JPS61258043A - Cloth for printed circuit board and printed circuit board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a cloth for a printed circuit board and a printed circuit board.

[Technical Background and Problems of the Invention] Conventional printed circuit board cloths are made of inorganic fibers such as non-alkali glass yarn (for example, JIS R34
13) is common, and in very small quantities, quartz glass fiber cloth is used. All of these fibers are manufactured by the melting method, and the cross-sectional shape of the single fiber is almost a perfect circle or a circle close to a perfect circle, so it can be said that it is actually circular.The cloth made by weaving these fibers is (For example, JIS R3
414) is a molded product using unsaturated polymeric hetero resin, epoxy resin, phenol resin, etc. as a binder, for example, when it is used as a base material for a printed circuit board, it is first subjected to heat cleaning etc. The sizing agent is removed by this method, and the cloth is used as a treated cloth (for example, as described in JIS R341B) that has been surface-treated with a chromium-based treatment agent or a silane-based treatment agent to strengthen the adhesion with the resin. Ru.

A printed circuit board is a laminated board made by laminating treated cloth using resin as a binding material. The number of layers is usually 4 to 8.
However, in multilayer laminates (hereinafter referred to as multilayer boards), there are several layers of lO, and some have more than that. A laminate with copper foil laminated on one or both sides is called a copper-clad laminate for printed circuits.

Glass cloth used as cloth for printed circuit boards has a thickness of approximately 0.03 to 0.18 mm and a weight of 25 to 20 mm.
Plain weave alkali-free glass cloth with a weight of about 0 g/fTI' is common. The characteristics of Ross as a base material for printed circuit boards include its electrical properties, mechanical properties, chemical resistance, non-water absorbing properties, and especially its nonflammability, heat resistance, and one-dimensional stability. In addition, the quality standards are stricter than those for general glass cloth, with particularly strict requirements regarding the uniformity of numerical specifications and appearance defects.

In particular, when the printed circuit board is a multilayer board, among the characteristics that the multilayer printed circuit board or the copper-clad laminate for multilayer printed circuits (hereinafter simply referred to as multilayer board) should have, especially the glass cloth that is the base material. Dimensional stability (rate of change) is one of the properties that largely depends on the resin. According to JIS 08488-1980, the dimensional stability of copper-clad laminates for multilayer printed circuits (glass fabric base epoxy resin) (rate of change) after etching, 0.05% or less, after heat treatment.

0.05% or less is required. A multilayer board made of glass cloth made of ordinary alkali-free glass thread satisfies this requirement, but as the number of laminated layers increases, this requirement becomes more severe. .

Dimensional stability (rate of change) in JIS 0848B-1980 refers to the dimensional change rate after removing the copper foil by etching of a test piece cut out with its original thickness, and the dimension after removing the copper foil and the dimension after treatment at 170°C for 30 minutes. It is the rate of change in dimension after cooling to room temperature. Factors that contribute to the dimensional stability include thermal properties such as the thermal expansion coefficient of the resin, the thermal expansion coefficient of the glass, and the strength of the bond between the resin and the glass.In order to improve the 0-dimensional stability, it is important to Possible factors include a small coefficient of thermal expansion, good returnability to the original size before and after heating, a small coefficient of thermal expansion of glass (usually smaller than that of resin), and a stronger bond between the resin and glass.

[Object of the Invention] The present invention provides a printed circuit board, which is a cloth made of inorganic fibers and is characterized in that when molded together with a resin to form a printed circuit board, a printed circuit board with excellent dimensional stability is obtained. The purpose is to provide cloth for use.

An object of the present invention is to provide a printed circuit board with excellent dimensional stability, which is made of a cloth made of inorganic fibers and a resin.

[Means for achieving the purpose of the invention] The cloth of the present invention has a cross-sectional shape of single fibers.

This cloth for printed circuit boards is mainly composed of inorganic fibers having a "dogleg" shape and/or inorganic fibers having a cross-sectional shape of a single fiber having a concave portion in a part of the "dogleg" shape.

Moreover, the printed circuit board of the present invention is made of the above-mentioned cloth for printed circuit boards and resin.

Inorganic fibers include E-glass fibers, 15-E glass fibers, glass fibers of other compositions, and the term cloth includes untreated cloth, treated cloth, and roving cloth.

Examples of inorganic fibers having the above-mentioned cross-sectional shape include quartz glass fibers obtained by a sol-gel direct spinning method.

The sol-gel direct spinning method is the hydrolysis and polymerization of metal alcoholates (ethyl silicate, methyl silicate, etc.) using an acid or alkali as a catalyst to create a vine liquid, and once it has an appropriate viscosity (10 to 1,000 poise), The sol solution is extruded from a nozzle and spun to create gel fibers. In this state, a lot of carbon such as alkoxide still remains in the fiber, and the tensile strength of the fiber is low.
A heat treatment is performed at 700 to 1300° C. for several minutes to several hours to volatilize residual carbon, and the mixture is fired to obtain a high-strength quartz glass fiber.

Conventionally, 2 quartz glass fibers have been created by the melting method, which involves melting high-purity silica sand at 1,600 to 1,800°C to create a cylindrical precursor of silica glass, which is then remelted using a gas burner to form fibers. Create. This requires a huge amount of energy and results in extremely expensive fibers, but the sol-gel method only requires heat treatment at a temperature of 1,200 to 1,300° C., resulting in inexpensive quartz gas fibers.

As mentioned above, the sol-gel direct spinning method involves spinning a sol solution obtained by hydrolyzing a metal alcoholate using an acid or alkali as a catalyst.
When a starting material consisting of metal alcoholate, cellulose acetate, water, a catalyst, and acetone for diluting the water is used, a single fiber having a dogleg shape in cross section can be obtained.

In the present invention. Figure 1 (a) shows some aspects of the cross-sectional shape of a single silica glass fiber obtained by the sol-gel direct spinning method.
) and (b), FIG. 1 (a) shows a cross-sectional shape with a dogleg shape, and (b) shows a cross-sectional shape with a gentle curve on the outside of the dogleg curve. In the present invention, the cross-sectional shape of the above-mentioned cross-sectional shape (b) is referred to as a "dog-shaped" cross-sectional shape, and the cross-sectional shape of the above-mentioned (b), including the non-41 fibers, is defined as a monofilament. (a) and (b), which are called inorganic fibers with a dogleg-shaped cross-section, have an axis of symmetry in an approximate sense. In the invention, the "kunoji" shape (
Both a) and (b) have a gentle curved shape, and (a) has a concave portion A in two parts.

Figure 2 shows the degree of curvature of the dogleg shape cross section
It is represented by the angle α shown in a) and (b), and α is called the curvature angle. α is as shown in Figure 2 (a) and (b),
Stand the "dogu-shaped" cross section of the single fiber perpendicular to the horizontal plane with the inside curved side facing downward, and point the contact points with the horizontal plane at A and B.
If the midpoint of line segment AB is M, the perpendicular bisector of line segment AB is ax, and the intersection of m and the inside part of the curve of the "dog-shaped" cross section is O, then OA and OB are The angle formed is 1 AOB. In FIGS. 2(a) and 2(b), the straight line is the straight line connecting A and B on the horizontal plane. ! Points A and B are the points of contact between L and the doglegged cross section. When measuring α, draw a straight line with points of contact on both convex portions forming the inner part of the curve in a “dog-shaped” cross section or a curved shape obtained by similarly enlarging the cross section, and connect the point of contact to A. . , B, </AOB may be obtained as described above.

Furthermore, if it is difficult to find the above-mentioned contact point, there is no practical problem as long as it can be regarded as a point in an approximate sense.

The preferable range of α in the inorganic fiber of the present invention, the quartz glass fiber produced by the sol-gel direct spinning method, is as follows:
The range is 80'll≦α≦170°, and more preferably the range is 90°≦α≦170'.

When the ratio of acetone to water is increased in the starting material described above, the cross-sectional shape of the single fiber becomes as shown in FIG. 1(b).
The shape gradually changes from the "dogleg" shape to the "dogleg" shape shown in FIG. 3(a). That is, the cross-sectional shape of FIG. 1(a) and the cross-sectional shape of FIG. 1(b) are of the starting materials described above! &min are the same, they simply correspond to different ratios of acetone to water.

If the bending angle α is too small, when impregnating with resin to make a laminate, the opening of the “dog” curved part will be narrow, making it difficult for the resin to penetrate into that part. The effect of increasing the surface area of the single fibers to strengthen the bond with the fibers becomes difficult to achieve. This is because, as a matter of course, there is no bond between the single fiber and the resin in the surface portion of the single fiber where no resin exists. Furthermore, it is known that α cannot be very large due to the composition of the starting materials.

Inorganic fibers whose single fibers have a dogleg-shaped cross-section and/
Alternatively, the weavability when making a cloth mainly made of inorganic fibers in which the cross-sectional shape of the single fibers has the above-mentioned dogleg shape and at least a portion of the concave portion is compared to that of cloth made of conventional inorganic fibers. Furthermore, the removal of the sizing agent by heat cleaning or the like and the surface treatment with various treatment agents of the cloth according to the present invention are not particularly different from those of conventional cloths.

Further, the drill workability of the printed circuit board of the present invention is not particularly different from that of conventional products.

In addition, the tensile strength of the single fiber of the inorganic fiber in the present invention is determined by the spinning process, the subsequent processing process, and the weaving process.
Approximately 15 kg/sm considering workability and quality aspects.
It is desirable to have 2 or more.

The thickness of the printed circuit board cloth of the present invention is 0.025
~0.40mm, preferably 0.030 NO, 30■
1 weight force 15~450 g/m'', special weight 15~300
g/rn' (7) range is preferred.

If it becomes thinner than the above range or its mass becomes lighter, the reinforcing effect of the cloth when used as a substrate becomes smaller, and the intended purpose cannot be achieved. However, when used for multilayer boards, a cloth as thin as the one described above is required, but on the other hand, since it is used for printed circuit boards, an extremely thick cloth is not necessary, and cloths of various thicknesses can be prepared.

Instead of a small number of thick cloths, a larger number of thinner cloths can be used without changing the total weight of the cloth in the board, or vice versa, while taking into account the reinforcing effect, workability, etc. You can expand your range of choices.

The cloth for printed circuit boards of the present invention is an inorganic fiber whose single fibers have an i-shaped cross-sectional shape, and/or a single fiber whose cross-sectional shape has a concave portion in at least a part of the "dogleg" shape. A printed circuit board cloth mainly composed of inorganic fibers with a weight ratio of 40-10.
0%, preferably in the range of 50-100%.

The inorganic fibers constituting the cloth are generally twisted yarns made of the above-mentioned single fibers, but they can also include strands, slivers, rovings made of them, aligned yarns, etc. (from twisted yarns to aligned yarns, these are collectively called (hereinafter referred to as "teito").

The inorganic fibers of the cloth for printed circuit boards of the present invention may include monomolecular fibers having a cross-sectional shape other than the above-described cross-sectional shape.

In addition to single fibers having the above-mentioned cross-sectional shapes, the threads made of inorganic fibers constituting the cloth may also contain single fibers having cross-sectional shapes other than the above-mentioned cross-sectional shapes, and yarns in the warp direction of the cloth (so-called Either the warp yarn or the weft yarn (so-called weft yarn) may be made of a single fiber yarn having a cross-sectional shape other than the above-mentioned cylindrical shape, for example, fused silica glass fiber.

First, the sizing agent is removed from the above-mentioned printed circuit board cloth by a method such as heat cleaning, and then the surface is treated with a chromium-based treatment agent or a silane-based treatment agent to strengthen the adhesion with the resin. The printed circuit board of the present invention is made by laminating the above-treated printed circuit board cloth using resin as a bonding material. As mentioned above, it is common to laminate in the form of prepreg.

Examples of the above resin include unsaturated polyester resin,
Epoxy resin, phenol resin, etc. [Function] The printed circuit board, which is the technical field of the present invention, is a so-called composite material of inorganic fiber and resin, and the inorganic fiber has the function of reinforcing the resin. Incorporation of fibers into glass fibers As mentioned above, the surface of the glass am is treated with a chromium-based treatment agent or a silane-based treatment agent to strengthen the adhesion between the glass fibers and the resin.

In order to improve the dimensional stability of printed circuit boards specified in JIS 0848 & -1980, the coefficient of thermal expansion of the resin is small, the ability to return to the original size before and after heating is good, and the thermal expansion of glass fiber is required. These include a small modulus (usually smaller than resin) and a stronger bond between resin and glass fiber. In order to reduce the coefficient of thermal expansion of glass fibers, it has been considered and put into practice to use quartz glass fibers instead of ordinary E-glass fibers.

The present invention uses inorganic fibers that make up the cloth.

"Dog" shaped cross-sectional shape and/or the "Dog"
It is based on the fact that the adhesive force between the cloth and the resin is increased by mainly using single fibers having a cross-sectional shape having a concave portion in at least a part of the cloth.

If other conditions are constant, the adhesive force between inorganic fibers that are reinforcing materials for printed circuit boards and resin is proportional to the surface area of the inorganic fibers that are in contact with the resin at the interface. Instead of considering a large number of inorganic fibers, consider a single fiber as a representative. Considering a cross section perpendicular to the longitudinal direction of a single fiber of an inorganic fiber, the ratio of the surface areas of various fibers with the same composition and equivalent physical properties is equal to the ratio of the peripheral length of the cross section of the single fiber. It may be considered that fibers having the same weight are fibers having the same cross-sectional area. After all, in order to compare the surface area of the various fibers of the same weight, assuming that the inorganic fiber content of the printed potato substrate is constant, it is necessary to compare the peripheral lengths of the cross sections when the areas of the cross sections are the same. Bye. In the present invention, when the area of the cross-sectional shape of a single fiber that is a planar figure is constant, the shortest peripheral length is circular. We propose a cloth made of inorganic fibers that has a large surface area, a cross-sectional shape that is not circular but a dogleg shape, and/or a cross-sectional shape that has four parts in at least a part of the dogleg shape. At the same time, the present invention proposes a printed circuit board having the cloth as a reinforcing material.

[Example] A plain weave cloth made of sol-gel direct spun quartz glass fiber of the present invention, a plain weave cloth made of ordinary E-glass fiber, and a plain weave cloth made of fusible silica glass fiber of the present invention shown in Table 1 were selected as base materials. After heat cleaning, the surface was treated with epoxy silane and impregnated with a heat-resistant epoxy resin to make a prepreg. This was formed into 8 layers to form a laminate.

The dimensional stability (rate of change) of the laminate test piece 280 x 280 x 280 was measured in accordance with JIS CE1488. Dimensional stability in the JIS is 170℃
This is the dimensional change rate of the laminate test piece before and after treatment for 30 minutes. The measurement results are shown in Table 2.

As a comparative example, a laminate made of E-glass fiber cloth and a laminate made of fusible quartz glass fiber cloth were compared.
The laminate made of the sol-gel direct spun quartz glass fiber cloth of the present invention has excellent dimensional stability.

[Effect of the invention] The cloth of the present invention has the same weave and the same density.

The total surface area of the single fibers is larger than that of a conventional cloth of the same quality 1k (g/rn').For example, the cross-sectional shape of the single fiber shown in Figure 1(a) is αΦ 110°, but its circumference is is about 1.4 times the circumference of a circular cross-section single fiber having the same cross-sectional area, and therefore the total surface area of the single fiber is also about 1.4 times. Furthermore, the cross-sectional shape of the single fiber shown in Figure 1(b) is 118° in α, but its perimeter is approximately 1 of the perimeter of a circular cross-section single fiber with the same cross-sectional area.
．． 35 times, and therefore the total surface area of the single fibers is also approximately 1.
It is 35 times more.

Because of the above-mentioned properties of the cloth of the present invention, a printed circuit board made of a composite material such as the cloth of the present invention and an unsaturated polyester resin, an epoxy resin, or a phenolic resin can be made of a resin material more easily than a conventional cloth. The overall adhesion between the and cross is strong. When the external environmental temperature of the printed circuit board increases, the cloth has the effect of suppressing the free expansion of the resin, which has a higher thermal expansion coefficient, but
Since the cloth of the present invention has a much stronger adhesion to the resin than conventional cloths, it also has a greater effect of suppressing the expansion of the resin.

This effect of suppressing the expansion of the resin from free expansion can also be obtained by selecting a material with the lowest possible coefficient of thermal expansion as the material for the cloth.

In fact, instead of the widely used E-glass fiber, a cloth made of quartz glass fiber, which has a smaller coefficient of thermal expansion, is sometimes used.6 Even when using a cloth made of quartz glass fiber, the cross-sectional shape is better than a single fiber with a circular cross-sectional shape. In the present invention, the cloth made of yarn made of single fibers having a cross-sectional shape has a greater effect of suppressing the free expansion of the resin.

Since the above-mentioned effect of suppressing the free expansion of the resin is more remarkable than that of conventional cloth, the printed circuit board made of the composite material having the claw-i component of the present invention is more effective than that of conventional cloth. Excellent dimensional stability.

In addition, the cloth of the present invention is made of inorganic fibers in which the constituent threads are inorganic fibers whose single fibers have a dogleg shape in cross section and/or inorganic fibers in which at least a part of the dogleg shape has a concave portion. Because of this, the single fibers and yarns are less likely to shift from each other, and therefore, the disadvantages of cloth, such as thread misalignment and fiber fraying, are less likely to occur.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the cross-sectional shape of a single silica glass fiber obtained by the sol-gel direct spinning method in the present invention. (a) is an aspect of the cross-sectional shape of a “dog” shape,
(b) is a cross-sectional view showing an aspect of the cross-sectional shape in which the outer side of the "dog-shaped" curve is gently curved. A shows a part of the concave part of the cross section, and Fig. 2 shows the curvature angle α.
Figure 1 (6, tb) Part 2 ■ (Revised) (b)

Claims (4)

[Claims] (1) Mainly composed of inorganic fibers whose single fibers have a dogleg-shaped cross-section and/or inorganic fibers whose cross-sectional shape has a recess in at least a part of the dogleg shape. A cloth for printed circuit boards. (2) The printed circuit board cloth according to claim 1, wherein the inorganic fiber is a quartz glass fiber produced by a sol-gel direct spinning method. (3) Mainly composed of inorganic fibers whose single fibers have a dogleg shape in cross-section and/or inorganic fibers whose cross-sectional shape has a recess in at least a part of the dogleg shape. A printed circuit board made of printed circuit board cloth and resin. (4) The printed circuit board according to claim 3, wherein the inorganic fiber is a quartz glass fiber produced by a sol-gel direct spinning method.