JPH1030082A - Adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an adhesive stabilized in joining to printed circuit boards mounted with functional elements having a large calorific value in operation and improved in heat reliability at a high temperature by using a specific epoxy resin (mixture) as a main agent so as to increase glass transition temperature of the adhesive. SOLUTION: This adhesive contains a naphthalene-based epoxy resin or a mixture of the epoxy resin with bisphenol A type or F type epoxy resin as a main agent (A). The adhesive is e.g. an anisotropic electroconductive adhesive. The adhesive is obtained by blending the main agent A with (B) a capsule type curing agent obtained by coating a cured material such as imidazole or an acid anhydride with a thermoplastic resin such as acrylic resin, (C) an additive such as silica and (D) a capsule type filler obtained by coating an electroconductive particles such as silver particles with an electrically insulating resin (e.g. a resin obtained by reacting an epoxy resin with an amine compound).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive, and more particularly to an adhesive for fixing an element and a conductive joint instead of a solder joint for joining various elements to a printed circuit board or the like.

In recent years, as an alternative to soldering various elements to a printed circuit board or the like, an adhesive which can easily fix or electrically connect the elements has attracted attention and has been put to practical use.

[0003] On the other hand, such an adhesive is stable and heat resistant even in electrical bonding or fixing of a high-performance functional element that generates a relatively large amount of heat during operation to a printed circuit board or the like. Excellent things are required.

[0004]

2. Description of the Related Art Conventionally, a large number of solders have been used as a bonding material for various functional elements mounted on a printed circuit board, etc.
Resin-based or conductive resin-based adhesives have been used as a joining material instead of solder, which can satisfactorily cope with working environments and operating environments.

Meanwhile, among the above-mentioned various functional elements, the amount of heat generated during operation tends to increase with the advance of performance, and the reliability of electronic components including such functional elements after mounting on a substrate is high. There is also a demand for the temperature condition of the test to be as high as about 150 ° C.

As such an adhesive for bonding elements, a thermosetting resin-based adhesive is more suitable than a thermoplastic resin-based adhesive from the viewpoints of moisture absorption resistance, electrical insulation and the like. Among them, epoxy resin-based adhesives are most useful when comprehensively evaluated from electrical characteristics, low-temperature rapid curing, cost, and the like.

[0007]

However, the conventional epoxy resin-based adhesive as described above is generally made of bisphenol A type epoxy resin or bisphenol F
Ingredients such as imidazole and acid anhydrides (methyltetrahydrophthalic anhydride, succinic anhydride, etc.) mixed with the main agent such as epoxy resin of the mold type, and those obtained by further mixing these with conductive fillers Most of such adhesives have a glass transition temperature of 130 ° C. or lower.

Accordingly, when such a conventional epoxy resin-based adhesive is used to join a functional element having a relatively large amount of operating heat to a printed circuit board or the like as described above, it is possible to stabilize the bonding against high operating heat and achieve a 150 ° C. There is a problem in that it is not possible to cope with a reliability test under a high temperature condition of ℃.

In view of the above-mentioned conventional problems, the present invention raises the glass transition temperature of an epoxy resin-based adhesive to stabilize the bonding of a functional element having a relatively large operating heat generation to a printed circuit board or the like. And 150
It is an object of the present invention to provide a novel adhesive excellent in heat resistance and capable of sufficiently responding to a reliability test under a high temperature condition of about ° C.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object of the present invention, for fixing a functional element having a relatively large amount of operating heat to a printed circuit board or the like or for electrical connection,
The main component is a naphthalene-based epoxy resin (an epoxy resin having naphthalene as a basic skeleton) or a mixture of a naphthalene-based epoxy resin and at least one bisphenol A-type or bisphenol F-type epoxy resin. An adhesive containing a curing agent that reacts with the resin material of the main agent and an additive is used.

Further, a naphthalene-based epoxy resin is used as a main component, or a mixture obtained by mixing at least one bisphenol A type or bisphenol F-type epoxy resin with a naphthalene-based epoxy resin is used as a main component. An adhesive having anisotropic conductivity containing a capsule-type curing agent coated with a plastic resin, an additive, and a capsule-type filler in which conductive particles are coated with an insulating resin is used.

An adhesive having such a composition or an anisotropic conductive adhesive is mainly composed of a naphthalene-based epoxy resin or at least one of a bisphenol A type and a bisphenol F type epoxy resin. Since the mixture mixed with the resin is used as the main agent, its glass transition point is at least about 30 ° C. to 50 ° C. higher than that of the conventional epoxy resin-based adhesive, and the change in the physical properties of the resin material is suppressed up to the high temperature. Can improve heat resistance.

[0013] The low thermal expansion of the adhesive by adding an additive of the such as silica approximate the adhesive to thermal expansion of the substrate and adherend (SiO _2), or alumina (Al ₂ O ₃₎ And the heat shrinkage rate are reduced, distortion at the bonding interface due to the difference in thermal expansion and the heat shrinkage with the material to be bonded, reduction in bonding properties and peeling are suppressed, and the bonding of materials to be bonded such as functional elements to the substrate is suppressed. Bonding becomes stable.

Therefore, even when the above-mentioned adhesive is applied to the joining of various elements having a large calorific value, the coefficient of thermal expansion of the adhesive is made closer to the substrate or the material to be adhered comprising the various elements, thereby stabilizing the joining. In addition, it is possible to sufficiently cope with a reliability test in which a mounting substrate or the like after bonding the various elements is bonded under a high temperature condition of about 150 ° C., and good bonding stability can be obtained.

Further, by incorporating a capsule-type filler in which conductive particles are coated with an insulating resin into the composition of the adhesive having good bonding stability, an integrated circuit chip and a mounting substrate which are being miniaturized are promoted. Can be sufficiently applied to fine pitch connection, and an anisotropic conductive adhesive suitable for stable fine pitch connection can be realized.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the adhesive according to the present invention and an anisotropic conductive adhesive will be described in detail.

In this embodiment, for example, a naphthalene-based epoxy resin (an epoxy resin having naphthalene as a basic skeleton)
And a curing agent such as an imidazole or an acid anhydride (methyltetrahydrophthalic anhydride, succinic anhydride, etc.), for example, imidazole is encapsulated in a thermoplastic resin such as an acrylic resin with respect to 100 parts by weight of the main agent. An adhesive is obtained by mixing 50 parts by weight of a microcapsule-type curing agent, and adding and dispersing about 40% by weight of an additive composed of silica (SiO ₂ ) powder thereto.

Then, such an adhesive is further provided with gold, silver,
Alternatively, a microcapsule-type filler coated with an insulating resin obtained by reacting the surface of fine metal particles such as solder, for example, silver fine metal particles with an epoxy resin and an amine, or an amine compound such as tetraethylenepentamine or hexamethylenediamine. Is added at a volume ratio of 5 vol% to form an anisotropic conductive adhesive.

The adhesive or anisotropic conductive adhesive thus prepared has a glass transition temperature of about 181 ° C., which is about 50 ° C. higher than that of the conventional adhesive, and has a low thermal expansion coefficient. The heat-shrinkage ratio is reduced, and it is possible to obtain the respective adhesives having a good pot life such that the viscosity thereof slightly increases even after being left for one month and having excellent bonding stability. .

As shown in Table 1, 100 parts by weight of a main agent composed of a naphthalene-based epoxy resin (an epoxy resin having a naphthalene nucleus in a basic skeleton), 100 parts by weight of a naphthalene-based epoxy resin, and a bisphenol A type epoxy resin Of a naphthalene epoxy resin and 100 parts by weight of a bisphenol A type epoxy resin, 100 parts by weight of a naphthalene type epoxy resin and 50 parts by weight of a bisphenol F type epoxy resin The imidazole is encapsulated with a thermoplastic resin such as an acrylic resin for each of the main agent mixed with 100 parts by weight of a naphthalene-based epoxy resin and 100 parts by weight of a bisphenol F type epoxy resin. Microcapsule type curing agent
It is obtained by mixing 50 parts by weight per 100 parts by weight, adding an additive composed of silica (SiO ₂ ) powder at a weight ratio of 40 wt%, and reacting the surface of silver metal fine particles with an epoxy resin and an amine. Sample No.1, No.2, No.3, No.4, No.5 of the sample added and dispersed with 5 vol% of the microcapsule type filler for imparting conductivity covered with the insulating resin. Various kinds of anisotropic conductive adhesives were prepared.

In addition, a microcapsule type of imidazole is added to each of the main agent of only 100 parts by weight of bisphenol A type epoxy resin and the main agent of only 100 parts by weight of bisphenol F type epoxy resin as in the conventional example. Mix 50 parts by weight of the curing agent and add silica (S
No. 6 and No. 7 of comparative samples in which an additive composed of iO ₂ ) powder was added and dispersed by weight ratio of 40 wt% and 5 vol% of the microcapsule type filler for imparting conductivity. 2 types of anisotropic conductive adhesives were prepared.

[0022]

[Table 1]

Next, Table 2 shows the results of measuring the glass transition points (° C.) of the five anisotropic conductive adhesives of this embodiment and the two anisotropic conductive adhesives of the conventional example.

[0024]

[Table 2]

As is clear from the measurement results of the glass transition point of each anisotropic conductive adhesive shown in Table 2, the glass transition point of the sample No. 1 of the present invention containing only the naphthalene-based epoxy resin as the main component was: Bisphenol A type epoxy resin,
Alternatively, compared to the comparative sample No. 6 and No. 7 of the conventional type using only bisphenol F type epoxy resin as the main ingredient,
It is shown that the temperature rises extremely remarkably to about 0 ° C.

Further, another sample No. 1 of the present invention containing a mixture of a bisphenol A type epoxy resin or a bisphenol F type epoxy resin with a naphthalene type epoxy resin as a main component.
It has been shown that the glass transition points of No. 2, No. 3, No. 4 and No. 5 are 30 ° C. or more, respectively, as compared with the conventional type comparative samples No. 6 and No. 7, respectively. , Good heat resistance can be expected.

Next, five types of these embodiments and two types of the conventional example will be described.
15 days immediately after the production of various anisotropic conductive adhesives, 1
Table 3 shows the results obtained by examining the change over time in the viscosity after leaving at room temperature (20 ° C.) for a month.

[0028]

[Table 3]

As is clear from the results of the time-dependent changes in the viscosity of each anisotropic conductive adhesive sample shown in Table 3, the No. 1 to No. 5 samples of the present invention were compared with the comparative samples of the conventional type. In both No. 6 and No. 7, there was almost no increase in viscosity after standing for 15 days at room temperature (20 ° C.) compared to the viscosity immediately after production, and the viscosity increased extremely even after standing for one month. It is slightly recognized, indicating a good pot life.

The good pot life is due to the shelf life of the resin material and the use of a microcapsule type in which imidazole is encapsulated with a thermoplastic resin such as an acrylic resin as a curing agent. This is also because the agent is prevented from directly reacting.

Next, a fixed amount of each of the five anisotropic conductive adhesives of the above embodiment and the two anisotropic conductive adhesives of the conventional example was applied on a comb-shaped electrode pattern of an Al film having an electrode interval of 20 μm.
After curing by heating at 150 ° C. for 2 minutes and then at 150 ° C. for 2 hours, a DC voltage of 5 V is applied to the comb-shaped electrode pattern for 200 hours at an environment of 85 ° C. and 85% humidity. Table 4 shows the results of the electrolytic corrosion test.

[0032]

[Table 4]

As is clear from Table 4, the results of the electrolytic corrosion test of each anisotropic conductive adhesive were as follows. All the samples had good insulation resistance immediately after production of 10 ¹¹ Ω or more, and the insulation after 200 hours. It shows good electrolytic corrosion resistance such that the resistance hardly changes.

It should be noted that it is present in the seven kinds of anisotropic conductive adhesives of the above-described embodiment and the conventional example, and has an effect on electric corrosion resistance.
Cl ^-, Na ^+, the total amount of the impurity ion concentration of K ⁺ and the like 20
ppm.

Next, a terminal pattern of a glass epoxy substrate (for example, having a pattern of 360 terminals provided at a pitch of 100 μm) is formed by using the five kinds of anisotropic conductive adhesives of the above embodiment and the two kinds of anisotropic conductive adhesives of the conventional example. Tables show the results of the temperature cycle test under which the chips were bonded (50 samples per type of resin-based adhesive) and these samples were repeated 1000 cycles at a temperature of -65 ° C to 150 ° C. It is shown in FIG.

[0036]

[Table 5]

The results of a temperature cycle test of a sample using each of the anisotropic conductive adhesives are also apparent from Table 5. As shown in Table 5, only the bisphenol A type epoxy resin or the bisphenol F type epoxy resin was used as the main component. In the case of using the sample No. 6 and No. 7 for comparison with the conventional example of the anisotropic conductive adhesive, 21 to 32 out of 50 test sheets have poor conduction due to thermal deterioration of the resin material. doing.

On the other hand, the sample No. of the present invention of an anisotropic conductive adhesive containing a naphthalene-based epoxy resin or a mixture of a naphthalene-based epoxy resin and a bisphenol A-type or bisphenol F-type epoxy resin as a main component was used. Nos. .1 to No.5 have no such poor conduction at all, and have obtained results showing good heat resistance.

In addition to the main agent described in the above embodiment, it is also possible to use a main agent composed of a mixture of, for example, a naphthalene-based epoxy resin and two epoxy resins of bisphenol A type and bisphenol F type. The results equivalent to those of the above-described examples are obtained in terms of the electrolytic corrosion resistance and the heat resistance.

Further, a main agent composed of 100 parts by weight of a naphthalene-based epoxy resin alone, or 50 parts by weight or 100 parts by weight of a bisphenol A type epoxy resin with respect to 100 parts by weight of a naphthalene-based epoxy resin, or Although an example in which a main agent mixed with a bisphenol F type epoxy resin is used has been described, the present embodiment is not limited to such an example.

For example, 100 parts by weight of bisphenol A
1 part by weight of a naphthalene-based epoxy resin with respect to a type epoxy resin or a bisphenol F type epoxy resin,
Alternatively, the imidazole microcapsule type curing agent is mixed with 50 parts by weight per 100 parts by weight of the main agent, respectively, and mixed with two types of main agents in which 5 parts by weight are mixed, and further added with silica (SiO ₂ ) powder. Each of the anisotropic conductive adhesives prepared by adding and dispersing a microcapsule-type filler for imparting conductivity to the same amount as shown in Table 1 above was used for various property tests performed in the above Examples. As a result of the same test, the glass transition point was found to be 140 ° C. for the anisotropic conductive adhesive using 1 part by weight of the naphthalene-based epoxy resin, and 5 parts by weight for the anisotropic conductive adhesive. The temperature of the conductive adhesive was 150 ° C.

In the time-dependent changes in viscosity and in the electrolytic corrosion test, the same results as the test results of the above-mentioned Examples were obtained with the anisotropic conductive adhesives using any of the base agents. In the temperature cycle test, test sample 5 was used for an anisotropic conductive adhesive using a base material containing 1 part by weight of a naphthalene-based epoxy resin.
Eleven of the 0 sheets suffered from poor conduction due to thermal degradation of the resin material, but no such poor conduction was observed with an anisotropic conductive adhesive using 5 parts by weight of the base material. It was confirmed that heat resistance was obtained.

From the above test results, it is desirable that the mixing amount of the naphthalene epoxy resin with respect to 100 parts by weight of the bisphenol A type epoxy resin or bisphenol F type epoxy resin is 5 parts by weight or more.

Further, in the above-mentioned embodiment, 100
Although an example in which 50 parts by weight of imidazole microcapsule type curing agent is mixed with respect to parts by weight has been described, the present embodiment is not limited to such an example, and for example, the imidazole microcapsule is used. The mixing amount of the mold curing agent with respect to 100 parts by weight of the main agent is 1 part by weight,
5 parts by weight, 100 parts by weight, and 110 parts by weight were mixed and mixed. Other additives made of silica (SiO ₂ ) powder and microcapsule type filler for imparting conductivity were added in the amounts shown in Table 1 above. As a result of performing the same tests as the various property tests performed in the above examples for each anisotropic conductive adhesive prepared by adding the same amount, the curing agent for the main agent was 1 part by weight and 110 parts by weight. Each of the mixed anisotropic conductive adhesives is not completely cured due to an insufficient or excessive mixing amount of the curing agent, and becomes a rubber-like semi-cured material. However, with each anisotropic conductive adhesive obtained by mixing 5 parts by weight and 100 parts by weight of the curing agent for the main agent, a good result equivalent to the test result of the above-described embodiment was obtained. The mixing amount of the agent is desirably 5 to 100 parts by weight.

Further, in the above-described embodiment, an example was described in which an additive consisting of 40 wt% silica (SiO ₂ ) powder was added to each base material, but this embodiment is not limited to such an example. Not silica, for example
The additive amount of the additive consisting of (SiO ₂ ) powder is 1 wt%, 5 wt%
%, 80% by weight, and 90% by weight, and other imidazole-based microcapsule-type curing agents are mixed at a ratio of 50 parts by weight per 100 parts by weight of the base material, and further microcapsules for imparting conductivity. As a result of performing the same tests as the various property tests performed in the above examples for the anisotropic conductive adhesive prepared by adding and dispersing the mold filler in the same amount as shown in Table 1 above, Adding as much as 90% by weight of an additive composed of silica (SiO ₂ ) powder to the base material makes it difficult to produce an adhesive due to excessive addition.

In addition, in each anisotropic conductive adhesive in which an additive composed of silica (SiO ₂ ) powder was added to the main component in the amounts of 1 wt%, 5 wt%, and 80 wt%, the glass transition performed in the above-described embodiment was performed. The results equivalent to the results of the point, the change of viscosity with time and the electrolytic corrosion test were obtained.

Each of the anisotropic conductive adhesives containing 5 wt% and 80 wt% of an additive composed of silica (SiO ₂ ) powder with respect to the above-mentioned base material was subjected to the same temperature cycle test as the test results of the above-described embodiment. Although good results were obtained, in the anisotropic conductive adhesive to which 1% by weight of the additive was added, conduction failure due to thermal deterioration of the resin material occurred in three of the 50 test samples in this temperature cycle test. .

According to the test results, the amount of the additive composed of silica (SiO ₂ ) powder to the above-mentioned base material was 5 to 80.
wt%, and silica (SiO
₂ ) Instead of powder, alumina (Al ₂ O ₃ ), silicon carbide (SiC),
Even if a powder such as silicon nitride (Si ₃ N ₄ ) is used, the glass transition point of the anisotropic conductive adhesive, the change with time of viscosity, the electric corrosion resistance by an electric corrosion test and the heat resistance by a temperature cycle test are as described above. A good result equivalent to that of the working example obtained is obtained.

Further, for example, Cl ⁻ , Na contained in the sample No. 1, No. 2, No. 3, No. 3, No. 5 of the anisotropic conductive adhesive described above.
⁺ , K ^+, etc. The total amount of impurity ions
pm and the same glass transition point as described above using those contained in 60 ppm, the results of a change in viscosity over time, an electrolytic corrosion test and a heat cycle test, and any anisotropic conductive adhesive Regardless of the difference in the total amount of impurity ion concentration, in the glass transition point, the time-dependent change in viscosity and the heat cycle test, the glass transition point does not change and there is almost no time-dependent change in the viscosity as in the above-described examples, and the temperature cycle test is performed. As a result, good results were obtained in which no conduction failure occurred due to thermal degradation or the like in any of the samples.

However, in the electrolytic corrosion test, in each sample of the anisotropic conductive adhesive containing the total amount of impurity ions at 60 ppm, the insulation resistance dropped to 10 ⁸ Ω or less after 60 hours, causing insulation failure. On the other hand, it was confirmed that each sample of the anisotropic conductive adhesive containing the impurity ion concentration of 50 ppm had the electrolytic corrosion resistance such that there was almost no change in the insulation resistance immediately after the production and after 200 hours.

Therefore, from the measurement results of the various tests in each of the above examples, the main agent in the anisotropic conductive adhesive of the present invention was a simple naphthalene epoxy resin or a bisphenol A type or a bisphenol F type. The naphthalene-based epoxy resin is 5 parts by weight or more based on 100 parts by weight of the epoxy resin, and the microcapsule-type curing agent is mixed in an amount of 5 to 100 parts by weight based on 100 parts by weight of the main agent.
Similarly, the additive amount of the additive such as silica (SiO ₂ ) powder is 5
~ 80wt%, total amount of impurity ion concentration is 50p
pm or less is optimal, and it is possible to reduce the coefficient of expansion of the adhesive, and to enhance the excellent heat resistance and electric corrosion resistance.

Therefore, it is possible to realize reliable electrical bonding and reliable fixing between the printed circuit board and the functional element that generates a relatively large amount of heat during operation. In addition, it can be applied to a joining process of components of a component component used at a relatively high temperature, which is extremely advantageous.

[0053]

As is apparent from the above description, according to the adhesive of the present invention, the glass transition point can be improved, the heat resistance and the electrolytic corrosion resistance can be improved, and the low expansion due to the addition of the additive can be achieved. Since the substrate can be brought closer to the material to be bonded, such as a substrate or various elements, the thermal expansion and thermal shrinkage are alleviated, and the distortion at the bonding interface, a decrease in bonding property and peeling are suppressed,
The bonding of the material to be bonded such as a functional element to the substrate becomes stable.

Therefore, even if the above-mentioned adhesive is applied to the bonding of various elements generating a large amount of heat, the bonding can be stabilized, and the mounting substrate or the like after the bonding of the various elements can be used.
It is possible to sufficiently cope with a reliability test performed under a high temperature condition of about 0 ° C., and good bonding stability can be obtained.

Further, miniaturization of an anisotropic conductive adhesive in which a capsule type filler in which conductive particles are coated with an insulating resin is added to the composition of the adhesive having good bonding stability is promoted. The present invention is extremely advantageous when applied to fine pitch connection between an integrated circuit chip and a mounting substrate, and has a practically excellent effect.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor ▲ Toku ▼ Eiji 4-1-1 1-1 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Inside Fujitsu Limited (72) Inventor Makoto Usui Upper Nakahara-ku, Kawasaki-shi, Kanagawa 4-1-1 Odanaka Fujitsu Limited

Claims (2)

[Claims] An adhesive characterized in that it comprises a main agent comprising a naphthalene epoxy resin or a mixture comprising a mixture of a naphthalene epoxy resin and at least one bisphenol A type or bisphenol F type epoxy resin. . 2. A main agent comprising a naphthalene-based epoxy resin or a mixture of a naphthalene-based epoxy resin and at least one bisphenol A-type or bisphenol F-type epoxy resin, and a hardening substance comprising a thermoplastic resin. An adhesive comprising: a coated capsule-type curing agent; an additive; and a capsule-type filler in which conductive particles are coated with an insulating resin.