WO1999028126A1

WO1999028126A1 - Prepreg for multilayer printed wiring boards and process for producing the same

Info

Publication number: WO1999028126A1
Application number: PCT/JP1998/005372
Authority: WO
Inventors: Michio Konno; Shin Kasai
Original assignee: Nitto Boseki Co., Ltd.
Priority date: 1997-12-01
Filing date: 1998-11-30
Publication date: 1999-06-10

Abstract

A prepreg for multilayer printed wiring boards having an insulating substrate comprising a resin-impregnated nonwoven glass fabric, characterized in that the nonwoven glass fabric is layered on a carrier sheet made of a synthetic resin film having a heat-resisting temperature of 150 °C or above or a copper-base circuit foil and that the fabric is constituted of highly flat glass fibers. The prepreg is increased in glass fiber content, excellent in dimensional stability and surface flatness, and is reduced in thickness, thus providing a prepreg based on nonwoven glass fabric suitable for multilayer printed wiring boards.

Description

Description: Pre-preda for multilayer printed wiring board and manufacturing method thereof

TECHNICAL FIELD The present invention relates to a pre-preda for a multilayer printed wiring board using a glass nonwoven fabric and a method for producing the same.

Background art

Conventionally, glass cloth has been mainly used as an insulating base material of a laminate for a printed wiring board. As a method of manufacturing a laminated board for a printed wiring board using the glass cloth, first, a glass cloth is impregnated with a matrix resin such as a liquid epoxy resin whose viscosity has been reduced with a solvent, using a squeezing apparatus. After the excess resin is squeezed and adjusted to the specified resin impregnation amount, it is passed through a dryer and heated to remove the solvent and produce a prepreg in which the resin curing stage is adjusted. After cutting to the prescribed size suitable for the copper-clad laminate, arranging copper foil for circuit on one or both sides, or laminating the number of sheets according to the configuration, printing by heating and pressing with a press A method of manufacturing a wiring laminate II has been adopted.

On the other hand, glass cloth is expensive, so instead, glass cloth is used for only one layer on each of the front and back sides, and the core is laminated with prepreg made of glass non-woven fabric. Printed wiring called CEM-3 There are also fields in which 扳 laminates are used.

However, the amount of the matrix resin impregnated in a laminated board composed of only glass cloth as the insulating base material is about 40% by weight, whereas the use of an insulating base material made of glass non-woven fabric results in the use of a matrix resin. (In comparison with glass fiber and resin by volume, glass fiber is about 25%, resin is about 75%, and the volume occupied by resin is overwhelming. As a result, when glass nonwoven fabric was used as the insulating base material, glass fibers could not be contained in a high proportion.

Thus, when the content of the resin is large relative to the glass fiber, the heat W.

(2) Dimensional change due to expansion, especially thermal expansion coefficient in the thickness direction is large, holes are drilled in the laminated board, and through-hole plating is performed on the inner surface by electroless plating etc. to disconnect the upper and lower surfaces due to thermal expansion. In some cases, there was a problem in the dimensional stability of the laminate and in reliability.

5 In addition to the above-mentioned problems, recent miniaturization and high performance of electronic devices have resulted in the use of multiple circuit boards, called multilayer boards, which have been used. The width of the circuit board has been increasingly narrower and arranged without gaps, and moreover, tens of circuit boards have been integrated.

Therefore, in such a situation, a pre-zero pre-printer used for a printed wiring board is required to have further thinner and smoother properties.

The glass non-woven fabric obtained by papermaking a small amount of glass fiber chopped strands dispersed in water as the raw material has a straight glass fiber and a smooth surface. It is difficult to obtain a sufficient tensile strength as a non-woven fabric using only glass fiber as a raw material, such as a paper made from an organic raw material without entanglement. Therefore, in order to secure sufficient tensile strength, a method of impregnating a paper-made glass nonwoven fabric with a binder such as a water-soluble acryl resin or epoxy resin and curing it is adopted. Glass nonwoven fabric cannot be used, and in order to have sufficient strength, a thick nonwoven fabric with a large basis weight must be used as the glass nonwoven fabric, and a resin binder to be impregnated Because of the necessity of increasing the impregnation amount of prepreg, it was not possible to produce a prepreg having a high glass fiber content and a small thickness.

Also, an increase in the amount of resin used for impregnation (for example, epoxy resin) leads to an increase in the amount of a surfactant for dispersing such a resin in water. In addition to deteriorating the water, it has caused long-term deterioration in insulation performance.

Furthermore, in the process of manufacturing the prepreg, the solvent contained in the resin impregnated into the glass fiber is removed, but when the solvent is removed, the volume of the resin part decreases and the resin moves from the surface to the inside. Due to the phenomenon of sink marks, when copper foil is laminated using a non-woven glass surface and press-molded, the surface becomes 10 / m Near intense irregularities may occur. Therefore, when the copper foil is removed by etching or the like on the laminated plate existing on the surface, the copper foil is likely to remain in the concave portion, and the copper foil in the convex portion is easily removed. There was a problem such as disconnection of a circuit or connection of the circuit by mistake due to the remaining copper foil. In addition, if such irregularities are present, spots are generated at the time of bonding the copper foil, which causes disconnection and the like as described above.

In order to solve the above problems, first, an attempt was made to increase the density of the glass nonwoven fabric in the pre-predator so as to approach the density of the glass cloth, using a glass fiber having an irregular cross section. The technology is disclosed in Japanese Unexamined Patent Publication No. Hei 7-122322, Japanese Unexamined Patent Publication No. Hei 6-250702 and Japanese Unexamined Patent Publication No. Hei 8-127794. In addition, the use of glass fibers having a flat cross section was considered in order to impart smoothness to an insulating substrate made of a glass nonwoven fabric. However, in the dip impregnation method, which consists of a continuous process of squeezing the resin-impregnated glass non-woven fabric and adjusting the amount of resin contained in the prepreg, it cannot withstand the tensile force applied during this process. However, since the glass nonwoven fabric is cut, sufficient strength must be given to the glass nonwoven fabric in advance. In other words, in order to obtain sufficient strength, it is still necessary to increase the amount of adhesive resin and use a thicker glass nonwoven fabric, and to meet the recent market demand for thinner prepregs for multilayer boards. I couldn't respond.

Furthermore, in the conventional dip impregnation method, the resin penetrates from both sides of the glass non-woven fabric almost simultaneously, and impregnation is carried out.Therefore, air bubbles are likely to remain at the center, and the thicker the non-woven fabric, the more easily the air bubbles remain. It was also a problem. The present invention is directed to a prepreg using a glass nonwoven fabric impregnated with a resin as an insulating substrate, to prevent bubbles remaining when cutting the glass nonwoven fabric substrate and impregnating the resin, and to reduce the glass fiber content. An object of the present invention is to provide a glass nonwoven fabric prepreg for a multilayer printed wiring board which is high, has excellent surface smoothness, and is thin. It is another object of the present invention to continuously and efficiently manufacture such a pre-preda.

Disclosure of the invention The present inventors have studied various methods for impregnating a glass nonwoven fabric substrate with a resin in order to solve the above-mentioned problems. As a result, a liquid resin is applied to one side of a specific carrier sheet, and then a glass non-woven fabric made of highly flat glass fiber is supplied thereon to impregnate the resin, thereby cutting the glass non-woven fabric base and cutting the resin. The present inventors have found that bubbles can be prevented from remaining when the resin is impregnated, and that the resin impregnation amount can be reduced, and the present invention has been completed.

That is, the present invention relates to a prepreg for a multilayer printed wiring board using a glass nonwoven fabric impregnated with a resin as an insulating base material, wherein the insulating base material has a heat-resistant temperature of 150 ° C. or higher. The present invention relates to a multi-layer printed pre-preparator for a torii wire plate, which is laminated on a carrier sheet made of a copper foil, and wherein the glass nonwoven fabric is made of a highly flat glass fiber.

In addition, the present invention provides a method for applying a liquid matrix resin to one side of a carrier sheet made of a synthetic resin film or a copper foil for a circuit having a heat resistance temperature of 150 ° C. or more, and then forming a highly flat glass fiber on the liquid matrix resin. The present invention relates to a method for producing a pre-preda for a multilayer printed wiring board, comprising laminating a glass non-woven fabric composed of a resin, impregnating with a resin, and drying and semi-curing the resin.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic side view of a laminating apparatus used in an embodiment of the method of the present invention.

FIG. 2 is a schematic view of the process of the conventional method.

BEST MODE FOR CARRYING OUT THE INVENTION

In the present invention, it is necessary to use a glass nonwoven fabric made of a highly flat glass fiber. However, in order to obtain a glass nonwoven fabric having a higher tensile strength, the ratio of the major axis to the minor axis of the high flat glass fiber must be 3. : 1 to 8: 1, more preferably 3: 1 to 5: 1, most preferably 3.5: 1 to 4.5: 1.

Furthermore, when highly flat glass fiber is used for the glass nonwoven fabric as in the present invention, the conventional cross-sectional shape is likely to occur in glass fiber having a circular shape, and bubbles occupy a large amount of space in the nonwoven fabric. The problem can be avoided, and the content of glass fibers in the laminate can be increased.

As a result, the resin content of the laminate can be reduced to the same level as glass cloth. .

5 and a laminate having good dimensional stability can be obtained. In addition, when highly flat glass fibers are used for the glass nonwoven fabric, since the highly flat glass fibers are arranged on the surface, it is possible to obtain a smoother laminated board surface than glass cloth, which is preferable. In the glass nonwoven fabric comprising a conventional cross-sectional shape of a glass fiber is circular, than the tensile strength point, its weight per unit area weight is ^{5 0 g / m 2 ~1 0} 0 g / m 2 and is commercially available glass nonwoven It was used for composite copper-clad laminates such as CEM-III, but in the present invention, since highly flat glass fiber is used as the glass nonwoven, a glass nonwoven made of glass fiber having a circular cross-sectional shape has hitherto been used. Glass non-woven fabrics having a basis weight in the range of 10 g / m ^{2 to} 50 g / m ² , which is rarely used in the above, can be used.

In particular, the ratio of the major axis to the minor axis of the glass fiber is 3: 1 to 5: 1, and the equivalent diameter is 9 to 15 (where the equivalent diameter is the dimension representing the cross-section of the flat glass fiber, the same weight, A value expressed in terms of the diameter when converted to a round glass fiber of the same length.) A nonwoven glass nonwoven fabric with a basis weight of 10 gZm ² to 50 gZ m ² using a chopped strand of highly flat glass fiber is density 0. 3~0. 4 5 gr / cm 3 resin content of the laminate is reduced as large as, also, since also have a good dimensional stability of the glass cloth and the same degree, the multilayer of the present invention It is suitable as a pre-preda for printed wiring boards.

The carrier sheet used in the present invention needs to be one that does not deform at the heating temperature when the solvent of the resin impregnated in the glass nonwoven fabric is removed from the viewpoint of securing the tensile strength of the glass nonwoven fabric during the manufacturing process. Specifically, the heat-resistant temperature of polyethylene terephthalate resin (PET), polyphenylene sulfide resin (PPS), polyetherimide resin (pI), polyallyl ether nitrile resin (PEN), etc. It is preferable to use a C or higher synthetic resin film.

For example, when the matrix resin used for the impregnation is an epoxy thermosetting resin FR-4, it is preferable to use a thermoplastic polyester resin film or the like which does not deform at a heating temperature of 150 ° C. for removing the solvent. It is more preferable to use a polyallyl ether nitrile resin (PEN) film having a heat resistance of 170 ° C. or more. In addition, instead of the synthetic resin carrier sheet as described above, A heat-resistant continuous sheet having a smooth surface such as a copper foil for a circuit to be bonded can also be used as a carrier sheet.

The thickness of the carrier sheet is preferably about 0.02 to 1 mm.

The synthetic resin carrier sheet is removed during actual use, and a glass non-woven fabric base or a copper non-foiled glass non-woven fabric base is laminated and used as a prepreg for a multilayer printed wiring board.

On the other hand, those using a circuit copper foil as a carrier sheet can be used as it is for the surface of a double-sided copper-clad printed wiring board or a copper-clad laminate for a multilayer printed wiring board.

The resin to be impregnated into the glass nonwoven fabric that can be used in the present invention is not particularly limited as long as it is a resin that can be dissolved in a solvent and impregnated into the glass nonwoven fabric, but an epoxy resin, an unsaturated polyester resin, or the like is preferable. .

As a method for producing the prepreg of the present invention using these carrier sheets, such a sheet material is sent out onto a flat conveyor that moves as a carrier sheet, and one surface thereof is impregnated with a glass nonwoven fabric in advance. There is a method in which the required resin amount is continuously and uniformly applied, and a glass nonwoven fabric or the like is sequentially laminated thereon. Also, a method of laminating a glass nonwoven fabric on a carrier sheet and supplying a resin from above to impregnate the resin, or a method of applying a resin to the rear surface of the carrier sheet to adjust the amount of adhesion, and then forming a glass nonwoven fabric or the like. The prepreg of the present invention may be manufactured by a method of sequentially supplying and stacking.

In order to uniformly apply the resin to the carrier sheet, a well-known liquid application method such as a kiss roll coater, a knife coater, or a rod coater is used. At this time, since the glass nonwoven fabric is sequentially impregnated so as not to trap air bubbles from one side on the resin surface, air bubbles can be greatly reduced as compared with the conventional one.

After the resin is impregnated into the glass nonwoven fabric, the copper foil can be laminated on the glass nonwoven fabric.

Next, a single-sided copper-foiled glass nonwoven fabric impregnated with resin or a resin-impregnated glass nonwoven fabric without copper foil is brought into contact with a heating roller to remove the solvent of the resin impregnated into the glass nonwoven fabric. Remove and pre-cure. Further, if necessary, a glass nonwoven fabric prepreg can be manufactured more stably and continuously by passing the resin through a pair of heating / pressing ports to ensure the impregnation of the resin into the glass nonwoven fabric substrate. It becomes possible. As described above, in the past, when using a nonwoven glass nonwoven fabric as an insulating base material and laminating it on a continuous line, there was a problem that the tensile strength of the glass nonwoven base material was low or the tensile strength was reduced due to lack of solvent resistance. there were. That is, the adhesive strength of the epoxy resin, acrylic resin, etc., which bonds the glass fibers of the glass nonwoven fabric to each other, is reduced by the solvent in the impregnated resin. Could not be produced.

In the present invention, a carrier sheet is present in the impregnation step to the partial curing step, so that the tensile strength required for handling in the production step can be secured. As described above, in the present invention, even if a glass nonwoven fabric having a small basis weight is used, the glass nonwoven fabric can sufficiently withstand a lamination process in a continuous line, and a multi-layer printed wiring board pre-preda can be stably obtained. That is, the basis weight of the glass nonwoven fabric is desirably 100 g / m ² or less from the viewpoint that the resin is uniformly and completely impregnated. However, according to the production method of the present invention, the basis weight is 1 g / m ^2. the 0 gZm ^² ~5 0 gZ m ² of tensile strength weak nonwoven may also be used.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.

The manufacturing process of the prepreg for a glass-nonwoven copper-clad laminate shown in Fig. 1 consists of a carrier sheet feeder, a resin coating device, a glass nonwoven fabric feeder, a copper foil feeder, a heating roller unit, a trimming device, and a winding device. .

The carrier sheet 1 starts moving by operating the feeding device and the winding device. After supplying the resin to the resin coating device, the kiss coater roller 3 is rotated to form a resin layer, and the carrier sheet 1 is brought into contact with the resin layer 4 on the roller 13 to apply the resin to the carrier sheet. The amount of application is adjusted by calculating the required amount of resin of the base material in advance, adjusting the rotation speed of the kiss coater 3 and the clearance of the guide roller 2, and managing the resin viscosity. . Furthermore, the thickness is made more uniform by squeeze barco 1-5.

Carrier sheet 1 is in a state where resin is evenly applied, and the moving carrier sheet The glass nonwoven fabric 7 is fed out onto the sheet 1 by a glass nonwoven fabric sending device, and is laminated on the resin layer 4 on the carrier sheet 1. At this time, since the glass nonwoven fabric 7 is sequentially impregnated with the resin from one side, bubbles are less likely to be generated.

Further, in a conventional method such as a dip method, bubbles generated when impregnating a glass nonwoven fabric with a resin are trapped in the glass nonwoven fabric. However, according to the present invention, the generation of bubbles itself is unlikely to occur, and the bubbles are further reduced. Even if it occurs, it is not trapped in the glass nonwoven fabric, so that uniform impregnation can be performed.

The preheater 6 is an auxiliary heating device when it is necessary to promote the removal of the solvent in the resin.

If necessary, it is also possible to send out and laminate a circuit copper foil 8 on a resin-impregnated glass non-woven fabric on the carrier sheet 1.

Then, the laminated sheet 9 is brought into a semi-cured state by bringing the impregnated resin into a semi-cured state by bringing the laminated sheet 9 into contact with a heating roller 10 and a heating / pressing roller 11 at 150 to 180 ° C. Trimming to the required width by 2 and winding by a winding device 13 give a continuous glass nonwoven prepreg.

(Example 1)

A high-flat glass fiber with a major diameter: minor diameter of 4: 1 and an equivalent diameter of 13 / zm is used as the glass non-woven fabric, and an epoxy adhesive is applied at a solid content of 6% by weight. It was used in m ^2.

The composition (FR-4 formulation) of the epoxy resin varnish used for impregnation is as follows.

• Epicoat 504-B-80 (Yukaka Epoxy); 100 parts • Epicoat 1554 (Yukaki Epoxy); 20 parts

• Dicyanamide; 4 copies

· Benzyldimethylamine; 0.2 parts

• Dimethylformamide; 30 parts

• Methyl ethyl ketone; 15 parts

As the carrier sheet, a film of a 50 zm polyallyl ether nitrile resin was used. Using these materials, a prepredder was manufactured using the apparatus shown in FIG. 1 described above. The results are shown in Table 1.

Here, for the sample for measuring surface smoothness, the obtained prepreg was cut into 50 cm squares, 10 sheets were laminated, and copper foil with a thickness of 18 m was stacked on both sides, sandwiched between mirror plates, and pressed. It was produced by pressing at a force of 50 kg / cm ² and a temperature of 170 ° C. for 60 minutes. The surface smoothness was measured using a universal shape measuring instrument (manufactured by Kosaka Laboratory Co., Ltd .; trade name: SEF-1A) based on “Surface Roughness Measurement Method” of JISB-0601. Was.

(Example 2)

A prepreg was produced under the same production conditions as in Example 1 except that a circuit copper foil of 18 / zm was used as a carrier sheet and the basis weight of the glass nonwoven fabric was 20 g / m ² . The results are shown in Table 1. The preparation of the surface smoothness measurement sample and the method for measuring the same are the same as in Example 1.

(Comparative Example 1)

A prepreg was manufactured in the same manner as in Example 1 except that a glass nonwoven fabric having a basis weight of 50 g / m ² made of glass fiber having a round cross section was used. The results are shown in Table 1. The preparation of the surface smoothness measurement sample and the measurement method thereof are the same as those in Example 1. (Comparative Example 2)

Using the glass nonwoven fabric used in Examples 1 and 2 and Comparative Example 1, an attempt was made to manufacture a prepreg by a conventional dip method as shown in FIG. However, during the manufacturing process, the sheet of glass nonwoven fabric impregnated with resin was often cut, and the manufacturing itself was difficult. 1 o Table 1

Industrial applicability

As is clear from the above results, the glass nonwoven fabric prepreg for a multilayer printed wiring board of the present invention is a prepreg having a high glass fiber content, excellent surface smoothness, and a small thickness as compared with conventional ones.

Further, in the present invention, the resin is sequentially laminated on the glass nonwoven fabric on the moving carrier sheet, and the resin is impregnated from one side of the glass nonwoven fabric. Even if it occurs, the impregnation can be performed under conditions where air bubbles can easily escape. As described above, according to the present invention, it is possible to solve the problem of the conventional dip impregnation method in which bubbles are trapped in the glass nonwoven fabric during the impregnation, and it is easy to sufficiently impregnate the glass nonwoven fabric with the resin. Therefore, a prepreg sheet having no bubbles and excellent surface smoothness can be obtained.

And while moving the glass non-woven fabric and resin in the presence of the carrier sheet By impregnating the resin into the glass nonwoven fabric, it is possible to use the the tensile strength low glass nonwoven, using glass nonwoven having a basis weight 1 0~5 0 g / m ² which can not be used as the insulating base material so far become able to.

Furthermore, in the present invention, since the amount of emulsion type lumber impregnated in the glass nonwoven fabric can be reduced, the amount of surfactant added to convert the emulsion type resin into an emulsion can be reduced. It is possible to do. Here, this surfactant has an adverse effect on the water resistance and heat resistance of the printed wiring board, etc., and in order to make up for the lack of strength, which has conventionally been desired to reduce the amount thereof. Thus, the amount of the emulsion resin had to be increased, so that the amount of the surfactant could not be reduced to less than 10% by weight in the past. However, by employing the constitution of the present invention, the amount of the surfactant can be significantly reduced to 6% by weight or less.

Claims

The scope of the claims

1. A prepreg for a multilayer printed wiring board including an insulating base material made of a glass nonwoven fabric impregnated with a resin, wherein the glass nonwoven fabric is made of a synthetic resin film having a heat resistance temperature of 150 ° C or more or a copper foil for a circuit. A pre-printer for a multilayer printed wiring board, wherein the glass non-woven fabric is made of highly flat glass fibers laminated on a carrier sheet.

2. The prepreg according to claim 1, wherein a ratio of a major axis to a minor axis of the highly flat glass fiber is 3 _: 1 to 8: 1.

3. The pre-preda for a multilayer printed wiring board according to claim 1, wherein the basis weight of the glass nonwoven fabric is 10 g Zm ^{2 to} 50 g / m ² .

4. A nonwoven glass fabric composed of highly flat glass fiber after applying a liquid resin to one side of a carrier sheet made of a synthetic resin film or copper foil for circuits with a heat resistance temperature of 150 ° C or higher. A method for producing a multi-layer printed wiring board pre-predder, comprising: laminating a glass non-woven fabric with the resin; drying the glass non-woven fabric; and performing a semi-curing treatment.

5. The method according to claim 4, wherein the ratio of the major axis to the minor axis of the highly flat glass fiber is 3: 1 to 5: 1.

6. The method according to claim 4, wherein the basis weight of the glass nonwoven fabric is 10 g / m ² to 50 g / m ² .