JPH08311157A - Curable conductive composition - Google Patents

Abstract

(57) Abstract: Even when a conductive cured body having a large thickness is formed, such as a case where a conductive through hole of a circuit forming substrate is formed, cracks do not occur during curing, and moreover, Provided is a curable conductive composition in which the obtained cured body exhibits stable conductivity over a long period of time. (1) (a) One epoxy group, one or more aromatic hydrocarbon groups, and 6 to 6 carbon atoms in the molecule.
18 to 30 carbon atoms having 20 aliphatic hydrocarbon groups
A monoglycidyl compound of, for example, cardanol glycidyl ether, (b) a crosslinking component having two or more epoxy groups and one or more aromatic hydrocarbon groups in the molecule, for example, bisphenol A glycidyl ether, (2) A curable conductive composition comprising a curing agent and (3) copper powder.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel curable conductive composition. In detail, even when a conductive cured body having a large thickness is obtained, such as a case where a through hole for a through hole of a circuit forming substrate is filled and cured to form a conductive through hole, cracks do not occur during curing. And moreover,
The resulting cured product is a curable conductive composition that exhibits stable conductivity over a long period of time.

[0002]

2. Description of the Related Art Curable conductive compositions are used in many fields in the electronics field, such as IC circuits, conductive adhesives, and electromagnetic wave shields. Particularly, recently, an inexpensive and highly reliable conductive through-hole forming technique has been proposed in which a curable conductive composition is filled in and cured in a through-hole forming through-hole to form a conductive through-hole.

In the use of the above-mentioned curable conductive composition for conductive through-holes, it is caused by the expansion and contraction of the base material during the curing of the curable conductive composition or the cooling after curing, and the curing contraction of the cured product. Due to the internal stress generated, the occurrence of cracks in the cured product becomes a problem. That is, the curable conductive composition is
The contact between the metal powders caused by the curing shrinkage of the curable resin exerts the conduction performance, and is accompanied by the curing shrinkage of the curable conductive composition itself. Therefore, the curable conductive composition,
In general, it has been pointed out that cracks are likely to occur inside the cured body during curing or during cooling after curing.
In addition, there is a problem in that even after curing, cracks are generated by thermal shock due to solder when mounting components.

As a method of solving such a problem,
(1) A method of adding a flexibility-imparting agent such as modified organosiloxane to the curable conductive composition, (2) a long-chain aliphatic ester compound having two or more glycidyl groups in the curable conductive composition, or A method of adding an ether compound (JP-A-4-173858) has been proposed.

However, the curable conductive composition in the above (1) has some effect on thermal shock when used for the purpose of forming circuits such as IC circuits, conductive adhesives and electromagnetic wave shields. For preventing the occurrence of cracks during curing or thermal shock during curing when a conductive cured body having a thickness is obtained, as in the case of filling the through holes for through holes to form conductive through holes There is still room for improvement. Further, in order to prevent the above phenomenon in the formation of through holes using such a flexibility-imparting agent, it is necessary to extremely increase the addition amount of the flexibility-imparting agent, and then the curable conductive composition. However, there is a problem that the curing shrinkage rate of the cured product decreases, and as a result, the conductivity of the obtained cured product decreases.

Further, in the above method (2), since the compound to be added is reactive, the compound can be added to the curable conductive composition without sacrificing the conductivity of the cured product. However, the glycidyl group in the compound is 2
Since there are one or more, the degree of freedom for the molecular motion of the compound is small after curing. Therefore, even with such a curable conductive composition, although it has a sufficient effect in the application of circuit formation, it is difficult to avoid generation of cracks when the through hole for through holes is filled and cured. .

Therefore, the present inventors have found that the carbon number is 11 to 13
Attempts were made to blend the linear alkyl monoglycidyl ether of No. 6 or the linear alkyl monoglycidyl ether having 9 to 11 carbon atoms into the epoxy resin (Japanese Patent Laid-Open No. 6-1844).
09 publication). By compounding these compounds having a linear alkyl group, the occurrence of cracks can be prevented to some extent.

However, in recent years, in order to reduce the cost of a circuit board, a conventional glass epoxy board is being changed to a paper-phenol board which is an inexpensive material. Since the paper-phenol substrate has a larger linear expansion coefficient than that of the glass epoxy substrate, when the through holes for through holes are formed in the paper-phenol substrate and the curable conductive composition is filled and cured, the conventional glass epoxy substrate is used. As compared with the case of using a substrate, the curable conductive composition is subjected to a large amount of expansion / contraction stress, and cracks easily occur in the obtained cured body.

The above-mentioned curable conductive composition containing an epoxy resin compounded with a compound having a linear alkyl group causes cracking of a cured product when applied to a substrate having a large linear expansion coefficient such as a paper-phenol substrate. I couldn't prevent it enough.

Therefore, when a thick conductive cured body is formed, no crack is generated during curing, and the resulting cured body exhibits a high degree of conductivity for a long period of time, and has a large linear expansion coefficient. It has been desired to develop a curable conductive composition that can be applied to a substrate without cracks or the like.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a curable conductive composition which does not generate cracks during curing and during cooling after curing even when a conductive cured product having a thickness is formed. It is in.

Another object of the present invention is to provide a curable conductive composition in which the obtained cured product exhibits a high degree of conductivity over a long period of time.

Still another object of the present invention is to provide a curable conductive composition which does not cause cracks during curing and during cooling after curing even when a substrate having a large linear expansion coefficient such as a paper-phenol substrate is used. To provide things.

[0014]

These objects of the present invention are achieved by the curable conductive composition described below.

(1) (a) One epoxy group in the molecule,
One or more aromatic hydrocarbon groups and 6 to 2 carbon atoms
C18 to C30 monoglycidyl compound having 0 aliphatic hydrocarbon group, and (b) crosslinking component having 2 or more epoxy groups and 1 or more aromatic hydrocarbon groups in the molecule And an epoxy resin containing 5 to 60 parts by weight of a monoglycidyl compound with respect to 100 parts by weight of a crosslinking component. (2) A curing agent having a reactive group that reacts with an epoxy group in the epoxy resin, and ( 3) Copper powder is included, and the curing agent is expressed as an equivalent of a reactive group that reacts with an epoxy group in an epoxy resin, and is 0.3 to 1.3 equivalents relative to 1 equivalent of an epoxy group of the epoxy resin. The curable conductive composition, wherein the copper powder is blended in the range of 180 to 750 parts by weight based on 100 parts by weight of the total amount of the epoxy resin and the curing agent.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION One component of the curable conductive composition of the present invention is an epoxy resin containing a specific monoglycidyl compound and a crosslinking component. The monoglycidyl compound contained in the epoxy resin has 18 carbon atoms having one epoxy group, one or more aromatic hydrocarbon groups, and an aliphatic hydrocarbon group having 6 to 20 carbon atoms in the molecule. ~ 30 monoglycidyl compounds.

It is important that the above monoglycidyl compound has one epoxy group in the molecule. When a compound having two or more epoxy groups is used, the compound acts as a cross-linking agent and the degree of freedom of molecular movement decreases,
As a result, the crack suppressing effect is not sufficiently exerted.
Further, when a compound having no epoxy group is used, the compound is not fixed in the cured product obtained by the reaction with the curing agent, which may cause elution or the like, which is not preferable.

The above monoglycidyl compound has one or more aromatic hydrocarbon groups and 6 to 20 carbon atoms in the molecule.
It is important to have an aliphatic hydrocarbon group of By using a monoglycidyl compound having such a specific group, even when a substrate having a large linear expansion coefficient such as a paper-phenol substrate is used, the occurrence of cracks during curing and cooling after curing is prevented. It can be effectively prevented.

Although the mechanism of action in which such an effect is exhibited is unknown, the present inventors consider the following. That is,
The aromatic hydrocarbon group has a function of improving compatibility with a crosslinking component having an aromatic hydrocarbon group and an epoxy group described later, while the aliphatic hydrocarbon group having 6 to 20 carbon atoms is It has a function of imparting flexibility to a cured product obtained by reacting with a curing agent described later. It is considered that these functions together contribute to the prevention of cracks during curing and during cooling after curing.

As the above-mentioned aromatic hydrocarbon group, a monovalent or divalent group derived from a benzene ring (phenyl group,
Alternatively, a phenylene group) is preferable. The number thereof may be 1 or more in the monoglycidyl compound, but 1 or in order not to impair the flexibility imparting effect to the cured product by the aliphatic hydrocarbon group having 6 to 20 carbon atoms or It is preferably two.

The above monoglycidyl compound must further have 18 to 30 carbon atoms. When the carbon number is less than 18, the aliphatic hydrocarbon group contained in the monoglycidyl compound has less than 6 carbon atoms, and the effect of imparting flexibility to the cured product is reduced, which is not preferable. Further, when the carbon number exceeds 30, the monoglycidyl compound becomes solid and the compatibility with other components constituting the epoxy resin decreases, which is not preferable.

A typical structural formula of the monoglycidyl compound which can be preferably used in the present invention is shown by the following formula (1).
And a monoglycidyl ester represented by the following formula (2).

[0023]

Embedded image

(In the formula, R1 represents an aliphatic hydrocarbon group having 6 to 20 carbon atoms or a group containing an aliphatic hydrocarbon group having 6 to 20 carbon atoms, and Ph represents a phenylene group. In the above formula, R1 is an aliphatic hydrocarbon group having 6 to 20 carbon atoms or a group containing an aliphatic hydrocarbon group having 6 to 20 carbon atoms. The aliphatic hydrocarbon group may be saturated or unsaturated, and may be linear or branched. When the aliphatic hydrocarbon group is unsaturated, it preferably has 1 to 4 unsaturated bonds.

Examples of the aliphatic hydrocarbon group having 6 to 20 carbon atoms include an alkyl group, alkenyl group, alkadienyl group, alkatrienyl group, alkatetraenyl group and the like having 6 to 20 carbon atoms. it can.

Further, as an example of a group containing an aliphatic hydrocarbon group having 6 to 20 carbon atoms, there can be mentioned an aralkyl group containing an alkylene group having 6 to 20 carbon atoms.

By blending the above-mentioned monoglycidyl compound with the curable conductive composition, the cured product obtained by heating and curing the curable conductive composition has both good conductivity and sufficient flexibility. You can Therefore, when the curable conductive composition is filled in a base material having a large coefficient of thermal expansion such as a paper-phenolic substrate, internal stress caused by the difference in the coefficient of thermal expansion with the base material during heat curing may be reduced. It is possible to relax and suppress the generation of cracks inside the cured body.

Specific examples of the above-mentioned monoglycidyl compound include nonylphenyl monoglycidyl ether, laurylphenyl monoglycidyl ether, and (iso) tridecylphenyl monoglycidyl in which R 1 of the formula (1) is a saturated aliphatic hydrocarbon group. Ether, pentadecaphenyl monoglycidyl ether, (iso) stearylphenyl monoglycidyl ether, or 3- (8 ', 11', 14'-pentadecatrienyl) phenylglycidyl ether in which R1 is an unsaturated aliphatic hydrocarbon group , 3- (8 ',
11'-pentadecadienyl) phenyl glycidyl ether, 3- (8'-pentadecenyl) phenyl glycidyl ether, or cardanol monoglycidyl ether which is a mixture of these three components and pentadecaphenyl monoglycidyl ether, or 3- (6 '-Tetradecenyl) phenyl glycidyl ether, 3- (4'-decenyl) phenyl glycidyl ether, or 3- (8'-phenyl-t-octyl) phenyl monoglycidyl ether, in which R1 contains an aromatic hydrocarbon group, 3- ( 4′-phenyl-n-hexyl) phenyl monoglycidyl ether, or a compound in which the glycidyl ether of the above compound is changed to a glycidyl ester, and the like, and these compounds may be used alone or in combination of two or more. .

Among the above monoglycidyl compounds, a compound in which R1 is a saturated or unsaturated aliphatic hydrocarbon group having 9 to 20 carbon atoms is a curable conductive composition obtained by blending the compound. It is preferable because it is particularly effective in relaxing the internal stress generated during curing.

The epoxy resin used in the present invention contains a crosslinking component in addition to the above monoglycidyl compound. As the cross-linking component, a compound having two or more epoxy groups and one or more aromatic hydrocarbon groups in the molecule and known to be used as an epoxy resin can be used without any limitation. Generally, a compound having one epoxy group at each end of the molecule and one to four phenyl groups can be preferably used.

In the present invention, as the crosslinking component, the epoxy equivalent is 170 to 170 for the reason that the water absorption is low, the crosslinking density when cured is high, and good conductivity is obtained.
200 g / equivalent of bisphenol A diglycidyl ether, epoxy equivalent of 156 to 200 g / equivalent bisphenol F diglycidyl ether, or a mixture thereof can be preferably used.

The above-mentioned epoxy equivalent is a value obtained by dividing the molecular weight by the equivalent number of epoxy groups contained in the molecule.

In the present invention, the above-mentioned monoglycidyl compound eliminates cracks in the cured product of the curable conductive composition, and reduces the crosslink density due to the crosslink component in the epoxy resin, thus lowering the conductivity. In order to prevent this, the amount should be in the range of 5 to 60 parts by weight with respect to 100 parts by weight of the crosslinking component, and preferably in the range of 15 to 50 parts by weight.

In the present invention, a reactive diluent may be added as another component of the epoxy resin. Such a reactive diluent is a liquid of 100 cps or less at room temperature, has 1 to 2 epoxy groups, and has a dissolution rate when 10 parts by weight of the reactive diluent is dissolved in 90 parts by weight of water at room temperature. A defined water solubility is 30% or less, and a compound having 6 to 16 carbon atoms can be preferably used.

The above-mentioned reactive diluent not only lowers the viscosity of the curable conductive composition to be obtained and improves workability, but also can reduce the amount of solvent used and facilitates volatilization of the solvent during curing. Therefore, defects such as voids in the obtained cured product can be reduced.

Specific examples of the reactive diluent that can be preferably used in the present invention include, for example, alkyl monoglycidyl ether having 6 to 16 carbon atoms, alkyl monoglycidyl ester having 6 to 16 carbon atoms, and 1,6-hexane. Examples thereof include diol diglycidyl ether, phenyl glycidyl ether, p-t-butylphenyl glycidyl ether, and adipic acid diglycidyl ester.

Among these reactive diluents, the alkyl monoglycidyl ether having 6 to 16 carbon atoms and the alkyl monoglycidyl ester having 6 to 16 carbon atoms each have a long-chain alkyl group, and therefore, the reactive diluent. Of the curable conductive composition obtained by adding the agent to the cured product has a β-dispersion temperature of −50 ° C. or lower, and in addition to the effect of incorporating the monoglycidyl compound, cracks caused by the thermal shock of the cured product. The effect of preventing the occurrence of can be exhibited.

When the reactive diluent is used for the above purpose, the addition amount may be determined within a range that does not significantly impair the effects of the present invention. Specifically, the reactive diluent is considered in terms of improving workability by reducing the viscosity of the curable conductive composition, and ensuring the crosslink density by the presence of an appropriate amount of the crosslinking component, that is, ensuring good conductivity. Then, it is preferably 10 to 60 parts by weight, and particularly preferably 20 to 50 parts by weight with respect to 100 parts by weight of the above-mentioned crosslinking component.

In the present invention, the second component curing agent is
Any known epoxy resin curing agent having a reactive group that reacts with the epoxy group in the above-mentioned epoxy resin can be used without any limitation. Examples of the reactive group that reacts with the epoxy group in the epoxy resin include an amino group, a carboxylic acid anhydride group, and a hydroxyl group. Examples of curing agents that can be preferably used in the present invention include, for example, amines such as metaphenylenediamine, diaminodiphenylmethane, and diaminodiphenylsulfone, phthalic anhydride,
Acid anhydrides such as succinic anhydride, trimellitic anhydride, pyromellitic anhydride, tetrahydrophthalic anhydride, compound type curing agents such as imidazoles and dicyandiamide, resin type curing agents such as phenol resins, polyamide resins, urea resins, etc. Can be mentioned. In particular, novolac-type phenol resin or novolac-type cresol resin has excellent moisture resistance, heat resistance, and reducibility, long pot life, and appropriate curing temperature for printed wiring boards. It is most suitable as the curing agent of the present invention because the amount of by-products that cause voids is extremely small.

The compounding amount of the above-mentioned curing agent may vary depending on the kind of the curing agent used, but in order to obtain a good cured product, it is generally a reactive group which reacts with the epoxy group in the epoxy resin. It should be 0.3 to 1.3 equivalents, preferably 0.4 to 1.1 equivalents, based on 1 equivalent of epoxy groups in the epoxy resin.

In particular, when the curing agent is a novolac type phenol resin or a novolac type cresol resin, it is represented by the equivalent amount of hydroxyl groups and is 0.4 to 1.3 equivalents, preferably 0 equivalent to 1 equivalent of epoxy groups of the epoxy resin. It is good to set it as 0.5-0.8 equivalent.

In the present invention, the copper powder is not particularly limited, but it is preferable that the purity is 99.99% or more in consideration of the reliability of the conductive through hole to be formed. In particular,
In order to maintain insulation reliability between through holes due to migration or the like, it is preferable that impurities such as silver that do not easily cause migration are mixed as impurities.

In addition, the shape of the copper powder is dendritic so that the adhesion with the epoxy resin is good, and in order to prevent the occurrence of cracks due to the peeling at the interface between the copper powder and the binder, and the specific description described later. By adjusting the particle size distribution and combining with the epoxy resin, a cured product obtained without cracks during curing is preferable in order to obtain a curable conductive composition that exhibits stable conductivity over a long period of time.

Further, in the curable conductive composition of the present invention, the copper powder extracted from the curable conductive composition without substantially changing the properties of the copper powder has an average particle size of 2
.About.20 .mu.m, preferably 5 to 15 .mu.m, and a tap density of 1.0 to 3.3 g / cm.sup.3, preferably 2.0 to.
It is preferably 3.1 g / cm @ 3.

The above-mentioned copper powder extracted from the curable conductive composition means the copper powder in which the curable resin constituting the curable conductive composition is separated without changing the properties of the copper powder, It is distinguished from raw copper powder.

Extraction of the copper powder from the curable conductive composition is generally carried out by dissolving the curable resin component constituting the curable conductive composition in a solvent which can be selectively dissolved and filtering the copper powder. The separation can be performed by a method in which the copper powder is subjected to Soxhlet extraction with a solvent for 20 hours.

Conventionally, the physical properties of the copper powder in the curable conductive composition have not been controlled, and generally, in the raw copper powder, the tap density and the average particle size are only controlled. . However, the properties of the copper powder in the curable conductive composition actually obtained change by kneading with the curable resin,
In particular, in the case of dendritic copper powder having many branched portions, the branched portions are crushed during kneading, and the average particle diameter and tap density greatly change. Therefore, the performance of the curable conductive composition obtained is difficult to maintain stable performance only by controlling the properties of the raw material copper powder, and the copper powder contained in the curable conductive composition, that is, cured It is important to control the properties of the copper powder extracted from the conductive conductive composition.

When the tap density of the copper powder extracted from the curable conductive composition exceeds 3.3 g / cm3 as described above, the branched portions of the dendritic copper powder are considerably crushed and the copper powder particles are separated from each other. Since there are few contact points, it tends to be difficult to obtain good conductivity after curing.

Since the dendritic copper powder is pulverized by kneading as described above, the tap density of the copper powder extracted from the curable conductive composition becomes higher than that of the raw material copper powder. Therefore, the tap density of the copper powder extracted from the curable conductive composition is 1.0 g even if kneading is performed by the production method described later.
/ Cm3 is the lower limit.

When the average particle size of the copper powder extracted from the curable conductive composition exceeds 20 μm, the flowability of the curable conductive composition deteriorates and the workability deteriorates, and the workability is relatively low. Since the abundance ratio of the copper powder having a large particle size becomes large, it tends to cause a crack when the curable conductive composition is cured. In particular, when a curable conductive composition is filled in and cured in a through hole for a through hole of a printed wiring board to obtain a conductive through hole, there is a high possibility that the conductivity is lowered due to the occurrence of cracks or the like. . The average particle size of the copper powder extracted from the curable conductive composition is 2 μm.
If smaller, the surface area becomes too large and the oxidation resistance tends to decrease.

Further, the raw material copper powder has an average particle size of 5 to 2
It is preferably 0 μm. In addition, in such a raw material copper powder, the ratio of the copper powder having a particle size of more than 40 μm is 0.05% by volume or less, and the standard deviation lo defined by the logarithmic distribution function is lo.
It is preferable that gσ is 0.20 to 0.26.

That is, as a result of various investigations by the present inventors on the cause of cracking of the curable conductive composition at the time of curing, when copper powder having a relatively large particle size is present in the copper powder,
It was found that cracks preferentially occur at the interface between the copper powder and the resin.

The copper powder having a large particle size has a standard deviation log σ defined by a logarithmic distribution function of 0.20 to 0.
By limiting the amount to be 26 and reducing the copper powder having a particle size of more than 40 μm, a synergistic effect with the action of the above-mentioned monoglycidyl compound is exerted, whereby the curable conductive composition is cracked at the time of curing and at the time of thermal shock. Can be effectively prevented.

The average particle diameter of the copper powder and the standard deviation logσ defined by the logarithmic distribution function, and the proportion of the copper powder having a particle diameter exceeding 40 μm are measured by a laser scattering method. That is, based on the measurement data of the particle size distribution of the copper powder measured by the laser scattering method, the standard deviation logσ defined by the average particle size and the logarithmic distribution function, and the ratio of the copper powder having a particle size exceeding 40 μm were calculated. . In addition, the average particle diameter of the copper powder in the present invention indicates a volume average particle diameter.

The particular average particle size used in the present invention,
The method for producing the dendritic copper powder having a particle size distribution is not particularly limited. For example, a temperature classifying method such as a rake classifier, a spiral classifier, a hydrocyclone, or a dry classifying method such as a sieve, a rotary type classifier, a circular center classifier, or an air separator is preferable.

In the present invention, in order to obtain a curable conductive composition having both stable conductivity and good handleability, the copper powder is 100 parts by weight of the total amount of the epoxy resin and the curing agent.
It should be 180 to 750 parts by weight, preferably 200 to 570 parts by weight, relative to parts by weight.

In the production of the curable conductive composition of the present invention, the kneading for uniformly dispersing the above-mentioned raw material copper powder in the curable resin is carried out with a weak dispersive force enough to loosen the secondary aggregation of the dendritic copper powder. Preferably.

Examples of the kneading apparatus include roll type kneaders such as roll mills, Banbury mixers and extruders, ball type kneaders such as ball mills and sand grinders, wheel type kneaders such as mix muller and multi mills. Kneader, screw mixer,
Examples thereof include a blade type kneader such as a zigzag mixer, a spiral mixer, a planetary mixer, a pony mixer, a raider machine, and a colloid mill. Among them, when kneading is performed using a device having a strong kneading force such as a roll-type kneading machine, a ball-type kneading machine, or a wheel-type kneading machine, the copper powder is easily crushed, and the conductivity of the obtained cured product decreases. Sometimes. Therefore, when such a device with a strong kneading force, for example, a three-roll mill is used, the conditions such as reducing the number of roll rotations, providing a gap between the rolls to some extent, and reducing the number of roll passages should be set. Is preferred.

Therefore, it is preferable to knead the curable conductive composition using a blade type kneader having a relatively weak kneading force. Among them, it is particularly preferable to use the planetary mixer.

In addition to the above curing agent, a curing accelerator may be added to the curable conductive composition of the present invention, if necessary. For example, tertiary amines and imidazoles can be preferably used for acid anhydrides, dicyandiamide, phenolic resins, aromatic amines and the like. An appropriate amount of the curing accelerator added is 0.1 to 5 parts by weight based on 100 parts by weight of the total amount of the epoxy resin and the curing agent.

The curable conductive composition of the present invention does not require a solvent in particular, but it may be used by adjusting the viscosity by adding a solvent depending on the application. As the solvent, known solvents can be used without particular limitation. For example,
Examples thereof include alcohols such as isopropanol and butanol, esters such as ethyl acetate and butyl acetate, and carbitols such as ethyl carbitol and butyl carbitol. You may use the said solvent individually or in mixture of 2 or more types.

Known additives may be added to the curable conductive composition of the present invention within a range that does not significantly deteriorate the characteristics. Examples of such additives include a defoaming agent, a dispersant, a thixotropic agent, a leveling agent, a rust preventive, and a reducing agent.

The curable conductive composition of the present invention is sprayed,
Coating, printing or filling can be performed by a known method such as brush coating, dipping, offset printing, screen printing.

[0064]

As can be understood from the above description, the curable conductive composition of the present invention uses an epoxy resin containing a specific monoglycidyl compound as the epoxy resin constituting the curable conductive composition. By doing so, it is possible to exert an excellent effect of preventing the occurrence of cracks during curing and preventing the occurrence of cracks due to the thermal shock of the obtained cured product. It also has the characteristic of exhibiting a high degree of conductivity over a long period of time.

Therefore, the curable conductive composition of the present invention is suitably used in the application of forming a relatively thick cured body such as through-hole filling by utilizing the above characteristics, and has high reliability. Obtainable.

[0066]

EXAMPLES Examples will be shown below for specifically explaining the present invention, but the present invention is not limited to these examples.

Examples 1 to 4 As a monoglycidyl compound, cardanol monoglycidyl ether represented by the following formula (manufactured by Cashew Co., Ltd.,
Product name Epicard)

[0068]

Embedded image

A curable conductive composition was prepared by using the above composition in the composition ratio shown in Table 1. That is, the epoxy resin is a monoglycidyl compound and an epoxy equivalent of 173 g as a crosslinking component.
/ Equivalent amount of bisphenol A diglycidyl ether and n-undecyl monoglycidyl ether as a reactive diluent were prepared at the compounding ratios shown in Table 1. Further, 46 parts by weight of a novolak type phenol resin having a hydroxy equivalent of 105 g / equivalent was blended with 100 parts by weight of bisphenol A diglycidyl ether as a curing agent in the epoxy resin to prepare a curable resin component. In addition, 1 part by weight of 2-
Ethyl-4-methylimidazole was added as a curing accelerator. Furthermore, the dendritic copper powder shown in Table 2 was previously added to 1.0
wt. % Of isopropyl tristearoyl titanate, and the dendritic copper powder of A was mixed in the compounding ratio shown in Table 1.

A kneading conductive composition was obtained by kneading the above composition ratio using a planetary mixer at 40 ° C. for 120 minutes.

The average particle size and tap density of the extracted copper powder in Table 2 are as follows. A part of the curable conductive composition in each example was dissolved in methyl ethyl ketone and filtered, and then the copper powder was washed by Soxhlet extraction. The obtained extracted copper powder was measured for each example, and the numerical range was specified for each copper powder.

The curable conductive composition thus obtained was evaluated by the following methods. That is, a 1.6 mm-thick paper-phenol substrate on which the test pattern shown in FIGS. 1 and 2 was formed was provided with a through hole having a diameter of 0.8 mm, and the resulting curable conductive composition was placed in the through hole. Was filled using a screen printing method. The filled curable conductive composition was dried in a hot air drying oven at 50 ° C. for 1 hour and then cured at 180 ° C. for 60 minutes.

After curing, the resistance value of each conductive through hole was measured with a digital multimeter, and the average value of the through hole resistance values was calculated. Those in which the resistance value of the through hole per hole exceeds 200 mΩ was counted as the number of defects in the calculation of the defect rate after curing. Further, the through hole resistance value is represented by an average value excluding defective through holes.

The cross-sections of the through holes obtained in each of the Examples and Comparative Examples were observed for 1,000 holes. The cross-section was observed with a stereoscopic microscope at a magnification of 40, and the crack generation rate was calculated.

Further, in each of the examples and comparative examples, a thermal shock test was conducted on 10,000 through holes. Cooling test condition is -40 ° C 30 minutes to 100
The cycle of 30 minutes at 30 ° C. (gas phase) was repeated 100 times.
After the thermal shock test, the through hole having a through hole resistance value increased by 30% or more was regarded as a defect, and the defect rate was calculated.

The results are summarized in Table 1.

Example 5 As the monoglycidyl compound, the same cardanol monoglycidyl ether as in Example 1 was used, and this was cured to 35 parts by weight with respect to 100 parts by weight of bisphenol A diglycidyl ether having an epoxy equivalent of 173 g / equivalent. As the agent, a hydroxy equivalent of 105 g / equivalent novolak type phenol resin was added to bisphenol A diglycidyl ether 10
46 parts by weight of 0 part by weight was compounded to obtain a curable resin component. To the above curable resin component, the same curing accelerator and copper powder as in Examples 1 to 4 were blended, and an appropriate amount of DBE (trade name) of an ester solvent of DuPont was added for viscosity adjustment. The composition was evaluated as in Examples 1 to 4. However, for the purpose of volatilizing the solvent, the curing condition of the curable conductive composition filled in the through hole was dried at 80 ° C. for 2 hours, and then heated to 180 ° C. at a heating rate of 1 ° C./min. The curing was carried out by changing the conditions of holding at 180 ° C. for 60 minutes. A series of evaluation results are also shown in Table 1.

Comparative Examples 1-2 A curable conductive composition was prepared in the same manner as in Examples 1-4 except that the amount of the monoglycidyl compound to be blended was changed and the other composition ratios were the same. The composition was evaluated. The results are also shown in Table 1.

Examples 6 to 10 As the monoglycidyl compound, isotridecylphenyl monoglycidyl ether (Example 6, molecular formula

[0080]

Embedded image

), Gingol monoglycidyl ether (= 3- (8 'pentadecenyl) phenyl monoglycidyl ether, Example 7, molecular formula

[0082]

[Chemical 4]

), Nonylphenyl monoglycidyl ester (Example 8, molecular formula

[0084]

Embedded image

), Pentadecaphenyl monoglycidyl ether (Example 9, molecular formula

[0086]

[Chemical 6]

), 3- (8 ', 11', 14'-Pentadecatrienyl) phenyl monoglycidyl ether (Example 10, molecular formula

[0088]

[Chemical 7]

A curable conductive composition was prepared in the same manner as in Example 3 except that (1) was used, and a series of evaluations were performed. The results are summarized in Table 1.

Examples 11 to 13 As a reactive diluent, n-tridecyl monoglycidyl ether (Example 11, molecular formula

[0091]

Embedded image

), N-nonyl monoglycidyl ether (Example 12, molecular formula

[0093]

[Chemical 9]

), N-undecyl monoglycidyl ester (Example 13, molecular formula

[0095]

[Chemical 10]

A curable conductive composition was prepared in the same manner as in Example 3 except that (1) was used, and a series of evaluations were performed. The results are summarized in Table 1.

Examples 14 and 15, Comparative Example 3 The same procedure as in Example 3 was carried out except that the dendritic copper powder shown in B of Table 2 was used and the copper powder was mixed in the mixing ratio shown in Table 1. A curable conductive composition was prepared and a series of evaluations were performed. The results are summarized in Table 1.

Examples 16 and 17, Comparative Example 4 The same procedure as in Example 3 was carried out except that the dendritic copper powder shown in Table 2C was used and the copper powder was mixed in the mixing ratio shown in Table 1. A curable conductive composition was prepared and a series of evaluations were performed. The results are summarized in Table 1.

[0099]

[Table 1]

[0100]

[Table 2]

[Brief description of drawings]

FIG. 1 is a plan view of a filling evaluation substrate.

FIG. 2 is a cross-sectional view of the filling evaluation substrate of FIG.

[Explanation of symbols]

 1 Through hole 2 Copper foil 3 Substrate

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H05K 1/09 7511-4E H05K 1/09 A 1/11 6921-4E 1/11 N

Claims (1)

[Claims] (1) (a) One epoxy group, one or more aromatic hydrocarbon groups, and 6 carbon atoms in the molecule.
18 to 3 carbon atoms having an aliphatic hydrocarbon group of 20
0 monoglycidyl compound, and (b) 2 in the molecule
Epoxy resin containing a cross-linking component having one or more epoxy groups and one or more aromatic hydrocarbon groups, and the compounding amount of the monoglycidyl compound is 5 to 60 parts by weight with respect to 100 parts by weight of the cross-linking component. ) A curing agent having a reactive group that reacts with an epoxy group in the epoxy resin and (3) copper powder, wherein the curing agent is represented by the equivalent amount of the reactive group that reacts with the epoxy group in the epoxy resin. The amount of the copper powder is 180 to 750 parts by weight based on 100 parts by weight of the total amount of the epoxy resin and the curing agent. A curable conductive composition that is blended within the range.