JP4797248B2 - Pre-preg for printed wiring board and laminated board using the same - Google Patents

Description

【００３２】
プリプレグの保存安定性は、４０℃保管条件によるゲルタイム減少率を測定し、また、樹脂流れは、ＪＩＳ−Ｃ−６５２１に準拠して測定した。積層板の成形性は、板厚と基材面外観を評価した。板厚は、５０点の板厚測定を行なって標準偏差を算出し、また、基材面外観は、銅箔を全面エッチングして除去し、ボイドやカスレの有無を評価した。Ｔｇは、熱分析法（Thermal Mechanical Analysis：ＴＭＡ）を用いて、ＪＩＳ−Ｃ−６４８１に準拠して測定した。耐熱性は、表面の銅箔をエッチングで除去し、１２０℃、２気圧の水蒸気中（ＰＣＴ：Pressure Cooker Test）で所定時間処理後、２６０℃のはんだ槽に２０秒間浸漬させ、ミーズリングやフクレの有無について目視にて評価した。評価基準は、○は異常なし、△はミーズリング発生あり、×はフクレの発生ありとした。
【００３３】
表１の結果より明らかなように、本発明の樹脂組成物である実施例１、２は、ゲルタイム減少率が小さくプリプレグ保存性に優れ、樹脂流れ、成形性、Ｔｇ、はんだ耐熱性が優れる。一方、イソシアネート変性エポキシ樹脂と無機充填剤をともに含有しない比較例１は、プリプレグ保存性が著しく低下し、Ｔｇが低く、はんだ耐熱性もＰＣＴ５時間処理で一部にミーズリングが発生し、６時間処理ですべてフクレが発生した。また、イソシアネート変性エポキシ樹脂を含有するが無機充填剤を含有しない比較例２、３は、比較例１よりはＴｇ、耐熱性が改善されているが、樹脂流れが著しく低下し、板厚偏差の低下、ボイドやカスレの発生が認められる。
【００３４】
【発明の効果】
本発明によれば、エポキシ樹脂の分子構造中に芳香族ジイソシアネートで変性されているエポキシ樹脂と、硬化剤と、硬化促進剤と、無機充填剤と、を必須成分として含有するワニスを使用することで、保存安定性に優れたプリプレグおよび成形性、耐熱性およびＴｇを向上させた積層板を得ることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a printed wiring board prepreg used as an electrical insulating material such as a printed wiring board, and a laminate using the same. In particular, the present invention relates to a printed wiring board prepreg excellent in storage stability and moldability, and a laminate excellent in moldability, heat resistance, and glass transition temperature (hereinafter referred to as “Tg”) characteristics.
[0002]
[Prior art]
For example, a metal-clad laminate used in electrical / electronic equipment is impregnated with a thermosetting resin varnish such as an epoxy resin composition on a substrate such as a glass cloth, and then heated and semi-cured (B stage state) ) Prepare a prepreg, then stack the required number of prepregs, and stack metal foil such as copper foil on one or both sides, and heat and press the laminate to form. ing. In addition, the multilayer metal-clad laminate is formed by etching the metal foil on the surface of the laminate obtained by the above method to form a conductor circuit, and on the front and back surfaces of the laminate on which the conductor circuit is formed, as described above. In addition, it is manufactured by stacking a required number of prepregs, laminating metal foils on one side or both sides thereof, and heating and pressurizing the laminated body.
[0003]
Generally, an epoxy resin having two or more epoxy groups, an amine curing agent, and a curing accelerator are used in the epoxy resin composition used for the prepreg for a printed wiring board.
[0004]
In recent years, with the increase in density, thickness, and high-speed transmission of printed wiring boards, printed wiring board materials are required to be improved in moldability, heat resistance, and Tg. For this reason, prepregs used for multilayer printed wiring boards are also required to have good moldability, high heat resistance, high Tg, and excellent storage stability.
[0005]
In response to such a demand, for example, JP-A-5-43655 discloses an invention of a resin composition containing an epoxy compound containing an isocyanate compound, a halogenated glycidyl compound and a non-halogenated glycidyl compound, and a curing agent. ing. The same publication describes that this resin composition is excellent in flame retardancy, heat resistance, storage stability, and uniformity of curing. However, the reactivity of this isocyanate-modified epoxy resin is slower than that of the conventional bifunctional epoxy resin. Therefore, when the curing agent is the same amount as the conventional epoxy resin, the blending amount of the curing accelerator is 1. It was necessary to increase it to about 5 times, and the resin flow became large at the time of press molding, and molding was difficult.
[0006]
[Problems to be solved by the invention]
The present invention provides a prepreg for a printed wiring board having excellent storage stability and moldability, and a resin composition for prepreg that can obtain a laminate having excellent moldability, heat resistance, and Tg. It aims at providing the prepreg for printed wiring boards, and a laminated board.
[0007]
[Means for Solving the Problems]
The present invention relates to a glass woven fabric or glass comprising a varnish containing an aromatic diisocyanate-modified epoxy resin modified with an aromatic diisocyanate in the molecular structure of the epoxy resin, a curing agent, a curing accelerator, and an inorganic filler. It is a prepreg for a printed wiring board that is impregnated into a nonwoven fabric and heated to be a B-stage. Moreover, at least 5 wt% of the aromatic diisocyanate-modified epoxy resin, 1 to 5 wt% of the curing agent, 0.1 to 1 wt% of the curing accelerator, and 5 to 50 wt% of the inorganic filler with respect to the total amount of the epoxy resin. % Is impregnated into a glass woven fabric or a glass nonwoven fabric and heated to be a B-stage prepreg for a printed wiring board. Furthermore, the present invention is a printed wiring board prepreg in which the gel time reduction rate during storage at 40 ° C. for 30 days is 20% or less and the resin flow is 15% or less.
[0008]
In this way, the present invention, surprisingly, in the aromatic diisocyanate-modified epoxy resin having a slow reaction, particularly by adding the aromatic diisocyanate-modified epoxy resin and the inorganic filler at the same time, It has been found that even if the amount is the same as that of the epoxy resin, the resin flow can be suppressed and a prepreg excellent in moldability can be obtained, and this is applied to a prepreg for a printed wiring board.
[0009]
The present invention is further a metal-clad laminate in which a metal foil is laminated on one side or both sides of these prepregs.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The aromatic diisocyanate-modified epoxy resin used in the present invention is not particularly limited as long as an epoxy resin having at least two epoxy groups in the molecule is modified with aromatic diisocyanate. Isocyanate-modified epoxy resin may be used. For example, as an aromatic diisocyanate-modified epoxy resin, trade name ARALDITE AER 4152 manufactured by Asahi Kasei Epoxy Co., Ltd. can be exemplified, and as a brominated isocyanate-modified epoxy resin, trade name ARALDITE AER 4100 manufactured by the same company can be exemplified. Moreover, this isocyanate-modified epoxy resin and an unmodified epoxy resin having two or more epoxy groups can be mixed and used. In this case, when the isocyanate-modified epoxy resin is contained at least 5% by weight, preferably at least 10% by weight, based on the total amount of the epoxy resin, the object of the present invention can be achieved.
[0011]
Examples of the epoxy resin curing agent used in the present invention include amines, phenols, acid anhydrides and the like, but are not particularly limited as long as they are usually used for electrically insulating varnishes. Examples of amines include diethylamine, diethylenetriamine, triethylenetetramine, diethylaminopropylamine, aminoethylpiperazine, mensendiamine, metaxylylenediamine, dicyandiamide, diaminodiphenylmethane, diaminodiphenylsulfone, methylenedianiline, metaphenylenediamine, and the like. . Of these, dicyandiamide is preferable in terms of heat resistance and storage stability in the B-stage state. Examples of the phenols include biphenol, bisphenol A, bisphenol F, phenol novolak, cresol novolak, bisphenol A novolak, halides thereof, and alkyl group-substituted products. Of these, bisphenol A novolak is preferable in terms of Tg. Acid anhydrides include hexahydrophthalic anhydride (HPA), tetrahydrophthalic anhydride (THPA), pyromellitic anhydride (PMDA), chlorendic anhydride (HET), nadic anhydride (NA), and methyl nadic anhydride (MNA), dodecynyl succinic anhydride (DDSA), phthalic anhydride (PA), methylhexahydrophthalic anhydride (MeHPA), maleic anhydride and the like. Of these, chlorendic anhydride (HET) is preferable in terms of heat resistance and flame retardancy.
[0012]
These curing agents may be of one type, or two or more types of curing agents can be mixed and used. Moreover, 1-5 weight part is preferable with respect to 100 weight part of epoxy resins, and, as for content of a hardening | curing agent, 2-4 weight part is more preferable.
[0013]
As the curing accelerator used in the present invention, an imidazole compound, an organic phosphorus compound, a tertiary amine, a quaternary ammonium salt, or the like can be used. Among them, it is preferable to use an imidazole compound in which a secondary amino group is masked with acrylonitrile, isocyanate, melamine, acrylate, or the like, because a prepreg with better storage stability can be obtained. Examples of imidazole compounds include imidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 1-benzyl-2-methylimidazole, 2-heptadecylimidazole, 4, 5 -Diphenylimidazole, 2-methylimidazoline, 2-ethyl-4-methylimidazoline, 2-phenylimidazoline, 2-undecylimidazoline, 2-heptadecylimidazoline, 2-isopropylimidazole, 2,4-dimethylimidazole, 2-phenyl Examples include -4-methylimidazole, 2-methylimidazoline, 2-isopropylimidazoline, 2,4-dimethylimidazoline, 2-phenyl-4-methylimidazoline. Of these, 2-ethyl-4-methylimidazole is preferable in terms of Tg, heat resistance, and reactivity. Examples of the masking agent include acrylonitrile, phenylene diisocyanate, toluene diisocyanate, naphthalene diisocyanate, hexamethylene diisocyanate, methylene bisphenyl isocyanate, and melamine acrylate.
[0014]
These curing accelerators can be used alone, or two or more curing accelerators can be used in combination. Moreover, 0.1-1 weight part is preferable with respect to 100 weight part of epoxy resins, and, as for content of a hardening accelerator, 0.2-0.5 weight part is more preferable.
[0015]
The inorganic filler used in the present invention is not particularly limited as long as the resin flow of the prepreg can be suppressed. For example, aluminum hydroxide, silica, talc, wollastonite, magnesium hydroxide, clay and the like can be used, and talc having a large resin flow suppressing effect and excellent workability is particularly preferable. Further, two or more kinds of inorganic fillers can be used in combination according to the properties of the laminated board.
[0016]
The content of the inorganic filler is preferably 5 to 50 parts by weight and more preferably 10 to 20 parts by weight with respect to 100 parts by weight of the epoxy resin from the viewpoint of workability and workability by suppressing the resin flow of the prepreg. Furthermore, the average particle diameter of the inorganic filler is preferably 2 to 20 μm and more preferably 3 to 10 μm from the viewpoint of the viscosity of the varnish and the coatability.
[0017]
The above-mentioned isocyanate-modified epoxy resin, curing agent, curing accelerator and inorganic filler are essential components for the prepreg for printed wiring board of the present invention. In particular, when an epoxy resin including an isocyanate-modified epoxy resin is used, the role played by the inorganic filler is large. That is, in a resin composition containing only an isocyanate-modified epoxy resin, a curing agent, and a curing accelerator without containing an inorganic filler, the reaction is slow because the epoxy resin is modified with diisocyanate. When the amount of the curing accelerator in the case of using an epoxy resin is blended, the gel time of the varnish becomes longer and the production efficiency is lowered. As a solution to this, it is possible to shorten the gel time of the varnish and efficiently produce a prepreg by adding a larger amount of the curing accelerator than in the case of a normal epoxy resin. In this case, the resin flow during press molding increases, and the plate thickness and moldability deteriorate. On the other hand, when an inorganic filler is blended, the resin flow can be suppressed and a prepreg excellent in moldability can be obtained even if the curing accelerator is blended in the same amount as that of a normal epoxy resin.
[0018]
Moreover, in this invention, additives, such as a coloring agent, antioxidant, a reducing agent, and an ultraviolet opaque agent, can also be added as needed.
[0019]
As a solvent for varnishing the resin composition of the present invention, methyl ethyl ketone, acetone, methyl isobutyl ketone, 2-ethoxyethanol, toluene, butyl cellosolve, methanol, ethanol, 2-methoxyethanol, etc. having a relatively low boiling point are used. Is preferred.
[0020]
The production of the varnish can be carried out using a rough machine, a three-roller, a bead mill or the like, or a combination thereof. In addition, after forming the varnish, it is preferable to remove bubbles in the varnish by vacuum degassing.
[0021]
The prepreg is a glass woven fabric or glass nonwoven fabric obtained by blending the epoxy resin varnish obtained by blending the above-mentioned isocyanate-modified epoxy resin, curing agent, curing accelerator, inorganic filler, and additives to be added if necessary in a solvent. It can be obtained by impregnating and drying. The kind of glass woven fabric or glass nonwoven fabric to be used is not particularly limited, and a glass woven fabric having a thickness of 0.02 to 0.4 mm can be used according to the thickness of the target prepreg or laminate. The drying conditions for producing the prepreg can be appropriately selected between a drying temperature of 80 to 200 ° C. and a drying time of 1 to 30 minutes.
[0022]
The prepreg produced by the above method is laminated according to the thickness of the target laminate, and a metal foil is laminated on one side or both sides thereof, and heated and pressed to produce a laminate. As the metal foil, copper foil or aluminum foil can be used, but other metal foils can also be used. The thickness of the metal foil is usually 5 to 200 μm.
[0023]
The heating temperature at the time of laminate production is 150 to 190 ° C, more preferably 160 to 180 ° C, and the pressure is 1 to 8 MPa, more preferably 1 to 4 MPa. These conditions can be determined by the characteristics of the prepreg, the capacity of the press, the thickness of the target laminate, and the like.
[0024]
【Example】
Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited thereto. In the following, “part” means “part by weight”.
[0025]
(Example 1)
90 parts of brominated bisphenol A type epoxy resin (epoxy equivalent 480, Br content 22%)
Isocyanate-modified epoxy resin (Asahi Kasei Co., Ltd.) 10 parts (epoxy equivalent 335)
Dicyandiamide 2.7 parts 2-ethyl-4-methylimidazole 0.3 parts talc (manufactured by Takehara Chemical Co., Ltd., average particle size 7 μm) 10 parts per 100 parts of resin The above resin composition was dissolved in methyl ethyl ketone, A varnish having a nonvolatile content of 65% was prepared. This varnish was impregnated into a glass woven fabric (thickness 0.2 mm, basis weight 210 g / m ² ) so that the resin content was 45% and dried to obtain a prepreg. Four prepregs were stacked, and a copper foil with a thickness of 18 μm was placed on both sides of the prepreg, and press molding was performed at 170 ° C. for 90 minutes at 4 MPa to obtain a FR-4 grade laminate having a thickness of 0.8 mm. .
[0026]
(Example 2)
Brominated isocyanate-modified epoxy resin (Asahi Kasei Corporation) 100 parts (epoxy equivalent 345, Br content 21%)
Dicyandiamide 2.9 parts 2-ethyl-4-methylimidazole 0.3 parts talc (same as above) 10 parts per 100 parts of resin Using the above resin composition, a prepreg having the same gel time as in Example 1 To obtain a FR-4 grade laminate having a thickness of 0.8 mm.
[0027]
(Comparative Example 1)
Brominated bisphenol A type epoxy resin 100 parts (epoxy equivalent 480, Br content 22%)
Dicyandiamide 2.6 parts 2-ethyl-4-methylimidazole 0.2 parts Using the above resin composition, a prepreg having the same gel time as in Example 1 was prepared, and FR-4 having a thickness of 0.8 mm A graded laminate was obtained.
[0028]
(Comparative Example 2)
90 parts of brominated bisphenol A type epoxy resin (epoxy equivalent 480, Br content 22%)
Isocyanate-modified epoxy resin (Asahi Kasei Corporation) 10 parts (epoxy equivalent 335)
Dicyandiamide 2.7 parts 2-ethyl-4-methylimidazole 0.3 parts Using the above resin composition, a prepreg having the same gel time as in Example 1 was prepared, and FR-4 having a thickness of 0.8 mm A graded laminate was obtained.
[0029]
(Comparative Example 3)
Brominated isocyanate-modified epoxy resin (Asahi Kasei Corporation) 100 parts (epoxy equivalent 345, Br content 21%)
Dicyandiamide 2.9 parts 2-Ethyl-4-methylimidazole 0.3 parts Using the above resin composition, a prepreg having the same gel time as in Example 1 was prepared, and FR-4 having a thickness of 0.8 mm A graded laminate was obtained.
[0030]
The prepregs obtained in Examples 1 and 2 and Comparative Examples 1, 2, and 3 were evaluated for storage stability and resin flow. Moreover, the moldability, Tg, and heat resistance were evaluated about the laminated board using this prepreg. The results are shown in Table 1.
[0031]
[Table 1]

[0032]
The storage stability of the prepreg was measured by the gel time reduction rate under storage conditions at 40 ° C., and the resin flow was measured according to JIS-C-6521. The moldability of the laminated plate was evaluated on the plate thickness and the substrate surface appearance. The plate thickness was measured by measuring the plate thickness at 50 points, and the standard deviation was calculated. In addition, the appearance of the substrate surface was evaluated by checking the presence or absence of voids and scum by removing the entire copper foil by etching. Tg was measured according to JIS-C-6481 using a thermal analysis method (Thermal Mechanical Analysis: TMA). For heat resistance, the copper foil on the surface is removed by etching, treated in water vapor at 120 ° C. and 2 atm (PCT: Pressure Cooker Test) for a predetermined time, then immersed in a solder bath at 260 ° C. for 20 seconds, and then subjected to measling and swelling. The presence or absence of was evaluated visually. The evaluation criteria are as follows: ○ indicates no abnormality, Δ indicates occurrence of mising, and × indicates occurrence of swelling.
[0033]
As is clear from the results in Table 1, Examples 1 and 2, which are resin compositions of the present invention, have a small gel time reduction rate and excellent prepreg storage, and excellent resin flow, moldability, Tg, and solder heat resistance. On the other hand, Comparative Example 1 containing neither an isocyanate-modified epoxy resin nor an inorganic filler has a significantly reduced prepreg storage stability, a low Tg, and a soldering heat resistance that is partly mesling after PCT for 5 hours. There was a bulge in the process. Further, Comparative Examples 2 and 3 containing an isocyanate-modified epoxy resin but not containing an inorganic filler have improved Tg and heat resistance as compared with Comparative Example 1, but the resin flow is remarkably lowered and the plate thickness deviation is reduced. Decrease, generation of voids and blurring are observed.
[0034]
【The invention's effect】
According to the present invention, the use of a varnish containing, as essential components, an epoxy resin modified with an aromatic diisocyanate in the molecular structure of the epoxy resin, a curing agent, a curing accelerator, and an inorganic filler. Thus, a prepreg having excellent storage stability and a laminate having improved moldability, heat resistance and Tg can be obtained.

Claims (2)

Varnish containing 2 to 4 parts by weight of dicyandiamide , 0.2 to 0.5 parts by weight of imidazole compound , and 10 to 20 parts by weight of talc with respect to 100 parts by weight of epoxy resin containing at least 5% by weight of an aromatic diisocyanate-modified epoxy resin A prepreg for a printed wiring board, which is impregnated into a glass woven fabric or a glass nonwoven fabric, heated, and made into a B-stage.   A metal-clad laminate in which a metal foil is laminated on one side or both sides of the prepreg according to claim 1.