Wiring boards and semiconductor devices

Abstract

The present invention provides a wiring board that can suppress warping and crack formation in the solder resist layer, even when reflow processing is performed. [Solution] A wiring substrate comprising a substrate, a wiring layer provided on at least one main surface of the substrate, a solder resist layer provided so as to cover a part of the wiring layer, and a reinforcing member provided on the solder resist layer via an adhesive layer, wherein the reinforcing member has a rectangular shape with an opening that exposes the semiconductor element mounting area, and the coating area of ​​the adhesive layer is S ad The area of ​​the main surface of the substrate is S sb If so, then the following formula: 0.1≦S ad / S sb ≤0.75 A feature is that an adhesive layer is provided to satisfy the following conditions.

Description

[Technical Field]

[0001] The present invention relates to a wiring board, and more particularly to a wiring board in which reinforcing members are provided around a semiconductor element mounting area, and to a semiconductor device in which semiconductor elements are mounted on the wiring board. [Background technology]

[0002] In recent years, electronic devices have become increasingly smaller and more sophisticated, and semiconductor devices are required to be highly integrated and densely mounted. For example, to improve the mounting density of semiconductor packages, ball grid array (BGA) and pin grid array (PGA) semiconductor devices have been put into practical use as technologies that can accommodate multiple pins while maintaining a wide terminal pitch. Recently, the performance of semiconductor chips such as CPUs that are mounted has also improved, and they have become larger, and consequently, wiring boards such as BGA substrates tend to become larger as well.

[0003] However, as wiring boards become larger, they are prone to warping, and this warping can cause problems when mounting semiconductor chips. For this reason, it is known to reinforce wiring boards by providing a frame-like reinforcing member (also called a stiffener) around the semiconductor chip to be mounted (for example, Patent Document 1). The reinforcing member is usually made of a highly rigid material such as copper or stainless steel and is provided on the wiring layer or solder resist layer of the wiring board via an adhesive (for example, Patent Document 2).

[0004] The mounting of semiconductor chips on a wiring board is performed by heating the board to a temperature above the melting point of solder (e.g., 230°C) using a reflow oven. As a result, warping sometimes occurred in the wiring board that had undergone the reflow process. To address such problems, for example, Patent Document 3 proposes that warping can be suppressed by using a reinforcing member (stiffener) with a difference in linear thermal expansion coefficient between the front and back sides such that the difference between the linear thermal expansion coefficient of the wiring board side of the reinforcing member and the linear thermal expansion coefficient of the wiring board is reduced. Also, Patent Document 4 proposes using a metal plate provided on the wiring board having an average thermal expansion rate of 3 to 15 ppm / °C from 30 to 260°C in order to suppress the amount of change in warping due to temperature.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0006] When using the reinforcing members proposed in Patent Document 3 and Patent Document 4, although it is possible to suppress the warping of the wiring board that has undergone the above-described reflow process, there is a problem in some cases that cracks occur in the solder resist layer.

[0007] Therefore, an object of the present invention is to provide a wiring board that can suppress warping and also suppress the occurrence of cracks in the solder resist layer even when a reflow process is performed.

Means for Solving the Problems

[0008] The inventors have found that, without using a reinforcing member having a special structure as proposed in Patent Document 3 or Patent Document 4, by adjusting the coating area of an adhesive for fixing the reinforcing member on the substrate, it is possible to suppress the warpage of the wiring board while suppressing cracks in the solder resist layer. The present invention is based on such findings. That is, the gist of the present invention is as follows.

[0009] [1] A substrate, A wiring layer provided on at least one main surface of the substrate, A solder resist layer provided so as to cover a part of the wiring layer, A reinforcing member provided on the solder resist layer via an adhesive layer, A wiring board comprising: The reinforcing member has a rectangular shape with an opening exposing a semiconductor element mounting region, When the coating area of the adhesive layer is S , and the area of the substrate main surface is S sb , the following formula: 0.1 ≦ S ad / S sb ≦ 0.75 is satisfied, and an adhesive layer is provided. A wiring board characterized by the above. [2] When the area of the side of the reinforcing member in contact with the adhesive layer is S st , the following formula: 0.5 ≦ S ad / S st ≦ 1.2 is satisfied, and the wiring board according to [1]. [3] The wiring board according to [1], wherein the thickness of the adhesive layer is 1 to 500 μm. ​​​ [6] The wiring board according to [1], wherein the reinforcing member is made of metal or ceramics. [7] A semiconductor device comprising a wiring board as described in any one of the items [1] to [6], A semiconductor device in which semiconductor elements are mounted in the aforementioned semiconductor element mounting region. [Effects of the Invention]

[0010] According to the present invention, by setting the application area of ​​the adhesive for fixing the reinforcing member to the substrate to a predetermined range, a wiring substrate can be made that suppresses warping and also suppresses crack formation in the solder resist layer, even when reflow processing is performed. [Brief explanation of the drawing]

[0011] [Figure 1] This is a plan view of a wiring board according to one embodiment of the present invention. [Figure 2] This is a cross-sectional view taken along the line X-X' in the plan view of Figure 1. [Figure 3] This is a cross-sectional view of a wiring board according to another embodiment of the present invention. [Figure 4] This is a cross-sectional view of a semiconductor device according to one embodiment of the present invention. [Figure 5] Figure 4 is a perspective view of the wiring board shown, viewed from the side on which semiconductor elements are mounted. [Modes for carrying out the invention]

[0012] Embodiments of the wiring board according to the present invention will be described with reference to the drawings. Figure 1 is a plan view of the wiring board according to one embodiment of the present invention, as seen from the side on which semiconductor elements are mounted, and Figure 2 is a cross-sectional view taken along the line X-X' of the plan view in Figure 1. Figure 3 is a cross-sectional view of the wiring board according to another embodiment of the invention. Figure 4 is a cross-sectional view of a semiconductor device in which semiconductor elements are mounted in the semiconductor element mounting area of ​​the wiring board according to one embodiment of the present invention, and Figure 5 is a perspective plan view of the wiring board according to one embodiment of the present invention, as seen from the side on which semiconductor elements are mounted.

[0013] As shown in Figures 1 and 2, the wiring substrate 1 according to one embodiment of the present invention has a wiring layer 20 provided on one side of the substrate 10, and a solder resist layer 30 is provided so as to cover a part of the wiring layer 20. The solder resist layer 30 is patterned in this way, and the patterning method will be described later. Although not shown, the wiring layer 20 may also be provided on the other side of the substrate 10, and if the substrate is multilayer, multiple wiring layers may be provided in the thickness direction of the substrate. Furthermore, as shown in Figure 3, the wiring substrate 1 according to the embodiment of the present invention has a solder resist layer 30A provided so as to cover a part of the wiring layer 20, and a solder resist layer 30B may also be provided on the ball grid array (not shown) side, which is the main surface of the substrate 10 opposite to the side on which the wiring layer 20 is provided.

[0014] A reinforcing member 40 is provided on the solder resist layer 30 via an adhesive layer 50. As shown in Figure 2, the reinforcing member 40 is provided in the patterned solder resist layer 30 where a wiring layer 20 is not provided in the lower layer. The reinforcing member 40 has a rectangular shape with an opening 402, which forms a semiconductor device mounting region 401 where the wiring layer 20 and solder resist layer 30 provided on the substrate 10 are exposed.

[0015] As shown in Figure 4, a wiring board 1 according to one embodiment of the present invention can be made into a semiconductor device 100 by mounting a semiconductor element 200 on the semiconductor element mounting area 401. The semiconductor element 200 is electrically connected to the wiring layer 20 of the wiring board 1 via solder 300. The mounting of the semiconductor element 200 is usually performed by reflow soldering. In the semiconductor device 100 shown in Figure 4, a solder resist layer 30B is also provided on the main surface side of the substrate 10 opposite to the side on which the wiring layer 20 is provided. However, the wiring board 1 may also be an embodiment in which the solder resist layer 30A is provided only on the side on which the wiring layer 20 of the substrate 10 is provided, as shown in Figure 2.

[0016] The substrate may be a single layer made of an insulating layer, or may be a multilayer substrate in which an insulating layer and a conductor layer (conductor pattern) are alternately laminated. Although not shown, in the multilayer substrate, the wiring layer 20 is electrically connected to vias, the conductor layers of each layer, and a wiring layer (not shown) on the back side of the wiring substrate 1. The substrate 10 may be a coreless substrate.

[0017] The wiring layer is typically formed by patterning a copper foil, and a layer (not shown) made of a metal such as gold or nickel may be provided on the copper foil surface as a pad for mounting a semiconductor element.

[0018] The solder resist layer 30 provided to cover a part of the wiring layer 20 is formed by exposing and developing a photosensitive resin composition to form a desired pattern and then curing it.

[0019] As shown in FIG. 5, the wiring substrate 1 according to an embodiment of the present invention has an application area S of an adhesive layer 50 formed by applying an adhesive ad (the area surrounded by the outer broken line and the inner broken line in FIG. 5) and the area S of the main surface of the substrate 10 sb such that <s 0.1 ≦ S ad / S sb ≦ 0.75 The adhesive layer is provided so as to satisfy the above condition. The application area of the adhesive layer 50 corresponds to the area of the adhesion interface between the solder resist layer 30 and the reinforcing member 40. Thus, by providing the adhesive layer 50 so that the adhesion interface between the solder resist layer 30 and the reinforcing member 40 occupies a predetermined ratio with respect to the entire area of the substrate, warping of the wiring substrate can be suppressed, and generation of cracks in the solder resist layer can also be suppressed by the stress relaxation effect of the adhesive layer. When the area of the adhesion interface between the solder resist layer 30 and the reinforcing member 40 is larger than the above-described range with respect to the substrate area (S ad / S sb > 0.75), the reinforcing member 40 sufficiently corrects the deformation of the substrate 10 and the solder resist layer 30 due to temperature change, and warping of the wiring substrate can be suppressed. On the other hand, when S ad / S sbIf the ratio is >0.75, the stress generated due to the mismatch between the reinforcing member 40 and the solder resist layer 30 is large, and the adhesive layer cannot fully relieve the stress, which may prevent the occurrence of cracks in the solder resist layer. Also, if the area of ​​the adhesive interface between the solder resist layer 30 and the reinforcing member 40 is smaller than the range described above relative to the substrate area (0.1 > S), then the stress may be large. ad / S sb ), the stress relaxation effect of the adhesive layer becomes insufficient, the occurrence of cracks in the solder resist layer cannot be suppressed, and the reinforcing member cannot adequately correct the deformation caused by temperature changes, resulting in insufficient suppression of warping of the wiring board. ad / S sb A more preferable lower limit is 0.15, S ad / S sb A more preferable upper limit is 0.45.

[0020] The reinforcing member 40 may be made of a plate made of metal such as copper, aluminum, or stainless steel, or of ceramics, or of resin such as a glass epoxy substrate. However, from the viewpoint of suppressing warping of the wiring board, it is preferable that the reinforcing member be made of a material with a high elastic modulus, and it is preferable that it be a plate made of metal or ceramics.

[0021] The reinforcing member 40 has a rectangular shape with an opening 402 that exposes the semiconductor element mounting area, and the size of the opening 402 is adjusted according to the size of the semiconductor element to be mounted, but the area S of the main surface of the reinforcing member 40 excluding the opening 402 st This is the area S of the main surface of the substrate 10. sb The ratio is preferably 0.1 to 0.6 times, and more preferably 0.25 to 0.45 times. Note that the area S of the main surface of the substrate 10. sb Area S of the main surface of the reinforcing member 40 relative to the area S st It goes without saying that the smaller the size, the more the function of the reinforcing member is impaired.

[0022] The thickness of the reinforcing member 40 can be adjusted as appropriate depending on the size and thickness of the wiring board or semiconductor element, but for example, the thickness of the reinforcing member 40 is about 0.5 mm to 5 mm.

[0023] The adhesive layer 50 is formed by applying the adhesive to the main surface of the solder resist layer 30 or the reinforcing member 40. The application area S of the adhesive layer 50 ad The coating is applied in such a way that it satisfies the above-mentioned relation. Furthermore, from the viewpoint of suppressing warping of the wiring board and suppressing cracks in the solder resist layer, the area S of the main surface of the reinforcing member 40 is st Application area S of the adhesive layer 50 ad (S ad / S st ) but 0.5≦S ad / S st It is preferable that the adhesive be applied such that ≤ 1.2, and more preferably ≤ 0.65. ad / S st The value is ≤ 1.0.

[0024] The thickness of the adhesive layer 50 is not particularly limited, but from the viewpoint of suppressing crack formation, it is preferably 1 to 500 μm, and more preferably 10 to 300 μm. If the thickness of the adhesive layer 50 is too small, it may not be possible to maintain adhesion between the solder resist layer 30 and the reinforcing member 40. On the other hand, if the thickness of the adhesive layer 50 is too large, although it is good from the viewpoint of suppressing crack formation, it may not adequately suppress warping of the wiring board.

[0025] While there are no particular restrictions on the adhesive used in the adhesive layer 50, epoxy adhesives, silicone adhesives, and urethane adhesives are preferred from the viewpoint of adhesion and heat resistance.

[0026] The solder resist layer 30 is formed by exposing and developing a photosensitive resin composition to form a desired pattern, and then curing it. The photosensitive resin composition for forming the solder resist layer 30 includes a curable resin. As the curable resin, it is preferable that a carboxyl group-containing resin is included, considering patterning by exposure and development. The inclusion of a carboxyl group-containing resin makes it alkali developable. Furthermore, from the viewpoint of photosensitivity, it is preferable that the molecule has an ethylenically unsaturated double bond in addition to the carboxyl group, but only a carboxyl group-containing resin without an ethylenically unsaturated double bond may be used. The ethylenically unsaturated double bond is preferably derived from acrylic acid or methacrylic acid or derivatives thereof. When only a carboxyl group-containing resin without an ethylenically unsaturated double bond is used, it is necessary to use a compound having multiple ethylenically unsaturated groups in the molecule, i.e., a photopolymerizable monomer, as described later, in order to make the composition photocurable. Specific examples of carboxyl group-containing resins include the following compounds (either oligomers or polymers). In this specification, (meth)acrylate is a general term referring to acrylates, methacrylates, and mixtures thereof, and the same applies to other similar expressions.

[0027] (1) A carboxyl group-containing resin obtained by copolymerization of an unsaturated carboxylic acid such as (meth)acrylic acid with an unsaturated group-containing compound such as styrene, α-methylstyrene, lower alkyl (meth)acrylate, or isobutylene.

[0028] (2) A carboxyl group-containing urethane resin obtained by polyaddition reaction of diisocyanates such as aliphatic diisocyanates, branched aliphatic diisocyanates, alicyclic diisocyanates, and aromatic diisocyanates with carboxyl group-containing dialcohol compounds such as dimethylolpropionic acid and dimethylolbutanoic acid, and diol compounds such as polycarbonate polyols, polyether polyols, polyester polyols, polyolefin polyols, acrylic polyols, bisphenol A alkylene oxide adduct diols, and compounds having phenolic hydroxyl groups and alcoholic hydroxyl groups.

[0029] (3) A partially acid anhydride modified product of a reaction between diisocyanate and a bifunctional epoxy resin such as bisphenol A type epoxy resin, hydrogenated bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bixylenol type epoxy resin, or biphenol type epoxy resin, and a monocarboxylic acid compound having an ethylenically unsaturated double bond such as (meth)acrylic acid, as well as a carboxyl group-containing photosensitive urethane resin obtained by polyaddition reactions of carboxyl group-containing dialcohol compounds and diol compounds.

[0030] (4) A carboxyl group-containing photosensitive urethane resin obtained by adding a compound having one hydroxyl group and one or more (meth)acryloyl groups in the molecule, such as hydroxyalkyl (meth)acrylate, during the synthesis of the resin of (2) or (3) above, and then (meth)acrylicating the terminal (meth)acrylic.

[0031] (5) A carboxyl group-containing photosensitive urethane resin in which a compound having one isocyanate group and one or more (meth)acryloyl groups in the molecule is added to the resin of (2) or (3) above during synthesis and then (meth)acrylicated at the terminal.

[0032] (6) A carboxyl group-containing photosensitive resin obtained by reacting a bifunctional or polyfunctional (solid) epoxy resin with (meth)acrylic acid and adding a dibasic acid anhydride to the hydroxyl groups present in the side chain.

[0033] (7) A carboxyl group-containing photosensitive resin obtained by reacting a polyfunctional epoxy resin, in which the hydroxyl groups of a bifunctional (solid) epoxy resin are further epoxidized with epichlorohydrin, with (meth)acrylic acid, and then adding a dibasic acid anhydride to the resulting hydroxyl groups.

[0034] (8) A carboxyl group-containing polyester resin obtained by reacting a bifunctional oxetane resin with dicarboxylic acids such as adipic acid, phthalic acid, and hexahydrophthalic acid, and adding dibasic acid anhydrides such as phthalic anhydride, tetrahydrophthalic anhydride, and hexahydrophthalic anhydride to the resulting primary hydroxyl groups.

[0035] (9) A carboxyl group-containing photosensitive resin obtained by reacting an epoxy compound having multiple epoxy groups in one molecule with a compound having at least one alcoholic hydroxyl group and one phenolic hydroxyl group in one molecule, such as p-hydroxyphenethyl alcohol, and an unsaturated group-containing monocarboxylic acid such as (meth)acrylic acid, and then reacting the alcoholic hydroxyl group of the resulting reaction product with a polybasic acid anhydride such as maleic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, or adipic acid.

[0036] (10) A carboxyl group-containing photosensitive resin obtained by reacting a reaction product obtained by reacting a compound having multiple phenolic hydroxyl groups in one molecule with an alkylene oxide such as ethylene oxide or propylene oxide with an unsaturated group-containing monocarboxylic acid, and then reacting the resulting reaction product with a polybasic acid anhydride.

[0037] (11) A carboxyl group-containing photosensitive resin obtained by reacting a reaction product obtained by reacting a compound having multiple phenolic hydroxyl groups in one molecule with a cyclic carbonate compound such as ethylene carbonate or propylene carbonate with an unsaturated group-containing monocarboxylic acid, and then reacting the resulting reaction product with a polybasic acid anhydride.

[0038] (12) A carboxyl group-containing photosensitive resin obtained by adding a compound having one epoxy group and one or more (meth)acryloyl groups in one molecule to the resins of (1) to (11) above.

[0039] The carboxyl group-containing resins that can be used in the present invention are not limited to those listed above. Furthermore, the carboxyl group-containing resins listed above may be used individually or in combination of multiple types.

[0040] The amount of carboxyl group-containing resin in the photosensitive resin composition is preferably 20 to 60% by mass, and more preferably 25 to 60% by mass, based on solid content relative to the entire photosensitive resin composition. A concentration of 20% by mass or more improves the strength of the coating film. A concentration of 60% by mass or less results in appropriate viscosity and improved processability.

[0041] The photosensitive resin composition may contain a filler. Known inorganic or organic fillers can be used, but barium sulfate, spherical silica, hydrotalcite, and talc are particularly preferred. Furthermore, metal oxides such as metal oxides or aluminum hydroxide can be used as extender pigment fillers to obtain flame retardancy.

[0042] The amount of filler is not particularly limited, but it is preferably 10 to 70% by mass relative to the curable resin, and more preferably 30 to 60% by mass.

[0043] The filler may be surface-treated to improve its dispersibility in the photosensitive resin composition. Using a surface-treated filler can suppress aggregation. The surface treatment method is not particularly limited, and any known and conventional method may be used, but it is preferable to treat the surface of the inorganic filler with a surface treatment agent having a curable reactive group, for example, a coupling agent having a curable reactive group as an organic group.

[0044] As coupling agents, silane-based, titanate-based, aluminate-based, and zircoaluminate-based coupling agents can be used. Among these, silane-based coupling agents are preferred. Examples of such silane-based coupling agents include vinyltrimethoxysilane, vinyltriethoxysilane, N-(2-aminomethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-anilinopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, and 3-mercaptopropyltrimethoxysilane, which can be used alone or in combination. It is preferable that these silane-based coupling agents are pre-immobilized on the surface of the filler by adsorption or reaction. Here, the amount of coupling agent treated per 100 parts by mass of spherical silica is preferably 0.5 to 10 parts by mass.

[0045] The photosensitive resin composition may contain a photopolymerizable monomer. The photopolymerizable monomer is a monomer having an ethylenically unsaturated double bond. Examples of such photopolymerizable monomers include conventionally known polyester (meth)acrylates, polyether (meth)acrylates, urethane (meth)acrylates, carbonate (meth)acrylates, epoxy (meth)acrylates, and the like. Specifically, hydroxyalkyl acrylates such as 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate; diacrylates of glycols such as ethylene glycol, methoxytetraethylene glycol, polyethylene glycol, and propylene glycol; acrylamides such as N,N-dimethylacrylamide, N-methylolacrylamide, and N,N-dimethylaminopropylacrylamide; aminoalkyl acrylates such as N,N-dimethylaminoethyl acrylate and N,N-dimethylaminopropyl acrylate; polyhydric alcohols such as hexanediol, trimethylolpropane, pentaerythritol, dipentaerythritol, and tris-hydroxyethyl isocyanurate, or their ethylene oxide adducts, propylene oxide adducts, or ε-caprolactone adducts. Polyvalent acrylates derived from such sources; polyvalent acrylates such as phenoxyacrylate, bisphenol A diacrylate, and ethylene oxide adducts or propylene oxide adducts of these phenols; polyvalent acrylates derived from glycidyl ethers such as glycerin diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, and triglycidyl isocyanurate; and, not limited to the above, acrylates obtained by directly acrylateting polyols such as polyether polyols, polycarbonate diols, hydroxyl-terminated polybutadienes, and polyester polyols, or by urethane acrylates via diisocyanates, as well as melamine acrylate and at least one of the methacrylates corresponding to the acrylates can be appropriately selected and used. Such photopolymerizable monomers can also be used as reactive diluents.

[0046] Polyfunctional epoxy resins such as cresol novolac type epoxy resins may be reacted with acrylic acid to produce epoxy acrylate resins, or epoxy urethane acrylate compounds may be used as photopolymerizable monomers, obtained by reacting the hydroxyl groups of the epoxy acrylate resin with a half-urethane compound of a hydroxyacrylate such as pentaerythritol triacrylate and a diisocyanate such as isophorone diisocyanate. Such epoxy acrylate resins can improve photocurability without reducing touch-drying properties.

[0047] The amount of photopolymerizable monomer blended is preferably 0.2 to 60 parts by mass, more preferably 0.5 to 50 parts by mass, per 100 parts by mass of carboxyl group-containing resin, based on solid content. By blending 0.2 parts by mass or more of photopolymerizable monomer, the photocurability of the photosensitive resin composition is improved. Furthermore, by blending 60 parts by mass or less, the surface hardness of the solder resist layer can be improved.

[0048] Furthermore, the photosensitive resin composition may contain a photopolymerization initiator. The photopolymerization initiator is used to react the carboxyl group-containing resin or photopolymerizable monomer described above by exposure. Any known photopolymerization initiator can be used. One type of photopolymerization initiator may be used alone, or two or more types may be used in combination.

[0049] Examples of photopolymerization initiators include bis-(2,6-dichlorobenzoyl)phenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-2,5-dimethylphenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-4-propylphenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-1-naphthylphosphine oxide, bis-(2,6-dimethoxybenzoyl)phenylphosphine oxide, and bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentyl phenylphosphine oxide. Sphin oxides, bisacylphosphine oxides such as bis-(2,6-dimethoxybenzoyl)-2,5-dimethylphenylphosphine oxide and bis-(2,4,6-trimethylbenzoyl)-phenylphosphine oxide; 2,6-dimethoxybenzoyldiphenylphosphine oxide, 2,6-dichlorobenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylphosphinate methyl ester, 2-methylbenzoyldiphenylphosphine oxide, pivaloylphenylphosphinate Monoacylphosphine oxides such as isopropyl esters and 2,4,6-trimethylbenzoyldiphenylphosphine oxide; ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate, 1-hydroxycyclohexylphenyl ketone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)-benzyl]phenyl}-2-methyl-propan-1-one, 2-hydro Hydroxyacetophenones such as xy-2-methyl-1-phenylpropan-1-one; benzoins such as benzoin, benzyl, benzoin methyl ether, benzoin ethyl ether, benzoin n-propyl ether, benzoin isopropyl ether, and benzoin n-butyl ether; benzoin alkyl ethers; benzophenones such as benzophenone, p-methylbenzophenone, Michlar's ketone, methylbenzophenone, 4,4'-dichlorobenzophenone, and 4,4'-bisdiethylaminobenzophenone;Acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone-1, 2-(dimethylamino)-2-[(4-methylphenyl)methyl)-1-[4-(4-morpholinyl)phenyl]-1-butanone-1 Acetophenones such as thioxanthone, N,N-dimethylaminoacetophenone; thioxanthones such as thioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2,4-diisopropylthioxanthone; anthraquinone, chloroanthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, 2-amylanthraquinone, Anthraquinones such as 2-aminoanthraquinone; ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal; benzoic acid esters such as ethyl-4-dimethylaminobenzoate, 2-(dimethylamino)ethyl benzoate, and p-dimethylbenzoate ethyl ester; 1,2-octanedione, 1-[4-(phenylthio)phenyl]-,2-(O-benzoyloxime)], ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-,1-(O-acetyl Examples include oxime esters such as bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrole-1-yl)phenyl)titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-(2-(1-pyr-1-yl)ethyl)phenyl]titanium, phenyl disulfide 2-nitrofluorene, butyroin, anisoin ethyl ether, azobisisobutyronitrile, tetramethylthiuram disulfide, etc.

[0050] The amount of photopolymerization initiator added is preferably 0.1 to 20 parts by mass, more preferably 0.5 to 18 parts by mass, and even more preferably 1 to 15 parts by mass, based on solid content, per 100 parts by mass of carboxyl group-containing resin. When the amount is 0.01 parts by mass or more, the photocurability of the photosensitive resin composition is good, and the film properties such as chemical resistance are also good. When the amount is 20 parts by mass or less, light absorption on the surface of the solder resist layer is good, and the deep curing properties are less likely to decrease.

[0051] In combination with the above-mentioned photopolymerization initiator, a photoinitiator or sensitizer may be used. Examples of photoinitiators or sensitizers include benzoin compounds, anthraquinone compounds, thioxanthone compounds, ketal compounds, benzophenone compounds, tertiary amine compounds, and xanthone compounds. In particular, it is preferable to use thioxanthone compounds such as 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2-isopropylthioxanthone, and 4-isopropylthioxanthone. The inclusion of a thioxanthone compound can improve deep curing properties. These compounds can sometimes be used as photopolymerization initiators, but it is preferable to use them in combination with a photopolymerization initiator. Furthermore, one type of photoinitiator or sensitizer may be used alone, or two or more types may be used in combination.

[0052] These photopolymerization initiators, photoinitiators, and sensitizers absorb specific wavelengths, which can sometimes lead to reduced sensitivity and cause them to function as UV absorbers. However, they are not used solely for the purpose of improving the sensitivity of photosensitive resin compositions. By absorbing light of specific wavelengths as needed, the photoreactivity of the surface can be increased, changing the line shape and apertures of the solder resist layer pattern to vertical, tapered, or reverse tapered shapes, while also improving the accuracy of line width and aperture diameter.

[0053] The photosensitive resin composition may contain a thermosetting resin in addition to a carboxyl group-containing resin as the curable resin. The inclusion of a thermosetting resin in the photosensitive resin composition improves the heat resistance of the solder resist layer and also improves adhesion to the adhesive layer in high-temperature environments. As the thermosetting resin, known thermosetting resins such as melamine resin, benzoguanamine resin, melamine derivatives, benzoguanamine derivatives, and other amino resins, isocyanate compounds, blocked isocyanate compounds, cyclocarbonate compounds, epoxy compounds, oxetane compounds, episulfide resins, bismaleimide, and carbodiimide resins can be used. Particularly preferred are thermosetting resins having multiple cyclic ether groups or cyclic thioether groups (hereinafter abbreviated as cyclic (thio) ether groups) in the molecule. The thermosetting resin can be used alone or in combination of two or more types, but among these, epoxy resins are preferably used.

[0054] Examples of epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, hydrogenated bisphenol A type epoxy resin, brominated bisphenol A type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A novolac type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, dicyclopentadiene type epoxy resin, and triphenylmethane type epoxy resin.

[0055] The amount of thermosetting resin blended is preferably 0.5 to 2.5 mol, and more preferably 0.8 to 2.0 mol, of the number of functional groups of the thermosetting resin that react with the carboxyl group-containing resin, based on solid content.

[0056] Furthermore, in addition to the thermosetting resin described above, a thermosetting catalyst may be added to the photosensitive resin composition. Examples of thermosetting catalysts include imidazole derivatives such as imidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 4-phenylimidazole, 1-cyanoethyl-2-phenylimidazole, and 1-(2-cyanoethyl)-2-ethyl-4-methylimidazole; amine compounds such as dicyandiamide, benzyldimethylamine, 4-(dimethylamino)-N,N-dimethylbenzylamine, 4-methoxy-N,N-dimethylbenzylamine, and 4-methyl-N,N-dimethylbenzylamine; hydrazine compounds such as adipic acid dihydrazide and sebacate dihydrazide; and phosphorus compounds such as triphenylphosphine. In particular, it is not limited to these, and any substance that promotes the reaction between epoxy groups and carboxyl groups will suffice, and it may be used alone or in combination of two or more types.

[0057] Furthermore, S-triazine derivatives such as guanamine, acetoguanamine, benzoguanamine, 2,4-diamino-6-methacryloyloxyethyl-S-triazine, 2-vinyl-2,4-diamino-S-triazine, 2-vinyl-4,6-diamino-S-triazine isocyanuric acid adduct, and 2,4-diamino-6-methacryloyloxyethyl-S-triazine isocyanuric acid adduct can also be used, and preferably these compounds that also function as adhesion imparters are used in combination with the thermosetting catalyst. The thermosetting catalyst may be used alone or in combination of two or more types.

[0058] The thermosetting catalyst may further include materials other than those mentioned above, such as phenolic resins, polycarboxylic acids and their acid anhydrides, cyanate ester resins, and activated ester resins.

[0059] In addition to the components mentioned above, the photosensitive resin composition may optionally contain other components such as colorants, elastomers, mercapto compounds, urethane catalysts, thixotropizing agents, adhesion promoters, block copolymers, chain transfer agents, polymerization inhibitors, copper damage inhibitors, antioxidants, rust inhibitors, thickeners such as organic bentonite and montmorillonite, defoamers and leveling agents such as silicone-based, fluorine-based, and polymer-based defoamers, and flame retardants such as phosphinates, phosphate ester derivatives, and phosphorus compounds. These components may be those known in the field of electronic materials.

[0060] Organic solvents may be added to the photosensitive resin composition from the viewpoint of ease of preparation and applicability. As organic solvents, known and commonly used organic solvents can be used, such as ketones like methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons like toluene, xylene, and tetramethylbenzene; glycol ethers like cellosolve, methyl cellosolve, butyl cellosolve, carbitol, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol diethyl ether, diethylene glycol monomethyl ether acetate, and tripropylene glycol monomethyl ether; esters like ethyl acetate, butyl acetate, butyl lactate, cellosolve acetate, butyl cellosolve acetate, carbitol acetate, butyl carbitol acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, and propylene carbonate; aliphatic hydrocarbons like octane and decane; and petroleum-based solvents such as petroleum ether, petroleum naphtha, and solvent naphtha. These organic solvents can be used individually or in combination of two or more.

[0061] The amount of organic solvent blended in the photosensitive resin composition can be appropriately changed depending on the materials constituting the photosensitive resin composition. For example, it can be 30 to 300 parts by mass in terms of solid content per 100 parts by mass of curable resin.

[0062] The photosensitive resin composition may be used as a dry film or as a liquid. When used as a liquid, it may be a one-component or two-component or more-component system. The dry film will be described below.

[0063] The dry film comprises a first film and a resin layer formed on the first film, which is made of the photosensitive resin composition described above. The first film in the dry film refers to the film that is at least adhered to the resin layer when it is laminated onto a substrate such as a substrate by heating or the like, so that the side of the dry film made of the photosensitive resin composition is in contact with the substrate. The first film may be peeled off from the resin layer in a process after lamination. In particular, in the present invention, it is preferable to peel it off from the resin layer in a process after exposure.

[0064] To produce a dry film, the photosensitive resin composition of the present invention is diluted with an organic solvent to an appropriate viscosity, and then applied to a first film to a uniform thickness using a comma coater, blade coater, lip coater, rod coater, squeeze coater, reverse coater, transfer roll coater, gravure coater, spray coater, etc. The film is usually dried at a temperature of 50 to 130°C for 1 to 30 minutes to obtain the film. There are no particular restrictions on the coated film thickness, but generally, the film thickness after drying is appropriately selected within the range of 1 to 150 μm, preferably 10 to 60 μm.

[0065] The first film can be any known film without particular limitations, and for example, films made of thermoplastic resins such as polyester films (polyethylene terephthalate, polyethylene naphthalate, etc.), polyimide films, polyamide-imide films, polypropylene films, and polystyrene films can be suitably used. Among these, polyester films are preferred from the viewpoint of heat resistance, mechanical strength, and ease of handling. Laminates of these films can also be used as the first film.

[0066] Furthermore, from the viewpoint of improving mechanical strength, the thermoplastic resin film described above is preferably a film stretched in one or two axes.

[0067] The thickness of the first film is not particularly limited, but can be, for example, 10 μm to 150 μm.

[0068] After forming a resin layer of the photosensitive resin composition of the present invention on the first film, it is preferable to further laminate a peelable second film onto the surface of the resin layer for purposes such as preventing dust from adhering to the surface of the resin layer. In the dry film according to the present invention, the second film refers to a film that is peeled off from the resin layer before lamination when integrally forming a dry film by laminating it onto a substrate such as a substrate by heating or the like so that the resin layer side of the dry film is in contact with it.

[0069] As the second film that can be peeled off from the resin layer, for example, polyethylene film, polytetrafluoroethylene film, polypropylene film, surface-treated paper, etc., it is sufficient that the adhesive force between the resin layer and the second film is less than the adhesive force between the resin layer and the first film when the second film is peeled off.

[0070] The thickness of the second film is not particularly limited, but can be, for example, 10 μm to 150 μm.

[0071] When using the photosensitive resin composition in liquid form, the photosensitive resin composition is adjusted to a viscosity suitable for the coating method using an organic solvent. It is then applied to the main surface of the substrate 10 where the wiring layer 20 is located, and optionally to the main surface of the substrate 10 on the ball grid array (not shown) side, by methods such as dip coating, flow coating, roll coating, bar coating, screen printing, or curtain coating. After application, the organic solvent contained in the composition is evaporated and dried (pre-dried) at a temperature of 60 to 100°C to form a tack-free resin layer. In the case of a dry film, the resin layer is bonded to the substrate using a laminator or the like so that the resin layer is in contact with the substrate, thereby forming the resin layer.

[0072] After forming a resin layer on a substrate, it is selectively exposed with active energy rays through a photomask with a predetermined pattern, and the unexposed areas are developed with a dilute alkaline aqueous solution (e.g., 0.3-3% by mass sodium carbonate aqueous solution) to form a pattern on the cured material. In the case of a dry film, after exposure, the first film is peeled off from the dry film and developed to form a patterned cured material on the substrate. In the case of a dry film, if the properties are not impaired, the first film may be peeled off from the dry film before exposure, and the exposed resin layer may be exposed and developed. Furthermore, by irradiating the cured material with active energy rays and then heat curing (e.g., 100-220°C), or irradiating with active energy rays after heat curing, or performing final finishing curing (main curing) by heat curing alone, a solder resist layer with excellent properties such as adhesion and hardness can be formed. [Examples]

[0073] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples. In the following, "parts" and "%" all refer to mass unless otherwise specified.

[0074] [Preparation of photosensitive resin composition] (Examples of carboxyl group-containing resin synthesis) Prior to preparing the photosensitive resin composition, the carboxyl group-containing resin used in this example was prepared according to the procedure shown below. In an autoclave equipped with a thermometer, nitrogen introduction device, alkylene oxide introduction device, and stirring device, 119.4 parts by mass of novolac-type cresol resin (trade name "Shonol CRG951", manufactured by Aica Kogyo Co., Ltd., OH equivalent: 119.4), 1.19 parts by mass of potassium hydroxide, and 119.4 parts by mass of toluene were introduced. The system was then purged with nitrogen while stirring, and the temperature was increased. Next, 63.8 parts by mass of propylene oxide was gradually added dropwise, and the reaction was carried out at 125-132°C and 0-4.8 kg / cm2 for 16 hours. After cooling to room temperature, 1.56 parts by mass of 89% phosphoric acid was added to the reaction solution and mixed while neutralizing the potassium hydroxide to obtain a propylene oxide reaction solution of novolac-type cresol resin [solid content: 62.1%; hydroxyl value: 182.2 mg KOH / g (307.9 g / eq.)]. This propylene oxide reaction solution contained an average of 1.08 moles of propylene oxide added per equivalent of phenolic hydroxyl groups. 293.0 parts by mass of the propylene oxide reaction solution of the obtained novolac-type cresol resin, 43.2 parts by mass of acrylic acid, 11.53 parts by mass of methanesulfonic acid, 0.18 parts by mass of methylhydroquinone, and 252.9 parts by mass of toluene were introduced into a reactor equipped with a stirrer, thermometer, and air blowing tube. Air was blown in at a rate of 10 ml / min, and the mixture was reacted at 110°C for 12 hours while stirring. 12.6 parts by mass of water produced by the reaction was distilled off as an azeotropic mixture with toluene. The mixture was then cooled to room temperature, neutralized with 35.35 parts by mass of 15% aqueous sodium hydroxide solution, and then washed with water. Subsequently, toluene was removed by distillation with 118.1 parts by mass of diethylene glycol monoethyl ether acetate in an evaporator, while substituting for the toluene, to obtain a novolac-type acrylate resin solution. Next, 332.5 parts by mass of the obtained novolac-type acrylate resin solution and 1.22 parts by mass of triphenylphosphine were introduced into a reactor equipped with a stirrer, thermometer, and air blowing tube. Air was blown in at a rate of 10 ml / min, and while stirring, 60.8 parts by mass of tetrahydrophthalic anhydride were gradually added. The mixture was reacted at 95-101°C for 6 hours, and after cooling, it was removed. In this way, a carboxyl group-containing resin solution (solid content: 70.6%; acid value of solid content: 87.7 mg KOH / g) was obtained.

[0075] Next, the components were mixed according to Table 1 below, pre-mixed in a stirrer, and then kneaded using a three-roll mill to prepare a photosensitive resin composition. The amounts in Table 1 represent the solid content. Details of each component in Table 1 are as follows. Carboxyl group-containing resin: Carboxyl group-containing resin obtained by the synthesis example described above Photopolymerization initiator: Omnirad819 (manufactured by IGM Resins) Thermosetting resin: Phenolic novolac type epoxy resin (N-730A, manufactured by DIC Corporation) Thermosetting catalyst: melamine Photopolymerizable monomer: Dipentaerythritol hexaacrylate (DPHA) (manufactured by Nippon Kayaku Co., Ltd.)

[0076] [Table 1]

[0077] [Example 1] <Preparation of dry film> The photosensitive resin composition obtained as described above was diluted with 70 g of methyl ethyl ketone and stirred with a stirrer for 15 minutes to obtain a coating solution. The coating solution was applied to a polyethylene terephthalate film (Emblet PTH-25, manufactured by Unitika Ltd.) with a thickness of 38 μm and dried at 80°C for 15 minutes to form a resin layer with a thickness of 20 μm. Next, a polypropylene film (OPP-FOA, manufactured by Futamura Chemical Co., Ltd.) with a thickness of 18 μm was laminated onto the resin layer to produce a dry film.

[0078] <Fabrication of evaluation boards> An evaluation substrate for FC-BGA (FR-4 copper-clad laminate, 50mm x 50mm x 0.8mmt, copper foil on both sides, copper foil thickness 18μm on both sides) with a pad pitch of 200μm was subjected to CZ treatment on the copper foil surface using CZ8101B manufactured by MEC Corporation at an etching rate of 1μm. The polypropylene film was peeled off from the dry film obtained as described above and the exposed surface of the resin layer of the exposed dry film was bonded to the CZ-treated copper foil surface. Subsequently, it was laminated using a vacuum laminator (CVP-300: manufactured by Nikko Materials Co., Ltd.) in the first chamber at 90°C under conditions of vacuum pressure of 3hPa and vacuum time of 30 seconds, and then pressed under conditions of press pressure of 0.5MPa and press time of 30 seconds to firmly bond the copper-clad laminate and the resin layer. Next, from the polyethylene terephthalate film side, via a negative mask, a UV conveyor furnace equipped with a metal halide lamp (Toshiba Corporation KUV-28351-XK-DM) was used as the light source to apply an integrated exposure of 1000 mJ / cm² at a wavelength of 365 nm. 2 (38mW·cm 2 Exposure was performed under the condition of ×26s. After standing for 10 minutes, the polyethylene terephthalate film was peeled off to expose the resin layer, and development was performed using a 0.2 mass% Na2CO3 aqueous solution at a liquid temperature of 30°C, followed by washing with water to form a pattern. Next, the resin layer was cured by heating at a temperature of 150°C for 60 minutes to obtain a solder resist layer-forming substrate. An epoxy resin adhesive was applied to the edges of all four sides of one main surface of the solder resist layer-forming substrate using a dispenser. At that time, the area (S) of the main surface of the solder resist layer-forming substrate was applied. sb ) relative to the adhesive application area (S ad ) was set to 0.1. Subsequently, a frame-shaped stiffener (reinforcement member) made of 50mm x 50mm x 2mmt stainless steel plate (SUS304) with a 40mm x 40mm opening in the center was prepared and bonded to the resist on the resist pattern formation surface of the resist pattern formation substrate as shown in Figure 4. Next, the solder resist layer formation substrate with the stiffener attached was heated to cure the adhesive applied to the stiffener and produce an evaluation substrate.

[0079] [Example 2] The adhesive application area is S ad / S sb The evaluation substrate was prepared in the same manner as in Example 1, except that it was changed to =0.4.

[0080] [Example 3] The adhesive application area is S ad / S sb The evaluation substrate was prepared in the same manner as in Example 1, except that it was changed to =0.75.

[0081] [Example 1] The adhesive application area is S ad / S sb The evaluation substrate was prepared in the same manner as in Example 1, except that it was changed to =0.05.

[0082] [Comparative Example 2] The adhesive application area is S ad / S sb The evaluation substrate was prepared in the same manner as in Example 1, except that it was changed to =0.8.

[0083] <Reflow Test> Each evaluation substrate obtained as described above was passed through a reflow oven pre-set to a maximum temperature of 260°C to perform a reflow test, after which the following warpage evaluation was performed.

[0084] <Warping evaluation> After the reflow test, each evaluation board was placed on a horizontal wooden board, and the average amount of lift at the four corners of the board was measured. Warpage was then evaluated based on the following evaluation criteria. ○: Less than 1 mm ×: greater than 1mm The evaluation results are shown in Table 2.

[0085] <Crack Evaluation> The evaluation substrates obtained as described above were placed in a thermal cycling machine that performed temperature cycles between -65°C and 150°C, and a thermal cycle test (TCT) was conducted. The surface of the cured material was observed after 500 cycles and 1000 cycles, and evaluated according to the notation criteria below. The results are shown in Table 2. ◎: Fewer than 50 cracks appear in 1000 cycles. ○: Fewer than 50 cracks appear after 500 cycles, and 50 or more cracks appear after 1000 cycles. ×: More than 50 cracks occurred in 500 cycles. The evaluation results are shown in Table 2.

[0086] [Table 2]

[0087] As is clear from the evaluation results shown in Table 2, the coating area of ​​the adhesive layer relative to the area of ​​the main surface of the substrate (S ad / S sb It can be seen that the evaluation substrates (Examples 1-3) in which the coefficient of warping is in the range of 0.1 to 0.75 show suppressed warping and crack formation in the solder resist layer. On the other hand, S ad / S sb Evaluation substrates with a value of less than 0.1 show insufficient suppression of both warping and crack formation in the solder resist layer. ad / S sb It was found that evaluation substrates with a value exceeding 0.75 showed suppressed warping, but were unable to suppress crack formation in the solder resist layer.

Claims

1. circuit board and A wiring layer provided on at least one main surface of the substrate, A solder resist layer is provided so as to cover a portion of the wiring layer, A reinforcing member provided on the solder resist layer via an adhesive layer, A wiring board equipped with, The reinforcing member has a rectangular shape with an opening that exposes the semiconductor element mounting area. The coating area of ​​the adhesive layer is S ａｄ The area of ​​the main surface of the substrate is S ｓｂ If so, then the following formula: 0.1≦S ａｄ / S ｓｂ ≦0.75 An adhesive layer is provided to satisfy the following conditions: A wiring board characterized by the following features.

2. The area of ​​the side of the reinforcing member that is in contact with the adhesive layer is S ｓｔ In that case, the following formula: 0.5≦S ａｄ / S ｓｔ ≦1.2 A wiring board according to claim 1 that satisfies the following conditions.

3. The wiring board according to claim 1, wherein the thickness of the adhesive layer is 1 to 500 μm.

4. The wiring board according to claim 1, wherein the adhesive layer is at least one selected from epoxy adhesives, silicone adhesives, and urethane adhesives.

5. The wiring substrate according to claim 1, wherein the solder resist layer is made of a cured product of a photosensitive resin composition containing a curable resin and a photopolymerization initiator.

6. The wiring board according to claim 1, wherein the reinforcing member is made of metal or ceramics.

7. A semiconductor device comprising a wiring board according to any one of claims 1 to 6, A semiconductor device in which semiconductor elements are mounted in the aforementioned semiconductor element mounting region.

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