/thermally conductive adhesive layer 120 and an electromagnetic wave absorbing layer 110. An insulating layer (not illustrated) may be added on a top surface of the electromagnetic wave shielding/thermally conductive adhesive layer 120.

The electromagnetic waveabsorbing layer 110 is prepared from a mixture in which metal powder is dispersed in a binder, and the metal powder may be formed of at least any one or a combination of two or more of iron (Fe), aluminum (Al), chromium (Cr), nickel (Ni), and manganese (Mn).

The binder include at least any one or more of a phenol resin, a urea resin, a melamine resin, Teflon, polyamide, polyvinyl chloride, flame-retardant polyethylene, flame-retardant polypropylene, flame-retardant polystyrene, polyphenylene sulfide, flame-retardant PET, flame-retardant PBT, flame-retardant polyolefin, a silicon resin, an epoxy resin, chlorinated polyethylene, ethylene propylene dimethyl, an acrylic resin, an amide-based resin, a polyester-based resin, a polyethylene-based resin, ethylene-propylene rubber, a polyvinyl butyral resin, a polyurethane resin, and nitrile butadiene-based rubber.

The electromagnetic wave shielding/thermally conductive adhesive layer 120 may have the form in which graphene is bonded by a polymer resin. The polymer resin may include a bisphenol A-type epoxy resin, a CTBN modified epoxy resin, and a thermoplastic polyurethane resin. The binding force with respect to the electromagnetic wave absorbing layer 110 can be improved by the action of the polymer resin. The polymer resin may be a conductive adhesive. The electromagnetic wave shielding/thermally conductive adhesive layer 120 may include a solvent (ethyl acetate, toluene, MEK (methyl ethyl ketone).

The polymer resin may further include an epoxy curing agent and a curing accelerator.

The electromagnetic wave absorbing layer 110 and the electromagnetic wave shielding/thermally conductive adhesive layer 120 may be integrated by way of uniaxial pressing (hot pressing). The hot pressing process may be carried out at a temperature of 100 to 150C. A pressure to be applied in the hot pressing process may be 30 to 50 kgf/cm². The hot pressing process may be carried out for 20 minutes to 1 hour. As an apparatus for the hot pressing process, a 17 ton press, which is a vacuum press manufactured by Sun Jin HighM Inc., may be used.

Figure 2 is a diagram showing a configuration of an electromagnetic wave shielding and absorbing sheet according to another exemplary embodiment of the present invention.

Referring to Figure 2, a configuration of an electromagnetic wave shielding and absorbing sheet according to another exemplary embodiment of the present invention may further include an electromagnetic wave shielding layer on the electromagnetic wave shielding/thermally conductive adhesive layer 120.

The electromagnetic wave shielding layer 130 is configured to obtain the electromagnetic wave shielding performance and may include 30 to 40 wt% of copper, silver, silver-coated copper,or silver-coated nickel as a conductive substance. The silver-coated copper or the silver-coated nickel may have the form in which a dendrite or flake surface is coated with silver. If silver is coated on a surface of copper or nickel, it is possible toprevent degradation of the copper or nickel caused by a reaction with the solvent (ethylene acetate, toluene, MEK (methyl ethyl ketone)). If degradation of the copper dendrite or the nickel dendrite is prevented, the electromagnetic wave shielding layer 130 can be used semipermanently.

In the silver-coated copper, 10 to 30 wt% of silver may be coated on a copper dendrite.

The above-described hot pressing process may be carried out to an electromagnetic wave shielding and absorbing sheet 101 of Figure 2 in the same manner as to the electromagnetic wave shielding and absorbing sheet 100 of Figure 1.

Referring to Figure 3, when an electromagnetic wave reflected from an electromagnetic wave reflector and present within the electromagnetic wave absorbing layer 110 has an impedance within the electromagnetic wave absorbing layer 110 so as to be matched with an impedance in the air before entering into the electromagnetic wave absorbing layer 110, it is called "impedance matching". In this case, reflection becomes minimum due to impedance matching, which means that a normally incident electromagnetic wave is absorbed by the electromagnetic wave absorbing layer 110 and dissipated in heat.

The electromagnetic wave shielding and absorbing sheet 100 according to the exemplary embodiment of the present invention may improve the absorption performance of the electromagnetic wave absorbing layer 110 by adjusting a thickness of the electromagnetic wave shielding/thermally conductive adhesive layer 120 including graphene. By varying a thickness of the electromagnetic wave shielding/thermally conductive adhesive layer 120 including graphene or modifying a physiochemical property of the electromagnetic wave shielding/thermally conductive adhesive layer 120 including graphene to improve the electromagnetic wave shielding efficiency, the electromagnetic wave shielding efficiency can be changed.

The electromagnetic wave shielding and absorbing sheet 100 according to the exemplary embodiment of the present invention may use a layer containing a metal as the absorbing layer 110, and, thus, an induced current may be caused by an induced magnetic field. Absorption of an electromagnetic wave by the current generated as such can be maximized. Further, the electromagnetic wave shielding/thermally conductive adhesive layer 120 including graphene may have an excellent thermal conductivity. If the electromagnetic wave shielding/thermally conductive adhesive layer 120 has an excellent heat transfer performance as described above, heat accumulated in the electromagnetic wave absorbing layer 110 is exhausted in a short time, and, thus, the electromagnetic wave absorbing and shielding performance can be maximized.

An electromagnetic wave shielding and absorbing sheet according to an exemplary embodiment of the present invention may have a thermal diffusivity of 800 to 2000 mm²/s and a thermal conductivity of 200 to 1000 W/mK. If the thermal diffusivity and the thermal conductivity are high as described above, heat accumulated in the electromagnetic wave absorbing layer 110 can be rapidly transferred to the outside, and, thus, the electromagnetic wave shielding and absorbing

sheet

100, 101 can be protected so as to perform its function for a long time. Further, by shielding and absorbing an electromagnetic wave generated in an FPCB (flexible printed circuit board), an electronic device can be protected from EMI (electromagnetic interference).

Figure 4 provides graphs showing thermal diffusivity of an electromagnetic wave shielding and absorbing sheet including graphene according to an exemplary embodiment of the present invention.

Referring to Figure 4, Figure 4(a) shows a result of temperature measurement in the case where an electromagnetic wave shielding/thermally conductive adhesive layer including graphene is not included according to a comparative example, and Figure 4(b) shows a result of temperature measurement in the case where graphene is included according to an exemplary embodiment.

As can be seen from Figure 4, the first electromagnetic wave shielding and absorbing sheet 101 including graphene according to an exemplary embodiment of the present invention includes the electromagnetic wave absorbing layer 110 as an undermost layer and may include the electromagnetic wave shielding/thermally conductive adhesive layer 120 on the electromagnetic wave absorbing layer 110 and the electromagnetic wave shielding layer 130 on the electromagnetic wave shielding/thermally conductive adhesive layer 120. The electromagnetic wave shielding layer 130 contains silver-coated copper, and, thus, an excellent electromagnetic shielding characteristic can be exhibited. Further, since a surface resistance is 100 to 200 mΩ/sq, an excellent electromagnetic shielding characteristic can be expressed. In comparison, the electromagnetic wave shielding and absorbing sheet according to the comparative example may include the electromagnetic wave shielding layer 130 formed on a top surface of the electromagnetic wave absorbing layer 110.

When a temperature of the electromagnetic wave absorbing layer 110 is increased under the above-described conditions, the highest temperature of the electromagnetic wave shielding and absorbing sheet 101 according to the exemplary embodiment of the present invention was measured at 42.3C and the highest temperature in the case where the electromagnetic wave shielding/thermally conductive adhesive layer 120 including graphene is not included according to the comparative example was measured at 50.4C. Therefore, it can be seen that a heat transfer characteristic in the exemplary embodiment of the present invention is excellent. Further, a temperature difference (denoted by dT) between the electromagnetic wave shielding layer 130 and the electromagnetic wave absorbing layer 110 in the electromagnetic wave shielding and absorbing sheet 101 according to the exemplary embodiment of the present invention was 7.2C, and it is smaller than 20.3Cwhich is a temperature difference in the electromagnetic wave shielding and absorbing sheet according to the comparative example. According to the fact as described above, it can be seen that the electromagnetic wave shielding and absorbing

sheet

100, 101 according to the exemplary embodiment of the present invention emits heat accumulated in the electromagnetic wave absorbing layer 110 at a high speed and reduces a temperature difference with respect to the atmosphere, and, thus, it has an excellent thermal diffusivity.

It can be seen that a thermal conductivity and a thermal diffusivity of the electromagnetic wave shielding and absorbing sheet according to the exemplary embodiment of the present invention were measured at 520 W/mK and 1020 mm²/s, respectively, and, thus, it has a high thermal conductivity and a high thermal diffusivity.

Hereinafter, a manufacturing method of the electromagnetic wave shielding and absorbing

sheet

100, 101 according to an exemplary embodiment of the present invention will be described in detail.

In an exemplary embodiment of the present invention, a manufacturing method of an electromagnetic wave shielding and absorbing sheet includes: a step of forming an electromagnetic wave absorbing layer containing metal powder on a coverlay film to be brought into contact with an electronic device (S10); a step of forming the electromagnetic wave shielding/thermally conductive adhesive layer 120 on the electromagnetic wave absorbing layer 110 (S20); and a step of integrating the coverlay film, the electromagnetic wave shielding/thermally conductive adhesive layer, and the electromagnetic wave absorbing layer by way of hot pressing at 100 to 150C under 30 to 50 kgf/cm²(S30), wherein the electromagnetic wave shielding/thermally conductive adhesive layer 120 may include graphene which is a carbonaceous substance.

The electromagnetic wave absorbing layer 110 is prepared from a mixture in which metal powder is dispersed in a binder, and the metal powder may be formed of at least any one or a combination of two or more of iron (Fe), aluminum (Al), chromium (Cr), nickel (Ni), and manganese (Mn).

The metal powder may be mixed with the binder, and a composition of the electromagnetic wave absorbing layer 110 may be coated on the coverlay film. The coverlay film coated with the electromagnetic wave absorbing layer 110 in the coating process prevents an electronic device which generates an electromagnetic wave from being oxidized by contact with air and functions to insulate the electronic device from the electromagnetic wave shielding and absorbing

sheet

100, 101. Typically, a film obtained from a polymer having a high thermal resistance and a low contraction rate may be used as the coverlay film. Preferably, a polyimide (PI) film of 5 to 50 m may be used.

For cross-linking between the components in the electromagnetic wave absorbing layer 110, any one or more of a thermal stabilizer, a catalyst, a cross-linking agent, a surface modifier, and an ultraviolet absorber may be added besides the basic components including the powder and the matrix resin for polymer binder.

The composition of the electromagnetic wave absorbing layer 110 is diluted in a polar solvent and then coated on the coverlay film. The polar solvent for dilution may be one or more of, for example, alcohols such as ethanol and isopropyl alcohol, water, and NMP (N-Methylpyrrolidone). As a method for coating the electromagnetic wave absorbing layer 110 in accordance with an exemplary embodiment of the present invention, coating methods known in the art, such as comma coating, knife coating, bar coating, spin coating, etc., may be applied.

Preferably, a thickness of the coating may be in the range of 0.05 to 0.5 mm after curing and drying.

The electromagnetic wave shielding/thermally conductive adhesive layer 120 may include a bisphenol A-type epoxy resin, a CTBN modified epoxy resin, and a thermoplastic polyurethane resin as a resin which can impart adhesiveness and flexibility. An epoxy curing agent and a curing accelerator are added to the resin, and any one or more of toluene, MEK (methyl ethyl ketone), and ethyl acetate may be mixed and used as a solvent. After the polymer resin is mixed with the graphene powder and the epoxy curing agent and the curing accelerator are added, the mixture may be coated on the electromagnetic wave absorbing layer 110 using a slot die coater or a comma coater and then dried at 100 to 150℃. After the drying process, the electromagnetic wave shielding/thermally conductive adhesive layer 120 in a semi-cured state can be formed.

As described above, the electromagnetic wave absorbing layer 110 and the electromagnetic wave shielding/thermally conductive adhesive layer 120 may be integrated on the coverlay film using the hot pressing process.

The integration process may be carried out by way of hot pressing at 100 to 150C under 30 to 50 kgf/cm².

The coverlay film may include polyimide. The polyimide may be a surface layer of an FPCB (Flexible Printed Circuit Board) including a stepped portion on which an FR-4 (Flame Retardant-4) is formed. Therefore, the electromagnetic wave shielding and absorbing sheet including graphene according to an exemplary embodiment of the present invention can be used as an electromagnetic wave shielding and absorbing sheet of an FPCB.

Although the present invention has been described with reference to the accompanying drawings, this is just one of various exemplary embodiments including the subject matter of the present invention and intends to allow those skilled in the art to easily implement the present invention. It is clear that the present invention is not limited to the above-described exemplary embodiments. Therefore, the scope of the present invention should be construed by the following claims. Without departing from the subject matter of the present invention, all the technical spirits within the scope equivalent to the subject matter of the present invention are included in the right scope of the present invention by modifications, substitutions, changes, and the like. Also, it is clear that some of the drawing configuration are intended for more clearly describing the configuration and are more exaggerated or shortened than the actual ones.

Claims

An electromagnetic wave shielding and absorbing sheet containing metal powder and a binder resin comprising:

an electromagnetic wave shielding/thermally conductive adhesive layer having electrical conductivity; and

an electromagnetic wave absorbing layer formed on the other surface of the electromagnetic wave shielding/thermally conductive adhesive layer,

wherein the electromagnetic wave shielding/thermally conductive adhesive layer and the electromagnetic wave absorbing layer are bonded with a conductive adhesive and integrated by way of hot pressing.
The electromagnetic wave shielding and absorbing sheet of claim 1,

wherein the electromagnetic wave shielding/thermally conductive adhesive layer includes graphene.
The electromagnetic wave shielding and absorbing sheet of claim 1,

wherein the metal powder is formed of at least any one or a combination of two or more of iron (Fe), aluminum (Al), chromium (Cr), nickel (Ni), and manganese (Mn).
The electromagnetic wave shielding and absorbing sheet of claim 1,

wherein the conductive adhesive includes one or more selected from bisphenol A-type epoxy, CTBN modified epoxy, and thermoplastic polyurethane.
The electromagnetic wave shielding and absorbing sheet of claim 1, further comprising:

an electromagnetic wave shielding layer on a top surface of the electromagnetic wave shielding/thermally conductive adhesive layer.
The electromagnetic wave shielding and absorbing sheet of claim 5,

wherein the hot pressing is carried out by uniaxially pressing at a temperature of 100 to 150℃ under a pressure of 30 to 50 kgf/cm².
The electromagnetic wave shielding and absorbing sheet of claim 5,

wherein the electromagnetic wave shielding layer further includes a metal dendrite or a metal flake.
The electromagnetic wave shielding and absorbing sheet of claim 7,

wherein the metal dendrite or the metal flake includes copper, silver, or silver-coated copper.
The electromagnetic wave shielding and absorbing sheet of claim 8,

wherein in the silver-coated copper, 10 to 30 wt% of silver is coated on a copper dendrite.
The electromagnetic wave shielding and absorbing sheet of claim 1,

wherein the electromagnetic wave shielding and absorbing sheet has

a thermal diffusivity of 800 to 2000 mm²/s, and

a thermal conductivity of 200 to 1000 W/mK.
The electromagnetic wave shielding and absorbing sheet of claim 1,

wherein in the electromagnetic wave shielding and absorbing sheet, an impedance is matched by adjusting a thickness of the electromagnetic wave shielding/thermally conductive adhesive layer.
A manufacturing method of an electromagnetic wave shielding and absorbing sheet comprising:

a step of forming an electromagnetic wave absorbing layer containing metal powder on a coverlay film to be brought into contact with an electronic device (S10);

a step of forming an electromagnetic wave shielding/thermally conductive adhesive layer on the electromagnetic wave absorbing layer (S20); and

a step of integrating the coverlay film, the electromagnetic wave shielding/thermally conductive adhesive layer, and the electromagnetic wave absorbing layer by way of hot pressing at 100 to 150C under 30 to 50 kgf/cm²(S30),

wherein the electromagnetic wave shielding/thermally conductive adhesive layer includes graphene which is a carbonaceous substance.
The manufacturing method of an electromagnetic wave shielding and absorbing sheet of claim 12,

wherein the metal powder is formed of at least any one or a combination of two or more of iron (Fe), aluminum (Al), chromium (Cr), nickel (Ni), and manganese (Mn).
The manufacturing method of an electromagnetic wave shielding and absorbing sheet of claim 12,

wherein the coverlay film includes polyimide.