Copper-clad laminate, and sputtering target for forming copper-clad laminate

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 base material containing a fluororesin, and a sputtering target for forming a copper-clad laminate used when manufacturing the copper-clad laminate.

Background Art

[0002] Generally, as a wiring substrate used in electronic and electrical devices, a copper-clad laminate in which a copper layer is laminated as a conductive layer or a heat transfer layer on the surface of an insulating resin layer is used. Here, in a wiring substrate for high-frequency signal transmission devices such as antennas and radars in the GHz band and above, it is required that the transmission loss is low when used in the high-frequency region. Therefore, for example, as shown in Patent Documents 1 and 2, a copper-clad laminate using a fluororesin film is provided. Since the fluororesin has a low dielectric constant and a low dielectric loss, it is particularly suitable as a resin material constituting a wiring substrate for high-frequency signal transmission.

[0003] By the way, in the fluororesin film, since its surface is chemically very stable, the adhesive force with other materials tends to be low. Therefore, in Patent Document 1, a metal thin film (nickel film or titanium film) is formed on the surface of the fluororesin by physical vapor deposition, and a copper film is formed by performing copper plating on this metal thin film, thereby improving the adhesion between the copper film and the fluororesin. Further, in Patent Document 2, protrusions are formed on the surface of the fluororesin, the metal foil is roughened, and the conditions for pressure bonding and lamination are optimized, thereby improving the adhesion between the copper film and the fluororesin due to the anchor effect.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

[0005] By the way, in Patent Document 1, there is a problem that since the bonding interface becomes smooth, there is no effect of improving the adhesion due to the anchor effect, and it is difficult to obtain sufficient adhesion strength. In addition, there is a risk that oxidation of the metal film in contact with the fluororesin progresses, and there is a problem that the durability particularly decreases in a high-temperature environment and a high-humidity environment. Further, in Patent Document 2, there is a problem that the interface between the fluororesin and the metal foil becomes roughened, and the transmission loss deteriorates.

[0006] This invention has been made in view of the above circumstances, and has low transmission loss in the high-frequency region, is particularly excellent in the adhesion between a base material containing a fluororesin and a copper layer, and even when used in a high-temperature environment and a high-humidity environment, the adhesion does not significantly decrease, and an object thereof is to provide a copper-clad laminate particularly suitable for a wiring board for high-frequency signal transmission, and a sputtering target for forming a copper-clad laminate used when manufacturing this copper-clad laminate. MEANS FOR SOLVING THE PROBLEMS

[0007] In order to solve the above problems, the copper-clad laminate according to Embodiment 1 of the present invention is a copper-clad laminate in which a base material containing a fluororesin and a metal copper layer are laminated, and between the base material and the metal copper layer, an alloy layer having a composition containing Co in the range of 25.0 at% or more and 75.0 at% or less, and the balance being Mo and unavoidable impurities is formed, and the metal copper layer is characterized by having a copper plating layer.

[0008] According to the copper-clad laminate of Aspect 1 of the present invention, an alloy layer having a composition containing Co in the 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 base material containing a fluororesin and the metal copper layer. Therefore, a strong bond is formed between Mo in the alloy layer and C, which is the main chain of the fluororesin contained in the base material, and the adhesion strength is improved. Further, since the alloy layer contains Co in the above range in Mo, it has a dense nanocrystalline structure and has high resistance to oxidation by heat and moisture. Even when used in a high-temperature environment and a high-humidity environment, a decrease in adhesion strength can be suppressed. Further, since the alloy layer has high barrier properties, the reaction between the metal copper layer (copper plating layer) and the fluororesin of the base material can be suppressed. In addition, since a metal copper layer (copper plating layer) is formed on this alloy layer, the roughness of the interface is reduced, and transmission loss can be lowered.

[0009] The copper-clad laminate of Aspect 2 of the present invention is characterized in that, in the copper-clad laminate of Aspect 1, the thickness of the alloy layer is in the range of 5 nm or more and 50 nm or less. According to the copper-clad laminate of Aspect 2 of the present invention, since the thickness of the alloy layer is 5 nm or more, sufficient oxidation resistance (resistance to oxidation by heat and moisture) and barrier properties of the alloy layer can be ensured, and even when used in a high-temperature environment and a high-humidity environment, a decrease in adhesion strength can be reliably suppressed. On the other hand, since the thickness of the alloy layer is 50 nm or less, warping of the base material due to film stress can be suppressed.

[0010] The copper-clad laminate of Aspect 3 of the present invention is characterized in that, in the copper-clad laminate of Aspect 1 or Aspect 2, the thickness of the metal copper layer is in the range of 1 μm or more and 20 μm or less. According to the copper-clad laminate of Aspect 3 of the present invention, since the thickness of the metal copper layer is 1 μm or more, the influence of radiation loss can be suppressed, and transmission loss can be reliably kept low. On the other hand, since the thickness of the metal copper layer is 20 μm or less, pattern formation by etching can be performed efficiently and with high accuracy.

[0011] The copper-clad laminate of Aspect 4 of the present invention is characterized in that, in any one of the copper-clad laminates of Aspect 1 to Aspect 3, the conductivity of the metallic copper layer is 80% IACS or more. According to the copper-clad laminate of Aspect 4 of the present invention, since the conductivity of the metallic copper layer is set to 80% IACS or more, the transmission characteristics are particularly excellent.

[0012] The sputtering target for forming a copper-clad laminate according to Aspect 5 of the present invention is a sputtering target for forming the alloy layer of any one of the copper-clad laminates of Aspect 1 to Aspect 4 of the present invention, and contains Co in the range of 25.0 at% or more and 75.0 at% or less, and the balance is composed of an alloy having a composition of Mo and unavoidable impurities.

[0013] According to the sputtering target for forming a copper-clad laminate of Aspect 5 of the present invention, since it is composed of an alloy containing Co in the range of 25.0 at% or more and 75.0 at% or less and having the balance of Mo and unavoidable impurities, a dense nano-crystalline structure alloy layer 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. It is possible to manufacture a copper-clad laminate that is particularly excellent in adhesion between the substrate and the copper plating layer and whose adhesion does not significantly decrease even when used in a high-temperature environment and a high-humidity environment.

Advantages 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 region, is particularly excellent in adhesion between a substrate containing a fluororesin and a copper layer, and whose adhesion does not significantly decrease even when used in a high-temperature environment and a high-humidity environment, and is particularly suitable for a wiring board for high-frequency signal transmission, and a sputtering target for forming a copper-clad laminate used in manufacturing this copper-clad laminate.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4A

Figure 4B

Mode for Carrying Out the Invention

[0016] Hereinafter, a copper-clad laminate according to an embodiment of the present invention will be described. The copper-clad laminate according to an embodiment of the present invention is used as a wiring board for high-frequency signal transmission.

[0017] As shown in FIG. 1, the copper-clad laminate 10 according to this embodiment includes a base material 11 containing a fluororesin and a copper plating layer 12 laminated on the base material 11, and an alloy layer 13 is formed between the base material 11 and the metal copper layer 12.

[0018] The base material 11 contains, for example, PFA (perfluoroalkoxyalkane), PTFE (polytetrafluoroethylene), ETFE (ethylene-tetrafluoroethylene copolymer), FEP (tetrafluoroethylene-hexafluoropropylene copolymer), PCTFE (polychlorotrifluoroethylene), etc. as the fluororesin. Since the fluororesin has a low dielectric constant and a low dielectric loss, it is particularly suitable as a base material for forming a wiring board for high-frequency signal transmission. Here, the thickness t1 of the base material 11 is not particularly limited, but it is preferably in the range of 5 μm or more and 200 μm or less.

[0019] The metal copper layer 12 is composed of copper or a copper alloy with excellent electrical and thermal conductivity, and acts as a conductive layer or a heat transfer layer. Here, in the metal copper layer 12, the conductivity is preferably 80% IACS or more, and more preferably 85% IACS or more. In this embodiment, as will be described later, the metal 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. Thereby, the roughness of the interface between the base material 11 and the metal layer (alloy layer 13 + metal copper layer 12) is reduced. Specifically, the maximum interface height becomes 0.2 μm or less.

[0020] Also, the thickness t2 of the metal copper layer 12 is preferably in the range of 1 μm or more and 20 μm or less. If the thickness t2 of the metal copper layer 12 is 1 μm or more, the influence of radiation loss can be ignored without being comparable to the skin effect. On the other hand, if the thickness t2 of the metal copper layer 12 is 20 μm or less, when forming a circuit pattern by etching the metal copper layer 12, etching can be performed efficiently and accurately. Note that 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. Also, 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] And an alloy layer 13 having a composition containing Co in the range of 25.0 at% or more and 75.0 at% or less and the balance being Mo and inevitable impurities is formed between the base material 11 and the metal copper layer 12. The Mo contained in this alloy layer 13 has a high binding energy with C. Therefore, C in the main chain of the fluororesin and Mo in the alloy layer form a strong bond, and the adhesion strength between the base material 11 and the alloy layer 13 is increased. In addition, since Co and Mo have the above-described compositions, when the alloy layer 13 is formed by sputtering, the alloy layer 13 has an amorphous-like dense nanocrystalline structure and is particularly excellent in oxidation resistance and barrier properties. Therefore, even when used in a high-temperature environment and a high-humidity environment, a decrease in 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. On the other hand, 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] Also, the thickness t3 of the alloy layer 13 is preferably in the range of 5 nm or more and 50 nm or less. 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 a high-temperature environment and a high-humidity environment, a decrease in adhesion can be reliably suppressed. On the other hand, if the thickness t3 of the alloy layer 13 is 50 nm or less, warping of the base material 11 due to film stress can be suppressed. Note that 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. Also, 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 the present embodiment will be described with reference to the flowchart of FIG. 2.

[0024] (Base material preparation step S01) First, a base material 11 containing a fluororesin is prepared. Note that surface treatment such as plasma treatment may be performed for the purpose of introducing a functional group on the surface of the base material 11.

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

[0026] (Seed layer forming step S03) Next, a copper layer is formed by sputtering on the alloy layer 13 as a seed layer for plating. The thickness of the seed layer (sputtered copper layer) is preferably in the range of 10 nm or more and 1000 nm or less. After forming the above-mentioned alloy layer 13, it is preferable to continuously form the seed layer without exposing it to the atmosphere.

[0027] (Copper plating layer forming step S04) Next, after forming the seed layer, an electrolytic plating is performed to form a copper plating layer with a predetermined thickness. A metal copper layer 12 is formed by the seed layer formed on the alloy layer 13 and the copper plating layer formed on this seed layer.

[0028] By the above-described respective steps, the copper-clad laminate 10 of the present embodiment is manufactured. When forming the copper plating layers 12 on both surfaces of the base material 11, the alloy layer forming step S02 and the seed layer forming step S03 are performed on one surface of the base material 11, and then, after performing the alloy layer forming step S02 and the seed layer forming step S03 on the opposite surface, the copper plating layer forming step S04 may be performed.

[0029] According to the copper-clad laminate 10 of this embodiment configured as described above, an alloy layer 13 having a composition containing Co in the range of 25.0 at% or more and 75.0 at% or less on a base material 11 containing a fluororesin, with the balance being Mo and inevitable impurities, is formed. Therefore, a strong bond is formed between Mo in the alloy layer 13 and C, which is the main chain of the fluororesin contained in the base material 11, and the adhesion strength between the alloy layer 13 and the base material 11 is improved. Further, since the alloy layer 13 contains Co in the above-mentioned range in Mo, when the film is formed by sputtering, the alloy layer 13 has a dense nanocrystalline structure, has high resistance to oxidation by heat and moisture, and even when used in a high-temperature environment and a high-humidity environment, a decrease in adhesion strength can be suppressed. Further, since the alloy layer 13 has high barrier properties, the reaction between the metal copper layer 12 and the fluororesin of the base material 11 can be suppressed. In addition, by forming the metal copper layer 12 on this alloy layer 13 by electroplating, the interface roughness of the metal copper layer 12 can be reduced and the transmission loss can be lowered.

[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 by 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 surely suppressed, and warping of the base material 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 influence of radiation loss can be suppressed, the transmission loss can be surely kept low, and pattern formation by etching can be efficiently and accurately performed. Furthermore, in the copper-clad laminate 10 of this embodiment, when the 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 the present embodiment, since it is composed of an alloy having a composition containing Co in the range of 25.0 at% or more and 75.0 at% or less, and the balance being Mo and unavoidable impurities, a dense nano-crystalline alloy layer 13 can be formed on the substrate 11 containing a fluororesin by sputtering, and the oxidation resistance and barrier properties of the alloy layer 13 can be sufficiently ensured. It is possible to manufacture a copper-clad laminate 10 that is particularly excellent in adhesion between the substrate 11 and the copper plating layer 12 and whose adhesion does not significantly decrease even when used in a high-temperature environment and a high-humidity environment.

[0033] As described above, the embodiments of the present invention have been described, but the present invention is not limited thereto, and can be appropriately modified without departing from the technical idea of the invention.

Examples

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

[0035] As a substrate containing a fluororesin, a PFA film (thickness 50 μm) manufactured by AGC Inc. was prepared. 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) of the sputtering target for forming a copper-clad laminate was equivalent to the composition ratio in the formed alloy layer. Here, 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 so as to have a predetermined composition, and a sintered body was obtained by hot-pressing the obtained mixed raw material powder. This sintered body was subjected to cutting and machining 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) Film formation start vacuum degree: 1.0×10 -4 Pa or less Sputtering gas: High-purity argon Sputtering gas pressure inside the chamber: 0.2 Pa DC power density: 7.5 W / cm 2

[0037] Next, as a seed layer for plating, a 100-nm copper layer was formed by sputtering. The sputtering conditions are as follows. Note that the seed layer was formed continuously without exposing to the atmosphere after forming the alloy layer. (Film formation conditions of the seed layer) Target material: Cu (purity 99.99 mass% or more) Vacuum degree at film formation start: 1.0×10 -4 Pa or less Sputtering gas: High-purity argon Sputtering gas pressure inside the chamber: 0.2 Pa DC power density: 7.5 W / cm 2

[0038] <Examples 1 to 7 of the present invention, Comparative Examples 1, 2, 4> Next, an electrolytic copper plating layer with the thickness shown in Table 1 was formed by performing electrolytic plating on the seed layer under the following conditions. Thereby, copper-clad laminate boards of Examples 1 to 7 of the present invention and Comparative Examples 1, 2, 4 were formed. (Electrolytic plating conditions) Pretreatment: Sulfuric acid cleaning Liquid temperature: 25°C Anode: Phosphorus-containing copper Stirring conditions: Air 12.5 L / min Plating conditions: 4 A, 45 min Plating solution: CuSO 4 ·5H 2 O 200 g / L H 2 SO 4 54 g / L 1 mol HCl 1.37 mL / L Topluthina α-M 4.5 mL / L Topluthina α-2 1.0 mL / L Topluthina α-3 3.0 mL / L

[0039] <Comparative Example 3> After forming the alloy layer as described above, an electrolytic copper foil with a thickness of 18 μm (V9 series manufactured by Fukuda Metal Foil & Powder Co., Ltd.) was laminated on this alloy layer and thermocompression bonding was performed to form the copper-clad laminate of Comparative Example 3. The electrolytic copper foil was subjected to a roughening treatment, and it was laminated and thermocompression bonded so that this roughened surface faced the alloy layer side. The thermocompression bonding conditions were a pressure of 0.1 MPa, a temperature of 350 °C, and a holding time of 20 minutes under a nitrogen atmosphere.

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

[0041] (Thickness of the alloy layer) The thickness of the alloy layer becomes the target value from the film formation rate. The film formation rate was calculated by measuring the film thickness after film formation on a dummy substrate for a certain period of time with a step profiler (Dektak-XT manufactured by Bruker) and dividing the film thickness by the film formation time. In addition, as a result of observing the cross-section of the copper-clad laminate with a TEM (transmission electron microscope) to confirm the thickness of the alloy layer, it showed a value equivalent to the target value from the film formation rate.

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

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

[0044] (Adhesion strength) As shown in Fig. 3, the alloy layer and the metallic copper layer formed on the substrate were cut out with a width of 5 mm and evaluated using a Tensilon universal testing machine (RTF-1310) manufactured by A&D Company Limited under the conditions of a peeling angle of 90 degrees and a peeling 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 × 240 h. For the copper-clad laminate after storage, the adhesion strength was measured as described above. Then, the change rate of the adhesion strength before and after the heat resistance test was calculated. Note that the change rate of the adhesion strength before and after the heat resistance test is preferably not less than -30% and less than 0%. (Change Rate) = (Adhesion Strength after Test - Adhesion Strength before Test) / Adhesion Strength before Test × 100 (%)

[0046] (Temperature and Humidity Cycling Test) As a humidity resistance test, the sample piece was stored in a temperature and humidity chamber under the conditions of a temperature of 85 °C, a relative humidity of 85%, and 240 h. After storage, the adhesion strength was measured in the same manner as above, and the change rate before and after the test was calculated. Note that the change rate of the adhesion strength before and after the temperature and humidity cycling test is preferably not less than -50% and less than 0%.

[0047] (Transmission Loss) Using the fabricated 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 fabricated circuit board was measured for the S (S21) parameter at a frequency of 50 GHz using a network analyzer.

[0048] (Maximum Interface Height) The cross-section of the fabricated copper-clad laminate was observed with a scanning electron microscope (JSM-7001FA manufactured by JEOL Ltd.). The observation magnification was 1000 times. An example of the observation result is shown in Fig. 4. For the interface between the substrate and the copper plating layer, the maximum height (the height difference between the highest and lowest points of the interface profile) was calculated (note that about 0.2 μm is the lower limit 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 base material and the metallic copper layer was outside the scope of the present invention. After the heat resistance test and after the constant temperature and humidity test, the adhesion significantly decreased. It is presumed that this is because the alloy layer did not become a dense nanocrystalline structure. In Comparative Example 3, the electrolytic copper foil was thermocompression bonded, but the maximum interface height between the base material and the metallic copper layer was 4.2 μm, resulting in a large transmission loss. In Comparative Example 4, the alloy layer formed between the base material and the metallic copper layer contained Al (50.0 at%) instead of Co. After the heat resistance test and after the constant temperature and humidity test, the adhesion significantly decreased. It is presumed that this is because the alloy layer did not become a dense nanocrystalline structure.

[0052] On the other hand, in Invention Examples 1 to 7, an alloy layer having a composition containing Co in the range of 25 at% or more and 75.0 at% or less, with the balance being Mo and unavoidable impurities, was formed between the base material and the metallic copper layer. It has excellent initial adhesion, and even after the heat resistance test and after the constant temperature and humidity test, the adhesion strength does not significantly decrease. It has excellent heat resistance and has been confirmed to be stably usable even in a high-temperature environment and a high-humidity environment. Also, the maximum interface height between the base material and the metallic copper layer was 0.2 μm or less, resulting in a small transmission loss.

[0053] From the above, according to the Invention Examples, it is possible to provide a copper-clad laminate having low transmission loss in the high-frequency region, particularly excellent adhesion between a base material containing a fluororesin and a copper layer, and whose adhesion does not significantly decrease even when used in a high-temperature environment and a high-humidity environment, and is particularly suitable for a wiring board for high-frequency signal transmission, and a sputtering target for forming a copper-clad laminate used when manufacturing this copper-clad laminate.

Industrial Applicability

[0054] It is possible to provide a copper-clad laminate that has low transmission loss in the high-frequency region, is particularly excellent in the adhesion between a base material containing a fluororesin and a copper layer, and whose adhesion does not significantly decrease even when used in a high-temperature environment and a high-humidity environment, and is particularly suitable for a wiring board for high-frequency signal transmission, and a sputtering target for forming a copper-clad laminate used when manufacturing this 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 base material 11 t2 Thickness of the metal copper layer 12 t3 Thickness of the 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, The copper clad laminate is characterized in that 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 within 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 or more and 20 μm or less.

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 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.

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