JP5368419B2 - Prepreg, substrate and semiconductor device - Google Patents

Abstract

This invention provides a prepreg that can cope with a demand for a film thickness reduction, enables different applications, functions, performances or properties or the like to be imparted respectively to both sides of the prepreg, and enables the amount of a resin composition to be set depending upon a circuit wiring pattern to be buried. There are also provided a process for producing the prepreg, a substrate comprising the prepreg, and a semiconductor device. The prepreg is characterized by comprising a core layer including a sheet-like base material, a first resin layer provided on one side of the core layer and formed of a first resin composition, and a second resin layer provided on the other side of the core layer and formed of a second resin composition, a conductor layer being provided on the first resin layer, at least one of a requirement that the first resin layer is different from the second resin layer in thickness and a requirement that the first resin composition is different from the second resin composition in composition, being satisfied.

Description

  The present invention relates to a prepreg, a substrate, and a semiconductor device.

A circuit board is formed using a prepreg obtained by impregnating a glass fiber base material with a thermosetting resin. 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, it has been difficult to thin a prepreg containing glass fibers. Moreover, in the conventional prepreg, the resin material was carry | supported by the object centering on glass fiber. Therefore, when the amount of resin required differs depending on the circuit pattern of the inner layer, the resin may protrude or the resin that fills the circuit may be insufficient.

JP 2004-216784 A

An object of the present invention is to provide a prepreg that can cope with thinning and can adjust the amount of resin according to a circuit pattern.
Moreover, the objective of this invention is providing the board | substrate and semiconductor device which have the said prepreg.

Such an object is achieved by the present invention described in the following (1) to (6).
(1) A fiber base composed of glass fibers, a first resin layer located on one side of the fiber base, and a second resin layer located on the other side of the fiber base Have
When 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, and the thickness of the second resin layer is B2, 0 <B2 / B1 ≦ 0.4 satisfied,
The resin composition constituting the first resin layer and the resin composition constituting the second resin layer are at least one selected from a cyanate resin, an epoxy resin, and a phenol resin, respectively, and the same thermosetting resin And an inorganic filler,
The inorganic filler is particles having an average particle diameter of 0.01 to 5.0 μm,
The content of the inorganic filler is 40 to 80% by weight of the entire resin composition,
A prepreg characterized by having a coefficient of thermal expansion in the plane direction of the prepreg of 10 ppm or less.
(2) The prepreg according to (1) above, wherein a circuit wiring portion is embedded in the first resin layer.
(3) When the thickness of the entire prepreg is T0 [μm] and the thickness of the circuit wiring portion is t1 [μm],
The prepreg according to (2), which satisfies a relationship of T0-t1 ≦ 35 μm.
(4) The prepreg according to the above (2) or (3), wherein t2 is 0 to 15 μm when the distance between the circuit wiring part and the fiber base material is t2 [μm].
(5) A substrate formed by laminating a plurality of prepregs,
A substrate, wherein at least one of the plurality of prepregs is the prepreg according to any one of (1) to (4).
(6) A semiconductor device in which a semiconductor element is mounted on the substrate according to (5).

ADVANTAGE OF THE INVENTION According to this invention, the prepreg which can respond to thin film formation and can adjust resin amount according to a circuit pattern can be provided. That is, the fiber base material can be unevenly distributed in the thickness direction of the prepreg according to the circuit pattern (for example, the ratio of remaining copper, the thickness of the copper foil), thereby obtaining a prepreg having only a necessary resin amount. .
Further, according to the present invention, a substrate and a semiconductor device having the prepreg can be provided, whereby a thin substrate and a semiconductor device can be obtained.

FIG. 1 is a cross-sectional view schematically showing an example of the prepreg of the present invention. FIG. 2 is a cross-sectional view schematically showing a state in which the fiber base material is unevenly distributed in the thickness direction of the prepreg. FIG. 3 is a cross-sectional view schematically showing a state in which the fiber base material is unevenly distributed in the thickness direction of the prepreg. FIG. 4 is a process diagram showing an example of a process for producing the prepreg of the present invention. FIG. 5 is a cross-sectional view showing an example of the substrate of the present invention. FIG. 6 is a schematic diagram schematically showing the state of the prepreg constituting the substrate. FIG. 7 is a cross-sectional view showing an example of a semiconductor device of the present invention.

  Hereinafter, the prepreg, substrate and semiconductor device of the present invention will be described.

First, a preferred embodiment of a prepreg will be described based on the drawings.
FIG. 1 is a cross-sectional view showing an example of the prepreg of the present invention.
In the prepreg 10, the resin material 2 is supported on the fiber substrate 1.
The fiber base material 1 is unevenly distributed with respect to the thickness direction of the prepreg 10 (vertical direction in FIG. 1).

The fiber substrate 1 preferably has a thickness of 25 μm or less. Thereby, the thickness of the prepreg 10 can be made thin.
Specifically, the thickness of the fiber substrate 1 is preferably 20 μm or less, and particularly preferably 10 to 15 μm. When the thickness of the fiber base material 1 is within the above range, the balance between the reduction in the thickness of the substrate and the strength of the substrate, which will be described later, and the processability and reliability of interlayer connection are excellent.

In a conventional prepreg manufacturing method (for example, a method in which a fiber cloth base material is dipped and impregnated in a resin varnish and dried using a normal coating apparatus), a resin material is supported on a fiber base material having a thickness of 30 μm or less. It was difficult to obtain a prepreg. That is, when a thin fiber substrate is immersed in a thermosetting resin and passed through a large number of transport rolls, or when the amount of resin material impregnated into the fiber substrate is adjusted, stress is applied to the fiber substrate. In some cases, the fiber base may be opened (expanded), or the fiber base may be cut off when it is pulled.
On the other hand, in the present invention, the resin material 2 can be supported on the fiber base material 1 having a thickness of 25 μm or less by using a method for manufacturing the prepreg 10 as will be described later. In addition to the prepreg 10 having a thickness of 35 mm, a prepreg 10 having a thickness of 35 μm or less can be obtained. Further, the thickness of the prepreg 10 after forming the substrate can be made 35 μm or less between the conductor circuit layers. If the thickness between the conductor circuit layers can be 35 μm or less, the thickness of the finally obtained substrate can be reduced.

(Fiber base)
Examples of such fiber base material 1 include glass fiber base materials such as glass woven fabric and glass nonwoven fabric, polyamide resin fibers, aromatic polyamide resin fibers, polyamide resin fibers such as wholly aromatic polyamide resin fibers, polyester resin fibers, Synthetic fiber substrate, kraft paper, cotton linter composed of woven or non-woven fabric mainly composed of aromatic polyester resin fiber, polyester resin fiber such as wholly aromatic polyester resin fiber, polyimide resin fiber, fluororesin fiber, etc. Examples thereof include organic fiber base materials such as paper base materials mainly composed of paper, mixed paper of linter and kraft pulp, and the like. Among these, a glass fiber base material is preferable. Thereby, the intensity | strength of the prepreg 10 can be improved. Moreover, the thermal expansion coefficient of the prepreg 10 can be reduced.

  As glass which comprises such a glass fiber base material, E glass, C glass, A glass, S glass, D glass, NE glass, T glass, H glass etc. are mentioned, for example. Among these, T glass is 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.

(Resin material)
Although the resin material 2 is not specifically limited, It is preferable to be comprised with the resin composition containing a thermosetting resin. Thereby, the heat resistance of the prepreg 10 can be improved.
Examples of the thermosetting resin include novolak type phenol resins such as phenol novolak resin, cresol novolak resin, bisphenol A novolak resin, unmodified resol phenol resin, oil-modified resole phenol modified with tung oil, linseed oil, walnut oil, and the like. Resins and other phenolic resins such as resol phenolic resins, bisphenol A epoxy resins, bisphenol F epoxy resins and other bisphenol epoxy resins, novolac epoxy resins, cresol novolac epoxy resins and other novolac epoxy resins, biphenyl epoxy resins and other epoxies Resin, urea (urea) resin, resin having triazine ring such as melamine resin, unsaturated polyester resin, bismaleimide resin, polyurethane resin, diallyl phthalate resin, silicon Resins, resins having a benzoxazine ring, cyanate ester resins.
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 is easily crystallized, and the solubility in a general-purpose solvent is relatively lowered, which may make handling difficult. Moreover, when average repeating unit n exceeds the said upper limit, melt viscosity will become high too much and the moldability of a prepreg 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.

  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 prepreg 10 is thinned (thickness of 35 μm or less), it can be excellent in strength. Furthermore, it is possible to improve the low thermal expansion of the prepreg.
Examples of the inorganic filler include talc, alumina, glass, silica, mica, aluminum hydroxide, magnesium hydroxide and the like. Among these, silica is preferable, and fused silica (particularly spherical fused silica) is preferable in that it has 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 1, a method of use that suits the purpose, such as using spherical silica, is adopted. The

The average particle size of the inorganic filler is 0 . 01-5.0 micrometers is preferable and 0.2-2.0 micrometers is especially preferable. 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).

  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.

The content of the inorganic filler is preferably 40 to 80 wt% of the total tree fat composition, in particular 60 to 70% by weight. 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 phenol novolac type epoxy resins, bisphenol type epoxy resins, naphthalene type epoxy resins, arylalkylene type epoxy resins and the like. Among these, aryl alkylene type epoxy resins are 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. When the weight average molecular weight is less than the lower limit value, tackiness may occur in the prepreg 10, and when the upper limit value is exceeded, the impregnation property to the base material is lowered when the prepreg 10 is produced, and a uniform product cannot be obtained. There is a case.
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. Among these, arylalkylene type phenol resins are 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. The biphenyl dimethylene type phenol resin can be represented by, for example, the 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-described cyanate resin (particularly novolac-type cyanate resin) and arylalkylene-type phenol resin, the crosslink density can be controlled and the adhesion between the metal and the resin can be improved.

  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. When the weight average molecular weight is less than the lower limit value, tackiness may occur in the prepreg 10, and when the upper limit value is exceeded, the impregnation property to the fiber base material 1 is reduced when the prepreg 10 is manufactured, 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 or the like and the inorganic filler to the fiber substrate 1 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 surface area of the inorganic filler, but is preferably 0.05 to 3 parts by weight, particularly 0.1 to 2 parts by weight with respect to 100 parts by weight of the inorganic filler. Part 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. .

  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, a thermoplastic resin such as a phenoxy resin, a polyimide resin, a polyamideimide resin, a polyphenylene oxide resin, or a polyethersulfone resin may be used in combination.
Moreover, you may add additives other than the said components, such as a pigment and antioxidant, to the said resin composition as needed.

The prepreg 10 of the present invention is characterized in that the resin material 2 as described above is supported on the fiber base material 1, and the fiber base material 1 is unevenly distributed in the thickness direction of the prepreg 10. Thereby, the amount of resin can be adjusted according to a circuit pattern.
Here, the state where the fiber base material 1 is unevenly distributed with respect to the thickness direction of the prepreg 10 will be described with reference to FIG. 2A and 2B are cross-sectional views schematically showing a state where the fiber base material 1 is unevenly distributed with respect to the prepreg 10. As shown in FIGS. 2 (a) and 2 (b), it means that the center of the fiber base material 1 is shifted from the center line AA in the thickness direction of the prepreg 10. In FIG. 2A, the lower surface (lower side in FIG. 2) of the fiber base 1 is substantially coincident with the lower surface (lower side in FIG. 2) of the prepreg 10. In FIG.2 (b), the fiber base material 1 is arrange | positioned between centerline AA and the surface of the lower side (lower side in FIG. 2) of the prepreg 10. In FIG. The fiber substrate 1 may partially overlap the center line AA.

In a conventional method for producing a prepreg (for example, a method in which a fiber base material is immersed and dried in a resin varnish using a normal coating apparatus), a resin material is formed on the fiber base material. However, in this case, if the circuit wiring pattern is different on both sides of the prepreg (especially when the remaining copper ratio of the circuit pattern is different), the amount of resin required on both sides is different, but this can be accommodated. There wasn't. In this case, when the substrate is manufactured, the resin constituting the prepreg may protrude or the resin necessary for filling the circuit pattern may be insufficient.
On the other hand, in the prepreg 10 of the present invention, since the fiber base 1 can be unevenly distributed in the thickness direction of the prepreg 10, the prepreg 10 having a resin amount corresponding to the pattern of the circuit to be built up is designed. Can be handled. Furthermore, it becomes possible to manufacture a thin prepreg 10 having a thickness of 35 μm or less, and the fiber substrate 1 is unevenly distributed in the thickness direction of the prepreg 10 to reduce the thickness of the finally obtained semiconductor device. You can also. This is because the thickness of the prepreg 10 is simply thin, and the resin amount of the prepreg 10 can be adjusted in accordance with the remaining copper ratio of the circuit pattern, etc., so there is no need to provide an extra resin layer. is there.

  In another expression for the unevenly distributed state, for example, as shown in FIG. 3, there is a fiber base 1 having a thickness of preferably 25 μm or less in the prepreg 10, and the first side of the fiber base 1 is the first side. It means that the first resin layer 21 and the second resin layer 22 are provided on the other surface side, and the thickness of the first resin layer 21 and the thickness of the second resin layer 22 are different. That is, the ratio (B2 / B1) when the thickness B1 [μm] of the thick first resin layer 21 and the thickness B2 [μm] of the thin second resin layer 22 is 0 < It is only necessary to satisfy B2 / B1 <1.

In this case, the ratio (B2 / B1) between the thickness B1 of the first resin layer 21 and the thickness B2 of the second resin layer 22 is preferably 0.4 or less , particularly 0.2 to 0. 4 is preferred. When the ratio is within the above range, the waviness of the fiber substrate 1 can be particularly reduced, and thereby the flatness of the prepreg 10 can be further improved.

  The thickness of the B2 is not particularly limited, but is preferably 5 to 15 μm, particularly preferably 8 to 10 μm, when the surface plating property is mainly required. Thereby, plating property can be provided to one surface side.

  Moreover, in the prepreg 10 of the present invention, for example, in the prepreg 10 as shown in FIG. 3, in addition to the state in which the thickness of the first resin layer 21 and the thickness of the second resin layer 22 are different, the first resin layer The resin composition constituting the resin 21 and the resin composition constituting the second resin layer 22 may be different from each other. Examples of the different resin composition include a resin composition having a different composition such as a different content of the inorganic filler, a resin composition using different types of thermosetting resins, and the like. If a resin composition having different compositions on both sides of the prepreg 10 can be obtained, a resin layer can be designed according to the required performance, and the range of resin selection can be expanded. For example, the resin layer facing the inner layer circuit may be given a different function on both sides of the prepreg 10 such as a flexible composition considering the embedding property and the opposite surface having a hard composition considering the rigidity. it can.

The linear expansion coefficient in the plane direction of such a prepreg 10 is preferably 10 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).

As described above, in the conventional method, it is difficult to carry a fiber base material having a thickness of 30 μm or less. Furthermore, it has been difficult to produce a prepreg having a fiber substrate having a thickness of 35 μm or less.
In the present invention, for example, carrier materials 2a and 2b in which the resin material 2 is previously applied to the carrier film are manufactured, the carrier materials 2a and 2b are laminated on the fiber substrate 1, and then the carrier film is peeled off. It is possible to obtain the prepreg 10 having a normal thickness and the prepreg 10 having a thickness of 35 μm or less by supporting the resin material 2 on the fiber substrate 1 having a thickness of 25 μm or less.

Here, the carrier material 2a, 2b having the resin material 2 in advance is manufactured, the carrier material 2a, 2b is laminated on the fiber base material 1, and then the method of peeling the carrier film is specifically described with reference to FIG. explain. FIG. 4 is a process diagram showing an example of a process for producing the prepreg of the present invention.
First, carrier materials 2a and 2b on which resin materials 2 having different thicknesses are formed are prepared. The carrier materials 2a and 2b can be obtained by, for example, a method of applying the resin material 2 to a carrier film.
Next, the carrier materials 2 a and 2 b are overlapped from both sides of the fiber substrate 1 under reduced pressure and bonded by the laminating roll 81 using the vacuum laminating apparatus 8. By joining under reduced pressure, even if there is an unfilled portion inside the fiber base material 1 or at the joint portion between the resin material 2 and the fiber base material 1, this should be a reduced pressure void or a substantial vacuum void. Can do. Therefore, voids generated in the finally obtained prepreg 10 can be reduced. This is because the decompression void or the vacuum void can be removed by a heat treatment described later. As another device for joining the fiber base material 1 and the resin material 2 under such reduced pressure, for example, a vacuum box device or the like can be used.

Next, after bonding the fiber base material 1 and the resin material 2, heat treatment is performed by the hot air drying device 9 at a temperature equal to or higher than the melting temperature of the resin material 2. Thereby, the decompression void etc. which have occurred in the joining process under the decompression can be almost eliminated.
The other heat treatment method can be carried out using, for example, an infrared heating device, a heating roll device, a flat platen hot platen press device, or the like.

  As another method for obtaining such a prepreg 10, a fiber base material 1 having a thickness of 25 μm or less is immersed in a resin varnish having a low viscosity and dried to form a first layer. The prepreg 10 can also be obtained by immersing the film in a film to form the second layer.

In the present invention, the prepreg 10 of the present invention described above can be obtained in this manner.
Moreover, the thickness of the prepreg 10 can be easily reduced to 35 μm or less by changing the thickness of the resin material 2 formed on the carrier film. When the thickness of the prepreg 10 is 35 μm or less, even a multilayer circuit board can be thinned. Thereby, the semiconductor device finally obtained can be made thin.
Specifically, the thickness of the prepreg 10 is preferably 30 μm or less, and particularly preferably 20 to 25 μm or less. When the thickness is within the above range, the substrate can be maintained in a thin state even when the number of layers is increased to 6 or more, and a thin semiconductor device can be finally obtained.

Next, the substrate and the semiconductor device will be described.
As shown in FIG. 5, the substrate 100 includes a core substrate 3, three layers of prepregs (10 a, 10 b, 10 c) provided on the upper side of the core substrate 3 (upper side in FIG. 5), and a lower side of the core substrate 3. 3 layers of prepregs (10d, 10e, 10f) provided on the side (lower side in FIG. 5). A predetermined circuit wiring portion 4 is formed between the core substrate 3 and the prepregs 10a and 10b and between the prepregs (10a and 10b, 10b and 10c, 10d and 10e, and 10e and 10f). A pad portion 5 is provided on the surfaces of the prepregs 10c and 10f. It is preferable to use the prepreg 10 having a thickness of 35 μm or less as described above for at least one (preferably all) of the prepregs 10a to 10f. Thereby, the thickness of the (circuit) substrate 100 can be reduced.
Each circuit wiring portion 4 is electrically connected via a filled via portion 6 provided through each prepreg 10a to 10f.
Since the prepregs 10a to 10f constituting the substrate 100 have the fiber base material 1 unevenly distributed in the thickness direction of each prepreg, the restriction on the circuit height and the like can be reduced, and thereby the degree of freedom in designing the inner layer conductor circuit. Will increase. That is, it becomes easy to form the inner layer conductor circuit. Furthermore, since it can design so that the fiber base material 1 may be arrange | positioned on the opposite side to an inner layer conductor circuit being formed, the malfunction which arises when an inner layer conductor circuit and the fiber base material 1 contact can also be reduced.

FIG. 6 is a schematic diagram schematically showing the prepreg 10 c constituting the substrate 100. As shown in FIG. 6, the circuit wiring portion 4 is embedded in the resin material 2 (first resin layer 21) on the opposite side of the prepreg 10 c where the fiber base material 1 is unevenly distributed. As described above, the resin material 2 (first resin layer 21) is embedded in a gap formed by the circuit wiring portions 4.
Then, as shown in FIG. 3, when the total thickness of the prepreg 10c is T0 [μm] and the height of the circuit wiring part 4 is t1 [μm] as shown in FIG. 6, the difference between T0 and t1 (Especially, t3) is not particularly limited, but is preferably 35 μm or less, and particularly preferably 10 to 30 μm. Thereby, even if the thickness of the substrate 100 is thin, the insulation reliability can be maintained.
Here, t3 is a surface 221 on the side where the fiber substrate 1 of the prepreg 10c is unevenly distributed from the surface 41 on the fiber substrate 1 side of the circuit wiring portion 4 (the upper surface in FIG. 6). Corresponds to the thickness up to the upper surface).

As shown in FIGS. 3 and 6, the thickness of the first resin layer 21 is B1 [μm], the thickness of the second resin layer 22 is B2 [μm], and the thickness of the circuit wiring portion 4 is t1. When [μm] and the remaining copper ratio are S [%] and the thickness from the upper end surface (upper side in FIG. 6) of the circuit wiring portion 4 to the fiber substrate 1 is t2 [μm], B2 <B1 It is preferable that B1 = t2 + t1 × (1−S / 100) is satisfied.
Here, although the thickness of t2 is not specifically limited, 0-15 micrometers is preferable. In addition, when there is a concern about a decrease in insulation in the circuit wiring portion 4 due to contact between the circuit wiring portion 4 and the fiber base material 1, t2 is preferably set to 3 to 15 μm. On the other hand, when the thickness of the substrate 100 is reduced, t2 is preferably 0 to 5 [mu] m, and in order to achieve both insulation and thinness, t2 is preferably 3 to 5 [mu] m. Thereby, it is excellent in the embedding property to the circuit wiring part 4 on the one surface side of the prepreg 10, and high insulation reliability can be provided.

  Further, the semiconductor device 200 can be obtained by mounting the semiconductor element 7 by connecting the bump 71 of the semiconductor element 7 and the pad portion 5 of the substrate 100 to the substrate 100 as shown in FIG. 5 (FIG. 7). . In such a semiconductor device 200, since the fiber base material 1 of each prepreg 10a to 10f constituting the substrate 100 is unevenly distributed in the thickness direction, the prepreg 10 having an optimum thickness can be used and is required. The semiconductor device 200 having the minimum thickness necessary for the characteristics to be obtained can be obtained.

5 and FIG. 7, a six-layer substrate has been described. However, the substrate of the present invention is not limited to this, and is also suitable for a three-layer, four-layer, five-layer, or seven-layer, eight-layer multilayer substrate. Can be used.
Moreover, in the board | substrate 100 of this invention, you may use together the prepreg 10 in which the fiber base materials 1 which were mentioned above are unevenly distributed in the thickness direction, and the prepreg used conventionally. Furthermore, even in the prepreg 10 that is unevenly distributed in the thickness direction of the fiber base material 1, prepregs 10 having various uneven distribution positions may be used in combination.

EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example and a comparative example, this invention is not limited to this. First, an example of a prepreg will be described.
Example 1
1. Adjustment of resin material varnish 15% by weight of novolak-type cyanate resin (manufactured by Lonza Japan, Primaset PT-30, weight average molecular weight of about 2,600) as thermosetting resin, biphenyldimethylene type epoxy resin (Nipponization) 8% by weight, NC-3000P, epoxy equivalent 275) manufactured by Yakuhin, 7% by weight of biphenyldimethylene type phenol resin (Maywa Kasei Co., Ltd., MEH-7851-S, hydroxyl equivalent 203) as a phenol resin, and epoxy as a coupling agent A silane type 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- is used as the inorganic filler. 10% (manufactured by Denki Kagaku Kogyo Co., Ltd., average particle size 0.3 μm) 20% by weight and sphere 50% by weight of a fused silica SO-32R (manufactured by Admatechs Co., Ltd., average particle size 1.5 μm) was added and stirred for 10 minutes using a high speed stirrer to prepare a resin material varnish.

2. Production of 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, and the above-mentioned resin material varnish is applied with a comma coater device, and is dried at 170 ° C. Was dried for 3 minutes, and a resin layer having a thickness of 15 μm and a width of 410 mm was formed so as to be positioned at the center in the width direction of the carrier film to obtain a carrier material 2a (finally formed the first resin layer 21). .
Further, the amount of the resin material varnish to be applied is adjusted by the same method so that the resin layer having a thickness of 8 μm and a width of 360 mm is positioned at the center in the width direction of the carrier film to form the carrier material 2b (final The second resin layer 22 was formed).

3. Production of Prepreg Using a glass woven fabric (cross type # 1015, width 360 mm, thickness 15 μm, basis weight 17 g / m ² ) as a fiber base material, a prepreg was produced by a vacuum laminating apparatus and a hot air drying apparatus shown in FIG.
Specifically, each of the glass woven fabrics is laminated so that the carrier material 2a and the carrier material 2b are positioned in the center in the width direction of the glass woven fabric, and the laminate roll at 80 ° C. under a reduced pressure condition of 750 Torr. Was used for bonding.
Here, in the inner region of the width direction dimension of the glass woven fabric, the resin layers of the carrier material 2a and the carrier material 2b are respectively bonded to both sides of the fiber cloth, and in the outer region of the width direction dimension of the glass woven fabric. The resin layers of the carrier material 2a and the carrier material 2b were joined together.
Next, the bonded material was heat-treated without applying pressure by passing it through a horizontal conveying type hot air drying device set at 120 ° C. for 2 minutes to obtain a thickness of 30 μm (first resin layer: 11 μm, A prepreg having a fiber base material of 15 μm and a second resin layer of 4 μm was obtained.

(Example 2)
The thickness of the resin layer of the carrier material 2a and the carrier material 2b was the same as that of Example 1 except that the thickness was 20 μm (carrier material 2a) and 8 μm (carrier material 2b), respectively. The thickness of the obtained prepreg was 35 μm (first resin layer: 16 μm, fiber substrate: 15 μm, second resin layer: 4 μm).

(Example 3)
Example 1 was repeated except that the fiber base material and the carrier materials 2a and 2b were as follows.
A glass woven fabric (cross type # 1037, thickness 24 μm, basis weight 24 g / m ² ) was used as a fiber base material. The thickness of the obtained prepreg was 40 μm (first resin layer: 12 μm, fiber substrate: 24 μm, second resin layer: 4 μm). The thicknesses of the resin layers of the carrier material 2a and the carrier material 2b were 20 μm (carrier material 2a) and 11 μm (carrier material 2b), respectively.

( Reference example )
Example 1 was repeated except that the following resin varnish was used.
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. The thickness of the obtained prepreg was 35 μm (first resin layer: 16 μm, fiber substrate: 15 μm, second resin layer: 4 μm).

(Example 5)
Example 2 was the same as Example 1 except that the carrier materials 2a and 2b were changed as follows.
The thicknesses of the resin layers on the carrier material 2a and the carrier material 2b were 25 μm (carrier material 2a) and 8 μm (carrier material 2b), respectively. The thickness of the obtained prepreg was 40 μm (first resin layer: 21 μm, fiber substrate: 15 μm, second resin layer: 4 μm).

(Comparative Example 1)
Example 1 was repeated except that the fiber base material and the carrier materials 2a and 2b were as follows.
A glass woven fabric (cross type # 1080, thickness 55 μm, basis weight 47 g / m ² ) was used as the fiber base material. The thicknesses of the resin layers of the carrier material 2a and the carrier material 2b were 25 μm (carrier material 2a) and 25 μm (carrier material 2b), respectively.
The thickness of the obtained prepreg was 75 μm (first resin layer: 10 μm, fiber substrate: 55 μm, second resin layer: 10 μm).

(Comparative Example 2)
The carrier materials 2a and 2b and the fiber base material were the same as in Example 1 except that a glass woven fabric (cross type # 1037, thickness 24 μm, basis weight 24 g / m ² ) was used as follows. The thicknesses of the resin layers of the carrier material 2a and the carrier material 2b were 16 μm (carrier material 2a) and 16 μm (carrier material 2b), respectively. The thickness of the obtained prepreg was 40 μm (first resin layer: 8 μm, fiber substrate: 24 μm, second resin layer: 8 μm).

The following evaluation was performed about the prepreg obtained by each Example , the reference example, and each comparative example . The evaluation contents are shown together with the items. The obtained results are shown in Table 1.
1. Ratio between the thickness of the first resin layer and the thickness of the second resin layer The thickness of each layer was measured from the cross section of the obtained prepreg.

2. Coefficient of thermal expansion in the plane direction of the prepreg The coefficient of thermal expansion in the plane direction of the prepreg was measured by raising the temperature at 10 ° C./min using a TMA apparatus (manufactured by TA Instruments).

3. Elastic modulus of prepreg The elastic modulus of the obtained prepreg was measured using a resonance frequency shift mode of DMA (DMA 983, manufactured by TA Instruments) at a temperature rising rate of 5 ° C./min.

As is clear from Table 1, in the prepregs of Examples 1 to 3 , and 5 , the thicknesses of the first resin layer and the second resin layer were different, and the fiber base material was unevenly distributed. Therefore, it was shown that the resin layer of the prepreg can be formed according to the circuit wiring pattern (remaining copper ratio, circuit height) and the like.
Moreover, the prepregs of Examples 1 to 3 , 5 had a small coefficient of thermal expansion and a high elastic modulus. Thereby, it is expected that the connection reliability of the substrate after forming the substrate is excellent.

Next, examples , reference examples, and comparative examples of the substrate (multilayer substrate) and the semiconductor device will be described.
(Examples 1A to 3A, 5A, Reference Example A )
A prepreg obtained in each example and reference example is stacked on a core substrate having a comb-shaped pattern with a conductor spacing of 50 μm on the surface, a circuit thickness of 18 μm and a residual copper ratio of 50%, and a copper foil is further stacked on the outermost layer. Then, heating and pressure molding (3 MPa, 200 ° C., 90 minutes) were performed to obtain a multilayer substrate. Then, after forming a circuit on the outermost copper foil (thickness 12 μm), a semiconductor element was mounted to obtain a semiconductor device.

(Comparative Example 1A and Comparative Example 2A)
The same procedure as in Example 1A was performed except that the prepregs obtained in Comparative Examples 1 and 2 were used.

The multilayer substrate obtained in each example , reference example and each comparative example was evaluated as follows. The evaluation contents are shown together with the evaluation items. The obtained results are shown in Table 2.
1. Substrate thickness The thickness of the obtained substrate 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, and an insulation resistance of 1 × 10 ⁹ Ω or higher was regarded as acceptable.

3. Embeddability The cross section of the 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 is a part of the circuit wiring contact with the glass woven fabric, but there is no practical problem.
Δ: There is a part of the circuit wiring contact with the glass woven fabric, impractical.
X: The resin layer is not sufficiently embedded, and there are voids and the like.

As apparent from Table 2, the thicknesses of the multilayer substrates of Examples 1A to 3A and 5A were 200 μm or less, indicating that a thin multilayer substrate was obtained.
In addition, the multilayer substrates of Examples 1A to 3A and 5A were excellent in insulation reliability and embeddability.
Moreover, it was confirmed that the semiconductor devices of Examples 1A to 3A and 5A operate normally.

DESCRIPTION OF SYMBOLS 1 Fiber base material 2 Resin material 2a, 2b Carrier material 21 1st resin layer 22 2nd resin layer 221 The surface by which the fiber base material is unevenly distributed 3 Core substrate 4 Circuit wiring part 41 The fiber base material side of a circuit wiring part Surface 5 Pad portion 6 Filled via portion 7 Semiconductor element 71 Bump 8 Vacuum laminating device 81 Laminating roll 9 Hot air drying device 10 Prepreg 10a Prepreg 10b Prepreg 10c Prepreg 10d Prepreg 10e Prepreg 10f Prepreg 100 Substrate 200 Semiconductor device

Claims (6)

A fiber base composed of glass fibers, a first resin layer located on one side of the fiber base, and a second resin layer located on the other side of the fiber base,
When 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, and the thickness of the second resin layer is B2, 0 <B2 / B1 ≦ 0.4 satisfied,
The resin composition constituting the first resin layer and the resin composition constituting the second resin layer are at least one selected from a cyanate resin, an epoxy resin, and a phenol resin, respectively, and the same thermosetting resin And an inorganic filler,
The inorganic filler is particles having an average particle diameter of 0.01 to 5.0 μm,
The content of the inorganic filler is 40 to 80% by weight of the entire resin composition,
A prepreg characterized by having a coefficient of thermal expansion in the plane direction of the prepreg of 10 ppm or less.   The prepreg according to claim 1, wherein a circuit wiring portion is embedded in the first resin layer. When the total thickness of the prepreg is T0 [μm] and the thickness of the circuit wiring portion is t1 [μm],
The prepreg according to claim 2, satisfying a relationship of T0−t1 ≦ 35 μm.   4. The prepreg according to claim 2, wherein t <b> 2 is 0 to 15 μm when a distance between the circuit wiring portion and the fiber base material is t <b> 2 [μm]. A substrate formed by laminating a plurality of prepregs,
5. The substrate according to claim 1, wherein at least one of the plurality of prepregs is the prepreg according to claim 1.   A semiconductor device comprising a semiconductor element mounted on the substrate according to claim 5.

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