Conductive film for circuit board and film for circuit board

Abstract

To provide a conductive film for circuit boards excellent in adhesion between a substrate and a thin film copper layer, and excellent in etching property and plating liquid resistance necessary in a post process for forming a circuit board and a film for circuit boards.SOLUTION: A conductive film for circuit boards includes a substrate and a coating layer covering the substrate and including a nuclear metal layer including a nuclear metal in this order, wherein the nucleated metal layer contains silicon, and the nucleated metal is provided in a state in which it is scattered on the substrate, and the coating layer includes a thin film copper layer, and when assumed that the nuclear metal is evenly laminated on the substrate, an average thickness of the nuclear metal layer is 1.5 nm or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a conductive film for circuit boards and a film for circuit boards, more specifically, to a conductive film for circuit boards and a film for circuit boards that have excellent adhesion between a substrate and a thin copper layer, and also have excellent etching properties and plating solution resistance required in a post-process for forming a circuit board. [Background technology]

[0002] Conventionally, laminates have been developed for use in flexible circuit boards and the like (Patent Documents 1 and 2). Such laminates are required to have excellent adhesion between the substrate and the thin-film copper layer in a heat-resistant environment. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-130995 A [Patent Document 2] JP 2017-76586 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the laminates described in Patent Documents 1 and 2 are inferior in etching properties and plating solution resistance in the post-processing for forming a circuit board.

[0005] The present invention has been made in consideration of such conventional inventions, and has an object to provide a conductive film for circuit boards and a film for circuit boards that have excellent adhesion between a substrate and a thin-film copper layer, and also have excellent etching properties and plating solution resistance required in later processes for forming a circuit board. [Means for solving the problem]

[0006] As a result of intensive research, the present inventors have found that by providing a nucleated metal layer containing a nucleated metal containing silicon on a substrate so that the nucleated metal is dispersed, and by adjusting the average thickness of the nucleated metal layer, a conductive film for circuit boards can be obtained that has excellent adhesion between the substrate and the thin copper layer, as well as excellent etching properties and plating solution resistance required in the post-process for forming a circuit board, and have completed the present invention. That is, the conductive film for circuit boards and film for circuit boards of the present invention that solve the above problems mainly include the following configurations.

[0007] (1) A conductive film for circuit boards comprising, in this order, a substrate and a coating layer covering the substrate and including a seed-bearing metal layer containing seed-bearing metal, the seed-bearing metal layer containing silicon, the seed-bearing metal being provided in a scattered state on the substrate, the coating layer including a thin film copper layer, and an average thickness of the seed-bearing metal layer being 1.5 nm or less when it is assumed that the seed-bearing metal is evenly layered on the substrate.

[0008] According to this configuration, the conductive film for circuit boards has excellent adhesion between the substrate and the thin-film copper layer, as well as excellent etching properties and plating solution resistance required in later processes for forming a circuit board.

[0009] (2) The conductive film for circuit boards according to (1), wherein the coating layer further includes a nickel alloy layer on the substrate side.

[0010] According to this configuration, the conductive film for circuit boards has better adhesion between the substrate and the thin-film copper layer.

[0011] (3) The conductive film for circuit boards according to (1) or (2), wherein the core-coated metal layer is provided on the thin-film copper layer.

[0012] According to this configuration, the conductive film for circuit boards has better adhesion between the substrate and the thin-film copper layer.

[0013] (4) The conductive film for circuit boards according to (2), wherein the core-containing metal layer is provided on the nickel alloy layer.

[0014] According to this configuration, the conductive film for circuit boards has better adhesion between the substrate and the thin-film copper layer.

[0015] (5) The surface resistance of the core-coated metal layer is 1.0×10 10 The conductive film for circuit boards according to any one of (1) to (4), having a resistivity of Ω / □ or more.

[0016] According to this configuration, the core-containing metal layer of the conductive film for circuit boards is not conductive and is a discontinuous film with a sea-island structure, so that the conductive film for circuit boards has better etching properties in a post-process.

[0017] (6) The resistivity of the core-coated metal layer is 1.0×10 -3 The conductive film for circuit boards according to any one of (1) to (5), which has a resistance of Ω·m or more.

[0018] According to this configuration, the core-containing metal layer of the conductive film for circuit boards is not conductive and is a discontinuous film with a sea-island structure, so that the conductive film for circuit boards has excellent etching properties in a post-process.

[0019] (7) A film for circuit boards, comprising the conductive film for circuit boards according to any one of (1) to (6) above, and a plated copper layer provided on the thin-film copper layer.

[0020] According to this configuration, the conductive film for circuit boards is suitable for use as a circuit board. Effect of the Invention

[0021] According to the present invention, it is possible to provide a conductive film for circuit boards and a film for circuit boards that have excellent adhesion between a substrate and a thin-film copper layer, and also have excellent etching properties and plating solution resistance required in later processes for forming a circuit board. [Brief description of the drawings]

[0022] [Figure 1] FIG. 1 is a schematic cross-sectional view of a conductive film for circuit boards according to one embodiment (first embodiment) of the present invention. [Diagram 2] FIG. 2 is a graph showing the relationship between the film thickness of the core-mounted metal layer and the surface resistance value in a conductive film for circuit boards. [Diagram 3] FIG. 3 is a schematic cross-sectional view of a conductive film for circuit boards according to one embodiment of the present invention (second embodiment). [Figure 4] FIG. 4 is an SEM photograph (metal side) of the peel interface of a specific example (Example 39 described below) of a conductive film for circuit boards according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] <Conductive film for circuit boards> (First embodiment) The conductive film for circuit boards according to one embodiment of the present invention comprises, in this order, a substrate and a coating layer covering the substrate and including a seeded metal layer containing seeded metal. The seeded metal layer contains silicon. The seeded metal is provided in a scattered state on the substrate. The coating layer includes a thin-film copper layer. Assuming that the seeded metal is evenly layered on the substrate, the average thickness of the seeded metal layer is 1.5 nm or less. Each of the configurations will be described below.

[0024] Fig. 1 is a schematic cross-sectional view of a conductive film for circuit boards 1 of the present embodiment. As shown in Fig. 1, the conductive film for circuit boards 1 of the present embodiment includes, in this order, a base material 2, a seed metal layer 4 including seed metals 3, and a thin-film copper layer 5. In Fig. 1, reference numeral 7 denotes a plated copper layer provided in a film for circuit boards 9 described below. Furthermore, a coating layer 6 covers the base material 2, and includes the seed metal layer 4 and the thin-film copper layer 5. In the present embodiment, the thin-film copper layer 5 is an example of a coating layer.

[0025] ·Base material The substrate is not particularly limited. The substrate may be any substrate on which a thin copper layer or a nucleated metal layer, which will be described later, can be formed. For example, the substrate may be a fluororesin film (PTFE film, PFA film, etc.), an LCP film, a PI film, a transparent PI film, an MPI film, a COP film, a polyester film, an olefin film, etc. Among these, the substrate is preferably a PTFE film, a transparent PI film, or an LCP film, and more preferably PTFE.

[0026] The substrate may contain known additives such as antistatic agents, ultraviolet absorbers, plasticizers, lubricants, colorants, etc. The substrate may also be coated in advance on one or both sides with a resin layer such as a silane coupling agent, acrylic, polyester, or epoxy.

[0027] The substrate may be subjected to a plasma treatment as a pretreatment step. For example, the pretreatment step may be performed at a maximum power density of 0.5 to 20 (W / cm 2 The process involves a two-stage treatment using plasma of argon and oxygen generated by a high-voltage pulse, which is a plasma processing method for flexible printed circuit boards (FPCs). This results in excellent adhesion between the substrate and the thin copper layer. The obtained conductive film for circuit boards has excellent reliability during processing and after product shipment in technical fields such as flexible copper clad laminates (FCCLs) in flexible printed circuit boards (FPCs).

[0028] The thickness of the substrate is not particularly limited. For example, the thickness of the substrate is preferably 4 μm or more, more preferably 12 μm or more, and even more preferably 25 μm or more. The thickness of the substrate is preferably 300 μm or less, more preferably 250 μm or less, and even more preferably 200 μm or less. When the thickness of the substrate is within the above range, the conductive film for circuit boards has excellent handling properties and flexibility during processing. In addition, the conductive film for circuit boards is easily suitable for use in bendable circuit boards. The average thickness of the substrate can be appropriately adjusted depending on the use of the film. For example, in applications requiring a thinner film and high flexibility, the average thickness of the substrate can be selected to be close to 6 μm. In addition, the average thickness of the substrate can be selected to be close to 300 μm from the viewpoints of insulation, high reliability, and handling.

[0029] ·Metal layer with core The seeded metal layer of the present embodiment is a layer provided on the thin-film copper layer, is provided on the substrate, and contains a seeded metal containing silicon.

[0030] The nucleated metal is not particularly limited as long as it contains silicon. For example, the nucleated metal is SiCo (Si-50Co, Si:Co=50wt%:50wt%), SiC (Si-50C, Si:C=50wt%:50wt%), Si (Si=100wt%), SiCoNx (nitride of SiCo), SiCoOx (oxide of SiCo), SiCNx (nitride of SiC), SiNx (nitride of Si), etc. Among these, the nucleated metal is preferably SiCo, SiC, etc. By using these nucleated metals, the conductive film for circuit board has excellent adhesion. In the above, "Si-50Co" and "Si-50C" are both the composition ratios of the sputtering target. In this embodiment, it has been confirmed that the composition ratios in the sputtered film when the film is formed using these targets are the same as the composition ratios of the targets.

[0031] In this embodiment, the silicon content in the nucleated metal is not particularly limited. As an example, the silicon content in the nucleated metal is preferably 30 mass% or more, more preferably 40 mass% or more, and even more preferably 45 mass% or more. The silicon content in the nucleated metal may be 100 mass%. By having the silicon content within the above range, the conductive film for circuit boards has excellent adhesion between the substrate and the thin copper layer. By having the silicon content within the above range, the conductive film for circuit boards is more likely to maintain surface insulation during etching in forming a circuit.

[0032] In this embodiment, the nucleated metal is provided in a scattered state on the substrate. In this embodiment, whether the nucleated metal is in a scattered state can be understood, for example, by observing an SEM photograph of the peeling interface and confirming traces of the nucleated metal in the nucleated metal layer. In addition, whether the nucleated metal is in a scattered state can also be confirmed by confirming that a continuous film of the nucleated metal is not formed. For example, when a nucleated metal layer is formed on a substrate to a predetermined thickness and the surface resistance value is measured, the film changes from a discontinuous film to a continuous film as the film thickness increases. When the film changes to a continuous film, the surface resistance value drops significantly. As a result, the film thickness at that time is calculated, and a film thickness smaller than that film thickness is adopted, and it can be understood that the nucleated metal is in a scattered state. More specifically, in the conductive film for circuit boards of this embodiment, when the film thickness of the nucleated metal layer is 0.6 nm, the surface resistance value is about 1.0×10 14 (Ω / □), but when the thickness of the seed metal layer is 1.6 nm, the surface resistance is about 23×10 6 (Ω / □). This shows that in the conductive film for circuit boards of this embodiment, when the film thickness (average thickness) of the core-containing metal layer is 1.5 nm or less, the core-containing metal can be present in a suitably dispersed state.

[0033] In addition, in this embodiment, the nucleated metal does not substantially contain Ti, Al, and Ni. Since the nucleated metal does not substantially contain Ti, it has excellent etching characteristics in the circuit processing and forming process when creating wiring. Furthermore, since the nucleated metal does not substantially contain Al, Al does not dissolve in the electrolytic copper plating process, and as a result, the adhesion does not decrease. Furthermore, since the nucleated metal does not substantially contain Ni, the manufacturing cost can be reduced.

[0034] Returning to the explanation of the seeded metal layer, the content of the seeded metal in the seeded metal layer is not particularly limited. As an example, the content of the seeded metal is preferably 95 mass% or more, more preferably 99 mass% or more, and even more preferably 99.5 mass% or more. In this embodiment, the seeded metal layer may contain impurities that are inevitably contained in addition to the seeded metal.

[0035] In this embodiment, the surface resistance of the core-attached metal layer is 1.0×10 10 It is preferable that the resistance is Ω / □ or more, and 1.0×10 11 More preferably, it is 1.0×10 12 It is more preferable that the surface resistance value of the core-bearing metal layer is Ω / □ or more. When the surface resistance value of the core-bearing metal layer is within the above range, the core-bearing metal layer does not have electrical conductivity and can become a discontinuous film with a sea-island structure. Therefore, the conductive film for circuit boards has better etching properties in the post-process. In this embodiment, the surface resistance value can be measured by immersing the film in an aqueous ferric chloride solution for 15 seconds, and then measuring the surface insulation at a measurement voltage of DC 500V using an LCR HiTester (LCR HiTester 3532-50, manufactured by Hioki E.E. Corporation).

[0036] FIG. 2 is a graph showing the relationship between the thickness of the seed metal layer and the surface resistance value. This graph is a graph in which a SiCo film (Si-50Co) is formed by magnetron sputtering to a predetermined thickness as the seed metal layer on a substrate (PET film, thickness 50 μm), a thin copper layer (thickness 0.12 μm) is then formed by magnetron sputtering, and the plated copper layer (thickness 20 μm) is patterned by electrolytic plating, and the obtained sample is etched by the same method as above, and then the surface resistance value is measured and plotted. As shown in FIG. 2, according to the approximation curve of each measurement result, when the thickness of the SiCo film is 1.5 nm or less, the surface resistance value is 1.0×10 10 (Ω / □) or more. Thus, when the thickness of the nucleated metal layer is 1.5 nm or less, the conductive film for circuit boards of this embodiment exhibits excellent insulating properties, and therefore has excellent etching properties. Note that while FIG. 2 relates to a SiCo film, the same applies when simple Si, an alloy of Si and other metals, or other compounds containing Si are used instead of SiCo. In particular, the resistance values ​​of oxides, nitrides, oxynitrides, etc. of simple Si and alloys of Si and other metals are higher than the resistance values ​​of simple Si and alloys of Si and other metals. Therefore, when the thickness of the nucleated metal layer is 1.5 nm or less, the surface resistance value is 1.0×10 10 This still means that it can be greater than (Ω / □).

[0037] The resistivity of the core metal layer is 1.0×10 -3 It is preferable that the resistance is Ω·m or more, and 1.0×10 -2 More preferably, it is 1.0×10 -1 It is more preferable that the resistivity of the core-bearing metal layer is Ω·m or more. When the resistivity of the core-bearing metal layer is within the above range, the core-bearing metal layer does not have electrical conductivity and can become a discontinuous film with a sea-island structure. Therefore, the conductive film for circuit boards has excellent etching properties in the post-processing.

[0038] The thickness of the nucleated metal layer is not particularly limited. For example, the thickness of the nucleated metal layer is preferably 0.1 nm or more, more preferably 0.2 nm or more, and even more preferably 0.3 nm or more. The thickness of the nucleated metal layer may be 1.5 nm or less, preferably 1.3 nm or less, and more preferably 1.0 nm or less. When the thickness of the nucleated metal layer is within the above range, the conductive film for circuit board can achieve both adhesion and etching properties. In particular, when the thickness of the nucleated metal layer exceeds 1.5 nm, the conductive film for circuit board is likely to deteriorate in etching properties and deteriorate in productivity due to the increased film thickness, which is likely to impair economic efficiency.

[0039] In this embodiment, the seeded metal layer has fine irregularities. The thickness of the seeded metal layer described above is the average thickness when it is assumed that the seeded metal is evenly laminated on the substrate. In this embodiment, the average thickness of the seeded metal layer can be measured using a fluorescent X-ray measurement device. Specifically, first, a substrate on which a seeded metal layer of a predetermined thickness is formed is prepared, and the physical film thickness of the seeded metal layer of the predetermined thickness is measured using a contact step gauge. In addition, the amount of the seeded metal layer in the seeded metal layer of the predetermined thickness is measured by quantitative analysis using a fluorescent X-ray measurement device (XRF, Primini (tabletop wavelength dispersive X-ray fluorescence analyzer), manufactured by Rigaku Corporation). A calibration curve is created from the film thickness measured by the contact step gauge and the amount of the seeded metal layer material measured by quantitative analysis using XRF. Each element component derived from the seeded metal layer is detected by quantitative analysis using XRF for the film, and the average value of the measured values ​​at 10 points is taken as the average thickness. The average thickness of the seed-bearing metal layer may be considered to be the average value in the fine unevenness profile. This is also true even if the seed-bearing metal layer is a discontinuous film and exists in a scattered state.

[0040] The method of providing the seed metal layer on the substrate is not particularly limited. As an example, the seed metal layer can be provided by a dry plating method. Dry plating methods include sputtering, magnetron sputtering, vacuum deposition, ion beam, and CVD. From the viewpoint of controlling the film thickness, magnetron sputtering is preferable.

[0041] Thin copper layer A thin copper layer is applied over the seeded metal layer.

[0042] The thickness of the thin-film copper layer is not particularly limited. For example, the thickness of the thin-film copper layer is preferably 50 nm or more, more preferably 60 nm or more, and even more preferably 70 nm or more. The thickness of the thin-film copper layer is preferably 5 μm or less, more preferably 3 μm or less, and even more preferably 2 μm or less. When the thickness of the thin-film copper layer is within the above range, the conductive film for circuit boards can be easily thickened by electrolytic copper plating. Furthermore, the conductive film for circuit boards has excellent productivity.

[0043] The method for providing the thin-film copper layer is not particularly limited. For example, the thin-film copper layer can be formed by a conventionally known physical vapor deposition method such as a vacuum deposition method, a sputtering method, or an ion plating method, or a chemical vapor deposition method. The deposition conditions can be appropriately selected from conventionally known conditions based on the desired thickness of the thin-film copper layer.

[0044] The conductive film for circuit boards of the present embodiment described above has excellent adhesion between the substrate and the thin-film copper layer, and also has excellent etching properties and plating solution resistance required in later processes for forming a circuit board.

[0045] Second embodiment The conductive film for circuit boards according to one embodiment of the present invention is the conductive film for circuit boards described above in relation to the first embodiment, except that the coating layer is a thin-film copper layer and a nickel alloy layer is also provided on the substrate side. The core metal layer is provided on the nickel alloy layer. That is, this embodiment is an example in which a thin-film copper layer and a nickel metal layer are provided as coating layers. As a result, the conductive film for circuit boards according to this embodiment has better adhesion between the substrate and the thin-film copper layer. In the following description, the description of matters common to the first embodiment will be omitted as appropriate.

[0046] Fig. 3 is a schematic cross-sectional view of a conductive film for circuit boards 1a of this embodiment. As shown in Fig. 3, the conductive film for circuit boards 1a of this embodiment includes a base material 2a, a seed metal layer 4a including seed metals 3a, a nickel alloy layer 8, and a thin-film copper layer 5a, in this order. In Fig. 3, reference numeral 7a denotes a plated copper layer provided in the film for circuit boards, which will be described later. The coating layer 6a covers the base material 2 and includes the seed metal layer 4a, the nickel alloy layer 8, and the thin-film copper layer 5a.

[0047] Nickel alloy layer The nickel alloy layer is disposed between the seed metal layer and the thin copper layer.

[0048] The nickel alloy constituting the nickel alloy layer is not particularly limited. For example, the alloy components contained in the nickel alloy are Cu, Cr, Ti, Mo, Fe, etc. As a result, the nickel alloy is, for example, a Ni-Cu alloy, a Ni-Cr alloy, a Ni-Cu-Ti alloy, etc. By adopting these as the nickel alloy, the conductive film for circuit boards has better adhesion. Regarding nickel and other alloy components, for example, "Ni-35Cu" and "Ni-7Cr" are both composition ratios of the sputtering target. In this embodiment, it has been confirmed that the composition ratios in the sputtered film when the film is formed using these targets are the same as the composition ratios of the target.

[0049] The content of the nickel alloy in the nickel alloy layer is not particularly limited. For example, the content of the nickel alloy is preferably 95 mass% or more, more preferably 99 mass% or more, and even more preferably 99.5 mass% or more. In this embodiment, the nickel alloy layer may contain impurities that are inevitably contained in addition to the nickel alloy.

[0050] The thickness of the nickel alloy layer is not particularly limited. For example, the thickness of the nickel alloy layer is preferably 3 nm or more, more preferably 4 nm or more, and even more preferably 5 nm or more. The thickness of the nickel alloy layer is preferably 100 nm or less, more preferably 50 nm or less, and even more preferably 25 nm or less. When the thickness of the nickel alloy layer is within the above range, the conductive film for circuit boards has excellent adhesion and excellent productivity.

[0051] In this embodiment, whether the nucleated metal is in a state of being scattered on the substrate can be understood, for example, by observing an SEM photograph of the peel interface and confirming the traces of the nucleated metal in the nucleated metal layer. FIG. 4 is an SEM photograph (metal side) of the peel interface of a specific example (Example 39 described later) of the conductive film for circuit boards of this embodiment. Specifically, the conductive film for circuit boards produced in Example 39 described later is peeled at the interface between the substrate and the nucleated metal layer. Thereafter, the traces of the nucleated metal can be understood by obtaining an SEM photograph from the metal layer side. As shown in FIG. 4, the nucleated metal layer 4a has many scattered recesses 3b, which are traces of the nucleated metal.

[0052] The method of providing the nickel alloy layer is not particularly limited. For example, the nickel alloy layer can be formed by a conventionally known physical vapor deposition method such as a vacuum deposition method, a sputtering method, or an ion plating method, or a chemical vapor deposition method. The deposition conditions can be appropriately selected from conventionally known conditions based on the desired thickness of the nickel alloy layer.

[0053] The conductive film for circuit boards of the present embodiment has excellent adhesion between the substrate and the thin copper layer, and has excellent etching properties and plating solution resistance required in the post-process for forming the circuit board. In addition, the conductive film for circuit boards of the present embodiment has a nickel alloy layer, which further improves adhesion between the substrate and the thin copper layer.

[0054] <Film for circuit boards> 1, a film for circuit board 9 according to one embodiment of the present invention includes the above-mentioned conductive film for circuit board 1 and a plated copper layer 7 provided on a thin copper layer 5. Each of these will be described below. In the following description, the conductive film for circuit board constituting the film for circuit board is similar to the above-mentioned conductive film for circuit board, and therefore a description of common points will be omitted as appropriate.

[0055] ·Plated copper layer A plated copper layer is provided over the thin film copper layer.

[0056] The method for providing the plated copper layer is not particularly limited. For example, the plated copper layer may be provided by electrolytic plating. The electrolytic plating conditions may be appropriately selected from conventionally known conditions based on the desired thickness of the plated copper layer.

[0057] Furthermore, when a circuit board is produced, the plated copper layer is patterned to form a circuit pattern. An etching solution is generally used to form the circuit pattern. Here, the wiring that is cut into the pattern must be insulated from each other. Therefore, during etching, not only the plated copper layer and thin copper layer, but also the underlying nucleated metal layer (and nickel alloy layer) must be removed with the etching solution. As mentioned above, the surface resistance of the nucleated metal layer after etching is 1.0×10 10 Therefore, it can be said that the film for circuit boards is sufficiently etched and has excellent etching properties.

[0058] The thickness of the plated copper layer is not particularly limited. For example, the thickness of the plated copper layer is preferably 1 μm or more, more preferably 2 μm or more. The thickness of the plated copper layer is preferably 50 μm or less, more preferably 30 μm or less. By having the thickness of the plated copper layer within the above range, the film for circuit boards can achieve both low resistance and productivity.

[0059] As described above, according to the film for circuit board of this embodiment, the conductive film for circuit board is used. The conductive film for circuit board has excellent adhesion between the substrate and the thin copper layer, and has excellent etching properties and plating solution resistance required in the post-process for forming the circuit board. Therefore, the obtained film for circuit board is suitable for use as a circuit board. EXAMPLES

[0060] The present invention will be described in more detail below with reference to the following examples. The present invention is not limited to these examples. Unless otherwise specified, "%" means "% by mass" and "parts" means "parts by mass".

[0061] <Example 1> Using a PTFE film (fluororesin substrate, V7990, manufactured by Valqua Corporation) as the substrate, a Si-50Co film was formed by high-pressure pulse sputtering in an argon gas atmosphere under the deposition conditions shown in Table 1 using a high-voltage pulse power supply. Next, a thin-film copper layer was formed under the deposition conditions shown in Table 1 to produce a conductive film for circuit boards. The average thickness of the cored metal layer was measured using an X-ray fluorescence measurement device. Specifically, first, a substrate is prepared on which a seed-bearing metal layer of multiple predetermined thicknesses is formed, the physical film thickness of the seed-bearing metal layer of multiple predetermined thicknesses is measured using a contact step gauge, and the amount of the seed-bearing metal layer in the seed-bearing metal layer of multiple predetermined thicknesses is measured by quantitative analysis using an X-ray fluorescence measurement device (XRF, Primini (tabletop wavelength-dispersive X-ray fluorescence analyzer), manufactured by Rigaku Corporation). A calibration curve is created from the film thickness measured using the contact step gauge and the amount of seed-bearing metal layer material measured by quantitative analysis using XRF, and the film is subjected to quantitative analysis using XRF to detect each element component derived from the seed-bearing metal layer, and the average value of the measured values ​​at 10 locations is used as the average thickness to calculate the thickness.

[0062] <Examples 2 to 5 and Comparative Examples 1 to 7> Conductive films for circuit boards were produced in the same manner as in Example 1, except that the formulation and conditions were changed to those shown in Table 1. In Table 1 and Tables 2 and 3 described below, the substrate was pretreated by plasma treatment in an argon atmosphere.

[0063] [Table 1]

[0064] <Examples 6 to 9 and Comparative Examples 8 to 15> A conductive film for circuit boards was produced in the same manner as in Example 1, except that the substrate was changed to a PI film (polyimide substrate, Kapton 100EN, manufactured by DuPont-Toray Co., Ltd.) and the formulation and conditions were changed to those shown in Table 2.

[0065] [Table 2]

[0066] <Examples 10 to 12 and Comparative Examples 16 to 21> A conductive film for circuit boards was produced in the same manner as in Example 1, except that the substrate was changed to a COP film (cycloolefin polymer substrate, Kapton ZF-16, manufactured by Zeon Corporation) and the formulation and conditions were changed to those shown in Table 3.

[0067] [Table 3]

[0068] <Example 13> Using a PTFE film (fluororesin substrate, V7990, manufactured by Valqua Corporation) as a substrate, a SiCo film was formed by high-pressure pulse sputtering in an argon gas atmosphere using a high-voltage pulse power supply under the deposition conditions shown in Tables 4 and 5. Next, a nickel alloy layer and a thin-film copper layer were formed under the deposition conditions shown in Table 1 to produce a conductive film for circuit boards.

[0069] <Examples 14 to 31 and Comparative Examples 22 to 28> Conductive films for circuit boards were produced in the same manner as in Example 13, except that the formulations and conditions were changed to those shown in Tables 4 and 5. In Tables 4 and 5 and Tables 6 and 7 described below, the substrates were pretreated by plasma treatment in an argon atmosphere.

[0070] [Table 4]

[0071] [Table 5]

[0072] <Examples 32 to 39 and Comparative Examples 29 to 36> A conductive film for circuit boards was produced in the same manner as in Example 13, except that the substrate was changed to a PI film (polyimide substrate, Kapton 100EN, manufactured by DuPont-Toray Co., Ltd.) and the formulation and conditions were changed to those shown in Table 6.

[0073] [Table 6]

[0074] <Examples 40 to 51 and Comparative Examples 37 to 46> A conductive film for circuit boards was produced in the same manner as in Example 13, except that the substrate was changed to a COP film (cycloolefin polymer substrate, Kapton ZF-16, manufactured by Zeon Corporation) and the formulation and conditions were changed to those shown in Table 7.

[0075] [Table 7]

[0076] The conductive films for circuit boards obtained in the above Examples and Comparative Examples were subjected to various evaluations according to the following methods. The results are shown in Tables 1 to 7.

[0077] (1) Adhesion The film was electrolytically plated with copper to a thickness of 20 μm on the deposition side of the film to provide a plated copper layer. The film was then cut into strips of 5 mm width, and the peel strength (peel strength) between the substrate and the metal side containing the plated copper layer was measured at 180° peeling and a pulling speed of 50 mm / min using a peel strength tester (autograph tensile tester, AGS-100G, manufactured by Shimadzu Corporation). In this test, the load applied when peeling the interface between the substrate and the metal layer was measured. In this case, peeling occurred at the weakest part, so it was thought that peeling could occur at the interface between the substrate and the metal layer (thin film copper layer or nickel alloy layer) or due to material destruction of the substrate.

[0078] (2) Etching properties The film was immersed in an aqueous solution of ferric chloride for 15 seconds, and then the surface insulation was measured at a measurement voltage of DC 500 V using an LCR Hitester (LCR Hitester 3532-50, manufactured by Hioki E.E. Corporation). The etching property was evaluated according to the following evaluation criteria. (Evaluation Criteria) ○: After immersion in an aqueous solution of ferric chloride (15 seconds), the surface resistance of the film is 1.0×10 10 It was Ω / □ or more. ×: After immersion in an aqueous solution of ferric chloride (15 seconds), the surface resistance of the film is 1.0×10 10 It was less than Ω / □.

[0079] (3) Plating solution resistance After forming a core-coated metal layer and a thin copper layer on the film, the film was immersed in a plating solution (aqueous solution of copper sulfate pentahydrate) for a specified time in the electrolytic copper plating process to evaluate the presence or absence of a thin film on the film when electrolytic copper plating was performed. (Evaluation Criteria) ◯: After immersion in an electrolytic plating solution (aqueous solution of copper sulfate pentahydrate), a thin film was formed on the film and the state was maintained. ×: After immersion in the electroplating solution (aqueous solution of copper sulfate pentahydrate), the state in which a thin film was formed on the film could not be maintained, and the core-attached metal layer and the thin copper layer peeled off or dissolved.

[0080] As shown in Tables 1 to 7, the conductive films for circuit boards and the films for circuit boards of the examples of the present invention all had excellent adhesion between the substrate and the thin-film copper layer, as well as excellent etching properties and plating solution resistance required in the post-processing for forming a circuit board. [Explanation of symbols]

[0081] 1, 1a Conductive film for circuit boards 2, 2a base material 3, 3a cored metal 3b recess 4, 4a Nucleated metal layer 5, 5a thin copper layer 6, 6a Covering layer 7, 7a Plated copper layer 8 Nickel alloy layer 9 Film for circuit boards

Claims

1. A substrate and a coating layer covering the substrate and including a cored metal layer including a cored metal, in this order; The seeded metal layer contains silicon, The core metal is provided in a scattered state on the substrate, the coating layer comprises a thin film copper layer; A conductive film for circuit boards, wherein the average thickness of the core-containing metal layer is 1.5 nm or less when it is assumed that the core-containing metal is evenly layered on the substrate.

2. The conductive film for circuit boards according to claim 1 , wherein the coating layer further comprises a nickel alloy layer on the substrate side.

3. 3. The conductive film for circuit boards according to claim 1, wherein the core-coated metal layer is provided on the thin-film copper layer.

4. The conductive film for circuit boards according to claim 2 , wherein the core-containing metal layer is provided on the nickel alloy layer.

5. The surface resistance of the metal layer is 1.0×10 10 3. The conductive film for circuit boards according to claim 1, wherein the resistivity is Ω / □ or more.

6. The resistivity of the metal layer is 1.0×10 -3 The conductive film for circuit boards according to claim 1 or 2, having a resistance of Ω·m or more.

7. 3. A film for circuit boards, comprising: the conductive film for circuit boards according to claim 1 or 2; and a plated copper layer provided on the thin copper layer.

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