JPH09176345A - Production of prepreg - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a prepreg extremely little in the dusting of resin powder, etc., and useful for printed circuit boards, etc., by impregnating an epoxy resin varnish containing a specific composition as essential components into a fibrous substrate and subsequently drying the impregnated varnish. SOLUTION: An epoxy resin varnish containing (A) a linear polymeric epoxy resin having an epoxy equivalent of 1,500-4,000 and terminated with two functional groups preferably in an amount of >=50wt.%, (B) a guanide compound (preferably 1,3-diphenylguanidine, diorthotolylguanidine, 1-orthotolyldiguanide), and (C) a curing accelerator (preferably an imidazole or phosphine curing accelerator) as essential components is impregnated into a fibrous substrate and subsequently dried. The prepreg preferably contains a novolak epoxy resin in an amount of 10-40wt.% based on the whole epoxy resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a prepreg in which dust generation due to resin powder or the like is extremely small, and which eliminates the need for the remelting treatment of the prepreg which is conventionally performed to prevent dust generation. The present invention relates to a manufacturing method of.

[0002]

2. Description of the Related Art Epoxy resin laminates for printed circuits are:
Generally, one or more prepregs obtained by applying and drying an epoxy resin on a fiber base material are laminated, and a metal foil is laminated on the upper surface thereof, followed by heat and pressure molding. Also,
The method of manufacturing a multilayer printed wiring board is as follows. One or more prepregs obtained by coating and drying an epoxy resin on a fiber substrate are stacked on an inner layer circuit board that has been subjected to circuit processing and black treatment on both sides or one side, and a metal foil is placed on top of it. It is obtained by stacking and heating and pressing. The epoxy resin used for the prepreg is usually a terminal bifunctional linear epoxy resin having an epoxy equivalent of about 350 to 800 and a small amount of novolac type epoxy resin for improving heat resistance and chemical resistance (based on the whole epoxy resin). 5 to 30% by weight). Epoxy resin having such a composition has sufficiently good characteristics as a printed circuit board, but resin powder is easily generated by cutting or punching a prepreg.

In the formation of a printed wiring board, resin powder generated from a cut portion of a prepreg or the like enters a space between a metal mirror plate and a metal foil in a heating / pressing step or a preceding laminating step, and is formed as it is. Then, the resin powder acts in the same manner as an etching resist in an etching step for forming a circuit pattern in a later step, causing insulation failure of the circuit pattern and the like. Therefore,
The resin and the resin powder in the portion of the prepreg where the resin powder is likely to be generated or where the resin powder is adhered are re-melted to prevent the generation and scattering of the resin powder from the prepreg. This step requires extra equipment and man-hours, and a method that does not require this step has been desired.

[0004]

DISCLOSURE OF THE INVENTION The inventors of the present invention have found that in a printed circuit board or a multilayer printed wiring board, a resin is formed between a metal mirror surface plate and a metal foil at the time of lamination molding, which causes etching defects at the time of forming a circuit pattern. In order to solve the problem that the powder enters, the present invention has been accomplished as a result of intensive studies on the composition of the epoxy resin impregnated in the prepreg.
The present invention relates to a method for producing a prepreg that can significantly reduce the amount of resin powder generated from the prepreg in steps such as cutting, bending, and drilling, thereby eliminating the need for a re-melting step of the prepreg. Things.

[0005]

The present invention relates to a method for producing a prepreg for a printed wiring board, comprising: (1) a terminal bifunctional linear polymer epoxy resin having an epoxy equivalent of 1500 or more and 4000 or less; and (2) guanide. The present invention relates to a compound and (3) a method for producing a prepreg, which comprises impregnating a fiber base material with an epoxy resin varnish containing a curing accelerator as an essential component and drying the prepreg.

The object of the present invention is, as described in the section of the problem to be solved by the present invention, the production of a prepreg capable of eliminating the need for remelting the impregnated resin of the prepreg for preventing the scattering of the resin powder. To provide a method. That is, by combining a bifunctional linear epoxy resin having a relatively high molecular weight as a main component with a guanide compound-based curing agent and a curing accelerator, the epoxy resin-containing prepreg which is B-staged without deteriorating the curability. It was possible to suppress the generation of resin powder from the resin to an extremely low level.

Hereinafter, the present invention will be described in detail. As the epoxy resin, in order to obtain a low dusting property of the prepreg and to eliminate the need for remelting the prepreg, a bifunctional linear polymer epoxy resin having an epoxy equivalent of 1500 or more and 4000 or less is used. . Typically, a bifunctional linear epoxy resin obtained by reacting a bifunctional phenol such as bisphenol A with epihalohydrin and a terminal bifunctional obtained by an alternating copolymerization reaction of a bifunctional epoxy resin and a bifunctional phenol There are linear epoxy resins and the like, and these can be used in combination of several types. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, tetrabromobisphenol A type epoxy resin, propylene oxide bisphenol A type epoxy resin, bisphenol S type epoxy resin, biphenyl type epoxy resin, 2,6-naphthol type diglycidyl ether. Polymer, bisphenol A type epoxy resin and tetrabromobisphenol A copolymer, bisphenol F type epoxy resin and tetrabromobisphenol A
Examples thereof include copolymers, bisphenol S type epoxy resins and tetrabromobisphenol A copolymers. The above-mentioned brominated epoxy resin can be used for flame retardancy.

The molecular weight of the epoxy resin will be mentioned. Considering the low dusting property of the prepreg that has not been subjected to the remelting treatment, the higher the molecular weight, the better the tendency, but the curability tends to decrease. Although there are some differences depending on the basic skeleton of the epoxy resin and the type of curing agent, this tendency is basically the same. For printed wiring boards using epoxy resin, the low dusting property of prepreg required for practical use is the average epoxy equivalent of 1
In the case of using 500 epoxy resin, it was a practical minimum level. Further, in the case of an epoxy resin having an average epoxy equivalent of 4000 or more, the dusting property is at a sufficiently low level, but the heat distortion temperature is lowered and it is difficult to develop heat resistance as required. This is because the distance between the bridge points is too large,
This is because the number of cross-linking points also decreases.

It is preferable that the content of the bifunctional linear polymer epoxy resin having an epoxy equivalent of 1500 or more and 4000 or less is 50% by weight or more based on the whole epoxy resin. If it is less than 50% by weight, the above-mentioned features of the epoxy resin cannot be fully exhibited. It is preferably 70% by weight or more.

It is preferable to add a novolak type epoxy resin in addition to the epoxy resin. The novolak-type epoxy resin has a small epoxy equivalent, increases the crosslinking density, and improves curability. Therefore, improvement of heat resistance (glass transition temperature), chemical resistance and the like can be achieved by blending the novolak type epoxy resin.
The content of this resin is preferably 10 to 40% by weight based on the total epoxy resin, and the characteristics of the two types of epoxy resins are effectively exhibited in this range. Even if it is less than 10% by weight, it can be used, but the compounding effect is small and it cannot be said to be substantial. 40% by weight
If it exceeds the above range, the effect of compounding the novolac type epoxy resin is large, but conversely, the compounding effect of the terminally bifunctional linear polymer epoxy resin having an epoxy equivalent of 1500 or more and 4000 or less decreases, which is not preferable.

The guanide compound which is a curing agent will be described. The guanide compound is used to make up for the deterioration of the curability due to the use of the terminal bifunctional linear polymer epoxy resin while ensuring the storage stability of the prepreg. As the guanide compound, a compound having a guanidine structure is generally shown, and 1,3-diphenylguanidine, di-orthotolylguanidine, 1-orthotolyldiguanide, α-2,
5-dimethylguanide, α, ω-diphenyldiguanide, 5-hydroxynaphthyl-1-diguanide, phenyldiguanide, α, α′-hexamethylenebis [ω-
(P-chlorophenol)] diguanide, o-tolyldiguanide zinc salt, diphenyldiguanide iron salt, phenyldiguanide copper salt, diguanide nickel salt, ethylenebisdiguanide hydrochloride, lauryldiguanide hydrochloride, Examples include phenyldiguanido oxalate, monosubstituted or disubstituted alkyl-substituted phenyldiguanide, and the like.
1,3-diphenylguanidine, di-orthotolylguanidine, and 1-orthotolyldiguanide are preferable compounds having a large curability improving effect, and one or more selected from these are used as an epoxy resin. Appropriate curability can be obtained by adjusting the equivalent ratio of 0.8 to 2 times.

The advantage of these compounds is that they generate a very large amount of heat when they react with the epoxy groups of the epoxy resin to open the epoxy ring. Therefore, as in the case of the present invention, the reaction is remarkably promoted in the reaction system in which the addition polymerization is caused with the epoxy resin by heating. To cure with a guanide compound, increase the compounding amount of a curing agent or a curing accelerator in a reaction with a resin having a small number of reaction points such as a terminally bifunctional linear polymer epoxy resin having an epoxy equivalent of 1500 or more and 4000 or less. It is a useful method for shortening the curing time. In addition, aromatic polyamines and the like can be used in combination for improving heat resistance and hygroscopicity, but if the amount of the curing agent is more than 80% of the total amount of the curing agent, the balance between curability and storability is obtained. Be careful because it may break.

The curing accelerator will be described. The type of the curing accelerator is not particularly limited, but an imidazole type curing accelerator and a phosphine type curing accelerator are preferably used. Examples of the imidazole-based curing accelerator include 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, and 2,4′-diamino-6- [2′-.
Ethyl-4′-methylimidazolyl- (1 ′)] ethyl-s-triazine, 2-methylimidazole / isocyanuric acid adduct, 2-methylimidazole / trimellitic acid adduct, and the like, and as a phosphine-based curing accelerator Include triphenylphosphine, triphenylphosphine phenol salt and the like. In order to improve the heat resistance, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-undecylimidazole, 1-cyanoethyl-2-undecylimidazole or 2,4-diamino-6- {2′- Undecyl imidazolyl- (1 ′) − ethyl-s-triazine is preferably used alone or in combination. The amount of the curing accelerator based on 100 parts by weight of the epoxy resin is preferably 0.1 to 0.8 parts by weight. 0.
If the amount of addition exceeds 8 parts by weight, curing will be too fast and moldability will be deteriorated, and heat resistance to moisture absorption solder and prepreg storability will not be compatible, or both properties will be deteriorated. On the other hand, if the addition amount is less than 0.1 part by weight, the curing property and the heat resistance become insufficient due to insufficient curing, and the adhesiveness also decreases.

Further, if necessary, a silane coupling agent may be blended for the purpose of imparting adhesion to an inorganic substance such as a metal foil or glass cloth. For example, as the coupling agent, a silane coupling agent,
Titanate-based coupling agents, aluminum chelate-based coupling agents, and the like can be used. For example, chloropropyltrimethoxysilane, vinyltrichlorosilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, N -Β- (aminoethyl) -γ-aminopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, isopropyltriisostearoyl titanate, isopropyltrimethacrylate titanate, isopropyltri (dioctylphyrophosphate) titanate, isopropylisostearoyldi ( 4-aminobenzoyl) titanate and the like. The compounding amount with respect to 100 parts by weight of the epoxy resin is preferably 0.1 to 2.0 parts by weight. If it is less than 0.1 part by weight, the effect of improving the peel strength with an inorganic material such as a metal foil or glass cloth is insufficient, and if it exceeds 2.0 parts by weight, no further improvement is observed. In particular, unreacted parts may occur, which may hinder curing.

Further, if necessary, an antifoaming agent can be added as a surface tension adjusting agent in order to improve the appearance characteristics of the prepreg (no repellency, craters, voids, etc.). As the defoaming agent, a non-silicone type (acrylic type) defoaming agent is preferable since it has good sliding characteristics. The amount of such defoaming agent is preferably 0.1 to 2.0 parts by weight with respect to 100 parts by weight of the epoxy resin. If the amount is less than 0.1 part by weight, the compounding effect is small, and if the amount is more than 2.0 parts by weight, the gel time of the varnish is shortened. Within this range, a sufficient effect of improving the appearance characteristics is exhibited.

When the above epoxy resin composition is applied to the fiber base material, the viscosity is usually adjusted with a solvent. As the solvent, acetone, methyl ethyl ketin, toluene, xylene, ethylene glycol monoethyl ether and its acetate compound, propylene glycol monoethyl ether and its acetate, dimethylformamide,
Methyldiglycol, ethyldiglycol, methanol, ethanol and the like can be mentioned.

As a coating method, any method can be used as long as the substrate is impregnated with an epoxy resin varnish containing an organic solvent. In any of these methods, the optimum viscosity required for impregnation is required, and it is necessary to adjust the types and blending amounts of the reactive diluent and solvent depending on the coating method.

The cured state of the resin of the prepreg will be mentioned. The cured state is generally A, which is a completely uncured state.
It can be divided into a stage state, a B-stage state which is a semi-cured state, a gel state which has been further cured, and a C-stage state which is a completely cured state. The epoxy resin of the prepreg obtained according to the present invention is usually in a B stage state, but handling is particularly facilitated by keeping it in a tack-free state.

By using the prepreg obtained according to the present invention in a printed circuit board, it is possible to eliminate the need for re-melting the prepreg for reducing dust, which has been conventionally required in advance during lamination molding or multilayer molding. it can. Therefore,
The number of man-hours required for quality control of the prepreg remelting process and the production cost can be reduced, and there is no fear that the gel time of the prepreg is locally shortened by not performing the prepreg remelting process. Furthermore, when cutting size is re-acquired or drilling is performed, even if the prepreg is re-melted to reduce dust generation, it is necessary to perform the same process again, and quality control is duplicated, which is complicated. In any case, in the prepreg obtained by the present invention,
The redundant quality control as described above is unnecessary. Furthermore, since a guanide compound is used as a curing agent, the terminal 2
It is possible to compensate for the decrease in curability and heat resistance due to the functional linear polymer epoxy resin.

[0020]

The present invention will be described below in detail based on examples and comparative examples.

(Example 1) Glass woven fabric substrate thickness 0.1 m
The glass epoxy double-sided copper clad laminate with a copper foil thickness of 35 μm was surface-polished, soft-etched to remove the rust-preventing treatment, and then processed into a circuit by etching and subjected to black treatment to obtain an inner layer printed circuit board.

80 parts by weight of a bisphenol A type epoxy resin (epoxy equivalent: 2900) was added to ethyl carbitol 80.
It dissolved in parts by weight. To this, ortho-cresol novolac type epoxy resin (epoxy equivalent 215, melting point 70-8
20 parts by weight of methyl ethyl ketone (MEK) 20
Then, 3.8 parts by weight of 1-orthotolyldiguanide as a curing agent was added and dissolved. Further, 2-phenyl-4-methylimidazole 0.1 as a curing accelerator is used.
2 parts by weight and acrylic antifoaming agent (BYK-361)
After adding 0.2 parts by weight, they were mixed in a mixing tank. Further, the viscosity was adjusted by MEK to obtain an epoxy resin varnish for impregnation.

A glass woven cloth was impregnated with the epoxy resin varnish and dried to obtain a prepreg (180 μm thick). This prepreg is overlaid on the inner layer printed circuit board one by one, and a copper foil with a thickness of 18 μm is overlaid on both sides of the prepreg.
Heat-press molding was carried out for 150 minutes at 70 ° C. including temperature rise and cooling to obtain a multilayer printed wiring board. The amount of resin powder generated in the prepreg was measured, and the characteristics of the multilayer printed wiring board (outer layer copper foil peel strength and solder heat resistance after moisture absorption) were evaluated, and the results are shown in Table 1. The amount of resin powder generated from the prepreg is extremely small.

(Examples 2 to 4) A multilayer printed wiring board was prepared in the same manner as in Example 1 except that the composition of the varnish was changed as shown in Table 1, and the characteristics were evaluated. Table 1 shows the compositions and evaluation results. As in Example 1, the amount of resin powder generated from the prepreg is extremely small.

(Comparative Examples 1 to 3) A multilayer printed wiring board was prepared in the same manner as in Example 1 except that the composition of the varnish was changed as shown in Table 1, and the characteristics were evaluated. Table 1 shows the compositions and evaluation results.

[0026]

[Table 1] Note 1 DDDDM: diaminodiethyldimethyldiphenylmethane Note 2 2P4MZ: 2-phenyl-4-methylimidazole Note 3 2E4MZ: 2-ethyl-4-methylimidazole

(Measurement method) 1. Amount of resin powder generated: The amount of resin powder generated (per 1 cm of length) was measured when the prepreg was cut by a cutter knife for a certain length (about 50 cm). 2. Peel strength of outer layer copper foil: The peel strength was measured according to JIS C 6481. Copper foil is TSTO foil (Furukawa Circuit Wheel)
(Manufactured by Co., Ltd.) was used. 3. Solder heat resistance after moisture absorption: The obtained multilayer printed wiring board was cut into a size of 50 × 50 mm, the surface copper foil was removed by etching, and after 125 minutes PCT treatment for 30 minutes,
It was immersed in a solder bath at 260 ° C. for 20 seconds and checked for any abnormalities such as swelling.

[0028]

As is clear from the above examples, the prepreg obtained by the method of the present invention generates very little resin powder at the time of cutting or the like. Can be substantially eliminated. In addition, since the guanide compound is used as the curing agent, the decrease in the curing property due to the use of the polymer bifunctional epoxy resin is compensated. Therefore, it is possible to eliminate the remelting treatment of the prepreg which is conventionally required, and further, it is possible to shorten the manufacturing process of the printed circuit board and achieve the reduction of the manufacturing cost.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display area C08L 63/04 NJC C08L 63/04 NJC

Claims (3)

[Claims] 1. A method of manufacturing a prepreg, comprising: (1)
Terminal 2 having an epoxy equivalent of 1500 or more and 4000 or less
A method for producing a prepreg, which comprises impregnating a fiber base material with an epoxy resin varnish containing a functional linear polymer epoxy resin, (2) a guanide compound, and (3) a curing accelerator as essential components, and drying. 2. The method for producing a prepreg according to claim 1, wherein the novolac type epoxy resin is contained in an amount of 10 to 40% by weight based on all the epoxy resins. 3. The epoxy resin having an epoxy equivalent of 1500 or more and 4000 or less is 50% by weight or more of a bifunctional linear polymer epoxy resin having a terminal end in all epoxy resins.
A method for producing the described prepreg.