JP2898809B2 - Manufacturing method of laminated board - Google Patents

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 laminate for a printed circuit, which enhances the adhesive strength between the interface between the base material and the resin and the bonding surface between the copper foil and the resin, and improves the heat resistance and moisture resistance. Therefore, the reliability with the circuit board is improved.

[0002]

2. Description of the Related Art Conventionally, epoxy resin varnishes used for printed circuit laminates having good heat resistance and moisture resistance are often composed of novolak type epoxy resins and novolak type phenol resins. In addition, there was a drawback that punching workability, interlayer adhesion, and copper foil peel strength were insufficient due to insufficient toughness. Also,
Since the varnish has high viscosity, the impregnating property of the glass cloth is poor, and the impregnating property has been improved by using a special cloth such as an opened cloth or by using a device such as vacuum impregnation or vacuum press.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a high-performance printed circuit laminate which simultaneously satisfies heat resistance, moisture resistance, interlayer adhesion and copper foil peel strength. And

[0004]

According to the present invention, there is provided a method for producing a prepreg by impregnating a fiber base material with an epoxy resin varnish and heating and drying the prepreg. (A) bisphenol A epoxy resin, (b) novolak epoxy resin, (c) bisphenol A and / or brominated bisphenol A (d) novolak phenol resin It is about the method.

Next, each component will be described. (A) The bisphenol A type epoxy resin preferably has an epoxy equivalent of 300 or less, particularly 190. Specifically, Epicoat 828 (epoxy equivalent 190, manufactured by Yuka Shell Epoxy) is preferably used, and Epicoat 834 (epoxy equivalent 25, manufactured by Yuka Shell Epoxy) is preferably used.
0) and Epicoat 1001 (same as above, epoxy equivalent 480)
And the like having a large molecular weight can be blended within 20 to 30%. (B) As the novolak type epoxy resin, any one can be used, and phenol novolak type epoxy resin (such as EPC-N-740 manufactured by Dainippon Ink & Chemicals, Inc.) and cresol novolak type epoxy resin (manufactured by the company)
EPC-N-673, etc., bisphenol A novolak type epoxy resin (EPC-N-880, EP manufactured by the company)
CN-856 etc.), but a bisphenol A novolak type epoxy resin is particularly preferred because of its excellent heat resistance and copper foil peel strength. As the component (a) and the component (b), brominated products can be used. As the component (a), ESB-400
(Epoxy equivalent 400 manufactured by Sumitomo Chemical Co., Ltd.) ESB-5
00 (Equivalent epoxy equivalent 500), ESB-700
(Epoxy equivalent of 700 manufactured by the company), and the component (b) includes BREN (epoxy equivalent of 400 manufactured by Nippon Kayaku Co., Ltd.).

(C) Examples of bisphenol A and / or brominated bisphenol A include bisphenol A and tetrabisphenol A. (D) As the novolak type phenol resin, those used as ordinary epoxy resin curing agents may be used.
It is preferred to have as little free phenol as possible. These components are contacted in order to react them in the prepreg manufacturing process and the lamination molding process. Examples of such catalysts include imidazole compounds, tertiary amines, triphenylphosphine, and DBU compounds. A catalyst for the curing reaction is used.

The ratio of the total of the epoxy groups of the components (a) and (b) to the total of the hydroxyl groups of the components (c) and (d) is about 1.0. Most preferably, when it is in the range of 0.7 to 1.3, the glass transition point of the reaction-cured product is high, and the adhesive strength (adhesion) is large.
Other characteristics are also good and can be used sufficiently. If the above ratio is 0.7 or less, the cured product becomes brittle and the adhesive strength decreases. If the ratio is 1.3 or more, the glass transition point decreases, and the moisture resistance also decreases. The amount of the catalyst is preferably about 0.05 to 0.5% based on the total of all the resin components.
If the amount is less than 0.05%, the effect of the catalyst is small, and the amount is less than 0.05%.
If it is more than 5%, the reaction rate is high, but various properties of the cured product tend to decrease.

[0008] In addition to these resins and contact, the addition of a silane coupling agent improves the adhesive strength, and is particularly preferable for improving the adhesive strength with the copper foil. The silane coupling agent is not particularly limited, but epoxy silane and isocyanate silane are preferable because they have reactivity with a hydroxyl group or an epoxy group. The compounding amount is preferably 0.01 to 0.5% based on the resin component. If the amount is less than 0.01%, the effect is small, and if it is more than 0.5%, the effect is hardly improved, and the cost increases, which is not preferable.

The epoxy resin containing the above components is dissolved in a solvent such as methyl cellosolve, dimethylformamide, methyl ethyl ketone, etc., to form a varnish having a resin content of 40 to 50%. The varnish is impregnated into a fiber base material such as a glass cloth and dried by heating to obtain a prepreg. Next, an appropriate number of prepregs are laminated, and a copper foil is usually laminated on one or both surfaces thereof, followed by heat and pressure molding to obtain an epoxy resin laminate. The copper foil is preferably subjected to a brass treatment as a roughened surface, and is preferably not deteriorated by a hydrochloric acid treatment in a processing step of a printed wiring board or the like.

[0010]

The epoxy resin varnish used in the present invention comprises two types of epoxy resin components and two types of phenolic compounds having a hydroxyl group which reacts with the two components. The epoxy resin and the phenolic compound react in a stage where the varnish is impregnated into the fiber base material and heated and dried to form a so-called B stage.
This reaction is mainly a reaction in which a bisphenol A-based compound connects an epoxy resin with a bisphenol A-based compound, particularly, a bisphenol A-type epoxy resin and a novolak-type epoxy resin. Then, at the stage of lamination molding,
Curing occurs when the reaction between the reaction product and the novolak phenol resin mainly proceeds. The resulting cured resin has an extremely suitable balance between crosslink density and crosslink network size, and has few free polar groups after curing, so it has excellent heat resistance and water resistance. The adhesion of the foil is also excellent. Furthermore, since the varnish has a low viscosity in a usual resin component, it has good impregnation into a fiber base material, and is suitable for obtaining a laminate having few voids.

[0011]

The present invention will be described below with reference to examples and comparative examples. The resins used are as follows. (A) Bisphenol A type phenol resin (a1) Epocoat 828 (epoxy equivalent 190) (a2) Epocoat 834 (epoxy equivalent 250) (b) Novolak type epoxy resin (b1) EPC-N-740 (phenol novolak type, epoxy equivalent) 190) (b2) EPC-N-880 (bisphenol A novolak type, epoxy equivalent 203) (c) bisphenol A and / or brominated bisphenol A (c1) tetrabromobisphenol A (d) novolak type phenolic resin (d1) phenol novolak Type (number average molecular weight 85
0) (e) Catalyst (e1) 2-phenol-4-methylimidazole (2
(P4MZ) (f) Silane coupling agent (f1) A-187 (epoxysilane) The composition of the epoxy resin varnish in Examples and Comparative Examples is as shown in Table 1. Formulations are by weight.

[0012]

[Table 1]

The varnish of each example was applied to a glass cloth (200 μm
Thickness) is impregnated to a resin content of about 40%,
After drying for 4 minutes, a prepreg was obtained. Eight pieces of this prepreg and 18 μm-thick copper foil were superimposed on both surfaces thereof.
The mixture was heated and pressed at 120 kg / cm ² for 120 minutes to obtain a double-sided copper-clad laminate. Characteristics were measured for each laminate, and the results are shown in Table 2.

[0014]

[Table 2]

(Measurement method) Glass transition temperature: By viscoelasticity method Water absorption: According to JIS C 6481 Copper foil peel strength: According to JIS C 6481 Heat resistance: Heated at 250 ° C. for 10 minutes to check for blisters. Presence or absence of voids: After etching the copper foil, the appearance of the surface was visually observed.

[0016]

The laminate obtained by the present invention is excellent in water resistance, high in glass transition point, and heat resistant since novolak type phenol resin is used as a curing agent. Further, since bisphenol A type and novolak type epoxy resin are used in combination and bisphenol A and / or brominated bisphenol A are used as epoxy resin, laminating adhesive strength and copper foil, which are disadvantages of conventional novolak type phenol resin curing, are used. And the varnish viscosity is low, so that the fiber base material is well impregnated, and therefore the number of voids in the laminate can be extremely reduced. In particular, if a bisphenol A novolak type phenol resin is used as the novolak type phenol resin, various characteristics are further improved.

Claims (2)

(57) [Claims] 1. A method for producing a prepreg by impregnating a fiber base material with an epoxy resin varnish and heating and drying the prepreg, and producing a laminate from the prepreg by a conventional method, wherein the epoxy resin varnish comprises: (a) a bisphenol A type epoxy resin (B) a novolak-type epoxy resin; (c) bisphenol A and / or brominated bisphenol A (d) a novolak-type phenol resin as a resin component. 2. The ratio (A / B) of the total (A) of the total number of epoxy groups (A) and (B) to the total number of hydroxyl groups (B) of (c) and (d) is 0. 1.7 to 1.3.
The method for producing a laminate according to the above.