JP2001329449A - Glass cloth for printed circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass cloth which is suitable for the high density printed circuit boards of electronic equipment and does substantially not have voids or basket holes. SOLUTION: This glass cloth having no basket hole and having excellent resin impregnability, characterized by preliminarily treating warps composing the glass cloth with a wax, opening and widening the warps, and weaving the warps. The printed circuit board comprising the glass cloth as a substrate and having not only excellent heat resistance and dimensional stability but also excellent small hole formability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass cloth for a printed wiring board for electronic equipment, and more particularly to a glass cloth suitable for a high-density printed wiring board capable of forming a fine hole and using the glass cloth as a base material. The present invention relates to a printed wiring board.

[0002]

2. Description of the Related Art In recent years, a multilayer substrate has become the mainstream of a printed wiring board, and is constituted by laminating a plurality of plies of an insulating substrate provided with a conductor layer in a multilayer shape and joining them. The conductor layer provided on each of the insulating bases constituting the printed wiring board is electrically connected to an arbitrary conductor layer in the vertical direction through a conductive hole (via hole or simply via). I have. The advancement of electronic devices with higher functions, more functions, smaller size, lighter weight, and higher speed is remarkable, and in order to meet the ever-increasing demands, higher density is required especially for printed wiring boards. Therefore, it is essential to reduce the diameter of the via hole.

The basic characteristics required for a printed wiring board and a glass cloth include dimensional stability, substantially no warpage, no deflection, surface smoothness, low coefficient of thermal expansion, electrical insulation, heat resistance and the like. Excellent physical mechanical properties, drilling workability, and the like. For glass cloth used for insulating layer substrates such as glass cloth and epoxy resin, parameters such as warp and weft density, thickness, yarn bundle shape, woven structure and surface condition are important, especially for electronic equipment. Among the required properties related to glass cloth for responding to light and thin, especially the degree of opening of the yarn bundle
Surface smoothness and drillability are important. That is, it is required that the surface of the glass cloth be flat without unevenness, and that the glass yarn bundles constituting the cloth be sufficiently opened and have a cloth structure having no gap between the glass yarn bundles.

A woven structure of a glass cloth is generally a plain woven structure in which warps and wefts alternately vertically and horizontally intersect with each other. It consists of two yarn bundles at the intersection, and a gap called a basket hole surrounded by warps and wefts. In the resin impregnation step, this void portion is a portion which is naturally made of only the resin, and the weave intersection portion is thicker than the other portions, so that surface unevenness occurs as a whole. This will have a significant effect on the drilling process. The drilling method has long been used as a method for drilling conductive holes.However, this method uses the roughness of the inner wall of the processing surface, displacement of the processing hole, and the wall surface of the processing hole in the next plating process. Tends to cause problems such as insulation failure due to the plating solution permeation. In the drilling of small-diameter holes of 0.2 mm or less required with the recent progress of high-density, there is a further problem that productivity is not improved because drilling is severely consumed due to breakage and the like, and it takes a lot of time to exchange drills. In addition, in the case of an ultra-thin insulating base material that requires a thickness of 0.1 mm or less for miniaturization of a printed wiring board, it is extremely difficult to control the depth of the hole with an accuracy of 0.1 mm or less by drilling. It was difficult to form a via hole in such a thin insulating base material. In the drilling method, there is a limit to the precise drilling of minute holes, and it is difficult. Therefore, a laser processing method has recently been developed as a method of drilling minute holes.

In the case where a small diameter hole of about 0.1 mm is formed by, for example, laser processing in a substrate made of the glass cloth / epoxy resin insulating layer, however, the resin and the glass caused by the existence of the basket hole are formed. The presence / absence causes variations in the via diameter and the opening diameter due to the difference in the thermal decomposition characteristics (thermal decomposition temperature, thermal conductivity, etc.) of the two. In particular, since the glass cloth (for example, 106, 1080, etc. according to the IPC standard style) for an ultra-thin insulating layer required for a high-density mounting substrate uses an ultrafine yarn, the ratio of the basket hole portion to the via diameter becomes large. In addition, the adverse effect on via hole formation also increases accordingly.

[0006]

However, in a conventional base material using a glass cloth having a large basket hole, even if a small-diameter via is formed by laser processing, the hole shape and the opening diameter of the via vary, so that the conductive plating is performed. The ill effect on unavoidable. In addition, since the shape of the hole is not a circle but a circular shape, there is a problem that wiring to the printed wiring board does not work well. Therefore, whether laser processing or drilling, various attempts have been made to obtain a glass cloth that enables drilling of circular via holes with a uniform diameter and shape, both in diameter and shape.
One such method is a method of uniformly flattening and opening a glass cloth. This is because the yarn width of the yarn bundle is widened and the thickness is reduced by the opening process, so that the impregnation of the resin into the glass cloth is uniform and the voids in the glass yarn are eliminated.
This is a method for improving heat resistance, dimensional stability, and drilling workability of a laminate. Conventionally, a method is known in which a fiber cloth is opened by, for example, continuously jetting a pressure water stream from a plurality of nozzles onto a glass cloth to obtain a glass cloth having no gap between glass thread bundles (Japanese Patent Laid-Open No. 10-259538). In the opening process by this water jet method, since the opening process is performed continuously while moving the glass cloth, tension is applied in the longitudinal direction of the woven fabric, that is, the warp direction, and it is difficult to open the fabric. This is a weft opening method utilizing the property that the weft is easily opened because a force in the direction of reducing the width of the woven fabric is applied due to the tension applied to the weft. However, this method has a complicated and difficult aspect because it has to be controlled by a number of parameters such as the nozzle diameter, arrangement, vibration, and pressure conditions.

In the present invention, as a result of various studies to develop a new simpler method of opening glass cloth, the wax treatment of the warp, which is difficult to open, was unexpectedly performed in the opening and the warp of the warp. The present inventor has found that it is possible to widen the width of the present invention, and has made further studies to complete the present invention. That is, an object of the present invention is to provide a glass cloth having substantially no basket holes, a flat glass yarn bundle, and a smooth cloth surface by spreading warp yarns. It is another object of the present invention to provide a printed wiring board formed by using the glass cloth base material and having excellent workability for microdrilling.

[0008]

The glass cloth of the present invention is characterized in that the warp yarn is woven after being subjected to a paraffin treatment in advance. The present invention for solving the above problems,
A glass cloth woven from a warp and a weft, woven using a warp prepared by performing a wax treatment in advance, and opened, wherein the glass cloth has substantially no basket hole. Since the warp yarn is wax-treated, the bunching property is weak, and the warp yarn is easily opened by the beating motion of driving the weft in the loom, so that the woven glass cloth is flattened,
Since the warp yarns are widened and the gaps are reduced by that amount, the warp yarns and the weft yarns constituting the glass cloth are arranged with almost no gap and exhibit a surface state uniformly distributed. That is, there is substantially no basket hole. Another invention is based on a predetermined number of prepregs such as glass cloth and synthetic resin (for example, epoxy resin) using a glass cloth without voids, which is woven from a warp and a weft, which are pre-waxed and opened. In a multilayer printed wiring board. This printed wiring board is excellent in drilling processability of minute via hole of about 0.1 mm, especially laser drilling processability, and since the surface and cross-sectional shape of the obtained via are perfectly circular, it is possible to perform wiring smoothly. There is.

That is, the present invention provides (1) a glass cloth having substantially no basket holes, which is woven using a warp yarn which has been subjected to a wax treatment before weaving, and (2) the above-mentioned (1). And a printed wiring board using the glass cloth as a base material.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION A glass cloth which is a main part of the present invention will be described below. The warp and weft used for weaving the glass cloth of the present invention are composed of 100 to 800 monofilaments having a filament diameter of preferably 5 to 10 μm and are usually provided with a starch-based spinning binder. The weft is usually treated with the above-mentioned starch-based spinning binder and used for weaving. The weave is plain weave, satin weave, nanako weave, twill weave, or the like, but plain weave is preferred. Glass types include not only E glass (non-alkali) used as a substrate for printed wiring boards, but also D glass (low dielectric), T glass
Glass (high strength), C glass (alkali lime), H glass (high dielectric) and the like can also be used.

Prior to weaving the glass cloth of the present invention, it is usually essential that the warp be subjected to a wax treatment in a preparation step after being added to a binder treatment. Wax is applied according to a standard method when making a coarsely wound beam with a warper. In addition, wax can be applied when beaming the roughly wound beam. Various natural waxes such as petroleum wax (e.g., paraffin wax, microcrystalline wax), vegetable wax (e.g., carnauba wax), animal wax (e.g., beeswax), mineral wax (e.g., montan wax), synthetic wax (e.g., carbowax) , Polyethylene wax), and the like, although not particularly limited, paraffin wax is preferred. The wax may be applied directly to the warp glass thread in a solid state, or may be applied as a liquid at a temperature equal to or higher than the melting point. The wax adhesion rate varies depending on the yarn count. When the count is large, the count is large, and when the count is small, the count is small. Generally, it is 0.1 to 5%, but preferably 0.3 to 2.5%. If the amount is too small, problems such as cutting of the warp may occur during weaving. If the amount is too large, wax may accumulate on the reed feathers, causing problems such as dirt and thread breakage. During weaving by plain weaving or the like, when the weft is alternately woven into the warp covered or attached with the wax, tension is applied to the warp, so that the warp is opened and simultaneously widened to the warp. The glass cloth thus obtained is not only opened but also has a greatly reduced basket hole compared to a glass cloth without wax treatment. For example, if a small via having a diameter of about 0.1 mm is used as a reference, the size of the gap is as small as about 0.03 to 0.04 mm on one side, which is an order of magnitude and negligible. It can be said that there is no basket hole part and it is closed. In addition, the glass cloth woven in this manner may be subjected to the above-described fiber-spreading processing by water jet injection, if desired. The binder and the wax agent need to be removed in order to be used for a printed wiring board. Usually, the binder and the wax agent are heated at about 400 ° C. for several tens of hours to perform a desizing process.

The desiccant-treated glass cloth of the present invention is
In manufacturing the printed wiring board, the prepreg is surface-treated with a coupling agent in advance for adhesion to a matrix resin. A typical example is a silane coupling agent. The surface treatment is performed by immersing, squeezing, and drying a glass cloth in a dilute aqueous solution of about 0.1 to 2%. Then, a prepreg is prepared by impregnating a glass cloth with a matrix resin such as an epoxy resin by an ordinary method. In that case, if it is used for the glass cloth of the present invention, the resin can be completely impregnated substantially without voids. The prepreg is obtained by laminating a plurality of prepregs, placing copper foil on the upper and lower sides, or laminating on the inner core plate, and forming the laminate by heating and pressing. Examples of the resin used for the printed wiring board include a thermosetting resin such as an epoxy resin, an unsaturated polyester resin, a polyimide resin, and a BT resin, and a thermoplastic resin such as a PPO resin, a polyetherimide resin, and a fluororesin.

[0013]

EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples. In Examples, the width, via diameter, and the like of the yarn bundle of the warp and the weft of the glass cloth were photographed with an electron microscope, and the dimensions were measured.

Example 1 As a glass fiber, ECE225 1 / 01Z was used in advance in a warping step for a warp, and a paraffin wax (Cytex GL) was used.
O-1400 (manufactured by Taiyo Kagaku Kogyo Kogyo Co., Ltd.) so as to give an adhesion rate of 1.0% by weight, and then beamed for a loom. EC as weft
Using E225 1/0 1Z, the density is 60 warps / 25mm and the weft is 58
The book / 25 mm was woven in an air jet loom. As a result, the woven greige cloth was obtained in which the warps were spread in a uniform fiber distribution state and a flat cloth substantially free of basket holes was obtained. Next, the woven fabric cloth is heat-treated at 400 ° C. for 70 hours to incinerate and remove the spinning binder adhering to the glass fibers and the paraffin wax adhering to the warp yarns. Then, SZ6032 (manufactured by Dow Corning Toray Silicone Co., Ltd.) is used as a surface treatment agent. Was subjected to a surface treatment so as to have an adhesion rate of 0.1% by weight. Table 1 shows the yarn widths of the greige cloth and the processing cloth.
Thereafter, a laminate for a printed wiring board was prepared as follows. The composition of the epoxy resin used is 100 parts of Epicoat 5046B80 (manufactured by Yuka Shell Epoxy) as bisphenol A resin, 28 parts of Epicoat 180S7570 (manufactured by Yuka Shell Epoxy) as a polyfunctional resin, and dicyandiamide is 3.
0 parts (DICY7 Yuka Shell Epoxy), curing accelerator 2
Using 0.1 parts of E4M imidazole (EMI24 manufactured by Yuka Shell Epoxy Co.), the solid content was adjusted to 60% with an organic solvent of methyl ethyl ketone, methyl cellosolve, and dimethylformamide. 0.1mm thick glass cloth (E10T
O4 106TT Unitika Glass Fiber Co., Ltd.) was used to prepare a prepreg with a resin adhesion rate of 50% by weight, and 35 μm copper foil was laid on top and bottom, pressure was 300 N / cm ² , temperature was 170 ° C., and temperature was 170 min.
m double-sided copper-clad laminate was prepared, and the surface copper foil was entirely blackened to form an inner layer core material. Next, a prepreg having a resin adhesion rate of 53% by weight was prepared on the prepared opening cloth, and one ply was disposed above and below the inner layer core material. An 18 μm copper foil was disposed on the surface layer, and a four-layer plate was formed under the same pressing conditions as the core material. I got The thus obtained four-layer plate was subjected to a small-diameter drilling process using a leather processing machine (manufactured by Sumitomo Heavy Industries, Ltd.) in a desired pattern after etching the surface copper foil. The processing conditions were a via diameter of 0.15 mm, a frequency of 500 Hz, and a pulse energy of 18 J / cm ² . When the surface shape of the via of the obtained printed wiring board was observed, it was almost a perfect circle, and there was no variation in the size.

Example 2 A paraffin wax (Cytex GL) was used in advance in a warping process for warp using ECE225 1 / 01Z as glass fiber.
O-1400 (manufactured by Taiyo Kagaku Kogyo Kogyo Co., Ltd.) so as to give an adhesion rate of 1.0% by weight, and then beamed for a loom. EC as weft
Using E225 1/0 1Z, the density is 65 warps / 25mm, weft 55
The book / 25 mm was woven in an air jet loom. Otherwise in the same manner as in Example 1, a four-layer board and a printed wiring board were obtained. Table 1 shows the yarn widths of the greige cloth and the processing cloth. The surface shape of the via of the obtained printed wiring board was almost a perfect circle as in Example 1, and there was no variation in the size.

Example 3 A paraffin wax (Cytex GL) was used in advance in a warping process for warp using ECD450 1 / 01Z as glass fiber.
(O-1400 manufactured by Koyo Kagaku Kogyo Co., Ltd.) so as to give an adhesion rate of 0.5% by weight, and then beamed for a loom. EC as weft
Using D450 1/0 1Z, the warp was woven in an air jet loom at a density of 70 warps / 25 mm and a weft of 60 threads / 25 mm. as a result,
The woven greige cloth was opened so that the warp yarns were spread in a uniform fiber distribution state, and a flat cloth having substantially no basket holes was obtained. Next, incineration and surface treatment were performed in the same manner as in Example 1. Table 1 shows the yarn widths of the greige cloth and the processing cloth. Thereafter, a laminated board for a printed wiring board was manufactured in the same manner as in Example 1 except that the prepreg having a resin adhesion amount of the prepared spread cloth of 60% by weight was disposed on each of the upper and lower inner core materials. And a printed wiring board were obtained. The surface shape of the via of the obtained pudding wiring board was almost a perfect circle as in Example 1, and there was no variation in the size.

Example 4 ECD900 1 / 01Z is used as a glass fiber, and a paraffin wax (Cytex GL) is used in a warping step for warp in advance.
(O-1400 manufactured by Koyo Kagaku Kogyo Co., Ltd.) so as to give an adhesion rate of 0.5% by weight, and then beamed for a loom. EC as weft
D900 1/0 1Z, density 100 warps / 25mm, weft 55
The book / 25 mm was woven in an air jet loom. As a result, the woven greige cloth was obtained in which the warps were spread in a uniform fiber distribution state and a flat cloth substantially free of basket holes was obtained. Next, incineration and surface treatment were performed in the same manner as in Example 1. Table 1 shows the yarn widths of the greige cloth and the processing cloth. Thereafter, a four-layer board was prepared in the same manner as in Example 1 except that a prepreg having a resin adhesion amount of the prepared spread cloth of 70% by weight was disposed on each of the upper and lower inner core materials. And a printed wiring board were obtained. The surface shape of the via of the obtained printed wiring board was almost a perfect circle as in Example 1, and there was no variation in the size.

Comparative Example 1 As a comparative example, ECE225 1 was used as glass fiber with a conventional paste.
Gluing for warp was carried out using / 0 1Z. Glue is PVA
As a main component so as to give an adhesion rate of 1.5% by weight. Using ECE225 1/0 1Z as weft, warp density 6
A four-layer board and a printed wiring board were obtained in the same manner as in Example 1 except that weaving of 0 threads / 25 mm and wefts of 58 threads / 25 mm was performed in an air jet loom. Table 1 shows the yarn widths of the greige cloth and the processing cloth. The warp is rounded by the glue, the yarn width is narrow, and the gap between the yarns is large. When the surface shape of the via of the obtained printed wiring board was observed, it was not a perfect circular shape but a variation in the size was observed.

Comparative Example 2 As a comparative example, ECE225 1 was used as glass fiber with a conventional paste.
Gluing for warp was carried out using / 0 1Z. Glue is PVA
As a main component so as to give an adhesion rate of 1.5% by weight. Warp using ECE225 1/0 1Z as weft
A four-layer board and a printed wiring board were obtained in the same manner as in Example 1 except that 65 yarns / 25 mm and wefts 55 yarns / 25 mm were woven in an air jet loom. Table 1 shows the yarn widths of the greige cloth and the processing cloth. When the surface shape of the via of the obtained printed wiring board was observed, it was not a perfect circular shape but a variation in the size was observed.

Comparative Example 3 As a comparative example, ECD450 1 was used as glass fiber with a conventional paste.
Gluing for warp was carried out using / 0 1Z. Glue is PVA
As a main component so as to give an adhesion rate of 1.0% by weight. Using ECD450 1/0 1Z as weft, warp density
A four-layer board and a printed wiring board were obtained in the same manner as in Example 3 except that 70 yarns / 25 mm and weft yarns 60 yarns / 15 mm were woven in an air jet loom. Table 1 shows the yarn widths of the greige cloth and the treated cloth. When the surface shape of the via of the obtained printed wiring board was observed, it was not a perfect circular shape but a variation in the size was observed.

Comparative Example 4 As a comparative example, ECD9001 was used as glass fiber with a conventional paste.
Gluing for warp was carried out using / 0 1Z. Glue is PVA
As a main component so as to give an adhesion rate of 1.0% by weight. Using ECD900 1/0 1Z as weft, warp density
A four-layer board and a printed wiring board were obtained in the same manner as in Example 4 except that weaving was performed at 100 yarns / 25 mm and weft yarns at 55 yarns / 25 mm.
Table 1 shows the yarn widths of the greige cloth and the processing cloth. When the surface shape of the via of the obtained printed wiring board was observed, it was not a perfect circular shape but a variation in the size was observed.

[0022]

[Table 1]

[0023]

The glass cloth of the present invention is uniformly opened and woven by pre-waxing the warp yarns, and has substantially no voids or basket holes, and the fibers are uniformly covered and distributed without any gaps. The glass cloth is flat with few surface irregularities. Therefore,
Since the resin impregnation is good without forming voids even when preparing prepregs for use in printed wiring boards, the resulting printed wiring board has excellent heat resistance, insulation, dimensional stability, drilling workability, especially laser workability, etc. Are better. Printed wiring is particularly excellent in drilling workability of small-diameter vias, and a perfect circular via can be obtained regardless of the small diameter.

Claims (2)

[Claims] 1. A glass cloth having substantially no basket holes, which is woven using a warp yarn which has been subjected to a wax treatment before weaving. 2. A printed wiring board using the glass cloth according to claim 1 as a base material.