JP4090905B2 - Manufacturing method of composite substrate - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a composite substrate having excellent surface smoothness.
[0002]
[Prior art]
In order to obtain a plastic substrate (laminate) usually used in a display device, one or a plurality of prepregs impregnated with a semi-cured resin is thermoformed to form a laminate having only a resin layer, or copper By heat forming together with a metal plate such as a foil, a laminated plate composed of a metal layer and a resin layer is formed, and then the metal plate is peeled off by an etching process or the like. Usually, a prepreg is impregnated with a fiber cloth such as glass cloth, then scrapes excess resin with a roll such as a squeeze roll and dried in a vertical drying oven. The surface shape becomes rough because it is dried and semi-cured. If the surface roughness of the prepreg itself is rough, the surface roughness of the plastic substrate obtained is also rough.
In order to obtain a laminated sheet from a prepreg, a multistage batch press is generally used in which a metal foil such as a copper foil, a prepreg, a mirror plate, etc. are combined as one set between hot plates and heat-molded by stacking a number of them. Is. At this time, since the resin also flows to some extent, the surface shape of the prepreg itself does not become the surface of the laminate itself, but the surface roughness of the original prepreg is reflected. That is, in the initial press, the resin is pressed in a state where there is no fluidity, but at this time, the metal foil is deformed by the pressure and becomes a shape reflecting the surface shape of the prepreg and reaches a fluid temperature range. In some cases, the metal foil or the metal plate has a shape reflecting the initial surface roughness of the prepreg, so that it does not become a smooth plastic substrate.
Surface smoothness is required for a plastic substrate used in a display device. In particular, when used in a display device, a semiconductor element may be directly written on a substrate and smoothness at a level of 2 μm is required. However, it is difficult to obtain this level of smoothness by a conventional method of pressing using a prepreg. Met.
Multi-stage batch presses are not only low in productivity, but also have uneven temperature in each stage's hot platen, and the heat history applied to each laminate during molding is different, so plate thickness accuracy, formability, warpage, dimensions It has been difficult to produce a laminated board with a small difference in quality due to a difference in quality such as rate of change. Furthermore, a plastic substrate can be obtained by etching and removing the copper foil of the obtained laminate, but the copper foil surface with insufficient surface smoothness (generally there are irregularities of about 5 μm on the glossy side) is transferred. Therefore, it could not be used for a liquid crystal display device.
[0003]
[Problems to be solved by the invention]
The present invention has been made in view of the above facts, and an object thereof is to provide a composite substrate having excellent surface smoothness and high productivity that can be used for a plastic substrate or the like used in a liquid crystal display device. .
[0004]
[Means for Solving the Problems]
That is, the present invention
(1) Surface roughness (Ry) where a peelable resin sheet is laminated on the front and back of a prepreg impregnated or coated / dried with a thermosetting resin composition on a fiber cloth, and the resin is cured and then peeled off. ) Is a method of manufacturing a composite substrate for a liquid crystal display device of 2 μm or less, the surface roughness (Ry) on the transfer surface side of the peelable resin sheet is 0.4 μm or less, and the peelable resin sheet is separated. A method for producing a composite substrate for a liquid crystal display device, wherein the polyester film is subjected to a mold treatment or a polyimide film is subjected to a release treatment, and the composite substrate is continuously wound up,
(2) The method for producing a composite substrate according to (1), wherein the thermosetting resin composition contains a cyanate resin,
(3) The method for producing a composite substrate according to (1), wherein the thermosetting resin composition contains a cyanate resin and an epoxy resin,
(4) The method for producing a composite substrate according to (2) or (3), wherein the cyanate resin is a novolak type cyanate resin and / or a prepolymer thereof,
(5) The manufacturing method of the composite substrate in any one of (1)-(4) which contains an inorganic filler in the said thermosetting resin composition,
(6) The method for producing a composite substrate according to (5), wherein the inorganic filler is spherical fused silica having an average particle size of 2 μm or less,
(7) The method for producing a composite substrate according to (5) or (6), wherein the content of the inorganic filler is 10 to 400 parts by weight with respect to 100 parts by weight of the resin component,
It is.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
The present invention uses a releasable resin sheet having specific physical properties to laminate on the front and back of the prepreg, and after the resin is cured, the releasable resin sheet is peeled off without requiring a press step that was conventionally required. It has been found that a continuously smooth plastic substrate can be obtained.
In the present invention, the peelable metal foil that has been conventionally used during prepreg molding (laminate) is deformed by the surface shape and pressure of the prepreg, and the surface smoothness of the transferred copper foil itself is insufficient. On the other hand, the peelable resin sheet has an advantage that it can be laminated along the surface shape of the prepreg, and the surface of the prepreg can be evenly flattened and smoothed according to the pressure of the laminate roll.
In the present invention, a fiber cloth is impregnated with a thermosetting resin solution and dried until it becomes a tack-free (semi-cured) state to form a prepreg. Then, a peelable resin sheet is heated and pressure-bonded to the front and back of the obtained prepreg, and further the resin is heated and cured, and then the resin sheet is peeled off to form a composite substrate, which is then rolled up continuously. Is what you get.
In the present invention, the conditions for drying the impregnated resin solution to form a semi-cured prepreg vary depending on the type of the impregnating resin and the solvent, but 50 to 200 ° C. and 0.5 to 30 minutes are suitable. When the temperature is lower than this and the time is short, the fluidity is large, the exudation from the end face is large, the film thickness varies greatly, and the composite substrate does not have a uniform thickness. Also, when the temperature is higher and the time is longer than this, the fluidity is too small when heating and pressure bonding with the peelable sheet, and the substrate surface cannot be sufficiently smoothed.
The conditions for heating and pressure-bonding the peelable sheet to the prepreg are 70 to 200 ° C., 0.1 to 10 MPa, 5 to 30 minutes in the case of a press type, and 70 to 200 ° C. and 0.1 to 5 minutes in the case of a roll laminator. The conditions of 100 MPa and 0.1 to 10 m / min are appropriate, and it is desirable that the temperature be in particular the drying temperature of the impregnating resin ± 60 ° C. If the laminating temperature is low, the resin is not softened and the substrate surface cannot be sufficiently smoothed. On the other hand, if the laminating temperature is too high, the solvent in the impregnating resin may suddenly evaporate and foam, or the flow may be too large and the resin may flow out. When the transfer sheet is heated and pressure-bonded to the fiber cloth in the press format, it is desirable to bond the front and back simultaneously from the viewpoint of efficiency, but when using a roll laminator, it can also be bonded to each side.
The composite substrate (laminated plate) containing the fiber cloth used in the present invention is not particularly limited as long as it is used in a liquid crystal display device, but the Tg of the impregnating resin used from the viewpoint of heat resistance is 150 ° C. or higher. It is preferable. Specific examples include a cyanate resin, a thermosetting polyimide resin containing bismaleimide as a constituent component, and a polyfunctional epoxy resin. Of these, a cyanate resin is particularly preferable.
[0006]
Examples of the cyanate resin used in the present invention include bisphenol dicyanate, di (4-cyanate-3,5-dimethylphenyl) methane, 4,4′-thiodiphenyl cyanate, and 2,2′-di (4-cyanatephenyl) hexa. Fluoropropane, bisphenol E dicyanate, cyanate of a phenol / dicyclopentadiene copolymer, phenol novolac type cyanate resin, cresol novolac type cyanate resin, and / or a prepolymer thereof can be used. Of these, novolak cyanate resins and / or prepolymers thereof are preferred because of their high heat resistance and low linear expansion coefficient. The novolak-type cyanate resin here is obtained by reacting an arbitrary novolak resin with a cyanating reagent such as cyanogen halide, and prepolymerizing by heating the obtained resin. I can do it.
When the number average molecular weight of the novolak-type cyanate resin in the present invention is less than 250, the crosslinking density is small and the heat resistance and the linear expansion coefficient may be inferior. When it exceeds 900, the crosslinking density is excessively increased and the reaction is completed. Since it may be impossible, it is desirable that it is 260-900, More preferably, it is 300-600. Moreover, when using a prepolymer, it is desirable to use the novolak cyanate resin having the above-mentioned number average molecular weight after prepolymerization within a range soluble in a solvent such as methyl ethyl ketone, dimethylformamide, cyclohexanone and the like. The number average molecular weight referred to in the present invention is a gel-permeation chromatography in terms of polystyrene using an HLC-8120GPC apparatus manufactured by Tosoh Corporation (use columns: SUPER H4000, SUPER H3000, SUPER H2000 × 2, eluent: THF). It is a value measured by a graphic method.
[0007]
In the resin composition of the present invention, one or more thermoplastic resins such as other thermosetting resins such as epoxy resin and phenol resin, phenoxy resin, solvent-soluble polyimide resin, polyphenylene oxide, and polyethersulfone are used in combination with cyanate resin. You may do it. In particular, the combined use of an epoxy resin is preferable because the water absorption can be reduced without deteriorating the chemical resistance. Examples of the epoxy resin used in combination include a phenol novolac type epoxy resin, a bisphenol A type epoxy resin, a dicyclopentadiene skeleton-containing epoxy resin, a naphthalene type epoxy resin, and an arylalkylene type epoxy resin, and in particular, a dicyclopentadiene skeleton epoxy resin, Naphthalene type epoxy resins and aryl alkylene type epoxy resins are preferred. Here, the aryl alkylene type epoxy resin refers to an epoxy resin having one or more aryl alkylene groups in the repeating unit, and examples thereof include a xylylene type epoxy resin and a biphenylene dimethyl type epoxy resin.
The amount of the epoxy resin used in combination is preferably 10 to 200 parts by weight with respect to 100 parts by weight of the cyanate resin. When the amount is less than 10 parts by weight, the effect of addition is hardly exhibited, and when it exceeds 200 parts by weight, the heat resistance of the cyanate resin may be impaired.
[0008]
The resin composition of the present invention preferably uses an inorganic filler together with a resin component such as a cyanate resin. The inorganic filler is added to increase the elastic modulus, decrease the linear expansion coefficient, and decrease the water absorption. Examples of the inorganic filler include talc, alumina, glass, silica, mica and the like. Among these, fused silica is preferable in that it has excellent low thermal expansibility. Furthermore, it is preferable to use spherical fused silica having an average particle size of 2 μm or less among fused silica in terms of improving the filling property. When the average particle size exceeds 2 μm, the impregnation property to the fiber cloth at the time of prepreg production, the inorganic filler in the resin composition is settled, and the surface smoothness is lowered, which is not desirable. The average particle size is preferably 0.2 μm or more in terms of viscosity control. In the present invention, the average particle diameter was measured by a laser diffraction / scattering method using a Horiba, Ltd. particle size distribution measuring apparatus LA920.
As a compounding quantity of an inorganic filler, 10-400 weight part is preferable with respect to 100 weight part of resin components, such as cyanate resin, More preferably, it is 40-300 weight part. If the amount is less than 10 parts by weight, the effect of reducing the thermal expansion due to the addition of the inorganic filler is small. If the amount exceeds 400 parts by weight, the proportion of the inorganic filler in the resin composition is too large, and the resin varnish becomes a glass substrate. There is a tendency that operations such as coating and impregnation are difficult.
[0009]
It is preferable to add a coupling agent to the resin composition of the present invention. By improving the wettability of the interface between the resin and the inorganic filler, the coupling agent has an effect of uniformly fixing the resin and the filler to the glass cloth and improving heat resistance and moisture absorption. Any coupling agent can be used as long as it is usually used. Among these, at least one selected from an epoxy silane coupling agent, a titanate coupling agent, an aminosilane coupling agent, and a silicone oil type coupling agent. Use of a coupling agent is preferable in terms of high wettability with the interface with the inorganic filler and improvement in heat resistance. In the present invention, the coupling agent is desirably 0.05% by weight or more and 3% by weight or less with respect to the inorganic filler. If it is less than this, the filler cannot be sufficiently covered, and if it is more than this, the mechanical properties and the like are lowered, so it is desirable to use within this range.
[0010]
When using cyanate resin by this invention, it is preferable to add a hardening accelerator to a resin composition. As the curing accelerator, known ones can be used. For example, organic metal salts such as zinc naphthenate, cobalt naphthenate, tin octylate, cobalt octylate, triethylamine, tributylamine, diazabicyclo [2,2 , 2] octane, tertiary amines, 2-phenyl-4-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5 -Imidazoles such as hydroxymethylimidazole, phenol, bisphenol A, nonylphenol, phenolic compounds such as phenol resin, organic acids, and the like, or a mixture thereof. Among these, a phenol resin is preferable from the viewpoints of curability and few ionic impurities. In the present invention, the blending amount of the curing accelerator can be appropriately changed according to the use conditions. However, in the case of an organometallic salt, 0.001 to 1 part by weight of imidazoles is added to 100 parts by weight of the cyanate resin. In the case of phenol resin, it is preferably in the range of 0.5 to 50 parts by weight. If it is less than these ranges, curing tends to be slow, and if it is more than these ranges, the resin composition and prepreg life are lowered due to excessive acceleration, and adverse effects such as ambient contamination due to volatile components derived from the curing accelerator. There is a risk of getting out.
[0011]
The fiber cloth used in the present invention is not particularly limited, and various inorganic or organic fiber cloths can be used. Specific examples include E glass (non-alkali glass), S glass, D glass, NE glass, quartz, high dielectric constant glass, etc., Kevlar (trade name: manufactured by DuPont Toray Kevlar), Technora ( Poly-p-phenylenephthalamide, poly-m-phenylenephthalamide, p-phenylenephthalamide, and 3,4'-diphenyl ether, represented by trade name: Teijin Limited) and Conex (trade name: Teijin Limited) Examples thereof include aromatic polyamide fiber cloth, aramid fiber cloth, polyester fiber cloth, nylon fiber cloth, polybenzazole fiber cloth, and carbon fiber cloth made of a phthalamide copolymer. A glass cloth is preferable. The method of weaving the woven filament is not particularly limited, and may be a woven fabric having a structure such as plain weave, Nanako weave, satin weave, twill weave, etc., and plain weave is preferable. Moreover, it is not limited to a woven fabric and may be a non-woven fabric. The thickness of the fiber is not particularly limited, but is preferably 30 to 300 μm.
[0012]
The fiber fabric used in the present invention is treated with various surface treatment agents such as various silane coupling agents, borane coupling agents, titanate coupling agents, aluminum coupling agents for the purpose of improving the wettability with the resin component. However, the present invention is not limited to this.
The peelable resin sheet of the present invention is a resin sheet having a surface roughness Ry of 0.5 μm or less on the transfer surface side, a Tg or thermal decomposition temperature of 180 ° C. or higher, and a linear expansion coefficient coefficient of 150 ° C. to 180 ° C. of less than 90 ppm. Is preferred. The surface roughness Ry on the transfer surface side is preferably as low as possible, but when a sheet of 0.5 μm or more is used, this surface is transferred to the prepreg and the surface roughness becomes rough. When using a resin sheet that requires heat resistance that can withstand the manufacturing process of the plastic substrate and the linear expansion coefficient exceeds 90 ppm, curl occurs because stress is inherent in the prepreg before the resin sheet is peeled off. , It may be difficult to smoothly perform the post-process. Examples of preferred resins include polyester resins, polyimide resins, polyamide resins and the like.
[0013]
If necessary, the resin composition of the present invention may be blended with components such as a lubricant, a heat-resistant agent, an antistatic agent, an ultraviolet absorber, a pigment, and a light stabilizer as long as the effects of the present invention are not impaired. Can do.
In order to impregnate the fiber composition with the resin composition of the present invention, alcohols, ethers, acetals, ketones, esters, alcohol esters, ketone alcohols, ether alcohols, ketone ethers, ketone esters, A prepreg can be obtained by forming into a varnish using an organic solvent such as ester ether, applying and drying to a peelable substrate sheet, laminating on the front and back of the fiber cloth, and then peeling the resin sheet.
[0014]
【Example】
EXAMPLES Next, although an Example and a comparative example are given and this invention is demonstrated in detail, this invention is not restrict | limited to a following example, unless the summary is exceeded.
Example 1
100 parts by weight of a novolak-type cyanate resin (PT60 manufactured by Lonza Japan Co., Ltd., number-average molecular weight 560) and 2 parts by weight of a phenol novolak resin (PR-51714 manufactured by Sumitomo Durez) are dissolved in methyl ethyl ketone at room temperature to prepare an epoxy silane coupling agent (Japan 1 part by weight of Unicar A-187) and 150 parts of spherical fused silica (SO-25R average particle size 0.5 μm manufactured by Admatechs Co., Ltd.) were added and stirred for 10 minutes using a high-speed stirrer to obtain a resin varnish. The prepared resin varnish was impregnated into a glass cloth (thickness 53 μm, manufactured by Nitto Boseki Co., Ltd., WEA-1080) using a roll squeeze type impregnation apparatus, and dried at 180 ° C. for 2 minutes to obtain a prepreg having a total thickness of 80 μm. Using a rubber roll laminator, polyester (PET) having a surface roughness Ry of 0.3 μm obtained by releasing the resin surface of the transfer sheet at 160 ° C., 1 MPa, 1 m / min was obtained. The resulting prepreg was laminated continuously at the same time, dried at 200 ° C. for 10 minutes, and then the peelable resin sheet was peeled off to obtain a composite substrate. The obtained composite substrate was excellent in smoothness with a surface roughness Ry of 1.2 μm, and could be used as a display substrate.
(Example 2)
A prepreg was obtained in the same manner as in Example 1 except that 50 parts by weight of spherical fused silica SO-25R and 0.4 parts by weight of epoxy silane coupling agent A-187 were used. The obtained composite substrate was excellent in smoothness with a surface roughness Ry of 1.1 μm, and could be used as a display substrate.
(Example 3)
A prepreg was obtained in the same manner as in Example 1 except that a polyimide film (Upilex 25S: manufactured by Ube Industries, Ltd.) having a transfer surface side surface roughness Ry of 0.4 μm was used as the release film. The obtained composite substrate was excellent in smoothness with a surface roughness Ry of 1.3 μm, and could be used as a display substrate.
(Comparative Example 1)
Using the prepreg of Example 1, this prepreg is inserted between two electrolytic copper foil (18 μm) glossy surfaces (surface roughness Ry is 5 μm), a mirror stainless steel plate is used as a backing plate, pressure 4 MPa, temperature 220 A double-sided copper-clad laminate was obtained by heating and pressing at 1 ° C. for 1 hour. Further, the copper foil on both sides was etched to remove the entire surface to obtain a composite substrate. The obtained composite substrate had a surface roughness Ry of 4.3 μm and was not smooth enough to be used as a display substrate.
(Comparative Example 2)
A prepreg was obtained in the same manner as in Example 1 except that 50 parts by weight of spherical fused silica SO-25R and 0.4 parts by weight of epoxy silane coupling agent A-187 were used. A composite substrate was obtained by the same method as in Comparative Example 1 using the obtained prepreg. The obtained composite substrate had a surface roughness Ry of 4.6 μm and was not smooth enough to be used as a display substrate.
[0015]
【The invention's effect】
The composite substrate having a smooth surface obtained by the present invention is suitable as a plastic substrate used in a liquid crystal display device. Moreover, continuous production in a roll shape is possible, and this is a production method with excellent productivity.

Claims (7)

The surface roughness (Ry) at which the peelable resin sheet is peeled off after laminating a peelable resin sheet on the front and back of a prepreg impregnated or coated / dried with a thermosetting resin composition on a fiber cloth is 2 μm The following manufacturing method of a composite substrate for a liquid crystal display device , wherein the surface roughness (Ry) on the transfer surface side of the peelable resin sheet is 0.4 μm or less, and the peelable resin sheet is subjected to a mold release treatment. A method for producing a composite substrate for a liquid crystal display device, comprising: a polyester film applied or a polyimide film subjected to a release treatment, wherein the composite substrate is continuously wound up . The method for producing a composite substrate according to claim 1, wherein the thermosetting resin composition contains a cyanate resin. The method for producing a composite substrate according to claim 1, wherein the thermosetting resin composition contains a cyanate resin and an epoxy resin. 4. The method for producing a composite substrate according to claim 2, wherein the cyanate resin is a novolak cyanate resin and / or a prepolymer thereof. The manufacturing method of the composite substrate as described in any one of Claims 1-4 which contains an inorganic filler in the said thermosetting resin composition. The method for producing a composite substrate according to claim 5, wherein the inorganic filler is spherical fused silica having an average particle diameter of 2 μm or less. The method for producing a composite substrate according to claim 5 or 6 , wherein the content of the inorganic filler is 10 to 400 parts by weight with respect to 100 parts by weight of the resin component.