JP2000022302A - Laminate for laser punching and method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable punching wherein irregularity of hole diameter is little, by setting either a gap between neighboring warp or a gap between neighboring weft in woven fabric to be a length in a specified range. SOLUTION: Woven fabric 10 is formed in a cloth type by weaving a thread formed by bundling many inorganic fibers such as glass and organic fibers such as a polyester, polyamide, polyacryl and polyimide. In this woven fabric 10, either a gap (x) between neighboring warps 12 or a gap (y) between neighboring wefts 14 is set in a range of 0-50 μm. The woven fabric 10 wherein either the gap (x) between the warps or the gap (y) between the wefts is 0-50 μm is used for a laminate. When a hole 30 is made in the laminate by using a laser beam, the area of a part where the gap (x) between the warps and the gap (y) between the wefts overlap with each other is narrowed, decomposition of cured resin 20 is made hard to expand, and irregularity of the hole diameter can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser drilling method for a laminate, wherein the laser is used to drill a laminate.
And a laminate used in the method.

[0002]

2. Description of the Related Art Laminated boards are used in the manufacture of printed wiring boards used for electric and electronic equipment. This laminated plate is formed by stacking a required number of prepregs impregnated with a thermosetting resin composition on a woven fabric such as a glass cloth, and arranging metal foils on both outer sides to form a body to be pressed. The crimped body is manufactured by heating and pressurizing by sandwiching it between molding presses. And when manufacturing a printed wiring board, after forming a hole in the laminated board by drilling, plating and the like are performed on the hole, and the metal foil on the front and back of the laminated board is electrically connected, and then It is manufactured by a method of etching a metal foil on the front and back of a laminate to form a circuit.

With the recent progress of high-density mounting of printed wiring boards and the like, very small holes are required to be formed in the laminated board. If a very small diameter hole is to be formed by drilling, the mechanical strength of the drill will be insufficient and the drill will be broken, so the frequency of drill replacement will increase and the productivity will be low. Therefore, in recent years, a method of drilling using a laser beam such as a carbon dioxide laser beam has been studied instead of the manufacturing method using the drill. However, there is a problem that the hole diameter is more likely to vary when drilling using a laser beam than when drilling using a drill. Therefore, there is a demand for a laser drilling method for a laminated board whose hole diameter is less likely to vary even when laser light is used.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to heat a prepreg obtained by impregnating a woven fabric with a thermosetting resin composition. It is an object of the present invention to provide a laser drilling method for a laminate obtained by punching a laminate obtained by pressurization using a laser beam, wherein the laser drilling is performed on a laminate having a hole diameter that is less likely to vary.

[0005] Further, a laminated plate obtained by heating and pressing a prepreg obtained by impregnating a woven fabric with a thermosetting resin composition,
It is an object of the present invention to provide a laser drilling laminate in which a hole diameter is less likely to vary even when drilling is performed using laser light.

[0006]

According to a first aspect of the present invention, there is provided a method for laser drilling a laminated board, comprising the steps of: heating and pressing a prepreg obtained by impregnating a woven fabric with a thermosetting resin composition; In a laser drilling method for a laminated board that is drilled using laser light, the woven fabric has a gap between a warp and an adjacent warp, and at least one of a gap between a weft and an adjacent weft has a size of 0 to 50 μm. It is a woven fabric.

According to a second aspect of the present invention, there is provided the laser drilling method for a laminated board according to the first aspect, wherein at least one of the warp and the weft has an aspect ratio of 15: 1 to 30. : 1 thread.

[0008] The laminated plate for laser drilling according to claim 3 of the present invention is a woven fabric in which at least one of a gap between a warp and an adjacent warp and a gap between a weft and an adjacent weft is 0 to 50 µm. The prepreg impregnated with the thermosetting resin composition is heated and pressurized.

According to a fourth aspect of the present invention, there is provided the laminated plate for laser drilling according to the third aspect, wherein at least one of the warp and the weft has an aspect ratio of 1 or more.
It is a yarn of 5: 1 to 30: 1.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for laser drilling a laminate according to the present invention will be described with reference to the drawings. 1A and 1B are diagrams illustrating an embodiment of a laser drilling method for a laminated plate according to the present invention, wherein FIG. 1A is a plan view illustrating a state in which a hole is drilled, and FIG. FIG. 2 is a front view illustrating a cross section of a laser drilling laminate according to the present invention). FIG. 2 is a plan view illustrating another embodiment of the laser drilling method for a laminated plate according to the present invention, in which a hole is drilled. Also,
3A and 3B are diagrams illustrating a conventional laser drilling method for a laminated plate, and FIG. 3A is a plan view illustrating a state in which a hole is drilled;
(B) is a front view explaining the cross section of a laminated board.

The method for laser drilling a laminate according to the present invention is directed to a laminate obtained by heating and pressing a prepreg obtained by impregnating a woven fabric with a thermosetting resin composition (the laminate for laser drilling according to the present invention). This is a laser drilling method for a laminated plate in which a laminate is drilled using a laser beam.

The woven fabric is made of inorganic fibers such as glass,
It is formed by weaving a yarn formed by converging a large number of organic fibers such as polyester, polyamide, polyacryl, and polyimide, and is formed into a cloth. The thickness of the woven cloth 10 is 0.04 to 0.3 mm. Is commonly used. Note that the use of a glass fiber woven fabric (glass cloth) is preferable because the resulting laminate has excellent heat resistance and moisture resistance.

As shown in FIG. 1, the woven fabric 10 has a gap x between a warp 12 and an adjacent warp 12 (hereinafter referred to as a warp gap x).
And a gap y between the weft thread 14 and the adjacent weft thread 14.
(Hereinafter referred to as a weft yarn gap y) at least one of 0 to 5
It is important that the woven fabric 10 is 0 μm. Warp gap x
When both the weft and the weft gap y exceed 50 μm, the hole diameter is liable to vary when drilling using laser light.

In the portion of the laminated board where the warp yarn gap x and the weft yarn gap y are provided, the ratio of the cured resin 20 obtained by curing the thermosetting resin composition is higher than that of the portion having the warp yarns 12 and the weft yarns 14. . In addition, when laser light is applied, since the thermal decomposition temperature is different between the cured resin 20 and the warp 12 or weft 14, even when the same amount of laser light is applied, the cured resin has a low thermal decomposition temperature. The resin 20 is largely decomposed.

For this reason, as shown in FIG.
Conventional woven fabric 1 in which both the weft yarn gap y exceeds 50 μm
When a hole 30 is formed by using a laser beam in the laminated board using the No. 0, the cured resin 20 in the portion where the warp yarn gap x and the weft yarn gap y overlap greatly expands and is easily decomposed, and the diameter of the hole 30 increases. It will be easier. However, as shown in FIG.
At least one of the warp gap x and the weft gap y is 0 to 50.
In the case of a laminated board using the woven fabric 10 μm, the yarn (12, 1
Since the distribution of 4) is more uniform, the area where the warp yarn gap x and the weft yarn gap y overlap is reduced, and the decomposition of the cured resin 20 is less likely to spread, and the hole diameter is less likely to vary.

The woven fabric 10 may be a woven fabric 10 in which at least one of the warp gap x and the weft gap y has a size of 0 to 50 μm, and as shown in FIG.
m, the diameter of the hole drilled using laser light is
It is particularly preferable because it hardly varies.

As a method of manufacturing the woven fabric 10 in which at least one of the warp gap x and the weft gap y is 0 to 50 μm, for example, a general woven fabric 10 having the warp gap x and the weft gap y of 50 μm or more is used. A method in which the fibers constituting the yarn are opened by passing between pressurized rolls, or a high-pressure water is sprayed on the surface of a similar general woven fabric 10 to open the fibers constituting the yarn. Woven fabric using a yarn that has been previously opened between fibers by the above-described method.
And the like.

The degree of the opening is such that at least one of the warp yarn 12 and the weft yarn 14 has an aspect ratio of 15: 1 to 3
It is preferable to open the yarn so that the yarn becomes 0: 1 because at least one of the warp gap x and the weft gap y can easily produce the woven fabric 10 having a thickness of 0 to 50 μm. The flatness is a value represented by the width of the yarn: the thickness of the yarn.

The conditions for irradiating the laser beam for drilling the hole 30 using the laser beam include the thickness of the laminate,
It is appropriately adjusted according to the material, hole diameter, and the like of the warp yarn 12, the weft yarn 14, and the cured resin 20. Examples of the laser light include a carbon dioxide laser light and an infrared laser light.

When a laminate is manufactured using the woven fabric 10, a prepreg is manufactured by impregnating the woven fabric 10 with a thermosetting resin composition, and then a conductor circuit is formed as necessary. A predetermined number of the prepregs are stacked while sandwiching the substrate, and metal foils are arranged on both outer sides of the prepregs as necessary. It is sandwiched between presses and heated and pressed to produce. In the case where the number of prepregs to be used is one, the effect that the hole diameter of the hole 30 formed by using laser light is less likely to vary is particularly large and preferable.

The thermosetting resin composition includes:
The entire thermosetting resin composition can be used, such as a single resin, a modified resin, or a mixture of an epoxy resin, a phenol resin, a polyimide resin, and an unsaturated polyester resin. The thermosetting resin composition contains a thermosetting resin as an essential component, and may contain a curing agent, a curing accelerator, an inorganic filler, and the like for the thermosetting resin as necessary. In addition, when the thermosetting resin composition is an epoxy resin type, a laminate having an excellent balance between electrical properties and adhesiveness can be obtained, which is preferable.

The method for producing the prepreg by impregnating the woven fabric 10 with the thermosetting resin composition is not particularly limited. For example, a varnish obtained by adjusting the viscosity of the thermosetting resin composition with a solvent may be used. After the cloth 10 is dipped and impregnated, it is heated and dried as necessary to be semi-cured, or the thermosetting resin composition is heated and melted without using a solvent to obtain the woven fabric 1.
It is manufactured by impregnating with 0. The amount of resin in this prepreg is
It is preferably 40 to 70 parts by weight based on 100 parts by weight of the prepreg (the total weight of the thermosetting resin composition and the woven fabric 10). If the amount is less than 40 parts by weight, the heat resistance of the obtained laminate may decrease, and if it exceeds 70 parts by weight, the thickness of the obtained laminate may vary greatly.

The metal foil is not particularly limited as long as it is a metal foil.
A single, alloy, or composite foil of brass, nickel, or the like can be used. The thickness of the metal foil is generally 5 to 70 μm. In addition, when drilling using a laser beam on a metal foil-clad laminate obtained using a metal foil,
After exposing the hardened resin 20 and the like by etching and removing the metal foil at the position where the drilling is to be performed in advance, laser beam irradiation is performed to drill the hole.

The conditions for heating and pressurizing the prepreg may be appropriately adjusted under the conditions for curing the thermosetting resin composition in the prepreg, and heating and pressurizing may be performed. Since air bubbles may remain inside the obtained laminate, it is preferable to apply pressure under conditions that satisfy moldability.

[0025]

EXAMPLES Example 1 As a thermosetting resin composition, an epoxy resin (tetrabromobisphenol A type epoxy resin having an epoxy equivalent of 500 [YDB-500 manufactured by Toto Kasei Co., Ltd.]) was used as a solid content. 80 parts by weight, 3 parts by weight of a curing agent (dicyandiamide [manufactured by Nippon Carbide Co., Ltd.]), and a curing accelerator (2-ethyl-4)
-Methylimidazole [manufactured by Shikoku Chemicals]).
An epoxy resin-based thermosetting resin composition mixed and mixed in 2 parts by weight was used.

A glass cloth having a warp gap and a weft gap both of 0 to 5 μm was used as the woven fabric. In addition, this glass cloth is a 0.06 mm-thick glass cloth [manufactured by Asahi Schwebel Co., Ltd., trade name 1080], in which both the warp gap and the weft gap exceed 50 μm, and the surface pressure is 100 kg /
By passing between the rolls pressurized to a diameter of 1 cm, the fibers constituting the yarn were opened to produce.

Then, a glass cloth is immersed and impregnated in the thermosetting resin composition whose viscosity has been adjusted by adding a solvent,
Then, it is dried by heating at a maximum temperature of 180 ° C.
A 7% by weight prepreg was obtained.

Next, a copper foil having a thickness of 35 μm is arranged on both outer sides of one of the prepregs to form a body to be crimped. Then, 10 sets of the bodies to be crimped are sandwiched between forming presses, and the maximum temperature is 170 ° C. Heating and pressing were performed at a pressure of 3.4 MPa for 90 minutes to obtain a copper foil-clad laminate having an insulating layer thickness of 0.07 mm.

(Example 2) By passing between rolls pressurized to a surface pressure of 80 kg / cm, the yarns constituting the yarn were opened to produce a warp yarn gap and a weft yarn gap.
A copper foil-clad laminate was obtained in the same manner as in Example 1 except that a glass cloth of 0 to 30 μm was used.

Comparative Example 1 A laminated board was obtained in the same manner as in Example 1 except that the glass cloth before the fiber opening treatment was used.

(Evaluation and Results) The copper foil-clad laminates obtained in the respective Examples and Comparative Example 1 were perforated by using a laser beam, and the variation in the hole diameter was evaluated. In this method, the copper foil on the surface of the obtained copper foil-clad laminate was entirely removed by etching, and then laser light was irradiated under the following three conditions to form 20 holes. Next, the hole diameters of the 20 holes were measured using a magnifying glass, and the maximum value, the minimum value, the difference between the maximum value and the minimum value, and the variation (σ) were determined. In addition,
For the hole diameter, the maximum diameter of each hole was defined as the hole diameter of each hole.

The irradiation conditions of the laser light include a carbon dioxide gas laser (trade name: ML-60, manufactured by Mitsubishi Electric Corporation).
5], the irradiation energy is 26 mJ / pulse,
Pulse length 28 μs, irradiation energy 55 mJ /
Pulse, pulse length 48μs, irradiation energy 8
The test was performed under three conditions of 0 mJ / pulse and a pulse length of 72 μs.

The results show that, as shown in Table 1, the laminated plate obtained in each example had a larger hole diameter than the laminated plate obtained in Comparative Example 1 under any irradiation conditions. It was confirmed that drilling with small variation was possible.

[0034]

[Table 1]

[0035]

According to the first and second aspects of the present invention, the method for laser drilling a laminated board is characterized in that a laminated board manufactured by using a woven fabric in which at least one of a warp gap and a weft gap is 0 to 50 μm. Since light is used to make a hole, it is possible to make a hole with a small diameter.

The laminated plate for laser drilling according to the third and fourth aspects of the present invention is a laminated plate in which at least one of the warp gap and the weft gap is manufactured using a woven fabric of 0 to 50 μm. Even in the case of drilling using light, the hole diameter is less likely to vary.

[Brief description of the drawings]

FIGS. 1A and 1B are diagrams illustrating an embodiment of a laser drilling method for a laminated plate according to the present invention, wherein FIG. 1A is a plan view illustrating a state in which a hole is drilled, and FIG. It is a front view explaining the section of the laser drilling laminated board concerning the present invention).

FIG. 2 is a plan view illustrating a state in which a hole is drilled in another embodiment of the laser drilling method for a laminate according to the present invention.

3A and 3B are views for explaining a conventional laser drilling method for a laminated plate, and FIG. 3A is a plan view illustrating a state in which a hole is drilled;
(B) is a front view explaining the cross section of a laminated board.

[Description of Signs] 10 Woven cloth 12 Warp 14 Weft 20 Cured resin 30 Hole x Warp gap (Gap between warp and adjacent warp) y Weft gap (Gap between weft and adjacent weft)

Claims (4)

[Claims] 1. A method for laser-piercing a laminate obtained by heating and pressurizing a prepreg obtained by impregnating a woven fabric with a thermosetting resin composition using a laser beam. However, at least one of the gap between the warp and the adjacent warp and the gap between the weft and the adjacent weft is 0 to 50 μm
Laser drilling method for a laminated plate, characterized by being a woven fabric. 2. The method according to claim 1, wherein at least one of the warp yarn and the weft yarn is a yarn having an aspect ratio of 15: 1 to 30: 1. 3. A gap between a warp and an adjacent warp and / or a gap between a weft and an adjacent weft is 0 to 50 μm.
A prepreg obtained by impregnating a woven fabric with a thermosetting resin composition into a woven fabric by heating and pressing. 4. The laminated plate for laser drilling according to claim 3, wherein at least one of the warp yarn and the weft yarn is a yarn having an aspect ratio of 15: 1 to 30: 1.