TW201635867A - Circuit board and manufacturing method thereof - Google Patents

Abstract

The present invention provides techniques capable of forming small-aperture through-holes of good through-hole shape in an insulation layer including inorganic filling material when manufacturing a circuit board. Disclosed is a circuit board which is a circuit board including an insulation layer formed with through-holes of an opening aperture below 15 [mu]m. The arithmetic average roughness (Ra) of the surface of the insulation layer is below 150nm. The insulation layer includes inorganic filling material. In a cross-section of the insulation layer in the direction perpendicular to the surface of the insulation layer, when the maximum aperture average of the inorganic filling material included in a region of a specific width is set to be n1 ([mu]m), the value (n2) of n1×1.27 is below 0.2[mu]m.

Description

Circuit substrate and manufacturing method thereof

The present invention relates to a circuit board and a method of manufacturing the same.

In order to miniaturize and increase the performance of electronic devices, circuit boards that are widely used in various electronic devices require finer and higher density of circuit wiring. As a manufacturing technique of a circuit board, a manufacturing method which is advantageous for a build-up method in which an insulating layer and a conductor layer are alternately overlapped on an inner substrate is known. In the manufacturing method using the build-up method, the insulating layer is formed by laminating a resin composition on an inner layer substrate by using, for example, an adhesive film including a support and a resin composition layer provided on the support. The layer is formed by thermal hardening. Next, a via hole is formed by laser drilling on the formed insulating layer, and the desmear removal and the roughening of the surface of the insulating layer are simultaneously performed by performing desmear treatment. (for example, Patent Document 1).

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2008-37957

When it is desired to achieve higher density of circuit wiring, it is desirable to reduce the diameter of the through hole. Through-holes are generally formed by processing using laser apertures. As a laser, carbon dioxide gas lasers having a high perforation speed and advantageous in terms of manufacturing cost are mainly used. However, there is a limit to the reduction in the diameter of the through hole. For example, it is difficult to form a through hole having an opening diameter of 25 μm or less by using a carbon dioxide gas laser.

A laser that can be used in the formation of a through hole is a UV solid laser such as a UV-YAG laser, in addition to a carbon dioxide gas laser. UV solid-state lasers are not often used in the formation of through-holes, but generally, since a strong ultraviolet region laser is obtained, unlike infrared lasers such as carbon dioxide gas lasers, heat is not generated. Therefore, it is possible to perform finer processing, and it is expected to contribute to the reduction in the diameter of the through hole.

On the other hand, progress has been made to correspond to the low dielectric constant of the insulating layer for high-speed signal transmission, and it is preferred that the insulating layer contain an inorganic filler.

The present inventors attempted to form a small-diameter through hole in an insulating layer containing an inorganic filler by using a UV solid laser such as a UV-YAG laser. As a result, it was found that the laser workability was lowered, and the shape of the through hole (sometimes referred to as "through hole shape") was deteriorated. In particular, it is a big problem in order to achieve an insulating layer having a low dielectric constant and to increase the content of the inorganic filler in the insulating layer. Further, it has been found that the value of the arithmetic mean roughness (Ra) of the insulating layer forming the via hole by the UV solid laser is also high. Through hole shape The deterioration causes the conduction of the communication to be lowered, and the increase in the amount of the glue inside the through hole causes an obstacle to the miniaturization of the circuit wiring which is required to perform the desmear treatment under strict conditions.

An object of the present invention is to provide a technique for forming a small-diameter through hole having a good through-hole shape on an insulating layer containing an inorganic filler when manufacturing a circuit board.

As a result of a positive review of the above-mentioned problems, the present inventors have found that the above problems can be solved by manufacturing a circuit board using a specific inorganic filler, and thus the present invention has been completed.

That is, the present invention includes the following.

[1] A circuit board comprising a circuit board having an insulating layer having a via hole having an opening diameter of 15 μm or less, wherein an arithmetic mean roughness (Ra) of a surface of the insulating layer is 150 nm or less, and the insulating layer contains an inorganic filler. In the cross section of the insulating layer perpendicular to the surface of the insulating layer, when the maximum diameter of the inorganic filler contained in the region of the specific width is n ¹ (μm), the value of n ¹ × 1.27 (n ² ) It is 0.2 μm or less.

[2] The circuit board according to [1], wherein Ra of the surface of the insulating layer is 100 nm or less.

[3] The circuit board according to [1] or [2] wherein the opening diameter of the through hole is 12 μm or less.

[4] of [1] to [3] of the circuit board according to any one of claims, wherein the insulating layer is cross-sectional view in the perpendicular to the surface of the insulating layer, the resin area A ₁ of the area of a certain width and area of the inorganic filler A ₂ satisfies 0.1 ≦ A ₂ /(A ₁ + A ₂ ).

[5] The circuit board according to any one of [1] to [4] wherein the opening diameter D of the through hole and the minimum diameter _{Dmin of the} through hole satisfy 0.65 ≦ D _mim /D.

[6] The circuit board according to any one of [1] to [5] wherein the insulating layer contains an inorganic filler which is surface-treated with a decane compound containing an organic group having an aromatic ring.

[7] The circuit board according to any one of [1] to [6] wherein the inorganic filler is cerium oxide.

[8] A semiconductor device comprising the circuit substrate according to any one of [1] to [7].

[9] A method of manufacturing a circuit board, comprising the steps of: (A) bonding a support film and a resin composition layer provided on the support, and bonding the resin composition layer to the inner substrate; a step of laminating on the inner substrate; (B) a step of thermally hardening the resin composition layer in a state in which the support is attached to form an insulating layer; and (C) forming a UV solid on the insulating layer a step of opening a via having an opening diameter of 15 μm or less; and the insulating layer formed in the step (B) comprises an inorganic filler, and the inorganic layer contained in the region of the specific width in a cross section perpendicular to the surface of the insulating layer When the average value of the maximum diameter of the filler is n ¹ (μm), the value (n ² ) of n ¹ × 1.27 is 0.2 μm or less.

[10] A method of manufacturing a circuit board, comprising the steps of: (A) bonding a support film and a resin composition layer provided on the support body to a resin composition layer and an inner layer substrate; a step of laminating on the inner substrate; (B) a step of thermally hardening the resin composition layer in a state in which the support is attached to form an insulating layer; and (C) forming a UV solid on the insulating layer The step of opening a hole having a diameter of 15 μm or less; and the resin composition layer of the film to be used in the step (A) contains 30% by mass or more of an inorganic filler having a BET specific surface area of 20 m ² /g or more.

[11] A method of manufacturing a circuit board, comprising the steps of: (A) bonding a support film and a resin composition layer provided on the support, and bonding the resin composition layer to the inner substrate; a step of laminating on the inner substrate; (B) a step of thermally hardening the resin composition layer in a state in which the support is attached to form an insulating layer; and (C) forming a UV solid on the insulating layer The step of opening a hole having a diameter of 15 μm or less; and the resin composition layer of the film to be used in the step (A) contains 30% by mass or more of an inorganic filler having an average particle diameter of 0.2 μm or less.

[12] The method according to [10], wherein the inorganic filler has a BET specific surface area of from 20 m ² /g to 500 m ² /g.

[13] The method according to [11], wherein the average particle diameter of the inorganic filler It is 0.01 μm or more and 0.2 μm or less.

[14] The method according to any one of [9] to [13] wherein the support is removed before the step (C).

[15] The method according to any one of [9] to [14] wherein the surface of the insulating layer has an arithmetic mean roughness (Ra) of 150 nm or less.

[16] [9] to [15] the method of any one of claims, wherein the insulating layer is cross-sectional view in the perpendicular to the surface of the insulating layer in the area of the resin A specific area with _a width of the inorganic filler area A ₂ satisfies 0.1≦A ₂ /(A ₁ +A ₂ ).

[17] The method according to any one of [9] to [16] wherein the opening diameter D of the through hole and the minimum diameter _{Dmin of the} through hole satisfy 0.65 ≦ D _mim /D.

[18] The method according to any one of [9] to [17] wherein the insulating layer comprises an inorganic filler which is surface-treated with a decane compound containing an organic group having an aromatic ring.

[19] The method according to any one of [9] to [18] wherein the inorganic filler is cerium oxide.

According to the present invention, in manufacturing a circuit board, a small-diameter through hole having a good through hole shape can be formed on an insulating layer containing an inorganic filler.

1‧‧‧ Inner substrate

10‧‧‧Insulation

11‧‧‧Resin composition

12‧‧‧Inorganic filler

Fig. 1 is a schematic view for explaining a method of calculating an average value of maximum diameters of inorganic fillers in a specific width region in a cross section of an insulating layer.

Fig. 2 is a schematic view for explaining the shape of a through hole.

First, the concept of the present invention will be described.

In the present invention, the following conditions (i) and (ii) are satisfied and a via having a small diameter (for example, an opening diameter of 15 μm or less) is formed on the insulating layer by a UV solid laser: (i) Arithmetic of the surface of the insulating layer The average roughness (Ra) is 150 nm or less, and (ii) the cross-sectional average of the inorganic filler contained in the region of the specific width in the cross section perpendicular to the surface of the insulating layer is set to n ¹ (μm) In the case of n ¹ × 1.27, the value (n ² ) is 0.2 μm or less. The inventors of the present invention can form a small-diameter pass having a good through-hole shape on an insulating layer containing an inorganic filler by satisfying the above specific conditions (i) and (ii) and performing hole drilling by a UV solid laser. The hole is thus completed.

- Condition (i)-

Condition (i) is the arithmetic mean roughness (Ra) of the surface of the insulating layer. The present inventors have found that when a small-diameter through hole is formed by a UV solid laser, the Ra of the surface of the insulating layer greatly affects the shape of the through hole.

Based on the formation of small-diameter through-holes with good through-hole shape The arithmetic mean roughness (Ra) of the surface of the insulating layer is 150 nm or less, preferably 140 nm or less, more preferably 130 nm or less, further preferably 120 nm or less, further preferably 110 nm or less, and particularly preferably 100 nm or less, 90 nm or less, or 80 nm or less. Or below 70nm. The lower limit of Ra is not particularly limited. However, from the viewpoint of ensuring the adhesion strength between the insulating layer and the conductor layer, it is usually 1 nm or more, 5 nm or more, 10 nm or more. The arithmetic mean roughness (Ra) of the surface of the insulating layer can be measured using a non-contact type surface roughness meter. A specific example of the non-contact type surface roughness meter is "WYKO NT3300" manufactured by VECCO Instruments.

- Condition (ii)-

Condition (ii) relates to the particle size of the inorganic filler in the insulating layer. The present inventors have found that when a small-diameter through hole is formed by a UV solid laser, the particle diameter of the inorganic filler in the insulating layer greatly affects the shape of the through hole.

From the viewpoint of forming a small-diameter through-hole having a good through-hole shape, the maximum diameter average of the inorganic filler is set in the cross section of the insulating layer (sometimes simply referred to as "insulation layer profile") perpendicular to the surface of the insulating layer. When n ¹ (μm), the value (n ² ) of n ¹ × 1.27 is 0.2 μm or less, preferably 0.18 μm or less, more preferably 0.16 μm or less, still more preferably 0.14 μm or less, 0.12 μm or less or 0.1. Below μm. The lower limit of n ² is not particularly limited, and is usually 0.01 μm or more, more preferably 0.02 μm or more, still more preferably 0.03 μm or more, 0.04 μm or more, or 0.05 μm or more. Further, n ^{2 was} confirmed to substantially coincide with the average particle diameter of the actual inorganic filler.

Insulation layer profile can be better used FIB-SEM composite device Observed. As the FIB-SEM composite device, for example, "SMI3050SE" manufactured by SII Nanotechnology Co., Ltd. is exemplified. After the cross section of the insulating layer in the direction perpendicular to the surface of the insulating layer was cut by FIB (bundled ion beam), the cross-sectional SEM image was obtained by observing the cross section by SEM (scanning electron microscope). The observation width and the observation magnification of the SEM are not particularly limited as long as the maximum diameter of the inorganic filler contained in the specific width region in the cross section of the insulating layer can be appropriately calculated, and may be determined according to the device specifications to be used.

When the average value n ^{1 of the} maximum diameter is obtained, the "region of a specific width" means a region in which the thickness of the insulating layer is t (μm) × width w (μm) in the cross-sectional SEM image. The width w is not particularly limited as long as it is an observable range in the SEM image, but is preferably, for example, 15 μm. That is, when the average value n ^{1 of the} maximum diameter is obtained, it is preferable that the thickness of the insulating layer is t (μm) × width 15 (μm) in the cross-sectional SEM image.

The term "maximum diameter" means the largest diameter of the inorganic filler particles observed in the cross-sectional SEM image. In addition, when the maximum diameter of the inorganic filler exceeds 1/2 into the region of the width w (μm), the inorganic filler is judged as "area included in the width w (μm)". Referring to Fig. 1, a method of calculating the average value of the maximum diameter of the inorganic filler will be described in more detail. 1 shows a cross section of an insulating layer 10 including a resin component 10 and an inorganic filler 12 and having a thickness t. In the cross section of the insulating layer shown in Fig. 1, the maximum diameter of the inorganic filler selected as a representative is indicated by a dotted line. Among the inorganic fillers on the left and right sides, only the inorganic filler having a maximum diameter of less than 1/2 in the region of the width w (μm) was determined to be excluded from the region of the width w (μm). Therefore, when the number of the inorganic fillers present in the region of the width w (μm) is determined to be two in the cross section of the insulating layer shown in Fig. 1, the maximum diameter is obtained, and the average value of the maximum diameter is calculated. For the insulating layer sample, a sufficient number (N ₁ ) of the cross-sectional SEM image was obtained, and the average value of the maximum diameter of the inorganic filler contained in the region of the width w (μm) was determined, and the average value of the maximum diameter n ^{1 was taken.} . Here, N _{1 is} preferably 10 or more. In the present invention, the average value n ^{1 of the} maximum diameter can be calculated in the order described in <Evaluation of Particle Size of Inorganic Filler in Insulating Layer> to be described later.

According to the invention satisfying the above conditions (i) and (ii), a small-diameter through hole having a good through hole shape can be formed. The problem of the shape of the through hole or the amount of the internal slag becomes remarkable as the diameter of the through hole is reduced. However, according to the method of the present invention, it is possible to form, for example, 15 μm or less, preferably 14 μm or less, without deteriorating the shape of the through hole. Further, a through hole having an opening diameter (top diameter) of preferably 12 μm or less, more preferably 10 μm or less, 9 μm or less, 8 μm or less, 7 μm or less, 6 μm or less, or 5 μm or less. The lower limit of the opening diameter of the through hole is not particularly limited, but may be usually 1 μm or more, 2 μm or more, 3 μm or more.

As described above, the present inventors have found that if a certain amount or more of the inorganic filler having a large particle diameter is contained in the insulating layer, the laser processability by the UV solid laser is lowered, and the shape of the through hole (also referred to as "pass" The hole shape ") is deteriorated, and the amount of dross inside the through hole is increased. In particular, the problem becomes more pronounced when the content of the inorganic filler becomes high. On the other hand, according to the present invention, even if the content of the inorganic filler in the insulating layer is high, a small-diameter through hole having a good through-hole shape can be formed on the insulating layer.

The content of the inorganic filler in the insulating layer can be evaluated by using the area ratio of the inorganic filler in the cross section of the insulating layer. Specifically, the content of the inorganic filler in the insulating layer can be A ₂ /(A ₁ + when the resin area of the specific width region in the cross section of the insulating layer is A ₁ and the area of the inorganic filler is A ₂ . A ₂ ) Evaluation of the value. The larger the value of A ₂ /(A ₁ +A ₂ ), the higher the content of the inorganic filler in the insulating layer. The value of A ₂ /(A ₁ +A ₂ ) is preferably 0.1 or more (that is, 0.1 ≦A ₂ /(A ₁ +A ₂ )), more preferably 0.2, based on the viewpoint of low dielectric constant of the insulating layer. The above is more preferably 0.25 or more, and even more preferably 0.26 or more. The upper limit of the value of A ₂ /(A ₁ +A ₂ ) is not particularly limited, but is preferably 0.9 or less, more preferably 0.8 or less, from the viewpoint of mechanical strength of the insulating layer and the like. In the present invention, the term "resin area" means the area occupied by the resin component. The "resin component" in the resin area means a component other than the inorganic filler in the component constituting the insulating layer. The value of A ₂ /(A ₁ +A ₂ ) in the cross section of the insulating layer can be determined in the order described in <Measurement of Resin Area and Inorganic Filler Area in the Section of Insulating Layer> to be described later. The specific width region is as described above.

In the present invention, the above conditions (i) and (ii) are satisfied, and a through hole having a small diameter is formed on the insulating layer by a UV solid laser.

As the UV solid laser, various conventional ones can be used, such as, for example, a UV-YAG laser, a UV-YLF laser, a UV-YVO ₄ laser, etc., among which a UV-YAG laser is preferred.

UV-YAG laser is a kind of UV solid-state laser. It can be used as a solid laser for the excitation of a part of the ruthenium in the crystal structure doped with other elements in the yttrium/aluminum/garnet (YAG) crystal. Laser of the medium. Nd:YAG doped with antimony (Nd) is generally used. The laser light whose wavelength is converted by LBO (LiB ₃ O ₅ ) crystals using a basic wavelength of laser light of Nd:YAG (3 times wave: 355 nm, 4 times wave: 266 nm) or the like is used. It is also possible to use a BBO (β-BaB ₂ O ₄ ) crystal or a KTP (KTiOPO ₄ ) crystal as a laser for a device for generating harmonics.

The opening processing conditions (for example, laser wavelength, pulse wave number, pulse width, and output) using the UV solid laser are not particularly limited as long as they can form a small-diameter through hole having a good through hole shape, and can be used depending on the UV used. The specifications of the solid laser processing machine are appropriately determined within the scope of general processing conditions. For the UV solid laser, a commercially available UV solid laser processing machine can be used. Specifically, as a commercially available UV-YAG laser processing machine, for example, "LU-2L212/M50L" manufactured by VIA MECHANICAL Co., Ltd. is used.

According to the method of the present invention which satisfies the above conditions (i) and (ii) and is subjected to the opening processing by UV solid laser, it can be formed in an insulating layer containing an inorganic filler (even if the inorganic filler is high in content) A small diameter through hole having a good through hole shape.

Referring to Fig. 2, the shape of the through hole will be described. In FIG. 2, an inner layer substrate 1 and an insulating layer 10 having a thickness t provided in a manner of being bonded to the inner layer substrate are shown, and the through holes of (a) to (c) are formed on the insulating layer 10. In the present invention, the "opening diameter" (D) of the through hole means the through hole diameter of the surface of the insulating layer (the position of Z = 0 in Fig. 2). And the "minimum diameter" (D _min ) of the through hole refers to the minimum diameter of the through hole in the range of Z from 0 to t. The "maximum diameter" (D _max ) of the through hole means the maximum diameter of the through hole in the range of Z from 0 to t. For example, the through hole of (a) of Fig. 2 has a shape of a forward cone which gradually becomes smaller as the depth from the surface of the insulating layer enters the depth direction of the insulating layer (Z). In the through hole (a), the opening diameter D is the maximum diameter D _max , and the minimum diameter D _{min is} present at the bottom of the through hole (the position of Z=t in FIG. 2). When a through hole is formed using a UV solid laser, a via hole of (a) is generally formed. There is also a case where the through holes of (b) or (c) of Fig. 2 are formed. (b) the via hole enters the depth direction (Z) of the insulating layer from the surface of the insulating layer by a certain distance (k ₁ t; but the k ₁ system satisfies the number of 0 < k ₁ <1), and the diameter gradually becomes smaller, and further The depth of the entering depth is gradually increased. The diameter of the opening diameter D of the through hole (b) or the bottom of the through hole (the position of Z = t) is the maximum diameter D _max , and the minimum diameter D _min is present at the position of the depth k ₁ t. (c) the via hole enters the depth direction (Z) of the insulating layer from the surface of the insulating layer by a certain distance (k ₂ t; but the k ₂ system satisfies the number of 0 < k ₂ <1), and the diameter gradually becomes larger, and further The depth of entry into the depth direction is gradually reduced. The through hole (c) exhibits a maximum diameter D _max at a position of the depth k ₂ t , and a diameter of the opening diameter D or the bottom of the through hole (the position of Z=t) is a minimum diameter D _min .

Regardless of the via type of (a) to (c), the aperture diameter D of the via hole and the minimum diameter D _{min of the} via hole preferably satisfy 0.65 ≦ D _mim /D from the viewpoint of obtaining good conduction communication. This is because if the value of D _mim /D is low, the deterioration of the penetration of the plating solution into the through hole is caused by the deterioration of the communication communication. The value of D _mim /D is preferably 0.66 or more, more preferably 0.68 or more, further preferably 0.70 or more, 0.72 or more, 0.74 or more, 0.75 or more, 0.76 or more, or 0.77 or more, from the viewpoint of obtaining a better communication-conducting property. The upper limit of the value of D _mim /D is 1, and is usually 0.99 or less, 0.98 or less, 0.95 or less, or 0.90 or less. According to the method of the present invention, a higher value of D _mim /D can be advantageous for forming a via having a small diameter. The value of D _mim /D can be obtained by observing the through-hole opening portion by a SEM for a sufficient number (N ₂ ) of via holes. Regarding the through hole of (c), when the diameter of the bottom of the through hole is smaller than the opening diameter D, the minimum diameter _Dmin can also be determined by observing the surface of the SEM (the opening diameter D is not recognized when the diameter of the bottom of the through hole is not recognized) Is the minimum diameter D _min ). N _{2 is} preferably 10 or more.

Further, the case where a large number of through holes (c) are formed is rare, but in this case, the opening diameter D of the through holes and the maximum diameter D _{max of the} through holes preferably satisfy D _max /D ≦ 1.35. The value of D _max /D is preferably 1.30 or less, more preferably 1.20 or less, still more preferably 1.10 or less or 1.05 or less. The lower limit of the value of D _max /D is 1. The value of D _max /D can be determined for a sufficient number (N ₂ ) of vias by SEM observation of the via profile. N _{2 is} preferably 10 or more.

In the present invention, the thickness t (μm) of the insulating layer and the opening diameter D (μm) of the through hole are preferably satisfied by t≦3D from the viewpoint of forming a small through hole having a good through hole shape, and more preferably satisfies t≦2.5. D, which better satisfies t≦2D, and thus better satisfies t≦1.8D, t≦1.6D, t≦1.4D, or t≦1.2D. The lower limit of the thickness t of the insulating layer is not particularly limited, but is usually 1 μm or more, 2 μm or more, 3 μm or more.

In a preferred embodiment, the insulating layer is formed by thermally curing a resin composition layer containing an inorganic filler.

The content of the inorganic filler in the resin composition constituting the resin composition layer is preferably 20% by mass or more, more preferably 25% by mass or more, from the viewpoint of sufficiently lowering the dielectric constant of the insulating layer and achieving high-speed signal transmission.

In the present invention, the content of each component constituting the resin composition is a value obtained by setting the nonvolatile component in the resin composition to 100% by mass.

Forming an insulating layer using a resin composition containing an inorganic filler At this time, the laser processability of the UV solid laser is lowered, and the shape of the via hole is deteriorated. On the other hand, in the present invention which satisfies the above-described specific conditions (i) and (ii) and forms a through hole by UV solid laser, there is no problem of the shape of the through hole, and a resin composition having a high content of the inorganic filler can be used. For example, the content of the inorganic filler in the resin composition is preferably as high as 30% by mass or more, 40% by mass or more, 50% by mass or more, 60% by mass or more, or 70% by mass or more.

The upper limit of the content of the inorganic filler in the resin composition is preferably 90% by mass or less, more preferably 85% by mass or less, from the viewpoint of preventing a decrease in mechanical strength of the insulating layer.

The average particle diameter of the inorganic filler is preferably 0.2 μm or less, more preferably 0.15 μm or less, still more preferably 0.1 μm or less, based on the viewpoint of satisfying the above conditions (i) and (ii). The lower limit of the average particle diameter of the inorganic filler is not particularly limited, and may be usually 0.01 μm or more and 0.02 μm or more. Commercial products of the inorganic filler having such an average particle diameter are, for example, "UFP-30" manufactured by Electric Chemical Industry Co., Ltd., "YC100C" manufactured by ADOMATEX Co., Ltd., "YA050C-MJE", and the like. The average particle diameter of the inorganic filler can be measured by a laser diffraction/scattering method based on the Mie scattering theory. Specifically, the laser diffraction scattering particle size distribution measuring apparatus can be used to measure the particle size distribution of the inorganic filler on a volume basis, and the median diameter is measured as an average particle diameter. The measurement sample can be preferably used in which an inorganic filler is dispersed in water by ultrasonic waves. As the laser diffraction scattering particle size distribution measuring apparatus, "LA-500" manufactured by Horiba, Ltd., etc. can be used.

The BET specific surface area of the inorganic filler is preferably 20 m ² /g or more, more preferably 25 m ² /g or more, and still more preferably 30 m ² /g, based on the viewpoint of satisfying the above conditions (i) and (ii). the above. The upper limit is not particularly limited, but is preferably 500 m ² /g or less, more preferably 400 m ² /g or less, and still more preferably 300 m ² /g or less. The BET specific surface area (m ² /g) of the inorganic filler can be determined as follows. Specifically, a molecule having a known adsorption-occupying area is adsorbed on an inorganic filler sample at a temperature of liquid nitrogen, and the specific surface area of the inorganic filler sample can be determined from the amount of adsorption. As the molecule having a known adsorption occupying area, an inert gas such as nitrogen gas or helium gas is preferably used. The specific surface area S (m ² /g) of the inorganic filler can be measured using an automatic specific surface area measuring device, for example, "Macsorb HM-1210" manufactured by MOUNTECH Co., Ltd.

Examples of the inorganic filler include, for example, cerium oxide, aluminum oxide, glass, cordierite, cerium oxide, barium sulfate, talc, clay, mica powder, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, and nitrogen. Boron, aluminum nitride, manganese nitride, aluminum borate, barium titanate, barium titanate, calcium titanate, magnesium titanate, barium titanate, titanium oxide, barium zirconate, calcium zirconate, zirconium phosphate and tungsten phosphate Zirconium acid and the like. Particularly preferred among these are cerium oxide such as amorphous cerium oxide, molten cerium oxide, crystalline cerium oxide, synthetic cerium oxide, hollow cerium oxide or the like. Further, as the cerium oxide, spherical cerium oxide is preferred. The inorganic filler may be used singly or in combination of two or more.

In order to improve the moisture resistance, the inorganic filler is preferably treated with one or more kinds of surface treatment agents such as a decane compound, an organic sulfonium compound, an aluminum coupling agent, a titanium coupling agent, and a zirconium coupling agent.

In particular, the present inventors have found that the above-mentioned A ₂ /(A ₁ +A ₂ ) value can be achieved by using an inorganic filler which is surface-treated with a decane compound having an organic group having an aromatic ring, and the above conditions are satisfied. (ii) A low insulating layer of n ₂ . Therefore, in a preferred embodiment, the resin composition constituting the resin composition layer, and the insulating layer further contains an inorganic filler which is surface-treated with a decane compound containing an organic group having an aromatic ring.

The organic group having an aromatic ring preferably has a carbon number of 6 to 20 (preferably 6 to 14) based on the viewpoint that an insulating layer having a high value of A ₂ /(A ₁ +A ₂ ) and a low n _{2 is obtained} . More preferably, it is 6 to 12, more preferably 6 to 10) of an aryl group, of which a phenyl group is preferred.

The decane compound containing an organic group having an aromatic ring used for the treatment of the inorganic filler is not particularly limited as long as it can introduce the above-mentioned organic group having an aromatic ring on the surface of the inorganic filler, and further has an epoxy which can be described later. A reactive group (for example, an amine group, an epoxy group, a thiol group, or the like) in which a resin component such as a resin reacts. Specific examples of the decane compound are phenyltrimethoxydecane, diphenyldimethoxydecane, N-phenyl-3-aminopropyltrimethoxydecane, glycidoxypropylphenyldiethyl Oxydecane, mercaptopropyl phenyl dimethoxy decane. The commercially available product of the decane compound is, for example, "KBM103" (phenyltrimethoxydecane) manufactured by Shin-Etsu Chemical Co., Ltd., and "KBM573" (N-phenyl-3-aminopropyl) manufactured by Shin-Etsu Chemical Co., Ltd. Trimethoxy decane) and the like. The decane compound may be used alone or in combination of two or more.

The degree of surface treatment using the surface treatment agent can be evaluated based on the amount of carbon per unit surface area of the inorganic filler. The amount of carbon per unit surface area of the inorganic filler is preferably 0.02 mg/m ² or more, based on the viewpoint that the value of A ₂ /(A ₁ +A ₂ ) is high and the n _{2 is} low. It is 0.1 mg/m ² or more, and more preferably 0.2 mg/m ² or more. On the other hand, from the viewpoint of preventing the melt viscosity of the resin varnish or the melt viscosity of the film form from increasing, it is preferably 1 mg/m ² or less, more preferably 0.8 mg/m ² or less, still more preferably 0.5 mg/m ² or less.

The amount of carbon per unit surface area of the inorganic filler can be measured by washing the surface-treated inorganic filler with a solvent such as methyl ethyl ketone (MEK). Specifically, a sufficient amount of MEK as a solvent was added to an inorganic filler surface-treated with a surface treatment agent, and ultrasonic cleaning was performed at 25 ° C for 5 minutes. After removing the supernatant liquid and drying the solid component, the amount of carbon per unit surface area of the inorganic filler can be measured using a carbon analyzer. As the carbon analyzer, "EMIA-320V" manufactured by Horiba, Ltd. can be used.

In one embodiment, the resin composition constituting the resin composition layer contains a thermosetting resin in addition to the inorganic filler. As the thermosetting resin, a conventional thermosetting resin which is used in forming an insulating layer of a circuit board can be used, and among them, an epoxy resin is preferred. The resin composition constituting the resin composition layer may also contain a curing agent. Therefore, in one embodiment, the resin composition contains an epoxy resin and a curing agent in addition to the inorganic filler.

- epoxy resin -

Examples of the epoxy resin are, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AF type epoxy resin, dicyclopentadiene type epoxy resin, and the like. Phenolic epoxy resin, naphthol novolac Epoxy resin, phenol novolak type epoxy resin, t-butyl catechol type epoxy resin, naphthalene type epoxy resin, naphthol type epoxy resin, fluorene type epoxy resin, glycidylamine type epoxy Resin, glycidyl ester epoxy resin, cresol novolak epoxy resin, biphenyl epoxy resin, linear aliphatic epoxy resin, epoxy resin with butadiene structure, alicyclic epoxy resin , Heterocyclic epoxy resin, epoxy resin with spiral ring, cyclohexane dimethanol type epoxy resin, naphthalene ether type epoxy resin, trimethylol type epoxy resin, tetraphenylethane type epoxy Resin, etc. Epoxy resins may be used alone or in combination of two or more.

The epoxy resin preferably contains an epoxy resin having two or more epoxy groups in one molecule. When the non-volatile component in the epoxy resin is 100% by mass, it is preferably at least 50% by mass or more of an epoxy resin having two or more epoxy groups in one molecule. Among them, the resin composition preferably contains a solid epoxy resin (also referred to as "solid epoxy resin") at a temperature of 20 ° C alone, or a solid epoxy resin in combination and a liquid epoxy at a temperature of 20 ° C. Resin (hereinafter referred to as "liquid epoxy resin"). The solid epoxy resin is preferably a solid epoxy resin having three or more epoxy groups in one molecule, and more preferably an aromatic solid epoxy resin having three or more epoxy groups in one molecule. The liquid epoxy resin is preferably a liquid epoxy resin having two or more epoxy groups in one molecule, and more preferably an aromatic liquid epoxy resin having two or more epoxy groups in one molecule. In the present invention, the aromatic epoxy resin means an epoxy resin having an aromatic ring in its molecule.

The liquid epoxy resin is preferably a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a bisphenol AF type epoxy resin, or a naphthalene type epoxy resin. Resin, glycidyl ester type epoxy resin, glycidylamine type epoxy resin, phenol novolak type epoxy resin, alicyclic epoxy resin having an ester skeleton, cyclohexane dimethanol type epoxy resin, glycidylamine The epoxy resin and the epoxy resin having a butadiene structure are more preferably a bisphenol A epoxy resin, a bisphenol F epoxy resin or a naphthalene epoxy resin. Specific examples of the liquid epoxy resin are "HP4032", "HP4032H", "HP4032D", "HP4032SS" (naphthalene type epoxy resin) manufactured by DIC Co., Ltd., and "jER828EL" manufactured by Mitsubishi Chemical Corporation. "828US" (bisphenol A type epoxy resin), "jER807" (bisphenol F type epoxy resin), "jER152" (phenol novolak type epoxy resin), and Nippon Steel & Sumitomo Chemical Co., Ltd. "ZX1059" (mixture of bisphenol A epoxy resin and bisphenol F epoxy resin), "EX-721" (glycidyl ester epoxy resin) manufactured by NAGASE CHEMTEX Co., Ltd., DAICEL (share) "CELLOXIDE2021P" (an alicyclic epoxy resin having an ester skeleton) and "PB-3600" (an epoxy resin having a butadiene structure). These may be used alone or in combination of two or more.

The solid epoxy resin is preferably a naphthalene type tetrafunctional epoxy resin, a cresol novolac type epoxy resin, a dicyclopentadiene type epoxy resin, a trisphenol type epoxy resin, or a naphthol type epoxy resin. Biphenyl type epoxy resin, naphthalene ether type epoxy resin, bismuth type epoxy resin, bisphenol A type epoxy resin, bisphenol AF type epoxy resin, tetraphenylmethane type epoxy resin, more preferably naphthalene type A 4-functional epoxy resin, a naphthol type epoxy resin, a biphenyl type epoxy resin, a dicyclopentadiene type epoxy resin, and a bisphenol AF type epoxy resin. A specific example of the solid epoxy resin is "HP-made by DIC". 4700", "HP-4710" (naphthalene type 4-functional epoxy resin), "N-690", "N-695" (cresol novolac type epoxy resin), "HP7200", "HP7200H", "HP7200HH (Dicyclopentadiene type epoxy resin), "EXA7311", "EXA7311-G3", "EXA7311-G4", "EXA7311-G4S", "HP6000" (naphthyl ether type epoxy resin), Nippon Kayaku "EPPN-502H" (trisphenol type epoxy resin), "NC7000L" (naphthol novolac type epoxy resin), "NC3000H", "NC3000", "NC3000L", "NC3100" (linked) "Benzene type epoxy resin", "ESN475V" (naphthol type epoxy resin) made by Nippon Steel & Sumitomo Chemical Co., Ltd., "ESN485" (naphthol novolac type epoxy resin), Mitsubishi Chemical Co., Ltd. "YX4000H", "YL6121" (biphenyl type epoxy resin), "YX4000HK" (bisxylenol type epoxy resin), "YX8800" (蒽 type epoxy resin), Osaka Gas Chemical Co., Ltd. PG-100", "CG-500", "YL7800" (茀-type epoxy resin) manufactured by Mitsubishi Chemical Corporation, and "jER1010" (solid bisphenol A epoxy resin) manufactured by Mitsubishi Chemical Corporation , "YL7723", "YL7 760" (bisphenol AF type epoxy resin), "jER1031S" (tetraphenylmethane type epoxy resin), etc. These may be used alone or in combination of two or more.

When a liquid epoxy resin and a solid epoxy resin are used as the epoxy resin, the ratio (liquid epoxy resin: solid epoxy resin) is preferably from 1:0.1 to 1:5 by mass ratio. The scope. When the ratio of the amount of the liquid epoxy resin to the solid epoxy resin is in this range, the following effects can be obtained: i) moderate adhesion when used in the form of a film to be described later, ii) When it is used in the form of a film, sufficient flexibility is obtained, handling property is improved, and iii) an insulating layer or the like having sufficient breaking strength can be obtained. The ratio of the liquid epoxy resin to the solid epoxy resin (liquid epoxy resin: solid epoxy resin), based on the effects of the above i) to iii), is preferably 1: by mass ratio: The range of 0.5 to 1:5 is preferably in the range of 1:1 to 1:4.5, and particularly preferably in the range of 1:1.5 to 1:4.5.

The epoxy resin content in the resin composition is preferably from 3% by mass to 60% by mass, more preferably from 5% by mass to 55% by mass, even more preferably from 5% by mass to 45% by mass.

The epoxy equivalent of the epoxy resin is preferably from 50 to 5,000, more preferably from 50 to 3,000, still more preferably from 80 to 2,000, and even more preferably from 110 to 1,000. By being in this range, it is possible to provide an insulating layer having a sufficient crosslinking density of the cured product and a small surface roughness. Further, the epoxy equivalent can be determined according to JIS K7236, and is a mass of a resin containing one equivalent of an epoxy group.

The weight average molecular weight of the epoxy resin is preferably from 100 to 5,000, more preferably from 250 to 3,000, still more preferably from 400 to 1,500. Here, the weight average molecular weight of the epoxy resin is a polystyrene-equivalent weight average molecular weight measured by a gel permeation chromatography (GPC) method.

-hardener-

The curing agent is not particularly limited as long as it has a function of curing the epoxy resin, and examples thereof include, for example, a phenol-based curing agent, a naphthol-based curing agent, an active ester-based curing agent, a benzoxazine-based curing agent, and a cyanate-based curing agent. And a carbodiimide-based hardener. The curing agent may be used alone or in combination of two or more. use.

The phenolic curing agent and the naphthol-based curing agent are preferably a phenolic curing agent having a novolac structure or a naphthol-based curing agent having a novolak structure, from the viewpoint of heat resistance and water resistance. Further, from the viewpoint of the adhesion strength to the conductor layer, a nitrogen-containing phenol-based curing agent or a nitrogen-containing naphthol-based curing agent is preferable, and a phenol-based curing agent containing a triazine structure or a naphthol containing a triazine structure is more preferable. A hardener. Among them, a phenol novolak resin containing a triazine structure or a naphthol novolak resin containing a triazine structure is preferred from the viewpoint of highly satisfying heat resistance, water resistance, and adhesion strength to a conductor layer. These may be used alone or in combination of two or more.

Specific examples of the phenolic curing agent and the naphthol-based curing agent are, for example, "MEH-7700", "MEH-7810", "MEH-7851", and "Nippon Chemical Co., Ltd." manufactured by Mingwa Kasei Co., Ltd. "SN-170", "SN-180", "SN-190", "SN-475" and "SN-485" made by NHN", "CBN", "GPH", Nippon Steel & Sumitomo Chemical Co., Ltd. "LA-7052", "LA-7054", "LA-3018", "LA-1356", "SN-495", "SN-375", "SN-395", DIC (share) system TD2090", "LA-3018-50P", etc.

The active ester-based curing agent is not particularly limited, and it is generally preferred to use two or more of one molecule of a phenol ester, a thiophene ester, an N-hydroxylamine, or an ester of a heterocyclic hydroxy compound. a compound of an ester group. The active ester-based curing agent is preferably obtained by a condensation reaction of a carboxylic acid compound and/or a thiocarboxylic acid compound with a hydroxy compound and/or a thiol compound. Especially from the viewpoint of improvement in heat resistance, it is preferably a carboxylic acid The active ester-based curing agent obtained from the compound and the hydroxy compound is more preferably an active ester-based curing agent obtained from a carboxylic acid compound and a phenol compound and/or a naphthol compound. The carboxylic acid compound is exemplified by, for example, benzoic acid, acetic acid, succinic acid, maleic acid, isaconic acid, phthalic acid, isophthalic acid, terephthalic acid, pyromellitic acid or the like. Phenolic compounds or naphthol compounds are exemplified by, for example, hydroquinone, resorcinol, bisphenol A, bisphenol F, bisphenol S, phenolphthalein, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2 ,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucinol, benzenetriol, dicyclopentadiene-type diphenol compound, phenol novolac Wait. The "dicyclopentadiene type diphenol compound" herein means a diphenol compound obtained by condensing two molecules of phenol in one molecule of dicyclopentadiene.

Preferred examples of the active ester-based hardener are exemplified by an active ester compound containing a dicyclopentadiene-type diphenol structure, an active ester compound containing a naphthalene structure, an active ester compound of a phenolic novolac-containing acetal compound, and a phenol-containing compound. An active ester compound obtained by reacting an active ester compound of a benzamidine compound of a novolac, an aromatic carboxylic acid with a phosphorus atom-containing oligomer having a phenolic hydroxyl group, and more preferably a dicyclopentadiene type diphenol An active ester compound obtained by reacting an active ester compound having a structure, an active ester compound containing a naphthalene structure, an oligomer of an aromatic carboxylic acid and a phosphorus atom having a phenolic hydroxyl group. Further, in the present invention, the "dicyclopentadiene-type diphenol structure" means a divalent structural unit composed of a phenyl-dicyclopentylene-phenylene group.

As an active ester-based hardener, JP-A-2004- The active ester compound disclosed in Japanese Patent Publication No. 277460, and JP-A-2013-40270, and a commercially available active ester compound can also be used. Commercial products of the active ester compound are exemplified by "EXB9451", "EXB9460", "EXB9460S", "HPC-8000-65T", and "HPC-8000L-65M" (including dicyclopentylene) manufactured by DIC Corporation. "Active ester compound of olefinic diphenol structure", "9416-70BK" (active ester compound containing naphthalene structure) made by DIC Co., Ltd., "DC808" by Mitsubishi Chemical Co., Ltd. (Acetone containing phenol novolac Active ester compound of the compound), "YLH1026" manufactured by Mitsubishi Chemical Co., Ltd. (active ester compound of benzoic acid phenolate containing phenol novolac), and "EXB9050L-62M" (made of DIC) Ester compound).

Specific examples of the benzoxazine-based curing agent are "HFB2006M" manufactured by Showa Polymer Co., Ltd., and "P-d" and "F-a" manufactured by Shikoku Chemical Industries Co., Ltd.

The cyanate-based curing agent is not particularly limited, and examples thereof include a novolak type (phenol novolak type, alkylphenol novolak type, etc.) cyanate-based curing agent and dicyclopentadiene type cyanate-based curing agent. A cyanate-based curing agent, a bisphenol-type (bisphenol A type, a bisphenol F type, a bisphenol S type, etc.), and a part of the triazine-based polymer. As specific examples, bisphenol A diisocyanate, polyphenol cyanate (oligo(3-methylene-1,5-phenylene)), 4,4'-methylene double (2) ,6-dimethylphenyl cyanate), 4,4'-ethylenediphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis(4-cyanate) Phenylpropane, 1,1-bis(4-cyanate phenylmethane), bis(4-cyanate-3,5-dimethylphenyl)methane, 1,3-bis(4-cyanide) Phosphate phenyl-1-(methylethylidene) Base)) 2-functional cyanate resin such as benzene, bis(4-cyanate phenyl) sulfide, and bis(4-cyanate phenyl) ether, derived from phenol novolac and cresol novolac A polyfunctional cyanate resin, a prepolymer of a portion of the cyanate resin which is partially triazineated, or the like. Commercial examples of the cyanate-based curing agent are, for example, "PT30" and "PT60" manufactured by RONZA Co., Ltd. (all of which are phenol novolac type polyfunctional cyanate resins), and "BA230" (bisphenol A). a prepolymer of a partially or fully triazineated trimer of a diisocyanate) or the like.

Specific examples of the carbodiimide-based curing agent are "V-03" and "V-07" manufactured by Nisshinbo Chemical Co., Ltd., and the like.

The ratio of the epoxy resin to the hardener is based on the ratio of the mechanical strength and water resistance of the resulting insulating layer, [the total number of epoxy groups of the epoxy resin]: [the total count of the reactive groups of the hardener], It is preferably in the range of 1:0.2 to 1:2, more preferably in the range of 1:0.3 to 1:1.5, and more preferably in the range of 1:0.4 to 1:1.2. Here, the reactive group of the curing agent is an active hydroxyl group, an active ester group or the like, and varies depending on the type of the curing agent. Further, the total number of epoxy groups of the epoxy resin is a total value obtained by dividing the solid content of each epoxy resin by the value of the epoxy equivalent of all the epoxy resins, and the total of the reactive groups of the hardener is for all The hardener is a value obtained by dividing the solid content of each hardener by the value of the reactive base equivalent.

The resin composition may further contain one or more additives selected from the group consisting of a thermoplastic resin, a hardening accelerator, a flame retardant, and an organic filler, as needed.

- Thermoplastic Resin -

The thermoplastic resin is exemplified by, for example, a phenoxy resin, a polyvinyl acetal resin, a polyolefin resin, a polybutadiene resin, a polyimide resin, a polyamidimide resin, a polyether quinone resin, and a polyfluorene. Resin, polyether oxime resin, polyphenylene ether resin, polycarbonate resin, polyether ether ketone resin, polyester resin. The thermoplastic resin may be used singly or in combination of two or more.

The polystyrene-equivalent weight average molecular weight of the thermoplastic resin is preferably in the range of 8,000 to 70,000, more preferably in the range of 10,000 to 60,000, still more preferably in the range of 20,000 to 60,000. The polystyrene-equivalent weight average molecular weight of the thermoplastic resin is measured by a gel permeation chromatography (GPC) method. Specifically, the weight average molecular weight of the thermoplastic resin in terms of polystyrene is LC-9A/RID-6A manufactured by Shimadzu Corporation, and the Shodex K-800P/K-804L manufactured by Showa Denko Co., Ltd. is used. /K-804L was used as a column, and chloroform or the like was used as a mobile phase, and the column temperature was measured at 40 ° C, and was calculated using a calibration line of standard polystyrene.

The phenoxy resin is exemplified by, for example, a bisphenol A skeleton, a bisphenol F skeleton, a bisphenol S skeleton, a bisphenol acetophenone skeleton, a novolak skeleton, a biphenyl skeleton, an anthracene skeleton, a dicyclopentadiene skeleton, and a phenanthrene skeleton. A phenoxy resin having one or more kinds of skeletons selected from the group consisting of a borneol skeleton, a naphthalene skeleton, an anthracene skeleton, an adamantane skeleton, a ruthenium skeleton, and a trimethylcyclohexane skeleton. The terminal of the phenoxy resin may be any one of a phenolic hydroxyl group, an epoxy group and the like. The phenoxy resin may be used singly or in combination of two or more. Specific examples of the phenoxy resin are "1256" and "4250" (all are phenoxy resins containing a bisphenol A skeleton) and "YX8100" manufactured by Mitsubishi Chemical Corporation. ( phenoxy resin containing a bisphenol S skeleton) and "YX6954" (a phenoxy resin containing a bisphenol acetophenone skeleton), and other examples are "FX280" manufactured by Nippon Steel & Sumitomo Chemical Co., Ltd. And "YX7553BH30", "YX7553", "YL6794", "YL7213", "YL7290" and "YL7482" manufactured by Mitsubishi Chemical Corporation.

Specific examples of the polyvinyl acetal resin are, for example, a polyethylene formal resin and a polyethylene butyral resin, preferably a polyvinyl butyral resin. Examples are electro-chemical butadiene 4000-2, 5000-A, 6000-C, 6000-EP, Sekisui Chemical Industry Co., Ltd. SLEC BH series, BX series, KS series (specifically "KS-1", etc., BL series, BM series, etc.

Specific examples of the polyimine resin are "RIKACOTE SN20" and "RIKACOTE PN20" manufactured by Nippon Chemical and Chemical Co., Ltd. Further, as a specific example of the polyimine resin, a linear polyimine obtained by reacting a bifunctional hydroxyl-terminated polybutadiene, a polyisocyanate compound, and a tetrachloro anhydride is described (JP-A-2006-37083) A modified polyimine such as a polyfluorene-containing polyamine (the one described in JP-A-2002-12667 and JP-A-2000-319386).

Specific examples of the polyamidoximine resin are "VYLOMAX HR11NN" and "VYLOMAX HR16NN" manufactured by Toyobo Co., Ltd. As a specific example of the polyamidoximine resin, modified polyamines such as "KS9100" and "KS9300", such as a polyoxyalkylene skeleton, which is a polyoxyalkylene skeleton, manufactured by Hitachi Chemical Co., Ltd. Yttrium.

A specific example of the polyether oxime resin is "PES5003P" manufactured by Sumitomo Chemical Co., Ltd., and the like.

Specific examples of the polyfluorene resin are condensed sheets "P1700" and "P3500" manufactured by SOLVAY ADVANCED POLYMERS.

The content of the thermoplastic resin in the resin composition is preferably from 0.1% by mass to 20% by mass, more preferably from 0.5% by mass to 10% by mass, even more preferably from 1% by mass to 5% by mass.

- hardening accelerator -

The hardening accelerator is exemplified by, for example, a phosphorus-based hardening accelerator, an amine-based hardening accelerator (for example, 4-dimethylaminopyridine), an imidazole-based hardening accelerator, an oxime-based hardening accelerator, a metal-based hardening accelerator, and the like. It is a phosphorus-based hardening accelerator, an amine-based hardening accelerator, and an imidazole-based hardening accelerator. The curing accelerator may be used alone or in combination of two or more. When the total amount of the non-volatile components of the epoxy resin and the curing agent is 100% by mass, the content of the curing accelerator in the resin composition layer is preferably from 0.05% by mass to 3% by mass.

- Flame retardant -

Examples of the flame retardant include an organic phosphorus-based flame retardant, a nitrogen-containing phosphorus compound, a nitrogen compound, a polyoxygenated flame retardant, and a metal hydroxide. The flame retardant may be used singly or in combination of two or more. The content of the flame retardant in the resin composition is not particularly limited, but is preferably 0.5 mass. %~10% by mass, more preferably 1% by mass to 9% by mass. As the flame retardant, for example, "HCA-HQ" manufactured by Sanko Co., Ltd. can be used.

-Organic filler -

As the organic filler, any organic filler which can be used in forming the insulating layer of the printed wiring board can be used, and examples thereof include rubber particles, polyamide fine particles, polyfluorene oxide particles, and the like, and rubber particles are preferable.

The rubber particles are not particularly limited as long as they are chemically crosslinked to a resin exhibiting rubber elasticity and are insoluble in an organic solvent, and are not particularly limited. For example, acrylonitrile butadiene rubber particles and butadiene are exemplified. Rubber particles, acrylic rubber particles, and the like. Specific examples of the rubber particles are XER-91 (made by Nippon Synthetic Rubber Co., Ltd.), STAFYROID AC3355, AC3816, AC3816N, AC3832, AC4030, AC3364, IM101 (above, AICA Industrial Co., Ltd.) PARAOID EXL2655, EXL2602 (above Wu Yu Chemical Industry Co., Ltd.).

The average particle diameter of the organic filler is preferably in the range of 0.005 μm to 1 μm, more preferably in the range of 0.2 μm to 0.6 μm. The average particle diameter of the organic filler can be measured by dynamic light scattering. For example, in an appropriate organic solvent, the organic filler is uniformly dispersed by ultrasonic waves or the like, and a particle size distribution of the organic filler is prepared on a mass basis using a thick particle size analyzer ("FPAR-1000" manufactured by Otsuka Electronics Co., Ltd.). The value is determined by setting the average particle diameter. The content of the organic filler in the resin composition layer is preferably from 1% by mass to 10% by mass, more preferably from 2% by mass to 5% by mass.

-Other ingredients -

The resin composition may contain other components as needed. Examples of the other component include an organometallic compound such as an organic copper compound, an organic zinc compound, and an organic cobalt compound, and a resin additive such as a tackifier, an antifoaming agent, a leveling agent, an adhesion imparting agent, and a coloring agent. .

The method of preparing the resin composition is not particularly limited, and for example, a method in which a solvent or the like is added as needed, and a method such as mixing or dispersing using a rotary mixer or the like is used. In addition, from the viewpoint of the fact that n ² in the above condition (ii) is 0.2 μm or less, if necessary, the particles having a specific particle diameter may be removed by filtering the resin composition or the like. Therefore, in one embodiment, the insulating layer is formed by thermally hardening a layer of the resin composition after the particles having a particle diameter of d (μm) or more are removed by filtration through a filter. Here, d is preferably 4 or less, more preferably 3 or less, still more preferably 2 or less, still more preferably 1 or less. The filtration precision of the filter is preferably 4 μm or less, more preferably 3 μm or less, still more preferably 2 μm or less, and still more preferably 1 μm or less. A preferred filter which can be used for the filtration of the resin composition is, for example, "SCP-010", "SHP-020", and "SHP-030" manufactured by ROKITECHNO Co., Ltd.

[circuit board]

A circuit board obtained based on the above concept of the present invention will be described.

The circuit board of the present invention is characterized in that it includes a circuit board on which an insulating layer having a through hole having an opening diameter of 15 μm or less is formed.

The arithmetic mean roughness (Ra) of the surface of the insulating layer is 150 nm or less.

The insulating layer comprises an inorganic filler. In the cross section of the insulating layer in a direction perpendicular to the surface of the insulating layer, when the maximum diameter of the inorganic filler contained in the region of a specific width is n ¹ (μm), n ¹ × The value of 1.27 (n ² ) is 0.2 μm or less.

The circuit board of the present invention is characterized in that a small-diameter through hole having a good through hole shape is formed on the insulating layer containing the inorganic filler.

The preferred range of the opening diameter of the through hole, the shape of the through hole (ie, the preferred range of D _mim /D and D _max /D), the preferred Ra value of the surface of the insulating layer, the thickness of the insulating layer, n ² and A ₂ The preferred range of /(A ₁ +A ₂ ) is as described above. The composition of the insulating layer is also as described above. In a preferred embodiment, the insulating layer contains an inorganic filler which is surface-treated with a decane compound containing an organic group having an aromatic ring. The details of the organic group having an aromatic ring, and preferred decane compounds are as described above.

The circuit board of the present invention further includes a conductor layer (circuit) formed on the surface of the insulating layer. The details of the conductor layer are described in [Manufacturing Method of Circuit Board] to be described later. In a preferred embodiment, the circuit board of the present invention has a ratio (L/S) of a circuit width (line; L) to a width (interval; S) between the circuits of 10 μm/10 μm or less (that is, a wiring pitch of 20 μm or less). The circuit. In a further preferred embodiment, L/S = 9 μm / 9 μm or less (wiring pitch: 18 μm or less), L/S = 8 μm / 8 μm or less (wiring pitch: 16 μm or less), L/S = 7 μm / 7 μm or less (wiring pitch: 14 μm) The following), L/S = 6 μm / 6 μm or less (wiring pitch: 12 μm or less), L/S = 5 μm / 5 μm or less (wiring pitch: 10 μm or less), or L/S = 4 μm / 4 μm or less (wiring pitch: 8 μm or less) Fine circuit.

[semiconductor device]

A semiconductor device can be manufactured using the circuit substrate of the present invention.

Examples of the semiconductor device include various semiconductor devices for electrical products (for example, computers, mobile phones, digital cameras, and televisions) and vehicles (for example, locomotives, automobiles, electric cars, ships, airplanes, etc.).

The semiconductor device of the present invention can be manufactured by mounting a component (semiconductor wafer) on a conduction portion of a circuit board. The term "conducting portion" means "a portion where a signal is transmitted in a circuit board", and the portion may be either a surface or an embedded portion. Further, the semiconductor wafer is not particularly limited as long as it is an electrical circuit element made of a semiconductor.

The method of mounting a semiconductor wafer in the manufacture of the semiconductor device of the present invention is not particularly limited as long as the function of the semiconductor wafer can be effectively utilized, and specific examples thereof include a wire bonding mounting method, a flip chip mounting method, and bump mounting and build-up (BBUL) mounting. The method includes a method of mounting an anisotropic conductive film (ACF), a method of mounting a non-conductive film (NCF), and the like. Here, the "mounting method using bumps and build-up layers (BBUL)" means "a method of mounting a semiconductor wafer directly in a concave portion of a printed wiring board to connect a semiconductor wafer to a wiring on a circuit board".

[Method of Manufacturing Circuit Board]

The method for producing the circuit board of the present invention is not particularly limited as long as the concept of the present invention described above can be achieved. Hereinafter, the comparison of the concept of the reachable cost invention Good implementation.

<First embodiment>

The method for producing a circuit board according to the present invention comprises the steps of: (A) laminating a film comprising a support and a resin composition layer provided on the support, and laminating the resin composition layer and the inner substrate a step of forming an insulating layer on the inner layer substrate; (B) thermally curing the resin composition layer in a state in which the support is attached; and (C) forming an opening diameter on the insulating layer by UV solid laser irradiation a step of a via hole of 15 μm or less; and the insulating layer formed in the step (B) comprises an inorganic filler, and the inorganic filler contained in the region of the specific width in the cross section of the insulating layer in a direction perpendicular to the surface of the insulating layer When the maximum diameter average value is n ¹ (μm), the value (n ² ) of n ¹ × 1.27 is 0.2 μm or less.

-Step (A)-

In the step (A), the adhesive film including the support and the resin composition layer provided on the support is laminated on the inner substrate such that the resin composition layer is bonded to the inner substrate.

The resin composition constituting the resin composition layer is as described above. The thickness of the resin composition layer is not particularly limited as long as the thickness t (μm) of the obtained insulating layer and the opening diameter D (μm) of the through hole satisfy the above-described specific relationship (that is, t≦3D), and may be appropriately determined.

The support is exemplified by, for example, a film made of a plastic material, a metal foil, and a release paper, and is preferably a film or a metal foil made of a plastic material.

When a film made of a plastic material is used as a support, examples of the plastic material include polyester such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), and polycarbonate (PC). An acrylic type, a cyclic polyolefin, a triethyl fluorene cellulose (TAC), a polyether sulfide (PES), a polyether ketone, a polyimine, or the like, such as polymethyl methacrylate (PMMA). Among them, polyethylene terephthalate or polyethylene naphthalate is preferred, and polyethylene terephthalate is particularly preferred. Commercially available products can be used for the polyethylene terephthalate. For example, "LUMIRROR T6AM" manufactured by TORAY Co., Ltd. or the like can be used.

When a metal foil is used as the support, the metal foil is preferably, for example, a copper foil or an aluminum foil, and is preferably a copper foil. As the copper foil, a foil made of a single metal of copper may be used, and a foil made of an alloy of copper and another metal such as tin, chromium, silver, magnesium, nickel, zirconium, hafnium, titanium or the like may be used.

The support may be subjected to a matte treatment or a corona treatment on the surface on the side joined to the resin composition layer. Further, as the support, a support having a release layer with a release layer on the surface on the side joined to the resin composition layer may be used. The release agent to be used for the release layer of the support having the release layer is, for example, one or more selected from the group consisting of an alkyd resin, an olefin resin, a urethane resin, and a polyoxymethylene resin. Release agent. The commercially available product of the release agent is, for example, "SK-1", "AL-5", "AL-7" manufactured by LINTEK Co., Ltd., which is an alkyd-based release agent.

The arithmetic mean roughness (Ra) of the surface of the side where the support is bonded to the resin composition layer is 150 nm or less, preferably 140 nm or less, from the viewpoint of lowering the Ra value of the surface of the insulating layer formed in the step (B). More preferably, it is 130 nm or less, more preferably 120 nm or less, still more preferably 110 nm or less, and particularly preferably 100 nm or less, 90 nm or less, 80 nm or less, or 70 nm or less. The lower limit of the Ra is not particularly limited. However, from the viewpoint of obtaining an insulating layer having good adhesion to the conductor layer, it is usually 1 nm or more, 5 nm or more, 10 nm or more. The arithmetic mean roughness (Ra) of the surface of the side of the support joined to the resin composition layer can be measured by the same method as that described for Ra of the surface of the insulating layer.

The thickness of the support is not particularly limited, but is preferably 75 μm or less, more preferably 60 μm or less, 50 μm or less, or 40 μm or less. The lower limit of the thickness of the support is not particularly limited, and may be usually 1 μm or more, 2 μm or more, 5 μm or more. Further, when the support is a support having a release layer, the total thickness of the support to which the release layer is attached is preferably in the above range.

Next, the film can be prepared by dissolving a resin composition in an organic solvent to prepare a resin varnish, applying the resin varnish to a support using a die coater, and drying to form a resin composition layer.

Examples of the organic solvent are ketones such as acetone, methyl ethyl ketone (MEK) and cyclohexanone, ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate, and card. Acetate such as alcoholic acetate, carbitol such as cellosolve and butyl carbitol, aromatic hydrocarbon such as toluene and xylene, dimethylformamide, dimethylacetamidine A guanamine solvent such as an amine (DMAc) or N-methylpyrrolidone, a solvent petroleum brain or the like. Have The solvent may be used singly or in combination of two or more.

Drying can be carried out by a conventional method such as heating or hot air blowing. The drying conditions are not particularly limited, but the organic solvent content in the resin composition layer is 10% by mass or less, preferably 5% by mass or less. Although it varies depending on the boiling point of the organic solvent in the resin varnish, for example, when a resin varnish containing 30% by mass to 60% by mass of an organic solvent is used, the resin composition can be formed by drying at 50 ° C to 150 ° C for 3 minutes to 10 minutes. Layer of matter.

Next, in the film, a protective film which is supported by the support may be laminated on the surface of the resin composition layer which is not bonded to the support (that is, the surface opposite to the support). The thickness of the protective film is not particularly limited, but may be, for example, 1 μm to 40 μm. By laminating the protective film, it is possible to prevent contamination or scratches from adhering to the surface of the resin composition layer. The film can then be rolled into a roll for storage. When the film has a protective film, it can be used by peeling off the protective film.

The "inner substrate" used in the step (A) mainly means a substrate such as a glass epoxy substrate, a metal substrate, a polyester substrate, a polyimide substrate, a BT resin substrate, or a thermosetting polyphenylene ether substrate, or the like. A substrate on which a patterned layer (circuit) is formed on one or both sides of the substrate. In the case of manufacturing a circuit board, the inner layer circuit board in which all of the intermediate products in which the insulating layer and/or the conductor layer are formed is included in the "inner substrate" as referred to in the present invention. When the circuit board is a part of the built-in board, it is only necessary to use the inner board of the built-in parts.

The laminate of the inner layer substrate and the succeeding film can be performed by, for example, heating the film to the inner layer substrate with the film on the side of the self-supporting body. As a connection The member in which the film is heated and pressed against the inner substrate (hereinafter also referred to as "heating and pressing member") is exemplified by, for example, a heated metal plate (SUS mirror plate or the like) or a metal roll (SUS roll). Further, since the heating and pressing member is not directly pressed against the adhesive film, it is preferable to pressurize the elastic member such as heat-resistant rubber so that the adhesive film sufficiently follows the surface unevenness of the inner layer substrate.

The laminate of the inner substrate and the subsequent film can also be carried out by a vacuum lamination method. In the vacuum lamination method, the heating and pressing temperature is preferably from 60 ° C to 160 ° C, more preferably from 80 ° C to 140 ° C, and the heating and pressing pressure is preferably from 0.098 MPa to 1.77 MPa, more preferably from 0.29 MPa to 1.47 MPa. The range of the heating and pressing time is preferably from 20 seconds to 400 seconds, more preferably from 30 seconds to 300 seconds. The lamination is preferably carried out under reduced pressure of 26.7 hPa or less.

The laminate can be carried out by a commercially available vacuum laminator. A commercially available vacuum laminator is, for example, a vacuum pressurizing laminator manufactured by Nippon Seisakusho Co., Ltd., a vacuum applicator manufactured by Nichigo-Morton Co., Ltd., or the like.

After the lamination, the heating and pressing member may be pressurized under normal pressure (at atmospheric pressure) by, for example, a self-supporting body side, and the subsequent film smoothing treatment of the laminated layer may be performed. The pressurization conditions of the smoothing treatment can be set to the same conditions as those of the above-described laminated heating and pressing conditions. The smoothing process can be carried out by a commercially available laminator. Further, the lamination and smoothing treatment can be continuously performed using the commercially available vacuum laminator described above.

-Step (B)-

In the step (B), the resin composition layer is heated in a state in which the support is attached. Hardened to form an insulating layer.

The thermosetting condition is not particularly limited, and conditions generally employed in forming an insulating layer of a circuit board can be used.

The thermosetting condition of the resin composition layer varies depending on the composition of the resin composition used for the resin composition layer, etc., and is not particularly limited as long as the conditions for forming a suitable insulating layer are finally formed. For example, the thermosetting temperature is preferably 120 ° C. The range of 240 ° C, more preferably in the range of 150 ° C to 210 ° C, and more preferably in the range of 160 ° C to 190 ° C. Here, the thermosetting temperature is not necessarily fixed to a specific temperature in the above temperature range, and if a suitable insulating layer is finally formed, it may be changed over time, or may be classified into a plurality of stages of hardening at different curing temperatures. And the highest reaching temperature of the hardening temperature is preferably within the above range.

The heat hardening time varies depending on the composition of the resin composition used in the resin composition layer and the heat curing temperature. However, if a suitable insulating layer is finally formed, it is not particularly limited, and may be, for example, 20 minutes to 150 minutes, preferably 30 minutes. ~120 minutes, preferably 40 minutes to 120 minutes.

The thermal hardening of the resin composition layer is preferably carried out under atmospheric pressure (at normal pressure).

As described above, in the present invention, the arithmetic mean roughness (Ra) of the surface of the insulating layer is set to 150 nm or less (condition (i)). When the Ra value exceeds 150 nm, the laser workability is lowered, and the shape of the via hole is deteriorated. In general, when the resin composition is thermally cured to form an insulating layer, the inorganic filler is exposed from the surface of the insulating layer by melting of the resin, and undulation or the like is generated on the surface to lower the smoothness, and it is difficult to make Ra at a low value. The electric power of the present invention in which the resin composition layer is thermally hardened by attaching a support body to the resin composition layer The method of manufacturing the substrate can easily achieve a low Ra value. Further, in the case of heat hardening, it is effective to increase the temperature in order to increase the Ra value. For example, the method of heating at a temperature T2 (but 150 ° C ≦ T2 ≦ 240 ° C) for 5 minutes to 90 minutes after heating at a heat hardening temperature T1 (but 50 ° C ≦ T1 < 150 ° C) for 10 minutes to 60 minutes is performed. . The preferred range of the Ra value is as described above.

The insulating layer formed in the step (B) contains an inorganic filler, and in the cross section of the insulating layer in a direction perpendicular to the surface of the insulating layer, n ^{2 in} a region of a specific width is 0.2 μm or less (condition (ii)). When n ² exceeds 0.2 μm, the laser workability is lowered, and the shape of the via hole is deteriorated. N ² is generally high in the insulating layer in the case where the content of the inorganic filler tends to increase it. When n ² is lowered, the following is effective: 1) using an inorganic filler having a small average particle diameter, 2) using an inorganic filler which is surface-treated with a decane compound having an organic group having an aromatic ring, and 3) implementing a resin composition The filter is filtered. The preferred range of n ² is as described above.

The support can also be removed after step (B). In a preferred embodiment, the support is removed prior to step (C). Further, when a metal foil having an extremely thin thickness (for example, a thickness of 2 μm or less or 1 μm or less) is used as the support, the step (C) may be carried out in a state in which the support is attached to the insulating layer.

-Step (C)-

In the step (C), a through hole having an opening diameter of 15 μm or less is formed on the insulating layer by a UV solid laser.

Details about UV solid laser (laser wavelength, etc.), through hole The opening diameter or shape is as described above.

-Step (D)-

The method for producing a circuit board of the present invention may further comprise the step of (D) desmear treatment after the step (C).

According to the method of the present invention, a small-diameter through hole having a small amount of dross inside the through hole can be formed on the insulating layer containing the inorganic filler (even when the content of the inorganic filler in the insulating layer is high). Therefore, in the method of the present invention, step (D) may or may not be carried out. When the step (D) is carried out, it can also be carried out under milder conditions than the usual desmear treatment. Therefore, it is possible to suppress the roughening of the surface of the insulating layer by the desmear treatment, and it is possible to realize an insulating layer having a low surface roughness suitable for forming fine wiring.

The desmear treatment is not particularly limited and can be carried out by various methods. In one embodiment, the desmear treatment can be a wet desmearing treatment using an oxidizer solution.

In the wet degumming treatment using the oxidizing agent solution, the swelling treatment by the swelling liquid, the oxidation treatment using the oxidizing agent solution, and the neutralization treatment using the neutralization liquid are preferably carried out in sequence. The swelling solution is not particularly limited, and examples thereof include an alkali solution and a surfactant solution, and an alkali solution is preferred. The alkali solution is preferably a sodium hydroxide solution or a potassium hydroxide solution. The commercially available swelling liquid is exemplified by, for example, Swelling Dip Securiganth P, Swelling Dip Securiganth SBU, etc., manufactured by ATOTECH Co., Ltd., Japan. The swelling treatment by the swelling liquid is not particularly limited, but the insulating layer may be immersed in a swelling liquid of, for example, 30 to 90 ° C for 1 to 20 minutes. base From the viewpoint of suppressing the swelling of the resin of the insulating layer to a moderate degree, it is preferred that the hardened body is immersed in a swelling liquid at 40 to 80 ° C for 5 to 15 minutes. The oxidizing agent solution is not particularly limited, and for example, an alkaline permanganic acid solution in which potassium permanganate or sodium permanganate is dissolved in an aqueous sodium hydroxide solution is exemplified. The oxidation treatment using an oxidizing agent such as an alkaline permanganic acid solution is preferably carried out by immersing the insulating layer in an oxidizing agent solution heated to 60 to 80 ° C for 10 to 30 minutes. Further, the permanganate concentration in the alkaline permanganic acid solution is preferably from 5% by mass to 10% by mass. The commercially available oxidizing agent solution is, for example, an alkaline permanganic acid solution such as "Concentrate Compact CP" or "Doesing Solution Securiganth P" manufactured by ATOTECH Co., Ltd., Japan. Further, the neutralizing liquid is preferably an acidic aqueous solution, and the commercially available product is, for example, "Reduction Solution Securiganth P" manufactured by ATOTECH Co., Ltd., Japan. The treatment with the neutralizing liquid is carried out by immersing the treated surface of the roughening treatment with an oxidizing agent at 30 to 80 ° C for 5 to 30 minutes. In view of workability and the like, it is preferred to immerse the object subjected to the roughening treatment with an oxidizing agent in a liquid at 40 to 70 ° C for 5 minutes to 20 minutes.

-Step (E)-

The method for manufacturing a circuit board of the present invention may further comprise the step of forming a conductor layer on the surface of the insulating layer after the step (C).

The conductor material used in the conductor layer is not particularly limited. In a preferred embodiment, the conductor layer comprises one or more metals selected from the group consisting of gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin, and indium. . The conductor layer may be a single metal layer or an alloy layer. The alloy layer is exemplified by a layer formed of, for example, an alloy of two or more kinds of metals selected from the above group (for example, a nickel/chromium alloy, a copper/nickel alloy, and a copper/titanium alloy). Among them, a single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver or copper, or nickel is preferred from the viewpoints of wide use of the conductor layer formation, cost, ease of patterning, and the like. /Cr alloy, copper/nickel alloy, copper/titanium alloy layer, preferably a single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver or copper, or an alloy layer of nickel/chromium alloy More preferably a single metal layer of copper.

The conductor layer may have a single layer structure or a multi-layer structure in which a single metal layer or an alloy layer made of a different type of metal or alloy is laminated in two or more layers. When the conductor layer has a multi-layer structure, the layer in contact with the insulating layer is preferably a single metal layer of chromium, zinc or titanium, or an alloy layer of nickel/chromium alloy.

The thickness of the conductor layer is determined according to the design of the desired circuit board, but is usually 35 μm or less, preferably 30 μm or less, more preferably 25 μm or less. The lower limit of the thickness of the conductor layer is not particularly limited, but is usually 3 μm or more, and preferably 5 μm or more.

In the step (E), the conductor layer may be formed by dry plating, wet plating, or a combination thereof.

Examples of the dry plating include chemical vapor deposition (PVD) methods such as vapor deposition, sputtering, ion plating, and laser ablation, thermal CVD, and plasma CVD. It is good for evaporation and sputtering. When the conductor layer is formed only by dry plating, the conductor layer (circuit) may be formed by a conventional method such as a full addition method.

When forming a conductor layer by wet plating, it is also possible to combine A semi-additive method of electroless plating and electrolytic plating forms a conductor layer, and a conductor layer can be formed by a full-addition method only by electroless plating by forming a plating resist having a pattern opposite to that of the conductor layer. . When an extremely thin metal foil is used as the support, the conductor layer can be formed by a modified semi-additive method. These methods can also be carried out in accordance with the order of knowledge in the art.

Dry plating and wet plating may also be combined to form a conductor layer. For example, a metal layer formed by dry plating can be used as a plating seed layer, and a conductor layer can be formed by a semi-additive method using electrolytic plating or electroless plating.

In the semi-additive method, a plating layer which is not required to be plated is removed by etching to form a conductor layer (circuit) having a desired wiring pattern. In this case, when the surface roughness of the insulating layer is large, it is difficult to remove the plating seed layer having a large thickness region when the wiring pattern is formed by etching to remove the plating seed layer, and the thickness is sufficiently removed. When the conditions for plating the seed layer in the region are etched, the dissolution of the wiring pattern becomes remarkable, which becomes an obstacle to miniaturization of the circuit wiring. On the other hand, in the method of the present invention, as described above, since the desmear treatment can be omitted or can be carried out under mild conditions, an insulating layer having a low surface roughness can be realized. In addition, the method of manufacturing the circuit board of the present invention contributes significantly to both the high density and the miniaturization of the circuit wiring, in addition to the effect of the small-diameter through-hole having a good through-hole shape.

<Second embodiment>

The method for producing a circuit board according to the present invention includes the following steps: (A) bonding a support film and a resin composition layer provided on the support, and bonding the resin composition layer to the inner substrate a step of laminating on the inner substrate; (B) a step of thermally hardening the resin composition layer in a state in which the support is attached to form an insulating layer; and (C) forming a UV solid on the insulating layer The step of opening a hole having a diameter of 15 μm or less; and the resin composition layer of the film to be used in the step (A) contains 30% by mass or more of an inorganic filler having a BET specific surface area of 20 m ² /g or more.

The preferred range of the BET specific surface area and content of the inorganic filler of the second embodiment is as described above.

Steps (A) to (C) of the second embodiment are as described in "Step (A)" to "Step (C)" of the first embodiment. Further, after the step (C), the above steps (D) and (E) may be further included. Step (D) and step (E) are as described in "Step (D)" and "Step (E)" in the first embodiment.

<Third embodiment>

The method for producing a circuit board according to the present invention is characterized in that the method comprises the steps of: (A) bonding a support film and a resin composition layer provided on the support, and bonding the resin composition layer to the inner substrate. a step of laminating on the inner substrate; (B) a step of thermally hardening the resin composition layer in a state in which the support is attached to form an insulating layer; (C) a step of forming a via hole having an opening diameter of 15 μm or less by a UV solid laser on the insulating layer; and the resin composition layer of the adhesive film used in the step (A) contains an average particle diameter of 30% by mass or more or 0.2. Inorganic filler below μm.

The preferred range of the average particle diameter and content of the inorganic filler in the third embodiment is as described above.

Steps (A) to (C) of the third embodiment are as described in "Step (A)" to "Step (C)" of the first embodiment. Further, after the step (C), the above steps (D) and (E) may be further included. Step (D) and step (E) are as described in "Step (D)" and "Step (E)" in the first embodiment.

Although the preferred embodiments of the method for manufacturing a circuit board of the present invention are exemplified above, the method of the present invention may include steps other than the above, as long as the concept of the present invention described above can be achieved.

[Examples]

The invention will be described in more detail below by using examples, but the invention is not limited to the examples. In the following description, "parts" and "%" mean "parts by mass" and "% by mass", respectively, unless otherwise stated.

<Measurement/Evaluation Method>

First, the measurement/evaluation method in the physical property evaluation in the present specification will be described.

[Modulation of substrate for measurement/evaluation]

(1) Underlying processing of the inner layer circuit substrate

A micro-etching agent (made by MERCK) is used on both sides of a copper-clad laminate (a copper foil thickness of 18 μm, a substrate thickness of 0.4 mm, and a Panason IC (R1515A)) on a glass cloth substrate on which a circuit is formed. CZ8100") The surface of the copper was roughened by etching 1 μm.

(2) followed by film laminate

The film peeling protective film produced from the examples and the comparative examples was used. Using a batch vacuum pressure laminator (Nichigo-Morton Co., Ltd. 2-stage build-up laminator "CVP700"), the film of the exposed resin composition layer was bonded to the inner layer circuit substrate by a resin composition layer. Laminated on both sides of the inner circuit board. The laminate was applied at a pressure of 10 hPa for 30 seconds, and then pressed at 100 ° C and a pressure of 0.74 MPa for 30 seconds. Next, the deposited film was smoothed under atmospheric pressure at 100 ° C and a pressure of 0.5 MPa for 60 seconds.

(3) Hardening of the resin composition layer

After the film is laminated, the resin composition layer is thermally cured to form an insulating layer on both surfaces of the inner layer circuit board. At this time, the resin composition layer is thermally cured in a state in which the support is attached, and the support is peeled off after heat curing. The obtained substrate is referred to as "evaluation substrate a".

Thermal curing of the resin composition layer at 100 ° C (input 100 After oven at °C for 30 minutes, followed by 170 ° C (after changing to an oven at 170 ° C) for 30 minutes, and heat hardened. The substrate was then taken out under a room temperature atmosphere.

(4) Formation of through-holes of UV-YAG laser

A through hole having a small diameter was formed on the insulating layer of the evaluation substrate a using a UV-YAG laser processing machine ("LU-2L212/M50L" manufactured by VIA MECHANICAL Co., Ltd.). Example 1 was subjected to the following condition I-1, Example 2 and Comparative Examples 1 and 3 were subjected to the following condition I-2, Example 3 was subjected to the following condition I-3, and Comparative Example 2 was formed under the following condition I-4. . The obtained substrate is referred to as "evaluation substrate b".

Condition I-1: power 0.08W, number of irradiation 15, attack hole diameter 10μm

Condition I-2: Power 0.08W, irradiation number 25, attack hole diameter 10μm

Condition I-3: power 0.17W, irradiation number 25, attack hole diameter 15μm

Condition I-4: Power 0.17W, irradiation number 60, attack hole diameter 15μm

<Measurement of arithmetic mean roughness (Ra)>

For the evaluation substrate a, a non-contact surface roughness meter ("WYKO NT3300" manufactured by VECCO Instruments Co., Ltd.) was used, and the Ra value was obtained by setting the measurement range to 121 μm × 92 μm with a 50-fold lens in the VSI contact mode. Find a random selection of 10 points for each sample Mean.

<Evaluation of particle size of inorganic filler in insulating layer>

For the evaluation substrate b, a cross-sectional observation of the insulating layer was performed using a FIB-SEM composite device ("SMI3050SE" manufactured by SII Nanotechnology Co., Ltd.). Specifically, a cross-sectional SEM image (observation width: 30 μm, observation magnification x 9000) was obtained by cutting a cross section perpendicular to the surface of the evaluation substrate by FIB (bundled ion beam). A cross-sectional SEM image of 10 randomly selected portions was obtained for each sample.

Each of the obtained cross-sectional SEM images of the 10 portions was measured in a region having a width of 15 μm, that is, a total thickness of the insulating layer in the longitudinal direction and a quadrangular region having a lateral direction of 15 μm (total thickness of the insulating layer (longitudinal) × 15 μm (horizontal)) The maximum diameter of the inorganic filler contained in the region is obtained as the average value n ¹ . The average value n ^{1 is} multiplied by 1.27 times to calculate the value n ² (average particle diameter). When the maximum diameter of the inorganic filler exceeds 1/2 into a region having a width of 15 μm, the inorganic filler is judged to be "included in a region having a width of 15 μm".

<Measurement of Resin Area and Inorganic Filler Area of Insulation Layer Profile>

For the evaluation substrate b, a cross-sectional observation of the insulating layer was performed using a FIB-SEM composite device ("SMI3050SE" manufactured by SII Nanotechnology Co., Ltd.). Specifically, a cross-sectional SEM image (observation width: 30 μm, observation magnification x 9000) was obtained by cutting a cross section perpendicular to the surface of the evaluation substrate by FIB (bundled ion beam). A cross-sectional SEM image of 10 randomly selected portions was obtained for each sample. Each of the obtained cross-sectional SEM images of the 10 portions was measured in a region having a width of 15 μm, that is, a total thickness of the insulating layer in the longitudinal direction, and a rectangular region having a lateral direction of 15 μm (total thickness of the insulating layer (longitudinal) × 15 μm (horizontal)) region) of the resin area A _1, an inorganic filler and an area _{A 2, A 2 / (A} 1 + A 2) the value obtained from the values of A ₁ and A ₂ values is calculated.

Specifically, the resin area A ₁ and the inorganic filler area A ₂ are stored as an image using an SEM observation image, and the image analysis software is used, and the resin portion is black, and the inorganic filler portion other than the resin is white. The white black is binarized, and the number of bits in the black portion is defined as the resin area A ₁ , and the number of bits in the white portion is defined as the inorganic filler area A ₂ .

<Evaluation of the shape of the through hole>

The through hole opening portion was observed on the surface of the evaluation substrate b using a scanning electron microscope ("S-4800" manufactured by Hitachi High-Tech Co., Ltd.). From the obtained image, the opening diameter D of the through hole and the minimum diameter _Dmin of the through hole were measured. The D and D _{min were} measured for 10 through holes, and the average value of the D _mim /D ratio was obtained. The shape of the via hole was evaluated based on the average value of the obtained D _mim /D ratio by the following evaluation criteria.

Evaluation criteria:

○: D _mim /D ratio is 0.65 or more

×: D _mim / D ratio is less than 0.65

<Preparation Example 1> Modulation of Resin Varnish 1

Bisphenol AF type epoxy resin ("YL7760" manufactured by Mitsubishi Chemical Corporation, epoxide equivalent: 238) 10 parts, biphenyl type epoxy resin ("30003000" manufactured by Nippon Kayaku Co., Ltd.), epoxy equivalent 269) 15 parts, bisxylenol type epoxy resin ("XX4000HK" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 185) 10 parts and phenoxy resin ("XX7553BH30" manufactured by Mitsubishi Chemical Corporation), solid content 30% by mass of cyclohexanone: a 1:1 solution of methyl ethyl ketone (MEK)) 35 parts of 5 parts of solvent petroleum brain and 2 parts of MEK were heated and dissolved while stirring. After cooling to room temperature, 4 parts of a phenol novolac-based curing agent (hydroxyl equivalent: 125, DIC (manufactured by DIC), MEK solution of 60% solid content) containing a triazine skeleton, and an active ester system were mixed therein. Hardener (HPC-8000-65T, manufactured by DIC), toluene solution of about 223 active base equivalent, and 65 mass% of nonvolatile matter), amine hardening accelerator (4-dimethylaminopyridine (DMAP) 2 parts of a MEK solution having a solid content of 5% by mass) 2 parts of spherical cerium oxide surface-treated with N-phenyl-3-aminopropyltrimethoxydecane ("KBM573" manufactured by Shin-Etsu Chemical Co., Ltd.) "UFP-30" manufactured by Chemical Industry Co., Ltd., having an average particle diameter of 0.1 μm, a specific surface area of 30 m ² /g, and a carbon content of 0.36 mg/m ² per unit surface area, is uniformly dispersed by a high-speed rotary mixer. A sputum filter ("SCP-010" manufactured by ROKITECHNO, filter efficiency (manufacturer's nominal value): 99.9% or more of particles of 1 μm or more) was filtered to prepare a resin varnish 1.

<Preparation Example 2> Modulation of Resin Varnish 2

Bisphenol AF type epoxy resin ("YL7760" manufactured by Mitsubishi Chemical Corporation, epoxide equivalent: 238) 12 parts, biphenyl type epoxy resin ("30003000" manufactured by Nippon Kayaku Co., Ltd.), epoxy equivalent 269) 12 parts, bisxylenol type epoxy resin ("YX4000HK" manufactured by Mitsubishi Chemical Co., Ltd., epoxy equivalent: 185) 12 parts and phenoxy resin ("XX7553BH30" manufactured by Mitsubishi Chemical Corporation), solid content 30% by mass of cyclohexanone: a 1:1 solution of methyl ethyl ketone (MEK)) 10 parts of the solvent petroleum brain 25 parts, MEK 6 parts, and heated and dissolved while stirring. After cooling to room temperature, a cresol novolak-based hardener containing a triazine skeleton (hydroxy equivalent 151, DIC (LA-3018-50P), solid content 50% 2-methoxy propylene) was mixed therein. Alcohol solution) 6 parts, an active ester-based curing agent ("HPC-8000-65T" manufactured by DIC Co., Ltd., a toluene solution having a reactive base equivalent of about 223 and a nonvolatile content of 65 mass%), 16 parts, an amine-based hardening accelerator ( 2-dimethylaminopyridine (DMAP), a solid content of 5% by mass of MEK solution), 2 parts, N-phenyl-3-aminopropyltrimethoxydecane ("MK Corporation" The surface-treated spherical cerium oxide ("UFP-30" manufactured by Electrochemical Industry Co., Ltd., average particle diameter: 0.1 μm, specific surface area: 30 m ² /g, carbon content per unit surface area: 0.36 mg/m ² ) 80 parts, After the high-speed rotary mixer was uniformly dispersed, the resin varnish 2 was prepared by filtration using a krypton filter ("SCP-010" manufactured by ROKITECHNO, filter efficiency (manufacturer's nominal value): 99.9% or more of particles of 1 μm or more).

<Preparation Example 3> (Modulation of Resin Varnish 3)

A bisphenol type epoxy resin (ZX1059) made by Nippon Steel & Sumitomo Chemical Co., Ltd., a 1:1 mixture of bisphenol A type and bisphenol F type, epoxy equivalent of about 169) 5 parts, naphthalene type epoxy 5 parts of a resin ("HP4032SS" manufactured by DIC Co., Ltd., epoxy equivalent: 144), and 20 parts of a dicyclopentadiene type epoxy resin ("HP-7200HH" manufactured by DIC Co., Ltd., epoxy equivalent: about 280). Phenoxy resin ("XX7553BH30" manufactured by Mitsubishi Chemical Co., Ltd., 30% by mass of cyclohexanone: 1:1 solution of MEK) 20 parts of MEK 6 parts were heated and dissolved while stirring. After cooling to room temperature, 10 parts of a phenol novolac-based curing agent (hydroxyl equivalent: 125, DIC (manufactured by DIC), and 60% solid MEK solution) containing a triazine skeleton was mixed therein, and a naphthol system was added. Hardener ("SN-485" made by Nippon Steel & Sumitomo Chemical Co., Ltd., hydroxy equivalent 215, 60% solids in MEK solution) 10 parts, polyvinyl butyral resin (glass transition temperature 105 ° C, Sekisui Chemical Industry ( "KS-1") 15 parts of a solid solution of 15% ethanol and toluene in a mixture of 1:1, an amine-based hardening accelerator (4-dimethylaminopyridine (DMAP), solid content of 5% by mass MEK solution) 1 part, flame retardant (HCA-HQ, manufactured by Sanguang Co., Ltd., 10-(2,5-dihydroxyphenyl)-10-hydrogen-9-oxa-10-phosphaphenanthrene-10- 2 parts of an oxide, an average particle diameter of 2 μm, and spherical cerium oxide surface-treated with N-phenyl-3-aminopropyltrimethoxydecane ("KBM573" manufactured by Shin-Etsu Chemical Co., Ltd.) (Electrical Chemical Industry ( "UFP-60S", the average particle size of 0.08μm, specific surface area of 60m ² /g, carbon content per unit surface area of 0.34mg / m ² ) 25 parts, evenly dispersed in a high-speed rotary mixer, with a 匣 filter ("SCP-010" made by ROKITECHNO, filtering Rate (nominal value of the manufacturer): The above particles taken 1μm 99.9%) was filtered to prepare a resin varnish 3.

<Preparation Example 4> (Modulation of Resin Varnish 4)

Bisphenol AF type epoxy resin ("YL7760" manufactured by Mitsubishi Chemical Corporation, epoxide equivalent: 238) 12 parts, biphenyl type epoxy resin ("30003000" manufactured by Nippon Kayaku Co., Ltd.), epoxy equivalent 269) 12 parts, bisxylenol type epoxy resin ("XX4000HK" manufactured by Mitsubishi Chemical Co., Ltd., epoxy equivalent: 185) 12 parts and phenoxy resin ("XX7553BH30" manufactured by Mitsubishi Chemical Corporation), solid content 30% by mass of cyclohexanone: a 1:1 solution of methyl ethyl ketone (MEK)) 10 parts of the solvent petroleum brain 20 parts, MEK 4 parts, and heated and dissolved while stirring. After cooling to room temperature, a cresol novolak-based hardener containing a triazine skeleton (hydroxy equivalent 151, DIC (LA-3018-50P), solid content 50% 2-methoxy propylene) was mixed therein. Alcohol solution) 6 parts, an active ester-based curing agent ("HPC-8000-65T" manufactured by DIC Co., Ltd., a toluene solution having a reactive base equivalent of about 223 and a nonvolatile content of 65 mass%), 16 parts, an amine-based hardening accelerator ( 2-dimethylaminopyridine (DMAP), a solid content of 5% by mass of MEK solution), 2 parts, N-phenyl-3-aminopropyltrimethoxydecane ("MK Corporation" The surface-treated spherical cerium oxide ("SO-C1" manufactured by Electric Chemical Industry Co., Ltd., average particle diameter 0.30 μm, specific surface area 10 m ² /g, carbon content per unit surface area 0.36 mg/m ² ) 80 parts, After the high-speed rotary mixer was uniformly dispersed, the resin varnish 4 was prepared by filtration using a krypton filter ("SHP-030" manufactured by ROKITECHNO, filter efficiency (manufacturer's nominal value): 99.9% or more of particles of 2 μm or more).

<Preparation Example 5> (Modulation of Resin Varnish 5)

Bisphenol AF type epoxy resin ("YL7760" manufactured by Mitsubishi Chemical Corporation, epoxide equivalent: 238) 12 parts, biphenyl type epoxy resin ("30003000" manufactured by Nippon Kayaku Co., Ltd.), epoxy equivalent 269) 12 parts, bisxylenol type epoxy resin ("YX4000HK" manufactured by Mitsubishi Chemical Co., Ltd., epoxy equivalent: 185) 12 parts and phenoxy resin ("XX7553BH30" manufactured by Mitsubishi Chemical Corporation), solid content 30% by mass of cyclohexanone: a 1:1 solution of methyl ethyl ketone (MEK)) 10 parts of 15 parts of solvent petroleum brain and 2 parts of MEK were heated and dissolved while stirring. After cooling to room temperature, a cresol novolak-based hardener containing a triazine skeleton (hydroxy equivalent 151, DIC (LA-3018-50P), solid content 50% 2-methoxy propylene) was mixed therein. Alcohol solution) 6 parts, an active ester-based curing agent ("HPC-8000-65T" manufactured by DIC Co., Ltd., a toluene solution having a reactive base equivalent of about 223 and a nonvolatile content of 65 mass%), 16 parts, an amine-based hardening accelerator ( 2-dimethylaminopyridine (DMAP), a solid content of 5% by mass of MEK solution), 2 parts, N-phenyl-3-aminopropyltrimethoxydecane ("MK Corporation" ) Surface-treated spherical cerium oxide ("SO-C2" manufactured by ADOMATEX Co., Ltd., average particle diameter 0.50 μm, specific surface area 6 m ² /g, carbon content per unit surface area 0.39 mg/m ² ) 80 parts, rotated at high speed After the mixture was uniformly dispersed, the resin varnish 5 was prepared by filtering with a ruthenium filter ("SHP-050" manufactured by ROKITECHNO, filter efficiency (manufacturer's nominal value): 99.9% or more of particles of 3 μm or more).

<Production Example 1> Next, the production of the film 1

A PET film ("LUMIRROR T6AM" manufactured by TORAY Co., Ltd., thickness 38 μm, softening point 130 ° C) which was subjected to mold release treatment with an alkyd resin release agent ("AL-5" manufactured by LINTEK Co., Ltd.) was used as a support. . The resin varnish 1 was applied onto the release surface of the support by a die coater, and dried at 80 ° C to 110 ° C (average 100 ° C) for 1.5 minutes to form a resin composition layer. The thickness of the resin composition layer was 10 μm. Next, a polypropylene film ("ALPHAND MA-411" manufactured by Oji Paper Co., Ltd., thickness: 15 μm) as a protective film was used as a protective film on the surface of the resin composition layer which was not bonded to the support. The film 1 was laminated so as to be bonded to the resin composition layer.

<Production Example 2> Production of Film 2 Next

A PET film ("LUMIRROR T6AM" manufactured by TORAY Co., Ltd., thickness 38 μm, softening point 130 ° C) which was subjected to mold release treatment with an alkyd resin release agent ("AL-5" manufactured by LINTEK Co., Ltd.) was used as a support. . The resin varnish 2 was applied onto the release surface of the support by a die coater, and dried at 80 ° C to 110 ° C (average 100 ° C) for 2 minutes to form a resin composition layer. The thickness of the resin composition layer was 15 μm. Next, a polypropylene film ("ALPHAND MA-411" manufactured by Oji Paper Co., Ltd., thickness: 15 μm) as a protective film was used as a protective film on the surface of the resin composition layer which was not bonded to the support. The film 2 was laminated so as to be bonded to the resin composition layer.

<Production Example 3> Next, the production of the film 3

The adhesive film 3 was produced in the same manner as in Production Example 2 except that the resin varnish 3 was used instead of the resin varnish 2.

<Production Example 4> Next, the production of the film 4

The adhesive film 4 was produced in the same manner as in Production Example 2 except that the resin varnish 4 was used instead of the resin varnish 2.

<Production Example 5> Production of Film 5 Next

A film 5 was produced in the same manner as in Production Example 2 except that the resin varnish 5 was used instead of the resin varnish 2.

<Example 1>

Using the adhesive film 1, the evaluation substrate was prepared in accordance with the above [modulation of the substrate for measurement/evaluation], and each evaluation was performed.

<Example 2>

Using the adhesive film 2, the evaluation substrate was prepared in accordance with the above [modulation of the substrate for measurement/evaluation], and each evaluation was performed.

<Example 3>

Using the adhesive film 3, the evaluation substrate was prepared in accordance with the above [modulation of the substrate for measurement/evaluation], and each evaluation was performed.

<Comparative Example 1>

Using the adhesive film 4, the evaluation substrate was prepared in accordance with the above [modulation of the substrate for measurement/evaluation], and each evaluation was performed.

<Comparative Example 2>

Using the adhesive film 4, the evaluation substrate was prepared in accordance with the above [modulation of the substrate for measurement/evaluation], and each evaluation was performed.

<Comparative Example 3>

Using the adhesive film 5, the evaluation substrate was prepared in accordance with the above [modulation of the substrate for measurement/evaluation], and each evaluation was performed.

The evaluation results are shown in Table 2.

Claims (19)

A circuit board comprising a circuit board having an insulating layer having a via hole having an opening diameter of 15 μm or less; an arithmetic mean roughness (Ra) of a surface of the insulating layer is 150 nm or less, and the insulating layer comprises an inorganic filler, perpendicular to In the cross section of the insulating layer in the direction of the surface of the insulating layer, when the average value of the maximum diameter of the inorganic filler contained in the region of the specific width is n ¹ (μm), the value of n ¹ × 1.27 (n ² ) is 0.2. Below μm. The circuit board of claim 1, wherein the Ra of the surface of the insulating layer is 100 nm or less. The circuit board of claim 1, wherein the opening diameter of the through hole is 12 μm or less. The circuit substrate according to claim 1, wherein in the cross section of the insulating layer in a direction perpendicular to the surface of the insulating layer, the resin area A ₁ and the inorganic filler area A _{2 in} the region of the specific width satisfy 0.1 ≦ A ₂ /(A ₁ + A ₂ ). The circuit board of claim 1, wherein the opening diameter D of the through hole and the minimum diameter _{Dmin of the} through hole satisfy 0.65 ≦ D _mim /D. The circuit substrate of claim 1, wherein the insulating layer comprises an inorganic filler which is surface-treated with a decane compound having an organic group having an aromatic ring. The circuit substrate of claim 1, wherein the inorganic filler is cerium oxide. A semiconductor device comprising the circuit substrate according to any one of claims 1 to 7. A method of manufacturing a circuit board, comprising the steps of: (A) laminating a film comprising a support and a resin composition layer provided on the support, and laminating the resin composition layer and the inner substrate a step of forming an insulating layer on the inner layer substrate; (B) thermally curing the resin composition layer in a state in which the support is attached; and (C) forming an opening diameter on the insulating layer by UV solid laser irradiation a step of a via hole of 15 μm or less; and the insulating layer formed in the step (B) comprises an inorganic filler, and the inorganic filler contained in the region of the specific width in the cross section of the insulating layer in a direction perpendicular to the surface of the insulating layer When the average value of the maximum diameter is n ¹ (μm), the value (n ² ) of n ¹ × 1.27 is 0.2 μm or less. A method of manufacturing a circuit board, comprising the steps of: (A) laminating a film comprising a support and a resin composition layer provided on the support, and laminating the resin composition layer and the inner substrate a step of forming an insulating layer on the inner layer substrate; (B) thermally curing the resin composition layer in a state in which the support is attached; and (C) forming an opening diameter on the insulating layer by UV solid laser irradiation The step of the through hole of 15 μm or less; and the resin composition layer of the adhesive film used in the step (A) contains 30% by mass or more of an inorganic filler having a BET specific surface area of 20 m ² /g or more. A method of manufacturing a circuit substrate, comprising the steps of: (A) a step of laminating a film comprising a support and a resin composition layer provided on the support, and laminating the resin composition layer on the inner substrate, and (B) attaching a step of forming a heat insulating layer of the resin composition layer to form an insulating layer; and (C) a step of forming a via hole having an opening diameter of 15 μm or less by a UV solid laser on the insulating layer; and the step (A) The resin composition layer of the adhesive film used therein contains 30% by mass or more of an inorganic filler having an average particle diameter of 0.2 μm or less. The method of claim 10, wherein the inorganic filler has a BET specific surface area of from 20 m ² /g to 500 m ² /g. The method of claim 11, wherein the inorganic filler has an average particle diameter of from 0.01 μm to 0.2 μm. The method of any one of clauses 9 to 11, wherein the support is removed prior to step (C). The method of any one of claims 9 to 11, wherein the surface of the insulating layer has an arithmetic mean roughness (Ra) of 150 nm or less. The method of any one of claims 9 to 11, wherein in the cross section of the insulating layer perpendicular to the surface of the insulating layer, the resin area A ₁ and the inorganic filler area A _{2 of the} specific width region satisfy 0.1 ≦ A ₂ /(A ₁ +A ₂ ). The method of any one of claims 9 to 11, wherein the opening diameter D of the through hole and the minimum diameter _{Dmin of the} through hole satisfy 0.65 ≦ D _mim /D. The method of any one of clauses 9 to 11, wherein the insulating layer package An inorganic filler containing a surface treatment of a decane compound containing an organic group having an aromatic ring. The method of any one of claims 9 to 11, wherein the inorganic filler is cerium oxide.