JP2013076002A - Thermosetting resin filler, and printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermosetting resin filler excellent in storage stability, capable of being stored for a long period at room temperature though it is of a one-component type; and to provide a printed wiring board highly reliable in solder heat resistance and electric properties by use of the filler, which can be filled in good workability in recesses between conductor circuits of the surface and in holes such as through-holes and via holes that have conductive layers formed on the inner walls.SOLUTION: The thermosetting resin filler contains an epoxy resin, an epoxy resin curing agent, and an inorganic filler, and is used for at least one of recesses of printed wiring boards and holes of double-sided boards or multilayer substrates, wherein the epoxy resin curing agent contains at least one selected from the group consisting of modified aliphatic polyamines and modified alicyclic polyamines. In a preferable embodiment, the epoxy resin curing agent further contains dicyanediamide.

Description

  The present invention relates to a thermosetting resin filler and a printed wiring board used for filling at least one of, for example, a recess between conductor circuits of a printed wiring board, a double-sided board or a through hole of a multilayer board, and a via hole. About.

  In recent years, with the miniaturization and high functionality of electronic devices, there is a demand for miniaturization of printed wiring board patterns, reduction of mounting area, and high density of component mounting. Therefore, a double-sided board provided with a through hole, or a multilayer board such as a build-up wiring board in which an insulating layer and a conductor circuit are sequentially formed on a core material and are connected in layers by via holes or the like are used. Then, area array mounting such as BGA (ball grid array) and LGA (land grid array) is performed.

  In such a printed wiring board, the concave portions between the conductor circuits on the surface, and the hole portions such as through holes and via holes in which a conductive layer is formed on the inner wall surface are filled with a thermosetting resin filler by a printing method or the like. The At this time, since the thermosetting resin filler is filled so as to slightly protrude from the hole portion, the protruding portion is flattened and removed by polishing after curing (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 10-75027

As described above, the thermosetting resin filler generally contains an epoxy resin as a thermosetting resin component, an imidazole curing agent as a curing agent, and an inorganic filler, as described in Patent Document 1 above. A thermosetting resin filler is used.
However, in the case of a combination of an epoxy resin and an imidazole curing agent, the storage stability at room temperature after mixing the above-described components is poor, and gelation (curing) occurs when stored at room temperature for a long time as a one-part resin composition. It becomes unusable. Therefore, it is necessary to store in a refrigerator or a freezer at a low temperature (for example, it can be stored at 10 ° C. for 3 to 5 months), and it takes time to store or ship the product, which causes problems in terms of workability and cost.

The present invention has been made in view of such circumstances, and its main purpose is to provide a thermosetting resin filler excellent in storage stability that can be stored for a long time at room temperature while being a one-pack type. It is to provide.
Furthermore, the object of the present invention is to use such a thermosetting resin filler so that the workability is improved in the recesses between the conductor circuits on the surface, and the holes such as through holes and via holes in which the conductive layer is formed on the inner wall surface. An object of the present invention is to provide a printed wiring board that can be filled well and has excellent solder heat resistance.

In order to achieve the above object, according to the present invention, at least one of a concave portion of a printed wiring board and a double-sided board or a hole of a multilayer board containing an epoxy resin, an epoxy resin curing agent, and an inorganic filler. Thermosetting resin filling, characterized in that it contains at least one selected from the group consisting of a modified aliphatic polyamine and a modified alicyclic polyamine as the epoxy resin curing agent Material is provided.
In a preferred embodiment, the epoxy resin curing agent further contains dicyandiamide.

  Furthermore, according to the present invention, there is provided a printed wiring board having a hole filled with a cured product of the thermosetting resin filler. The “hole” in this specification includes both a non-through hole such as a via hole of a printed wiring board and a through hole such as a through hole.

Since the thermosetting resin filler of the present invention contains at least one selected from the group consisting of a modified aliphatic polyamine and a modified alicyclic polyamine as an epoxy resin curing agent as described above, it is a one-pack type. However, it can be stored for a long time at room temperature, for example, it can be stored at 25 ° C. for 180 days or more without gelation, and it has excellent storage stability, so that its handling is convenient. The “room temperature” here is synonymous with the temperature range in the work environment, and is generally set to a temperature range of about 15 ° C. or more and 30 ° C. or less, for example.
In addition, in a preferred embodiment containing another amine-based curing agent, particularly dicyandiamide, in combination with the polyamine as an epoxy resin curing agent, the viscosity increase rate during storage at room temperature can be suppressed, so that the Can be stored, and the amount of the polyamine used can be reduced.
Furthermore, by using the thermosetting resin filler of the present invention, it is possible to fill the recesses between the conductor circuits on the surface, and the holes such as through holes and via holes in which a conductive layer is formed on the inner wall surface with good workability. A printed wiring board having excellent heat resistance can be provided.

It is a schematic sectional drawing which shows the state of the peripheral part of a hole insulating layer of an evaluation board in an example and a comparative example, and an outer insulating layer (solder resist layer).

  As described above, the thermosetting resin filler of the present invention contains an epoxy resin, an epoxy resin curing agent, and an inorganic filler, and at least any one of a concave portion of a printed wiring board and a double-sided board or a hole of a multilayer board. It is a resin filler used for either, and is characterized by containing at least one selected from the group consisting of a modified aliphatic polyamine and a modified alicyclic polyamine as the epoxy resin curing agent.

  According to the study by the present inventors, these modified aliphatic polyamines and modified alicyclic polyamines act as curing agents for epoxy resins, and when mixed with epoxy resins, can be used as a one-pack type resin composition after mixing. Moreover, it can be stored for a long time at room temperature (long pot life) even though it is a one-pack type. For example, it can be stored at 25 ° C. without gelation for 180 days or longer, and has excellent storage stability at room temperature. I found out. In addition, compared with other amine-based curing agents such as dicyandiamide and its derivatives, and amine compounds such as boron trifluoride-amine complex, the curing reaction starts at a relatively low temperature, and has high heat resistance and water resistance. It was found that can be manufactured.

  Further, according to the study by the present inventors, as an epoxy resin curing agent, in combination with at least one selected from the group consisting of the above-mentioned modified aliphatic polyamine and modified alicyclic polyamine, further amine compounds, particularly dicyandiamide In the case of a thermosetting resin filler that is used in combination, the viscosity increase rate during storage at room temperature can be suppressed, so it can be stored for a longer period of time, and it can be cured with a small amount of polyamine. It has been found that the amount of polyamine and modified alicyclic polyamine used can be reduced.

  The present invention has been made based on the findings as described above. By using the thermosetting resin filler of the present invention as described above, it is possible to fill the recesses between the conductor circuits on the surface, and holes such as through holes and via holes in which a conductive layer is formed on the inner wall surface with good workability. Highly reliable printed wiring boards such as solder heat resistance and electrical characteristics can be manufactured. Hereinafter, each component of the thermosetting resin filler of the present invention will be described.

  As an epoxy resin used for the thermosetting resin filler of this invention, what has a 2 or more epoxy group in 1 molecule should just be used, and a well-known thing can be used. For example, bisphenol A type epoxy resin, bisphenol S type epoxy resin, dinaphthol type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, alicyclic epoxy resin, polyethylene glycol or polypropylene glycol diester Glycidyl ether, polytetramethylene glycol diglycidyl ether, glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, phenyl-1,3-diglycidyl ether, biphenyl-4,4′-diglycidyl ether, 1,6-hexanediol Diglycidyl ether, diglycidyl ether of ethylene glycol or propylene glycol, sorbitol polyglycidyl ether, Compounds having two or more epoxy groups in one molecule such as rubitan polyglycidyl ether, tris (2,3-epoxypropyl) isocyanurate, triglycidyltris (2-hydroxyethyl) isocyanurate, tetraglycidylaminodiphenylmethane Amine type epoxy resins such as tetraglycidyl metaxylylene diamine, triglycidyl paraaminophenol, diglycidyl aniline, diglycidyl orthotoluidine, etc., and epoxy resins that are liquid at room temperature, for example, 20 ° C. are preferred.

  These commercially available products include bisphenol A liquid epoxy resin, Mitsubishi Chemical Corporation jER828, bisphenol F liquid epoxy resin, Mitsubishi Chemical Corporation jER807, amine liquid epoxy (paraaminophenol liquid epoxy), Mitsubishi Chemical. Examples include jER-630 manufactured by Sumitomo Chemical Co., Ltd. and ELM-100 manufactured by Sumitomo Chemical.

Among these, when the paste has a low viscosity, the amount of the inorganic filler can be increased, and a liquid epoxy resin containing a benzene ring which is a heat-resistant skeleton is preferable.
The epoxy resins as described above can be used alone or in combination of two or more.

  The epoxy resin curing agent is used for curing the epoxy resin, and in the present invention, at least one selected from the group consisting of a modified aliphatic polyamine and a modified alicyclic polyamine is used. These modified aliphatic polyamines and modified alicyclic polyamines can be used alone or in combination of two or more. These modified aliphatic polyamines and modified alicyclic polyamines generally contain a small amount of unmodified amine, but can be used without any problem.

  When a modified aliphatic polyamine curing agent or a modified alicyclic polyamine curing agent is used as the epoxy resin curing agent, as described above, it can be used after mixing pot life (epoxy resin and curing agent). Approximate time) becomes longer, and toxicity and skin irritation are less, and workability is improved.

  The polyamine-based curing agent is an adduct compound of an aliphatic polyamine such as an alkylene diamine having 2 to 6 carbon atoms, a polyalkylene polyamine having 2 to 6 carbon atoms, or an aromatic ring-containing aliphatic polyamine having 8 to 15 carbon atoms. Or an adduct compound of an alicyclic polyamine such as isophoronediamine or 1,3-bis (aminomethyl) cyclohexane, or a mixture of the adduct compound of the aliphatic polyamine and the adduct compound of the alicyclic polyamine as a main component. Those are preferred. In particular, a curing agent mainly composed of an adduct compound of xylylenediamine or isophoronediamine is preferable.

  As the above-mentioned aliphatic polyamine adduct compound, an aliphatic polyamine obtained by addition reaction of aryl glycidyl ether (particularly phenyl glycidyl ether or tolyl glycidyl ether) or alkyl glycidyl ether is preferable. The alicyclic polyamine adduct compound is preferably a compound obtained by subjecting the alicyclic polyamine to an addition reaction of n-butyl glycidyl ether, bisphenol A diglycidyl ether, or the like.

Aliphatic polyamines include alkylenediamines having 2 to 6 carbon atoms such as ethylenediamine and propylenediamine, polyalkylene polyamines having 2 to 6 carbon atoms such as diethylenetriamine and triethylenetriamine, and aromatics having 8 to 15 carbon atoms such as xylylenediamine. Examples thereof include ring-containing aliphatic polyamines. Examples of commercially available aliphatic polyamines include FXE-1000 or FXR-1020, Fujicure FXR-1030, Fujicure FXR-1080, FXR-1090M2 (Fuji Kasei Kogyo Co., Ltd.), Ancamine (registered trademark) 2089K, Sanmide ( (Registered trademark) P-117, Sanmide X-4150, Ancamine 2422, Thurwet R, Sunmide TX-3000, Sunmide A-100 (manufactured by Air Products Japan), and the like.
Examples of alicyclic polyamines include isophorone diamine, 1,3-bis (aminomethyl) cyclohexane, bis (4-aminocyclohexyl) methane, norbornene diamine, 1,2-diaminocyclohexane, and laromine. Examples of commercially available alicyclic polyamines include Ancamine 1618, Ancamine 2074, Ancamine 2596, Ancamine 2199, Sanmide IM-544, Sanmide I-544, Ancamine 2075, Ancamine 2280, Ancamine 1934, Ancamine 2228 (produced by Air Products Japan). ), Daitokural (registered trademark) F-5197, Daitokural B-1616 (manufactured by Daito Sangyo Co., Ltd.), Fuji Cure FXD-821, Fuji Cure 4233 (manufactured by Fuji Kasei Kogyo Co., Ltd.), jER Cure (registered trademark) 113 (Mitsubishi Chemical Corporation) Product), Lalomin (registered trademark) C-260 (manufactured by BASF) and the like.

  The blending ratio of the modified aliphatic polyamine or modified alicyclic polyamine as described above is 0.1 parts by mass or more and 30 parts by mass or less, preferably 1 part by mass or more and 20 parts by mass with respect to 100 parts by mass of the epoxy resin. The following are appropriate. When the blending ratio of the modified aliphatic polyamine or the modified alicyclic polyamine is less than 0.1 parts by mass with respect to 100 parts by mass of the epoxy resin, generally the precuring speed of the epoxy resin composition becomes slow, and voids are formed in the cured product. It is not preferable because it tends to cause residue and cracks. On the other hand, when the blending ratio exceeds 30 parts by mass, the desired effect of improving storage stability at room temperature becomes difficult to obtain.

  In addition, the thermosetting resin filler of the present invention, as an epoxy resin curing agent, in combination with at least one selected from the group consisting of the modified aliphatic polyamine and the modified alicyclic polyamine, further other amine compounds, It is particularly preferable to use dicyandiamide in combination. As a result, the viscosity increase rate at the time of storage of the thermosetting resin filler at room temperature is suppressed, so that it can be stored for a longer period of time, and it can be cured even with a small amount of polyamine. The amount of the modified alicyclic polyamine used can be reduced. 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 organic acid salts and epoxy adducts thereof have adhesiveness with copper and rust prevention, and as a curing agent for epoxy resin. Since it can work and contribute to prevention of copper discoloration of the printed wiring board, it can be suitably used.

  The mixing ratio of such an amine curing agent is usually a normal ratio. For example, 0.1 to 10 parts by mass is appropriate for 100 parts by mass of the epoxy resin.

  In the thermosetting resin filler of the present invention, the inorganic filler is used for stress relaxation due to curing shrinkage and adjustment of the linear expansion coefficient. As such an inorganic filler, the well-known inorganic filler used for a normal resin composition can be used. Specifically, nonmetals such as silica, barium sulfate, calcium carbonate, silicon nitride, aluminum nitride, boron nitride, alumina, magnesium oxide, aluminum hydroxide, magnesium hydroxide, titanium oxide, mica, talc, organic bentonite, etc. Examples of the filler include metal fillers such as copper, gold, silver, palladium, and silicone. These can be used alone or in combination of two or more.

  Among these inorganic fillers, silica and calcium carbonate excellent in low hygroscopicity and low volume expansibility are preferably used. Silica may be either amorphous or crystalline, or a mixture thereof. In particular, amorphous (fused) silica is preferred. The calcium carbonate may be either natural heavy calcium carbonate or synthetic precipitated calcium carbonate.

  Examples of the shape of such an inorganic filler include a spherical shape, a needle shape, a plate shape, a scale shape, a hollow shape, an indefinite shape, a hexagonal shape, a cubic shape, and a flake shape. preferable.

  Moreover, the average particle diameter of these inorganic fillers is 0.1 μm or more and 25 μm or less, preferably 0.1 μm or more and 15 μm or less. When the average particle diameter is less than 0.1 μm, the specific surface area is large, and dispersion failure is likely to occur due to the influence of the aggregating action between the fillers, and it is difficult to increase the filling amount of the filler. On the other hand, when the thickness exceeds 25 μm, there is a problem that the filling property to the hole of the printed wiring board is deteriorated and the smoothness is deteriorated when the conductor layer is formed in the filled portion. More preferably, they are 1 micrometer or more and 10 micrometers or less.

  The blending ratio of such an inorganic filler is suitably 40% by mass or more and 90% by mass or less, preferably 40% by mass or more and 80% by mass or less, with respect to the total amount of the thermosetting resin filler. If it is less than 40% by mass, the resulting cured product will have too much thermal expansion, and it will be difficult to obtain sufficient abrasiveness and adhesion. On the other hand, when it exceeds 90% by mass, it becomes difficult to form a paste, and it becomes difficult to obtain good printability and hole filling. More preferably, it is 50 mass% or more and 75 mass% or less.

  To the thermosetting resin filler of the present invention, a filler treated with a fatty acid to impart thixotropy, or an amorphous filler such as organic bentonite and talc can be added.

The fatty acid has the general formula: (R ¹ COO) n-R ² (substituent R ¹ is a hydrocarbon having 5 or more carbon atoms, substituent R ² is hydrogen, metal alkoxide, or metal, and n is 1 or more. 4 or less) can be used. The fatty acid can exhibit an effect of imparting thixotropy when the substituent R ¹ has 5 or more carbon atoms. More preferably, n is 7 or more.

As a fatty acid, the unsaturated fatty acid which has a double bond or a triple bond in a carbon chain may be sufficient, and the saturated fatty acid which does not contain them may be sufficient. For example, stearic acid (the number of carbon atoms and the number of unsaturated bonds and the value in parentheses is a numerical expression depending on the position. 18: 0), hexanoic acid (6: 0), oleic acid (18: 1 (9)), icosane Examples include acid (20: 0), docosanoic acid (22: 0), and melicic acid (30: 0). These fatty acid substituents R ¹ preferably have 5 to 30 carbon atoms. More preferably, it has 5 to 20 carbon atoms. In addition, for example, metal alkoxides in which the substituent R ² is a titanate-based substituent capped with an alkoxyl group, etc., having a skeleton having a long (5 or more carbon atoms) fatty chain with a coupling agent structure It may be. For example, trade name KR-TTS (manufactured by Ajinomoto Fine Techno Co., Ltd.) can be used. In addition, metal soaps such as aluminum stearate and barium stearate (each manufactured by Kawamura Kasei Kogyo Co., Ltd.) can be used. Examples of other metal soap elements include Ca, Zn, Li, Mg, and Na.

  The proportion of such fatty acid is suitably 0.1 to 2 parts by mass with respect to 100 parts by mass of the inorganic filler. If it is less than 0.1 parts by mass, sufficient thixotropy cannot be imparted. On the other hand, if it exceeds 2 parts by mass, the apparent viscosity of the thermosetting resin filler becomes too high, resulting in holes in the printed wiring board. The embeddability in the part is reduced. In addition, after filling and curing in the hole portion, bubbles remain in the hole portion, so that the defoaming property is deteriorated, and voids and cracks are likely to occur. More preferably, they are 0.1 mass part or more and 1 mass part or less.

  A fatty acid may be mix | blended by using the inorganic filler surface-treated with the fatty acid previously, and it becomes possible to provide thixotropy to a thermosetting resin filler more effectively. In this case, the blending ratio of the fatty acid can be reduced as compared with the case where the untreated filler is used. When all the inorganic fillers are used as the fatty acid-treated filler, the blending ratio of the fatty acid is 0. It is preferable to be 1 part by mass or more and 1 part by mass or less.

  In the thermosetting resin filler of the present invention, a silane coupling agent can be further used. By mix | blending a silane coupling agent, it becomes possible to improve the adhesiveness of an inorganic filler and an epoxy resin, and to suppress generation | occurrence | production of the crack in the hardened | cured material.

  Examples of the silane coupling agent include epoxy silane, vinyl silane, imidazole silane, mercapto silane, methacryloxy silane, amino silane, styryl silane, isocyanate silane, sulfide silane, ureido silane, and the like. Moreover, a silane coupling agent may be mix | blended by using the inorganic filler surface-treated with the silane coupling agent previously.

  The mixing ratio of such a silane coupling agent is preferably 0.05 parts by mass or more and 2.5 parts by mass or less with respect to 100 parts by mass of the inorganic filler. If it is less than 0.05 parts by mass, sufficient adhesion cannot be obtained, and cracks are likely to occur. On the other hand, if it exceeds 2.5 parts by mass, after filling and curing the thermosetting resin filler in the hole of the printed wiring board, bubbles remain in the hole and the defoaming property deteriorates, causing voids and cracks. Is likely to occur.

  The thermosetting resin filler of the present invention does not necessarily use a diluting solvent when a liquid epoxy resin is used at room temperature, but a small amount of diluting solvent is added to adjust the viscosity of the composition. Also good. Examples of the diluent solvent include ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene and tetramethylbenzene; methyl cellosolve, butyl cellosolve, methyl carbitol, ethyl carbitol, butyl carbitol, propylene glycol monomethyl ether , Glycol ethers such as dipropylene glycol monoethyl ether and triethylene glycol monoethyl ether; esters such as ethyl acetate, butyl acetate, and acetates of the above glycol ethers; ethanol, propanol, ethylene glycol, propylene glycol, etc. Alcohols; aliphatic hydrocarbons such as octane and decane; petroleum oils such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha Organic solvents such as solvents. These can be used alone or in combination of two or more.

  The blending ratio of the dilution solvent is 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less of the total amount of the thermosetting resin filler. If the blending ratio of the dilution solvent exceeds 10% by mass, bubbles and cracks are likely to occur in the hole insulating layer after curing due to the effect of evaporation of volatile components during curing. Therefore, a solvent-free thermosetting resin filler is particularly desirable.

  If necessary, the thermosetting resin filler of the present invention may be blended with an oxazine compound having an oxazine ring obtained by reacting a phenol compound, formalin and a primary amine. By containing the oxazine compound, after curing the thermosetting resin filler filled in the hole of the printed wiring board, when performing electroless plating on the formed cured product, by using an aqueous potassium permanganate solution, etc. Roughening of the cured product can be facilitated, and the peel strength with the plating can be improved.

  Further, known colorants such as phthalocyanine blue, phthalocyanine green, disazo yellow, titanium oxide, carbon black, and naphthalene black, which are used in ordinary resist inks for screen printing, may be added.

  In order to impart storage stability during storage, known thermal polymerization inhibitors such as hydroquinone, hydroquinone monomethyl ether, tert-butylcatechol, pyrogallol, and phenothiazine, and clay, kaolin, Known thickeners such as organic bentonite and montmorillonite, and thixotropic agents can be added. In addition, known additives such as antifoaming agents such as silicones, fluorines, and polymers, leveling agents, and adhesion-imparting agents such as imidazoles, thiazoles, triazoles, and silane coupling agents are blended. be able to.

  In the obtained thermosetting resin filler, the viscosity measured by a rotary viscometer is preferably 200 dPa · Sec or more and 1000 dPa · Sec or less at a 30 Sec value of 25 ° C. and 5 rpm. If it is less than 200 dPa · Sec, it is difficult to maintain the shape, and sagging occurs. On the other hand, when it exceeds 1000 dPa · Sec, the embedding property in the hole of the printed wiring board is lowered. More preferably, it is 200 dPa · Sec or more and 800 dPa · Sec or less.

  The viscosity is measured with a cone plate viscometer composed of a cone rotor (conical rotor) and a plate described in JIS Z 8803, for example, TV-30 type (manufactured by Toki Sangyo, rotor 3 ° × R9.7). The

  The thermosetting resin filler of the present invention is a printed wiring in which a conductive layer such as copper is formed on the surface and the wall surface of the hole using a known patterning method such as a screen printing method, a roll coating method, or a die coating method. Fill the hole in the plate. At this time, it is completely filled so as to slightly protrude from the hole. And a printed wiring board with which the hole part was filled with the thermosetting resin filler is heated at 150 degreeC for about 60 minutes, for example, a thermosetting resin filler is hardened and hardened | cured material is formed. Preferably, it is preliminarily cured by heating at about 90 ° C. or higher and 130 ° C. or lower for about 30 minutes or longer and 90 minutes or shorter. 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. Thereafter, the film is heated again at about 140 ° C. or higher and 180 ° C. or lower for about 30 minutes or longer and 90 minutes or shorter to be fully cured (finish curing). At this time, the cured product hardly expands or contracts due to low expansibility, and becomes a final cured product excellent in dimensional stability, low moisture absorption, adhesion, electrical insulation and the like. The hardness of the pre-cured product can be controlled by changing the pre-curing heating time and heating temperature.

  Then, unnecessary portions of the cured product protruding from the surface of the printed wiring board are removed by a known physical polishing method and planarized, and then the conductive layer on the surface is patterned into a predetermined pattern to form a predetermined circuit pattern. The In addition, after performing surface roughening of hardened | cured material with potassium permanganate aqueous solution etc. as needed, you may form a conductive layer on hardened | cured material by electroless plating etc.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, it cannot be overemphasized that this invention is not limited to the following Example. In the following description, “parts” and “%” are based on mass unless otherwise specified.

<Preparation of paste>
The components shown in Table 1 were premixed with a stirrer at each blending ratio (parts by mass), then dispersed with a three-roll mill, and Examples 1 to 8, which are thermosetting resin fillers, And the paste of Comparative Examples 1 and 2 was prepared.

<Performance evaluation>
Each paste obtained as described above was evaluated for performance as listed below. The results are summarized in Table 2.

viscosity:
A 0.2 ml sample of each paste was collected and measured using a cone plate viscometer (TV-30, manufactured by Toki Sangyo Co., Ltd.) at 25 ° C. and at a rotation speed of 5 rpm / min.

Printability (fillability):
As shown in FIG. 1, each paste was filled in a through hole under the following printing conditions by a screen printing method on a glass epoxy substrate 1 having a through hole 2 on which a conductor layer 3 was formed by panel plating. After filling, it was placed in a hot air circulation drying oven and pre-cured at 130 ° C. for 45 minutes to obtain an evaluation substrate. Fillability was evaluated based on the degree of filling of the cured product 4 filled in the through holes of the evaluation substrate. The evaluation criteria are as follows.
○: Completely filled.
×: The bottom of the through hole is not filled (insufficient filling).
<Printing conditions>
Squeegee: Squeegee thickness 20mm, hardness 70 °, oblique polishing: 23 °,
Plate: PET100 mesh bias plate,
Printing pressure: 60 kgf / cm ² , Squeegee speed 5 cm / Sec,
Squeegee angle: 80 °

Gelation time:
Measured with a gelling tester in accordance with the hot plate method of JIS C 2105, and the torque when rotating the rotating rod in 0.5 ml of the sample held at the measurement temperature (150 ° C.) is 30% of the maximum torque. The time to reach is the gel time. The measurement time was 30 minutes, and no more gelation was determined.

Cross-sectional state after curing:
Each paste is filled into a through-hole using a semi-automatic printing machine on a substrate having a thickness of 1.6 mm / through-hole diameter of 0.25 mm / pitch of 1 mm, and 130 ° C. × 45 minutes + 150 ° C. × in a hot air circulating drying oven. It was cured by heating for 60 minutes. After polishing the obtained evaluation substrate for cross-sectional observation, it is observed with an optical microscope, and cracks (internal crack Y) and voids as shown in FIG. 1 are not generated in the cross section of the cured product in the through-hole portion. I confirmed. The judgment criteria are as follows.
○: No abnormality.
X: Cracks and voids are generated.

Solder heat resistance:
As shown in FIG. 1, each paste is filled into the through-hole 2 using a semi-automatic printing machine on a substrate having a thickness of 1.6 mm / through-hole diameter of 0.25 mm / pitch of 1 mm, and the hot-air circulating drying oven is used. And cured by heating at 130 ° C. for 45 minutes + 150 ° C. for 60 minutes. Further, a solder resist was applied to the upper layer, and exposure, development and curing were performed under standard conditions to form a solder resist layer 5 to produce an evaluation substrate.
This evaluation board was immersed in a 260 ° C. solder solution for 10 seconds 5 times, and then allowed to cool to room temperature. Observation of the obtained evaluation substrate with a visual and optical microscope, delamination X (the periphery of the through hole is lifted during solder leveling) around the hole insulating layer 4 (cured material in the through hole), Hereinafter, it was confirmed whether or not there was no occurrence of “deami”. The judgment criteria are as follows.
○: No delamination occurred.
Δ: A slight delamination state was observed around the hole insulating layer.
X: Delamination having a considerable width was generated in a ring shape around the hole insulating layer.

As shown in Table 2, in Examples 1 to 8, after storage at 25 ° C. for 180 days, it can be stored without gelation, has excellent storage stability at room temperature, and exhibits good filling properties. Also, there was no problem in solder heat resistance. In particular, in Examples 5 and 6, since dicyandiamide was further contained as a curing agent for epoxy resin in combination with a modified aliphatic polyamine, the viscosity increase rate after storage for 180 days at 25 ° C. was suppressed.
On the other hand, Comparative Example 1 using only dicyandiamide as an epoxy resin curing agent could not be evaluated because it was not cured by preheating. In addition, in the case of Comparative Example 2 using an imidazole derivative as an epoxy resin curing agent, storage stability at room temperature is poor, gelation occurs after storage for 180 days at 25 ° C., and cannot be evaluated because it cannot be filled into the through-hole part. It was.

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 Through hole 3 Conductor layer 4 Hole insulating layer (hardened | cured material of a thermosetting resin filler)
5 Solder resist layer X Delami Y crack

Claims (3)

  An epoxy resin, an epoxy resin curing agent, and an inorganic filler, a resin filler used for at least one of a recessed portion of a printed wiring board and a double-sided board or a hole of a multilayer board, the epoxy resin curing A thermosetting resin filler comprising at least one selected from the group consisting of a modified aliphatic polyamine and a modified alicyclic polyamine as an agent.   The thermosetting resin filler according to claim 1, further comprising dicyandiamide as the epoxy resin curing agent.   A printed wiring board having a hole filled with a cured product of the thermosetting resin filler according to claim 1.

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