JP2005126862A - Unidirectional rib weave glass cloth - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a unidirectional rib weave glass cloth having low crimp percentage in weft direction and having high tensile strength in warp direction. <P>SOLUTION: The unidirectional rib weave glass cloth 1 is obtained by weaving a weft 10 with a warp 20, and weft content is 6-20 times larger than warp content and 2-3 warps 20 as a pair are woven with one weft 10 to provide the rib weave. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a glass cloth used as a reinforcing material for a laminated board for printed wiring boards.

  With respect to printed wiring boards (PWB) used for communication equipment, industrial machines, electronic equipment, and the like, the demand for dimensional stability has become increasingly severe as the density and size have been reduced. The printed wiring board has various shapes. For example, a printed wiring board that is arranged on the frame (淵) of the liquid crystal display has a very long and thin shape. In such a printed wiring board, dimensional stability in the longitudinal direction is particularly important. In addition, a laminated sheet for a printed wiring board generally includes a glass cloth as a reinforcing material, and the dimensional stability of the printed wiring board largely depends on the characteristics of the shrinkage ratio of the glass cloth.

  Conventionally, the following Patent Documents 1 to 3 are known as glass cloths that can improve dimensional stability. Patent Document 1 describes a glass cloth in which the warp is thicker than the weft. However, if the yarn count is in such a relationship, the weft shrinkage of the weft yarn becomes excessively large during weaving. If the weft shrinkage is large, the warp is likely to come into contact with the heel or be pressed to generate fluff, resulting in low productivity and high cost. As described above, increasing the dimensional stability in the warp direction of the cloth in the printed wiring board is accompanied by adverse effects.

On the other hand, Patent Documents 2 and 3 disclose glass cloths in which wefts are thicker than warps. Patent Document 2 discloses a glass cloth having a knot weave structure in which two or more and four or less warps are floated and subtracted simultaneously with respect to one weft, and the glass content is approximately the same in the warp and weft directions. Yes. Patent Document 3 discloses a glass cloth woven by plain weaving of warp and weft and having a TEX count of weft of 8 to 50 times that of warp.
JP 11-335945 A JP 2000-192351 A JP2003-171848

  However, according to the glass cloths of Patent Documents 2 and 3, although the weaving rate in the weft direction can be lowered to some extent, higher dimensional stability is required as the printed wiring board is densified and miniaturized. It's getting on.

  It is also important to reduce the weaving rate in the weft direction and increase the tensile strength in the warp direction. When the tensile strength in the warp direction is low, the handleability is deteriorated and the production becomes difficult.

  An object of the present invention is to provide a unidirectional woven glass cloth having a low weaving shrinkage in the weft direction and a high tensile strength in the warp direction.

  In order to solve the above problems, the unidirectional woven glass cloth of the present invention is a glass cloth formed by weaving a weft and a warp, and the weft content is 6 to 20 times the warp content. The warp weave is characterized by being woven by lifting and lowering as a set of two or three warps.

  In this glass cloth, since the weft content is set to a high value such as 6 to 20 times the warp content, the shrinkage rate in the weft direction is reduced. More preferably, the weft content is 7 to 20 times the warp content. Further, since the weft weave has two or three warps per one weft, the number of weft floats and sinks is reduced. Thereby, the weaving rate in the weft direction is further reduced.

  Moreover, the following effects can be obtained by forming a warp with two or three warps per weft. That is, in the plain weave glass cloth, the wefts that intersect each other are in contact on both sides in the yarn width direction of each warp. That is, each warp is in contact with the weft at two locations on the left and right. On the other hand, in this invention, it contacts with a weft on both sides of the group of 2 or 3 warp. In other words, in the present invention, since the number of portions of each warp that come into contact with the weft is smaller than that in the case of plain weave, the number of portions that receive an impact from the weft when an external force such as tension or friction is applied is reduced. . Thereby, the tensile strength in the warp direction is improved.

  In the unidirectional woven glass cloth of the present invention, it is preferable that the TEX count of the weft is 8 times or more the TEX count of one warp.

  In order to increase the weft content compared to the warp content, there is a method to decrease the number of warp threads and increase the number of weft threads, or to increase the TEX count of each weft and decrease the TEX count of each warp. Conceivable. When the method of reducing the number of warp yarns to be driven is employed with respect to the former number of weft yarns to be driven, the cross tends to bend. Therefore, if the TEX count of the warp is made smaller than the TEX count of the weft as in the present invention, the woven glass cloth having a unidirectional property (that is, having a low unidirectional shrinkage rate) while preventing cross bending. Can be obtained.

  Furthermore, in the unidirectional warp woven glass cloth of the present invention, the diameter of the filament constituting the warp is preferably 80% or less of the diameter of the filament constituting the weft.

  By reducing the filament diameter of the warp in this way, the warp is easily crushed during weaving, so that the straightness of the weft is improved. Further, increasing the filament diameter of the weft also increases the rigidity of the weft and improves the straightness. As a result, the weaving ratio in the weft direction is significantly reduced.

  According to the unidirectional warp woven glass cloth according to the present invention, the shrinkage rate in the weft direction is low, and the tensile strength in the warp direction can be increased. A laminated board or printed wiring board obtained by impregnating such a glass cloth with a resin has markedly improved dimensional stability in the weft direction of the glass cloth.

  Hereinafter, with reference to the accompanying drawings, a preferred embodiment of a unidirectional woven glass cloth according to the present invention will be described in detail. In addition, the same code | symbol shall be used for the same element and the overlapping description is abbreviate | omitted.

  FIG. 1 is a plan view showing a unidirectional woven glass cloth 1 according to this embodiment, and FIG. 2 is a cross-sectional view in the II-II direction of FIG. The glass cloth 1 is suitably used as a reinforcing material for a printed wiring board, and is configured to have a low weaving rate in the weft direction.

The glass cloth 1 is obtained by weaving a weft 10 and a warp 20 and has a structure in which two warps 20 are floated and submerged as a set with respect to one weft 10. Further, the total content of the weft 10 in the glass cloth 1 is 6 to 20 times the total content of the warp 20. The weft 10 and the warp 20 are made of, for example, E glass whose main component is SiO ₂ , CaO, Al ₂ O ₃ , B ₂ O ₃ or the like. The thickness of the glass cloth 1 is about 100 μm.

  In this glass cloth 1, since the weft content is set to a high value such as 6 to 20 times the warp content as described above, the shrinkage rate in the weft direction (left-right direction in the figure) is reduced. . More preferably, the weft content is 7 to 20 times the warp content. When the ratio of the weft content is lower than the lower limit of these ranges, the reduction in the weaving rate is not sufficient, whereas when it is higher than the upper limit of these ranges, there is a problem that weaving is difficult.

  Further, in the glass cloth 1, since the warp weave is composed of two warps 20 for one weft 10, compared to the case where one weft is woven for one warp, the weft 10 The rise and fall points have been reduced. Thereby, the weaving rate in the weft direction is further reduced. Here, “ups and downs” means ups and downs of the weft in FIG.

  Further, when it is assumed that the total TEX count of two warps is equal to the TEX count of one warp in a plain weave, that is, assuming that the TEX count of one warp is half that of a plain weave, as shown in FIG. The thickness h of the warp yarn 20 is smaller than that of the plain weave. For this reason, the straightness of the weft 10 is maintained, and the weaving / shrinkage ratio of the glass cloth 1 in the weft direction is also reduced from this point.

  Moreover, the following effects can be obtained by forming a warp with two or three warps per weft. In other words, in the conventional plain weave glass cloth, the warp yarns that intersect with each warp yarn are in contact with each other in the yarn width direction. On the other hand, in this embodiment, as shown by the broken line in FIG. 1 and the black circle in FIG. 2, the weft 10 is in contact only in the regions A and B on both sides of the set of two warps. That is, in this embodiment, since the number of portions of each warp 20 that come into contact with the weft 10 is smaller than that in the case of plain weave, the number of portions that receive an impact from the weft 10 when an external force such as tension or friction is applied is reduced. That's right. Thereby, the tensile strength in the warp direction is improved.

  The TEX count of the weft 10 can be, for example, 20 to 80 TEX, and the TEX count of the warp 20 can be, for example, 5 to 30 TEX. Further, from these ranges, it is preferable to combine so that the TEX count of the weft is 8 times or more the TEX count of one warp. The reason is as follows. That is, in order to increase the weft content as compared with the warp content as described above, a method of reducing the number of warps 20 to be driven can be considered. However, when this method is adopted, the cross tends to bend. Therefore, instead of reducing the number of warps 20 to be driven, if the count of the warps 20 is reduced as in this embodiment, the weaving / shrinkage rate can be reduced while preventing cross bending.

  The number of wefts 10 to be driven is preferably about 35 to 60/25 mm, and the number of warp threads to be driven is preferably about 0.8 to 2.0.

  The weft 10 and the warp 20 are formed by twisting a plurality of glass filaments having a filament diameter of 3 to 13 μm. The number of filaments of the weft 10 is, for example, 200 to 800, and the number of filaments of the warp 20 is, for example, 50. It can be -400. Further, from these ranges, it is preferable to combine so that the diameter of the filament constituting the warp 20 is 80% or less of the diameter of the filament constituting the weft 10.

  By reducing the filament diameter of the warp 20 as described above, the warp 20 is liable to be crushed and flattened during weaving, so that the straightness of the weft 10 is improved. In addition, increasing the filament diameter of the weft 10 also increases the rigidity of the weft 10 and improves the straightness. Thereby, the weaving rate in the weft direction is significantly reduced. In order to make the warp 20 easy to be crushed during weaving, it is preferable to reduce the number of warp twists. The number of warp twists can be, for example, 0 to 0.5 times / 25 mm.

  As described above, the glass cloth 1 having improved dimensional stability in the weft direction is used to reinforce a printed wiring board that requires high dimensional stability in one direction, such as an elongated printed wiring board disposed in the frame of a liquid crystal display. It can be suitably used as a material. In addition, such a printed wiring board has high surface smoothness.

  In addition, when a glass cloth 1 is impregnated with a thermosetting resin to prepare a prepreg, and a plurality of the prepregs are laminated so that the weft directions of the glass cloth are alternately orthogonal, when a conventional plain weave glass cloth is used In comparison, the glass content is improved, and the weft of the thick count is small, so that the dimensional stability is improved in both the warp direction and the weft direction. However, when producing a printed wiring board that requires a high degree of dimensional stability in one direction, it is preferable to stack a plurality of prepregs so that the wefts of the glass cloth are in the same direction.

  In order to obtain the effect of the present embodiment, three warps may correspond to one weft. On the other hand, if four or more warps are made to correspond to one weft, the glass cloth tends to bend and the productivity is lowered. Therefore, two or three warps are used as one set.

  Next, the effect of this invention is demonstrated based on an Example. In Examples and Comparative Examples, glass cloths were produced according to the warp and weft configurations (filament diameter, number of bundles of filaments, TEX count) and the number of driven yarns shown in Table 1. Moreover, E glass was used as a warp and a weft.

[Example 1]
In Example 1, the content of the weft with respect to the warp was set to 8.2 times (the content of each yarn is obtained by multiplying the TEX count and the number of driven yarns). Also, by using weft yarns with a TEX count of 46TEX and warp yarns with a TEX count of 5.6 TEX, weft TEX count is about 8.2 times (8 times or more) It was. Further, the diameter of the filament constituting the warp was set to 5.3 μm, the diameter of the filament constituting the weft was set to 7.2 μm, and the filament diameter of the warp was set to about 73% (80% or less) of the filament diameter of the weft.

  First, a pair of warps was weaved as a set for one weft to obtain a glass cloth. The tensile strength in the warp direction of the glass cloth of this example was 3.8 kg / 25 mm. The tensile strength of the glass cloth was determined by the tensile strength of JIS R 3420 7.4.

Further, the weaving and shrinkage ratios of the glass cloth of this example were 1.9% in the warp direction and 0.08% in the weft direction. If a glass cloth with a small weaving rate is used as a reinforcing material, the dimensional stability of the laminated board for printed wiring boards is improved. The weaving / reducing rate is the length of the yarn after drawing after using a glass cloth that has been cut so that the crosscut length is about 50 cm in length and width, pulling out the yarn and applying a tensile load at 10 gf. It was obtained by measuring.
Reduction rate (%) = (yarn length after drawing-cross cut length) / (yarn length after drawing) * 100

  And after deoiling this by heating, it is immersed in 0.5% by weight of aqueous treatment liquid of vinylbenzyldiaminopropyltrimethoxysilane / hydrochloride (SZ6032 manufactured by Toray Dow Corning Co., Ltd.) so that the pickup amount becomes 30% by weight. Drawing with a mangle and drying at 110 ° C. for 5 minutes gave a treated glass cloth.

The treated glass cloth was impregnated with an epoxy resin varnish having the following composition, and then heated and dried at 150 ° C. for 5 minutes to obtain a prepreg having a melt viscosity of 300 poise. As shown in Table 1, the glass filling rate of this prepreg was 44.8% by weight.
<Composition of epoxy resin varnish>
Epicoat 1001 (Oilized Shell Epoxy Co., Ltd.)) 80 parts by weight Epicoat 154 (Oilized Shell Epoxy Co., Ltd.)) 20 parts by weight Dicyandiamide 4 parts by weight Benzyldimethylamine 0.2 parts by weight Dimethylformamide 30 parts by weight

Next, 16 sheets of this prepreg were aligned in the warp direction and the weft direction, and a copper foil having a thickness of 18 μm was further stacked on the front and back, and after heat-pressing at 170 ° C., 30 kgf / cm ² for 70 minutes, After cutting into 1 cm square, the copper foil was removed by etching to obtain a laminate. The resulting laminate had a thermal expansion coefficient in the warp direction of 27.8 ppm / ° C. and a thermal expansion coefficient in the weft direction of 9.0 ppm / ° C. The coefficient of thermal expansion was determined by increasing the temperature of the glass epoxy laminate test piece from room temperature to 150 ° C. at 5 ° C. per minute using DMA 7 manufactured by Perkin Elmer (the following formula) (See (1)).
α = ΔL / (L0 × ΔT) (1)
α: Average linear expansion coefficient ΔL: Displacement amount (length) of test piece {L ₂ (test piece length at 100 ° C.) − L ₁ (test piece length at 70 ° C.)}
L0: Sample length {Normal specimen length}
ΔT: Temperature range (° C.) {T ₂ (100 ° C.) − T ₁ (70 ° C.)}

  Further, when 16 sheets of prepregs were laminated so that the warp direction and the weft direction were alternately orthogonal, a laminated plate was produced. The thermal expansion coefficient in the warp direction and the weft direction was 14.3 ppm / ° C.

[Example 2]
In Example 2, as in Example 1, a warp weave in which two warps correspond to one weft was used. In addition, the weft content relative to the warp was about 8.4 times. In addition, using weft yarn with TEX count of 67.5TEX and warp yarn with TEX count of 5.6 TEX, weft TEX count is about 12 times (8 times or more) of warp TEX count It was. Furthermore, the filament diameter constituting the warp was 5.3 μm, the filament diameter constituting the weft was 9.1 μm, and the filament diameter of the warp was about 58% (80% or less) of the filament diameter of the weft.

  And by the same method as Example 1, the glass cloth, the prepreg, and the laminated board (what aligned the warp direction and the weft direction of the cloth which overlaps up and down) were produced.

[Example 3]
In Example 3, as in Example 1, a warp weave in which two warps correspond to one weft was used. Further, the weft content relative to the warp was set to 7 times. Further, in this example, the weft content was higher than the warp content by reducing the number of driven-in yarns instead of lowering the TEX count of the warp. Specifically, the weft and warp TEX counts were both 22.5 TEX. The filament diameters of the weft and the warp were both 7.2 μm.

  And by the same method as Example 1, the glass cloth, the prepreg, and the laminated board (what aligned the warp direction and the weft direction of the cloth which overlaps up and down) were produced.

[Comparative Example 1]
In Comparative Example 1, a glass cloth was produced by weaving a weft and a warp. The warp and weft were the same as in Example 2. And by the same method as Example 1, the glass cloth, the prepreg, and the laminated board (what aligned the warp direction and the weft direction of the cloth which overlaps up and down) were produced.

[Comparative Example 2]
In Comparative Example 2, a glass cloth was produced by weaving wefts and warps. The warp used was TEX count 11.2 TEX which is twice that of Example 2. The same weft as in Example 2 was used. That is, in the comparative example 2, what has the same ratio of the glass content in the warp direction and the weft direction as in the example 2 is constituted by plain weave. And by the same method as Example 1, the glass cloth, the prepreg, and the laminated board (what aligned the warp direction and the weft direction of the cloth which overlaps up and down) were produced.

[Comparative Example 3]
In Comparative Example 3, the same yarn was used for the warp and the weft, and a glass cloth was produced by plain weaving. And the glass cloth, the prepreg, and the laminated board were produced by the same method as Example 1. Laminate plates were produced in which the warp direction and the weft direction were aligned, and the warp direction and the weft direction were alternately perpendicular to each other in the cloth that overlapped vertically.

[Test results of Examples and Comparative Examples]
In Examples 1 to 3, the weaving rate of the glass cloth in the weft direction was low. Further, since the linear expansion coefficient of the laminated plate in the weft direction was low, it was found that the dimensional stability in the weft direction was remarkably improved. In Examples 1 to 3, the tensile strength in the warp direction was a sufficiently high value, and the handleability was good.

  On the other hand, in Comparative Example 2, the weaving rate of the glass cloth in the weft direction was high. Here, as can be seen from the comparison between Example 2 and Comparative Example 2, the glass cloth of the present invention and the plain weave glass cloth having the same glass content ratio of the warp and the weft have a large weaving shrinkage ratio in the weft direction, and the laminated board It has been found that the coefficient of thermal expansion at the time of making increases, and the dimensional stability of the laminate is poor. Further, the shrinkage ratio of the glass cloth of Comparative Example 1 and the thermal expansion coefficient of the laminate were not so inferior to those of the Examples, but the tensile strength in the warp direction was as low as 1.9 kg / 25 mm, It turned out that handling was bad. In addition, when weaving the glass cloth of Comparative Example 1, the number of times the loom was stopped was very large, and many fluffs of the glass cloth were generated.

  In Examples 1 and 2, the weaving rate in the weft direction was reduced as compared with Example 3. This is due to the fact that the TEX count of the weft is 8 times or more of the TEX count of one warp and that the diameter of the warp filament is 80% or less of the filament diameter of the weft.

It is a figure which shows one Embodiment of the unidirectional woven glass cloth which concerns on this invention. It is sectional drawing of the II-II direction of the glass cloth shown in FIG.

Explanation of symbols

1 ... glass cloth, 10 ... weft, 20 ... warp.

Claims (3)

A glass cloth made of weft and warp,
The weft content is 6 to 20 times the warp content,
A unidirectional warp woven glass cloth, wherein the warp weave is made by weaving two or three warps as a set with respect to one weft.   The unidirectional woven glass cloth according to claim 1, wherein the weft yarn has a TEX count of 8 times or more of the single warp TEX count. The unidirectional warp woven glass cloth according to claim 1 or 2, wherein a diameter of the filament constituting the warp is 80% or less of a diameter of the filament constituting the weft.

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