JPH0369353A - Manufacture of copper-clad laminated board - Google Patents

Abstract

PURPOSE:To attain the lowering of the dielectric constant of a laminated board and excellent punchability by a method wherein a woven fabric woven by using yarn, in which a specific quantity of polyethylene terephthalate and glass fiber are bundled, as warp and weft is impregnated with a resin, and a prepreg is obtained, a fixed number of the prepregs are laminated, and copper foils are positioned on one surfaces or both surfaces and heated, pressed and formed. CONSTITUTION:A woven fabric woven by using yarn, in which 30-80 wt.% polyethylene terephthalate fibers and 70-20 wt.% glass fiber are bundled, as warp and weft is impregnated with a resin, thus acquiring a prepreg. A fixed number of the prepregs are laminated, and copper foils are positioned on one surfaces or both surfaces of the laminate, and heated ad worked and molded,thus manufacturing a copper-clad laminated board. Size of 30-60mum is favorable as the polyethylene terephthalate fiber, and size of 6-9mum is preferable as the glass fiber. When the rate of the polyethylene terephthalate fibers are smaller than 30 wt.%, a dielectric constant is not lowered extremely, punching resistance is increased on machining, and cracks are easy to be formed at the intersections of yarn. When the rate of the polyethylene terephthalate fibers is larger than 80 wt.%, through-holes in a thermal process, etc. are easy to be scaled down, and dimensional stability is deteriorated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a low dielectric constant printed circuit board with excellent punching workability.

(Prior art) Conventionally, in order to reduce the dielectric constant of printed circuit boards, a laminated layer was used in which a core layer was a Bribrig made of polyethylene terephthalate fiber nonwoven fabric, and a Bribrig made of glass fiber cloth was used as the surface layer. The board is well known.

This laminate has problems in that, compared to a laminate made of a glass cloth base material, chipping of the wall surface and fiber residue are more likely to occur during punching, and the through-hole diameter is more likely to become narrower after heat treatment.

In addition, in order to use a low dielectric constant laminate in a high frequency range, it is necessary to use a glass cloth base material with a high dielectric constant for the layer immediately below the circuit in order to maintain the strength of the laminate. had its limits.

(Problems to be Solved by the Invention) Therefore, as a result of intensive studies to improve the above-mentioned drawbacks, the present inventors have developed a method for laminating layers by using bundled yarns using polyethylene terephthalate fibers and glass fibers as base materials. It has been found that it is possible to achieve both a low dielectric constant of the plate and good punching workability.

(Means for Solving the Problems) The present invention provides polyethylene terephthalate fibers of 30 to 80%
A prepreg is obtained by impregnating a woven fabric with a resin using a yarn made of a bundle of 170 to 20% by weight of glass fibers as the warp and weft, and a pre-preg is laminated in a predetermined number of sheets, and one or both sides thereof are coated with W4. This is a method for manufacturing a copper-clad laminate, which is characterized by placing a foil and performing heat and pressure molding.

The base material used in the present invention is a woven fabric using yarns made of bundles of polyethylene terephthalate fibers and glass fibers as warp and weft threads.

Polyethylene terephthalate fiber has a thickness of 20 to 90μ
is usually used, but 30 to 60μ is preferable.
Glass fibers with a thickness of 5 to 13μ are used,
The glass fiber is preferably 6 to 9μ, and the type of glass fiber is not particularly limited, but E glass is preferred.

These two types of fibers are bundled into a yarn in a proportion of 30-80% by weight of polyethylene terephthalate fibers and 70-20% by weight of glass fibers. A woven fabric is produced using this yarn as warp and weft threads. If the proportion of polyethylene terephthalate fibers is less than 1%, the dielectric constant will not decrease so much, and furthermore, during punching, the punching resistance will be large and cracks will easily occur at the intersections of the yarns.
If the amount is higher than that, the dimensional stability of a single hole in a heat process etc. will deteriorate.

The preferred blending ratio of both fibers is 30-60% by weight of polyethylene terephthalate fiber and 70-40% by weight of glass fiber.
It is.

The woven fabric thus obtained is impregnated with a resin to obtain a prepreg. The resin to be impregnated is not limited to epoxy resin, phenol resin, unsaturated polyester resin, etc., but epoxy resin is preferable in order to fully utilize the features of this woven fabric.

Thereafter, according to a conventional method, copper foil is superimposed on one or both surfaces of a predetermined number of the blibrig, and the copper foil is formed under heat and pressure to obtain a copper-clad laminate.

(Function) A feature of the present invention is that a woven fabric using yarn made of polyethylene terephthalate fibers and glass fibers bundled in a specific ratio is used as a base material. Compared to a laminate that uses glass fiber cloth as the surface layer base material and polyethylene terephthalate non-fibrous cloth as the core layer base material, the strength of the core layer is improved, and the strength of the core layer is improved in the punching process when only polyethylene terephthalate fiber is used. Prevents fibers from remaining due to difficulty in cutting. Furthermore, even if the polyethylene terephthalate fiber, which is a thermoplastic resin, softens during heating during the soldering process, the glass fiber maintains its strength, thereby preventing the polyethylene terephthalate fiber from shrinking and reducing the diameter of the through hole.

(Example) The present invention will be specifically explained using examples. In the formulation, "parts" and "%" indicate parts by weight and % by weight.

(Preparation of varnish) A varnish with a resin content of 50% was prepared using the following formulation.

Brominated bisphenol A type epoxy tree 11 100 parts (
Epoxy equivalent: 480) Diaminodiphenylmethane 10 parts 2-ethyl-4-methylimidazole 0.15 parts Methyl ethyl ketone 125 parts
Glass) and yarn (
Thread), the number of vertical strokes is 42/25m, and the number of horizontal strokes is 32/25m.
A woven fabric with a length of 25 m and a thickness of 0.2 mm was produced.

This base material was also impregnated with the varnish to obtain a prepreg with a resin content of 40%. Eight sheets of this prepreg were laminated with copper foil on both sides, and heated and pressed to obtain an epoxy resin copper-clad laminate having a thickness of 1.6 sm.

Example 2 An epoxy resin copper-clad laminate having a thickness of 1.6 mm was obtained in the same manner as in Example 1, except that the ratio of the polyethylene terephthalate fiber and glass fiber of the base material was 40 parts to 60 parts.

Comparative Example 1 The surface layer base material was glass fiber with a filament diameter of 9μ, the number of vertical strokes was 42/25 m, and the number of horizontal strokes was 32/2.
A 5M glass fiber woven fabric was used, and a polyethylene terephthalate fiber nonwoven fabric with a filament diameter of 30 μm, a basis weight of 100 g/nf, and a thickness of 0.2 mm was used as the core layer base material.

Hereinafter, as in Example 1, the varnish was used to obtain a thickness of 1.
Six epoxy resin copper-clad laminates were obtained.

Comparative Example 2 As a base material, the glass fiber woven fabric used as the surface layer base material in Comparative Example 1 was used for all layers, and the varnish was used in the same manner as in Example 1 to form an epoxy resin with a thickness of 1.6 cm. A steel clad laminate was obtained.

Regarding the copper-clad laminates obtained in each of the above cases, dielectric constant, punching workability, diameter of through-hole after heat treatment, etc. were measured. The results obtained are shown in Table 1.

(Effects of the Invention) As is clear from the above results, the copper-clad laminate of the present invention has a glass fiber woven fabric as a base material, or a glass fiber woven fabric as a surface layer base material and a core layer base material. Compared to those using polyethylene terephthalate fiber nonwoven fabric as the material, the dielectric constant is the same or lower, the punching processability is excellent, and the diameter of the through hole is hardly narrowed.

Therefore, it is most suitable for circuit boards that require high frequency characteristics.

Claims (1)

[Claims] (1) A prepreg is obtained by impregnating a woven fabric with a resin using a yarn made of 30 to 80% by weight of polyethylene terephthalate fibers and 70 to 20% by weight of glass fibers as warp and weft yarns, which is then woven in a predetermined number of sheets. A method for manufacturing a copper-clad laminate, which comprises laminating the sheets, placing copper foil on one or both sides, and forming the sheets under heat and pressure.