JP5327521B2 - White prepreg, white laminate, and metal foil-clad white laminate - Google Patents

Description

  The present invention relates to a white laminated board used as a printed wiring board for mounting a light emitting diode element, a metal foil-clad white laminated board, and laminating heating and pressing to form the white laminated board and the metal foil-clad white laminated board. It relates to a white prepreg for manufacturing.

  In recent years, electronic devices have become lighter and thinner, such as mobile phones, liquid crystal televisions, and mobile games, and added value such as appearance, operability, and visibility has been demanded. For this reason, a large number of light emitters having high visual effects have been used, and light-emitting diodes (hereinafter referred to as LEDs) that are small in size and consume less power are used.

  Conventionally, bullet-type LEDs with a light-emitting part sealed with resin were mainly used. However, in recent years, chip LEDs in which elements are directly mounted on the substrate surface have been used due to the miniaturization and thinning of electronic devices. It has increased. This chip LED originally had a problem that its luminance was lower than that of a bullet-type LED, but sufficient luminance has been obtained by subsequent improvements. Since the brightness of the chip LED is improved, it is possible to use a plurality of chip LEDs on a variety of printed circuit boards as a surface light source, that is, a luminaire component. Moreover, practical use has begun for backlights for liquid crystal displays that are required to be thin, low heat generation and long life.

  Conventionally, as a printed wiring board for mounting LED chips for surface-mounted LEDs, a laminated plate obtained by heat-pressing a layer of a sheet-like glass fiber base material (prepreg) impregnated with a thermosetting resin has been used. . In particular, in order to improve the brightness of the chip LED, the reflection of the substrate surface is important, and a white one in which titanium dioxide having a high reflectance as a coloring pigment is contained in a thermosetting resin has been conventionally used. Yes.

  However, the conventional white laminates for printed wiring boards have a problem that the thermosetting resin portion is discolored by long-term use or heat during processing, and the reflectance is lowered. Especially in chip LEDs using ultraviolet light emitting elements and high-intensity blue LEDs, the substrate on which the LED chip is mounted is easily deteriorated and discolored by high-energy light such as ultraviolet rays or blue. Became unfit. In addition, the conventional white laminates for printed wiring boards have a problem in that they are colored due to heat deterioration caused by the heat generated by the LED chip, in addition to the light emitted from the LED chip. For this reason, there is an increasing demand for substrate materials that are extremely less discolored by ultraviolet rays and heat. Moreover, when mounting a chip LED, high plate thickness accuracy is also required so as not to cause problems such as liquid leakage in the sealing process of the chip LED, and a substrate having both is required.

  In order to improve such a problem, there is one using an epoxy resin containing an alicyclic epoxy resin. A certain effect can be obtained by using an alicyclic epoxy resin, but it is not always sufficient to sufficiently prevent heat resistance, deterioration or discoloration due to heat or ultraviolet rays, and a decrease in reflectance.

Here, as the curing agent used in the epoxy resin for white prepreg, in addition to primary amine (diaminodiphenylsulfone (hereinafter referred to as DDS), etc.), secondary amine, tertiary amine, acid anhydride, derivative thereof, and aromatic There are photocuring agents such as aromatic diazonium salts and aromatic sulfonium salts, dicyandiamide (hereinafter referred to as DICY), urea curing agents, organic acid hydrazide curing agents, polyamine salt curing agents, amine adduct curing agents, One or a combination of these has been used.
JP 2006-316173 A

  In view of the above, the present invention provides a white prepreg for printed wiring boards, which has heat resistance, has very little deterioration or discoloration even by heat or ultraviolet rays, and has very little reduction in reflectance, and the white prepreg is 1 It is an object of the present invention to provide a white laminated plate obtained by laminating one or more sheets and a metal foil-clad white laminated plate in which metal foils are laminated.

………式（１）
式（１）中、Ｒは、水素または炭素数１〜５の直鎖若しくは側鎖を有するアルキル基を表す。また、ｎは１から３０の整数を表す。
（５）本発明の白色プリプレグは、好ましくは前記グリシジル（メタ）アクリレート系ポリマー（Ｂ）が、グリシジル（メタ）アクリレートホモポリマーである。
（６）本発明の白色プリプレグは、好ましくは前記グリシジル（メタ）アクリレート系ポリマー（Ｂ）が、グリシジル（メタ）アクリレートとラジカル重合性モノマーとの共重合体である。
（７）本発明の白色プリプレグは、好ましくは前記白色顔料（Ｃ）が酸化亜鉛、炭酸カルシウム、二酸化チタン、アルミナ、及び合成スメクタイトから選ばれる１種類、又は２種類以上である。
（８）本発明の白色プリプレグは、好ましくは前記白色顔料（Ｃ）が二酸化チタンである。
（９）本発明の白色積層板は、好ましくは（１）〜（８）に記載の白色プリプレグ１枚、又は複数枚積層したものを加熱加圧成形してなることを特徴とする。
（１０）本発明の金属箔張り白色積層板は、好ましくは（１）〜（８）に記載の白色プリプレグ１枚、又は複数枚積層したものに、更に金属箔を積層配置したものを加熱加圧成形してなることを特徴とする。
（１１）（９）の白色積層板は、チップ型発光ダイオードを実装するためのプリント配線基板若しくはチップLEDの反射枠として使用することが好ましい。
（１２）（１０）の金属箔張り白色積層板は、好ましくはチップ型発光ダイオードを実装するためのプリント配線基板として使用する。 The white prepreg, the white laminate, and the printed wiring board of the present invention are characterized as follows in order to solve the above problems.
(1) The white prepreg of the present invention comprises an epoxy resin (A) containing an alicyclic epoxy resin (A1), a glycidyl (meth) acrylate polymer (B), a white pigment (C), and a curing agent as essential components. The resin composition (E) using only the imidazole derivative or its salt (D) as the curing agent is impregnated into a sheet-like glass fiber substrate and dried.
(2) In the white prepreg of the present invention, preferably the epoxy resin (A) containing the alicyclic epoxy resin (A1) is a glycidyl ether type such as a bisphenol diglycidyl ether type or a phenol novolak type, An epoxy resin (A2) selected from glycidylamine type and glycidyl ester type is contained in the epoxy resin (A) in an amount of 5 to 60% by weight.
(3) In the white prepreg of the present invention, the resin composition (E) is preferably (A): 20 to 85% by weight, (B); 5 to 40% by weight, (C); 10 to 75% by weight. (D); It consists of a composition ratio of 0.5 to 10 parts by weight with respect to 100 parts by weight of the epoxy resin contained in (E).
(4) The white prepreg of the present invention preferably has a structure in which the alicyclic epoxy resin (A1) is represented by the following formula (1).

......... Formula (1)
In formula (1), R represents hydrogen or an alkyl group having a linear or side chain having 1 to 5 carbon atoms. N represents an integer of 1 to 30.
(5) In the white prepreg of the present invention, the glycidyl (meth) acrylate polymer (B) is preferably a glycidyl (meth) acrylate homopolymer.
(6) In the white prepreg of the present invention, the glycidyl (meth) acrylate polymer (B) is preferably a copolymer of glycidyl (meth) acrylate and a radical polymerizable monomer.
(7) In the white prepreg of the present invention, the white pigment (C) is preferably one type or two or more types selected from zinc oxide, calcium carbonate, titanium dioxide, alumina, and synthetic smectite.
(8) In the white prepreg of the present invention, the white pigment (C) is preferably titanium dioxide.
(9) The white laminate of the present invention is preferably characterized by being formed by heating and pressing one or more of the white prepregs described in (1) to (8).
(10) Preferably, the metal foil-clad white laminate of the present invention is obtained by heating one of the white prepregs described in (1) to (8) or a laminate in which a metal foil is further laminated. It is formed by pressure forming.
(11) The white laminate of (9) is preferably used as a printed circuit board for mounting a chip type light emitting diode or a reflection frame of a chip LED.
(12) The metal foil-clad white laminate of (10) is preferably used as a printed wiring board for mounting a chip type light emitting diode.

  According to the present invention, a white prepreg for a printed wiring board, a white laminate, and a metal foil-clad white having high reflectivity in the visible light region, extremely little discoloration due to heating and ultraviolet rays, and high heat resistance and thickness accuracy. A laminate can be provided.

  In the white prepreg of the present invention, the epoxy resin (A) which is one of the constituent elements of the resin composition (E) to be impregnated into the sheet-like glass fiber substrate contains the alicyclic epoxy resin (A1). In order to obtain heat resistance, it is preferable to use a resin having a high glass transition temperature after curing among the epoxy resin (A) group. The glass transition temperature of the resin cured product may be in the range of 150 to 350 ° C.

  In general, examples of the alicyclic epoxy resin (A1) include, in addition to the cyclohexene oxide type, an epoxy resin in which an epoxy group is directly bonded to a condensate of a cyclohexane derivative (the structural formula (1)). it can.

  The alicyclic epoxy resin (A1) has a low melt viscosity, and when the prepreg is heated and pressed, there is a possibility that the flow of the resin is large and the thickness accuracy of the molded product may be deteriorated. In the white prepreg of the invention, blending other epoxy resins rather than using only the alicyclic epoxy resin (A1) as the epoxy resin (A) in the resin composition (E) to be impregnated into the sheet-like glass fiber substrate. Is preferred. Of course, it is also possible to use only the alicyclic epoxy resin (A1).

  A general-purpose epoxy resin (A2) may be added to the epoxy resin (A) of the present invention in order to improve the above problems and the manufacturing cost. That is, the ratio of the alicyclic epoxy resin (A1) in the epoxy resin (A) is reduced, and the remainder is replaced with the general-purpose epoxy resin (A2). The addition amount of the general-purpose epoxy resin (A2) may be 5 to 60% by weight in the epoxy resin (A), and preferably 30 to 50% by weight. If the addition amount with respect to an epoxy resin (A) is 60 weight% or less, the effect by using an alicyclic epoxy resin (A1) will not fall. That is, deterioration or discoloration due to heat or ultraviolet rays does not easily occur.

  General-purpose epoxy resins (A2) to be added to the epoxy resin (A) of the present invention include diglycidyl ether types of bisphenols (bisphenol A, F, or S), novolak types of phenols (phenol, cresol, etc.), There are glycidylamine type, glycidyl ester type, and the like, which are not particularly limited, but diglycidyl ether type epoxy resins of bisphenols (particularly A and F) have a good balance between cost and performance.

  In the white prepreg of the present invention, the content of the epoxy resin (A) including the alicyclic epoxy resin (A1) is preferably 20 to 85% by weight of the resin composition (E) (nonvolatile component). If it is 20% by weight or more, the above-mentioned effect can be obtained, and if it is 85% by weight or less, the prepreg is heated and pressure-molded due to the low melt viscosity of the alicyclic epoxy resin (A1). In this case, there is no possibility that the thickness accuracy is deteriorated, and there is no disadvantage in terms of cost.

  In the white prepreg of the present invention, it is necessary to add the glycidyl (meth) acrylate polymer (B) to the resin composition (E) to be impregnated into the sheet-like glass fiber substrate. As a result, the dispersibility of the pigment of the resin composition (E) and the fluidity of the resin during prepreg molding are improved. The alicyclic epoxy resin (A1) described above has a low melt viscosity, and the prepreg is heated and pressurized. It becomes possible to avoid the problem that the thickness accuracy at the time of molding deteriorates. The appearance is improved by improving the dispersibility of the pigment, and the thickness accuracy of the laminate is improved by improving the fluidity of the resin during molding.

  The glycidyl (meth) acrylate polymer (B) is preferably a glycidyl (meth) acrylate homopolymer having an epoxy equivalent of preferably about 100 to 1000 g / eq and a weight average molecular weight of 200 to 250,000. Or it is preferable in order to improve heat resistance that it is a copolymer of a glycidyl (meth) acrylate and a radically polymerizable monomer. The copolymerization ratio is preferably in the range of 5 to 75% by weight of the radical polymerizable monomer with respect to glycidyl (meth) acrylate. Moreover, as a radically polymerizable monomer which can be used conveniently, (meth) acrylate derivatives, such as styrene and methyl (meth) acrylate, cyclohexyl (meth) acrylate, etc. can be mentioned.

  The addition amount of the glycidyl (meth) acrylate polymer (B) is preferably 5 to 40% by weight in the resin composition (E). When the above-mentioned general-purpose epoxy resin (A2) is added, the glycidyl (meth) acrylate polymer (B) is added in an amount of 5% by weight or more based on the resin composition (E). Phase separation in the cured product of the cyclic epoxy resin (A1) and the general-purpose epoxy resin (A2) can be suppressed, and the addition of 10 to 20% by weight is particularly effective and preferable. Moreover, if it is 40 weight% or less, the impregnation property of the resin composition (E) to a sheet-like glass fiber base material will not worsen.

  It is necessary to add a white pigment (C) to the resin composition (E) of the present invention. Examples of the white pigment (C) to be added include zinc oxide, calcium carbonate, titanium dioxide, alumina, and synthetic smectite. The white pigment is not particularly limited as long as it is a white inorganic powder. It is most preferable to use titanium dioxide from the viewpoint of degree or electrical characteristics.

  The crystal structure of titanium dioxide includes anatase type and rutile type. When both characteristics are mentioned, the anatase type has good reflectance in the visible light short wavelength region, and the rutile type has excellent long-term durability and discoloration resistance. Either may be sufficient as the white pigment (C) added to the resin composition (E) of this invention, and it does not specifically limit. It is of course possible to use a mixture of both.

  The content of the white pigment (C) is preferably 10 to 75% by weight in the resin composition (E). If it is 10% by weight or more, sufficient whiteness and reflectance can be obtained, and if it is 75% by weight or less, the impregnation property to the sheet-like glass fiber substrate is lowered or the adhesive strength to the metal foil is lowered. There will be no problems.

  When titanium dioxide is used as the white pigment (C), the titanium dioxide may be treated with alumina, silica, zirconia or the like as a surface treatment. Moreover, a silane coupling agent or titanate coupling agent treatment is also possible.

  The resin composition (E) to be impregnated into the sheet-like glass fiber substrate may contain an inorganic filler such as silica as necessary. Examples of the inorganic filler that can be contained include silica, aluminum hydroxide, magnesium hydroxide, E glass powder, magnesium oxide, potassium titanate, calcium silicate, clay, and talc. Two or more types may be used in combination. By containing these inorganic fillers, the rigidity of the substrate is improved. The blending amount is not particularly limited, but is preferably 50% by weight or less based on the resin composition (E). If it is 50% by weight or less, there is almost no possibility that the impregnation property of the sheet-like glass fiber substrate is lowered or the adhesive strength with the metal foil is lowered.

  In addition to the inorganic filler, the resin composition (E) to be impregnated into the sheet-like glass fiber substrate can be mixed with a fluorescent agent as necessary. By blending the fluorescent agent, the apparent reflectance in the visible light short wavelength region can be increased. Here, the fluorescent agent is a compound that has the property of absorbing light energy such as light, radiation, and ultraviolet light, and radiating it by changing to light of other wavelengths. , Diaminostilbene disulfonic acid derivatives, imidazole derivatives, coumarin derivatives, pyrazoline derivatives, decalylamine derivatives, and the like. Examples of inorganic substances include ZnCdS: Ag, ZnS: Pb, and ZnS: Cu. The fluorescent agent preferably has a radiation wavelength in the visible light short wavelength region (380 to 470 nm) in which the reflectance is remarkably lowered, and among the above fluorescent agents, it is generally called a fluorescent whitening agent. Diaminostilbene disulfonic acid derivatives, imidazole derivatives, coumarin derivatives, pyrazoline derivatives and the like are suitable. The addition amount is not limited, but in the case of a pyrazoline derivative, the effect is exerted from the addition of about 0.1% by weight with respect to the resin composition (E), and the effect increases as the addition amount increases. . Further, it is desirable that the optical brightener to be added is soluble in an organic solvent.

  For the white prepreg, white laminate and printed wiring board of the present invention, only an imidazole derivative or a salt thereof (D) is used as a curing agent. By not containing curing agents other than imidazole derivatives or their salts, white prepregs, white laminates and printed wiring boards are obtained that have high heat resistance, are hardly deteriorated or discolored by heat or ultraviolet rays, and are extremely low in reflectance. be able to.

  Examples of the imidazole derivatives used in the present invention include 2-methylimidazole, 2-ethyl-4methylimidazole, 2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole, 2-phenyl-4-methylimidazole, 2- Examples include phenyl-4,5-dihydroxymethylimidazole and 2-phenyl-4-methyl-5-hydroxymethylimidazole.

  In addition, those in which any organic functional group is bonded to the nitrogen atom at the 1-position can be selected, for example, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl 2-undecylimidazole, 1-cyanoethyl-2-phenylimidazole, 2,4-diamino-6- [2′-ethyl-4′methylimidazolyl- (1 ′)]-ethyl-s-triazine, and the like. .

  Examples of the salt of the imidazole derivative used in the present invention include 1-cyanoethyl-2-undecylimidazolium trimellitate-2-phenylimidazole isocyanuric acid adduct, 2,4-diamino-6- [2′-ethyl. -4'methylimidazolyl- (1 ')]-ethyl-s-triazine isocyanuric acid adduct and the like.

  Although the compounding quantity of an imidazole derivative or its salt (D) changes with kinds of the imidazole derivative or its salt to mix | blend, (A) + (B) in the resin composition (E) used for the white prepreg of this invention. The blending ratio of the curing agent (D) to is preferably a blending amount of 0.5 to 10 parts by weight with respect to 100 parts by weight of the epoxy resins. If the amount is less than 0.5 parts by weight, the epoxy resins cannot be sufficiently solidified. If the amount exceeds 10 parts by weight, the epoxy resin is colored or the epoxy resin is heated by self-reaction heat during the hot press molding. The resin composition may be burnt.

  As a sheet-like glass fiber base material used for the white prepreg of the present invention, either a glass cloth or a nonwoven fabric may be used, and a glass cloth and a nonwoven fabric may be used in combination. In the case of a glass cloth, a plain weave structure is basically used, but a woven structure such as Nanako weave, satin weave or twill weave may be used, and is not particularly limited. In order not to impair the appearance and workability, it is preferable to use a woven structure in which the gap between the intersections of the warp and the weft is small. Although there is no restriction | limiting in particular about the thickness of a glass cloth, The thing of the range of 0.02-0.3 mm is easy to handle and preferable.

  Moreover, you may perform surface treatment by a silane coupling agent etc. to a sheet-like glass fiber base material. Furthermore, the sheet-like glass fiber base material itself may be colored white.

  A solvent such as methyl ethyl ketone is added to the resin composition described above to prepare a resin varnish, impregnated into a sheet-like glass fiber substrate made of glass cloth or the like, and dried to produce the white prepreg of the present invention. The method of impregnating and drying the resin composition into the sheet-like glass fiber substrate is not particularly limited. For example, after impregnating the sheet-like glass fiber substrate into the resin composition by impregnation, the method is 100. For example, a method of removing the solvent and semi-curing the epoxy resin by heating at a temperature of about from ℃ to 180 ℃ can be employed. The amount of the resin composition impregnated in the white prepreg produced by impregnating and drying the sheet-like glass fiber substrate is not particularly limited, but is preferably 30 to 60% by weight based on the glass cloth fiber substrate.

  One white prepreg or a laminate of the obtained white prepregs is heated and pressed to produce the white laminate of the present invention. Further, a metal foil-clad white laminate of the present invention is manufactured by further arranging and arranging a metal foil on the obtained white prepreg or a laminate of a plurality of white prepregs, and heating and pressing. The number of prepregs to be stacked is not particularly limited, but as a single-layer substrate, 1 or 2 to 10 white prepregs are stacked. It is common to arrange. As the metal foil, copper foil, aluminum foil or the like is used. The thickness of the metal foil is generally 3 μm to 105 μm, and particularly preferably 9 μm to 35 μm. It is also possible to use only the surface layer on which the white prepreg of the present invention is laminated, and use the prepreg of the prior art for the intermediate layer. The white laminate and the metal foil-clad white laminate of the present invention thus obtained have high reflectivity in the visible light region, extremely little discoloration due to heating and ultraviolet rays, and have high heat resistance. The white laminate for printed wiring boards and the white laminate with metal foil are excellent.

  A conductive pattern is formed on the obtained white laminate by an additive method to obtain a printed wiring board. Moreover, a circuit pattern is printed on the metal foil of the obtained metal foil-clad white laminate and etched to obtain a printed wiring board. In order to mount the chip LED on the printed wiring board, first, solder is applied on the printed wiring board, and the chip LED is placed on the printed wiring board, and then the chip LED is melted by passing it through reflow or the like. Is fixed to the printed circuit board. By integrating chip LEDs with high density, it can be used as a surface light source, and such a surface light source is suitably used for a backlight for a liquid crystal display that is particularly required to be thin. In addition, it is applied to induction display illumination lamps, evacuation exit illumination lamps, advertisement lights, etc. as surface emitting illumination devices.

  The thickness accuracy of the chip LED mounting substrate is extremely important when the elements mounted on the substrate are sealed by transfer molding. Here, transfer molding refers to a method of press-fitting a resin into a clamped mold. The thickness of the substrate used for the chip LED is generally 0.06 mm to 1.0 mm. However, if the accuracy of the plate thickness is poor, there is a gap between the substrate and the mold at the time of clamping during transfer molding. And the press-fitted resin leaks from the gap, resulting in molding defects. The required accuracy of the substrate thickness in such transfer molding is, for example, a tolerance of ± 0.05 mm or less (range is 0.1 mm), preferably a tolerance of ± 0.03 mm or less for a substrate having a thickness of 1.0 mm. (The range is 0.06 mm). Therefore, if there is a substrate with high thickness accuracy, the defect rate can be greatly reduced in the manufacturing process of the chip LED, which is extremely significant in the industry.

  Next, contents and effects of the present invention will be described with reference to examples, but the present invention is not limited to the following examples without departing from the gist thereof.

[Example 1]
Alicyclic epoxy resin: 50 parts by weight of EHPE-3150 (manufactured by Daicel Chemical Industries), bisphenol A type epoxy resin: 40 parts by weight of AER-6051 (manufactured by Asahi Kasei Kogyo Co., Ltd.), and glycidyl methacrylate copolymer: Marproof 10 parts by weight of G-0150M (manufactured by NOF Corporation) and 2.0 parts by weight of 2E4MZ-CN (manufactured by Shikoku Kasei Kogyo Co., Ltd., 1-cyanoethyl-2-ethyl-4-methylimidazole) as an imidazole derivative It was dissolved in 100 parts by weight of methyl ethyl ketone (hereinafter referred to as MEK). Thereto, 73 parts by weight of rutile titanium dioxide R-21 (manufactured by Sakai Chemical Industry Co., Ltd.) was added as a white pigment, and stirred at room temperature for 1 hour to obtain a white epoxy varnish.
This white epoxy varnish was impregnated into 0.1 mm thick glass cloth WEA-116E (manufactured by Nittobo Co., Ltd.) and pre-dried at 140 ° C. for 5 minutes to obtain a prepreg having a resin composition content of 50%. Four or ten prepregs are laminated, and 18 μm thick copper foil is stacked on the top and bottom of the prepreg, and heated and pressed at a pressure of 20 kgf / cm ² and a temperature of 200 ° C., 0.4 mm thickness and 1 mm Thick copper foil-clad white laminates were obtained.

[Comparative Example 1]
A white laminate was obtained in the same manner as in Example 1 except that the composition of the white epoxy varnish was changed as follows.
Alicyclic epoxy resin: 50 parts by weight of EHPE-3150 (manufactured by Daicel Chemical Industries), bisphenol A type epoxy resin: 40 parts by weight of AER-6051 (manufactured by Asahi Kasei Kogyo Co., Ltd.), and glycidyl methacrylate copolymer: Marproof 10 parts by weight of G-0150M (manufactured by NOF Corporation) was dissolved in 75 parts by weight of methyl ethyl ketone (hereinafter referred to as MEK). ... (Varnish A)
3 parts by weight of DICY as a curing agent, 0.1 part by weight of C11Z-CN (manufactured by Shikoku Kasei Kogyo Co., Ltd., 1-cyanoethyl-2-undecylimidazole) as a curing accelerator, 25 parts by weight of dimethylformamide (hereinafter referred to as DMF) Dissolved in. ... (Varnish B)
Varnish A and varnish B were mixed, and 73 parts by weight of rutile titanium dioxide R-21 (manufactured by Sakai Chemical Industry Co., Ltd.) was added as a white pigment and stirred at room temperature for 1 hour to obtain a white epoxy varnish.

[Effectiveness confirmation test]
1) Heat discoloration resistance After removing the copper foil of the 0.4 mm copper foil-clad white laminate obtained in Example 1 and Comparative Example 1 by etching treatment, the visible light reflectance of the substrate surface was changed. The spectral reflectance after measurement with CM-3600d manufactured by Konica Minolta and further heat treatment at 200 ° C. for 4 hours was also measured.
The results are shown in FIG. As is clear from FIG. 1, the substrate of Example 1 is less deteriorated in the short wavelength region than the substrates of Comparative Example 1 and Comparative Example 2, and it can be seen that the heat resistance is greatly improved.

2) Ultraviolet resistance After removing the copper foil of the 0.4 mm thick copper foil-clad white laminate obtained in Example 1 and Comparative Example 1 by etching, the spectral reflectance of the substrate surface was measured, and Visible after irradiation with 5600 W of high-pressure mercury lamp (ultraviolet light emission spectrum: 253.7 nm, 365 nm) on the substrate at an irradiation distance of 15 cm (irradiation intensity = about ² kW / m ² , 30 seconds per time) 500 times. The light reflectance was measured in the same manner.
The results are shown in FIG. As is apparent from FIG. 2, it can be seen that the substrate of Example 1 clearly has a lower degree of decrease in reflectance and the ultraviolet resistance is significantly improved as compared with the substrate of Comparative Example 1.

3) Glass transition temperature The glass transition temperature was determined according to JIS-C6481. That is, after removing the copper foil of the 0.4 mm-thick metal foil-clad white laminate obtained in Example 1 and Comparative Example 1 by etching, it was cut into a size of 7 mm × 70 mm, and a viscoelasticity measuring device (SII) The glass transition temperature was determined from the peak temperature of the loss tangent of the measurement data using an EXSTER-6000) and a temperature increase rate of 2 ° C./min and a frequency of 10 Hz.
The glass transition temperatures of the white laminates of Example 1 and Comparative Example 1 (after removal of the metal foil) were 210 ° C. and 210 ° C., respectively. From these results, the white laminates of Example 1 and Comparative Example 1 have practically sufficient heat resistance.

  As described above, according to the present invention, a white prepreg for a printed wiring board, a white laminate, and a metal having high reflectivity in the visible light region, remarkably little discoloration due to heating or ultraviolet rays, and high heat resistance. It is possible to provide a foil-laminated white laminate and contribute greatly to the industry.

Comparison of visible light reflectance after heat treatment at 200 ° C. for 4 hours. Comparison of visible light reflectance after irradiation with high pressure mercury lamp (5600 W) light (ultraviolet part main emission wavelengths: 253.7 nm and 365 nm, irradiation intensity: about 2 kW / m ² ) 500 times.

Claims (12)

  An epoxy resin (A) containing an alicyclic epoxy resin (A1), a glycidyl (meth) acrylate polymer (B), a white pigment (C), and a curing agent are essential components, and an imidazole derivative or a salt thereof as the curing agent A white prepreg obtained by impregnating a sheet-like glass fiber base material with the resin composition (E) using only (D) and drying it.   The epoxy resin (A) including the alicyclic epoxy resin (A1) is a general-purpose epoxy resin (A2) selected from bisphenol diglycidyl ether type, phenol novolak type, glycidyl amine type, and glycidyl ester type. The white prepreg according to claim 1, wherein the epoxy resin (A) is contained in an amount of 5 to 60 wt%. Epoxy contained in the resin composition (E) in (A); 20 to 85% by weight, (B); 5 to 40% by weight, (C); 10 to 75% by weight, (D); (E) The white prepreg according to claim 1, comprising a composition ratio of 0.5 to 10 parts by weight with respect to 100 parts by weight of the resin. The white prepreg according to claim 1, wherein the alicyclic epoxy resin (A1) has a structure represented by the following formula (1).

...... Formula (1)
In formula (1), R represents hydrogen or an alkyl group having a linear or side chain having 1 to 5 carbon atoms. N represents an integer of 1 to 30. The white prepreg according to any one of claims 1 to 4, wherein the glycidyl (meth) acrylate polymer (B) is a glycidyl (meth) acrylate homopolymer. The white prepreg according to any one of claims 1 to 4, wherein the glycidyl (meth) acrylate polymer (B) is a copolymer of glycidyl (meth) acrylate and a radical polymerizable monomer. . The said white pigment (C) is 1 type chosen from a zinc oxide, a calcium carbonate, titanium dioxide, an alumina, and a synthetic smectite, or 2 or more types, The any one of Claims 1 thru | or 6 characterized by the above-mentioned. White prepreg.   The white prepreg according to any one of claims 1 to 6, wherein the white pigment (C) is titanium dioxide. A white laminated board obtained by heat-pressing one or more of the white prepregs according to any one of claims 1 to 8.   Metal foil tension characterized by being formed by heating and press-molding a white prepreg according to any one of claims 1 to 8 or a laminate of a plurality of metal foils. White laminate. A printed wiring board for mounting a chip type light emitting diode using the white laminated board according to claim 9. A printed wiring board for mounting a chip-type light-emitting diode using the metal foil-clad white laminate according to claim 10.

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