JPH09255798A - Copper-foil-clad prepreg for printed wiring board and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copper-foil-clad prepreg excellent in rigidity, dimensional stability and reliability of connection without using any glass cloth by using a non-film-forming thermosetting resin used in prepregs containing glass cloth bases and to provide a process for producing the same. SOLUTION: This invention provides a copper-foil-clad prepreg which comprises a copper foil at least either of the surfaces of which is roughened and a prepreg layer formed thereon and in which the prepreg layer is made from a non-film-forming thermosetting resin having electrical insulation short fibers, and the resin is in a tack-free state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a prepreg with a copper foil for a printed wiring board used in electronic equipment and the like and a method for manufacturing the same.

[0002]

2. Description of the Related Art A multilayer printed wiring board used in electronic equipment is a wiring board having an electric circuit in its inner layer.
This multilayer printed wiring board is a circuit formed on the outer layer of an inner layer circuit-containing multilayer copper clad laminate obtained by thermocompressing an inner layer circuit board on which a circuit is formed in advance and an outer layer circuit copper foil with a prepreg interposed therebetween. Obtained by forming. In this prepreg,
BACKGROUND ART Conventionally, a glass cloth-based epoxy resin prepreg in which a solvent is removed and a resin is semi-cured by impregnating a glass cloth with a thermosetting resin varnish, for example, an epoxy resin varnish and heating and drying it is used. In recent years, along with the demand for smaller and lighter electronic devices, the demand for thinner multilayer printed wiring boards and surface smoothing for forming fine wiring has been increasing year by year. Currently, in thin multilayer printed wiring boards,
The thickness of the interlayer insulating layer is 30 to 100 μm. However, when a thin multilayer printed wiring board is manufactured using such a thin glass cloth base material epoxy resin prepreg,
A short circuit between circuits due to migration of copper ions is likely to occur. Copper ions have been found to tend to migrate along the fibers of glass cloth. Therefore, when glass cloth is used as the base material, the occurrence of short circuit between circuits due to migration of copper ions is unavoidable to some extent.In addition, such a thin glass cloth base material epoxy resin prepreg is used. When a thin multi-layer printed wiring board is manufactured, the cross stitches are easily raised, and the unevenness of the inner layer circuit board cannot be absorbed inside the prepreg, and the unevenness is likely to appear on the outer layer surface, so the surface smoothness is impaired and fine wiring is formed. Has become an obstacle. Therefore, instead of using the conventional glass cloth-based epoxy resin prepreg,
A method of using an adhesive film or the like that does not contain glass cloth as a prepreg is practiced. As a method of using these prepregs that do not use glass cloth, as in the prior art, a method of sandwiching a prepreg that does not use glass cloth between an inner layer circuit board and a copper foil for outer layer circuits and performing thermocompression molding (Japanese Patent Application Laid-Open No. H06-69242). -200216), a prepreg with a copper foil in which a prepreg layer not using glass cloth is previously formed on one surface of the copper foil for an outer layer circuit, and an inner circuit board are laminated so that the prepreg layer is in contact with the inner layer circuit and heat is applied. A pressure molding method (Japanese Patent Laid-Open No. 6-242465) is used. A resin having film forming ability is used for the prepreg and the prepreg with a copper foil that do not use the glass cloth. The film-forming ability is less likely to cause problems such as resin cracking or chipping in the steps of conveying, cutting, and laminating the prepreg, and the interlayer insulating layer during thermocompression molding when used as an insulating material for interlayer connection of a multilayer board. Means that the troubles such as abnormal thinning in the inner layer circuit existing portion, decrease in interlayer insulation resistance, and short circuit are unlikely to occur. For example, U.S. Pat. No. 4,543,295 discloses a thermoplastic polyimide adhesive film.
-120135 discloses an average molecular weight of 70,000.
The use of the above high molecular weight epoxy resin is disclosed,
Japanese Unexamined Patent Publication No. 6-200216 discloses a prepreg in which a silicone unit is introduced into a polyimide resin having a high film-forming ability, and is disclosed in Japanese Patent Laying-Open Nos. 4-29393, 4-36366, and 4-41581. The official gazette discloses the use of acrylonitrile butadiene rubber / phenol resin, phenol resin / butyral resin, and acrylonitrile butadiene rubber / epoxy resin as the resin.

[0003]

The above-mentioned conventional techniques have the following problems. That is, USP
The thermoplastic polyimide adhesive film disclosed in Japanese Patent No. 4,543,295 has a heating temperature of 250 as compared with a heating temperature of 170 ° C. which is generally used in a printed wiring board manufacturing process.
As high as ℃, special molding equipment that is not widely used must be used. The resins disclosed in JP-A-4-120135 and JP-A-6-200216 have limited dilutable solvents, and must be solvents with a high boiling point. The efficiency of solvent removal by subsequent drying is low, and when the solvent remains, the characteristics of the printed wiring board may be impaired. In addition, the insulating layer made of these prepregs has a Tg of around 130 ° C., which is insufficient for applications requiring high heat resistance.
In addition, JP-A-4-29393 and JP-A-4-363.
The insulating materials using a resin disclosed in Japanese Patent No. 66 and Japanese Patent Application Laid-Open No. 4-41581 have poor heat resistance and chemical resistance, and when used as a printed wiring board, they have poor heat resistance and electrical insulation. As described above, the conventional prepreg that does not use glass cloth is limited in the resin that can be used to the above-mentioned resin having the film forming ability, and the characteristics of the resin are the same as those used in the conventional glass cloth-based epoxy resin prepreg. In general, they are inferior in heat resistance, moldability, adhesiveness, etc. to the properties of the resins used. Furthermore, since the multilayer printed wiring boards made using these prepregs do not have reinforcing fibers such as glass cloth, comparison with printed wiring boards made using conventional glass cloth base epoxy resin prepregs Then, the rigidity is low, the dimensional stability in the manufacturing process is low, and the coefficient of thermal expansion is extremely large when compared to a conductor circuit or electronic components to be mounted when it is used as a printed wiring board. Part breakage easily occurs.

As described above, in the conventional prepreg for a printed wiring board and a prepreg with a copper foil which do not use glass cloth, only a special resin capable of forming a film can be used, and rigidity, dimensional stability, and connection with mounted components can be achieved. There is a problem to be solved due to low reliability, and it is in a situation where it is not possible to meet the increasing demand for printed wiring boards.
The present invention is a prepreg with a copper foil that does not use a glass cloth, the resin is not a special resin having a film-forming ability as described above, but is used in a conventional glass cloth base material prepreg. A general-purpose resin used for printed wiring boards that solves the problems of low rigidity, dimensional stability, and low connection reliability that occur with conventional prepregs with copper foil that do not use glass cloth. An object of the present invention is to provide a prepreg with a copper foil and a method for producing the same.

[0005]

A prepreg with a copper foil for a printed wiring board according to the present invention comprises a copper foil having at least one surface roughened and a prepreg layer formed on the roughened surface. However, it is characterized in that electrically insulating short fibers are dispersed in a thermosetting resin which alone has no film-forming ability, and the resin is in a semi-cured state. In such a prepreg with a copper foil for a printed wiring board, a thermosetting resin having no film forming ability by itself is mixed with electrically insulating short fibers, and the short fibers are uniformly mixed in the thermosetting resin by stirring. It can be manufactured by coating the roughened surface of a copper foil having at least one surface roughened, and then heating the thermosetting resin to a semi-cured state. At this time, the electrically insulating short fibers are glass,
Alumina fiber is preferable, and its content is preferably 5 to 50% by volume based on the solid content of the thermosetting resin. That is, the present inventors, as a result of earnest study,
As in the above-mentioned conventional technique, by dispersing electrically insulating short fibers in a general-purpose thermosetting resin without using a special resin capable of forming a film, a film is formed on the prepreg layer of the prepreg with a copper foil. The present invention has been made on the basis of the finding that it has a forming ability.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Electrically insulating short fibers used in the present invention include short glass fibers such as E glass, S glass, Q glass and D glass, aramid fibers, ultra high molecular weight polyethylene fibers, polyarylate fibers, and polyarylate fibers. -P-oxybenzoyl whiskers, poly-2-oxy-6-naphthol whiskers, high elasticity organic short fibers such as polyoxymethylene whiskers, alumina fibers, magnesia fibers, silica fibers,
Inorganic short fibers such as zirconia fibers can be used. Among these, glass such as E glass short fiber and S glass short fiber, aramid short fiber, and alumina short fiber are preferable. In particular, glass and alumina fibers are preferable because they are excellent in versatility and addition effect. If the average diameter of the electrically insulating short fibers is small, it will be difficult to mix it with the resin varnish and the coating workability will decrease, and if it is large, the surface smoothness will be adversely affected and microscopic observation of the electrically insulating short fibers will occur. It is preferably 0.1 μm or more and 15 μm or less because the uniform uniform dispersibility is impaired. Further, if it is 0.5 μm or more and 3 μm or less, the coatability is good (smooth coating is easy), which is more preferable.

The average length of electrically insulating short fibers is
It is preferably 5 times or more, and more preferably about 10 times or more of the average diameter, because sufficient rigidity can be obtained when a wiring board is obtained due to the reinforcing effect as fibers. And, if the electrically insulating short fibers are too long, it becomes difficult to uniformly disperse them in the varnish and the coatability decreases, so that the dispersibility and the coatability of the electrically insulating short fibers are kept good. The length is preferably 100 times or less the average diameter. In the present invention, since such a short fiber is used, the occurrence of an inter-circuit short circuit accident due to migration of copper ions, which is a problem in the conventional glass cloth base epoxy resin using long glass fibers, It can be prevented like a prepreg with a copper foil that does not use glass cloth. It is also effective to use electrically insulating short fibers surface-treated with a silane coupling agent in order to further increase the rigidity and heat resistance of the multilayer printed wiring board. The electrically insulating short fibers surface-treated with a coupling agent have excellent wettability and bondability with a resin and can improve rigidity and heat resistance. As the coupling agent, known ones such as silicon type, titanium type, aluminum type, zirconium type, zirco aluminum type, chromium type, boron type, phosphorus type and amino acid type can be used.

The resin used in the present invention is a resin which does not have a film forming ability by itself. The film-forming ability is easy to control to a predetermined thickness when applying the resin varnish to the carrier film, and after transporting after drying by heating to a semi-cured state, in the steps such as cutting and laminating,
Trouble such as resin cracking or chipping is unlikely to occur, and the interlayer insulating layer becomes abnormally thin in the inner layer circuit existing part during thermocompression molding when used as an insulating material for interlayer connection of multilayer boards, and the interlayer insulating resistance decreases. It means the performance that does not easily cause trouble such as short circuit. Further, the resin having no film-forming ability often has a low molecular weight which does not exceed 30,000. Specifically, it is preferable to use the thermosetting resin used in the conventional glass cloth-based prepreg. The resin referred to herein means a resin, a curing agent, a curing accelerator, and, if necessary, a coupling agent and a diluent. As the type of resin, for example, epoxy resin, bismaleimide triazine resin, polyimide resin, phenol resin, melamine resin, silicon resin, unsaturated polyester resin, cyanate ester resin, isocyanate resin, polyimide resin or various modified resins thereof. Is preferred. Among them, in terms of printed wiring board characteristics,
In particular, bismaleimide triazine resin, polyimide resin,
Epoxy resins are preferred. For example, as the epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A novolac type epoxy resin, salicylaldehyde novolac type epoxy resin , Bisphenol F novolac type epoxy resin, alicyclic epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, hydantoin type epoxy resin, isocyanurate type epoxy resin,
Aliphatic cyclic epoxy resins and their halides, hydrogenates, and mixtures of said resins are preferred. Among them, bisphenol novolac type epoxy resin or salicylaldehyde novolac type epoxy resin is preferable because it has excellent heat resistance.

As a curing agent for such a resin, a conventionally used one can be used. When the resin is an epoxy resin, for example, dicyandiamide, bisphenol A, bisphenol F, polyvinylphenol, phenol novolac resin, bisphenol A novolac resin can be used. Also, halides and hydrides of these phenolic resins can be used. Among them, bisphenol A novolac resin is preferable because it has excellent heat resistance. The ratio of the curing agent to the resin may be a conventionally used ratio, and is preferably in the range of 2 to 100 parts by weight with respect to 100 parts by weight of the resin. Further, in the case of dicyandiamide, 2 to 5 parts by weight, For other curing agents, the range is preferably 30 to 80 parts by weight.

As the curing accelerator, when the resin is an epoxy resin, an imidazole compound, an organic phosphorus compound, a tertiary amine, a quaternary ammonium salt or the like is used. The ratio of the curing accelerator to the resin may be a conventionally used ratio, and is 0.01 to 20 relative to 100 parts by weight of the resin.
The range of parts by weight is preferable, and the range of 0.1 to 1.0 parts by weight is more preferable.

As the diluent used in the thermosetting resin of the present invention, conventionally used solvents can be used. As the type of solvent, acetone, methyl ethyl ketone, toluene, xylene, methyl isobutyl ketone, ethyl acetate,
Ethylene glycol monomethyl ether, methanol,
Ethanol, N, N-dimethylformamide, N, N-
Dimethylacetamide and the like can be used. Reactive diluents such as phenyl glycidyl ether, glycidyl methacrylate, butyl glycidyl ether, styrene oxide, methyl glycidyl ether and ethyl glycidyl ether can be used. The ratio of the diluent to the resin may be a conventionally used ratio and is preferably in the range of 1 to 200 parts by weight with respect to 100 parts by weight of the resin.
The range of 0 to 100 parts by weight is more preferable.

Further, in the present invention, in addition to the above-mentioned components, a conventionally known coupling agent, filler, etc. may be appropriately blended in the resin.

If the fraction of the short fibers in the prepreg layer of the copper foil prepreg for a printed wiring board of the present invention is too small, the prepreg with a copper foil tends to be shattered by the resin when it is cut. In addition, the multi-layer printed wiring board made of this resin does not have sufficient rigidity, and if it is too large, the hole filling properties of the inner layer circuit and the resin filling property between circuits during thermocompression molding are impaired. However, since voids and scratches are likely to occur in the insulating layer after thermocompression molding and the wiring board characteristics may be impaired, the solid content of the thermosetting resin is 5%.
It is preferably about 50% by volume. Furthermore, it is excellent in filling holes in the inner layer circuit and resin filling between circuits, and
Compared with a wiring board manufactured using a prepreg using a conventional glass cloth, the manufactured wiring board maintains the same or higher rigidity, dimensional stability, and wire bonding property, and thus the short fiber in the prepreg layer is used. Fraction is 20-40
It is more preferable to be vol%.

In the present invention, the copper foil to be formed with the thermosetting resin layer containing the electrically insulating short fibers, which is the prepreg layer, on one surface of the roughened copper foil has at least one roughened surface. Electrolytic copper foil, rolled copper foil, and ultra-thin copper foil with carrier film, which have been conventionally used for printed wiring boards, are used. By forming a thermosetting resin layer containing electrically insulating short fibers on a smooth copper foil surface, thermosetting resin containing copper foil and electrically insulating short fibers when in a prepreg state or in a multilayer printed wiring board It is not possible to secure sufficient adhesiveness with the functional resin layer. Therefore, in the present invention, a thermosetting resin layer containing electrically insulating short fibers is formed on the roughened surface of the copper foil. As a result, when the prepreg with a copper foil and the multilayer printed wiring board using the prepreg are used, sufficient adhesion between the copper foil and the thermosetting resin layer containing electrically insulating short fibers can be ensured. The thickness of the copper foil is preferably thin, preferably 30 μm or less, because a fine circuit can be formed. More preferably, an ultra-thin copper foil having a thickness of 10 μm or less is preferable. In this case, however, it is difficult to handle alone, and thus a copper foil with a carrier film is preferable.

The electrically insulating short fibers in the prepreg layer of the prepreg with a copper foil of the present invention are in a state close to a two-dimensional orientation (the axial direction of the electrically insulating short fibers is almost parallel to the surface formed by the prepreg layer). (State) is preferable.

When coating a resin varnish containing electrically insulating short fibers on a copper foil, a surface parallel to the copper foil such as a blade coater, a rod coater, a knife coater, a squeeze coater, a reverse roll coater or a transfer roll coater. A coating method that can apply a shearing force in a direction or a compressing force in a direction perpendicular to the surface of the copper foil can be adopted. Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto.

[0017]

【Example】

(Example 1) 100 parts by weight of bisphenol A novolac type epoxy resin 60 parts by weight of bisphenol A novolac resin 0.5 parts by weight of 2-ethyl-4-methylimidazole 100 parts by weight of methyl ethyl ketone No film forming ability E-glass short fibers having an average diameter of 6 μm and an average fiber length of 100 μm were mixed with the epoxy resin so as to be 30% by volume with respect to 100 parts by weight of the resin solid content, and stirred until the short fibers were uniformly dispersed in the varnish. This is coated on a roughened surface of an electrolytic copper foil having a thickness of 18 μm with a knife coater, and is dried by heating at a temperature of 150 ° C. for 10 minutes to remove the solvent and make the resin semi-cured.
A prepreg with a copper foil for a printed wiring board having a prepreg layer made of a short fiber having a short fiber volume fraction of 30% and a thickness of 60 μm and a semi-cured epoxy resin was produced. The prepared prepreg with a copper foil was in a state with almost no warp, and could be cut cleanly with a cutter knife and a shear without scattering of resin and had good handleability.

(Example 2) 100 parts by weight of bisphenol A novolac type epoxy resin 55 parts by weight of bisphenol A novolac resin 0.5 parts by weight of 2-ethyl-4-methylimidazole 100 parts by weight of methyl ethyl ketone An aramid short fiber having an average diameter of 12 μm and an average fiber length of 150 μm was blended in an epoxy resin not having 30% by volume with respect to 100 parts by weight of a resin solid content and stirred until the short fibers were uniformly dispersed in the varnish. . This is coated on a roughened surface of an electrolytic copper foil having a thickness of 18 μm with a knife coater, and is dried by heating at a temperature of 150 ° C. for 10 minutes to remove the solvent and make the resin semi-cured.
A prepreg with a copper foil for a printed wiring board having a prepreg layer made of short fibers having a volume fraction of short fibers of 30% and a thickness of 60 μm and an epoxy resin in a semi-cured state was produced. The prepared prepreg with a copper foil was in a state with almost no warp, and could be cut cleanly with a cutter knife and a shear without scattering of resin and had good handleability.

(Example 3) 100 parts by weight of bisphenol A novolac type epoxy resin 60 parts by weight of bisphenol A novolac resin 0.5 parts by weight of 2-ethyl-4-methylimidazole 100 parts by weight of methyl ethyl ketone A short fiber of alumina having an average diameter of 3 μm and an average fiber length of 50 μm is mixed with a non-containing epoxy resin so as to be 30% by volume with respect to 100 parts by weight of the resin solid content, and stirred until the short fibers are uniformly dispersed in the varnish. did. This is coated on a roughened surface of an electrolytic copper foil having a thickness of 18 μm with a knife coater, and dried by heating at a temperature of 150 ° C. for 10 minutes to remove the solvent and to make the resin semi-cured state. A prepreg with a copper foil for a printed wiring board having a prepreg layer composed of a short fiber having a rate of 30% and a thickness of 60 μm and an epoxy resin in a semi-cured state was prepared.
The prepared prepreg with a copper foil had almost no warp, and could be cut cleanly with a cutter knife and a shear without scattering of resin and had good handleability.

(Example 4) 100 parts by weight of salicylaldehyde novolak type epoxy resin 70 parts by weight of bisphenol A novolac resin 1 part by weight of N-methylimidazole 100 parts by weight of methyl ethyl ketone An average diameter of 1 μm in a thermosetting resin, Average fiber length 3
E glass short fibers of 0 μm were mixed so that the short fibers would be 30% by volume with respect to 100 parts by weight of the resin solid content, and the mixture was stirred until the short fibers were uniformly dispersed in the varnish. This, thickness 1
Coat the roughened surface of 8μm electrolytic copper foil with a knife coater,
It is heated and dried at a temperature of 150 ° C. for 10 minutes to remove the solvent and make the resin in a semi-cured state.
A prepreg with a copper foil for a printed wiring board having a prepreg layer made of a short fiber having a thickness of 0% and a thickness of 60 μm and an epoxy resin in a semi-cured state was prepared. The prepared prepreg with a copper foil had almost no warpage, and could be cut cleanly with a cutter knife without scattering of resin and had good handleability.

(Embodiment 5) The thickness of the insulating layer is 0.1 mm,
Copper foil for a conductor A prepreg with a copper foil for a printed wiring board of Example 1 was formed on both surfaces of an inner layer circuit board prepared by etching away unnecessary portions of the copper foil on both surfaces of a double-sided copper clad laminate having a thickness of 18 μm. The prepreg surface was laminated so as to face the inner layer circuit, and thermocompression molding was performed at a temperature of 170 ° C. and a pressure of 2 MPa for 60 minutes to produce a multilayer copper clad laminate with an inner layer circuit. The outer layer of the copper clad laminate containing the inner layer circuit was etched and the outer layer was etched, and the appearance was observed.There were no defects such as voids or scratches, and this prepreg with copper foil provided good circuit filling and hole filling properties. I confirmed that I had it. Further, the surface roughness of the multilayer copper clad laminate containing the inner layer circuit was measured with a stylus surface roughness meter. The measurement location was the outer layer surface on a straight line having a length of 25 mm including a portion with and without an inner layer circuit immediately below. The 10-point average roughness (Rz) of the step between the portion with the inner layer circuit and the portion without the inner layer circuit was 3 μm or less, which was good surface smoothness that did not hinder circuit processing. A part of the multilayer printed wiring board from which the outer layer copper foil was removed was cut out, and its thermal expansion coefficient and bending elastic modulus were measured. Thermal expansion coefficient is TMA
The flexural modulus was measured by a (thermomechanical analyzer) in a bending mode of DMA (dynamic thermomechanical analyzer).
The average thermal expansion coefficient in the surface direction (vertical direction) is 16 pp
m / ° C. (at room temperature), the average flexural modulus in the plane direction (vertical direction) is 20 GPa at room temperature and at high temperature (200
It was 12 GPa at (° C.). The surface hardness measured by a Vickers hardness meter was 35.

(Example 6) A multilayer copper clad laminate containing an inner layer circuit was prepared in the same manner as in Example 5, except that the prepreg with a copper foil of Example 1 was used in place of the prepreg with a copper foil of Example 1. It was produced and evaluated by the same method. The coefficient of thermal expansion of the multilayer printed wiring board after removing the outer copper foil is 10 p
pm / ° C. (at room temperature), the average flexural modulus in the plane direction (vertical direction) is 25 GPa at room temperature and at high temperature (200
It was 15 GPa at (° C.). The surface hardness measured by a Vickers hardness meter was 30. Other characteristics were the same as in Example 5.

(Embodiment 7) A multilayer copper clad laminate containing an inner layer circuit was prepared in the same manner as in Embodiment 5 except that the prepreg with a copper foil of Example 1 was used in place of the prepreg with a copper foil of Example 1. It was produced and evaluated by the same method. The coefficient of thermal expansion of the multilayer printed wiring board after removing the outer layer copper foil is 12 p.
pm / ° C. (at room temperature), the average bending elastic modulus in the plane direction (vertical direction) is 23 GPa at room temperature, and at high temperature (200
It was 16 GPa at (° C.). The surface hardness measured by a Vickers hardness meter was 37. Other characteristics were the same as in Example 5.

(Example 8) A 10-layer printed wiring board was produced in exactly the same manner as in Example 5 except that the prepreg with a copper foil of Example 1 was used in place of the prepreg with a copper foil of Example 1. . The average flexural modulus in the plane direction (vertical direction) of this multilayer printed wiring board is 20 GPa at room temperature,
It was 16 GPa at high temperature (200 ° C.). The surface hardness measured by a Vickers hardness meter was 35. Other characteristics were the same as in Example 5. Next, comparative examples for confirming the effects of these examples will be described.

(Embodiment 9) The epoxy resin having no film forming ability used in the embodiment 1 contains 8% by volume of E glass short fibers having an average diameter of 6 μm and an average fiber length of 100 μm with respect to 100 parts by weight of the resin solid content. The mixture was mixed as above and stirred until the short fibers were uniformly dispersed in the varnish. This is the thickness 18
It is coated with a knife coater on the roughened surface of the electrolytic copper foil of μm, and is dried by heating at a temperature of 150 ° C. for 10 minutes to remove the solvent and make the resin semi-cured, and the short fiber volume fraction is 8%. A prepreg with a copper foil for a printed wiring board having a prepreg layer composed of a short fiber having a thickness of 60 μm and an epoxy resin in a semi-cured state was produced. The prepared prepreg with a copper foil had a slight curl on the copper foil surface, but was easy to handle. Further, when cutting with a cutter knife, the resin in the vicinity of the cut portion was somewhat cracked and scattered, but it was sufficiently durable to be used as a material for a multilayer printed wiring board.

(Embodiment 10) E-glass short fibers having an average diameter of 6 μm and an average fiber length of 100 μm were added to the epoxy resin having no film-forming ability used in Example 1 to obtain a resin solid content of 100.
It was mixed so as to be 45% by volume with respect to parts by weight, and stirred so that the short fibers were uniformly dispersed in the varnish. This is coated on a roughened surface of an electrolytic copper foil having a thickness of 18 μm with a knife coater, and dried by heating at a temperature of 150 ° C. for 10 minutes to remove the solvent and to make the resin semi-cured state. A prepreg with a copper foil for a printed wiring board having a prepreg layer composed of a short fiber having a rate of 45% and a thickness of 60 μm and an epoxy resin in a semi-cured state was prepared. The prepared prepreg with a copper foil was in a state with almost no warp, and could be cut cleanly with a cutter knife and a shear without scattering of resin and had good handleability. A multilayer copper clad laminate containing an inner layer circuit was produced in exactly the same manner as in Example 5 except that this prepreg with a copper foil was used. When the cross section of the multilayer printed wiring board from which the outer layer copper foil was removed was observed, no void was found near the inner layer circuit, which was good.

(Comparative Example 1) The epoxy resin having no film forming ability used in Example 1 was coated on a roughened surface of an electrolytic copper foil having a thickness of 18 μm with a knife coater without using glass short fibers, and the temperature was changed. Dry at 150 ° C for 10 minutes to remove the solvent and leave the resin in a semi-cured state.
A prepreg with a copper foil having a m prepreg layer was produced. The produced prepreg with a copper foil has a curl with a convex copper foil surface, and when cutting with a cutter knife,
The resin in the vicinity of the cut portion was cracked and scattered violently, so that it could not be used as a material for a multilayer printed wiring board.

(Comparative Example 2) Brominated high molecular weight epoxy polymer having a weight average molecular weight of 500,000 synthesized from tetrabromobisphenol A and bisphenol A diglycidyl ether in dimethylacetamide. 100 parts by weight ・ Tolylene diisocyanate blocked with phenol novolac 20 parts by weight ・ Bisphenol A type epoxy resin ‥‥‥‥‥‥‥‥‥ 30 parts by weight ・ Phenol novolac equivalent to bisphenol A type epoxy resin ・ Urea silane coupling Agent: 0.5 parts by weight of solvent dimethylacetamide used in the synthesis of high molecular weight epoxy polymer and a film-forming ability of resin solid content of 40% by weight dissolved in cyclohexanone in the same amount as the solvent dimethylacetamide. A thermosetting resin having a thickness of 18
The roughened surface of the electrolytic copper foil of μm is coated with a knife coater and heated and dried at a temperature of 150 ° C. for 10 minutes to remove the solvent and semi-harden the resin, and the short fibers with a thickness of 60 μm and semi-cured. A prepreg with a copper foil having a prepreg layer made of a cured epoxy resin was prepared. The prepared prepreg with a copper foil had almost no warpage, and could be cut cleanly with a cutter knife and a shear without scattering of resin and had good handleability.

(Comparative Example 3) A multilayer copper clad laminate with an inner layer circuit was prepared in the same manner as in Example 5, except that the prepreg with a copper foil of Comparative Example 3 was used in place of the prepreg with a copper foil of Example 1. It was produced and evaluated by the same method. The coefficient of thermal expansion of the multilayer printed wiring board after removing the outer copper foil is 30 p
pm / ° C. (at room temperature), the average bending elastic modulus in the plane direction (vertical direction) is 8 GPa at room temperature and at high temperature (200
It was 3 GPa at (° C.). The surface hardness measured by a Vickers hardness tester was 18. Other characteristics were the same as in Example 5.

In summary, the first embodiment according to the present invention will be described.
4 and the prepregs with a copper foil for printed wiring boards of Examples 9 and 10 caused deterioration of handleability as shown in Comparative Example 1 even though a resin having no film forming ability was used. Without having to do so, due to the effect of blending the electrically insulating short fibers, it has a good handling property equivalent to that of the prepreg with a copper foil using the resin having the conventional film forming ability shown in Comparative Example 4. Furthermore, the multilayer copper clad laminates with inner layer circuits of Examples 5 to 8 using the prepreg with a copper foil for printed wiring boards of Examples 1 to 4 according to the present invention,
It has higher rigidity, lower thermal expansion coefficient, and higher surface hardness than the multilayer copper clad laminate with an inner layer circuit of Comparative Example 3 using the conventional prepreg with a copper foil of Comparative Example 2.

[0031]

INDUSTRIAL APPLICABILITY The prepreg with a copper foil of the present invention does not use a resin having a special film-forming ability, but can use a general-purpose resin having no film-forming ability, and still has good handleability. It is a thing. Moreover, the multilayer printed wiring board using this has higher rigidity and higher mounting reliability than the conventional multilayer printed wiring board using the prepreg with copper foil, and the high surface hardness provides good wire bondability and thermal expansion. Good dimensional stability due to small coefficient. Therefore, the prepreg with a copper foil for a printed wiring board according to the present invention greatly contributes to thinning, high density, high productivity, high reliability, and low cost of a multilayer printed wiring board.

Claims (8)

[Claims] 1. A copper foil having at least one surface roughened and a prepreg layer formed on the roughened surface. The prepreg layer alone has an electrically insulating property in a thermosetting resin having no film forming ability. The prepreg with a copper foil for a printed wiring board, characterized in that the short fibers of (1) are dispersed and the resin is in a semi-cured state. 2. The prepreg with a copper foil for a printed wiring board according to claim 1, wherein the electrically insulating short fiber is glass. 3. The prepreg with a copper foil for a printed wiring board according to claim 1, wherein the electrically insulating short fibers are alumina fibers. 4. The blending ratio of the short fibers in the prepreg layer is 5 to 5.
The prepreg with a copper foil for a printed wiring board according to claim 1, wherein the prepreg is 50% by volume. 5. A thermosetting resin which alone has no film forming ability, is mixed with electrically insulating short fibers, and the short fibers are uniformly dispersed in the thermosetting resin by stirring, and then at least one surface is roughened. A method for producing a prepreg with a copper foil for a printed wiring board, which comprises applying the heat-curable resin to a semi-cured state by applying it to a roughened surface of a copper foil which has been made into a solid. 6. The method for producing a prepreg with a copper foil for a printed wiring board according to claim 5, wherein the electrically insulating short fiber is glass. 7. The method for producing a prepreg with a copper foil for a printed wiring board according to claim 5, wherein the electrically insulating short fibers are alumina fibers. 8. The blending ratio of the short fibers in the prepreg layer is 5 to 5.
It is 50 volume%, The manufacturing method of the prepreg with a copper foil for printed wiring boards of Claim 5 characterized by the above-mentioned.