JPH0976262A - Preparation of paper base copper-clad laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper base copper-clad laminate with excellent migration resistance and resistance to galvanic corrosion. SOLUTION: In a single-sided or a double-sided copper-clad laminate consisting of several sheets of prepregs prepd. by impregnating a paper base with a specified amt. of a resin and a copper foil with an adhesive, a prepreg prepd. by forming a resin layer with a thickness of 5-50/μm on the surface layer of the prepreg to be used is used and a plurality of these sheets are laminated and the copper foil with the adhesive are laminated on the outside and a paper base copper-clad laminate is prepd. by heating and pressing them.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper base copper clad laminate having excellent silver migration resistance and electrolytic corrosion resistance.

[0002]

2. Description of the Related Art Recently, due to the multifunctionalization and high reliability of electronic equipment, copper-clad laminates using paper base materials have been made into silver paste through holes, copper paste through holes, copper plating through holes, etc. High reliability is required. In particular, a printed wiring board having excellent through-hole reliability, silver migration resistance, and electrolytic corrosion resistance is required. Conventionally, as a technique for improving silver migration resistance and electrolytic corrosion resistance, there is a method of treating a paper base material with a water-soluble phenol resin or a water-soluble melamine resin.

[0003]

However, due to the high density of the pattern of the printed wiring board and the narrowing of the silver through-hole spacing, sufficient silver migration resistance and electrolytic corrosion resistance cannot be satisfied by the above method alone. It was An object of the present invention is to provide a paper-based copper-clad laminate excellent in silver migration resistance and electrolytic corrosion resistance.

[0004]

DISCLOSURE OF THE INVENTION The present invention relates to a prepreg used in a paper base copper-clad laminate consisting of several prepregs obtained by impregnating a paper base with a predetermined amount of resin and a copper foil with an adhesive. A method for producing a paper-based copper-clad laminate, comprising forming a resin layer of 5 μm to 50 μm on a surface layer.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The thermosetting resin used in the varnish of the present invention is a phenol resin, a melamine resin, an unsaturated polyester resin or the like. Particularly, if it is a thermosetting resin or a drying oil-modified phenolic resin, the punching processability is also good. As the drying oil, tung oil, dehydrated castor oil, linseed oil, etc. are used, and as the phenols, phenol, metacresol, paracresol, orthocresol, isopropylphenol, paratertiarybutylphenol, paraisopropenylphenol oligomer, nonylphenol, bisphenol. A or the like is used. Kraft paper, linter paper or the like is used as the paper base material. A paper base treated with a water-soluble phenolic resin or a melamine resin is preferably used as the undercoat varnish.
The thickness of the resin layer on the surface of the prepreg used in the present invention is preferably 5 μm to 50 μm, and preferably 10 to 30 μm,
It is more preferable that the thickness is 15 to 25 μm. If it is less than 5 μm, silver migration resistance and electrolytic corrosion resistance are deteriorated, and
If it exceeds 0 μm, workability is extremely deteriorated due to adhesion of the prepreg during production and storage. The thickness is increased by increasing the viscosity and resin content of the varnish to be applied, adjusting the gap during varnish application, or applying multiple times. The paper-based copper-clad laminate is processed into a silver through-hole printed wiring board, but the double-sided copper-clad laminate is subjected to etching processing, and then silver through-hole holes are formed, silver paste is embedded, dried, and printed to form a silver through hole. It becomes a hole printed wiring board. Further, silver through-hole holes, semiconductor, resistor and other component holes are generally formed by drilling or punching.

In a silver through-hole printed wiring board,
Silver migration occurs at the boundary between the prepreg and the prepreg that form the copper clad laminate, and as a result, the silver migration resistance decreases. The reason why silver migration occurs at the boundary between prepregs and prepregs is that when the copper-clad laminate is manufactured (during lamination), the resin compatibility between the prepregs is not sufficient, so minute voids are created at the boundary. It is considered that the silver ions forming the silver through hole move through the void. The present invention provides a paper-based copper-clad laminate having a surface layer of a prepreg of 5 μm to 50 μm.
m resin layer is formed. 5 μm to 5 on the surface of the prepreg
By forming a resin layer having a thickness of 0 μm, the compatibility between the resin of the prepreg and the resin of the prepreg becomes good at the time of manufacturing (when laminating) the copper-clad laminate, voids in which silver migration occurs are eliminated, and silver migration resistance is improved. . Compared with this conventional one, the resin layer is 5 μm to 5
A plurality of prepregs thickened to 0 μm are stacked, and one or both sides of the prepreg are laminated so that the adhesive surface of the copper foil with the adhesive is on the prepreg side, and press-molded to obtain a laminated plate. Generally, the molding conditions are 150 to 180
C, 30 to 120 minutes, 30 to 150 Kgf / cm ²
It is.

[0007]

【Example】

(Example 1) Kraft paper treated with a water-soluble phenolic resin to a resin-adhered resin content of 14 to 20% in advance, and a resole resin having a tung oil modification rate of 30% was added to a prepreg to have a resin-adhered resin content of 50 to 54%. It was impregnated and dried.
The thickness of the resin layer on the surface of this prepreg was 20 μm. Eight sheets of this prepreg and two sheets of copper foil with an adhesive were combined and heat and pressure laminated at 170 ° C. for 90 minutes at 100 kgf / cm ² to obtain a double-sided copper clad laminate having a thickness of 1.6 mm. Table 1 shows the properties of the double-sided copper-clad laminate.

(Examples 2 and 3) In Example 1, the thickness of the resin layer on the surface of the prepreg was 6 μm (Example 2), 48
A double-sided copper-clad laminate was obtained in the same manner as in Example except that the thickness was changed to μm (Example 3). The properties of these double-sided copper-clad laminates are shown in Table 1.

Comparative Example 1 Example 1 is the same as Example 1 except that the thickness of the resin layer on the surface of the prepreg is 2 μm.
A prepreg was obtained in the same manner as in. 8 pieces of this prepreg and 2 pieces of copper foil with adhesive are combined and laminated by heating and pressing,
A 1.6 mm double-sided copper clad laminate was obtained. Table 1 shows the properties of the double-sided copper-clad laminate.

Comparative Example 2 A prepreg was obtained in the same manner as in Example 1 except that the thickness of the resin layer on the surface of the prepreg in Example 1 was changed to 55 μm. This prepreg and two copper foils with an adhesive were combined and heat-pressed and laminated to obtain a double-sided copper-clad laminate of about 1.6 mm. Table 1 shows the properties of the double-sided copper-clad laminate. In addition, this prepreg is used because it is difficult to separate the prepregs when they are piled up and the prepregs are stuck to each other, so that the prepregs are stored with a release film interposed therebetween, and are carefully laminated so as not to entrap air during manufacturing. . However, the obtained laminate had unevenness on the surface of the copper foil.

[0011]

[Table 1] Through hole reliability test results ───────────────────────────────── Item Item Example 1 Example 2 Example 3 Comparative example 1 Comparative example 2 ───────────────────────────────── 20 48 6 2 55 of the prepreg surface layer Resin thickness (μm) ───────────────────────────────── Silver-resistant Migra 2.6 × 10 ⁹ 3.8 × 10 ⁹ 8.2 × 10 ⁹ 6.1 × 10 ⁷ 4.0 × 10 ⁹ Option (Ω) ──────────────────────────────── ── Remark − Slightly sticky − − Sticky ───────────────────────────────────

The migration resistance is as follows.
5 mm, land diameter 0.5 mm, 100 holes continuous 2 circuits silver migration test pattern, applied voltage 50
V, relative humidity 90%, temperature 40 ° C., insulation resistance between circuits after 2000 hours of treatment was measured and evaluated. As shown in Table 1, when the resin thickness of the prepreg surface layer is 5 μm or more, it has migration resistance, and when it exceeds 50 μm, the prepreg becomes sticky and the handleability becomes extremely poor. This is because the thickness of the resin of the surface layer of the conventional prepreg was 0 to 4 μm.
This is because it is designed to be thicker than that.

[0013]

As is clear from the above results, the paper-based copper-clad laminate obtained by the present invention is excellent in silver migration resistance and electrolytic corrosion resistance.

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Claims (1)

[Claims] 1. A single-sided or double-sided copper-clad laminate consisting of several prepregs in which a resin is impregnated and adhered to a paper base material in a predetermined amount and a copper foil with an adhesive is used as a surface layer of the prepreg to be used.
A method for producing a paper-based copper-clad laminate, which comprises forming a resin layer of μm to 50 μm.