JP2008244189A - Circuit board and semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a favorable circuit board and a semiconductor device which are adapted to the reduction of a film by the use of a prepreg according to a circuit pattern. <P>SOLUTION: The circuit board is formed by laminating a core layer of a sheet-shaped substrate, the prepreg having a first resin layer formed on the one face side of the core layer and a second resin layer formed on the other face side thereof, and a board having circuit wiring. The first resin layer of the prepreg is jointed to a face where the circuit wiring of the board is formed, and a thickness of the first resin layer is thicker than that of the second resin layer. Furthermore, when the thickness of the first resin layer is B1 [μm], a thickness of the circuit board coming into contact with the first resin layer is t1 [μm], a copper remaining rate of the circuit wiring is S [%], and a thickness from the upper end of the circuit wiring to the core layer is t2 [μm], a relation of B1=t2+t1×(1-S/100) is satisfied. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a circuit board and a semiconductor device.

A circuit board is formed using a prepreg obtained by impregnating a thermosetting resin using a glass fiber substrate or the like as a core layer of a sheet-like substrate. This prepreg is obtained by a method of immersing a glass fiber substrate having a thickness of about 50 to 200 μm in a thermosetting resin varnish (see, for example, Patent Document 1).
However, along with recent downsizing and thinning of electronic parts and electronic devices, circuit boards and the like used therefor are required to be downsized and thinned. Accordingly, it has become necessary to form a higher-density circuit wiring pattern on the circuit board.

  In order to form such a high-density circuit pattern, a multilayer circuit board is used and each layer is thinned. However, the amount of resin required varies depending on the inner layer circuit pattern. When the prepreg is laminated, the resin protrudes or the resin that fills the circuit is insufficient, so that a good circuit board may not be obtained.

JP 2004-216784 A

  An object of the present invention is to provide a circuit board and a semiconductor device corresponding to thinning, and to provide a good circuit board and a semiconductor device using a prepreg corresponding to a circuit pattern.

Such an object is achieved by the present invention described in the following (1) to (6).
(1) A prepreg having a core layer of a sheet-like base material, a first resin layer formed on one side of the core layer and a second resin layer formed on the other side, and circuit wiring are formed. A first resin layer of the prepreg is bonded to a surface of the substrate on which circuit wiring is formed, and the thickness of the first resin layer is the first substrate. The thickness of the first resin layer is B1 [μm], the thickness of the circuit wiring in contact with the first resin layer is t1 [μm], and the remaining copper ratio of the circuit wiring is A circuit that satisfies the relationship of B1 = t2 + t1 × (1−S / 100), where S [%] and the thickness from the upper end surface of the circuit wiring portion to the core layer is t2 [μm]. substrate.
(2) The circuit board according to (1), wherein the thickness of the sheet-like base material is 5 to 25 μm.
(3) The circuit board according to (1) or (2), wherein a thermal expansion coefficient in a plane direction after the prepreg is cured is 20 ppm / ° C. or less.
(4) The ratio of the thickness of the first resin layer to the thickness of the second resin layer (second resin layer / first resin layer), (1) to (3) A circuit board according to any one of the above.
(5) The circuit board according to any one of (1) to (4), wherein the thickness of the second resin layer is 5 to 15 μm.
(6) The circuit board according to any one of (1) to (5), wherein the sheet-like base material has a dielectric constant of 7 or less and a thermal expansion coefficient of 6 ppm / ° C. or less.
(7) A semiconductor device, wherein a semiconductor element is mounted on the circuit board according to any one of (1) to (6).

ADVANTAGE OF THE INVENTION According to this invention, it can respond to thin film formation, and can provide a favorable circuit board using the optimal prepreg according to a circuit pattern. That is, the core layer of the sheet-like base material, for example, the fiber base material is unevenly distributed in the thickness direction of the prepreg according to the circuit pattern (for example, the remaining copper ratio, the thickness of the copper foil), and the necessity according to the circuit pattern By using a prepreg having only a small amount of resin, it is possible to obtain a good circuit board that is thin and has no problems due to insufficient or excessive resin.
In addition, according to the present invention, a semiconductor device having the circuit board can be provided, whereby a thin semiconductor device can be obtained.

The circuit board and semiconductor device of the present invention will be described below.
A circuit board of the present invention includes a prepreg having a core layer of a sheet-like base material, a first resin layer formed on one side of the core layer, and a second resin layer formed on the other side, and a circuit A circuit board formed by laminating a substrate on which wiring is formed, wherein the first resin layer of the prepreg is bonded to a surface of the substrate on which circuit wiring is formed, and the thickness of the first resin layer is Is thicker than the thickness of the second resin layer, the thickness of the first resin layer is B1 [μm], the thickness of the circuit wiring in contact with the first resin layer is t1 [μm], and the circuit wiring When the remaining copper ratio is S [%] and the thickness from the upper end surface of the circuit wiring portion to the core layer is t2 [μm], the relationship B1 = t2 + t1 × (1−S / 100) is satisfied. Features.
A semiconductor device of the present invention is characterized in that a semiconductor element is mounted on the circuit board described above.

First, the circuit board will be described.
The circuit board includes a prepreg 10 as shown in FIG. 1 and a board 30 as shown in FIG.
The prepreg 10 includes a core layer 11 of a sheet-like substrate, a first resin layer 1 formed on one side of the core layer 11 (upper side in FIG. 1), and the other side (lower side in FIG. 1). A second resin layer 2 formed on the side).
The circuit wiring portion 5 is formed on the substrate 30 so as to protrude from both surfaces of the core material 4. A space 51 is formed between the circuit wires 5. When the prepreg 10 and the substrate 30 are bonded, the second resin layer 2 is embedded in the space 51.

FIG. 3 schematically shows a state in which the prepreg 10 and the substrate 30 are laminated. As shown in FIG. 3, the first resin layer 1 is embedded in the space 51 between the circuit wires 5.
Then, the thickness of the first resin layer 1 is B1 [μm], the thickness of the circuit wiring part 5 is t1 [μm] and the remaining copper ratio is S [%], and the upper end surface of the circuit wiring part 5 (FIG. When the thickness from the upper side of 3 to the core layer 11 is t2 [μm], the relationship B1 = t2 + t1 × (1−S / 100) is satisfied. Thereby, the optimal resin layer thickness can be set for the circuit wiring pattern, and the thickness of the finally obtained circuit board can be reduced.

  Here, although the thickness of t2 is not specifically limited, 0-15 micrometers is preferable. Moreover, when there is a concern about a decrease in insulation in the circuit wiring part 5 due to contact between the circuit wiring part 5 and the core layer 11, it is preferable to set t2 to 3 to 15 μm. On the other hand, when the final thickness of the circuit board is reduced, t2 is preferably 0 to 5 μm, and in order to achieve both insulation and thinness, t2 is preferably 3 to 5 μm. preferable. Thereby, after optimizing the thickness of the prepreg 10, it is excellent in the embedding property to the circuit wiring part 5 on one surface side, and high insulation reliability can be provided to the other surface side.

  Further, when the thickness of the entire prepreg 10 is t0 [μm] and the thickness of the circuit wiring part 5 is t1 [μm], the difference (t3) between t0 and t1 is not particularly limited, but is 35 μm or less. It is preferable that it is 10-30 micrometers especially. Thereby, even if the thickness of the circuit board finally obtained is thin, insulation reliability can be maintained.

  Further, the thickness B2 [μm] of the second resin layer 2 is not particularly limited, but is preferably 5 to 15 μm, particularly preferably 8 to 10 μm, when only the surface plating property is mainly required. Thereby, it is excellent in the plating property of one surface side.

  Further, the ratio (B2 / B1) between the thickness B1 [μm] of the first resin layer 1 and the thickness B2 [μm] of the second resin layer 2 is not particularly limited, but is preferably 0.1 to 1, 0.2 to 0.4 is particularly preferable. When the thickness ratio is within the above range, the waviness of the core layer 11 can be particularly reduced, thereby improving the flatness of the prepreg 10 and improving the yield of the substrate.

  The total thickness of the prepreg 10 is not particularly limited, but is preferably 10 to 35 μm, and particularly preferably 10 to 25 μm. Thereby, the substrate can be kept thin even when the number of layers is increased to 6 or more, and a thin semiconductor device can be finally obtained.

The circuit board is obtained, for example, by laminating the above-described prepreg 10 on both sides of the substrate 30. Such a circuit board can be obtained, for example, by superposing the prepreg 10 on both surfaces of the substrate 30 having a circuit pattern on the surface, and further superposing a copper foil on the outermost layer, followed by heating and pressure molding.
The circuit board will be described in detail based on a circuit board having four layers of circuit wiring as shown in FIG.
In the circuit board 70, prepregs 10 a and 10 b are laminated on both surfaces of the board 30.
A through hole 41 is provided in the substrate 30 so as to penetrate the substrate 30. The inside of the through hole 41 is copper-plated and is electrically connected to the circuit wiring portion 5 formed on both surfaces of the substrate 30.

  Prepregs 10a and 10b are provided so as to cover the circuit wiring portions 5 on both surfaces of the substrate 30. The first resin layers 1 of the prepregs 10a and 10b are embedded in the space portions 51 between the circuit wiring portions 5 respectively.

  Circuit wiring portions 5a and 5b are formed on the surfaces of the prepregs 10a and 10b. The circuit wiring portions 5a and 5b can be formed by, for example, copper plating. The prepregs 10a and 10b are provided with through holes 101 so as to penetrate the prepregs 10a and 10b. The inside of the through hole 101 is copper-plated, and the circuit wiring part 5 formed on the surface of the substrate 30 is electrically connected to the circuit wiring parts 5a and 5b formed on the surface of the prepreg 10. ing.

  Thus, in order for the thickness of the 1st resin layer 1 of the prepreg 10 which comprises the circuit board 70 to satisfy the relationship as mentioned above with the thickness of the circuit wiring part 5, the thickness of the circuit board 70 is made thin. be able to.

Next, the prepreg 10 as described above will be described.
As shown in FIG. 1, the prepreg 10 includes a core layer 11 of a sheet-like base material, a first resin layer 1 formed on one surface side (upper side in FIG. 1) of the core layer 11, and the other surface side. And a second resin layer 2 formed on the lower side in FIG. Each will be described below.

(Core layer)
Examples of the sheet-like substrate constituting the core layer 11 include glass fiber substrates such as glass woven fabric and glass nonwoven fabric, polyamide resin fibers such as polyamide resin fibers, aromatic polyamide resin fibers and wholly aromatic polyamide resin fibers, Synthetic fiber substrate, craft made of woven or non-woven fabric mainly composed of polyester resin fiber such as polyester resin fiber, aromatic polyester resin fiber, wholly aromatic polyester resin fiber, polyimide resin fiber, fluororesin fiber, etc. Examples thereof include organic fiber base materials such as paper base materials such as paper, cotton linter paper, and mixed paper of linter and kraft pulp. Among these, a glass fiber base material is preferable. Thereby, the intensity | strength of the prepreg 10 can be improved.

  As glass which comprises such a glass fiber base material, E glass, C glass, A glass, S glass, D glass, NE glass, T glass etc. are mentioned, for example. Among these, N, NE, S, and T glass are preferable. Thereby, the thermal expansion coefficient of a glass fiber base material can be made small, and, thereby, the thermal expansion coefficient of a prepreg can be made small.

Although the thickness of a sheet-like base material is not specifically limited, It is preferable that it is 5-25 micrometers, and it is especially preferable that it is 10-15 micrometers. When the thickness is within the above range, the balance between the reduction in the thickness of the substrate and the strength of the substrate, and the processability and reliability of interlayer connection are particularly excellent.
The dielectric constant of the sheet-like substrate is not particularly limited, but is preferably 7 or less.
Moreover, the thermal expansion coefficient of the sheet-like substrate is not particularly limited, but is preferably 6 ppm / ° C. or less, more preferably 3 ppm / ° C. or less.

(First resin layer)
The 1st resin layer 1 is comprised by the resin composition containing curable resin, a hardening | curing agent, etc., for example.
Examples of the curable resin include novolac type phenol resins such as phenol novolak resin, cresol novolak resin, bisphenol A novolak resin, unmodified resole phenol resin, oil-modified resole phenol resin modified with paulownia oil, linseed oil, walnut oil, etc. Phenol resin such as resol type phenol resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol E type epoxy resin, bisphenol M type epoxy resin, bisphenol P type epoxy resin, bisphenol Z type epoxy Bisphenol type epoxy resin such as resin, phenol novolac type epoxy resin, novolak type epoxy resin such as cresol novolak type epoxy resin, biphenyl type epoxy resin, Phenylaralkyl epoxy resin, arylalkylene epoxy resin, naphthalene epoxy resin, anthracene epoxy resin, phenoxy epoxy resin, dicyclopentadiene epoxy resin, norbornene epoxy resin, adamantane epoxy resin, fluorene epoxy resin, etc. Resin having triazine ring such as epoxy resin, urea (urea) resin, melamine resin, unsaturated polyester resin, bismaleimide resin, polyurethane resin, diallyl phthalate resin, silicone resin, resin having benzoxazine ring, cyanate resin, polyimide resin , Polyamideimide resin, benzocyclobutene resin and the like. One of these may be used alone, two or more having different weight average molecular weights may be used in combination, and one or two or more thereof and a prepolymer thereof may be used in combination.
Among these, cyanate resins (including prepolymers of cyanate resins) are particularly preferable. Thereby, the thermal expansion coefficient of the prepreg 10 can be made small. Furthermore, the electrical characteristics (low dielectric constant, low dielectric loss tangent) of the prepreg 10 are also excellent.

The cyanate resin can be obtained by, for example, reacting a halogenated cyanide compound with a phenol and prepolymerizing it by a method such as heating as necessary. Specific examples include bisphenol type cyanate resins such as novolac type cyanate resin, bisphenol A type cyanate resin, bisphenol E type cyanate resin, and tetramethylbisphenol F type cyanate resin. Among these, novolac type cyanate resin is preferable. Thereby, the heat resistance improvement by a crosslinking density increase and flame retardance, such as a resin composition, can be improved. This is because the novolac-type cyanate resin forms a triazine ring after the curing reaction. Furthermore, it is considered that novolak-type cyanate resin has a high benzene ring ratio due to its structure and is easily carbonized. Furthermore, even when the prepreg 10 is thinned (thickness of 35 μm or less), excellent rigidity can be imparted to the prepreg 10. In particular, since the rigidity during heating is excellent, the reliability when mounting a semiconductor element is also particularly excellent.

  As said novolak-type cyanate resin, what is shown, for example by Formula (I) can be used.

  The average repeating unit n of the novolak cyanate resin represented by the formula (I) is not particularly limited, but is preferably 1 to 10, and particularly preferably 2 to 7. When the average repeating unit n is less than the lower limit, the novolak cyanate resin has low heat resistance, and the low-mer may be desorbed and volatilized during heating. Moreover, when average repeating unit n exceeds the said upper limit, melt viscosity will become high too much and the moldability of the prepreg 10 may fall.

Although the weight average molecular weight of the cyanate resin is not particularly limited, a weight average molecular weight of 500 to 4,500 is preferable, and 600 to 3,000 is particularly preferable. When the prepreg 10 is produced when the weight average molecular weight is less than the lower limit, tackiness may occur, and when the prepregs 10 come into contact with each other, they may adhere to each other or transfer of the resin may occur. In addition, when the weight average molecular weight exceeds the above actual value, the reaction becomes too fast, and when it is used as a substrate (particularly a circuit substrate), molding defects may occur or the interlayer peel strength may be lowered.
The weight average molecular weight of the cyanate resin or the like can be measured by, for example, GPC (gel permeation chromatography, standard substance: converted to polystyrene).

  In addition, although not particularly limited, the cyanate resin can be used alone or in combination of two or more having different weight average molecular weights, or one or two or more of these prepolymers. It can also be used together.

  Although content of the said thermosetting resin is not specifically limited, 5 to 50 weight% of the whole said resin composition is preferable, and 20 to 40 weight% is especially preferable. When the content is less than the lower limit, it may be difficult to form the prepreg 10, and when the content exceeds the upper limit, the strength of the prepreg 10 may be reduced.

Moreover, it is preferable that the said resin composition contains an inorganic filler. Thereby, even if the circuit board finally obtained is thinned (thickness 0.5 mm or less), it can be excellent in strength. Furthermore, the low thermal expansion of the circuit board can be improved.
Examples of the inorganic filler include silicates such as talc, calcined clay, unfired clay, mica and glass, oxides such as titanium oxide, alumina, silica and fused silica, calcium carbonate, magnesium carbonate, hydrotalcite and the like. Carbonates, hydroxides such as aluminum hydroxide, magnesium hydroxide, calcium hydroxide, sulfates or sulfites such as barium sulfate, calcium sulfate, calcium sulfite, zinc borate, barium metaborate, aluminum borate, boron Examples thereof include borates such as calcium oxide and sodium borate, nitrides such as aluminum nitride, boron nitride, silicon nitride, and carbon nitride, titanates such as strontium titanate and barium titanate. As the inorganic filler, one of these can be used alone, or two or more can be used in combination. Among these, silica is particularly preferable, and fused silica (particularly spherical fused silica) is preferable in terms of excellent low thermal expansion. The shape is crushed and spherical, but in order to reduce the melt viscosity of the resin composition in order to ensure the impregnation of the fiber substrate, a method of use that suits the purpose, such as using spherical silica, is adopted. .

The average particle diameter of the inorganic filler is not particularly limited, but is preferably 0.01 to 5.0 μm, particularly preferably 0.1 to 2.0 μm. If the particle size of the inorganic filler is less than the lower limit value, the viscosity of the varnish increases, which may affect the workability when producing the prepreg 10. When the upper limit is exceeded, phenomena such as sedimentation of the inorganic filler may occur in the varnish.
This average particle diameter can be measured, for example, by a particle size distribution meter (manufactured by HORIBA, LA-500).

  The inorganic filler is not particularly limited, and an inorganic filler having a monodispersed average particle diameter can be used, and an inorganic filler having a polydispersed average particle diameter can be used. Furthermore, one type or two or more types of inorganic fillers having an average particle size of monodisperse and / or polydisperse may be used in combination.

  Furthermore, spherical silica (especially spherical fused silica) having an average particle size of 5.0 μm or less is preferable, and spherical fused silica having an average particle size of 0.01 to 2.0 μm is particularly preferable. Thereby, the filling property of an inorganic filler can be improved.

  Although content of the said inorganic filler is not specifically limited, 20 to 80 weight% of the whole resin composition is preferable, and 30 to 70 weight% is especially preferable. When the content is within the above range, particularly low thermal expansion and low water absorption can be achieved.

When a cyanate resin (particularly a novolac-type cyanate resin) is used as the thermosetting resin, it is preferable to use an epoxy resin (substantially free of halogen atoms). Examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, bisphenol S type epoxy resin, bisphenol M type epoxy resin, bisphenol P type epoxy resin, and bisphenol Z type epoxy resin. Type epoxy resins, phenol novolac type epoxy resins, cresol novolac epoxy resins and other novolak type epoxy resins, biphenyl type epoxy resins, xylylene type epoxy resins, biphenyl aralkyl type epoxy resins and other aryl alkylene type epoxy resins, naphthalene type epoxy resins, anthracene Type epoxy resin, phenoxy type epoxy resin, dicyclopentadiene type epoxy resin, norbornene type epoxy resin, adamantane type An epoxy resin, a fluorene type epoxy resin, etc. are mentioned. As the epoxy resin, one of these can be used alone, or two or more having different weight average molecular weights are used in combination, or one or two or more thereof and a prepolymer thereof are used in combination. You can also.
Among these epoxy resins, aryl alkylene type epoxy resins are particularly preferable. Thereby, moisture absorption solder heat resistance and a flame retardance can be improved.

  The arylalkylene-type epoxy resin refers to an epoxy resin having one or more arylalkylene groups in a repeating unit. For example, a xylylene type epoxy resin, a biphenyl dimethylene type epoxy resin, etc. are mentioned. Among these, a biphenyl dimethylene type epoxy resin is preferable. The biphenyl dimethylene type epoxy resin can be represented by, for example, the formula (II).

  The average repeating unit n of the biphenyl dimethylene type epoxy resin represented by the formula (II) is not particularly limited, but is preferably 1 to 10, and particularly preferably 2 to 5. When the average repeating unit n is less than the lower limit, the biphenyl dimethylene type epoxy resin is easily crystallized, and the solubility in a general-purpose solvent is relatively lowered, which may make handling difficult. On the other hand, if the average repeating unit n exceeds the upper limit, the fluidity of the resin is lowered, which may cause molding defects.

  Although content of the said epoxy resin is not specifically limited, 1 to 55 weight% of the whole resin composition is preferable, and 2 to 40 weight% is especially preferable. If the content is less than the lower limit, the reactivity of the cyanate resin may decrease, or the moisture resistance of the product obtained may decrease, and if the content exceeds the upper limit, the heat resistance may decrease.

The weight average molecular weight of the epoxy resin is not particularly limited, but a weight average molecular weight of 500 to 20,000 is preferable, and 800 to 15,000 is particularly preferable. If the weight average molecular weight is less than the lower limit value, tackiness may occur in the prepreg 10, and if the upper limit value is exceeded, the impregnation property into the sheet-like base material is lowered when the prepreg 10 is produced, and a uniform product is obtained. It may not be possible.
The weight average molecular weight of the epoxy resin can be measured by GPC, for example.

  When using cyanate resin (especially novolak-type cyanate resin) as said thermosetting resin, it is preferable to use a phenol resin. Examples of the phenol resin include novolak-type phenol resins, resol-type phenol resins, and arylalkylene-type phenol resins. As the phenolic resin, one of these can be used alone, or two or more having different weight average molecular weights are used in combination, or one or two or more thereof and a prepolymer thereof are used in combination. You can also. Among these, arylalkylene type phenol resins are particularly preferable. Thereby, moisture absorption solder heat resistance can be improved further.

Examples of the aryl alkylene type phenol resin include a xylylene type phenol resin and a biphenyl dimethylene type phenol resin. A biphenyl dimethylene type phenol resin can be shown, for example by Formula (III).

  Although the repeating unit n of the biphenyl dimethylene type phenol resin represented by the formula (III) is not particularly limited, 1 to 12 is preferable, and 2 to 8 is particularly preferable. If the average repeating unit n is less than the lower limit, the heat resistance may be lowered. Moreover, when the said upper limit is exceeded, compatibility with other resin will fall and workability | operativity may fall.

  By combining the above-mentioned cyanate resin (particularly novolak-type cyanate resin) and arylalkylene-type phenol resin, the crosslinking density can be controlled and the reactivity can be easily controlled.

  Although content of the said phenol resin is not specifically limited, 1 to 55 weight% of the whole resin composition is preferable, and 5 to 40 weight% is especially preferable. If the content is less than the lower limit, the heat resistance may be reduced, and if the content exceeds the upper limit, the characteristics of low thermal expansion may be impaired.

The weight average molecular weight of the phenol resin is not particularly limited, but a weight average molecular weight of 400 to 18,000 is preferable, and 500 to 15,000 is particularly preferable. If the weight average molecular weight is less than the lower limit value, tackiness may occur in the prepreg 10, and if the upper limit value is exceeded, the impregnation property into the sheet-like base material is lowered when the prepreg 10 is produced, and a uniform product is obtained. It may not be possible.
The weight average molecular weight of the phenol resin can be measured by, for example, GPC.

  Furthermore, the cyanate resin (especially novolac type cyanate resin), the phenol resin (arylalkylene type phenolic resin, particularly biphenyldimethylene type phenolic resin) and the epoxy resin (arylalkylene type epoxy resin, particularly biphenyldimethylene type epoxy resin). When a board (especially a circuit board) is produced using a combination with the above, particularly excellent dimensional stability can be obtained.

The resin composition is not particularly limited, but it is preferable to use a coupling agent. The coupling agent uniformly fixes the thermosetting resin and the inorganic filler to the sheet-like substrate by improving the wettability of the interface between the thermosetting resin and the inorganic filler. The heat resistance, particularly the solder heat resistance after moisture absorption can be improved.
As the coupling agent, any commonly used one can be used. Specifically, an epoxy silane coupling agent, a cationic silane coupling agent, an aminosilane coupling agent, a titanate coupling agent, and a silicone oil type coupling. It is preferable to use one or more coupling agents selected from among the agents. Thereby, the wettability with the interface of an inorganic filler can be made high, and thereby heat resistance can be improved more.

  The addition amount of the coupling agent is not particularly limited because it depends on the specific surface area of the inorganic filler, but is preferably 0.05 to 3 parts by weight, particularly 0.1 to 2 parts per 100 parts by weight of the inorganic filler. Part by weight is preferred. If the content is less than the lower limit, the inorganic filler cannot be sufficiently coated, and thus the effect of improving the heat resistance may be reduced. If the content exceeds the upper limit, the reaction is affected, and the bending strength is reduced. There is a case.

  A curing accelerator may be used in the resin composition as necessary. A well-known thing can be used as said hardening accelerator. For example, organic metal salts such as zinc naphthenate, cobalt naphthenate, tin octylate, cobalt octylate, bisacetylacetonate cobalt (II), trisacetylacetonate cobalt (III), triethylamine, tributylamine, diazabicyclo [2,2 , 2] tertiary amines such as octane, 2-phenyl-4-methylimidazole, 2-ethyl-4-ethylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4-methyl-5-hydroxyimidazole Imidazoles such as 2-phenyl-4,5-dihydroxyimidazole, phenolic compounds such as phenol, bisphenol A, and nonylphenol, organic acids such as acetic acid, benzoic acid, salicylic acid, paratoluenesulfonic acid, and the like, or a mixture thereof. . As the curing accelerator, one kind including these derivatives can be used alone, or two or more kinds including these derivatives can be used in combination.

  Although content of the said hardening accelerator is not specifically limited, 0.05-5 weight% of the whole said resin composition is preferable, and 0.2-2 weight% is especially preferable. If the content is less than the lower limit, the effect of promoting curing may not appear, and if the content exceeds the upper limit, the storability of the prepreg 10 may be reduced.

In the resin composition, thermoplastic resins such as phenoxy resin, polyimide resin, polyamideimide resin, polyphenylene oxide resin, polyethersulfone resin, polyester resin, polyethylene resin, polystyrene resin, styrene-butadiene copolymer, styrene-isoprene copolymer are used. Polystyrene thermoplastic elastomers such as polymers, polyolefin thermoplastic elastomers, polyamide elastomers, thermoplastic elastomers such as polyester elastomers, and diene elastomers such as polybutadiene, epoxy modified polybutadiene, acrylic modified polybutadiene, methacryl modified polybutadiene, etc. You may do it.
The resin composition may contain additives other than the above components such as pigments, dyes, antifoaming agents, leveling agents, ultraviolet absorbers, foaming agents, antioxidants, flame retardants, and ion scavengers as necessary. May be added.

(Second resin layer)
Similar to the first resin layer 1, the second resin layer 2 is composed of a resin composition including a thermosetting resin such as an epoxy resin or a cyanate ester resin, and a curing agent.
Here, the resin compositions constituting the second resin layer 2 and the first resin layer 1 may be the same or different, but are preferably different. Thereby, a different function can be provided to each resin layer.
About a specific resin composition, the thing similar to the resin composition which comprises the 1st resin layer 1 can be used.

  A prepreg having such a first resin layer and a second resin layer is obtained, for example, by impregnating a sheet-like base material with the above-described resin composition. Thereby, a prepreg suitable for manufacturing a printed wiring board excellent in various characteristics such as dielectric characteristics, mechanical and electrical connection reliability under high temperature and high humidity can be obtained.

Examples of the method of impregnating the fiber base material with the above-described resin composition include, for example, a method of preparing a resin varnish using the resin composition of the present invention, immersing the fiber base material in the resin varnish, and a method of applying with various coaters , Spraying method, vacuum laminating method and the like. Among these, the vacuum laminating method is preferable. Thereby, the uneven distribution position of the resin layer with respect to a sheet-like base material can be controlled freely, and it is excellent also in the impregnation property.
The vacuum laminating method will be briefly described. A carrier material obtained by previously applying a resin composition constituting the first resin layer 1 and the second resin layer 2 to a carrier film or the like is manufactured, and the carrier material is used as a sheet-like substrate. After laminating from both sides in vacuum, a method of heat treatment drying in vacuum or in the air can be mentioned. According to such a method, the resin composition on both sides of the prepreg 10 can be made different by changing only the thicknesses of the first resin layer 1 and the second resin layer 2 applied to the carrier material and the resin composition constituting the two. It becomes easy to adjust the thickness of each resin layer.

The solvent used in the resin varnish desirably exhibits good solubility in the resin component in the resin composition, but a poor solvent may be used within a range that does not adversely affect the resin varnish. Examples of the solvent exhibiting good solubility include acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, tetrahydrofuran, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, ethylene glycol, cellosolve and carbitol.
The solid content of the resin varnish is not particularly limited, but the solid content of the resin composition is 40-8.
0 wt% is preferable, and 50 to 65 wt% is particularly preferable. Thereby, the impregnation property to the fiber base material of the resin varnish can further be improved. A prepreg can be obtained by impregnating the fiber base material with the resin composition and drying at a predetermined temperature, for example, 80 to 200 ° C.

The linear expansion coefficient in the plane direction after curing of the prepreg 10 is not particularly limited, but is preferably 20 ppm or less, and particularly preferably 5 to 10 ppm. When the linear expansion coefficient is within the above range, the crack resistance against repeated thermal shock can be improved.
The linear expansion coefficient in the plane direction can be evaluated by elevating the temperature at 10 ° C./min using, for example, a TMA apparatus (manufactured by TA Instruments).
After the prepreg 10 is cured, for example, it means a state where the reaction rate when evaluated with a DSC apparatus is 80% or more.

(substrate)
The circuit board 5 is formed on the substrate 30 so as to protrude from both surfaces of the core material 4 and the core material 4.
Examples of the core material 4 include a printed wiring board such as Sumitomo Bakelite ELC-4785GS and other FR4 and FR5.

  Although the thickness of the core material 4 is not specifically limited, 50-200 micrometers is preferable and 50-100 micrometers is especially preferable. When the thickness is within the above range, the circuit board finally obtained can be made thin and excellent in suppressing deformation such as warpage.

  The circuit wiring 5 is obtained by, for example, copper plating or etching a copper foil. The height of the circuit wiring 5 is not particularly limited, but is preferably 35 μm or less, and particularly preferably 3 to 25 μm. When the height is within the above range, the balance between circuit formability and embedding property is excellent.

  A semiconductor device can be obtained by mounting a semiconductor element on the circuit board 70 constituted by such a prepreg 10 and the substrate 30. As described above, since the thickness of the circuit board 70 can be reduced, the thickness of the semiconductor device can also be reduced.

  In the above description, the case where the prepreg 10 is laminated on both surfaces of the substrate 30 has been described. However, the present invention is not limited to this, and the prepreg 10 may be laminated in two or more layers. In this case, it is not necessary to use the same prepreg.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example and a comparative example, this invention is not limited to this.

Example 1
1) Formation of first resin layer (preparation of resin varnish)
15% by weight of novolak cyanate resin (Lonza Japan, Primaset PT-30, weight average molecular weight of about 2,600) as thermosetting resin, biphenyldimethylene type epoxy resin (Nippon Kayaku, NC) as epoxy resin -3000P, epoxy equivalent 275) 8 wt%, phenol resin as biphenyldimethylene type phenol resin (Maywa Kasei Co., Ltd., MEH-7851-S, hydroxyl group equivalent 203) 7 wt%, and epoxysilane type coupling agent as coupling agent (Nihon Unicar Co., Ltd., A-187) is dissolved in methyl ethyl ketone at room temperature with respect to 100 parts by weight of the inorganic filler described later, and spherical fused silica SFP-10X (electrochemical industry) is used as the inorganic filler. 20% by weight, average fused particle size 0.3 μm) and spherical fused silica SO-3 R was added (Admatechs Co., Ltd., average particle diameter 1.5 [mu] m) 50 wt%, the resin material varnish was prepared by stirring 10 minutes using a high speed stirrer.

(Formation of first carrier material)
A polyethylene terephthalate film (manufactured by Mitsubishi Chemical Polyester Co., Ltd., SFB-38, thickness 38 μm, width 480 m) is used as a carrier film. Thus, a carrier layer 1 (finally formed with a first resin layer) was obtained by forming a resin layer having a thickness of 20 μm and a width of 410 mm so as to be positioned at the center in the width direction of the carrier film.

2) Formation of second resin layer (preparation of resin varnish)
15% by weight of novolak cyanate resin (Lonza Japan, Primaset PT-30, weight average molecular weight of about 2,600) as thermosetting resin, biphenyldimethylene type epoxy resin (Nippon Kayaku, NC) as epoxy resin -3000P, epoxy equivalent 275) 8 wt%, phenol resin as biphenyldimethylene type phenol resin (Maywa Kasei Co., Ltd., MEH-7851-S, hydroxyl group equivalent 203) 7 wt%, and epoxysilane type coupling agent as coupling agent (Nihon Unicar Co., Ltd., A-187) is dissolved in methyl ethyl ketone at room temperature with respect to 100 parts by weight of the inorganic filler described later, and spherical fused silica SFP-10X (electrochemical industry) is used as the inorganic filler. 20% by weight, average fused particle size 0.3 μm) and spherical fused silica SO-3 R was added (Admatechs Co., Ltd., average particle diameter 1.5 [mu] m) 50 wt%, the resin material varnish was prepared by stirring 10 minutes using a high speed stirrer.

(Formation of second carrier material)
A polyethylene terephthalate film (manufactured by Mitsubishi Chemical Polyester Co., Ltd., SFB-38, thickness 38 μm, width 480 m) is used as a carrier film. Thus, a resin layer having a thickness of 8 μm and a width of 360 mm was formed so as to be positioned at the center in the width direction of the carrier film to obtain a carrier material 2 (finally formed a second resin layer).

3) Production of prepreg Using a glass fiber substrate (cross type # 1015, width 360 mm, thickness 15 μm, basis weight 17 g / m ² ) as a fiber substrate, a prepreg was produced by a vacuum laminator and a hot air dryer. Specifically, the carrier material 1 and the carrier material 2 are overlapped on both surfaces of the glass fiber base so that they are positioned at the center in the width direction of the glass fiber base, respectively, and under reduced pressure conditions of 750 Torr, Bonding was performed using a laminate roll. Here, in the inner region of the width direction dimension of the glass fiber base material, the resin layers of the carrier material 1 and the carrier material 2 are respectively bonded to both sides of the fiber cloth, and the outer region of the width direction dimension of the glass fiber base material. , The resin layers of the carrier material 1 and the carrier material 2 were joined together. Next, the above-mentioned joined piece was heated for 2 minutes through a horizontal conveyance type hot air drying apparatus set at 120 ° C. without applying pressure, and the thickness was 35 μm (first resin layer: 16 μm, A prepreg having a fiber base material of 15 μm and a second resin layer of 4 μm was obtained.

4) Manufacture of a circuit board A comb-shaped pattern with a conductor spacing of 50 μm on the surface, a prepreg is stacked on a core substrate with a circuit thickness of 18 μm and a residual copper ratio of 50%, and a copper foil is further stacked on the outermost layer. A multilayer substrate was obtained by pressure molding (3 MPa, 200 ° C., 90 minutes).

5) Manufacture of Semiconductor Device After forming a circuit on the outermost copper foil (thickness 12 μm), a semiconductor element was mounted to obtain a semiconductor device.

(Example 2)
The same procedure as in Example 1 was performed except that the following was used as the sheet-like substrate.
A glass fiber substrate (cross type # 106, width 360 mm, thickness 35 μm, basis weight 24 g / m ² ) was used as the sheet-like substrate.

(Example 3)
Example 1 was the same as Example 1 except that the resin composition of the first resin layer was as follows.
As a thermosetting resin, 100 parts by weight of an epoxy resin (manufactured by Japan Epoxy Resin Co., “Ep5048”), 2 parts by weight of a curing agent (dicyandiamide) and 0.1 part by weight of a curing accelerator (2-ethyl-4-methylimidazole) A resin varnish was obtained by dissolving in 100 parts by weight of methyl cellosolve. A prepreg having a thickness of 30 μm (first resin layer: 11 μm, fiber substrate: 15 μm, second resin layer: 4 μm) was obtained.

(Comparative Example 1)
Example 1 was repeated except that the fiber base material and carrier materials 1 and 2 were as follows.
A glass fiber substrate (cross type # 1080, thickness 55 μm, basis weight 47 g / m ² ) was used as the fiber substrate. The thicknesses of the resin layers of carrier material 1 and carrier material 2 were 20 μm (carrier material 1) and 20 μm (carrier material 2), respectively.
The thickness of the obtained prepreg was 65 μm (first resin layer: 5 μm, fiber base material: 55 μm, second resin layer: 5 μm). Then, the surface has a comb pattern with a conductor spacing of 50 μm, a prepreg is stacked on a core substrate with a circuit thickness of 18 μm and a residual copper ratio of 50%, and a copper foil is further stacked on the outermost layer. 3 MPa, 200 ° C., 90 minutes) to obtain a multilayer substrate. Further, after forming a circuit on the outermost copper foil (thickness 12 μm), a semiconductor element was mounted to obtain a semiconductor device.

The semiconductor device obtained in each example and comparative example was evaluated as follows. The evaluation items are shown together with the contents. The obtained results are shown in Table 1.
1. Circuit board thickness The thickness of the obtained circuit board was measured.

2. Insulation reliability After making a four-layer printed wiring board for insulation reliability test having a comb pattern with a conductor spacing of 50 μm on the inner and outer layers, and measuring these insulation resistances with an automatic super insulation resistance meter (manufactured by ADVANTEST) In a PCT-130 ° C / 85% atmosphere, a DC voltage of 50 V was applied, and the insulation resistance after 96 hours was measured. The applied voltage at the time of measurement was 100 V for 1 minute, the case where the insulation resistance was 1 × 10 ⁹ Ω or more was rated as ◯, and the case where the insulation resistance was less than 1 × 10 ⁹ Ω was rated as x.

3. The cross section of the embedding comb pattern portion was observed with a microscope to evaluate the embedding property of the resin layer. Each code is as follows.
A: All samples were excellent in embeddability.
○: There was a part of the circuit wiring contact with the glass woven fabric, but there was no practical problem.
(Triangle | delta): There existed a part of circuit wiring contact to glass woven fabric, and it was unpractical.
X: The resin layer was not sufficiently embedded and had voids or the like.

As is apparent from Table 1, the thickness of the circuit boards of Examples 1 to 3 was 200 μm or less, indicating that a thin circuit board was obtained.
Moreover, the circuit boards of Examples 1 to 3 were excellent in insulation reliability and embeddability.
Moreover, it was confirmed that the semiconductor devices of Examples 1 to 3 operate normally.

FIG. 1 is a cross-sectional view schematically showing an example of a prepreg. FIG. 2 is a cross-sectional view showing an example of a substrate. FIG. 3 is a cross-sectional view schematically showing a state where the prepreg and the substrate are laminated. FIG. 4 is a cross-sectional view showing an example of the circuit board of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st resin layer 2 2nd resin layer 4 Core material 41 Through hole 5 Circuit wiring part 5a Circuit wiring part 5b Circuit wiring part 51 Space part 10 Prepreg 10a Prepreg 10b Prepreg 101 Through hole 11 Core layer 30 Substrate 70 Circuit board

Claims (7)

A prepreg having a core layer of a sheet-like substrate; a first resin layer formed on one side of the core layer; and a second resin layer formed on the other side; a substrate on which circuit wiring is formed; Is a circuit board formed by laminating,
The first resin layer of the prepreg is bonded to the surface of the substrate where the circuit wiring is formed,
The thickness of the first resin layer is larger than the thickness of the second resin layer, the thickness of the first resin layer is B1 [μm], and the thickness of the circuit wiring in contact with the first resin layer is t1 [ μm] and the remaining copper ratio of the circuit wiring is S [%], and the thickness from the upper end surface of the circuit wiring portion to the core layer is t2 [μm], B1 = t2 + t1 × (1−S / 100) A circuit board characterized by satisfying the following relationship.   The circuit board according to claim 1, wherein the sheet-like base material has a thickness of 5 to 25 μm.   The circuit board according to claim 1, wherein the prepreg has a coefficient of thermal expansion in the plane direction after curing of 20 ppm / ° C. or less.   4. The circuit according to claim 1, wherein a ratio between the thickness of the first resin layer and the thickness of the second resin layer (second resin layer / first resin layer) is 0.1 to 1. 5. substrate.   The circuit board according to claim 1, wherein a thickness of the second resin layer is 5 to 15 μm.   The circuit board according to claim 1, wherein the sheet-like base material has a dielectric constant of 7 or less and a thermal expansion coefficient of 6 ppm / ° C. or less.   A semiconductor device comprising a semiconductor element mounted on the circuit board according to claim 1.

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