JP4778833B2 - Laminate substrate and prepreg, and laminate - Google Patents

Description

  The present invention relates to an aromatic polyamide fiber paper that is excellent in heat resistance and electrical insulation and can be suitably used for laminates for electric circuits. More specifically, the present invention relates to high strength and low moisture absorption, and further to heat resistant dimensional stability. The present invention relates to a laminate base material that can be suitably used for an electrical circuit laminate, a prepreg comprising the same, and a laminate.

  Base materials used in laminates for electric circuit boards have characteristics such as heat resistance, heat-resistant dimensional stability, moisture-resistant dimensional stability, electrical insulation, and deformation resistance (not easily torsion, warpage, undulation, etc.) Is required. In addition, for small electronic devices such as mobile phones and laptop computers, it is necessary to increase the density. Therefore, various characteristics such as lightness and thinning are required in addition to the above characteristics. Aromatic polyamide fiber paper is superior to other paper base materials in terms of heat resistance, electrical insulation, heat-resistant dimensional stability, lightness, etc. It has come to be used well as a base material for laminates for circuit boards.

  For example, polyparaphenylene terephthalamide short fiber ("Kevlar" manufactured by DuPont) and copolyparaphenylene 3,4'-oxydiphenylene terephthalamide short fiber ("Technora" manufactured by Teijin Techno Products Co., Ltd.) Aromatic polyamide fiber paper made of an organic resin binder (Japanese Patent Laid-Open No. 1-92233) and a method for producing aromatic polyamide paper (Japanese Patent Laid-Open No. 2-47392) have been proposed.

  However, the aromatic polyamide fiber paper described in the patent has a limitation in thinning because the wet paper is easily cut during the wet papermaking process. In addition, since the heat resistance of the binder resin is inferior to that of aromatic polyamide, the performance of the laminate for electrical circuits, especially the flow of lead-free solder, decreases mechanical properties due to deterioration of the binder resin, and absorbs moisture. There has been a problem of lowering.

  In addition, para-aramid paper (such as Japanese Patent Publication No. 5-65640) composed of polyparaphenylene terephthalamide short fibers and polymetaphenylene isophthalamide fibrids has been proposed. The use of polymetaphenylene isophthalamide fibrids has the effect of making the wet paper difficult to cut in the wet papermaking process, but the paper strength does not increase so much, and there is a limit to making it thinner. Because isophthalamide fibrids are inferior in heat resistance to para-type aromatic polyamides, when they are used as laminates for electrical circuits, they are generated due to the transmission of large volumes of information, which is required especially for the recent high performance of portable devices. Since the laminated board cannot withstand the temperature rise and the moisture absorption is large, the dimensional change at the time of temperature rise becomes large, which is not preferable.

JP-A-1-92233 JP-A-2-47392 Japanese Patent Publication No. 5-65640

  The object of the present invention is to solve the problems of heat resistance, heat-resistant dimensional stability, and thinning, which have been problems of laminated base materials using aromatic polyamide fibers, and can be increased in density and large. An object of the present invention is to obtain a laminated board substrate that can withstand the temperature rise of the laminated board due to transmission of capacity information.

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention have constituted a laminated board base material from aromatic polyamide fibers, an aromatic polyamide pulp and, if necessary, an organic resin binder, of which an aromatic polyamide Laminate which is excellent in heat-resistant dimensional stability and can be thinned when a pulp made of para-type aromatic polyamide and having a drying shrinkage of 10% or more is used as the pulp. The present inventors have found that a base material for use can be obtained, and have reached the present invention.

That is, according to the present invention, there is provided a laminate base material mainly composed of para-type aromatic polyamide short fibers and aromatic polyamide pulp, and the aromatic polyamide pulp has a drying shrinkage of 10% or more. consists polyparaphenylene terephthalamide, it is and the polyparaphenylene terephthalamide pulp more than 10% of the total weight base material laminate, provides laminate base material, characterized in that contained 30% .

  According to the laminated board substrate of the present invention described above, the strength of the substrate can be particularly improved by using a pulp made of para-type aromatic polyamide and having a high drying shrinkage rate. It can be a material. Moreover, the high heat resistance of para-type aromatic polyamide can also improve the heat-resistant dimensional stability of the substrate. Therefore, the laminate for an electric circuit board using the base material is thin and excellent in heat-resistant dimensional stability, so that the density can be increased and it can be suitably used as a base material for a semiconductor wiring board or a flexible printed wiring board. .

Hereinafter, the present invention will be described in detail.
The base material for laminated boards in this invention consists of a heat resistant fiber paper formed by using an aromatic polyamide short fiber, an aromatic polyamide pulp and, if necessary, an organic resin binder as main components.

  In the present invention, the prepreg refers to a single sheet obtained by impregnating a base material such as a nonwoven fabric (paper) with a thermosetting resin and dried, and the laminated plate refers to a plurality of prepregs formed by heating and pressing. Or the one with metal foil attached to it. Moreover, what is called a multilayer board which has a printed wiring in an inner layer and a surface layer is also included.

In the present invention, the aromatic polyamide is an aromatic homopolyamide or aromatic copolyamide in which 80 mol% or more (preferably 90 mol% or more) of the repeating units constituting the polyamide is represented by the following formula (1): It is the short fiber which consists of. Here, Ar ₁ and Ar ₂ represent an aromatic group, and among them, those composed of the same or different aromatic groups selected from the following formula (2) are preferable. However, the hydrogen atom of the aromatic group may be substituted with a halogen atom, a lower alkyl group, a phenyl group, or the like.

Regarding the production method and fiber characteristics of such aromatic polyamide fibers, for example, British Patent No. 1501948, US Pat. Nos. 3,733,964, 3,767,756, 3,869,429, and Japanese Patent JP-A-49-100322, JP-A-47-10863, JP-A-58-144152, JP-A-4-65513, etc. An aromatic polyamide short fiber is mentioned, which is a short fiber made of polyamide in which the chain bond of the aromatic polyamide is coaxial or parallel and is directed in the opposite direction. For example, Ar ₁ , Ar ₂ is a polyamide in which 80 mol% or more of ₂ is a para-coordinate aromatic group.

  Specifically, polyparaphenylene terephthalamide short fibers (for example, “Kevlar” manufactured by DuPont Co., Ltd.), copolyparaphenylene 3,4′-oxydiphenylene terephthalamide short fibers (manufactured by Teijin Techno Products Co., Ltd.) “Technola”) and the like are exemplified, and the latter is particularly preferable because the content of impure ions is small and the electrical insulation is excellent.

  The ratio of the para-type aromatic polyamide short fibers to the total weight of the laminate base material is preferably 50 to 98% by weight. More preferably, it is 60 to 95% by weight. When the ratio is out of the above range, the thermal dimensional stability of the obtained laminated board base material is poor, which is not preferable.

  Moreover, it is preferable that the short fiber fineness of said para type | mold aromatic polyamide short fiber is 0.11-5.5 dtex. If it is less than 0.11 dtex, there are many difficult points in terms of the spinning technique, and it is not only difficult to stably produce fibers of good quality due to the occurrence of yarn breakage and fluff, but it is also preferable because the cost increases. Absent. On the other hand, if it exceeds 5.5 dtex, the mechanical properties of the fiber, particularly the strength, will be greatly reduced, and it will be difficult to generate a paper break in the production process of the base material.

Aromatic polyamide pulp used in the present invention comprises a poly-para-phenylene terephthalamide and, drying shrinkage of the polyparaphenylene terephthalamide is characterized by using a pulp of 10% or more.

Here, the aromatic polyamide pulp is a general term for thin leaf-like or scaly pieces having fine fibrils made of aromatic polyamide, or randomly short fibrillated microfibers. Examples of the aromatic polyamide pulp, For example, Japanese Patent Publication 35-11851, JP-B-37-5732 and JP according to the method described in such as WO2004 / 99 476, the polymer weight organic polymer polymer solution It is produced by mixing in a system in the presence of a shearing force with a precipitant of a coalesced solution. The polyparaphenylene terephthalamide pulp having a drying shrinkage rate of 10% or more according to the present invention is suitable for large-scale continuous production since it has a function of a binder that shrinks during drying and bonds short fibers to each other. pulp that is described in 99476 is optimal from the point that excellent resistance to thermal dimensional stability.

The drying shrinkage of the pulp in the present invention is a para-type aromatic polyamide pulp, a 100 g / m ² paper is made by a known wet paper making method using a tappy paper machine, the wet paper sheet area immediately after paper making, The wet paper sheet is calculated from the area of a sheet obtained by drying the wet paper sheet at 120 ° C. for 5 hours under no pressure by the following formula.
(Dry shrinkage) = [(sheet area with wet paper) − (sheet area after drying)] / (sheet area with wet paper) × 100

  The drying shrinkage of the para-type aromatic polyamide pulp is 10% or more, preferably 15% or more. By using such a pulp having a high drying shrinkage rate, fine fibrils shrink with drying when wet paper is dried and entangle with other fibers, firmly connecting short fibers together, and as a result, the substrate strength is increased. It is possible to obtain a high-strength base material that can withstand continuous production even if it rises and thins. On the other hand, a drying shrinkage ratio of less than 10% is not preferable because the base material cannot be given strength sufficient to withstand continuous production when the base material strength does not increase and thinned.

Further, percentage of laminate base material in the present invention the pulp is 10 to 30 wt%. The blending may be determined while ascertaining the required characteristics of the target laminate for an electric circuit, such as the basis weight of the base material and the dimensional stability when used as a laminate. In any case, if the mixing ratio of the pulp exceeds 30 % by weight, the resulting bulk density of the laminate base material becomes too high, impairing the impregnation of the blended varnish, which is not preferable.

Also, the aromatic polyamide pulp, that have a function as a binder allowed to coupling between the short fibers in the wet papermaking process.

  The laminate substrate described above can be produced by a conventionally known method. For example, copolyparaphenylene / 3,4′-oxydiphenylene / terephthalamide short fibers are weighed to a predetermined ratio, and the fiber concentration is about 0.15 to 0.40% by weight in water. After adding a dispersing agent and a viscosity adjusting agent to the adjusted aqueous slurry as necessary, the wet paper is formed by a wet paper making method using a paper machine such as a long net type or a round net type. If the wet paper is formed, if necessary, an organic binder resin is applied to the weight of a predetermined solid content ratio by a spray method or the like, and then dried to obtain a dry paper having a predetermined bulk density range. An aromatic polyamide fiber paper can be obtained by heating and pressing so that

  The aromatic polyamide fiber paper of the present invention described above can be produced by a conventionally known method (process). For example, para-type aromatic polyamide short fibers and para-type aromatic polyamide pulp are weighed to have a predetermined ratio, and the fiber concentration (including pulp) is about 0.15 to 0.40% by weight. After adding a dispersing agent and a viscosity adjusting agent to the aqueous slurry that has been uniformly dispersed and adjusted after being introduced into water as described above, the wet slurry is added by a wet papermaking method using a paper machine such as a long net type or a round net type. A dry paper obtained by forming paper and drying the wet paper can be heated and pressed to obtain a laminate base material having a desired basis weight, thickness, and heat-resistant dimensional stability.

  The conditions for the heat and pressure processing are, for example, when a heat and pressure is applied using a calendar machine, one hard surface roll having a diameter of about 15 to 80 cm, and a surface deformable elastic roll having a diameter of about 30 to 100 cm Between the two hard surface rolls having a diameter of about 20 to 80 cm. In addition, since there is a process of high-temperature heat treatment at 240 ° C. or higher in the manufacturing process of the laminate for electric circuit boards, if a heat history higher than this heat treatment temperature is given to the substrate in advance, the heat of the paper in this heat treatment process It is more preferable because it suppresses dimensional change and internal strain induction, and improves the heat-resistant dimensional stability and deformation resistance of the resulting laminate. According to the study by the present inventors, it is optimal to calender at a temperature of 300 to 400 ° C. and a linear pressure of 1764 to 3920 N / cm, and the aromatic polyamide fiber paper produced under these conditions is An excellent heat-resistant dimensional stability and excellent tensile strength can be obtained. If the heating and pressing conditions exceed 400 ° C. and 3920 N / cm, it is not preferable because paper breakage occurs during calendar processing.

By such a heating and pressing process, the bulk density of the aromatic polyamide fiber paper of the present invention is in the range of 0.55 to 0.90 g / cm ³ , preferably 0.60 to 0.85 g / cm ³ . It is possible to adjust and control in the papermaking process so as to enter.

  Hereinafter, the present invention will be described in more detail with reference to examples. In addition, the preparation method of the test piece used in the Example and its evaluation method are as follows.

(1) Preparation of para-type aromatic polyamide pulp Polyparaphenylene terephthalamide (“Twaron” manufactured by Teijin Twaron Co., Ltd.) was used and manufactured according to the method of WO 2004/99476 (referred to as Twaron pulp 1). The drying shrinkage ratio of this pulp calculated by the above formula was 29.4%.

(2) Production of base material for laminate plate Para type aromatic polyamide short fibers and the para type aromatic polyamide pulp prepared in the above (1) are dispersed in water, resulting in a concentration of 0.02%. Thus, a dispersing agent (“YM-80” manufactured by Matsumoto Yushi Co., Ltd.) was added to prepare a slurry having a fiber (including pulp) concentration of 0.15 wt%.
Next, using a tappy type square paper machine, paper is made using the slurry, and after light pressure dehydration, the mixed paper is dried at a temperature of 110 ° C., and a calender device having a pair of metal rolls Temperature: 200 ° C. to 350 ° C., linear pressure: 1960 N / cm (200 kg / cm), calendar speed: 4 m / min, and calendering was performed to obtain an aromatic polyamide fiber paper having a basis weight of 15 g / m ² . .

(3) Basis weight of paper Measured according to JIS P 8124.

(4) Paper thickness and bulk density Measured in accordance with JIS P 8118.

(5) Breaking length Measured according to JIS P8113.

(6) Thermal dimensional change rate of paper Using a high-precision two-dimensional coordinate measuring machine (manufactured by Mutou Industry Co., Ltd.), in the length direction of a sample having a length of 250 mm and a width of 50 mm, before heat treatment and at a temperature of 300 ° C. for 5 minutes. The length after heat treatment was measured, and the thermal dimensional change rate was calculated by the following formula. In addition, the sample for a measurement was extract | collected and measured from the length direction of the continuous paper, and the width direction, and compared and determined by the average value.
Thermal dimensional change rate (%) = {(| Length before heat treatment−Length after heat treatment |)
/ Length before heat treatment} × 100

(7) Deformation amount of laminated board Epoxy resin composition comprising dicyandiamide as curing agent and 2-ethyl-4methylimidazole as curing accelerator in high purity brominated bisphenol A type epoxy resin and orthocresol novolac type epoxy resin After impregnating the blended varnish obtained by dissolving the product in a mixed solution of methyl ethyl ketone and methyl cellosolve into the aromatic polyamide fiber base material, it is dried at a temperature of 110 to 120 ° C. for 5 to 10 minutes to contain a volume of resin content A B-stage prepreg paper having a rate of 55% was prepared.
The prepreg paper is laminated on both sides of a copper foil having a thickness of 12 μm, and the same copper foil is further laminated on the outside thereof. The hot press is pressed under reduced pressure at 170 ° C. × 40 kg / cm × 50 minutes. Then, the resin was cured to produce a laminated board for an electric circuit board, and further subjected to a curing treatment in a hot air dryer at a temperature of 200 ° C. for about 20 minutes.
This laminated board for electric circuit boards is cut into a 150 mm square, the copper foil on both sides is left in a frame shape with a width of 20 mm from the end of the laminate, and the copper foil is removed by etching the 110 mm square equivalent part of the central part. Remove and make a sample for evaluation.
The maximum deformation amount starting from the central portion when the partially etched electrical circuit laminate is heat-treated at 300 ° C. for 10 minutes is determined as the deformation amount.

[Examples 1 to 3, Comparative Example 1]
As aromatic polyamide short fibers, copolyparaphenylene • 3,4′-oxydiphenylene / terephthalamide short fibers (“Technola” manufactured by Teijin Techno Products Co., Ltd.) and Twaron pulp 1 described in the above (1) are shown in Table 1. The base material for laminated boards which consists of an aromatic polyamide was produced using the method of said (2), mix | blending so that it might become the ratio shown in (4). Table 2 shows various properties of the substrate evaluated by the measurement methods (3) to (7).

[Example 4 ]
In Example 1, it carried out similarly to Example 1 except having used the polyparaphenylene terephthalamide short fiber ("Twaron" by Teijin Twaron Co., Ltd.) as an aromatic polyamide short fiber, and produced the base material for laminated boards. . Various properties of this substrate evaluated by the measuring methods (3) to (7) were as shown in Table 2.

[Comparative Example 2]
In Example 1, instead of using the Twaron pulp 1 described in the above (1), a polymer solution composed of polymetaphenylene isophthalamide (“Conex” manufactured by Teijin Techno Products Co., Ltd.) is used. Pulp made by mixing in an existing system was used. The drying shrinkage percentage of this pulp calculated by the above formula was 20.5%. Except having used this pulp, it implemented similarly to Example 1 and produced the base material for laminated boards. Various properties of this substrate evaluated by the measuring methods (3) to (7) were as shown in Table 2.

[Comparative Example 3]
In Example 1, instead of using the Twaron pulp 1 described in the above (1), a pulp obtained by randomly fibrillating polyparaphenylene terephthalamide short fibers by applying mechanical shearing force (“Twaron 1094” manufactured by Teijin Twaron) ) Was used. The drying shrinkage percentage of this pulp calculated by the above formula was 4.0%. Except having used this pulp, it implemented similarly to Example 1 and produced the base material for laminated boards. Various properties of this substrate evaluated by the measuring methods (3) to (7) were as shown in Table 2.

[Comparative Example 4]
In Example 4, instead of using the Twaron pulp 1 described in the above (1), instead of using a water dilution of a bisphenol A epichlorohydrin type water-dispersible epoxy resin binder (manufactured by Dainippon Chemical Co., Ltd.) A substrate for laminates was produced in the same manner as in Example 4 except that the resin was sprayed so that the solid content adhered amount was 20% by weight. Various properties of this substrate evaluated by the measuring methods (3) to (7) were as shown in Table 2.

  The laminated board for an electric circuit board using the laminated board substrate of the present invention is thin and excellent in heat-resistant dimensional stability, so that it can be densified and is suitable as a substrate for semiconductor wiring boards and flexible printed wiring boards. Can be used.

Claims (4)

A substrate for a laminate comprising a para-type aromatic polyamide short fiber and an aromatic polyamide pulp as main components, wherein the aromatic polyamide pulp comprises polyparaphenylene terephthalamide having a drying shrinkage of 10% or more, And the base material for laminated boards in which this polyparaphenylene terephthalamide pulp is contained 10 % or more and 30 % or less with respect to the total weight of the laminated board base materials. The base material for laminated boards of Claim 1 whose para type | mold aromatic polyamide short fiber is a short fiber which consists of polyparaphenylene terephthalamide and / or copolyparaphenylene * 3,4'-oxydiphenylene terephthalamide. It is the prepreg formed by impregnating the thermosetting resin to the base material for laminated boards, Comprising: This base material for laminated boards is a base material for laminated boards of any one of Claims 1-2. A prepreg characterized by that. It is a laminated board formed by heat-press-molding the base material for laminated boards impregnated with the thermosetting resin, Comprising: The laminated board base material is the lamination | stacking of any one of Claims 1-2. A laminated board characterized by being a board substrate.