Manufacturing method of wiring board

Abstract

To provide a manufacturing method of a wiring board which can form a conductor wiring pattern that is fine and hardly peeled off on an insulation layer whose dielectric constant and dielectric loss tangent are low.SOLUTION: A manufacturing method of a wiring board comprises: a step (A) of forming a resin layer 12 to contact with at least one surface 11a of a support plate 11; a step (B) of forming an insulator layer 14 through hardening the resin layer 12; a step (C) of roughening a surface 14a of the insulator layer 14 through plasma treatment that does not contact with the support plate 11; and a step (D) of forming a seed layer 15 through sputtering treatment on the roughened surface 14a of the insulator layer 14. Arithmetic average roughness Ra of the surface 14a made by roughening the insulator layer 14 is 30 to 500 nm, and dielectric loss tangent of the insulator layer 14 is 0.004 or less at 10 GHz.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a wiring board.

Background Art

[0002] With the increase in the amount of information processing in various electronic devices, mounting technologies such as high integration, high wiring density, and multilayerization of semiconductor devices mounted thereon have been evolving. In addition, as a wiring board used in various electronic devices, for example, in a substrate for server applications for communication infrastructure, a wiring board compatible with high frequencies is required. In the insulating layer of the wiring board used in various electronic devices, in order to increase the signal transmission speed and reduce the loss during signal transmission, it is required that the dielectric properties such as relative permittivity and dielectric tangent are low. Further, when forming a wiring board used in various electronic devices, a conductor wiring pattern is formed on the insulating layer. For example, when forming a rewiring layer such as a build-up layer for multilayerization, an insulating layer is formed on an inner layer substrate or the like, and a conductor wiring pattern is formed on the formed insulating layer. Examples of the method for forming such a conductor wiring pattern include a method of forming a conductor wiring pattern after performing a predetermined treatment on the insulating layer. For example, a method for manufacturing a printed wiring board described in Patent Document 1 can be mentioned.

[0003] Patent Document 1 describes a method for manufacturing a printed wiring board, including: (A) a step of laminating a resin composition layer of an adhesive film including a support and a resin composition layer so as to be joined to one surface or both surfaces of an inner layer substrate; (B) a step of thermally curing the resin composition layer to form an insulating layer; (C) a step of peeling the support; (D) a step of roughening the surface of the insulating layer; and (E) a step of forming a wiring pattern of 20 μm or less, wherein in step (A), the arithmetic mean roughness Ra of the surface of the support in contact with the resin composition layer is 200 nm or more, the dielectric tangent of the insulating layer formed in step (B) is 0.005 or less, and the arithmetic mean roughness Ra of the surface of the insulating layer after step (D) is 200 to 800 nm. According to Patent Document 1, it is disclosed that the adhesion of the dry film can be improved despite the low dielectric tangent.

Prior Art Documents

Patent Document

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In electronic devices, especially in small portable devices such as mobile communication terminals and notebook computers, diversification, high performance, thinning, and miniaturization are rapidly progressing. Along with this, in the wiring boards used in these products, further high performance is required in terms of miniaturization of conductor wiring in the conductor wiring pattern, multilayerization, thinning, and mechanical properties, etc. of the conductor wiring layer. For this reason, miniaturization of the conductor wiring pattern, for example, miniaturization of the conductor wiring pattern in an inner layer substrate, etc. is required. Therefore, in the manufacturing method of the wiring board, it is required that a finer conductor wiring pattern can be formed on the insulating layer, etc., and further, even if the formed conductor wiring pattern is miniaturized, the conductor wiring pattern is difficult to peel off from the insulating layer.

[0006] The present invention has been made in view of such circumstances, and an object thereof is to provide a manufacturing method of a wiring board capable of forming a fine and difficult - to - peel conductor wiring pattern on an insulating layer having low dielectric properties such as dielectric loss tangent.

Means for Solving the Problems

[0007] As a result of various studies, the present inventors have found that the above object is achieved by the following present invention.

[0008] A method for manufacturing a wiring board according to an aspect of the present invention includes a step (A) of forming a resin layer so as to be in contact with at least one surface of a support plate, a step (B) of curing the resin layer to form an insulating layer, a step (C) of roughening the surface of the insulating layer on the side not in contact with the support plate by plasma treatment, and a step (D) of forming a seed layer on the roughened surface of the insulating layer by sputtering treatment. The arithmetic mean roughness Ra of the roughened surface of the insulating layer is 30 to 500 nm, and the dielectric tangent of the insulating layer is 0.004 or less at 10 GHz. This is a method for manufacturing a wiring board.

Effect of the Invention

[0009] According to the present invention, it is possible to provide a method for manufacturing a wiring board capable of forming a fine and difficult-to-peel conductor wiring pattern on an insulating layer having low dielectric characteristics such as a dielectric tangent.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Mode for Carrying Out the Invention

[0011] As a method for forming a conductor wiring pattern on an insulating layer, for example, a semi-additive method is known in which the surface of the insulating layer is roughened and then electroless plating and electroplating are performed to form the conductor wiring pattern. In such a method for forming a conductor wiring pattern, as the roughening treatment, a roughening solution such as an alkaline permanganate solution may be used. Further, when forming a multilayer wiring board, in order to conduct between wirings in the conductor wiring patterns formed on different insulating layers, vias may be formed in the insulating layer. After forming these vias, desmear treatment may be performed to remove smears at the bottom of the vias. This desmear treatment may also use, for example, an alkaline permanganate solution or the like and can also serve as the roughening treatment. Thus, when forming a conductor wiring pattern on an insulating layer, so-called wet processing such as the roughening treatment and the desmear treatment may be performed. For example, the method for manufacturing a printed wiring board described in Patent Document 1 is so-called wet processing such as roughening the surface of an insulating layer by swelling treatment with a swelling solution. According to the studies by the present inventors, when forming a fine conductor wiring pattern by such wet processing, the formed conductor wiring pattern may be easily peeled off. Further, according to the studies by the present inventors, it has been found that dry processing such as plasma treatment and sputtering treatment can form a finer conductor wiring pattern than such wet processing. Then, as a result of various studies, the present inventors have found a method for manufacturing a wiring board capable of forming a conductor wiring pattern that is difficult to peel off even when a fine conductor wiring pattern is formed by dry processing on an insulating layer having a low dielectric tangent. That is, as a result of various studies, the present inventors have found that the above object of providing a method for manufacturing a wiring board capable of forming a fine and difficult-to-peel conductor wiring pattern on an insulating layer having low dielectric characteristics such as dielectric tangent is achieved by the following present invention.

[0012] Hereinafter, embodiments according to the present invention will be described, but the present invention is not limited thereto.

[0013] The method for manufacturing a wiring board according to an embodiment of the present invention includes a step (A) of forming a resin layer so as to contact at least one surface of a support plate, a step (B) of curing the resin layer to form an insulating layer, a step (C) of roughening the surface of the insulating layer on the side not in contact with the support plate by plasma treatment, and a step (D) of forming a seed layer on the roughened surface of the insulating layer by sputtering treatment. In the method for manufacturing the wiring board, the arithmetic mean roughness Ra of the roughened surface of the insulating layer is 30 to 500 nm. The dielectric tangent of the insulating layer is 0.004 or less at 10 GHz. When a conductor wiring pattern is formed using the seed layer formed by this manufacturing method, a conductor wiring pattern that is fine and difficult to peel off is formed. Therefore, the manufacturing method can form a fine and difficult-to-peel conductor wiring pattern on an insulating layer having low dielectric characteristics such as a dielectric tangent. That is, the manufacturing method may simply form a conductor wiring pattern based on the seed layer, and specifically, may further include a step (E) of forming a conductor wiring pattern on the seed layer.

[0014] The step (A) is not particularly limited as long as a resin layer can be formed so as to contact at least one surface (one-sided or both-sided) of the support plate. Examples of the step (A) include a method of applying a resin composition onto the support plate (coating method) and a method of laminating a resin film onto the support plate (laminating method). Specifically, examples of the coating method include a method of forming the resin layer on the support plate by applying a fluid resin composition (such as a resin varnish and a resin solution) onto the support plate and drying the applied resin composition. Further, specifically, examples of the laminating method include a method of laminating a resin film that becomes the resin layer onto the support plate. More specifically, examples of this method include a method of laminating the resin film laminated on a release film onto the support plate and then peeling the release film from the resin film. Examples of the lamination of this resin film include a vacuum lamination method. Further, examples of the resin film include a resin film formed by applying a fluid resin composition (such as a resin varnish and a resin solution) onto a release film and drying the resin composition applied to the release film.

[0015] The support plate is not particularly limited as long as it has an insulating layer (an insulating layer on which a seed layer is formed) on its surface. Examples of the support include a resin film, a metal foil, a metal plate, a metal-clad laminate, and an inner layer substrate.

[0016] The resin layer is not particularly limited as long as, by curing it, an insulating layer having a dielectric tangent of 0.004 or less at 10 GHz can be obtained (the dielectric tangent of the insulating layer obtained after curing is 0.004 or less at 10 GHz). Examples of the resin layer include a resin composition containing a curable compound and a filler (the resin composition before curing), or a layer containing a semi-cured product of the resin composition. Further, the thickness of the resin layer is not particularly limited, but examples include 5 to 40 μm.

[0017] The step (B) is not particularly limited as long as the resin layer can be cured to form an insulating layer. Examples of the step (B) include curing in a vacuum state, that is, vacuum curing and the like. Further, if the resin layer is thermosetting, methods such as heating the resin layer can be mentioned. The conditions for curing the resin layer are not particularly limited as long as the resin layer can be cured to form the insulating layer. As these conditions, for example, the heating temperature is preferably 80 to 250°C, more preferably 100 to 230°C. Further, the heating time is preferably 1 to 4 hours, more preferably 1.5 to 3 hours. More specifically, as the method of heating the resin layer, after heating from room temperature to a predetermined temperature within 80 to 150°C and holding for about 30 minutes, further heating to a predetermined temperature within 180 to 230°C and holding the predetermined temperature for 1 to 4 hours can be mentioned. Further, the method of heating the resin layer may be the above-mentioned vacuum curing. Further, as the step (B), for example, if the resin layer is photocurable, methods such as irradiating the resin layer with light such as ultraviolet rays can be mentioned.

[0018] The insulating layer is a layer formed by curing the resin layer. That is, the insulating layer is not particularly limited as long as the dielectric tangent is 0.004 or less at 10 GHz. The dielectric tangent of the insulating layer is 0.004 or less at 10 GHz, and preferably 0.0005 to 0.003. Also, the relative permittivity of the insulating layer preferably has a relative permittivity of 2 to 3 at 10 GHz, and more preferably 2 to 2.8. Here, the relative permittivity and dielectric tangent are the relative permittivity and dielectric tangent of the insulating layer at a frequency of 10 GHz, and examples include the relative permittivity and dielectric tangent of the insulating layer at a frequency of 10 GHz measured by the cavity resonator perturbation method. The thermal expansion coefficient (CTE: Coefficient of Thermal Expansion) of the insulating layer is preferably 15 to 80 ppm / °C, and more preferably 15 to 60 ppm / °C. When the thermal expansion coefficient is within the above range, the dimensional change rate of the insulating layer due to heating becomes small. The thermal expansion coefficient is a value representing the ratio of the expansion of the length of an object per 1°C due to an increase in temperature, and examples include the thermal expansion coefficient measured by the TMA (Thermo-mechanical analysis) method. More specifically, the thermal expansion coefficient measured by the TMA method in the temperature range of 50 to 100°C can be mentioned.

[0019] The step (C) is not particularly limited as long as the insulating layer can be roughened by plasma treatment so that the arithmetic mean roughness Ra of the surface of the insulating layer is 30 to 500 nm. In the step (C), since plasma treatment is performed on the insulating layer on the support, the surface of the insulating layer on the side opposite to the surface in contact with the support (the side not in contact with the support) is plasma-treated. The arithmetic mean roughness Ra of the roughened surface of the insulating layer is 30 to 500 nm as described above, preferably 30 to 400 nm, and more preferably 30 to 300 nm.

[0020] The plasma treatment is not particularly limited as long as the arithmetic mean roughness of the roughened surface of the insulating layer becomes 30 to 500 nm by applying this plasma treatment to the insulating layer. Examples of the plasma treatment include oxygen gas plasma treatment (surface treatment using plasma generated using oxygen gas as a source gas), mixed gas plasma treatment of oxygen and carbon tetrafluoride (surface treatment using plasma generated using a mixed gas of oxygen and carbon tetrafluoride as a source gas), and mixed gas plasma treatment of argon, hydrogen, and nitrogen (surface treatment using plasma generated using a mixed gas of argon, hydrogen, and nitrogen as a source gas). Among these, the oxygen gas plasma treatment is preferable as the plasma treatment. Also, these plasma treatments may be used alone or in combination of two or more.

[0021] The conditions of the plasma treatment are not particularly limited as long as the arithmetic mean roughness is 30 to 500 nm. The irradiation amount of the plasma in the plasma treatment is preferably 100 to 500 W / cm 2 in terms of watt density. The time for applying the plasma treatment varies depending on the amount of the source gas, plasma density, etc., but is preferably, for example, 0.5 to 5 minutes.

[0022] As the plasma treatment, a treatment using microwave plasma (plasma excited by microwaves) may be used, or RF (Radio Frequency) plasma (plasma excited by RF) may be used. These plasmas may be pulse-excited or DC-excited. As the microwaves, for example, microwaves having a frequency of 1 GHz or higher, which are in an industrially usable frequency band and can generate a high-density non-equilibrium plasma, can be used, and it is preferable to use microwaves having a frequency of 2.45 GHz. In the case of the microwave plasma, for example, the microwave power when generating the plasma atmosphere can be 300 W or more. Further, the RF plasma is a plasma widely used in the industrial world, and the excitation frequency used for generating the RF plasma is generally 13.56 MHz in Japan from the viewpoint of legal regulations and the like.

[0023] The step (D) is not particularly limited as long as a seed layer can be formed on the roughened surface of the insulating layer by sputtering treatment. The sputtering treatment is not particularly limited as long as the seed layer can be formed on the roughened surface of the insulating layer.

[0024] Examples of the sputtering treatment include sputtering treatment using the metal constituting the seed layer as a target. Further, examples of the sputtering treatment include sputtering treatment performed under vacuum. Specifically, the sputtering treatment includes a process in which the metal constituting the seed layer is installed as a target in a vacuum chamber, a gas ionized by applying a high voltage is collided with the target, atoms of the metal are separated from the target surface, and deposited on the roughened surface of the insulating layer to form a film. Examples of the gas include noble gases such as argon and nitrogen. Further, examples of the sputtering treatment include treatments by a direct current (DC) sputtering method, a radio frequency (RF) sputtering method, a DC magnetron sputtering method, an RF magnetron sputtering method, and an ion beam sputtering method.

[0025] The seed layer is not particularly limited as long as it is a seed layer formed on the surface of an insulating layer or the like when manufacturing a wiring board. For example, when subsequently forming a conductor wiring pattern and a conductor layer by an electroplating process or the like, the seed layer is used as an electrode. That is, when an electroplating process is performed subsequently, the seed layer acts as a power supply layer for the electrolytic plating process. Examples of the metal contained in the seed layer include titanium (Ti), chromium (Cr), nickel (Ni), tungsten (W), copper (Cu), cobalt (Co), aluminum (Al), molybdenum (Mo), tantalum (Ta), iridium (Ir), ruthenium (Ru), lead (Pb), gold (Au), and platinum (Pt). Among these, it is preferable to contain any one of Ti, Cr, Ni, and W. This metal may be used alone or in combination of two or more. That is, the seed layer preferably contains at least one selected from the group consisting of Ti, Cr, Ni, and W. Further, the seed layer may include a seed layer main body and a seed adhesion layer for improving the adhesion of the seed layer main body to the insulating layer or the like. Examples of the seed layer include a layer formed by laminating a Ti-containing layer (for example, a layer made of Ti) as the seed adhesion layer and a Cu-containing layer (for example, a layer made of Cu) as the seed layer main body. Examples of the thickness of the seed layer include 200 to 350 nm. When the seed layer includes the seed layer main body and the seed adhesion layer, examples of the thickness of the seed layer main body include 150 to 250 nm, and examples of the thickness of the seed adhesion layer include 50 to 100 nm.

[0026] As described above, the manufacturing method may form a conductor wiring pattern based on the seed layer. Specifically, it may further include a step (E) of forming a conductor wiring pattern on the seed layer. The step (E) is not particularly limited as long as a conductor wiring pattern can be formed using the seed layer. For example, methods such as forming a wiring layer by electrolytic plating treatment can be mentioned. Examples of the electroplating treatment include electrolytic nickel plating, electrolytic copper plating, electrolytic chromium plating, electrolytic palladium plating, electrolytic gold plating, electrolytic rhodium plating, electrolytic iridium plating, etc. Among these, electrolytic copper plating is preferable. Examples of the thickness of this wiring layer include 15 to 35 μm, etc.

[0027] According to the manufacturing method, the conductor layer formed using the obtained seed layer is difficult to peel off from the insulating layer. Further, the manufacturing method is a dry process such as plasma treatment and sputtering treatment, rather than a wet process, and can form a finer conductor wiring pattern. Therefore, when a conductor wiring pattern is formed using the seed layer formed by this manufacturing method, a conductor wiring pattern that is fine and difficult to peel off is formed. That is, the manufacturing method can form a fine and difficult-to-peel conductor wiring pattern on an insulating layer with low dielectric properties such as dielectric tangent.

[0028] The minimum value of the width of the wiring in the conductor wiring pattern is not particularly limited, but is preferably 25 μm or less, and more preferably 0.5 to 15 μm. That is, the conductor wiring pattern preferably includes wiring having a width of 25 μm or less, and more preferably includes wiring having a width of 0.5 to 15 μm. By forming a wiring board having such a conductor wiring pattern with a minimum wiring width of 25 μm or less on an insulating layer, that is, a wiring board including at least a part of a portion where the wiring width is 25 μm or less, the wiring in the wiring board can be made denser. For example, the wiring board can be made smaller. Further, by making the wiring in the wiring board denser, it becomes easier to handle a wiring board corresponding to high frequencies. According to the manufacturing method, such a fine and difficult-to-peel conductor wiring pattern can be suitably formed on the insulating layer. Here, the wiring width is the distance perpendicular to the longitudinal direction of the wiring.

[0029] The minimum value of the distance between wirings in the conductor wiring pattern is not particularly limited, but is preferably 25 μm or less, and more preferably 0.5 to 15 μm. By using a wiring board having such a minimum distance between wirings of 25 μm or less, that is, a wiring board including a conductor wiring pattern including at least a part of a portion where the distance between wirings is 25 μm or less, the wiring in the wiring board can be made denser. For example, the wiring board can be made smaller. Further, by making the wiring in the wiring board denser, it becomes easier to handle a wiring board corresponding to high frequencies. According to the manufacturing method, even if the minimum value of the distance between wirings is 15 μm or less, the conductor wiring pattern can be suitably formed on the insulating layer. Here, the distance between wirings is the distance between adjacent wirings.

[0030] The wiring board may be a multilayer wiring board having two or more wiring layers. That is, the number of wiring layers in the wiring board is not particularly limited, but may be two or more, and preferably three or more. By using such a multilayered wiring board, it becomes easier to handle a wiring board compatible with high frequencies. In the multilayered wiring board, through holes and vias for making conductive connections between the multilayered wiring layers may be formed as necessary. That is, through holes and vias may be formed in the insulating layer. In the multilayer wiring board, only through holes may be formed, only vias may be formed, or both may be formed. Further, the through holes and the vias may be formed in the insulating layer as necessary, respectively, and the number thereof may be one or a plurality. The seed layer formed in the manufacturing method may be formed on the roughened surface of the insulating layer, or may be formed on the surfaces of the through holes and the vias.

[0031] Specific examples of the manufacturing method include the manufacturing method shown in FIG. 1. Note that FIG. 1 is a schematic diagram for explaining the manufacturing method of the wiring board according to the present embodiment.

[0032] First, as shown in FIG. 1(a), a release film 13 having a resin layer 12 is laminated on a support plate 11 such that the resin layer 12 contacts the surface 11a of the support plate 11. At that time, the support plate 11 and the resin layer 12 may be adhered by vacuum lamination or the like as described above. By doing so, as shown in FIG. 1(b), the support plate 11 and the resin layer 12 are laminated, and the resin layer 12 is formed on the surface 11a of the support plate 11. This step corresponds to the step (A). Here, as the support plate 11, a metal-clad laminate or the like including an insulating layer 112 and a metal foil 111 provided on the surface of the insulating layer 112 is used, but it is not limited thereto.

[0033] Next, as shown in FIG. 1(b), the resin layer 12 formed on the surface of the support plate 11 is cured with the release film 13 attached. At this time, the resin layer 12 may be cured by vacuum curing (for example, curing by heating under vacuum) as described above. By doing so, as shown in FIG. 1(c), an insulating layer 14 obtained by curing the resin layer 12 is formed on the surface of the support plate 11. Thereafter, as shown in FIG. 1(c), the release film 13 is peeled off. This step corresponds to the step (B).

[0034] Next, as shown in FIG. 1(d), the plasma treatment is performed on the surface 14a of the insulating layer 14 that does not contact the support plate 11. By doing so, this surface 14a becomes a roughened surface (a roughened surface with an arithmetic mean roughness of 30 to 500 nm). This step corresponds to the step (C).

[0035] Next, a sputtering treatment is performed on the roughened surface 14a of the insulating layer 14. By doing so, as shown in FIG. 1(e), a seed layer 15 is formed on the roughened surface 14a of the insulating layer 14. Here, the seed layer 15 is not limited to a seed layer including a seed layer main body 152 and a seed adhesion layer 151 that improves the adhesion of the seed layer main body 152 to the insulating layer 14. Further, examples of the seed adhesion layer 151 include a Ti layer. Further, examples of the seed layer main body 152 include a Cu layer. This step corresponds to the step (D).

[0036] Next, as shown in FIG. 1(f), a conductor layer 16 is formed using the seed layer 15. Specifically, by performing an electroplating treatment using the seed layer 15, a conductor layer 16 integrated with the seed layer main body 152 can be formed. The conductor layer 16 may be formed so as to be a conductor wiring pattern.

[0037] As described above, the conductor layer 16 formed using the obtained seed layer 15 is difficult to peel off from the insulating layer 14. Therefore, even if the conductor layer 16 is formed into a fine conductor wiring pattern, the obtained conductor wiring pattern is difficult to peel off. From this, according to the manufacturing method, it is a method for manufacturing a wiring board, and a fine and difficult-to-peel conductor wiring pattern can be formed.

[0038] As the manufacturing method, when forming a conductor wiring pattern, specifically, a manufacturing method as shown in FIG. 2 and the like can be mentioned. Note that FIG. 2 is a schematic diagram for explaining a specific example of the manufacturing method of the wiring board according to the present embodiment.

[0039] First, as shown in FIG. 2(a), a release film 13 provided with a resin layer 12 is overlapped on a support plate 11 so that the resin layer 12 contacts the surface 11a of the support plate 11, whereby, as shown in FIG. 2(b), the resin layer 12 is formed on the surface of the support plate 11.

[0040] Next, the resin layer 12 formed on the surface of the support plate 11 as shown in FIG. 2(b) is cured while the release film 13 is attached. By doing so, an insulating layer 14 obtained by curing the resin layer 12 is formed on the surface of the support plate 11.

[0041] Next, laser processing is performed on the insulating layer 14 obtained by curing the resin layer 12 while the release film 13 is attached, to form a recess 22 in the insulating layer 14. This recess 22 corresponds to the conductor wiring pattern to be finally formed. The laser processing is not particularly limited as long as a recess corresponding to the conductor wiring pattern can be formed in the insulating layer 14. For example, CO 2Examples include a laser and a UV laser. Then, a plasma desmear treatment is performed on the recess 22 formed in the insulating layer 14. By doing so, the residue (smear) of the insulating layer 14 generated by the laser processing can be removed from the recess 22. The plasma desmear treatment is not particularly limited as long as desmear can be performed using plasma. For example, the same treatment as the plasma treatment can be mentioned. Here, among them, a mixed gas plasma treatment of oxygen and carbon tetrafluoride (surface treatment using plasma generated using a mixed gas of oxygen and carbon tetrafluoride as a source gas) is preferable.

[0042] Next, as shown in FIG. 2(d), the release film 13 is peeled off from the insulating layer 14 in which the recess 22 is formed. Next, the plasma treatment is performed on the surface 14a of the insulating layer 14 on the side not in contact with the support plate 11. By doing so, this surface 14a becomes a roughened surface (roughened surface with an arithmetic mean roughness of 30 to 500 nm).

[0043] Next, a sputtering treatment is performed on the roughened surface 14a of the insulating layer 14. By doing so, as shown in FIG. 2(e), a seed layer 15 is formed on the roughened surface 14a of the insulating layer 14.

[0044] Next, as shown in FIG. 2(f), a resist layer 18 is formed on the insulating layer 14 on which the seed layer 15 is formed. Then, as shown in FIG. 2(g), the resist layer 18 is selectively exposed and developed so that the resist layer 18 remains except for the location where the conductor layer 19 is to be formed later (the location corresponding to the finally formed conductor wiring pattern). Next, as shown in FIG. 2(h), the conductor layer 19 is formed using the seed layer 15. Specifically, the conductor layer 19 integrated with the seed layer 15 can be formed by performing an electrolytic plating process using the seed layer 15. Then, as shown in FIG. 2(i), the resist layer 18 is peeled off. Then, as shown in FIG. 2(j), the portion of the seed layer 15 in the conductor layer 19 is removed by etching to form the conductor wiring pattern 20. Finally, as shown in FIG. 2(k), the conductor wiring pattern 20 may be covered with another insulating layer 31.

[0045] The manufacturing method may also form conductor wiring patterns and the like on the surface of the support plate opposite to the side where the conductor wiring patterns and the like are formed, by the same method as above. That is, the manufacturing method may form conductor wiring patterns and the like on one side of the support plate, or may form conductor wiring patterns and the like on both sides. Also, when forming conductor wiring patterns and the like on both sides, they may be formed simultaneously, or may be formed at different timings.

[0046] As described above, the obtained conductor wiring pattern 20 is difficult to peel off from the insulating layer 14. Therefore, even if the conductor wiring pattern 20 is fine, it is difficult to peel off. From this, according to the manufacturing method, it is a method for manufacturing a wiring board that can form a fine and difficult-to-peel conductor wiring pattern. Also, by repeating the manufacturing method, a wiring board in which the conductor wiring pattern 20 is multilayered can be manufactured.

[0047] As described above, examples of the resin layer include a resin composition containing a curable compound and a filler (the resin composition before curing), or a layer containing a semi-cured product of the resin composition. Examples of the resin composition include a resin composition containing a curable compound and a filler. Examples of the resin composition also include a resin composition containing a curable compound and a filler such that the specific gravity of the resin composition is 0.95 or more. The specific gravity of the resin composition is preferably 0.95 or more, more preferably 0.95 to 1.37.

[0048] The curable compound is not particularly limited, and examples thereof include polyphenylene ether compounds, maleimide compounds, and hydrocarbon-based compounds. The resin composition may contain a curing agent. When the resin composition contains the polyphenylene ether compound as the curable compound, the curing agent is preferably contained in the resin composition. That is, the resin composition preferably contains the polyphenylene ether compound and the curing agent. The resin composition preferably contains a maleimide compound and a hydrocarbon-based compound.

[0049] The polyphenylene ether compound is not particularly limited, and examples thereof include polyphenylene ether compounds having a carbon-carbon unsaturated double bond at the terminal. Examples of the polyphenylene ether compound include polyphenylene ether compounds having a carbon-carbon unsaturated double bond at the molecular terminal. More specifically, examples include polyphenylene ether compounds having a substituent having a carbon-carbon unsaturated double bond at the molecular terminal, such as a modified polyphenylene ether compound end-modified with a substituent having a carbon-carbon unsaturated double bond.

[0050] The maleimide compound is not particularly limited as long as it is a maleimide compound having a maleimide group in the molecule. Examples of the maleimide compound include, for example, a maleimide compound having an arylene structure bonded in the meta-position in the molecule, a maleimide compound having an indane structure in the molecule, and a maleimide compound having an arylene structure bonded in the meta-position and an indane structure in the molecule. The maleimide compound may contain any one of these, or may contain two of these.

[0051] The maleimide compound having an arylene structure bonded in the meta-position in the molecule is not particularly limited as long as it has the arylene structure in the molecule. Examples of the arylene structure include an arylene structure in which a structure containing a maleimide group is bonded in the meta-position (an arylene structure in which a structure containing a maleimide group is substituted in the meta-position). The arylene group is not particularly limited as long as it is an arylene group bonded in the meta-position, and examples thereof include m-arylene groups such as an m-phenylene group and an m-naphthylene group. As the maleimide compound having an arylene structure bonded in the meta-position in the molecule, a commercially available product can also be used, and for example, the solid content in MIR-5000-60T manufactured by Nippon Kayaku Co., Ltd. may be used.

[0052] The maleimide compound having an indane structure in the molecule is not particularly limited as long as it is a maleimide compound having an indane structure in the molecule. Examples of the indane structure include a divalent group formed by removing two hydrogens from indane or indane substituted with a substituent. The maleimide compound having an indane structure in the molecule also has a maleimide group in the molecule.

[0053] The method for producing a maleimide compound having the indane structure in the molecule specifically includes, for example, a so-called maleimidation reaction in which an amine compound and maleic anhydride are reacted in an organic solvent such as toluene in the presence of a catalyst such as toluenesulfonic acid. Specifically, after this maleimidation reaction, unreacted maleic anhydride and other impurities are removed by washing with water or the like, and the solvent is removed under reduced pressure to obtain a maleimide compound having the indane structure in the molecule. A dehydrating agent may be used during this reaction. Note that a commercially available product may be used as the maleimide compound having the indane structure in the molecule.

[0054] Examples of the maleimide compound having an arylene structure and an indane structure bonded in an oriented manner at the meta position in the molecule include, for example, a maleimide compound having the arylene structure and the indane structure in the molecule.

[0055] Examples of the maleimide compound include maleimide compounds having an arylene structure bonded in an orientation at the meta-position in the molecule, maleimide compounds having the indane structure in the molecule, and maleimide compounds other than maleimide compounds having both an arylene structure and an indane structure bonded in an orientation at the meta-position in the molecule (other maleimide compounds). The other maleimide compounds have a maleimide group in the molecule and do not have an arylene structure and an indane structure bonded in an orientation at the meta-position in the molecule, and examples thereof include maleimide compounds having one or more maleimide groups in the molecule and modified maleimide compounds. Examples of the other maleimide compounds include phenyl maleimide compounds such as 4,4'-diphenylmethane bismaleimide, polyphenylmethane maleimide, m-phenylene bismaleimide, bisphenol A diphenyl ether bismaleimide, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide, 4-methyl-1,3-phenylene bismaleimide, and biphenyl aralkyl type polymaleimide compounds, and N-alkyl bismaleimide compounds having an aliphatic skeleton. Examples of the modified maleimide compounds include modified maleimide compounds in which a part of the molecule is modified with an amine compound and modified maleimide compounds in which a part of the molecule is modified with a silicone compound. As the other maleimide compounds, commercially available products can also be used. For example, BMI-4000, BMI-5100 manufactured by Daiwa Kasei Kogyo Co., Ltd., and BMI-689, BMI-1500, BMI-3000J manufactured by Designer Molecules Inc. may be used.

[0056] The maleimide compound may be used alone or in combination of two or more.

[0057] The hydrocarbon compound is not particularly limited as long as it is a thermosetting hydrocarbon compound. For example, an aromatic polymer having a structural unit derived from a bifunctional aromatic compound in which two carbon-carbon unsaturated double bonds are bonded to an aromatic ring, such as a divinyl aromatic compound, can be mentioned. The structural unit derived from the bifunctional aromatic compound is a structural unit obtained by polymerizing the bifunctional aromatic compound. As the bifunctional aromatic compound, divinylbenzenes such as m-divinylbenzene and p-divinylbenzene are preferable, and p-divinylbenzene is more preferable. The aromatic polymer may have not only a structural unit derived from the bifunctional aromatic compound but also other structural units. Examples of such other structural units include structural units derived from monofunctional aromatic compounds in which one carbon-carbon unsaturated double bond is bonded to an aromatic ring, such as monovinyl aromatic compounds. Examples of the monovinyl aromatic compound include ethylvinyl aromatic compounds. The structural unit derived from the monofunctional aromatic compound is a structural unit obtained by polymerizing the monofunctional aromatic compound. When the aromatic polymer has not only a structural unit derived from the bifunctional aromatic compound but also other structural units, it is a copolymer of the structural unit derived from the bifunctional aromatic compound and other structural units such as the structural unit derived from the monofunctional aromatic compound. This copolymer may be a block copolymer or a random copolymer. As an example of the hydrocarbon compound, as described above, the aromatic polymer can be mentioned, and among them, for example, a polyfunctional vinyl aromatic copolymer can be mentioned. The polyfunctional vinyl aromatic copolymer includes, for example, a copolymer having a repeating unit (a) derived from a divinyl aromatic compound and a repeating unit (b) derived from a monovinyl aromatic compound. The contents of the repeating unit (a) and the repeating unit (b) in the polyfunctional vinyl aromatic copolymer are not particularly limited. However, when the total of the repeating unit (a) and the repeating unit (b) is 100 mol%, for example, it is preferable to contain the repeating unit (a) in an amount of 2 mol% or more and less than 95 mol% and the repeating unit (b) in an amount of 5 mol% or more and less than 98 mol%.Further, the molecular weight of the polyfunctional vinyl aromatic copolymer is not particularly limited, but for example, it is preferably 300 to 10,000 in terms of number average molecular weight (Mn). Examples of the polyfunctional vinyl aromatic copolymer include those described in JP-A-2018-168347.

[0058] As described above, the resin composition may contain a curing agent that reacts with the curable compound as necessary. Here, the curing agent refers to a compound that reacts with the curable compound and contributes to the curing of the resin composition. Examples of the curing agent include epoxy compounds, methacrylate compounds, acrylate compounds, vinyl compounds, cyanate ester compounds, active ester compounds, and allyl compounds. The epoxy compound is not particularly limited, and examples thereof include epoxidized butadiene.

[0059] The resin composition may further contain an elastomer. The elastomer is not particularly limited, and examples thereof include elastomers contained in resin compositions used for forming insulating layers provided in metal-clad laminates, wiring boards, and the like. The resin composition used for forming the insulating layer provided in a metal-clad laminate, a wiring board, etc. may be a resin composition used for forming a resin layer provided in a resin film with metal foil, etc., or may be a resin composition contained in a prepreg. Examples of the elastomer include styrene-based polymers.

[0060] The styrenic polymer is, for example, a polymer obtained by polymerizing monomers including styrenic monomers, and may be a styrenic copolymer. Examples of the styrenic copolymer include copolymers obtained by copolymerizing one or more of the styrenic monomers and one or more other monomers copolymerizable with the styrenic monomers. The styrenic copolymer may be a random copolymer or a block copolymer as long as it has a structure derived from the styrenic monomer in the molecule. Examples of the block copolymer include a binary copolymer of a structure (repeating unit) derived from the styrenic monomer and a structure (repeating unit) of the other copolymerizable monomer, a ternary copolymer of a structure (repeating unit) derived from the styrenic monomer, a structure (repeating unit) of the other copolymerizable monomer, and a structure (repeating unit) derived from the styrenic monomer, and a ternary copolymer of a structure (repeating unit) derived from the styrenic monomer, a random copolymer block (repeating unit) containing the other copolymerizable monomer and the styrenic monomer, and a structure (repeating unit) derived from the styrenic monomer. The styrenic polymer may be a hydrogenated styrenic copolymer obtained by hydrogenating the styrenic copolymer. The styrenic polymer may be one obtained by modifying a part of the copolymer with maleic anhydride.

[0061] The styrenic monomer is not particularly limited. For example, styrene, styrene derivatives, those in which some of the hydrogen atoms of the benzene ring in styrene are substituted with alkyl groups, those in which some of the hydrogen atoms of the vinyl group in styrene are substituted with alkyl groups, vinyltoluene, α-methylstyrene, butylstyrene, dimethylstyrene, and isopropenyltoluene, etc. may be mentioned. These styrenic monomers may be used alone or in combination of two or more. Also, the other copolymerizable monomers are not particularly limited. For example, olefins such as α-pinene, β-pinene, and dipentene, non-conjugated dienes such as 1,4-hexadiene and 3-methyl-1,4-hexadiene, conjugated dienes such as 1,3-butadiene and 2-methyl-1,3-butadiene (isoprene), etc. may be mentioned. These other copolymerizable monomers may be used alone or in combination of two or more.

[0062] Preferable examples of the styrenic copolymer include polymers or copolymers obtained by polymerizing or copolymerizing one or more styrenic monomers such as styrene, vinyltoluene, α-methylstyrene, isopropenyltoluene, divinylbenzene, and allylstyrene. More specifically, the styrenic copolymer includes methylstyrene(ethylene / butylene)methylstyrene copolymer, methylstyrene(ethylene-ethylene / propylene)methylstyrene copolymer, styrene isoprene copolymer, styrene isoprene styrene copolymer, styrene(ethylene / butylene)styrene copolymer, styrene(ethylene-ethylene / propylene)styrene copolymer, styrene butadiene styrene copolymer, butadiene styrene butadiene copolymers such as butadiene styrene butadiene oligomer, styrene(butadiene / butylene)styrene copolymer, methylstyrene(styrene / butadiene random copolymer block)methylstyrene copolymer, styrene(styrene / butadiene random copolymer block)styrene copolymer, and styrene isobutylene styrene copolymer. Examples of the hydrogenated styrenic copolymer include, for example, hydrogenated products of the above styrenic copolymers. More specifically, the hydrogenated styrenic copolymer includes hydrogenated methylstyrene(ethylene / butylene)methylstyrene copolymer, hydrogenated methylstyrene(ethylene-ethylene / propylene)methylstyrene copolymer, hydrogenated styrene isoprene copolymer, hydrogenated styrene isoprene styrene copolymer, hydrogenated styrene(ethylene / butylene)styrene copolymer, hydrogenated styrene(ethylene-ethylene / propylene)styrene copolymer, hydrogenated methylstyrene(styrene / butadiene random copolymer block)methylstyrene copolymer, and hydrogenated styrene(styrene / butadiene random copolymer block)styrene copolymer.

[0063] As the styrene polymer, commercially available products can also be used. For example, V9827, V9461, 2002, 7125F manufactured by Kuraray Co., Ltd., FTR2140, FTR6125 manufactured by Mitsui Chemicals, Inc., Tough Tech H1041, Tough Tech P1500, Tough Tech H1221, Tough Tech M1913 manufactured by Asahi Kasei Corporation, liquid 1,2-SBS manufactured by Nippon Soda Co., Ltd., and Ricon181, Ricon184, etc. manufactured by Cray valley may be used.

[0064] The elastomer (the styrene polymer) preferably has a weight average molecular weight of 1,000 to 300,000, more preferably 1,200 to 200,000. If the molecular weight is too low, the glass transition temperature of the cured product of the resin composition tends to decrease, and the heat resistance tends to decrease. Also, if the molecular weight is too high, the viscosity of the resin composition when made into a varnish state and the viscosity of the resin composition during heat molding tend to become too high. The weight average molecular weight may be measured by a general molecular weight measurement method. Specifically, values measured using gel permeation chromatography (GPC) etc. may be mentioned.

[0065] These elastomers may be used alone or in combination of two or more.

[0066] The filling material is not particularly limited. For example, it may be organic particles or inorganic particles. The organic particles are not particularly limited. For example, they include acrylic particles, acrylonitrile particles, silicone particles, polycarbonate particles, polyolefin particles, polyester particles, polystyrene particles, melamine resin particles, and polyamide particles. Among these organic particles, acrylic particles are preferred. The inorganic particles are not particularly limited. For example, they include silica particles, titanium oxide particles, aluminum oxide particles, tin oxide particles, indium oxide particles, zinc oxide particles, zirconium oxide particles, magnesium oxide particles, calcium carbonate particles, calcium carbonate particles, aluminum hydroxide particles, barium sulfate particles, and glass beads. Further, the filling material may be hollow particles. Specifically, for example, organic hollow particles such as hollow polystyrene particles and inorganic hollow particles are included. Among these filling materials, polystyrene particles, hollow polystyrene particles, inorganic particles, and inorganic hollow particles are preferred, and polystyrene particles, hollow polystyrene particles, silica particles, and hollow silica particles are more preferred. Further, these filling materials may be used alone or in combination of two or more kinds.

[0067] The content of the filling material is preferably 25% by mass or more, more preferably 25 to 60% by mass, and even more preferably 25 to 50% by mass with respect to the resin composition. Further, the content of the curable compound is preferably 10 to 60% by mass, more preferably 10 to 50% by mass with respect to the resin composition. When the elastomer is contained in the resin composition, the content of the elastomer is preferably 10 to 40% by mass, more preferably 10 to 30% by mass with respect to the resin composition.

[0068] The resin composition may contain, as necessary, components other than the filler, the elastomer, and the curable compound (other components) as long as the effects of the present invention are not impaired. Examples of the other components contained in the resin composition may further include additives such as a reaction initiator, a reaction accelerator, a catalyst, a polymerization retarder, a polymerization inhibitor, a dispersant, a leveling agent, a silane coupling agent, an antifoaming agent, an antioxidant, a heat stabilizer, an antistatic agent, an ultraviolet absorber, a dye or a pigment, and a lubricant.

[0069] As described above, the resin composition may contain a reaction initiator. The reaction initiator is not particularly limited as long as it can promote the curing reaction of the resin composition, and examples thereof include peroxides and organic azo compounds. Examples of the peroxide include α,α'-bis(t-butylperoxy-m-isopropyl)benzene, 2,5-dimethyl-2,5-di(t-butylperoxy)-3-hexyne, and benzoyl peroxide. Examples of the organic azo compound include azobisisobutyronitrile. Further, if necessary, a metal carboxylate or the like can be used in combination. By doing so, the curing reaction can be further promoted. Among these, α,α'-bis(t-butylperoxy-m-isopropyl)benzene is preferably used. Since α,α'-bis(t-butylperoxy-m-isopropyl)benzene has a relatively high reaction start temperature, it can suppress the promotion of the curing reaction at the time when curing is not necessary, such as during prepreg drying, and can suppress the deterioration of the storage stability of the resin composition. Further, since α,α'-bis(t-butylperoxy-m-isopropyl)benzene has low volatility, it does not volatilize during prepreg drying or storage, and has good stability. The reaction initiator may be used alone or in combination of two or more.

[0070] As described above, the resin composition may contain a silane coupling agent. The silane coupling agent may be contained in the resin composition, or may be contained as a silane coupling agent that has been surface-treated in advance on the filler contained in the resin composition. Among these, as the silane coupling agent, it is preferable to contain it as a silane coupling agent that has been surface-treated in advance on the filler. Containing it in this way as a silane coupling agent that has been surface-treated in advance on the filler, and further, it is more preferable to also contain a silane coupling agent in the resin composition. Also, in the case of a prepreg, the prepreg may contain a silane coupling agent that has been surface-treated in advance on the fibrous base material. Examples of the silane coupling agent include the same ones as the silane coupling agent used when surface-treating the above-described filler.

[0071] As described above, the resin composition may contain a flame retardant. By containing a flame retardant, the flame retardancy of the cured product of the resin composition can be enhanced. The flame retardant is not particularly limited. Specifically, in fields where halogen-based flame retardants such as bromine-based flame retardants are used, for example, ethylenedipentabromobenzene, ethylenebistetrabromoimide, decabromodiphenyl oxide, and tetradecabromodiphenoxybenzene having a melting point of 300 °C or higher are preferable. By using a halogen-based flame retardant, it is considered that the elimination of halogen at high temperatures can be suppressed, and a decrease in heat resistance can be suppressed. In addition, in fields where halogen-free is required, a flame retardant containing phosphorus (phosphorus-based flame retardant) may be used. The phosphorus-based flame retardant is not particularly limited, and examples thereof include phosphate ester-based flame retardants, phosphazene-based flame retardants, phosphine oxide-based flame retardants, and phosphinate-based flame retardants. Specific examples of the phosphate ester-based flame retardant include condensed phosphate esters of dixylenyl phosphate. Specific examples of the phosphazene-based flame retardant include phenoxyphosphazene. Examples of the phosphine oxide-based flame retardant include bisdiphenylphosphine oxide-based flame retardants, and specific examples thereof include xylylenebisdiphenylphosphine oxide. Specific examples of the phosphinate-based flame retardant include, for example, metal phosphinates such as aluminum dialkylphosphinate. As the flame retardant, each of the exemplified flame retardants may be used alone, or two or more thereof may be used in combination.

[0072] The manufacturing method includes the above-described steps (A) to (D), the arithmetic mean roughness Ra of the roughened surface of the insulating layer is 30 to 500 nm, and the dielectric tangent of the insulating layer is 0.004 or less at 10 GHz. With such a manufacturing method, there is no particular limitation. For example, using the resin composition, a wiring board can be manufactured in which a fine and difficult-to-peel conductor wiring pattern is formed on an insulating layer having low dielectric properties such as a dielectric tangent.

[0073] As described above, this specification discloses various aspects of technology, and the main technologies are summarized below.

[0074] The method for manufacturing a wiring board according to the first aspect of the present invention includes a step (A) of forming a resin layer so as to be in contact with at least one surface of a support plate, a step (B) of curing the resin layer to form an insulating layer, a step (C) of roughening the surface of the insulating layer on the side not in contact with the support plate by plasma treatment, and a step (D) of forming a seed layer on the roughened surface of the insulating layer by sputtering treatment. The arithmetic mean roughness Ra of the roughened surface of the insulating layer is 30 to 500 nm, and the dielectric tangent of the insulating layer is 0.004 or less at 10 GHz. This is a method for manufacturing a wiring board.

[0075] The method for manufacturing a wiring board according to the second aspect of the present invention further includes a step (E) of forming a conductor wiring pattern on the seed layer in the method for manufacturing a wiring board according to the first aspect of the present invention.

[0076] The method for manufacturing a wiring board according to the third aspect of the present invention is the method for manufacturing a wiring board according to the first or second aspect of the present invention, wherein the seed layer contains at least one selected from the group consisting of Ti, Cr, Ni, and W.

[0077] The method for manufacturing a wiring board according to the fourth aspect of the present invention is the method for manufacturing a wiring board according to any one of the first to third aspects of the present invention, wherein the conductor wiring pattern includes wiring having a width of 25 μm or less.

[0078] The method for manufacturing a wiring board according to the fifth aspect of the present invention is the method for manufacturing a wiring board according to any one of the first to fourth aspects of the present invention, wherein the resin layer contains a resin composition containing a curable compound and a filler, or a semi-cured product of the resin composition, and the specific gravity of the resin composition is 0.95 or more.

[0079] The method for manufacturing a wiring board according to the sixth aspect of the present invention is the method for manufacturing a wiring board according to any one of the first to fifth aspects of the present invention, wherein the content of the filler is 25% by mass or more based on the resin composition.

[0080] The present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited thereto.

Example

[0081] [Example] In the method for manufacturing a wiring board shown in FIG. 1, a resin composition having the following composition was used.

[0082] (Elastomer) Hydrogenated styrene (ethylene / butylene) styrene copolymer (Tuftec H1221 manufactured by Asahi Kasei Corporation) 40 parts by mass (Curable compound) Modified polyphenylene ether compound (modified polyphenylene ether obtained by modifying the terminal hydroxyl group of polyphenylene ether with a methacryl group, SA9000 manufactured by SABIC Innovative Plastics, number average molecular weight Mn 2300) 40 parts by mass (Curing agent) Triallyl isocyanurate (TAIC manufactured by Mitsubishi Chemical Corporation) 10 parts by mass (Reaction initiator) α,α'-Bis(t-butylperoxy-m-isopropyl)benzene (Perbutyl P (PBP) manufactured by NOF Corporation) 1 part by mass 2-Ethyl-4-methylimidazole (2E4MZ manufactured by Shikoku Kasei Kogyo Co., Ltd.) 0.1 part by mass (Other components) Epoxidized polybutadiene (JP-100 manufactured by Nippon Soda Co., Ltd.) 10 parts by mass Phosphine oxide-based flame retardant (paraxylylene bisdiphenylphosphine oxide, PQ60 manufactured by Jin Yi Chemical Co., Ltd.) 42 parts by mass (Filler) Silica particles (SC2300-SVJ manufactured by Admatechs Co., Ltd.) 85 parts by mass First, a resin composition was prepared to have the above composition. The specific gravity of this resin composition was 1.37. Using this resin composition, an evaluation substrate having a conductor layer formed on an insulating layer made of a cured product of the resin composition was manufactured by the method shown in FIG. 1. Specifically, as the resin layer 12, a layer made of the resin composition was used, heated from room temperature to 130° C., held at that temperature for 30 minutes, then heated to 220° C., and held at that temperature for 2 hours to cure the resin layer 12 to obtain the insulating layer 14. That is, the insulating layer 14 was a layer made of a cured product of the resin composition. Further, as the plasma treatment, oxygen gas plasma treatment was performed so that the arithmetic mean roughness Ra on the roughened surface became Ra shown in Table 1 below. As the sputtering treatment, as the seed adhesion layer, a Ti layer of 50 to 100 nm was formed, and as the main body of the seed layer, a Cu layer of 150 to 250 nm was formed. Thereafter, as the conductor layer, a Cu layer of 15 to 35 μm was formed by electrolytic plating treatment.

[0083] [Comparative Example 1] The conductor layer was formed by electroless plating treatment (that is, the conductor layer was formed without performing the sputtering treatment), instead of forming the seed layer by the sputtering treatment and using the seed layer to form the conductor layer, and the same procedure as in the example was performed.

[0084] [Comparative Example 2] The same procedure as in Comparative Example 1 was performed except that the plasma treatment was not performed.

[0085] [Comparative Example 3] The same procedure as in the example was performed except that the plasma treatment was not performed.

[0086] [Dielectric Properties (Relative Dielectric Constant Dk and Dissipation Factor Df)] The relative dielectric constant and dissipation factor of the insulating layer (cured product of the resin composition) at 10 GHz were measured by the cavity resonator perturbation method. Specifically, using a network analyzer (N5230A manufactured by Keysight Technologies Co., Ltd.), the relative dielectric constant (Dk) and dissipation factor (Df) of the insulating layer at 10 GHz were measured.

[0087] [Coefficient of thermal expansion] Using the cured product of the resin composition as the insulating layer as a test piece, the coefficient of thermal expansion in the Y-axis direction (CTE: ppm / ℃) was measured by the TMA method (Thermo-mechanical analysis) in accordance with JIS C 6481. For the measurement, a TMA apparatus (TMA6000 manufactured by SII NanoTechnology Inc.) was used and the measurement was carried out in the range of 50 to 100°C.

[0088] [Surface roughness Ra before plasma treatment] The surface roughness Ra of the insulating layer (cured product of the resin composition) before plasma treatment was measured using surface roughness analysis by a scanning confocal laser microscope (LEXT OLS3000 manufactured by Olympus Corporation).

[0089] [Surface roughness Ra after plasma treatment] The surface roughness Ra of the insulating layer (cured product of the resin composition) after plasma treatment was measured using surface roughness analysis by a scanning confocal laser microscope (LEXT OLS3000 manufactured by Olympus Corporation).

[0090] [Peel strength] The Cu layer was peeled off from the evaluation substrate, and the peel strength at that time was measured in accordance with JIS C 6481 (1996). Specifically, a pattern with a width of 10 mm and a length of 80 mm was formed from the Cu layer on the evaluation substrate, and the Cu layer on which this pattern was formed was peeled off by a tensile testing machine at a speed of 50 mm / min, and the peel strength (N / mm) at that time was measured.

[0091] These results are shown in Table 1. In Comparative Example 2 and Comparative Example 3 where no plasma treatment was performed, "Surface roughness Ra after plasma treatment" is indicated as "-". Also, for the evaluation substrate obtained in Comparative Example 2, the peel strength could not be measured by the above method because the Cu layer was peeled off from the insulating layer or other reasons. Therefore, in Table 1, it is indicated as "-".

[0092]

Table 1

[0093] From the above, an insulating layer with a dielectric tangent of 0.004 or less at 10 GHz is subjected to plasma treatment so that the arithmetic mean roughness Ra of the roughened surface is 30 to 500 nm. A seed layer is formed on the roughened surface of the insulating layer by sputtering treatment, and when a wiring board is manufactured using this seed layer (Example), it was found that the peel strength of the formed Cu layer was high compared to the case where it was not (Comparative Examples 1 to 3). From this, it was found that even when forming a fine conductor wiring pattern by dry processing, a conductor wiring pattern that is difficult to peel off can be formed on an insulating layer with low dielectric properties such as dielectric tangent.

Explanation of Reference Numerals

[0094] 11 Support plate 12 Resin layer 13 Release film 14, 31 Insulating layer 15 Seed layer 16, 19 Conductor layer 18 Resist layer 20 Conductor wiring pattern 22 Recess

Claims

1. Step (A) of forming a resin layer so as to contact at least one surface of the support plate; Step (B) of curing the resin layer to form an insulating layer; Step (C) of roughening the surface of the insulating layer on the side not in contact with the support plate by plasma treatment; Step (D) of forming a seed layer on the roughened surface of the insulating layer by sputtering treatment, and The arithmetic mean roughness Ra of the roughened surface of the insulating layer is 30 to 500 nm, and A method for manufacturing a wiring board, wherein the dielectric tangent of the insulating layer is 0.004 or less at 10 GHz.

2. The method for manufacturing a wiring board according to claim 1, further comprising step (E) of forming a conductor wiring pattern on the seed layer.

3. The method for manufacturing a wiring board according to claim 1, wherein the seed layer contains at least one selected from the group consisting of Ti, Cr, Ni, and W.

4. The method for manufacturing a wiring board according to claim 2, wherein the conductor wiring pattern includes a wiring having a width of 25 μm or less.

5. The method for manufacturing a wiring board according to claim 1, wherein the resin layer contains a resin composition containing a curable compound and a filler, or a semi-cured product of the resin composition, and the specific gravity of the resin composition is 0.95 or more.

6. The method for manufacturing a wiring board according to claim 5, wherein the content of the filler is 25% by mass or more based on the resin composition.

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