JP2005255793A - Non-solvent single pack type thermosetting epoxy resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermosetting epoxy resin composition having a high glass transition temperature of its cured material, excellent in working property and preservation stability, and also a non-solvent single pack type. <P>SOLUTION: This non-solvent single pack type epoxy resin composition is characterized by containing an epoxy resin being a liquid state in a room temperature and having ≥3 functionalities, fine powdery dicyandiamide which is a latent curing agent and an inorganic filler as indispensable components. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention is a solventless one-component type that is used for filling and filling through holes in printed wiring boards (single-sided printed wiring boards, double-sided printed wiring boards, multilayer printed wiring boards, etc.) and excellent in workability and storage stability. The present invention relates to a thermosetting epoxy resin composition.

  With the widespread use of personal computers, mobile phones, etc., package substrate materials for semiconductor mounting are becoming smaller, higher density, and higher performance. Epoxy resin compositions are often used as package substrate materials, and plastic substrate materials having high heat resistance and low coefficient of thermal expansion have been developed with higher performance. In order to ensure high reliability in the packaging temperature region and thermal cycle temperature region of package substrate materials that are becoming more sophisticated, not only the individual material characteristics included in the printed circuit board for packaging but also the physical properties between various materials. Consistency is a very important factor.

  Further, in a printed circuit board for a package, it is indispensable to form a circuit at a narrow pitch as the density increases, and high reliability is required in a thermal cycle test or the like. In particular, in recent years, there has been an increasing need for a structure for mounting a component on a through hole of a substrate and a structure for forming a laser via on the through hole. In order to respond to these, it is necessary to fill the through hole with a resin. . In multi-layer boards, etc., there is a method such as batch filling with a build-up material on the upper layer of the substrate in order to fill and fill the through holes with resin, but it is difficult to fill up the holes as the through hole is made smaller or deeper. Therefore, it is not a versatile method. Therefore, a highly reliable resin composition for filling and filling through-holes in a high-density package printed circuit board is required.

  In general, when filling a through hole with a resin composition, a screen printing method is the mainstream, and there are other methods such as a roll coating method.

  As the resin composition for filling holes, there are generally one-component type and two-component type, thermosetting type and UV curing type. Although the one-pack type is easy to work, storage stability is a major issue. On the other hand, the two-component type has a difficulty in storage and handling because the two components must be weighed and mixed sufficiently uniformly immediately before filling the hole. Comparing the thermosetting type and the UV curing type, in the UV curing type, radical polymerization of the photosensitive compound proceeds faster in the surface layer portion, and a difference occurs in the degree of curing between the surface layer portion and the inside. Therefore, there is a drawback that curing shrinkage becomes large. On the other hand, in the thermosetting type, amines and acid anhydrides are mainly used as the curing agent. However, when these curing agents are used, fast curing is difficult, and it is difficult to ensure storage stability and control the reaction. Moreover, since it hardens | cures completely, the hardness of hardened | cured material is high and the grinding | polishing for flattening the surface of hardened | cured material becomes remarkably difficult.

  Moreover, there are two types of resin compositions for filling holes, a solvent-containing type and a solventless type. In the solvent-containing type, the solvent volatilizes during curing, so that the volume shrinks, and the residual solvent and voids and cracks due to the residual solvent are generated. Furthermore, taking into consideration the reduction of environmental burdens and the like, in recent years, a solvent-free resin composition for hole filling has become essential.

In order to be a solventless thermosetting epoxy resin composition excellent in workability, it is necessary to be liquid at room temperature. Therefore, most of the conventional hole filling resin compositions use a bifunctional epoxy resin as a main agent. However, when a bifunctional epoxy resin is used, the cured resin cannot have a cross-linked structure, so that a glass transition temperature (Tg) equivalent to that of a high heat resistant substrate material for a package cannot be obtained. Moreover, when the epoxy resin more than trifunctional was used, the viscosity of the resin composition for hole filling became high and the problem that workability | operativity worsened had arisen.
JP 6-68091 JP-A-11-269355

  Along with the progress of higher heat resistance and lower thermal expansion coefficient of package materials, it has high heat resistance and low thermal expansion coefficient equivalent to those of substrate materials, and also has low viscosity, excellent workability and storage stability, no solvent and 1 There is a strong demand for a liquid thermosetting insulating resin composition for filling holes.

  The present invention eliminates the problems of the prior art by using a liquid trifunctional or higher functional epoxy resin, granular dicyandiamide, and an inorganic filler at room temperature, and is a solvent-free one-component thermosetting epoxy resin composition. It provides things.

  The solventless one-component thermosetting epoxy resin composition of the present invention has a small increase in viscosity with time, and is excellent in workability and storage stability. Furthermore, when the Tg of the resin cured product is 150 ° C. or higher, it exhibits heat resistance characteristics suitable for a package substrate material having a high Tg for semiconductor mounting. Hereinafter, the present invention will be described in detail.

  The trifunctional or higher functional epoxy resin used in the present invention is not particularly limited as long as it is liquid at room temperature. For example, examples of the trifunctional epoxy resin include triglycidyl isocyanate and triglycidyl paraaminophenol. Examples of the tetrafunctional epoxy resin include tetraglycidyl metaxylene diamine and tetraglycidyl diaminophenylmethane. Furthermore, other examples of polyfunctional epoxy resins having three or more functionalities include phenol novolac polyglycidyl ether and the like. These three or more functional epoxy resins may be used in combination.

  As described above, in order to be a solventless one-component thermosetting epoxy resin composition excellent in workability, it is necessary to be liquid at room temperature. Further, when a curing agent, a filler, an additive, or the like is added, the thermosetting epoxy resin composition inevitably causes a significant increase in viscosity. Therefore, in order to obtain a resin composition with excellent workability, the present invention It is desirable that the epoxy resin having a trifunctional or higher functionality in has a low viscosity.

  In the present invention, “solvent-free” means that the solvent content is 0.1 wt% or less.

  As the curing agent in the present invention, granular dicyandiamide is used. Dicyandiamide is a latent curing agent that is solid at room temperature, disperses without dissolving in the epoxy resin, dissolves when the temperature near the melting point is reached, and starts a reaction rapidly. Use of a liquid curing agent at room temperature, such as amine, is preferred because it has the advantage of lowering the viscosity and making it easier to adjust to an appropriate viscosity, but it may react with the epoxy resin at room temperature to reduce storage stability. Absent. On the other hand, dicyandiamide, a latent curing agent, only contains a primary reaction with the surface of the curing agent when blended in an epoxy resin, and the curing reaction does not proceed until dissolved by heating. A solventless one-component thermosetting epoxy resin composition excellent in stability is obtained.

  The dicyandiamide used in the present invention is pulverized into granules. Furthermore, it is desirable that the particulate dicyandiamide is uniformly dispersed in the thermosetting epoxy resin composition. If the granular dicyandiamide is not uniformly dispersed and aggregates are present, the curing reaction is biased and a uniform cured resin product cannot be obtained. In addition, these aggregates are not preferable because they do not completely dissolve in the resin composition and the curing reaction proceeds. The average particle size of the granular dicyandiamide in the present invention is suitably in the range of 0.5 to 20 μm from the viewpoint of dispersibility and uniform solubility during the curing reaction. When the average particle diameter of dicyandiamide is 20 μm or more, the curing agent remains in the cured product without being completely dissolved during the curing reaction, and the cured product characteristics such as Tg may be deteriorated. Furthermore, as the diameter of the through hole is reduced, the presence of large-diameter particles may result in insufficient hole filling properties. On the other hand, when the average particle size of dicyandiamide is 0.5 μm or less, the influence of the interaction acting between the dicyandiamide particle surfaces becomes large, and secondary aggregates may be generated.

  The compounding quantity of the granular dicyandiamide in this invention is the range of 0.5-20 parts with respect to 100 parts of all the epoxy resins, Preferably it is the range of 3-15 parts. When the blending amount of the granular dicyandiamide is less than 0.5 part, the curing reaction time becomes long, Tg is lowered, and the adhesion of the through hole to the plated copper or the like is lowered. On the other hand, when the amount of dicyandiamide is more than 20 parts, the curing reaction time becomes too short, and the dicyandiamide may not be sufficiently dissolved during the curing reaction. Furthermore, the water absorption rate is increased, and when hot water extraction or the like is performed, ammonium ions are extracted so much that the insulation reliability of the package material is lowered.

  The inorganic filler in the present invention has an effect of suppressing the coefficient of thermal expansion of the cured resin. The kind of the inorganic filler in the present invention is not particularly limited. For example, calcium carbonate, alumina, aluminum hydroxide, magnesium hydroxide, titanium oxide, mica, aluminum carbonate, magnesium silicate, aluminum silicate, silica, glass short Various whiskers such as fibers, aluminum borate and silicon carbide can be used. Furthermore, you may use these several types together.

  The average particle diameter of the inorganic filler in the present invention is preferably in the range of 0.1 to 20 μm. When the average particle diameter of the inorganic filler is 20 μm or more, sedimentation or the like occurs in the resin composition, and workability decreases. In addition, it is difficult to cope with package materials that have been increasingly thinned, densified and pitched in recent years. On the other hand, when the average particle size of the inorganic filler is 0.1 μm or less, the influence due to the interaction between the particle surfaces of the inorganic filler is increased, secondary aggregates are easily generated, and complete uniform dispersion is difficult. It is not appropriate because there are.

  Although the compounding quantity of the inorganic filler in this invention is not specifically limited, In order to suppress the thermal expansion coefficient of resin cured | curing material, it is desirable to mix | blend 20 volume% or more with respect to the total solid. Moreover, the solventless one-component thermosetting epoxy resin composition of the present invention has a viscosity excellent in workability, and the coefficient of thermal expansion in a region lower than the Tg of the cured product is 40 ppm / ° C. or less. Therefore, the blending amount of the inorganic filler is desirably in the range of 20 to 65% by volume with respect to the total solid content.

  The solvent-free one-component thermosetting epoxy resin composition in the present invention can be used in combination with a viscosity modifier as desired. As the viscosity modifier, a bifunctional liquid epoxy resin, a low viscosity reactive diluent, or the like can be used.

  Examples of the bifunctional epoxy resin for viscosity adjustment in the present invention include bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, phthalic acid diglycidyl ester, cyclic aliphatic adipic acid diepoxy, diglycidyl hydantoin and the like. Is mentioned. Addition of the bifunctional epoxy resin is effective for reducing the viscosity of the thermosetting epoxy resin composition for filling a hole, but if the blending amount is too large, the crosslink density of the cured product is lowered, and heat resistance and Tg are lowered. Therefore, the type and blending amount of the bifunctional epoxy resin to be added should be selected in consideration of the viscosity of the target solvent-free one-component thermosetting epoxy resin composition and the properties of the cured product. is important.

  The reactive diluent for adjusting the viscosity in the present invention may be monofunctional, bifunctional or higher, and is not particularly limited. However, in order to maintain a high Tg of the cured product, the bifunctional or higher functional diluent is not limited. A reactive diluent is more preferred. Examples of monofunctional reactive diluents include n-butyl glycidyl ether, C12 to C14 alkyl glycidyl ether, allyl glycidyl ether, 2-ethylhexyl glycidyl ether, styrene oxide, phenyl glycidyl ether, cresyl glycidyl ether, p-sec. -Butylphenyl glycidyl ether, t-butylphenyl glycidyl ether, glycidyl methacrylate, tertiary carboxylic acid glycidyl ester and the like. Examples of the bifunctional reactive diluent include ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, butanediol diglycidyl ether, and the like. Addition of a reactive diluent is effective for reducing the viscosity of the thermosetting epoxy resin composition. However, if the blending amount is too large, the crosslink density of the cured product is lowered, and heat resistance and Tg are lowered. Therefore, the type and blending amount of the reactive diluent to be added can be selected in consideration of the viscosity of the target solventless one-component thermosetting epoxy resin composition and the properties of the cured product. is important.

  Moreover, the solvent-free one-component thermosetting epoxy resin composition in the present invention can be used in combination with a curing accelerator as desired. The type and blending amount of the curing accelerator are not particularly limited. For example, imidazole compounds, organophosphorus compounds, tertiary amines, quaternary ammonium salts and the like are used, and two or more kinds may be used in combination. .

  Furthermore, the thermosetting epoxy resin composition for filling holes in the present invention includes a dispersant, an antifoaming agent, a colorant, a flame retardant, and the like, if desired, and these two or more additives may be used in combination.

  Examples of the present invention will be specifically described below, but the present invention is not limited thereto.

Example 1
A triglycidyl paraaminophenol type epoxy resin (Ep630 manufactured by JER) that is a trifunctional epoxy resin and dicyandiamide (Dicy7 manufactured by JER: average particle diameter of 2.7 μm) that is a curing agent were mixed. Furthermore, 2-phenyl-4-methylimidazole (2P4MZ manufactured by Shikoku Kasei) as a curing accelerator and calcined clay (average particle size 1.2 μm) as an inorganic filler are added to this mixture so that a uniform composition is obtained. To obtain a solvent-free one-component thermosetting epoxy resin composition. Table 1 shows the amount of each component.

Example 2
Phenol novolac type epoxy resin (Ep152 made by JER) which is a polyfunctional epoxy resin having three or more functionalities, Dicyandiamide (Jicy7 made by JER: average particle size 2.7 μm), and a bifunctional bisphenol as a viscosity modifier A type epoxy resin (Ep828 manufactured by JER) was mixed. Furthermore, 2-phenyl-4-methylimidazole (2P4MZ manufactured by Shikoku Chemicals), which is a curing accelerator, and calcined clay (average particle size 1.2 μm) were added to this mixture and kneaded to obtain a uniform composition. A solvent-free one-component thermosetting epoxy resin composition was obtained. Table 1 shows the amount of each component.

Example 3
A solventless one-component thermosetting epoxy resin composition was obtained in the same manner as in Example 2 except that dicyandiamide (Dicy 15 manufactured by JER: average particle size 4.6 μm) was used as the curing agent. Table 1 shows the amount of each component.

Example 4
Tetraglycidyldiaminophenylmethane type epoxy resin (Ep604 made by JER) which is a tetrafunctional epoxy resin, Dicyandiamide (Dicy7 made by JER: average particle size 2.7 μm), and a bifunctional bisphenol A type as a viscosity modifier An epoxy resin (Ep929 made by JER) was mixed. Furthermore, 2-phenyl-4-methylimidazole (2P4MZ manufactured by Shikoku Kasei), which is a curing accelerator, and calcined clay (average particle size 1.2 μm) were added to this mixture and kneaded to obtain a uniform composition. A solvent-free one-component thermosetting epoxy resin composition was obtained. Table 1 shows the amount of each component.

Example 5
Triglycidyl paraaminophenol type epoxy resin (Ep630 manufactured by JER) which is a trifunctional epoxy resin, phenol novolac type epoxy resin (Ep152 made by JER) which is a polyfunctional epoxy resin, dicyandiamide (Jicy7 made by JER: average particle) which is a curing agent And 2.7 μm in diameter) and a reactive diluent (YED205 manufactured by JER) as a viscosity modifier. Furthermore, 2-phenyl-4-methylimidazole (2P4MZ manufactured by Shikoku Kasei), which is a curing accelerator, and calcined clay (average particle size 1.2 μm) were added to this mixture and kneaded to obtain a uniform composition. A solvent-free one-component thermosetting epoxy resin composition was obtained. Table 1 shows the amount of each component.

Example 6
A solventless one-component thermosetting epoxy resin composition was obtained in the same manner as in Example 2. Table 1 shows the amount of each component.

Example 7
A solventless one-component thermosetting epoxy resin composition was obtained in the same manner as in Example 2. Table 1 shows the amount of each component.

Example 8
Phenol novolac type epoxy resin (Ep152 made by JER) which is a polyfunctional epoxy resin having three or more functionalities, Dicyandiamide (Jicy7 made by JER: average particle size 2.7 μm), and a bifunctional bisphenol as a viscosity modifier A type epoxy resin (Ep828 manufactured by JER) and a reactive diluent (YED205 manufactured by JER) were mixed. Furthermore, 2-phenyl-4-methylimidazole (2P4MZ manufactured by Shikoku Kasei), which is a curing accelerator, and calcined clay (average particle size 1.2 μm) were added to this mixture and kneaded to obtain a uniform composition. A solvent-free one-component thermosetting epoxy resin composition was obtained. Table 1 shows the amount of each component.

Comparative Example 1
Bisphenol A type epoxy resin (Ep828 manufactured by JER) which is a bifunctional epoxy resin and dicyandiamide (Dicy7 manufactured by JER: average particle size of 2.7 μm) as a curing agent were mixed. Furthermore, 2-phenyl-4-methylimidazole (2P4MZ manufactured by Shikoku Chemicals), which is a curing accelerator, is added to this mixture and kneaded to obtain a uniform composition to obtain a solventless thermosetting epoxy resin composition. It was. Table 1 shows the amount of each component.

Comparative Example 2
A bisphenol A type epoxy resin (Ep828 manufactured by JER), which is a bifunctional epoxy resin, and dicyandiamide (manufactured by Nippon Carbide: 20 μm <average particle size) were mixed. Furthermore, 2-phenyl-4-methylimidazole (2P4MZ manufactured by Shikoku Kasei) as a curing accelerator and calcined clay (average particle size 1.2 μm) as an inorganic filler are added to this mixture so that a uniform composition is obtained. To obtain a solvent-free thermosetting epoxy resin composition. Table 1 shows the amount of each component.

Comparative Example 3
A triglycidyl paraaminophenol type epoxy resin (Ep630 manufactured by JER), which is a trifunctional epoxy resin, and a phenol novolac resin (H400 manufactured by Meiwa Kasei), which is a curing agent, were mixed. Furthermore, 2-phenyl-4-methylimidazole (2P4MZ manufactured by Shikoku Kasei) as a curing accelerator and calcined clay (average particle size 1.2 μm) as an inorganic filler are added to this mixture so that a uniform composition is obtained. To obtain a solvent-free thermosetting epoxy resin composition. Table 1 shows the amount of each component.

The initial viscosity of the epoxy resins obtained in Examples and Comparative Examples and the viscosity after storage for one week at room temperature were measured at 25 ° C. and a rotation speed of 2 rpm using a rotary viscometer. When the rate of increase in viscosity after one week with respect to the initial viscosity is 10% or less, “no change”, when it is in the range of 10 to 50%, “thickening”, when it is 50% or more, “unusable”, viscosity measurement When it was not possible (torque over), it was set to “gelation”. Further, as the cured product characteristics, the thermal expansion coefficient (α1) in a temperature region lower than Tg and the thermal expansion coefficient (α2) in a temperature region higher than Tg were measured. Furthermore, the burying property was evaluated by observing the cross-section after burying hardening, and those with insufficient voids and filling were regarded as “poor”. The obtained epoxy resin composition was evaluated for storage stability, cured product characteristics, and hole filling properties. The results are shown in Table 1.

  From the above results, Examples 1 to 8 have good hole filling properties. In addition, since the viscosity change over time is not so large, workability at a practical level is maintained. In particular, Examples 1 to 6 and Example 8 are excellent in storage stability with no change in viscosity. Moreover, Examples 1-5 and Example 7 have high Tg of 150 degreeC or more of cured | curing material, and its heat resistance is favorable. On the other hand, Comparative Examples 1 and 2 using a bifunctional epoxy resin had poor hole filling properties. In Comparative Example 3 using a liquid phenol novolac resin as a curing agent, the curing reaction proceeded during storage and gelled.

Claims (7)

  A solventless one-component thermosetting epoxy resin composition comprising at least a liquid trifunctional or higher functional epoxy resin at room temperature, granular dicyandiamide, and an inorganic filler.   2. The solventless one-component thermosetting epoxy resin composition according to claim 1, wherein the dicyandiamide has an average particle size of 0.5 to 20 μm.   The solvent-free one-component thermosetting epoxy resin composition according to any one of claims 1 to 2, wherein the content of the inorganic filler is 20% by volume or more in the total solid content. .   The solvent-free one-component thermosetting epoxy resin composition according to any one of claims 1 to 3, wherein the inorganic filler has a particle size of 0.1 to 20 µm.   Furthermore, the bifunctional epoxy resin is included, The solventless one-component thermosetting epoxy resin composition of any one of Claims 1-4 characterized by the above-mentioned.   The solvent-free one-component thermosetting epoxy resin composition according to any one of claims 1 to 5, further comprising a monofunctional or bifunctional or higher reactive diluent.   The glass transition temperature (Tg) after hardening is 150 degreeC or more, The solventless one-component thermosetting epoxy resin composition of any one of Claims 1-6 characterized by the above-mentioned.