JP4968460B2 - Resin composition, metal foil with resin composition and printed wiring board - Google Patents

Description

  The present invention relates to a highly heat-resistant printed wiring board suitable for mounting a light-emitting element such as a light-emitting diode and a high heat resistance, a resin composition used therefor, and a metal foil with a resin composition.

  In a printed wiring board on which a light emitting element such as a light emitting diode is mounted or a printed wiring board not mounted on a light emitting element used around the light emitting element, it is required not to reduce the amount of reflected light of the light emitting element in order to ensure brightness. Yes.

  Conventionally, as a method for producing a printed wiring board on which a light emitting element is mounted, a method for producing a laminated board in which a metal foil coated with a resin containing a white filler and a prepreg are integrated by heating and pressing is disclosed ( JP-A-7-241952). Specifically, one or more prepreg sheets obtained by impregnating a sheet-like glass fiber base material with an epoxy resin and semi-cured thereon are stacked on an inner layer printed wiring board on which a circuit is formed, and a white filler is further included thereon. This is a method in which a copper foil coated with a resin is pressure-integrated and molded by a hot plate press.

  As shown in FIG. 6, the LED chip is obtained by mounting an LED element 103 on one surface 102 of a printed wiring board 101 obtained by the above method. The LED element 103 is connected to the conductor circuit of the printed wiring board 101 by a wire 104 and sealed with a resin 105.

  Although the surface layer of the printed wiring board 101 used for the LED chip 100 is blended with a white filler, the epoxy resin tends to absorb light of 400 to 600 nm, so the reflection becomes weak and the brightness is ensured. It was not enough to do. Moreover, the sheet-like glass fiber base material mix | blended with the printed wiring board 101 permeate | transmits light, and it was inadequate to ensure brightness similarly. In particular, visible light having a wavelength region of 400 to 600 nm tends to reduce the amount of reflected light compared to light having a wavelength region of 600 nm or more, and ensuring brightness for light having a wavelength of 400 to 600 nm. It was desired.

Further, when the resin composition used in the prepreg is only a normal epoxy resin, it cannot withstand the heat generated due to the light emission of the device, and the deterioration of mechanical properties due to heat has been a problem. In order to solve this, what has been blended with a highly heat-resistant aromatic epoxy resin has been proposed, but when the light-emitting element is directly mounted, it may be exposed to a temperature close to 200 ° C. Previously remained unresolved. Further, in many cases, connection by wire bonding is performed when connecting the printed wiring board and the light emitting element. However, there is a problem that a sufficient strength cannot be ensured if a glass woven fabric is not present, resulting in problems in connection.
Japanese Patent Laid-Open No. 7-241952 (Claim 3)

  Therefore, an object of the present invention is to efficiently reflect visible light of a device, particularly visible light in a wavelength region of 400 to 600 nm when a light-emitting device is mounted, and to have high heat resistance that can withstand the light emitted from the light-emitting device. Another object of the present invention is to provide a printed wiring board having high rigidity, a resin composition used therefor, and a metal foil with a resin composition.

  In this situation, as a result of intensive studies, the present inventor has (1) a sheet-like glass fiber base material and an epoxy resin, which have been conventionally used for prepregs of resin compositions for printed wiring boards, to significantly reduce the amount of reflected light. (2) Instead of the sheet-like glass fiber base material, an inorganic filler with an increased amount is used, and the inorganic filler is a first powder inorganic filler having an average particle diameter of about 0.5 μm and If the mixed filler of the second powder inorganic filler having an average particle diameter of about 1.0 μm is used, the visible light of the element, particularly 400 to 600 nm, is obtained when the light emitting element is mounted without resonating at a wavelength of 400 to 600 nm. The ability to efficiently reflect visible light in the wavelength region, and (3) the light emission heat of the light emitting device by using a cyanate resin or a mixed resin of its prepolymer and epoxy resin. It has been found that high heat resistance that can withstand heat resistance can be imparted, and that high rigidity that enables wire bonding connection can be imparted without using a sheet-like glass fiber substrate, and the present invention has been completed.

  That is, this invention is a resin composition for printed wiring boards laminated | stacked on one side surface of metal foil or a resin film, Comprising: (A) Cyanate resin or its prepolymer, (B) Epoxy resin, (C ) A curing agent, (D) a mixed filler of a first powder inorganic filler having an average particle size of 0.45 to 0.55 μm and a second powder inorganic filler having an average particle size of 0.8 to 1.2 μm, and (E) white It contains a pigment, and the content of the mixed filler (D) is 30 to 60% by weight in the resin composition.

  Moreover, this invention provides the metal foil with a resin composition obtained by laminating | stacking the said resin composition on one side of metal foil.

  Further, the present invention is obtained by heating and pressurizing the metal foil with the resin composition on one side or both sides of the inner printed wiring board so that the resin composition is inside. A printed wiring board is provided.

  When the printed wiring board of the present invention is used for an LED chip, visible light of the element, particularly visible light in a short wavelength region of 400 to 600 nm can be reflected with a reflectance of 80% when a light emitting element is mounted. The reflectance of a printed wiring board using a conventional prepreg is at most 40%, and it is possible to ensure brightness that has not been obtained conventionally. In addition, since a mixed resin of cyanate resin or a prepolymer thereof and an epoxy resin is used, high heat resistance capable of withstanding the light emission heat of the light emitting element can be imparted, and further, high rigidity capable of wire bonding connection can be imparted. .

(Description of resin composition)
The resin composition of the present invention is a resin composition for printed wiring boards that is laminated on one side of a metal foil or resin film. The cyanate resin or its prepolymer, which is one component of the resin composition, can impart heat resistance to the printed wiring board when used in combination with an epoxy resin. In addition, the cyanate resin or its prepolymer can increase the storage elastic modulus when used in combination with a mixed filler.

  Examples of the cyanate resin include those obtained by reacting a cyanogen halide compound with phenols. Moreover, the cyanate resin prepolymer can be obtained by prepolymerizing the cyanate resin obtained by the method by a method such as heating. Specific examples of the cyanate resin include bisphenol type cyanate resins such as novolak 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. If a cyanate resin or a prepolymer thereof is used, the heat resistance is improved because the crosslink density is increased. At the same time, flame retardancy can be improved. Cyanate resin and its prepolymer can also be used together.

  As the novolac type cyanate resin, for example, those represented by the following general formula (I) can be used.

  The weight average molecular weight of the novolak cyanate resin represented by the general formula (I) is not particularly limited, but is preferably 500 to 4,500, and particularly preferably 600 to 3,000. When the weight average molecular weight of the novolak-type cyanate resin is less than the lower limit value, the mechanical strength may be lowered, and when the upper limit value is exceeded, the resin composition may be cured at a high rate, so that the storage stability may be lowered. The novolak-type cyanate resin can be obtained, for example, by reacting an arbitrary novolak resin with a compound such as cyanogen chloride or cyanogen bromide. These cyanate resins or prepolymers thereof can be used alone or in combination of two or more.

  In the resin composition of the present invention, an epoxy resin (B) is further used. The epoxy resin can improve moisture absorption characteristics when used in combination with a cyanate resin or a prepolymer thereof, and can provide a highly rigid substrate having heat resistance and moisture absorption resistance.

  The epoxy resin is not particularly limited, but bisphenol A epoxy resin, bisphenol F epoxy resin, phenol novolac epoxy resin, cresol novolac epoxy resin, bisphenol A novolac epoxy resin, naphthalene modified epoxy resin, dicyclopentadiene modified epoxy resin, aralkyl modified epoxy. Resin, diaminodiphenylmethane-modified epoxy resin, and the like. Among these, a cresol novolac epoxy resin is preferable in order to develop high heat resistance, and a dicyclopentadiene-modified epoxy resin is preferable in that the dielectric loss tangent can be reduced.

  Moreover, in order to express flame retardancy, those obtained by halogenating these epoxy resins can also be used. As the halogenated epoxy resin, it is preferable to use a brominated epoxy resin having a bromination rate of 20% or more and a weight average molecular weight of 10,000 to 30,000. Examples of brominated epoxy resins include brominated bisphenol A type epoxy resins and brominated bisphenol F type epoxy resins, among which brominated bisphenol A type epoxy resins are preferred. These epoxy resins can be used alone or in combination of two or more.

  The compounding ratio ((A) :( B)) of the cyanate resin, its prepolymer (A) and the epoxy resin (B) is 60:40 to 30:70, preferably 50:50 to 35:65, based on parts by weight. Especially preferably, it is 45: 55-40: 60. When there are too many compounding quantities of cyanate resin and its prepolymer (A) in combined use resin, while becoming hard and brittle, moisture absorption heat resistance will worsen. Moreover, when there are too many compounding quantities of an epoxy resin (B), a glass transition temperature will become low and heat resistance will worsen.

  The compounding ratio of the mixed resin of cyanate resin and its prepolymer (A) and epoxy resin (B) is 35 to 65% by weight, preferably 40 to 60% by weight, based on the entire resin composition. If it is less than 35% by weight, it is not preferable in that the amount of filler increases and becomes brittle, whereas if it exceeds 65% by weight, it is not preferable in that the hardness cannot be maintained.

  The curing agent (C) is used for curing the epoxy resin and promoting the reaction of the cyanate resin. Examples of the curing agent include amine compounds, imidazole compounds, acid anhydrides, phenol resin compounds, and the like. An amine compound is preferable because it can sufficiently cure the epoxy resin in a small amount and can exhibit the flame retardancy of the resin. Amine-based compounds are solid at room temperature with a melting point of 150 ° C. or higher, soluble in organic solvents, have low solubility in epoxy resins, reach high temperatures of 150 ° C. or higher, and react quickly with epoxy resins. Particularly preferred. Specific examples include dicyandiamide, diaminodiphenylmethane, and diaminodiphenylsulfone. These amine compounds are dissolved in a solvent and uniformly dispersed in the resin composition varnish. Since the compatibility with epoxy resin is small, when the solvent is volatilized and removed, it is dispersed microscopically in the resin and the reaction does not proceed at room temperature to 100 ° C. Therefore, a uniform epoxy resin while maintaining good storage stability A cured product can be obtained.

  The imidazole compound can accelerate the reaction of the cyanate resin or its prepolymer without reducing the insulating properties of the resin composition. Examples of the imidazole compound include 2-phenyl-4-methylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, and 2,4-diamino- 6- [2′-Methylimidazolyl- (1 ′)]-ethyl-s-triazine, 2,4-diamino-6- (2′-undecylimidazolyl) -ethyl-s-triazine, 2,4-diamino- 6- [2'-Ethyl-4-methylimidazolyl- (1 ')]-ethyl-s-triazine. Among these, imidazole compounds having two or more functional groups selected from an aliphatic hydrocarbon group, an aromatic hydrocarbon group, a hydroxyalkyl group, and a cyanoalkyl group are preferable, and 2-phenyl-4,5 is particularly preferable. -Dihydroxymethylimidazole is preferred. Thereby, the heat resistance of a resin composition can be improved, the thermal expansion of the insulating layer obtained can be suppressed, and a water absorption can be reduced.

  The compounding amount of the curing agent (C) is preferably 0.05 to 5% by weight, particularly preferably 0.2 to 2% by weight in the resin composition. Moreover, when using an imidazole compound as a hardening | curing agent (C), the suitable compounding quantity of an imidazole compound is 0.05 to 5 weight% in a resin composition, Especially 0.2 to 2 weight%. When the content of the imidazole compound is within the above range, the heat resistance can be particularly improved.

  The resin composition of the present invention contains a mixed inorganic filler (D). Addition of the mixed inorganic filler (D) can improve the light reflectance of visible light, particularly light in the visible short wavelength region of 400 to 500 nm, and can achieve low thermal expansion and flame retardancy. Further, the storage elastic modulus can be improved by the combination of the cyanate resin or a prepolymer thereof, particularly a novolac type cyanate resin and a mixed inorganic filler.

  The mixed inorganic filler (D) has an average particle size of 0.45 to 0.55 μm, preferably 0.47 to 0.53 μm, and an average particle size of 0.8 to 1.2 μm, preferably Is a mixture of the second powder inorganic filler of 0.85 to 1.15 μm. Both the first powder inorganic filler and the second powder inorganic filler have a uniform particle size distribution, and the first powder inorganic filler is present between 0.25 and 0.75 μm in particle size. The powder to be used is 90% or more, preferably 95% or more of the entire first powder inorganic filler, and the second powder inorganic filler is a powder having a particle size of 0.75 to 1.50 μm. It is 90% or more of the whole inorganic filler, preferably 95% or more. For both the first powder inorganic filler and the second powder inorganic filler, the particle size and particle size distribution can be measured by a laser scattering method.

  In the mixed filler, the blending amount of the first powder inorganic filler is 200 to 500 parts by weight, preferably 350 to 450 parts by weight with respect to 100 parts by weight of the second powder inorganic filler. Moreover, the compounding quantity of a mixed filler is 30 to 60 weight% in the whole resin composition, Preferably it is 45 to 55 weight%.

  Since the 1st powder inorganic filler and the 2nd powder inorganic filler have the above-mentioned average particle size and the above-mentioned particle size distribution, respectively, the reflectance of light in a short wavelength region of 400-600 nm improves especially. When only the first powder inorganic filler having an average particle diameter of about 0.5 μm is used as the filler, light having a wavelength of 500 nm is transmitted and the reflectance is lowered. By further using a second powdered inorganic filler having an average particle diameter of 0.8 to 1.2 μm in addition to this, it is possible to block transmitted light that closes a gap of 0.5 μm. On the other hand, when only the second powder inorganic filler having an average particle diameter of 0.8 to 1.2 μm is used as the filler, a gap of about 0.5 μm is generated and light in a short wavelength region of 400 to 600 nm is transmitted. As a result, the reflectance decreases.

On the other hand, if the blending amount of the mixed filler is less than 30 % by weight in the entire resin composition, the effect of low thermal expansion and low water absorption may be reduced, and improvement in storage modulus cannot be expected. The blending amount of the inorganic filler in the conventional resin composition was 10 to 30% by weight, but in the present invention, the blending amount is larger than that. On the other hand, if it exceeds 60% by weight in the whole resin composition, there is a risk of forming a conductor path in the resin composition, which is not preferable.

  Examples of the first powder inorganic filler and the second powder inorganic filler include talc, alumina, glass, silica, mica, and the like. Among these, silica is preferable, and fused silica is preferable in that it has excellent low expansibility. The shape is crushed and spherical, but it is preferable to use spherical silica from the viewpoint that close-packing can be performed, the reflectance can be increased, and the expansion can be efficiently reduced.

  A known white pigment can be used for the white pigment (E). Specific examples include titanium oxide, kaolin, calcium carbonate, and zinc oxide. The crystal structure of titanium oxide may be either a rutile type or an anatase type, but the anatase type is preferred in that the reflectance in the visible short wavelength region is good. The compounding quantity of a white pigment is 0.5 to 10 weight% in a resin composition. If the amount of the resin composition is less than 0.5% by weight, the effect of improving the reflectivity is not obtained. If the amount exceeds 10% by weight, mechanical properties such as cracking are deteriorated.

  Although it does not specifically limit in the resin composition of this invention, It is preferable to contain a coupling agent further. The coupling agent improves the wettability at the interface between the resin and the mixed inorganic filler, thereby uniformly fixing the resin and the inorganic filler to the substrate, and improving the heat resistance, particularly the solder heat resistance after moisture absorption. For blending.

  As the coupling agent, any of those usually used can be used, and among these, one selected from an epoxy silane coupling agent, a titanate coupling agent, an aminosilane coupling agent, and a silicone oil type coupling agent. It is preferable to use the above coupling agent. Thereby, wettability with the interface of an inorganic filler can be made high, and heat resistance can be improved more.

  Although content of the said coupling agent is not specifically limited, 0.05-3 weight part is preferable with respect to 100 weight part of mixed inorganic fillers. If the content is less than the lower limit, the mixed inorganic filler cannot be sufficiently coated and the effect of improving heat resistance may be reduced, and if the content exceeds the upper limit, the bending strength of the resin-coated metal foil may be reduced. is there.

  The resin composition of this invention can add additives other than the said component in the range which does not impair a characteristic as needed. Examples of the additive include an antifoaming material and a leveling material. Moreover, in the resin composition of this invention, sheet-like fiber base materials, such as a glass fiber base material, are not included. Examples of the sheet-like base material that is not used include glass fiber base materials such as glass fiber cloth and glass non-woven cloth, or inorganic fiber base materials such as fiber cloth and non-fiber cloth containing inorganic compounds other than glass, aromatic polyamide resins, polyamides. Examples thereof include organic fiber base materials composed of organic fibers such as resins, aromatic polyester resins, polyester resins, polyimide resins, and fluororesins. By not using a sheet-like fiber base material in the resin composition, and further using a mixed inorganic filler that can be closely packed in a predetermined blending amount, light in a wavelength region of 400 to 600 nm of the obtained printed wiring board is obtained. A reflectance of 80% is obtained.

  The physical properties of the cured product of the resin composition, for example, the glass transition temperature (Tg) when the resin composition is heated and cured at 200 ° C. for 2 hours is 200 ° C. or higher and 230 to 250 ° C., and has a wavelength of 400 to 600 nm. The light reflectivity is about 80%. Thereby, it is very stable with respect to the thermal history at the time of mounting a light emitting element, Furthermore, the light of a light emitting element can be reflected efficiently, and deterioration of light quantity can be prevented. Further, the storage elastic modulus at 200 ° C. when heated and cured at 180 ° C. for 1 hour is 2 to 20 MPa. If the storage elastic modulus at 200 ° C. is in this range, there is little dent in wire bonding at the time of component connection, and a reliable connection can be made. Further, the cured product of the resin composition of the present invention has a storage elastic modulus at 200 ° C. of 30 to 80% with respect to the storage elastic modulus at room temperature. If the retention rate is within this range, even a thin printed wiring board will not be deformed by the weight of the component even with a heat history of 200 ° C. or higher during LED mounting, and reliable mounting can be performed. it can.

(Description of metal foil with resin)
Next, the resin-coated metal foil of the present invention will be described with reference to FIG. FIG. 1 (B) is a longitudinal sectional view of a resin-attached metal foil, and FIG. 1 (A) is a view showing the resin composition portion and the metal foil portion apart from each other in an easily understandable manner. The metal foil with resin 20 is obtained by laminating the above-described resin composition 21 on the metal foil 22. Examples of the method of laminating the resin composition 21 on the metal foil 22 include, for example, a method in which the resin composition is dissolved in a solvent to form a resin varnish, which is applied to the metal foil and dried, and a film obtained from the resin composition is laminated. And the like. Among these, a method in which a resin varnish is applied to a metal foil and dried is preferable. Thereby, the metal foil with resin which has the uniform insulating layer thickness without a void can be obtained. Moreover, you may further laminate | stack a release sheet on the resin surface of metal foil with resin.

  As a solvent for dissolving the resin composition, a resin composition varnish is applied to a metal foil and dried at 80 to 180 ° C., and thus does not remain in the resin. Examples of such a solvent include acetone, methyl ethyl ketone, toluene, xylene, n-hexane, methanol, ethanol, methyl cellosolve, ethyl cellosolve, methoxypropanol, cyclohexanone, and N, N dimethylformamide.

  The thickness (h) of the resin composition is not particularly limited, but is preferably 10 to 100 μm, and particularly preferably 20 to 80 μm. Thereby, there is no generation | occurrence | production of the crack of a resin layer and powder fall at the time of cutting can also be decreased. Examples of the metal constituting the metal foil 22 include copper and / or a copper-based alloy, aluminum and / or an aluminum-based alloy, iron and / or an iron-based alloy, and the like. Such a metal foil with resin is usually used as an outer printed wiring board in the production of a printed wiring board.

  Moreover, as shown in FIG. 2, the resin composition may be laminated with a resin film such as PET instead of laminating the metal foil instead of laminating the metal foil. The film with resin 30 is obtained by laminating the above resin composition 21 on the film 23. As a method of laminating the resin composition 21 on the film 23, for example, a method in which the resin composition is dissolved in a solvent to form a resin varnish, which is applied to the film and dried, or a method in which a film obtained from the resin composition is laminated Etc. Moreover, you may further laminate | stack a release sheet on the resin surface of the film 30 with resin. The film with resin 30 can be used as an intermediate insulating material for a multilayer printed board by peeling off the film 23. Moreover, when using as an outer layer printed circuit board of a multilayer printed circuit board, after peeling the film 23, it forms and uses a plating metal foil on the resin surface. The thickness of the film is usually 5 μm or more and 50 μm or less.

(Printed wiring board)
Next, the printed wiring board of this invention is demonstrated with reference to FIGS. 3 is a schematic diagram of a printed wiring board having a two-layer structure, FIG. 4 is a schematic diagram of a printed wiring board having a three-layer structure, and FIG. 5 is a schematic diagram of a printed wiring board having a five-layer structure. Although FIGS. 3 to 5 are shown separated for easy understanding of the constituent members, the constituent members are actually in close contact and there is no space. In FIG. 3, the same components as those in FIG. 1 are denoted by the same reference numerals, description thereof is omitted, and different points are mainly described. The printed wiring board 50 of FIG. 3 is a printed wiring board in which the resin-coated metal foil 20 is superposed on one side of the inner printed wiring board 51 so that the resin is on the inside and heated and pressurized. The inner layer printed wiring board 51 is obtained by forming a circuit 52 on one side of a copper clad laminate 53 and blackening it, for example. The copper clad laminate 53 is a cured prepreg 53 obtained by impregnating a sheet-like glass fiber substrate 54 with a matrix resin such as an epoxy resin. As shown in FIG. 6, the printed wiring board 50 of FIG. 3 undergoes a process of etching the metal foil 22 to form a conductor pattern, a process of forming through-hole plating, a process of mounting LED elements on the mounting surface, and the like. Chip LED. Conventionally, a laminate was formed by interposing a prepreg between a resin-coated metal foil and an inner printed wiring board. However, if the resin-coated metal foil of the present invention is used, the use of a prepreg can be omitted. . This is because the resin viscosity of the metal foil with resin is about 3000 to 10000 poise when heated during pressing and laminating, so that the conductor pattern irregularities of the inner printed wiring board can be embedded without any gaps.

  The LED element is not mounted on the printed wiring board 50, but is mounted on another board that is not mounted, and the LED element non-mounted printed wiring board 50 disposed near the other board is wired to the LED element. There is also a usage method to connect. In this case, the printed wiring board with no LED element mounted is the printed wiring board of the present invention. Even in this case, the reflectance of the non-mounted printed wiring board with respect to light leaking from the LED element can be increased and brightened. Moreover, in the printed wiring board 50 of FIG. 3, it can also be used as a single-sided printed wiring board which abbreviate | omitted the inner layer printed wiring board 51. FIG.

  Since the surface of the printed circuit board on which the LED element is mounted or not mounted according to the present invention is subjected to conductor pattern processing and the resin surface is always exposed, it is meaningful to take measures to increase the light reflectance as in the present invention. .

  4, the same components as those in FIG. 3 are denoted by the same reference numerals, description thereof is omitted, and different points are mainly described. The printed wiring board 60 of FIG. 4 is a printed wiring board in which the resin-coated metal foil 20 is superposed on both surfaces of the inner printed wiring board 51a so that the resin is on the inside and heated and pressurized. As the inner layer printed wiring board 51a, for example, a circuit 52 is formed on both surfaces of a copper clad laminate 53 and blackened. The copper clad laminate 53 is a cured prepreg 53 obtained by impregnating a sheet-like glass fiber base material with a matrix resin such as an epoxy resin.

  In FIG. 5, the same components as those in FIG. 3 are denoted by the same reference numerals, description thereof is omitted, and different points are mainly described. The printed wiring board 70 in FIG. 5 is arranged vertically so that the respective resin compositions of the two resin-attached metal foils 20 are inside, and between the two resin-attached metal foils 20 in order from top to bottom. This is a printed wiring board in which a three-layer body of a first inner layer printed wiring board 51a, a resin composition 21a, and a second inner layer printed wiring board 51a is arranged, heated, and pressed. The resin composition 21a of the inner layer may be used by peeling off the film of the film with the resin composition according to the present invention, but since light reflection occurs in the insulating resin layer of the outer layer, there is little influence on the light reflection, You may use the conventional well-known resin composition, without using the resin composition of this invention.

  In order to form, for example, a seven-layer printed wiring board having five or more layers, in FIG. 5, a first inner printed wiring board 51a, a resin composition 21a, What is necessary is just to arrange | position the 5 layer body of the 2nd inner layer printed wiring board 51a, the resin composition 21a, and the 3rd inner layer printed wiring board 51a, and to heat and pressurize them. That is, the multilayer printed wiring board may be formed by repeatedly forming a laminated body of the inner printed wiring board 51a and the resin composition 21a between the two metal foils 20 with resin.

  In the production process of the printed wiring board, the heating temperature is not particularly limited, but is preferably 140 to 240 ° C. Although the pressure to pressurize is not specifically limited, 1-4 MPa is preferable.

EXAMPLES Next, the present invention will be described more specifically with reference to examples. However, this is merely an example and does not limit the present invention.

-Preparation of resin varnish Novolak-type cyanate resin “PT-60” (Lonza, Inc., weight average molecular weight 2300) 9.9 wt%, novolac-type cyanate resin “PT-30” (Lonza, Inc., weight average molecular weight 1300) 9.9% by weight, bisphenol A type, F type mixed epoxy resin “Epicoat 4275” (manufactured by JER, weight average molecular weight 57000) 14% by weight, orthocresol novolac type epoxy resin “Epicron N-690” (Dainippon Ink and Chemicals) Co., Ltd., epoxy equivalent 220) 15.7% by weight, imidazole compound (manufactured by Shikoku Kasei Kogyo Co., Ltd., 2-phenyl-4,5-dihydroxymethylimidazole) 0.5% by weight, spherical melting as the first powder inorganic filler Silica "SO-25H" (manufactured by Admatechs) 36.0 weight As a second powder inorganic filler, spherical fused silica “SO-31H” (manufactured by Admatechs Co., Ltd.) 9.0% by weight, anatase type titanium dioxide “R-11P”, manufactured by Sakai Chemical Co., Ltd.) 5% by weight is dissolved in methyl ethyl ketone. , Dispersed. Furthermore, 0.5 parts by weight of epoxy silane coupling agent A-187 (manufactured by Nihon Unicar Co., Ltd.) is added as a coupling agent to 100 parts by weight of the mixed filler, and the resin is stirred for 10 minutes using a high speed stirrer A varnish was obtained.

  The first powder inorganic filler has an average particle diameter of 0.5 μm, and the powder existing between 0.25 and 0.75 μm is 99% in the first powder inorganic filler, and the second powder The average particle diameter of the inorganic filler was 1.0 μm, and the powder existing between 0.75 and 1.50 μm was 99% in the second powder inorganic filler.

-Manufacture of resin-coated metal foil The above resin varnish is applied to the anchor surface of a copper foil having a thickness of 18 μm with a comma coater so that the resin thickness after drying is 60 μm, and dried to form a copper with a film-like resin. A foil was obtained.

(3) Production of three-layer printed wiring board As shown in FIG. 6, on the front and back of the inner layer printed wiring board (halogen-free FR-4 (thickness 0.2 mm, manufactured by Sumitomo Bakelite Co., Ltd.)) obtained by etching the entire copper foil, The resin surface of the insulating resin sheet with copper foil was laminated on the inside, and heat pressing was performed at a pressure of 2 MPa and a temperature of 200 ° C. for 2 hours by a vacuum press to obtain a three-layer printed wiring board. The obtained three-layer printed wiring board was evaluated according to the following evaluation items. The obtained results are shown in Table 1 and FIG.

(Evaluation item)
LED light reflectance The copper foil of the three-layer printed wiring board (sample) obtained by the above method was etched on the entire surface to expose the cured insulating resin. A test piece of 100 mm × 100 mm is cut out from this three-layer printed wiring board, LED light of a predetermined wavelength is applied to the cured resin surface under normal temperature and normal pressure, and the reflectivity of the light is measured by a variable angle spectroscopic measurement system “GeMS-4 type”. (Murakami Color Research Laboratory Co., Ltd.) Tables 1 and 2 show the reflectivity of 500 nm, and FIG. 7 shows the reflectivity for each 10 nm in the wavelength range of 400 to 759 nm.

・ Glass transition temperature Two copper foils with film-like resin are laminated inside, heat-pressed for 2 hours at a pressure of 2MPa and a temperature of 200 ° C by vacuum press, and the copper foil is etched to cure the insulating resin. I got a thing. A 10 mm × 30 mm test piece was cut out from the obtained cured cured insulating resin, heated at 5 ° C./min using DMA (TA Instruments Co., Ltd.), and the peak position of tan δ was defined as the glass transition temperature. .

-Linear expansion coefficient Two copper foils with film-like resin are laminated inside, and heat pressing is performed at a pressure of 2MPa and a temperature of 220 ° C for 1 hour with a vacuum press, and the copper foil is entirely etched to cure the insulating resin. I got a thing. A 4 mm × 20 mm test piece was cut out from the obtained cured insulating resin, and the linear expansion coefficient was measured at 10 ° C./min using TMA (TA Instruments Co., Ltd.).

・ Formability Copper foil with film-like resin is applied to the front and back of the inner layer circuit board test piece having a copper foil thickness of 35 μm and a conductor pattern shape of L / S = 120/180 μm, clearance holes 1 mmφ, 3 mmφ, 2 mm slit. Heat-press molding was performed under the above-mentioned conditions, and the presence or absence of molding voids on the resin surface was visually observed after etching the entire surface of the copper foil.

-Hygroscopic solder heat resistance A 50 mm x 50 mm sample piece was cut out from the three-layer printed wiring board, and ½ copper foil on one side and the other side was etched and removed. After processing for 2 hours in a 125 ° C. pressure cooker, the copper foil surface was floated for 180 seconds in a 260 ° C. solder bath, and the presence or absence of blistering or peeling was confirmed.

(6) Elastic modulus of insulating resin material Elastic modulus (MPa) at 200 ° C. measured with a dynamic thermal analyzer (TA Instruments, DMA, 5 ° C./min).

Retention rate of storage elastic modulus Elastic modulus at 200 ° C. and elastic modulus at room temperature (25 ° C.) (b) measured by dynamic thermal analyzer (manufactured by TA Instruments, DMA, 5 ° C./min) (b ) Ratio ((a) × 100 / (b))%.

  In the manufacturing process of the three-layer printed wiring board, instead of the three-layer printed wiring board, the entire copper foil of the three-layer printed wiring board is etched to expose the cured insulating resin, and further in an air atmosphere at 170 ° C. for 3 hours. Except for the heat treatment, the same method as in Example 1 was performed to obtain a three-layer printed wiring board having a thermal history, and the same evaluation was performed. The results are shown in Table 1 and FIG.

  A resin varnish preparation process and a resin-coated metal foil manufacturing process in the same manner as in Example 1 except that the weight ratio of the first powder inorganic filler and the second powder inorganic filler is 230: 100 instead of 400: 100. And the manufacturing process of the 3 layer printed wiring board was performed, and the same evaluation was performed about the 3 layer printed wiring board. The results are shown in Table 1.

  Resin varnish preparation process and resin-coated metal foil manufacturing process in the same manner as in Example 1 except that the weight ratio of the first powder inorganic filler and the second powder inorganic filler was changed to 480: 100 instead of 400: 100. And the manufacturing process of the 3 layer printed wiring board was performed, and the same evaluation was performed about the 3 layer printed wiring board. The results are shown in Table 1.

  A resin varnish preparation process, a resin-coated metal foil manufacturing process, and a three-layer printed wiring board in the same manner as in Example 1 except that the weight ratio of cyanate resin to epoxy resin was changed to 50:50 instead of 40:60 The same evaluation was performed on the three-layer printed wiring board. The results are shown in Table 1.

Comparative Example 1
A resin varnish preparation process, a resin-coated metal foil manufacturing process, and a three-layer printed wiring board were prepared in the same manner as in Example 1 except that the second powder inorganic filler 45 wt% was used instead of the mixed filler 45 wt%. The manufacturing process was performed and the same evaluation was performed on the three-layer printed wiring board. That is, Comparative Example 1 uses only the second powder inorganic filler having a large particle size as the inorganic filler. The results are shown in Table 2.

Comparative Example 2
A resin varnish preparation step, a resin-coated metal foil manufacturing step, and a three-layer printed wiring board were prepared in the same manner as in Example 1 except that the first powder inorganic filler was 45 wt% instead of the mixed filler 45 wt%. The manufacturing process was performed and the same evaluation was performed on the three-layer printed wiring board. That is, the comparative example 2 uses only the 1st powder inorganic filler with a small particle size as an inorganic filler. The results are shown in Table 2.

Comparative Example 3
Except for omitting the use of titanium dioxide, which is a white pigment, a resin varnish preparation step, a resin-coated metal foil manufacturing step, and a three-layer printed wiring board manufacturing step are performed in the same manner as in Example 1. The same evaluation was performed on the wiring board. In the resin composition, the decrease in titanium dioxide was 100% by weight as a whole by increasing the amount of the mixed filler. The results are shown in Table 2 and FIG.

Comparative Example 4
In the manufacturing process of the three-layer printed wiring board, instead of the three-layer printed wiring board, the entire copper foil of the three-layer printed wiring board is etched to expose the cured insulating resin, and further in an air atmosphere at 170 ° C. for 3 hours. Except for the heat treatment, the same method as in Comparative Example 3 was performed to obtain a three-layer printed wiring board having received a thermal history. In Comparative Example 3, only the light reflectance was measured. The results are shown in Table 2 and FIG.

Comparative Example 5
The sheet-like glass fiber base material was impregnated with an epoxy resin and semi-cured on the front and back of an inner layer printed wiring board (halogen-free FR-4 (Sumitomo Bakelite Co., Ltd., thickness 0.2 mm)) obtained by etching the entire copper foil. One prepreg (two in total) was stacked, and heat-press molding was performed at a pressure of 2 MPa and a temperature of 200 ° C. for 2 hours by a vacuum press to obtain a printed wiring board. The obtained printed wiring board was cut into a predetermined size and used for measurement of reflectance. The results are shown in Table 2 and FIG.

  From Tables 1 and 2, in all of Examples 1 to 5, the visible light reflectance in the short wavelength region of 400 to 600 nm was about 80%. Moreover, it turns out that the reflective effect of a mixed filler is very large compared with the filler of a single particle size distribution from the comparison of Examples 1-5 and Comparative Examples 1 and 2. Moreover, it turns out that Examples 1-5 which use mixed resin of cyanate resin and an epoxy resin have the high heat resistance and high rigidity which can endure the luminescence heat of a light emitting element.

(B) is a longitudinal cross-sectional view of a resin-attached metal foil, and (A) is a diagram showing the resin composition part and the metal foil part in an easily understandable manner and separated from each other. (B) is a longitudinal cross-sectional view of a film with resin, and (A) is a diagram showing the resin composition portion and the film portion in an easily understandable manner and separated from each other. It is a schematic diagram of the printed wiring board of the 2 layer structure of this invention. It is a schematic diagram of the printed wiring board of the three-layer structure of the present invention. It is a schematic diagram of the printed wiring board of the 5 layer structure of this invention. It is a simplified diagram of an LED chip. It is a graph which shows the reflectance with respect to the light of a wavelength of 400-750 nm.

Explanation of symbols

20 Metal foil with resin 21, 21a Resin composition 22 Metal foil 30 Film with resin 23 Film 50 Two-layer printed wiring board 51, 51a Inner-layer printed wiring board 52 Conductor pattern (metal foil)
53 Cured prepreg 54 Sheet-like glass fiber substrate 60 Three-layer printed wiring board 70 Five-layer printed wiring board

Claims (7)

  A resin composition for a printed wiring board laminated on one side of a metal foil or resin film, wherein (A) a cyanate resin or a prepolymer thereof, (B) an epoxy resin, (C) a curing agent, (D ) Containing a mixed filler of a first powder inorganic filler having an average particle diameter of 0.45 to 0.55 μm and a second powder inorganic filler having an average particle diameter of 0.8 to 1.2 μm, and (E) a white pigment, Content of mixed filler (D) is 30 to 60 weight% in a resin composition, The resin composition characterized by the above-mentioned.   2. The resin composition according to claim 1, wherein the blending amount of the first powder inorganic filler is 200 to 500 parts by weight with respect to 100 parts by weight of the second powder inorganic filler.   The blending ratio ((A) :( B)) of the cyanate resin or its prepolymer (A) and the epoxy resin (B) is 60:40 to 30:70 on a weight part basis. The resin composition according to claim 1 or 2.   Metal foil with a resin composition obtained by laminating | stacking the resin composition of any one of Claims 1-3 on the one side of metal foil.   A metal foil with a resin composition according to claim 4 is superimposed on one side or both sides of an inner printed wiring board so that the resin composition is on the inside, heated and pressed to form a two-layer structure or a three-layer structure. A printed wiring board characterized in that   Two metal foils with a resin composition according to claim 4 are arranged one above the other so that the resin composition is on the inside, and the first inner layer is arranged in order from top to bottom between the two metal foils with the resin composition What is claimed is: 1. A printed wiring board, comprising: a printed wiring board, a resin composition, and a second inner layer printed wiring board including at least a three-layered body;   The printed wiring board according to claim 5, wherein a light emitting element is mounted.

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