Copper-clad laminates and sputtering targets for forming copper-clad laminates

Abstract

To provide a copper-clad laminate that has a low transmission loss in a high frequency range, is particularly excellent in an adhesion property between a base material containing a fluoro-resin and a copper layer, and does not lose adhesion property significantly even when used in a high temperature and high humidity environment, and is particularly suitable for a wiring board for high frequency signal transmission.SOLUTION: There is provided a copper-clad laminate 10 in which a base material 11 containing a fluoro-resin and a metallic copper layer 12 are laminated, wherein an alloy layer 13 that has a composition containing Co in a range of 25.0 at% or more and 75.0 at% or less and that has a balance thereof with Mo and an unavoidable impurity is formed between the base material 11 and the metallic copper layer 12, and the metallic copper layer 12 has a copper plating layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a copper-clad laminate in which a copper layer is laminated on a substrate containing a fluororesin, and to a sputtering target for forming a copper-clad laminate used in producing the copper-clad laminate. [Background technology]

[0002] BACKGROUND ART Generally, copper-clad laminates, in which a copper layer is laminated as a conductive layer or a heat-transfer layer on the surface of an insulating resin layer, are used as wiring substrates for use in electronic and electric devices. Here, wiring boards for high-frequency signal transmission devices such as antennas and radars in the GHz band or above are required to have low transmission loss when used in the high-frequency range. Therefore, copper-clad laminates using fluororesin films have been provided, as shown in, for example, Patent Documents 1 and 2. Fluororesin has a low dielectric constant and low dielectric loss, and is therefore particularly suitable as a resin material for forming wiring boards for high-frequency signal transmission.

[0003] However, since the surface of a fluororesin film is chemically very stable, it tends to have low adhesive strength with other materials. Therefore, in Patent Document 1, a thin metal film (nickel film or titanium film) is formed on the surface of the fluororesin using physical vapor deposition, and then a copper film is formed by copper plating on this thin metal film, thereby improving the adhesion between the copper film and the fluororesin. In addition, in Patent Document 2, protrusions are formed on the surface of the fluororesin, the metal foil is roughened, and the conditions for pressure lamination are optimized to improve the adhesion between the copper film and the fluororesin through the anchor effect. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2018 / 179904 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-006668 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in Patent Document 1, the bonding interface becomes smooth, so there is no anchor effect to improve adhesion, making it difficult to obtain sufficient adhesive strength. In addition, there is a risk of oxidation of the metal film in contact with the fluororesin, which reduces durability, particularly in high-temperature and high-humidity environments. Furthermore, in Patent Document 2, the interface between the fluororesin and the metal foil becomes rough, which causes a problem of increased transmission loss.

[0006] The present invention has been made in view of the above-mentioned circumstances, and aims to provide a copper-clad laminate that has low transmission loss in the high frequency range, is particularly excellent in adhesion between a substrate containing a fluororesin and a copper layer, and does not significantly decrease in adhesion even when used in a high-temperature environment or a high-humidity environment, and is particularly suitable for wiring boards for high-frequency signal transmission, and a sputtering target for forming the copper-clad laminate that is used in producing the copper-clad laminate. [Means for solving the problem]

[0007] In order to solve the above problems, the copper-clad laminate of aspect 1 of the present invention is a copper-clad laminate in which a substrate containing a fluororesin and a metallic copper layer are laminated together, and an alloy layer having a composition containing Co in the range of 25.0 at% to 75.0 at% and the balance being Mo and unavoidable impurities is formed between the substrate and the metallic copper layer, and the metallic copper layer has a copper plating layer.

[0008] According to the copper-clad laminate of the first aspect of the present invention, an alloy layer is formed between the substrate containing a fluororesin and the metallic copper layer. The alloy layer contains Co in a range of 25.0 at% to 75.0 at% and the remainder is Mo and unavoidable impurities. This allows the Mo in the alloy layer to form a strong bond with the C in the main chain of the fluororesin contained in the substrate, improving adhesion strength. Furthermore, since the alloy layer contains Mo and Co in the above-mentioned range, it has a dense nanocrystalline structure, which is highly resistant to oxidation caused by heat and moisture. This prevents a decrease in adhesion strength even when used in high-temperature and high-humidity environments. Furthermore, the alloy layer has high barrier properties, which prevents reaction between the metallic copper layer (copper plating layer) and the fluororesin of the substrate. Furthermore, since a metallic copper layer (copper plating layer) is formed on this alloy layer, the roughness of the interface is reduced, and transmission loss can be reduced.

[0009] A copper clad laminate according to a second aspect of the present invention is the copper clad laminate according to the first aspect, characterized in that the thickness of the alloy layer is within the range of 5 nm to 50 nm. In the copper-clad laminate of the second aspect of the present invention, the thickness of the alloy layer is 5 nm or more, so that the oxidation resistance (resistance to oxidation due to heat and moisture) and barrier properties of the alloy layer are sufficiently ensured, and even when used in high-temperature and high-humidity environments, a decrease in adhesion strength can be reliably suppressed. Meanwhile, the thickness of the alloy layer is 50 nm or less, so that warping of the substrate due to membrane stress can be suppressed.

[0010] A copper clad laminate according to a third aspect of the present invention is the copper clad laminate according to the first or second aspect, characterized in that the thickness of the metallic copper layer is in the range of 1 μm to 20 μm. According to the copper-clad laminate of the third aspect of the present invention, the thickness of the metallic copper layer is 1 μm or more, which can suppress the influence of radiation loss and reliably keep transmission loss low. On the other hand, the thickness of the metallic copper layer is 20 μm or less, which can efficiently and accurately form a pattern by etching.

[0011] A copper clad laminate according to a fourth aspect of the present invention is the copper clad laminate according to any one of the first to third aspects, characterized in that the electrical conductivity of the metallic copper layer is 80% IACS or more. According to the copper clad laminate of the fourth aspect of the present invention, the electrical conductivity of the metallic copper layer is set to 80% IACS or more, and therefore the transmission characteristics are particularly excellent.

[0012] The sputtering target for forming a copper-clad laminate of aspect 5 of the present invention is a sputtering target for forming a copper-clad laminate used in forming the alloy layer of the copper-clad laminate of any one of aspects 1 to 4 of the present invention, and is characterized in that it consists of an alloy having a composition containing Co in a range of 25.0 at% or more and 75.0 at% or less, with the remainder being Mo and unavoidable impurities.

[0013] According to the sputtering target for forming a copper-clad laminate of aspect 5 of the present invention, the target is composed of an alloy containing Co in a range of 25.0 at% or more and 75.0 at% or less, with the remainder being Mo and unavoidable impurities.Therefore, an alloy layer with a dense nanocrystalline structure can be formed by sputtering on a substrate containing a fluororesin, and the oxidation resistance and barrier properties of the alloy layer can be sufficiently ensured.A copper-clad laminate can be produced that has particularly excellent adhesion between the substrate and the copper plating layer and that does not significantly decrease in adhesion even when used in high-temperature and high-humidity environments. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a copper-clad laminate that has low transmission loss in the high frequency range, is particularly excellent in adhesion between a substrate containing a fluororesin and a copper layer, and does not significantly decrease in adhesion even when used in a high-temperature environment or a high-humidity environment, and is particularly suitable for wiring boards for high-frequency signal transmission, as well as a sputtering target for forming the copper-clad laminate that is used in producing the copper-clad laminate. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic explanatory diagram of a copper-clad laminate according to an embodiment of the present invention; [Figure 2] 1 is a flow diagram showing an example of a method for manufacturing a copper-clad laminate according to an embodiment of the present invention. [Figure 3] Schematic diagram of the peel test in the examples. The upward arrow indicates the peel direction (measurement of the load applied during peeling). The peel angle is 90°, and the peel speed in the direction indicated by the arrow extending downward to the left is 50 mm / min. [Figure 4A] 1 is a SEM photograph of a cross section of an interface of a copper-clad laminate of Example 1 of the present invention in the Examples. [Figure 4B] 1 is a SEM photograph of a cross section of an interface of a copper-clad laminate of Comparative Example 3 in the Examples. DETAILED DESCRIPTION OF THE INVENTION

[0016] A copper clad laminate according to one embodiment of the present invention will be described below. A copper clad laminate according to one embodiment of the present invention is used as a wiring board for transmitting high frequency signals.

[0017] As shown in FIG. 1, the copper-clad laminate 10 of this embodiment comprises a substrate 11 containing a fluororesin and a copper plating layer 12 laminated on the substrate 11, with an alloy layer 13 formed between the substrate 11 and the metallic copper layer 12.

[0018] The substrate 11 contains, as a fluororesin, for example, PFA (perfluoroalkoxyalkane), PTFE (polytetrafluoroethylene), ETFE (ethylene-tetrafluoroethylene copolymer), FEP (tetrafluoroethylene-hexafluoropropylene copolymer), PCTFE (polychlorotrifluoroethylene), etc. Fluororesins have a low dielectric constant and low dielectric loss, making them particularly suitable as a substrate for forming a wiring board for high-frequency signal transmission. Here, the thickness t1 of the substrate 11 is not particularly limited, but is preferably within the range of 5 μm to 200 μm.

[0019] The metallic copper layer 12 is made of copper or a copper alloy that has excellent electrical and thermal conductivity, and functions as an electrically conductive layer or a heat transfer layer. Here, the electrical conductivity of the metallic copper layer 12 is preferably 80% IACS or more, and more preferably 85% IACS or more. In this embodiment, as will be described later, the metallic copper layer 12 is formed by a seed layer formed on the alloy layer 13 and a copper plating layer formed on this seed layer. This reduces the roughness of the interface between the substrate 11 and the metal layer (alloy layer 13+metallic copper layer 12), and specifically, the maximum interface height is 0.2 μm or less.

[0020] The thickness t2 of the metallic copper layer 12 is preferably within the range of 1 μm to 20 μm. If the thickness t2 of the metal copper layer 12 is 1 μm or more, the effect of radiation loss can be ignored without being equivalent to the skin effect. On the other hand, if the thickness t2 of the metal copper layer 12 is 20 μm or less, etching can be performed efficiently and accurately when forming a circuit pattern on the metal copper layer 12 by etching. The lower limit of the thickness t2 of the metal copper layer 12 is more preferably 3 μm or more, and even more preferably 5 μm or more. The upper limit of the thickness t2 of the metal copper layer 12 is more preferably 18 μm or less, and even more preferably 15 μm or less.

[0021] Between the substrate 11 and the metallic copper layer 12, an alloy layer 13 is formed, which contains Co in a range of 25.0 at % to 75.0 at % and the remainder being Mo and unavoidable impurities. Mo contained in this alloy layer 13 has a high bond energy with C. Therefore, C in the main chain of the fluororesin and Mo in the alloy layer form a strong bond, increasing the adhesive strength between substrate 11 and alloy layer 13. Furthermore, because the Co and Mo are in the above-mentioned composition, when the alloy layer 13 is formed by sputtering, the alloy layer 13 has an amorphous-like dense nanocrystalline structure, which provides particularly excellent oxidation resistance and barrier properties. Therefore, even when used in high-temperature and high-humidity environments, deterioration of adhesion can be suppressed. Here, the lower limit of the Co content in the alloy layer 13 is preferably 50 at% or more, and more preferably 60 at% or more, while the upper limit of the Co content in the alloy layer 13 is preferably 73 at% or less, and more preferably 70 at% or less.

[0022] Furthermore, the thickness t3 of the alloy layer 13 is preferably within the range of 5 nm to 50 nm. If the thickness t3 of the alloy layer 13 is 5 nm or more, sufficient oxidation resistance and barrier properties can be ensured, and even when used in high-temperature and high-humidity environments, a decrease in adhesion can be reliably prevented. On the other hand, if the thickness t3 of the alloy layer 13 is 50 nm or less, the occurrence of warping of the substrate 11 due to film stress can be suppressed. The lower limit of the thickness t3 of the alloy layer 13 is more preferably 8 nm or more, and even more preferably 10 nm or more. The upper limit of the thickness t3 of the alloy layer 13 is more preferably 30 nm or less, and even more preferably 20 nm or less.

[0023] Next, a method for manufacturing the copper clad laminate 10 according to this embodiment will be described with reference to the flow diagram of FIG.

[0024] (Substrate preparation process S01) First, a substrate 11 containing a fluororesin is prepared. Note that, for the purpose of introducing functional groups into the surface of the substrate 11, surface treatment such as plasma treatment may be performed.

[0025] (Alloy layer formation step S02) Next, an alloy layer 13 is formed on the surface of the substrate 11 to a predetermined thickness by sputtering using the sputtering target for forming a copper-clad laminate according to this embodiment. Here, the sputtering target of this embodiment is configured from an alloy having a composition containing Co in the range of 25 at % to 75.0 at %, with the balance being Mo and unavoidable impurities. The alloy layer 13 formed in this alloy layer forming step S02 has an amorphous-like dense nanocrystalline structure.

[0026] (Seed layer formation step S03) Next, a copper layer is formed by sputtering as a seed layer for plating on the alloy layer 13. The thickness of the seed layer (sputtered copper layer) is preferably in the range of 10 nm to 1000 nm. The seed layer is preferably formed continuously after the alloy layer 13 is formed without exposure to the atmosphere.

[0027] (Copper plating layer formation process S04) Next, a seed layer is formed, and then a copper plating layer of a predetermined thickness is formed by electrolytic plating. The seed layer formed on the alloy layer 13 and the copper plating layer formed on this seed layer form a metallic copper layer 12.

[0028] The copper-clad laminate 10 of this embodiment is manufactured through the above-mentioned steps. When forming copper plating layers 12 on both sides of the substrate 11, the alloy layer forming step S02 and the seed layer forming step S03 may be performed on one side of the substrate 11, and then the alloy layer forming step S02 and the seed layer forming step S03 may be performed on the opposite side, followed by the copper plating layer forming step S04.

[0029] In the copper-clad laminate 10 of this embodiment configured as described above, an alloy layer 13 having a composition containing 25.0 at% to 75.0 at% Co, with the remainder being Mo and unavoidable impurities, is formed on a substrate 11 containing fluororesin. This allows Mo in the alloy layer 13 to form a strong bond with the C in the main chain of the fluororesin contained in the substrate 11, improving the adhesion strength between the alloy layer 13 and the substrate 11. Furthermore, since the alloy layer 13 contains Mo and Co in the above-mentioned range, the alloy layer 13 forms a dense nanocrystalline structure when formed by sputtering, providing high resistance to oxidation due to heat and moisture. This prevents a decrease in adhesion strength even when used in high-temperature and high-humidity environments. Furthermore, the alloy layer 13 has high barrier properties, preventing reaction between the metallic copper layer 12 and the fluororesin of the substrate 11. Furthermore, by forming the metallic copper layer 12 on the alloy layer 13 by plating, the interface roughness of the metallic copper layer 12 is reduced, and the transmission loss can be reduced.

[0030] In the copper-clad laminate 10 of this embodiment, when the thickness t3 of the alloy layer 13 is within the range of 5 nm or more and 50 nm or less, the oxidation resistance and barrier properties of the alloy layer 13 can be sufficiently ensured, and even when used in a high-temperature environment and a high-humidity environment, a decrease in adhesion strength can be reliably suppressed, and warping of the substrate 11 due to film stress can be suppressed.

[0031] In the copper-clad laminate 10 of this embodiment, when the thickness t2 of the metal copper layer 12 is within the range of 1 μm or more and 20 μm or less, the effect of radiation loss can be suppressed, transmission loss can be reliably kept low, and pattern formation by etching can be performed efficiently and accurately. Furthermore, in the copper-clad laminate 10 of this embodiment, when the electrical conductivity of the metal copper layer 12 is 80% IACS or more, the transmission characteristics are particularly excellent.

[0032] According to the sputtering target for forming a copper-clad laminate of this embodiment, the target is composed of an alloy containing Co in a range of 25.0 at% or more and 75.0 at% or less, with the remainder being Mo and unavoidable impurities.Therefore, an alloy layer 13 with a dense nanocrystalline structure can be formed by sputtering on a substrate 11 containing a fluororesin, and the oxidation resistance and barrier properties of the alloy layer 13 can be sufficiently ensured.A copper-clad laminate 10 can be produced which has particularly excellent adhesion between the substrate 11 and the copper plating layer 12 and which does not lose adhesion significantly even when used in high-temperature and high-humidity environments.

[0033] Although the embodiment of the present invention has been described above, the present invention is not limited to this and can be modified as appropriate within the scope of the technical idea of ​​the invention. [Example]

[0034] The results of confirmation experiments conducted to confirm the effectiveness of the present invention will be described below.

[0035] A PFA film (50 μm thick) manufactured by AGC was prepared as a substrate containing a fluororesin. An alloy layer having the composition shown in Table 1 was formed on the surface of this substrate by sputtering. The film formation conditions are shown below. The at% of Mo / Co (Mo / Al in the case of Comparative Example 4) in the sputtering target for forming a copper-clad laminate was the same as the composition ratio in the formed alloy layer. The sputtering target for forming a copper-clad laminate was manufactured as follows: raw material powders containing the constituent elements were prepared, weighed and mixed to obtain a predetermined composition, and the resulting mixed raw material powder was hot-pressed to obtain a sintered body. This sintered body was then cut and machined to obtain a disk target of a predetermined size.

[0036] Target material: Mo—Co alloy (Mo—Al alloy in the case of Comparative Example 4) Deposition start vacuum degree: 1.0×10 -4 Pa or less Sputtering gas: High-purity argon Sputtering gas pressure in the chamber: 0.2 Pa DC power density: 7.5W / cm 2

[0037] Next, a 100 nm copper layer was formed as a plating seed layer by sputtering under the following sputtering conditions: The seed layer was formed immediately after the alloy layer was formed without exposure to the atmosphere. (Seed layer deposition conditions) Target material: Cu (purity 99.99 mass% or more) Deposition start vacuum degree: 1.0×10 -4 Pa or less Sputtering gas: High-purity argon Sputtering gas pressure in the chamber: 0.2 Pa DC power density: 7.5W / cm 2

[0038] <Invention Examples 1 to 7, Comparative Examples 1, 2, and 4> Next, electrolytic plating was carried out on the seed layer under the following conditions to form a copper plating layer with the thickness shown in Table 1. In this way, copper-clad laminates of Invention Examples 1 to 7 and Comparative Examples 1, 2, and 4 were formed. (Electrolytic plating conditions) Pretreatment: Sulfuric acid washing Liquid temperature: 25℃ Anode: Phosphorus-containing copper Stirring conditions: Air 12.5L / min Plating conditions: 4A, 45min Plating solution: CuSO4·5H2O 200g / L H2SO4 54g / L 1 mol HCl 1.37 mL / L Top Lucina α-M 4.5mL / L Top Lucina α-2 1.0mL / L Top Lucina α-3 3.0mL / L

[0039] <Comparative Example 3> After forming the alloy layer as described above, an 18 μm thick electrolytic copper foil (V9 series manufactured by Fukuda Metal Foil & Powder Co., Ltd.) was laminated on the alloy layer and thermocompression bonded to form a copper-clad laminate of Comparative Example 3. The electrolytic copper foil was roughened, and the roughened surface was placed facing the alloy layer before thermocompression bonding under a nitrogen atmosphere at a pressure of 0.1 MPa, a temperature of 350°C, and a holding time of 20 minutes.

[0040] The copper-clad laminates manufactured as described above were evaluated for the thickness of the alloy layer, the thickness of the metallic copper layer, the conductivity of the metallic copper layer, adhesion strength, heat resistance test, constant temperature and humidity test, transmission loss, and maximum interfacial height of the metallic copper layer as follows. The evaluation results are shown in Table 2.

[0041] (Thickness of alloy layer) The thickness of the alloy layer is a target value determined from the deposition rate. The deposition rate was calculated by measuring the film thickness after deposition on a dummy substrate for a certain period of time using a step measurement meter (Dektak-XT by Bruker) and dividing the film thickness by the deposition time. Furthermore, the thickness of the alloy layer was confirmed by observing the cross section of the copper-clad laminate using a TEM (transmission electron microscope), and was found to be equivalent to the target value based on the film formation rate.

[0042] (Thickness of the metal copper layer) The thickness of the metallic copper layer was confirmed by an eddy current method.

[0043] (Conductivity of the metallic copper layer) Conductivity of the metallic copper layer σ A The resistivity (S / m) was measured by the four-probe method using a low resistivity meter (Loresta GP manufactured by Mitsubishi Chemical Corporation), and was converted to %IACS using the following formula: σ(%IACS)=σ A / (5.8×10 7 )

[0044] (adhesion strength) As shown in Figure 3, the alloy layer and metallic copper layer formed on the substrate were cut into 5 mm widths and evaluated using an A&D Tensilon universal testing machine (RTF-1310) at a peel angle of 90 degrees and a peel speed of 50 mm / min.

[0045] (heat resistance test) As a heat resistance test, the copper-clad laminate was stored in a clean oven under the conditions of 150°C x 240 hours. After storage, the adhesion strength of the copper-clad laminate was measured as described above. The rate of change in adhesion strength before and after the heat resistance test was calculated. Note that the rate of change in adhesion strength before and after the heat resistance test is preferably -30% or more and less than 0%. (Change rate) = (Adhesion strength after test - Adhesion strength before test) / Adhesion strength before test × 100 (%)

[0046] (Constant temperature and humidity test) For the humidity resistance test, the sample pieces were stored in a constant temperature and humidity chamber at a temperature of 85°C and a relative humidity of 85% for 240 hours. After storage, the adhesion strength was measured in the same manner as above, and the rate of change before and after the test was calculated. Note that the rate of change in adhesion strength before and after the constant temperature and humidity test is preferably -50% or more and less than 0%.

[0047] (Transmission loss) Using the prepared copper-clad laminate, a microstrip line was fabricated by a wet etching process (the circuit width was adjusted so that the characteristic impedance was 50 Ω), and the S(S21) parameters of the fabricated circuit board at a frequency of 50 GHz were measured using a network analyzer.

[0048] (Maximum interface height) The cross section of the prepared copper-clad laminate was observed using a scanning electron microscope (JEOL JSM-7001FA) at a magnification of 1000. An example of the observation results is shown in Figure 4. The maximum height (the difference in height between the highest and lowest points on the outline of the interface) was calculated for the interface between the substrate and the copper plating layer (note that the lower limit is about 0.2 μm due to magnification).

[0049] [Table 1]

[0050] [Table 2]

[0051] In Comparative Examples 1 and 2, the Co content in the alloy layer formed between the substrate and the metallic copper layer was outside the range of the present invention, and the adhesion significantly decreased after the heat resistance test and the constant temperature and humidity test. This is presumably because the alloy layer did not have a dense nanocrystalline structure. In Comparative Example 3, electrolytic copper foil was thermocompression bonded, but the maximum interface height between the substrate and the metallic copper layer was 4.2 μm, resulting in increased transmission loss. In Comparative Example 4, the alloy layer formed between the substrate and the metallic copper layer contained Al (50.0 at%) instead of Co, and the adhesion significantly decreased after the heat resistance test and the constant temperature and humidity test. This is presumably because the alloy layer did not have a dense nanocrystalline structure.

[0052] In contrast, in Examples 1 to 7 of the present invention, an alloy layer containing 25 at% to 75.0 at% Co and the remainder being Mo and unavoidable impurities was formed between the substrate and the metallic copper layer, and the initial adhesion was excellent, and the adhesion strength did not decrease significantly even after heat resistance tests and constant temperature and humidity tests, demonstrating excellent heat resistance and stable use even in high temperature and high humidity environments.In addition, the maximum interface height between the substrate and the metallic copper layer was 0.2 μm or less, and transmission loss was reduced.

[0053] From the above, it was confirmed that the present invention can provide a copper-clad laminate that has low transmission loss in the high frequency range, is particularly excellent in adhesion between the substrate containing a fluororesin and the copper layer, and does not significantly reduce adhesion even when used in high-temperature and high-humidity environments, and is particularly suitable for wiring boards for high-frequency signal transmission, as well as a sputtering target for forming the copper-clad laminate that is used in producing the copper-clad laminate. [Industrial Applicability]

[0054] The present invention provides a copper-clad laminate that has low transmission loss in the high frequency range, is particularly excellent in adhesion between a substrate containing a fluororesin and a copper layer, and does not significantly reduce adhesion even when used in high-temperature and high-humidity environments, making it particularly suitable for wiring boards for high-frequency signal transmission. It also provides a sputtering target for forming the copper-clad laminate that is used in producing the copper-clad laminate. [Explanation of symbols]

[0055] 10 Copper-clad laminate 11 Base material 12 metal copper layer 13 Alloy layer t1 Thickness of the substrate 11 t2 Thickness of the metal copper layer 12 t3 Thickness of alloy layer 13

Claims

1. A copper clad laminate in which a substrate containing a fluororesin and a metallic copper layer are laminated, an alloy layer having a composition containing Co in a range of 25.0 at% or more and 75.0 at% or less, with the balance being Mo and unavoidable impurities, is formed between the substrate and the metallic copper layer; A copper clad laminate, wherein the metallic copper layer has a copper plating layer.

2. 2. The copper clad laminate according to claim 1, wherein the thickness of the alloy layer is in the range of 5 nm to 50 nm.

3. 2. The copper clad laminate according to claim 1, wherein the thickness of the metallic copper layer is in the range of 1 μm to 20 μm.

4. 2. The copper clad laminate according to claim 1, wherein the electrical conductivity of the metallic copper layer is 80% IACS or more.

5. A sputtering target for forming a copper-clad laminate used in forming the alloy layer of the copper-clad laminate according to any one of claims 1 to 4, A sputtering target for forming a copper-clad laminate, comprising an alloy containing Co in a range of 25.0 at % to 75.0 at %, with the balance being Mo and unavoidable impurities.

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