Copper-clad laminate and method for manufacturing same

Abstract

This copper-clad laminate comprises: a dielectric film which has a dielectric constant of 3.5 or less at 23 ± 5°C, 50 ± 5% RH, and a frequency of 10 GHz, and a dielectric loss tangent of 0.0030 or less; an adhesive layer which contains at least one of a specific silane coupling agent and a bismaleimide resin, and is formed on at least one surface of the dielectric film; and a copper layer which is composed of a copper foil that has a matte surface having a ten-point average roughness (Rzjis) of 1.5 µm or less as measured in accordance with JIS standard B0601 2001 (ISO 4287 1997), the copper layer being disposed so that the matte surface is in contact with a surface of the adhesive layer on the reverse side from the surface on which the dielectric film is disposed.

Description

Copper-clad laminate and its manufacturing method

[0001] The present invention relates to a copper-clad laminate and a method for producing the same.

[0002] High-frequency circuits that process high-frequency signals experience transmission loss. To reduce this transmission loss, copper-clad laminates, which are composed of a conductive layer and an electrically insulating layer with a low dielectric constant and a small dielectric loss tangent, have been proposed as materials for wiring substrates on which high-frequency circuits are formed.

[0003] Patent Document 1 discloses a copper-clad laminate comprising a copper foil layer made of copper foil and a fluororesin layer made of fluororesin, with the fluororesin layer formed on at least one surface of the copper foil layer. This copper-clad laminate is obtained as follows: First, a dispersion of fluororesin powder dispersed in an organic solvent is applied to at least one surface of the copper foil. Next, the copper foil coated with the dispersion is heated to remove the organic solvent. Next, the copper foil is heated at 350°C to melt the fluororesin powder, forming a fluororesin layer on the surface of the copper foil. After this, the copper-clad laminate is obtained by cooling.

[0004] Patent No. 7234921

[0005] The fluororesin layer, which is the electrical insulating layer of this copper-clad laminate, has a low dielectric constant and a small dielectric loss tangent. Therefore, the transmission loss of a wiring board made from this copper-clad laminate is low. However, during the manufacturing process of this copper-clad laminate, residual stress occurs in the fluororesin layer, causing the copper-clad laminate to warp. Therefore, it is difficult to form high-resolution circuits on the copper foil layer of such a copper-clad laminate.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a copper-clad laminate that has little warpage and can suppress transmission loss in a wiring board on which a high-frequency circuit is formed, and a method for manufacturing the same.

[0007] The present invention is as follows.

[0008] [1] The copper-clad laminate according to the present invention comprises: a dielectric film having a dielectric constant of 3.5 or less and a dielectric dissipation factor of 0.0030 or less at 23±5°C, 50±5% RH, and a frequency of 10 GHz; an adhesive layer formed on at least one surface of the dielectric film, the adhesive layer containing at least one of a silane coupling agent represented by the following formula (1) and a bismaleimide resin; and a copper layer composed of copper foil having a matte surface with a ten-point average roughness (Rzjis) of 1.5 μm or less as measured in accordance with JIS standard B0601 2001 (ISO 4287 1997), the copper layer being arranged on the surface of the adhesive layer opposite to the surface on which the dielectric film is arranged so that the matte surface is in contact with the surface. In formula (1), R １ , R ２ are each independently a hydrogen atom, a monovalent hydrocarbon group having 1 to 24 carbon atoms, a phenyl group, an amino group, or an aminoalkyl group; ３ is a divalent hydrocarbon group having 3 to 24 carbon atoms, and R ４ is a monovalent hydrocarbon group having 1 to 24 carbon atoms, N is a nitrogen atom, Si is a silicon atom, and O is an oxygen atom.

[0009] [2] The adhesive layer may contain the silane coupling agent and the bismaleimide resin, and the weight ratio (wt %) of the silane coupling agent to the bismaleimide resin may be 5:95 to 95:5.

[0010] [3] The thickness of the adhesive layer may be 0.01 μm or more and 7 μm or less.

[0011] [4] The copper-clad laminate may have a warpage of 10 mm or less after being left in an atmosphere of 20±5° C. and 65±20% RH for 24 hours.

[0012] [5] A method for producing a copper-clad laminate according to the present invention includes: an adhesive layer forming step of forming an adhesive layer containing at least one of a silane coupling agent represented by the following formula (1) and a bismaleimide resin on a matte surface of a copper foil having a matte surface and a ten-point average roughness (Rzjis) of 1.5 μm or less as measured in accordance with JIS standard B0601 2001 (ISO 4287 1997); a dielectric film disposing step of disposing, on the adhesive layer, a dielectric film having a dielectric constant of 3.5 or less and a dielectric dissipation factor of 0.0030 or less at 23±5°C, 50±5% RH, and a frequency of 10 GHz; and a heating and pressing step of heating the obtained laminate composed of the copper foil, the adhesive layer, and the dielectric film at a temperature of 40°C or more and 110°C or less, a pressure of 0.01 MPa or more and 5.0 MPa or less, and a heating and pressing time of 0.01 seconds or more and 2 minutes or less. In formula (1), R １ , R ２ are each independently a hydrogen atom, a monovalent hydrocarbon group having 1 to 24 carbon atoms, a phenyl group, an amino group, or an aminoalkyl group; ３ is a divalent hydrocarbon group having 3 to 24 carbon atoms, and R ４ is a monovalent hydrocarbon group having 1 to 24 carbon atoms, N is a nitrogen atom, Si is a silicon atom, and O is an oxygen atom.

[0013] [6] A method for producing a copper-clad laminate according to the present invention includes: an adhesive layer forming step of forming an adhesive layer containing at least one of a silane coupling agent represented by the following formula (1) and a bismaleimide resin on at least one surface of a dielectric film having a dielectric constant of 3.5 or less and a dielectric dissipation factor of 0.0030 or less at 23±5°C, 50±5% RH, and a frequency of 10 GHz; a copper foil arranging step of arranging a copper foil having a matte surface with a ten-point average roughness (Rzjis) of 1.5 μm or less as measured in accordance with JIS standard B0601 2001 (ISO 4287 1997) on the adhesive layer so that the matte surface contacts the surface of the adhesive layer; and a heating and pressing step of heating the obtained laminate composed of the dielectric film, the adhesive layer, and the copper foil at a temperature of 40°C or higher and 110°C or lower, applying a pressure of 0.01 MPa or higher and 5.0 MPa or lower, and applying heating and pressing for a time of 0.01 seconds or higher and 2 minutes or shorter. In formula (1), R １ , R ２ are each independently a hydrogen atom, a monovalent hydrocarbon group having 1 to 24 carbon atoms, a phenyl group, an amino group, or an aminoalkyl group; ３ is a divalent hydrocarbon group having 3 to 24 carbon atoms, and R ４ is a monovalent hydrocarbon group having 1 to 24 carbon atoms, N is a nitrogen atom, Si is a silicon atom, and O is an oxygen atom.

[0014] According to the present invention, it is possible to provide a copper-clad laminate that has little warpage and can suppress transmission loss in a wiring board on which a high-frequency circuit is formed, and a method for manufacturing the same.

[0015] 1 is a schematic cross-sectional view of a copper-clad laminate according to an embodiment.

[0016] Hereinafter, a copper-clad laminate and a method for manufacturing the same, which are modes for carrying out the present invention (hereinafter referred to as embodiments), will be described in detail. The following embodiments are examples for explaining the present invention, and are not intended to limit the present invention to the following content. The present invention can be carried out with appropriate modifications within the scope of its gist.

[0017] 1 , the copper clad laminate 10 of the embodiment includes a dielectric film 11, an adhesive layer 13 formed on one side of the dielectric film 11, and a copper layer 15 disposed on the side of the adhesive layer 13 opposite to the side on which the dielectric film 11 is disposed. Here, the dielectric film 11 and the adhesive layer 13 are electrically insulating layers of the copper clad laminate 10. The copper layer 15 is a conductive layer of the copper clad laminate 10.

[0018] The dielectric film 11, adhesive layer 13, and copper layer 15 will be described below.

[0019] (Dielectric Film 11) From the viewpoint of reducing the dielectric constant and the dielectric dissipation factor of the electrical insulating layers constituting the copper-clad laminate 10, the dielectric film 11 has a dielectric constant of 3.5 or less and a dielectric dissipation factor of 0.0030 or less at 23±5°C, a relative humidity of 50±5%, and a frequency of 10 GHz. Specifically, the dielectric constant of the dielectric film 11 is preferably 1.5 or more and 3.5 or less and a dielectric dissipation factor of 0.0005 or more and 0.0030 or less, more preferably 1.5 or more and 3.4 or less and a dielectric dissipation factor of 0.0005 or more and 0.0027 or less, still more preferably 1.5 or more and 2.3 or less and a dielectric dissipation factor of 0.0005 or more and 0.0020 or less, and particularly preferably 1.5 or more and 2.1 or less and a dielectric dissipation factor of 0.0005 or more and 0.0012 or less. Examples of materials for the dielectric film 11 include fluorine-containing polymers, cycloolefin polymers, liquid crystal polymers (LCPs), and low-dielectric polyimides with small dielectric loss tangents. From the viewpoint of reducing warping of the copper-clad laminate 10, the material for the dielectric film 11 is preferably a liquid crystal polymer or a low-dielectric polyimide. From the viewpoint of reducing the dielectric constant and dielectric loss tangent of the electrical insulating layer constituting the copper-clad laminate 10, the material for the dielectric film 11 is preferably a fluorine-containing polymer. The material for the dielectric film 11 may be composed of two or more materials. Note that a relative humidity of 50±5% is also expressed as 50±5% RH. The frequency used to measure the dielectric constant and dielectric loss tangent is 10 GHz, in accordance with standards established by IEC, ASTM, and others.

[0020] From the viewpoint of suppressing warping of the copper-clad laminate 10 and improving processability, the thickness of the dielectric film 11 is preferably, for example, 5 μm or more and 50 μm or less, more preferably 5 μm or more and 25 μm or less, and even more preferably 5 μm or more and 12.5 μm or less.

[0021] From the viewpoint of uniformly forming the adhesive layer 13 on the surface of the dielectric film 11, it is preferable that the surface of the dielectric film 11 on which the adhesive layer 13 is to be formed be subjected to a modification treatment. Examples of modification treatments include plasma treatment and corona treatment. From the viewpoint of improving the adhesion between the adhesive layer 13 and the dielectric film 11, modification treatment by plasma treatment is preferable. From the viewpoint of efficiently introducing hydroxyl groups, carbonyl groups, and carboxyl groups into the surface of the film 11, the gas used for the plasma treatment is preferably a gas containing oxygen, nitrogen, argon, hydrogen, ammonia, etc., and more preferably a gas containing argon. The element(s) and / or compound(s) contained in the gas may be composed of two or more elements and / or compounds. Examples of devices used for the plasma treatment include a vacuum plasma device and an atmospheric pressure plasma device.

[0022] (Adhesive Layer 13) The adhesive layer 13 contains at least one of a silane coupling agent and a bismaleimide resin. Examples of the silane coupling agent contained in the adhesive layer 13 include a silane coupling agent represented by formula (1).

[0023]

[0024] R in formula (1) １ , R ２ are each independently a hydrogen atom, a monovalent hydrocarbon group having 1 to 24 carbon atoms, a phenyl group, an amino group, or an aminoalkyl group. Examples of the monovalent hydrocarbon group having 1 to 24 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an n-hexyl group, and an isohexyl group. Examples of the aminoalkyl group include an aminomethyl group and an aminoethyl group. From the viewpoint of increasing the reactivity of the silane coupling agent, R １ and R ２are preferably each independently a hydrogen atom, an amino group, an aminomethyl group, or an aminoethyl group. １ and R ２ At least one of these is preferably a hydrogen atom.

[0025] R ３ is a divalent hydrocarbon group having 3 to 24 carbon atoms. From the viewpoint of increasing the reactivity of the silane coupling agent, R ３ is preferably a divalent hydrocarbon group having 3 to 8 carbon atoms.

[0026] R ４ is a monovalent hydrocarbon group having 1 to 24 carbon atoms. From the viewpoint of increasing the reactivity of the silane coupling agent, R ４ is preferably a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, or an isobutyl group.

[0027] N is a nitrogen atom, Si is a silicon atom, and O is an oxygen atom.

[0028] Specific examples of silane coupling agents include 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-8-aminooctyltriethoxysilane, and N-2-(aminoethyl)-8-aminooctyltrimethoxysilane. Because these silane coupling agents contain amino groups, they are highly reactive with functional groups such as hydroxyl groups, carbonyl groups, and carboxyl groups introduced onto the surface of the film 11. This allows the adhesive layer 13 containing the silane coupling agent to exhibit adhesion to the dielectric film 11.

[0029] Examples of the bismaleimide resin contained in the adhesive layer 13 include bismaleimide resins obtained by polymerizing a bismaleimide having a main chain and maleimide groups at both ends of the main chain. From the viewpoint of reducing the parasitic capacitance and transmission loss of the wiring board, the bismaleimide resin contained in the adhesive layer 13 of the copper-clad laminate 10 constituting the wiring board preferably has a low dielectric constant and a small dielectric dissipation factor. Examples of bismaleimide resins having a low dielectric constant and a small dielectric dissipation factor include bismaleimide resins obtained by polymerizing a bismaleimide having a symmetrical main chain molecular structure, bismaleimide resins having few polar functional groups, and bismaleimide resins having a symmetrical main chain molecular structure and few polar functional groups. Furthermore, the glass transition temperature of the bismaleimide resin contained in the adhesive layer 13 is preferably a temperature equal to or lower than the heating temperature in the heating and pressurizing step described below. Specifically, the glass transition temperature is preferably 110°C or lower, more preferably 80°C or lower, even more preferably 30°C to 50°C, and particularly preferably 35°C to 45°C. The bismaleimide resin having such a glass transition temperature spreads to every corner along the irregularities on the surface of the copper layer 15. This improves the adhesion between the adhesive layer 13 and the copper layer 15.

[0030] Examples of such bismaleimide resins include ULTIMID 3000S (manufactured by ABC NANOTECH CO., LTD., glass transition temperature 41°C), SFR-2300MR-T (manufactured by Resonac Corporation, glass transition temperature 39°C), and SLK-3000-T50 (manufactured by Shin-Etsu Chemical Co., Ltd., glass transition temperature 40°C). The glass transition temperature can be obtained by dynamic viscoelasticity measurement.

[0031] The bismaleimide resin contained in the adhesive layer 13 has a dielectric constant of 2.7 or less and a dielectric dissipation factor of 0.0021 or less at 23±5°C, 50±5% RH, and a frequency of 10 GHz. Specifically, the dielectric constant is preferably 1.5 or more and 2.7 or less and the dielectric dissipation factor is preferably 0.0005 or more and 0.0021 or less, and more preferably 1.5 or more and 2.6 or less and the dielectric dissipation factor is preferably 0.0010 or more and 0.0020 or less.

[0032] The adhesive layer 13 may contain both the above-mentioned silane coupling agent and bismaleimide resin. From the viewpoint of improving the adhesion between the dielectric film 11 and the copper layer 15, the weight ratio (wt%) of the silane coupling agent to the bismaleimide resin contained in the adhesive layer 13 is preferably 5:95 to 95:5, more preferably 5:95 to 30:70, and even more preferably 5:95 to 10:90.

[0033] The silane coupling agent contained in the adhesive layer 13 may include two or more types of silane coupling agents. The bismaleimide resin contained in the adhesive layer 13 may include two or more types of bismaleimide resins.

[0034] From the viewpoint of improving the adhesion between the dielectric film 11 and the copper layer 15, the thickness of the adhesive layer 13 is, for example, 0.01 μm or more and 7 μm or less, preferably 0.01 μm or more and 3 μm or less, more preferably 0.01 μm or more and 2 μm or less, and even more preferably 0.01 μm or more and 0.5 μm or less.

[0035] The adhesive layer 13 containing at least one of the above-mentioned silane coupling agent and bismaleimide resin has excellent adhesion to the dielectric film 11 and the copper layer 15. As a result, the dielectric film 11 and the copper layer 15 exhibit excellent adhesion via the adhesive layer 13.

[0036] (Copper layer 15) The copper layer 15 is composed of copper foil having a matte surface. The adhesive layer 13 is formed on the matte surface of the copper foil that constitutes the copper layer 15. The dielectric film 11 is disposed on the surface of the adhesive layer 13 opposite to the surface on which the copper layer 15 (copper foil) is disposed.

[0037] From the viewpoint of reducing transmission loss of the wiring board, the roughness of the matte surface of the copper layer 15 is, in terms of ten-point average roughness (Rzjis) measured in accordance with JIS standard B0601 2001 (ISO 4287 1997), 1.5 μm or less, preferably 1.0 μm or less, more preferably 0.8 μm or less, and even more preferably 0.5 μm or less.

[0038] The thickness of the copper layer 15 is preferably 2 μm or more and 50 μm or less, more preferably 2 μm or more and 35 μm or less, and even more preferably 2 μm or more and 18 μm or less, from the viewpoint of easily forming wiring that constitutes a circuit by etching the copper layer 15. The copper foil that constitutes the copper layer is a rolled copper foil or an electrolytic copper foil.

[0039] The electrical insulating layer constituting such copper-clad laminate 10 has a dielectric constant of 3.5 or less and a dielectric dissipation factor of 0.0030 or less at 23±5°C, 50±5% RH, and a frequency of 10 GHz. Specifically, the dielectric constant is preferably 1.5 or more and 3.5 or less and the dielectric dissipation factor is 0.0005 or more and 0.0030 or less, more preferably 1.5 or more and 3.4 or less and the dielectric dissipation factor is 0.0005 or more and 0.0027 or less, even more preferably 1.5 or more and 2.3 or less and the dielectric dissipation factor is 0.0005 or more and 0.0020 or less, and particularly preferably 1.5 or more and 2.1 or less and the dielectric dissipation factor is 0.0005 or more and 0.0012 or less.

[0040] Furthermore, the copper-clad laminate 10, which includes such a dielectric film 11, an adhesive layer 13 formed on one side of the dielectric film 11, and a copper layer 15 disposed on the side of the adhesive layer 13 opposite to the side on which the dielectric film 11 is disposed, exhibits little warping. This allows fine wiring to be formed with high precision on the copper layer 15 of the copper-clad laminate 10. Furthermore, because the electrical insulating layer constituting the copper-clad laminate 10 has a low dielectric constant and a small dielectric loss tangent, the transmission loss of a wiring board formed by patterning the copper layer 15 of the copper-clad laminate 10 can be reduced.

[0041] The copper-clad laminate 10 according to the embodiment has been described above, but another adhesive layer 13 may be formed on the surface of the dielectric film 11 on which the adhesive layer 13 is not formed, and another copper layer 15 may be disposed thereon. Furthermore, before forming this other adhesive layer 13 on the dielectric film 11, the surface of the dielectric film 11 may be subjected to plasma treatment or corona treatment. This allows the other adhesive layer 13 to be formed uniformly on the surface of the dielectric film 11, thereby enhancing the adhesion between the other adhesive layer 13 and the dielectric film 11.

[0042] Furthermore, an adhesive film or prepreg may be disposed on the surface of the dielectric film 11 on which the adhesive layer 13 is not formed. Another copper-clad laminate 10 can be stacked via such a film or prepreg.

[0043] An example of an adhesive film is a double-sided adhesive sheet in which thermoplastic resin layers are formed on both sides of a film-like core material. The resin that makes up the thermoplastic resin layer is made of, for example, thermoplastic polyimide. The film-like core material is made of, for example, a thermosetting polyimide film. This double-sided adhesive sheet is placed on the side of the dielectric film 11 on which the adhesive layer 13 is not formed, and then heated and pressurized. This melts the resin layer and bonds it to the dielectric film 11.

[0044] An example of an adhesive prepreg is an insulating and adhesive sheet obtained by impregnating glass cloth with an insulating epoxy resin or the like. Such a prepreg is placed on the side of the dielectric film 11 on which the adhesive layer 13 is not formed, and then heated and pressurized. This melts the resin impregnated in the glass cloth and bonds it to the dielectric film 11. The cured state of the resin that makes up the prepreg is a semi-cured state (B stage) in which the resin curing reaction has progressed partway.

[0045] Furthermore, before placing the adhesive film or prepreg, the surface of the dielectric film 11 may be subjected to plasma treatment or corona treatment, which can enhance the adhesion between the dielectric film 11 and the adhesive film or prepreg.

[0046] [Method for Manufacturing Copper-Clad Laminate 10] The method for manufacturing the copper-clad laminate 10 includes an adhesive layer forming step, a dielectric film arranging step, and a heating and pressing step.

[0047] (Adhesive Layer Forming Step) An adhesive containing at least one of a silane coupling agent represented by formula (1) and a bismaleimide resin is applied to the matte surface of the copper foil constituting the copper layer 15, and heated at 60°C to 130°C for 1 minute to 30 minutes to form the adhesive layer 13. From the viewpoint of reducing transmission loss of the wiring board, the copper layer 15 is composed of a copper foil having a matte surface with a ten-point average roughness (Rzjis) of 1.5 μm or less as measured in accordance with JIS standard B0601 2001 (ISO 4287 1997).

[0048]

[0049] In formula (1), R １ , R ２ are each independently a hydrogen atom, a monovalent hydrocarbon group having 1 to 24 carbon atoms, a phenyl group, an amino group, or an aminoalkyl group; ３ is a divalent hydrocarbon group having 3 to 24 carbon atoms, and R ４ is a monovalent hydrocarbon group having 1 to 24 carbon atoms, N is a nitrogen atom, Si is a silicon atom, and O is an oxygen atom.

[0050] (Dielectric Film Arrangement Step) A dielectric film 11 having a dielectric constant of 3.5 or less and a dielectric loss tangent of 0.0030 or less at 23±5° C., 50±5% RH, and a frequency of 10 GHz is arranged on the adhesive layer 13 .

[0051] (Heating and Pressurizing Step) The obtained laminate is heated and pressed under conditions of a heating temperature of 40°C to 110°C, a pressing pressure of 0.01 MPa to 5.0 MPa, and a heating and pressing time of 0.01 seconds to 2 minutes to obtain a copper-clad laminate 10. From the viewpoint of reducing warping of the copper-clad laminate 10, the heating temperature is preferably 40°C to 110°C, more preferably 50°C to 110°C, and even more preferably 50°C to 100°C. The processing time can be set depending on the heating temperature and the applied pressure. For example, under conditions of 80°C and 0.5 MPa, the processing time is 10 seconds.

[0052] When producing a sheet of copper-clad laminate 10, the copper-clad laminate 10 can be produced using a press molding machine. In this case, the heating and pressing time is preferably 5 seconds to 2 minutes, and more preferably 10 seconds to 1 minute, from the viewpoint of reducing warping of the copper-clad laminate 10. When producing a long copper-clad laminate 10, the long copper-clad laminate 10 can be produced using a roll laminator. In this case, the heating and pressing time is preferably 0.01 seconds to 30 seconds, and more preferably 0.03 seconds to 20 seconds, from the viewpoint of reducing warping of the copper-clad laminate 10.

[0053] In the copper-clad laminate 10 obtained by this manufacturing method, the heating temperature in the heating and pressing step is 40°C or higher and 110°C or lower, so residual stress due to shrinkage after heating and cooling is less likely to occur in the dielectric film 11. As a result, warping of the copper-clad laminate 10 is reduced.

[0054] In the adhesive layer forming step, an organic solvent such as acetone, methyl ethyl ketone, isopropyl alcohol, or toluene may be added to the adhesive to uniformly apply the adhesive layer 13 to the matte surface of the copper foil. The concentration of the silane coupling agent and / or bismaleimide resin in the adhesive containing an organic solvent is preferably 1 wt % or more and 30 wt % or less. The dielectric film 11 used in the dielectric film disposing step may be subjected to a modification treatment such as a corona treatment or a plasma treatment to uniformly form the adhesive layer 13 on the surface of the dielectric film 11. In addition, in the heating and pressing step, heating and pressing may be performed in a nitrogen atmosphere to prevent oxidation of the laminate.

[0055] Another method for manufacturing the copper clad laminate 10 includes an adhesive layer forming step, a copper foil arranging step, and a heating and pressing step.

[0056] (Adhesive Layer Forming Process) An adhesive containing at least one of a silane coupling agent represented by formula (1) and a bismaleimide resin is applied to one surface of the dielectric film 11 and heated at 60°C to 150°C for 1 minute to 30 minutes to form the adhesive layer 13. From the viewpoint of lowering the dielectric constant and reducing the dielectric loss tangent of the electrical insulating layer that constitutes the copper-clad laminate 10, the dielectric film 11 has a dielectric constant of 3.5 or less and a dielectric loss tangent of 0.0030 or less at 23±5°C, 50±5% RH, and a frequency of 10 GHz.

[0057]

[0058] In formula (1), R １ , R ２ are each independently a hydrogen atom, a monovalent hydrocarbon group having 1 to 24 carbon atoms, a phenyl group, an amino group, or an aminoalkyl group; ３ is a divalent hydrocarbon group having 3 to 24 carbon atoms, and R ４ is a monovalent hydrocarbon group having 1 to 24 carbon atoms, N is a nitrogen atom, Si is a silicon atom, and O is an oxygen atom.

[0059] (Copper Foil Placement Step) Copper foil as copper layer 15 is placed on adhesive layer 13 formed on one side of dielectric film 11 so that the matte side of the copper foil is in contact with adhesive layer 13. From the viewpoint of reducing transmission loss of the wiring board, the copper foil has a matte side with a ten-point average roughness (Rzjis) of 1.5 μm or less as measured in accordance with JIS standard B0601 2001 (ISO 4287 1997). Preferred copper foils have a matte side of 1.0 μm or less, more preferably a matte side of 0.8 μm or less, and even more preferably a matte side of 0.5 μm or less.

[0060] (Heating and Pressing Step) Next, the obtained laminate is heated and pressed under conditions of a heating temperature of 40°C to 110°C, a pressing pressure of 0.01 MPa to 5.0 MPa, and a heating and pressing time of 0.01 seconds to 2 minutes to obtain a copper-clad laminate 10. From the viewpoint of reducing warping of the copper-clad laminate 10, the heating temperature is preferably 40°C to 110°C, more preferably 50°C to 110°C, and even more preferably 50°C to 100°C. The processing time can be set depending on the heating temperature and the applied pressure. For example, under conditions of 80°C and 0.5 MPa, the processing time is 10 seconds.

[0061] When producing a sheet of copper-clad laminate 10, the copper-clad laminate 10 can be produced using a press molding machine. In this case, the heating and pressing time is preferably 5 seconds to 2 minutes, and more preferably 10 seconds to 1 minute, from the viewpoint of reducing warping of the copper-clad laminate 10. When producing a long copper-clad laminate 10, the long copper-clad laminate 10 can be produced using a roll laminator. In this case, the heating and pressing time is preferably 0.01 seconds to 30 seconds, and more preferably 0.03 seconds to 20 seconds, from the viewpoint of reducing warping of the copper-clad laminate 10.

[0062] In the copper-clad laminate 10 obtained by this manufacturing method, the heating temperature in the heating and pressing step is 40°C or higher and 110°C or lower, so residual stress due to shrinkage after heating and cooling is less likely to occur in the dielectric film 11. As a result, warping of the copper-clad laminate 10 is reduced.

[0063] The dielectric film 11 used in the adhesive layer formation step may be subjected to a surface modification treatment such as corona treatment or plasma treatment in order to uniformly form the adhesive layer 13 on the surface of the dielectric film 11. Furthermore, an organic solvent such as acetone, methyl ethyl ketone, isopropyl alcohol, or toluene may be added to the adhesive in order to uniformly apply the adhesive layer 13 to the surface of the dielectric film 11. The concentration of the silane coupling agent and / or bismaleimide resin in the adhesive containing an organic solvent is preferably 1 wt % or more and 30 wt % or less. Furthermore, in the heating and pressing step, heating and pressing may be performed in a nitrogen atmosphere in order to prevent oxidation of the laminate.

[0064] The above describes two methods for manufacturing copper-clad laminates 10. These manufacturing methods can also be used to produce copper-clad laminates in which adhesive layers 13 and copper layers 15 are formed in this order on both sides of dielectric film 11.

[0065] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples in any way.

[0066] Example 1 (Preparation of copper-clad laminate 10) (1) Preparation of adhesive layer 13 (1-1) Preparation of silane coupling agent solution In a container, 97.5 g of 100 wt % isopropyl alcohol as an organic solvent and 2.5 g of 100 wt % silane coupling agent (KBM-603 manufactured by Shin-Etsu Chemical Co., Ltd.) were added and mixed to prepare a silane coupling agent solution containing 2.5 wt % of the silane coupling agent. Note that KBM-603 manufactured by Shin-Etsu Chemical Co., Ltd. is N-2-(aminoethyl)-3-aminopropyltrimethoxysilane.

[0067] (1-2) Formation of Adhesive Layer 13 The prepared silane coupling agent solution was applied to one side of a 12 μm thick fluororesin film (Fluon+ (registered trademark) EA-2000 manufactured by AGC) to form the dielectric film 11, using a bar coater, so that the thickness after heating would be 0.02 μm. After application, the film was heated at 130°C for 3 minutes, yielding a laminate in which an adhesive layer 13 was formed on one side of the fluororesin film. The fluororesin film used had a dielectric constant of 2.06 and a dielectric dissipation factor of 0.0011 at 23±5°C, 50±5% RH, and a frequency of 10 GHz.

[0068] (1-3) Bonding of a Laminate Having an Adhesive Layer 13 Formed thereon and a Copper Foil (Copper Layer 15) A copper foil (electrolytic copper foil CF-T9DA-SV, manufactured by Fukuda Metal Foil Co., Ltd.) having a thickness of 18 μm was placed on the adhesive layer 13 so that the matte side of the copper foil was in contact with the adhesive layer 13. Thereafter, using a press, the resulting laminate was heated and pressed under conditions of a heating temperature of 80°C, a pressing pressure of 0.5 MPa, and a heating and pressing time of 10 seconds, to obtain a copper-clad laminate 10. The ten-point average roughness (Rzjis) of the copper foil used, measured according to JIS standard B0601 2001 (ISO 4287 1997), was 0.6 μm.

[0069] <Peel Strength> The peel strength of the copper layer 15 of the copper-clad laminate 10 was measured in accordance with Section 8.1 of JIS C6471.

[0070] Specifically, a measurement sample was prepared by cutting the copper-clad laminate 10 into a 10 mm x 50 mm rectangle. Next, a stainless steel reinforcing plate was attached to the film surface of the measurement sample via double-sided adhesive tape. The measurement sample was then measured for 90° peel strength using an Autograph AGS-500 manufactured by Shimadzu Corporation under the following measurement conditions: copper stripping, test speed 50 mm / min. Measurements were performed on five samples (n = 5), and the average value was taken as the peel strength of the copper-clad laminate 10 of Example 1. The 90° direction refers to the direction perpendicular to the surface of the measurement sample. The evaluation criteria were as follows: Excellent: peel strength of 0.4 N / cm or more; Good: peel strength of less than 0.4 N / cm and 0.1 N / cm or more; Poor: peel strength of less than 0.1 N / cm.

[0071] The peel strength of the copper clad laminate 10 of Example 1 was 1.0 N / cm, which was excellent.

[0072] <Warpage> The warpage of the copper-clad laminate 10 was measured and evaluated according to the following procedure. First, a copper-clad laminate 10 cut into a 100 mm x 100 mm square was prepared. Next, the copper-clad laminate 10 was left on a horizontal table for 24 hours in an atmosphere of 20°C ± 5°C and 65% ± 20% relative humidity, with the copper layer 15 facing upward. The distance from the main surface of the table to the copper-clad laminate 10 was then measured at four points on the corners of the copper-clad laminate 10 using a scale. The average of the measured values ​​at the four points was then applied to the following evaluation criteria to evaluate the warpage of the copper-clad laminate 10. Evaluation criteria: Excellent: Less than 10 mm; Poor: 10 mm or more.

[0073] The warpage of the copper clad laminate 10 of Example 1 was 5.3 mm, which was excellent.

[0074] <Dielectric Constant and Dielectric Loss Tangent> The dielectric constant and dielectric loss tangent of the electrical insulating layer constituting the copper-clad laminate 10 were measured and evaluated by the SPDR (split post dielectric resonator) method. (1) Measurement Sample The copper-clad laminate 10 of Example 1 cut into a 100 mm x 100 mm square was heated at 200°C for 60 minutes. Thereafter, the copper layer 15 (copper foil) constituting the copper-clad laminate 10 was entirely removed by etching, and the resulting laminate was left to stand in an atmosphere of 23±5°C and 50±5% RH for 24 hours or more to prepare a measurement sample.

[0075] (2) Measurement Method The measurement sample prepared in (1) was attached to a dedicated jig (SPDR fixture), and the dielectric constant and dielectric loss tangent of the electrical insulating layer constituting the copper-clad laminate 10 were measured using a Network Analyzer N5230A manufactured by Agilent Technologies. The measurement conditions were an atmosphere of 23±5°C, 50±5% RH, and a frequency of 10 GHz. Measurement was performed on five samples, and the average values ​​were used as the dielectric constant and dielectric loss tangent of the measured sample.

[0076] (3) Evaluation Criteria The evaluation criteria for dielectric constant were as follows: Excellent: 3.30 or less, Good: 3.31 to 3.50, Poor: 3.51 or more. The evaluation criteria for dielectric loss tangent were as follows: Excellent: 0.0035 or less, Good: 0.0036 to 0.0040, Poor: 0.0041 or more.

[0077] The dielectric constant of the electrical insulating layer constituting the copper-clad laminate 10 of Example 1 at 23±5°C, 50±5% RH, and a frequency of 10 GHz was 2.10, which was excellent. The dielectric dissipation factor was 0.0017, which was excellent.

[0078] As described above, it was found that the copper-clad laminate 10 of Example 1 had little warpage. It was also found that the electrical insulating layer constituting the copper-clad laminate 10 had a low dielectric constant and a small dielectric dissipation factor. It was also found that the peel strength between the dielectric film 11 and the copper layer 15 was high. A copper-clad laminate 10 with little warpage allows high-definition wiring to be formed on the copper layer 15. It also allows efficient production of wiring boards. It also improves the yield of the produced wiring boards. Furthermore, a wiring board made from a copper-clad laminate 10 with an electrical insulating layer having a low dielectric constant and a small dielectric dissipation factor can suppress transmission loss. Furthermore, because the peel strength between the dielectric film 11 and the copper layer 15 of the copper-clad laminate 10 is high, the formed wiring is also less likely to peel from the dielectric film 11.

[0079] (Examples 2 and 3) Copper-clad laminates 10 of Examples 2 and 3 were each produced using the same method as that for producing copper-clad laminate 10 of Example 1, except that the type of silane coupling agent constituting adhesive layer 13 was changed. Copper-clad laminates 10 of Examples 2 and 3 were also evaluated using the same evaluation method as copper-clad laminate 10 of Example 1. The results are shown in Table 1. Table 1 reveals that the electrical insulating layers constituting copper-clad laminates 10 of Examples 2 and 3 also had low dielectric constants and small dielectric dissipation factors, and that the copper-clad laminates 10 exhibited little warpage. It was also found that the copper-clad laminates 10 of Examples 2 and 3 had high peel strength. In particular, it was found that the copper-clad laminates 10 of Examples 1 and 3, which used a silane coupling agent with a long molecular chain, exhibited high peel strength.

[0080] The copper-clad laminates 10 of Examples 1 to 3 allow high-definition wiring to be formed on the copper layer 15. Furthermore, wiring boards constructed from these copper-clad laminates 10 can suppress transmission loss. Furthermore, because the peel strength of the copper-clad laminate 10 is high, the formed wiring is also less likely to peel off from the dielectric film 11. KBM-903 manufactured by Shin-Etsu Chemical Co., Ltd., used in Example 2, is 3-aminopropyltrimethoxysilane. KBM-6803 manufactured by Shin-Etsu Chemical Co., Ltd., used in Example 3, is N-2-(aminoethyl)-8-aminooctyltrimethoxysilane.

[0081]

[0082] Example 4 Copper-clad laminates 10 of Example 4 were produced in the same manner as copper-clad laminates 10 of Example 1, except that the composition of adhesive layer 13 was changed from a silane coupling agent to a bismaleimide resin and the thickness of adhesive layer 13 was changed from 0.02 μm to 0.1 μm. The bismaleimide resin solution used in Example 4 was a bismaleimide resin solution containing 2.0 wt % bismaleimide resin. This solution was obtained by adding 96 g of 100 wt % toluene as an organic solvent and 4 g of 50 wt % bismaleimide resin (SLK-3000-T50 manufactured by Shin-Etsu Chemical Co., Ltd.) to a container and mixing them.

[0083] The copper clad laminate 10 of Example 4 was evaluated using the same evaluation method as the copper clad laminate 10 of Example 1. The results are shown in Table 2. It was found that the copper clad laminate 10 of Example 4, which used only the bismaleimide resin, also had small warpage, just like Example 1, which used only the silane coupling agent.

[0084] (Example 5) The copper-clad laminates 10 of Example 5 were produced in the same manner as the copper-clad laminate 10 of Example 1, except that the composition of the adhesive layer 13 was changed from a composition containing only a silane coupling agent to a composition containing a silane coupling agent and a bismaleimide resin, and the thickness of the adhesive layer 13 was changed from 0.02 μm to 0.1 μm. The mixed solution used in Example 5 was obtained by adding and mixing 96.1 g of 100 wt % toluene as an organic solvent, 0.1 g of 100 wt % silane coupling agent (KBM-6803 manufactured by Shin-Etsu Chemical Co., Ltd.), and 3.8 g of 50 wt % bismaleimide resin (SLK-3000-T50 manufactured by Shin-Etsu Chemical Co., Ltd.). The concentration of this mixed solution was 2.0 wt %. The weight ratio (wt %) of the silane coupling agent to the bismaleimide resin contained in the adhesive layer 13 formed using this mixed solution was 5:95.

[0085] The copper clad laminate 10 of Example 5 was also evaluated by the same evaluation method as the copper clad laminate 10 of Example 1. The results are shown in Table 2. It was found that the copper clad laminate 10 of Example 5 also had small warpage, as in Example 1. It was also found that the peel strength of the copper clad laminate 10 of Example 5, in which the adhesive layer 13 contained a silane coupling agent and a bismaleimide resin, was higher than the peel strength of Example 4, in which the adhesive layer 13 contained only a bismaleimide resin.

[0086] (Examples 6, 7, 8) Copper-clad laminates 10 of Examples 6, 7, and 8 were each produced using the same method as that for producing copper-clad laminate 10 of Example 5, except that the ratio of the silane coupling agent and bismaleimide resin in the composition containing the silane coupling agent and bismaleimide resin that constituted adhesive layer 13 was changed. The weight ratio (wt%) of the silane coupling agent and bismaleimide resin was also changed for each Example. The concentration of the mixed solution containing the silane coupling agent and bismaleimide resin used in Examples 6, 7, and 8 was 2.0 wt%.

[0087] The copper-clad laminates 10 of Examples 6, 7, and 8 were evaluated using the same evaluation method as the copper-clad laminate 10 of Example 1. The results are shown in Table 2. It was found that the peel strength of the copper-clad laminate 10 of Example 6, in which the weight ratio (wt%) of the silane coupling agent to the bismaleimide resin was 10:90, was higher than the peel strengths of Examples 5, 7, and 8. It was also found that the warpage of Example 7, in which the weight ratio (wt%) of the silane coupling agent to the bismaleimide resin was 50:50, was smaller than that of Examples 5, 6, and 8.

[0088]

[0089] (Examples 9 and 10) Copper-clad laminates 10 of Examples 9 and 10 were each produced in the same manner as copper-clad laminate 10 of Example 6, except that the ratio of the silane coupling agent and the bismaleimide resin in the composition containing the silane coupling agent and the bismaleimide resin that constitutes adhesive layer 13 was kept unchanged and the type of bismaleimide resin was changed.

[0090] The mixed solution used in Example 9 was obtained by mixing 96.75 g of 100 wt % toluene as an organic solvent, 0.2 g of 100 wt % silane coupling agent (KBM-6803 manufactured by Shin-Etsu Chemical Co., Ltd.), and 3.05 g of 59 wt % bismaleimide resin (SFR-2300MR-T manufactured by Resonac Corporation). The concentration of this mixed solution was 2.0 wt %. The weight ratio (wt %) of the silane coupling agent to the bismaleimide resin contained in the adhesive layer 13 formed using this mixed solution was 10:90.

[0091] The mixed solution used in Example 10 was obtained by adding and mixing 96.85 g of 100 wt % toluene as an organic solvent, 0.2 g of 100 wt % silane coupling agent (KBM-6803 manufactured by Shin-Etsu Chemical Co., Ltd.), and 2.95 g of 61 wt % bismaleimide resin (ULTIMID 3000S manufactured by ABC NANOTECH CO., LTD.). The concentration of this mixed solution was 2.0 wt %. The weight ratio (wt %) of the silane coupling agent and bismaleimide resin contained in the adhesive layer 13 formed using this mixed solution was 10:90. The bismaleimide resin used in Example 10 was composed of an aliphatic bismaleimide oligomer.

[0092] The copper-clad laminates 10 of Examples 9 and 10 were evaluated using the same evaluation method as the copper-clad laminate 10 of Example 1. The results are shown in Table 3. It was found that the peel strength of the copper-clad laminate 10 of Example 10, which had an adhesive layer 13 containing a bismaleimide resin composed of an aliphatic bismaleimide oligomer, was higher than that of Examples 6 and 9. It was also found that the warpage of the copper-clad laminates 10 of Examples 9 and 10 was small.

[0093]

[0094] (Examples 11, 12, 13) The copper-clad laminates 10 of Examples 11, 12, and 13 were each produced using the same method as the copper-clad laminate 10 of Example 6, except that the processing conditions for bonding the dielectric film 11 and copper foil (copper layer 15) that constitute the copper-clad laminate 10 were changed. Here, the processing conditions for producing the copper-clad laminate 10 of Example 11 were a heating temperature of 40°C, a pressurized pressure of 0.5 MPa, and a heating and pressurizing time of 10 seconds. The processing conditions for producing the copper-clad laminate 10 of Example 12 were a heating temperature of 60°C, a pressurized pressure of 0.5 MPa, and a heating and pressurizing time of 10 seconds. The processing conditions for producing the copper-clad laminate 10 of Example 13 were a heating temperature of 100°C, a pressurized pressure of 0.5 MPa, and a heating and pressurizing time of 10 seconds.

[0095] The copper-clad laminates 10 of Examples 11, 12, and 13 were evaluated using the same evaluation method as the copper-clad laminate 10 of Example 1. The results are shown in Table 4. It was found that increasing the temperature during lamination increases the peel strength of the copper-clad laminate 10. Furthermore, the warpage of the copper-clad laminate 10 of Example 13 also tends to increase as the temperature of the processing conditions increases, but it was found that the warpage was within a range that could be used in practical applications.

[0096]

[0097] (Examples 14 and 15) Copper-clad laminates 10 of Examples 14 and 15 were each produced in the same manner as copper-clad laminate 10 of Example 6, except that adhesive layer 13 was formed on one side of preheat-treated dielectric film 11. Dielectric film 11 used in Example 14 was heat-treated at 100°C for 10 minutes before use. Dielectric film 11 used in Example 15 was heat-treated at 150°C for 10 minutes before use.

[0098] The copper clad laminates 10 of Examples 14 and 15 were evaluated using the same evaluation method as the copper clad laminate 10 of Example 1. The results are shown in Table 5. It was found that the copper clad laminates 10 of Examples 14 and 15 had less warpage than Example 6. It was also found that the copper clad laminate 10 of Example 14 had higher peel strength and less warpage than Example 6. One reason for the less warpage of the copper clad laminates 10 of Examples 14 and 15 is that they used a dielectric film 11 in which residual stress had been removed by heat treatment.

[0099]

[0100] (Examples 16 and 17) The copper-clad laminates 10 of Examples 16 and 17 were each produced in the same manner as the copper-clad laminate 10 of Example 6, except that the concentration of the mixed solution containing the silane coupling agent and bismaleimide resin used to form the adhesive layer 13 on one side of the dielectric film 11 and the thickness of the adhesive layer 13 were changed.

[0101] The mixed solution used in Example 16 was obtained by mixing 6.2 g of 100 wt% toluene as an organic solvent, 0.2 g of 100 wt% silane coupling agent (KBM-6803 manufactured by Shin-Etsu Chemical Co., Ltd.), and 3.6 g of 50 wt% bismaleimide resin (SLK-3000-T50 manufactured by Shin-Etsu Chemical Co., Ltd.). The concentration of this mixed solution was 20 wt%. The weight ratio (wt%) of the silane coupling agent to the bismaleimide resin contained in the adhesive layer 13 formed using this mixed solution was 10:90. The thickness of the adhesive layer 13 formed on one side of the dielectric film 11 was 2.0 μm.

[0102] The mixed solution used in Example 17 was obtained by mixing 6.2 g of 100 wt% toluene as an organic solvent, 0.2 g of 100 wt% silane coupling agent (KBM-6803 manufactured by Shin-Etsu Chemical Co., Ltd.), and 3.6 g of 50 wt% bismaleimide resin (SLK-3000-T50 manufactured by Shin-Etsu Chemical Co., Ltd.). The concentration of this mixed solution was 20 wt%. The weight ratio (wt%) of the silane coupling agent to the bismaleimide resin contained in the adhesive layer 13 formed using this mixed solution was 10:90. The thickness of the adhesive layer 13 formed on one side of the dielectric film 11 was 5.0 μm.

[0103] The copper clad laminates 10 of Examples 16 and 17 were evaluated using the same evaluation method as the copper clad laminate 10 of Example 1. The results are shown in Table 6. It was found that the copper clad laminates 10 of Examples 16 and 17 had less warpage than the copper clad laminate 10 of Example 6.

[0104]

[0105] (Example 18) The copper clad laminate 10 of Example 18 was produced in the same manner as the copper clad laminate 10 of Example 16, except that the copper foil used in producing the copper clad laminate 10 was changed from an 18 μm thick electrolytic copper foil CF-T9DA-SV manufactured by Fukuda Metal Foil Co., Ltd. to a 18 μm thick rolled copper foil BHY-82F-HAV2 manufactured by JX Metals Corporation. The ten-point average roughness (Rzjis) of the copper foil used, measured according to JIS standard B0601 2001 (ISO 4287 1997), was 0.8 μm.

[0106] Example 19 Copper-clad laminate 10 of Example 19 was produced in the same manner as copper-clad laminate 10 of Example 17, except that the copper foil used in producing copper-clad laminate 10 was changed from CF-T9DA-SV, an 18 μm thick electrolytic copper foil manufactured by Fukuda Metal Foil Co., Ltd., to BHY-82F-HAV2, an 18 μm thick rolled copper foil manufactured by JX Nippon Mining & Metals Corporation.

[0107] (Example 20) The copper clad laminate 10 of Example 20 was produced in the same manner as the copper clad laminate 10 of Example 16, except that the copper foil used in producing the copper clad laminate 10 was changed from CF-T9DA-SV, an 18 μm thick electrolytic copper foil manufactured by Fukuda Metal Foil Co., Ltd., to CF-T49A-DS-HD2, an 18 μm thick electrolytic copper foil manufactured by Fukuda Metal Foil Co., Ltd. The copper clad laminate 10 of Example 20 was produced in the same manner as the copper clad laminate 10 of Example 16. The ten-point average roughness (Rzjis) of the copper foil used, measured according to JIS standard B0601 2001 (ISO 4287 1997), was 1.3 μm.

[0108] (Example 21) Copper-clad laminate 10 of Example 21 was produced in the same manner as copper-clad laminate 10 of Example 17, except that the copper foil used in producing copper-clad laminate 10 was changed from CF-T9DA-SV manufactured by Fukuda Metal Foil Co., Ltd., having a thickness of 18 μm, to CF-T49A-DS-HD2, an electrolytic copper foil having a thickness of 18 μm, manufactured by Fukuda Metal Foil Co., Ltd. Co., Ltd. Co., Ltd.

[0109] The copper clad laminates 10 of Examples 18 to 21 were evaluated using the same evaluation method as the copper clad laminate 10 of Example 1. The results are shown in Table 7. It was found that the copper clad laminates 10 of Examples 18 to 21 had higher peel strength than the copper clad laminate 10 of Example 16.

[0110]

[0111] (Example 22) Copper-clad laminate 10 of Example 22 was produced in the same manner as copper-clad laminate 10 of Example 6, except that dielectric film 11 used in producing copper-clad laminate 10 was changed from a 12 μm thick fluororesin film (Fluon+ (registered trademark) EA-2000 manufactured by AGC) to a 50 μm thick LCP film (CT-Z manufactured by Kuraray Co., Ltd.) whose surface had been plasma-treated. The LCP film used had a dielectric constant of 3.34 and a dielectric dissipation factor of 0.0018 at 23±5°C, 50±5% RH, and a frequency of 10 GHz.

[0112] (Example 23) The dielectric film 11 used in producing the copper-clad laminate 10 was changed from a 12 μm thick fluororesin film (Fluon+ (registered trademark) EA-2000 manufactured by AGC) to a 50 μm thick LCP film (CT-Z manufactured by Kuraray Co., Ltd.) with a plasma treatment applied to the film surface. In addition, the concentration of the mixed solution containing the silane coupling agent and bismaleimide resin used in forming the adhesive layer 13 on one side of the dielectric film 11, and the thickness of the adhesive layer 13 were changed. Except for these, the copper-clad laminate 10 of Example 23 was produced in the same manner as the copper-clad laminate 10 of Example 6.

[0113] The mixed solution used in Example 23 was obtained by mixing 6.2 g of 100 wt % toluene as an organic solvent, 0.2 g of 100 wt % silane coupling agent (KBM-6803 manufactured by Shin-Etsu Chemical Co., Ltd.), and 3.6 g of 50 wt % bismaleimide resin (SLK-3000-T50 manufactured by Shin-Etsu Chemical Co., Ltd.). The concentration of this mixed solution was 20 wt %. The weight ratio (wt %) of the silane coupling agent to the bismaleimide resin contained in the adhesive layer 13 formed using this mixed solution was 10:90. The thickness of the adhesive layer 13 formed on one side of the dielectric film 11 was 2.0 μm.

[0114] Example 24 The dielectric film 11 used in producing the copper-clad laminate 10 was changed from a 12 μm thick fluororesin film (Fluon+ (registered trademark) EA-2000 manufactured by AGC) to a 50 μm thick LCP film (CT-Z manufactured by Kuraray Co., Ltd.) with a plasma treatment applied to the film surface. In addition, the concentration of the mixed solution containing the silane coupling agent and bismaleimide resin used in forming the adhesive layer 13 on one side of the dielectric film 11, and the thickness of the adhesive layer 13 were changed. Except for these, the copper-clad laminate 10 of Example 24 was produced in the same manner as the copper-clad laminate 10 of Example 6.

[0115] The mixed solution used in Example 24 was obtained by mixing 6.2 g of 100 wt% toluene as an organic solvent, 0.2 g of 100 wt% silane coupling agent (KBM-6803 manufactured by Shin-Etsu Chemical Co., Ltd.), and 3.6 g of 50 wt% bismaleimide resin (SLK-3000-T50 manufactured by Shin-Etsu Chemical Co., Ltd.). The concentration of this mixed solution was 20 wt%. The weight ratio (wt%) of the silane coupling agent to the bismaleimide resin contained in the adhesive layer 13 formed using this mixed solution was 10:90. The thickness of the adhesive layer 13 formed on one side of the dielectric film 11 was 5.0 μm.

[0116] (Example 25) Copper-clad laminate 10 of Example 25 was produced in the same manner as copper-clad laminate 10 of Example 6, except that dielectric film 11 used in producing copper-clad laminate 10 was changed from a 12 μm thick fluororesin film (Fluon+ (registered trademark) EA-2000 manufactured by AGC Corporation) to a 25 μm thick low dielectric polyimide film (IB-142#SW manufactured by Kaneka Corporation) whose surface had been subjected to corona treatment. The low dielectric polyimide film used had a dielectric constant of 3.36 and a dielectric dissipation factor of 0.0027 at 23±5°C, 50±5% RH, and a frequency of 10 GHz.

[0117] (Example 26) The dielectric film 11 used in producing the copper-clad laminate 10 was changed from a 12 μm thick fluororesin film (Fluon+ (registered trademark) EA-2000 manufactured by AGC Corporation) to a 25 μm thick low-dielectric polyimide film (IB-142#SW manufactured by Kaneka Corporation) with a corona treatment applied to the film surface. In addition, the concentration of the mixed solution containing the silane coupling agent and bismaleimide resin used in forming the adhesive layer 13 on one side of the dielectric film 11 and the thickness of the adhesive layer 13 were changed. Except for these, the copper-clad laminate 10 of Example 26 was produced in the same manner as the copper-clad laminate 10 of Example 6.

[0118] The mixed solution used in Example 26 was obtained by mixing 6.2 g of 100 wt% toluene as an organic solvent, 0.2 g of 100 wt% silane coupling agent (KBM-6803 manufactured by Shin-Etsu Chemical Co., Ltd.), and 3.6 g of 50 wt% bismaleimide resin (SLK-3000-T50 manufactured by Shin-Etsu Chemical Co., Ltd.). The concentration of this mixed solution was 20 wt%. The weight ratio (wt%) of the silane coupling agent to the bismaleimide resin contained in the adhesive layer 13 formed using this mixed solution was 10:90. The thickness of the adhesive layer 13 formed on one side of the dielectric film 11 was 2.0 μm.

[0119] The copper clad laminates 10 of Examples 22 to 26 were evaluated using the same evaluation method as the copper clad laminate 10 of Example 1. The results are shown in Table 8. It was found that the copper clad laminates 10 of Examples 22 to 26 had less warpage than the copper clad laminate 10 of Example 6. It was also found that the peel strength increased as the adhesive layer 13 became thicker.

[0120]

[0121] (Comparative Examples 1 and 2) Copper-clad laminates 10 of Comparative Examples 1 and 2 were each produced using the same method as that for producing copper-clad laminate 10 of Example 1, except that the type of silane coupling agent constituting adhesive layer 13 was changed. However, in Comparative Examples 1 and 2, copper layer 15 and dielectric film 11 were not bonded, and copper-clad laminate 10 could not be obtained.

[0122] (Comparative Example 3) Copper-clad laminate 10 of Comparative Example 3 was produced in the same manner as copper-clad laminate 10 of Example 6, except that the processing conditions for bonding dielectric film 11 and copper foil (copper layer 15) constituting copper-clad laminate 10 were changed to a heating temperature of 120°C, a pressure of 0.5 MPa, and a heating and pressing time of 10 seconds. Copper-clad laminate 10 of Comparative Example 3 was also evaluated using the same evaluation method as copper-clad laminate 10 of Example 1. The results are shown in Table 9. Copper-clad laminate 10 of Comparative Example 3 warped more than copper-clad laminate 10 of Example 6, making it difficult to use in practice.

[0123] (Comparative Example 4) A copper-clad laminate 10 was produced without providing an adhesive layer 13 between the dielectric film 11 and the copper layer 15. The bonding conditions were the same as those for the copper-clad laminate 10 of Example 1. However, in Comparative Example 4, as in Comparative Examples 1 and 2, the copper layer 15 and the dielectric film 11 did not bond, and a copper-clad laminate 10 could not be obtained. The results are shown in Table 9.

[0124]

[0125] The KBM-403 manufactured by Shin-Etsu Chemical Co., Ltd. used in Comparative Example 1 is 3-glycidoxypropyltrimethoxysilane. The KBM-503 manufactured by Shin-Etsu Chemical Co., Ltd. used in Comparative Example 2 is 3-methacryloxypropyltrimethoxysilane.

[0126] From the results of the Examples and Comparative Examples, it was found that the peel strength of the copper-clad laminate 10 of the Examples, which used an amino-based silane coupling agent, was higher than the peel strength of the copper-clad laminate 10 of the Comparative Examples, which used an epoxy-based silane coupling agent or a methacrylic-based silane coupling agent. Furthermore, it was found that the warpage of the copper-clad laminate 10 of the Examples, which was bonded at a temperature of 110°C or less, was smaller than the warpage of the copper-clad laminate 10 of the Comparative Examples, which was bonded at a temperature of 120°C or more.

[0127] As described above, it was found that the electrical insulating layer of the copper-clad laminate 10 of the example had a low dielectric constant and a small dielectric dissipation factor, and that the warpage of the copper-clad laminate 10 was small. It was also found that the peel strength between the dielectric film 11 and the copper layer 15 constituting the copper-clad laminate 10 of the example was good. Such a copper-clad laminate 10 allows high-definition circuits to be formed on the copper layer 15. A wiring board constructed from such a copper-clad laminate 10 can suppress transmission loss. Furthermore, because the peel strength between the dielectric film 11 and the copper layer 15 is high, the formed wiring is also less likely to peel from the dielectric film 11.

[0128] The present invention allows various embodiments and modifications without departing from the broad spirit and scope of the present invention. Furthermore, the above-described embodiments are intended to explain the present invention and do not limit the scope of the present invention. That is, the scope of the present invention is defined by the claims, not the embodiments. Various modifications made within the scope of the claims and within the scope of the meaning of the invention equivalent thereto are considered to be within the scope of the present invention.

[0129] This application is based on Japanese Patent Application No. 2024-072385, filed on April 26, 2024. The entire specification, claims, and drawings of Japanese Patent Application No. 2024-072385 are incorporated herein by reference.

[0130] (Appendix) Various aspects of the present disclosure are described below as appendices. (Appendix 1) A copper-clad laminate comprising: a dielectric film having a dielectric constant of 3.5 or less and a dielectric dissipation factor of 0.0030 or less at 23±5°C, 50±5% RH, and a frequency of 10 GHz; an adhesive layer formed on at least one surface of the dielectric film, the adhesive layer containing at least one of a silane coupling agent represented by the following formula (1) and a bismaleimide resin; and a copper layer composed of copper foil having a matte surface with a ten-point average roughness (Rzjis) of 1.5 μm or less as measured in accordance with JIS standard B0601 2001 (ISO 4287 1997), the copper layer being arranged on the surface of the adhesive layer opposite to the surface on which the dielectric film is arranged so that the matte surface is in contact with the surface. In formula (1), R １ , R２ are each independently a hydrogen atom, a monovalent hydrocarbon group having 1 to 24 carbon atoms, a phenyl group, an amino group, or an aminoalkyl group; ３ is a divalent hydrocarbon group having 3 to 24 carbon atoms, and R ４ is a monovalent hydrocarbon group having 1 to 24 carbon atoms, N is a nitrogen atom, Si is a silicon atom, and O is an oxygen atom.

[0131] (Appendix 2) The copper-clad laminate according to Appendix 1, wherein the adhesive layer contains the silane coupling agent and the bismaleimide resin, and a weight ratio (wt%) of the silane coupling agent to the bismaleimide resin is 5:95 to 95:5.

[0132] (Appendix 3) The copper clad laminate according to appendix 1 or 2, wherein the adhesive layer has a thickness of 0.01 μm or more and 7 μm or less.

[0133] (Appendix 4) The copper-clad laminate according to any one of Appendices 1 to 3, which has a warpage of 10 mm or less after being left in an atmosphere of 20±5°C and 65±20% RH for 24 hours.

[0134] (Appendix 5) A method for producing a copper-clad laminate, comprising: an adhesive layer forming step of forming an adhesive layer comprising at least one of a silane coupling agent represented by the following formula (1) and a bismaleimide resin on a matte surface of copper foil, the matte surface having a ten-point average roughness (Rzjis) of 1.5 μm or less as measured in accordance with JIS standard B0601 2001 (ISO 4287 1997); a dielectric film disposing step of disposing, on the adhesive layer, a dielectric film having a dielectric constant of 3.5 or less and a dielectric dissipation factor of 0.0030 or less at 23±5°C, 50±5% RH, and a frequency of 10 GHz; and a heating and pressing step of heating the obtained laminate composed of the copper foil, the adhesive layer, and the dielectric film at a temperature of 40°C or more and 110°C or less, a pressing pressure of 0.01 MPa or more and 5.0 MPa or less, and a heating and pressing time of 0.01 seconds or more and 2 minutes or less. In formula (1), R １ , R ２are each independently a hydrogen atom, a monovalent hydrocarbon group having 1 to 24 carbon atoms, a phenyl group, an amino group, or an aminoalkyl group; ３ is a divalent hydrocarbon group having 3 to 24 carbon atoms, and R ４ is a monovalent hydrocarbon group having 1 to 24 carbon atoms, N is a nitrogen atom, Si is a silicon atom, and O is an oxygen atom.

[0135] (Appendix 6) A method for producing a copper-clad laminate, comprising: an adhesive layer forming step of forming an adhesive layer containing at least one of a silane coupling agent represented by the following formula (1) and a bismaleimide resin on at least one surface of a dielectric film having a dielectric constant of 3.5 or less and a dielectric dissipation factor of 0.0030 or less at 23±5°C, 50±5% RH, and a frequency of 10 GHz; a copper foil arranging step of arranging a copper foil having a matte surface with a ten-point average roughness (Rzjis) of 1.5 μm or less as measured in accordance with JIS standard B0601 2001 (ISO 4287 1997) on the adhesive layer so that the matte surface contacts a surface of the adhesive layer; and a heating and pressing step of heating the obtained laminate composed of the dielectric film, the adhesive layer, and the copper foil at a temperature of 40°C or more and 110°C or less, applying a pressure of 0.01 MPa or more and 5.0 MPa or less, and applying heating and pressing for a time of 0.01 seconds or more and 2 minutes or less. In formula (1), R １ , R ２ are each independently a hydrogen atom, a monovalent hydrocarbon group having 1 to 24 carbon atoms, a phenyl group, an amino group, or an aminoalkyl group; ３ is a divalent hydrocarbon group having 3 to 24 carbon atoms, and R ４ is a monovalent hydrocarbon group having 1 to 24 carbon atoms, N is a nitrogen atom, Si is a silicon atom, and O is an oxygen atom.

[0136] 10 copper clad laminate, 11 dielectric film, 13 adhesive layer, 15 copper layer.

Claims

1. A copper-clad laminate comprising: a dielectric film having a dielectric constant of 3.5 or less and a dielectric dissipation factor of 0.0030 or less at 23±5°C, 50±5% RH, and a frequency of 10 GHz; an adhesive layer formed on at least one surface of the dielectric film, the adhesive layer containing at least one of a silane coupling agent represented by the following formula (1) and a bismaleimide resin; and a copper layer composed of copper foil having a matte surface with a ten-point average roughness (Rzjis) of 1.5 μm or less as measured in accordance with JIS standard B0601 2001 (ISO 4287 1997), the copper layer being arranged on the surface of the adhesive layer opposite to the surface on which the dielectric film is arranged so that the matte surface is in contact with the surface. In formula (1), R １ , R ２ are each independently a hydrogen atom, a monovalent hydrocarbon group having 1 to 24 carbon atoms, a phenyl group, an amino group, or an aminoalkyl group; ３ is a divalent hydrocarbon group having 3 to 24 carbon atoms, and R ４ is a monovalent hydrocarbon group having 1 to 24 carbon atoms, N is a nitrogen atom, Si is a silicon atom, and O is an oxygen atom.

2. The copper-clad laminate according to claim 1, wherein the adhesive layer contains the silane coupling agent and the bismaleimide resin, and the weight ratio (wt%) of the silane coupling agent to the bismaleimide resin is 5:95 to 95:

5.

3. The copper clad laminate according to claim 1 or 2, wherein the thickness of the adhesive layer is 0.01 μm or more and 7 μm or less.

4. A copper-clad laminate according to any one of claims 1 to 3, which has a warpage of 10 mm or less after being left in an atmosphere of 20±5°C and 65±20% RH for 24 hours.

5. A method for manufacturing a copper clad laminate, comprising: an adhesive layer forming step of forming an adhesive layer containing at least one of a silane coupling agent represented by the following formula (1) and a bismaleimide resin on a matte surface of copper foil having a ten-point average roughness (Rzjis) of 1.5 μm or less as measured in accordance with JIS standard B0601 2001 (ISO 4287 1997); a dielectric film placing step of placing a dielectric film on the adhesive layer, the dielectric film having a dielectric constant of 3.5 or less and a dielectric dissipation factor of 0.0030 or less at 23±5°C, 50±5% RH, and a frequency of 10 GHz; and a heating and pressing step of heating the obtained laminate composed of the copper foil, the adhesive layer, and the dielectric film at a temperature of 40°C to 110°C, a pressure of 0.01 MPa to 5.0 MPa, and a heating and pressing time of 0.01 seconds to 2 minutes. In formula (1), R １ , R ２ are each independently a hydrogen atom, a monovalent hydrocarbon group having 1 to 24 carbon atoms, a phenyl group, an amino group, or an aminoalkyl group; ３ is a divalent hydrocarbon group having 3 to 24 carbon atoms, and R ４ is a monovalent hydrocarbon group having 1 to 24 carbon atoms, N is a nitrogen atom, Si is a silicon atom, and O is an oxygen atom.

6. A method for manufacturing a copper-clad laminate, comprising: an adhesive layer forming step of forming an adhesive layer containing at least one of a silane coupling agent represented by the following formula (1) and a bismaleimide resin on at least one surface of a dielectric film having a dielectric constant of 3.5 or less and a dielectric dissipation factor of 0.0030 or less at 23±5°C, 50±5% RH, and a frequency of 10 GHz; a copper foil arranging step of arranging copper foil having a matte surface with a ten-point average roughness (Rzjis) of 1.5 μm or less as measured in accordance with JIS standard B0601 2001 (ISO 4287 1997) on the adhesive layer so that the matte surface contacts the surface of the adhesive layer; and a heating and pressing step of heating the obtained laminate composed of the dielectric film, the adhesive layer, and the copper foil at a temperature of 40°C or higher and 110°C or lower, applying a pressure of 0.01 MPa or higher and 5.0 MPa or lower, and applying heating and pressing for a time of 0.01 seconds or higher and 2 minutes or shorter. In formula (1), R １ , R ２ are each independently a hydrogen atom, a monovalent hydrocarbon group having 1 to 24 carbon atoms, a phenyl group, an amino group, or an aminoalkyl group; ３ is a divalent hydrocarbon group having 3 to 24 carbon atoms, and R ４ is a monovalent hydrocarbon group having 1 to 24 carbon atoms, N is a nitrogen atom, Si is a silicon atom, and O is an oxygen atom.

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