JPH0347746A - Laminated sheet - Google Patents

Abstract

PURPOSE:To reduce the internal stress in base material fabric itself and make it possible to remarkably reduce the warp and twist of laminated sheet made of the base material fabric by a method wherein the warps of the base material fabric consisting of Z twist yarns and S twist yarns arranged in the ratio of the former to the latter of the specified one. CONSTITUTION:When Z twist yarn (or S twist yarn) is used as the woof consisting of the base material of laminated sheet, the warp consists of S twist yarn (Z twist yarn) and Z twist yarn (S twist yarn) uniformly arranged in the ratio of the former to the latter of 1:2 - 8. For example, the warp consists of warp 1 made of glass fiber monofilament of ECG-75 1/0-1Z and warp 2 made of glass fiber monofilament of ECG-75 1/0-1S, the ratio of the former to the latter of 3:1. The woof 3 is made of glass fiber monofilament of ECG-75 1/0-0.7Z.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a laminate used as a substrate for printed wiring boards and the like, and particularly to a laminate with less warpage and twist. In the present invention, laminates include, in addition to those based on textiles,
It also includes so-called composite-type laminates based on a combination of woven and non-woven fabrics.

[Conventional technology]

A laminate or a copper-clad laminate is manufactured by laminating a predetermined number of prepregs obtained by impregnating a substrate with a resin and drying the prepregs, and if necessary, layering copper foil on the surface and applying pressure. In the field of printed wiring boards, which is the main application for copper-clad laminates, with the advancement of high-density automatic mounting technology, requirements for the performance of printed wiring boards have become even more stringent. There is an increasingly strict requirement for less warping and twisting.

[Problem to be solved by the invention]

The causes of warping and twisting in laminates are the type of laminate,
Although the extent of this difference varies depending on the manufacturing method and the type of material, the following reasons can be considered.

That is, (a) the existence of a tension difference in the warp direction and the weft direction in the manufacturing process, (El) application of press pressure, (c) flow of matrix resin during pressing, and (d)
Due to differences in expansion or contraction between the base material and the matrix resin due to temperature differences and differences in linear expansion coefficients, stress and strain mainly act on the base fabric or woven and nonwoven fabrics that are stress carriers, and their It is thought that warping and twisting occur as a result, and in the case of prior art laminates, this warping and twisting is so large that automatic equipment for installing printed wiring boards has been interrupted or rendered inoperable.

In addition to the conventionally known causes, the inventors have discovered the following causes of warping and twisting.

In other words, if there is a factor in the generation of internal stress and strain in the fabric itself, which is the base material of the laminate, the stress and strain from the outside due to the factors (a) to (d) above will be combined into the internal stress of the fabric itself.・
This results in large stress and strain, which manifests as warping and twisting of the laminate.In order to reduce this warping and twisting, it is necessary to reduce the internal stress and distortion of the fabric itself.
It is necessary to reduce distortion.

[Means to solve the problem]

The present invention was made based on such conventional problems and the knowledge of the inventor, and uses Z-twisted yarns (or S-twisted yarns) in the twisting direction regarding the weft yarns constituting the base material of the laminate. When doing so, the warp yarns are determined by the number of twists of the weft yarns, the tex of the weft yarns, and the number of weft yarns (strands/25mm).
By making the warp threads almost uniformly arranged in the twisting direction, with a ratio of 1 to 1 S strand (Z strand) to 2 to 8 Z strands (S strand), the warp and twist of the laminate are significantly improved. , the purpose is to solve problems.

In this case, it is preferable that the number of twists of the S-twisted yarn and the Z-twisted yarn used for the warp is the same. Fabrics used as the base material of the laminate include glass fiber fabrics, polyester fiber fabrics, and aramid fiber fabrics for special purposes. Generally, glass fiber fabrics are widely used as the base material for laminates, so the present invention will be explained with reference to the drawings in the case where the fabric that is the base material of the laminate is a glass fiber fabric. Currently, single yarn fabrics are the mainstream glass fiber fabrics. A single yarn fabric is a fabric in which the yarns constituting the fabric are single-twisted yarns that are lightly twisted (the number of twists is small).

The organization diagram shown in FIG. 1 is that of a glass fiber plain weave fabric. The warp of this fabric is ECG-75110 with warp 1.
-IZ glass fiber single yarn and warp 2 ECG-7511
It is composed of 0-IS glass fiber single yarns in a ratio of 3:1, and the weft 3 is composed of HCG-75110-0,72 (7) glass fiber single yarns.

The yarn count range used for the glass fiber fabric is preferably 5 to 150 in Tex. There are no particular restrictions on the shape, thickness, etc. of the filaments constituting the yarn, as long as they do not impede adhesiveness to the resin. The number of twists of the yarn is 0.3 to 3t/25M. If the number of twists is less than 0.3, the convergence of the filaments constituting the yarn will be insufficient and good workability in the weaving process will not be obtained. Because it is a single-twisted yarn, it is difficult to handle.

Regarding the structure of the fabric, the number of threads is 20 to 80/25m.
The mass of the fabric is 20 to 400 g/bore, and the weave of the fabric may be plain weave, satin weave, twill weave, etc.

Generally, woven fabrics used as base materials for laminates are treated with various treatment agents in order to improve adhesion with matrix resins, but there are no particular limitations on the type and amount of these treatment agents.

Further, the present invention is not particularly limited with respect to the uniformity of the woven fabric, the warp/weft warp, etc., and if these are improved, the effects of the present invention will be further improved.

The effects of the present invention are most noticeable when the thickness of the laminate to which the present invention is applied is 0.1 to 3.0 -.

As the matrix resin for the laminate, thermosetting resins such as epoxy resins, phenolic resins, polyimide resins, unsaturated polyester resins, and silicone resins, thermoplastic resins such as fluorine resins, etc. can be used. Alternatively, a mixture of a plurality of these resins can be used as a matrix resin.

The laminate of the present invention is obtained by treating the fabric having the above structure with a matrix resin by a conventionally known method to form a prepreg,
It can be obtained by laminating a plurality of sheets of this prepreg, overlapping metal foil on both sides or one side as necessary, and heating and pressurizing.

Furthermore, the composite-type laminate of the present invention uses a combination of the above-mentioned woven fabric and non-woven fabric as a base material, impregnates the above-mentioned resin to form a prepreg, and after laminating a plurality of prepregs, heats and heats the laminate. Obtained by pressing.

[For production]

Conventionally, the bending of the weft yarns of the fabric was thought to be a cause of warping and twisting in the base material itself.

The present inventors have discovered that there are other causes of warping and twisting in the fabric structure itself. Conventionally, in the case of glass single yarn fabrics used for laminates, the threads were lightly twisted, single-twisted yarns, but due to the heat setting effect during the oil removal process during manufacturing and the setting effect during the subsequent surface treatment, the twist was reduced. It is thought that the unbalanced twist was not noticed because the distortion caused by the unbalance was temporarily suppressed, and the warping and twisting required of the laminate was not as severe as it is today.

The present inventor noticed the unbalanced twist during research to improve the level of warping and twisting of laminates, and clarified the relationship between the warp and weft of textiles. That is, it has been found that warping and twisting of the laminate can be reduced by using every other S-twist yarn and Z-twist yarn in order to eliminate the bias in the twist in the warp direction.

However, it was insufficient because the twist bias in the weft direction remained.

Therefore, by uniformly inserting S-twisted yarn and Z-twisted yarn with opposite yarn twist directions into the warp yarns in a certain proportion, the distortion inherent in the entire fabric due to the unbalanced twist can be reduced, and as a result, this fabric can be used as a base material. We were able to reduce the warping and twisting of the laminate used as a material. The ratio is suitably in the range of 1/2 to 178, and is appropriately selected within this range depending on the type of fabric, for example, the warp and weft yarns used, and the number of yarns to be inserted.

〔Example〕

Example 1 A glass fiber fabric was used as the base material for the laminate of the present invention.

This glass fiber fabric is WEA-18W type and WEA
-19 types (both products of Nittobo Co., Ltd.) were used, and the present invention was applied to each glass fabric to weave it.
Glass fiber fabrics shown in Table 1 were produced by deoiling and surface treatment using known methods.

As a comparative example, the current product W, which uses only Z-twisted yarn, is
EA-18W and ridge A-19 were used.

Prepreg is made by a known method using each of the four types of glass fiber fabrics shown in Table 1 and epoxy resin (FR-4 type), and eight sheets of this prepreg are stacked to form a top and bottom surface. A copper foil with a thickness of 18 μm is superimposed on the surface, and this is heated at a pressure of 80 @/c+fl and a temperature of 170
A copper-clad laminate was produced by pressing under conditions of 90 minutes of holding time.

The glass fiber fabric used in this test was
0cs++), fixed one side, and the twist angle when suspended, and JIS C6 for copper-clad laminates.
Warpage and torsion were measured using the test method specified in 481, 5.4.3. The results are shown in Tables 1 and 2.

As is clear from Table 2, it was confirmed that in Example 1 of the copper-clad laminate according to the present invention, warping and twisting were significantly reduced compared to the comparative example.

Example 2 Commonly known as a thin material (100 μm thick) as a base material for the laminate of the present invention
Glass fiber fabric was used.

This glass fiber fabric uses -EA-116E type (Nitto Boseki Co., Ltd. product), is woven by applying the present invention to the glass fabric, and is deoiled and surface treated by a known method to obtain the glass fibers shown in Table 3. Manufactured textiles. As a comparative example, the current product WEA-116, which uses only Z-twisted yarn, is
E was used.

The prepregs shown in Table 3 are made by a known method using each of the two types of glass fiber fabrics and epoxy resin (PR-4 type), and 10 sheets of these prepregs are stacked one on top of the other. A copper foil with a thickness of 18 μm is placed on the bottom surface, and this is heated at a pressure of 80 kg/ci and a temperature of 170°.
A copper-clad laminate was manufactured by pressing under the conditions of C1 holding time of 90 minutes.

The glass fiber fabric used in this test was
JIS C648 regarding the helix angle and copper-clad laminate when cut out to 0 cm), fixed on one side, and hung.
Warpage and twisting were measured using the test method specified in 1, 5, 4, and 3. The results are shown in Tables 3 and 4.

FIG. 2 shows the organization diagram of the glass fiber fabric of this example. The warp is composed of a 5:1 ratio of ECE 225110-IZ glass fiber single yarn of warp 1' and ECE 225110-15 glass fiber single yarn of warp 2', and weft 3' is HCE.
It is a plain weave fabric made of 225I10-IZ glass fiber single yarn.

Table 3 Table 4 Measurement method, based on JIS C6481, 5.4.3 Dimensions of sample: 450 mm x 450 mm, with copper foil on both sides *Heating conditions: 17
Heat at 0°C for 30 minutes *l The ratio of Z-twisted yarn to S-twisted yarn is 5:l *2 Measurement method;
Torsion angle when a strip of 10 cm x 200 cm is hung without weight [Example 3] Among the glass fiber fabrics shown in Example 1, WEA-18
Two types using W type glass fiber fabric (I! II
A laminate (usually referred to as a composite laminate) was made by a known method by combining the composition of the present invention and the comparative example) with glass paper, that is, glass nonwoven fabric. The manufacturing process was as follows. Glass paper of 100g/rrfO was used, and glass paper prepreg was made with epoxy resin (FR-4 type) with a resin content of 67%, while glass fiber woven fabric had a resin content of 67%.
09g/rrfO was used, and this and epoxy resin (
PR-4 type) to make a glass fiber fabric prepreg with a resin content of 42%, stack four glass paper prepregs, place one glass fiber fabric prepreg on the top and bottom surfaces, and add a thick layer to both sides. 18μ
Layer m of copper foil, pressure 30 kg/cd, temperature 170°C
and held for 90 minutes to produce two types of laminates (composite laminates).

The dimensions of this laminate were 45 ci x 45 cm+ and the thickness was 1.6 mm.

Warpage and twisting of the laminate according to the third example of the present invention and the laminate of the comparative example were measured using the same test method as in Example 1.

The results are shown in Table 5.

Table 5 As is clear from Table 5, the composite laminate according to the third embodiment of the present invention also has significantly reduced warping and twisting compared to the conventional composite laminate as a comparative example. confirmed.

〔effect〕

In the laminate of the present invention, the internal stress of the fabric itself is reduced by arranging the warps of the base fabric at a specific ratio of Z-twisted yarns and S-twisted yarns, and the internal stress of the fabric itself is reduced. The laminate can significantly reduce warping and twisting compared to conventional laminates. As a result, especially when this laminate is used as a printed wiring board,
Processing using high-density automatic mounting equipment is now possible without any trouble.

[Brief explanation of drawings]

Figures 1 and 2 are organization charts showing examples of the glass fiber fabric of the present invention.

Claims (6)

[Claims] (1) having a plurality of superimposed fabric layers and a synthetic resin impregnated into and integrating the plurality of fabric layers, the fabric has warp and weft yarns, and the weft yarn is Z
It consists of twisted yarn (or either S twisted yarn), and the warp is S (or Z) twisted yarn / Z (or S
) A laminate plate that is almost uniformly arranged in a ratio of twist = 1/2 to 8. (2) The laminate according to claim 1, wherein the number of twists of the Z-twisted yarn and the S-twisted yarn constituting the warp of the fabric is the same. (3) The laminate according to claim 1, in which copper foil is bonded to both sides or one side. (4) a plurality of superimposed layers of nonwoven fabric, and a layer of fabric superimposed on the layer of nonwoven fabric on both sides of the layer of nonwoven fabric;
a synthetic resin impregnated into and uniting the non-woven layer and the woven fabric layer, the woven fabric having warp and weft yarns, the weft yarns being composed of Z-twisted yarns (or either S-twisted yarns); The warp yarns are approximately uniform in the ratio of S (or Z) twist/Z (or S) twist = 1/2 to 8 depending on the number of twists of the weft, the tex of the weft, and the number of weft threads (strands/25 mm). Laminate board placed on. (5) The laminate according to claim 4, wherein the number of twists of the S-twisted yarn and the Z-twisted yarn constituting the warp of the fabric is the same. (6) The laminate according to claim 4, in which copper foil is bonded to both sides or one side.