JP2011017025A - Epoxy resin composition and circuit board comprising insulating layer formed from the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new halogen-free epoxy resin composition capable of forming an insulating layer having flame retardance and insulating properties required for a circuit board and to provide the circuit board comprising a flame retardant insulating layer formed from the epoxy resin composition.SOLUTION: The epoxy resin composition comprises an epoxy resin, a curing agent for the epoxy resin, a resorcinol type phosphoric ester, aluminum hydroxide and an epoxy curing accelerator. A circuit board 10 is a circuit board of a multilayered structure comprising a core board 1 and at least one set of insulating layers 2 and wiring layers 3 alternately formed on the core board 1 and at least one of the insulating layers 2 is formed from the epoxy resin composition.

Description

  The present invention relates to a halogen-free flame-retardant insulating epoxy resin composition. More specifically, the present invention relates to a multilayer circuit board field such as an MCM-L / D (Multi-Chip Module-Laminate / Deposit) board or a single chip package board, and a wiring layer is formed on a board formed mainly of an organic substance. The present invention relates to a halogen-free flame-retardant insulating epoxy resin composition for forming and a multilayer circuit board including an insulating layer formed using the same.

  Conventionally, a printed circuit board is generally used in order to incorporate an electronic component into an electronic device in a compact manner. Such a printed circuit board is manufactured by etching a steel foil bonded to the surface of a laminated board (core substrate) according to a predetermined electronic circuit pattern, and is used by attaching various electric / electronic components. Although it is difficult to mount electronic components to a density, it is advantageous in terms of cost. On the other hand, for hybrid ICs, build-up multilayer wiring structures have been used for a long time. In this method, thick film pastes of conductors and insulators are alternately printed and stacked on a ceramic substrate, and then fired to produce a multilayer circuit board.

  In recent years, along with demands for downsizing, high performance, and low prices for electronic devices, electronic circuit miniaturization, multilayering, and high-density mounting of electronic components have rapidly progressed. However, studies on build-up multilayer wiring structures have become active. Since the insulating film for built-up interconnects the lower layer and upper layer electronic circuits, the built-up insulating film is formed on the entire surface of the lower wiring layer except for a portion to be interconnected (a through-hole portion generally referred to as “via hole”). Is formed.

  In order to form this build-up insulating film, an epoxy resin is mainly used because of its excellent electrical characteristics, cost, and workability.

  In general, epoxy resins have the disadvantage of being relatively flammable. This is not a desirable characteristic for materials used in electronic devices that are required to be difficult to burn. Therefore, in order to make an epoxy resin flame-retardant, it is most widely performed to use a halogenated epoxy (particularly, an epoxy resin containing bromine) and antimony oxide as a flame retardant.

  However, halogenated organic substances such as halogenated epoxies produce highly toxic harmful substances when burned, and antimony oxide is a carcinogenic substance. There is. Therefore, the movement to stop using products using such a flame-retardant epoxy resin composition has become stronger mainly in Western Europe. For this reason, there is a growing demand for halogen-free and antimony-free insulating resins that use neither halogen-based flame retardants nor antimony-based flame retardants, and there is a strong demand for the development of such materials.

  It is known to use metal hydrates, particularly aluminum hydroxide and magnesium hydroxide, instead of the halogen-based flame retardant in the epoxy resin composition. However, in order to achieve practical flame retardancy, it is necessary to add a large amount of metal hydrate, which makes the epoxy resin composition inferior in curability, insulation or mechanical properties, There will also be a problem in producing the build-up layer.

  The use of phosphorus or organic phosphorus compounds as phosphorus-based flame retardants is also widely known in the flame retardant field. Phosphorus flame retardants are broadly divided into additive and reactive types. A typical example of the additive-type phosphorus flame retardant is phosphorus (red phosphorus) or a phosphate ester. However, when phosphorus is added, there is a problem that the insulating properties of the epoxy resin composition deteriorate as in the case of metal hydrates. The phenomenon called “bleed-out” that appears on the surface of the film becomes a problem, and it is disadvantageous in that it is weak to the plating process.

  Therefore, when an insulating layer is formed on a circuit board, the present invention can exhibit flame retardancy and sufficient insulating properties required for that purpose, and does not cause bleed out and is strong in a plating process. An object is to provide a new halogen-free epoxy resin composition. It is also an object of the present invention to provide a circuit board having flame retardancy, including an insulating layer formed from the epoxy resin composition.

  The halogen-free flame-retardant insulating epoxy resin composition according to the present invention comprises (1) an epoxy resin, (2) a curing agent for the epoxy resin, (3) a resorcinol-type phosphate ester, (4) aluminum hydroxide, (5) An epoxy curing accelerator is included.

  A circuit board according to the present invention is a circuit board having a multilayer structure including a core substrate and at least a pair of insulating layers and wiring layers alternately formed thereon, wherein at least one of the insulating layers is a halogen substrate of the present invention. It is formed from a free flame retardant insulating epoxy resin composition.

  According to the present invention, it is possible to provide a halogen-free insulating layer that has sufficient flame retardancy and insulation, does not cause bleed out, and is resistant to plating processes, and has such excellent characteristics. A circuit board including a flame-retardant insulating layer can be used.

It is a figure explaining the circuit board by this invention.

  The flame-retardant insulating epoxy resin composition of the present invention is an epoxy composition comprising an epoxy resin, a curing agent, and a curing accelerator, and becomes a source of harmful compounds when discarded as one of the flame-retardant components. Addition-type organophosphorus compound resorcinol phosphate that does not contain halogen, does not cause bleed-out, and is composed of aluminum hydroxide as another flame retardant component. is there.

  The epoxy resin in the epoxy resin composition of the present invention has two or more epoxy groups in the molecule and can be formed into a film by curing, and the cured product has sufficient characteristics as an insulating layer in a circuit board. For example, it is selected to provide peel (peel) strength, tensile elongation, resistance in the plating process, and the like. A preferred epoxy resin in the composition of the present invention is an alicyclic or aromatic epoxy resin. Moreover, the epoxy resin in the composition of the present invention has a functionality of 2 or more, and more preferably has a functionality of 2 to 4. Examples of suitable aromatic bifunctional epoxy resins include bifunctional epoxy resins such as bisphenol A type epoxy, bisphenol S type epoxy, bisphenol F type epoxy, and the like. Examples of glycidyl isocyanurate epoxy, VG3101L manufactured by Mitsui Chemicals, and aromatic tetrafunctional epoxy resin include Araldite MTO163 manufactured by Ciba Geigy. Examples of suitable alicyclic epoxy resins include bifunctional epoxy resins such as Araldite CY179 (Ciba Geigy) and EHPE-3150 (Daicel Chemical), trifunctional epoxy such as Eporide GT300 (Daicel Chemical), A tetrafunctional epoxy such as GT400 (Daicel Chemical Company) can be used. In particular, by including a low molecular weight epoxy resin generated from these trifunctional or tetrafunctional epoxy resins, the intermolecular network structure in the insulating film formed from the epoxy resin composition of the present invention can be strengthened, and the present invention. The flame retardant insulating layer which can suppress the dissolution of the phosphate ester flame retardant used in the epoxy resin composition of the present invention, thereby having better resistance to the plating solution and excellent in other mechanical properties It becomes possible to provide.

  As described above, the epoxy resin can be used by mixing two or more kinds so as to provide sufficient properties as an insulating layer, and a mixture of an alicyclic epoxy resin and an aromatic epoxy resin is used. Is preferred. In this case, the epoxy resin mixture contains at least one epoxy resin having a functionality of 3 or more, thereby forming an insulating layer having high peel strength, high tensile elongation, and high glass transition temperature (Tg). This is particularly advantageous. Preferably, the epoxy resin composition of the present invention includes at least one trifunctional or higher functional epoxy resin in addition to at least a bifunctional alicyclic epoxy and an aromatic epoxy resin.

  The curing agent in the epoxy resin composition of the present invention may be any as long as it is useful for curing the epoxy compound to be used, but should be selected so as not to impair the properties of the formed insulating layer. is there. In the present invention, an aralkyl type phenol resin (for example, XLC-LL manufactured by Mitsui Chemicals) or a phenol novolak resin (for example, PSM-4300 manufactured by Gunei Chemical Co., Ltd.) can be used. Further, a mixture of plural kinds of curing agents may be used depending on the characteristics required for the insulating layer. The combination of the above-mentioned aralkyl type phenol resin and phenol novolac resin is a preferable curing agent in the epoxy resin of the present invention.

  The amount of the curing agent used may be appropriately determined in consideration of the characteristics of the insulating layer to be formed, etc., but usually the active hydrogen equivalent of the curing agent is 0.8 to 1 with respect to 1 equivalent of the epoxy group in the composition. It is preferable to blend in an amount such that .1.

  The curing accelerator in the composition of the present invention may be an appropriate one depending on the epoxy compound used and the type of the curing agent. Examples of suitable curing accelerators include imidazole compounds, triphenylphosphine, tertiary amines and the like.

  What is necessary is just to determine suitably the usage-amount of a hardening accelerator according to the epoxy resin to be used and the kind of the hardening agent, but normally 1-10 weight part is used with respect to 100 weight part of epoxy resins in a composition. It is done.

  In the composition of the present invention, a resorcinol-type phosphate ester is particularly used as a component imparting flame retardancy. While ordinary phosphoric acid ester flame retardants tend to dissolve in the plating solution and make the insulating layer brittle, and easily bleed out at high temperatures, resorcinol-type phosphoric acid esters suffer from such drawbacks. And can be used as an additive type flame retardant. A typical example of a resorcinol-type phosphate ester that can be used in the present invention is FP-500 manufactured by Asahi Denka Co., Ltd. In general, the blending amount of the resorcinol-type phosphate ester is preferably 12 to 18 parts by weight with respect to 100 parts by weight of the total solid content of the epoxy resin composition of the present invention. If this phosphate ester is less than 12 parts by weight, sufficient flame retardancy cannot be obtained, and if it exceeds 18 parts by weight, sufficient plating peel strength cannot be obtained.

  In the composition of the present invention, aluminum hydroxide is used as another flame retardant component. Aluminum hydroxide having an appropriate particle size is selected in consideration of the thickness of the insulating layer to be formed. In the present invention, since aluminum hydroxide is used in combination with resorcinol-type phosphate ester, the amount of flame retardant aluminum hydroxide used can be kept low, so that the curability of the insulating epoxy resin composition is not impaired. It is possible to suppress adverse effects on the insulating properties and mechanical properties of the formed insulating layer. In general, the aluminum hydroxide is preferably used in an amount of 15 to 20 parts by weight based on 100 parts by weight of the total solid content of the epoxy resin composition of the present invention. If the aluminum hydroxide is less than 15 parts by weight, sufficient flame retardancy cannot be obtained, and if it exceeds 20 parts by weight, the mechanical properties of the resin deteriorate.

  Thus, by using a combination of resorcinol-type phosphate ester and aluminum hydroxide without using a halogen-containing material, the composition of the present invention has sufficient flame retardancy required in a circuit board and sufficient It is possible to provide an insulating layer that can exhibit excellent insulating properties, has no bleed-out, and is strong in the plating process.

  You may add a various additive to the composition of this invention as needed. Examples of such additives include fillers and leveling agents. When silica powder is added as an inorganic filler, the thixotropic property of the composition is remarkably improved, which is very advantageous. The addition amount of the silica powder should be determined so as not to impair other characteristics of the insulating layer to be formed. Specifically, the amount of silica powder is 2.5 with respect to 100 parts by weight of the total solid content of the epoxy resin composition of the present invention. It is good to be about -5.0 weight part.

  The composition of the present invention is generally applied in the form of a varnish onto a processing substrate (a core substrate or an insulating layer and a wiring layer formed thereon). In order to obtain a varnish-like composition, the composition of the present invention may contain a suitable solvent in addition to the above components. Examples of the solvent include acetates such as propylene glycol monoether acetate, and organic solvents such as cyclohexane, dioxane, methyl ethyl ketone (MEK), xylene, and N-methylpyrrolidone.

  In order to produce a circuit board using the composition of the present invention, first, the composition of the present invention is applied to an electronic circuit board with a desired thickness by a suitable method such as screen printing, curtain coating, roll coating, or bin coating. Apply (for example, 40 μm) to form a film. Subsequently, the film is heated by heating at an appropriate temperature (for example, 120 ° C.). Next, it heats at 170-200 degreeC, for example, the thermosetting epoxy resin component in a film is heat-hardened, and an insulating layer is formed. Thereafter, a via hole is formed in a portion (via hole portion) to be connected to an electronic circuit formed as an upper layer of the insulating layer by a laser processing machine using, for example, a carbon dioxide gas laser, an excimer laser, a YAG laser or the like. Next, the surface of the electronic circuit board is immersed in an alkaline solution such as an aqueous permanganate solution to roughen the surface, and then electroless plating and subsequent electrolytic plating are performed to form a conductor layer, which is then patterned, and the upper layer Form wiring. Usually, the insulating layer and the wiring are simultaneously formed on both surfaces of the substrate by this series of steps. Thereafter, the steps from the application of the resin composition to the formation of the upper wiring can be repeated a predetermined number of times to produce a multilayer circuit board. The production of multilayer circuit boards by such build-up techniques is well known to those skilled in the art and will not be described in further detail here.

  As shown in FIG. 1, the circuit board 10 of the present invention having an insulating layer formed by using the epoxy resin composition of the present invention has a core substrate 1 having a predetermined pattern of wiring 7 formed on the surface thereof. In addition, the insulating layer 2 and the wiring 3 formed through the necessary number of steps as described above are included. As shown in this figure, when there are the insulating layer 2 and the wiring 3 formed through a plurality of processes, a part of the insulating layer 2 is formed from a material other than the epoxy resin composition of the present invention. There is no problem. The circuit board (core board) 1 shown in FIG. 1 is usually formed through the wirings on both surfaces so as to connect each other, and through holes 5 filled with an insulating resin material 4 are used. The wiring 8 formed inside the substrate is included. Further, the circuit board 10 has a protective layer (not shown) on the uppermost wiring 3, terminals (not shown) used for mounting various electric / electronic components and the like on the circuit board 10, and the like. Can also be included.

  The invention will now be further described by way of examples. Of course, these examples are illustrative of the present invention and are not intended to be limiting.

[Example 1]
75 parts by weight of a bisphenol A type epoxy resin (Ciba Geigy's XAC5020), 25 parts by weight of a cyclohexane skeleton cycloaliphatic epoxy resin (Araldite CY179 of Ciba Geigy), 10 parts by weight of triglycidyl inocyanurate epoxy resin (Nissan Chemical) Resorcinol type phosphoric acid ester (FP-500 manufactured by Asahi Denka Co., Ltd.) 35 parts by weight, aralkyl type phenolic resin (XLC-LL from Mitsui Chemicals) 60 parts by weight, phenol novolac resin (PSM-4300 from Gunei Chemical Co., Ltd.) 30 parts by weight Part, 2-methyl-4-ethylimidazole (Shikoku Chemicals Co., Ltd.) 1.0 part by weight, aluminum hydroxide (Sumitomo Chemical Co., Ltd., particle size 1 μm or less), silica powder (Asahi Denka Kogyo Co., Ltd., particle size 1 μm or less) ) 7.5 parts by weight of propylene glycol monoether acetate 24 layers A coating composition was prepared by dissolving in a mixed solvent of parts by weight, 16 parts by weight of MEK and 20 parts by weight of N-methylpyrrolidone.

  The prepared composition was applied to a copper foil substrate to a thickness of 70 μm, then heated and dried at 120 ° C. for 20 minutes, further heated at 170 ° C. for 60 minutes, and then allowed to cool to room temperature to form a resin film. . Next, a pretreatment agent (Shipley Co. conditioner, 60 ° C., 10 minutes), an oxidizing agent (Shipley Co. promoter, 70 ° C., 10 minutes, pH = 11), a neutralizing agent (Shipley Co., Ltd. New Trizer, 60 ° C.) 10 minutes), electroless copper plating and electrolytic copper plating were sequentially performed to form a conductor layer having a thickness of 25 μm on the resin film. The peel strength of this conductor layer was 950 gf / cm (9.3 N / cm).

  Further, the above coating liquid composition was applied onto an aluminum plate, peeled off after curing to produce a film having a thickness of 70 μm, and the elongation at break was measured as a result of measuring the breaking elongation of this film with a tensile tester. It was 5% or more.

  Further, the above coating composition was applied to both sides of a halogen-free core substrate (125 mm × 13 mm copper-etched Toshiba core substrate having a thickness of 0.4 mm) (70 μm) and dried by heating at 100 ° C. for 20 minutes. The mixture was heated at 170 ° C. for 60 minutes and then allowed to cool to room temperature. When this board was subjected to a UL94V flame retardant test, it was flame retardant equivalent to V1.

The coating composition was applied onto a BT (bismaleimide triazine) substrate having wiring with an IPC A pattern, and an insulating layer was formed on the wiring in the same manner as described above. This substrate was subjected to a USPCBT (Unsaturated Pressure Cooker Bias Test) test (electrolytic corrosion test) under the conditions of 120 ° C., 85% relative humidity, 1.7 atm (172 kPa), 24 V, and 100 hours. The inter-wiring resistance during the test maintained the order of 1 × 10 ⁷ Ω. After the test, the resistance between the wirings measured after drying was in the order of 1 × 10 ¹² Ω. From these, it was shown that the insulating property of the formed insulating layer was good.

  The results obtained from the tests in this example are summarized in Table 1.

[Example 2]
75 parts by weight of a bisphenol A type epoxy resin (XAC5020 from Ciba-Geigy), 25 parts by weight of cyclohexane skeleton alicyclic epoxy resin (Araldite CY179 from Ciba-Geigy), 20 parts by weight of trifunctional epoxy resin (VG3101L from Mitsui Chemicals), resorcinol Type phosphoric acid ester (FP-500 manufactured by Asahi Denka Co., Ltd.) 35 parts by weight, aralkyl type phenol resin (XLC-LL from Mitsui Chemicals) 60 parts by weight, phenol novolak resin (PSM-4300 from Gunei Chemical Co., Ltd.) 30 parts by weight , 1.0 part by weight of 2-methyl-4-ethylimidazole (Shikoku Chemicals), 40 parts by weight of aluminum hydroxide (Sumitomo Chemical Co., Ltd., particle size 1 μm or less), silica powder (Asahi Denka Kogyo Co., Ltd., particle size 1 μm or less) 7.5 parts by weight, 24 parts by weight of propylene glycol monoether acetate and M Dissolved in 16 parts by weight of EK mixed solvent to prepare a coating composition.

  The prepared composition was applied to a copper foil substrate to a thickness of 70 μm, then heated and dried at 120 ° C. for 20 minutes, further heated at 170 ° C. for 60 minutes, and then allowed to cool to room temperature to form a resin film. . Next, after processing in the same manner as in Example 1, electroless copper plating and electrolytic copper plating were sequentially performed to form a 25 μm thick copper film on the resin film. The peel strength of this copper film was 1100 gf / cm (10.8 N / cm).

The tensile elongation of the insulating layer produced in the same manner as in Example 1 using the above coating composition was 7.2%.
Furthermore, when a combustion test was conducted in the same manner as in Example 1, it was flame retardancy equivalent to V1.
Also, as a result of the USPCBT test as in Example 1, the resistance between the wirings during the test maintained the order of 1 × 10 ⁷ Ω, and the resistance between the wirings measured after drying was 1 × 10 ¹² Ω. It was an order.
The results obtained from the tests in this example are also summarized in Table 1.

Example 3
75 parts by weight of bisphenol A type epoxy resin (Ciba Geigy's XAC5020), 25 parts by weight of cyclohexane skeleton cycloaliphatic epoxy resin (Ciba Geigy's Araldite CY179), tetrafunctional epoxy resin (Ciba Geigy's Araldite MTO163), 30 parts by weight, resorcinol Type phosphoric acid ester (FP-500 manufactured by Asahi Denka Co., Ltd.) 35 parts by weight, aralkyl type phenol resin (XLC-LL from Mitsui Chemicals) 60 parts by weight, phenol novolak resin (PSM-4300 from Gunei Chemical Co., Ltd.) 30 parts by weight , 1.0 part by weight of 2-methyl-4-ethylimidazole (Shikoku Chemicals), 40 parts by weight of aluminum hydroxide (Sumitomo Chemical Co., Ltd., particle size 1 μm or less), silica powder (Asahi Denka Kogyo Co., Ltd., particle size 1 μm or less) 7.5 parts by weight of propylene glycol monoether acetate A coating composition was prepared by dissolving in a mixed solvent of 60 parts by weight and 7 parts by weight of ethylene glycol butyl ether acetate (EGBAc).

  The prepared composition was applied to a copper foil substrate to a thickness of 70 μm, then heated and dried at 120 ° C. for 20 minutes, further heated at 170 ° C. for 60 minutes, and then allowed to cool to room temperature to form a resin film. . Next, after processing in the same manner as in Example 1, electroless copper plating and electrolytic copper plating were sequentially performed to form a 25 μm thick copper film on the resin film. The peel strength of this copper film was 950 gf / cm (9.3 N / cm).

The tensile elongation of the insulating layer produced in the same manner as in Example 1 using the above coating composition was 7.8%.
Furthermore, when a combustion test was conducted in the same manner as in Example 1, it was flame retardancy equivalent to V1.
As a result of the USPCBT test as in Example 1, the inter-wiring resistance during the test maintained the order of 1 × 10 ⁷ Ω, and the inter-wiring resistance measured after drying was 1 × 10 ¹² Ω. It was an order.
The results obtained from the tests in this example are also summarized in Table 1.

[Comparative Example 1]
Bisphenol A type epoxy resin (Ciba Geigy XAC5020) 75 parts by weight, cyclohexane skeleton cycloaliphatic epoxy resin (Ciba Geigy Araldite CY179) 25 parts by weight, resorcinol type phosphate ester (FP-500 manufactured by Asahi Denka Co., Ltd.) 60 parts by weight Parts, 54 parts by weight of aralkyl type phenolic resin (XLC-LL, Mitsui Chemicals), 27 parts by weight of phenol novolac resin (PSM-4300, Gunei Chemicals), 2-methyl-4-ethylimidazole (Shikoku Chemicals) 1 0.0 parts by weight and 7.5 parts by weight of silica powder (Asahi Denka Kogyo Co., Ltd., particle size of 1 μm or less) are dissolved in a mixed solvent of 60 parts by weight of propylene glycol monoether acetate and 7 parts by weight of EGBAc to prepare a coating composition. did.

  The prepared composition was applied to a copper foil substrate to a thickness of 70 μm, then heated and dried at 120 ° C. for 20 minutes, further heated at 170 ° C. for 60 minutes, and then allowed to cool to room temperature to form a resin film. . Next, after processing in the same manner as in Example 1, electroless copper plating and electrolytic copper plating were sequentially performed to form a 25 μm thick copper film on the resin film. The peel strength of this copper film was 100 gf / cm (0.98 N / cm).

The tensile elongation of the insulating layer produced in the same manner as in Example 1 using the above coating composition was 3.5%.
Further, when a combustion test was conducted in the same manner as in Example 1, sufficient flame retardancy was not shown ("not equivalent" in Table 1 indicates this).
The test results in this example are also summarized in Table 1.

  Thus, in the composition of this example, resorcinol-type phosphate ester is used twice as an appropriate amount as a flame retardant, so that the plating adhesion and mechanical properties are not sufficient. Moreover, since aluminum hydroxide is not used, the flame retardancy is not sufficient.

[Comparative Example 2]
75 parts by weight of bisphenol A type epoxy resin (Ciba Geigy's XAC5020), 25 parts by weight of cyclohexane skeleton cycloaliphatic epoxy resin (Cirba Geigy's Araldite CY179), 54 parts by weight of aralkyl type phenolic resin (XLC-LL, Mitsui Chemicals) , Phenol novolac resin (PSM-4300 of Gunei Chemical Co., Ltd.) 27 parts by weight, 1.0 parts by weight of 2-methyl-4-ethylimidazole (Shikoku Kasei Co., Ltd.), silica powder (Asahi Denka Kogyo Co., Ltd., particle size of 1 μm or less) 7.5 parts by weight and 50 parts by weight of aluminum hydroxide (Sumitomo Chemical Co., Ltd., particle size of 1 μm or less) were dissolved in a mixed solvent of 60 parts by weight of propylene glycol monoether acetate and 7 parts by weight of EGBAc to prepare a coating composition. .

  The prepared composition was applied to a copper foil substrate to a thickness of 70 μm, then heated and dried at 120 ° C. for 20 minutes, further heated at 170 ° C. for 60 minutes, and then allowed to cool to room temperature to form a resin film. . Next, after processing in the same manner as in Example 1, electroless copper plating and electrolytic copper plating were sequentially performed to form a 25 μm thick copper film on the resin film. The peel strength of this copper film was 700 gf / cm (6.9 N / cm).

The tensile elongation of the insulating layer produced in the same manner as in Example 1 using the above coating liquid composition was 3.3%.
Further, when a combustion test was conducted in the same manner as in Example 1, sufficient flame retardancy was not shown.
The test results in this example are also summarized in Table 1.

  Thus, in the composition of this example, only aluminum hydroxide is used as a flame retardant component, and resorcinol-type phosphate ester is not used. Therefore, the insulating layer formed from this composition is a mechanical layer. It can be seen that the properties are low and the flame retardancy is not sufficient.

1 Core substrate 2 Insulating layer 3, 7 Wiring 10 Circuit board

Claims (7)

  (1) an epoxy resin, (2) a hardener for the epoxy resin, (3) a resorcinol phosphate, (4) aluminum hydroxide, and (5) an epoxy cure accelerator. Flammable insulating epoxy resin composition.   The epoxy resin composition according to claim 1, wherein the epoxy resin contains at least one trifunctional or higher functional epoxy resin in addition to at least a bifunctional alicyclic epoxy and an aromatic epoxy resin.   The epoxy resin composition of Claim 1 or 2 which contains the said resorcinol type | mold phosphate ester and aluminum hydroxide 12-18 weight part and 15-20 weight part with respect to 100 weight part of the total solid of the said composition, respectively.   The epoxy resin composition according to any one of claims 1 to 3, wherein an aralkyl type phenol resin and a phenol novolac resin are used as the curing agent.   The epoxy resin composition according to any one of claims 1 to 4, wherein the curing accelerator is an imidazole compound, triphenylphosphine, or a tertiary amine.   The epoxy resin composition according to any one of claims 1 to 5, further comprising 2.5 to 5.0 parts by weight of silica powder with respect to 100 parts by weight of the total solid content of the composition.   A circuit board having a multilayer structure including a core substrate and at least one pair of insulating layers and wiring layers alternately formed thereon, wherein at least one of the insulating layers is any one of claims 1 to 6. It is formed from the epoxy resin composition of description.

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