KR20110026436A - Electromagnetic-wave shielding material, and printed-wiring board - Google Patents

Abstract

It is possible to maintain the long-term electron shielding effect even when repeated bending / sliding occurs. The electromagnetic shielding material 101 includes a first conductive adhesive layer disposed between the first metal layer 21 and the second metal layer 22 while the first metal layer 21 and the second metal layer 22 are stacked. 11), four layers of the first metal layer 21, the first conductive adhesive layer 11, the second metal layer 22, and the second conductive adhesive layer 12 are laminated in the arrangement order. In addition, the electromagnetic shielding material 101 is formed by the first release sheet 31 and the second release sheet 32 to protect the laminated structure formed of the first conductive adhesive layer 11, the first metal layer 21, and the like. The surfaces are each covered.

Description

Electromagnetic shielding material and printed wiring board {ELECTROMAGNETIC-WAVE SHIELDING MATERIAL, AND PRINTED-WIRING BOARD}

The present invention relates to electromagnetic shielding materials and printed wiring boards used in devices such as computers, communication devices, video cameras, and the like.

Background Art Conventionally, electromagnetic shielding materials using metal layers have been known. For example, Patent Document 1 discloses an electromagnetic shielding material having a structure in which one or two or more metal films having a film thickness of 1 to 8 µm are formed by sputtering, vapor deposition, or plating. In patent document 2, Cu (film thickness of 0.3-3 micrometers) is formed in the 1st layer on ABS or PC type polymer alloy using the vacuum plating method, and Sn-Cr or Sn-Ni (film thickness 0.1- is formed in 2nd layer). The electromagnetic shielding film of the structure which formed 3 micrometers) is disclosed. Patent Document 3 discloses an electromagnetic wave shield having a structure formed by forming a base layer with 10 to 60 wt% of a composite metal oxide hydrate and a binder of 40 to 90 wt% and electroless plating Cu and / or Ni on the surface of the base layer. Is disclosed.

The electromagnetic shielding materials disclosed in these patent documents 1, 2, and 3 have a structure in which a plurality of metal layers are laminated in abutting state, whereby one metal layer is broken by metal fatigue due to repetition of bending, so that conductivity at the fracture portion is improved. Even in the blocked state, it is possible for the remaining metal layer to cover the broken portion to maintain the electron shielding effect.

Patent Document 1: Japanese Patent Application Laid-Open No. 2000-120 Patent Document 2: Japanese Patent Laid-Open No. 2000-119 Patent Document 3: Japanese Patent Application Laid-Open No. Hei 90-13

In recent years, electromagnetic shielding materials and printed wiring boards that can withstand repeated bending / sliding ranging from large bending radii to small bending radii (1.0 mm) in devices such as computers, communication devices, and video cameras are required. Therefore, the application of the electromagnetic shielding materials disclosed in the above-described prior patent documents 1, 2, and 3 can maintain the electron shielding effect for a longer time than in the case of the single layer metal layer, but is limited only by laminating a plurality of metal layers in a bonded state. There is a demand for realization of an electron shield effect for a longer period of time.

It is an object of the present invention to provide an electromagnetic shielding material and a printed wiring board capable of maintaining a long-term electron shielding effect even when repeatedly bending / sliding occurs.

The electromagnetic shielding material of the present invention has a plurality of stacked metal layers and a conductive adhesive layer positioned between at least one layer of the metal layers.

According to the said structure, since a conductive adhesive layer is located between the layers of a metal layer, metal layers mutually become in the state connected with each other by indirect contact through a conductive adhesive layer. As a result, the electromagnetic shielding material has an electron shielding effect by the conductivity of the plurality of metal layers electrically integrated.

Here, for example, when a repetitive bending / sliding operation from a large bending radius to a small bending radius (1.0 mm, etc.) occurs for the electromagnetic shielding material, the metal layer may be destroyed due to metal fatigue due to a change in stress. However, the probability of breakage in the same portion of all metal layers is low. In addition, because the conductive adhesive layer is present between the layers of the metal layer, the metal layers are arranged at intervals from each other, so that when the metal layer is broken, the breakdown proceeds in the layer direction that becomes the thickness direction of the electromagnetic shielding material. By blocking through, it is possible to reduce the effects of breakage on adjacent metal layers. As a result, it is possible to further lower the probability of breakage in the same portion of all the metal layers.

Therefore, a plurality of metal layers are less likely to be destroyed at the same time, and even if any part of one metal layer is destroyed and loses conductivity, the conductive adhesive layer and the other metal layer bypass the fractured portions to maintain conductivity. Therefore, the fall and the loss of the electron shielding effect can be prevented over a long period of time.

In addition, since the conductive adhesive layer is disposed between at least one layer of the metal layer, it is possible to include the metal layer composed of a plurality of layers in the electromagnetic shielding material in various lamination forms. That is, the electromagnetic shielding material may be configured to have a lamination form in which the metal layers are in indirect contact with each other through the conductive adhesive layer, and a lamination form in which the metal layers are in direct contact with each other. Thereby, the electromagnetic shielding material of the structure by the contact of an indirect metal layer through a conductive adhesive layer or the direct contact of metal layers can be used according to a use.

The conductive adhesive layer of the present invention may be located on at least one shield material surface.

According to the said structure, since the layer located on the at least one shield material surface becomes a conductive adhesive layer, the board | substrate and an electromagnetic shielding material can be bonded by adhering the conductive adhesive layer of the shield material surface to board | substrates, such as a printed wiring board. Can be. As a result, the work of attaching the electromagnetic shielding material to the substrate can be performed easily and in a short time, and can be suitably used for a substrate for bending.

One or more of the metal layers of the present invention may be formed to have a bellows structure along the shield material surface.

According to the above configuration, the metal layer of the bellows structure is made stretchable by the bellows portion with respect to the shielding material surface. Therefore, even when the electromagnetic shielding material is stressed in the stretching direction with respect to the metal layer due to bending or the like, the stress is relaxed by stretching in the metal layer of the bellows structure. Thereby, the electromagnetic shielding material can reduce the metal fatigue of the metal layer of a bellows structure, and can prevent the fall and the loss | disappearance of an electromagnetic shielding effect for a long time.

The conductive adhesive layer and the metal layer of the present invention may be alternately arranged.

According to the above configuration, the conductive adhesive layer is present between the layers of all the metal layers so that all the metal layers can be arranged at intervals from each other. As a result, the probability of breakage occurring in the same portion in all the metal layers can be further lowered, so that the degradation and disappearance of the electron shielding effect can be prevented for a longer period of time.

The conductive adhesive layer of the present invention may be formed by an anisotropic conductive material.

According to the said structure, by forming a conductive adhesive layer with an anisotropic conductive material, it can be stronger against bending than when the conductive adhesive layer is formed with an isotropic conductive material. This reduces the possibility of breakage of the conductive adhesive layer due to repetition of bending, whereby the decrease and disappearance of the electron shielding effect can be prevented over a longer period of time.

The conductive adhesive layer of the present invention may be formed of a conductive material in which conductive particles containing a soft magnetic material as a main component and a binder are mixed.

According to the said structure, electroconductive particle exhibits the high magnetization, it can suppress the fall of permeability also with respect to the electromagnetic wave with a high frequency, and an electromagnetic shielding material can absorb an electromagnetic wave. As a result, the electromagnetic shielding material has a function of absorbing electromagnetic waves in addition to the function of the electromagnetic shielding effect.

In the printed wiring board of the present invention, the electromagnetic shielding material is adhered to the at least one surface of the substrate including the printed circuit by the conductive adhesive layer.

According to the said structure, even if it is used for the use which the printed wiring board is bend | folded, an electron shielding effect can be maintained over a long term.

1: is explanatory drawing which shows the schematic cross section of an electromagnetic shielding material.
It is explanatory drawing which shows the schematic cross section of an electromagnetic shielding material.
It is explanatory drawing which shows the schematic cross section of an electromagnetic shielding material.
It is explanatory drawing which shows the schematic cross section of an electromagnetic shielding material.
It is explanatory drawing which shows the schematic cross section of an electromagnetic shielding material.
It is explanatory drawing which shows the schematic cross section of an electromagnetic shielding material.
It is explanatory drawing which shows the schematic cross section of an electromagnetic shielding material.
It is explanatory drawing which shows the test method of a bending resistance test.
9 is an explanatory diagram showing a state in which an electromagnetic shielding material deteriorates.
10 is an explanatory diagram showing a state in which an electromagnetic shielding material deteriorates.
It is explanatory drawing which shows the manufacturing process of a printed wiring board, and is a figure which shows a preparation process.
It is explanatory drawing which shows the manufacturing process of a printed wiring board, and is a figure which shows a pressurization process.
It is explanatory drawing which shows the manufacturing process of a printed wiring board, and is a figure which shows a peeling process.
It is explanatory drawing which shows the manufacturing process of a printed wiring board, and manufacturing is completed.
It is explanatory drawing which shows the schematic cross section of a printed wiring board.

EMBODIMENT OF THE INVENTION The electromagnetic shielding material which concerns on embodiment of this invention is demonstrated with reference to FIGS.

(Overall configuration)

The electromagnetic shielding material has a plurality of stacked metal layers and a conductive adhesive layer located between at least one layer of these metal layers. In other words, the electromagnetic shielding material has a conductive adhesive layer between at least one layer of the metal layer. In addition, as long as the electromagnetic shielding material is a structure which has a conductive adhesive layer between layers as mentioned above, it may be a structure without another layer, and the structure which arbitrarily combined other metal layers and a conductive adhesive layer may be sufficient.

According to the said structure, an electromagnetic shielding material can include a metal layer which consists of multiple layers in an electromagnetic shielding material in various laminated forms by arrange | positioning a conductive adhesive layer between at least one layer of a some metal layer. As a result, the electromagnetic shielding material may be classified and used in various electromagnetic shielding materials in various laminated forms by indirect metal contact through the conductive adhesive layer or direct contact between metal layers.

Specifically, for example, as shown in FIGS. 1 to 5, as for the electromagnetic shielding materials 101 to 105, the first metal layer 21 and the second metal layer 22 are stacked, and the first electromagnetic wave shielding material is stacked. The first conductive adhesive layer 11 is disposed between the metal layer 21 and the layer of the second metal layer 22. That is, the electromagnetic shielding materials 101 to 105 have at least a configuration in which three layers of the first conductive adhesive layer 11, the first metal layer 21, and the second conductive adhesive layer 12 are stacked in the arrangement order. .

In addition, the electromagnetic shielding materials 101 to 105 at the time of not being used, the first release sheet 31 and the second release, in order to protect the laminated structure composed of the first conductive adhesive layer 11, the first metal layer 21, or the like. The surface is covered by the sheet 32, respectively. In use, the first release sheet 31 and the second release sheet 32 are peeled off to expose the surface of the laminated structure to the outside. For example, in the electromagnetic shielding material 101 of FIG. 1, the first metal layer 21 and the second conductive adhesive layer 12 are exposed to the outside.

In detail, as shown in FIG. 1, the electromagnetic shielding material 101 can be comprised by the structure by which the conductive adhesive layer and the metal layer were alternately arrange | positioned. That is, in the electromagnetic shielding material 101, four layers of the first metal layer 21, the first conductive adhesive layer 11, the second metal layer 22, and the second conductive adhesive layer 12 are stacked in the arrangement order. It may be made of a configuration, it may be composed of four or more layers in the arrangement order of the metal layer and the conductive adhesive layer.

In addition, as shown in FIG. 2, the electromagnetic shielding material 102 has a lamination form in which the metal layers 21 and 22 are indirectly contacted through the first conductive adhesive layer 11, and the metal layers 21 and 23 are connected to each other. It can be made of a configuration having a laminated form in direct contact with. That is, the electromagnetic shielding material 102 includes five layers of the third metal layer 23, the first metal layer 21, the first conductive adhesive layer 11, the second metal layer 22, and the second conductive adhesive layer 12. This may be made of a stacked configuration in the arrangement order. As shown in FIG. 3, the electromagnetic shielding material 103 includes the third conductive adhesive layer 13, the third metal layer 23, the first metal layer 21, the first conductive adhesive layer 11, and the second. Six layers of the metal layer 22 and the second conductive adhesive layer 12 may be laminated in the arrangement order.

In addition, as shown in FIG. 4, the electromagnetic shielding material 104 may include an insulating layer 51. That is, the electromagnetic shielding material 104 includes five layers of the insulating layer 51, the first metal layer 21, the first conductive adhesive layer 11, the second metal layer 22, and the second conductive adhesive layer 12. It may be made of a stacked configuration in the arrangement order.

1 to 5, in the electromagnetic shielding materials 101 to 105, the first conductive adhesive layer 11 is positioned between the first metal layer 21 and the second metal layer 22, so that the metal layer ( 21 and 22 are brought into contact with each other by indirect contact through the first conductive adhesive layer 11. As a result, the electromagnetic shielding materials 101 to 105 have an electron shielding effect due to the conductivity of the plurality of metal layers 21 and 22 that are electrically integrated with each other.

Here, as shown in FIG. 8, when the repetitive bending / sliding operation with a small bending radius (1.0 mm, etc.) occurs with respect to the electromagnetic shielding material 101 of FIG. A crack 41 may occur on at least one of the metal layer 21 and the second metal layer 22. In addition, as shown in FIG. 9, if the bending / sliding continues repeatedly, the cracks 41 may grow in the width direction and the thickness direction intersecting with the bending direction and may be totally destroyed in the entire width direction and the entire layer direction. have. When fracture occurs due to such a crack 41, the regions on both sides of the metal layers 21 and 22 are electrically insulated with the crack 41 interposed therebetween. In addition, the imaginary line which consists of a 2-dot chain line shows the state of the electromagnetic shielding material 104 of FIG.

However, the probability that cracks 41 occur in the same portions of the first metal layer 21 and the second metal layer 22 is low. In addition, since the first conductive adhesive layer 11 is present between the layers of the first metal layer 21 and the second metal layer 22, the metal layers 21 and 22 are arranged at intervals from each other, so that at least one When the metal layers 21 and 22 are broken by the cracks 41, the propagation of the cracks 41 (destruction) in the layer direction that becomes the thickness direction of the electromagnetic shielding material 101 is performed by the first conductive adhesive layer 11. It is possible to reduce the influence of breakage on the adjacent metal layers 21 and 22 by being prevented by the " As a result, the electromagnetic shielding materials 101 to 105 have a lower probability of occurrence of breakage in the same portions of all the metal layers 21 and 22.

On the other hand, as shown in FIG. 10, when the metal layers 21 and 22 are in direct contact, the crack 41 which generate | occur | produced in one metal layer 21 and 22 is directly in the other metal layer 22, By affecting 21), the cracks 41 easily occur at the same portions.

Accordingly, all the electromagnetic shielding materials 101 to 105 of FIGS. 1 to 5 have a low possibility that the same portions of the first metal layer 21 and the second metal layer 22 are destroyed at the same time, and one metal layer 21. ) Or the metal layer 22 is in a state where any part of the metal layer 22 is destroyed and thus loses conductivity, so that the first metal layer 21 and the other metal layer 22 bypass the fractured portion to maintain conductivity, thereby deteriorating and disappearing the electron shielding effect. Can be prevented over a long period of time.

In addition, as shown in FIG. 1, in the case where the conductive adhesive layers 11 and 12 and the metal layers 21 and 22 are alternately arranged, all the metal layers 21 and 22 can be arrange | positioned at intervals from each other. As a result, since the probability of breakage occurring in the same portion in all the metal layers 21 and 22 can be further lowered, it is possible to prevent the decrease and disappearance of the electron shielding effect for a longer period of time.

Further, the conductive adhesive layer of the electromagnetic shielding material may be located on at least one shielding material surface. Specifically, as shown in FIGS. 1 and 2, the second conductive adhesive layer 12 may be disposed on the surface of one shield material of the electromagnetic shielding materials 101 and 102, and the second conductive adhesive layer 12 may be disposed as shown in FIG. 3. The conductive adhesive layer 12 may be disposed on the surface of one shield of the electromagnetic shield material 103, and the third conductive adhesive layer 13 may be disposed on the surface of one shield of the electromagnetic shield material 103. . Here, the "shield material surface" is a position which is in the state exposed to the exterior when peeling the 1st release sheet 31 and the 2nd release sheet 32 at the time of use.

According to the above structure, for example, as shown in FIG. 1, since the layer located on the surface of the shielding material becomes the second conductive adhesive layer 12, the second conductive adhesive layer 12 on the surface of the shielding material is applied to a substrate such as a printed wiring board. ) Can be easily bonded to the substrate and the electromagnetic shielding material 101. Thereby, while attaching the electromagnetic shielding material 101 to a board | substrate can be performed easily and in a short time, it can utilize suitably for the board | substrate of the use to bend.

(Metal layer)

The metal layers 21, 22, and 23 of the electromagnetic shielding materials 101 to 105 of FIGS. 1 to 5 will be described in detail. Examples of the metal material for forming the metal layers 21, 22, and 23 include nickel, copper, silver, tin, gold, palladium, aluminum, chromium, titanium, zinc and alloys containing any one or more of these materials. have. In addition, the metal material and thickness of the metal layers 21, 22, and 23 can be appropriately selected according to the required electron shielding effect and repeated bending / sliding resistance, and the thickness is preferably about 0.1 m to 8 m. The metal layers 21, 22, and 23 may be formed by electrolytic plating, electroless plating, sputtering, electron beam deposition, vacuum deposition, CVD, metal-organic, or the like. In addition, the metal layer may be metal foil.

In addition, one or more of the metal layers 21, 22, 23 may be formed to have a bellows structure along the shield material surface. Specifically, as shown in FIG. 6, the electromagnetic shielding material 101 may have a bellows-shaped first metal layer 21 waving in a wave shape along the surface of the shielding material in one direction (X-axis direction), or As shown in FIG. 7, the bellows structure of the first metal layer 21 is waved in a wave shape in two directions intersecting along the surface of the shielding material, preferably in two orthogonal directions (X-axis direction and Y-axis direction). Can have

According to the above configuration, the first metal layer 21 of the bellows structure is made stretchable by the bellows portion with respect to the shield material surface. Therefore, even when stress is generated in the stretching direction with respect to the first metal layer 21 due to the bending of the electromagnetic shielding material, the stress is alleviated by the stretching with respect to the bellows structure of the first metal layer 21. As a result, the electromagnetic shielding material reduces the metal fatigue of the bellows structure of the first metal layer 21, thereby preventing the electron shielding effect from dropping and disappearing for a longer period of time.

The electromagnetic shielding material 101 of FIG. 6 can sufficiently reduce metal fatigue against bending acting to stretch the first metal layer 21 in the X-axis direction. In addition, the electromagnetic shielding material 101 of FIG. 7 can sufficiently reduce metal fatigue against bending acting to stretch the first metal layer 21 in an arbitrary direction along the surface of the shielding material.

In addition, as a formation method of a bellows structure, the arithmetic mean roughness of the surface of the 1st conductive adhesive bond layer 11 used as the base on which the 1st metal layer 21 is formed is set to 0.5-5.0 micrometers, and this surface roughness is used There is a method in which the first metal layer 21 has a bellows structure. As another method of forming the bellows structure, there is a method of forming the first metal layer 21 by depositing a plurality of scaly metal particles on a smooth base (first conductive adhesive layer 11). The average particle diameter of the scaly metal particles is 1 μm to 100 μm, and the thickness is 0.1 μm to 8 μm, and the thickness of more than 8 μm is preferable because the metal layer 22 becomes too thick to obtain a film having a desired thickness. Not.

Further, the material of the scaly metal particles may include nickel, copper, silver, tin, gold, palladium, aluminum, chromium, titanium, zinc and an alloy containing any one or more of these materials. At least one material is appropriately selected depending on the electron shielding effect and the repeated bending / sliding resistance. In addition, the metal layer in which the scaly-shaped metal particles are deposited may form an interstitial portion between the scaly-shaped metal particles by pressing under heating at a predetermined temperature or more, thereby forming an electrically continuous layer. . In this case, the first metal layer 21 is 0.1 when the electromagnetic shielding material 101 including the first metal layer 21 is pressed and adhered to the printed wiring board by a predetermined temperature (for example, 150 ° C.) or more. It adjusts previously so that it may become thickness of micrometer-8 micrometers.

The metal layers 21 and 22 may be porous materials having a plurality of holes or voids. In the case of the porous metal layers 21 and 22 having a plurality of holes, the diameter of the holes is 0.1 μm to 10 μm, and in the case of the porous metal layers 21 and 22 having a plurality of pores, the size of the pores is 0.1 μm to 10 μm. The porosity is 1-50%. In addition, when the porosity exceeds 50%, the conductivity is considerably lowered.

(Conductive adhesive layer)

For example, as shown in FIG. 1, the conductive adhesive layers 11 and 12 are formed of a conductive adhesive agent. The conductive adhesive is formed of a mixture of conductive particles and a binder (such as epoxy resin). That is, the electroconductive adhesive bond layer 2 disperse | distributes electroconductive particle in thermosetting resins, such as an epoxy resin, or mixed resin of a thermosetting resin and a thermoplastic resin. Electrical connection of the conductive adhesive is realized by the continuous and mechanical contact of the conductive particles in the binder, and is maintained by the adhesive force of the binder.

The conductive adhesive is formed by one of isotropic conductivity and anisotropic conductivity.

Isotropic conductive adhesives have the same electrical properties as conventional solders. Therefore, in the case where the conductive adhesive layers 11 and 12 are formed of an isotropic conductive adhesive, it is possible to ensure the electrical conduction state in the conductive adhesive layers 11 and 12 in three directions in all directions including the thickness direction, the width direction, and the longitudinal direction. The electromagnetic shielding material 101 can be formed. On the other hand, in the case where the conductive adhesive layers 11 and 12 are formed of the anisotropic conductive adhesive, the electromagnetic shielding material 101 can secure the electrical conduction state in the conductive adhesive layers 11 and 12 only in the two-dimensional direction formed in the thickness direction. Can be formed.

In addition, one of the conductive adhesive layers 11 and 12 may be formed of an anisotropic conductive adhesive, and the other may be formed of an isotropic conductive adhesive. That is, the electromagnetic shielding material 101 may be configured in which the conductive adhesive layer formed of the anisotropic conductive adhesive and the conductive adhesive layer formed of the isotropic conductive adhesive are mixed.

An isotropic electrically conductive adhesive is a mixture which consists of a binder containing electroconductive particle, and is an adhesive which can be heat-compression-bonded at 100-200 degreeC. Electroconductive particle is a metal powder or a low melting metal powder which has an average particle diameter of 5-50 micrometers, and is mix | blended 150-250 weight part with respect to 100 weight part of binders. The low melting point metal powder here is a melting point of 300 ° C. or less, and includes melting alloy particles having a melting point higher than the initial melting point after melting. In addition, a binder including any one or both of a structural adhesive (not shown) and a heat resistant adhesive (not shown) may be used, and may further include a reducing additive (not shown).

The anisotropic conductive adhesive has a property of conducting only in the heating pressurization direction by, for example, dispersing the resin coated conductive particles. The conductive particles include copper powder, silver powder, nickel powder, silver coated copper powder, gold coated copper powder, silver coated nickel powder, and gold coated nickel powder. The metal powders are electrolytically, atomized, or reduced. Can be formed through. Moreover, in addition to the above, the particle | grains which coat | covered resin to metal powder, and the particle | grains which coat | covered metal powder to resin can also be used.

The low melting metal powder may be formed of a metal composition such as tin silver copper, tin silver copper bismuth, tin silver copper indium, tin silver copper bismuth indium, tin silver bismuth indium, tin bismuth, tin silver bismuth, tin zinc bismuth, tin zinc, and tin indium. . Specifically, Senju Metal Industry Co., Ltd Eco solder (article number: M20, M30, M31, M33, M35, M37, M41, M42, M51, M704, M705, M706, M707, M715, M716) , L11, L20, L21, L23, or Asahi Kasei Coporation alloy powder (described in Japanese Patent Application Laid-Open Nos. 2000-144203 and 2001-176331).

In addition, the conductive adhesive layers 11 and 12 may be formed of a conductive material in which conductive particles containing a soft magnetic material as a main component and a binder are mixed. In this case, it becomes possible to absorb radio waves by suppressing the fall of permeability even with the electromagnetic wave with a high frequency by exhibiting high magnetization of electroconductive particle. Thereby, the electromagnetic wave shielding material 101 has a radio wave absorption function in addition to the function of the electromagnetic shielding effect.

Examples of the structural adhesive include nitrile rubber epoxy, nitrile rubber phenolic, nitrile rubber epoxy, CTBN-epoxy, nylon-epoxy, saturated amorphous polyester-epoxy, epoxyphenolic, epoxy-aromatic polyamide, elastomer epoxy, and the like. . Here, as an elastomer, polyester type and polyamide type elastomer are preferable.

Examples of the heat resistant adhesive include epoxy-silica hybrid resins, phenol-silica hybrids, polyimide-silica hybrids, soluble polyimide-silica hybrids, polyamideimide-silica hybrids, polyamideimide resins, and polyimide resins.

Reducing additives include amino phenol, quinone, hydroquinone, catechol, pyrogallol, juglone, hydroxyanthraquinone, alizarin, anthrarufin, chrysazin, purpurin, qui Reducing substances such as quinalizarin can be used.

On the other hand, the anisotropic conductive adhesive basically has a binder having the same component as the isotropic conductive adhesive, and disperse the conductive particles in the binder. Further, the conductive adhesive is preferably formed of an anisotropic conductive adhesive in that cracks against bending are less likely to occur, and an anisotropic conductive adhesive is easier to thin than an isotropic conductive adhesive.

(Release sheet)

The conductive adhesive layers 11 and 12 and the metal layers 21 and 22 laminated as described above are sandwiched by the first release sheet 31 and the second release sheet 32. In other words, the electromagnetic shielding material 101 includes the conductive adhesive layers 11 and 12, the metal layers 21 and 22, and the release sheets 31 and 32.

The first release sheet 31 and the second release sheet 32 may be coated with a silicone-based or non-silicone-based release agent on a base film such as polyester or polyethylene naphthalate. In addition, the thickness of the 1st and 2nd release sheets 31 and 32 is not specifically limited, It determines suitably in consideration of convenience.

In addition, it is preferable that the first release sheet 31 and the second release sheet 32 are color-coded or have different transparency. In this case, since one surface (surface) and the other surface (rear surface) of the electromagnetic shielding material 101 can be discriminated easily, workability can be improved.

(Insulation layer)

The insulating layer 51 of FIG. 4 consists of a cover film or the coating layer of insulating resin. In addition, when the insulating layer 51 is formed of a cover film, the first release sheet 31 may be omitted. The cover film is made of engineering plastics. For example, polypropylene, crosslinked polyethylene, polyester, polybenzimidazole, polyimide, polyimideamide, polyetherimide, polyphenylene sulfide (PPS), polyethylene naphthalate (PEN), etc. are mentioned. A low-cost polyester film is preferable when much heat resistance is not required, and a polyphenylene sulfide film when flame retardancy is required, and a polyimide film is preferable when heat resistance is required.

In the case of insulated resin, the resin which has insulating property is possible, for example, a thermosetting resin, an ultraviolet curable resin, etc. are mentioned. As a thermosetting resin, a phenol resin, an acrylic resin, an epoxy resin, a melamine resin, a silicone resin, an acrylic modified silicone resin, etc. are mentioned, for example. As ultraviolet curable resin, an epoxy acrylate resin, polyester acrylate resin, these methacrylate modified products, etc. are mentioned, for example. Moreover, as hardening form, any of thermosetting, ultraviolet curing, electron beam hardening, etc. is possible, and what hardens | cures is possible.

(Adhesive resin layer)

In addition, the electromagnetic shielding materials 101-105 of FIGS. 1-5 are formed in the whole or one part of the surface layer which an adhesive resin layer consists of the 1st conductive adhesive layer 11, the 2nd metal layer 22, etc. of the shield material surface. Can be. The adhesive resin layer is not particularly limited as long as the resin has adhesiveness to an object such as a circuit board, but is preferably any one of a polyester resin, an acrylic resin, a urethane resin, and an epoxy resin. Among these resins, epoxy resins are particularly preferred as constituent materials of the adhesive resin layer. In the case of epoxy resin, reflow resistance is improved along with improvement of adhesiveness and connection resistance.

In the case where the electromagnetic wave shielding materials 101 to 105 are provided with the adhesive resin layer, the adhesive resin layer having the adhesive property adheres to the object when the adhesive resin layer is brought into contact with an object such as a circuit board. Can be maintained at a predetermined position of the object. As a result, for example, when the electromagnetic shielding materials 101 to 105 are positioned at a predetermined position of the object, the electromagnetic shielding materials 101 to 105 are applied to the object when a series of adhesion treatments are performed to heat and pressurize both sides. Since it is attached and maintains the positioned state, it can be adhered to a predetermined position with high accuracy, and since it does not need a special mechanism or operation for preventing the position of the electromagnetic shielding materials 101-105 from shifting, it bonds easily, can do.

(How to use)

Next, the usage method of the electromagnetic shielding materials 101-104 of FIGS. 1-4 is demonstrated. As shown in FIG. 12, the electromagnetic shielding materials 101-104 are used when performing an electromagnetic shield with respect to the circuit board 66 (base film). In addition, the electromagnetic shielding material 105 of FIG. 5 is provided with a conductive adhesive layer on at least one of the electromagnetic shielding material 105 and the circuit board 66 before use, so that the electromagnetic shielding materials 101 to 104 of FIGS. Can be used for the circuit board 66 by carrying out the same installation work process.

Here, the circuit board 66 is a base film 63, a printed circuit 64 (signal circuit 64a and ground circuit 64b) formed on the base film 63 and at least a portion (non-insulating portion) 64c. Except for the insulating film 65 formed on the printed circuit (64).

The base film 63 and the insulation film 65 are both made of engineering plastics. For example, resin, such as polypropylene, crosslinked polyethylene, polyester, polybenzimidazole, polyimide, polyimideamide, polyetherimide, polyphenylene sulfide (PPS), is mentioned. A low-cost polyester film is preferable when heat resistance is not largely required, a polyphenylene sulfide film when flame resistance is required, and a polyimide film is preferable when heat resistance is required.

In addition, bonding of the base film 63 and the printed circuit 64 can be bonded through an adhesive agent, and can also be bonded in the same manner as a so-called adhesive-free copper clad laminate that does not use an adhesive. In addition, the insulating film 65 can be bonded to the flexible insulating film using an adhesive, and can also be formed by a series of methods such as coating, drying, exposure, development, and heat treatment of the photosensitive insulating resin. In addition, the circuit board 66 may include a single-sided printed wiring board having a printed circuit only on one side of the base film, a double-sided printed wiring board having a printed circuit on both sides of the base film, a multilayered printed wiring board in which a plurality of such printed wiring boards are stacked, FLEXBOARD (registered trademark) having a multilayer component mounting portion and a cable portion, a flex rigid substrate having a rigid member comprising the multilayer portion, or a TAB tape for a tape carrier package can be appropriately employed.

Next, the attaching operation process for attaching the electromagnetic shielding material 104 of FIG. 4 to the circuit board 66 will be described. In other words, the manufacturing method of the printed wiring board 110 using the electromagnetic shielding material 104 of FIG. 4 is demonstrated.

First, as shown in FIG. 11A, the electromagnetic shielding material 104 of the state provided with the 1st release sheet 31 and the 2nd release sheet 32, respectively is prepared. Then, for example, when one of the second release sheets 32 is peeled from the second conductive adhesive layer 12, the second conductive adhesive layer 12 is exposed to the outside (peeling step).

Thereafter, the second conductive adhesive layer 12 of the electromagnetic shielding material 104 is contacted while being positioned at a predetermined position on the upper surface (surface on the insulating film 65 side) of the circuit board 66. At this time, if the adhesive resin layer is formed on the surface of the second conductive adhesive layer 12, the electromagnetic shielding material 104 is attached to the circuit board 66 by the adhesiveness of the adhesive resin layer. Thereby, even if the electromagnetic shielding material 104 is removed, the positional relationship between the electromagnetic shielding material 104 and the circuit board 66 is not disturbed.

Next, as shown in FIG. 11B, the electromagnetic shielding material 104 and the circuit board 66 are carried in the press machine 69 (69a, 69b) while the state of overlapping is maintained. The electromagnetic shielding material 104 and the circuit board 66 are thermocompressed by press working (130 to 190 ° C, 1 to 4 MPa). A part of the second conductive adhesive layer 12 softened by the heating enters the insulation removing portion 65a by being pressed. In addition, the second conductive adhesive layer 12 and the first conductive adhesive layer 11 are compressed in the pressing direction, and the conductive particles come into contact with each other in the pressing direction, thereby providing conductivity only in the pressing direction. As a result, the first metal layer 21 and the second metal layer 22 of the electromagnetic shielding material 104 and the ground circuit 64b are electrically connected through the conductive particles of the conductive adhesive layers 11 and 12 (adhesive step). ). Thereafter, after curing for about 60 minutes is performed in a heating atmosphere at 150 ° C. (postcure step).

Next, the electromagnetic shielding material 104 and the circuit board 66 integrated by adhesion are carried out from the press 69. And the 1st release sheet 31 is peeled from the insulating layer 51, as shown to FIG. 11C. Thereby, as shown to FIG. 11D and FIG. 12, the printed wiring board 110 with which the electromagnetic shielding material 104 was attached to the circuit board 66 is manufactured.

The printed wiring board 110 manufactured as described above is configured to have the electromagnetic shielding material 104 bonded to the circuit board 66 and the circuit board 66 on which the circuit pattern is formed and bonded by pressing and heating. As a result, the circuit signal of the circuit board 66 is stabilized by the metal layers 21 and 22 in the electromagnetic shielding material 104 of the printed wiring board 110. In addition, the printed wiring board 110 exhibits an electromagnetic shielding effect, and in particular, the electromagnetic shielding property is not reduced and physically protected even for repeated bending / sliding with a small bending radius (1.0 mm).

The electromagnetic shielding materials 101 to 105 may be used in FPC, Chip On Flexible Printed Circuit (COF), RF (Flex Printed Plate), multilayer flexible substrates, rigid substrates, and the like, but are not necessarily limited thereto.

[Example]

The present invention will be described in detail through examples.

First, as shown in FIG. 4, the insulating layer 51 which consists of an epoxy resin set to the layer thickness of 5 micrometers, the 1st metal layer 21 which consists of silver deposition set to the layer thickness of 0.1 micrometer, and a layer of 17 micrometers First conductive adhesive layer 11 made of anisotropic conductive resin paste A set to a thickness, second metal layer 22 made of silver deposition set to a layer thickness of 0.1 μm, and anisotropic conductive resin paste set to a layer thickness of 5 μm The electromagnetic shielding material 104 in which the second conductive adhesive layer 12 made of B is laminated is prepared.

Next, the first release sheet 31 and the second release sheet 32 of the electromagnetic shielding material 104 are peeled off, and as shown in FIG. 8, the second conductive adhesive layer 12 is printed on a printed wiring board 71 ( To bend test FPC). And the sample of Example 1 in which the shield layer was formed in the printed wiring board 71 by bonding while heating / pressing with a press machine was produced.

According to the above manufacturing method, as shown in Table 1, the various samples which changed the material and film thickness of a conductive adhesive layer and a metal layer were produced.

Specifically, as the sample of Example 2, it consists of the insulating layer 51 which consists of 5 micrometers epoxy resin, the 1st metal layer 21 which consists of 0.1 micrometer silver deposition, and the anisotropic conductive resin paste A of 5 micrometers. Electromagnetic shield of the form in which the 1st conductive adhesive layer 11, the 1st metal layer 21 which consists of 0.1-micrometer silver deposition, and the 2nd conductive adhesive layer 12 which consists of an anisotropic conductive resin paste B of 5 micrometers are laminated | stacked. Ash 104 was used.

Here, 'anisotropic conductive resin paste A' is formed of epoxy resin (100 parts by weight) and silver coated copper powder (20 parts by weight). 'Anisotropic conductive resin paste B' is formed of epoxy resin (100 parts by weight) and silver coated copper powder (60 parts by weight).

In addition, as a sample of Comparative Example 1, the insulating layer 51 made of 5 μm epoxy resin, the first metal layer 21 made of 0.1 μm silver deposition, and the first made of 17 μm anisotropic conductive resin paste A were used. The electromagnetic shielding material of the form in which the conductive adhesive layer 11 was laminated | stacked was used. In addition, as the sample of the comparative example 2, the electromagnetic shielding material formed only by the insulating layer 51 which consists of an epoxy resin of 5 micrometers, and the 1st metal layer 21 formed of the 20 micrometers silver paste was used.

(Flexibility test)

According to the IPC standard, as shown in FIG. 8, the curvature radius of the printed wiring board 111 (any one of the sample of the said Example and a comparative example) with a shield layer between the fixing plate 121 and the sliding plate 122 was attached. Is bent in a U-shape in a state of 1.0 mm, and the sliding plate 122 is slid in the vertical direction at a test atmosphere of 23 ° C at a stroke of 50 mm and a sliding speed of 100 times / minute (sliding reciprocating speed of 100 round trips / minute). It proved whether the resistance of the metal layer of the shield film for printed wiring boards (preservation of electronic shielding property), and the printed wiring board at the time of making it protect.

In addition, the printed circuit of each printed wiring board of the sample of the said Example and a comparative example used the thing of 20 lines, 0.075 mm of line width, and 0.075 mm of space width. In addition, the resistance values (10 Ω, 100 Ω, ∞ Ω) of the metal layer of each sample and the resistance of the printed circuit were increased for the resistance of the metal layer of the shield film for the printed wiring board (maintaining the electromagnetic shielding property) and whether the printed wiring board was protected. The change was confirmed by measuring the number of sliding times at which the rate of change becomes 10 or more. The verification results are shown in Table 1 below.

Table 1 shows the following.

That is, in Examples 1 and 2, the number of sliding times of the shield layer of 10 Ω or more is '16000 times' and '8400 times', respectively, and the number of sliding times of 100 Ω or more is '173200 times' and '75400 times', respectively. The number of sliding times exceeding ∞ Ω was 175700 times and 146000 times, respectively. In Examples 1 and 2, the number of slidings at which the resistance increase rate of the printed wiring circuit became 10% or more was '162900 times' and '417900 times', respectively.

On the other hand, in Comparative Example 1 and Comparative Example 2, the number of sliding times of the shield layer of 10 Ω or more was 400 times and 6400 times, respectively, and the number of slidings of 100 Ω or more was 5700 times and 62100 times, respectively. ', And the number of sliding over ∞Ω was' 231800 times' and' 64800 times', respectively. In Comparative Examples 1 and 2, the number of sliding for which the resistance increase rate of the printed wiring circuit was 10% or more was '86300 times' and '26900 times', respectively.

As a result, the electromagnetic shielding material of the laminated form in which the conductive adhesive layer exists between the metal layers from the relationship between Examples 1 and 2 and Comparative Examples 1 and 2 is the electromagnetic shielding material (comparative example 1) of the laminated form of the metal layer and the conductive adhesive layer. It was found that the resistance (bending resistance) is improved against bending sliding than the electromagnetic shielding material (comparative example 2) only for the metal layer. That is, in Examples 1 and 2, the second layer portion was added to Comparative Example 1, and it was found that the flex resistance of the shield layer and the printed wiring circuit was improved by the two-layer structure. Further, it was found from the relationship between Examples 1 and 2 that the thinner the thickness of the conductive adhesive layer is, the more the effect of suppressing the resistance increase between the shield layer and the printed wiring circuit was obtained.

In addition, this invention can change a design in the range which does not deviate from the claim, and is not limited to the said embodiment or Example.

11: first conductive adhesive layer 12: second conductive adhesive layer
13: third conductive adhesive layer 21: first metal layer
22: second metal layer 23: third metal layer
31: First Release Sheet 32: Second Release Sheet
51: insulating layer 101: electromagnetic shielding material
102: electromagnetic shielding material 103: electromagnetic shielding material
104: electromagnetic shielding material 105: electromagnetic shielding material
110: printed wiring board

Claims (7)

A plurality of stacked metal layers;
And a conductive adhesive layer positioned between at least one layer of the metal layer. The method of claim 1,
The conductive adhesive layer is located on the surface of at least one shield material, electromagnetic shield material. The method according to claim 1 or 2,
At least one of the metal layers is formed to have a bellows structure along the shield material surface. The method according to claim 1 or 2,
The electromagnetic shielding material, characterized in that the conductive adhesive layer and the metal layer are alternately arranged. The method according to claim 1 or 2,
The conductive adhesive layer is formed of an anisotropic conductive material, characterized in that the electromagnetic shield material. The method according to claim 1 or 2,
And said conductive adhesive layer is formed of a conductive material in which conductive particles containing a soft magnetic material as a main component and a binder are mixed. The electromagnetic wave shielding material of Claim 1 or 2 adhere | attaches on at least one surface of the board | substrate containing a printed circuit by the said conductive adhesive layer, The printed wiring board characterized by the above-mentioned.

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