JP6198483B2 - Thermosetting resin composition and printed wiring board - Google Patents

Description

  The present invention is a thermosetting resin composition used in the production of printed wiring boards, and particularly a liquid thermosetting useful as a composition for filling holes such as through holes and via holes in printed wiring boards such as multilayer boards and double-sided boards. The present invention relates to a conductive resin composition and a printed wiring board in which the hole is filled.

  A printed wiring board is a circuit board with a conductor circuit pattern formed on it. Electronic parts are mounted on the land of the conductor circuit by soldering, and a solder resist film is used to protect the conductor on the circuit parts other than the land. It has a basic structure coated on.

  In recent years, the conductor circuit pattern of a printed wiring board has been made thinner and the mounting area has been reduced. That is, in order to cope with the downsizing and high functionality of the equipment including the printed wiring board, it is desired to make the printed wiring board lighter, thinner and shorter. For this reason, a multi-layer print is made by filling a through-hole provided in a printed wiring board with a resin filler, curing it to make a smooth surface, and then alternately laminating interlayer resin insulation layers and conductor circuit layers on the wiring board A multilayer printed wiring board has been developed in which a solder resist film is directly formed on a wiring board or a substrate filled with a resin filler in a through hole or the like. Under such circumstances, the development of an insulating composition for filling a permanent hole excellent in filling properties, polishing properties, workability (low viscosity), cured product characteristics, etc. for filling holes such as through holes and via holes has been made. It is desired.

  As an insulating composition for filling a permanent hole of a printed wiring board, generally, a cured product is excellent in mechanical, electrical and chemical properties and has good adhesiveness. Therefore, a thermosetting epoxy resin composition is used. Widely used. In this case, the permanent filling process of the printed wiring board includes a step of filling the hole portion of the printed wiring board with the epoxy resin composition, a step of pre-curing the filled composition into a polishable state by heating, and pre-curing. It is performed by a step of polishing and removing a portion protruding from the surface of the hole portion of the composition, and a step of further heating and precuring the precured composition.

  However, when the above hole filling composition is used, since it differs from the solder resist composition, cracks (internal cracks) may occur in the hole insulating layer under high temperature conditions such as curing treatment and solder leveling. There has been a problem that peeling (delamination) occurs between the outer insulating layer (solder resist layer and insulating resin layer) in the periphery of the hole insulating layer.

  In order to solve such a problem, for example, Patent Document 1 discloses a solvent-free resin filler filled in a recess formed on the surface of a wiring board or a through-hole provided in the board, and bisphenol as a resin component. There is disclosed a resin filler characterized by using an epoxy resin, an imidazole curing agent as a curing agent, and inorganic particles having an average particle diameter of 0.1 to 5.0 μm as an additive component.

  The cited document 2 contains an epoxy resin composition having an epoxy resin and a curing agent and a filler, and the epoxy resin is a through-hole filling paste containing an amine type epoxy resin and a polyphenol type epoxy resin. . In addition, an imidazole compound (2E4MZ-C) is used as a curing agent.

  Patent Document 3 discloses a filler containing calcium carbonate powder of crushed particles, spherical particles, cubic particles or spindle-shaped particles and a thermosetting resin (eg, epoxy resin). Moreover, the Example of patent document 3 is disclosing the composition containing the bisphenol F type epoxy resin as a bifunctional epoxy resin, and the aminophenol type epoxy resin as a trifunctional epoxy resin.

Furthermore, Patent Document 4 discloses a thermosetting resin composition that contains (A) an epoxy resin, (B) an epoxy resin curing agent, and (C) an inorganic filler, and is filled in a hole of a printed wiring board. The epoxy resin (A) includes a bifunctional epoxy resin (A-1) and a trifunctional or higher functional epoxy resin (A-2), and the inorganic filler (C) is a group IIa element of the periodic table. filling a thermosetting resin composition characterized by comprising a salt that is disclosed.

Patent No. 3242009 Japanese Patent No. 3405914 JP-A-2005-223312 JP2009-269994A

  However, sufficient heat resistance cannot be obtained with the combination of the bisphenol type epoxy resin of Cited Document 1 and an imidazole curing agent as the curing agent. Further, when an amine type epoxy resin and a polyphenol type epoxy resin are used as the epoxy resin of Cited Document 2 and an imidazole compound (2E4MZ-C) is used as a curing agent, it is still insufficient in terms of storage stability, generation of cracks, and the like. I can not say. Furthermore, when a bifunctional epoxy resin and a trifunctional or higher functional epoxy resin are used as the epoxy resins of Cited Document 3 and Cited Document 4 and a specific inorganic filler is used, sufficient heat resistance cannot be obtained and the viscosity is high. There is a tendency for voids to occur.

  Therefore, the present invention shows printability that can be satisfactorily filled with low viscosity when filling holes such as through-holes and via holes in printed wiring boards, has excellent storage stability and heat resistance, and is further filled and cured. An object of the present invention is to provide an insulating thermosetting resin composition in which cracks and voids are hardly generated in the filler.

  Another object of the present invention is to provide a wiring board filled with the thermosetting resin composition.

の構造を有するトリグリシジルアミノフェノール型エポキシ樹脂と、
下式（ＩＩ）

（式ＩＩにおいて、ｎが０．１〜０．２である。）
の構造を有するフェノールノボラック型エポキシ樹脂であり、
前記（Ｂ）硬化剤がトリアジン構造を含むイミダゾール化合物であることを特徴とする熱硬化性樹脂組成物により達成することができる。 The above purpose is
(A) Two or more types of polyfunctional epoxy resins,
Including (B) a curing agent, and (C) including an inorganic filler,
(A) Two or more types of polyfunctional epoxy resins are
2 types of polyfunctional epoxy resins that are liquid at 20 ° C., and the polyfunctional epoxy resin that is liquid at 20 ° C.
Formula (I)

A triglycidylaminophenol type epoxy resin having the structure:
Formula (II)

(In Formula II, n is 0.1 to 0.2.)
A phenol novolac type epoxy resin having the structure:
The (B) curing agent can be achieved by a thermosetting resin composition characterized in that it is an imidazole compound containing a triazine structure.

The d epoxy resin monomer (compound) but the polymer also contains, in this specification, if the epoxy resin is a polymer, "3 or more" in three or more epoxy groups in one molecule, in a molecule It means that it is 2.1 or more on average.

  Preferred embodiments of the thermosetting resin composition of the present invention are listed below.

(1) (A) At least one of two or more types of polyfunctional epoxy resins is an epoxy resin that is liquid at 20 ° C.
(2) (A) At least one of two or more polyfunctional epoxy resins is an aminophenol type epoxy resin, particularly a triglycidyl aminophenol type epoxy resin.
(3) (A) At least one of the two or more polyfunctional epoxy resins different from the above (preferably in combination with a triglycidylaminophenol type epoxy resin) is a phenol novolac type epoxy resin.
(4) The viscosity of the thermosetting resin composition is in the range of 100 to 1000 dPa · s at 25 ± 1 ° C. (preferably 200 to 900 dPa · s, particularly 300 to 800 dPa · s). It is possible to satisfactorily fill the recesses and the through holes without generating voids or the like.
(5) For filling at least one of a recessed portion (eg, via hole) and a through hole of a printed wiring board. It is preferably for through holes (through holes).

The above purpose is
It can also be achieved by a printed wiring board in which at least one of the concave portion and the through hole of the printed wiring board is filled with the cured product of the thermosetting resin composition of the present invention.

  The thermosetting resin composition of the present invention uses an imidazole compound containing a triazine structure as a curing agent in a mixture of two or more types of polyfunctional epoxy resins and inorganic fillers, and uses such a thermosetting resin composition. When filling through holes and via holes in printed wiring boards, it exhibits good printability with low viscosity and excellent storage stability, and the resulting cured product has almost no cracks or voids. It also has excellent heat resistance. Such an effect is considered to be brought about by a combination of two or more kinds of polyfunctional epoxy resins and an imidazole compound containing a triazine structure as a curing agent.

  That is, for example, a multilayer printed board in which a resin filler is filled in a hole portion such as a through hole provided in a printed wiring board and cured, and then an interlayer resin insulating layer and a conductor circuit layer are alternately laminated on the wiring board. In a multilayer printed wiring board that directly forms a solder resist film on a wiring board or a substrate filled with a resin filler in a through hole, by using the thermosetting resin composition of the present invention as a resin filler, There is no generation of cracks or peeling of the outer insulating layer (solder resist layer or insulating resin layer) around the hole insulating layer (delamination), etc., and a highly reliable printed wiring board excellent in various characteristics can be obtained. .

  In the present specification, the “hole” is a general term for a through hole, a via hole, or the like formed in the manufacturing process of the printed wiring board.

It is a schematic side view which shows the two test tubes used for the liquid determination of the epoxy resin. It is a schematic sectional drawing which shows the formation process of the hole part insulating layer and outer layer insulating layer of a printed wiring board.

  Hereinafter, the printed wiring board which has each component which comprises a thermosetting resin composition, and the insulating hardened | cured material obtained by hardening the same composition is demonstrated.

  The thermosetting resin composition of the present invention comprises (A) two or more kinds of polyfunctional epoxy resins, (B) a curing agent, and (C) an inorganic filler as main components, and (B) a triazine structure as a curing agent. An imidazole compound containing is used.

  As the epoxy resin (A), two or more kinds of polyfunctional epoxy resins are used. The polyfunctional epoxy resin is an epoxy resin having three or more epoxy groups in one molecule. In the present invention, it is preferable to use two types of polyfunctional epoxy resins, but other than these, other 1, 2 or polyfunctional epoxy resins may of course be used.

  Polyfunctional epoxy resins include phenol novolac type epoxy resins, alkylphenol novolac type epoxy resins, aminophenol type epoxy resins (particularly triglycidyl aminophenol type epoxy resins), bisphenol A novolac type epoxy resins, naphthalene type epoxy resins, dicyclo Pentadiene type epoxy resin, glycidylamine type epoxy resin, trihydroxyphenylmethane type epoxy resin, tetraphenylolethane type epoxy resin, diglycidyl phthalate resin, phenols (including biphenol, bisphenol, cresol, etc.) and phenolic hydroxyl group. Epoxides of condensates with aromatic aldehydes and their bromine atom-containing epoxy resins and phosphorus atom-containing epoxy resins, triglycidyl isocyanate Isocyanurate, it may be mentioned alicyclic epoxy resins, a liquid alcohol ether type epoxy resin, a trifunctional or more epoxy resins, such as a fluorene epoxy resin. Examples of the bifunctional epoxy resin that may be used in combination include a biphenol type epoxy resin or a bisphenol type epoxy resin, specifically, a bisphenol A type epoxy resin, a hydrogenated bisphenol A type epoxy resin, or a bromination. Examples thereof include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, and bixylenol type epoxy resin.

  The bisphenol novolac type epoxy resin includes novolac type epoxy resins having a bisphenol structure such as bisphenol A novolac type epoxy resin and bisphenol F novolak type epoxy resin.

  One epoxy resin of two or more types of polyfunctional epoxy resins is preferably a polyfunctional epoxy resin having three or more epoxy groups in one molecule and liquid at 20 ° C.

  Examples of liquid phenolic novolak epoxy resins, liquid alkylphenol novolac epoxy resins, liquid aminophenol epoxy resins (particularly triglycidylaminophenol type) that have three or more epoxy groups in one molecule and are liquid at 20 ° C. Epoxy resin), liquid bisphenol A novolac type epoxy resin, liquid naphthalene type epoxy resin, liquid dicyclopentadiene type epoxy resin, liquid glycidylamine type epoxy resin, liquid trihydroxyphenylmethane type epoxy resin, liquid tetraphenylolethane type epoxy resin And liquid diglycidyl phthalate resin, liquid alicyclic epoxy resin, and liquid alcohol ether type epoxy resin. Among these, liquid aminophenol type epoxy resins (particularly, triglycidyl aminophenol type epoxy resins) are preferable.

  The other epoxy resin of the two or more types of polyfunctional epoxy resins is selected from the epoxy resins having three or more epoxy groups in one molecule. The other epoxy resin is a trifunctional epoxy resin, which may be liquid or solid.

  As a combination of two types of polyfunctional epoxy resins, a combination of two types of polyfunctional epoxy resins that are liquid at 20 ° C., a combination of a polyfunctional epoxy resin that is liquid at 20 ° C. and a polyfunctional epoxy resin that is solid at 20 ° C., 20 Two types of combinations of polyfunctional epoxy resins that are solid at ℃ are possible. In the present invention, a combination of two types of polyfunctional epoxy resins that are liquid at 20 ° C., or a combination of a polyfunctional epoxy resin that is liquid at 20 ° C. and a polyfunctional epoxy resin that is solid at 20 ° C. is preferable. Two combinations of functional epoxy resins are preferred.

  Here, the “liquid” determination method referred to in this specification will be described.

  Judgment of liquid state shall be made in accordance with the second “Liquid Confirmation Method” of the Ministerial Ordinance on Dangerous Goods Testing and Properties (Ministry of Local Government Ordinance No. 1 of 1989).

(1) Apparatus Constant-temperature water bath: A device equipped with a stirrer, a heater, a thermometer, and an automatic temperature controller (with temperature control at ± 0.1 ° C.) having a depth of 150 mm or more.

  In the determination of the epoxy resin used in the examples to be described later, a combination of a low temperature thermostatic water tank (model BU300) manufactured by Yamato Scientific Co., Ltd. and a thermostat (model BF500) of the input type thermostatic apparatus (model BF500) is used. Put 22 liters in a low temperature constant temperature water bath (model BU300), turn on the thermomate (model BF500) assembled to it and set it to the set temperature (20 ° C or 40 ° C), and set the water temperature to the set temperature ± 0.1 Although fine adjustment was performed with a thermomate (model BF500) at 0 ° C., any apparatus capable of the same adjustment can be used.

Test tube:
As shown in FIG. 1, the test tube is made of a flat bottom cylindrical transparent glass having an inner diameter of 30 mm and a height of 120 mm, and marked lines 11 and 12 are respectively provided at heights of 55 mm and 85 mm from the tube bottom. The test tube 10a for liquid judgment with the mouth of the test tube sealed with a rubber plug 13a, and a rubber plug 13b having the same size and the same marked line, and a hole for inserting and supporting a thermometer in the center A test tube 10b for temperature measurement in which the mouth of the test tube is sealed and a thermometer 14 is inserted into the rubber plug 13b is used. Hereinafter, a marked line having a height of 55 mm from the tube bottom is referred to as “A line”, and a marked line having a height of 85 mm from the tube bottom is referred to as “B line”.

  As the thermometer 14, the one for freezing point measurement (SOP-58 scale range 20-50 ° C.) specified in JIS B7410 (1982) “Petroleum test glass thermometer” is used, but the temperature is 0-50 ° C. It is sufficient if the range can be measured.

(2) Test procedure The sample that was allowed to stand for 24 hours or more at an atmospheric pressure of 20 ± 5 ° C. was used for the liquid determination test tube 10a shown in FIG. 1 (a) and the temperature measurement test shown in FIG. 1 (b). Insert up to line A in each tube 10b. Two test tubes 10a and 10b are left standing in a low-temperature thermostatic water tank so that the line B is below the water surface. The thermometer has its lower end 30 mm below the A line.

  The state is maintained as it is for 10 minutes after the sample temperature reaches the set temperature ± 0.1 ° C. After 10 minutes, remove the liquid judgment test tube 10a from the low-temperature water bath, immediately lay it down horizontally on a horizontal test bench, and use the stopwatch to measure the time the tip of the liquid level in the test tube has moved from line A to line B. Measure and record. A sample is determined to be liquid if the measured time is within 90 seconds at a set temperature, and solid if it exceeds 90 seconds.

  As the combination of resin types in the two types of polyfunctional epoxy resins, aminophenol type epoxy resins (particularly, triglycidylaminophenol type epoxy resins), phenol novolac type epoxy resins, alkylphenol novolak type epoxy resins, and naphthalene type epoxy resins. , Dicyclopentadiene type epoxy resin, aminophenol type epoxy resin, hydrogenated bisphenol type epoxy resin, alicyclic epoxy resin, alcohol ether type epoxy resin, alicyclic epoxy resin or fluorene type epoxy resin Can do. In particular, aminophenol type epoxy resins (particularly triglycidyl aminophenol type epoxy resins), phenol novolac type epoxy resins, alkylphenol novolac type epoxy resins, naphthalene type epoxy resins, dicyclopentadiene type epoxy resins, aminophenol type epoxy resins, Combination with hydrogenated bisphenol type epoxy resin or cycloaliphatic epoxy resin, especially aminophenol type epoxy resin (especially triglycidyl aminophenol type epoxy resin), phenol novolac type epoxy resin, alkylphenol novolac type epoxy resin or dicyclopentadiene A combination with a mold epoxy resin is preferred.

  Commercially available triglycidylaminophenol type epoxy resins include jER-630 manufactured by Mitsubishi Chemical Corporation, ELM-100 manufactured by Sumitomo Chemical Co., Ltd., ELM-100H, manufactured by Huntsman Advantest Materials, Inc. MY0510, Epicron 430-L of DIC Corporation, Epicron 430, and the like.

  The triglycidylaminophenol type epoxy resin generally has the structure of the following formula (I):

  The phenol novolac type epoxy resin generally has a structure represented by the following formula (II):

式ＩＩにおいて、ｎが０．１〜３．０、好ましくは０．２〜１．８であり、ベンゼン環はメチル基等の低級アルキル基を置換基として有していてもよい。

In Formula II, n is 0.1 to 3.0, preferably 0.2 to 1.8, and the benzene ring may have a lower alkyl group such as a methyl group as a substituent.

  Dicyclopentadiene type epoxy resins generally have the structure of the following formula (III):

式ＩＩＩにおいて、ｎが０．１〜３．０、好ましくは０．２〜１．８であり、ベンゼン環はメチル基等の低級アルキル基を置換基として有していてもよい。

In Formula III, n is 0.1 to 3.0, preferably 0.2 to 1.8, and the benzene ring may have a lower alkyl group such as a methyl group as a substituent.

  In the combination of two types of polyfunctional epoxy resins, when one of the two types of polyfunctional epoxy resins is an aminophenol type epoxy resin, the mass ratio of aminophenol type epoxy resin to other epoxy resin (aminophenol type: other ) Is preferably in the range of 30:70 to 90:10, particularly 40:60 to 80:20. By making the mass ratio (aminophenol type: other) above the lower limit, the water absorption rate of the cured product can be kept low, delamination can be suppressed, and by making it below the upper limit, good water absorption and heat resistance can be obtained. Can do.

  Further, as described above, the epoxy resin may be used in addition to the above two types, and may contain a monofunctional epoxy resin as a reactive diluent.

  By using two or more types of polyfunctional epoxy resins, for example, a low molecular weight liquid polyfunctional epoxy resin contributes to a decrease in the viscosity of the composition and an improvement in the flexibility and adhesion of the resulting cured film. Since the polyfunctional epoxy resin having a molecular weight contributes to raising the glass transition point, a cured product having a balanced property can be obtained by adjusting these ratios as described above.

  In the present invention, an imidazole compound containing a triazine structure is used as the epoxy resin curing agent (B). The imidazole compound containing a triazine structure generally has 1 to 3 imidazolyl groups or imidazolylalkyl groups (alkyl is preferably alkyl having 1 to 4 carbon atoms, particularly preferably ethyl) which may have a substituent (preferably 1) A substituted triazine. By using an imidazole compound containing a triazine structure, it is possible to obtain excellent physical properties such as an improvement in storage stability and the absence of cracks and voids. In particular, the above-mentioned two types of polyfunctional epoxy resins and By using in combination, a cured product with high heat-reliability can be obtained together with the above excellent storage stability.

  Examples of imidazole compounds containing a triazine structure include 2,4-diamino-6- [2′-methylimidazolyl- (1 ′)]-ethyl-S-triazine, 2,4-diamino-6- [2′-. Methyl imidazolyl-(1 ')]-ethyl-s-triazine, 2,4-diamino-6- [2'-undecylimidazolyl- (1')]-ethyl-s-triazine, 2,4-diamino-6 -[2'-ethyl-4'-methylimidazolyl- (1 ')]-ethyl-s-triazine and the like can be mentioned. These are marketed under trade names (manufactured by Shikoku Kasei Co., Ltd.) such as 2MZ-A, 2MZ-AP, 2MZA-PW, C11Z-A, 2E4MZ-A. 2,4-diamino-6- [2'-methylimidazolyl- (1 ')]-ethyl-S-triazine, 2,4-diamino-6- [2'-ethyl-4'-methylimidazolyl- (1' )]-Ethyl-s-triazine is preferred. Thereby, the storage stability of a thermosetting resin composition is excellent, and the hardened | cured material which does not generate | occur | produce a crack by short-time hardening is obtained.

  In the present invention, as the epoxy resin curing agent (B), a compound other than an imidazole compound containing a triazine structure can be used as a secondary agent.

  Imidazole derivatives such as 2-methylimidazole, 4-methyl-2-ethylimidazole, 2-phenylimidazole, 4-methyl-2-phenylimidazole, 1-benzyl-2-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole and the like.

  Besides imidazole, dicyandiamide and its derivatives, melamine and its derivatives, diaminomaleonitrile and its derivatives, diethylenetriamine, triethylenetetramine, tetramethylenepentamine, bis (hexamethylene) triamine, triethanolamine, diaminodiphenylmethane, organic acid hydrazide Amines such as 1,8-diazabicyclo [5.4.0] undecene-7 (trade name DBU, manufactured by San Apro Co., Ltd.), 3,9-bis (3-aminopropyl) -2,4,8, 10-tetraoxaspiro [5.5] undecane (trade name ATU, manufactured by Ajinomoto Co., Inc.), or organic phosphine compounds such as triphenylphosphine, tricyclohexylphosphine, tributylphosphine, methyldiphenylphosphine, etc. alone or Two or more Only together can be used.

  Further, dicyandiamide, melamine, acetoguanamine, benzoguanamine, 3,9-bis [2- (3,5-diamino-2,4,6-triazaphenyl) ethyl] -2,4,8,10-tetraoxa It is known that guanamine such as spiro [5.5] undecane and derivatives thereof, and their organic acid salts and epoxy adducts have adhesion and rust prevention properties with copper, and are used as curing catalysts for epoxy resins. In addition to working, it can contribute to the prevention of discoloration of copper on the printed wiring board.

  The compounding quantity of a hardening | curing agent (B) is 3-20 mass parts per 100 mass parts of epoxy resins (A), Furthermore, 5-15 mass parts is preferable. By setting the blending amount of the epoxy resin curing agent (B) to 3 parts by mass or more, generally the pre-curing speed of the resin composition is moderately increased, and the composition in the deep part of the hole is cured well. Since it becomes difficult to generate | occur | produce, it is preferable. In addition, when the amount of the epoxy resin curing agent (B) is 20 parts by mass or less, storage stability is maintained, and generally the pre-curing speed of the resin composition does not become too fast, and voids are present in the cured product. It is preferable because it does not easily remain.

  Examples of the inorganic filler (C) include barium sulfate, barium titanate, silicon oxide powder, finely divided silicon oxide, amorphous silica, talc, clay, magnesium carbonate, calcium carbonate, aluminum oxide, aluminum hydroxide, mica powder, Known and commonly used inorganic fillers such as Neuburg silica can be used. The inorganic filler is preferably contained at 40 to 90% by mass in the total composition. By setting it as 40 mass% or more, the thermal expansion coefficient of hardened | cured material can be made low and generation | occurrence | production of delamination can be suppressed. On the other hand, by setting it to 90% by mass or less, it is possible to form a liquid paste, and it is possible to maintain good printability, hole filling and filling properties.

  The average particle diameter of the inorganic filler (C) is preferably 0.1 to 25 μm, more preferably 0.5 to 10 μm, and particularly preferably 1 to 10 μm. Examples of the shape of the inorganic filler (C) include a spherical shape, a needle shape, a plate shape, a scale shape, a hollow shape, an indeterminate shape, a hexagonal shape, a cubic shape, and a flake shape. Is preferred.

  In the liquid thermosetting resin composition of the present invention, since it is possible to make the viscosity low, it is not always necessary to use a diluting solvent, but in order to adjust the viscosity of the composition, the diluting solvent should be used to such an extent that no voids are generated. It may be added.

  Diluent solvents include ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene and tetramethylbenzene; methyl cellosolve, butyl cellosolve, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol mono Glycol ethers such as ethyl ether and triethylene glycol monoethyl ether; Esters such as ethyl acetate, butyl acetate and acetic acid ester of the above glycol ethers; Alcohols such as ethanol, propanol, ethylene glycol and propylene glycol; Octane And aliphatic hydrocarbons such as decane; petroleum solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha.

  Further, the thermosetting resin composition of the present invention may be applied to known and commonly used colorings such as phthalocyanine blue, phthalocyanine green, iodine green, disazo yellow, crystal violet, titanium oxide, carbon black, and naphthalene black. In order to impart storage stability during storage, known conventional thermal polymerization inhibitors such as hydroquinone, hydroquinone monomethyl ether, tert-butylcatechol, pyrogallol, phenothiazine, clay, kaolin, organic bentonite, montmorillonite, etc. Such as thickeners or thixotropic agents, silicone-based, fluorine-based, polymer-based antifoaming agents and / or leveling agents, imidazole-based, thiazole-based, triazole-based, silane coupling agents, etc. It can be blended additives such conventionally known. In particular, when organic bentonite is used, a precured product portion protruding from the surface of the hole portion is easily formed in a protruding state that can be easily polished and removed, and is excellent in polishing properties.

  The thermosetting resin composition of the present invention obtained as described above can be used for via holes and through-holes in printed wiring boards by using conventionally used methods such as screen printing, roll coating, and die coating. A hole such as a hole can be easily filled.

  For this reason, it is preferable that the viscosity of the thermosetting resin composition of this invention exists in the range of 100-1000 dPa * s at 25 +/- 1 degreeC, 200-900 dPa * s, especially 300-800 dPa * s. By setting it as such a range, a recessed part and a through-hole can be filled favorably easily without the filling of a hole part and generation | occurrence | production of a void etc.

  Moreover, it is preferable that the glass transition temperature (Tg) of the thermosetting resin composition of this invention is 150 degreeC or more, and it is more preferable that it is 160 degreeC or more. When Tg is 150 ° C. or higher, generation of delamination can be suppressed.

    Hereinafter, the formation of the hole insulating layer and the outer insulating layer (solder resist layer and insulating resin layer) of the printed wiring board will be specifically described with reference to the accompanying drawings. The attached drawings show an example in which a double-sided board is used as a core board, but the present invention can be similarly applied to a multilayer printed wiring board.

(1) Filling holes First, plated through holes 3 of the core substrate 1 as shown in FIG. 2A (in the case of using a multilayer printed wiring board as the core substrate, holes such as via holes in addition to the plated through holes) In addition, the thermosetting resin composition of the present invention is filled as shown in FIG. For example, a mask having an opening in the through hole portion is placed on the substrate and filled into the through hole by a printing method or a dot printing method. As the core substrate 1, a through-hole is drilled in a glass epoxy substrate laminated with copper foil, or a substrate 2 such as a polyimide substrate, a bismaleimide-triazine resin substrate, a fluororesin substrate, a ceramic substrate, or a metal substrate. In addition, it is possible to suitably use a plated through hole 3 and a conductor circuit layer 4 formed by electroless plating or further electrolytic plating on the wall surface of the through hole and the copper foil surface. Copper plating is generally used as the plating.

(2) Polishing Next, the filler is precured. For example, the preliminary curing is performed by heating at about 90 to 130 ° C. for about 30 to 90 minutes. It is preferable to perform primary preliminary curing at about 90 to 110 ° C. and then secondary preliminary curing at about 110 to 130 ° C. Since the hardness of the cured product preliminarily cured in this manner is relatively low, unnecessary portions protruding from the substrate surface can be easily removed by physical polishing, and a flat surface can be obtained. The “pre-cured” or “pre-cured product” as used herein generally refers to those having an epoxy reaction rate of 80% to 97%. The hardness of the precured product can be controlled by changing the precuring heating time and heating temperature. Then, as shown in FIG.2 (c), the unnecessary part of the precured material 5 which protruded from the through hole is removed by grinding | polishing, and it planarizes. Polishing can be performed by belt sander, buffing or the like.

(3) Formation of outer insulating layer After that, the substrate surface is pretreated by buffing or roughening as necessary, and then the outer insulating layer 6 is formed as shown in FIG. Since the roughened surface excellent in the anchor effect is formed by this pretreatment, the adhesiveness with the outer insulating layer 6 applied thereafter is excellent. The outer insulating layer 6 is a solder resist layer, an insulating resin layer, a protective mask, or the like according to a subsequent process, and can be formed of a conventionally known curable resin composition. When a fine pattern is formed on the outer insulating layer, it is preferable to use a photocurable / thermosetting resin composition or a dry film thereof. Thereafter, the film is heated at about 130 to 180 ° C. for about 30 to 90 minutes to be fully cured (finish cured) (when a photocurable / thermosetting resin composition is used for forming the outer insulating layer, a known method is used). Then, after drying (temporary curing) and exposure, main curing is performed to form the outer insulating layer 6.

  When a double-sided substrate as shown in FIG. 2 (a) is used as the core substrate 1, the formation of the conductor circuit layer by electroless plating and electrolytic plating and the formation of the interlayer resin insulation layer are alternately performed according to a well-known method. Repeatedly, if necessary, via holes are formed (if the interlayer resin insulation layer contains a photosensitive resin, it is exposed and developed, and if it contains a thermosetting resin or thermoplastic resin, laser light is used. It is also possible to form a multilayer printed wiring board.

  In addition, as a material of an interlayer resin insulation layer, a copper foil with resin, a dry film, a prepreg, or the like can be used.

EXAMPLES The present invention will be specifically described below with reference to examples, reference examples, and comparative examples, but the present invention is not limited to the following examples. In the following, “parts” means all parts by mass unless otherwise specified.

[Examples 1, 2, 3, 4, 5, Reference Examples 6 and 7 and Comparative Examples 1 to 4]
The components listed in Table 1 below were blended in the proportions shown in Table 1 and premixed, and then kneaded and dispersed with a three-roll mill to obtain a thermosetting resin composition paste.

  The components in Table 1 are as follows.

Bifunctional liquid epoxy resin (1): Bisphenol A type epoxy resin (trade name: JER-828; manufactured by Mitsubishi Chemical Corporation)
Bifunctional liquid epoxy resin (2): Bisphenol F type epoxy resin (trade name: JER-807; manufactured by Mitsubishi Chemical Corporation)
Polyfunctional liquid epoxy resin (3): Triglycidyl paraaminophenol type epoxy resin (Formula I, trade name ELM-100; manufactured by Sumitomo Chemical Co., Ltd.)
Polyfunctional liquid epoxy resin (4): Phenol novolac type epoxy resin (n = 0.2 of formula II, phenol novolac type epoxy resin, trade name DEN-431; manufactured by DOW)
Polyfunctional solid epoxy resin (5): Dicyclopentadiene type epoxy resin (n = 0.1 to 3.0 of formula III, dicyclopentadiene type epoxy resin, trade name HP-7200L; Dainippon Ink & Chemicals, Inc.) Made)
Polyfunctional solid epoxy resin (6): phenol novolac type epoxy resin (n = 1.6 of formula II (trade name DEN-438; manufactured by DOW))
Curing agent (7) 2MZ-A (2,4-diamino-6- [2'-methylimidazolyl- (1 ')]-ethyl-S-triazine; manufactured by Shikoku Chemicals Co., Ltd.)
Curing agent (8) 2E4MZ-A (2,4-diamino-6- [2'-ethyl-4'-methylimidazolyl- (1 ')]-ethyl-s-triazine; manufactured by Shikoku Kasei Kogyo Co., Ltd.)
Curing agent (9) 2E4MZ-CN (1-cyanoethyl-2-ethyl-4-methylimidazole; manufactured by Shikoku Chemicals Co., Ltd.)
Spherical silica (10) (D50 = 5.6 μm; trade name FB-7SDX, manufactured by Denki Kagaku Kogyo Co., Ltd.)
Heavy calcium carbonate (11) (D50 = 1.2μm; trade name Micropowder 3N, manufactured by Bihoku Flour Chemical Co., Ltd.)
Antifoaming agent (12) (trade name KS-66, manufactured by Shin-Etsu Chemical Co., Ltd.)
Organic bentonite (13) (Brand name Orben, manufactured by Shiroishi Kogyo Co., Ltd.)

[Evaluation method]
1. Viscosity For the thermosetting resin compositions of Examples 1, 2, 3, 4, 5, Reference Examples 6 and 7, and Comparative Examples 1 to 4, the viscosity at 25 ° C. was measured. That is, 0.2 ml of a sample was collected, and the viscosity was set at 30 ° C. at 25 ° C. and 5 rpm with a cone plate viscometer (TV-33 manufactured by Toki Sangyo Co., Ltd.).

2. Printability (fillability) was evaluated in each of the thermosetting resin compositions of the printability examples , reference examples, and comparative examples. As the evaluation substrate, a glass epoxy substrate in which through holes were formed by panel plating was used. The specification was a substrate having a small diameter through hole (TH) with a plate thickness: 0.8 mm, through hole diameter: 0.1 mm, and through hole pitch: 1.0 mm. A dot pattern was printed on such an evaluation board by a semi-automatic printing machine, and the printability (fillability) was evaluated as follows.

<Printing conditions>
Squeegee: Squeegee thickness 20 mm, hardness 70 °, oblique polishing: 25 °,
Plate: PET100 mesh bias plate,
Printing pressure: 50 kgf / cm ² , Squeegee angle: 75 °
Printing was performed in one stroke, and the maximum printing speed at which the thermosetting resin composition could be discharged on the extruded surface side was compared.
○: Faster than 20 mm / sec Δ: 5 to 20 mm / sec
×: Slower than 5mm / sec

3 . Water absorption rate The pastes of thermosetting resin compositions of Examples , Reference Examples and Comparative Examples were applied by screen printing to ceramic plates weighed in advance , and cured at 150 ° C. for 30 minutes in a hot air circulating drying oven. An evaluation sample was obtained. After cooling this to room temperature, the weight of the evaluation sample was measured.
The evaluation sample was 121 ° C., 100% R.D. H. The PCT (pressure cooker) treatment was performed under the conditions of 24 hours, the weight of the cured product after the treatment was measured, and the water absorption rate of the cured product was determined by the following formula.

Water absorption (%) = (W2−Wg) / (W1−Wg) × 100
Here, W2 is the evaluation sample weight (g) after the PCT treatment, W1 is the initial evaluation sample weight (g), and Wg is the ceramic plate weight (g).

4 . TMA
Each thermosetting resin composition of Examples , Reference Examples and Comparative Examples is applied to the glossy surface side (copper foil) of GTS-MP foil (Furukawa Circuit Foil Co., Ltd.) with an applicator, and is applied to a hot-air circulating drying oven. And cured at 150 ° C. for 60 minutes. Then, after peeling hardened | cured material from copper foil, the sample was cut out to measurement size and it used for the TMA measurement.

  TMA measurement measured the glass transition point Tg using the thermomechanical analyzer (TMA-120).

  The measurement conditions were that both 1st run and 2nd run were carried out by raising the temperature from room temperature to 300 ° C. at a rate of 10 ° C./min, and the bending point of the 2nd run linear expansion curve was Tg.

5 . Storage Stability The initial viscosity of each thermosetting resin composition of Examples , Reference Examples and Comparative Examples was compared with the viscosity after storage at 25 ° C. for 7 days.

The thickening rate was calculated from the following formula.
Thickening rate = (viscosity after storage at 25 ° C for 7 days / initial viscosity) x 100
The storage stability was evaluated as follows according to the value of the thickening rate.
○: Less than 10% △: 10-30%
X: Greater than 30%

6 . Generation of cracks and voids The thermosetting resin compositions of Examples , Reference Examples and Comparative Examples were screened on a glass epoxy substrate (thickness 1.6 mm, through hole diameter 0.25 mm) in which through holes were formed by panel plating. The through hole was filled by a printing method.

  This was put into a hot air circulation type drying furnace and held at 150 ° C. for 30 minutes to prepare an evaluation sample.

Each evaluation sample was cut at the through-hole portion, and the cross section was observed with an optical microscope to count the number of occurrences of cracks and voids in 100 through-holes. Evaluation was performed as follows.
○: 0 △: 1-10 ×: 11 or more

7 . Moisture absorption reflow heat resistance test Each thermosetting resin composition was filled in the through holes by screen printing on a glass epoxy board (plate thickness 1.6 mm, through hole diameter 0.25 mm) formed with through holes by panel plating. .

  This was placed in a hot air circulation drying oven and cured at 150 ° C. for 30 minutes. Then, the part which protruded from the board | substrate surface of hardened | cured material was grind | polished with the buffing machine (made by Ishii notation) using the high cut buff # 320 (made by Sumitomo 3M Co., Ltd.).

  Humidification treatment was performed for 48 hours in an environment of 121 ° C. and 100%.

  Next, after performing CZ-8101 (1 μm etching) + CL-8300 treatment made by MEC as pretreatment, a prepreg having a thickness of 0.1 mm on both sides of the substrate (equivalent to R-1661 FR-4 made by Matsushita Electric Works Co., Ltd.) Then, copper foil (GTS-MP-18 manufactured by Furukawa Circuit Foil Co., Ltd.) was press-molded by a press machine (KVHC-PRESS manufactured by Kitagawa Seiki Co., Ltd.) to obtain an evaluation substrate.

After the evaluation substrate is reflowed (peak temperature: 270 ° C. × 5 cycles), it is cut at the through-hole portion, and the cross section is observed with an optical microscope to confirm the occurrence of delamination between the upper portion of the hole filling and the prepreg. It was evaluated as follows.
○: 0 pieces Δ: 1 to 10 pieces ×: 11 pieces or more The above results are shown in Table 2.

  As is apparent from the results shown in Table 2, an inorganic failer comprising a thermosetting composition having the characteristic requirements of the present invention, that is, two types of epoxy resins having three or more functions and an imidazole compound having a triazine structure as a curing agent. Only the thermosetting composition containing, showed almost satisfactory results in all physical properties. That is, it was shown that Examples 2, 4 and 5 combined with the polyfunctional liquid epoxy were excellent in all properties. In Examples 6 and 7, which combined semi-solid or solid epoxy, the generation of voids was slightly observed due to increased viscosity. In Example 1 with few fillers, moisture absorption reflow heat resistance was somewhat inferior, and in Example 3 using heavy calcium carbonate, voids were seen. In all Examples, since a curing agent containing a triazine structure was used, the storage stability was good, and there was a tendency for voids and cracks during curing to be small.

  On the other hand, when only two types of bifunctional liquid epoxy resins of Comparative Example 1 were used, voids were generated. This is considered because the viscosity of the composition (ink) was not sufficiently lowered. Further, the glass transition point is lower than that of the example, and it is considered that a large amount of delamination occurred in the moisture absorption reflow heat resistance test.

  Since only the amine type epoxy resin was used in Comparative Example 2, the water absorption rate was high, and it is considered that a lot of delamination occurred in the moisture absorption reflow heat resistance test.

  Comparative Example 3 used two types of tri- or higher functional epoxy resins as in the present invention. However, since imidazole containing a triazine structure was not used as a curing agent, storage stability was poor and many voids and cracks occurred during curing. It is thought that.

  In the case of the composition in which the bifunctional epoxy resin and the polyfunctional epoxy resin of Comparative Example 4 were combined, a lot of delamination occurred as in Comparative Example 1.

DESCRIPTION OF SYMBOLS 1 Core board | substrate 2 Board | substrate 3 Plating through hole 4 Conductor circuit layer 5 Hole part insulating layer (hardened | cured material of a thermosetting resin composition)
6 Outer insulation layer

Claims (4)

(A) Two or more types of polyfunctional epoxy resins,
(B) a curing agent, and (C) an inorganic filler,
(A) Two or more types of polyfunctional epoxy resins are
2 types of polyfunctional epoxy resins that are liquid at 20 ° C., and the polyfunctional epoxy resin that is liquid at 20 ° C.
Formula (I)

A triglycidylaminophenol type epoxy resin having the structure:
Formula (II)

(In Formula II, n is 0.1 to 0.2.)
A phenol novolac type epoxy resin having the structure:
The thermosetting resin composition, wherein the curing agent (B) is an imidazole compound containing a triazine structure. The thermosetting resin composition according to claim 1 , wherein the viscosity is in the range of 100 to 1000 dPa · s at 25 ± 1 ° C. The thermosetting resin composition according to claim 1 or 2 , which is used for filling at least one of a concave portion and a through hole of a printed wiring board. The printed wiring board with which at least one of the recessed part and through-hole of a printed wiring board was filled with the hardened | cured material of the thermosetting resin composition of any one of Claims 1-3 .

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