JP6949724B2 - Electromagnetic wave shield film and its manufacturing method - Google Patents

Description

The present disclosure relates to an electromagnetic wave shielding film and a method for producing the same.

In recent years, smartphones and tablet-type information terminals are required to have the ability to transmit a large amount of data at high speed, and it is necessary to use a high frequency signal in order to transmit a large amount of data at high speed. However, when a high-frequency signal is used, electromagnetic noise is generated from a signal circuit provided on the printed wiring board, and peripheral devices are liable to malfunction. Therefore, in order to prevent such a malfunction, it is important to shield the printed wiring board from electromagnetic waves.

As a method of shielding a printed wiring board, it has been studied to use an electromagnetic wave shielding film having a shield layer and a conductive adhesive layer (see, for example, Patent Documents 1 to 3).

In these electromagnetic wave shield films, the conductive adhesive layer is superposed on the opening provided in the insulating layer covering the ground circuit of the printed wiring board, heated and pressed, and the opening is filled with the conductive adhesive. As a result, the shield layer and the ground circuit of the printed wiring board are connected via the conductive adhesive, and the printed wiring board is shielded. After that, the shielded printed wiring board is exposed to a high temperature of about 270 ° C. in the reflow process in order to connect the printed wiring board and the electronic component.

In addition, after pasting the electronic component on the printed wiring board, in order to finely correct the position of the electronic component, the printed wiring board is heated to peel off the electronic component from the printed wiring board, and then the electronic component is pasted again. Called work may be done. Then, after the repair work, it is necessary to attach the electronic component to the printed wiring board, so that the electromagnetic wave shield film is exposed to high temperature again in the reflow process.

Japanese Unexamined Patent Publication No. 2004-095566 WO2006 / 088127 Pamphlet WO2009 / 019963 Pamphlet

Here, in the electromagnetic wave shield film described in Patent Documents 1 to 3, when the shield printed wiring board is exposed to a plurality of reflow steps, the conductive adhesive layer flows and the metal surface is oxidized, resulting in the shield film. There is a problem that the electrical connection between the film and the printed wiring board is deteriorated, and as a result, the shield characteristics are deteriorated.

Therefore, the present invention has been made in view of the above problems, and is an electromagnetic wave shielding film capable of maintaining a stable connection with a printed wiring board even when exposed to a plurality of reflow steps. , And a method for producing the same.

In order to achieve the above object, the electromagnetic wave shielding film of the present invention comprises a shield layer composed of a first metal layer containing nickel as a main component and a second metal layer containing copper as a main component, and a first shield layer. It is characterized by having an adhesive layer provided on the side of the two metal layers and a protective layer provided on the side of the first metal layer of the shield layer, and the average crystal grain size of the second metal layer is 50 nm or more and 200 nm or less. And.

In the electromagnetic wave shielding film of the present invention, since the average crystal grain size of the second metal layer is 50 nm or more and 200 nm or less, the connection with the printed wiring board can be stably maintained even when exposed to a plurality of reflow steps. can.

It is sectional drawing of the electromagnetic wave shielding film which concerns on embodiment of this invention. It is sectional drawing of the shield printed wiring board which concerns on embodiment of this invention. It is a figure for demonstrating the measuring method of the electric resistance value in the reflow resistance evaluation of an Example.

Hereinafter, the electromagnetic wave shielding film of the present invention will be specifically described. The present invention is not limited to the following embodiments, and can be appropriately modified and applied without changing the gist of the present invention.
<Electromagnetic wave shield film>
As shown in FIG. 1, the electromagnetic wave shielding film 1 of the present invention is formed on a shield layer 2 composed of a first metal layer 5 and a second metal layer 6 and a surface of the shield layer 2 on the second metal layer 6 side. The adhesive layer 3 provided and the protective layer 4 provided on the surface of the shield layer 2 on the side of the first metal layer are provided.

<Shield layer>
As shown in FIG. 1, the shield layer 2 is composed of a first metal layer 5 provided on one side of the protective layer 4 and a second metal layer 6 provided on the surface of the first metal layer 5. ..

Here, in the present embodiment, the average crystal grain size of the second metal layer 6 is set to 50 nm or more and 200 nm or less from the viewpoint of preventing a decrease in the electrical connection between the electromagnetic wave shielding film 1 and the printed wiring board. It is necessary to control it, and it is more preferable to control it to 50 nm or more and 150 nm or less. The average crystal grain size should be small in order to suppress surface oxidation, but the film formation rate may slow down. Therefore, it is stable by forming a film so that the average crystal grain size is 50 nm or more by the vacuum vapor deposition method. Can be manufactured. Further, by setting the average crystal grain size to 200 nm or less, the surface oxidation preventing effect of the second metal layer 6 can be obtained, and by setting the average crystal particle size to 150 nm or less, a higher effect can be obtained.

The first metal layer 5 and the second metal layer 6 can be a metal film, a conductive film made of conductive particles, or the like, and in the present embodiment, the first metal layer 5 contains nickel as a main component and is a first metal layer. 2 The metal layer 6 contains copper as a main component. This is because if a copper film is formed on the protective layer 4 only by the vacuum vapor deposition method, sufficient adhesion between the protective layer 4 and the copper film cannot be secured. Therefore, for the purpose of ensuring the adhesive force, a sputtering method is performed on the protective layer 4. A method is adopted in which a first metal layer 5 is formed as a base layer, and a second metal layer 6 containing copper as a main component is vapor-deposited on the first metal layer 5. However, when copper is deposited as the first metal layer 5 as the base layer by the sputtering method, it is affected by the copper formed by the sputtering method having a large average crystal grain size, and the second metal formed on the copper by vacuum deposition. The average crystal grain size of the layer 6 also becomes large, which makes control difficult. Therefore, it is preferable that nickel having a small effect on the average crystal grain size on the second metal layer 6 is formed as the first metal layer 5 by a sputtering method.

With such a configuration, it is presumed that a stable thin oxide film is formed on the surface of the second metal layer 6 on the adhesive layer 3 side. Further, it is considered that this thin oxide film acts as a protective film even in a high temperature environment and suppresses the progress of oxidation. Therefore, even when the shield printed wiring board is exposed to a plurality of reflow steps, it is possible to prevent a decrease in electrical connection due to an increase in the oxide film between the electromagnetic wave shield film 1 and the printed wiring board. .. Therefore, a stable connection between the electromagnetic wave shield film 1 and the printed wiring board can be maintained.

The "average crystal grain size" referred to here refers to the result of measuring the average crystal grain size using X-ray diffraction (RIGAKU Ultima IV). In addition, the voltage and current of the X-ray tube: 40 kV-40 mA, scanning speed: 2 ° / min, divergence slit (DS): 2/3 °, scattering slit (SS): 2/3 °, light receiving slit (RS). : Measured under the measurement condition of 0.3 mm, and the average crystal grain size is calculated from the half-value width (FWHM) of the (111) diffraction line, which is the preferential orientation plane of the second metal layer 6, using the Scherrer equation. do.

In the present embodiment, the thickness _{T 1} of the first metal layer 5, the sum of the thickness _{T 2} of the second metal layer 6 is more than 0.105μm 3.03μm or less (i.e., 0.105μm ≦ _{T 1} + T ₂ ≤ 3.03 μm) is preferable. If it is less than 0.105 μm, the performance as an electromagnetic wave shield is insufficient, and from the viewpoint of the electromagnetic wave shield performance, the thickness of the second metal layer 6 is preferably thick, but it is larger than 3.03 μm. In this case, the average crystal grain size of the second metal layer 6 becomes too large, which may cause a disadvantage that the effect of preventing surface oxidation of the second metal layer 6 cannot be obtained.

Further, in the present embodiment, the thickness T ₂ of the second metal layer 6 is preferably 0.1 μm or more and 3 μm or less, and more preferably 0.2 μm or more and 1.5 μm or less. If it is less than 0.1 μm, there may be an inconvenience that the electromagnetic wave shielding performance becomes insufficient. Further, even if it is 0.1 μm or more, the electromagnetic wave shielding performance is insufficient depending on the application, and the thickness of the second metal layer 6 is preferably 0.2 μm or more from the viewpoint of improving the electromagnetic wave shielding performance. On the other hand, if it is larger than 3 μm, the average crystal grain size of the second metal layer 6 becomes too large, which may cause a disadvantage that the effect of preventing surface oxidation of the second metal layer 6 cannot be obtained. Is. Further, from the viewpoint of preventing surface oxidation, the second metal layer 6 is preferably thinner, and when the heating conditions during reflow become more severe due to the use of lead-free solder, the thickness of the second metal layer 6 is 1.5 μm. The following is more preferable.

Further, in the present embodiment, the thickness T ₁ of the first metal layer 5 is preferably 5 nm or more and 30 nm or less, and more preferably 7 nm or more and 15 nm or less. This is because if it is less than 5 nm, there may be a disadvantage that the adhesion between the first metal layer 5 and the protective layer 4 is lowered. In reflow used for solder mounting or the like, when the heating conditions become more severe due to the use of lead-free solder, it is necessary to further stabilize the adhesion force, and it is more preferably 7 nm or more. If it is larger than 30 nm, the average crystal grain size of the second metal layer 6 formed on the first metal layer 5 becomes even larger, and the effect of preventing surface oxidation of the second metal layer 6 cannot be obtained. This is because the inconvenience may occur. In order to prevent surface oxidation, the thickness T ₁ of the first metal layer 5 is preferably thin, and in reflow used for solder mounting or the like, when the heating conditions become more severe due to the use of lead-free solder, the thickness is 15 nm. The following is preferable.

<Adhesive layer>
The adhesive layer 3 is not particularly limited as long as it can fix the electromagnetic wave shielding film 1 to the printed wiring board, but it is preferably a conductive adhesive layer having an adhesive resin composition and a conductive filler.

The adhesive resin composition is not particularly limited, but a styrene resin composition, a vinyl acetate resin composition, a polyester resin composition, a polyethylene resin composition, a polypropylene resin composition, an imide resin composition, Thermoplastic resin composition such as amide resin composition or acrylic resin composition, or phenol resin composition, epoxy resin composition, urethane resin composition, melamine resin composition, or alkyd resin composition A thermosetting resin composition or the like can be used. These may be used alone or in combination of two or more.

The adhesive layer 3 contains, if necessary, 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 flame retardant. At least one such as a viscosity modifier may be contained.

The thickness of the adhesive layer 3 is not particularly limited and can be appropriately set as needed, but can be 3 μm or more, preferably 4 μm or more, 10 μm or less, and preferably 7 μm or less.

The conductive filler is not particularly limited, and for example, a metal filler, a metal-coated resin filler, a carbon filler, and a mixture thereof can be used. Examples of the metal filler include copper powder, silver powder, nickel powder, silver coat copper powder, gold-coated copper powder, silver-coated nickel powder, and gold-coated nickel powder. These metal powders can be obtained by an electrolytic method, an atomizing method, or reduction. It can be produced by the method.

Further, in particular, in order to facilitate contact between the fillers, it is preferable that the average particle size of the conductive filler is 3 to 50 μm. Further, examples of the shape of the conductive filler include a spherical shape, a flake shape, a dendritic shape, and a fibrous shape. Among these, at least one selected from the group consisting of silver powder, silver-coated copper powder, and copper powder is preferable from the viewpoint of connection resistance and cost.

When the adhesive layer 3 contains a conductive filler, it can be an anisotropic conductive adhesive layer or an isotropic conductive adhesive layer.

When the conductive filler is an isotropic conductive adhesive layer, the conductive filler can be added in a range of more than 39 wt% and 400 wt% or less with respect to the total amount of the adhesive layer 3. Further, in the case of the anisotropic conductive adhesive layer, it can be added in the range of 3 wt% to 39 wt% with respect to the total amount of the adhesive layer 3.

<Protective layer>
The protective layer 4 may satisfy predetermined mechanical strength, chemical resistance, heat resistance, etc. that can protect the shield layer 2. The protective layer 4 is not particularly limited as long as it has sufficient insulating properties and can protect the adhesive layer 3 and the shield layer 2, but for example, it is a thermoplastic resin composition, a thermosetting resin composition, or active energy ray curable. A composition or the like can be used.

The thermoplastic resin composition is not particularly limited, but is limited to a styrene resin composition, a vinyl acetate resin composition, a polyester resin composition, a polyethylene resin composition, a polypropylene resin composition, an imide resin composition, and the like. Alternatively, an acrylic resin composition or the like can be used. The thermosetting resin composition is not particularly limited, but is limited to a phenol-based resin composition, an epoxy-based resin composition, a urethane-based resin composition having an isocyanate group at the terminal, a urea-based resin having an isocyanate group at the terminal, and a terminal. A urethane urea-based resin having an isocyanate group, a melamine-based resin composition, an alkyd-based resin composition, or the like can be used. The active energy ray-curable composition is not particularly limited, and for example, a polymerizable compound having at least two (meth) acryloyloxy groups in the molecule can be used. These resins may be used alone or in combination of two or more.

Further, among these, from the viewpoint of improving the reflow resistance and preventing a decrease in the electrical connection between the electromagnetic wave shielding film 1 and the printed wiring board, the urethane urea resin having an isocyanate group at the terminal or the terminal is used. A resin in which a urethane urea resin having an isocyanate group and an epoxy resin are used in combination is preferable. Further, the urethane-based resin having an isocyanate group at the terminal or the urethane urea-based resin having an isocyanate group at the terminal preferably has an acid value of 1 to 30 mgKOH / g, and preferably has an acid value of 3 to 20 mgKOH / g. More preferred. Further, two or more urethane resins or urethane urea resins having an acid value in the range of 1 to 30 mgKOH / g and having different acid values may be used in combination. When the acid value is 1 mgKOH / g or more, the reflow resistance of the electromagnetic wave shield film is good, and when the acid value is 30 mgKOH / g or less, the bending resistance of the electromagnetic wave shield film is good. The acid value is measured in accordance with JIS K 0070-1992. Further, the protective layer 4 may be formed of a single material or may be formed of two or more kinds of materials.

The protective layer 4 contains 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, if necessary. At least one agent, anti-blocking agent and the like may be contained.

The protective layer 4 may be a laminate of two or more layers having different physical properties such as material or hardness or elastic modulus. For example, in the case of a laminate of an outer layer having a low hardness and an inner layer having a high hardness, the outer layer has a cushioning effect, so that the pressure applied to the shield layer 2 is relaxed in the step of heating and pressurizing the electromagnetic wave shield film 1 on the printed wiring board. can. Therefore, it is possible to prevent the shield layer 2 from being destroyed by the step provided on the printed wiring board.

The thickness of the protective layer 4 is not particularly limited and can be appropriately set as needed, but is 1 μm or more, preferably 4 μm or more, and 20 μm or less, preferably 10 μm or less, more preferably 5 μm or less. can do. By setting the thickness of the protective layer 4 to 1 μm or more, the adhesive layer 3 and the shield layer 2 can be sufficiently protected. By setting the thickness of the protective layer 4 to 20 μm or less, the flexibility of the electromagnetic wave shielding film 1 can be ensured, and it is easy to apply one electromagnetic wave shielding film 1 to a member requiring flexibility. It becomes.

(Manufacturing method of electromagnetic wave shield film)
Next, an example of the method for manufacturing the electromagnetic wave shielding film 2 of the present invention will be described. The method for producing the electromagnetic wave shielding film 2 of the present invention is not particularly limited, and for example, a step of forming the protective layer 4, a step of forming the first metal layer 5 on the surface of the protective layer 4, and a step of forming the first metal layer 5. After the step of forming the second metal layer 6 on the surface opposite to the protective layer 4 and the coating of the composition for the adhesive layer on the surface of the second metal layer 6 opposite to the first metal layer 5. An example is a production method including a step of curing the composition for adhesive composition to form the adhesive layer 3.

<Protective layer forming process>
First, a composition for a protective layer is prepared. This protective layer composition can be prepared by adding an appropriate amount of a solvent and other compounding agents to the resin composition. The solvent can be, for example, toluene, acetone, methyl ethyl ketone, methanol, ethanol, propanol, dimethylformamide and the like. As other compounding agents, a cross-linking agent, a polymerization catalyst, a curing accelerator, a colorant and the like can be added. Other compounding agents may be added as needed.

Next, the prepared protective layer composition is applied to one side of the supporting base material. The method of applying the protective layer composition to one side of the support base material is not particularly limited, and known techniques such as lip coating, comma coating, gravure coating, and slot die coating can be adopted.

The supporting base material can be, for example, in the form of a film. The supporting base material is not particularly limited, and can be formed of, for example, a material such as a polyolefin-based material, a polyester-based material, a polyimide-based material, or a polyphenylene sulfide-based material. A release agent layer may be provided between the support base material and the composition for the protective layer.

Then, the protective layer 4 is formed by applying the protective layer composition to the supporting base material and then heating and drying to remove the solvent. The support base material can be peeled off from the protective layer 4, but the support base material can be peeled off after the electromagnetic wave shield film 1 is attached to the printed wiring board. In this way, the electromagnetic wave shielding film 1 can be protected by the supporting base material.

<First metal layer forming process>
Next, the first metal layer 5 is formed on the surface of the protective layer 4. More specifically, a film is installed in a batch type vacuum vapor deposition apparatus (EBH-800 manufactured by ULVAC), a nickel target having a size of 50 mm × 550 mm is used, and a vacuum reach of 5 × 10 ^-1 Pa or less in an argon gas atmosphere. The first metal layer 5 can be formed by continuously applying the DC power supply for a period of time to reach a predetermined metal film thickness. The vacuum deposition for forming the second metal layer 6 performed after sputtering was continuously processed so as not to come into contact with the atmosphere between sputtering and vapor deposition.

Here, in the present embodiment, when the first metal layer 5 is formed into a film by a sputtering method, sufficient adhesion to the protective layer 4 can be obtained. Further, by using nickel as the first metal layer 5, it is possible to suppress the average crystal grain size of the second metal layer 6 and suppress the surface oxidation of the second metal layer 6.

<Second metal layer forming process>
Next, the second metal layer 6 is formed on the surface of the first metal layer 5 opposite to the protective layer 4. More specifically, after installing the film in a batch type vacuum vapor deposition apparatus (EBH-800 manufactured by ULVAC) and placing an amount of copper to the desired thickness on the vapor deposition boat, the vacuum reach is 9.0. After evacuation was performed until it became × 10 ^-3 Pa or less, the evaporation boat was heated to perform vacuum deposition. The formation of the first metal layer 5 and the formation of the second metal layer 6 were continuously processed so as not to come into contact with the atmosphere between sputtering and vapor deposition.

Here, in the present embodiment, the vacuum vapor deposition method is preferable as the method for forming the second metal layer 6 having a small average crystal grain size. Since the growth rate of metal crystals is high by a sputtering method or the like and it is difficult to control the average crystal grain size to 200 nm or less, it is preferable to form the second metal layer 6 by a vacuum deposition method.

<Adhesive layer forming process>
Next, the composition for an adhesive layer is applied to the surface of the second metal layer 6 opposite to the first metal layer 5, to form the adhesive layer 3. Here, the composition for the adhesive layer contains a resin composition and a solvent. The resin composition is not particularly limited, but is a styrene resin composition, a vinyl acetate resin composition, a polyester resin composition, a polyethylene resin composition, a polypropylene resin composition, an imide resin composition, and an amide resin. A composition, a thermoplastic resin composition such as an acrylic resin composition, a phenol-based resin composition, an epoxy-based resin composition, a urethane-based resin composition, a melamine-based resin composition, an alkyd-based resin composition, or the like. It can be a thermosetting resin composition or the like. These may be used alone or in combination of two or more.

The solvent can be, for example, toluene, acetone, methyl ethyl ketone, methanol, ethanol, propanol, dimethylformamide and the like.

In addition, if necessary, a curing accelerator, a tackifier, an antioxidant, a pigment, a dye, a plasticizer, an ultraviolet absorber, a defoaming agent, a leveling agent, a filler, and a flame retardant are added to the composition for the adhesive layer. , And at least one of a viscosity modifier and the like may be contained. The ratio of the resin composition in the composition for the adhesive layer may be appropriately set according to the thickness of the adhesive layer 3 and the like.

The method of applying the composition for the adhesive layer on the second metal layer 6 is not particularly limited, and lip coating, comma coating, gravure coating, slot die coating and the like can be used.

Then, the composition for the adhesive layer is applied onto the second metal layer 6, and then the adhesive layer 3 is formed by heating and drying to remove the solvent. If necessary, a release film may be attached to the surface of the adhesive layer 3.

(Shield printed wiring board)
The electromagnetic wave shield film 1 of the present embodiment can be used, for example, in the shield printed wiring board 30 shown in FIG. The shield printed wiring board 30 includes a printed wiring board 20 and an electromagnetic wave shielding film 1.

The printed wiring board 20 includes a base layer 11, a printed circuit (ground circuit) 12 formed on the base layer 11, and an insulating adhesive layer 13 provided adjacent to the printed circuit 12 on the base layer 11. An opening 15 for exposing a part of the printed circuit 12 is formed, and the insulating coverlay 14 is provided so as to cover the insulating adhesive layer 13. The insulating layer of the printed wiring board 20 is formed by the insulating adhesive layer 13 and the coverlay 14.

The base layer 11, the insulating adhesive layer 13, and the coverlay 14 are not particularly limited, and may be, for example, a resin film or the like. In this case, it can be formed of a resin such as polypropylene, cross-linked polyethylene, polyester, polybenzoimidazole, polyimide, polyimideamide, polyetherimide, or polyphenylene sulfide. The print circuit 12 can be, for example, a copper wiring pattern formed on the base layer 11.

The electromagnetic wave shield film 1 is adhered to the printed wiring board 20 with the adhesive layer 3 on the coverlay 14 side.

Next, a method of manufacturing the shield printed wiring board 30 will be described. The electromagnetic wave shield film 1 is placed on the printed wiring board 20 and pressurized while being heated by a press machine. A part of the adhesive layer 3 softened by heating flows into the opening 15 formed in the coverlay 14 by pressurization. As a result, the shield layer 2 and the ground circuit 12 of the printed wiring board 20 are connected via a conductive adhesive, and the shield layer 2 and the ground circuit 12 are connected.

Hereinafter, the present invention will be described based on examples. The present invention is not limited to these examples, and these examples can be modified or modified based on the gist of the present invention, and they are not excluded from the scope of the invention. No.

(Example 1)
<Manufacturing of electromagnetic wave shield film>
As the supporting base material, a PET film having a thickness of 60 μm and having a mold release treatment on the surface was used. Next, a protective layer composition (solid content: 30% by mass) composed of a bisphenol A type epoxy resin (manufactured by Mitsubishi Chemical Corporation, jER1256) and methyl ethyl ketone is applied onto the supporting base material, and the mixture is heated and dried. To prepare a supporting base material with a protective layer having a thickness of 5 μm.

Next, a shield layer was formed on the surface of the protective layer. More specifically, a support base material with a protective layer is installed in a batch type vacuum vapor deposition apparatus (EBH-800 manufactured by ULVAC), and the vacuum reach is adjusted to ^{5 × 10 -1 Pa or less in an argon gas atmosphere.} , Nickel was deposited to a thickness of 5 nm by a magnetron sputtering method (DC power supply output: 3.0 kW) to form a first metal layer.

Next, after copper was placed on the vapor deposition boat, vacuuming ^{was performed until the degree of vacuum reached was 9.0 × 10 -3} Pa or less, and then the evaporation boat was heated to perform vacuum deposition. A 5 μm second metal layer was formed. The formation of the first metal layer and the formation of the second metal layer were continuously processed so as not to come into contact with the atmosphere between sputtering and vapor deposition.

Next, an adhesive composed of an epoxy resin and silver-coated copper powder having a spherical particle diameter of 3 μm (blending amount 50 wt%) having an average particle diameter of 3 μm is applied to the surface of the shield layer to form an adhesive layer having a thickness of 5 μm. Formed.

<Manufacturing of shield printed wiring board>
Next, the produced electromagnetic wave shield film and the printed wiring board are superposed so that the adhesive layer of the electromagnetic wave shield film and the printed wiring board face each other, and the pressure is 170 ° C. and 3.0 MPa using a press machine. After heating and pressurizing for 1 minute, heating and pressurizing was performed at the same temperature and pressure for 3 minutes, and the supporting base material was peeled off from the protective layer to prepare a shield-printed wiring board.

The printed wiring board has two copper foil patterns extending in parallel with each other at intervals and an insulating layer (thickness: 25 μm) made of polyimide while covering the copper foil patterns. The insulating layer has an insulating layer (thickness: 25 μm). , An opening (diameter: 1 mm) was provided to expose each copper foil pattern. Further, the adhesive layer of the electromagnetic wave shielding film and the printed wiring board were overlapped so that the opening was completely covered by the electromagnetic wave shielding film.

<Reflow resistance evaluation>
Next, the reflow resistance of the produced shield printed wiring board was evaluated. As the reflow conditions, lead-free solder was assumed, and a temperature profile was set so that the shield film on the shield printed wiring board was exposed to 265 ° C. for 1 second.

Then, after exposing the shield printed wiring board to the shield printed wiring board 1 to 5 times under the temperature conditions of the above profile, as shown in FIG. 3, the electrical resistance between the two copper foil patterns 41 formed on the printed wiring board 40. The value was measured with an ohmmeter 42, and the connectivity between the copper foil pattern 41 and the electromagnetic wave shielding film 43 was evaluated.

Then, the above reflow steps were performed 5 times, and the change in resistance value after each reflow was evaluated. The above results are shown in Table 1.

(Example 2)
An electromagnetic wave shield film and a shield printed wiring board were produced in the same manner as in Example 1 except that the nickel film thickness of the first metal layer was changed to 10 nm, and reflow resistance was evaluated. The above results are shown in Table 1.

(Example 3)
An electromagnetic wave shield film and a shield printed wiring board were produced in the same manner as in Example 1 except that the nickel film thickness of the first metal layer was changed to 7 nm, and reflow resistance was evaluated. The above results are shown in Table 1.

(Example 4)
An electromagnetic wave shield film and a shield printed wiring board were produced in the same manner as in Example 1 except that the nickel film thickness of the first metal layer was changed to 3 nm, and reflow resistance was evaluated. The above results are shown in Table 1.

(Comparative Example 1)
An electromagnetic wave shield film and a shield printed wiring board were produced in the same manner as in Example 1 except that the metal forming the first metal layer was changed to copper and the copper film thickness was changed to 10 nm, and the reflow resistance was evaluated. Was done. The above results are shown in Table 1.

As shown in Table 1, in Examples 1 to 4 in which the average crystal grain size of the second metal layer is 50 nm or more and 200 nm or less, the resistance value increases even when exposed to a plurality of reflow steps. It can be seen that the electrical connection between the electromagnetic wave shielding film and the printed wiring board is stably maintained.

1 Electromagnetic wave shield film 2 Shield layer 3 Adhesive layer 4 Protective layer 5 1st metal layer 6 2nd metal layer 11 Base layer 12 Print circuit (ground circuit)
13 Insulating adhesive layer 14 Coverlay 15 Opening 20 Printed wiring board 30 Printed wiring board

Claims (5)

A shield layer composed of a first metal layer containing nickel as a main component and a second metal layer containing copper as a main component,
An adhesive layer provided on the surface of the shield layer on the side of the second metal layer,
An electromagnetic wave shielding film provided with a protective layer provided on the surface of the shield layer on the side of the first metal layer.
The adhesive layer includes a styrene resin composition, a vinyl acetate resin composition, a polyester resin composition, a polyethylene resin composition, a polypropylene resin composition, an imide resin composition, an amide resin composition, and acrylic. At least one adhesive resin composition selected from the group consisting of a based resin composition, a phenolic resin composition, an epoxy resin composition, a urethane resin composition, a melamine resin composition, and an alkyd resin composition. A conductive adhesive layer having at least one conductive filler selected from the group consisting of a metal filler, a metal-coated resin filler, and a carbon filler.
The average particle size of the conductive filler is 3 to 50 μm.
The blending amount of the conductive filler is more than 39 wt% and 400 wt% or less with respect to the total amount of the adhesive layer.
The thickness of the adhesive layer is 3 μm or more and 10 μm or less.
An electromagnetic wave shielding film characterized in that the average crystal grain size of the second metal layer is 50 nm or more and 200 nm or less. The electromagnetic wave shielding film according to claim 1, wherein the total of the thickness of the first metal layer and the thickness of the second metal layer is 0.105 μm or more and 3.03 μm or less. The electromagnetic wave shielding film according to claim 1 or 2, wherein the thickness of the second metal layer is 0.1 μm or more and 3 μm or less. The electromagnetic wave shielding film according to any one of claims 1 to 3, wherein the thickness of the first metal layer is 5 nm or more and 30 nm or less. A shield layer composed of a first metal layer containing nickel as a main component and a second metal layer containing copper as a main component, an adhesive layer provided on the second metal layer side of the shield layer, and a shield layer. This is a method for manufacturing an electromagnetic wave shielding film provided with a protective layer provided on the first metal layer side of the above.
The adhesive layer includes a styrene resin composition, a vinyl acetate resin composition, a polyester resin composition, a polyethylene resin composition, a polypropylene resin composition, an imide resin composition, an amide resin composition, and acrylic. At least one adhesive resin composition selected from the group consisting of a based resin composition, a phenolic resin composition, an epoxy resin composition, a urethane resin composition, a melamine resin composition, and an alkyd resin composition. A conductive adhesive layer having at least one conductive filler selected from the group consisting of a metal filler, a metal-coated resin filler, and a carbon filler.
The average particle size of the conductive filler is 3 to 50 μm.
The blending amount of the conductive filler is more than 39 wt% and 400 wt% or less with respect to the total amount of the adhesive layer.
The thickness of the adhesive layer is 3 μm or more and 10 μm or less.
A method for producing an electromagnetic wave shielding film, wherein the first metal layer is formed by a sputtering method, and the second metal layer is formed by a vacuum vapor deposition method.

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