JP6200063B2 - Thermosetting resin composition and printed wiring board filled with the resin composition - Google Patents

Description

  The present invention relates to a thermosetting resin composition, and more particularly to a thermosetting resin composition useful as a filling material for permanent holes such as via holes and through holes in printed wiring boards such as multilayer boards and double-sided boards. In particular, the present invention relates to a thermosetting resin composition that suppresses an increase in viscosity over time and is excellent in filling properties of holes in printed wiring boards and polishing properties after curing.

In recent years, there has been a demand for further reduction in the thickness and length of printed wiring boards in order to cope with the downsizing and high functionality of electronic devices. Therefore, for the printed wiring board, a construction method such as a build-up method is proposed in which an insulating layer is formed on the top and bottom of the core material, a necessary circuit is formed, an insulating layer is further formed, and a circuit is formed. And used.
In such a printed wiring board, a conductive layer is formed on the surface and inner walls of holes such as through holes such as through holes and via holes, and the holes are filled with a resin composition such as a thermosetting resin by printing or the like. . At this time, since the resin is filled so as to slightly protrude from the hole portion, the protruding portion is flattened and removed by polishing or the like after curing. Furthermore, the conductive layer on the surface is patterned. (See Patent Document 1)

In general, thermosetting epoxy resin compositions are widely used as resin compositions filled in holes because the cured products have excellent mechanical, electrical, and chemical properties and good adhesion. It has been.
In such a thermosetting epoxy resin composition, primary or secondary aromatic amines or acid anhydrides, tertiary amines or imidazoles are used as curing accelerators. Further, from the viewpoint of workability, the epoxy resin and the curing accelerator are often used as a one-component property that is mixed and dispersed to coexist. Problems with a one-component composition include strict control of storage conditions for the composition and short pot life. In particular, if the pot life is short, workability may be reduced. Therefore, a resin composition that can be used for a long time is desired.

  On the other hand, the printing method is the main method for filling the holes of the thermosetting epoxy resin composition. Items required by the printing method include fluidity and sagging, which are indicators of the ease of flowing into holes. After the epoxy resin composition is cured, the items required when removing the epoxy resin composition protruding by polishing such as buffing to flatten are as follows: polishability meaning ease of polishing and post-polishing The flatness of an epoxy resin composition is mentioned.

Japanese Patent Laid-Open No. 10-75027

An object of the present invention is to provide a thermosetting resin composition that suppresses an increase in viscosity over time, has excellent filling properties in holes in a printed wiring board, and has excellent polishing properties after curing, and the printed wiring board. To do. Its main purpose is to provide a thermosetting resin composition that suppresses an increase in viscosity over time and is excellent in filling properties of holes in printed wiring boards and polishing properties after curing.
More specifically, the heat-curing is excellent in suppressing the increase in viscosity over time, which was insufficient in the prior art, as well as the filling properties required for epoxy resin compositions for hole filling and polishing properties after curing. It is in providing a conductive resin composition.

  As a result of intensive studies to solve the above problems, the inventors have (A) an epoxy resin having no alicyclic skeleton, (B) an epoxy resin having an alicyclic skeleton, (C) a curing catalyst, (D ) It was found that a thermosetting resin composition characterized by containing a filler can solve the above-mentioned problems, and the present invention has been completed.

  That is, the thermosetting resin composition of the present invention contains (A) an epoxy resin having no alicyclic skeleton, (B) an epoxy resin having an alicyclic skeleton, (C) a curing catalyst, and (D) a filler. It is characterized by being used for filling holes in printed wiring boards.

  Moreover, the printed wiring board of this invention has a hole part filled with the hardened | cured material of the said thermosetting resin composition, It is characterized by the above-mentioned.

The epoxy resin composition of the present invention contains (A) an epoxy resin having no alicyclic skeleton, (B) an epoxy resin having an alicyclic skeleton, (C) a curing catalyst, and (D) a filler. An increase in the composition viscosity due to the change can be suppressed. As a result, the storage period can be extended, and strict storage management becomes unnecessary. Furthermore, since the pot life is also long, it is possible to prevent deterioration of workability and to use it stably for a long time. Specifically, the viscosity is stable even when used for a long time, so that the embedding property in the hole remains stable, and the problem that bubbles in the hole increase as the viscosity increases is suppressed. Can do.
In particular, by using an epoxy resin that does not have (A) an alicyclic skeleton, moderate fluidity and hardness of a cured product can be obtained, so that filling properties and polishing properties can be obtained. (B) By using an epoxy resin having an alicyclic skeleton, it is possible to suppress an increase in the viscosity of the composition over time due to the effect of suppressing the curing reaction of the composition. Therefore, all characteristics cannot be obtained if both are missing.

(D) About a filler, the role of the buffer material at the time of the shrinkage | contraction in thermosetting can be given by making it contain, and the function of stress relaxation can be provided to a resin composition. Further, by imparting thixotropy to the resin composition, it is possible to prevent a problem that the resin composition oozes out of the hole after printing and curing. Furthermore, by providing thixotropy, the resin composition can follow the unevenness of the copper surface in the hole at the time of filling and can be filled. Stable adhesion can be obtained by curing the resin composition and copper uniformly by subsequent curing.
Therefore, not all the characteristics can be obtained without (D) filler.

  On the other hand, the conventional thermosetting resin composition has sufficient filling properties and polishing properties, but it has been insufficient to suppress an increase in viscosity with time. The reason is that in the conventional thermosetting resin composition, it is usual to use only (A) an epoxy resin having no alicyclic skeleton, and the resin composition is designed to have a high reactivity. As a conventional measure, it was the simplest method to make it two-component, but when using it, two components had to be mixed, leading to a decrease in workability. Thus, it is difficult to use a conventional thermosetting resin composition stably for a long time.

  From the above, the thermosetting resin composition of the present invention suppresses the increase in viscosity over time, the thermosetting resin composition excellent in the filling property to the hole of the printed wiring board and the polishing property after curing, In addition, the printed wiring board can be provided.

Hereinafter, each component in the thermosetting resin composition of this invention is demonstrated.
(A) As an epoxy resin which does not have alicyclic skeleton, what is necessary is just to have two or more epoxy groups in 1 molecule, 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 novolak type epoxy resin, diglycidyl ether of propylene glycol or polypropylene glycol, 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, ethylene glycol Or diglycidyl ether of propylene glycol, sorbitol polyglycidyl ether, sorbitan polyglycidyl ether Compounds having two or more epoxy groups in one molecule such as ter, tris (2,3-epoxypropyl) isocyanurate, triglycidyltris (2-hydroxyethyl) isocyanurate, tetraglycidylaminodiphenylmethane, tetraglycidylmetaxylyl Examples include amine-type epoxy resins such as range amine, triglycidyl paraaminophenol, diglycidyl aniline, and diglycidyl orthotoluidine.

  As these commercial products, jER-828 manufactured by Mitsubishi Chemical Co., Ltd. as a bisphenol A type liquid epoxy resin, jER-807 manufactured by Mitsubishi Chemical Co., Ltd. as a bisphenol F type liquid epoxy resin, and manufactured by Mitsubishi Chemical Co., Ltd. as an amine type liquid epoxy resin. jER-630, Sumitomo Chemical Co., Ltd. ELM-100, etc. are mentioned.

  Of these, amine-type liquid epoxy resins containing a benzene ring, which is a heat-resistant skeleton, can be used when the paste has a low viscosity and the amount of filler can be increased. These can be used alone or in combination of two or more.

  (A) The compounding ratio of the epoxy resin having no alicyclic skeleton is 4 to 40% by mass, preferably 10 to 38% by mass, more preferably 20 to 35% by mass, based on the total amount of the composition. If it is less than 4% by mass, the reactivity of the composition becomes poor and it becomes impossible to have sufficient hardness. As a result, there is a possibility of causing problems such as missing composition during polishing. On the other hand, if it is 40% by mass or more, an increase in viscosity over time cannot be suppressed.

  (B) The epoxy resin having an alicyclic skeleton is a compound having a cyclic aliphatic skeleton and two or more epoxy groups in the molecule. However, (B) the epoxy group of the epoxy resin having an alicyclic skeleton preferably does not contain a glycidyl ether group. (B) An epoxy group preferable as an epoxy resin having an alicyclic skeleton is an epoxy group formed by including two carbon atoms constituting the cycloaliphatic skeleton, or an epoxy group directly bonded to the cycloaliphatic skeleton. As such an epoxy resin having (B) an alicyclic skeleton, it is produced by oxidizing a corresponding alicyclic olefin compound with an aliphatic percarboxylic acid or the like, and a substantially anhydrous aliphatic percarboxylic acid is used. It is preferable in that it has a high epoxidation rate.

  (B) The epoxy resin having an alicyclic skeleton has a linking group, for example, a single bond, an alkylene group, a carbonyl group (—CO—), an ether bond (—O—), an ester bond (—COO—), Examples thereof include an amide bond (—CONH—), a carbonate bond (—OCOO—), and a group in which a plurality of these are linked. Among them, preferred linking groups are an ether bond (—O—) and an ester bond (—COO—). The alkylene group preferably has 1 to 18 carbon atoms, and includes a linear or branched alkylene group such as methylene, methylmethylene, dimethylmethylene, ethylene, propylene, trimethylene group, 1,2-cyclopentylene, Divalent alicyclic hydrocarbon groups such as 3-cyclopentylene, cyclopentylidene, 1,2-cyclohexylene, 1,3-cyclohexylene, 1,4-cyclohexylene, cyclohexylidene group ( Particularly, a divalent cycloalkylene group) and the like are exemplified.

  (B) The epoxy resin having an alicyclic skeleton can be obtained on the market, for example, “Celoxide 2021” or “Celoxide 2081” in which the linking group is an ester bond, and “EHPE3150” in which the linking group is an ether bond. (Both are manufactured by Daicel Chemical Industries, Ltd.), and particularly preferable examples include “Celoxide 2021” and “EHPE3150”.

  (B) The compounding ratio of the epoxy resin having an alicyclic skeleton is from 2 to 38% by mass, preferably from 4 to 31% by mass, and more preferably from 6 to 20% by mass, based on the total amount of the composition. If it is less than 2% by mass, an increase in viscosity over time may not be suppressed. On the other hand, if it is 38% by mass or more, the reactivity of the composition becomes poor, and it may not be possible to have sufficient hardness. As a result, problems such as missing composition may occur during polishing.

The blending ratio of (A) an epoxy resin having no alicyclic skeleton and (B) an epoxy resin having an alicyclic skeleton is shown below. By mass ratio, (A) :( B) = 90: 10-20: 80, preferably 85: 15-50: 50, more preferably 80: 20-60: 40.
(B) Even if the ratio of the epoxy resin having an alicyclic skeleton is high, the characteristics are satisfied. However, if the ratio of the epoxy resin having no (A) alicyclic skeleton is high, the curing time can be shortened and workability is improved. So desirable.

  (C) Any curing catalyst can be used as long as it is a known conventional catalyst for curing (A) an epoxy resin having no alicyclic skeleton and (B) an epoxy resin having an alicyclic skeleton. Specifically, the following can be cited. That is, imidazoles such as trade names 2E4MZ, C11Z, C17Z and 2PZ, AZINE compounds of imidazoles such as trade names 2MZ-A and 2E4MZ-A, isocyanurates of imidazoles such as trade names 2MZ-OK and 2PZ-OK, Product names 2PHZ, 2P4MHZ and other imidazole hydroxymethyl compounds (the product names are all manufactured by Shikoku Kasei Kogyo Co., Ltd.), dicyandiamide and derivatives thereof, melamine and derivatives thereof, diaminomaleonitrile and derivatives thereof, diethylenetriamine and triethylenetetramine , Tetraethylenepentamine, bis (hexamethylene) triamine, triethanolamine, diaminodiphenylmethane, organic acid dihydrazide, and other amines, 1,8-diazabicyclo [5,4,0] undecene-7 octylate, sulfo Honate (trade name DBU, manufactured by San Apro Co., Ltd.), 3,9-bis (3-aminopropyl) -2,4,8,10-tetraoxaspiro [5,5] undecane (trade name ATU, Ajinomoto Co., Inc.) or organic phosphine compounds such as triphenylphosphine, tricyclohexylphosphine, tributylphosphine, and methyldiphenylphosphine. These can be used singly or in combination of two or more according to the demand for improving the properties of the coating film. In addition, known acid anhydrides such as tetrapropenyl succinic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, dodecenyl succinic anhydride, and methylendomethylenetetrahydrophthalic anhydride can also be used. Among these curing catalysts, in particular, imidazole is preferable because it is excellent in heat resistance and chemical resistance in a cured epoxy resin, and water-absorbing properties can be obtained. 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 its derivatives, and their organic acid salts and epoxy adducts have adhesion and rust prevention properties with copper, and are used as curing agents for epoxy resins. Since it can contribute not only to work but also to prevention of copper discoloration of the printed wiring board, it can be suitably used.

  The blending amount of the (C) curing catalyst is sufficient in a normal quantitative ratio. For example, per 100 mass of the total amount of the (A) epoxy resin having no alicyclic skeleton and the (B) epoxy resin having an alicyclic skeleton. 0.05 mass part or more and 140 mass parts or less are suitable. Preferably, they are 0.1 mass part or more and 120 mass parts or less, More preferably, they are 0.3 mass part or more and 100 mass parts or less. When the amount is less than 0.05 parts by mass, a cured product having sufficient hardness cannot be obtained. As a result, there is a possibility of causing problems such as missing composition during polishing. If it is 140 parts by mass or more, an increase in viscosity over time cannot be suppressed, and generally the pre-curing rate of the resin composition becomes too fast, and voids are likely to remain in the cured product, which is not preferable.

  (D) Filler is used for stress relaxation by curing shrinkage, adjustment of linear expansion coefficient, and further to impart thixotropy to the resin composition. Any non-conductive material may be used. Specifically, for example, silica, barium sulfate, calcium carbonate, silicon nitride, aluminum nitride, boron nitride, alumina, magnesium oxide, aluminum hydroxide, magnesium hydroxide, titanium oxide, mica, talc, organic bentonite, kaolin, silitin And non-metallic fillers such as calcined kaolin clay, calcined talc and calcined Neuburg silica, and metal fillers such as copper, gold, silver, palladium and silicon. These can be used singly or in combination of two or more according to the demand for improving the properties of the coating film. Among these, silica and calcium carbonate are preferable in terms of characteristics and work.

Examples of the shape of the filler (D) 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, but any shape may be used.
(D) The average particle size of the filler is not particularly suitable and can be made into a paste, and any particle size may be used as long as expected characteristics are obtained.
Further, (D) the surface treatment of the filler may or may not have any treatment.

  (D) 30-90 mass% of the composition whole quantity is preferable, and, as for the mixture ratio of a filler, More preferably, it is 40-70 mass%. When the blending ratio of the inorganic filler is less than 30% by mass, the obtained cured product cannot exhibit a sufficiently low expansion property, and further, the polishing property and adhesion are insufficient. On the other hand, when it exceeds 90% by mass, it becomes difficult to form a paste, and printability, hole filling and filling properties cannot be obtained.

  In the thermosetting resin composition of the present invention, when a liquid epoxy resin is used at room temperature, it is not always necessary to use a diluting solvent, but a diluting solvent may be added to adjust the viscosity of the composition. . 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.

  It is preferable that the mixture ratio of a dilution solvent is 10 mass% or less of the whole quantity of a thermosetting resin composition. When the blending ratio of the dilution solvent exceeds 10% by mass, bubbles and cracks are likely to be generated in the hole due to the effect of evaporation of volatile components during curing. More preferably, it is 5 mass% or less.

  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.

  The thermosetting resin composition of this embodiment is a print in which a conductive layer such as copper is formed on the surface and the wall surface of a hole, for example, using a known patterning method such as a screen printing method, a roll coating method, or a die coating method. Filled in the hole of the wiring board. At this time, it is completely filled so as to slightly protrude from the hole. And the printed wiring board with which the hole part was filled with the thermosetting resin filler is heated, for example at 150 degreeC for 60 minutes, a thermosetting resin filler is hardened, and hardened | cured material is formed.

  And the unnecessary part of the hardened | cured material which protruded from the surface of the printed wiring board is removed and planarized by the well-known physical polishing method. Then, a predetermined circuit pattern is formed by patterning the conductive layer on the surface into a predetermined pattern. 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.

  The present invention will be described in more detail based on examples and comparative examples, but the technical scope and embodiments of the present invention are not limited thereto. “Parts” or “%” in Examples and Comparative Examples are based on weight unless otherwise specified. A property value test of the composition of this example was performed by the method described below.

(Preparation of paste)
The components shown in Table 1 were premixed with a stirrer at respective blending ratios (parts by mass), and then dispersed with a three-roll mill. Examples 1 to 4 and Comparative Examples 1 to 5 were cured. A resin composition was prepared.

Performance evaluation:

(1) Viscosity Each of the thermosetting resin compositions of Examples 1 to 4 and Comparative Examples 1 to 5 was measured for the viscosity before and after standing for 168 hours in a 30 ° C. environment, and the thickening rate was determined by the following formula. . The viscosity was measured by taking 0.2 ml of each thermosetting resin composition and using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd.) under the conditions of 25 ° C. and 5 rpm / min.
Thickening rate = (viscosity after 168 hours−initial viscosity) ÷ initial viscosity evaluation criteria are as follows.
○: Thickening rate 20% or less ×: Thickening rate more than 20%

(2) Fillability The glass epoxy substrate in which through-holes were previously formed by panel plating was filled with each thermosetting resin composition of Examples 1 to 4 and Comparative Examples 1 to 5 in the through-holes by screen printing. Then, this was put into a hot air circulation type drying furnace and main curing was performed at 150 ° C. for 1 hour to obtain an evaluation sample. This evaluation sample was physically polished by a polishing machine equipped with a high cut buff 19 (SFBR- # 320 manufactured by Sumitomo 3M), and the cross section of the hole was observed with an optical microscope (100 times). The evaluation criteria are as follows.
○: Cracks / voids / peeling are not observed in all through holes.
X: Any of void / crack / peeling is recognized.

(3) Abrasiveness:
In the glass epoxy board | substrate which formed the through hole by panel plating previously, each thermosetting resin composition of the said Examples 1-4 and Comparative Examples 1-5 was filled in the through hole by the screen-printing method. It put into the hot-air circulation type drying furnace, main curing was performed at 150 degreeC for 1 hour, and the evaluation sample was obtained. This evaluation sample was physically polished by a polishing machine equipped with a high-cut buff 19 (SFBR- # 320, manufactured by Sumitomo 3M), and the surface polishing state was observed visually and with an optical microscope. The evaluation criteria are as follows.
◯: The paste that protrudes from the surface is removed by polishing once in the number of times of polishing.
(Triangle | delta): The paste which protruded on the surface is removed by grinding | polishing by frequency | count of 2 times.
X: A residue of the thermosetting resin composition is observed around the through hole or between adjacent through holes, or the thermosetting resin composition of the through hole is missing.

Table 2 shows the results of the above tests.

  From the above, by adjusting to the thermosetting resin compositions of Examples 1 to 4, the increase in viscosity over time is suppressed, and heat that is excellent in filling into holes of printed wiring boards and polishing after curing It turns out that a curable resin composition is obtained. On the other hand, Comparative Examples 1 and 2 have high reactivity and high viscosity, and the cured product has high hardness and cannot be polished unless the polishing conditions are strict. Therefore, the polishing properties are not sufficient. (B) Although Comparative Example 3 using only an epoxy resin having an alicyclic skeleton has poor reactivity, thickening is suppressed, but the strength and hardness of the cured product is insufficient, and the resin composition in the hole and copper Separation occurred at the interface, and the cured product in the hole was chipped so that the surface of the cured product did not become horizontal after polishing, so that filling properties and polishing properties could not be obtained. In Comparative Example 4, increase in viscosity could not be suppressed due to high reactivity. In Comparative Example 5, because the reactivity is high, an increase in viscosity cannot be suppressed, and further, due to the effect of not containing a filler, the stress relaxation of the resin composition is insufficient and cracks are generated. I couldn't.

Claims (2)

(A) an epoxy resin having no alicyclic skeleton, (B) an epoxy resin having an alicyclic skeleton, (C) a curing catalyst, (D) a composition comprising a filler ,
The blending ratio of the epoxy resin having no (A) alicyclic skeleton is 4 to 40% by mass of the total amount of the composition,
The blending ratio of the epoxy resin having the (B) alicyclic skeleton is 2 to 38% by mass of the total amount of the composition,
The blending ratio of the (A) epoxy resin having no alicyclic skeleton and the (B) epoxy resin having an alicyclic skeleton is a mass ratio of (A) :( B) = 90: 10 to 20:80. Yes,
As the epoxy resin having no (A) alicyclic skeleton, an amine-type epoxy resin having a benzene ring and two or more epoxy groups in one molecule,
(B) Holes in a printed wiring board containing a cycloaliphatic skeleton and a compound having two or more epoxy groups not containing a glycidyl ether group and having no benzene ring as the epoxy resin having an alicyclic skeleton A thermosetting resin composition characterized in that it is used for filling in water. A printed wiring board having a hole filled with a cured product of the thermosetting resin composition according to claim 1.