JP5238342B2 - Thermosetting resin composition for hole filling of printed wiring board and printed wiring board using the same - Google Patents

Description

The present invention relates to a thermosetting resin composition for filling a printed wiring board, particularly a liquid thermosetting useful as a composition for filling a permanent hole such as a through hole or a via hole in a printed wiring board such as a multilayer board or a double-sided board. The present invention relates to a functional resin composition. Furthermore, this invention relates to the printed wiring board which performed permanent hole filling, such as a through hole and a via hole, using this composition.
In this 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.

  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. Is covered. Thus, the solder resist film prevents solder from adhering to unnecessary parts when mounting electronic components on a printed wiring board, and also prevents the circuit from being oxidized or corroded. Have.

  By the way, in recent years, the conductor circuit pattern of the printed wiring board has been thinned and the mounting area has been reduced, and further, the printed wiring board has been made lighter and thinner in order to cope with the downsizing and higher functionality of the equipment equipped with the printed wiring board. Shortening is desired. Therefore, after filling the through hole provided in the printed wiring board with a resin filler and curing it to make a smooth surface, multilayer printed wiring in which interlayer resin insulation layers and conductor circuit layers are alternately laminated on the wiring board A multilayer printed wiring board has been developed in which a solder resist film is directly formed on a board or a substrate in which through holes are filled with a resin filler. Under such circumstances, it is desired to develop a permanent hole filling composition excellent in filling properties, polishing properties, cured product characteristics, and the like for filling holes such as through holes and via holes.

  Also, particularly in Taiwan and Asia, a specification that fills all the through holes of a wiring board such as a copper through-hole wiring board with a liquid solder resist composition, that is, filling a printed wiring board and forming a solder resist film simultaneously. The method has become mainstream. However, when the conventional liquid solder resist composition is used to fill the through holes of a wiring board such as a copper through-hole wiring board, for example, the formed solder resist film is formed around the through-holes during solder leveling. There is a problem that a phenomenon that a part floats (hereinafter abbreviated as “delamination”) or a phenomenon that a coating film in a through-hole protrudes during post-cure or solder leveling has occurred.

  In order to solve such problems, various measures have been considered. For example, it has been proposed to use a photo solder resist composition characterized by a combination of active energy ray-curable resins to be used (Patent Literature). 1). However, when the hole in the printed wiring board and the formation of the solder resist film are simultaneously performed using the photo solder resist composition, since the solvent is included, there is a problem that curing shrinkage and cracks occur in the hole insulating layer after curing. there were. Moreover, since the aspect ratio of the through hole is high, there is a problem that the deep part curability is insufficient and the rate of change of the coefficient of thermal expansion during the heat cycle is large.

  Therefore, generally, different compositions are used for filling a printed wiring board and forming a solder resist film. As a composition for permanent hole filling of a printed wiring board, a thermosetting epoxy resin composition is widely used because its cured product is generally excellent in mechanical, electrical and chemical properties and has good adhesion. It has been. In this case, the permanent filling process of the printed wiring board includes a step of filling the hole 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 comprises a step of polishing and removing a portion of the composition that protrudes from the hole surface, and a step of further heating and precuring the precured composition.

However, as described above, when an epoxy resin composition different from the solder resist composition is used for filling a hole in a printed wiring board, under high temperature conditions such as a curing process and solder leveling, as shown in FIG. Cracks (internal crack Y) are generated in the partial insulating layer 5, or peeling (delamination X) occurs between the outer insulating layer 6 (solder resist layer and insulating resin layer) in the peripheral portion of the hole insulating layer 5 There was a problem. When such cracks and delamination occur, the PCT resistance (pressure / cooker resistance) under high temperature and high humidity decreases, and the insulation reliability of the printed wiring board deteriorates.
International Publication WO2003 / 059975 (Claims)

The present invention has been made in view of the problems of the prior art as described above, and its basic purpose is optimal for filling holes such as through holes and via holes in a printed wiring board, Under high temperature conditions such as hardening treatment and solder leveling, cracks (internal cracks) occur in the hole insulating layer, or between the outer insulating layer (solder resist layer and insulating resin layer) around the hole insulating layer It is an object of the present invention to provide a thermosetting resin composition that can form a hole insulating layer having excellent insulation reliability, heat resistance, moisture resistance, PCT resistance, and the like.
Furthermore, the object of the present invention is that there is no occurrence of cracks during heat cycle, deterioration of insulation reliability, peeling of the outer insulating layer (solder resist layer or insulating resin layer) around the hole insulating layer (delamination), etc. An object of the present invention is to provide a highly reliable printed wiring board having excellent characteristics such as reliability, heat resistance, moisture resistance, and PCT resistance.

In order to achieve the above object, according to the present invention, (A) an epoxy resin, (B) an epoxy resin curing agent, and (C) an inorganic filler, the thermosetting that fills the hole of the printed wiring board. The epoxy resin (A) is obtained by dissolving a trifunctional or higher functional epoxy resin (A-2) in a liquid bifunctional epoxy resin (A-1), and the inorganic filler (C ) is silica free of, Ri Do from the salts of group IIa elements of the periodic table, and, mixing ratio of the inorganic filler (C) is characterized in that 45 to 85% by weight of the total composition filling A thermosetting resin composition is provided.

In a preferred embodiment, the epoxy resin (A) has a viscosity after dissolving a trifunctional or higher functional epoxy resin (A-2) in a liquid bifunctional epoxy resin (A-1) at 25 ° C. 100 dPa · s.
Furthermore, according to this invention, the printed wiring board characterized by the hole part of a printed wiring board being filled with the hardened | cured material of the said thermosetting resin composition is also provided.

The thermosetting resin composition of the present invention has an epoxy resin in the composition (A) is 3 or more functional epoxy resin (A-2) was dissolved in bifunctional epoxy resin (A-1) liquid since the filler (C) does not contain silica, Ri Do from the salts of group IIa elements of the periodic table, and, mixing ratio of the inorganic filler (C) is 45 to 85% by weight of the total composition, The cured product shows a high glass transition point Tg, and the rate of change in the coefficient of thermal expansion during the heat cycle is small. The occurrence of cracks and the outer insulating layer (solder resist layer and insulating resin layer) around the hole insulating layer There is a specific effect that there is no occurrence of delamination or the like.
Therefore, for example, after filling a resin filler in a hole such as a through hole provided in a printed wiring board and curing it, a multilayer print in which interlayer resin insulation layers and conductor circuit layers 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, deterioration of insulation reliability, peeling of the outer insulation layer (solder resist layer or insulation resin layer) around the hole insulation layer (delamination), etc., insulation reliability, heat resistance, moisture resistance, PCT resistance It is possible to provide a highly reliable printed wiring board having excellent characteristics such as the above.

The present inventors have developed a crack in a cured product of a conventional epoxy resin composition filled in a hole portion such as a through hole or a via hole of a printed wiring board and an outer insulating layer (a solder resist layer or a peripheral portion around the hole insulating layer). As a result of earnest research on the cause of delamination, etc. of the insulating resin layer), the cured product shows a low glass transition point Tg and is related to a large rate of change of the thermal expansion coefficient during the heat cycle. Was found mainly due to the epoxy resin used and the inorganic filler (silica) that has been generally used. Therefore, as a result of further research on this relationship, the epoxy resin (A) in the thermosetting resin composition is changed from a trifunctional or higher functional epoxy resin (A-2) to a liquid bifunctional epoxy resin (A-1). made from those dissolved, and contains no inorganic filler (C) is silica, Ri Do from the salts of group IIa elements of the periodic table, and, mixing ratio of the inorganic filler (C) of the total composition 45 In the case of 85% by mass , the cured product exhibits a high glass transition point Tg, and the rate of change in the coefficient of thermal expansion during the heat cycle is small. The present inventors have found that the occurrence of peeling (delamination) or the like of a layer or an insulating resin layer) can be suppressed, and the present invention has been completed.

Hereinafter, each component of the thermosetting resin composition of the present invention will be described in detail.
First, as the epoxy resin (A), a bifunctional epoxy resin (A-1) having two epoxy groups in one molecule and a trifunctional or more functional group having at least three epoxy groups in one molecule. An epoxy resin (A-2) is used in combination. Examples of the bifunctional epoxy resin (A-1) include bisphenol A type epoxy resin, hydrogenated bisphenol A type epoxy resin, brominated bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, Trifunctional or higher functional epoxy resin (A-2) such as xylenol type epoxy resin, biphenol type epoxy resin, phenol novolac type epoxy resin, alkylphenol novolac type epoxy resin, bisphenol A novolak type epoxy resin, naphthalene type epoxy resin, dicyclo Pentadiene type epoxy resin, glycidylamine type epoxy resin, trihydroxyphenylmethane type epoxy resin, tetraphenylolethane type epoxy resin, diglycidyl phthalate resin, phenols and vinyl Epoxidized products of condensates with aromatic aldehydes having a norlic hydroxyl group, or bromine atom-containing epoxy resins, phosphorus atom-containing epoxy resins, epoxy resins such as triglycidyl isocyanurate, and alicyclic epoxy resins Can be used alone or in combination of two or more. Moreover, you may contain the monofunctional epoxy resin as a reactive diluent.

  As the epoxy resin as described above, in particular, when a mixture of a trifunctional or higher functional epoxy resin (A-2) dissolved in a liquid bifunctional epoxy resin (A-1) at room temperature is used, a low molecular weight liquid resin is used. By adjusting these ratios, bifunctional epoxy resins contribute to improving the flexibility and adhesion of the resulting cured film, and trifunctional or higher epoxy resins contribute to raising the glass transition point. It becomes possible to adjust the balance of the above characteristics. That is, by using a mixture in which a predetermined amount of trifunctional or higher functional epoxy resin (A-2) is dissolved in a liquid bifunctional epoxy resin (A-1) at room temperature, the resulting cured product has a high glass transition point Tg. In addition, the rate of change in the coefficient of thermal expansion during the heat cycle is small, and it is effective to generate cracks and peeling (delamination) of the outer insulating layer (solder resist layer and insulating resin layer) around the hole insulating layer. Can be suppressed. Moreover, by using a liquid bifunctional epoxy resin (A-1), it becomes possible to make a composition solvent-free and it is effective in suppressing generation | occurrence | production of a void and a crack. The blending ratio (mass basis) of the liquid bifunctional epoxy resin (A-1) and the trifunctional or higher functional epoxy resin (A-2) is (A-1) :( A-2) = 100: 5 to 100: The range is 100, more preferably (A-1) :( A-2) = 100: 10 to 100: 40.

  Any epoxy resin curing agent (B) can be used as long as it has an effect of promoting the curing reaction of the epoxy resin, and is not limited to a specific one. Among these, an imidazole derivative is preferable, and an imidazole derivative that is solid at room temperature and that melts into a liquid epoxy resin at 150 ° C. is preferable. Specific examples of the imidazole derivative include, for example, 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. Specific examples of commercially available products include imidazoles such as trade names 2E4MZ, C11Z, C17Z, and 2PZ, AZINE compounds of imidazoles such as trade names 2MZ-A and 2E4MZ-A, trade names 2MZ-OK, and 2PZ-OK. And imidazole hydroxymethyl compounds such as trade names 2PHZ and 2P4MHZ (the trade names are all manufactured by Shikoku Kasei Kogyo Co., Ltd.).

  Besides imidazole, dicyandiamide and its derivatives, melamine and its derivatives, diaminomaleonitrile and its derivatives, diethylenetriamine, triethylenetetramine, tetramethylenepentamine, bis (hexamethylene) triamine, triethanolamine, diaminodiphenylmethane, organic acid Amines such as hydrazide, 1,8-diazabicyclo [5.4.0] undecene-7 (trade name DBU, manufactured by San Apro), 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, and methyldiphenylphosphine alone Or two It can be used in combination with the above. However, when aromatic amines are used, the resin composition after heat-curing shrinks greatly, and a gap is likely to form between the through-hole wall after curing and voids are likely to occur in the cured product in the hole filling portion. Absent. Among these curing catalysts, dicyandiamide, melamine, acetoguanamine, benzoguanamine, 3,9-bis [2- (3,5-diamino-2,4,6-triazaphenyl) ethyl] -2,4,8 , 10-tetraoxaspiro [5.5] undecane and derivatives thereof, and their organic acid salts and epoxy adducts are known to have adhesion and rust prevention properties with copper. In addition to acting as a curing catalyst for the resin, it can contribute to the prevention of discoloration of copper in the printed wiring board.

  The amount of the epoxy resin curing agent (B) as described above is generally 3 parts by mass or more and 20 parts by mass or less, preferably 5 parts by mass or more and 15 parts by mass or less per 100 parts by mass of the epoxy resin (A). Is appropriate. When the compounding amount of the epoxy resin curing agent (B) is less than 3 parts by mass, generally the pre-curing speed of the resin composition is slowed down and the composition in the deep part of the hole is insufficiently cured, resulting in generation of cracks. Since it becomes easy, it is not preferable. On the other hand, when the compounding amount of the epoxy resin curing agent (B) exceeds 20 parts by mass, the storage stability is deteriorated and generally the pre-curing speed of the resin composition becomes too fast, and voids are present in the cured product. Since it remains easily, it is not preferable.

  As the inorganic filler (C), salts of Group IIa elements of the periodic table, such as calcium carbonate, barium sulfate, magnesium carbonate, etc., can be used, and calcium carbonate is particularly preferable. Conventionally, silica is generally used as an inorganic filler in liquid thermosetting resin compositions for filling holes such as through-holes in printed wiring boards. However, as shown in Table 5 described later, when silica is used as the inorganic filler, delamination is likely to occur, which is not preferable.

The average particle size of the inorganic filler (C) is 0.1 μm or more and 25 μm or less, preferably 0.5 to 10 μm, more 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.

  Moreover, the compounding quantity of an inorganic filler (C) has preferable 45-85 mass% of the composition whole quantity. If it is less than 45% by mass, delamination tends to occur. On the other hand, if it exceeds 85% by mass, it becomes difficult to form a liquid paste, and printability, hole filling and filling properties cannot be obtained.

  In the liquid thermosetting resin composition of the present invention, when a liquid bifunctional epoxy resin is mainly used as an epoxy resin, it is not always necessary to use a diluting solvent. However, in order to adjust the viscosity of the composition, voids are not used. A diluting solvent may be added to such an extent that it does not occur.

  Diluting 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 liquid thermosetting resin composition of the present invention thus obtained is a conventionally used method such as a screen printing method, a roll coating method, a die coating method, etc. It is possible to easily fill the holes.
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. 1A (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) ) Is filled with the liquid thermosetting resin composition of the present invention as shown in FIG. Specifically, a mask having an opening in the through hole portion can be placed on the substrate and applied by a printing method or the like, or can be easily filled into the through hole by a dot printing method or the like. As the core substrate 1, a through hole is drilled in a substrate 2 such as a glass epoxy substrate laminated with copper foil, a polyimide substrate, a bismaleimide-triazine resin substrate, a fluororesin substrate, a ceramic substrate, a metal substrate, What formed the plated through hole 3 and the conductor circuit layer 4 by performing electroless plating or further electrolytic plating on the wall surface of the through hole and the copper foil surface can be suitably used. Copper plating is generally used as the plating.

(2) Polishing Next, the filler is precured. For example, it is pre-cured by heating at about 90 to 130 ° C. for about 30 to 90 minutes. Preferably, the primary precuring is performed at about 90 to 110 ° C, followed by the secondary precuring 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.1 (c), the unnecessary part of the precured material 5 which protruded from the through hole was removed by grinding | polishing, and it planarizes. Polishing can be suitably 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 depending on the processing performed thereafter, and various conventionally known thermosetting resin compositions and photocurable / thermosetting resin compositions. Such as resin sheet (dry film), glass cloth, glass and aramid non-woven fabric, etc. that are applied with a curable resin composition such as A sheet-like fibrous base material can be formed by laminating a resin sheet (prepreg sheet) that has been applied and / or impregnated and semi-cured. 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, the outer insulating layer 6 is formed by drying (temporary curing) and exposing to light followed by main curing. In addition, as a filler mix | blended with the said curable resin composition, it is preferable to use the salt of the IIa group element of a periodic table similarly to the said thermosetting resin composition for said hole filling for the reason mentioned above.

When a double-sided substrate as shown in FIG. 1 (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 a thermoplastic resin, the laser beam is used. In this case, a multilayer printed wiring board can be formed.
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 Hereinafter, the present invention will be described in detail with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the following description, “parts” are all based on mass unless otherwise specified.

Examples 1-7
The components listed in Table 1 below were blended in the proportions shown in Table 1, preliminarily mixed, and then kneaded with a three-roll mill to obtain a thermosetting resin composition paste.

Comparative Examples 1-5
The components listed in Table 2 below were blended in the proportions shown in Table 2, premixed, and then kneaded with a three-roll mill to obtain a paste of a thermosetting resin composition.

  Only the epoxy resins used in the thermosetting resin compositions of Examples 1 to 7 and Comparative Examples 1 to 5 (in the case of using two types of epoxy resins, a mixture thereof, in the case of using a single epoxy resin) Itself), the viscosity at 25 ° C. was measured by the following method. In Examples 1 to 7 and Comparative Examples 4 and 5, since a liquid bifunctional epoxy resin and a solid or semisolid trifunctional or higher epoxy resin were used in combination, the solid or semisolid with respect to the liquid epoxy resin was used. The solubility of the epoxy resin was visually evaluated. The test results are shown in Table 3. In the case of Example 7, since the viscosity at 25 ° C. is high, it is not preferable from the viewpoint of workability such as printing, so it is preferable to adjust the viscosity.

Viscosity at 25 ° C:
A sample of 0.2 ml was collected, and a 30 second value at 25 ° C. and a rotation speed of 5 rpm was defined as a viscosity using a cone plate viscometer (TV-33 manufactured by Toki Sangyo Co., Ltd.).

TMA (Thermo-mechanical analysis):
The thermosetting resin compositions for filling holes in Examples 1 to 6 and Comparative Examples 1 and 2 were applied on the glossy surface side (copper foil) of GTS-MP foil (manufactured by Furukawa Circuit Foil) with an applicator, Curing was carried out at 150 ° C. for 60 minutes in a hot air circulating drying oven. 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 was performed by raising the temperature of the sample from room temperature to 300 ° C. at a heating rate of 10 ° C./min. The glass transition temperature Tg and the thermal expansion coefficient CTE (α1) in the region below Tg and the region above Tg The coefficient of thermal expansion CTE (α2) was measured.
The results are shown in Table 4.

表４に示す結果から明らかなように、２官能の液状エポキシ樹脂のみを含有する液状熱硬化性樹脂組成物を用いた比較例１、２の場合、硬化物のガラス転移点Ｔｇが実施例１〜６の場合に比べて低く、また、ヒートサイクルにより熱膨張率の変化率も大きかった。

As is apparent from the results shown in Table 4, in the case of Comparative Examples 1 and 2 using a liquid thermosetting resin composition containing only a bifunctional liquid epoxy resin, the glass transition point Tg of the cured product is Example 1. It was low as compared with the case of ˜6, and the rate of change in the coefficient of thermal expansion was also large due to the heat cycle.

Reliability test:
Using the thermosetting resin compositions for filling holes in Examples 1 to 7 and Comparative Examples 1 to 5, hole filling + prepreg test substrates and hole filling + solder mask forming substrates were prepared by the following methods, and the following tests were performed. The method was examined for the occurrence of delamination X and internal crack Y shown in FIG.
The results are shown in Table 5.

Fabrication of hole filling + prepreg substrate:
After pickling a double-sided board with a thickness of 1.6 mm, plated through hole diameter of 0.25 mm, and through hole pitch of 1 mm (no pattern formation, 25 through holes) as a pretreatment, semi-automatic printing machine (manufactured by Ceria) The hole was printed with the thermosetting resin composition. Then, it was cured at 150 ° C. for 60 minutes in a hot air circulation type drying furnace. Then, the part which protruded from the board | substrate surface of hardened | cured material was grind | polished with the buff grinder (product made from Ishii Co., Ltd.) using high cut buff # 320 (made by Sumitomo 3M).
Next, after performing CZ-8100 (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.) And copper foil (GTS-MP-18 manufactured by Furukawa Circuit Foil Co., Ltd.) was press-molded with a press machine (KVHC-PRESS manufactured by Kitagawa Seiki Co., Ltd.).

Method for testing and evaluating hole filling + substrate for prepreg testing:
The test substrate press-molded as described above was immersed in a 288 ° C. solder solution for 10 seconds 5 times, and then allowed to cool to room temperature. The obtained test substrate was polished for cross-sectional observation and then observed with an optical microscope to evaluate the presence of delamination and internal cracks in the hole-filled cured product. About delamination, it evaluated by the ratio of the NG hole which the delamination generate | occur | produced with respect to the number of holes observed, and set it as (circle) when there is no NG hole. As for the internal cracks, the case where no crack was generated was marked with ◯, and the case where crack was generated was marked with x.

Fabrication of hole filling + solder mask test substrate:
After pickling a double-sided board with a thickness of 1.6 mm, plated through hole diameter of 0.25 mm, and through hole pitch of 1 mm (no pattern formation, 25 through holes) as a pretreatment, semi-automatic printing machine (manufactured by Ceria) The hole was printed with the thermosetting resin composition. Then, it was cured at 150 ° C. for 60 minutes in a hot air circulation type drying furnace. Then, the part which protruded from the board | substrate surface of hardened | cured material was grind | polished with the buff grinder (product made from Ishii Co., Ltd.) using high cut buff # 320 (made by Sumitomo 3M).
Next, after performing a polishing process with a buffing machine (manufactured by Ishii Co., Ltd.) using a high-cut buff # 800 (manufactured by Sumitomo 3M) as a pretreatment, a solder resist manufactured by Taiyo Ink Manufacturing Co., Ltd. is formed on both sides of the substrate. (PSR-4000SP08) is spray-coated and dried (preliminary curing) at 80 ° C. for 30 minutes in a hot-air circulating drying furnace, and then exposed at an exposure amount of 300 mJ / cm ^{2 using} an ORC exposure machine (HMW-680). Then, main curing was performed at 150 ° C. for 60 minutes in a hot air circulation type drying furnace.

Hole filling + solder mask test board testing and evaluation methods:
The test substrate prepared as described above was immersed in a 260 ° C. solder solution for 10 seconds 5 times, and then allowed to cool to room temperature. The obtained test substrate was observed visually and with an optical microscope to confirm the degree of peeling.

表５に示す結果から明らかなように、本発明の実施例１〜７の液状熱硬化性樹脂組成物を用いて穴埋め硬化物層を形成した場合、その上にプリプレグ及びソルダーマスクのいずれの外層絶縁層を形成した場合にも、デラミや内部クラックは発生しなかった。これに対し、２官能の液状エポキシ樹脂のみを含有する液状熱硬化性樹脂組成物を用いて穴埋め硬化物層を形成した比較例１、２の場合、デラミや内部クラックが発生した。また、３官能以上のエポキシ樹脂のみを含有する液状熱硬化性樹脂組成物を用いて穴埋め硬化物層を形成した比較例３〜５の場合、内部クラックが発生した。

As is clear from the results shown in Table 5, when the hole-filled cured product layer was formed using the liquid thermosetting resin compositions of Examples 1 to 7 of the present invention, any outer layer of the prepreg and the solder mask was formed thereon. Even when the insulating layer was formed, neither delamination nor internal cracks occurred. On the other hand, in the case of Comparative Examples 1 and 2 in which the hole-filled cured product layer was formed using the liquid thermosetting resin composition containing only the bifunctional liquid epoxy resin, delamination and internal cracks occurred. Moreover, in the case of Comparative Examples 3-5 which formed the hole-filling hardened | cured material layer using the liquid thermosetting resin composition containing only a trifunctional or more than epoxy resin, the internal crack generate | occur | produced.

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. It is a schematic sectional drawing which shows the state of the delamination of the outer peripheral insulating layer and the peripheral part of a hole insulating layer of a printed wiring board.

Explanation of symbols

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 X Delami Y Internal crack

Claims (3)

(A) An epoxy resin, (B) an epoxy resin curing agent, and (C) a thermosetting resin composition that contains an inorganic filler and is filled in a hole of a printed wiring board, the epoxy resin (A) Is a trifunctional or higher functional epoxy resin (A-2) dissolved in a liquid bifunctional epoxy resin (A-1), and the inorganic filler (C) does not contain silica and is a group IIa in the periodic table. of Ri Do from the salts of the elements, and, filling a thermosetting resin composition, wherein the mixing ratio is 45 to 85% by weight of the total composition of an inorganic filler (C). The epoxy resin (A) has a viscosity of 5 to 100 dPa · s at 25 ° C. after the trifunctional or higher functional epoxy resin (A-2) is dissolved in the liquid bifunctional epoxy resin (A-1). The thermosetting resin composition for hole filling according to claim 1.   A printed wiring board, wherein a hole of the printed wiring board is filled with a cured product of the thermosetting resin composition according to claim 1 or 2.

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