JPH0931307A - Thermosetting paste composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a thermosetting paste composition which can give a cured product at relatively low temperatures within a shout time while it has a long assured pot life by mixing a base metal powder in a specified range of particle diameters with an epoxy resin and a curing agent. SOLUTION: At least one base metal powder, in an amount of 50-92wt.%, based on the total weight of the paste composition, desirably selected from copper, nickel and iron powders and having a mean particle diameter is mixed with 30-50 equivalent %, based on the equivalents of an epoxy resin, a curing agent (e.g. phthalic anhydride or triethylenetetramine) to obtain a one-package thermosetting paste composition. Because it is desirable from the viewpoints of workability that the composition has a viscosity of about 50-1,000 Pa.s and a small viscosity change, it is suitable that the number of equivalents of the curing agent used is not excessively large.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a thermosetting paste composition applied to, for example, a conductive resin paste containing a semiconductor encapsulating resin or a metal filler.

[0002]

2. Description of the Related Art Generally, when an epoxy resin composition is cured with an accelerator using an acid curing agent, a network composed of ester bonds is formed, and when there is no accelerator, ester and ether bonds are mixed. A network structure is formed, and conversely, when there is only a promoter and no curing agent, a network is formed by an ether bond due to a reaction between epoxy groups. On the other hand, when an amine curing agent is cured together with an accelerator, a network consisting of amine bonds is formed, and when there is no accelerator, it has a network structure in which amine and ether bonds are mixed. A mesh of ether bonds is formed by the reaction between the two. Both the acid curing agent and the amine curing agent have been applied to various one-component thermosetting compositions such as a semiconductor encapsulating resin and a conductive paste containing a metal filler.

[0003]

However, the one-component thermosetting composition containing an accelerator can be cured at a relatively low temperature and forms a network of ester bonds and amine bonds, so that the mechanical strength of the cured product is high. On the other hand, it has the advantage of excellent adhesiveness, but when a base metal is added, a marked increase in viscosity occurs, the pot life in the actual process of the paste composition is short, and the viscosity rises sharply during storage. There was a problem of being short (for example, Japanese Patent Laid-Open No. 4-2
58661, JP-A-7-41706, JP-A-7-14422, and JP-A-7-45119).

The present invention solves the above-mentioned problems in the conventional conductive paste containing a base metal. It is possible to obtain a reaction-cured product at a relatively low temperature in a short time while ensuring a sufficiently long pot life. It is an object of the present invention to provide a one-part thermosetting paste composition.

[0005]

In order to achieve the above object, the thermosetting paste composition of the present invention has an average particle size of 0.
A base metal powder of 5 to 15 μm, an epoxy resin and a curing agent are contained, and the equivalent of the curing agent added to the epoxy resin reaction equivalent is 30% to 50%. The thermosetting paste composition of the present invention does not contain an organic curing accelerator. The curing agent for the epoxy resin may be selected according to the intended properties of the cured product, but is preferably an acid curing agent or an amine curing agent.
Further, in the above structure, the base metal is preferably at least one selected from copper, nickel, and iron.
Further, in the above structure, the content ratio of the base metal powder to the entire paste is preferably 50% by weight to 92% by weight.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION According to the thermosetting paste composition of the present invention, a base metal powder having an average particle size of 0.5 to 15 μm, an epoxy resin and a curing agent are contained, and the reaction equivalent of the epoxy resin is equivalent. Equivalent weight of curing agent added is 30% to 50%
By so doing, it is possible to achieve a one-part thermosetting paste composition that makes it possible to obtain a reaction-cured product at a relatively low temperature in a short time while ensuring a sufficiently long pot life.
That is, the reaction peak of a normal epoxy resin such as bisphenol A diglycidyl ester is around 130 ° C., whereas the thermosetting paste composition of the present invention has a reaction peak of 8 ° C.
It cures in a few hours even at 0 to 120 ° C.

Further, according to a preferred example of the present invention in which the base metal is at least one selected from copper, nickel and iron, the reactivity of the paste during heating can be enhanced by the excellent catalytic effect of the base metal. . Further, according to a preferable example of the present invention in which the content ratio of the base metal powder to the entire paste is 50% by weight to 92% by weight, a paste composition that is hardened at a relatively low temperature in a short time while maintaining an appropriate viscosity is obtained. Can be achieved.

In the conventional epoxy type curing system, if an accelerator is not used, it takes a long time for curing at a high temperature, and even if the curing agent is added in an equivalent amount or more, in the case of an acid curing agent, a mixture of ester bond and ether bond is mixed. When the formed network is an amine curing agent, a mixed network of amine bonds and ether bonds is formed. According to this example, curing is completed at a relatively low temperature and in a short time even without an accelerator, and after heating and curing, a network is formed by an ester bond or an amine bond corresponding to the equivalent of the curing agent, and may be mixed with an ether bond. confirmed. It is considered that in the thermosetting paste composition containing the base metal of this example, the surface of the base metal reactive with the epoxy group acted catalytically as the active site of the reaction. This catalytic action by the base metal is supported by the fact that even with the composition containing only the epoxy main agent containing no curing agent and the base metal powder, the curing temperature shifts to the high temperature side, but the network is formed by the ether bond. Further, such a catalytic action of the base metal surface causes a rapid curing reaction even at room temperature in the presence of the promoter. Curing agent equivalent is 50
If it exceeds%, the curing reaction tends to proceed rapidly and the pot life becomes short, which is not preferable. On the contrary, when the equivalent of the curing agent is less than 30%, not only the time required for curing becomes long, but also the ratio of ester bond or amine bond in the cured product is remarkably reduced, and from the viewpoint of mechanical strength of the cured product. Not preferable. The lower the content of base metal powder, the higher the temperature and the time required for curing, so the content of base metal powder is 5
It is preferably 0% by weight to 92% by weight. The viscosity of the paste of this example is 50 to 1000 pa in terms of workability.
It may be about s, but it is desirable that the change in viscosity is small.

Examples of the acid-based curing agent in this embodiment include phthalic anhydride, hexahydrophthalic anhydride, methylnadic acid anhydride, dodecenyl succinic anhydride, pyromellitic anhydride / maleic anhydride mixture, chlorendic anhydride and the like. Can be given. Examples of the amine-based curing agent include triethylenetetramine, diethylaminopropylamine, metaphenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, dicyandiamide, BF ₃
-Monoethylamine, polyamidoamine, imidazoles and the like can be mentioned. Examples of the other curing agent include phenol resin, amino resin, dicyandiamide, polymercaptan and the like.

[0010]

【Example】

(Example 1) Bisphenol A diglycidyl ester (DGEBA) as an epoxy main agent and 4-methylhexahydrophthalic anhydride (4-MHHFA) as an acid curing agent were used in proportions as shown in Table 1 with particle sizes of 1 to 5 μm. Mixed with base metal powder. As an index for determining the pot life, the time (A) at which the viscosity doubled when stored at 25 ° C. compared to the initial time was measured and compared. Further, the curing characteristics were compared by the time (B) until the curing reaction reached equilibrium at 120 ° C. As a comparative example, a paste containing dimethylbenzylamine (DMBA) as an accelerator and a paste containing no metal powder were prepared. Table 1 shows the results of the comparison.

[0011]

[Table 1]

Sample No. Sample No. 1 (viscosity 180 pa · s) No. 2 (viscosity 160 pa · s) is compared. No. 1 is a well-balanced paste that has a long pot life and hardens in a relatively short time, while sample No. 1 containing a catalyst. 2 takes a short time to cure, but 25 ° C
It can be seen that the increase in viscosity at is extremely fast. Sample N
o. 3 (viscosity of 250 pa · s) had a long pot life and was cured in a relatively short time. Sample No. 4 (viscosity 80p
The a / s) had a sufficiently long pot life. Sample No. 5
(Viscosity 360 pa · s) and sample No. 6 (viscosity 280p
a.s) is compared, sample No. Sample No. 5 has a long pot life and cures in a relatively short time, whereas sample No. 5 having a curing agent equivalent of more than 50% even in the absence of a catalyst.
It can be seen that the thickening of 6 is severe. Sample No. 7 (viscosity 1
5 pa · s) is the sample No. of this example. 3 and sample N
o. Although it is a comparative example in the case where the same curing agent equivalent as in No. 5 does not contain a base metal, it is understood that although the pot life is long, the curing takes a long time. From the above results, it is understood that each of the pastes of the present example has a well-balanced characteristic that it has a long pot life and is hardened in a relatively short time.

Example 2 Bisphenol A diglycidyl ester (DGEBA) as an epoxy main agent and diaminodiphenylmethane (DDM) as an amine curing agent were mixed with each base metal powder having a particle size of 1 to 5 μm in a ratio as shown in Table 2. . As in Example 1, the curing reaction reaches equilibrium at 120 ° C. for a time (A) at which the viscosity doubles as compared to the initial value when stored at 25 ° C. as an index for determining pot life and pot life. (B) was measured to compare the curing characteristics. As a comparative example, a paste containing salicylic acid (SA) as a promoter and a paste containing no metal powder were prepared.
Table 2 shows the results of the comparison.

[0014]

[Table 2]

In general, amine type curing agents tend to have shorter pot life and shorter curing time than acid type curing agents. Sample No. 8 (viscosity 200 pas) and sample N
o. When comparing 9 (viscosity 140 pa · s), sample N
o. Sample No. 8 has a well-balanced property of having a long pot life and hardening in a relatively short time, while Sample N containing a catalyst.
o. It can be seen that in No. 9, the time required for curing is short, but the viscosity increase at 25 ° C. is extremely fast. Sample No. 10
(Viscosity 270 pa · s) had a long pot life and was cured in a relatively short time. Sample No. 11 (viscosity 110pa
・ S) had a sufficiently long pot life. Sample No. 12
(Viscosity 290 pa · s) and sample No. 13 (viscosity 240
pa · s), sample No. Sample No. 12 had a long pot life and was cured in a relatively short time, while Sample N having a curing agent equivalent of more than 50% even if it contained no catalyst.
o. It can be seen that the thickening of No. 13 is severe. Sample No. 14
(Viscosity 10 pa · s) is the sample No. of this example. 10 and sample No. It is a comparative example in which the curing agent equivalent is the same as that of No. 12 and the base metal is not included, but it can be seen that the pot life is long but the curing takes a long time. From the above results, it is understood that each of the pastes of the present example has a well-balanced characteristic that it has a long pot life and is hardened in a relatively short time.

[0016]

As described above, according to the thermosetting paste composition of the present invention, the base metal powder, the epoxy resin and the curing agent are contained, and the equivalent of the curing agent added to the reaction equivalent of the epoxy resin is 30. % Or more and 50% or less, a relatively low temperature, while guaranteeing a sufficiently long pot life as a one-component thermosetting paste composition using a base metal.
It is possible to obtain a reaction-cured product in a short time, and the industrial effect is great in the field of using various pastes such as conductive pastes.

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Claims (4)

[Claims] 1. A base metal powder having an average particle size of 0.5 μm or more and 15.0 μm or less and an epoxy resin and a curing agent, and the equivalent of the curing agent added to the epoxy resin reaction equivalent is 30% or more and 50% or less. Which is a thermosetting paste composition. 2. The thermosetting paste composition according to claim 1, wherein the curing agent is an acid curing agent or an amine curing agent. 3. The thermosetting paste composition according to claim 1, wherein the base metal is at least one selected from copper, nickel, and iron. 4. The thermosetting paste composition according to claim 1, wherein the content ratio of the base metal powder to the entire paste is 50% by weight or more and 92% by weight or less.