JP2019112610A - Thermosetting resin filler, cured product of the same, and multilayer printed wiring board - Google Patents

Abstract

To provide a thermosetting resin filler which has high adhesion to both a conductive part and an insulating part, and is excellent in electric insulation property.SOLUTION: A thermosetting resin filler is used for embedding a multilayer printed wiring board which includes a plurality of wiring layers laminated in a thickness direction through an insulating layer, a recess having a through hole or a bottom part formed in a thickness direction of the plurality of wiring layers, and a conductive part and an insulating part on the inner wall of the through hole or the recess, and contains an epoxy resin, an epoxy resin curing agent and an inorganic filler, in which the epoxy resin contains an epoxy resin having tertiary amine and an epoxy resin having a bisphenol type skeleton.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a thermosetting resin filler, and more specifically, a plurality of wiring layers stacked in a thickness direction via an insulating layer, and a through hole formed in the thickness direction of the plurality of wiring layers. Or a thermosetting resin filler that can be suitably used for filling a hole in a multilayer printed wiring board provided with a recess having a bottom and a conductive portion and an insulating portion on the inner wall of the through hole or the recess; On the board.

  With the miniaturization and high performance of electronic devices, miniaturization of patterns of printed wiring boards, reduction of mounting area, and high density of component mounting are required. Therefore, an insulating layer and a conductor circuit are sequentially formed on a double-sided board provided with a through hole forming an interlayer connection for electrically connecting different wiring layers, that is, a through hole, via holes and the like. A multilayer substrate such as an interlayer connection and a multilayer buildup wiring board is used. Then, area array mounting such as BGA (ball grid array), LGA (land grid array), etc. is performed.

  In such printed wiring boards, thermosetting resin filler materials are used to fill in the recesses between the conductor circuits on the surface, and the through holes with via holes on which the wiring layer is formed on the inner wall, and via holes. Is common. As a thermosetting resin filler, a thermosetting resin filler containing an epoxy resin as a thermosetting resin component, an epoxy resin curing agent, and an inorganic filler is generally used. For example, Patent Document 1 proposes a thermosetting resin filler containing a liquid epoxy resin, a liquid phenol resin, a curing catalyst, and two types of fillers as a thermosetting resin filler excellent in filling property and the like. It is done.

  By the way, in recent years, along with the advancement of the function of printed wiring boards, it is possible to improve frequency characteristics by removing an extra portion which is not related to the conduction between layers in the plating film of the wall surface of through holes and via holes. It is For example, Patent Document 2 proposes a printed wiring board provided with a hole portion in which a through hole or a via hole is excavated halfway by using a method called a back drilling method. Patent Document 3 also proposes providing a plating film only on a part of the wall surface of the through hole or the via hole.

JP, 2001-019834, A Japanese Patent Publication No. 2007-509487 JP 2012-256636 A

In the through holes and the like of the printed wiring board as described in Patent Documents 2 and 3, the plating film or the like is not formed on a part of the inner wall surface of the hole, or a part of the plating film is removed. There are places where the insulating layer of the printed wiring board is exposed. When a thermosetting resin filler is filled in a hole such as a through hole having such a structure to fill the hole, the filler in contact with the inner wall surface of the hole has a portion in contact with the plating film and a portion in contact with the insulating layer. It will be done.
The insulating layer of the printed wiring board is formed of a resin material such as epoxy resin, and the plating film is formed of a metal material such as copper. Therefore, when filling is performed using a filler, the adhesion of the filler differs depending on the material between the insulating layer and the plating film, and as a result, when holes such as through holes having the above structure are filled. The adhesion between the inner wall surface and the filler differs depending on the location of the inner wall surface of the hole, and in some cases, the filler may peel off. This tendency is particularly remarkable when the inner wall of the hole has a conductive portion and an insulating portion as in Patent Documents 2 and 3. Further, by providing the insulating portion as in Patent Documents 2 and 3 as well, the electrical insulating property is also required. Thus, a thermosetting resin filler suitable for filling a hole such as a through hole having the above-mentioned structure while maintaining the electrical insulating property which is the original purpose of the filler has not been found yet.

  Therefore, an object of the present invention is to provide a thermosetting resin filler which has high adhesion to both the conductive part and the insulating part and is also excellent in electrical insulation. In particular, a plurality of wiring layers stacked in the thickness direction via an insulating layer, a recess having a through hole or a bottom formed in the thickness direction of the plurality of wiring layers, and an inner wall of the through hole or the recess It is an object of the present invention to provide a thermosetting resin filler excellent in the above characteristics when used for filling a hole in a multilayer printed wiring board provided with a conductive portion and an insulating portion. Another object of the present invention is to provide a cured product formed using the thermosetting resin filler and a multilayer printed wiring board having the cured product.

  As a result of intensive studies, the present inventors have found that in the multilayer printed wiring board as described above, the filling state of the filler to the interface between the conductive part and the insulating part is extremely bad. That is, a gap is easily generated at the interface between the insulating portion and the conductive portion due to the difficulty in maintaining the filled state, specifically, after the filler is filled in the hole or the recess, a gap is likely to occur. It was found that the adhesion of the filler material was deteriorated due to the influence of Furthermore, the present inventors have found that, in a thermosetting resin filler containing an epoxy resin, an epoxy resin curing agent, and an inorganic filler, the conductive portion and the insulation can be obtained by using an epoxy resin having a specific functional group as the epoxy resin. We obtained the finding that a filler with high adhesion to both parts and excellent electrical insulation could be realized.

  Furthermore, the present inventors have found that adhesion to both the conductive portion and the insulating portion is high by using two specific epoxy resins in combination as the epoxy resin, and the conductivity of the inner wall surface of the concave portion and the hole portion It has been found that even in the case of filling a hole in a multilayer printed wiring board having a structure in which an insulating portion is exposed in part of the portion, a filler excellent in electrical insulation can be realized. The present invention is based on such findings.

That is, the thermosetting resin filler of the present invention has a plurality of wiring layers stacked in the thickness direction via the insulating layer, and a through hole or a bottom formed in the thickness direction of the plurality of wiring layers. It is a thermosetting resin filler used for hole filling of a multilayer printed wiring board provided with a recess and a conductive part and an insulating part on the inner wall of the through hole or the recess,
Containing epoxy resin, epoxy resin curing agent and inorganic filler,
The epoxy resin includes an epoxy resin having a tertiary amine and an epoxy resin having a bisphenol type skeleton.

  In an embodiment of the present invention, the epoxy resin having the tertiary amine and the epoxy resin having the bisphenol type skeleton may be contained in a ratio of 20:80 to 90:10 on a mass basis.

  In the embodiment of the present invention, the epoxy resin curing agent may contain at least one selected from the group consisting of an amine curing agent and an imidazole curing agent.

  In the embodiment of the present invention, the inorganic filler may be at least one selected from the group consisting of calcium carbonate, silica, barium sulfate and aluminum oxide.

  In the embodiment of the present invention, the average particle diameter of the inorganic filler may be 0.1 μm to 15 μm.

  In the embodiment of the present invention, the conductive portion of the multilayer printed wiring board may be made of copper.

  In the embodiment of the present invention, the epoxy resin having a bisphenol skeleton may have at least one skeleton selected from the group consisting of bisphenol A, bisphenol F and bisphenol E. Good.

  In the embodiment of the present invention, the epoxy resin having a bisphenol skeleton may include two types of epoxy resin having a bisphenol A skeleton and epoxy resin having a bisphenol F skeleton.

  Furthermore, the cured product according to another aspect of the present invention is a cured product of the above-mentioned thermosetting resin filler.

  A multilayer printed wiring board according to another aspect of the present invention has the above-mentioned cured product.

  According to the present invention, it is possible to realize a filler which has high adhesion to both the conductive part and the insulating part and is also excellent in electrical insulation. In particular, a plurality of wiring layers stacked in the thickness direction via an insulating layer, a recess having a through hole or a bottom formed in the thickness direction of the plurality of wiring layers, and an inner wall of the through hole or the recess It can be realized when used in the hole filling of a multilayer printed wiring board provided with a conductive portion and an insulating portion. Moreover, according to the other form of this invention, the multilayer printed wiring board which has the hardened | cured material formed using the said thermosetting resin filler and the said hardened | cured material can be implement | achieved.

It is the schematic sectional drawing which showed one Embodiment of the printed wiring board by which the hole was filled with the thermosetting resin filler. It is the schematic sectional drawing which showed another embodiment of the printed wiring board by which the hole was filled with the thermosetting resin filler. It is the schematic sectional drawing which showed another embodiment of the printed wiring board by which the hole was filled with the thermosetting resin filler.

  First, a printed wiring board to which the thermosetting resin filler of the present invention is applied will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing an embodiment of a multilayer printed wiring board which is filled with a thermosetting resin filler. In the multilayer printed wiring board 1 to which the thermosetting resin filler is applied, a plurality of wiring layers 20a, 20b, 20c, 20d made of a plating film or the like are stacked in the thickness direction via the insulating layer 10 The through holes 40 (holes filled with a thermosetting resin filler) formed in the thickness direction of the wiring layers 20a, 20b, 20c, and 20d are provided. At one end of the hole portion of the through hole 40, a conductive portion 20e extending from the wiring layer 20d is formed on the inner wall of the through hole 40. At the other end of the hole of the through hole 40, the inner diameter of the through hole is enlarged to remove a part of the wiring layer 20a after the formation of the conductive portion 20e, and the insulating layer is exposed on the inner wall of the hole. Thus, the insulating portion 10a is formed. That is, the inner wall of the through hole 40 (hole) is in a state provided with the conductive portion 20e and the insulating portion 10a. By providing the conductive portion 20e and the insulating portion 10a on the inner wall of the through hole 40 (hole) as described above, a portion not electrically connected is formed, and as a result, the transmission efficiency is improved. A thermosetting resin filler is filled in the through holes 40 (holes) having such a cross-sectional shape, and the holes are filled by heat curing. In the present embodiment, the insulating layer refers to a layer that supports the wiring layer while insulating different wiring layers, and the wiring layer refers to a layer that is electrically conducted by a circuit. In addition, an insulating portion refers to a portion which does not electrically connect each layer, and may include the above-described insulating layer. On the other hand, the conductive portion refers to a portion for electrically conducting each wiring layer, such as a plating film, and may include the above-described wiring layer. Furthermore, the through hole means a hole provided so as to penetrate the entire thickness direction of the multilayer printed wiring board. The through hole may be formed in the thickness direction of the wiring layer, and more specifically, may not be formed parallel to the wiring layer. In the present embodiment, although the wiring layer extending to the wall surface of the through hole is the conductive portion, the conductive portion is also referred to when a portion of the wiring layer is exposed to the wall surface of the through hole. In addition to the case where the wiring layer is formed by extending to the wall surface, the conductive portion is also referred to as a conductive portion also when the conductive film is formed on the wall surface by plating or the like.

  In another embodiment of the present invention, the wiring layer 30a and 30d extend as far as the inner wall of the through hole 40 (hole) as shown in FIG. Forming a conductive portion 30e, removing a portion of the conductive portion to expose the insulating layer, and forming a multilayer printed wiring board having a structure in which the conductive portion 30e and the insulating portion 10a are provided. It may be. In the present embodiment, although the wiring layer extending to the wall surface of the through hole is the conductive portion, the conductive portion is also referred to when a portion of the wiring layer is exposed to the wall surface of the through hole. In addition to the case where the wiring layer is formed by extending to the wall surface, the conductive portion is also referred to as a conductive portion also when the conductive film is formed on the wall surface by plating or the like.

  Further, in another embodiment of the present invention, it is not limited to the through hole that the hole filling is performed using the thermosetting resin filler, and for example, a multilayer printed wiring board having a recess 70 as shown in FIG. It may be two. In the multilayer printed wiring board 2, the wiring layer 50a provided on one surface of the insulating layer 10 extends to the wall surface and the bottom 60 of the recess 70 to form the conductive portion 50d, and the opening side of the recess 70 is the conductive portion 50d. The inner diameter of the recess is enlarged so as to remove a part of the wiring layer 50a after formation, and the insulating portion is exposed on the inner wall of the hole to form the insulating portion 10a. That is, the inner wall of the concave portion (hole portion) having the bottom portion is in a state provided with the conductive portion 50d and the insulating portion 10a. In the present embodiment, although the wiring layer extending to the wall surface of the recess is the conductive portion, the conductive portion is also referred to when a portion of the wiring layer is exposed to the wall surface of the recess. In such a multilayer printed wiring board 2, when the recess 70 having the bottom 60 is filled with the thermosetting resin filler, both the conductive portion extending from the wiring layer 50 a and the insulating portion exposed on the wall of the recess 70 are The thermosetting resin filler comes into contact with the In addition to the case where the wiring layer is formed by extending to the wall surface, the conductive portion is also referred to as a conductive portion also when the conductive film is formed on the wall surface by plating or the like. In the present embodiment, the recess means a portion of the surface of the multilayer printed wiring board which is recognized as being clearly recessed from the other portions.

  In the multilayer printed wiring board, as a range of the inner diameter and the depth of the recess having the through hole or the bottom, the inner diameter is preferably 0.1 to 1 mm and the depth is 0.1 to 10 mm, respectively.

  The wiring layer forming the conductive portion is not particularly limited, such as copper plating, gold plating, tin plating, etc., but from the viewpoint of the filling property of the thermosetting resin filler described later and the adhesion with the cured product, And copper are preferable. Similarly, as the insulating layer constituting the printed wiring board, paper phenol, paper epoxy, glass cloth epoxy, glass polyimide, glass cloth / non-woven cloth epoxy, glass cloth / paper epoxy, synthetic fiber epoxy, fluorocarbon resin, Polyphenylene ether, polyphenylene oxide, cyanate ester, polyimide, PET, glass, ceramic, silicon wafer and the like can be mentioned. Among these, from the viewpoint of the filling property of the thermosetting resin filler and the adhesion with the cured product, it is preferable to use a glass cloth / non-woven cloth epoxy, polyphenylene ether, polyimide, ceramic, and epoxy resin containing Cured products are more preferred. The epoxy resin-containing cured product refers to a cured product of an epoxy resin impregnated with glass fibers or a cured product of a resin composition containing an epoxy resin.

  The thermosetting resin filler of the present invention is used for filling a hole in a multilayer printed wiring board having a conductive portion and an insulating portion on the inner wall of the through hole or recess as described above, and is an epoxy resin as an essential component And an epoxy resin curing agent and an inorganic filler. Hereinafter, each component which comprises the thermosetting resin filler of this invention is demonstrated.

<Epoxy resin>
The thermosetting resin filler of the present invention contains, as an epoxy resin, two epoxy resins of an epoxy resin having a tertiary amine and an epoxy resin having a bisphenol type skeleton as essential components. When the thermosetting resin filler contains such two specific types of epoxy resins, it is possible to obtain a filler that has high adhesion to both the conductive portion and the insulating portion and is also excellent in electrical insulation. The reason for this is not clear, but is considered as follows. That is, in the present invention, by including an epoxy resin having a polar group such as tertiary amine as the epoxy resin, it is generally formed not only from the insulating part made of an organic material such as epoxy resin but also from a metal material. It is considered that the filling property of the filler is improved for a member provided with both parts of the conductive part. Moreover, it is thought that the water absorbency of hardened | cured material can be reduced by containing the epoxy resin which has a bisphenol-type frame | skeleton, As a result, electrical insulation improves. Furthermore, by the combination of the epoxy resin having a bisphenol type skeleton and the epoxy resin having a tertiary amine, the filling state of the filler can be maintained at a high level, as a result, to both the insulating portion and the conductive portion. Adhesion can be improved. However, the above-mentioned mechanism is just our guess and is not necessarily bound by this theory.

  The epoxy resin having a tertiary amine is not particularly limited as long as it has two or more epoxy groups in one molecule and has a tertiary amine group, and even an aliphatic epoxy resin is aromatic. Group epoxy resin may be used. From the viewpoints of heat resistance, electrical insulation, water absorption and the like, aromatic epoxy resins are preferable to aliphatic epoxy resins. The epoxy resin having a tertiary amine may be liquid, semi-solid or solid, and among them, liquid is preferable. In the present invention, the liquid means that it is in a liquid state having fluidity at 20 ° C.

  Examples of the epoxy resin having a tertiary amine as described above include tetraglycidyl aminodiphenylmethane, tetraglycidyl metaxylylene diamine, triglycidyl para aminophenol, diglycidyl aniline, diglycidyl ortho toluidine etc. as liquid ones. Examples of solid substances include diaminodiphenylmethane epoxy and the like. The epoxy resin which has these tertiary amines may be used individually by 1 type, and may use 2 or more types together. As these commercial products, jER-630 (para amino phenol type epoxy resin) manufactured by Mitsubishi Chemical Corporation, jER-604 (diaminodiphenylmethane type epoxy), ELM-100 (para amino phenol type epoxy resin) manufactured by Sumitomo Chemical Co., Ltd., Japan GAN manufactured by Kayaku Co., Ltd. (diglycidyl aniline), GOT manufactured by Nippon Kayaku Co., Ltd. (diglycidyl ortho toluidine), and the like.

  Examples of the epoxy resin having a bisphenol type skeleton used in combination with the above-described epoxy resin having a tertiary amine include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E (AD) type epoxy resin, bisphenol S type epoxy Although a resin etc. are mentioned, a bisphenol A epoxy resin, a bisphenol F-type epoxy resin, and a bisphenol E (AD) epoxy resin are preferable from an electric insulation and an adhesive viewpoint to a conductive part and an insulation part. Moreover, although the epoxy resin which has a bisphenol-type frame | skeleton is used any of liquid, semi-solid, and solid, it is preferable in particular that it is liquid from a filling viewpoint. The liquid state is as described in the description of the epoxy resin having a tertiary amine. One of these epoxy resins having a bisphenol skeleton may be used alone, or two or more thereof may be used in combination, and in particular, two types of bisphenol A epoxy resin and bisphenol F epoxy resin are used in combination. Is preferred. As these commercial products, jER-828, jER-834, jER-1001 (bisphenol A epoxy resin), jER-807, jER-4004P (bisphenol F epoxy resin), manufactured by Mitsubishi Chemical Corporation, Air Water Co., Ltd. R710 (bisphenol E type epoxy resin) etc. are mentioned.

  It is more preferable that the epoxy resin having a tertiary amine and the epoxy resin having a bisphenol type skeleton are contained in a ratio of 20:80 to 90:10 on a mass basis. If the ratio of both is within the above-mentioned range, it is possible to obtain a filler which is further excellent in the electrical insulation and also in the adhesion to the conductive portion and the insulating portion.

  The thermosetting resin filler of the present invention may contain an epoxy resin other than those described above, and may be, for example, a phenol novolac epoxy resin, a cresol novolac epoxy resin, bisphenol A as long as the effects of the present invention are not impaired. Novolak type epoxy resin, biphenyl type epoxy resin, naphthol type epoxy resin, naphthalene type epoxy resin, dicyclopentadiene type epoxy resin, triphenylmethane type epoxy resin, alicyclic epoxy resin, aliphatic chain epoxy resin, phosphorus containing An epoxy resin, an anthracene epoxy resin, a norbornene epoxy resin, an adamantane epoxy resin, a fluorene epoxy resin, an alkylphenol epoxy resin, and the like may be included. The above-mentioned epoxy resin is preferably liquid at normal temperature from the viewpoint of hole-filling properties, but it does not exclude an epoxy resin which is solid at normal temperature, and when it contains an epoxy resin which is solid at normal temperature, a solvent is used A solid epoxy resin may be dissolved and used at room temperature.

<Epoxy resin curing agent>
The thermosetting resin filler of the present invention contains, as an essential component, an epoxy resin curing agent for curing the above-mentioned epoxy resin. As the epoxy resin curing agent, known curing agents generally used to cure epoxy resins can be used, such as amines, imidazoles, polyfunctional phenols, acid anhydrides, isocyanates And polymers containing these functional groups, and a plurality of these may be used if necessary. Amines include dicyandiamide, diaminodiphenylmethane and the like. The imidazoles include alkyl-substituted imidazoles, benzimidazoles and the like. The imidazole compound may also be an imidazole latent curing agent such as an imidazole adduct. Examples of polyfunctional phenols include hydroquinone, resorcinol, bisphenol A and its halogen compounds, and further, novolak which is a condensate with an aldehyde, and resol resin.
Examples of the acid anhydride include phthalic anhydride, hexahydrophthalic anhydride, methyl nadic anhydride, benzophenone tetracarboxylic acid and the like. As isocyanates, there are tolylene diisocyanate, isophorone diisocyanate and the like, and those obtained by masking this isocyanate with phenols and the like may be used. One of these epoxy resin curing agents may be used alone, or two or more thereof may be used in combination.

  Among the above-described epoxy resin curing agents, amines and imidazoles can be suitably used from the viewpoints of adhesion to the conductive part and the insulating part, storage stability, and heat resistance. As the amines, adduct compounds of aliphatic polyamines such as alkylene diamines having 2 to 6 carbon atoms, polyalkylene polyamines having 2 to 6 carbon atoms, and aromatic ring-containing aliphatic polyamines having 8 to 15 carbon atoms, or isophorone diamine, Those containing an adduct compound of an alicyclic polyamine such as 1,3-bis (aminomethyl) cyclohexane or a mixture of an adduct compound of the above aliphatic polyamine and an adduct compound of the above alicyclic polyamine are preferable as the main component. In particular, curing agents based on adduct compounds of xylylene diamine or isophorone diamine are preferred.

  As the adduct compound of the aliphatic polyamine, one obtained by subjecting the aliphatic polyamine to an addition reaction of an aryl glycidyl ether (particularly, phenyl glycidyl ether or tolyl glycidyl ether) or an alkyl glycidyl ether is preferable. Moreover, as an adduct compound of the said alicyclic polyamine, what is obtained by making n-butyl glycidyl ether, a bisphenol A diglycidyl ether, etc. add to the said alicyclic polyamine is preferable.

    Examples of aliphatic polyamines include alkylene diamines having 2 to 6 carbon atoms such as ethylene diamine and propylene diamine, polyalkylene diamines having 2 to 6 carbon atoms such as diethylene triamine and triethylene triamine, and aromatic ring-containing fats having 8 to 15 carbon atoms such as xylylene diamine Family polyamines and the like. Examples of commercially available modified aliphatic polyamines include FXE-1000 or FXR-1020, Fujicure FXR-1030, Fujicure FXR-1080, FXR-1090M2 (Fuji Kasei Kogyo Co., Ltd.), Ancamine 2089K, Sanmide P-117. Sunmide X-4150, Ankamin 2422, Serwett R, Sunmide TX-3000, Sunmide A-100 (manufactured by Air Products Japan Co., Ltd.), and the like.

    Examples of alicyclic polyamines include isophorone diamine, 1,3-bis (aminomethyl) cyclohexane, bis (4-aminocyclohexyl) methane, norbornene diamine, 1,2-diaminocyclohexane, laromine and the like. Commercially available modified alicyclic polyamines include, for example, ankamine 1618, ankamine 2074, ankamine 2596, ankamine 2199, sunmide IM-544, sunmide I-544, ankamine 2075, ankamine 2280, ankamine 1934, ankamine 2228 (air products Japan stock) Made by company), Dytoclar F-5197, Daitoclar B-1616 (made by Daito Sangyo Co., Ltd.), Fujicure FXD-821, Fujicure 4233 (made by Fuji Kasei Kogyo Co., Ltd.), jER Cure 113 (made by Mitsubishi Chemical Co., Ltd.), Lalomin C-260 (made by BASF Corporation) etc. are mentioned.

  The imidazoles are preferably of the non-latent type, for example, a reaction product of an epoxy resin and imidazole, and the like. The (B) imidazole compound of the present invention is, for example, 2-methylimidazole, 4-methyl-2-ethylimidazole, 2-phenylimidazole, 4-methyl-2-phenylimidazole, 1-benzyl-2-methylimidazole, 2 And -ethylimidazole, 2-isopropylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole and the like. Examples of commercially available imidazole compounds include imidazoles such as 2E4MZ, C11Z, C17Z and 2PZ, and AZINE (azines) compounds of imidazole such as 2MZ-A and 2E4MZ-A, and imidazoles such as 2MZ-OK and 2PZ-OK. And an imidazole hydroxymethyl compound such as 2PHZ or 2P4MHZ (all of which are manufactured by Shikoku Kasei Kogyo Co., Ltd.). As a commercial item of an imidazole type latent curing agent, Cuazole P-0505 (made by Shikoku Chemicals Co., Ltd.) etc. can be mentioned, for example.

  From the viewpoint of adhesion to both the conductive part and the insulating part, it is preferable to use the imidazoles described above as the epoxy resin curing agent in combination with a polyamine and / or an imidazole type latent curing agent.

  The compounding amount of the epoxy resin curing agent is preferably 1 to 30 parts by mass with respect to 100 parts by mass of the epoxy resin from the viewpoints of adhesion to both the conductive part and the insulating part, electrical insulation, water absorption, etc. And more preferably 4 to 20 parts by mass. In addition, when the imidazole and the polyamine and / or the imidazole type latent curing agent are used in combination, the blending ratio of the imidazole and the polyamine and / or the imidazole type latent curing agent is 1:99 on a mass basis. It is preferably -99: 1, more preferably 10:90 to 90:10.

<Inorganic filler>
The thermosetting resin filler of the present invention contains an inorganic filler for stress relaxation due to curing shrinkage of the filler and adjustment of the linear expansion coefficient. As an inorganic filler, the well-known inorganic filler used for a normal resin composition can be used. Specifically, for example, 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 and the like Fillers and metal fillers such as copper, gold, silver, palladium and silicone can be mentioned. These inorganic fillers may be used alone or in combination of two or more.

  Among these inorganic fillers, calcium carbonate, silica, barium sulfate and aluminum oxide which are excellent in low hygroscopicity and low volume expansion are suitably used, and in particular, silica and calcium carbonate are more suitably used. The silica may be amorphous, crystalline or a mixture thereof. In particular, amorphous (fused) silica is preferred. Moreover, as calcium carbonate, any of natural ground calcium carbonate and synthetic precipitated calcium carbonate may be used.

  The shape of the inorganic filler is not particularly limited, and may be spherical, needle-like, plate-like, scaly, hollow, indeterminate, hexagonal, cubic, flaky, etc. A spherical shape is preferable from the viewpoint.

  The average particle size of the inorganic filler is preferably 0.1 μm to 25 μm, preferably considering the dispersibility of the inorganic filler, the filling property to the hole, the smoothness when forming the wiring layer in the hole-filled portion, etc. A range of 0.1 μm to 15 μm is appropriate. More preferably, it is 1 μm to 10 μm. The average particle diameter means an average primary particle diameter, and the average particle diameter (D50) can be measured by a laser diffraction / scattering method.

  The compounding ratio of the inorganic filler is 10 to 1000 mass with respect to 100 mass parts of the epoxy resin from the viewpoint of achieving both the thermal expansion coefficient, the abradability, the adhesiveness, and the printability and the hole filling property when formed into a cured product. It is preferably a part, more preferably 20 to 500 parts by mass, and particularly preferably 30 to 300 parts by mass.

<Other ingredients>
In 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 or talc can be added.

As the above-mentioned fatty acid, it is a general formula: (R1COO) _n -R2 (substituent R1 is hydrocarbon having 5 or more carbon atoms, substituent R2 is hydrogen or metal alkoxide, metal and n is 1 to 4) The compounds represented can be used. The said fatty acid can express the effect of thixotropy provision, when carbon number of substituent R1 is five or more. More preferably, n is 7 or more.

  The fatty acid may be an unsaturated fatty acid having a double bond or a triple bond in the carbon chain, or may be a saturated fatty acid not containing them. For example, stearic acid (the number of carbon atoms and the number of unsaturated bonds and in parentheses is the numerical expression by the position. 18: 0), hexanoic acid (6: 0), oleic acid (18: 1 (9)), icosane Examples include acid (20: 0), docosanoic acid (22: 0), and melisic acid (30: 0). As for carbon number of substituent R1 of these fatty acids, 5-30 are preferable. More preferably, it is C5-C20. Also, for example, a metal alkoxide having a substituent group R2 substituted with an alkoxyl-capped titanate-based substituent, such as a metal alkoxide having a coupling agent-based structure and a long (five or more carbon atoms) backbone. It may be. For example, the 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 Chemical Co., Ltd.) can be used. Examples of other metal soap elements include Ca, Zn, Li, Mg and Na.

  The proportion of the fatty acid is preferably 0.1 to 2 parts by mass with respect to 100 parts by mass of the inorganic filler from the viewpoint of thixotropy, embedding property, defoaming property, and the like.

  The fatty acid may be blended by using an inorganic filler which has been surface-treated with fatty acid beforehand, and it becomes possible to more effectively impart thixotropy to the thermosetting resin filler. In this case, the blending ratio of the fatty acid can be reduced as compared to the case of using the untreated filler, and when all the inorganic filler is the fatty acid-treated filler, the blending ratio of the fatty acid is 0. 0. to 100 parts by mass of the inorganic filler. It is preferable to be 1 to 1 part by mass.

  In addition, the thermosetting resin filler of the present invention may contain a silane coupling agent. By blending a silane coupling agent, the adhesion between the inorganic filler and the epoxy resin can be improved, and the occurrence of cracks in the cured product can be suppressed.

  Examples of the silane coupling agent include epoxysilane, vinylsilane, imidazolesilane, mercaptosilane, methacryloxysilane, aminosilane, styrylsilane, isocyanate silane, sulfide silane, ureidosilane and the like. Further, the silane coupling agent may be blended by using an inorganic filler which has been surface-treated with the silane coupling agent in advance.

  The blending ratio of the silane coupling agent is 0.05 to 2.5 parts by mass with respect to 100 parts by mass of the inorganic filler from the viewpoint of achieving both the adhesion between the inorganic filler and the epoxy resin and the defoaming property. Is preferred.

  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. When an electroless plating is performed on the formed cured product after curing the thermosetting resin filler filled in the hole of the printed wiring board by containing the oxazine compound, an aqueous potassium permanganate solution or the like may be used. The roughening of the cured product can be facilitated, and the peel strength with plating can be improved.

  In addition, 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-butyl catechol, pyrogallol, phenothiazine, etc., clay, kaolin, etc. for adjustment of viscosity etc. Known thickeners such as organic bentonite and montmorillonite and thixotropic agents can be added. In addition, known additives such as silicone type, fluorine type, polymer type antifoaming agent, adhesion agent such as leveling agent, imidazole type, thiazole type, triazole type, silane coupling agent, etc. are blended. be able to. In particular, when organic bentonite is used, it is preferable that the portion protruding from the surface of the hole is easily formed in a protruding state that is easy to polish and remove, and has excellent polishability. Also, known and commonly used coloring agents such as phthalocyanine blue, phthalocyanine green, iodine green, disazo yellow, crystal violet, titanium oxide, carbon black, naphthalene black and the like can be blended.

The viscosity of the thermosetting resin filler measured by a rotary viscometer is preferably 200 to 1000 dPa · Sec at a temperature of 25 ° C. and a speed of 30 sec at 5 rpm. If the viscosity is in this range, it is possible to further improve both the shape retentivity (liquid dripping suppression) and the embeddability. More preferably, it is 200 to 800 dPa · Sec. The viscosity is JIS Z
The cone-plate viscometer comprising a cone rotor (conical rotor) and a plate described in 8803 is measured, for example, with a TV-30 type (manufactured by Toki Sangyo Co., Ltd., rotor 3 ° × R9.7).

  The thermosetting resin filler of the present invention can be formed, for example, using the known patterning method such as screen printing method, roll coating method, die coating method or vacuum printing method, for example, the hole portion of the through hole of the multilayer printed wiring board as described above. Filled in the recess with the bottom. At this time, it is completely filled so as to slightly protrude from the hole or recess. The thermosetting resin filler is cured by heating the multilayer printed wiring board in which the holes and recesses are filled with the thermosetting resin filler, for example, at 80 to 160 ° C. for about 30 to 180 minutes, and the cured product is It is formed. In particular, it is preferable to cure in two stages from the viewpoint of suppressing outgassing. That is, it is preferable to precure the thermosetting resin filler at a lower temperature, and then to perform main curing (finish curing). The conditions for the pre-curing are preferably heating at 80 to 110 ° C. for about 30 to 90 minutes. Since the hardness of the pre-cured cured product is relatively low, unnecessary portions protruding from the substrate surface can be easily removed by physical polishing and can be made flat. After that, it is heated to be fully cured. As the conditions for the main curing, heating for about 30 to 180 minutes at 130 to 160 ° C. is preferable. At this time, the cured product hardly expands or shrinks due to its low expansion property, and becomes a final cured product having excellent dimensional stability, low hygroscopicity, adhesion, electrical insulation and the like. The hardness of the precured product can be controlled by changing the heating time and temperature of the precuring.

  After the thermosetting resin filler is cured as described above, 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 surface wiring layer is formed. Are patterned into a predetermined pattern to form a predetermined circuit pattern. If necessary, the surface of the cured product may be roughened with a potassium permanganate aqueous solution or the like, and then a wiring layer may be formed on the cured product by electroless plating or the like.

  EXAMPLES The present invention will next be described in more detail by way of examples, which should not be construed as limiting the invention thereto. In the following, “parts” and “%” are all based on mass unless otherwise noted.

<Preparation of thermosetting resin filler>
Various components shown in Tables 1 and 2 below are blended in proportions (parts by mass) shown in the respective tables, and after preliminary mixing with a stirrer, dispersion is performed with a 3-roll mill, and Examples 1 to 16 and Comparative Examples One to five thermosetting resin fillers were prepared. The viscosity of each thermosetting resin filler obtained is measured using a viscometer (TV-30 type, manufactured by Toki Sangyo Co., Ltd., rotor 3 ° × R9.7), and the 30 Sec value at 25 ° C. and 5 rpm Under the measurement conditions of 300 to 500 dPa · Sec.

In addition, * 1 to * 16 in Table 1 represent the following components.
* 1: Mitsubishi Chemical Corporation jER-630 (triglycidyl aminophenol, liquid)
* 2: ELM-100 (Paraaminophenol type liquid epoxy resin) manufactured by Sumitomo Chemical Co., Ltd.
* 3: GAN manufactured by Nippon Kayaku Co., Ltd. (diglycidyl aniline, liquid)
* 4: GOT manufactured by Nippon Kayaku Co., Ltd. (diglycidyl ortho toluidine, liquid)
* 5: jER-828 (bisphenol A liquid epoxy resin) manufactured by Mitsubishi Chemical Corporation
* 6: Mitsubishi Chemical Corporation jER-807 (bisphenol F type liquid epoxy resin)
* 7: Air Water R710 (bisphenol E type liquid epoxy resin)
* 8: Dow Chemical's DEN 431 (phenol novolac semi-solid epoxy resin)
* 9: 2PHZ (imidazole hydroxymethyl compound) manufactured by Shikoku Kasei Kogyo Co., Ltd.
* 10: 2P4 MHZ (imidazole hydroxymethyl compound) manufactured by Shikoku Kasei Kogyo Co., Ltd.
* 11: Fuji Cure FXR-1030 (modified aliphatic polyamine) manufactured by Fuji Kasei Kogyo Co., Ltd.
* 12: jER Cure 113 (modified aliphatic polyamine) manufactured by Mitsubishi Chemical Corporation
* 13: Shikoku Kasei Kogyo Co., Ltd. Cuazole P-0505 (imidazole type latent curing agent)
* 14: Bihoku Powder Industry Co., Ltd. Softon 1800 (calcium carbonate, average particle size 1.2 μm)
* 15: ACEMAT 3300 (amorphous silica, average particle size 9.5 μm) manufactured by Evonik Degussa Japan Co., Ltd.
* 16: Shin-Etsu Chemical Co., Ltd. SK-66 (silicone oil)

<Evaluation>
(1) Evaluation of adhesion of conductive material (conductive part) Evaluation was made by providing a wiring layer (plating thickness 25 μm) made of copper plating on the entire inner wall surface of the through hole having an inner diameter of 0.3 mm and a depth of 3.2 mm. Prepare a 3.2 mm thick multilayer printed wiring board with through holes, fill the through holes with each thermosetting resin filler by screen printing method, and use a hot air circulation type drying oven (DF610 manufactured by Yamato Scientific Co., Ltd.) The thermosetting resin filler was cured by heating at 150 ° C. for 30 minutes. The optical microscope observation and the electron microscope observation of the cross section of the through-hole filled up with the filler were performed, and evaluation was performed according to the following criteria.
In addition, the cross-section of the through-hole to observe was formed as follows in microscopically observing.
That is, a multilayer printed wiring board including through holes is cut perpendicularly to the thickness direction, and on a cut surface, SiC abrasive paper (# 500 and # 2000 manufactured by Marumoto Struers Co., Ltd.) and a polishing machine (manufactured by Harzok Japan Ltd.) The cross section of the through hole was polished using FORCIPOL-2V).
○: no peeling between the conductive portion (wiring layer) and the filler material Δ: the conductive portion (wiring layer) and the filler material are slightly peeled off ×: the conductive portion (wiring layer) and the filler material are clearly peeled off The evaluation results are as shown in Tables 1 and 2 below.

(2) Evaluation of adhesion of filler (insulation part) Evaluation A through hole with an inner diameter of 0.5 mm is formed by a drill on a 3.2 mm thick printed wiring board whose insulating layer is made of glass cloth / non-woven cloth epoxy, With the insulating layer exposed on the inner wall surface, the thermosetting resin filler is filled in the through holes by the screen printing method, and heated for 30 minutes at 150 ° C. in a hot air circulating drying oven (DF610 manufactured by Yamato Scientific Co., Ltd.) The thermosetting resin filler was cured by heating. The optical microscope observation and the electron microscope observation of the cross section of the through-hole filled up with the filler were performed, and evaluation was performed according to the following criteria. In addition, the cross section of the through-hole to observe was carried out similarly to the said (1) adhesiveness (conductive part) evaluation of a filler.
○: no peeling between the insulating portion (insulating layer) and the filler material Δ: the insulating portion (insulating layer) and the filler material are slightly peeled off ×: the insulating portion (insulating layer) and the filler material are clearly peeled off The evaluation results are as shown in Tables 1 and 2 below.

(3) Evaluation of adhesion of conductive material (conductive part / insulation part) (1) Drilling of multilayer printed wiring board used in evaluation of adhesive property of conductive material (conductive part) to a depth of 1.6 mm from one side (drill diameter 0.5 mm) to remove part of the wiring layer to expose the insulating layer, and prepare a multilayer printed wiring board having a through hole in which the conductive portion and the insulating portion are formed on the inner wall, and heat each through hole The curable resin filler was filled by a screen printing method, and the thermosetting resin filler was cured by heating at 150 ° C. for 30 minutes in a hot air circulating drying oven (DF610 manufactured by Yamato Scientific Co., Ltd.). The optical microscope observation and the electron microscope observation of the cross section of the through-hole filled up with the filler were performed, and evaluation was performed according to the following criteria. The cross section of the through hole to be observed was carried out in the same manner as the evaluation (1) of the adhesion (conductive part) of the filler.
:: There is no peeling of the filler from both the conductive part and the insulating part ○: There is slight peeling from the filler to either the conductive part or the insulating part. Δ: Both of the conductive part and the insulating part Peeling with Filler x: There is clear peeling with the filler in both the conductive part and the insulating part. The evaluation results are as shown in Tables 1 and 2 below.

(4) Confirmation of filling state The following evaluation was performed about the filling state of the filler to a through hole. That is, (1) drilling processing from a single side to a depth of 1.6 mm on a multilayer printed wiring board with a thickness of 3.2 mm having a through hole with an inner diameter of 0.3 mm used in the adhesion (conductive part) evaluation of the filler 0.5 mm) to remove part of the wiring layer to expose the insulating layer, and prepare a multilayer printed wiring board having a through hole in which the conductive portion and the insulating portion are formed on the inner wall, and heat each through hole The curable resin filler was filled by screen printing, placed on a rack to maintain the substrate at an angle of 90 ° ± 10 °, and left at room temperature for 30 minutes. The state after leaving was checked visually. The judgment criteria are as follows.
:: The filling state is maintained.
○: Some collapse was observed, but no dent was found on the through hole surface.
X: The filling state was broken, and a dent was observed on the surface of the through hole.
The evaluation results were as shown in Tables 1 and 2 below.

(5) Water absorption evaluation The thermosetting resin filler of each Example and a comparative example is applied by the applicator on the glossy surface side (copper foil) of GTS-MP foil (made by Furukawa Circuit Foil Co., Ltd.), and hot air circulation type It was cured at 150 ° C. for 30 minutes in a drying oven (DF610 manufactured by Yamato Scientific Co., Ltd.). Thereafter, the cured product is peeled off from the copper foil, and after cutting out a sample in a measurement size (size of 50 mm × 50 mm), drying is performed at 100 ° C. for 2 hours to completely remove moisture, and the mass is measured with a precision balance. The measurement of (W1) was performed. Thereafter, the sample was immersed in distilled water controlled at 23 ° C. ± 2 ° C., and the mass (W2) after 24 hours was measured. The water absorption was determined by (W2−W1) / W1 × 100 (%).
Water absorbency evaluation was performed by the following references | standards.
:: Water absorption rate less than 1.0% ○: Water absorption rate 1.0% or more, less than 1.5% Δ: Water absorption rate 1.5% or more, less than 2.0% ×: Water absorption rate 2.0% or more Evaluation result Were as shown in Tables 1 and 2 below.

(6) Evaluation of Electrical Insulating Property The thermosetting resin filler of each example and comparative example was formed on the FR-4 substrate on which the IPC-B-25A interdigital electrode described in IPC-SM-840-D was formed. The thermosetting resin filler is cured by printing by screen printing method and heating at 150 ° C. for 30 minutes in a hot air circulating drying oven (DF610 manufactured by Yamato Scientific Co., Ltd.) to form a cured product pattern, and insulation An evaluation substrate for resistance measurement was produced. The insulation resistance value of the obtained evaluation board | substrate was measured on condition of the following, and it was set as the initial value. As for the initial value, it was confirmed that the insulation resistance of each sample was 1.0 × 10 ¹² Ω or more. After that, IPC-SM-840-D Class H (25-65 ° C ± 2 ° C cycle, humidity 90% + 3%, -5%, VDC = 50 V, measurement time 100 V, T = 160 h, D coupon, 500 MΩ or more The insulation resistance value processed in accordance with 2.) was measured under the following conditions.
Measurement conditions of insulation resistance:
100 V DC was applied to the evaluation substrate, and the insulation resistance value was measured. The insulation resistance value after the treatment was evaluated according to the following judgment criteria.
:: insulation resistance of 1.0 × 10 ¹¹ Ω or more ○: insulation resistance of less than 1.0 × 10 ¹¹ Ω, 1.0 × 10 ¹⁰ Ω or more Δ: insulation resistance of less than 1.0 × 10 ¹⁰ Ω, 1 .0 × 10 ⁹ Ω or more ×: Insulation resistance less than 1.0 × 10 ⁹ Ω The evaluation results are as shown in Tables 1 and 2 below.

  As apparent from the evaluation results of Tables 1 and 2, a thermosetting resin filler containing both an epoxy resin having a tertiary amine and an epoxy resin having a bisphenol type skeleton as an epoxy resin (Examples 1 to 16) ) Is excellent in adhesion to both the conductive part and the insulating part, and is also excellent in electrical insulation, but only one of the epoxy resin having a tertiary amine and the epoxy resin having a bisphenol type skeleton The thermosetting resin filler (comparative examples 1 to 5) not containing is excellent in the adhesion of the conductive part or the insulating part, but the filling state is worse as compared with the example, and the adhesion with both the conductive part and the insulating part It can be seen that the sex is inferior. Moreover, it turns out that the thermosetting resin filler (comparative example 1, 2, 4, 5) which does not contain the epoxy resin which has a bisphenol type frame | skeleton as an epoxy resin has low water absorption, and electrical insulation is inferior.

DESCRIPTION OF SYMBOLS 1 Multilayer printed wiring board having through holes 2 Multilayer printed wiring board having recesses 10 insulating layer 10a insulating portion 20a, 20b, 20c, 20d wiring layers 30a, 30b, 30c, 30d wiring layers 40 through holes 50a, 50b, 50c, Wiring layer 20e, 30e, 50d Conductive portion 60 Bottom portion 70 Concave portion

Claims (10)

Conducting on a plurality of wiring layers stacked in the thickness direction via an insulating layer, a recess having a through hole or a bottom formed in the thickness direction of the plurality of wiring layers, and conducting on the inner wall of the through hole or the recess A thermosetting resin filler used for filling a hole in a multilayer printed wiring board having a portion and an insulating portion,
Containing epoxy resin, epoxy resin curing agent and inorganic filler,
A thermosetting resin filler, wherein the epoxy resin comprises an epoxy resin having a tertiary amine and an epoxy resin having a bisphenol type skeleton.   The thermosetting resin filler according to claim 1, wherein the epoxy resin having a tertiary amine and the epoxy resin having a bisphenol skeleton are contained in a ratio of 20:80 to 90:10 on a mass basis.   The thermosetting resin filler according to claim 1, wherein the epoxy resin curing agent contains at least one selected from the group consisting of an amine curing agent and an imidazole curing agent.   The thermosetting resin filler according to any one of claims 1 to 3, wherein the inorganic filler is at least one selected from the group consisting of calcium carbonate, silica, barium sulfate and aluminum oxide.   The thermosetting resin filler as described in any one of Claims 1-4 whose average particle diameter of the said inorganic filler is 0.1 micrometer-15 micrometers.   The thermosetting resin filler according to any one of claims 1 to 5, wherein the conductive portion of the multilayer printed wiring board is made of copper.   The heat according to any one of claims 1 to 6, wherein the epoxy resin having a bisphenol skeleton has at least one skeleton selected from the group consisting of bisphenol A type, bisphenol F type and bisphenol E type. Curable resin filler.   The thermosetting resin according to any one of claims 1 to 7, wherein the epoxy resin having a bisphenol skeleton has two kinds of epoxy resin having a bisphenol A skeleton and an epoxy resin having a bisphenol F skeleton. Resin filler.   The hardened | cured material of the thermosetting resin filler as described in any one of Claims 1-8.   The multilayer printed wiring board which has a hardened | cured material of Claim 9.

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