JP7140175B2 - Circuit board and its manufacturing method - Google Patents

Description

The present invention relates to a circuit board and its manufacturing method.

Circuit boards widely used in electronic devices are required to have finer wiring and higher density in order to reduce the size and increase the functionality of the electronic devices. As a method of manufacturing a circuit board, there is known a manufacturing method by a build-up method in which insulating layers and conductor layers are alternately stacked on an inner layer substrate to form a multilayer wiring structure.

In the method for manufacturing a circuit board by a build-up method, the insulating layer is formed by laminating a resin composition layer on an inner layer substrate using, for example, a resin sheet with a support containing a support and a resin composition layer, and forming a resin composition layer. is formed by thermally curing the Next, via holes are formed by drilling the formed insulating layer (see, for example, Patent Document 1).

It is known that one of the causes of the attenuation of electrical signals in circuit boards is the large surface roughness of the conductor layer, which includes wiring. In order to do so, it is desirable to make the surface roughness of the conductor layer smaller. Especially when high-frequency electric signals are used, the transmission loss is remarkable due to the large surface roughness of the conductor layer. It is desired to make the surface roughness of .

JP 2008-37957 A

In view of the above points, the present inventors made the surface roughness of the conductor layer smaller, and made the insulating layer of the circuit board thinner by irradiating the via hole with a laser. When a via hole with a smaller top diameter is formed, the insulating layer near the conductor layer is hollowed out due to the reflection and diffusion of the laser light on the surface of the conductor layer. The present inventors have found that, in the case of forming, notably, problems such as cracks occurring in the conductor layer and the insulating layer due to such gouged portions may occur over time due to use.

Accordingly, an object of the present invention is to provide a thin circuit board having a thinner insulating layer, in which the surface roughness of the conductor layer is reduced, and a via hole with a small diameter is formed in the insulating layer by laser irradiation. To provide a circuit board which hardly causes problems such as cracks over time due to use even if there is a crack.

As a result of intensive studies on the above-mentioned problem, the present inventors have found that the above-mentioned problem is to achieve an adhesion strength of 0.15 kgf/cm or more between the conductor layer and the insulating layer of the circuit board, the top diameter (Z) of the via hole, and the maximum size of the via hole. The relationship between the small diameter (Y) and the bottom diameter (X) of the via hole satisfies Y/Z = 0.7 to 0.99 and Y/X = 0.7 to 1 (Z>Y), thereby solving the above problem. can be solved, and the present invention has been completed.

That is, the present invention provides the following [1] to [20].
[1] A circuit board comprising a conductor layer, an insulating layer covering the conductor layer, and a via hole exposing a portion of the conductor layer from the insulating layer,
The arithmetic mean roughness of the surface of the conductor layer is 350 nm or less,
The via hole has a depth of 30 μm or less,
The top diameter (Z) of the via hole is 50 μm or less,
The relationship between the top diameter (Z) of the via hole, the minimum diameter (Y) of the via hole, and the bottom diameter (X) of the via hole is Y/Z = 0.7 to 0.99 and Y/X = 0.7. A circuit board that satisfies ~1 (Z>Y).
[2] The circuit board according to [1], wherein the position of the minimum diameter is positioned closer to the conductor layer than the depth of the via hole.
[3] The circuit board according to [1] or [2], wherein the surface of the conductor layer has an arithmetic mean roughness of 300 nm or less.
[4] The circuit board according to any one of [1] to [3], wherein the via hole has a depth of 25 μm or less.
[5] The circuit board according to any one of [1] to [4], wherein the adhesion strength between the conductor layer and the insulating layer is 0.15 kgf/cm or more.
[6] The circuit board according to any one of [1] to [4], wherein the adhesion strength between the conductor layer and the insulating layer is 0.2 kgf/cm or more.
[7] The circuit board according to any one of [1] to [6], wherein the via hole has a top diameter (Z) of 40 μm or less.
[8] The circuit board according to any one of [1] to [5], wherein the insulating layer is a cured resin composition.
[9] The circuit board according to any one of [1] to [8], wherein the via hole is formed by laser irradiation.
[10] A semiconductor device comprising the circuit board according to any one of [1] to [9].
[11] Step (A) A resin sheet with a plastic film support, which includes a plastic film support and a resin composition layer bonded to the plastic film support, is coated with a resin sheet having a surface arithmetic mean roughness of 350 nm or less. A step of bonding to the conductor layer of a wiring board provided with a conductor layer including a conductor pattern;
Step (B) Thermosetting the resin composition layer to form an insulating layer having a thickness of 30 µm or less on the conductor layer, and an adhesion strength between the insulating layer and the conductor layer of 0.15 kgf/cm or more. a step of forming an insulating layer which is
Step (C) A laser is irradiated from the plastic film support side to form a via hole having a top diameter (Z) of 50 μm or less in the insulating layer, wherein the top diameter (Z) of the via hole and the minimum diameter (Y ) and the bottom diameter (X) of the via hole satisfies Y/Z=0.7 to 0.99 and Y/X=0.7 to 1 (Z>Y); ,
Step (D) a step of performing desmear treatment;
Step (E): peeling the plastic film support from the insulating layer;
and (F) forming a further conductor layer on the insulating layer.
[12] According to [11], in the step (C), the via hole is formed such that the minimum diameter (Y) of the via hole is positioned closer to the conductor layer than the depth of the via hole. of the circuit board manufacturing method.
[13] The method for manufacturing a circuit board according to [11] or [12], wherein the desmear treatment in the step (D) is a wet desmear treatment.
[14] The step (F) is a step of forming a metal layer on the surface of the insulating layer by dry plating, and forming the conductor layer on the surface of the metal layer by wet plating. [11] to [13] ] The manufacturing method of the circuit board as described in any one of ].
[15] The method for producing a circuit board according to any one of [11] to [14], wherein the plastic film support is a release layer-attached plastic film support.
[16] The method for producing a circuit board according to any one of [11] to [15], wherein the resin composition layer contains an epoxy resin, a curing agent and an inorganic filler.
[17] The method for producing a circuit board according to [16], wherein the inorganic filler has an average particle size of 0.01 μm to 3 μm.
[18] The method for producing a circuit board according to [16], wherein the inorganic filler has an average particle size of 0.01 μm to 0.4 μm.
[19] The content of the inorganic filler in the resin composition layer is 40% by mass to 95% by mass when the non-volatile component in the resin composition layer is 100% by mass, [16]- [18] The method for manufacturing a circuit board according to any one of [18].
[20] The method for producing a circuit board according to any one of [16] to [19], wherein the inorganic filler is surface-treated with a surface treatment agent.

According to the present invention, cracks occur in the conductor layer and the insulation layer even when a small-diameter via hole is formed by laser irradiation in a circuit board provided with a thinner insulation layer covering a conductor layer with a small surface roughness. It is possible to provide a circuit board that is less likely to cause troubles over time due to use such as being used.

FIG. 1 is a schematic diagram showing a circuit board in plan view. FIG. 2 is a schematic diagram showing an end surface cut along the dashed-dotted line II-II in FIG. FIG. 3 is a schematic diagram for explaining a method of manufacturing a circuit board. FIG. 4 is a schematic diagram for explaining the method of manufacturing the circuit board.

Embodiments of the present invention will be described below with reference to the drawings. It should be noted that each drawing only schematically shows the shape, size and arrangement of constituent elements to the extent that the invention can be understood. The present invention is not limited by the following description, and each component can be changed as appropriate without departing from the gist of the present invention. In the drawings used for the following description, the same components are denoted by the same reference numerals, and redundant description may be omitted. Also, the configurations according to the embodiments of the present invention are not necessarily manufactured or used in the illustrated arrangement and shape.

[Circuit board provided with a conductor layer and an insulating layer covering the conductor layer]
A circuit board of the present invention comprises a conductor layer, an insulating layer covering the conductor layer, and a via hole exposing a part of the conductor layer from the insulating layer, wherein the arithmetic mean roughness of the surface of the conductor layer is is 350 nm or less, the depth of the via hole is 30 μm or less, the top diameter (Z) of the via hole is 50 μm or less, and the top diameter (Z) of the via hole, the minimum diameter (Y) of the via hole, and the bottom diameter ( X), it satisfies Y/Z=0.7 to 0.99 and Y/X=0.7 to 1 (Z>Y).

A configuration example of a circuit board will be described with reference to FIGS. 1 and 2. FIG.
FIG. 1 is a schematic diagram showing a circuit board in plan view. A region in which one via hole is provided on the circuit board is shown in an enlarged manner. FIG. 2 is a schematic diagram showing an end face cut along the dashed-dotted line II-II in FIG.

As shown in FIGS. 1 and 2, the circuit board 10 of this embodiment includes a wiring board (inner layer board) 20 . The wiring board 20 includes a substrate 22 and a conductor layer 24 provided on the main surface of the substrate 22 . An insulating layer 30 covering the conductor layer 24 and the main surface of the substrate 22 exposed from the conductor layer 24 is provided on the side where the conductor layer 24 is provided.

In the illustrated example, the conductor layer 24 and the insulating layer 30 are provided only on one main surface side of the substrate 22 . However, the configuration of the circuit board 10 according to the present embodiment is not limited to the illustrated example, and a configuration in which the conductor layer 24 and the insulating layer 30 are provided on both surface sides of the substrate 22, and the buildup layer is provided on both surface sides of the substrate 22. may be In this case, the wiring board 20 corresponds to a so-called inner layer circuit board.

In the following description, in order to simplify the description and facilitate understanding, a configuration in which the conductor layer 24 and the insulating layer 30 are provided only on one main surface side of the substrate 22 will be described.

Here, the surface roughness of the surface 24a of the conductor layer 24, that is, the average roughness (arithmetic mean roughness Ra) is 350 nm or less, preferably 300 nm or less. Therefore, the conductor layer 24 has a smaller surface roughness than the conventional conductor layer.

The thickness of the insulating layer 30 on the conductor layer 24 according to this embodiment is 30 μm or less, preferably 25 μm or less. Therefore, the insulating layer 30 is made thinner than the insulating layer of a conventional circuit board. That is, the circuit board 10 according to the present invention is characterized by being thinner as a whole.

Although the details of the method for manufacturing the insulating layer 30 will be described later, the insulating layer 30 is configured as a cured product of a resin composition. This cured product may be formed using a prepreg containing a resin composition and a sheet-like fiber base material.

The circuit board 10 is provided with one or more via holes 40 extending from the surface 30a of the insulating layer 30 to the surface 24a of the conductor layer 24 and exposing a portion thereof. In the present embodiment, the via hole 40 has a top diameter (Z), which is a diameter (opening diameter) of a substantially circular contour defined on the surface 30a of the insulating layer 30, of 50 μm or less, preferably 40 μm or less. In other words, the via hole 40 provided in the circuit board 10 of the present invention is provided as a via hole whose top diameter (Z), which is the maximum diameter when viewed in the thickness direction of the circuit board 10, is smaller than that of a conventional via hole.

Although the details of the method for forming the via hole 40 will be described later, the via hole 40 is preferably formed by irradiating a laser.

In the via hole 40 of the present embodiment, the relationship between the top diameter (Z), the minimum diameter (Y), and the bottom diameter (X) of the via hole is such that Y/Z is in the range of 0.7 to 0.99 (Y/Z = 0.7 to 0.99), and Y/X is in the range of 0.7 to 1 and Z>Y (Y/X = 0.7 to 1 (Z>Y)).

In the via hole 40 of the present embodiment, the depth d extends in the via hole 40 in a direction perpendicular to the surface 30a of the insulating layer 30 and/or the surface 24a of the conductor layer 24, with one end on the surface 24a and the other on the surface 24a. corresponds to the length of a line segment whose end is at a position equal to the height of the surface 30a. In the via hole 40, the minimum diameter (Y) is positioned closer to the conductor layer 24 when the depth d of the via hole 40 is used as a reference. In other words, the position of the minimum diameter (Y) is located at an equal distance from the position of the top diameter (Z) or the position of the bottom diameter (X) with respect to the depth d of the via hole 40, that is, the position of d/2. Near the conductor layer 24, that is, a position within a range of d/2 from the bottom portion 44 (0d) of the via hole 40, which is on the bottom diameter (X) side when the depth d of the via hole 40 is used as a reference, in other words, the top diameter ( It is positioned within the range of 0.5d to 1.0d from the Z) side.

Here, when the insulating layer 30 is derived from prepreg and contains a sheet-like fiber base material, the position where a part of the sheet-like fiber base material protrudes from the insulating layer 30 (side wall of the via hole 40) into the via hole 40. corresponds to the minimum diameter (Y).

Normally, the contour of the via hole 40 has an inverted truncated cone shape in which the top diameter (Z) is larger than the bottom diameter (X). A gouged portion 42 is formed in a region near the conductor layer 24 . The via hole 40 of this embodiment does not have the gouged portion 40, the minimum diameter (Y) and the bottom diameter (X) are the same, and the top diameter (Z) is larger than the bottom diameter (X). It may also have an inverted truncated conical shape.

The gouged portion 42 is formed by reflecting and diffusing the laser light used for forming the via hole 40 on the surface 24 a of the conductor layer 24 .

In the illustrated example, the gouged portion 42 has a shape of a truncated cone in which the diameter of the bottom surface is larger than the diameter of the top surface. However, the shape of the gouged portion 42 is not limited to this. The maximum diameter of the gouged portion 42 matches the bottom diameter (X) of the bottom portion 44 of the via hole 40 in the illustrated example.

In the circuit board 10, the gouged portion 42 preferably has a smaller outline diameter (diameters of the bottom and top surfaces of the truncated cone) and a smaller size. Therefore, it is more preferable that the contour of the via hole 40 has an inverted truncated cone shape.

The adhesion strength between the conductor layer 24 and the insulating layer 30 according to this embodiment is 0.15 kgf/cm or more, preferably 0.18 kgf/cm or more, more preferably 0.20 kgf/cm or more. By setting the adhesion strength between the conductor layer 24 and the insulating layer 30 to 0.15 kgf/cm or more, the shape of the contour of the via hole 40 satisfies the above relationship. This makes it possible to form the via hole 40 that does not have the gouged portion 42 or, even if it inevitably has the gouged portion 42 , has a smaller diameter and a smaller size of the gouged portion 42 . As a result, problems such as cracks in the insulating layer 30 and the conductor layer 24 due to use are less likely to occur, so the circuit board 10 has a long life and is highly reliable even when operated with high-frequency signals, for example. be able to.
On the other hand, when the adhesion strength between the conductor layer 24 and the insulating layer 30 is less than 0.15 kgf/cm, the shape of the contour of the via hole 40 cannot satisfy the above relationship, and the diameter and size of the gouged portion 42 cannot be satisfied. As a result, problems such as cracks in the insulating layer 30 and conductor layer 24 tend to occur over time, resulting in deterioration of characteristics over time and shortening of the life of the device. There is a risk.

In the illustrated example, a wiring layer 70 is provided on the surface 30 a of the insulating layer 30 . The wiring layer 70 is configured as a wiring pattern including a plurality of wirings. Here, the material of the wiring layer 70 is configured to fill the inside of the via hole 40, for example, as a filled via. electrically connected.

[Method for manufacturing circuit board]
In the method for manufacturing a circuit board according to the present embodiment, step (A) a resin sheet with a plastic film support, which includes a plastic film support and a resin composition layer bonded to the plastic film support, is coated on the surface. A step of bonding to the conductor layer of a wiring board provided with a conductor layer including a conductor pattern having an arithmetic mean roughness of 350 nm or less; a step of forming an insulating layer having a thickness of 30 μm or less and an adhesion strength between the insulating layer and the conductor layer of 0.15 kgf/cm or more; is a via hole having a top diameter (Z) of 50 μm or less in an insulating layer, and the relationship between the top diameter (Z) of the via hole, the minimum diameter (Y) of the via hole, and the bottom diameter (X) of the via hole is Y/Z = 0.7 to 0.99 and Y / X = 0.7 to 1 (Z>Y), step (D) performing desmear treatment, and step (E) plastic film support and step (F) forming a further conductive layer on the insulating layer.

A method for manufacturing a circuit board according to this embodiment will be described with reference to FIGS. 3 and 4 are schematic diagrams for explaining the manufacturing method of the circuit board shown in the same manner as in FIG.

<Step (A)>
In the step (A), a resin sheet with a plastic film support, which includes a plastic film support and a resin composition layer bonded to the plastic film support, is treated as a conductor having a surface arithmetic mean roughness of 350 nm or less. It is a step of bonding to the conductor layer of the wiring board provided with the conductor layer including the pattern.

As shown in FIG. 3, in step (A), a plastic film support-attached resin sheet 60 including a plastic film support 50 and a resin composition layer 30X bonded to the plastic film support 50 is prepared. Then, the resin composition layer 30X of the resin sheet 60 with a plastic film support is laminated so as to be bonded to the surface 24a of the conductor layer 24 of the wiring board 20. FIG.

Examples of the substrate 22 included in the wiring substrate 20 include glass epoxy substrates, metal substrates, polyester substrates, polyimide substrates, BT resin substrates, thermosetting polyphenylene ether substrates, and the like. A conductive layer (circuit) 24 including one or more patterned wiring patterns is formed on one side (or both sides) of the substrate 22, as already described.

The average surface roughness (Ra) of the surface 24a of the conductor layer 24 of the wiring board 20 is set to 350 nm or less, preferably 300 nm or less, from the viewpoint of reducing conductor loss of electric signals. The surface roughness of the conductor layer 24 can be adjusted by surface treatment of the conductor layer 24 .

An example of a preferable surface treatment of the surface 24a of the conductor layer 24 from the viewpoint of achieving both low roughness of the surface 24a of the conductor layer 24 and adhesion between the conductor layer 24 and the insulating layer 30 is an organic acid-based micro-etching agent. Roughening treatment using “Mec Etch Bond CZ8100” and “Mec Etch Bond CZ8101” (manufactured by MEC Co., Ltd.), tin-based treatment agent “Secure HFz” (manufactured by Atotech), “Flat Bond” (Mec Co. ), and surface treatment by tin-based treatment using ). Here, the tin-based treatment means forming a layer containing at least metallic tin or tin oxide on the surface 24 a of the conductor layer 24 . Specifically, the wiring substrate 20 is subjected to surface treatment such as displacement tin plating or immersion using a treatment liquid containing a tin salt, an organic and/or inorganic acid, a reducing agent, or the like.

Details of the configuration and manufacturing method of the plastic film support-attached resin sheet 60 used in step (A) will be described later.

The bonding (lamination) of the resin sheet 60 with the plastic film support and the wiring board 20 is performed, for example, by a thermocompression bonding process in which the resin sheet 60 with the plastic film support is thermally crimped to the wiring board 20 from the plastic film support 50 side. It can be carried out. As a member for thermocompression bonding the resin sheet 60 with a plastic film support to the wiring board 20 (hereinafter also referred to as a "thermocompression member"), for example, a heated metal plate (such as a SUS end plate) or a metal roll (SUS roll ) and the like. Instead of directly pressing the thermocompression member onto the resin sheet 60 with a plastic film support, heat-resistant rubber or the like is used as a material so that the resin composition layer 30X can sufficiently follow the unevenness of the surface of the circuit board 20. It is preferable to press through an elastic material that supports.

The temperature of the thermocompression bonding process is preferably in the range of 80.degree. C. to 160.degree. C., more preferably in the range of 90.degree. C. to 140.degree. The pressure in the thermocompression bonding process is preferably in the range of 0.098 MPa to 1.77 MPa, more preferably in the range of 0.29 MPa to 1.47 MPa. The processing time of the thermocompression bonding process is preferably in the range of 20 seconds to 400 seconds, more preferably in the range of 30 seconds to 300 seconds. Lamination is preferably carried out under reduced pressure conditions of 26.7 hPa or less.

Lamination can be done with a commercially available vacuum laminator. Examples of commercially available vacuum laminators include a vacuum pressurized laminator manufactured by Meiki Seisakusho Co., Ltd., a vacuum applicator manufactured by Nichigo-Morton Co., Ltd., and the like.

In the step (A), the resin sheet 60 with a plastic film support may be laminated on only one of both main surfaces of the wiring board 20, or may be laminated on both surfaces.

After the lamination, the laminated plastic film support-attached resin sheet 60 may be smoothed under normal pressure (atmospheric pressure), for example, by pressing a thermocompression member from the plastic film support 50 side. . Pressing conditions for the smoothing treatment may be the same conditions as those in the thermocompression bonding process. Smoothing treatment can be performed with a commercially available laminator. Note that the lamination and the smoothing treatment may be performed continuously using the above-mentioned commercially available vacuum laminator.

<Step (B)>
In the step (B), the resin composition layer 30X is thermally cured so that the insulating layer 30 having a thickness of 30 μm or less on the conductor layer 24 and the adhesion strength between the insulating layer 30 and the conductor layer 24 is 0.15 kgf. This is a step of forming the insulating layer 30 having a thickness of 1/cm or more.

In step (B), the insulating layer 30 is formed by thermosetting the resin composition layer 30X. The plastic film support 50 may be peeled off from the resin composition layer 30X before thermal curing. After the insulating layer 30 is formed, such as when the surface of the plastic film support 50 is subjected to the release treatment and the resin composition layer 30X is in contact with the surface subjected to the release treatment, the surface 30a of the insulating layer 30 can be easily removed. If the plastic film support 50 is peelable, the insulating layer 30 can be formed by thermally curing the plastic film support 50 without peeling it off.

In the step (B), the thermosetting conditions for the resin composition layer 30X are not particularly limited, but for example, the curing temperature is in the range of 120°C to 240°C (preferably 150°C to 210°C, more preferably 160°C). to 200° C.), and the curing time can be in the range of 5 minutes to 90 minutes (preferably 10 minutes to 75 minutes, more preferably 15 minutes to 60 minutes). Moreover, the pressure during thermosetting is not particularly limited, and may be normal pressure, increased pressure, or reduced pressure.

Before thermally curing the resin composition layer 30X, a preliminary heat treatment may be performed to heat the resin composition layer 30X at a temperature lower than the curing temperature. For example, prior to thermosetting the resin composition layer 30X, the resin composition layer 30X is heated for 5 minutes or more (preferably 5 minutes 150 minutes), a preliminary heat treatment may be performed.

The thickness of the insulating layer 30 formed by thermosetting the resin composition layer 30X on the conductor layer 24, that is, the depth d of the via hole 40 is set to 30 μm or less from the viewpoint of making the circuit board 10 thin. From the viewpoint of thinning, the thickness of the insulating layer 30 on the conductor layer 24 is preferably 25 μm or less. Although the lower limit of the thickness of the insulating layer 30 on the conductor layer 24 is not particularly limited, it is usually 3 μm or more. The thickness t of the insulating layer 30 and the thickness (d) of the insulating layer 30 on the conductor layer 24 are appropriately adjusted by adjusting the thickness of the resin composition layer 30X of the resin sheet 60 with a plastic film support. be able to.

The adhesion strength between the insulating layer 30 formed by thermosetting the resin composition layer 30X and the conductor layer 24 is 0.15 kgf/cm or more. The adhesion strength between the insulating layer 30 and the conductor layer 24 is preferably 0.2 kgf/cm or more. When the adhesion strength is less than 0.15 kgf/cm, when the via hole 40 is formed by laser irradiation, the laser light is reflected and diffused on the surface 24a of the conductor layer 24 located on the bottom 44 side of the via hole 40, causing the insulating layer 30 to be damaged. and the conductor layer 24 may be peeled off due to the heat of the laser energy.

The adhesion strength between the formed insulating layer 30 and the conductor layer 24 depends on the components of the resin composition for forming the insulating layer 30 and the curing conditions when forming the insulating layer 30 (the glass of the resin constituting the insulating layer 30 It can be adjusted by the transition temperature (Tg)), the surface roughness of the surface 24a of the conductor layer 24, the treatment for improving the adhesion of the surface 24a of the conductor layer 24, and the like.

From the viewpoint of adjusting the adhesion strength between the insulating layer 30 and the conductor layer 24, for example, in the components of the resin composition, a resin composition containing an epoxy resin as a main component is used, and a phenol-based curing agent and an active ester-based curing agent are used as the curing agent. It is preferred to use agents. As the curing conditions for such a resin composition, it is preferable to cure the resin composition under such curing conditions that the Tg of the cured product of the resin composition is 100° C. or higher. When an epoxy resin having a triazine structure or a phenolic curing agent having a triazine structure is used as the material of the resin composition, the adhesion strength between the insulating layer 30 and the conductor layer 24 tends to be improved. On the other hand, when an alicyclic epoxy resin is used as the epoxy resin, the adhesion strength between the insulating layer 30 and the conductor layer 24 tends to decrease. Strength tends to decrease.

As the surface roughness of the surface 24a of the conductor layer 24 increases, the adhesion strength between the insulating layer 30 and the conductor layer 24 tends to improve due to the so-called anchor effect. However, signal transmission loss tends to increase as the surface roughness of the surface 24a of the conductor layer 24 increases. Therefore, in the circuit board 10 according to this embodiment, the surface roughness of the surface 24a of the conductor layer 24 is set to 350 μm or less. Further, the adhesion strength between the insulating layer 30 and the conductor layer 24 can be improved by performing a surface treatment for improving the adhesion strength on the surface 24 a of the conductor layer 24 .

Examples of the surface treatment that can improve the adhesion strength while reducing the roughness of the surface 24a of the conductor layer 24 include "Mec Etch Bond CZ8100" and "Mec Etch Bond CZ8101" (Mec Etch Bond CZ8101), which are organic acid-based micro-etching agents. (manufactured by Co., Ltd.). Examples of surface treatment for improving the adhesion strength of the surface 24a of the conductor layer 24 include surface treatment with a tin-based treatment agent "Secure HFz" (manufactured by Atotech). Further, after performing the roughening treatment and the treatment for improving the adhesion strength, the adhesion strength may be improved by further performing the treatment using a coupling agent. Examples of coupling agents that can be used include silane coupling agents, titanate coupling agents, aluminate coupling agents, and the like. Among them, silane coupling agents are preferred, and examples of silane coupling agents include aminosilane coupling agents, epoxysilane coupling agents, styrene silane coupling agents, and the like. Examples of such surface treatment include surface treatment with “Flat Bond” (manufactured by MEC Co., Ltd.), which includes treatment with a tin-based treatment agent and treatment with a coupling agent.

In the method of manufacturing the circuit board 10 according to this embodiment, the via holes 40 are formed in the insulating layer 30 . As already explained, the top diameter (Z) of the via hole 40 to be formed is 50 μm or less, and the top diameter (Z) of the via hole 40, the minimum diameter (Y) of the via hole 40, and the bottom diameter (X) of the via hole 40 are equal to each other. The relationship is Y/Z=0.7-0.99 and Y/X=0.7-1 (Z>Y). At this time, the position of the minimum diameter of the via hole 40 is located near the conductor layer 24 when the depth d of the via hole 40 is used as a reference.

<Step (C)>
The circuit board 10 according to the present embodiment can be manufactured, for example, by performing the step (C) after performing the steps (A) and (B).
In the step (C), a laser is irradiated from the plastic film support 50 side, that is, from above the plastic film support 50 to form a via hole 40 having a top diameter (Z) of 50 μm or less in the insulating layer 30 . The relationship between the top diameter (Z) of the via hole 40, the minimum diameter (Y) of the via hole 40, and the bottom diameter (X) of the via hole 40 is Y/Z = 0.7 to 0.99 and Y/X = 0.7 This is the step of forming the via hole 40 that satisfies ˜1 (Z>Y).

As shown in FIG. 4, in step (C), a via hole 40 having a top diameter (Z) of 50 μm or less is formed in the insulating layer 30 by laser irradiation. When the plastic film support 50 exists in a state of being bonded to the insulating layer 30 as in the illustrated example, the plastic film support 50 may be irradiated with a laser from above the plastic film support 50. The plastic film support 50 may be peeled off and the insulating layer 30 may be directly irradiated with the laser. From the viewpoint of forming the via holes 40 with high accuracy, it is preferable to form the via holes 40 by irradiating the laser from above without peeling off the plastic film support 50 .

The top diameter (Z) of the via hole 40 formed in step (C) is preferably less than 50 μm, more preferably 40 μm or less, from the viewpoint of further increasing the density of the wiring pattern provided on the circuit board 10. , is more preferably 35 μm or less, and particularly preferably 30 μm or less.

The number of via holes 40 formed in step (C) is not particularly limited, and may be any desired number depending on the design of the circuit board 10 . The top diameters (Z) of the plurality of via holes 40 to be formed may be the same or different. It should be noted that the top diameter (Z) of all the via holes 40 formed in step (C) need not be 50 μm or less. A via hole 40 having a top diameter (Z) exceeding 50 μm may also be formed depending on the design of the circuit board 10 .

The relationship between the top diameter (Z) of the via hole 40, the minimum diameter (Y) of the via hole 40, and the bottom diameter (X) of the via hole 40 formed by the manufacturing method of the circuit board 10 according to the present embodiment is Y/Z= 0.7 to 0.99 and Y/X=0.7 to 1 (Z>Y). The position of the minimum diameter of the via hole 40 is positioned near the conductor layer 24 when the depth d of the via hole 40 is used as a reference.

Examples of laser light sources that can be used for laser irradiation in step (C) include carbon dioxide laser, YAG laser, UV-YAG laser, YVO ₄ laser, YLF laser, and excimer laser. Any suitable laser light source can be used depending on the light absorption properties of the plastic film support 50 and the insulating layer 30 .

The laser irradiation conditions are not particularly limited as long as a small via hole 40 having a top diameter (Z) as described above can be formed. It may be determined appropriately according to the thickness, type, etc. of the insulating layer 30 . Irradiation conditions when a carbon dioxide gas laser is used as a laser light source will be described below. When a carbon dioxide laser is used as the laser light source, laser light with a wavelength of 9.3 μm to 10.6 μm is generally used. The number of shots varies depending on the depth d and the top diameter (Z) of the via hole 40 to be formed, but is usually selected within the range of 1 shot to 10 shots. From the viewpoint of increasing the processing speed and improving the productivity of circuit boards, the number of shots is preferably as small as possible, preferably in the range of 1 shot to 5 shots, more preferably in the range of 1 shot to 3 shots. . When the number of shots is two or more, the laser may be applied in either burst mode or cycle mode. The energy of the laser is preferably 0.2 mJ or more, more preferably 0.3 mJ or more, still more preferably 0, although it depends on the number of shots, the depth d of the via hole 40, the presence or absence of the plastic film support 50, and its thickness. .4 mJ or more. The upper limit of laser energy is preferably 20 mJ or less, more preferably 15 mJ or less, and still more preferably 10 mJ or less.

Step (C) can be carried out using a commercially available laser device. Examples of commercially available laser devices include "LC-2E21B/1C" (carbon dioxide laser device) manufactured by Hitachi Via Mechanics Co., Ltd., "605GTWIII(-P)" (carbon dioxide laser device) manufactured by Mitsubishi Electric Corporation, ESI "MODEL5330xi", "MODEL5335" (UV-YAG laser device) and the like.

Resin residue (smear) generally adheres to the inside of via hole 40 formed in step (C) (particularly to the bottom of via hole 40). Since such smears cause electrical connection failures between layers, a desmear process (step (D)) for removing smears is usually performed after the formation of the via holes 40 .

<Step (D)>
A process (D) is a process of performing a desmear process.
In the step (D), the desmear treatment is not particularly limited, and any suitable conventionally known desmear treatment can be performed. Desmearing may be performed, for example, by dry desmearing, wet desmearing, or a combination thereof. When the via hole 40 is formed with a laser from above the plastic film support 50, the plastic film support 50 is bonded to the insulating layer 30, but the desmear treatment is performed after the plastic film support 50 is peeled off. Alternatively, it may be performed while being bonded to the insulating layer 30 .

An example of dry desmear treatment is desmear treatment using plasma. Desmearing using plasma can be performed using a commercially available plasma desmearing device. Among commercially available plasma desmear treatment apparatuses, suitable examples for use in manufacturing the circuit board of the present invention include a microwave plasma apparatus manufactured by Nissin Co., Ltd., an atmospheric pressure plasma etching apparatus manufactured by Sekisui Chemical Co., Ltd., and the like. be done.

Examples of dry desmearing also include dry sandblasting, in which an abrasive material may be sprayed from a nozzle to abrade an object being treated. Dry sandblasting can be carried out using commercially available dry sandblasting equipment. When a water-soluble abrasive is used as the abrasive, smears can be effectively removed by washing with water after dry sandblasting without the abrasive remaining inside the via hole 40. .

Examples of wet desmear treatment include desmear treatment using an oxidizing agent solution. When the desmear treatment is performed using the oxidant solution, it is preferable to perform the swelling treatment with the swelling liquid, the oxidation treatment with the oxidant solution, and the neutralization treatment with the neutralization solution in this order. Examples of the swelling liquid include "Swelling Dip Securigans P" and "Swelling Dip Securigans SBU" manufactured by Atotech Japan. The swelling treatment is preferably performed by immersing the substrate having the via holes 40 formed therein in a swelling liquid heated to 60° C. to 80° C. for 5 to 10 minutes. As the oxidizing agent solution, an aqueous alkaline permanganate solution is preferable. For example, a solution obtained by dissolving potassium permanganate or sodium permanganate in an aqueous solution of sodium hydroxide can be mentioned. The oxidation treatment with the oxidizing agent solution is preferably carried out by immersing the substrate after the swelling treatment in the oxidizing agent solution heated to 60° C. to 80° C. for 10 minutes to 30 minutes. Examples of commercially available alkaline permanganate aqueous solutions include "Concentrate Compact CP" and "Dosing Solution Security P" manufactured by Atotech Japan. The neutralization treatment with the neutralizing solution is preferably carried out by immersing the substrate after the oxidation treatment in the neutralizing solution at 30° C. to 50° C. for 3 to 10 minutes. As the neutralizing liquid, an acidic aqueous solution is preferable, and as a commercial product, for example, "Reduction Solution Securigant P" manufactured by Atotech Japan Co., Ltd. can be mentioned.

As the wet desmearing treatment, a wet sandblasting treatment that can polish the object to be treated by spraying an abrasive and a dispersion medium from a nozzle may also be used. Wet sandblasting can be carried out using commercially available wet sandblasting equipment.

When the dry desmear treatment and the wet desmear treatment are performed in combination, the dry desmear treatment may be performed first, or the wet desmear treatment may be performed first.

From the viewpoint that the effects of the present invention can be enjoyed more, the desmear treatment in the step (D) is preferably a wet desmear treatment.

<Step (E)>
Step (E) is a step of peeling off the plastic film support 50 from the insulating layer 30 .
The peeling method of the plastic film support 50 is not particularly limited, and any suitable conventionally known method can be used. The plastic film support 50 can be mechanically peeled off by an automatic peeling device.

<Step (F)>
Step (F) is a step of forming the wiring layer 70 on the insulating layer 30 .
After the desmearing process, a wiring layer 70 (build-up wiring layer) is formed on the surface 30 a of the insulating layer 30 .
A conductor material that can be used for the wiring layer 70 is not particularly limited. In a preferred embodiment, the wiring layer 70 is at least one selected from the group consisting of gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin and indium. metal as material. The wiring layer 70 may be a single metal layer or an alloy layer. As the alloy layer, for example, an alloy of two or more metals selected from the above group (eg, nickel-chromium alloy, copper - Nickel alloys and copper-titanium alloys). The wiring layer 70 is, among others, a single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver or copper, or An alloy layer of nickel-chromium alloy, copper-nickel alloy, copper-titanium alloy is preferable, and a single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver or copper, or nickel-chromium alloy It is more preferable that the layer is an alloy layer of, and more preferable that it is a single metal layer of copper.

The wiring layer 70 may have a single layer structure or a multi-layer structure in which two or more single metal layers or alloy layers made of different kinds of metals or alloys are laminated. When the wiring layer 70 has a multi-layer structure, the layer bonded to the insulating layer 30 is preferably a single metal layer of chromium, zinc or titanium, or an alloy layer of a nickel-chromium alloy.

The thickness of the wiring layer 70 is usually 35 μm or less, preferably 30 μm or less, more preferably 25 μm or less, depending on the desired circuit board design. Although the lower limit of the thickness of the wiring layer 70 is not particularly limited, it is usually 3 μm or more, preferably 5 μm or more.

In a preferred embodiment, step (F) comprises
forming a metal layer on the surface of the insulating layer 30 by dry plating;
forming a wiring layer 70 on the surface of the metal layer by wet plating (hereinafter referred to as "step (F-1)").

In step (F-1), first, a metal layer is formed on surface 30a of insulating layer 30 by dry plating.

Examples of dry plating include physical vapor deposition (PVD) methods such as vapor deposition, sputtering, ion plating, and laser ablation, and chemical vapor deposition (CVD) methods such as thermal CVD and plasma CVD. Sputtering is preferred. The metal layer may be formed by combining two of these dry plating methods.

The thickness of the metal layer to be formed is not particularly limited, but is preferably 5 nm to 2 μm, more preferably 10 nm to 1 μm, still more preferably 20 nm to 500 nm. Note that the metal layer may have a single-layer structure or a multi-layer structure. When the metal layer has a multi-layer structure, the thickness of the entire metal layer is preferably within the above range.

In step (F-1), after forming the metal layer, the wiring layer 70 is formed on the surface of the metal layer by wet plating.

Using the metal layer as a plating seed layer, the wiring layer 70 including a wiring pattern having a desired pattern can be formed by wet plating in a semi-additive method. Specifically, a mask pattern is formed on the plating seed layer (metal layer) to expose a portion of the plating seed layer corresponding to a desired wiring pattern. After forming the wiring layer 70 on the exposed plating seed layer by electroplating, the mask pattern is removed. After that, the unnecessary plating seed layer is removed by etching or the like, and the wiring layer 70 including the desired wiring pattern can be formed.

In forming the wiring layer 70, the surface 30a of the insulating layer 30 may be roughened. In this case, the step (F-1) is
roughening the surface 30a of the insulating layer 30;
forming a metal layer on the surface 30a of the insulating layer 30 by dry plating;
and forming a wiring layer 70 on the surface of the metal layer by wet plating.

Examples of roughening treatment include dry roughening treatment and wet roughening treatment, and roughening treatment may be performed by combining these.

The dry roughening treatment can be performed in the same manner as the already described dry desmear treatment. Also, the wet roughening treatment can be performed in the same manner as the already described wet desmear treatment. When the dry roughening treatment and the wet roughening treatment are performed in combination, the dry roughening treatment may be performed first, or the wet roughening treatment may be performed first. The purpose of the roughening treatment is to roughen the exposed surface 30 a of the insulating layer 30 , but it is also effective in removing smears inside the via holes 40 . Therefore, smears can be prevented from remaining even when the step (D) is carried out under mild conditions.

In another preferred embodiment, step (F) comprises
roughening the surface 30a of the insulating layer 30;
forming the wiring layer 70 on the surface 30a of the insulating layer 30 by wet plating (hereinafter referred to as "step (F-2)").

Details of the roughening treatment are as described above.

In step (F-2), after surface 30a of insulating layer 30 is roughened, wiring layer 70 is formed on surface 30a of insulating layer 30 by wet plating.

For example, the wiring layer 70 including a wiring pattern having a desired pattern can be formed by a semi-additive method by combining electroless plating and electrolytic plating.

The surface roughness of the surface 30a of the insulating layer 30 to be obtained can be made lower, which contributes to finer wiring and higher density. is preferred.

The circuit board 10 is manufactured through the above steps. Although an example in which only one insulating layer 30 is formed has been described here, one or more layers of so-called build-up layers, including a further insulating layer and a wiring layer provided on this insulating layer, may be further formed.

<Resin sheet with plastic film support>
The resin sheet 60 with a plastic film support used in the manufacturing method of the present invention will be described.

The plastic film support-attached resin sheet 60 used in the manufacturing method of the present invention includes a plastic film support 50 and a resin composition layer 30X bonded to the plastic film support 50 . These will be described below.

(Plastic film support)
Examples of materials for the plastic film support 50 include polyesters such as polyethylene terephthalate (referred to as "PET") and polyethylene naphthalate (referred to as "PEN"), polycarbonate (referred to as "PC"), and polymethyl methacrylate (referred to as "PC"). PMMA"), cyclic polyolefin, triacetyl cellulose (referred to as "TAC"), polyether sulfide (referred to as "PES"), polyether ketone, and polyimide. Among them, PET, PEN and polyimide are preferred, and PET and PEN are more preferred. In one preferred embodiment, the plastic film support 50 is a PET film support or a PEN film support.

When manufacturing the circuit board 10 of the present invention, it is preferable to irradiate the laser from above the plastic film support 50 side to form the small-diameter via holes 40 in the insulating layer 30 . From the viewpoint of smoothly forming the via hole 40 by laser irradiation, the plastic film support 50 is preferably capable of absorbing laser energy. For example, since a PEN film support has ultraviolet (UV) absorption properties, it can be suitably used as the plastic film support 50 for forming the via holes 40 by UV irradiation.

The laser energy absorptivity may be imparted or increased by incorporating a laser energy absorptive component into the plastic film support 50 . The laser energy absorbing component is not particularly limited as long as it can absorb the laser used for forming the via hole 40, and examples thereof include carbon powder, metal compound powder, metal powder and black dye. The laser energy absorptive components may be used singly or in combination of two or more.

Carbon powders include, for example, furnace black, channel black, acetylene black, thermal black, anthracene black, and other carbon black powders, graphite powders, and powders of mixtures thereof. Examples of the metal compound powder include titania such as titanium oxide, magnesia such as magnesium oxide, iron oxide such as iron oxide, nickel oxide such as nickel oxide, manganese dioxide, zinc oxide such as zinc oxide, and dioxide. Silicon, aluminum oxide, rare earth oxides, cobalt oxides such as cobalt oxide, tin oxides such as tin oxide, tungsten oxides such as tungsten oxide, silicon carbide, tungsten carbide, boron nitride, silicon nitride, titanium nitride, aluminum nitride , barium sulfate, rare earth oxysulfides, and mixtures thereof. Examples of metal powders include silver, aluminum, bismuth, cobalt, copper, iron, magnesium, manganese, molybdenum, nickel, palladium, antimony, silicon, tin, titanium, vanadium, tungsten, zinc, and alloys or mixtures thereof. Powder etc. are mentioned. Examples of black dyes include azo (monoazo, disazo, etc.) dyes, azo-methine dyes, anthraquinone dyes, quinoline dyes, ketoneimine dyes, fluorone dyes, nitro dyes, xanthene dyes, acenaphthene dyes, quinophthalone dyes, aminoketone dyes, and methine dyes. , perylene dyes, coumarin dyes, perinone dyes, triphenyl dyes, triallylmethane dyes, phthalocyanine dyes, incrophenol dyes, azine dyes, and mixtures thereof. A black dye that is soluble in a solvent is preferably used as the black dye in order to improve dispersibility. Among them, as the laser energy absorptive component, carbon powder is preferable, and carbon black is particularly preferable, from the viewpoints of conversion efficiency of laser energy into heat and versatility. The upper limit of the average particle size of the laser energy absorbing component is preferably 20 μm or less, more preferably 10 μm or less, from the viewpoint of efficiently absorbing laser energy. From the viewpoint of dispersibility, the lower limit of the average particle diameter is preferably 0.001 μm or more, more preferably 0.002 μm. The "average particle size" as used herein can be measured by a particle size distribution analyzer and the BET method. The BET method is a method in which molecules having a known adsorption occupation area are adsorbed on the surfaces of powder particles at the temperature of liquid nitrogen, and the specific surface area of the sample is determined from the amount. Furthermore, the average particle size can be calculated from the specific surface area determined by the BET method.

The content of the laser energy absorptive component is preferably 0.01% by mass or more from the viewpoint of smooth formation of via holes 40 when all components constituting the plastic film support 50 are taken as 100% by mass. It is preferably 0.03% by mass, more preferably 0.05% by mass or more. The upper limit of the content is preferably 40% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less, from the viewpoint of obtaining a plastic film support 50 having good flexibility. is. In addition, the laser energy absorbing component may be contained in the release layer described later.

Commercial products of the plastic film support 50 include, for example, "Lumirror R56", "Lumirror R80" and "Lumirror T6AM" (PET film) manufactured by Toray Industries, Inc., and "G2LA" manufactured by Teijin DuPont Films Limited ( PET film), "Teonex Q83" (PEN film), "Upilex-S" (polyimide film) manufactured by Ube Industries, Ltd., "Apical AH" manufactured by Kaneka Corporation, "Apical NPI" (polyimide film), etc. is mentioned.

The plastic film support 50 may be subjected to matte treatment or corona treatment on the surface to be bonded to the resin composition layer 30X.

In the step (B), since the adhesion strength between the insulating layer 30 and the plastic film support 50 can be easily adjusted within a desired range, the plastic film support 50 has a surface that is to be bonded to the resin composition layer 30X. A release layered plastic film support 50 having a mold layer is preferred. Release agents that can be used in the release layer include, for example, non-silicone release agents such as alkyd resins, melamine resins, olefin resins and urethane resins, and silicone release agents. The releasing agent may be used singly or in combination of two or more. Among them, when the resin sheet 60 with a plastic film support is produced, the release layer exhibits high wettability to the resin varnish, and the contact state with the resin composition layer 30X tends to be uniform over the entire surface. It is preferably a release layer containing a release agent, and more preferably a release layer containing an alkyd resin and/or an olefin resin.

The release agent is classified into a so-called light release type release agent with low peel strength, a so-called heavy release type release agent with high peel strength, and a light release type release agent depending on the type of its constituent components. It can be classified as a so-called medium release type release agent that exhibits a peel strength intermediate between that of a heavy release type release agent and a heavy release type release agent. Peelable release agents are preferred. Although it varies depending on the composition of the resin composition layer 30X for forming the insulating layer 30, the lamination conditions in the step (A), the thermosetting conditions in the step (B), etc., the initial adhesion strength is preferably 100 (mN/20 mm) or more, more preferably 300 (mN/20 mm) or more, still more preferably 500 (mN/20 mm) or more, 700 (mN/20 mm) or more, 800 (mN /20 mm) or higher, 900 (mN/20 mm) or higher, or 1000 (mN/20 mm) or higher. The upper limit of the initial adhesion strength is not particularly limited, but from the viewpoint of smoothly peeling the plastic film support 50 in the step (E), it is usually 8000 (mN/20 mm) or less, and 7500 (mN/20 mm) or less. and so on. The initial adhesion strength was determined by applying an acrylic adhesive tape (“31B” manufactured by Nitto Denko Corporation) to the surface treated with a release agent using a 2 kg roller and leaving it for 30 minutes. is peeled off and gripped with a gripper, and the load (mN/20 mm) when peeled off under the conditions of room temperature, speed of 30 cm/min, and peel angle of 180° can be measured. The measurement may be performed using a tensile tester such as "AC-50C-SL" manufactured by TSE Co., Ltd., for example.

Examples of commercially available releasing agents include "X" (silicone-containing alkyd resin-based releasing agent; 490 mN/20 mm) and "SK-1" (silicone-containing alkyd resin-based releasing agent; 1250mN/20mm), "AL-5" (non-silicone/alkyd resin release agent; 1480mN/20mm), "6050" (non-silicone/alkyd resin release agent; 2400mN/20mm), "6051" (non- silicone/alkyd resin type release agent; 2800 mN/20 mm), "6052" (non-silicone/alkyd resin type release agent; 4000 mN/20 mm), etc. (values of initial adhesion strength are shown in parentheses). Commercial release agents include "AL-7" (non-silicone/alkyd resin release agent; heavy release type) manufactured by Lintec Corporation, and "NSP-4" (manufactured by Fujimori Industry Co., Ltd.). non-silicone/alkyd resin release agent; heavy release type), and the like.

Although the thickness of the plastic film support 50 is not particularly limited, it is preferably in the range of 10 μm to 100 μm, more preferably in the range of 15 μm to 75 μm. In particular, the range of 20 μm to 50 μm is more preferable from the viewpoint of facilitating the formation of small-diameter vias. When the plastic film support 50 is a release layer-attached plastic film support 50, the thickness of the entire release layer-attached plastic film support 50 is preferably within the above range.

(Resin composition layer)
The resin composition used for the resin composition layer 30X is not particularly limited as long as the cured product thereof has sufficient hardness and insulating properties and provides desired adhesion strength to the plastic film support 50 . As the resin composition, for example, a resin composition containing an epoxy resin, a curing agent and an inorganic filler can be used. The resin composition used for the resin composition layer 30X may further contain additives such as a thermoplastic resin, a curing accelerator, a flame retardant, and an organic filler, if necessary. The components of the resin composition are described below.

-Epoxy resin-
Examples of epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AF type epoxy resin, dicyclopentadiene type epoxy resin, trisphenol type epoxy resin, naphthol novolac type epoxy resin, Phenol novolak type epoxy resin, tert-butyl-catechol type epoxy resin, naphthalene type epoxy resin, naphthol type epoxy resin, anthracene type epoxy resin, glycidylamine type epoxy resin, glycidyl ester type epoxy resin, cresol novolac type epoxy resin, biphenyl type epoxy resin Epoxy resins, linear aliphatic epoxy resins, epoxy resins having a butadiene structure, alicyclic epoxy resins, heterocyclic epoxy resins, spiro ring-containing epoxy resins, cyclohexanedimethanol-type epoxy resins, naphthylene ether-type epoxy resins and tri- Examples include methylol type epoxy resins. The exemplified epoxy resins may be used singly 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 of the epoxy resin is 100 mass %, at least 50 mass % or more of the epoxy resin preferably has two or more epoxy groups in one molecule. Among them, an epoxy resin that has two or more epoxy groups in one molecule and is liquid at a temperature of 20°C (hereinafter referred to as "liquid epoxy resin") and one that has three or more epoxy groups in one molecule. , and an epoxy resin that is solid at a temperature of 20° C. (hereinafter referred to as “solid epoxy resin”). By using both a liquid epoxy resin and a solid epoxy resin as epoxy resins, a resin composition having excellent flexibility can be obtained. Moreover, the breaking strength of the cured product of the resin composition is also improved.

As liquid epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, naphthalene type epoxy resins, glycidyl ester type epoxy resins, phenol novolac type epoxy resins, and epoxy resins having a butadiene structure are preferred, and bisphenol A type epoxy resins are preferred. , bisphenol F type epoxy resin, and naphthalene type epoxy resin are more preferred. Specific examples of liquid epoxy resins include "HP4032", "HP4032H", "HP4032D", and "HP4032SS" (naphthalene-type epoxy resins) manufactured by DIC Corporation, and "jER828EL" (bisphenol A manufactured by Mitsubishi Chemical Corporation). type epoxy resin), "jER807" (bisphenol F type epoxy resin), "jER152" (phenol novolac type epoxy resin), "ZX1059" manufactured by Nippon Steel & Sumikin Chemical Co., Ltd. (bisphenol A type epoxy resin and bisphenol F type epoxy resin ), "EX-721" (glycidyl ester type epoxy resin) manufactured by Nagase ChemteX Co., Ltd., "PB-3600" (epoxy resin having a butadiene structure) manufactured by Daicel Chemical Industries, Ltd. be done. These may be used individually by 1 type, and may be used in combination of 2 or more type.

Solid epoxy resins include naphthalene type tetrafunctional epoxy resin, cresol novolak type epoxy resin, dicyclopentadiene type epoxy resin, trisphenol type epoxy resin, naphthol type epoxy resin, biphenyl type epoxy resin, naphthylene ether type epoxy resin, Anthracene-type epoxy resins are preferred, and naphthalene-type tetrafunctional epoxy resins, naphthol-type epoxy resins, and biphenyl-type epoxy resins are more preferred. Specific examples of solid epoxy resins include "HP-4700" and "HP-4710" (naphthalene-type tetrafunctional epoxy resin), "N-690" (cresol novolac-type epoxy resin) manufactured by DIC Corporation, " N-695" (cresol novolak type epoxy resin), "HP-7200" (dicyclopentadiene type epoxy resin), "EXA7311", "EXA7311-G3", "EXA7311-G4", "EXA7311-G4S", "HP6000 ” (naphthylene ether type epoxy resin), Nippon Kayaku Co., Ltd. “EPPN-502H” (trisphenol type epoxy resin), “NC7000L” (naphthol novolac type epoxy resin), “NC3000H”, “NC3000”, "NC3000L", "NC3100" (biphenyl type epoxy resin), "ESN475V" (naphthol type epoxy resin) manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., "ESN485V" (naphthol novolac type epoxy resin), manufactured by Mitsubishi Chemical Corporation "YX4000H", "YL6121" (biphenyl-type epoxy resin), "YX4000HK" (bixylenol-type epoxy resin), "YX8800" (anthracene-type epoxy resin), "PG-100" manufactured by Osaka Gas Chemicals Co., Ltd., " CG-500” and “YL7800” (fluorene type epoxy resin) manufactured by Mitsubishi Chemical Corporation.

When a liquid epoxy resin and a solid epoxy resin are used together as the epoxy resin, the ratio by mass (liquid epoxy resin: solid epoxy resin) is in the range of 1:0.1 to 1:6. preferably. By setting the ratio between the liquid epoxy resin and the solid epoxy resin in such a range, i) moderate adhesiveness is provided when used in the form of a resin sheet with a plastic film support, and ii) a plastic film support. When used in the form of a resin sheet with a coating, sufficient flexibility can be obtained to improve handleability, and iii) a cured product having sufficient breaking strength can be obtained. From the viewpoint of the above effects i) to iii), the ratio of the liquid epoxy resin to the solid epoxy resin (liquid epoxy resin: solid epoxy resin) is 1:0.3 to 1:5 by mass. A range is more preferred, and a range of 1:0.6 to 1:4.5 is even more preferred.

The content of the epoxy resin in the resin composition is preferably 3% to 40% by mass, more preferably 5% to 35% by mass, still more preferably 10% to 30% by mass.

In this specification, unless otherwise specified, the content of each component in the resin composition is a value when the non-volatile component in the resin composition is 100% by mass.

The weight average molecular weight of the epoxy resin is preferably 100-5000, more preferably 250-3000, still more preferably 400-1500. Here, the weight average molecular weight of the epoxy resin is the polystyrene equivalent weight average molecular weight measured by gel permeation chromatography (GPC).

The epoxy equivalent of the epoxy resin is preferably 50-3000, more preferably 80-2000, still more preferably 110-1000. Within this range, the crosslink density of the cured product is sufficient, and an insulating layer with a small surface roughness can be obtained. The epoxy equivalent can be measured according to the method specified in JIS K7236, and is the mass of a resin containing one equivalent of epoxy groups.

-Curing agent-
The curing agent is not particularly limited as long as it has the function of curing the epoxy resin. system curing agents and the like. The curing agent may be used singly or in combination of two or more.

As the phenolic curing agent and the naphtholic curing agent, a phenolic curing agent having a novolac structure or a naphtholic curing agent having a novolac structure is preferable from the viewpoint of heat resistance and water resistance. From the viewpoint of adhesion strength to the conductor layer, a nitrogen-containing phenolic curing agent or a nitrogen-containing naphthol curing agent is preferable, and a triazine skeleton-containing phenolic curing agent or a triazine skeleton-containing naphthol curing agent is more preferable. Among them, a triazine skeleton-containing phenol novolak resin is preferable from the viewpoint of highly satisfying heat resistance, water resistance, and adhesion strength to the conductor layer. These may be used individually by 1 type, and may be used in combination of 2 or more type.

Specific examples of phenol-based curing agents and naphthol-based curing agents include, for example, “MEH-7700”, “MEH-7810” and “MEH-7851” manufactured by Meiwa Kasei Co., Ltd., manufactured by Nippon Kayaku Co., Ltd. "NHN", "CBN", "GPH", Tohto Kasei Co., Ltd. "SN-170", "SN-180", "SN-190", "SN-475", "SN-485", " SN-495", "SN-375", "SN-395", DIC Corporation "LA-7052", "LA-7054", "LA-3018", "LA-1356" and the like. .

From the viewpoint of increasing the adhesion strength with the conductor layer 24, an active ester curing agent is also preferable. The active ester-based curing agent is not particularly limited, but generally contains an ester group with high reaction activity such as phenol esters, thiophenol esters, N-hydroxyamine esters, esters of heterocyclic hydroxy compounds in one molecule. A compound having two or more is preferably used. The active ester curing agent is preferably obtained by a condensation reaction between a carboxylic acid compound and/or a thiocarboxylic acid compound and a hydroxy compound and/or a thiol compound. In particular, from the viewpoint of improving heat resistance, an active ester curing agent obtained from a carboxylic acid compound and a hydroxy compound is preferred, and an active ester curing agent obtained from a carboxylic acid compound and a phenol compound and/or a naphthol compound is more preferred. Examples of carboxylic acid compounds include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, and pyromellitic acid. Examples of phenolic compounds or naphthol compounds include hydroquinone, resorcinol, bisphenol A, bisphenol F, bisphenol S, phenolphthalin, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol and m-cresol. , p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucine, benzene triols, dicyclopentadiene-type diphenol compounds, phenol novolacs, and the like. Here, the term "dicyclopentadiene-type diphenol compound" refers to a diphenol compound obtained by condensing one molecule of dicyclopentadiene with two molecules of phenol.

Active ester curing agents include active ester compounds containing a dicyclopentadiene type diphenol structure, active ester compounds containing a naphthalene structure, active ester compounds containing acetylated phenol novolacs, and active ester compounds containing benzoylated phenol novolacs. Among them, an active ester compound containing a naphthalene structure and an active ester compound containing a dicyclopentadiene-type diphenol structure are more preferred. These may be used individually by 1 type, and may be used in combination of 2 or more type. The “dicyclopentadiene-type diphenol structure” represents a divalent structural unit composed of phenylene-dicyclopentalene-phenylene.

Commercially available active ester curing agents include active ester compounds containing a dicyclopentadiene type diphenol structure such as "EXB9451", "EXB9460", "EXB9460S", "HPC8000-65T" (manufactured by DIC Corporation), "EXB9416-70BK" (manufactured by DIC Corporation) as an active ester compound containing a naphthalene structure, "DC808" (manufactured by Mitsubishi Chemical Corporation) as an active ester compound containing an acetylated phenol novolak, and a benzoylated phenol novolac. "YLH1026" (made by Mitsubishi Chemical Corporation) etc. are mentioned as an active-ester compound containing.

Specific examples of benzoxazine-based curing agents include "HFB2006M" manufactured by Showa High Polymer Co., Ltd., and "Pd" and "Fa" manufactured by Shikoku Kasei Kogyo Co., Ltd.

The cyanate ester curing agent is not particularly limited. bisphenol F type, bisphenol S type, etc.), cyanate ester curing agents, and prepolymers obtained by partially triazinizing these. Specific examples include bisphenol A dicyanate (BADCy, also referred to as 2,2-bis(4-cyanatephenyl)propane), polyphenolcyanate (oligo(3-methylene-1,5-phenylenecyanate)), 4, 4'-methylenebis(2,6-dimethylphenylcyanate), 4,4'-ethylidene diphenyl dicyanate, hexafluorobisphenol A dicyanate, 1,1-bis(4-cyanatophenyl)methane, bis(4-cyanate-3 ,5-dimethylphenyl)methane, 1,3-bis(4-cyanatophenyl-1-(methylethylidene))benzene, bis(4-cyanatophenyl)thioether, and bis(4-cyanatophenyl)ether. Polyfunctional cyanate resins derived from cyanate resins, phenol novolacs, cresol novolacs, and the like, and prepolymers obtained by partially triazine-forming these cyanate resins. Commercially available cyanate ester curing agents include "PT30" and "PT60" (both phenol novolac type polyfunctional cyanate ester resins) and "BA230" (a part or all of bisphenol A dicyanate is triazine-modified) manufactured by Lonza. trimerized prepolymer), "Primaset (registered trademark) BADCy", and the like.

Specific examples of carbodiimide-based curing agents include “V-03” and “V-07” manufactured by Nisshinbo Chemical Co., Ltd., and the like.

From the viewpoint of improving the mechanical strength and water resistance of the resulting insulating layer, the ratio of the epoxy resin to the curing agent is [total number of epoxy groups in the epoxy resin]:[total number of reactive groups in the curing agent]. The range is preferably from 1:0.2 to 1:2, more preferably from 1:0.3 to 1:1.5, and even more preferably from 1:0.4 to 1:1. 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 curing agent. In addition, the total number of epoxy groups in the epoxy resin is the sum of the values obtained by dividing the mass of the non-volatile component of each epoxy resin by the epoxy equivalent, and the total number of reactive groups in the curing agent is , is the value obtained by dividing the mass of the non-volatile component of each curing agent by the reactive group equivalent and totaling the values for all curing agents.

-Inorganic filler-
Materials for the inorganic filler are not particularly limited, but examples include silica, alumina, glass, cordierite, silicon oxide, barium sulfate, barium carbonate, talc, clay, mica powder, zinc oxide, hydrotalcite, boehmite, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, boron nitride, aluminum nitride, manganese nitride, aluminum borate, strontium carbonate, zirconium oxide, barium titanate, barium zirconate titanate, strontium titanate, Examples include calcium titanate, magnesium titanate, bismuth titanate, titanium oxide, barium zirconate, calcium zirconate, zirconium phosphate, and zirconium tungstate phosphate. Among these, silica such as amorphous silica, fused silica, crystalline silica, synthetic silica and hollow silica is particularly preferred. As silica, spherical silica is preferable. An inorganic filler may be used individually by 1 type, and may be used in combination of 2 or more type. Examples of commercially available spherical fused silica include "SO-C3", "SO-C2", "SO-C1", "YA100C", "YA050C", and "YA010C" manufactured by Admatechs.

From the viewpoint of obtaining an insulating layer on which a fine wiring pattern can be formed, the average particle size of the inorganic filler is preferably 3 μm or less, more preferably 1 μm or less, and 0.7 μm or less. 0.5 μm or less, 0.4 μm or less, or 0.3 μm or less is even more preferable. The lower limit of the average particle size of the inorganic filler is 0.01 μm or more from the viewpoint of obtaining a resin varnish having an appropriate viscosity and good handleability when forming a resin varnish using a resin composition. is preferably 0.03 μm or more, more preferably 0.05 μm or more, even more preferably 0.07 μm or more, and particularly preferably 0.1 μm or more. The average particle size of the inorganic filler can be measured by a laser diffraction/scattering method based on Mie scattering theory. Specifically, the particle size distribution of the inorganic filler can be prepared on a volume basis using a laser diffraction particle size distribution measuring apparatus, and the median diameter can be used as the average particle size for measurement. As the measurement sample, one obtained by ultrasonically dispersing an inorganic filler in water can be preferably used. "LA-500", "LA-750", "LA-950" manufactured by Horiba, Ltd. and the like can be used as the laser diffraction particle size distribution analyzer.

As the inorganic filler used in the production method of the present embodiment, it is preferable to use an inorganic filler from which coarse particles have been removed by classification. In one embodiment, it is preferable to use an inorganic filler from which particles with a particle size of 10 μm or more are removed by classification, more preferably an inorganic filler from which particles with a particle size of 5 μm or more are removed by classification, It is more preferable to use an inorganic filler from which particles having a particle size of 3 μm or more have been removed by classification.

The average particle size of the inorganic filler is preferably 0.01 μm to 3 μm, more preferably 0.01 μm to 0.4 μm.

From the viewpoint of improving dispersibility and moisture resistance, the inorganic filler is preferably surface-treated with a surface-treating agent. Examples of surface treatment agents include aminosilane coupling agents, epoxysilane coupling agents, mercaptosilane coupling agents, silane coupling agents, organosilazane compounds, and titanate coupling agents. The surface treatment agents may be used singly or in combination of two or more. Examples of commercially available surface treatment agents include "KBM403" (3-glycidoxypropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM803" (3-mercaptopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd. silane), Shin-Etsu Chemical Co., Ltd. "KBE903" (3-aminopropyltriethoxysilane), Shin-Etsu Chemical Co., Ltd. "KBM573" (N-phenyl-3-aminopropyltrimethoxysilane), Shin-Etsu Chemical Co., Ltd. "SZ-31" (hexamethyldisilazane) and the like.

After surface treatment of the inorganic filler, the amount of carbon bonded to the surface of the inorganic filler per unit surface area is preferably 0.05 mg/m ² or more, more preferably 0.08 mg/m ² or more. , more preferably 0.11 mg/m ² or more, still more preferably 0.14 mg/m ² or more, particularly preferably 0.17 mg/m ² or more, 0.20 mg/m ² or more, 0.23 mg /m ² or more, or 0.26 mg/m ² or more. The upper limit of the amount of carbon is preferably 1.00 mg/m ² or less, more preferably 0.75 mg/m ² or less, even more preferably 0.70 mg/m ² or less, still more preferably 0.70 mg/m 2 or less. 65 mg/m ² or less, 0.60 mg/m ² or less, 0.55 mg/m ² or less, 0.50 mg/m ² or less.

The amount of carbon bonded to the surface of the inorganic filler per unit area can be calculated by the following procedure. A sufficient amount of methyl ethyl ketone (MEK) is added as a solvent to the inorganic filler after the surface treatment, and the inorganic filler is ultrasonically cleaned. After removing the supernatant liquid and drying the obtained non-volatile component, the amount of carbon bound to the surface of the inorganic filler is measured using a carbon analyzer. By dividing the obtained amount of carbon by the specific surface area of the inorganic filler, the amount of carbon bonded to the inorganic filler per unit surface area is calculated. Examples of the carbon analyzer include "EMIA-320V" manufactured by Horiba, Ltd., and the like.

The content of the inorganic filler in the resin composition is determined from the viewpoint of reducing the thermal expansion coefficient of the insulating layer 30 and preventing the occurrence of cracks and circuit distortion due to the difference in thermal expansion between the insulating layer 30 and the conductor layer 24. , is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more. When the insulating layer 30 is formed using a resin composition having a high inorganic filler content, the adhesion strength between the insulating layer 30 and the conductor layer 24 may decrease. For example, even when a resin composition having a high inorganic filler content is used, sufficient adhesion strength between the insulating layer 30 and the conductor layer 24 can be achieved. In the circuit board manufacturing method of the present invention, the content of the inorganic filler in the resin composition can be further increased without lowering the adhesion strength between the insulating layer 30 and the conductor layer 24 . For example, the content of the inorganic filler in the resin composition may be increased to 62% by mass or more, 64% by mass or more, 66% by mass or more, 68% by mass or more, or 70% by mass or more.

From the viewpoint of the mechanical strength of the insulating layer 30, the upper limit of the content of the inorganic filler is preferably 95% by mass or less, more preferably 90% by mass or less, and further preferably 85% by mass or less. preferable.

In one embodiment, the resin composition used for the resin composition layer 30X contains the above epoxy resin, curing agent and inorganic filler. Among them, the resin composition contains, as an epoxy resin, a mixture of a liquid epoxy resin and a solid epoxy resin (the mass ratio of liquid epoxy resin:solid epoxy resin is preferably 1:0.1 to 1:6, more preferably 1 : 0.3 to 1:5, more preferably 1:0.6 to 1:4.5) as a curing agent, a phenolic curing agent, a naphthol curing agent, an active ester curing agent and a cyanate ester curing agent. It is preferable to include at least one selected from the group consisting of silica as an inorganic filler. Regarding the resin composition layer 30X containing such a combination of specific components, the preferred contents of the epoxy resin, the curing agent, and the inorganic filler are as described above. It is preferable that the content of the inorganic filler is 40% to 95% by mass, the content of the epoxy resin is 10% to 30% by mass, and the content of the inorganic filler is 50% by mass to More preferably, it is 90% by mass. Regarding the content of the curing agent, it is preferable that the ratio of the total number of epoxy groups in the epoxy resin to the total number of reactive groups in the curing agent is 1:0.2 to 1:2. It is more preferable that the ratio is 1:0.3 to 1:1.5, more preferably 1:0.4 to 1:1.

The resin composition used for forming the resin composition layer 30X may further contain a thermoplastic resin, a curing accelerator, a flame retardant, an organic filler, and the like, if necessary. These components are described below.

-Thermoplastic resin-
Examples of thermoplastic resins include phenoxy resins, polyvinyl acetal resins, polyolefin resins, polybutadiene resins, polyimide resins, polyamideimide resins, polyetherimide resins, polysulfone resins, polyethersulfone resins, polyphenylene ether resins, polycarbonate resins, polyether resins. Ether ketone resins and polyester resins can be mentioned. 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, and even 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 polystyrene-equivalent weight average molecular weight of the thermoplastic resin is measured by LC-9A/RID-6A manufactured by Shimadzu Corporation as a measuring device, and Shodex K-800P/K- manufactured by Showa Denko Co., Ltd. as a column. 804L/K-804L can be measured using chloroform or the like as a mobile phase at a column temperature of 40° C., and can be calculated using a standard polystyrene calibration curve.

Examples of phenoxy resins include bisphenol A skeleton, bisphenol F skeleton, bisphenol S skeleton, bisphenolacetophenone skeleton, novolac skeleton, biphenyl skeleton, fluorene skeleton, dicyclopentadiene skeleton, norbornene skeleton, naphthalene skeleton, anthracene skeleton, adamantane skeleton, and terpene. and a phenoxy resin having one or more skeletons selected from the group consisting of a trimethylcyclohexane skeleton. The terminal of the phenoxy resin may be any functional group such as a phenolic hydroxyl group or an epoxy group. A phenoxy resin may be used individually by 1 type, and may be used in combination of 2 or more type. Specific examples of phenoxy resins include "1256" and "4250" manufactured by Mitsubishi Chemical Corporation (both phenoxy resins containing bisphenol A skeleton), "YX8100" (phenoxy resin containing bisphenol S skeleton), and "YX6954" ( bisphenolacetophenone skeleton-containing phenoxy resin); YL7213", "YL7290" and "YL7482".

Specific examples of polyvinyl acetal resins include Denka Butyral 4000-2, 5000-A, 6000-C, and 6000-EP manufactured by Denki Kagaku Kogyo Co., Ltd., S-Lec BH series and BX series manufactured by Sekisui Chemical Co., Ltd., KS series, BL series, BM series and the like.

Specific examples of the polyimide resin include "Ricacoat SN20" and "Ricacoat PN20" manufactured by Shin Nippon Rika Co., Ltd. Specific examples of polyimide resins also include linear polyimides obtained by reacting bifunctional hydroxyl group-terminated polybutadiene, diisocyanate compounds and tetrabasic acid anhydride (for example, linear polyimides described in JP-A-2006-37083). and modified polyimides such as polysiloxane skeleton-containing polyimides (polysiloxane skeleton-containing polyimides described in JP-A-2002-12667 and JP-A-2000-319386).

Specific examples of polyamide-imide resins include "VYLOMAX HR11NN" and "VYLOMAX HR16NN" manufactured by Toyobo Co., Ltd. Specific examples of the polyamideimide resin include modified polyamideimides such as polysiloxane skeleton-containing polyamideimides "KS9100" and "KS9300" manufactured by Hitachi Chemical Co., Ltd.

Specific examples of the polyethersulfone resin include "PES5003P" manufactured by Sumitomo Chemical Co., Ltd., and the like.

Specific examples of the polysulfone resin include polysulfone "P1700" and "P3500" manufactured by Solvay Advanced Polymers.

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

- Curing accelerator -
Examples of curing accelerators include phosphorus-based curing accelerators, amine-based curing accelerators, imidazole-based curing accelerators, and guanidine-based curing accelerators. Curing accelerators are preferred. A hardening accelerator may be used individually by 1 type, and may be used in combination of 2 or more type. The content of the curing accelerator is preferably in the range of 0.05% by mass to 3% by mass when the total of the non-volatile components of the epoxy resin and the curing agent is 100% by mass. Curing accelerators include, for example, 4-dimethylaminopyridine (DMAP) and cobalt (III) acetylacetonate (Co(III)-1M) (Tokyo Kasei Co., Ltd.).

-Flame retardants-
Examples of flame retardants include organic phosphorus flame retardants, organic nitrogen-containing phosphorus compounds, nitrogen compounds, silicone flame retardants, and metal hydroxides. A flame retardant may be used individually by 1 type, or may be used in combination of 2 or more type. The content of the flame retardant in the resin composition is not particularly limited, but is preferably 0.5% by mass to 10% by mass, more preferably 1% by mass to 9% by mass. Examples of flame retardants include HCA-HQ (manufactured by Sanko Co., Ltd.).

－Organic filler－
As the organic filler, any organic filler that can be used for forming an insulating layer of a circuit board may be used. Examples thereof include rubber particles, polyamide fine particles, silicone particles, etc. Rubber particles are preferred.

The rubber particles are not particularly limited as long as they are fine particles of a resin that is made insoluble and infusible in an organic solvent by chemically cross-linking a resin exhibiting rubber elasticity. Examples include acrylonitrile-butadiene rubber particles, butadiene rubber particles, Examples include acrylic rubber particles. Specific examples of rubber particles include XER-91 (manufactured by Japan Synthetic Rubber Co., Ltd.), Staphyloid AC3355, AC3816, AC3816N, AC3832, AC4030, AC3364, IM101 (manufactured by Aica Kogyo Co., Ltd.), and Paraloid. Examples include EXL2655 and EXL2602 (manufactured by Kureha Chemical Industry Co., Ltd.).

The average particle size 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 size of rubber particles can be measured using a dynamic light scattering method. For example, rubber particles are uniformly dispersed in an appropriate organic solvent by ultrasonic waves or the like, and the particle size distribution of the rubber particles is determined on a mass basis using a concentrated particle size analyzer ("FPAR-1000" manufactured by Otsuka Electronics Co., Ltd.). It can be measured by making the median diameter as the average particle diameter. The content of rubber particles in the resin composition is preferably 1% by mass to 10% by mass, more preferably 2% by mass to 5% by mass.

-Other ingredients-
The resin composition used for the resin composition layer may optionally contain other components. Other components include, for example, organometallic compounds such as organocopper compounds, organozinc compounds and organocobalt compounds, as well as thickeners, antifoaming agents, leveling agents, adhesion imparting agents, coloring agents and curable resins. resin additives and the like.

In the plastic film support-attached resin sheet 60, the resin composition layer 30X may have a multi-layer structure consisting of two or more layers. When the resin composition layer 30X has a multilayer structure, it is preferable that the thickness of the entire layer is within the above range.

The plastic film support-attached resin sheet 60 can be produced by forming the resin composition layer 30X so as to be bonded to the plastic film support 50 .

The resin composition layer 30X can be formed on the plastic film support 50 by any suitable conventionally known method. For example, a resin varnish is prepared by dissolving a resin composition in a solvent, the resin varnish is applied to the surface of the plastic film support 50 using a coating device such as a die coater, and the coating film is dried to form a resin composition. Layer 30X may be formed.

Examples of the solvent used for preparing the resin varnish include ketone solvents such as acetone, methyl ethyl ketone and cyclohexanone; ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate and carbitol acetate; and carbitol solvents such as butyl carbitol, aromatic hydrocarbon solvents such as toluene and xylene, and amide solvents such as dimethylformamide, dimethylacetamide and N-methylpyrrolidone. A solvent may be used individually by 1 type, and may be used in combination of 2 or more type.

The coating film may be dried by a known drying method such as heating or blowing hot air. If a large amount of solvent remains in the resin composition layer 30X, it causes swelling after curing. Let Although it varies depending on the boiling point of the organic solvent in the resin varnish, for example, when using a resin varnish containing 30% by mass to 60% by mass of solvent, the resin composition is obtained by drying at 50 ° C. to 150 ° C. for 3 minutes to 10 minutes. Layer 30X may be formed.

In the plastic film support-attached resin sheet 60, the plastic film support 50 A protective film according to can be further laminated. The thickness of the protective film is not particularly limited, and may be, for example, 1 μm to 40 μm. By laminating the protective film, it is possible to prevent the surface of the resin composition layer 30X from being dusted or scratched. The plastic film support-attached resin sheet 60 can be wound into a roll and stored, and can be used when manufacturing the circuit board 10 by peeling off the protective film.

[Semiconductor device]
A semiconductor device having the circuit board 10 can be manufactured by using the circuit board 10 manufactured by the manufacturing method of the present invention and mounting, for example, a semiconductor chip having a desired function.

Examples of such semiconductor devices include various semiconductor devices used in electrical appliances (e.g., computers, mobile phones, digital cameras, televisions, etc.) and vehicles (e.g., motorcycles, automobiles, trains, ships, aircraft, etc.). mentioned.

EXAMPLES The present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. In the following, "parts" and "%" mean "mass parts" and "mass%", respectively, unless otherwise specified.

Examples 1 to 3 and Comparative Examples 1 to 4 are described below.

[Sample preparation and evaluation]
(1) Surface treatment of wiring board A glass cloth-based epoxy resin laminate (copper foil thickness 18 μm, substrate thickness 0.3 mm, size 510 mm × 340 mm, on both sides of a wiring board on which a conductor pattern (residual copper rate of about 70%) is formed using "R5715ES" manufactured by Panasonic Corporation), treatment (i) with "CZ8100" manufactured by MEC Co., Ltd. Sample (i) obtained by etching and removing to a thickness of about 0.6 μm and roughening the surface of the conductor pattern, and treatment (ii) instead of treatment (i) with MEC ( A sample (ii) obtained by performing the “Flatbond” treatment manufactured by Co., Ltd. was prepared.

(Measurement of arithmetic mean roughness (Ra value) of surface of conductor layer)
Using a non-contact surface roughness meter (WYKO NT3300 manufactured by BCo Instruments), the Ra value was determined as a numerical value obtained with a measurement range of 121 µm × 92 µm with a 50x lens in VSI contact mode. The Ra value is a value obtained by averaging 10 measurement values for each of sample (i) and sample (ii). Sample (i) treated with CZ8100 had an Ra value of 270 nm and sample (ii) with flat bond treatment had an Ra value of 160 nm. Thus, in this embodiment, the Ra value is smaller than the Ra value (500 nm to 700 nm) obtained by conventional processing (etching to a thickness of about 1 μm to 2 μm).

(2) Step of laminating a resin sheet with a plastic film support Peel off the protective film of a resin sheet with a plastic film support (prepreg with a plastic film support) (size 504 mm × 334 mm) produced as shown in the production example below. Then, using a batch-type vacuum pressure laminator (2-stage build-up laminator, CVP700, manufactured by Nichigo-Morton Co., Ltd.), wiring is performed so that the resin composition layer is in contact with the wiring substrate treated in (1) above. Laminated on both sides of the substrate. This lamination step was carried out by pressure bonding for 30 seconds at a temperature of 110° C. and a pressure of 0.74 MPa after reducing the pressure to 13 hPa or less for 30 seconds. Then, a hot press process was performed for 60 seconds under conditions of a temperature of 110° C. and a pressure of 0.5 MPa.

When the resin sheet with a plastic film support is a prepreg with a plastic film support, after bonding the prepregs with a plastic film support to both sides of the wiring board, the pressure in the lamination process is reduced for 30 seconds to a pressure of 13 hPa or less. , a temperature of 120° C. and a pressure of 0.74 MPa for 60 seconds. Then, a hot press process was performed for 90 seconds at a temperature of 120° C. and a pressure of 0.5 MPa.

(Measurement and evaluation of adhesion strength (peel strength) between conductor layer and insulating layer)
The peel strength was measured by the following treatments (a) to (c).
(a) Surface treatment of copper foil The glossy side of 3EC-III (electrolytic copper foil, thickness 35 μm) manufactured by Mitsui Kinzoku Mining Co., Ltd. is treated (i) by “CZ8100” manufactured by MEC Co., Ltd. to thicken. Sample (i) obtained by etching and removing by 0.6 μm and roughening the surface of the copper foil (i), and treatment (ii) “Flat Bond” treatment manufactured by MEC Co., Ltd. instead of the treatment (i) A sample (ii) obtained by treating the surface of the copper foil was prepared. Regarding the surface roughness of the copper foil, the sample (i) treated with CZ8100 had an Ra value of 270 (nm), and the sample (ii) treated with a flat bond had an Ra value of 160 (nm). rice field.

(b) Lamination of copper foil and formation of insulating layer Peeling off the plastic film support (PET film) from the resin sheet with plastic film support (prepreg with plastic film support) laminated in (2) above, With the shiny side of the copper foil treated in a) facing the resin composition layer side, under the same conditions as the lamination step of (2) above, the copper foil is formed on both sides of the wiring board. Laminated in layers. A sample (circuit board) for evaluation was obtained as an insulating layer by thermally curing the resin composition layer by heat treatment at 120° C. for 30 minutes and then at 175° C. for 30 minutes. The obtained circuit board is called "evaluation board A". Moreover, the laminated copper foil is called a conductor layer.

(c) Measurement of peeling strength (peel strength) of conductor layer The evaluation substrate A obtained in (b) above was cut into small pieces of 150 mm x 30 mm. A strip-shaped cut of 10 mm in width and 100 mm in length was made in the copper foil portion of the small piece, and one end of the strip-shaped cut in the copper foil was peeled off and a gripper (TSE Co., Ltd., Autocom type) was applied. Tester AC-50C-SL), and using an Instron universal testing machine at room temperature at a speed of 50 mm / min. The measured value was taken as the peel strength.

Samples with a measured peel strength of 0.15 kgf/cm or more were evaluated as "good", and samples with a measured peel strength of less than 0.15 kgf/cm were evaluated as "bad".

Subsequent to the step of laminating a resin sheet with a plastic film support in (2) above, evaluation substrates B and C were obtained by carrying out the following (3) to (7).

(3) Curing of resin composition layer A wiring board laminated with a resin sheet with a plastic film support was cured at 120°C for 30 minutes, then at 175°C for 30 minutes, or at 165°C for 30 minutes (Comparative Examples 1 and 2). By heating, the resin composition layer was thermally cured to form an insulating layer.

(4) Formation of Via Hole A small diameter via hole was formed in the insulating layer directly above the inner circular conductor pattern with a diameter of 150 μm by irradiating a laser from above the plastic film support side.

The via hole forming process was performed under different conditions as shown in (A) to (D) below. Here, the correspondence between Examples 1 to 3 and Comparative Examples 1 to 4 will be described.

For Example 1, Comparative Example 1 and Comparative Example 3, according to the procedure (A) below, for Example 2 and Example 4, according to the procedure (B) below, for Example 3 and Comparative Example 4, (C ), and for Comparative Example 2, according to the procedure of (D) below, a small-diameter via hole was formed in each insulating layer.

(A) Using a CO ₂ laser processing machine "605GTWIII (-P)" manufactured by Mitsubishi Electric Corporation, a laser is irradiated from above the plastic film support side, and the top diameter (diameter) of 30 or 31 μm is applied to the insulating layer. of via holes were formed. The laser irradiation conditions were a mask diameter of 1 mm, a pulse width of 16 μs, an energy of 0.20 mJ/shot, two shots, and burst mode (10 kHz).
(B) Using a CO ₂ laser processing machine "605GTWIII (-P)" manufactured by Mitsubishi Electric Corporation, a laser is irradiated from above the plastic film support side, and a via hole with a top diameter (diameter) of 25 μm is formed in the insulating layer. formed. The laser irradiation conditions were a mask diameter of 0.9 mm, a pulse width of 16 μs, an energy of 0.18 mJ/shot, two shots, and burst mode (10 kHz).
(C) Using a CO ₂ laser processing machine "LC-2k212/2C" manufactured by Via Mechanics Co., Ltd., a laser is irradiated from above the plastic film support side, and the top diameter (diameter) of the insulating layer is 40 or 41 μm. of via holes were formed. The laser irradiation conditions were a mask diameter of 2.5 mm, a pulse width of 4 μs, a power of 0.7 W, a shot number of 3, and a cycle mode (2 kHz).
(D) Using a CO ₂ laser processing machine "605GTWIII(-P)" manufactured by Mitsubishi Electric Corporation, a laser is irradiated from above the plastic film support side, and a via hole with a top diameter (diameter) of 29 μm is formed in the insulating layer. formed. The laser irradiation conditions were a mask diameter of 0.9 mm, a pulse width of 16 μs, an energy of 0.36 mJ/shot, two shots, and burst mode (10 kHz).

The depth d of the via holes formed in Examples 1, 2, 4 and Comparative Examples 1 to 3 was 15 μm, and the depth d of the via holes formed in Example 3 and Comparative Example 4 was 23 μm. there were.

(5) Desmear Treatment After forming the via holes, the plastic film support was peeled off, and the circuit board provided with the via holes was subjected to desmear treatment. As the desmear treatment, the following wet desmear treatment was performed.
Wet desmear treatment:
A circuit board provided with via holes is soaked in a swelling liquid ("Swelling Dip Securigant P" manufactured by Atotech Japan Co., Ltd., an aqueous solution of diethylene glycol monobutyl ether and sodium hydroxide) at 60 ° C. for 10 minutes, and then in an oxidizing agent solution ( "Concentrate Compact CP" manufactured by Atotech Japan Co., Ltd., an aqueous solution with a potassium permanganate concentration of about 6% and sodium hydroxide concentration of about 4%) at 80 ° C. for 20 minutes, and finally a neutralizing solution (Atotech Japan Co., Ltd.) ) manufactured by "Reduction Solution Securigant P", sulfuric acid aqueous solution) at 40°C for 5 minutes, and then dried at 80°C for 15 minutes. The obtained substrate is called "evaluation substrate B".

(6) Confirmation of the shape of the via hole For the evaluation substrate B obtained in (5) above, the opening of the via hole was observed from the surface with a scanning electron microscope (SMI3050SE FIB-SEM composite device manufactured by SII Nanotechnology Co., Ltd.). After observation with a focused ion beam processing observation device (FIB), the cross section of the central portion is cut out, and from the obtained image, the top diameter of the via hole (Z), the minimum diameter of the via hole (Y), the bottom diameter of the via hole (X ) and the distance of the minimum diameter (Y) from the bottom of the via hole, and the average value of 10 via holes was obtained.

(7) Formation of conductor layer In order to form a conductor layer on the surface of the evaluation board B, a plating process (copper plating process using a chemical solution manufactured by Atotech Japan Co., Ltd.) including the following steps 1 to 7 is performed to form a conductor. formed a layer.

1. Alkali cleaning (cleaning and charge adjustment of the surface of the insulating layer with via holes)
Trade name: Cleaning Cleaner Security 902 (trade name) was used to wash at 60° C. for 5 minutes.
2. Soft etching (cleaning inside via holes)
It was treated at 30° C. for 1 minute with a sulfuric acid-acid sodium peroxodisulfate aqueous solution.
3. Pre-dip (adjustment of surface charge of insulating layer for Pd application)
Pre. Dip Neoganth B (trade name) was used for 1 minute at room temperature.
4. Application of activator (application of Pd to the surface of the insulating layer)
Using Activator Neoganth 834 (trade name), it was treated at 35° C. for 5 minutes.
5. Reduction (reduction of Pd applied to the insulating layer)
Reducer Neoganth WA (trade name) and Reducer Accelerator 810 mod. (trade name) and treated at 30° C. for 5 minutes.
6. Electroless copper plating process (Cu is deposited on the surface of the insulating layer (Pd surface))
Using a mixed solution of Basic Solution Printganth MSK-DK (trade name), Copper solution Printganth MSK (trade name), Stabilizer Printganth MSK-DK (trade name), and Reducer Cu (trade name), at 35 ° C. Treated for 20 minutes. The thickness of the formed electroless copper plating layer was 1 μm.

7. Electrolytic Copper Plating Step Next, an electrolytic copper plating step was performed using a chemical solution manufactured by Atotech Japan Co., Ltd. under the condition that the via holes were filled with copper. After that, as a resist pattern for patterning by etching, a land pattern with a diameter of 80 μm corresponding to the via hole is formed, and using this land pattern, a conductor layer having a conductor pattern with a thickness of 15 μm is formed on the surface of the insulating layer. did. Next, annealing treatment was performed at 190° C. for 60 minutes to obtain a circuit board. The obtained circuit board is called "evaluation board C".

<Thermal cycle test>
The evaluation substrate C obtained in (7) above was subjected to treatment a at -55 ° C. for 30 minutes and treatment at 120 ° C. for 30 minutes using a small thermal shock apparatus "TSE-11" manufactured by Espec Co., Ltd. A thermal cycle test (TCB) was conducted in which 1,000 cycles of the treatment b were taken as one cycle. After that, the filled via made of copper filled in the via hole by the plating process was observed from the surface with a scanning electron microscope (SMI3050SE FIB-SEM composite device manufactured by SII Nano Technology Co., Ltd.). A cross section of the central portion was cut out with a mortar, and cracks in the insulating layer and conductor layer and voids in the conductor layer were observed for 10 filled vias, and evaluated according to the following evaluation criteria.
Evaluation criteria:
◯: No cracks or voids were observed in any of the filled vias.
x: Cracks or voids were confirmed in one or more filled vias.

<Preparation Example 1> Preparation of resin varnish 1 Bisphenol-type epoxy resin (epoxy equivalent of about 165, "ZX1059" manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., 1:1 mixture of bisphenol A type and bisphenol F type) 6 parts, bixylenol type epoxy resin (epoxy equivalent about 185, "YX4000HK" manufactured by Mitsubishi Chemical Corporation) 10 parts, biphenyl type epoxy resin (epoxy equivalent about 290, manufactured by Nippon Kayaku Co., Ltd. "NC3000H") 10 parts, and phenoxy resin ( 10 parts of "YX7553BH30" manufactured by Mitsubishi Chemical Corporation, a methyl ethyl ketone (MEK) solution containing 30% by mass of non-volatile components) were heated and dissolved in 20 parts of solvent naphtha with stirring. After cooling to room temperature, 10 parts of a triazine skeleton-containing phenolic novolak curing agent (hydroxyl equivalent 146, "LA-1356" manufactured by DIC Corporation, MEK solution of 60% by mass of non-volatile components), active ester curing. Agent ("HPC8000-65T" manufactured by DIC Corporation, active group equivalent of about 223, non-volatile component 65% by mass toluene solution) 10 parts, curing accelerator (4-dimethylaminopyridine (DMAP), non-volatile component 2% by mass MEK solution) 4 parts, flame retardant ("HCA-HQ" manufactured by Sanko Co., Ltd., 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide , average particle size 1 μm), 2 parts of rubber particles (“Staphyloid AC3816N” manufactured by Aica Kogyo Co., Ltd., finely ground product), and an aminosilane coupling agent (“KBM573” manufactured by Shin-Etsu Chemical Co., Ltd.). Small-diameter spherical silica (“SO-C1” manufactured by Admatechs Co., Ltd., average particle diameter 0.25 μm, carbon amount per unit surface area 0.36 mg / m ² ) were mixed and uniformly dispersed with a high-speed rotating mixer to prepare a resin varnish 1. Table 1 shows the compounding components and compounding amounts of Resin Varnish 1.

<Preparation Example 2> Preparation of resin varnish 2 Bisphenol-type epoxy resin (epoxy equivalent of about 165, "ZX1059" manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., 1:1 mixture of bisphenol A type and bisphenol F type) 6 parts, naphthalene type Epoxy resin ("HP-4032SS" manufactured by DIC Corporation, epoxy equivalent of about 144) 3 parts, bixylenol type epoxy resin (epoxy equivalent of about 185, manufactured by Mitsubishi Chemical Corporation "YX4000HK") 9 parts, biphenyl type epoxy resin (Epoxy equivalent about 290, "NC3000H" manufactured by Nippon Kayaku Co., Ltd.) 8 parts, and phenoxy resin (Mitsubishi Chemical Co., Ltd. "YX7553BH30", nonvolatile component 30% by mass methyl ethyl ketone (MEK) solution) 10 parts, It was heated and dissolved in 20 parts of solvent naphtha with stirring. After cooling to room temperature, 30 parts of an active ester curing agent ("HPC8000-65T" manufactured by DIC Corporation, an active group equivalent of about 223, a toluene solution of 65% by mass of non-volatile components), a curing accelerator (4 -Dimethylaminopyridine (DMAP), MEK solution of 2% by mass of non-volatile components) 10 parts, flame retardant (manufactured by Sanko Co., Ltd. "HCA-HQ", 10-(2,5-dihydroxyphenyl)-10-hydro-9 -Oxa-10-phosphaphenanthrene-10-oxide, average particle size 1 μm) 2 parts, rubber particles ("Staphyloid AC3816N" manufactured by Aica Kogyo Co., Ltd., finely ground product) 2 parts, aminosilane-based coupling agent (“KBM573” manufactured by Shin-Etsu Chemical Co., Ltd.), small-diameter spherical silica (“SO-C1” manufactured by Admatechs Co., Ltd., average particle diameter 0.00) from which particles of 3 μm or more were removed by classification. A resin varnish 2 was prepared by mixing 100 parts of 25 μm carbon and 0.36 mg/m ² carbon content per unit surface area and uniformly dispersing them with a high-speed rotating mixer. Table 1 shows the compounding components and compounding amounts of Resin Varnish 2.

<Preparation Example 3> Preparation of resin varnish 3 Bisphenol-type epoxy resin (epoxy equivalent of about 165, "ZX1059" manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., 1:1 mixture of bisphenol A type and bisphenol F type) 2 parts, bixylenol type epoxy resin (epoxy equivalent about 185, "YX4000HK" manufactured by Mitsubishi Chemical Corporation) 12 parts, biphenyl type epoxy resin (epoxy equivalent about 290, manufactured by Nippon Kayaku Co., Ltd. "NC3000H") 12 parts, and phenoxy resin ( 10 parts of "YX7553BH30" manufactured by Mitsubishi Chemical Corporation, a methyl ethyl ketone (MEK) solution containing 30% by mass of non-volatile components) were heated and dissolved in 20 parts of solvent naphtha with stirring. After cooling to room temperature, 10 parts of an active ester curing agent ("HPC8000-65T" manufactured by DIC Corporation, a toluene solution with an active group equivalent of about 223 and a non-volatile component of 65% by mass) and a cyanate ester curing agent are added. (BADCy, "Primaset (registered trademark) BADCy" manufactured by Lonza) 5 parts, curing accelerator (4-dimethylaminopyridine (DMAP), non-volatile component 2% by weight MEK solution) 1 part, curing accelerator (Tokyo Kasei ( Co., Ltd., cobalt (III) acetylacetonate (Co (III)-1M), MEK solution of 1% by mass of non-volatile components) 2 parts, flame retardant (manufactured by Sanko Co., Ltd. “HCA-HQ”, 10-(2 ,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide, average particle size 1 μm) 2 parts, rubber particles ("Staphyloid AC3816N" manufactured by Aica Kogyo Co., Ltd., Finely pulverized product) 2 parts, surface-treated with an aminosilane coupling agent ("KBM573" manufactured by Shin-Etsu Chemical Co., Ltd.), small-diameter spherical silica (Admatechs Co., Ltd.) from which particles of 3 μm or more have been removed by classification 100 parts of "SO-C1" manufactured by Ajinomoto Co., having an average particle size of 0.25 μm and a carbon amount per unit surface area of 0.36 mg/m ² , were mixed and uniformly dispersed in a high-speed rotating mixer to prepare a resin varnish 3. Table 1 shows the compounding components and compounding amounts of Resin Varnish 3.

<Production Example 1> Production of resin sheet 1 with plastic film support As the plastic film support, a PET film (Toray Industries, Inc. ) made "Lumirror T6AM", thickness 38 μm) was prepared. Resin varnish 1 was applied to the release surface of the plastic support using a die coater and dried at 80° C. to 110° C. (average 100° C.) for 3 minutes to form a resin composition layer. The thickness of the resin composition layer was 20 μm. Next, on the surface of the resin composition layer that is not bonded to the plastic film support, the rough side of a polypropylene film (“Alphan MA-411” manufactured by Oji Specialty Paper Co., Ltd., thickness 15 μm) is attached as a protective film. Together, a resin sheet 1 with a plastic film support (resin sheet 1) was obtained.

<Production Example 2> Production of prepreg 2 with plastic film support A 1000 glass cloth (thickness: 14 µm) manufactured by Arisawa Seisakusho Co., Ltd. was immersed and impregnated in the resin varnish 1 by the solvent method, and the solvent was volatilized by heating. , Dry so that the amount of solvent remaining in the prepreg is 0.5% and the thickness is 28 μm, and apply a non-silicone release agent ("AL-5" manufactured by Lintec Corporation) from both sides. The release surface of the PET film (manufactured by Toray Industries, Inc. "Lumirror T6AM", thickness 38 μm) and the polypropylene film (manufactured by Oji Specialty Paper Co., Ltd. "Alphan MA-411", thickness 15 μm) The rough surface side of was laminated to obtain a prepreg 2 with a plastic film support (prepreg 2).

<Production Example 3> Production of resin sheet 3 with plastic film support ) made "Lumirror T6AM", thickness 38 μm) was prepared. Resin varnish 2 was applied to the release surface of the plastic support using a die coater and dried at 80° C. to 110° C. (average 100° C.) for 3 minutes to form a resin composition layer. The thickness of the resin composition layer was 20 μm. Next, on the surface of the resin composition layer that is not bonded to the plastic film support, the rough side of a polypropylene film (“Alphan MA-411” manufactured by Oji Specialty Paper Co., Ltd., thickness 15 μm) is attached as a protective film. Together, a resin sheet 3 with a plastic film support (resin sheet 3) was obtained.

<Production Example 4> Production of resin sheet 4 with plastic film support As the plastic film support, a PET film (Toray Industries, Inc. ) made "Lumirror T6AM", thickness 38 μm) was prepared. Resin varnish 3 was applied to the release surface of the plastic support using a die coater and dried at 80° C. to 110° C. (average 100° C.) for 3 minutes to form a resin composition layer. The thickness of the resin composition layer was 20 μm. Next, on the surface of the resin composition layer that is not bonded to the plastic film support, the rough side of a polypropylene film (“Alphan MA-411” manufactured by Oji Specialty Paper Co., Ltd., thickness 15 μm) is attached as a protective film. Together, a resin sheet 4 with a plastic film support (resin sheet 4) was obtained.

<Production Example 5> Production of Prepreg 5 with Plastic Film Support A 1000 glass cloth (thickness: 14 μm) manufactured by Arisawa Seisakusho Co., Ltd. is immersed and impregnated in resin varnish 3 by the solvent method, and the solvent is volatilized by heating. The prepreg was dried so that the amount of solvent remaining in the prepreg was 0.5% and the thickness was 28 μm. The release surface of the release-treated PET film (“Lumirror T6AM” manufactured by Toray Industries, Inc., thickness 38 μm) and the polypropylene film (manufactured by Oji Specialty Paper Co., Ltd. “Alphan MA-411”, thickness 15 μm). The rough side was laminated to obtain a prepreg 5 with a plastic film support (prepreg 5).

The thickness of the resin composition layers of resin sheet 1, prepreg 2, resin sheet 3, resin sheet 4, and prepreg 5 (thickness including glass cloth in the case of prepreg) was ) was measured using Mitutoyo MCD-25MJ).

In the sample according to Example 1, the resin sheet 1 was used, the Ra value (surface roughness) of the surface of the conductor layer was set to 270 (nm) by the above roughening treatment, and the Ra value (surface roughness) was increased to 30 at 120 ° C. in the step (3). minutes, and then at 175° C. for 30 minutes to thermally cure the resin composition layer to form an insulating layer.

A sample according to Example 2 was produced in the same manner as in Example 1 except that the Ra value of the surface of the conductor layer was set to 160 (nm) by flat bonding.

A sample according to Example 3 was prepared in the same manner as in Example 1 except that the prepreg 2 was used as the resin sheet with a plastic film support.

A sample according to Example 4 was prepared in the same manner as in Example 2 except that the resin sheet 3 was used.

The sample according to Comparative Example 1 was prepared in the same manner as the sample according to Example 1, except that in the step (3) above, the resin composition layer was heated at 165° C. for 30 minutes and the resin composition layer was thermally cured to form an insulating layer. .

A sample according to Comparative Example 2 was formed in the same manner as in Comparative Example 1 except that the Ra value (surface roughness) of the surface of the conductor layer was set to 160 (nm) by flat bonding.

A sample according to Comparative Example 3 was prepared in the same manner as in Example 1 except that the resin sheet 4 was used as the resin sheet with a plastic film support.

A sample according to Comparative Example 4 was prepared in the same manner as in Example 1 except that the prepreg 5 was used as the resin sheet with a plastic film support.

Table 2 below shows the preparation conditions, aspects and evaluation results of the samples according to Examples 1 to 4, and Table 3 below shows the preparation conditions, aspects and evaluation results of the samples according to Comparative Examples 1 to 4.

As is clear from Tables 2 and 3, in the circuit boards according to Examples 1 to 4 where the top diameter (Z), minimum diameter (Y), and bottom diameter (X) of the via hole 40 satisfy a predetermined relationship, the laser A thermal cycle test revealed that even when a small-diameter via hole is formed by irradiation, it is possible to effectively suppress the occurrence of defects such as cracks in the conductor and insulating layers over time. Therefore, according to the present invention, deterioration of characteristics over time is suppressed, so that reliability can be improved, product life can be lengthened, and a thin circuit board can be provided. .

REFERENCE SIGNS LIST 10 circuit board 20 wiring board 22 substrate 24 conductor layer 24a surface of conductor layer 30 insulating layer 30X resin composition layer 30a surface of insulating layer 40 via hole 42 cut-out portion 44 bottom portion 50 plastic film support 60 resin sheet with plastic film support 70 Wiring layer X Bottom diameter Y Minimum diameter Z Top diameter t Thickness of insulating layer d Depth of via hole

Claims (9)

Step (A) A resin sheet with a plastic film support, which includes a plastic film support and a resin composition layer bonded to the plastic film support, is coated with a conductor pattern having a surface arithmetic mean roughness of 350 nm or less. a step of bonding to the conductor layer of a wiring board provided with a conductor layer containing
Step (B) The resin composition layer is thermally cured to form an insulating layer having a thickness of 25 μm or less on the conductor layer, the adhesion strength between the insulating layer and the conductor layer being 0.15 kgf/cm. A step of forming an insulating layer as described above;
Step (C) A laser is irradiated from the plastic film support side to form a via hole having a top diameter (Z) of 50 μm or less in the insulating layer, wherein the top diameter (Z) of the via hole and the minimum diameter (Y ) and the bottom diameter (X) of the via hole satisfies Y/Z=0.7 to 0.99 and Y/X=0.7 to 1 (Z>Y); ,
Step (D) a step of performing desmear treatment;
Step (E): peeling the plastic film support from the insulating layer;
Step (F) forming a further conductor layer on the insulating layer;
A method for manufacturing a circuit board, wherein the resin composition layer contains an epoxy resin, a curing agent and an inorganic filler. 2. The method of manufacturing a circuit board according to claim 1, wherein in step (A), a wiring board provided with a conductor layer including a conductor pattern having a surface arithmetic mean roughness of 300 nm or less is used. 3. The method of manufacturing a circuit board according to claim 1, wherein in step (B), an insulating layer having a thickness of less than 25 [mu]m is formed on the conductor layer. 4. The method for manufacturing a circuit board according to claim 1, wherein in step (B), an insulating layer having a thickness of 23 μm or less is formed on the conductor layer. 5. The method for manufacturing a circuit board according to any one of claims 1 to 4, wherein in step (B), an insulating layer having an adhesion strength to the conductor layer of 0.18 kgf/cm or more is formed. 6. The method of manufacturing a circuit board according to claim 1, wherein in step (C), a via hole having a top diameter (Z) of 40 μm or less is formed. 7. The method for manufacturing a circuit board according to claim 1, wherein in step (C), a via hole having a top diameter (Z) of 30 μm or less is formed. In step (C), carbon dioxide laser, YAG laser, UV-YAG laser, YVO ₄ 8. The method of manufacturing a circuit board according to claim 1, wherein the laser is irradiated using a laser light source selected from the group consisting of a laser and a YLF laser. The content of the inorganic filler in the resin composition layer is 50% by mass or more when the non-volatile component in the resin composition layer is 100% by mass, according to any one of claims 1 to 8. A method of manufacturing a circuit board.

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