JP2006328198A - Prepreg and laminated plate using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a prepreg with low water absorption, excellent in laser processability and provided with flame retardancy without containing halogens, and a laminated plate using the prepreg. <P>SOLUTION: This prepreg is obtained by impregnating an aramid substrate with a resin composition comprising a reactive phosphorus-containing epoxy resin (a), a phenol resin (b) and an inorganic filler (c). The laminated plate is obtained by using the prepreg. Further preferably, the content of the inorganic filler (c) is 10-80 pts.wt. to 100 pts.wt. of the resin, the average particle diameter thereof is 0.1-20 μm and the inorganic filler comprises aluminum hydroxide. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a prepreg used for manufacturing a printed wiring board used for electric / electronic devices and the like, and a laminate using the prepreg.

Conventionally, prepregs for printed wiring boards used in electrical and electronic devices are made of a thermosetting resin varnish obtained by dispersing a resin composition containing an epoxy resin or the like in a base material made of glass fiber or the like. After impregnation, it is produced by drying by heating and semi-curing. Then, the required number of the prepregs are stacked, and copper foil is stacked on one or both sides as necessary, and a copper-clad laminate is created by laminating and heating it, and then processing this to produce printed wiring I'm getting a board.
The electrical connection between the conductor layers of this printed wiring board is made through through holes and via holes. In recent years, to reduce the size and weight of electrical and electronic equipment, the diameter of these through holes and via holes is reduced and the processing accuracy is reduced. Improvement is desired. In order to solve this problem, through holes are formed by irradiating a laser beam to the insulating layer of a printed wiring board, and the inner surface thereof is plated or filled with a conductive paste. And via holes are formed. However, in a prepreg using a glass base material, the base material is difficult to be removed by laser processing, so that the workability is poor.
Therefore, studies have been made on using an aramid base material excellent in laser processability instead of a glass base material. This aramid base material is not only excellent in laser processability, but also has a problem that it is lighter and better in mechanical strength than a glass base material, but has a high water absorption rate.
On the other hand, as a resin composition to be impregnated into a prepreg, an epoxy resin is a main component, and a bromine-containing aromatic compound such as tetrabromobisphenol A is added to add flame retardancy, or in the epoxy resin skeleton. Although bromine was often introduced, these halogen compounds such as bromine are required to be reduced from the environmental and hygiene viewpoints. In addition, since bromine is easily decomposed at high temperatures, some have problems with high-temperature heat resistance. Therefore, in recent years, phosphorus compounds are sometimes used in place of these halogen compounds.
For example, JP-A-2002-348354 discloses a prepreg in which a base material made of aramid fibers is impregnated with a resin composition containing a phosphate ester. In this product, an aramid fiber is used as a base material, so that laser workability is excellent, and phosphoric acid ester is used to impart flame retardancy without halogen. Here, phosphorus compounds such as the phosphoric acid ester used as a flame retardant are roughly classified into a reaction type that reacts directly with an epoxy resin and an addition type that does not react directly. When an additive-type phosphorus compound is used, elution of the phosphorus compound has been confirmed from the resin composition to the outside during the plating process or reliability test, which is not particularly preferable for use in electrical insulation applications. I know it. On the other hand, when a reactive phosphorus compound is directly mixed in a curing agent or an epoxy resin, there is a possibility that the crosslinking reaction between the curing agent and the epoxy resin may be hindered.
JP 2002-348354 A

  The present invention has been made in view of the above points, and is to provide a prepreg having excellent laser processability, halogen-free flame retardancy, low water absorption, and a laminate using the prepreg. .

  In order to solve the above problems, the prepreg according to claim 1 of the present invention contains (a) a reactive phosphorus-containing epoxy resin, (b) a phenol resin, and (c) an inorganic filler. An aramid base material is impregnated with the resin composition.

  The prepreg according to claim 2 is characterized in that the content of (c) the inorganic filler is 10 to 80 parts by weight with respect to 100 parts by weight of the resin.

The prepreg according to claim 3 is characterized in that (c) the inorganic filler has an average particle size of 0.1 to 20 μm.
The prepreg according to claim 4 is characterized in that (c) the inorganic filler contains aluminum hydroxide.

  In the laminated board which concerns on Claim 5, it produced using the prepreg in any one of Claims 1-4, It is characterized by the above-mentioned.

  According to the prepreg according to claim 1 of the present invention, a resin composition comprising (a) a reactive phosphorus-containing epoxy resin, (b) a phenol resin, and (c) an inorganic filler is used as an aramid substrate. As a result of being impregnated, the laser processability is excellent, and flame retardance can be imparted without halogen, and since the water absorption is small, the adhesion and heat resistance are excellent. In addition, since a reactive phosphorus-containing epoxy resin is used, elution of the phosphorus compound from the resin composition to the outside is suppressed, resulting in excellent electrical insulation, and crosslinking between the epoxy resin and the curing agent. It does not interfere with the reaction.

  Further, according to the prepreg according to claim 2 of the present invention, since the content of the inorganic filler (c) is 10 to 80 parts by weight with respect to 100 parts by weight of the resin, it retains flame retardancy and has a water absorption rate. Suppressing and moldability are also improved.

  Further, according to the prepreg according to claim 3 of the present invention, (c) since the average particle size of the inorganic filler is 0.1 to 20 μm, the viscosity of the resin composition is suppressed from being increased, and a circuit having a narrow pitch is used. Even in the formation, the inorganic filler particles do not adversely affect the circuit formation, and the insulation is sufficiently maintained.

  Further, according to the prepreg according to claim 4 of the present invention, since (c) the inorganic filler contains aluminum hydroxide, the flame retardancy is further improved.

  Further, according to the laminate of claim 5 of the present invention, it is possible to provide a laminate having excellent laser processability, halogen-free flame retardancy, and excellent adhesion and heat resistance due to a decrease in water absorption. Obtainable. In addition, since the reactive phosphorus-containing epoxy resin is used, elution of the phosphorus compound from the resin composition to the outside can be suppressed, and a laminate having excellent electrical insulation can be obtained.

Hereinafter, embodiments of the present invention will be described. A prepreg and a laminate using the prepreg according to the present embodiment are obtained by using an aramid resin composition comprising (a) a reactive phosphorus-containing epoxy resin, (b) a phenol resin, and (c) an inorganic filler. The substrate is impregnated.
Although it does not specifically limit as an aramid base material, For example, the aramid fiber nonwoven fabric etc. which have the para-aramid generally used as a main component are applicable. Since para-aramid is excellent in electrical insulation, it is suitable for use in electrical insulation, such as a printed wiring board. This aramid fiber nonwoven fabric can be used in combination with a resin binder for binding fibers together. Although it does not specifically limit as a resin binder, 1 type, or 2 or more types combined use is possible among fibrides of a meta-aramid fiber chop, a meta-aramid film, para-aramid fiber pulp, etc.
(A) The reactive phosphorus-containing epoxy resin is not particularly limited as long as it contains a phosphorus element in the molecule and has two or more reactive epoxy groups in one molecule. By using this reactive phosphorus-containing epoxy resin, flame retardancy can be imparted, and elution of the phosphorus compound from the resin composition when using an additive-type phosphorus compound can be prevented. Further, the cross-linking reaction between the curing agent and the epoxy resin is not hindered as when the reactive phosphorus compound is directly mixed with the curing agent or the epoxy resin. The reactive phosphorus-containing epoxy resin may be used alone or in combination with other epoxy resins. Examples of other epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, novolac type epoxy resins, dicyclopentadiene type epoxy resins, biphenyl type epoxy resins, and naphthalene type epoxy resins. By using another epoxy resin in combination, other properties other than flame retardancy can be imparted. However, it is limited to a range that can ensure flame retardancy. As a specific guideline, the phosphorus content relative to the resin is preferably 1.8% by mass or more. Here, the resin includes a reactive phosphorus-containing epoxy resin, another epoxy resin, and a phenol resin described below.
(B) Although it does not necessarily limit as a phenol resin, a phenol novolak type phenol resin, a cresol novolak type phenol resin, a bisphenol A type phenol resin, a dicyclopentadiene type phenol resin, a biphenyl type phenol resin, a naphthalene type phenol Resins can be used. By using these phenolic resins as curing agents, the hydrophilicity due to nitrogen atoms is eliminated compared to the case of using dicyandiamide, which is generally used as a curing agent, so that the water absorption rate of the laminate can be reduced. It becomes possible. These phenolic resins may be used alone or in combination of two or more. Moreover, it is preferable that the compounding quantity is the range of 0.8-1.2 by an equivalent ratio with respect to the total amount of (a) reactive phosphorus containing epoxy resin and the other epoxy resin used together with it. In a region exceeding this range, a large amount of the resin (epoxy resin or phenol resin) excessively contained at the time of blending after the reaction remains, which may undesirably deteriorate the properties of the cured product.
(C) The inorganic filler is not particularly limited, and metal hydroxide, silica powder, talc, clay, glass fiber and the like can be used alone or in combination of two or more. Can be reduced. In particular, it is preferable to use aluminum hydroxide as a main component from the viewpoint of imparting flame retardancy. The inorganic filler may be subjected to a coupling treatment using a coupling agent such as a silane coupling agent.

  The content of these (c) inorganic fillers is preferably between 10 and 80 parts by weight with respect to 100 parts by weight of the resin, more preferably between 20 and 70 parts by weight, and compatibility between flame retardancy and varnish stability. From this viewpoint, the amount is more preferably 20 to 60 parts by weight. (C) If the content of the inorganic filler is less than 10 parts by weight, improvement of the water absorption rate and adhesion at the time of producing the laminate is not seen, and if it is contained by 80 parts by weight or more, it is difficult to ensure the moldability of the laminate become. Here, the resin includes a reactive phosphorus-containing epoxy resin and a phenol resin, and also includes other epoxy resins in combination with the reactive phosphorus-containing epoxy resin.

  Furthermore, the average particle size of these (c) inorganic fillers is preferably in the range of 0.1 to 20 μm. More preferably, it is 0.5-15 micrometers, and it is still more preferable that it is 1-10 micrometers from a viewpoint of varnish stability and miniaturization correspondence. As a result, the moldability is improved by suppressing the increase in the viscosity of the resin composition, and the inorganic filler particles do not adversely affect the circuit formation even in the formation of a narrow pitch circuit, and the insulation is sufficiently maintained. Therefore, the circuit can be finely processed. (C) When the average particle size of the inorganic filler is less than 0.1 μm, the specific surface area of the filler is increased, and thus there is a possibility that adverse effects such as viscosity improvement may occur when blending varnish, and the particle size larger than 20 μm Use of such a material is not preferable, especially when a narrow-pitch circuit is formed, and if inorganic filler particles are present in the wiring portion, the circuit formation is adversely affected and the insulation properties are significantly reduced.

  A catalyst can be used for these resin compositions as needed. Specifically, tertiary catalysts such as benzyldimethylamine, quaternary ammonium salts such as tetramethylammonium chloride, phosphines such as triphenylphosphine, and various catalysts such as imidazole can be used. These catalysts may be used alone or in combination of two or more.

  Moreover, it is also possible to use a solvent together at the time of varnish adjustment. Specifically, ketones such as acetone and methyl ethyl ketone, ethers such as propylene glycol monobutyl ether and ethylene glycol monomethyl ether, and aromatic hydrocarbons such as benzene and toluene can be used. These solvents may be used alone or in combination of two or more.

  The method for producing the prepreg from the epoxy resin composition and the base material is not particularly limited. For example, the base material is immersed in a resin varnish prepared by dispersing the epoxy resin composition in a solvent. After impregnating the epoxy resin composition, the resin component is semi-cured (B-stage) by heating and drying.

  Next, the laminated board of this invention is demonstrated.

  The laminate of the present invention is a laminate obtained by laminating the above-described prepreg. In the laminated plate in the present invention, one laminate of the prepreg described above, or a laminate of the required number of prepregs, a metal foil such as copper foil is arranged on one or both sides to constitute a laminate, Also included are metal foil-clad laminates laminated and integrated by heating and pressurizing this laminate, and laminates with inner layer circuits produced by integrating metal foils, prepregs, and so-called core materials forming inner layer circuits. .

Hereinafter, the present invention will be described with reference to examples and comparative examples, but the present invention is not limited thereto.
[Preparation of prepreg]
[Example 1]
(A) 100 parts by weight of FX289 manufactured by Toto Kasei Co., Ltd. as a reactive phosphorus-containing epoxy resin, 5 parts by weight of YD128 manufactured by Toto Kasei Co., Ltd. as an epoxy resin, (b) TD2090 manufactured by Dainippon Ink & Chemicals, Inc. as a phenol resin 35 parts by weight, Shikoku Kasei Co., Ltd. 2E4MZ 0.1 parts by weight as a curing accelerator, (c) 30 parts by weight of Admatex spherical silica SO-25R (average particle size 3 μm) as an inorganic filler And dispersed in MEK solvent. In order to improve dispersibility, filler dispersion treatment was performed with a disperser (bead mill), and this was used as a resin varnish.

  The resin varnish was impregnated with Aramid nonwoven fabric N718 # 80 manufactured by DuPont Teijin Advanced Paper Co., Ltd. and dried at 160 ° C. for 5 minutes to prepare a B-stage prepreg.

[Example 2]
(C) A prepreg was produced in the same manner as in Example 1 except that 30 parts by weight of CL-303 (average particle size 3 μm) manufactured by Sumitomo Chemical Co., Ltd., which is aluminum hydroxide, was used as the inorganic filler.

[Comparative Example 1]
(B) A prepreg was produced in the same manner as in Example 1 except that no phenol resin was used and 3.5 parts by weight of dicyandiamide was used instead as a curing agent.

[Comparative Example 2]
(C) A prepreg was produced in the same manner as in Example 1 except that the resin varnish was adjusted without using an inorganic filler.

[Flame Retardancy Evaluation Board Fabrication Method]
Eight prepregs obtained in each example and comparative example were laminated, 18 μm thick copper foil was placed on both sides, and vacuum-pressing was performed at 190 ° C. and 2.94 MPa for 60 minutes to cure the prepreg. And laminated and integrated to form a double-sided copper clad laminate having a thickness of 0.8 mm ± 0.1 mm.

  After removing the surface copper foil by etching on this laminate, a vertical combustion test was conducted according to UL94 to evaluate flame retardancy. The evaluation results are shown in Table 1 in the order of average burning time (seconds) / maximum burning time (seconds). In addition, the number of samples measured in each laminated board is n = 5 according to UL94.

[Substrate water absorption measurement method]
The etched laminate obtained by the method described in the above flame retardant evaluation substrate preparation method was dried at 120 ° C. for 60 minutes, cooled in an environment that did not absorb moisture, and then the initial weight was measured. This substrate was treated at 121 ° C. and 100% humidity for 20 hours, and the weight after treatment was measured. The water absorption rate was calculated from the weight change between the post-treatment weight and the initial weight.

[Substrate-resin adhesion measuring substrate preparation method]
A double-sided copper-clad laminate was prepared using the prepregs obtained in each Example and Comparative Example by the method described in Flame Retardancy Evaluation Board Preparation Method. After roughening the surface copper foil on both sides, the prepregs obtained in each Example and Comparative Example were placed on both sides of the double-sided copper-clad laminate, and a copper foil with a thickness of 18 μm was placed on the outside. Then, vacuum heating and pressure molding was performed at 190 ° C. and 2.94 MPa for 60 minutes to cure the prepreg and laminate and integrate to prepare a four-layer plate. The copper foil on one side surface of this four-layer plate is partially removed to form a 2 mm square electrode, and a test pin is soldered vertically on the electrode, and this is performed at 121 ° C. and 100% humidity for 20 hours. After the treatment, a lateral load was applied to a predetermined position of the test pin, and the breaking position and breaking strength when the test pin was put down with the pad were measured at 10 points. When soldering the test pin, the amount of solder depends on its strength, so the solder amount was made constant by printing with a metal mask using cream solder. Regarding the fracture position, it is preferable that the fracture occurs in the base material in order to measure the adhesion between the base material and the resin. For the breaking strength, the average value of each measured value was obtained.
The results are shown in Table 1.

表１に示すように、実施例１及び２の本願発明のプリプレグ及びそれを用いた積層板は、難燃性に優れ、且つ、吸水率も小さいために強度も強くなっていることが分かる。

As shown in Table 1, it can be seen that the prepregs of the present invention of Examples 1 and 2 and the laminates using the prepreg are excellent in flame retardancy and have a low water absorption rate, so that the strength is increased.

  Moreover, when Example 2 and Example 1 are compared, since aluminum hydroxide is used as an inorganic filler, it turns out that a flame retardance is further improved.

Claims (5)

  A prepreg comprising an aramid base material impregnated with a resin composition comprising (a) a reactive phosphorus-containing epoxy resin, (b) a phenol resin, and (c) an inorganic filler.   (C) Content of an inorganic filler is 10-80 weight part with respect to 100 weight part of resin, The prepreg of Claim 1 characterized by the above-mentioned.   (C) The average particle diameter of an inorganic filler is 0.1-20 micrometers, The prepreg of Claim 1 or 2 characterized by the above-mentioned.   (C) The prepreg according to any one of claims 1 to 3, wherein the inorganic filler contains aluminum hydroxide.   A laminate comprising the prepreg according to any one of claims 1 to 4 laminated.