JPH05154960A - Production of laminated sheet for printed circuit board - Google Patents

Abstract

PURPOSE:To obtain a composite laminated plate excellent in dimensional stability in respective processes processing the laminated sheet into a printed circuit board. CONSTITUTION:In a composite laminated sheet wherein a surface layer is composed of a glass fabric impregnated with an epoxy resin and an intermediate layer is composed of a glass nonwoven fabric impregnated with an inorg. filler, copper foil whose Young's modulus in a 180 deg.C-atmosphere is 1500kg/mm<2> or less is used and after-baking treatment is performed after laminate molding. Therefore, the strain at the time of laminate molding is eliminated and a dimensional change rate during processing can be reduced to about 1/3 as compared with a conventional product.

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 laminated board for a printed circuit, which has excellent dimensional stability in each step of processing the laminated board.

[0002]

2. Description of the Related Art As a laminate for a printed circuit, a laminate made of a nonwoven glass fabric as an intermediate layer base material and a glass woven fabric as a surface layer base material and impregnated with an epoxy resin and heated and pressed (hereinafter referred to as composite laminate). Plates) have come to be used in large quantities. Laminates made by impregnating epoxy resin on a base material made only of glass woven fabric have excellent mechanical strength, dimensional stability, heat resistance, etc., and high reliability of through-hole plating, so electronic calculators, communication devices, electronic exchanges, etc. Is widely used in industrial electronic devices. However, since only the glass woven fabric is used as the base material, the punching process is not possible in the punching process, which is one of the processes for processing the printed circuit board, and the fact is that it is drilled.

On the other hand, the composite laminated plate is economically cheaper than the laminated plate of the glass woven fabric base material and is excellent in that it can be punched and punched. However, the reliability of through-hole plating was evaluated to be lower than that of the glass woven fabric substrate laminate. The reason is that the glass woven fabric-based epoxy laminate has a composition in which the weight ratio of the organic epoxy resin to the inorganic glass woven fabric is about 40:60. In this case, it is considered that the epoxy resin mainly makes various electrical characteristics excellent, and the glass woven cloth makes mechanical properties such as bending strength and dimensional stability favorable.

By the way, a general composite laminated board uses a glass non-woven fabric as a base material for the intermediate layer, and is liable to be distorted during heating and pressurizing as compared with a laminated board using a woven cloth base material. There is a problem of poor stability.

[0005]

DISCLOSURE OF THE INVENTION The present invention makes the dimensional stability during processing into a circuit board equal to that of a laminated sheet using a glass woven base material without losing the excellent characteristics of the conventional composite laminated sheet. The purpose is to

[0006]

According to the present invention, the surface layer comprises a thermosetting resin-impregnated glass woven cloth, and the intermediate layer comprises a resin containing 10 to 200% by weight of a filler with respect to the thermosetting resin. In a laminated board made of impregnated glass non-woven fabric, as a metal foil for forming a printed circuit, a copper foil having a Young's modulus of 1500 kg / mm ² or less in an atmosphere of 180 ° C. is laminated, and after-baking is performed after lamination molding. And a method for manufacturing a printed circuit laminate. The conditions for after-baking are usually 155 to 190 ° C.
Therefore, a time of 20 to 90 minutes is suitable. If the temperature is 155 ° C or lower, the effect of after-baking may be insufficient, and if the temperature is 190 ° C or higher, further improvement of the effect cannot be expected. If the time is 20 minutes or less, the effect may be insufficient,
Even if heated for 90 minutes or more, the effect does not change.

[0007]

Since the conventional composite laminated board uses the glass non-woven fabric as the base material of the intermediate layer, it has a problem that the dimensional stability in the laminated plate processing step is inferior to that of the glass woven cloth base material laminated board. there were. The present invention is to solve these drawbacks, by using a metal foil having a low Young's modulus at the time of heating and after-baking the resulting laminated sheet, the strain at the time of heat and pressure molding can be easily performed. It can be eliminated, and the dimensional stability can be improved to the same level as that of the glass woven fabric substrate laminate.

As the metal foil having a low Young's modulus when heated for use in the present invention, aluminum, tin, lead or the like can be considered, but usually copper foil is used for a printed circuit. A patent for a special copper foil, for example, a hot-expansion foil (hereinafter referred to as HTE foil) for the purpose of improving dimensional stability has been filed (Japanese Patent Laid-Open No. 2-258337). The stipulation that the elongation rate is good does not have a great effect on the improvement of dimensional stability. For example, even if a metal foil having a Young's modulus similar to that of a copper foil and an elongation of several times is used, the dimensional change is not improved. This indicates that the copper foil needs to easily follow the slight stress of the substrate when releasing the strain at the time of heating and pressurizing the laminate by performing post-baking after the laminate molding.

Therefore, when the Young's modulus in an atmosphere of 180 ° C. is 1500 kg / mm ² or more, the dimensional change rate is similar to that of a normal copper foil, but when a metal foil of 1500 Kg / mm ² or less is used, it becomes a glass woven fabric. It has been confirmed to show similar dimensional change rates. Further, in the measurement of Young's modulus, it is generally accepted that the measurement conditions and the values obtained by the measuring device vary greatly, but the data in the present invention is that the crosshead speed of the measuring device is 10 mm / min, the chart speed is Was set to 1000 mm / min so that a slight amount of elongation of the copper foil could be accurately measured. The copper foil having a Young's modulus of not more than 1500 kg / mm ² in an atmosphere of 180 ° C. according to the present invention has the above-mentioned properties after the copper is crystallized by preheating the foil at a temperature of not less than 160 ° C. It also includes the Young's modulus measured under the conditions. The preheating conditions are, for example, 120 minutes at 160 ° C., 60 minutes at 180 ° C., and 30 minutes at 200 ° C. 200 ° C
At higher temperatures, the surface of the copper foil is likely to be oxidized, so it is usually best to avoid it. The thickness of the metal foil is not particularly limited.

[0010]

EXAMPLES The present invention will be described with reference to Examples and Comparative Examples. The composition of the epoxy resin varnish is as follows.

[Table 1]

The above materials were mixed to prepare a uniform varnish. Next, this varnish was used as a surface layer on a glass woven fabric (WE-18K-RB84 manufactured by Nitto Boseki) having a resin content of 42-4.
The glass woven fabric prepreg was obtained by impregnating and drying so as to be 5%. Then, a resin component 1 was added to the above varnish for the intermediate layer.
An inorganic filler having the following composition was added to 00 parts, and mixed by stirring to prepare a varnish containing an inorganic filler. Silica (Tatsumori Crystallite VX-3) 25 parts Aluminum hydroxide (Al ₂ O ₂ · 3H ₂ O) 70 parts Superfine silica (Shionogi Carplex) 5 parts This inorganic filler-containing varnish is a glass nonwoven fabric A base material (manufactured by Nippon Vilene) was impregnated and dried so that the content of the resin and the inorganic filler was 90% to obtain a prepreg.

[0012]

[Examples 1 and 2] A glass non-woven fabric base prepreg was used as an intermediate layer, the glass woven prepreg was placed on the upper and lower surface layers, and a copper foil was preheated thereon at 180 ° C for 60 minutes and then in an atmosphere at 180 ° C. Young's modulus at 1100kg
/ Mm ² of copper foil is overlaid, molding temperature 180 ℃, pressure 60
Lamination molding was performed at Kg / cm ² for 90 minutes to obtain a copper clad laminate having a thickness of 1.6 mm. Further, after molding, after-baking treatment was performed at 180 ° C. for 60 minutes. A copper foil having a thickness of 18 μm was used in Example 1, and a copper foil having a thickness of 35 μm was used in Example 2.

[0013]

Comparative Examples 1 and 2 Instead of the above example,
A copper clad laminate having a thickness of 1.6 mm was prepared in the same manner as in Examples 1 and 2 except that the copper foil having Young's modulus of 2500 kg / mm ² in an atmosphere of 180 ° C. was preheated for 0 minutes. Obtained. With respect to the obtained copper-clad laminate, the dimensional change rate (shrinkage rate) in the process of processing the circuit board was measured. The results are shown in Table 2.

[0014]

[Table 2] As is clear from Table 2, the copper-clad laminate according to the example using a copper foil having a small Young's modulus when heated has excellent dimensional stability.

[0015]

EFFECTS OF THE INVENTION The laminated sheet according to the present invention is obtained by laminating a copper foil having a small Young's modulus at the time of heating with a substrate and subjecting it to a baking treatment, so that it has a greater dimensional stability than conventional composite laminated sheets. It is improved to the same level as the glass woven fabric substrate laminate, and is suitable as an industrial method for producing a laminate for a printed circuit. Further, the obtained laminated plate is also improved in deformation such as warp and twist.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical indication H05K 1/03 L 7011-4E 3/00 R 6921-4E

Claims (1)

[Claims] 1. The surface layer is made of a glass woven fabric impregnated with a thermosetting resin, and the intermediate layer is made of a glass nonwoven fabric impregnated with a resin containing 10 to 200% by weight of a filler with respect to the thermosetting resin. In the laminated plate, the Young's modulus of the metal foil forming a printed circuit is 15 at 180 ° C.
A method for producing a laminated board for a printed circuit, comprising laminating copper foils having a weight of 00 kg / mm ² or less, and performing after-baking after laminating.