ELECTROMAGNETIC WAVE ABSORBING COMPOSITE SHEET

Abstract

An electromagnetic wave absorbing composite sheet comprising an electromagnetic wave absorbing film (1) and an electromagnetic wave shielding film (2) laminated on the electromagnetic wave absorbing film (1); wherein the electromagnetic wave absorbing film (1) has a single- or multi-layered thin metal film (12) formed on a surface of a plastic film (11), the thin metal film (12) being provided in a large number (plurality) of substantially parallel, intermittent, linear scratches (13a, 13b) with irregular widths and intervals in multiple directions; characterized in that an area ratio of the electromagnetic wave shielding film (2) to the electromagnetic wave absorbing film (1) is 10-80%.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to an electromagnetic wave absorbing composite sheet having high absorbability to electromagnetic wave noise in a desired frequency range and capable of shifting a frequency range in which the absorbability of electromagnetic wave noise is maximized. BACKGROUND OF THE INVENTION

[0002] Electrical and electronic devices emit electromagnetic wave noise, and ambient electromagnetic wave noise penetrates them, resulting in noise in signals. To prevent the emission and penetration of electromagnetic wave noise, electrical and electronic devices have traditionally been shielded with metal sheets. It is also proposed to place electromagnetic wave-absorbing films inside electrical and electronic devices to absorb electromagnetic wave noise.

[0003] For example, WO 2010 / 093027 A1 discloses a linearly scratched, metal-film-plastic composite thin film with reduced anisotropy in electromagnetic wave absorbability, comprising a plastic film and a single- or multi-layered metal thin film formed on at least one surface of the plastic film, wherein the metal thin film is provided with a large number of substantially parallel, intermittent linear scratches with irregular widths and intervals in multiple directions. WO 2010 / 093027 A1 describes that the linearly scratched, metal-film-plastic composite thin film may be laminated with an electromagnetic wave reflector (a sheet, a metal mesh or braid, a plastic film with a metal thin film, etc.) via a dielectric layer to obtain a composite electromagnetic wave absorber.This composite electromagnetic wave absorber has high absorption capacity to electromagnetic wave noise in a wide frequency, but has no function of showing particularly large absorption capacity to electromagnetic wave noise in a certain frequency range and no function of shifting a frequency range in which the electromagnetic wave absorption capacity is maximized.

[0004] WO 2013 / 081043 A1 discloses an electromagnetic wave absorbing composite sheet comprising (a) a first electromagnetic wave absorbing film comprising a plastic film and a single- or multi-layered thin metal film formed on at least one surface of the plastic film, wherein the thin metal film is provided with a large number of substantially parallel, intermittent linear scratches with irregular widths and intervals in multiple directions; and (b) a second electromagnetic wave absorbing film made of a resin or rubber in which magnetic or non-magnetic particles are dispersed.This electromagnetic wave absorbing composite sheet has high absorption capacity to electromagnetic wave noise in a wide frequency, but has no function of showing particularly large absorption capacity to electromagnetic wave noise in a certain frequency range and no function of shifting a frequency range in which the electromagnetic wave absorption capacity is maximized. OBJECT OF THE INVENTION

[0005] Accordingly, it is an object of the present invention to provide an electromagnetic wave absorbing composite sheet having a high absorbing ability to electromagnetic wave noise in a desired frequency range and capable of shifting a frequency range in which the absorbing ability of electromagnetic wave noise is maximized. SUMMARY OF THE INVENTION

[0006] As a result of intensive research in view of the above object, the inventor has found that an electromagnetic wave absorbing composite sheet having high absorbability against electromagnetic wave noise in a desired frequency range and capable of shifting a frequency range in which the absorbability of electromagnetic wave noise is maximized can be obtained by laminating an electromagnetic wave shielding film on an electromagnetic wave absorbing film with a thin metal film provided with a large number (plurality) of substantially parallel, intermittent, linear scratches with irregular widths and intervals in multiple directions, and setting an area ratio of the electromagnetic wave shielding film to the electromagnetic wave absorbing film to 10-80%.The present invention was completed based on such findings.

[0007] Therefore, the electromagnetic wave absorbing composite sheet of the present invention comprises an electromagnetic wave absorbing film and an electromagnetic wave shielding film laminated on the electromagnetic wave absorbing film; wherein the electromagnetic wave absorbing film comprises a single- or multi-layered thin metal film formed on a surface of a plastic film, the thin metal film being provided with a large number (plurality) of substantially parallel, intermittent, linear scratches having irregular widths and intervals in multiple directions; and wherein an area ratio of the electromagnetic wave shielding film to the electromagnetic wave absorbing film is 10-80%.

[0008] The area ratio of the electromagnetic wave shielding film to the electromagnetic wave absorbing film is preferably 20-80%, more preferably 30-70%, most preferably 40-60%.

[0009] The electromagnetic wave shielding film is preferably a conductive metal foil, a plastic film with a thin conductive metal film or coating, or a carbon sheet.

[0010] The linear scratches in the electromagnetic wave absorbing film preferably have widths in a range of 0.1-100 µm for 90% or more and 1-50 µm on average and lateral distances in a range of 1-500 µm and 1-200 µm on average.

[0011] The linear scratches in the electromagnetic wave absorbing film preferably have an acute crossing angle θs in a range of 30-90°.

[0012] The conductive metal in the electromagnetic wave shielding film is preferably at least one selected from the group consisting of aluminum, copper, silver, tin, nickel, cobalt, chromium and their alloys.

[0013] Both the electromagnetic wave absorbing film and the electromagnetic wave shielding film are preferably in a rectangular or square shape. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1(a) is an exploded plan view showing an example of the electromagnetic wave absorbing composite sheets of the present invention. Fig. 1(b) is a plan view showing an example of the electromagnetic wave absorbing composite sheets of the present invention. Fig. 2(a) is a cross-sectional view showing an example of electromagnetic wave absorbing films constituting the electromagnetic wave absorbing composite sheet of the present invention. Fig. Figure 2(b) is a partial plan view showing an example of linear scratches of an electromagnetic wave absorbing film. Fig. 2(c) is a cross-sectional view taken along the line AA in Fig. 2(b). Fig. 2(d) is an enlarged cross-sectional view showing a section B in Fig. 2(c) shows. Fig. Figure 2(e) is a cross-sectional view showing another example of electromagnetic wave absorbing films. Fig. 2(f) is an enlarged cross-sectional view showing a section C in Fig. 2(e) shows. Fig. 3(a) is a perspective view showing an example of devices for forming linear scratches. Fig. 3(b) is a plan view showing the device of Fig. 3(a) shows. Fig. 3(c) is a cross-sectional view taken along line BB in Fig. 3(b). Fig. 3(d) is an enlarged partial plan view showing the principle of forming linear scratches to the moving direction of a composite film. Fig. 3(e) is a partial plan view showing the inclination angles of a pattern roller and a push roller to a composite film in the apparatus of Fig. 3(a) shows. Fig. 4 is a partial cross-sectional view showing an apparatus for forming linear scratches. Fig. 5 is a perspective view showing another example of linear scratch forming apparatuses. Fig. 6(a) is a plan view showing another example of the electromagnetic wave absorbing composite sheets of the present invention. Fig. 6(b) is a plan view showing another example of the electromagnetic wave absorbing composite sheets of the present invention. Fig. Figure 7(a) is a plan view showing a system for measuring the forces of reflected wave and transmitted wave against incident wave. Fig. Figure 7(b) is a schematic partial cross-sectional view showing the system of Fig. 7(a) shows. Fig. Figure 8 is a plan view showing an example of samples placed on a microstripline (MSL). Fig. 9 is a graph showing the noise absorption ratio P loss / P in of Sample 1 (crossing angle θs of linear scratches = 90° and area ratio of aluminum foil piece = 0%) of the electromagnetic wave absorbing composite sheet. Fig. 10 is a graph showing the noise absorption ratio P loss / P inof Sample 2 (crossing angle θs of linear scratches = 90° and area ratio of aluminum foil piece = 20%) of the electromagnetic wave absorbing composite sheet. Fig. 11 is a graph showing the noise absorption ratio P loss / P in of Sample 3 (crossing angle θs of linear scratches = 90° and area ratio of aluminum foil piece = 40%) of the electromagnetic wave absorbing composite sheet. Fig. 12 is a graph showing the noise absorption ratio P loss / P in of Sample 4 (crossing angle θs of linear scratches = 90° and area ratio of aluminum foil piece = 50%) of the electromagnetic wave absorbing composite sheet. Fig. 13 is a graph showing the noise absorption ratio P loss / P inof Sample 5 (crossing angle θs of linear scratches = 90° and area ratio of aluminum foil piece = 60%) of the electromagnetic wave absorbing composite sheet. Fig. 14 is a graph showing the noise absorption ratio P loss / P in of Sample 6 (crossing angle θs of linear scratches = 90° and area ratio of aluminum foil piece = 80%) of the electromagnetic wave absorbing composite sheet. Fig. 15 is a graph showing the noise absorption ratio P loss / P in of Sample 7 (crossing angle θs of linear scratches = 90° and area ratio of aluminum foil piece = 100%) of the electromagnetic wave absorbing composite sheet. Fig. 16 is a plan view showing samples 21 and 22 of the electromagnetic wave absorbing composite sheet. Fig. 17 is a diagram showing the noise absorption ratios P loss / P in of samples 21 and 22 of electromagnetic wave absorbing composite sheets comprising aluminum foil pieces in different shapes, together with the noise absorption ratios P loss / P in of samples 1 and 4. Fig. Figure 18(a) is a graph showing electromagnetic wave noise at a frequency near 3 GHz derived from Fire Stick TV when the electromagnetic wave absorbing composite sheet of Example 4 was placed on an IC chip in Fire Stick TV. Fig. Figure 18(b) is a graph showing electromagnetic wave noise at a frequency near 3 GHz derived from Fire Stick TV without the electromagnetic wave absorbing composite sheet. Fig. 19 is a diagram showing the noise absorption ratios P loss / P inof samples 31-33 of the electromagnetic wave absorbing composite sheets comprising carbon sheet pieces of graphite powder / carbon black. Fig. 20 is a graph showing the noise absorption ratio P loss / P in of Sample 41 (crossing angle θs of linear scratches = 60° and area ratio of aluminum foil piece = 20%) of the electromagnetic wave absorbing composite sheet. Fig. 21 is a diagram showing the noise absorption ratio P loss / P in of Sample 42 (crossing angle θs of linear scratches = 60° and area ratio of aluminum foil piece = 30%) of the electromagnetic wave absorbing composite sheet. Fig. 22 is a graph showing the noise absorption ratio P loss / P inof Sample 43 (crossing angle θs of linear scratches = 60° and area ratio of aluminum foil piece = 40%) of the electromagnetic wave absorbing composite sheet. Fig. 23 is a diagram showing the noise absorption ratio P loss / P in of Sample 44 (crossing angle θs of linear scratches = 60° and area ratio of aluminum foil piece = 50%) of the electromagnetic wave absorbing composite sheet. Fig. 24 is a graph showing the noise absorption ratio P loss / P in of Sample 45 (crossing angle θs of linear scratches = 60° and area ratio of aluminum foil piece = 60%) of the electromagnetic wave absorbing composite sheet. Fig. 25 is a diagram showing the noise absorption ratio P loss / P inof Sample 46 (crossing angle θs of linear scratches = 60° and area ratio of aluminum foil piece = 70%) of the electromagnetic wave absorbing composite sheet. Fig. 26 is a graph showing the noise absorption ratio P loss / P in of Sample 47 (crossing angle θs of linear scratches = 60° and area ratio of aluminum foil piece = 80%) of the electromagnetic wave absorbing composite sheet. Fig. 27 is a graph showing the noise absorption ratio P loss / P in of Sample 48 (crossing angle θs of linear scratches = 60° and area ratio of aluminum foil piece = 100%) of the electromagnetic wave absorbing composite sheet. Fig. 28 is a diagram showing the noise absorption ratio P loss / P inof Sample 51 (crossing angle θs of linear scratches = 60° and distance D from aluminum foil piece = 0 mm) of the electromagnetic wave absorbing composite sheet. Fig. 29 is a diagram showing the noise absorption ratio P loss / P in of Sample 52 (crossing angle θs of linear scratches = 60° and distance D from aluminum foil piece = 5 mm) of the electromagnetic wave absorbing composite sheet. Fig. 30 is a graph showing the noise absorption ratio P loss / P in of Sample 53 (crossing angle θs of linear scratches = 60° and distance D from aluminum foil piece = 10 mm) of the electromagnetic wave absorbing composite sheet. Fig. 31 is a diagram showing the noise absorption ratio P loss / P inof Sample 54 (crossing angle θs of linear scratches = 60° and distance D from aluminum foil piece = 15 mm) of the electromagnetic wave absorbing composite sheet. Fig. 32 is a diagram showing the noise absorption ratio P loss / P in of Sample 55 (crossing angle θs of linear scratches = 60° and distance D from aluminum foil piece = 20 mm) of the electromagnetic wave absorbing composite sheet. Fig. 33 is a diagram showing the noise absorption ratio P loss / P in of Sample 56 (crossing angle θs of linear scratches = 60° and distance D from aluminum foil piece = 25 mm) of the electromagnetic wave absorbing composite sheet. Fig. 34 is a diagram showing the noise absorption ratio P loss / P inof Sample 61 (crossing angle θs of linear scratches = 30° and area ratio of aluminum foil piece = 20%) of the electromagnetic wave absorbing composite sheet. Fig. 35 is a diagram showing the noise absorption ratio P loss / P in of Sample 62 (crossing angle θs of linear scratches = 30° and area ratio of aluminum foil piece = 30%) of the electromagnetic wave absorbing composite sheet. Fig. 36 is a graph showing the noise absorption ratio P loss / P in of Sample 63 (crossing angle θs of linear scratches = 30° and area ratio of aluminum foil piece = 40%) of the electromagnetic wave absorbing composite sheet. Fig. 37 is a diagram showing the noise absorption ratio P loss / P inof Sample 64 (crossing angle θs of linear scratches = 30° and area ratio of aluminum foil piece = 50%) of the electromagnetic wave absorbing composite sheet. Fig. 38 is a diagram showing the noise absorption ratio P loss / P in of Sample 65 (crossing angle θs of linear scratches = 30° and area ratio of aluminum foil piece = 60%) of the electromagnetic wave absorbing composite sheet. Fig. 39 is a diagram showing the noise absorption ratio P loss / P in of Sample 66 (crossing angle θs of linear scratches = 30° and area ratio of aluminum foil piece = 70%) of the electromagnetic wave absorbing composite sheet. Fig. 40 is a diagram showing the noise absorption ratio P loss / P inof Sample 67 (crossing angle θs of linear scratches = 30° and area ratio of aluminum foil piece = 80%) of the electromagnetic wave absorbing composite sheet. Fig. 41 is a diagram showing the noise absorption ratio P loss / P in of Sample 68 (crossing angle θs of linear scratches = 30° and area ratio of aluminum foil piece = 100%) of the electromagnetic wave absorbing composite sheet. Fig. 42 is a diagram showing the noise absorption ratio P loss / P in of Sample 71 (crossing angle θs of linear scratches = 30° and distance D from aluminum foil piece = 0 mm) of the electromagnetic wave absorbing composite sheet. Fig. 43 is a diagram showing the noise absorption ratio P loss / P inof Sample 72 (crossing angle θs of linear scratches = 30° and distance D from aluminum foil piece = 5 mm) of the electromagnetic wave absorbing composite sheet. Fig. 44 is a diagram showing the noise absorption ratio P loss / P in of Sample 73 (crossing angle θs of linear scratches = 30° and distance D from aluminum foil piece = 10 mm) of the electromagnetic wave absorbing composite sheet. Fig. 45 is a diagram showing the noise absorption ratio P loss / P in of Sample 74 (crossing angle θs of linear scratches = 30° and distance D from aluminum foil piece = 15 mm) of the electromagnetic wave absorbing composite sheet. Fig. 46 is a diagram showing the noise absorption ratio P loss / P inof Sample 75 (crossing angle θs of linear scratches = 30° and distance D from aluminum foil piece = 20 mm) of the electromagnetic wave absorbing composite sheet. Fig. 47 is a diagram showing the noise absorption ratio P loss / P in of Sample 76 (crossing angle θs of linear scratches = 30° and distance D from aluminum foil piece = 25 mm) of the electromagnetic wave absorbing composite sheet. Fig. 48 is a diagram showing the noise absorption ratio P loss / P in of Sample 81 (crossing angle θs of linear scratches = 60° and area ratio of copper foil piece = 20%) of the electromagnetic wave absorbing composite sheet. Fig. 49 is a diagram showing the noise absorption ratio P loss / P inof Sample 82 (crossing angle θs of linear scratches = 60° and area ratio of copper foil piece = 30%) of the electromagnetic wave absorbing composite sheet. Fig. 50 is a diagram showing the noise absorption ratio P loss / P in of Sample 83 (crossing angle θs of linear scratches = 60° and area ratio of copper foil piece = 40%) of the electromagnetic wave absorbing composite sheet. Fig. 51 is a diagram showing the noise absorption ratio P loss / P in of Sample 84 (crossing angle θs of linear scratches = 60° and area ratio of copper foil piece = 50%) of the electromagnetic wave absorbing composite sheet. Fig. 52 is a diagram showing the noise absorption ratio P loss / P inof Sample 85 (crossing angle θs of linear scratches = 60° and area ratio of copper foil piece = 60%) of the electromagnetic wave absorbing composite sheet. Fig. 53 is a diagram showing the noise absorption ratio P loss / P in of Sample 86 (crossing angle θs of linear scratches = 60° and area ratio of copper foil piece = 70%) of the electromagnetic wave absorbing composite sheet. Fig. 54 is a diagram showing the noise absorption ratio P loss / P in of Sample 87 (crossing angle θs of linear scratches = 60° and area ratio of copper foil piece = 80%) of the electromagnetic wave absorbing composite sheet. Fig. 55 is a diagram showing the noise absorption ratio P loss / P inof Sample 88 (crossing angle θs of linear scratches = 60° and area ratio of copper foil piece = 100%) of the electromagnetic wave absorbing composite sheet. Fig. 56 is a diagram showing the noise absorption ratio P loss / P in of Sample 91 (crossing angle θs of linear scratches = 60° and distance D from copper foil piece = 0 mm) of the electromagnetic wave absorbing composite sheet. Fig. 57 is a diagram showing the noise absorption ratio P loss / P in of Sample 92 (crossing angle θs of linear scratches = 60° and distance D from copper foil piece = 5 mm) of the electromagnetic wave absorbing composite sheet. Fig. 58 is a diagram showing the noise absorption ratio P loss / P inof Sample 93 (crossing angle θs of linear scratches = 60° and distance D from copper foil piece = 10 mm) of the electromagnetic wave absorbing composite sheet. Fig. 59 is a diagram showing the noise absorption ratio P loss / P in of Sample 94 (crossing angle θs of linear scratches = 60° and distance D from copper foil piece = 15 mm) of the electromagnetic wave absorbing composite sheet. Fig. 60 is a diagram showing the noise absorption ratio P loss / P in of Sample 95 (crossing angle θs of linear scratches = 60° and distance D from copper foil piece = 20 mm) of the electromagnetic wave absorbing composite sheet. Fig. 61 is a diagram showing the noise absorption ratio P loss / P inof Sample 96 (crossing angle θs of linear scratches = 60° and distance D from copper foil piece = 25 mm) of the electromagnetic wave absorbing composite sheet. Fig. 62 is a diagram showing the noise absorption ratio P loss / P in of Sample 101 (crossing angle θs of linear scratches = 45° and area ratio of copper foil piece = 20%) of the electromagnetic wave absorbing composite sheet. Fig. 63 is a diagram showing the noise absorption ratio P loss / P in of Sample 102 (crossing angle θs of linear scratches = 45° and area ratio of copper foil piece = 30%) of the electromagnetic wave absorbing composite sheet. Fig. 64 is a diagram showing the noise absorption ratio P loss / P inof Sample 103 (crossing angle θs of linear scratches = 45° and area ratio of copper foil piece = 40%) of the electromagnetic wave absorbing composite sheet. Fig. 65 is a diagram showing the noise absorption ratio P loss / P in of Sample 104 (crossing angle θs of linear scratches = 45° and area ratio of copper foil piece = 50%) of the electromagnetic wave absorbing composite sheet. Fig. 66 is a diagram showing the noise absorption ratio P loss / P in of Sample 105 (crossing angle θs of linear scratches = 45° and area ratio of copper foil piece = 60%) of the electromagnetic wave absorbing composite sheet. Fig. 67 is a diagram showing the noise absorption ratio P loss / P inof Sample 106 (crossing angle θs of linear scratches = 45° and area ratio of copper foil piece = 70%) of the electromagnetic wave absorbing composite sheet. Fig. 68 is a diagram showing the noise absorption ratio P loss / P in of Sample 107 (crossing angle θs of linear scratches = 45° and area ratio of copper foil piece = 80%) of the electromagnetic wave absorbing composite sheet. Fig. 69 is a diagram showing the noise absorption ratio P loss / P in of Sample 108 (crossing angle θs of linear scratches = 45° and area ratio of copper foil piece = 100%) of the electromagnetic wave absorbing composite sheet. Fig. 70 is a diagram showing the noise absorption ratio P loss / P inof Sample 111 (crossing angle θs of linear scratches = 45° and distance D from copper foil piece = 0 mm) of the electromagnetic wave absorbing composite sheet. Fig. 71 is a diagram showing the noise absorption ratio P loss / P in of Sample 112 (crossing angle θs of linear scratches = 45° and distance D from copper foil piece = 5 mm) of the electromagnetic wave absorbing composite sheet. Fig. 72 is a diagram showing the noise absorption ratio P loss / P in of Sample 113 (crossing angle θs of linear scratches = 45° and distance D from copper foil piece = 10 mm) of the electromagnetic wave absorbing composite sheet. Fig. 73 is a diagram showing the noise absorption ratio P loss / P inof Sample 114 (crossing angle θs of linear scratches = 45° and distance D from copper foil piece = 15 mm) of the electromagnetic wave absorbing composite sheet. Fig. 74 is a diagram showing the noise absorption ratio P loss / P in of Sample 115 (crossing angle θs of linear scratches = 45° and distance D from copper foil piece = 20 mm) of the electromagnetic wave absorbing composite sheet. Fig. 75 is a diagram showing the noise absorption ratio P loss / P in of Sample 116 (crossing angle θs of linear scratches = 45° and distance D from copper foil piece = 25 mm) of the electromagnetic wave absorbing composite sheet. Fig. 76 is a diagram showing the noise absorption ratio P loss / P inof Sample 121 (crossing angle θs of linear scratches = 30° and area ratio of copper foil piece = 20%) of the electromagnetic wave absorbing composite sheet. Fig. 77 is a diagram showing the noise absorption ratio P loss / P in of Sample 122 (crossing angle θs of linear scratches = 30° and area ratio of copper foil piece = 30%) of the electromagnetic wave absorbing composite sheet. Fig. 78 is a diagram showing the noise absorption ratio P loss / P in of Sample 123 (crossing angle θs of linear scratches = 30° and area ratio of copper foil piece = 40%) of the electromagnetic wave absorbing composite sheet. Fig. 79 is a diagram showing the noise absorption ratio P loss / P inof Sample 124 (crossing angle θs of linear scratches = 30° and area ratio of copper foil piece = 50%) of the electromagnetic wave absorbing composite sheet. Fig. Figure 80 is a diagram showing the noise absorption ratio P loss / P in of Sample 125 (crossing angle θs of linear scratches = 30° and area ratio of copper foil piece = 60%) of the electromagnetic wave absorbing composite sheet. Fig. 81 is a diagram showing the noise absorption ratio P loss / P in of Sample 126 (crossing angle θs of linear scratches = 30° and area ratio of copper foil piece = 70%) of the electromagnetic wave absorbing composite sheet. Fig. 82 is a diagram showing the noise absorption ratio P loss / P inof Sample 127 (crossing angle θs of linear scratches = 30° and area ratio of copper foil piece = 80%) of the electromagnetic wave absorbing composite sheet. Fig. 83 is a diagram showing the noise absorption ratio P loss / P in of Sample 128 (crossing angle θs of linear scratches = 30° and area ratio of copper foil piece = 100%) of the electromagnetic wave absorbing composite sheet. Fig. 84 is a diagram showing the noise absorption ratio P loss / P in of Sample 131 (crossing angle θs of linear scratches = 30° and distance D from copper foil piece = 0 mm) of the electromagnetic wave absorbing composite sheet. Fig. 85 is a diagram showing the noise absorption ratio P loss / P inof Sample 132 (crossing angle θs of linear scratches = 30° and distance D from copper foil piece = 5 mm) of the electromagnetic wave absorbing composite sheet. Fig. 86 is a diagram showing the noise absorption ratio P loss / P in of Sample 133 (crossing angle θs of linear scratches = 30° and distance D from copper foil piece = 10 mm) of the electromagnetic wave absorbing composite sheet. Fig. 87 is a diagram showing the noise absorption ratio P loss / P in of Sample 134 (crossing angle θs of linear scratches = 30° and distance D from copper foil piece = 15 mm) of the electromagnetic wave absorbing composite sheet. Fig. 88 is a diagram showing the noise absorption ratio P loss / P inof Sample 135 (crossing angle θs of linear scratches = 30° and distance D from copper foil piece = 20 mm) of the electromagnetic wave absorbing composite sheet. Fig. 89 is a diagram showing the noise absorption ratio P loss / P in of Sample 136 (crossing angle θs of linear scratches = 30° and distance D from copper foil piece = 25 mm) of the electromagnetic wave absorbing composite sheet. DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The embodiments of the present invention will be explained in detail with reference to the attached drawings. It should be noted that explanations of one embodiment are applicable to other embodiments unless otherwise noted. Furthermore, the following explanations are not limiting, and various modifications can be made within the scope of the present invention.

[0015] Fig. 1(a) shows an electromagnetic wave absorbing film 1 and an electromagnetic wave shielding film 2 laminated on the electromagnetic wave absorbing film 1, which constitute the electromagnetic wave absorbing composite sheet 10 of the present invention, and Fig. 1(b) shows an example of the electromagnetic wave absorbing composite sheets 10 of the present invention, which includes the electromagnetic wave absorbing film 1 and the electromagnetic wave shielding film 2. [1] Electromagnetic wave absorbing film

[0016] As in Fig. 2(a) and Fig. 2(b), the electromagnetic wave absorbing film 1 comprises a plastic film 11 and a single- or multi-layered thin metal film 12 on at least one surface of the plastic film 11, wherein the thin metal film 12 is provided with a large number (plurality) of substantially parallel, intermittent, linear scratches 13 having irregular widths and intervals in a plurality of directions. (1) Plastic film

[0017] Resins constituting the plastic film 11 are not particularly limiting as long as they have sufficient strength, flexibility, and processability in addition to insulation. They can be, for example, polyesters (polyethylene terephthalate, etc.), polyarylene sulfide (polyphenylene sulfide, etc.), polyamides, polyimides, polyamideimides, polyethersulfone, polyetheretherketone, polycarbonates, acrylic resins, polystyrenes, polyolefins (polyethylene, polypropylene, etc.), etc. In view of strength and cost, polyethylene terephthalate (PET) is preferred. The thickness of the plastic film 11 can be about 8-30 μm. (2) Thin metal film

[0018] Metals constituting the thin metal film 12 are not particularly limiting as long as they have conductivity, and they are preferably aluminum, copper, silver, tin, nickel, cobalt, chromium, and their alloys, especially aluminum, copper, nickel, and their alloys in view of corrosion resistance and cost. The thickness of the thin metal film 12 is preferably 0.01 μm or more. Although not limiting, the upper limit of the thickness of the thin metal film 12 may practically be about 10 μm. Of course, the thin metal film 12 may be thicker than 10 μm substantially without changing the absorbability of high-frequency electromagnetic waves. Accordingly, the thickness of the thin metal film 12 is preferably 0.01-10 μm, more preferably 0.01-5 μm, most preferably 0.01-1 μm. The thin metal film 12 can be deposited by vapor deposition methods (physical vapor deposition methods such asVacuum vapor deposition processes, a sputtering process and an ion plating process, or chemical vapor deposition (CVD) processes such as a plasma CVD process, a thermal CVD process and a photo CVD process), plating processes or foil bonding processes.

[0019] When the thin metal film 12 has a single-layer structure, the thin metal film 12 is preferably made of aluminum or nickel in consideration of conductivity, corrosion resistance, and cost. When the thin metal film 12 has a multi-layer structure, one layer may be made of a non-magnetic metal, while the other layer may be made of a magnetic metal. The non-magnetic metals include aluminum, copper, silver, tin, and their alloys, and the magnetic metals include nickel, cobalt, chromium, and their alloys. The magnetic thin metal film is preferably as thick as 0.01 μm or more, and the non-magnetic thin metal film is preferably as thick as 0.1 μm or more. Although not limiting, the upper limits of their thicknesses may practically be about 10 μm. More preferably, the thickness of the magnetic thin metal film is 0.01-5 μm, and the thickness of the non-magnetic thin metal film is 0.1-5 μm. Fig. 2(e) and Fig. 2(f) shows two layers (thin metal films 12a, 12b) formed on a plastic film 11. (3) Linear scratches

[0020] In the example shown in Fig. 2(b) and Fig. 2(c), a thin metal film 12 is provided with a large number of substantially parallel, intermittent linear scratches 13 (13a, 13b) with irregular widths and intervals in two directions. The depth of the linear scratches 13 is Fig. 2 (c) exaggerated for explanatory purposes. As in Fig. As shown in Figure 2(d), the linear scratches 13 have different widths W and intervals I. The widths W and intervals I of linear scratches 13 are determined at a height corresponding to a surface S of the thin metal film 12 before linear scratches are formed. Since the linear scratches 13 have different widths W and intervals I, the electromagnetic wave absorbing film 1 can efficiently absorb electromagnetic noise in a wide frequency range.

[0021] 90% or more of the widths W of the linear scratches 13 are in a range of preferably 0.1-100 µm, more preferably 0.5-50 µm, most preferably 0.5-20 µm. The average width Wav of the linear scratches 13 is preferably 1-50 µm, more preferably 1-10 µm, most preferably 1-5 µm.

[0022] The lateral intervals I of the linear scratches 13 are in a range of preferably 1-500 µm, more preferably 1-100 µm, most preferably 1-50 µm, especially 1-30 µm. The average lateral interval Iav of the linear scratches 13 is preferably 1-200 µm, more preferably 5-50 µm, most preferably 5-30 µm.

[0023] Since the lengths Ls of the linear scratches 13 are determined by sliding conditions (mainly relative peripheral speeds of the pattern roll and the composite film, and the sliding direction of the composite film with respect to the pattern roll), most linear scratches 13 have substantially the same lengths Ls (substantially equal to the average length Lsav) unless the sliding conditions are changed. The lengths Ls of the linear scratches 13 can practically be about 1-100 mm, preferably 2-10 mm, although not particularly limiting.

[0024] The acute crossing angle θs, which may simply be called "crossing angle θs" unless otherwise noted, of the linear scratches 13a, 13b is preferably 30-90°, more preferably 45-90°. By adjusting the sliding conditions of the composite film to the pattern rolls (relative peripheral speeds, sliding directions, etc.), the linear scratches 13 with various crossing angles θs can be obtained. (4) Manufacturing process

[0025] Fig. 3(a)-3(e) show an example of apparatuses for forming linear scratches 113 (113a, 113b) in two directions. This apparatus includes (a) a roll 221 from which a composite film 100 having a thin metal film 112 formed on a plastic film is unwound; (b) a first pattern roller 202a arranged in a direction different from the lateral direction of the composite film 100 on the thin metal film 112 side; (c) a first push roller 203a arranged upstream of the first pattern roller 202a on the side opposite to the thin metal film 112; (d) a second pattern roller 202b arranged in a direction opposite to the first pattern roller 202a with respect to the lateral direction of the composite film 100 on the thin metal film 112 side. (e) a second push roller 203b arranged downstream of the second pattern roller 202b on the side opposite the thin metal film 112;(f) an electrical resistance measuring means 204a disposed on the thin metal film 112 side between the first and second pattern rollers 202a, 202b; (g) a second electrical resistance measuring means 204b disposed downstream of the second pattern roller 202b on the thin metal film 112 side; and (h) a roller 224 around which a linearly scratched composite film (electromagnetic wave absorbing film) 111 is wound, in this order from upstream. In addition, a plurality of guide rollers 222, 223 are disposed at predetermined positions. Each pattern roller 202a, 202b is rotatably supported by a backup roller (e.g., rubber roller) 205a, 205b.

[0026] Since the position of each push roller 203a, 203b is lower than a position where the composite film 100 is in sliding contact with each pattern roller 202a, 202b as shown in Fig. 3(c), the thin metal film 112 of the composite film 100 is pushed toward each pattern roller 202a, 202b. When this condition is satisfied, the vertical position of each push roller 203a, 203b can be adjusted to control the pressing force of each pattern roller 202a, 202b on the thin metal film 112 and a sliding distance proportional to a center angle θ1.

[0027] Fig. 3(d) shows the principle that linear scratches 113a are formed on the composite film 100 with inclination in the moving direction thereof. Since the pattern roller 202a is inclined to the moving direction of the composite film 100, the moving direction (rotation direction) a of fine, hard particles on the pattern roller 202a differs from the moving direction b of the composite film 100. After a fine, hard particle comes into contact with the thin metal film 112 at a point A on the pattern roller 202a to form a scratch B, as shown by X, the fine, hard particle moves to a point A', and the scratch B moves to a point B'. As the fine, hard particle moves from the point A to the point A', a scratch is continuously formed, resulting in a linear scratch 113a extending from the point B' to the point A'.

[0028] The directions and the crossing angle θs of the first and second linear scratches formed by the first and second pattern rollers 202a, 202b can be adjusted by changing the angle of each pattern roller 202a, 202b to the composite film 100 and / or the peripheral speed of each pattern roller 202a, 202b relative to the moving speed of the composite film 100. For example, the linear scratches 113a can be arranged at 45° in the moving direction of the composite film 100, such as a line C'D' shown by Y in Fig. 3(d), can be tilted as the peripheral speed a of the pattern roller 202a increases relative to the moving speed b of the composite film 100. Similarly, the peripheral speed a of the pattern roller 202a can be changed by changing the inclination angle θ2 of the pattern roller 202a in the lateral direction of the composite film 100. This applies to the pattern roller 202b. Accordingly, the directions of the linear scratches 113a, 113b can be changed when both pattern rollers 202a, 202b are adjusted.

[0029] Since each pattern roller 202a, 202b is inclined relative to the composite film 100, sliding contact with each pattern roller 202a, 202b is likely to exert a force in a lateral direction on the composite film 100. Accordingly, it is preferable to adjust the vertical position and / or angle of each push roller 203a, 203b to each pattern roller 202a, 202b to prevent lateral displacement of the composite film 100. For example, properly adjusting an intersection angle θ3 between the axis of the pattern roller 202a and the axis of the push roller 203a can provide a pressing force with such a lateral distribution that lateral components are eliminated, thereby preventing lateral displacement. Adjusting the distance between the pattern roller 202a and the push roller 203a also contributes to preventing lateral displacement.To prevent the lateral displacement and breakage of the composite film 100, the rotation directions of the first and second pattern rollers 202a, 202b, which are inclined from the lateral direction of the composite film 100, are the same as the moving direction of the composite film 100.

[0030] As in Fig. As shown in Fig. 3(b), each electrical resistance measuring means (roller) 204a, 204b includes a pair of electrodes (not shown) via an insulating portion, between which the electrical resistance of the linearly scratched thin metal film 112 is measured. The electrical resistance measured by the electrical resistance measuring means 204a, 204b is compared with a target electrical resistance to adjust the operating conditions, such as the moving speed of the composite film 100, the rotational speeds and inclination angles θ2 of the pattern rollers 202a, 202b, the positions and inclination angles θ3 of the shift rollers 203a, 203b, etc., depending on their difference.

[0031] To increase the pressing forces of the pattern rollers 202a, 202b on the composite film 100, a third push roller 203c can be arranged between the pattern rollers 202a, 202b, as shown in Fig. 4. The third sliding roller 203c increases the sliding distance of the thin metal film 12 in proportion to a center angle θ1, resulting in longer linear scratches 113a, 113b. Adjusting the position and inclination angle of the third sliding roller 203c can contribute to preventing lateral displacement of the composite film 100.

[0032] Fig. Figure 5 shows an example of devices for forming linear scratches oriented in two perpendicular directions. This device differs from the one shown in Fig. 3(a)-3(e) in that a second pattern roller 232b is parallel to the lateral direction of the composite film 100. Accordingly, only portions that differ from the Fig. 3(a)-3(e). The rotational direction of the second pattern roller 232b may be the same as or opposite to the moving direction of the composite film 100. The second push roller 233b may also be upstream or downstream of the second pattern roller 232b. This device brings the direction (line E'F') of linear scratches 113a' into alignment with the lateral direction of the composite film 100, as indicated by Z in Fig. 3(d), forming linear scratches crossing at 90°.

[0033] Operating conditions that determine not only the inclination angles and intersection angles of linear scratches, but also their depths, widths, lengths, and pitches are the moving speed of the composite film 100, the rotational speeds and inclination angles, and the pressing forces of the pattern rollers, etc. The moving speed of the composite film 100 is preferably 5-200 m / minute, and the peripheral speed of the pattern roller is preferably 10-2000 m / minute. The inclination angles θ2 of the pattern rollers are preferably 20°-60°, especially about 45°. The tension (parallel to the pressing force) of the composite film 100 is preferably 0.05-5 kgf / cm width.

[0034] The pattern rollers used in the linear scratch forming apparatus are preferably rollers having fine particles with sharp edges and Mohs hardness of 5 or more on the surface, for example, the diamond rollers described in JP 2002-59487 A. Since the widths of linear scratches are determined by the size of the fine particles, 90% or more of the fine diamond particles preferably have sizes in a range of 1-1000 µm, more preferably in a range of 10-200 µm. The fine diamond particles are preferably attached to the roller surface at an area ratio of 50% or more. [2] Electromagnetic wave shielding film

[0035] To reflect electromagnetic wave noise transmitted through the electromagnetic wave absorbing film 1 and project it back onto the electromagnetic wave absorbing film 1, the electromagnetic wave shielding film 2 should have a function of reflecting electromagnetic wave noise. To effectively exhibit such a function, the electromagnetic wave shielding film 2 is preferably a conductive metal foil, a plastic film with a thin conductive metal film or coating, or a carbon sheet. The electromagnetic wave absorbing film 1 and the electromagnetic wave shielding film 2 are preferably laminated via a non-conductive adhesive, which may be a known one. (1) Conductive metal foil

[0036] The conductive metal is preferably at least one selected from the group consisting of aluminum, copper, silver, tin, nickel, cobalt, chromium, and their alloys. The conductive metal foil is preferably as thick as 5-50 µm. (2) Thin conductive metal film or thin conductive metal coating

[0037] The thin conductive metal film is preferably a vapor-deposited film of the above conductive metal. The vapor-deposited metal film can be as thick as several tens of nanometers to several tens of micrometers. The plastic film on which a vapor-deposited film of the above conductive metal is formed can be the same as the plastic film 11 in the electromagnetic wave absorbing film 1. (3) Conductive metal coating

[0038] The conductive metal coating can be formed by coating a plastic film with an ink (paste) comprising conductive metal powder such as silver powder, etc., finely dispersed in a thermoplastic resin or a photocuring resin, drying the resulting coating, and then optionally irradiating the coating with ultraviolet rays. The conductive ink (paste) can be a known one, for example, a photocuring conductive ink composition (JP 2016-14111 A) comprising a conductive filler, a photoinitiator, and a polymer dispersant, wherein the percentage of the conductive filler is 70-90 mass%; and wherein the conductive filler is silver powder having a particle size D 50of 0.3-3.0 µm, 50 mass% or more, which is in a scale, film, or flake form. The plastic film on which the conductive metal is coated may be the same as the plastic film 11 in the electromagnetic wave absorbing film 1. (4) Carbon sheet

[0039] The carbon sheet used as the electromagnetic wave shielding film may be commercially available PGS (registered trademark) graphite sheet (available from Panasonic Corporation) formed by heat-treating a polyimide film at an ultra-high temperature in an inert gas, a carbon sheet (heat dissipation sheet) comprising graphite powder and carbon black, etc.

[0040] A heat dissipation sheet (JP 2015-170660 A) with a structure in which carbon black is uniformly dispersed among fine graphite particles, with a mass ratio of fine graphite particles to carbon black of 75 / 25-95 / 5, and a density of 1.9 g / cm 3 or more and an in-plane thermal conductivity of 570 W / mK or more. The fine graphite particles preferably have an average diameter of 5-100 µm and an average thickness of 200 nm or more. This heat dissipation sheet is preferably as thick as 25-250 µm.

[0041] This heat dissipation sheet can be formed by a method comprising: (1) preparing a dispersion containing a total of 5-25 mass % of fine graphite particles and carbon black and 0.05-2.5 mass % of a bonding resin in an organic solvent, wherein a mass ratio of the fine graphite particles to carbon black is 75 / 25-95 / 5; (2) repeating a step of applying the dispersion on a surface of a support plate and a drying step several times to form a resinous composite sheet comprising the fine graphite particles, the carbon black, and the bonding resin; (3) firing the resinous composite sheet to remove the bonding resin; and (4) pressing the resulting fine graphite particles / carbon black composite sheet for densification. [3] Arrangement of electromagnetic wave absorbing film and electromagnetic wave shielding film(1) Area ratio

[0042] As in Fig. As shown in Figure 1(b), an area ratio of the electromagnetic wave shielding film 2 to the electromagnetic wave absorbing film 1 is 10-80%. If the area ratio is less than 10% or more than 80%, the absorption capacity of electromagnetic wave noise in a desired frequency range is not sufficiently maximized. This is an unexpected result, and it is an important feature of the present invention that the area ratio of the electromagnetic wave shielding film 2 to the electromagnetic wave absorbing film 1 is 10-80%. The lower limit of the area ratio is preferably 20%, more preferably 30%, further preferably 40%, most preferably 45%. The upper limit of the area ratio is preferably 70%, more preferably 65%, most preferably 60%.The area ratio range of the electromagnetic wave shielding film 2 to the electromagnetic wave absorbing film 1 is, for example, preferably 20-80%, more preferably 30-70%, further preferably 40-65%, most preferably 45-60%. (2) Position

[0043] A center of the electromagnetic wave absorbing film 2 is preferably positioned at a center of the electromagnetic wave absorbing film 1, but it may deviate to change a frequency at which the electromagnetic wave absorbing ability has a peak. The position change of the electromagnetic wave shielding film 2 can be achieved by shifting the electromagnetic wave shielding film 2 in a direction relative to the electromagnetic wave absorbing film 1, as shown in Fig. 6(a), or by reducing the size of the electromagnetic wave shielding film 2 such that four sides of the electromagnetic wave shielding film 2 are separated from four sides of the electromagnetic wave absorbing film 1, as shown in Fig. 6(b). In both cases, it is preferably determined depending on a frequency range in which the electromagnetic wave absorption capacity is to be maximized, since the way in which the electromagnetic wave shielding film 2 is shifted or dimensioned relative to the electromagnetic wave absorbing film 1 affects a frequency at which the electromagnetic wave absorption capacity has a peak. In one of Fig. 6(a) and Fig. 6(b), the area ratio of the electromagnetic wave shielding film 2 to the electromagnetic wave absorbing film 2 should naturally meet the above requirement.

[0044] The present invention will be explained in more detail with reference to examples below without intending to limit the present invention thereto. Reference example 1

[0045] Using a device with the Fig. In the structure shown in Figure 5, comprising pattern rollers 232a, 232b electroplated with fine diamond particles having a particle size distribution of 50-80 µm, linear scratches oriented in two directions with a crossing angle θs of 90° were formed in a thin aluminum film with a thickness of 0.05 µm, which was formed on a surface of a biaxially oriented polyethylene terephthalate (PET) film as thick as 16 µm by a vacuum vapor deposition method. An optical micrograph of the linearly scratched thin aluminum film revealed that the linear scratches had the following characteristics: Range of widths W: 0.5-5 µm, Average width Wav: 2 µm, Range of intervals: 2-30 µm, Average interval Iav: 20 µm, Average length Lsav: 5 mm and Crossing angle θs: 90°. Reference example 2

[0046] Using a device with the Fig. In the structure shown in Figure 3, comprising pattern rollers 202a, 202b electroplated with fine diamond particles having a particle size distribution of 50-80 µm, linear scratches oriented in two directions with a crossing angle θs of 60° were formed in a thin aluminum film with a thickness of 0.05 µm, which was formed on a surface of a PET film as thick as 16 µm by a vacuum vapor deposition method. An optical micrograph of the linearly scratched thin aluminum film revealed that the linear scratches had the following characteristics: Range of widths W: 0.5-5 µm, Average width Wav: 2 µm, Range of intervals I: 2-30 µm, Average interval Iav: 20 µm, Average length Lsav: 5 mm and Crossing angle θs: 60°. Reference example 3

[0047] A thin aluminum film as thick as 0.05 μm formed on a surface of a PET film as thick as 16 μm by a vacuum vapor deposition method was provided with linear scratches oriented in two directions with a crossing angle θs of 45° by the same method as in Reference Example 2 except for changing the crossing angle θs to 45°, to prepare an electromagnetic wave absorbing film. Reference Example 4

[0048] A thin aluminum film as thick as 0.05 μm formed on a surface of a PET film as thick as 16 μm by a vacuum vapor deposition method was provided with linear scratches oriented in two directions with a crossing angle θs of 30° by the same method as in Reference Example 2 except for changing the crossing angle θs to 30°, to prepare an electromagnetic wave absorbing film. Example 1

[0049] Electromagnetic wave absorbing film pieces of 50 mm × 50 mm were cut from the electromagnetic wave absorbing film (crossing angle θs of linear scratches: 90°) obtained in Reference Example 1, and an aluminum foil piece (thickness: 15 μm) with a size L (0 mm, 10 mm, 20 mm, 25 mm, 30 mm, 40 mm and 50 mm) × 50 mm was glued via a non-conductive adhesive onto each electromagnetic wave absorbing film piece as shown in Fig. 8, laminated to prepare samples 1-7. In each sample, a center of the aluminum foil piece was aligned with a center of the electromagnetic wave absorbing film piece.

[0050] Using a system comprising a microstrip line MSL (64.4 mm × 4.4 mm) of 50 Ω, an insulating substrate 300 supporting the microstrip line MSL, a grounded electrode 301 attached to a lower surface of the insulating substrate 300, conductor pins 302, 302 connected to both ends of the microstrip line MSL, a network analyzer NA, and coaxial cables 303, 303 connecting the network analyzer NA to the conductor pins 302, 302, as shown in Fig. 7(a) and Fig. 7(b), each sample was attached to an upper surface of the insulating substrate 300 by an adhesive such that a center of each sample was aligned with a center of the microstrip line MSL as shown in Fig. 8, was aligned to reflect wave power S 11 and transmitted shaft power S 12 with incident wave power in 0.1-6 GHz.

[0051] Power loss P loss was calculated by subtracting the reflected wave power S 11 and the transmitted shaft power S 12 of the incident power P in that was entered into the system that was Fig. 7(a) and Fig. 7(b) and a noise absorption ratio P loss / P in was created by dividing P loss by the incident power P in The results are in Fig. 9 to 15 and Table 1. Table 1 Probe Nr. θs (1) (°) Aluminiumfolienstück Maximale Rauschabsorption L (mm) Flächenverhältnis (2) (%) P loss / P in Frequenz (GHz) 1* 90 0 0 0,88 2 2 90 10 20 0,93 1,7 3 90 20 40 0,95 1,8 4 90 25 50 0,96 1,9 5 90 30 60 0,93 2,3 6 90 40 80 0,93 3,4 7* 90 50 100 0,90 3,7

[0052] Note: (1) θs represents the crossing angle of linear scratches.

[0053] (2) An area ratio of the aluminum foil piece to the electromagnetic wave absorbing film piece.

[0054] Samples with * are outside the scope of the present invention.

[0055] In Sample 1, which has no aluminum foil piece laminated on the electromagnetic wave absorbing film piece, the maximum noise absorption ratio P loss / P in 0.88 at a frequency of about 2 GHz. In Sample 7, which has an aluminum foil piece of the same size laminated on the electromagnetic wave absorbing film piece, the maximum noise absorption ratio P loss / P in 0.90 at a frequency of about 3.7 GHz. On the other hand, in Sample 4, which has an aluminum foil piece with a size corresponding to an area ratio of 50% laminated on the electromagnetic wave absorbing film piece, the maximum noise absorption ratio P loss / Pin as high as 0.96 at a frequency of about 1.9 GHz. In Sample 6, which had an aluminum foil piece with a size corresponding to an area ratio of 80% laminated on the electromagnetic wave absorbing film piece, the maximum noise absorption ratio P loss / P in as high as 0.93, but a frequency at which the maximum noise absorption ratio P loss / P in was shifted to 3.4 GHz. It is therefore obvious that the area ratio of the aluminum foil piece (electromagnetic wave shielding film) to the electromagnetic wave absorbing film piece should be 10-80% to achieve the noise absorption ratio P loss / P in in a desired frequency range. Example 2

[0056] An aluminum foil piece (thickness: 15 µm) of 25 mm x 50 mm was laminated via a non-conductive adhesive to each electromagnetic wave absorbing film piece (crossing angle θs of linear scratches: 90°) of 50 mm x 50 mm used in Example 1 in such a way that the distance D between a side X1 of the electromagnetic wave absorbing film piece and a side X2 (parallel to X1) of the aluminum foil piece was as shown in Fig. 6(a), was 0 mm, 5 mm, and 10 mm, respectively, to prepare samples 11-13. Each sample was applied to the microstrip line MSL on the insulating substrate 300 as shown in Fig. 7(a), placed to determine their noise absorption ratio P loss / P in in a range of 0.1-6 GHz. With respect to each sample, the distance D, the noise absorption ratio P loss / P in at 2 GHz, the maximum noise absorption ratio P loss / P inand a frequency at the maximum noise absorption ratio is shown in Table 2. Table 2 Probe Nr. θs (1) (°) D (2) (mm) P loss / P in bei 2 GHz Maximales P loss / P in (GHz) 11 90 0 0,50 0,98 (3,9) 12 90 5 0,60 1,0 (3,7) 13 90 10 0,89 0,98 (2,6)

[0057] Note: (1) θs represents the crossing angle of linear scratches.

[0058] (2) D represents the distance between one side X1 of the electromagnetic wave absorbing film piece and one side X2 of the aluminum foil piece.

[0059] As can be seen from Table 2, (a) the noise absorption ratio P loss / P in at 2 GHz, when a center of the aluminum foil piece was moved closer to a center of the electromagnetic wave absorbing film piece and (b) the noise absorption ratio P decreased loss / P in at 2 GHz, but the noise absorption ratio P loss / P inwas maximized at a frequency (near 4 GHz) different from 2 GHz when a center of the aluminum foil piece was shifted away from a center of the electromagnetic wave absorbing film piece. This indicates that in a noise frequency range of semiconductors, a center of the aluminum foil is preferably as close to a center of the electromagnetic wave absorbing film as possible, and that in other frequency ranges, a center of the aluminum foil piece can be shifted away from a center of the electromagnetic wave absorbing film piece to increase the noise absorption ratio P loss / P in to maximize. Example 3

[0060] As in Fig. As shown in Figure 16, a square aluminum foil piece with an area ratio of 50% and a square-frame-shaped aluminum foil piece with an area ratio of 50% were laminated on each of the same 50 mm x 50 mm electromagnetic wave absorbing film pieces as in Example 1 such that their centers were aligned with each other to prepare Samples 21 and 22. The noise absorption ratio P loss / P in of each sample was measured. The measurement results are shown in Fig. 17 together with those of samples 1 and 4.

[0061] As from Fig. As can be seen in Figure 17, Sample 21, which is laminated with a square piece of aluminum foil with an area ratio of 50%, exhibited the maximum noise absorption ratio P loss / P inat the same level as that of Sample 4, which is laminated with a 25 mm x 50 mm aluminum foil piece, at a different frequency from that of Sample 4. On the other hand, Sample 22, which is laminated with an aluminum foil piece of a different shape with the same area ratio, exhibited a much lower noise absorption ratio P loss / P in than that of Sample 21 in a wide frequency range. This indicates that (a) a frequency at which the maximum noise absorption ratio P loss / P incan be changed by changing the shape of an aluminum foil piece (electromagnetic wave shielding film) despite the same area ratio; and that (b) among aluminum foil pieces having the same area ratio, an aluminum foil piece having a shape such that it occupies a central portion of the electromagnetic wave absorbing film piece has a higher noise absorption ratio P loss / P in has. Example 4

[0062] An electromagnetic wave-absorbing composite sheet large enough to cover an IC chip in Amazon's Fire Stick TV, which had the same structure as Example 1, was produced. An electromagnetic wave-absorbing film piece was square-shaped with the same size as the IC chip, and an aluminum foil piece was rectangular-shaped with an area ratio of 50% to the electromagnetic wave-absorbing film piece. A pair of opposite sides of the aluminum foil piece were aligned with a pair of opposite sides of the electromagnetic wave-absorbing film piece, and the distance between the other pair of opposite sides perpendicular to a pair of opposite sides of the aluminum foil piece was 50% of the distance between the other pair of opposite sides of the electromagnetic wave-absorbing film piece.A center of the laminated aluminum foil piece was aligned with a center of the electromagnetic wave absorbing film piece. Namely, the electromagnetic wave absorbing composite sheet of Example 4 had the structure shown in . Fig. 1(b) shown.

[0063] With the cover removed from the Fire Stick TV, the electromagnetic wave absorbing composite sheet of Example 4 was placed on the IC chip in the Fire Stick TV to measure the leakage of electromagnetic wave noise from the Fire Stick TV using a spectrum analyzer VSA6G2A available from Keisoku Giken Co., Ltd. The results are shown in Fig. 18(a). EMI leakage from the Fire Stick TV was also measured with the cover removed but the electromagnetic wave absorbing composite sheet not placed on the IC chip. The results are shown in Fig. 18(b). As can be seen from Fig. 18(a) and Fig. As can be seen from Fig. 18(b), when the electromagnetic wave absorbing composite sheet of the present invention was placed on the IC chip, leakage of electromagnetic wave noise at a frequency of about 3 GHz from the Firestick TV was significantly reduced. Example 5

[0064] Each electromagnetic wave-absorbing composite sheet was manufactured in the same manner as in Example 1, except that each graphite powder / carbon black carbon sheet piece measuring 20 mm x 50 mm (Sample 31), 25 mm x 50 mm (Sample 32), and 50 mm x 50 mm (Sample 33) was laminated to the 50 mm x 50 mm electromagnetic wave-absorbing film piece instead of the aluminum foil piece, with their centers aligned. The graphite powder / carbon black carbon sheet was manufactured by the same method as in Example 1 of JP 2015-170660 A. The noise absorption ratio P loss / P ineach sample was measured in the same way as in Example 1. The results are shown in Fig. 19 shown.

[0065] As from Fig. As can be seen from Figure 19, the same results as in Example 1 were obtained even when the carbon sheet piece was used instead of the aluminum foil piece.

[0066] Although any electromagnetic wave absorbing composite sheet in which an electromagnetic wave absorbing film provided with linear scratches having a crossing angle of 90° in a thin aluminum film is laminated with an aluminum foil or a carbon sheet made of graphite powder / carbon black as an electromagnetic wave shielding film is used in the above examples, the present invention is not limited to these electromagnetic wave absorbing composite sheets, but can be changed within the scope of the invention. For example, the thin metal film is not limited to the thin aluminum film, but may be a thin copper film, etc.; the crossing angle of linear scratches is not limited to 90°, but can be changed within a range of 30-90°; and a copper foil, aluminum, a coating of a conductive ink in which powders of copper, silver, etc. are incorporated.dispersed, can be used instead of aluminum foil as the electromagnetic wave shielding film. Example 6

[0067] An aluminum foil piece (thickness: 15 µm) with a size of L (10 mm, 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, 40 mm and 50 mm) × 50 mm was laminated via a non-conductive adhesive onto an electromagnetic wave absorbing film piece of 50 mm × 50 mm cut from the electromagnetic wave absorbing film (crossing angle θs of linear scratches: 60°) obtained in Reference Example 2 as in Fig. 8 to prepare samples 41-48. In each sample, a center of the aluminum foil piece was aligned with a center of the electromagnetic wave absorbing film piece. The noise absorption ratio P loss / P in of each sample 41-48 was determined by the same method as in Example 1. The results are shown in Fig. 20-27 and Table 3. Table 3 Probe Nr. θs (1) (°) Aluminiumfolienstück Maximale Rauschabsorption L (mm) Area ratio (2) (%) P loss / P in Frequenz (GHz) 41 60 10 20 0,96 1,9 42 60 15 30 0,96 1,95 43 60 20 40 0,96 2,2 44 60 25 50 0,93 2,2 45 60 30 60 0,94 4,1 46 60 35 70 0,99 4,05 47 60 40 80 0,97 4,1 48* 60 50 100 - (3) - (3)

[0068] Note: (1) θs represents the crossing angle of linear scratches.

[0069] (2) An area ratio of the aluminum foil piece to the electromagnetic wave absorbing film piece.

[0070] (3) P loss / P in was low across the entire frequency range.

[0071] A sample with * is outside the scope of the present invention.

[0072] In Sample 48, in which the electromagnetic wave absorbing film piece and the aluminum foil piece laminated together had the same size, the noise absorption ratio P loss / P in low across the entire frequency range. On the other hand, the maximum noise absorption ratios P loss / P inIn samples 41-47, in which the aluminum foil pieces with area ratios of 20-80% were laminated with the electromagnetic wave absorbing film pieces, the values were as high as 0.93-0.99 at frequencies ranging from 1.9-4.1 GHz. This indicates that to maximize the noise absorption ratio P loss / P in in a desired frequency range, the area ratio of the aluminum foil piece (electromagnetic wave shielding film) to the electromagnetic wave absorbing film piece should be 10-80%. Example 7

[0073] An aluminum foil piece (thickness: 15 µm) of 25 mm × 50 mm was laminated via a non-conductive adhesive to the same electromagnetic wave absorbing film piece of 50 mm × 50 mm (crossing angle θs of linear scratches: 60°) as used in Example 6, such that the distance D between a side X1 of the electromagnetic wave absorbing film piece and a side X2 (parallel to X1) of the aluminum foil piece was 0 mm, 5 mm, 10 mm, 15 mm, 20 mm, and 25 mm, respectively, as shown in Fig. 6(a) to prepare samples 51-56. The noise absorption ratio P loss / P in of each sample in a range of 0.1-6 GHz was measured in the same manner as in Example 2. The relationship between the noise absorption ratio P loss / P in and the distance D in each sample is in Fig. 28-33. As shown in Fig. 28-33, a curve of the noise absorption ratio P loss / P indrastically as the distance D changed. Example 8

[0074] An aluminum foil piece (thickness: 15 µm) of L (10 mm, 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, 40 mm and 50 mm) × 50 mm was laminated via a non-conductive adhesive onto an electromagnetic wave absorbing film piece of 50 mm × 50 mm, which was cut from the electromagnetic wave absorbing film (crossing angle θs of linear scratches: 30 °) obtained in Reference Example 4 as in Fig. 8 to prepare samples 61-68. In each sample, a center of the aluminum foil piece was aligned with a center of the electromagnetic wave absorbing film piece. The noise absorption ratio P loss / P in of each sample 61-68 was determined by the same method as in Example 1. The results are shown in Fig. 34-41 and Table 4. Table 4 Probe Nr. θs (1) (°) Aluminiumfolienstück Maximale Rauschabsorption L (mm) Area ratio (2) (%) P loss / P in Frequenz (GHz) 61 30 10 20 0,93 (3) 2,1 62 30 15 30 0,92 (4) 2,1 63 30 20 40 0,9 (5) 2,3 64 30 25 50 0,9 (6) 2,4 65 30 30 60 0,98 4,1 66 30 35 70 0,97 4,2 67 30 40 80 0,95 4,1 68* 30 50 100 - (7) - (7) Note: (1) θs represents the crossing angle of linear scratches.

[0075] (2) An area ratio of the aluminum foil piece to the electromagnetic wave absorbing film piece.

[0076] (3) The noise absorption ratio P loss / P in was 0.98 in a frequency range of about 5 GHz and had a large peak of 0.93 at a frequency of 2.1 GHz.

[0077] (4) The noise absorption ratio P loss / P in was 0.98 in a frequency range of about 5 GHz or more and had a large peak of 0.92 at a frequency of 2.1 GHz.

[0078] (5) The noise absorption ratio P loss / P in was 0.97 in a frequency range of 4 GHz or more and had a large peak of 0.9 at a frequency of 2.3 GHz.

[0079] (6) The noise absorption ratio P loss / P inwas 0.97 in a frequency range of 4.2 GHz and had a large peak of 0.9 at a frequency of 2.4 GHz.

[0080] (7) P loss / P in was low across the entire frequency range.

[0081] A sample with * is outside the scope of the present invention.

[0082] In Sample 68, in which the electromagnetic wave absorbing film piece and the aluminum foil piece laminated together had the same size, the noise absorption ratio P loss / P in low over the entire frequency range. On the other hand, the maximum noise absorption ratios P loss / P inIn samples 61-67, in which the aluminum foil pieces were laminated with area ratios of 20-80% to the electromagnetic wave absorbing film pieces, the noise absorption ratio was as high as 0.9-0.98 at frequencies ranging from 2.1-4.2 GHz. This indicates that to maximize the noise absorption ratio P loss / P in in a desired frequency range, the area ratio of the aluminum foil piece (electromagnetic wave shielding film) to the electromagnetic wave absorbing film piece should be 10-80%. Example 9

[0083] An aluminum foil piece (thickness: 15 µm) of 25 mm x 50 mm was laminated via a non-conductive adhesive onto the electromagnetic wave absorbing film piece of 50 mm x 50 mm (crossing angle θs of linear scratches: 30°) as used in Example 8, such that the distance D between a side X1 of the electromagnetic wave absorbing film piece and a side X2 (parallel to X1) of the aluminum foil piece was 0 mm, 5 mm, 10 mm, 15 mm, 20 mm, and 25 mm, respectively, as shown in Fig. 6(a) to prepare samples 71-76. The noise absorption ratio P loss / P in of each sample in a range of 0.1-6 GHz was measured in the same manner as in Example 2. The relationship between the noise absorption ratio P loss / P in and the distance D in each sample is in Fig. 42-47. As can be seen from Fig. 42-47, a curve of the noise absorption ratio P loss / P indrastically as the distance D changed. Example 10

[0084] A copper foil piece (thickness: 15 µm) of L (10 mm, 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, 40 mm and 50 mm) x 50 mm was laminated via a non-conductive adhesive onto an electromagnetic wave absorbing film piece of 50 mm x 50 mm which was cut from the electromagnetic wave absorbing film (crossing angle θs of linear scratches: 60°) obtained in Reference Example 2 as in Fig. 8 to prepare samples 81-88. In each sample, a center of the copper foil piece was aligned with a center of the electromagnetic wave absorbing film piece. The noise absorption ratio P loss / P in of each sample 81-88 was determined by the same method as in Example 1. The results are shown in Fig. 48-55 and Table 5. Table 5 Probe Nr. θs (1) (°) Kupferfolienstück Maximale Rauschabsorption L (mm) Area ratio (2) (%) P loss / P in Frequency (GHz) 81 60 10 20 0,96 1,9 82 60 15 30 0,98 2,1 83 60 20 40 0,97 2,2 84 60 25 50 0,95 2,2 85 60 30 60 0,98 3,4 86 60 35 70 0,99 4,1 87 60 40 80 0,98 4,2 88* 60 50 100 - (3) - (3)

[0085] Note: (1) θs represents the crossing angle of linear scratches.

[0086] (2) An area ratio of the copper foil piece to the electromagnetic wave absorbing film piece.

[0087] (3) P loss / P in was low across the entire frequency range.

[0088] A sample with * is outside the scope of the present invention.

[0089] In Sample 88, in which the electromagnetic wave absorbing film piece and the copper foil piece laminated together had the same size, the noise absorption ratio P loss / P in low across the entire frequency range. On the other hand, the maximum noise absorption ratios P loss / P inIn samples 81-87, in which the copper foil pieces were laminated to the electromagnetic wave absorbing film pieces with area ratios of 20-80%, the noise absorption ratio was as high as 0.95-0.99 at frequencies ranging from 1.9-4.2 GHz. This indicates that to maximize the noise absorption ratio P loss / P in in a desired frequency range, the area ratio of the copper foil piece (electromagnetic wave shielding film) to the electromagnetic wave absorbing film piece should be 10-80%. Example 11

[0090] A copper foil piece (thickness: 15 µm) of 25 mm x 50 mm was laminated via a non-conductive adhesive to the same electromagnetic wave absorbing film piece of 50 mm x 50 mm (crossing angle θs of linear scratches: 60°) as used in Example 10, such that the distance D between a side X1 of the electromagnetic wave absorbing film piece and a side X2 (parallel to X1) of the copper foil piece was 0 mm, 5 mm, 10 mm, 15 mm, 20 mm, and 25 mm, respectively, as shown in Fig. 6(a) to prepare samples 91-96. The noise absorption ratio P loss / P in of each sample in a range of 0.1-6 GHz was measured in the same manner as in Example 2. The relationship between the noise absorption ratio P loss / P in and the distance D in each sample is in Fig. 56-61. As can be seen from Fig. 56-61, a curve of the noise absorption ratio P loss / P indrastically as the distance D changed. Example 12

[0091] A copper foil piece (thickness: 15 µm) of L (10 mm, 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, 40 mm and 50 mm) x 50 mm was laminated via a non-conductive adhesive onto an electromagnetic wave absorbing film piece of 50 mm x 50 mm which was cut from the electromagnetic wave absorbing film (crossing angle θs of linear scratches: 45°) obtained in Reference Example 3 as in Fig. 8 to prepare samples 101-108. In each sample, a center of the copper foil piece was aligned with a center of the electromagnetic wave absorbing film piece. The noise absorption ratio P loss / P in of each sample 101-108 was determined by the same method as in Example 1. The results are shown in Fig. 62-69 and Table 6. Table 6 Sample No. θs (1) (°) piece of copper foil Maximum noise absorption L (mm) Area ratio (2) (%) P loss / P in Frequency (GHz) 101 45 10 20 0,88 2,4 102 45 15 30 0,90 3,5-4,2 103 45 20 40 0,92 3,3-4 104 45 25 50 0,93 3,3-3,8 105 45 30 60 0,97 3,4 106 45 35 70 0,98 3,9 107 45 40 80 0,94 4,1 108* 45 50 100 - (3) - (3)

[0092] Note: (1) θs represents the crossing angle of linear scratches.

[0093] (2) An area ratio of the copper foil piece to the electromagnetic wave absorbing film piece.

[0094] (3) P loss / P in was low across the entire frequency range.

[0095] A sample with * is outside the scope of the present invention.

[0096] In Sample 108, in which the electromagnetic wave absorbing film piece and the copper foil piece laminated together had the same size, the noise absorption ratio P loss / P in low across the entire frequency range. On the other hand, the maximum noise absorption ratios P loss / P inIn samples 101-107, in which the copper foil pieces were laminated to the electromagnetic wave absorbing film pieces with area ratios of 20-80%, the values were as high as 0.90-0.98 at frequencies ranging from 2.4 to 4.2 GHz. This indicates that to maximize the noise absorption ratio P loss / P in in a desired frequency range, the area ratio of the copper foil piece (electromagnetic wave shielding film) to the electromagnetic wave absorbing film piece should be 10-80%. Example 13

[0097] A copper foil piece (thickness: 15 µm) of 25 mm x 50 mm was laminated via a non-conductive adhesive to the same electromagnetic wave absorbing film piece of 50 mm x 50 mm (crossing angle θs of linear scratches: 45°) as used in Example 12, such that the distance D between a side X1 of the electromagnetic wave absorbing film piece and a side X2 (parallel to X1) of the copper foil piece was 0 mm, 5 mm, 10 mm, 15 mm, 20 mm, and 25 mm, respectively, as shown in Fig. 6(a) to prepare samples 111-116. The noise absorption ratio P loss / P in of each sample in a range of 0.1-6 GHz was measured in the same manner as in Example 2. The relationship between the noise absorption ratio P loss / P in and the distance D in each sample is in Fig. 70-75. As can be seen from Fig. 70-75, a curve of the noise absorption ratio P loss / P indrastically as the distance D changed. Example 14

[0098] A copper foil piece (thickness: 15 µm) of L (10 mm, 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, 40 mm and 50 mm) x 50 mm was laminated via a non-conductive adhesive onto an electromagnetic wave absorbing film piece of 50 mm x 50 mm which was cut from the electromagnetic wave absorbing film (crossing angle θs of linear scratches: 30°) obtained in Reference Example 4 as in Fig. 8 to prepare samples 121-128. In each sample, a center of the copper foil piece was aligned with a center of the electromagnetic wave absorbing film piece. The noise absorption ratio P loss / P in of each sample 121-128 was determined by the same method as in Example 1. The results are shown in Fig. 76-83 and Table 7. Table 7 Sample No. θs (1) (°) piece of copper foil Maximum noise absorption L (mm) Area ratio (2) (%) P loss / P in Frequency (GHz) 121 30 10 20 0,91 2,1 122 30 15 30 0,9 2,2 123 30 20 40 0,89 2,4 124 30 25 50 0,97 4,2 125 30 30 60 0,98 4,0 126 30 35 70 0,95 4,2 127 30 40 80 0.92 4.2 128* 30 50 100 - (3) - (3)

[0099] Note: (1) θs represents the crossing angle of linear scratches.

[0100] (2) An area ratio of the copper foil piece to the electromagnetic wave absorbing film piece.

[0101] (3) P loss / P in was low across the entire frequency range.

[0102] A sample with * is outside the scope of the present invention.

[0103] In Sample 128, in which the electromagnetic wave absorbing film piece and the copper foil piece laminated together had the same size, the noise absorption ratio P loss / P in low across the entire frequency range. On the other hand, the maximum noise absorption ratios P loss / P inIn samples 121-127, in which the copper foil pieces were laminated to the electromagnetic wave absorbing film pieces with area ratios of 20-80%, the values were as high as 0.9-0.98 at frequencies ranging from 2.1-4.2 GHz. This indicates that to maximize the noise absorption ratio P loss / P in in a desired frequency range, the area ratio of the copper foil piece (electromagnetic wave shielding film) to the electromagnetic wave absorbing film piece should be 10-80%. Example 15

[0104] A copper foil piece (thickness: 15 µm) of 25 mm x 50 mm was laminated via a non-conductive adhesive to the same electromagnetic wave absorbing film piece of 50 mm x 50 mm (crossing angle θs of linear scratches: 30°) as used in Example 14, such that the distance D between a side X1 of the electromagnetic wave absorbing film piece and a side X2 (parallel to X1) of the copper foil piece was 0 mm, 5 mm, 10 mm, 15 mm, 20 mm, and 25 mm, respectively, as shown in Fig. 6(a) to prepare samples 131-136. The noise absorption ratio P loss / P in of each sample in a range of 0.1-6 GHz was measured in the same manner as in Example 2. The relationship between the noise absorption ratio P loss / P in and the distance D in each sample is in Fig. 84-89. As can be seen from Fig. 84-89, a curve of the noise absorption ratio P loss / P indrastically as the distance D changed. EFFECTS OF THE INVENTION

[0105] The electromagnetic wave absorbing composite sheet of the present invention having the above structure exhibits excellent electromagnetic wave absorption capacity and can maximize the absorption capacity of electromagnetic wave noise in a desired frequency range by changing the area ratio of an electromagnetic wave shielding film to an electromagnetic wave absorbing film within a range of 10-80%. When used in electronic devices and parts that emit electromagnetic wave noise at specific frequencies, their electromagnetic wave noise can be effectively absorbed by such electromagnetic wave absorbing composite sheets. DESCRIPTION OF REFERENCE NUMBERS 10 Electromagnetic wave absorbing composite sheet 1 Electromagnetic wave absorbing film 11 Plastic film 12, 12a, 12b, 112 Thin metal film 13, 13a, 13b, 113, 113a, 113b Linear scratch 2 Electromagnetic wave shielding film 100 Thin metal film-plastic composite film 202a, 202b, 232a, 232b pattern roller 203a, 203b, 233a, 233b sliding roller 204a, 204b, 234a, 234b Measuring instruments for electrical resistance (roller) 205a, 205b, 235a support roller 221, 224 role 222, 223 guide roller 300 insulating substrate 301 Grounded electrode 302 guide pin 303 Coaxial Cable D Distance between one side X1 of an electromagnetic wave absorbing film piece and one side X2 of a metal foil piece MSL microstrip line NA Network Analyzer θs crossing angle of linear scratches in electromagnetic wave absorbing film Ls Length of linear scratch W Width of linear scratch I Distance from linear scratches

Claims

[1] An electromagnetic wave absorbing composite sheet comprising an electromagnetic wave absorbing film (1) and an electromagnetic wave shielding film (2) laminated on the electromagnetic wave absorbing film (1); wherein the electromagnetic wave absorbing film (1) has a single- or multi-layered thin metal film (12) formed on a surface of a plastic film (11), the thin metal film (12) being provided in a large number (plurality) of substantially parallel, intermittent, linear scratches (13a, 13b) with irregular widths and intervals in multiple directions; characterized by that an area ratio of the electromagnetic wave shielding film (2) to the electromagnetic wave absorbing film (1) is 10-80%. [2] The electromagnetic wave absorbing composite sheet according to claim 1, wherein the area ratio of the electromagnetic wave shielding film (2) to the electromagnetic wave absorbing film (1) is 20-80%. [3] The electromagnetic wave absorbing composite sheet according to claim 2, wherein the area ratio of the electromagnetic wave shielding film (2) to the electromagnetic wave absorbing film (1) is 30-70%. [4] The electromagnetic wave absorbing composite sheet according to any one of claims 1-3, wherein the electromagnetic wave shielding film (2) is a conductive metal foil, a plastic film with a thin conductive metal film or coating, or a carbon sheet. [5] The electromagnetic wave absorbing composite sheet according to any one of claims 1-4, wherein the linear scratches in the electromagnetic wave absorbing film (1) have widths in a range of 0.1-100 µm for 90% or more and 1-50 µm on average and lateral pitches in a range of 1-500 µm and 1-200 µm on average. [6] The electromagnetic wave absorbing composite sheet according to any one of claims 1-5, wherein the linear scratches in the electromagnetic wave absorbing film (1) have an acute crossing angle θs in a range of 30-90°. [7] The electromagnetic wave absorbing composite sheet according to claim 4, wherein the conductive metal in the electromagnetic wave shielding film (2) is at least one selected from the group consisting of aluminum, copper, silver, tin, nickel, cobalt, chromium and their alloys. [8] The electromagnetic wave absorbing composite sheet according to any one of claims 1-7, wherein both the electromagnetic wave absorbing film (1) and the electromagnetic wave shielding film (2) are in a rectangular or square shape.

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