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WO2023190425A1 - Electromagnetic wave shield film - Google Patents

Electromagnetic wave shield film Download PDF

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Publication number
WO2023190425A1
WO2023190425A1 PCT/JP2023/012360 JP2023012360W WO2023190425A1 WO 2023190425 A1 WO2023190425 A1 WO 2023190425A1 JP 2023012360 W JP2023012360 W JP 2023012360W WO 2023190425 A1 WO2023190425 A1 WO 2023190425A1
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WO
WIPO (PCT)
Prior art keywords
inorganic particles
porous inorganic
adhesive layer
shielding film
electromagnetic shielding
Prior art date
Application number
PCT/JP2023/012360
Other languages
French (fr)
Japanese (ja)
Inventor
洋平 芝田
Original Assignee
タツタ電線株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by タツタ電線株式会社 filed Critical タツタ電線株式会社
Priority to CN202380024924.2A priority Critical patent/CN118805451A/en
Publication of WO2023190425A1 publication Critical patent/WO2023190425A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/02—Physical, chemical or physicochemical properties
    • B32B7/025—Electric or magnetic properties
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K9/00—Screening of apparatus or components against electric or magnetic fields

Definitions

  • the present invention relates to an electromagnetic shielding film.
  • An electromagnetic shielding film usually has a structure in which an adhesive layer, a shielding layer made of a metal thin film, etc., and an insulating layer are laminated in this order.
  • the electromagnetic shielding film is superimposed on the printed wiring board and hot-pressed, thereby adhering the electromagnetic shielding film to the printed wiring board with the adhesive layer, thereby producing a shielded printed wiring board. After this adhesion, the components are mounted on the shield printed wiring board by solder reflow. Further, the printed wiring board has a structure in which a printed pattern on a base film is covered with an insulating film.
  • Patent Document 1 discloses a shielding film characterized by comprising a metal layer with a layer thickness of 0.5 ⁇ m to 12 ⁇ m and an anisotropically conductive adhesive layer in a laminated state. has been done.
  • 3A and 3B are explanatory diagrams schematically showing a mechanism in which an adhesive layer and a metal layer delaminate when manufacturing a shield printed wiring board using a conventional electromagnetic shielding film.
  • an electromagnetic shielding film 510 in which an adhesive layer 520 and a shielding layer 530 made of a metal layer are sequentially laminated is heated by hot pressing or solder reflow. Due to this heating, volatile components (mainly water) 560 are generated from the adhesive layer 520 and the like of the electromagnetic shielding film 510 and accumulate between the adhesive layer 520 and the shielding layer 530.
  • the present invention has been made to solve the above problems, and an object of the present invention is to provide an electromagnetic shielding film in which the interlayer adhesion between the adhesive layer and the shielding layer is not easily destroyed even when subjected to heating such as reflow.
  • the goal is to provide the following.
  • the inventor believes that the reason why volatile components accumulate between the adhesive layer and the shield layer is that the adhesive layer absorbs moisture in the air when the electromagnetic shielding film is stored. It was discovered that the above problem could be solved by lowering the hygroscopicity, and the present invention was conceived.
  • the electromagnetic wave shielding film of the present invention is an electromagnetic wave shielding film including an adhesive layer and a shielding layer laminated on the adhesive layer, the adhesive layer comprising a resin and porous inorganic particles.
  • the porous inorganic particles have a pore volume of more than 0.44 mL/g and less than or equal to 1.80 mL/g.
  • the porous inorganic particles function as a filler. Therefore, the strength of the conductive adhesive increases. Furthermore, as will be described later, in the electromagnetic shielding film of the present invention, the porous inorganic particles are difficult to absorb volatile components. Therefore, volatile components are not absorbed in the areas where the porous inorganic particles are present. In other words, the inclusion of porous inorganic particles reduces the hygroscopicity of the adhesive layer as a whole. Therefore, in the electromagnetic shielding film of the present invention, even when subjected to heating such as reflow, the interlayer adhesion between the adhesive layer and the shielding layer is unlikely to be destroyed.
  • the pore volume of the porous inorganic particles is more than 0.44 mL/g and less than 1.80 mL/g.
  • the pores of the porous inorganic particles have an appropriate size, and volatile components such as moisture are difficult to accumulate in the porous inorganic particles.
  • the pore volume is 0.44 mL/g or less, the pores formed in the porous inorganic particles become small, making it easier to exert capillary force.
  • An electromagnetic shielding film is an electromagnetic shielding film comprising an adhesive layer and a shielding layer laminated on the adhesive layer, the adhesive layer comprising a resin and a porous material.
  • the porous inorganic particles have a specific surface area of 280 m 2 /g or more and less than 700 m 2 /g.
  • porous inorganic particles function as a filler. Therefore, the strength of the conductive adhesive increases. Further, as described later, in the electromagnetic shielding film of another embodiment of the present invention, the porous inorganic particles hardly absorb volatile components. Therefore, volatile components are not absorbed in the areas where the porous inorganic particles are present. In other words, the inclusion of porous inorganic particles reduces the hygroscopicity of the adhesive layer as a whole. Therefore, in the electromagnetic shielding film according to another aspect of the present invention, the interlayer adhesion between the adhesive layer and the shielding layer is unlikely to be destroyed even if it is subjected to heating such as reflow.
  • the porous inorganic particles have a specific surface area of 280 m 2 /g or more and less than 700 m 2 /g.
  • the specific surface area of the porous inorganic particles is within the above range, the pores of the porous inorganic particles have an appropriate size, and volatile components such as moisture are difficult to accumulate in the porous inorganic particles.
  • the specific surface area is less than 280 m 2 /g, the pores formed in the porous inorganic particles become large and the porous inorganic particles become brittle. Therefore, it becomes difficult to improve the strength of the adhesive layer.
  • the specific surface area is 700 m 2 /g or more
  • the pores formed in the porous inorganic particles become small, making it easier to exert capillary force.
  • volatile components tend to accumulate in the pores, and the porous inorganic particles tend to absorb the volatile components. Therefore, the hygroscopicity of the adhesive layer as a whole tends to increase.
  • An electromagnetic shielding film is an electromagnetic shielding film comprising an adhesive layer and a shielding layer laminated on the adhesive layer, the adhesive layer comprising a resin and a porous
  • the porous inorganic particles have an average pore diameter of more than 2.5 nm and less than 26 nm.
  • porous inorganic particles function as a filler. Therefore, the strength of the conductive adhesive increases. Furthermore, as will be described later, in the electromagnetic shielding film of yet another embodiment of the present invention, the porous inorganic particles are difficult to absorb volatile components. Therefore, volatile components are not absorbed in the areas where the porous inorganic particles are present. In other words, the inclusion of porous inorganic particles reduces the hygroscopicity of the adhesive layer as a whole. Therefore, in the electromagnetic shielding film of yet another aspect of the present invention, the interlayer adhesion between the adhesive layer and the shielding layer is unlikely to be destroyed even when subjected to heating such as reflow.
  • the average pore diameter of the pores of the porous inorganic particles is greater than 2.5 nm and less than or equal to 26 nm.
  • the pores of the porous inorganic particles have an appropriate size, and volatile components such as moisture are difficult to accumulate in the porous inorganic particles.
  • the average pore diameter of the pores is 2.5 nm or less, the pores formed in the porous inorganic particles become small, making it easier to exert capillary force.
  • the porous inorganic particles preferably have a DBA value of 50 meq/kg or more and less than 200 meq/kg. It is difficult to produce porous inorganic particles with a DBA value of less than 50 meq/kg. When the DBA value is less than 200 meq/kg, hydrophobicity becomes high and water becomes difficult to accumulate in the pores.
  • DBA value refers to the amount of di-n-butylamine adsorbed when porous inorganic particles are treated with a toluene solution of di-n-butylamine (the amount of di-n-butylamine adsorbed per 1 kg of particles). ), and this adsorption amount can be measured by a known titration test or the like.
  • the particle diameter (D 50 ) of the porous inorganic particles is preferably 1.0 to 20.0 ⁇ m.
  • the particle diameter (D 50 ) of the porous inorganic particles is less than 1.0 ⁇ m, it becomes difficult to form pores of an appropriate size in the porous inorganic particles.
  • the particle diameter (D 50 ) of the porous inorganic particles exceeds 20.0 ⁇ m, the adhesive layer becomes thick and it becomes difficult to miniaturize the electromagnetic shielding film.
  • the porous inorganic particles tend to protrude from the adhesive layer, and the connection resistance value when the adhesive layer comes into contact with a ground circuit, which will be described later, tends to increase.
  • the particle diameter (D 50 ) of the porous inorganic particles can be measured using a laser diffraction particle size distribution analyzer (SALD-2200, manufactured by Shimadzu Corporation). Further, the method for measuring the particle diameter (D 50 ) of the conductive filler described later is also the same.
  • SALD-2200 laser diffraction particle size distribution analyzer
  • the adhesive layer preferably contains a conductive filler, and the conductive filler preferably has a particle diameter (D 50 ) of 4.0 to 30.0 ⁇ m. Since the adhesive layer contains the conductive filler, the adhesive layer functions as a conductive adhesive layer. Moreover, when the particle diameter (D 50 ) of the conductive filler is within the above range, the conductivity of the adhesive layer becomes good.
  • the thickness of the adhesive layer is preferably 5 to 50 ⁇ m. If the thickness of the adhesive layer is less than 5 ⁇ m, it will be thin and the adhesiveness will be reduced. When the thickness of the adhesive layer exceeds 50 ⁇ m, the adhesive layer becomes thick and it becomes difficult to miniaturize the electromagnetic shielding film.
  • the adhesive layer preferably contains 1 to 100 parts by weight of the porous inorganic particles based on 100 parts by weight of the resin.
  • the content of the porous inorganic particles is within the above range, the hygroscopicity of the adhesive layer can be suitably reduced.
  • an insulating layer is further laminated on the shielding layer.
  • the shield layer and the adhesive layer can be protected. Furthermore, the presence of the insulating layer can prevent the shield layer from coming into contact with other conductive members.
  • an electromagnetic shielding film in which the interlayer adhesion between the adhesive layer and the shielding layer is not easily destroyed even when subjected to heating such as reflow.
  • FIG. 1 is a cross-sectional view schematically showing an example of the electromagnetic shielding film of the present invention.
  • FIG. 2 is a cross-sectional view schematically showing an example of a shield printed wiring board using the electromagnetic shielding film of the present invention.
  • FIG. 3A is an explanatory diagram schematically showing a mechanism in which an adhesive layer and a metal layer delaminate when manufacturing a shield printed wiring board using a conventional electromagnetic shielding film.
  • FIG. 3B is an explanatory diagram schematically showing a mechanism in which an adhesive layer and a metal layer delaminate when manufacturing a shield printed wiring board using a conventional electromagnetic shielding film.
  • the electromagnetic shielding film of the present invention will be specifically explained.
  • the present invention is not limited to the following embodiments, and can be modified and applied as appropriate without changing the gist of the present invention.
  • FIG. 1 is a cross-sectional view schematically showing an example of the electromagnetic shielding film of the present invention.
  • the electromagnetic shielding film 10 shown in FIG. 1 includes an adhesive layer 20, a shielding layer 30 laminated on the adhesive layer 20, and an insulating layer 40 further laminated on the shielding layer 30.
  • the adhesive layer 20 includes resin and porous inorganic particles.
  • the porous inorganic particles function as a filler. Therefore, the strength of the conductive adhesive increases.
  • the porous inorganic particles have at least the following characteristics. That is, the porous inorganic particles are characterized in that the pore volume of the porous inorganic particles is more than 0.44 mL/g and less than or equal to 1.80 mL/g, and the specific surface area of the porous inorganic particles is 280 m 2 /g.
  • the porous inorganic particles have at least one of the characteristics that the diameter is less than 700 m 2 /g and the average pore diameter of the pores of the porous inorganic particles is more than 2.5 nm and less than 26 nm. Because porous inorganic particles have such characteristics, it is difficult for porous inorganic particles to absorb volatile components.
  • porous inorganic particles have the above characteristics makes it difficult for the porous inorganic particles to absorb volatile components will be explained below.
  • the pores of the porous inorganic particles When the pore volume of the porous inorganic particles is more than 0.44 mL/g and less than 1.80 mL/g, the pores of the porous inorganic particles have an appropriate size, and moisture is trapped in the porous inorganic particles. It is difficult for volatile components such as When the pore volume is 0.44 mL/g or less, the pores formed in the porous inorganic particles become small, making it easier to exert capillary force. When the pores exert capillary force, volatile components tend to accumulate in the pores, and the porous inorganic particles tend to absorb the volatile components. Therefore, the hygroscopicity of the adhesive layer as a whole tends to increase.
  • the pore volume of the porous inorganic particles is preferably 0.80 mL/g or more and 1.80 mL/g or less, more preferably 1.00 mL/g or more and 1.80 mL/g or less. , more preferably 1.60 mL/g or more and 1.80 mL/g or less.
  • the pore volume of the porous inorganic particles can be measured by a nitrogen adsorption method using an elemental analyzer: Vari EL III (manufactured by Elementar). Further, the methods for measuring the specific surface area and average pore diameter, which will be described later, are also the same.
  • the specific surface area of the porous inorganic particles is 280 m 2 /g or more and less than 700 m 2 /g, the pores of the porous inorganic particles have an appropriate size, and volatile components such as moisture are contained in the porous inorganic particles. is difficult to accumulate.
  • the specific surface area is less than 280 m 2 /g, the pores formed in the porous inorganic particles become large and the porous inorganic particles become brittle. Therefore, it becomes difficult to improve the strength of the adhesive layer.
  • the specific surface area is 700 m 2 /g or more, the pores formed in the porous inorganic particles become small, making it easier to exert capillary force.
  • the specific surface area of the porous inorganic particles is preferably 280 m 2 /g or more and 500 m 2 /g or less, more preferably 280 m 2 / g or more and 480 m 2 /g or less, and 280 m 2 /g. Above, it is more preferable that it is 300 m 2 /g or less.
  • the average pore diameter of the pores of the porous inorganic particles is more than 2.5 nm and less than 26 nm, the pores of the porous inorganic particles will have an appropriate size, and moisture etc. will not evaporate into the porous inorganic particles. Ingredients do not accumulate easily.
  • the average pore diameter of the pores is 2.5 nm or less, the pores formed in the porous inorganic particles become small, making it easier to exert capillary force.
  • volatile components tend to accumulate in the pores, and the porous inorganic particles tend to absorb the volatile components. Therefore, the hygroscopicity of the adhesive layer as a whole tends to increase.
  • the average pore diameter of the pores of the porous inorganic particles is preferably 7 nm or more and 26 nm or less, more preferably 11 nm or more and 26 nm or less, and even more preferably 21 nm or more and 26 nm or less.
  • the DBA value of the porous inorganic particles is preferably 50 meq/kg or more and less than 200 meq/kg, more preferably 50 to 175 meq/kg. It is difficult to produce porous inorganic particles with a DBA value of less than 50 meq/kg. When the DBA value is less than 200 meq/kg, hydrophobicity becomes high and water becomes difficult to accumulate in the pores.
  • the particle diameter (D 50 ) of the porous inorganic particles is preferably 1.0 to 20.0 ⁇ m, more preferably more than 2.5 ⁇ m and less than 15.0 ⁇ m, and 2. Even more preferably, it is greater than .5 ⁇ m and less than 10.0 ⁇ m.
  • the particle diameter (D 50 ) of the porous inorganic particles is less than 1.0 ⁇ m, it becomes difficult to form pores of an appropriate size in the porous inorganic particles.
  • the particle diameter (D 50 ) of the porous inorganic particles exceeds 20.0 ⁇ m, the adhesive layer becomes thick and it becomes difficult to miniaturize the electromagnetic shielding film.
  • the porous inorganic particles tend to protrude from the adhesive layer, and the connection resistance value when the adhesive layer comes into contact with a ground circuit, which will be described later, tends to increase.
  • the type of porous inorganic particles is not particularly limited, but silica, alumina, etc. can be used. Among these, silica is preferred, and hydrophobized silica is more preferred.
  • the adhesive layer 20 preferably contains 1 to 100 parts by weight, more preferably 1 to 50 parts by weight, and 1 to 30 parts by weight of porous inorganic particles based on 100 parts by weight of the resin. It is even more preferable to include. When the content of the porous inorganic particles is within the above range, the hygroscopicity of the adhesive layer 20 can be suitably reduced.
  • the resin material is not particularly limited, but may include a styrene resin composition, a vinyl acetate resin composition, a polyester resin composition, a polyethylene resin composition, a polypropylene resin composition, and an imide resin.
  • compositions thermoplastic resin compositions such as amide resin compositions, acrylic resin compositions, phenolic resin compositions, epoxy resin compositions, urethane resin compositions, melamine resin compositions, alkyd resins
  • a thermosetting resin composition such as a composition can be used.
  • the resin material may be one of these materials, or a combination of two or more.
  • the adhesive layer 20 may contain a conductive filler. Since the adhesive layer 20 contains the conductive filler, the adhesive layer 20 functions as a conductive adhesive layer. In this case, adhesive layer 20 functions as a conductive adhesive layer.
  • the conductive filler is not particularly limited, but may be fine metal particles, carbon nanotubes, carbon fibers, metal fibers, or the like.
  • the metal fine particles include, but are not limited to, silver powder, copper powder, nickel powder, solder powder, aluminum powder, silver-coated copper powder obtained by silver plating copper powder, and polymer fine particles. It may also be fine particles such as glass beads or the like coated with metal. Among these, from the viewpoint of economic efficiency, copper powder or silver-coated copper powder, which can be obtained at low cost, is preferable.
  • the shape of the conductive filler is not particularly limited, but can be appropriately selected from spherical, flat, flaky, dendrite, rod-like, fibrous, and the like.
  • the particle diameter (D 50 ) of the conductive filler is preferably 4.0 to 30.0 ⁇ m, more preferably 4.0 to 20.0 ⁇ m. When the particle diameter (D 50 ) of the conductive filler is within the above range, the adhesive layer 20 has good conductivity.
  • the content thereof is preferably 5 to 900 parts by weight, and preferably 10 to 800 parts by weight, based on 100 parts by weight of the resin. It is more preferable.
  • the conductive filler in an amount of 500 to 900 parts by weight per 100 parts by weight of the resin.
  • anisotropic conductivity it is preferable to mix the conductive filler in an amount of 5 parts by weight or more and less than 500 parts by weight based on 100 parts by weight of the resin.
  • the thickness of the adhesive layer 20 is preferably 5 to 50 ⁇ m, more preferably 5 to 30 ⁇ m. If the thickness of the adhesive layer is less than 5 ⁇ m, it will be thin and the adhesiveness will be reduced. When the thickness of the adhesive layer exceeds 50 ⁇ m, the adhesive layer becomes thick and it becomes difficult to miniaturize the electromagnetic shielding film.
  • the adhesive layer 20 contains, in addition to the resin and porous inorganic particles, a curing accelerator, a tackifier, an antioxidant, a pigment, a dye, a plasticizer, an ultraviolet absorber, and a quencher, if necessary. It may also contain foaming agents, leveling agents, fillers, flame retardants, viscosity modifiers, and the like.
  • the shielding layer 30 is preferably made of a metal layer.
  • the metal layer preferably contains at least one metal selected from the group consisting of copper, silver, gold, aluminum, nickel, tin, palladium, chromium, titanium, and zinc.
  • the metal layer may be made of an alloy of at least two selected from these groups. The shield layer 30 made of these metals can suitably shield electromagnetic waves.
  • the metal layer may be a rolled metal foil, a metal plating layer, or a metal vapor deposition layer.
  • the shielding layer 30 when the shielding layer 30 is made of a metal layer, its thickness is preferably 0.1 to 10 ⁇ m, more preferably 0.5 to 6 ⁇ m. If the thickness of the shield layer is less than 0.1 ⁇ m, the strength of the shield layer will be low because the shield layer will be too thin. Therefore, the bending resistance decreases. Furthermore, since it becomes difficult to sufficiently reflect and absorb electromagnetic waves, electromagnetic wave shielding characteristics tend to deteriorate. When the thickness of the shield layer exceeds 10 ⁇ m, the entire electromagnetic shielding film becomes thick and difficult to handle.
  • the insulating layer 40 is not particularly limited as long as it has sufficient insulation and can protect the shielding layer 30 and the adhesive layer 20.
  • it may be made of a thermoplastic resin composition, a thermosetting resin composition, an activated It is preferable that it is made of an energy ray curable composition or the like.
  • the above-mentioned thermoplastic resin compositions include, but are not particularly limited to, styrene resin compositions, vinyl acetate resin compositions, polyester resin compositions, polyethylene resin compositions, polypropylene resin compositions, and imide resin compositions. , acrylic resin compositions, and the like.
  • thermosetting resin composition examples include, but are not particularly limited to, phenolic resin compositions, epoxy resin compositions, urethane resin compositions, melamine resin compositions, alkyd resin compositions, and the like.
  • the active energy ray-curable composition is not particularly limited, but includes, for example, a polymerizable compound having at least two (meth)acryloyloxy groups in the molecule.
  • the insulating layer 40 may be composed of a single type of material, or may be composed of two or more types of materials.
  • the insulating layer 40 may contain a curing accelerator, a tackifier, an antioxidant, a pigment, a dye, a plasticizer, an ultraviolet absorber, an antifoaming agent, a leveling agent, a filler, a flame retardant, and a viscosity adjuster, as necessary. It may also contain agents, anti-blocking agents, etc.
  • the thickness of the insulating layer 40 is not particularly limited and can be appropriately set as necessary, but is preferably 1 to 15 ⁇ m, more preferably 3 to 10 ⁇ m. If the thickness of the insulating layer 40 is less than 1 ⁇ m, it is too thin and it becomes difficult to protect the shield layer 30 and the adhesive layer 20 sufficiently. When the thickness of the insulating layer 40 exceeds 15 ⁇ m, the electromagnetic shielding film 10 becomes difficult to bend because it is too thick, and the toughness of the insulating layer 40 decreases. Therefore, it becomes difficult to apply it to members that require bending resistance.
  • the insulating layer should just be formed as needed, and does not need to be formed.
  • FIG. 2 is a cross-sectional view schematically showing an example of a shield printed wiring board using the electromagnetic shielding film of the present invention.
  • the shield printed wiring board 1 shown in FIG. 2 consists of a printed wiring board 50 and an electromagnetic shielding film 10.
  • the printed wiring board 50 includes a base film 51, a printed circuit 52 placed on the base film 51, and a coverlay 53 placed so as to cover the printed circuit 52.
  • the printed circuit 52 includes a ground circuit 52a
  • the coverlay 53 has an opening 53a that exposes the ground circuit 52a.
  • the electromagnetic shielding film 10 is arranged on the printed wiring board 50 so that the coverlay 53 and the adhesive layer 20 are in contact with each other.
  • the adhesive layer 20 fills the opening 53a of the coverlay 53 and is in contact with the ground circuit 52a. With such a configuration, the shielding characteristics of the electromagnetic shielding film 10 can be improved.
  • Example 1 As the insulating layer, an insulating layer made of epoxy resin and having a thickness of 5 ⁇ m was prepared. Next, electrolytic plating was performed on the insulating layer so that a copper layer having a thickness of 2.0 ⁇ m was formed. Note that the copper layer functions as a shield layer.
  • a conductive adhesive according to Example 1 was prepared by mixing the following. Table 1 shows parameters such as the pore volume of the porous silica used. Next, the adhesive layer was coated on the metal layer to a thickness of 7 ⁇ m to produce the electromagnetic shielding film according to Example 1.
  • Electromagnetic shielding films according to Examples 2 to 9 and Comparative Examples 1 to 3 were produced in the same manner as in Example 1, except that the porous inorganic particles shown in Table 1 were used. Further, an electromagnetic shielding film according to Comparative Example 4 was produced in the same manner as in Example 1 except that porous inorganic particles were not used.
  • Shield printed wiring board 10 510 Electromagnetic shielding film 20, 520 Adhesive layer 30, 530 Shield layer 40, 540 Insulating layer 50 Printed wiring board 51 Base film 52 Printed circuit 52a Ground circuit 53 Coverlay 53a Opening 560 Volatile component

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  • Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
  • Laminated Bodies (AREA)

Abstract

Provided is an electromagnetic shield film in which the interlayer adhesion between an adhesive layer and a shield layer is unlikely to break down even upon heating with reflow etc. An electromagnetic shield film according to the present invention comprises an adhesive layer and a shield layer that is laminated on the adhesive layer, said electromagnetic shield film being characterized in that: the adhesive layer contains resin and porous inorganic particles; and the pore volume of the porous inorganic particles is more than 0.44 mL/g but not more than 1.80 mL/g.

Description

電磁波シールドフィルムelectromagnetic shielding film
本発明は、電磁波シールドフィルムに関する。 The present invention relates to an electromagnetic shielding film.
従来から、例えばフレキシブルプリント配線板（ＦＰＣ）などのプリント配線板に電磁波シールドフィルムを貼り付けて、外部からの電磁波をシールドすることが行われている。 2. Description of the Related Art Conventionally, electromagnetic waves from the outside have been shielded by attaching an electromagnetic wave shielding film to a printed wiring board such as a flexible printed wiring board (FPC).
電磁波シールドフィルムは、通常、接着剤層と、金属薄膜等からなるシールド層と、絶縁層とが順に積層された構成を有する。この電磁波シールドフィルムをプリント配線板に重ね合わせた状態で加熱プレスすることにより、電磁波シールドフィルムは接着剤層によってプリント配線板に接着されて、シールドプリント配線板が作製される。この接着後、はんだリフローによってシールドプリント配線板に部品が実装される。また、プリント配線板は、ベースフィルム上のプリントパターンが絶縁フィルムで被覆された構成となっている。 An electromagnetic shielding film usually has a structure in which an adhesive layer, a shielding layer made of a metal thin film, etc., and an insulating layer are laminated in this order. The electromagnetic shielding film is superimposed on the printed wiring board and hot-pressed, thereby adhering the electromagnetic shielding film to the printed wiring board with the adhesive layer, thereby producing a shielded printed wiring board. After this adhesion, the components are mounted on the shield printed wiring board by solder reflow. Further, the printed wiring board has a structure in which a printed pattern on a base film is covered with an insulating film.
このような電磁波シールドフィルムとして、特許文献１には、層厚が０．５μｍ～１２μｍの金属層と、異方導電性接着剤層とを積層状態で備えたことを特徴とするシールドフィルムが開示されている。 As such an electromagnetic shielding film, Patent Document 1 discloses a shielding film characterized by comprising a metal layer with a layer thickness of 0.5 μm to 12 μm and an anisotropically conductive adhesive layer in a laminated state. has been done.
国際公開第２０１３／０７７１０８号International Publication No. 2013/077108
このような電磁波シールドフィルムをプリント配線板に配置し、その後、リフロー等により部品実装を行うと、電磁波シールドフィルムの接着剤層と金属層との層間密着が破壊され、層間剥離してしまうという問題があった。 If such an electromagnetic shielding film is placed on a printed wiring board and then components are mounted by reflow etc., the interlayer adhesion between the adhesive layer and the metal layer of the electromagnetic shielding film is destroyed, resulting in delamination. was there.
上記層間剥離が生じる原因は、以下のメカニズムによるものと考えられている。
図３Ａ及び図３Ｂは、従来の電磁波シールドフィルムを用いてシールドプリント配線板を製造する場合に、接着剤層と金属層とが層間剥離するメカニズムを模式的に示す説明図である。
図３Ａに示すように、シールドプリント配線板を製造する際に、接着剤層５２０、金属層からなるシールド層５３０が順に積層された電磁波シールドフィルム５１０は、加熱プレスやはんだリフローにより加熱される。
この加熱により、電磁波シールドフィルム５１０の接着剤層５２０等から揮発成分（主に水分）５６０が発生し、接着剤層５２０とシールド層５３０との間に溜まることになる。 The cause of the above delamination is thought to be due to the following mechanism.
3A and 3B are explanatory diagrams schematically showing a mechanism in which an adhesive layer and a metal layer delaminate when manufacturing a shield printed wiring board using a conventional electromagnetic shielding film.
As shown in FIG. 3A, when manufacturing a shielded printed wiring board, an electromagnetic shielding film 510 in which an adhesive layer 520 and a shielding layer 530 made of a metal layer are sequentially laminated is heated by hot pressing or solder reflow.
Due to this heating, volatile components (mainly water) 560 are generated from the adhesive layer 520 and the like of the electromagnetic shielding film 510 and accumulate between the adhesive layer 520 and the shielding layer 530.
このような状態で、部品の実装のためにリフロー等の急激な加熱が行われると、図３Ｂに示すように、接着剤層５２０とシールド層５３０との間に溜まった揮発成分５６０が膨張することにより、接着剤層５２０とシールド層５３０との層間密着が破壊され、層間剥離が生じる。 In this state, when rapid heating such as reflow is performed to mount components, the volatile component 560 accumulated between the adhesive layer 520 and the shield layer 530 expands, as shown in FIG. 3B. As a result, the interlayer adhesion between the adhesive layer 520 and the shield layer 530 is broken, and delamination occurs.
本発明は、上記問題を解決するためになされた発明であり、本発明の目的は、リフロー等の加熱を受けたとしても、接着剤層とシールド層との層間密着が破壊されにくい電磁波シールドフィルムを提供することである。 The present invention has been made to solve the above problems, and an object of the present invention is to provide an electromagnetic shielding film in which the interlayer adhesion between the adhesive layer and the shielding layer is not easily destroyed even when subjected to heating such as reflow. The goal is to provide the following.
本発明者は、接着剤層とシールド層との間に揮発成分が溜まる原因が、電磁波シールドフィルムの保管時に接着剤層が空気中の水分等を吸収してしまうためであり、接着剤層の吸湿性を低くすることにより上記問題が解決できることを見出し、本発明に想到した。 The inventor believes that the reason why volatile components accumulate between the adhesive layer and the shield layer is that the adhesive layer absorbs moisture in the air when the electromagnetic shielding film is stored. It was discovered that the above problem could be solved by lowering the hygroscopicity, and the present invention was conceived.
すなわち、本発明の電磁波シールドフィルムは、接着剤層と、上記接着剤層の上に積層されたシールド層とを含む電磁波シールドフィルムであって、上記接着剤層は、樹脂と、多孔質無機粒子とを含み、上記多孔質無機粒子の細孔容積は、０．４４ｍＬ／ｇを超え、１．８０ｍＬ／ｇ以下であることを特徴とする。 That is, the electromagnetic wave shielding film of the present invention is an electromagnetic wave shielding film including an adhesive layer and a shielding layer laminated on the adhesive layer, the adhesive layer comprising a resin and porous inorganic particles. The porous inorganic particles have a pore volume of more than 0.44 mL/g and less than or equal to 1.80 mL/g.
本発明の電磁波シールドフィルムにおいて、多孔質無機粒子は充填剤として機能する。そのため、導電性接着剤の強度が高くなる。
また、後述するように、本発明の電磁波シールドフィルムにおいて、多孔質無機粒子は揮発成分を吸収しにくい。そのため、多孔質無機粒子がある部分では揮発成分が吸収されない。つまり、多孔質無機粒子を含むことにより、接着剤層全体の吸湿性が低下する。従って、本発明の電磁波シールドフィルムでは、リフロー等の加熱を受けたとしても、接着剤層とシールド層との層間密着が破壊されにくい。 In the electromagnetic shielding film of the present invention, the porous inorganic particles function as a filler. Therefore, the strength of the conductive adhesive increases.
Furthermore, as will be described later, in the electromagnetic shielding film of the present invention, the porous inorganic particles are difficult to absorb volatile components. Therefore, volatile components are not absorbed in the areas where the porous inorganic particles are present. In other words, the inclusion of porous inorganic particles reduces the hygroscopicity of the adhesive layer as a whole. Therefore, in the electromagnetic shielding film of the present invention, even when subjected to heating such as reflow, the interlayer adhesion between the adhesive layer and the shielding layer is unlikely to be destroyed.
本発明の電磁波シールドフィルムにおいて、多孔質無機粒子が揮発成分を吸収しにくい理由について説明する。
本発明の電磁波シールドフィルムにおいて、多孔質無機粒子の細孔容積は、０．４４ｍＬ／ｇを超え、１．８０ｍＬ／ｇ以下である。
多孔質無機粒子の細孔容積が上記範囲であると、多孔質無機粒子の細孔が適度な大きさとなり、多孔質無機粒子の中に水分等の揮発成分が溜まりにくい。
上記細孔容積が０．４４ｍＬ／ｇ以下であると、多孔質無機粒子に形成されている細孔が小さくなり、毛細管力を発揮しやすくなる。細孔が毛細管力を発揮すると、細孔内に揮発成分が溜まりやすくなり、多孔質無機粒子が揮発成分を吸収しやすくなる。そのため、接着剤層全体の吸湿性が上がりやすくなる。
上記細孔容積が１．８０ｍＬ／ｇを超えると、多孔質無機粒子に形成されている細孔が大きくなり、多孔質無機粒子が脆くなる。そのため、導電性接着剤の強度を向上させにくくなる。 The reason why porous inorganic particles are difficult to absorb volatile components in the electromagnetic shielding film of the present invention will be explained.
In the electromagnetic shielding film of the present invention, the pore volume of the porous inorganic particles is more than 0.44 mL/g and less than 1.80 mL/g.
When the pore volume of the porous inorganic particles is within the above range, the pores of the porous inorganic particles have an appropriate size, and volatile components such as moisture are difficult to accumulate in the porous inorganic particles.
When the pore volume is 0.44 mL/g or less, the pores formed in the porous inorganic particles become small, making it easier to exert capillary force. When the pores exert capillary force, volatile components tend to accumulate in the pores, and the porous inorganic particles tend to absorb the volatile components. Therefore, the hygroscopicity of the adhesive layer as a whole tends to increase.
When the pore volume exceeds 1.80 mL/g, the pores formed in the porous inorganic particles become large and the porous inorganic particles become brittle. Therefore, it becomes difficult to improve the strength of the conductive adhesive.
本発明の別の態様の電磁波シールドフィルムは、接着剤層と、上記接着剤層の上に積層されたシールド層とからなる電磁波シールドフィルムであって、上記接着剤層は、樹脂と、多孔質無機粒子とを含み、上記多孔質無機粒子の比表面積は、２８０ｍ２／ｇ以上、７００ｍ２／ｇ未満であることを特徴とする。 An electromagnetic shielding film according to another aspect of the present invention is an electromagnetic shielding film comprising an adhesive layer and a shielding layer laminated on the adhesive layer, the adhesive layer comprising a resin and a porous material. The porous inorganic particles have a specific surface area of 280 m 2 /g or more and less than 700 m 2 /g.
本発明の別の態様の電磁波シールドフィルムにおいて、多孔質無機粒子は充填剤として機能する。そのため、導電性接着剤の強度が高くなる。
また、後述するように、本発明の別の態様の電磁波シールドフィルムにおいて、多孔質無機粒子は揮発成分を吸収しにくい。そのため、多孔質無機粒子がある部分では揮発成分が吸収されない。つまり、多孔質無機粒子を含むことにより、接着剤層全体の吸湿性が低下する。従って、本発明の別の態様の電磁波シールドフィルムでは、リフロー等の加熱を受けたとしても、接着剤層とシールド層との層間密着が破壊されにくい。 In another embodiment of the electromagnetic shielding film of the present invention, porous inorganic particles function as a filler. Therefore, the strength of the conductive adhesive increases.
Further, as described later, in the electromagnetic shielding film of another embodiment of the present invention, the porous inorganic particles hardly absorb volatile components. Therefore, volatile components are not absorbed in the areas where the porous inorganic particles are present. In other words, the inclusion of porous inorganic particles reduces the hygroscopicity of the adhesive layer as a whole. Therefore, in the electromagnetic shielding film according to another aspect of the present invention, the interlayer adhesion between the adhesive layer and the shielding layer is unlikely to be destroyed even if it is subjected to heating such as reflow.
本発明の別の態様の電磁波シールドフィルムにおいて、多孔質無機粒子が揮発成分を吸収しにくい理由について説明する。
本発明の別の態様の電磁波シールドフィルムにおいて、多孔質無機粒子の比表面積は、２８０ｍ２／ｇ以上、７００ｍ２／ｇ未満である。
多孔質無機粒子の比表面積が上記範囲であると、多孔質無機粒子の細孔が適度な大きさとなり、多孔質無機粒子の中に水分等の揮発成分が溜まりにくい。
上記比表面積が２８０ｍ２／ｇ未満であると、多孔質無機粒子に形成されている細孔が大きくなり、多孔質無機粒子が脆くなる。そのため、接着剤層の強度を向上させにくくなる。
上記比表面積が７００ｍ２／ｇ以上であると、多孔質無機粒子に形成されている細孔が小さくなり、毛細管力を発揮しやすくなる。細孔が毛細管力を発揮すると、細孔内に揮発成分が溜まりやすくなり、多孔質無機粒子が揮発成分を吸収しやすくなる。そのため、接着剤層全体の吸湿性が上がりやすくなる。 The reason why porous inorganic particles are difficult to absorb volatile components in the electromagnetic shielding film of another embodiment of the present invention will be explained.
In another embodiment of the electromagnetic shielding film of the present invention, the porous inorganic particles have a specific surface area of 280 m 2 /g or more and less than 700 m 2 /g.
When the specific surface area of the porous inorganic particles is within the above range, the pores of the porous inorganic particles have an appropriate size, and volatile components such as moisture are difficult to accumulate in the porous inorganic particles.
When the specific surface area is less than 280 m 2 /g, the pores formed in the porous inorganic particles become large and the porous inorganic particles become brittle. Therefore, it becomes difficult to improve the strength of the adhesive layer.
When the specific surface area is 700 m 2 /g or more, the pores formed in the porous inorganic particles become small, making it easier to exert capillary force. When the pores exert capillary force, volatile components tend to accumulate in the pores, and the porous inorganic particles tend to absorb the volatile components. Therefore, the hygroscopicity of the adhesive layer as a whole tends to increase.
本発明のさらに別の態様の電磁波シールドフィルムは、接着剤層と、上記接着剤層の上に積層されたシールド層とからなる電磁波シールドフィルムであって、上記接着剤層は、樹脂と、多孔質無機粒子とを含み、上記多孔質無機粒子の細孔の平均細孔径は、２．５ｎｍを超え、２６ｎｍ以下であることを特徴とする。 An electromagnetic shielding film according to still another aspect of the present invention is an electromagnetic shielding film comprising an adhesive layer and a shielding layer laminated on the adhesive layer, the adhesive layer comprising a resin and a porous The porous inorganic particles have an average pore diameter of more than 2.5 nm and less than 26 nm.
本発明のさらに別の態様の電磁波シールドフィルムにおいて、多孔質無機粒子は充填剤として機能する。そのため、導電性接着剤の強度が高くなる。
また、後述するように、本発明のさらに別の態様の電磁波シールドフィルムにおいて、多孔質無機粒子は揮発成分を吸収しにくい。そのため、多孔質無機粒子がある部分では揮発成分が吸収されない。つまり、多孔質無機粒子を含むことにより、接着剤層全体の吸湿性が低下する。従って、本発明のさらに別の態様の電磁波シールドフィルムでは、リフロー等の加熱を受けたとしても、接着剤層とシールド層との層間密着が破壊されにくい。 In yet another embodiment of the electromagnetic shielding film of the present invention, porous inorganic particles function as a filler. Therefore, the strength of the conductive adhesive increases.
Furthermore, as will be described later, in the electromagnetic shielding film of yet another embodiment of the present invention, the porous inorganic particles are difficult to absorb volatile components. Therefore, volatile components are not absorbed in the areas where the porous inorganic particles are present. In other words, the inclusion of porous inorganic particles reduces the hygroscopicity of the adhesive layer as a whole. Therefore, in the electromagnetic shielding film of yet another aspect of the present invention, the interlayer adhesion between the adhesive layer and the shielding layer is unlikely to be destroyed even when subjected to heating such as reflow.
本発明のさらに別の態様の電磁波シールドフィルムにおいて、多孔質無機粒子が揮発成分を吸収しにくい理由について説明する。
本発明のさらに別の態様の電磁波シールドフィルムにおいて、多孔質無機粒子の細孔の平均細孔径は、２．５ｎｍを超え、２６ｎｍ以下である。
多孔質無機粒子の細孔の平均細孔径が上記範囲であると、多孔質無機粒子の細孔が適度な大きさとなり、多孔質無機粒子の中に水分等の揮発成分が溜まりにくい。
上記細孔の平均細孔径が２．５ｎｍ以下であると、多孔質無機粒子に形成されている細孔が小さくなり、毛細管力を発揮しやすくなる。細孔が毛細管力を発揮すると、細孔内に揮発成分が溜まりやすくなり、多孔質無機粒子が揮発成分を吸収しやすくなる。そのため、接着剤層全体の吸湿性が上がりやすくなる。
上記細孔の平均細孔径が２６ｎｍを超えると、多孔質無機粒子に形成されている細孔が大きくなり、多孔質無機粒子が脆くなる。そのため、導電性接着剤の強度を向上させにくくなる。 The reason why porous inorganic particles are difficult to absorb volatile components in the electromagnetic shielding film of yet another embodiment of the present invention will be explained.
In yet another embodiment of the electromagnetic shielding film of the present invention, the average pore diameter of the pores of the porous inorganic particles is greater than 2.5 nm and less than or equal to 26 nm.
When the average pore diameter of the pores of the porous inorganic particles is within the above range, the pores of the porous inorganic particles have an appropriate size, and volatile components such as moisture are difficult to accumulate in the porous inorganic particles.
When the average pore diameter of the pores is 2.5 nm or less, the pores formed in the porous inorganic particles become small, making it easier to exert capillary force. When the pores exert capillary force, volatile components tend to accumulate in the pores, and the porous inorganic particles tend to absorb the volatile components. Therefore, the hygroscopicity of the adhesive layer as a whole tends to increase.
When the average pore diameter of the pores exceeds 26 nm, the pores formed in the porous inorganic particles become large and the porous inorganic particles become brittle. Therefore, it becomes difficult to improve the strength of the conductive adhesive.
本発明の電磁波シールドフィルムでは、上記多孔質無機粒子のＤＢＡ値は、５０ｍｅｑ／ｋｇ以上、２００ｍｅｑ／ｋｇ未満であることが好ましい。
ＤＢＡ値が、５０ｍｅｑ／ｋｇ未満の多孔質無機粒子は製造することが困難である。
ＤＢＡ値が、２００ｍｅｑ／ｋｇ未満であると、疎水性が高くなり、細孔内に水分が溜まりにくくなる。
なお、本明細書において「ＤＢＡ値」とは、ジ－ｎ－ブチルアミンのトルエン溶液で多孔質無機粒子を処理した際のジ－ｎ－ブチルアミン吸着量（粒子１ｋｇに対するジ－ｎ－ブチルアミンの吸着量）を意味しており、この吸着量は、公知の滴定試験等により測定することができる。 In the electromagnetic shielding film of the present invention, the porous inorganic particles preferably have a DBA value of 50 meq/kg or more and less than 200 meq/kg.
It is difficult to produce porous inorganic particles with a DBA value of less than 50 meq/kg.
When the DBA value is less than 200 meq/kg, hydrophobicity becomes high and water becomes difficult to accumulate in the pores.
In this specification, "DBA value" refers to the amount of di-n-butylamine adsorbed when porous inorganic particles are treated with a toluene solution of di-n-butylamine (the amount of di-n-butylamine adsorbed per 1 kg of particles). ), and this adsorption amount can be measured by a known titration test or the like.
本発明の電磁波シールドフィルムでは、上記多孔質無機粒子の粒子径（Ｄ５０）は、１．０～２０．０μｍであることが好ましい。
多孔質無機粒子の粒子径（Ｄ５０）が、１．０μｍ未満である場合、多孔質無機粒子に適度な大きさの細孔を形成しにくくなる。
多孔質無機粒子の粒子径（Ｄ５０）が、２０．０μｍを超えると、接着剤層が厚くなり、電磁波シールドフィルムを小型化しにくくなる。また、多孔質無機粒子が接着剤層から突出しやすくなり、接着剤層が後述のグランド回路と接触したときの接続抵抗値が高くなりやすくなる。
なお、多孔質無機粒子の粒子径（Ｄ５０）は、レーザー回折式粒度分布測定装置（株式会社島津製作所製　ＳＡＬＤ－２２００）にて測定することができる。
また、後述する導電性フィラーの粒子径（Ｄ５０）の測定方法も同様である。 In the electromagnetic shielding film of the present invention, the particle diameter (D 50 ) of the porous inorganic particles is preferably 1.0 to 20.0 μm.
When the particle diameter (D 50 ) of the porous inorganic particles is less than 1.0 μm, it becomes difficult to form pores of an appropriate size in the porous inorganic particles.
When the particle diameter (D 50 ) of the porous inorganic particles exceeds 20.0 μm, the adhesive layer becomes thick and it becomes difficult to miniaturize the electromagnetic shielding film. In addition, the porous inorganic particles tend to protrude from the adhesive layer, and the connection resistance value when the adhesive layer comes into contact with a ground circuit, which will be described later, tends to increase.
The particle diameter (D 50 ) of the porous inorganic particles can be measured using a laser diffraction particle size distribution analyzer (SALD-2200, manufactured by Shimadzu Corporation).
Further, the method for measuring the particle diameter (D 50 ) of the conductive filler described later is also the same.
本発明の電磁波シールドフィルムでは、上記接着剤層は導電性フィラーを含み、上記導電性フィラーの粒子径（Ｄ５０）は、４．０～３０．０μｍであることが好ましい。
接着剤層が導電性フィラーを含むことにより、接着剤層が導電性接着剤層として機能する。また、導電性フィラーの粒子径（Ｄ５０）が上記範囲であると、接着剤層の導電性が良好になる。 In the electromagnetic shielding film of the present invention, the adhesive layer preferably contains a conductive filler, and the conductive filler preferably has a particle diameter (D 50 ) of 4.0 to 30.0 μm.
Since the adhesive layer contains the conductive filler, the adhesive layer functions as a conductive adhesive layer. Moreover, when the particle diameter (D 50 ) of the conductive filler is within the above range, the conductivity of the adhesive layer becomes good.
本発明の電磁波シールドフィルムでは、上記接着剤層の厚さは、５～５０μｍであることが好ましい。
接着剤層の厚さが、５μｍ未満であると、薄いので接着性が低下する。
接着剤層の厚さが、５０μｍを超えると、接着剤層が厚くなり、電磁波シールドフィルムを小型化しにくくなる。 In the electromagnetic shielding film of the present invention, the thickness of the adhesive layer is preferably 5 to 50 μm.
If the thickness of the adhesive layer is less than 5 μm, it will be thin and the adhesiveness will be reduced.
When the thickness of the adhesive layer exceeds 50 μm, the adhesive layer becomes thick and it becomes difficult to miniaturize the electromagnetic shielding film.
本発明の電磁波シールドフィルムでは、上記接着剤層は、上記樹脂１００重量部に対し、上記多孔質無機粒子を１～１００重量部含むことが好ましい。
多孔質無機粒子の含有量が上記範囲であると、接着剤層の吸湿性を好適に低下させることができる。 In the electromagnetic shielding film of the present invention, the adhesive layer preferably contains 1 to 100 parts by weight of the porous inorganic particles based on 100 parts by weight of the resin.
When the content of the porous inorganic particles is within the above range, the hygroscopicity of the adhesive layer can be suitably reduced.
本発明の電磁波シールドフィルムでは、上記シールド層の上に、さらに絶縁層が積層されていることが好ましい。
絶縁層が形成されていることで、シールド層及び接着剤層を保護することができる。また絶縁層が存在することにより、シールド層と他の導電部材とが接触することを防ぐことができる。 In the electromagnetic shielding film of the present invention, it is preferable that an insulating layer is further laminated on the shielding layer.
By forming the insulating layer, the shield layer and the adhesive layer can be protected. Furthermore, the presence of the insulating layer can prevent the shield layer from coming into contact with other conductive members.
本発明によれば、リフロー等の加熱を受けたとしても、接着剤層とシールド層との層間密着が破壊されにくい電磁波シールドフィルムを提供することができる。 According to the present invention, it is possible to provide an electromagnetic shielding film in which the interlayer adhesion between the adhesive layer and the shielding layer is not easily destroyed even when subjected to heating such as reflow.
図１は、本発明の電磁波シールドフィルムの一例を模式的に示す断面図である。FIG. 1 is a cross-sectional view schematically showing an example of the electromagnetic shielding film of the present invention. 図２は、本発明の電磁波シールドフィルムが用いられたシールドプリント配線板の一例を模式的に示す断面図である。FIG. 2 is a cross-sectional view schematically showing an example of a shield printed wiring board using the electromagnetic shielding film of the present invention. 図３Ａは、従来の電磁波シールドフィルムを用いてシールドプリント配線板を製造する場合に、接着剤層と金属層とが層間剥離するメカニズムを模式的に示す説明図である。FIG. 3A is an explanatory diagram schematically showing a mechanism in which an adhesive layer and a metal layer delaminate when manufacturing a shield printed wiring board using a conventional electromagnetic shielding film. 図３Ｂは、従来の電磁波シールドフィルムを用いてシールドプリント配線板を製造する場合に、接着剤層と金属層とが層間剥離するメカニズムを模式的に示す説明図である。FIG. 3B is an explanatory diagram schematically showing a mechanism in which an adhesive layer and a metal layer delaminate when manufacturing a shield printed wiring board using a conventional electromagnetic shielding film.
以下、本発明の電磁波シールドフィルムについて具体的に説明する。しかしながら、本発明は、以下の実施形態に限定されるものではなく、本発明の要旨を変更しない範囲において適宜変更して適用することができる。 Hereinafter, the electromagnetic shielding film of the present invention will be specifically explained. However, the present invention is not limited to the following embodiments, and can be modified and applied as appropriate without changing the gist of the present invention.
図１は、本発明の電磁波シールドフィルムの一例を模式的に示す断面図である。
図１に示す電磁波シールドフィルム１０は、接着剤層２０と、接着剤層２０の上に積層されたシールド層３０と、シールド層３０の上にさらに絶縁層４０が積層されている。
そして、接着剤層２０は、樹脂と、多孔質無機粒子とを含む。 FIG. 1 is a cross-sectional view schematically showing an example of the electromagnetic shielding film of the present invention.
The electromagnetic shielding film 10 shown in FIG. 1 includes an adhesive layer 20, a shielding layer 30 laminated on the adhesive layer 20, and an insulating layer 40 further laminated on the shielding layer 30.
The adhesive layer 20 includes resin and porous inorganic particles.
電磁波シールドフィルム１０において、多孔質無機粒子は充填剤として機能する。そのため、導電性接着剤の強度が高くなる。 In the electromagnetic shielding film 10, the porous inorganic particles function as a filler. Therefore, the strength of the conductive adhesive increases.
電磁波シールドフィルム１０において、多孔質無機粒子は、少なくとも以下の特徴を有する。
すなわち、多孔質無機粒子は、多孔質無機粒子の細孔容積は、０．４４ｍＬ／ｇを超え、１．８０ｍＬ／ｇ以下であるという特徴、多孔質無機粒子の比表面積は、２８０ｍ２／ｇ以上、７００ｍ２／ｇ未満であるという特徴、及び、多孔質無機粒子の細孔の平均細孔径は、２．５ｎｍを超え、２６ｎｍ以下であるという特徴のうち、少なくとも一つの特徴を有する。
多孔質無機粒子がこのような特徴を有するので、多孔質無機粒子は揮発成分を吸収しにくい。そのため、多孔質無機粒子がある部分では揮発成分が吸収されない。つまり、多孔質無機粒子を含むことにより、接着剤層２０全体の吸湿性が低下する。従って、電磁波シールドフィルム１０では、リフロー等の加熱を受けたとしても、接着剤層２０とシールド層３０との層間密着が破壊されにくい。 In the electromagnetic shielding film 10, the porous inorganic particles have at least the following characteristics.
That is, the porous inorganic particles are characterized in that the pore volume of the porous inorganic particles is more than 0.44 mL/g and less than or equal to 1.80 mL/g, and the specific surface area of the porous inorganic particles is 280 m 2 /g. The porous inorganic particles have at least one of the characteristics that the diameter is less than 700 m 2 /g and the average pore diameter of the pores of the porous inorganic particles is more than 2.5 nm and less than 26 nm.
Because porous inorganic particles have such characteristics, it is difficult for porous inorganic particles to absorb volatile components. Therefore, volatile components are not absorbed in the areas where the porous inorganic particles are present. That is, by including porous inorganic particles, the hygroscopicity of the entire adhesive layer 20 is reduced. Therefore, in the electromagnetic shielding film 10, the interlayer adhesion between the adhesive layer 20 and the shielding layer 30 is unlikely to be destroyed even if it is subjected to heating such as reflow.
多孔質無機粒子が上記特徴を有すると、多孔質無機粒子が揮発成分を吸収しにくくなる理由について以下に説明する。 The reason why the porous inorganic particles have the above characteristics makes it difficult for the porous inorganic particles to absorb volatile components will be explained below.
多孔質無機粒子の細孔容積が、０．４４ｍＬ／ｇを超え、１．８０ｍＬ／ｇ以下であると、多孔質無機粒子の細孔が適度な大きさとなり、多孔質無機粒子の中に水分等の揮発成分が溜まりにくい。
上記細孔容積が０．４４ｍＬ／ｇ以下であると、多孔質無機粒子に形成されている細孔が小さくなり、毛細管力を発揮しやすくなる。細孔が毛細管力を発揮すると、細孔内に揮発成分が溜まりやすくなり、多孔質無機粒子が揮発成分を吸収しやすくなる。そのため、接着剤層全体の吸湿性が上がりやすくなる。
上記細孔容積が１．８０ｍＬ／ｇを超えると、多孔質無機粒子に形成されている細孔が大きくなり、多孔質無機粒子が脆くなる。そのため、導電性接着剤の強度を向上させにくくなる。
なお、多孔質無機粒子の細孔容積は、０．８０ｍＬ／ｇ以上、１．８０ｍＬ／ｇ以下であることが好ましく、１．００ｍＬ／ｇ以上、１．８０ｍＬ／ｇ以下であることがより好ましく、１．６０ｍＬ／ｇ以上、１．８０ｍＬ／ｇ以下であることがより好ましい。
上記多孔質無機粒子の細孔容積は、元素分析装置：Ｖａｒｉ　ＥＬ　ＩＩＩ（Ｅｌｅｍｅｎｔａｒ社製）を用いて窒素吸着法により測定することができる。また、後述の、比表面積、及び、平均細孔径の測定方法も同様である。 When the pore volume of the porous inorganic particles is more than 0.44 mL/g and less than 1.80 mL/g, the pores of the porous inorganic particles have an appropriate size, and moisture is trapped in the porous inorganic particles. It is difficult for volatile components such as
When the pore volume is 0.44 mL/g or less, the pores formed in the porous inorganic particles become small, making it easier to exert capillary force. When the pores exert capillary force, volatile components tend to accumulate in the pores, and the porous inorganic particles tend to absorb the volatile components. Therefore, the hygroscopicity of the adhesive layer as a whole tends to increase.
When the pore volume exceeds 1.80 mL/g, the pores formed in the porous inorganic particles become large and the porous inorganic particles become brittle. Therefore, it becomes difficult to improve the strength of the conductive adhesive.
Note that the pore volume of the porous inorganic particles is preferably 0.80 mL/g or more and 1.80 mL/g or less, more preferably 1.00 mL/g or more and 1.80 mL/g or less. , more preferably 1.60 mL/g or more and 1.80 mL/g or less.
The pore volume of the porous inorganic particles can be measured by a nitrogen adsorption method using an elemental analyzer: Vari EL III (manufactured by Elementar). Further, the methods for measuring the specific surface area and average pore diameter, which will be described later, are also the same.
多孔質無機粒子の比表面積が、２８０ｍ２／ｇ以上、７００ｍ２／ｇ未満である場合、多孔質無機粒子の細孔が適度な大きさとなり、多孔質無機粒子の中に水分等の揮発成分が溜まりにくい。
上記比表面積が２８０ｍ２／ｇ未満であると、多孔質無機粒子に形成されている細孔が大きくなり、多孔質無機粒子が脆くなる。そのため、接着剤層の強度を向上させにくくなる。
上記比表面積が７００ｍ２／ｇ以上であると、多孔質無機粒子に形成されている細孔が小さくなり、毛細管力を発揮しやすくなる。細孔が毛細管力を発揮すると、細孔内に揮発成分が溜まりやすくなり、多孔質無機粒子が揮発成分を吸収しやすくなる。そのため、接着剤層全体の吸湿性が上がりやすくなる。
なお、多孔質無機粒子の比表面積は、２８０ｍ２／ｇ以上、５００ｍ２／ｇ以下であることが好ましく、２８０ｍ２／ｇ以上、４８０ｍ２／ｇ以下であることがより好ましく、２８０ｍ２／ｇ以上、３００ｍ２／ｇ以下であることがさらに好ましい。 When the specific surface area of the porous inorganic particles is 280 m 2 /g or more and less than 700 m 2 /g, the pores of the porous inorganic particles have an appropriate size, and volatile components such as moisture are contained in the porous inorganic particles. is difficult to accumulate.
When the specific surface area is less than 280 m 2 /g, the pores formed in the porous inorganic particles become large and the porous inorganic particles become brittle. Therefore, it becomes difficult to improve the strength of the adhesive layer.
When the specific surface area is 700 m 2 /g or more, the pores formed in the porous inorganic particles become small, making it easier to exert capillary force. When the pores exert capillary force, volatile components tend to accumulate in the pores, and the porous inorganic particles tend to absorb the volatile components. Therefore, the hygroscopicity of the adhesive layer as a whole tends to increase.
The specific surface area of the porous inorganic particles is preferably 280 m 2 /g or more and 500 m 2 /g or less, more preferably 280 m 2 / g or more and 480 m 2 /g or less, and 280 m 2 /g. Above, it is more preferable that it is 300 m 2 /g or less.
多孔質無機粒子の細孔の平均細孔径が、２．５ｎｍを超え、２６ｎｍ以下であると、多孔質無機粒子の細孔が適度な大きさとなり、多孔質無機粒子の中に水分等の揮発成分が溜まりにくい。
上記細孔の平均細孔径が２．５ｎｍ以下であると、多孔質無機粒子に形成されている細孔が小さくなり、毛細管力を発揮しやすくなる。細孔が毛細管力を発揮すると、細孔内に揮発成分が溜まりやすくなり、多孔質無機粒子が揮発成分を吸収しやすくなる。そのため、接着剤層全体の吸湿性が上がりやすくなる。
上記細孔の平均細孔径が２６ｎｍを超えると、多孔質無機粒子に形成されている細孔が大きくなり、多孔質無機粒子が脆くなる。そのため、導電性接着剤の強度を向上させにくくなる。
なお、多孔質無機粒子の細孔の平均細孔径は、７ｎｍ以上、２６ｎｍ以下であることが好ましく、１１ｎｍ以上、２６ｎｍ以下であることがより好ましく、２１ｎｍ以上、２６ｎｍ以下であることがさらに好ましい。 If the average pore diameter of the pores of the porous inorganic particles is more than 2.5 nm and less than 26 nm, the pores of the porous inorganic particles will have an appropriate size, and moisture etc. will not evaporate into the porous inorganic particles. Ingredients do not accumulate easily.
When the average pore diameter of the pores is 2.5 nm or less, the pores formed in the porous inorganic particles become small, making it easier to exert capillary force. When the pores exert capillary force, volatile components tend to accumulate in the pores, and the porous inorganic particles tend to absorb the volatile components. Therefore, the hygroscopicity of the adhesive layer as a whole tends to increase.
When the average pore diameter of the pores exceeds 26 nm, the pores formed in the porous inorganic particles become large and the porous inorganic particles become brittle. Therefore, it becomes difficult to improve the strength of the conductive adhesive.
The average pore diameter of the pores of the porous inorganic particles is preferably 7 nm or more and 26 nm or less, more preferably 11 nm or more and 26 nm or less, and even more preferably 21 nm or more and 26 nm or less.
電磁波シールドフィルム１０では、上記多孔質無機粒子のＤＢＡ値は、５０ｍｅｑ／ｋｇ以上、２００ｍｅｑ／ｋｇ未満であることが好ましく、５０～１７５ｍｅｑ／ｋｇであることがより好ましい。
ＤＢＡ値が、５０ｍｅｑ／ｋｇ未満の多孔質無機粒子は製造することが困難である。
ＤＢＡ値が、２００ｍｅｑ／ｋｇ未満であると、疎水性が高くなり、細孔内に水分が溜まりにくくなる。 In the electromagnetic shielding film 10, the DBA value of the porous inorganic particles is preferably 50 meq/kg or more and less than 200 meq/kg, more preferably 50 to 175 meq/kg.
It is difficult to produce porous inorganic particles with a DBA value of less than 50 meq/kg.
When the DBA value is less than 200 meq/kg, hydrophobicity becomes high and water becomes difficult to accumulate in the pores.
電磁波シールドフィルム１０では、多孔質無機粒子の粒子径（Ｄ５０）は、１．０～２０．０μｍであることが好ましく、２．５μｍを超え、１５．０μｍ未満であることがより好ましく、２．５μｍを超え、１０．０μｍ未満であることがさらにより好ましい。
多孔質無機粒子の粒子径（Ｄ５０）が、１．０μｍ未満である場合、多孔質無機粒子に適度な大きさの細孔を形成しにくくなる。
多孔質無機粒子の粒子径（Ｄ５０）が、２０．０μｍを超えると、接着剤層が厚くなり、電磁波シールドフィルムを小型化しにくくなる。また、多孔質無機粒子が接着剤層から突出しやすくなり、接着剤層が後述のグランド回路と接触したときの接続抵抗値が高くなりやすくなる。 In the electromagnetic shielding film 10, the particle diameter (D 50 ) of the porous inorganic particles is preferably 1.0 to 20.0 μm, more preferably more than 2.5 μm and less than 15.0 μm, and 2. Even more preferably, it is greater than .5 μm and less than 10.0 μm.
When the particle diameter (D 50 ) of the porous inorganic particles is less than 1.0 μm, it becomes difficult to form pores of an appropriate size in the porous inorganic particles.
When the particle diameter (D 50 ) of the porous inorganic particles exceeds 20.0 μm, the adhesive layer becomes thick and it becomes difficult to miniaturize the electromagnetic shielding film. In addition, the porous inorganic particles tend to protrude from the adhesive layer, and the connection resistance value when the adhesive layer comes into contact with a ground circuit, which will be described later, tends to increase.
電磁波シールドフィルムにおいて、多孔質無機粒子の種類は特に限定されないが、シリカ、アルミナ等を用いることができる。
これらの中では、シリカが好ましく、疎水化シリカであることがより好ましい。 In the electromagnetic shielding film, the type of porous inorganic particles is not particularly limited, but silica, alumina, etc. can be used.
Among these, silica is preferred, and hydrophobized silica is more preferred.
電磁波シールドフィルム１０において、接着剤層２０は、樹脂１００重量部に対し、多孔質無機粒子を１～１００重量部含むことが好ましく、１～５０重量部含むことがより好ましく、１～３０重量部含むことがさらに好ましい。
多孔質無機粒子の含有量が上記範囲であると、接着剤層２０の吸湿性を好適に低下させることができる。 In the electromagnetic shielding film 10, the adhesive layer 20 preferably contains 1 to 100 parts by weight, more preferably 1 to 50 parts by weight, and 1 to 30 parts by weight of porous inorganic particles based on 100 parts by weight of the resin. It is even more preferable to include.
When the content of the porous inorganic particles is within the above range, the hygroscopicity of the adhesive layer 20 can be suitably reduced.
電磁波シールドフィルム１０において、樹脂の材料としては特に限定されないが、スチレン系樹脂組成物、酢酸ビニル系樹脂組成物、ポリエステル系樹脂組成物、ポリエチレン系樹脂組成物、ポリプロピレン系樹脂組成物、イミド系樹脂組成物、アミド系樹脂組成物、アクリル系樹脂組成物等の熱可塑性樹脂組成物や、フェノール系樹脂組成物、エポキシ系樹脂組成物、ウレタン系樹脂組成物、メラミン系樹脂組成物、アルキッド系樹脂組成物等の熱硬化性樹脂組成物等を用いることができる。
樹脂の材料はこれらの１種単独であってもよく、２種以上の組み合わせであってもよい。 In the electromagnetic wave shielding film 10, the resin material is not particularly limited, but may include a styrene resin composition, a vinyl acetate resin composition, a polyester resin composition, a polyethylene resin composition, a polypropylene resin composition, and an imide resin. compositions, thermoplastic resin compositions such as amide resin compositions, acrylic resin compositions, phenolic resin compositions, epoxy resin compositions, urethane resin compositions, melamine resin compositions, alkyd resins A thermosetting resin composition such as a composition can be used.
The resin material may be one of these materials, or a combination of two or more.
電磁波シールドフィルム１０では、接着剤層２０は、導電性フィラーを含んでいてもよい。
接着剤層２０が導電性フィラーを含むことにより、接着剤層２０が導電性接着剤層として機能する。この場合、接着剤層２０は、導電性接着剤層として機能する。
導電性フィラーとしては、特に限定されないが、金属微粒子、カーボンナノチューブ、炭素繊維、金属繊維等であってもよい。 In the electromagnetic shielding film 10, the adhesive layer 20 may contain a conductive filler.
Since the adhesive layer 20 contains the conductive filler, the adhesive layer 20 functions as a conductive adhesive layer. In this case, adhesive layer 20 functions as a conductive adhesive layer.
The conductive filler is not particularly limited, but may be fine metal particles, carbon nanotubes, carbon fibers, metal fibers, or the like.
導電性フィラーが金属微粒子である場合、金属微粒子としては、特に限定されないが、銀粉、銅粉、ニッケル粉、ハンダ粉、アルミニウム粉、銅粉に銀めっきを施した銀コート銅粉、高分子微粒子やガラスビーズ等を金属で被覆した微粒子等であってもよい。
これらの中では、経済性の観点から、安価に入手できる銅粉又は銀コート銅粉であることが好ましい。 When the conductive filler is metal fine particles, the metal fine particles include, but are not limited to, silver powder, copper powder, nickel powder, solder powder, aluminum powder, silver-coated copper powder obtained by silver plating copper powder, and polymer fine particles. It may also be fine particles such as glass beads or the like coated with metal.
Among these, from the viewpoint of economic efficiency, copper powder or silver-coated copper powder, which can be obtained at low cost, is preferable.
導電性フィラーの形状は、特に限定されないが、球状、扁平状、リン片状、デンドライト状、棒状、繊維状等から適宜選択することができる。 The shape of the conductive filler is not particularly limited, but can be appropriately selected from spherical, flat, flaky, dendrite, rod-like, fibrous, and the like.
導電性フィラーの粒子径（Ｄ５０）は、４．０～３０．０μｍであることが好ましく、４．０～２０．０μｍであることがより好ましい。
導電性フィラーの粒子径（Ｄ５０）が上記範囲であると、接着剤層２０の導電性が良好になる。 The particle diameter (D 50 ) of the conductive filler is preferably 4.0 to 30.0 μm, more preferably 4.0 to 20.0 μm.
When the particle diameter (D 50 ) of the conductive filler is within the above range, the adhesive layer 20 has good conductivity.
電磁波シールドフィルム１０では、接着剤層２０が導電性フィラーを含む場合、その含有量は、樹脂１００重量部に対し、導電性フィラーを５～９００重量部含むことが好ましく、１０～８００重量部含むことがより好ましい。
なお、接着剤層２０に等方導電性を付与したい場合には、樹脂１００重量部に対し、導電性フィラーを５００～９００重量部含むように配合することが好ましい。
また、接着剤層２０に異方導電性を付与したい場合には、樹脂１００重量部に対し、導電性フィラーを５重量部以上、５００重量部未満含むように配合することが好ましい。 In the electromagnetic shielding film 10, when the adhesive layer 20 contains a conductive filler, the content thereof is preferably 5 to 900 parts by weight, and preferably 10 to 800 parts by weight, based on 100 parts by weight of the resin. It is more preferable.
Note that if it is desired to impart isotropic conductivity to the adhesive layer 20, it is preferable to mix the conductive filler in an amount of 500 to 900 parts by weight per 100 parts by weight of the resin.
Moreover, when it is desired to impart anisotropic conductivity to the adhesive layer 20, it is preferable to mix the conductive filler in an amount of 5 parts by weight or more and less than 500 parts by weight based on 100 parts by weight of the resin.
電磁波シールドフィルム１０では、接着剤層２０の厚さは、５～５０μｍであることが好ましく、５～３０μｍであることがより好ましい。
接着剤層の厚さが、５μｍ未満であると、薄いので接着性が低下する。
接着剤層の厚さが、５０μｍを超えると、接着剤層が厚くなり、電磁波シールドフィルムを小型化しにくくなる。 In the electromagnetic shielding film 10, the thickness of the adhesive layer 20 is preferably 5 to 50 μm, more preferably 5 to 30 μm.
If the thickness of the adhesive layer is less than 5 μm, it will be thin and the adhesiveness will be reduced.
When the thickness of the adhesive layer exceeds 50 μm, the adhesive layer becomes thick and it becomes difficult to miniaturize the electromagnetic shielding film.
電磁波シールドフィルム１０では、接着剤層２０は、樹脂、多孔質無機粒子以外に、必要に応じて硬化促進剤、粘着性付与剤、酸化防止剤、顔料、染料、可塑剤、紫外線吸収剤、消泡剤、レベリング剤、充填剤、難燃剤、粘度調節剤等を含んでいてもよい。 In the electromagnetic shielding film 10, the adhesive layer 20 contains, in addition to the resin and porous inorganic particles, a curing accelerator, a tackifier, an antioxidant, a pigment, a dye, a plasticizer, an ultraviolet absorber, and a quencher, if necessary. It may also contain foaming agents, leveling agents, fillers, flame retardants, viscosity modifiers, and the like.
電磁波シールドフィルム１０では、シールド層３０は、金属層からなることが好ましい。
また、金属層は、銅、銀、金、アルミニウム、ニッケル、錫、パラジウム、クロム、チタン及び亜鉛からなる群から選択される少なくとも１種の金属を含むことが好ましい。また、金属層は、これらの群から選択される少なくとも２種の合金からなっていてもよい。
これらの金属からなるシールド層３０は、電磁波を好適にシールドすることができる。 In the electromagnetic shielding film 10, the shielding layer 30 is preferably made of a metal layer.
Further, the metal layer preferably contains at least one metal selected from the group consisting of copper, silver, gold, aluminum, nickel, tin, palladium, chromium, titanium, and zinc. Furthermore, the metal layer may be made of an alloy of at least two selected from these groups.
The shield layer 30 made of these metals can suitably shield electromagnetic waves.
電磁波シールドフィルム１０では、シールド層３０が金属層からなる場合、金属層は、圧延金属箔であってもよく、金属めっき層であってもよく、金属蒸着層であってもよい。 In the electromagnetic shielding film 10, when the shielding layer 30 is made of a metal layer, the metal layer may be a rolled metal foil, a metal plating layer, or a metal vapor deposition layer.
電磁波シールドフィルム１０では、シールド層３０が金属層からなる場合、その厚さは、０．１～１０μｍであることが好ましく、０．５～６μｍであることがより好ましい。
シールド層の厚さが０．１μｍ未満であると、シールド層が薄すぎるためシールド層の強度が低くなる。そのため、耐屈曲性が低下する。また、電磁波を充分に反射及び吸収しにくくなるので電磁波シールド特性が低下しやすくなる。
シールド層の厚さが１０μｍを超えると、電磁波シールドフィルム全体が厚くなり扱いにくくなる。 In the electromagnetic shielding film 10, when the shielding layer 30 is made of a metal layer, its thickness is preferably 0.1 to 10 μm, more preferably 0.5 to 6 μm.
If the thickness of the shield layer is less than 0.1 μm, the strength of the shield layer will be low because the shield layer will be too thin. Therefore, the bending resistance decreases. Furthermore, since it becomes difficult to sufficiently reflect and absorb electromagnetic waves, electromagnetic wave shielding characteristics tend to deteriorate.
When the thickness of the shield layer exceeds 10 μm, the entire electromagnetic shielding film becomes thick and difficult to handle.
電磁波シールドフィルム１０では、絶縁層４０は充分な絶縁性を有し、シールド層３０及び接着剤層２０を保護できれば特に限定されないが、例えば、熱可塑性樹脂組成物、熱硬化性樹脂組成物、活性エネルギー線硬化性組成物等から構成されていることが好ましい。
上記熱可塑性樹脂組成物としては、特に限定されないが、スチレン系樹脂組成物、酢酸ビニル系樹脂組成物、ポリエステル系樹脂組成物、ポリエチレン系樹脂組成物、ポリプロピレン系樹脂組成物、イミド系樹脂組成物、アクリル系樹脂組成物等が挙げられる。 In the electromagnetic wave shielding film 10, the insulating layer 40 is not particularly limited as long as it has sufficient insulation and can protect the shielding layer 30 and the adhesive layer 20. For example, it may be made of a thermoplastic resin composition, a thermosetting resin composition, an activated It is preferable that it is made of an energy ray curable composition or the like.
The above-mentioned thermoplastic resin compositions include, but are not particularly limited to, styrene resin compositions, vinyl acetate resin compositions, polyester resin compositions, polyethylene resin compositions, polypropylene resin compositions, and imide resin compositions. , acrylic resin compositions, and the like.
上記熱硬化性樹脂組成物としては、特に限定されないが、フェノール系樹脂組成物、エポキシ系樹脂組成物、ウレタン系樹脂組成物、メラミン系樹脂組成物、アルキッド系樹脂組成物等が挙げられる。 Examples of the thermosetting resin composition include, but are not particularly limited to, phenolic resin compositions, epoxy resin compositions, urethane resin compositions, melamine resin compositions, alkyd resin compositions, and the like.
上記活性エネルギー線硬化性組成物としては、特に限定されないが、例えば、分子中に少なくとも２個の（メタ）アクリロイルオキシ基を有する重合性化合物等が挙げられる。 The active energy ray-curable composition is not particularly limited, but includes, for example, a polymerizable compound having at least two (meth)acryloyloxy groups in the molecule.
絶縁層４０は１種単独の材料から構成されていてもよく、２種以上の材料から構成されていてもよい。 The insulating layer 40 may be composed of a single type of material, or may be composed of two or more types of materials.
絶縁層４０には、必要に応じて、硬化促進剤、粘着性付与剤、酸化防止剤、顔料、染料、可塑剤、紫外線吸収剤、消泡剤、レベリング剤、充填剤、難燃剤、粘度調節剤、ブロッキング防止剤等が含まれていてもよい。 The insulating layer 40 may contain a curing accelerator, a tackifier, an antioxidant, a pigment, a dye, a plasticizer, an ultraviolet absorber, an antifoaming agent, a leveling agent, a filler, a flame retardant, and a viscosity adjuster, as necessary. It may also contain agents, anti-blocking agents, etc.
絶縁層４０の厚さは、特に限定されず、必要に応じて適宜設定することができるが、１～１５μｍであることが好ましく、３～１０μｍであることがより好ましい。
絶縁層４０の厚さが１μｍ未満であると、薄すぎるのでシールド層３０及び接着剤層２０を充分に保護しにくくなる。
絶縁層４０の厚さが１５μｍを超えると、厚すぎるので電磁波シールドフィルム１０が折れ曲りにくくなり、また、絶縁層４０の靭性が低下する。そのため、耐屈曲が要求される部材へ適用しにくくなる。 The thickness of the insulating layer 40 is not particularly limited and can be appropriately set as necessary, but is preferably 1 to 15 μm, more preferably 3 to 10 μm.
If the thickness of the insulating layer 40 is less than 1 μm, it is too thin and it becomes difficult to protect the shield layer 30 and the adhesive layer 20 sufficiently.
When the thickness of the insulating layer 40 exceeds 15 μm, the electromagnetic shielding film 10 becomes difficult to bend because it is too thick, and the toughness of the insulating layer 40 decreases. Therefore, it becomes difficult to apply it to members that require bending resistance.
なお、本発明の電磁波シールドフィルムにおいては、絶縁層は必要に応じて形成されていればよく、形成されていなくてもよい。 In addition, in the electromagnetic wave shielding film of this invention, the insulating layer should just be formed as needed, and does not need to be formed.
次に、本発明の電磁波シールドフィルムが用いられたシールドプリント配線板について説明する。
図２は、本発明の電磁波シールドフィルムが用いられたシールドプリント配線板の一例を模式的に示す断面図である。 Next, a shield printed wiring board using the electromagnetic shielding film of the present invention will be described.
FIG. 2 is a cross-sectional view schematically showing an example of a shield printed wiring board using the electromagnetic shielding film of the present invention.
図２に示すシールドプリント配線板１は、プリント配線板５０と、電磁波シールドフィルム１０とからなる。
プリント配線板５０は、ベースフィルム５１と、ベースフィルム５１の上に配置されたプリント回路５２と、プリント回路５２を覆うように配置されたカバーレイ５３とを備える。
プリント配線板５０では、プリント回路５２はグランド回路５２ａを含み、カバーレイ５３にはグランド回路５２ａを露出する開口部５３ａが形成されている。 The shield printed wiring board 1 shown in FIG. 2 consists of a printed wiring board 50 and an electromagnetic shielding film 10.
The printed wiring board 50 includes a base film 51, a printed circuit 52 placed on the base film 51, and a coverlay 53 placed so as to cover the printed circuit 52.
In the printed wiring board 50, the printed circuit 52 includes a ground circuit 52a, and the coverlay 53 has an opening 53a that exposes the ground circuit 52a.
シールドプリント配線板１では、カバーレイ５３と接着剤層２０とが接するように、プリント配線板５０の上に、電磁波シールドフィルム１０が配置されている。 In the shield printed wiring board 1, the electromagnetic shielding film 10 is arranged on the printed wiring board 50 so that the coverlay 53 and the adhesive layer 20 are in contact with each other.
シールドプリント配線板１では、接着剤層２０が、カバーレイ５３の開口部５３ａを埋め、グランド回路５２ａと接触している。このような構成とすることにより、電磁波シールドフィルム１０のシールド特性を向上させることができる。 In the shield printed wiring board 1, the adhesive layer 20 fills the opening 53a of the coverlay 53 and is in contact with the ground circuit 52a. With such a configuration, the shielding characteristics of the electromagnetic shielding film 10 can be improved.
以下に本発明をより具体的に説明する実施例を示すが、本発明はこれらの実施例に限定されるものではない。 Examples to more specifically explain the present invention are shown below, but the present invention is not limited to these Examples.
（実施例１）
絶縁層として、厚さが５μｍのエポキシ樹脂からなる絶縁層を準備した。
次に、当該絶縁層の上に、厚さが２．０μｍの銅層が形成されるように電解めっきを行った。なお、当該銅層はシールド層として機能する。 (Example 1)
As the insulating layer, an insulating layer made of epoxy resin and having a thickness of 5 μm was prepared.
Next, electrolytic plating was performed on the insulating layer so that a copper layer having a thickness of 2.0 μm was formed. Note that the copper layer functions as a shield layer.
次に、樹脂としてポリエステル系熱硬化性樹脂を１００重量部、導電性フィラーとして銀コート銅粉（粒子径Ｄ５０：５μｍ）を４０重量部及び多孔質無機粒子として多孔質シリカ粒子を１０重量部を混合し実施例１に係る導電性接着剤を作製した。使用した多孔質シリカの細孔容積等のパラメータは表１に示す。
次に、当該接着剤層を金属層の上に７μｍの厚さとなるように塗工し、実施例１に係る電磁波シールドフィルムを製造した。 Next, 100 parts by weight of a polyester thermosetting resin as a resin, 40 parts by weight of silver-coated copper powder (particle diameter D50 : 5 μm) as a conductive filler, and 10 parts by weight of porous silica particles as a porous inorganic particle. A conductive adhesive according to Example 1 was prepared by mixing the following. Table 1 shows parameters such as the pore volume of the porous silica used.
Next, the adhesive layer was coated on the metal layer to a thickness of 7 μm to produce the electromagnetic shielding film according to Example 1.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
（実施例２）～（実施例９）及び（比較例１）～（比較例４）
多孔質無機粒子として表１に示すものを用いた以外は、実施例１と同様に、実施例２～実施例９及び比較例１～比較例３に係る電磁波シールドフィルムを製造した。
また、多孔質無機粒子を使用しない以外は、実施例１と同様に比較例４に係る電磁波シールドフィルムを作製した。 (Example 2) - (Example 9) and (Comparative example 1) - (Comparative example 4)
Electromagnetic shielding films according to Examples 2 to 9 and Comparative Examples 1 to 3 were produced in the same manner as in Example 1, except that the porous inorganic particles shown in Table 1 were used.
Further, an electromagnetic shielding film according to Comparative Example 4 was produced in the same manner as in Example 1 except that porous inorganic particles were not used.
（層間剥離の有無の評価）
各実施例及び各比較例の電磁波シールドフィルムを熱プレスによりプリント配線板上に配置した。次いで、このプリント配線板を、３０℃、６０％ＲＨの恒温恒湿槽内に１日間放置した後、リフロー時の温度条件に曝して層間剥離の有無を評価した。なお、はんだフロート時の温度条件としては、最高２８８℃の温度を設定した。また、層間剥離の有無は、シールドフィルムを貼り付けたプリント配線板をはんだ槽に３回浮かべ、膨れの有無を目視により観察して評価した。ここで、シールドフィルムに膨れが全く生じなかったものを「◎」、シールドフィルムの一部にしか膨れが生じなかったものを「〇」、シールドフィルムの全面に著しく膨れが生じたものを「×」とした。その結果を表１に示す。 (Evaluation of presence or absence of delamination)
The electromagnetic shielding films of each Example and each Comparative Example were placed on a printed wiring board by heat pressing. Next, this printed wiring board was left in a constant temperature and humidity chamber at 30° C. and 60% RH for one day, and then exposed to the temperature conditions during reflow to evaluate the presence or absence of delamination. Note that the temperature conditions during solder float were set at a maximum temperature of 288°C. Further, the presence or absence of interlayer peeling was evaluated by floating the printed wiring board to which the shield film was attached three times in a solder bath and visually observing the presence or absence of blistering. Here, "◎" indicates that the shield film did not bulge at all, "〇" indicates that the bulge occurred only on a part of the shield film, and "×" indicates that the shield film had significant bulges on the entire surface. ”. The results are shown in Table 1.
（仮止め性の評価）
各実施例及び各比較例に係る電磁波シールドフィルムを用いて、以下の手順で接着性の評価を行った。
各電磁波シールドフィルムを、銅張積層板（ポリイミドフィルム基材／接着剤層／銅箔）のポリイミドフィルム基材側に０．５Ｐａ、１２０℃、５ｓｅｃの条件で押し付け仮止めを行った。その後、電磁波シールドフィルムが押し付けられた銅張積層板を手で振ることで銅張積層基板から電磁波シールドフィルムが落下するかで仮止め性を評価した。評価試験は１０回実施した。結果を表１に示す。
なお、評価基準は以下の通りである。
〇：すべてのサンプルが落下しなかった
△：一部のサンプルが落下しなかった
×：すべてのサンプルで落下が見られた (Evaluation of temporary fixability)
Adhesion was evaluated using the electromagnetic shielding film according to each Example and each Comparative Example according to the following procedure.
Each electromagnetic shielding film was pressed and temporarily fixed on the polyimide film base material side of a copper-clad laminate (polyimide film base material/adhesive layer/copper foil) under conditions of 0.5 Pa, 120° C., and 5 seconds. Thereafter, the temporary fixability was evaluated by shaking the copper-clad laminate to which the electromagnetic shielding film was pressed by hand to determine whether the electromagnetic shielding film would fall from the copper-clad laminate. The evaluation test was conducted 10 times. The results are shown in Table 1.
The evaluation criteria are as follows.
〇: All samples did not fall △: Some samples did not fall ×: All samples were observed to fall
表１に示すように、各実施例に係る電磁波シールドフィルムでは、層間剥離が生じないことが明らかとなった。 As shown in Table 1, it was revealed that interlayer peeling did not occur in the electromagnetic shielding films according to each example.
１　シールドプリント配線板
１０、５１０　電磁波シールドフィルム
２０、５２０　接着剤層
３０、５３０　シールド層
４０、５４０　絶縁層
５０　プリント配線板
５１　ベースフィルム
５２　プリント回路
５２ａ　グランド回路
５３　カバーレイ
５３ａ　開口部
５６０　揮発成分

  1 Shield printed wiring board 10, 510 Electromagnetic shielding film 20, 520 Adhesive layer 30, 530 Shield layer 40, 540 Insulating layer 50 Printed wiring board 51 Base film 52 Printed circuit 52a Ground circuit 53 Coverlay 53a Opening 560 Volatile component

Claims (9)

  1. 接着剤層と、前記接着剤層の上に積層されたシールド層とを含む電磁波シールドフィルムであって、
    前記接着剤層は、樹脂と、多孔質無機粒子とを含み、
    前記多孔質無機粒子の細孔容積は、０．４４ｍＬ／ｇを超え、１．８０ｍＬ／ｇ以下であることを特徴とする電磁波シールドフィルム。     An electromagnetic shielding film comprising an adhesive layer and a shielding layer laminated on the adhesive layer,
    The adhesive layer includes a resin and porous inorganic particles,
    An electromagnetic shielding film characterized in that the porous inorganic particles have a pore volume of more than 0.44 mL/g and less than 1.80 mL/g.
  2. 接着剤層と、前記接着剤層の上に積層されたシールド層とからなる電磁波シールドフィルムであって、
    前記接着剤層は、樹脂と、多孔質無機粒子とを含み、
    前記多孔質無機粒子の比表面積は、２８０ｍ２／ｇ以上、７００ｍ２／ｇ未満であることを特徴とする電磁波シールドフィルム。     An electromagnetic shielding film comprising an adhesive layer and a shielding layer laminated on the adhesive layer,
    The adhesive layer includes a resin and porous inorganic particles,
    An electromagnetic shielding film characterized in that the porous inorganic particles have a specific surface area of 280 m 2 /g or more and less than 700 m 2 /g.
  3. 接着剤層と、前記接着剤層の上に積層されたシールド層とからなる電磁波シールドフィルムであって、
    前記接着剤層は、樹脂と、多孔質無機粒子とを含み、
    前記多孔質無機粒子の細孔の平均細孔径は、２．５ｎｍを超え、２６ｎｍ以下であることを特徴とする電磁波シールドフィルム。     An electromagnetic shielding film comprising an adhesive layer and a shielding layer laminated on the adhesive layer,
    The adhesive layer includes a resin and porous inorganic particles,
    An electromagnetic shielding film characterized in that the porous inorganic particles have an average pore diameter of more than 2.5 nm and less than 26 nm.
  4. 前記多孔質無機粒子のＤＢＡ値は、５０ｍｅｑ／ｋｇ以上、２００ｍｅｑ／ｋｇ未満である請求項１～３のいずれかに記載の電磁波シールドフィルム。 The electromagnetic shielding film according to any one of claims 1 to 3, wherein the porous inorganic particles have a DBA value of 50 meq/kg or more and less than 200 meq/kg.
  5. 前記多孔質無機粒子の粒子径（Ｄ５０）は、１．０～２０．０μｍである請求項１～４のいずれかに記載の電磁波シールドフィルム。 The electromagnetic shielding film according to any one of claims 1 to 4, wherein the porous inorganic particles have a particle diameter (D 50 ) of 1.0 to 20.0 μm.
  6. 前記接着剤層は、導電性フィラーを含み、前記導電性フィラーの粒子径（Ｄ５０）は、４．０～３０．０μｍである請求項１～５のいずれかに記載の電磁波シールドフィルム。 The electromagnetic shielding film according to any one of claims 1 to 5, wherein the adhesive layer contains a conductive filler, and the conductive filler has a particle diameter (D 50 ) of 4.0 to 30.0 μm.
  7. 前記接着剤層は、前記樹脂１００重量部に対し、前記多孔質無機粒子を１～１００重量部含む請求項１～６のいずれかに記載の電磁波シールドフィルム。 7. The electromagnetic shielding film according to claim 1, wherein the adhesive layer contains 1 to 100 parts by weight of the porous inorganic particles based on 100 parts by weight of the resin.
  8. 前記接着剤層の厚さは、５～５０μｍである請求項１～７のいずれかに記載の電磁波シールドフィルム。 The electromagnetic shielding film according to any one of claims 1 to 7, wherein the adhesive layer has a thickness of 5 to 50 μm.
  9. 前記シールド層の上に、さらに絶縁層が積層されている請求項１～８のいずれかに記載の電磁波シールドフィルム。

          The electromagnetic shielding film according to claim 1, further comprising an insulating layer laminated on the shielding layer.
PCT/JP2023/012360 2022-03-29 2023-03-28 Electromagnetic wave shield film WO2023190425A1 (en)

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JP2015053412A (en) * 2013-09-09 2015-03-19 東洋インキＳｃホールディングス株式会社 Electromagnetic shield sheet and printed wiring board
JP2016204567A (en) * 2015-04-27 2016-12-08 東洋インキＳｃホールディングス株式会社 Conductive adhesive, conductive adhesive sheet, and wiring device

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2015053412A (en) * 2013-09-09 2015-03-19 東洋インキＳｃホールディングス株式会社 Electromagnetic shield sheet and printed wiring board
JP2016204567A (en) * 2015-04-27 2016-12-08 東洋インキＳｃホールディングス株式会社 Conductive adhesive, conductive adhesive sheet, and wiring device

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