Film for adhesive layer, wiring board, multilayer wiring board, and semiconductor device

Abstract

Provided is a film for an adhesive layer, which is capable of suppressing breakage of a plating layer that is disposed on the inner surface of a through hole which is formed in a multilayer wiring board. Specifically provided is a film 10A for an adhesive layer, which is used for the production of a multilayer wiring board 100. The multilayer wiring board 100 comprises a fluororesin substrate 20 and the film 10A for an adhesive layer. The film 10A for an adhesive layer has a thickness of 10-35 μm. The film 10A for an adhesive layer has a thermal expansion coefficient in the thickness direction of 110 ppm / °C or less after curing, and satisfies the following relational expression (1).　(1): X + Y ≤ 14,000 (In the relational expression (1), X is a value obtained by multiplying the thickness (μm) of the film 10A for an adhesive layer by the thermal expansion coefficient (ppm / °C) in the thickness direction after curing, Y is a value obtained by multiplying the thickness (μm) of the fluororesin substrate 20 by the thermal expansion coefficient (ppm / °C) in the thickness direction, and the thickness of the fluororesin substrate 20 is 50 μm or more.)

Description

Adhesive layer film, wiring board, multilayer wiring board, and semiconductor device.

[0001] The present invention relates to a film for an adhesive layer, a wiring board, a multilayer wiring board, and a semiconductor device.

[0002] In recent years, electronic devices have become smaller and more powerful, and there is a need for faster electrical signals used to transmit information. When transmitting high-speed electrical signals, signal loss occurs, and as the electrical signals become faster, the above-mentioned signal loss increases.

[0003] One known method for reducing signal loss during electrical signal transmission is to use low-dielectric materials for circuit boards. The use of low-dielectric materials can reduce signal loss, and there has been an increase in the use of fluororesin substrates for circuit boards.

[0004] In addition, the use of multilayered and highly integrated circuit boards for high-frequency communications is also being considered. For example, by incorporating a film for an interlayer adhesive layer, such as a bonding sheet, into a multilayered board, high-speed communication in electronic communication devices is possible. Hereinafter, the "film for an interlayer adhesive layer" may be simply referred to as an "interlayer adhesive film" or "adhesive layer film." A circuit board that is multilayered together with an interlayer adhesive film is also referred to as a multilayer wiring board.

[0005] Furthermore, there is an increasing demand for low dielectric properties for the interlayer adhesive film itself used in multilayer wiring boards. As a resin composition used in the production of the interlayer adhesive film, for example, a thermosetting resin composition containing a specific vinyl compound and rubber and / or a thermoplastic elastomer has been proposed (see, for example, Patent Document 1).

[0006] International Publication No. 2008 / 018483

[0007] In a multilayer wiring board, a through-hole portion is provided, which is made up of a through-hole formed through the wiring board and a plating layer disposed on the inner surface of the through-hole, for the purpose of connecting to a core substrate having a conductor pattern. The conductor patterns in the multilayer wiring board are connected to each other via the plating layer in the through-hole portion.

[0008] In multilayer wiring boards using fluororesin substrates, the connection reliability of through-holes has often been a problem. For example, the connection reliability of multilayer wiring boards can be evaluated by reliability tests such as a thermal cycle test. Then, an interlayer adhesive film was prepared using a thermosetting resin composition as described in Patent Document 1, and the above-mentioned thermal cycle test was performed on a multilayer wiring board including an interlayer insulating film made of the interlayer adhesive film and a fluororesin substrate. However, breakage was easily generated in the plating layer of the through-holes, making it difficult to obtain sufficient connection reliability.

[0009] For this reason, there is a strong demand for the development of an adhesive layer film that can effectively prevent breakage of the plating layer disposed on the inner surface of a through hole, as an adhesive layer film intended for use in multilayer wiring boards using fluororesin substrates.

[0010] The present invention has been made in consideration of the problems of the prior art. The present invention provides a film for an adhesive layer that can be used in the production of a multilayer wiring board including a fluororesin substrate and that can suppress fracture of a plating layer disposed on the inner surface of a through hole formed in the multilayer wiring board. The present invention also provides a wiring board, a multilayer wiring board, and a semiconductor device that include the above-mentioned film for an adhesive layer that can effectively suppress fracture of a plating layer disposed on the inner surface of a through hole formed in the multilayer wiring board.

[0011] As a result of extensive research to achieve the above-mentioned object, the inventors have discovered that when an adhesive layer film has a specific thickness (μm) and a specific thickness-direction thermal expansion coefficient (ppm / °C), fracture of the plating layer disposed on the inner surface of a through-hole in a multilayer wiring board can be suppressed under the following specific conditions, leading to the completion of the invention. The specific conditions are: First, let X be the product of the thickness (μm) of the adhesive layer film and the thickness-direction thermal expansion coefficient (ppm / °C) of the cured product; And, let Y be the product of the thickness (μm) of the fluororesin substrate laminated with the adhesive layer film and the thickness-direction thermal expansion coefficient (ppm / °C). By keeping the sum of X and Y below a certain value, fracture of the plating layer disposed on the inner surface of a through-hole can be effectively suppressed. That is, according to the present invention, the adhesive layer film, wiring board, multilayer wiring board, and semiconductor device shown below are provided.

[0012] [1] An adhesive layer film used in the production of a multilayer wiring board, the multilayer wiring board comprising at least a fluororesin substrate and the adhesive layer film, wherein the thickness of the adhesive layer film is 10 to 35 μm, the thermal expansion coefficient of the adhesive layer film in the thickness direction after curing is 110 ppm / °C or less, and the adhesive layer film satisfies the following relational expression (1): X+Y≦14000 (1) (wherein, in the relational expression (1), X is the value obtained by multiplying the thickness (μm) of the adhesive layer film by the thermal expansion coefficient (ppm / °C) in the thickness direction after curing, Y is the value obtained by multiplying the thickness (μm) of the fluororesin substrate by the thermal expansion coefficient (ppm / °C) in the thickness direction, and the thickness of the fluororesin substrate is 50 μm or more.)

[0013] [2] The film for an adhesive layer according to [1], which is used for lamination with the fluororesin substrate having a thickness of 50 to 135 μm, and the thermal expansion coefficient in the thickness direction of the fluororesin substrate is 110 ppm / °C or less.

[0014] [3] The film for adhesive layers according to [1] or [2], wherein the dielectric loss tangent of the cured product measured at 25°C and 10 GHz is 0.0021 or less.

[0015] [4] The film for an adhesive layer according to any one of [1] to [3], wherein the dielectric loss tangent of the cured product measured under conditions of 25°C and 80 GHz is 0.0027 or less.

[0016] [5] The film for adhesive layers according to any one of [1] to [4] above, which is made of a resin composition containing at least (A) a thermosetting resin, (B) a thermoplastic elastomer, and (C) an inorganic filler.

[0017] [6] The film for an adhesive layer according to [5], containing a modified polyphenylene ether resin as the component (A).

[0018] [7] A wiring board comprising a fluororesin substrate and the film for an adhesive layer according to any one of [1] to [6] above.

[0019] [8] A wiring board comprising a fluororesin substrate and an adhesive layer film disposed on the fluororesin substrate, wherein the adhesive layer film has a thickness of 10 to 35 μm, the adhesive layer film has a thermal expansion coefficient in the thickness direction after curing of 110 ppm / °C or less, the fluororesin substrate has a thickness of 50 μm or more, and satisfies the following relational expression (2): X+Y≦14000 (2) (where, in the relational expression (2), X is the value obtained by multiplying the thickness (μm) of the adhesive layer film by the thermal expansion coefficient in the thickness direction after curing (ppm / °C), and Y is the value obtained by multiplying the thickness (μm) of the fluororesin substrate by the thermal expansion coefficient in the thickness direction (ppm / °C).)

[0020] [9] The wiring board according to [8], wherein the thickness of the fluororesin substrate is 50 to 135 μm, and the thermal expansion coefficient of the fluororesin substrate in the thickness direction is 110 ppm / ° C. or less.

[0021]

[10] The wiring board according to any one of [7] to [9], wherein the sum of the thickness (μm) of the fluororesin substrate and the thickness (μm) of the adhesive layer film is 60 to 160 μm.

[0022]

[11] A multilayer wiring board in which two or more wiring boards according to any one of [7] to

[10] are stacked.

[0023]

[12] The multilayer wiring board according to

[11] , wherein the total number of laminated layers is 8 or more when the wiring board is one layer.

[0024]

[13] The multilayer wiring board according to

[11] or

[12] , wherein the wiring board has at least one or more through holes penetrating the wiring board, and a plating layer is disposed on the inner surface of the through hole, and the following relational expression (3) is satisfied: 0.1≦(X+Y) / Z≦2.0 (3) (wherein, in relational expression (3), X is the value obtained by multiplying the thickness (μm) of the adhesive layer film by the thermal expansion coefficient (ppm / °C) in the thickness direction after curing, Y is the value obtained by multiplying the thickness (μm) of the fluororesin substrate by the thermal expansion coefficient (ppm / °C) in the thickness direction, and Z is the value obtained by multiplying the diameter (μm) of the through hole by the thickness (μm) of the plating layer disposed on the inner surface of the through hole.)

[0025]

[14] The multilayer wiring board according to

[13] , wherein the through-hole has a diameter of 100 to 600 μm and the plating layer has a thickness of 15 to 35 μm.

[0026]

[15] A semiconductor device comprising the multilayer wiring substrate according to any one of

[11] to

[14] .

[0027] The adhesive layer film of the present invention can be used in the production of a multilayer wiring board including a fluororesin substrate, and has the effect of effectively suppressing breakage of a plating layer disposed on the inner surface of a through hole formed in the multilayer wiring board. Furthermore, the wiring board, multilayer wiring board, and semiconductor device of the present invention include the above-mentioned adhesive layer film of the present invention or a cured product thereof, and enjoy the effects of the present invention described so far.

[0028] 1 is a cross-sectional view schematically showing a multilayer wiring board using the film for adhesive layer of the first embodiment of the present invention as an adhesive layer, and FIG. 2 is an enlarged plan view of a through hole provided in the multilayer wiring board shown in FIG. 1, seen from the opening end side, and FIG. 3 is a cross-sectional view schematically showing a wiring board used in the multilayer wiring board shown in FIG.

[0029] While the present invention will be described below with reference to exemplary embodiments, it should be understood that the present invention is not limited to the following exemplary embodiments. Therefore, it should be understood that modifications and improvements to the following exemplary embodiments, based on the ordinary knowledge of those skilled in the art, are also within the scope of the present invention, provided that they do not deviate from the spirit of the present invention.

[0030] [Film for Adhesive Layer] A first embodiment of the film for adhesive layer of the present invention is a film for adhesive layer 10A used in producing a multilayer wiring board 100 as shown in Fig. 1. Here, Fig. 1 is a cross-sectional view schematically showing a multilayer wiring board 100 using the film for adhesive layer 10A of the first embodiment of the present invention as an adhesive layer 10.

[0031] Here, a description will be given of the multilayer wiring board 100 shown in Fig. 1. The multilayer wiring board 100 includes a fluororesin substrate 20 having a conductor pattern 21 formed on at least one surface thereof, and an adhesive layer 10 for adhering the fluororesin substrate 20. The adhesive layer 10 is formed by using the adhesive layer film 10A of this embodiment as an interlayer bonding sheet or interlayer adhesive for a multilayer wiring board.

[0032] In the multilayer wiring board 100 shown in FIG. 1 , a wiring board 30 is formed by a fluororesin substrate 20 and an adhesive layer film 10A, and two or more such wiring boards 30 are laminated together. As shown in FIGS. 1 and 2 , the multilayer wiring board 100 may be provided with at least one through hole 40 formed to penetrate the multilayer wiring board 100, as needed. A plating layer 41 is disposed on the inner surface of the through hole 40, and electrical connection is made between the conductor patterns 21 of the laminated wiring boards 30. Furthermore, as shown in FIG. 1 , the multilayer wiring board 100 may be provided with a core substrate 50. FIG. 2 is an enlarged plan view of a through hole provided in the multilayer wiring board shown in FIG. 1 , viewed from the opening end side.

[0033] The adhesive layer film 10A of this embodiment has a thickness of 10 to 35 μm, a thermal expansion coefficient in the thickness direction of the adhesive layer film 10A after curing of 110 ppm / °C or less, and satisfies the following relational expression (1): When the adhesive layer film 10A of this embodiment configured in this manner is used to fabricate a multilayer wiring board 100 including a fluororesin substrate 20, it can effectively suppress fracture of the plating layer 41 disposed on the inner surface of the through hole 40 formed in the multilayer wiring board 100. Hereinafter, the plating layer 41 disposed on the inner surface of the through hole 40 may be referred to as the "plating layer 41 disposed in the through hole 40" or simply as the "plating layer 41."

[0034] X+Y≦14000 (1)

[0035] In the above relational expression (1), X is the value obtained by multiplying the thickness (μm) of the adhesive layer film 10A by the thermal expansion coefficient (ppm / °C) in the thickness direction after curing. Y is the value obtained by multiplying the thickness (μm) of the fluororesin substrate 20 by the thermal expansion coefficient (ppm / °C) in the thickness direction. In addition, in the multilayer wiring board 100 in which the adhesive layer film 10A of this embodiment is used, the thickness of the fluororesin substrate 20 is 50 μm or more.

[0036] The adhesive layer film 10A has the above-mentioned specific thickness (μm) and specific thermal expansion coefficient (ppm / °C), and is configured so that the value of X+Y in the above relational expression (1) is not more than 14000. When the adhesive layer film 10A is used to fabricate a multilayer wiring board 100 including a fluororesin substrate 20, it can effectively suppress fracture of the plating layer 41 disposed in the through hole 40.

[0037] The upper limit of the value of X + Y in the above relational expression (1) is 14,000. However, from the viewpoint of more effectively suppressing fracture of the plating layer 41, the upper limit of the value of X + Y may be 13,500, 13,000, 12,000, 10,000, 9,000, 8,000, or 7,000. There is no particular limitation on the lower limit of the value of X + Y. A realistically possible value for the lower limit of X + Y is preferably 3,000 or more, more preferably 3,500 or more, and even more preferably 4,000 or more. Furthermore, from the same viewpoint as the above-mentioned upper limit, the lower limit of the value of X + Y may be 4,500, 5,000, or 5,500. Here, a suitable combination of the upper and lower limits of X + Y may be any value selected from the above-mentioned multiple upper limits and any value selected from the above-mentioned multiple lower limits. For example, although not particularly limited, the value of X+Y in relational formula (1) is preferably 3,000 to 14,000, more preferably 3,000 to 13,500, even more preferably 3,500 to 10,000, and particularly preferably 4,000 to 8,000.

[0038] The adhesive layer film 10A has a thickness of 10 to 35 μm. From the viewpoint of miniaturization of electronic devices, the thickness of the adhesive layer film 10A is preferably 10 to 30 μm, more preferably 10 to 25 μm, and even more preferably 10 to 20 μm. Hereinafter, unless otherwise specified, the "thickness" of the adhesive layer film 10A refers to the thickness of the adhesive layer film 10A before thermal curing.

[0039] For example, when a support is attached to the adhesive layer film 10A, the support is peeled off from the adhesive layer film 10A, leaving the adhesive layer film 10A in a stand-alone state, and the thickness of the adhesive layer film 10A is measured. The thickness of the adhesive layer film 10A can be determined, for example, by measuring any nine points on the adhesive layer film 10A using a contact film thickness meter and calculating the average value of the nine measured points. As a contact film thickness meter, for example, a "Millitron 1240" manufactured by Marl Corporation can be used.

[0040] The adhesive layer film 10A has a thermal expansion coefficient in the thickness direction after curing of 110 ppm / °C or less. Hereinafter, unless otherwise specified, the "thermal expansion coefficient (ppm / °C)" of the adhesive layer film 10A means the thermal expansion coefficient (ppm / °C) in the thickness direction of the adhesive layer film 10A after curing. The "thermal expansion coefficient (ppm / °C) of the adhesive layer film 10A in the thickness direction after curing" may sometimes be simply referred to as the "thermal expansion coefficient (ppm / °C) of the adhesive layer film 10A in the thickness direction" or the "thermal expansion coefficient (ppm / °C) of the adhesive layer film 10A."

[0041] The thermal expansion coefficient of the adhesive layer film 10A in the thickness direction is preferably 105 ppm / °C or less, more preferably 100 ppm / °C or less, and even more preferably 90 ppm / °C or less, from the viewpoint of suppressing fracture of the plating layer 41 disposed in the through-hole 40 of the multilayer wiring board 100. The lower limit of the thermal expansion coefficient of the adhesive layer film 10A in the thickness direction is not particularly limited, but from a practical viewpoint, it may be 1 ppm / °C or more, 5 ppm / °C or more, 10 ppm / °C or more, or 20 ppm / °C or more. For example, although not particularly limited, the thermal expansion coefficient of the adhesive layer film 10A in the thickness direction is preferably 1 to 110 ppm / °C, more preferably 1 to 105 ppm / °C, even more preferably 1 to 100 ppm / °C, and particularly preferably 5 to 90 ppm / °C.

[0042] The thermal expansion coefficient in the thickness direction of the adhesive layer film 10A after curing can be measured, for example, by the following method. First, the adhesive layer film 10A is stacked so that the thickness of the laminate after curing is 2 mm, and the laminate is sandwiched between release-treated polyethylene terephthalate (hereinafter referred to as "PET") films on both sides. The adhesive layer film 10A is then thermally cured by vacuum hot pressing under conditions of 200°C, 60 min, and 1 MPa. The PET films on both sides are then peeled off to obtain a cured adhesive layer film 10A. The obtained cured product is cut into test pieces 7 mm wide and 7 mm long, and thermomechanical analysis is performed in compression mode using a thermomechanical analyzer (manufactured by Bruker AXS under the trade name "TMA4000SA"). For the thermomechanical analysis, a test piece is mounted in the thermomechanical analyzer, and measurements are performed twice consecutively under the measurement conditions of a load of 1 g and a temperature increase rate of 5°C / min, and the average thermal expansion coefficient (ppm / °C) from 30°C to 150°C in the second measurement is calculated. The average thermal expansion coefficient (ppm / °C) from 30°C to 150°C calculated in this way is defined as the thermal expansion coefficient (ppm / °C) in the thickness direction of the adhesive layer film 10A after curing.

[0043] In the above relational expression (1), X is the value obtained by multiplying the thickness (μm) of the adhesive layer film 10A by the thermal expansion coefficient (ppm / °C) in the thickness direction after curing. As is clear from the numerical ranges of the thermal expansion coefficient (ppm / °C) and thickness (μm) of the adhesive layer film 10A described above, the value that X can take in relational expression (1) is a positive number of 3850 or less. For example, although there are no particular limitations, from the above-mentioned practical viewpoint, the value that X can essentially take is 10 to 3850. From the viewpoint of suppressing breakage of the plating layer 41 disposed in the through-hole 40 of the multilayer wiring board 100, the value of X is preferably 10 to 3500, and more preferably 10 to 3200.

[0044] In some embodiments, the adhesive layer film 10A preferably has excellent dielectric properties. For example, low dielectric loss at 1 to 100 GHz can suppress electrical signal loss in high-frequency, high-speed telecommunications. For example, the adhesive layer film 10A preferably has a dielectric dissipation factor of 0.0021 or less, more preferably 0.0020 or less, even more preferably 0.0019 or less, and particularly preferably 0.0018 or less, when measured at 25°C and 80 GHz. Furthermore, the adhesive layer film 10A preferably has a dielectric dissipation factor of 0.0027 or less, more preferably 0.0026 or less, even more preferably 0.0025 or less, and particularly preferably 0.0024 or less, when measured at 25°C and 80 GHz.

[0045] The dielectric loss tangent of the cured adhesive layer film 10A can be measured, for example, by the following method. First, the adhesive layer film 10A is sandwiched between release-treated polyethylene terephthalate (hereinafter referred to as "PET") films on both sides and thermally cured in a press. The thermal curing conditions are not particularly limited, but examples include conditions of 200°C, 60 min, and 1 MPa. The PET films disposed on both sides of the thermally cured adhesive layer film 10A are then removed, and a test piece with one side measuring 50±0.5 mm and the other side measuring 100±2 mm is cut from the thermally cured adhesive layer film 10A. The dielectric loss tangent at 10 GHz is defined as the dielectric loss tangent (tanδ) of the cut test piece measured using the SPDR method at 25°C and 10 GHz. The dielectric loss tangent under the condition of 80 GHz is the dielectric loss tangent (tan δ) measured at 25° C. and 80 GHz using a cut-out test piece with a balanced disk resonator.

[0046] [Composition of Adhesive Layer Film] The composition of the adhesive layer film 10A is not particularly limited as long as it satisfies the properties of the adhesive layer film 10A described above. For example, examples of the composition of the adhesive layer film 10A that can satisfy the above properties are shown below.

[0047] The adhesive layer film 10A may be made of a resin composition containing at least (A) a thermosetting resin, (B) a thermoplastic elastomer, and (C) an inorganic filler. Hereinafter, the (A) thermosetting resin may be referred to as the (A) component. Similarly, the (B) thermoplastic elastomer may be referred to as the (B) component, and the (C) inorganic filler may be referred to as the (C) component.

[0048] [Component (A)] Examples of the thermosetting resin as component (A) include modified polyphenylene ether resin, bisphenol A type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, bismaleimide, special acrylate, modified polyimide, etc. The thermosetting resin as component (A) may be used alone or in combination of two or more types.

[0049] In particular, resins containing modified polyphenylene ether resins or modified polyimides are preferred as component (A) from the viewpoint of obtaining low dielectric properties. Furthermore, modified polyphenylene ether resins having ethylenically unsaturated groups at both ends are more preferred, as they have low polarity and high adhesion to fluororesins with low polarity. As the ethylenically unsaturated group, a styrene group is particularly preferred. Examples of such modified polyphenylene ether resins include the modified polyphenylene ether resins described in JP-A-2004-59644.

[0050] When the thermosetting resin as component (A) is an epoxy resin, it is preferable to further contain a curing agent. From the viewpoints of reaction temperature and reaction time, imidazole-based agents are preferred, and 1-benzyl-2-phenylimidazole and 2-phenyl-4,5-dihydroxymethylimidazole are more preferred. The curing agent may be used alone or in combination with two or more other agents. In this specification, the term "curing agent" includes not only curing agents in the narrow sense, but also compounds known as curing catalysts and curing accelerators.

[0051] [Component (B)] The thermoplastic elastomer used as component (B) is not particularly limited, but examples include block copolymers containing a block of styrene or its analog as at least one terminal block and an elastomer block of a conjugated diene as at least one intermediate block. Examples include styrene / butadiene / styrene block copolymer (SBS), styrene / butadiene / butylene / styrene block copolymer (SBBS), styrene / ethylene / butylene / styrene block copolymer (SEBS), and styrene / ethylene / ethylene / propylene / styrene block copolymer (SEEPS). The inclusion of a styrene-based thermoplastic elastomer imparts flexibility to the resin composition, maintains the toughness of the cured product, improves adhesion, and provides excellent dielectric properties. The thermoplastic elastomer used as component (B) may be used alone or in combination of two or more types.

[0052] [Component (C)] The inorganic filler as component (C) is not particularly limited, but examples thereof include silica, alumina, glass, cordierite, silicon oxide, barium sulfate, talc, clay, mica powder, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, boron nitride, aluminum nitride, manganese nitride, aluminum borate, barium titanate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, titanium oxide, barium zirconate, calcium zirconate, zirconium phosphate, and zirconium tungstate phosphate.

[0053] Among the inorganic fillers used as component (C) above, silica is preferred from the viewpoint of reducing the thermal expansion coefficient. Furthermore, alumina and boron nitride are preferred from the viewpoint of improving thermal conductivity. Preferred silicas include amorphous silica, pulverized silica, fused silica, crystalline silica, synthetic silica, and hollow silica, with fused silica being more preferred. Furthermore, spherical silica is preferred. These may be used alone or in combination of two or more.

[0054] From the viewpoint of further reducing the transmission loss of the multilayer wiring substrate 100, the resin composition used to prepare the adhesive layer film 10A preferably contains a filler having a dielectric dissipation factor of 0.002 or less. Examples of fillers having a dielectric dissipation factor of 0.002 or less include silica fillers as the inorganic filler (C). Such silica fillers include hollow silica particles. On the other hand, examples of fillers other than the component (C) include fluororesin fillers.

[0055] The average particle size of the inorganic filler as component (C) is not particularly limited, but is preferably 0.01 to 10 μm, and more preferably 0.01 to 5 μm. Here, the average particle size can be measured using a laser diffraction particle size distribution analyzer (model number: LS13320) manufactured by Beckman Coulter. The inorganic filler as component (C) may be used alone or in combination of two or more types.

[0056] [Other Components] In addition to the components (A), (B), and (C) described above, the resin composition may further contain other components as needed, as long as the object of the present invention is not impaired. For example, other components include additives such as crosslinking agents (e.g., polybutadiene, L-DAIC or TAIC manufactured by Shikoku Chemical Industries Co., Ltd.), coupling agents, peroxides, flame retardants, leveling agents, antifoaming agents, thixotropic agents, antioxidants, pigments, and dyes. The types and amounts of each of these additives are the same as in conventional methods.

[0057] The blending ratios of components (A) to (C) contained in the resin composition are not particularly limited. For example, the blending ratios can be adjusted appropriately to satisfy the properties of the adhesive layer film 10A described above, particularly to achieve a predetermined thermal expansion coefficient (ppm / °C) in the thickness direction after curing. For example, although not particularly limited, the thermosetting resin (component (A)) is preferably contained in the resin composition in an amount of 5 to 40 parts by mass, more preferably 10 to 35 parts by mass. Furthermore, the thermoplastic elastomer (component (B)) is preferably contained in the resin composition in an amount of 10 to 45 parts by mass, more preferably 15 to 40 parts by mass. Furthermore, the inorganic filler (component (C)) is preferably contained in the resin composition in an amount of 15 to 85 parts by mass, more preferably 25 to 75 parts by mass.

[0058] [Fluororesin Substrate] Next, the fluororesin substrate 20 that is laminated together with the adhesive layer film 10A in the multilayer wiring substrate 100 will be described.

[0059] 3, the fluororesin substrate 20 can be used as a wiring substrate 30 including the fluororesin substrate 20 and an adhesive layer film 10A disposed on the fluororesin substrate 20. Fig. 3 is a cross-sectional view schematically showing the wiring substrate 30 used in the multilayer wiring substrate 100 shown in Fig. 1.

[0060] In the multilayer wiring board 100 in which the adhesive layer film 10A of this embodiment is used, the thickness of the fluororesin substrate 20 laminated with the adhesive layer film 10A is 50 μm or more. When the value obtained by multiplying the thickness (μm) of the fluororesin substrate 20 by the thermal expansion coefficient (ppm / °C) in the thickness direction is defined as Y, the adhesive layer film 10A of this embodiment is configured to satisfy the above-mentioned relational expression (1).

[0061] The thickness of the fluororesin substrate 20 laminated together with the adhesive layer film 10A may be 50 μm or more, but from the viewpoint of miniaturization of electronic devices, it is preferably 50 to 135 μm, and more preferably 50 to 130 μm.

[0062] The thermal expansion coefficient in the thickness direction of the fluororesin substrate 20 is preferably 110 ppm / °C or less. For this reason, the adhesive layer film 10A of this embodiment is suitably used for lamination with a fluororesin substrate 20 having a thickness of 50 to 135 μm, and the thermal expansion coefficient in the thickness direction of the fluororesin substrate 20 is preferably 110 ppm / °C or less.

[0063] The thickness of the fluororesin substrate 20 can be measured in the same manner as in the film for adhesive layer 10A described above. However, when the fluororesin substrate 20 has a copper foil laminated to one or both sides thereof to form a conductive pattern 21, the thickness of the fluororesin substrate 20 can be measured after removing the copper foil conductive pattern 21 using an etching solution and drying.

[0064] The thermal expansion coefficient in the thickness direction of the fluororesin substrate 20 can also be measured in the same manner as for the adhesive layer film 10A described above. However, if copper foil is bonded to both sides or one side of the fluororesin substrate 20 to form the conductive pattern 21, the thermal expansion coefficient can be measured after removing the conductive pattern 21 using the method described above. For example, the fluororesin substrate 20 is cut into test pieces 7 mm wide and 7 mm long, and thermomechanical analysis is performed in compression mode using a thermomechanical analyzer (manufactured by Bruker AXS under the trade name "TMA4000SA"). The test pieces are mounted in the thermomechanical analyzer and subjected to two consecutive measurements under the measurement conditions of a load of 1 g and a temperature rise rate of 5°C / min. The average thermal expansion coefficient (ppm / °C) from 30°C to 150°C in the second measurement is calculated. The average thermal expansion coefficient (ppm / °C) from 30°C to 150°C calculated in this manner is defined as the thermal expansion coefficient (ppm / °C) in the thickness direction of the fluororesin substrate 20.

[0065] From the viewpoint of suppressing fracture of the plating layer 41 disposed in the through-hole 40 of the multilayer wiring board 100 as shown in FIG. 1 , the thermal expansion coefficient of the fluororesin substrate 20 in the thickness direction is more preferably 105 ppm / °C or less, even more preferably 103 ppm / °C or less, and particularly preferably 100 ppm / °C or less. There is no particular restriction on the lower limit of the thermal expansion coefficient of the fluororesin substrate 20 in the thickness direction. For example, from a practical viewpoint, the lower limit of the thermal expansion coefficient of the fluororesin substrate 20 in the thickness direction may be 1 ppm / °C or more, 5 ppm / °C or more, 10 ppm / °C or more, or 20 ppm / °C or more. For example, although not particularly limited, the thermal expansion coefficient of the fluororesin substrate 20 in the thickness direction is preferably 1 to 110 ppm / °C, more preferably 1 to 105 ppm / °C, even more preferably 1 to 103 ppm / °C, and particularly preferably 5 to 100 ppm / °C.

[0066] As explained above, the value that X, which is the product of the thickness (μm) of the adhesive layer film 10A and the thermal expansion coefficient (ppm / °C) in the thickness direction after curing, can take, from a practical standpoint, is 10 to 3850. Therefore, in order for the adhesive layer film 10A to be laminated with the fluororesin substrate 20 to satisfy relational expression (1), the value that Y can take in relational expression (1) is a positive number of 13,990 or less. For example, although there are no particular limitations, the substantial value that Y can take from the above-mentioned practical standpoint is 50 to 13,990. Therefore, the adhesive layer film 10A of this embodiment is suitably used for lamination with a fluororesin substrate 20 for which the value of Y is 50 to 13,990.

[0067] From the viewpoint of suppressing fracture of the plating layer 41 disposed in the through hole 40 of the multilayer wiring board 100, the value of Y is preferably 50 to 13,500, more preferably 50 to 13,000, and even more preferably 50 to 12,500.

[0068] For example, those described in Japanese Patent Application Laid-Open Nos. 07-323501 and 2005-268365 can be used as the fluororesin substrate 20 laminated together with the adhesive layer film 10A in the multilayer wiring board 100. Specific examples include a rigid substrate made of a prepreg in which polytetrafluoroethylene (PTFE) is impregnated into glass cloth, and a so-called paper sheet formed by a wet papermaking method using fluororesin fiber and heat-resistant insulating fiber such as glass fiber.

[0069] Examples of fluororesins used in the fluororesin substrate 20 include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer (FEPPFA), FEP, polychlorotrifluoroethylene (PCTFE), vinylidene fluoride resin (PVDF), polyvinyl fluoride resin (PVF), ethylene-tetrafluoroethylene copolymer (ETFE), and ethylene-chlorotrifluoroethylene copolymer (ECTFE). From the viewpoints of low dielectric constant, low dielectric loss tangent, heat resistance, chemical resistance, and the like, polytetrafluoroethylene (PTFE) is preferred. The fluororesins may be used alone or in combination of two or more.

[0070] Examples of heat-resistant insulating fibers used in the above-mentioned papermaking sheets include inorganic fibers such as glass fibers, silica fibers, alumina fibers, and aluminum silicate fibers, and organic fibers such as polyparaphenylene benzobisoxazole fibers (PBO fibers), aromatic polyester fibers, polyphenylene sulfide fibers, and wholly aromatic polyamide fibers. Glass fibers are preferred from the viewpoints of heat resistance, high strength, high elastic modulus, and low cost. The heat-resistant insulating fibers may be used alone or in combination of two or more types.

[0071] The fluororesin substrate 20 may have a conductive pattern 21 formed on at least one surface thereof. The conductive pattern 21 may be a copper wiring formed by etching a copper foil.

[0072] [Wiring Board] Next, an embodiment of the wiring board of the present invention will be described. As shown in FIG. 3, the wiring board of this embodiment includes a fluororesin substrate 20 and an adhesive layer film 10A disposed on the fluororesin substrate 20. The adhesive layer film 10A of this embodiment described above can be used as the adhesive layer film 10A. As for the fluororesin substrate 20, the fluororesin substrate 20 used for laminating with the adhesive layer film 10A of this embodiment described above can also be used. For example, two or more wiring substrates 30 of this embodiment are laminated to form a multilayer wiring board 100 as shown in FIG. 1. The adhesive layer film 10A serves as the adhesive layer 10 for adhering the fluororesin substrate 20 in the multilayer wiring board 100.

[0073] 3, the adhesive layer film 10A and the fluororesin substrate 20 satisfy the following relational expression (2): the thickness of the adhesive layer film 10A is 10 to 35 μm, and the thermal expansion coefficient of the adhesive layer film 10A in the thickness direction after curing is 110 ppm / °C or less. Also, the thickness of the fluororesin substrate 20 is 50 μm or more.

[0074] X+Y≦14000 (2)

[0075] In the above relational expression (2), X is the value obtained by multiplying the thickness (μm) of the adhesive layer film 10A by the thermal expansion coefficient (ppm / °C) in the thickness direction after curing. Y is the value obtained by multiplying the thickness (μm) of the fluororesin substrate 20 by the thermal expansion coefficient (ppm / °C) in the thickness direction. Preferred aspects of the adhesive layer film 10A and the fluororesin substrate 20 used in the wiring board 30 are as described for the adhesive layer film 10A of this embodiment.

[0076] In the wiring board 30, the sum of the thickness of the adhesive layer film 10A and the thickness of the fluororesin substrate 20 is preferably 60 to 160 μm, more preferably 70 to 160 μm, and even more preferably 80 to 160 μm.

[0077] [Multilayer Wiring Board] Next, an embodiment of the multilayer wiring board of the present invention will be described. As shown in Fig. 1, the multilayer wiring board 100 of this embodiment is formed by laminating two or more wiring substrates 30 each including a fluororesin substrate 20 and an adhesive layer film 10A.

[0078] 1 includes a fluororesin substrate 20 having a conductor pattern 21 formed on at least one surface thereof, and an adhesive layer 10 for bonding the fluororesin substrate 20. The adhesive layer 10 for bonding the fluororesin substrate 20 is made of a cured product of the adhesive layer film 10A of the present embodiment described above.

[0079] For example, when a wiring board 30 obtained by laminating an adhesive layer film 10A and a fluororesin substrate 20 is counted as one layer, the total number of laminated layers in the multilayer wiring board 100 is preferably 8 or more. The multilayer wiring board 100 may include a core substrate 50, and copper foil (e.g., a conductor pattern 21) may be provided on at least one outermost layer of the multilayer wiring board 100.

[0080] If necessary, the multilayer wiring board 100 may be provided with at least one through hole 40 formed so as to penetrate the multilayer wiring board 100. A plating layer 41 is disposed on the inner surface of the through hole 40, and electrical connection is made between the conductor patterns 21 of the stacked wiring boards 30.

[0081] There are no particular limitations on the method for processing the through-holes 40, and they can be made by known methods such as NC drilling, laser drilling, chemical etching, plasma etching, etc. There are also no particular limitations on the type (e.g., plating material) or plating formation method of the plating layer disposed inside the through-holes 40 (i.e., on the inner surface of the through-holes 40).

[0082] In the multilayer wiring board 100, the larger the diameter D3 of the through hole 40 (see, for example, FIG. 2 ), the smaller the stress applied to the plating layer 41 disposed in the through hole 40. Therefore, from the viewpoint of reducing the stress applied to the plating layer 41 disposed in the through hole 40, it can be said that a large diameter D3 of the through hole 40 is preferable. However, on the other hand, from the viewpoint of miniaturizing a semiconductor device including the multilayer wiring board 100, it can also be said that it is preferable not to make the diameter D3 of the through hole 40 excessively large, but to keep it within a certain size. Therefore, the diameter D3 of the through hole 40 is preferably 100 to 600 μm, more preferably 100 to 500 μm, and even more preferably 200 to 500 μm.

[0083] Furthermore, from the viewpoint of easily achieving the effect of "suppressing fracture of the plating layer 41" achieved by the adhesive layer film 10A described above, the thickness T3 of the plating layer 41 (see, for example, FIG. 2) is preferably 15 μm or more, and more preferably 20 μm or more. There is no particular upper limit to the thickness T3 of the plating layer 41, but in relation to the preferred diameter D3 of the through hole 40, it may be 35 μm or less, or 30 μm or less. Therefore, the thickness T3 of the plating layer 41 is preferably 15 to 35 μm, more preferably 15 to 30 μm, and even more preferably 20 to 30 μm.

[0084] When the through-holes 40 are provided in the multilayer wiring board 100, the multilayer wiring board 100 preferably satisfies the following relational expression (3).

[0085] 0.1≦(X+Y) / Z≦2.0 (3)

[0086] In the above relational expression (3), X is the value obtained by multiplying the thickness (μm) of the adhesive layer film 10A by the thermal expansion coefficient (ppm / °C) in the thickness direction after curing. Y is the value obtained by multiplying the thickness (μm) of the fluororesin substrate 20 by the thermal expansion coefficient (ppm / °C) in the thickness direction. Z is the value obtained by multiplying the diameter D3 (μm) of the through hole 40 by the thickness T3 (μm) of the plating layer 41 disposed on the inner surface of the through hole 40 (see, for example, FIG. 2 ).

[0087] As described above, in the above relational expression (3), Z is the product of the diameter D3 (μm) of the through hole 40 and the thickness T3 (μm) of the plating layer 41 disposed on the inner surface of the through hole 40. When "(X+Y) / Z" is within a certain numerical range as shown in the above relational expression (3), the effect of "suppressing fracture of the plating layer 41" described above is extremely effectively achieved. That is, when "(X+Y) / Z" is 0.1 to 2.0, fracture of the plating layer 41 disposed on the through hole 40 in the multilayer wiring board 100 can be more effectively suppressed. Note that the same effect as that of the present invention can also be achieved with via holes intended for interlayer conductivity in a multilayer board. For example, although not shown, a plating layer is disposed on the inner surface of a via hole provided in a wiring board, similar to the through hole 40 (see FIG. 1), and according to the present invention, stress on the plating layer disposed on the inner surface of the via hole can also be reduced.

[0088] Suitable upper limits of "(X+Y) / Z" in the above relational formula (3) may be 1.8, 1.5, 1.0, or 0.5. Suitable lower limits of "(X+Y) / Z" in the above relational formula (3) may be 0.2, 0.3, or 0.4. Suitable combinations of the upper and lower limits of "(X+Y) / Z" include any suitable combination of a value selected from the above-described multiple upper limits and a value selected from the above-described multiple lower limits. For example, although not particularly limited, the value of "(X+Y) / Z" in the above relational formula (3) is preferably 0.2 to 1.8, more preferably 0.3 to 1.5, and even more preferably 0.4 to 1.0.

[0089] When the multilayer wiring board 100 satisfies the above relational expression (3), it is particularly preferable that the diameter D3 of the through-hole 40 is 100 to 600 μm and the thickness T3 of the plating layer 41 is 15 to 35 μm.

[0090] [Semiconductor Device] An embodiment of the semiconductor device of the present invention will be described. The semiconductor device of this embodiment includes the above-described multilayer wiring substrate. Examples of the semiconductor device include a server, a router, a communication terminal (such as a PC, a tablet terminal, or a smartphone), a millimeter-wave antenna, and a wireless base station.

[0091] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0092] (Examples 1 to 15, Comparative Examples 1 to 3) [Preparation of Film for Adhesive Layer] A varnish containing a resin composition for preparing a film for an adhesive layer was prepared by the following method. First, a thermosetting resin, a thermoplastic elastomer, an inorganic filler, a silane coupling agent, and a peroxide were prepared as raw material components. After weighing and blending the components, they were placed in a reaction vessel heated to 80°C and mixed at atmospheric pressure for 4 hours while rotating at a rotation speed of 150 rpm. When a peroxide was to be added, the peroxide was added after cooling.

[0093] In this example, three types of varnishes containing resin compositions were prepared by changing the formulation of each component. The resulting three types of varnishes were designated Varnish A, Varnish B, and Varnish C. Varnish A was prepared with 11.5 parts of thermosetting resin, 16.5 parts of thermoplastic elastomer, 71.5 parts of inorganic filler, 0.2 parts of silane coupling agent, and 0.3 parts of peroxide. Varnish B was prepared with 22.5 parts of thermosetting resin, 27.5 parts of thermoplastic elastomer, and 50.0 parts of inorganic filler. Varnish C was prepared with 31.5 parts of thermosetting resin, 38.5 parts of thermoplastic elastomer, and 30.0 parts of inorganic filler.

[0094] Next, the obtained varnish was applied to one side of a support (a PET film subjected to a release treatment) and dried at 100°C to obtain a support-attached adhesive layer film. Specifically, Film 1 having a thickness of 25 μm and Film 2 having a thickness of 15 μm were prepared using Varnish A. Film 3 having a thickness of 20 μm, Film 4 having a thickness of 25 μm, and Film 5 having a thickness of 30 μm were prepared using Varnish B. Film 6 having a thickness of 25 μm and Film 7 having a thickness of 30 μm were prepared using Varnish C. The thicknesses of Films 1 to 7 were determined by measuring any nine points on each film using a contact film thickness meter and calculating the average value of the nine measured points. A contact film thickness meter, trade name "Millitron 1240" manufactured by Marl, was used.

[0095] Furthermore, for Films 1 to 7, the thermal expansion coefficient (ppm / ° C.) in the thickness direction after curing and the dielectric loss tangent (tan δ) after curing were measured by the following methods.

[0096] [Thermal Expansion Coefficient (ppm / °C)] First, each of the prepared films 1 to 7 was temporarily bonded to a fluororesin substrate described below using vacuum thermal lamination to prepare a temporary bonded product. The resulting temporary bonded products were stacked so that the thickness of the laminate after curing was 2 mm, and each film was thermally cured by vacuum hot pressing under conditions of 200°C, 60 min, and 1 MPa. The fluororesin substrate was then peeled off to obtain a cured product of each film. The resulting cured product was cut into test pieces with a width of 7 mm and a length of 7 mm, and thermomechanical analysis was performed in compression mode using a thermomechanical analyzer (manufactured by Bruker AXS, trade name "TMA4000SA"). For the thermomechanical analysis, the test pieces were mounted in the thermomechanical analyzer described above, and measurements were performed twice consecutively under measurement conditions of a load of 1 g and a heating rate of 5°C / min. The average thermal expansion coefficient (ppm / °C) from 30°C to 150°C in the second measurement was calculated. The average thermal expansion coefficient (ppm / °C) from 30°C to 150°C calculated in this manner was used as the thermal expansion coefficient (ppm / °C) in the thickness direction of each film after curing. The thermal expansion coefficient (ppm / °C) of the fluororesin substrate described below was also calculated from 30°C to 150°C under the same conditions using the thermomechanical analyzer, and the calculated value was used as the thermal expansion coefficient (ppm / °C) in the thickness direction of the fluororesin substrate.

[0097] [Dielectric Loss Tangent (tanδ)] First, each of the prepared films 1 to 7 was sandwiched between release-treated PET films on both sides and heat-cured in a press. The heat-curing conditions were 200°C, 60 min, and 1 MPa. The PET films on both sides of the heat-cured film were then removed, and test pieces measuring 50±0.5 mm on one side and 100±2 mm on the other side were cut out from the heat-cured film. The cut test pieces were measured using the SPDR method at 25°C and 10 GHz to determine the dielectric loss tangent (tanδ) of the heat-cured film at 10 GHz. The cut test pieces were also measured using a balanced disk resonator at 25°C and 80 GHz to determine the dielectric loss tangent (tanδ) of the heat-cured film at 80 GHz.

[0098] The structures of the prepared films 1 to 7 are shown below. The thermal expansion coefficient and dielectric loss tangent in the thickness direction of each film were measured using a cured product obtained by thermally curing each film, as shown in the measurement method described above. Film 1 (thickness: 25 μm, thermal expansion coefficient in the thickness direction: 48 ppm / °C, dielectric dissipation factor at 10 GHz: 0.0016, dielectric dissipation factor at 80 GHz: 0.0021) Film 2 (thickness: 15 μm, thermal expansion coefficient in the thickness direction: 48 ppm / °C, dielectric dissipation factor at 10 GHz: 0.0016, dielectric dissipation factor at 80 GHz: 0.0021) Film 3 (thickness: 20 μm, thermal expansion coefficient in the thickness direction: 107 ppm / °C, dielectric dissipation factor at 10 GHz: 0.0010, dielectric dissipation factor at 80 GHz: 0.0018) Film 4 (thickness: 25 μm, thermal expansion coefficient in the thickness direction: 107 ppm / °C, dielectric dissipation factor at 10 GHz: 0.0010, dielectric dissipation factor at 80 GHz: 0.0018) Film 5 (thickness: 30 μm, thermal expansion coefficient in the thickness direction: 107 ppm / °C, dielectric dissipation factor at 10 GHz: 0.0010, dielectric dissipation factor at 80 GHz: 0.0018) Film 6 (thickness: 25 μm, thermal expansion coefficient in the thickness direction: 166 ppm / °C, dielectric dissipation factor at 10 GHz: 0.0011, dielectric dissipation factor at 80 GHz: 0.0018) Film 7 (thickness: 30 μm, thermal expansion coefficient in the thickness direction: 166 ppm / °C, dielectric dissipation factor at 10 GHz: 0.0011, dielectric dissipation factor at 80 GHz: 0.0018)

[0099] [Preparation of Fluororesin Substrates] As the fluororesin substrates, fluororesin substrates (PTFE1 to PTFE5) made of polytetrafluoroethylene (PTFE) having the following properties were prepared. Fluororesin substrate; PTFE1 (PTFE substrate, thickness: 127 μm, thermal expansion coefficient in thickness direction: 96 ppm / °C) Fluororesin substrate; PTFE2 (PTFE substrate, thickness: 127 μm, thermal expansion coefficient in thickness direction: 39 ppm / °C) Fluororesin substrate; PTFE3 (PTFE substrate, thickness: 75 μm, thermal expansion coefficient in thickness direction: 73 ppm / °C) Fluororesin substrate; PTFE4 (PTFE substrate, thickness: 75 μm, thermal expansion coefficient in thickness direction: 101 ppm / °C) Fluororesin substrate; PTFE5 (PTFE substrate, thickness: 127 μm, thermal expansion coefficient in thickness direction: 25 ppm / °C)

[0100] [Preparation of Multilayer Wiring Boards] Multilayer wiring boards were prepared using adhesive layer films (Films 1 to 7) and fluororesin substrates (PTFE 1 to 5). The procedure was as follows. First, eight adhesive layer films (Films 1 to 7) and fluororesin substrates (PTFE 1 to 5) were temporarily bonded by vacuum thermal lamination in the combinations shown in Table 1 to prepare temporary bonded objects for each substrate. The fluororesin substrates (PTFE 1 to 5) used to prepare the temporary bonded objects had copper foil for forming a conductor pattern attached to the side opposite to the side on which the adhesive layer films (Films 1 to 7) were laminated.

[0101] Next, the prepared temporary adhesive was placed on each of the upper and lower surfaces of a core substrate, with the film side of the temporary adhesive facing inward, and vacuum hot-pressed at 200°C for 60 minutes at 1 MPa to obtain a laminate. Next, both the upper and lower surfaces of the obtained laminate (i.e., the copper foil bonded to the fluororesin substrate) were etched to form a conductor pattern. Then, a temporary adhesive was placed on each of the upper and lower surfaces of the laminate on which the conductor pattern was formed, with the film side facing inward, and vacuum hot-pressed, thereby repeatedly laminating the temporary adhesives. In this example, a multilayer laminate was prepared by laminating four layers above and below the core substrate, which was the center of the lamination. Then, through-holes were drilled in the prepared multilayer laminate from the top layer to the bottom layer, and a plating process was performed to produce a multilayer wiring board. Table 1 shows the configurations of the adhesive layer films and fluororesin substrates used in Examples 1 to 15 and Comparative Examples 1 to 3, as well as the diameters (μm) of the through-holes and the thicknesses (μm) of the plating layers. The core substrate used was a Panasonic product with a thickness of 100 μm, trade name "R-5775." Conductive patterns were formed on both the top and bottom surfaces of the core substrate, and then a temporary adhesive was placed on the core substrate and vacuum pressed.

[0102] As shown in Table 1, the diameter of the through holes provided in the multilayer wiring board was 200 μm in Examples 1 to 9, 13 to 15 and Comparative Examples 1 to 3, and 500 μm in Examples 10 to 12. The thickness of the plating layer was 30 μm in Examples 1 to 8, 10 to 15 and Comparative Examples 1 to 3, and 20 μm in Example 9.

[0103] For the multilayer wiring boards produced in Examples 1 to 15 and Comparative Examples 1 to 3, the values ​​of X and Y in the relational expressions (1) to (3) described above, and the value of Z in relational expression (3) were determined. X is the value obtained by multiplying the thickness (μm) of the adhesive layer film by the thermal expansion coefficient (ppm / °C) in the thickness direction after curing. Y is the value obtained by multiplying the thickness (μm) of the fluororesin substrate by the thermal expansion coefficient (ppm / °C) in the thickness direction. Z is the value obtained by multiplying the diameter (μm) of the through-hole by the thickness (μm) of the plating layer. The results are shown in Table 2. The sum of X and Y is shown in the column "Value of Formula (1): X + Y" in Table 2. The quotient obtained by dividing the sum of X and Y by Z is shown in the column "Value of Formula (3): (X + Y) / Z" in Table 2.

[0104]

[0105]

[0106] The connection reliability was evaluated (thermal cycle test) by the following method for the multilayer wiring boards produced in Examples 1 to 15 and Comparative Examples 1 to 3. The results are shown in Table 2.

[0107] [Connection Reliability Evaluation (Thermal Cycle Test)] First, the initial resistance value of the multilayer wiring board was measured. Then, the multilayer wiring board was subjected to a thermal cycle test. The conditions for the thermal cycle test were to maintain −55°C for 30 minutes, followed by maintaining 125°C for 30 minutes (or maintaining 125°C for 30 minutes, followed by maintaining −55°C for 30 minutes), with one cycle consisting of these. Then, every 250 cycles, the multilayer wiring board was removed from the thermal cycle test, and the resistance value was measured. If the rate of change in resistance value was within ±10%, the board was judged as passing (OK), and the board was subjected to the thermal cycle test again. If the rate of change in resistance value exceeded ±10% or was unmeasurable, the board was judged as failing (NG).

[0108] The connection reliability was evaluated based on the number of cycles until the result determined from the resistance measurement in the above-mentioned thermal cycle test became "fail" (NG), according to the following criteria. Note that, from the perspective of practically required connection reliability, a rating of A or B is particularly suitable, a rating of C or D is suitable, and those rated E are not suitable for practical use. A: 1001 cycles or more. B: 751 to 1000 cycles. C: 501 to 750 cycles. D: 251 to 500 cycles. E: 250 cycles or less.

[0109] [Results] As shown in Table 2, the adhesive layer films of Examples 1 to 15 satisfied the relational expression (1) described above, and all of them were evaluated as having good connection reliability. Furthermore, when Example 1 and Example 10 were compared, even if the value of "X + Y" in relational expression (1) was the same, those that satisfied relational expression (3) were evaluated as having better connection reliability.

[0110] On the other hand, the adhesive layer film of Comparative Example 1 had a large thermal expansion coefficient in the thickness direction after curing of 166 ppm / °C, and did not satisfy the relational expression (1), so the connection reliability was not suitable for practical use. The adhesive layer film of Comparative Example 2 had a thermal expansion coefficient in the thickness direction after curing of 110 ppm / °C or less, but did not satisfy the relational expression (1), so it was not suitable for practical use like Comparative Example 1. On the other hand, the adhesive layer film of Comparative Example 3 satisfied the relational expression (1), but had a large thermal expansion coefficient in the thickness direction after curing of 166 ppm / °C, so it was not suitable for practical use like Comparative Examples 1 and 2.

[0111] The adhesive film of the present invention can be used to produce a multilayer wiring board. The wiring board, multilayer wiring board, and semiconductor device of the present invention can also be used in, for example, various electronic devices.

[0112] 10: Adhesive layer, 10A: Adhesive layer film, 20: Fluororesin substrate, 21: Conductive pattern, 30: Wiring board, 40: Through hole, 41: Plating layer, 50: Core substrate, 100: Multilayer wiring board, D3: Diameter (diameter of through hole), T3: Thickness (thickness of plating layer).

Claims

1. An adhesive layer film used in the production of a multilayer wiring board, the multilayer wiring board comprising at least a fluororesin substrate and the adhesive layer film, the thickness of the adhesive layer film being 10 to 35 μm, the thermal expansion coefficient of the adhesive layer film in the thickness direction after curing being 110 ppm / °C or less, and satisfying the following relational expression (1): X+Y≦14000 (1) (wherein, in the relational expression (1), X is the value obtained by multiplying the thickness (μm) of the adhesive layer film by the thermal expansion coefficient (ppm / °C) in the thickness direction after curing, Y is the value obtained by multiplying the thickness (μm) of the fluororesin substrate by the thermal expansion coefficient (ppm / °C) in the thickness direction, and the thickness of the fluororesin substrate is 50 μm or more.) 2. The adhesive layer film according to claim 1, which is used for lamination with a fluororesin substrate having a thickness of 50 to 135 μm, and the thermal expansion coefficient in the thickness direction of the fluororesin substrate is 110 ppm / °C or less.

3. A film for adhesive layers according to claim 1 or 2, wherein the dielectric loss tangent of the cured product measured at 25°C and 10 GHz is 0.0021 or less.

4. A film for adhesive layers according to any one of claims 1 to 3, wherein the dielectric loss tangent of the cured product measured at 25°C and 80 GHz is 0.0027 or less.

5. A film for adhesive layers according to any one of claims 1 to 4, which is made of a resin composition containing at least (A) a thermosetting resin, (B) a thermoplastic elastomer, and (C) an inorganic filler.

6. The adhesive layer film according to claim 5, which contains a modified polyphenylene ether resin as component (A).

7. A wiring board comprising a fluororesin substrate and the film for adhesive layers according to any one of claims 1 to 6.

8. A wiring board comprising a fluororesin substrate and an adhesive layer film disposed on the fluororesin substrate, wherein the adhesive layer film has a thickness of 10 to 35 μm, the adhesive layer film has a thermal expansion coefficient in the thickness direction after curing of 110 ppm / °C or less, the fluororesin substrate has a thickness of 50 μm or more, and satisfies the following relational formula (2): X + Y ≦ 14000 (2) (where, in the relational formula (2), X is the value obtained by multiplying the thickness (μm) of the adhesive layer film by the thermal expansion coefficient in the thickness direction after curing (ppm / °C), and Y is the value obtained by multiplying the thickness (μm) of the fluororesin substrate by the thermal expansion coefficient in the thickness direction (ppm / °C).) 9. The wiring board according to claim 8, wherein the thickness of said fluororesin substrate is 50 to 135 μm, and the thermal expansion coefficient of said fluororesin substrate in the thickness direction is 110 ppm / ° C. or less.

10. The wiring board according to any one of claims 7 to 9, wherein the sum of the thickness (µm) of the fluororesin substrate and the thickness (µm) of the adhesive layer film is 60 to 160 µm.

11. A multilayer wiring board comprising two or more wiring boards according to any one of claims 7 to 10 stacked together.

12. The multilayer wiring board according to claim 11, wherein the total number of laminated layers is eight or more when the wiring board is one layer.

13. The multilayer wiring board according to claim 11 or 12, wherein the wiring board is provided with at least one through-hole penetrating the wiring board, and a plating layer is disposed on the inner surface of the through-hole, and the following relational expression (3) is satisfied: 0.1≦(X+Y) / Z≦2.0 (3) (where, in relational expression (3), X is the value obtained by multiplying the thickness (μm) of the adhesive layer film by the thermal expansion coefficient (ppm / °C) in the thickness direction after curing, Y is the value obtained by multiplying the thickness (μm) of the fluororesin substrate by the thermal expansion coefficient (ppm / °C) in the thickness direction, and Z is the value obtained by multiplying the diameter (μm) of the through-hole by the thickness (μm) of the plating layer disposed on the inner surface of the through-hole.) 14. The multilayer wiring board according to claim 13, wherein the through-hole has a diameter of 100 to 600 μm, and the plating layer has a thickness of 15 to 35 μm.

15. A semiconductor device comprising the multilayer wiring board according to any one of claims 11 to 14.

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