JP2002161259A - Electro-conductive adhesive, electronics packaging structure, and method for fabricating electronics packaging structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a anelectronics packaging structure which hardly causes ion migration and sulfuration. SOLUTION: This electro-conductive adhesive comprises a binder resin 2, electro-conductive particles 3, and an elution-preventing film-forming agent 4, characterized in that the elution-preventing film-forming agent 4 reacts after the development of electric conduction through the electro-conductive particles 3 in the electro-conductive adhesive on the curing of the binder resin 2 to form an elution-preventing film 5 on the surface of the electro-conductive particles 3. The employment of the electro-conductive adhesive gives the electronics packaging structure which hardly causes ion migration and sulfuration.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to the present invention. The present invention relates to a conductive adhesive used for bonding an electronic component and a circuit board, a mounting structure using the conductive adhesive, and a method of manufacturing the mounting structure in the field of mounting electronic components.

[0002]

2. Description of the Related Art In recent years, in the field of electronic packaging, restrictions on lead in solder alloys have been regulated due to increasing awareness of environmental harmony, and lead-free packaging technology, that is, electronic materials using lead-free materials, has been developed. There is an urgent need to establish a technology for joining parts.

[0003] As a lead-free mounting technique, mounting using lead-free solder and a conductive adhesive can be cited. However, in recent years, much attention has begun to be paid to conductive adhesives, which are expected to have advantages such as flexibility of bonding portions and lower mounting temperature.

[0004] The conductive adhesive is generally one in which conductive particles are dispersed in a resin-based adhesive component. The components are mounted by applying a conductive adhesive to the electrodes of the substrate, mounting the components, and then curing the resin. By this step, the bonding portion is bonded with the resin, and the conductive particles come into contact with each other due to the shrinkage of the resin, so that the conduction of the connecting portion is ensured.

The curing temperature of the conductive adhesive resin is 150 ° C.
And a melting temperature of about 240 ° C., which is extremely low as compared with a solder that requires a melting temperature, so that a conductive adhesive can be used even for inexpensive components having low heat resistance.

In addition, since the joint is bonded with a resin, it can flexibly cope with deformation due to heat or external force. Therefore, compared to solder where the joint is an alloy,
The conductive adhesive has a merit that a crack is not easily generated in the joint.

For the above reasons, conductive adhesives are expected as a substitute for solder.

[0008]

The silver which is generally used for the conductive particles of the conductive adhesive has a feature that it easily undergoes ion migration and sulfuration. This has been a problem when the agent is used as a solder substitute material.

First, ion migration will be described. Ion migration is a kind of electrolytic action, and is a phenomenon in which, when an electrolyte such as water exists between electrodes to which a voltage is applied, dielectric breakdown occurs between the electrodes in the following four steps.

Step 1) Elution and ionization of anode metal Step 2) Movement of ionized metal toward cathode by applying voltage Step 3) Precipitation of metal ions transferred to cathode Step 4) Repeat steps 1) to 3) Due to such ion migration, the metal grows between the electrodes in a dendritic manner, and finally the metal is bridged between the electrodes, causing dielectric breakdown.

Silver used as the conductive filler of the conductive adhesive has a property of easily dissolving, and easily causes ion migration. Furthermore, with the further reduction in size and weight of electronic devices in recent years, the pitch of electrodes provided on semiconductor devices, electronic components, or circuit boards has become narrower, and ion migration has been more and more likely to occur. Therefore, the solution of ion migration is indispensable for practical use of conductive adhesive mounting.

Conventionally, the following three methods have been proposed as methods for suppressing ion migration.

Proposal 1: Alloying of conductive filler (silver-
Proposal 2 Encapsulation of conductive adhesive with insulating resin such as epoxy resin Proposal 3 Dissolution of metal by adding ion-trapping agent such as ion exchange resin or chelating agent to conductive adhesive However, these proposals have the following disadvantages. In Proposal 1, the filler metal becomes very expensive, raising the cost of the conductive adhesive. In Proposal 2,
The addition of the sealing step requires an increase in man-hours and a large increase in equipment, thereby raising manufacturing costs. Proposal 3 dissolves metal ions from the conductive filler, thereby lowering the contactability of the conductive filler and causing an increase in connection resistance.

As described above, each of the above proposals has an effect of suppressing ion migration, but has other problems, so that it is difficult to put it to practical use except in special fields.

Next, the sulfidation phenomenon will be described. The sulfidation phenomenon refers to a phenomenon in which a metal reacts with a weakly acidic gas containing sulfur such as hydrogen sulfide or sulfur dioxide to change into a substance having low conductivity called a metal sulfide. Although there are many unclear parts, the sulfurization phenomenon is thought to occur in the following steps.

Step 1) Elution and ionization of metal in a weakly acidic atmosphere Step 2) Formation of metal sulfide by reaction between sulfur ions and metal ions As described above, the conductive filler mainly contains silver as a main component. However, since silver is a metal that is easily sulfided, when silver is sulfided, the volume specific resistance of the conductive adhesive increases, and accordingly, the connection resistance increases. Very few solutions to this problem have been reported so far, especially for electronic component products that may be used in environments with relatively high concentrations of hydrogen sulfide and sulfur dioxide, such as around hot springs and volcanoes. Cannot apply a mounting structure using a conductive adhesive. Therefore, the application field of the mounting structure using the conductive adhesive is largely limited.

Accordingly, a main object of the present invention is to maintain the reliability of a mounting structure using a conductive adhesive even under relatively severe conditions such as a humid condition and a gas atmosphere containing sulfur. It is to be.

[0018]

In order to achieve the above-mentioned object, a conductive adhesive according to the present invention comprises a binder resin, conductive particles and an elution-preventing film-forming agent. Reacts after electrical conduction through the conductive particles is developed inside the conductive adhesive during curing of the binder resin, and forms an elution preventing film on the surface of the conductive particles. There is. This brings about the following.

By coating the surface of the conductive particles with the elution preventing film, the conductive particles can be protected from being eluted even under high temperature and high humidity or in a gas containing sulfur. Therefore, the elution preventing film can prevent ion migration and also can prevent the first step of sulfurization described above. Thus, when the conductive adhesive of the present invention is used, it is possible to manufacture a mounting structure in which ion migration and sulfuration hardly occur.

Here, when the elution prevention film is made of an insulating material, the portions involved in conduction (the contact points between the conductive particles and the contact points between the conductive particles and the electrodes). When the elution preventing film is present, the electrical conduction is hindered and the connection resistance of the mounting structure is increased.

On the other hand, the conductive adhesive of the present invention
In the uncured state of the conductive adhesive, the elution preventing film is not formed on the surface of the conductive particles, and in the curing step, after the conductive particles come into contact with each other to exhibit conduction, the elution preventing film is formed on the surface of the particles. It is formed. For this reason, the elution preventing film is not formed at a portion involved in conduction, and the connection resistance does not increase.

On the other hand, if the above requirements of the present invention are not satisfied, the object of the present invention cannot be realized. That is, before the conduction is developed, that is, when the elution prevention film is formed on the surface of the conductive particles in an uncured state, at the time of curing the conductive adhesive, the elution prevention film is present at a site involved in the conduction. This hinders the electrical conduction of the mounting structure and increases the connection resistance.

In the conductive adhesive of the present invention, the reaction temperature of the elution-preventing film-forming material is as follows: the application temperature of the conductive adhesive <the reaction temperature of the elution-preventing film-forming material. It is preferable to satisfy the condition of the curing temperature. Then, the following will appear.

When the conductive adhesive of the present invention is applied, no elution preventing film is formed. And when heated to the curing temperature to cure the conductive adhesive, the elution prevention film forming agent reacts in a temperature range before curing,
An elution preventing film is formed on the conductive particles. At this time, since the binder resin has not yet been cured, it does not hinder the formation of the elution prevention film. Therefore, the elution preventing film is formed evenly on the entire surface of the conductive particles except for the contact points between the conductive particles and other conductive substances (other conductive particles, electrodes, etc.). Then, after the elution preventing film is formed, when the temperature reaches the curing temperature of the conductive adhesive, the binder resin is cured, and the connection and fixing by the conductive adhesive are completed.

In the conductive adhesive of the present invention, the elution-preventing film-forming agent contains a chelating agent, and the chelating agent is used when the binder resin is cured through the conductive particles. It is preferable that the conductive particles be reacted after the electrical conduction develops inside the conductive adhesive to form an elution preventing film containing a metal complex on the surface of the conductive particles. Then, the following will appear.

When the elution-preventing film-forming agent contains a chelating agent, an elution-preventing film containing a very stable substance called a metal complex is formed on the conductive particles. Therefore, even if the connection site made of the conductive adhesive is left in a high-temperature and high-humidity environment or a gas containing sulfur, the conductive particles do not elute.

Further, since the metal complex is an insulating substance,
If a metal complex is present at a site involved in conduction (a contact point between conductive particles and a contact point between a conductive particle and an electrode), electrical conduction is hindered, and the connection resistance of the mounting structure increases. . In contrast, the conductive adhesive of the present invention is:
In the uncured state of the conductive adhesive, no metal complex is formed on the surface of the conductive particles, and in the curing step, after the conductive particles come into contact with each other to exhibit conduction, elution including the metal complex on the particle surface is performed. A barrier film is formed. As described above, the elution preventing film containing the metal complex is not formed at a portion involved in conduction, and the connection resistance does not increase.

In the case where a chelating agent is contained in the elution-preventing film-forming agent in the conductive adhesive of the present invention, the activation temperature of the chelating agent is as follows: the application temperature of the conductive adhesive <the temperature of the chelating agent. Activation temperature It is preferable to satisfy the following condition: activation temperature of the chelating agent ≦ curing temperature of the binder resin. Then, the following will appear.

A chelating agent is a material that selectively reacts with a metal to form a metal complex. This reaction is most likely to occur at the activation temperature of the chelating agent, and the activation temperature depends on the conductive adhesive. Since the temperature is higher than the application temperature of the agent and lower than the curing temperature of the binder resin, the reaction takes place at a temperature between the application temperatures to form an elution prevention film containing a metal complex on the surface of the conductive particles. Therefore, when the conductive adhesive is in an uncured state, the chelating agent is dispersed in the conductive adhesive, and the elution preventing film is hardly formed on the surface of the conductive particles. Then, in the curing step, the chelating agent reacts with the conductive particles to form an elution preventing film containing a metal complex on the surface of the particles. This elution preventing film serves as a protective film for the conductive particles and suppresses ion migration and sulfuration. In addition, since the formation of the elution preventing film occurs after the occurrence of conduction, the elution preventing film (metal complex) is hardly formed at a part involved in the conduction, and the connection resistance is unlikely to increase.

Here, the activation temperature (reaction temperature) means the temperature at which the reaction between the chelating agent and the metal occurs most frequently, and is usually around the melting point. Note that the relationship between the reaction between the chelating agent and the metal and the temperature is non-linear, and has a property that the reaction is rapidly activated at the activation temperature, and is near the activation temperature. The reaction hardly occurs in the temperature range outside the range.

The application temperature of the conductive adhesive refers to a working temperature at the time of applying the conductive adhesive on the substrate electrode by printing or dispensing in order to manufacture a mounting structure. Usually, the temperature is around room temperature of about 20 ° C to 40 ° C.

When a chelating agent having an activation temperature higher than the curing temperature of the binder resin (for example, bismuthiol II having a melting point of 246 ° C. when the curing temperature is 150 ° C.) is used, the chelating agent remains conductive even after curing. Since it does not react with the reactive particles and does not form a metal complex, the effect of ion migration resistance and the effect of sulfuration resistance cannot be obtained.

Since the activation temperature is often near the melting point, the chelating agent may be, for example, an anthranilic acid (C) at a coating temperature of 25 ° C. and a curing temperature of 150 ° C. Melting point 145 ° C), thionalide (2
17 ° C.), pyrogallol (132 ° C.) and the like.

In the conductive adhesive of the present invention, the elution-preventing film-forming agent is encapsulated in microcapsules, and the melting temperature of the microcapsules and the activation temperature of the chelating agent contained in the elution-preventing film-forming material. It is preferable that the following condition is satisfied: conductive adhesive application temperature <microcapsule melting temperature microcapsule melting temperature ≦ binder resin curing temperature Chelating agent activation temperature ≦ binder resin curing temperature. This not only suppresses an increase in the connection resistance of the mounting structure after curing, but also widens the range of choice of the chelating agent. The reason will be described below.

In this improvement, the reaction of the chelating agent in the uncured state is more reliably suppressed by adding the chelating agent to the conductive adhesive in a state of being encapsulated in the microcapsules. Hereinafter, the reason will be described.

In the structure of the present invention, since the activation temperature of the chelating agent is higher than the application temperature of the conductive adhesive, the reactivity of the chelating agent is low when the binder resin is in an uncured state. However, moisture, hardeners (amines, acid anhydrides, etc.), residual impurities (chlorine, etc.) during the production of the binder resin, etc., act as reaction accelerators, and actually react slightly even in an uncured state to form a conductive material. An anti-elution film containing a metal complex is formed on the surface of the conductive particles.

On the other hand, in the conductive adhesive of the present invention improved as described above, since the chelating agent is protected by the microcapsules, the reaction of the chelating agent does not occur when the binder resin is not cured. Rarely occurs. Then, in the step of curing the binder resin, the microcapsules melt and release the chelating agent, so that the chelating agent reacts with the conductive particles to form an elution preventing film containing a metal complex. As described above, in the present invention having the above-described improvement, the degree of formation of the elution preventing film (metal complex) in the uncured state of the binder resin is further reduced, so that the connection resistance of the conductive adhesive after curing is increased. Is surely suppressed. Furthermore, since the activation temperature of the chelating agent may be lower than the application temperature of the conductive adhesive, the range of characteristics (especially, activation temperature) required for the chelating agent is widened, and the chelating agent can be used accordingly. The range of chelating agents that can be selected will be expanded.

[0038] In the conductive adhesive of the present invention, the elution-preventing film-forming agent is preferably composed of a water-insoluble substance. Then, the following will appear.

The anti-elution film once formed does not dissolve out under high-temperature and high-humidity conditions, so that the ion migration resistance is enhanced. Here, insoluble means solubility (100 g of water)
Is less than 1 × 10 ⁻⁵ g.

In the conductive adhesive of the present invention, the elution-preventing film-forming agent is preferably composed of a substance insoluble in an aqueous solution containing hydrogen sulfide or sulfur oxide. Then, the following will appear. That is, since the once formed elution prevention film does not dissolve even in a weakly acidic aqueous solution containing sulfur or in an atmosphere, the ion migration resistance and the sulfuration resistance are enhanced.

In the conductive adhesive of the present invention, it is preferable that the elution preventing film forming agent is added to the conductive adhesive in a state of being dispersed in a non-polar solvent. Then, the following will appear.

Since the non-polar solvent has a function of suppressing the reaction of the chelating agent, in the conductive adhesive of the present invention having the above-mentioned improvement, when the binder resin is not cured, the reaction of the chelating agent does not occur. Hardly occurs. And
In the step of curing the binder resin, the chelating agent reacts with the conductive particles to form an elution preventing film containing a metal complex. As described above, in the present invention having the above-described improvement, the degree of formation of the elution preventing film (metal complex) in the uncured state of the binder resin is further reduced, so that the connection resistance of the conductive adhesive after curing is increased. Is surely suppressed. Furthermore, the activation temperature of the chelating agent is
Since the temperature may be lower than the application temperature of the conductive adhesive, the range of characteristics (especially, activation temperature) required for the chelating agent is widened, and accordingly, the range of selection of the chelating agent that can be used is widened. Become.

According to another aspect of the present invention, there is provided a mounting structure having an electric structure and a conductive adhesive layer provided on the electric structure. Has a configuration in which conductive particles are contained, and the contact points between the conductive particles and the contact points between the conductive particles and the electric structure are covered with an elution preventing film.

As a result, the ion migration resistance is improved. This is because the elution preventing film serving as a protective film against ion migration is formed in a required portion, that is, a portion other than a portion involved in conduction.

The mounting structure has another electric structure disposed on the electric structure, and the conductive adhesive layer electrically connects the other electric structure to the electric structure. In this case, the influence on the connection resistance due to the ion migration reaction or the like becomes significant.
Therefore, if the present invention is implemented in such a configuration, the effect is particularly large.

In the mounting structure of the present invention, it is preferable that the elution preventing film is made of a material containing a metal complex. Then, the following will appear. In other words, in order to form an elution prevention film containing a very stable substance called a metal complex on the conductive particles, the connection portion of the conductive adhesive is left in a high-temperature and high-humidity environment or a gas containing sulfur. Also, the conductive particles are not eluted.

Since the metal complex is an insulating substance,
If a metal complex is present at a site involved in conduction (a contact point between conductive particles and a contact point between a conductive particle and an electrode), electrical conduction is hindered, and the connection resistance of the mounting structure increases. . On the other hand, in the mounting structure of the present invention in which the above-described improvement has been made, the metal complex is not formed in a portion involved in conduction, so that the connection resistance does not increase.

In the mounting structure of the present invention, it is preferable that the elution preventing film is made of a water-insoluble substance. Then, the anti-elution film once formed does not dissolve out under high-temperature and high-humidity conditions, so that the ion migration resistance is improved.

In the mounting structure of the present invention, it is preferable that the elution preventing film is made of a substance which is insoluble in an aqueous solution containing hydrogen sulfide or sulfur oxide. Then, the following will appear. That is, since the once formed anti-elution film does not dissolve in a weakly acidic aqueous solution containing sulfur or in an atmosphere, the ion migration resistance and the sulfidation resistance are improved.

As a method of manufacturing such a mounting structure of the present invention, there are first and second methods described below.

In the first method, a binder resin, conductive particles, and an elution-preventing film-forming material are contained as the conductive adhesive, and the reaction temperature of the elution-preventing film-forming material is set to a value of the conductive adhesive. A coating material that satisfies the condition of application temperature <reaction temperature of elution-preventing film-forming material reaction temperature of elution-preventing film-forming material ≦ curing temperature of binder resin is prepared, and the conductive adhesive is applied on the electrode at the application temperature. A conductive adhesive forming step to be applied and formed, and heating the conductive adhesive until the curing temperature is reached, and reacting the elution preventing film forming agent at the reaction temperature that reaches the temperature during the heating, The method includes a step of forming an anti-elution film on the conductive particles, and a curing step of heating the conductive adhesive to the curing temperature to cure the binder resin.

The second method comprises a binder resin, conductive particles, and an elution-preventing film-forming agent as a conductive adhesive, and the reaction temperature of the elution-preventing film-forming agent is determined by the curing temperature of the binder resin. <Preparing a material that satisfies the condition of the reaction temperature of the elution-preventing film-forming agent, and then forming a layer of the conductive adhesive on the electrode in an uncured state; Curing step of heating the binder to the curing temperature to cure the binder resin,
An anti-elution film forming step of reacting the anti-elution film forming agent by reheating the conductive adhesive to a temperature equal to or higher than the reaction temperature to form an anti-elution film on the conductive particles And a method that includes

According to these manufacturing methods, the following is manifested.

That is, when the conductive adhesive of the present invention is applied, no elution preventing film is formed. When the conductive adhesive is heated to the curing temperature in order to cure, the elution-preventing film-forming agent reacts in a temperature range before curing to form an elution-preventing film on the conductive particles. At this time, since the binder resin has not yet been cured, it does not hinder the formation of the elution prevention film. Therefore, the elution preventing film is formed evenly on the entire surface of the conductive particles except for the contact points between the conductive particles and other conductive substances (other conductive particles, electrodes, etc.). Then, after the elution preventing film is formed, when the temperature reaches the curing temperature of the conductive adhesive, the binder resin is cured, and the connection and fixing by the conductive adhesive are completed.

According to the second method, an increase in the connection resistance of the mounting structure can be suppressed more accurately. The reason will be described.

Since the reaction temperature of the anti-elution film-forming agent is higher than the curing temperature of the binder resin, the anti-elution film-forming agent is applied to the surface of the conductive particles when the conductive adhesive is not cured and in the curing step. , And therefore good conduction is developed. Then, after the binder resin is cured, by heating again at a temperature higher than the reaction temperature of the anti-elution film forming agent, the anti-elution film is formed only in portions not involved in conduction. Therefore, the connection resistance of the cured mounting structure can be reliably reduced.

Further, in the first method described above, a chelating agent is contained as the elution-preventing film forming agent, and the activation temperature of the chelating agent is such that the application temperature of the conductive adhesive <the chelating agent An activation temperature of a chelating agent is prepared.A temperature that satisfies the condition of activating temperature ≦ curing temperature of binder resin is prepared, and in the elution prevention film forming step, the conductive adhesive is heated until the curing temperature is reached. Preferably, the chelating agent is reacted at the activation temperature that reaches the temperature during the heating to form an elution prevention film containing a metal complex on the conductive particles. Then, the following will appear.

A chelating agent is a material that selectively reacts with a metal to form a metal complex, and this reaction is most likely to occur at the activation temperature of the chelating agent. In this improved production method, a chelating agent is contained, and the activation temperature is equal to or higher than the application temperature of the conductive adhesive and equal to or lower than the curing temperature of the binder resin. Therefore, the chelating agent reacts at a temperature between the application temperature of the conductive adhesive and the curing temperature of the binder resin to form an elution preventing film containing a metal complex on the surface of the conductive particles. Therefore, when the conductive adhesive is in an uncured state, the chelating agent is dispersed in the conductive adhesive, and the elution preventing film is hardly formed on the surface of the conductive particles. Then, in the curing step, the chelating agent reacts with the conductive particles to form an elution preventing film containing a metal complex on the surface of the particles. This elution preventing film serves as a protective film for the conductive particles and suppresses ion migration and sulfuration.
In addition, since the formation of the elution preventing film occurs after the occurrence of conduction, the elution preventing film (metal complex) is less likely to be formed at a site involved in conduction, and the connection resistance is less likely to increase.

In the above-mentioned second method, an agent containing a chelating agent having an activation temperature higher than the curing temperature of the binder resin is used as the elution-preventing film-forming agent. In a heat treatment at a temperature lower than the temperature, the binder resin is cured, and in the elution prevention film forming step, the chelating agent is reacted by reheating at a temperature equal to or higher than the activation temperature. It is preferable to form an elution preventing film containing a metal complex on the conductive particles. Then, a film containing a metal complex can be formed as the elution preventing film.

In the first and second methods described above, as the elution-preventing film-forming agent, a material in which the elution-preventing film-forming agent is encapsulated in a microcapsule is used. The activation temperature of the chelating agent contained in the film is as follows: conductive adhesive application temperature <microcapsule melting temperature microcapsule melting temperature ≦ binder resin curing temperature chelating agent activation temperature ≦ binder resin curing It is preferable to satisfy the temperature condition, so that the range of choice of the conductive adhesive is expanded. The reason will be described.

Since the melting temperature of the microcapsules is higher than the curing temperature of the conductive adhesive, the dissolution preventing film forming agent does not form the dissolution preventing film on the surface of the conductive particles when the binder resin is not cured or during the curing step. And good conduction is developed. Then, after the binder resin is cured, by reheating at a temperature higher than the melting temperature of the microcapsules, the elution-preventing film-forming agent is released from the microcapsules, and the elution-preventing film-forming agent elutes only in portions not involved in conduction. Forming a barrier film; Therefore, the connection resistance of the mounted structure after curing can be reduced more reliably. Further, since there is no need to set the reaction temperature of the elution-preventing film-forming agent higher than the curing temperature of the binder resin, the range of choice of the elution-preventing film-forming agent is expanded.

In the first and second methods described above, a conductive adhesive obtained by adding the elution-preventing film-forming agent dispersed in a nonpolar solvent to the conductive adhesive is used. Is preferred. Then, the following will appear.

Since the non-polar solvent has a function of suppressing the reaction of the chelating agent, if the elution preventing film-forming agent is added to the conductive adhesive in a state of being dispersed in the non-polar solvent,
When the binder resin is in an uncured state, the reaction of the chelating agent hardly occurs. Then, in the step of curing the binder resin, the chelating agent reacts with the conductive particles to form an elution preventing film containing a metal complex. Therefore, the degree of formation of the elution preventing film (metal complex) in the uncured state of the binder resin is further reduced, and the increase in connection resistance in the cured conductive adhesive is reliably suppressed. Furthermore, since the activation temperature of the chelating agent may be lower than the application temperature of the conductive adhesive, the range of characteristics (especially, activation temperature) required for the chelating agent is widened, and the chelating agent can be used accordingly. The range of chelating agents that can be selected will be expanded.

Examples of materials that can be used in each of the inventions described above are shown below.

As the binder resin, almost all resins that can be obtained relatively easily can be used. For example, as the thermosetting resin, an epoxy resin, a phenol resin, a urea resin, a melamine resin, a furan resin, an unsaturated resin polyester resin, a diallyl phthalate resin, a silicon resin, and the like can be used. As the thermoplastic resin, vinyl chloride resin, vinylidene chloride resin, polystyrene, ionomer, methylpentene resin, polyallomer, fluororesin, polyamide, polyimide, polyamideimide, polycarbonate, modified polyphenylene oxide, polyphenylene sulfide, and the like can be used. .

The constituent materials of the microcapsules include relatively easily available thermoplastic resins, for example, vinyl chloride resin, vinylidene chloride resin, polystyrene, ionomer, methylpentene resin, polyallomer, fluororesin, polyamide, polyimide, polyamideimide. , Polycarbonate, modified polyphenylene oxide, polyphenylene sulfide, and the like. As described above, the melting temperature of the microcapsules can be freely adjusted by adjusting the resin molecular weight and the thickness of the microcapsules.

Although the present invention sets the above-mentioned various requirements for the conductive adhesive and the mounting structure, the object of the present invention cannot be realized unless the above-mentioned requirements of the present invention are adopted. This will be described below.

When the melting point of the microcapsules is lower than the application temperature of the conductive adhesive, the microcapsules are melted in an uncured state, and the elution-preventing film-forming agent is released to form an elution-preventing film on the surface of the conductive particles. Therefore, the connection resistance of the mounted structure after curing is increased.

When the melting point of the microcapsules is higher than the curing temperature, the elution-preventing film-forming agent does not react with the conductive particles even after the curing, and the elution-preventing film is not formed. I can't.

As the elution preventing film forming agent to be added to the conductive adhesive, a chelating agent having an activation temperature higher than the curing temperature (for example, when the curing temperature is 150 ° C., the melting point is 24
When a material containing bismuthol II) at 6 ° C. as a main component is used, the anti-elution film-forming agent does not react with the conductive particles even after curing, and the anti-elution film is not formed. I can't get it.

[0071]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) In this embodiment,
The present invention is implemented in a conductive adhesive. FIG.
1A to 1C are enlarged views of a main part of the conductive adhesive according to the present embodiment. FIG. 1A shows an uncured state, FIG.
(B) is a state in which conduction is developed in the curing step, FIG.
(C) shows a state where the curing is completed. In FIG. 1A, a conductive adhesive 1 is formed by mixing and dispersing conductive particles 3 and an elution-preventing film-forming agent 4 containing a chelating agent as a main component in a liquid binder resin 2. I have. In FIG. 1B, which is a curing step, the semi-cured binder resin 2
Inside, the conductive particles 3 exist in a state of being in contact with each other,
The elution-preventing film-forming agent 4 is still dispersed. FIG.
In (C), the conductive particles 3 are present in the cured binder resin 2 in a state of being in contact with each other, and the non-contacted portion is covered with an elution preventing film 5 containing a metal complex as a main component.

The following can be used as the binder resin 2. That is, as the thermosetting resin, an epoxy resin, a phenol resin, a urea resin, a melamine resin, a furan resin, an unsaturated resin polyester resin, a diallyl phthalate resin, a silicon resin, or the like can be used. As the thermoplastic resin, vinyl chloride resin, vinylidene chloride resin, polystyrene, ionomer, methylpentene resin, polyallomer, fluororesin, polyamide, polyimide, polyamideimide, polycarbonate, modified polyphenylene oxide, polyphenylene sulfide, and the like can be used. .

When the application temperature of the conductive adhesive 1 is 25 ° C. and the curing temperature is 150 ° C., the chelating agent as the main component of the elution preventing film forming agent 4 is anthranilic acid (melting point: 143).
° C ≒ activation temperature), pyrogallol (132 ° C).

The conductive particles 3 include, in addition to Ag,
Au, Cu coated with Ag, Cu-Ag alloy, Cu,
Ni, Ag-Pd alloy or the like may be used. However, Ag is preferable in consideration of the volume resistivity and the material cost.

(Second Embodiment) In the present embodiment, the present invention is implemented in a flip-chip mounting structure of a semiconductor device. As shown in FIG. 2, the mounting structure includes a circuit board 6 which is an example of an electric structure, and a semiconductor device 7 which is an example of another electric structure. The semiconductor device 7 includes an IC substrate 8 and a bump electrode 9 provided on a surface of the IC substrate 8. The circuit board 6 has input / output terminal electrodes 10 on its surface. A conductive adhesive layer 1A made of the conductive adhesive 1 described in the first embodiment is provided on the input / output terminal electrode 10, and the input / output terminal electrode is formed by the conductive adhesive layer 1A. 10 and the bump electrode 9 are electrically connected. Further, the sealing resin 11 is provided in the gap between the semiconductor device 7 and the circuit board 6, and thus constitutes a flip-chip mounting structure.

(Third Embodiment) In the present embodiment,
The present invention is embodied in a chip component mounting structure. As shown in FIG. 3, in this mounting structure, a chip resistor 14, a chip coil 15, and a chip capacitor 16, which are examples of another electric structure, are provided on the electrodes 13 of a circuit board 12, which is an example of an electric structure. It is implemented and configured. The electrode 13 is provided with a conductive adhesive layer 1A made of the conductive adhesive 1 described in the first embodiment. The conductive adhesive layer 1A allows the electrode 13 and the chip components 14 to be formed. , 15, and 16 are electrically connected.

An example of each of the above embodiments will be described.

First, the first embodiment (conductive adhesive)
Each embodiment of the invention will be described.

Example 1 In this example, in the conductive adhesive 1 shown in the first embodiment, the elution-preventing film forming agent 4 was replaced with an anthranilic acid as a chelating agent (having a melting point of 1).
43 ° C ≒ activation temperature) as the main component,
There is a feature in this point. Anthranilic acid reacts with the Ag particles to form a metal complex, anthranilic acid Ag, on the surface of the particles. The activation temperature (reaction temperature) of anthranilic acid, the application temperature of the conductive adhesive, and the curing temperature of the conductive adhesive satisfy the following relationship. Application temperature of conductive adhesive (32 ° C.) <Activation temperature of anthranilic acid (143 ° C.) Activation temperature of anthranilic acid (143 ° C.) ≦ curing temperature of binder resin (150 ° C.) Therefore, elution containing anthranilic acid The prevention film forming agent 4 reacts with the conductive particles 3 in the curing step of the binder resin 2 to form the elution prevention film 5 containing a metal complex.
Further, anthranilic acid Ag, which is a metal complex formed by this reaction, is nonionic and can be defined as insoluble in water and an aqueous solution containing hydrogen sulfide or sulfur oxide.

Next, a method for manufacturing the conductive adhesive 1 of this embodiment will be described. Liquid binder resin 2 (7% by weight) made of a thermosetting epoxy resin, conductive particles 3 (92% by weight) made of Ag, and elution preventing film forming agent 4 (2 % By weight) and an additive, a dispersant, an adhesion improver and the like (2% by weight) are dispersed and mixed using a three-roll mill to obtain a conductive adhesive 1 of this embodiment.

(Example 2) In this example, in the structure of the conductive adhesive described in Example 1, the chelating agent 1-
The elution-preventing film-forming agent 4 containing nitroso-2-naphthol (melting point 110 ° C.) as a main component is characterized in this point. Other conditions, that is, the constituent conditions of the conductive adhesive material, the manufacturing method, the application temperature, the curing temperature, and the like are exactly the same as those in the first embodiment.

The activation temperature of 1-nitroso-2-naphthol (reaction temperature ≒ melting point) is (around 110 ° C.), and reacts with the conductive particles 3 in the curing step of the binder resin 2 to react with the metal complex, ie, 1-nitroso-2-naphthol. Nitroso-2-naphthol Ag
Is formed as a main component. 1-Nitroso-2-naphthol Ag is an ionic substance, is extremely soluble in water, and has a property of easily absorbing water and an aqueous solution containing hydrogen sulfide or sulfur oxide.

Example 3 In this example, the elution-preventing forming agent 4 was added to the composition of the conductive adhesive described in Example 1.
Is a state in which a drug mainly composed of anthranilic acid is microencapsulated with hexamethylene phthalamide resin (melting temperature: 87 ° C.), which is characterized in this point. Other conditions, that is, the constituent conditions of the conductive adhesive material, the manufacturing method, the application temperature, the curing temperature, and the like are exactly the same as those in the first embodiment. The softening temperature of the microcapsule, the application temperature of the conductive adhesive, and the curing temperature of the conductive adhesive satisfy the following relationship. Application temperature of conductive adhesive (32 ° C) <melting temperature of microcapsule (87 ° C) Melting temperature of microcapsule (87 ° C) ≤ curing temperature of binder resin (150 ° C) Activation temperature of anthranilic acid (143 ° C) ≦ Curing temperature of binder resin (150 ° C.) Therefore, in the curing step of binder resin 2, the microcapsules melt to release internal elution-preventing film-forming agent 4, and the released elution-preventing film-forming agent (anthranilic acid) The elution preventing film 5 containing the metal complex is formed by reacting with the conductive particles 3.

The microencapsulation of the elution-preventing film forming material 4 is performed by using an interfacial polymerization reaction which is a known technique. A detailed manufacturing method will be described below. 0.4M 1,
After adding an equal amount of water to 7.5 ml of an aqueous solution in which 6-hexamethylenediamine and 0.45 M sodium carbonate are dissolved, 15 ml of this solvent is mixed with a chloroform-cyclohexane mixed solution containing 5% anthranilic acid (volume ratio). At 1:
4) Add to 75 ml, emulsify while stirring well, and add water /
Create an oil emulsion. After emulsification for 5 minutes, phthaloyl dichloride is added with stirring. Thereby, a polycondensation reaction occurs between phthaloyl dichloride and diamine on the surface of the water droplet in the emulsion, and hexamethylene phthalamide is generated. By the above steps, the elution preventing film forming agent 4
Are encapsulated in the microcapsules.

Example 4 In this example, in the construction of the conductive adhesive described in Example 1, the elution preventing film forming agent 4 was replaced with bismuthyl II (melting point: 246 ° C./activation temperature) instead of anthranilic acid. ) As a main component, and as a production method, a step of reheating at a temperature higher than the activation temperature of the elution-preventing film-forming agent 4 after curing of the conductive adhesive 1 is included. . Other conditions, that is, the constituent conditions of the conductive adhesive material, the manufacturing method, the application temperature, the curing temperature, and the like are exactly the same as those in the first embodiment. The activation temperature of the elution preventing film forming agent (chelating agent), the curing temperature of the conductive adhesive 1, and the reheating temperature satisfy the following relationship. Curing temperature of binder resin (150 ° C) ≦ Bismuthiol II
Activation temperature (246 ° C) Activation temperature of bismuthiol II (246 ° C) <reheating temperature
(250 ° C.) (Example 5) In the present example, in the configuration of the conductive adhesive described in Example 4, bismuthiol II was used as a chelating agent as a main component of the elution preventing film forming agent 4,
It uses anthranilic acid (activating temperature: 143 ° C.) and then microencapsulates this elution preventing film forming agent 4 with hexamethylene phthalamide resin (melting temperature: 162 ° C.). There are features. Other conditions, that is, the constituent conditions of the conductive adhesive material, the manufacturing method, the application temperature, the curing temperature, and the like are exactly the same as those in the first embodiment. The activation temperature (reaction temperature) of the elution prevention film forming material 4, the curing temperature of the conductive adhesive 4, the reheating temperature, and the melting temperature of the capsule satisfy the following relationship. Curing temperature of binder resin (150 ° C) <melting temperature of microcapsule (162 ° C) Melting temperature of microcapsule (162 ° C) <reheating temperature (170 ° C) Activation temperature of hexamethylene phthalamide resin (143)
° C) <reheating temperature (170 ° C) Therefore, in the curing step, the elution-preventing film-forming agent 4 does not react, and in the reheating step, the elution-preventing film-forming agent 4 reacts with the conductive particles and contains a metal complex. An elution prevention film 5 is formed.

The conductive adhesives of Comparative Examples 1 to 3 are prepared corresponding to Examples 1 to 5 described above.

(Comparative Example 1) This conductive adhesive was prepared by removing the elution preventing film forming agent 4 from the structure of the conventional conductive adhesive, that is, the conductive adhesive 1 of Example 1, and then removing the conductive adhesive. It has a configuration in which the content of the particles 3 is the same as in Example 1.
That is, the conductive adhesive 1 is a liquid binder resin 2 (6% by weight) made of a thermosetting epoxy resin.
And conductive particles 3 made of Ag (92% by weight) and additives (2% by weight) such as a curing agent, a dispersant, and an adhesion improver are dispersed and mixed using a three-roll mill. I do.

(Comparative Example 2) This conductive adhesive is the same as the conductive adhesive of Example 1 except that bismuthiol II (having an activation temperature higher than the curing temperature of the conductive adhesive) is used as a chelating agent. Melting point 246 ° C. (activation temperature). The activation temperature of the chelating agent, the application temperature of the conductive adhesive, and the curing temperature of the conductive adhesive satisfy the following relationship. Application temperature of conductive adhesive (32 ° C.) <Curing temperature of binder resin (150 ° C.) Curing temperature of binder resin (150 ° C.) <Bismuthiol II
Therefore, in Comparative Example 2, the chelating agent does not react in the curing step of the binder resin, and the elution preventing film 5 containing the metal complex is formed on the surface of the conductive particles 3 in Comparative Example 2. Never.

(Comparative Example 3) This conductive adhesive is the same as the conductive adhesive of Example 1 except that toluene-3, whose activation temperature is lower than the application temperature of the binder resin 2, is used as a chelating agent. Contains 4-dithiol (melting point 31 ° C. ≒ activation temperature). The activation temperature of the chelating agent, the application temperature of the conductive adhesive, and the curing temperature of the conductive adhesive satisfy the following relationship. Activation temperature of toluene-3,4-dithiol (31 ° C.) <
Application temperature of conductive adhesive (32 ° C.) Application temperature of conductive adhesive (32 ° C.) <Curing temperature of binder resin (150 ° C.) Therefore, in the uncured state, the chelating agent reacts with the conductive particles, An elution preventing film containing a metal complex is formed on the particle surface.

A conductive adhesive layer is formed using the conductive adhesives of Examples 1 to 5 and Comparative Examples 1 to 3 prepared as described above, and evaluation and measurement are performed according to the following method.

Evaluation of resistance to ion migration (drop of water
Lower test) The water drop test is a test method for simply and simply evaluating the ion migration property of a material. Details of the test method are as follows. As a test sample, FIG.
As shown in (1), conductive adhesive layers 18 and 19 in the form of comb electrodes are formed on a test substrate 17 made of ceramic by a screen printing method. The conductive adhesive layers 18 and 19 are opposed to each other so that their electrode tips cross each other in a state of being separated by a predetermined electrode distance (400 μm). Current should not flow through.

The conductive adhesive layer 1 thus formed
8 and 19, deionized water was dropped, and both conductive adhesives 1
A DC voltage (1 V) is applied between 8 and 19. Then, the time until a current flows due to a short circuit between the conductive adhesive layers 18 and 19 is measured, and the ion migration resistance is evaluated based on the length of the short circuit time.

[0094] As shown in sulfidation reaction evaluation Figure 5, after forming the test substrate 20 to the gold-plated electrode 21 made of a glass epoxy substrate, conductive made of a conductive adhesive 1 by further screen printing gold plating electrodes 21 The adhesive layer 1A is formed. Then, on the conductive adhesive layer 1A, 32 is mounted using a mount mounting machine.
16 size 0Ω resistor (terminal plating: SnPb solder)
22 is mounted. Next, in order to cure the conductive adhesive layer 1A, it is heated in an oven at 150 ° C. for 30 minutes. After measuring the initial connection resistance of the sample manufactured in this way, the sample is left to stand in a sealed tank filled with hydrogen sulfide, and the change in the connection resistance is measured to evaluate the resistance to sulfuration reaction. The test conditions are a temperature of 40 ° C., a humidity of 90%, a hydrogen sulfide concentration of 3 ppm, and a test time of 96 hours.

Table 1 shows the results of the above evaluation and measurement.
The application temperature (working temperature) of the conductive adhesive in each test was 32 ° C.

[0096]

[Table 1] The following can be seen from the conductive adhesives of Examples 1 to 5 as compared with Comparative Examples 1 to 3. That is, in the evaluation of the resistance to ion migration, the time until the current flows is longer than that in the case of using the conventional conductive adhesive (Comparative Example 1), and it can be confirmed that the resistance to ion migration is improved. In addition, in the evaluation of the sulfidation reactivity, the rate of change of the connection resistance before and after the test was smaller than that in Comparative Example 1, and it can be confirmed that the sulfidation reactivity was improved.

Further, the following can be confirmed by comparing the examples. That is, the metal complex which is the main component of the elution preventing film 5 formed on the surface of the conductive particles 3 is insoluble in water and an aqueous solution containing hydrogen sulfide or sulfur oxide. Comparing with Example 2, which has properties, it can be confirmed that Example 1 has better ion migration resistance and sulfuration reaction resistance. This is because the formed elution prevention film (metal complex)
It is considered that the film having a property of being insoluble in water and an aqueous solution containing hydrogen sulfide or sulfur oxide is less likely to peel off even when the aqueous solution containing water or sulfur condenses on the film surface.

A comparison between Example 1 in which the elution-preventing film-forming agent 4 (chelating agent) was directly added to the conductive adhesive 1 and Example 3 in which the elution-preventing film-forming agent 4 (the chelating agent) was added in a microencapsulated state, showed that However, it can be confirmed that the initial connection resistance is low. This is achieved by microencapsulation
The reaction of the elution-preventing film-forming agent 4 in the uncured state can be more reliably suppressed, and the contact points between the conductive particles 3 and the conductive particles 3
It is considered that the amount of the insulating elution preventing film 5 (metal complex) existing at the contact point between the electrode and the electrodes 13 and 21 is reduced. In the third embodiment, an example is shown in which the elution-preventing film-forming agent 4 mainly composed of anthranilic acid whose activation temperature is higher than the application temperature of the conductive adhesive 1 is encapsulated. Since the elution-preventing film-forming agent 4 mainly containing a chelating agent having an activation temperature lower than the application temperature can be used, the range of choice of the elution-preventing film-forming agent (chelating agent) can be wider than that of Example 1. spread.

Example 1 using the elution-preventing film-forming agent 4 containing a chelating agent which reacts in the curing step of the conductive adhesive 1 as a main component, and elution containing a chelating agent which does not react in the curing step as a main component In comparison with Example 4 in which the anti-elution film forming agent 4 was reacted in the reheating step after the curing step using the anti-film forming agent 4, Example 4 had a lower initial connection resistance, It can be confirmed that the results obtained when the adhesive was used (Comparative Example 1) were equivalent to the initial values. This is because, in the fourth embodiment, the elution preventing film 4
It is considered that the elution preventing film 5 is hardly formed at the conductive part because the formation reaction occurs.

As shown in Example 5, in Example 4, micro-encapsulation of the elution-preventing film-forming agent 4 further provides equivalent ion migration resistance and sulfidation reaction resistance. Elution preventing film forming agent 4
The range of choices is expanded. In Example 4, it is necessary to use the elution-preventing film-forming agent 4 containing a chelating agent having an activation temperature (reaction temperature) higher than the curing temperature. 2
If the curing temperature is higher than the curing temperature of
The activation temperature may be any value. For example, the elution preventing film forming agent 4 having an activation temperature (reaction temperature) lower than the application temperature of the conductive adhesive 1 can also be used.

If the conditions shown in Examples 1 to 5 are not used, the intended effect cannot be obtained. The example is referred to as Comparative Example 2,
3 is shown.

Comparative Example 2 shows the case where the elution preventing film-forming agent 4 used was a chelating agent as a main component, in which the activation temperature was lower than the application temperature of the conductive adhesive 1. In this case, the initial connection resistance becomes extremely high as compared with Example 1, that is, when the activation temperature is higher than the application temperature. This is because, in the uncured state, the anti-elution film forming agent 4 reacts with the conductive particles 3 to form an elution prevention film 5 (metal complex). This is because the elution preventing film 5 (metal complex) is present to increase the contact resistance.

In Comparative Example 3, the elution preventing film forming agent 4
The case where the activation temperature of the chelating agent as the main component is higher than the curing temperature of the conductive adhesive 1 is shown.
Compared with Example 1, that is, when the activation temperature of the chelating agent is lower than the curing temperature, the ion migration resistance and the sulfidation reaction resistance are extremely poor. This is because the elution preventing film forming agent 4 does not react in the curing step of the conductive adhesive 1 (binder resin 2), and the elution preventing film (metal complex) 4 cannot be formed on the surface of the conductive particles 3.

Next, examples of the second embodiment (flip-chip mounting structure of a semiconductor device) will be described.

(Example 6) In the present example, the conductive adhesive of Example 1 using an anthranilic acid as a chelating agent as a main component was used as the elution-preventing film-forming agent 4 (however, a liquid adhesive). The only difference is that an epoxy resin having thermoplasticity is used as the binder resin 2).
The semiconductor device 7 is flip-chip mounted on the circuit board 6 and is characterized in this point. That is, the conductive adhesive 1 described in the first embodiment is transferred to the bump electrode 9 of the semiconductor device 7 by a known method. Then, the transferred conductive adhesive 1
The semiconductor device 7 is flip-chip mounted on the circuit board 6 in a state where is aligned with the input / output terminal electrode 10 of the circuit board 6. Then, an electrical inspection is performed after the conductive adhesive 1 is cured, and when a good result is obtained, a sealing resin 11 made of a thermosetting epoxy resin is supplied between the circuit board 6 and the semiconductor device 7. Then, the connection is sealed to form a flip-chip mounting structure.

Example 7 In this example, the elution preventing film forming agent 4 was 1-nitroso-2-chelate, a chelating agent.
The flip-chip mounting structure is formed by using the conductive adhesive 1 of Example 2 using naphthol as a main component, which is characterized in this point. The structure and manufacturing method of the flip-chip mounting structure were the same as those in Example 6 except for the conductive adhesive.
Is exactly the same as

Example 8 In this example, an elution-preventing film-forming agent 4 containing an anthranilic acid as a main component as a chelating agent was used, and this elution-preventing film-forming agent 4 was treated with hexamethylene phthalamide. The flip chip mounting structure is formed using the conductive adhesive 1 of the third embodiment, which is microencapsulated with a resin, and is characterized in this point. The configuration and manufacturing method of the flip-chip mounting structure are exactly the same as those of the sixth embodiment except for the conductive adhesive 1.

(Embodiment 9) In this embodiment, as the elution-preventing film-forming agent 4, the conductive adhesive 1 mainly containing bismuthyl II as a chelating agent is cured, and then a reheating step is performed. The flip-chip mounting structure is formed by the method of Example 4, which is characterized. The configuration and manufacturing method of the flip-chip mounting structure are exactly the same as those of the sixth embodiment except for the conductive adhesive.

Example 10 In this example, the elution-preventing film-forming agent 4 was mainly composed of anthranilic acid as a chelating agent, and the elution-preventing film-forming agent 4 was microencapsulated with hexamethylene phthalamide resin. A flip-chip mounting structure is formed by the method of Embodiment 5 in which a reheating step is provided after the conductive adhesive 1 is cured, which is characterized in this point. The configuration and the manufacturing method of the flip-chip mounting structure are exactly the same as those of the sixth embodiment except for the configuration of the conductive adhesive 1.

(Comparative Examples 4 to 6) Examples 6 to 10 described above.
In response to the above, flip-chip mounted structures of Comparative Examples 4 to 6 are manufactured.

This flip-chip mounting structure uses the conductive adhesive of Comparative Example 1 and has a mounting structure similar to those of Examples 6 to 10.

Examples 6 to 10 produced as described above
The reliability of the flip-chip mounting structures of Comparative Examples 4 to 6 is evaluated according to the following method.

That is, a current (10 mA) during actual use was passed through these flip-chip mounted structures, and the connection resistance was reduced in a high-temperature and high-humidity environment (temperature 85 ° C., humidity 85%, test time 1000 h). By measuring the change, an evaluation measurement of ion migration resistance is performed.
Similarly, by measuring the change in connection resistance in a hydrogen sulfide atmosphere (temperature: 40 ° C., humidity: 90%, hydrogen sulfide concentration: 3 ppm, test time: 96 h) while passing a current (10 mA) during actual use, the resistance to sulfidation is measured. An evaluation measurement of the reactivity is performed.
Table 2 shows the results.

[0114]

[Table 2] In the flip chip mounting structures of Examples 6 to 10, the following can be understood as compared with Comparative Examples 4 to 6. In other words, in the evaluation of ion migration resistance, the case where the time until the current flows was obtained using the conventional conductive adhesive (Comparative Example 4)
It can be confirmed that the ion migration resistance was improved. In addition, in the evaluation of the sulfidation reactivity, the rate of change of the connection resistance before and after the test was smaller than that in Comparative Example 4, and it can be confirmed that the sulfidation reactivity was improved.

Further, comparing the examples, the following can be confirmed. That is, the elution preventing film 5 formed on the surface of the conductive particles 3 has the property of being insoluble in water and an aqueous solution containing hydrogen sulfide or sulfur oxide, and the example 7 having the property of being soluble. Can be confirmed that Example 6 has better ion migration resistance and sulfuration resistance. This is because if the formed elution preventing film 5 has the property of being insoluble in water and an aqueous solution containing hydrogen sulfide or sulfur oxide, even if the aqueous solution containing water or sulfur condenses on the film surface, This is probably because the film is hard to peel off.

Further, when comparing Example 6 in which the elution preventing film forming agent 4 was directly added to the conductive adhesive 1 and Example 8 in which the elution preventing film forming agent 4 was added in a microencapsulated state, Example 8 showed that It can be confirmed that the initial connection resistance is low. This is because the reaction of the elution-preventing film-forming agent 4 in the uncured state can be more reliably suppressed by microencapsulation,
The contact points between the conductive particles 3 and the conductive particles 3 and the electrode 1
It is considered that the amount of the insulating elution preventing film 5 existing at the contact points with the reference numerals 3 and 21 is reduced. In Example 8, the elution-preventing film-forming agent 4 containing anthranilic acid as a main component and having a higher reaction temperature (activation temperature) than the application temperature of the conductive adhesive 1 was used.
Here is an example in which is encapsulated. However, in Example 8, the elution-preventing film-forming agent 4 containing a chelating agent as a main component and having a reaction temperature (activation temperature) lower than the application temperature of the conductive adhesive 1 can be used.
The range of choice of the elution-preventing film-forming agent (chelating agent) is broader than that.

Further, Example 6 using the elution-preventing film-forming agent 4 that reacts in the curing step of the conductive adhesive 1 and reaction in the reheating step using the elution-preventing film-forming agent 4 that does not react in the curing step. Comparing Example 9 with Example 9, Example 9 has a lower initial connection resistance, and has a value equivalent to the initial value of the result (Comparative Example 1) when the conventional conductive adhesive is used. You can check. This is considered to be because in Example 9, the elution preventing film forming agent 4 reacts after the conduction is developed in the curing step, and therefore, the elution preventing film 5 is hardly formed at the conductive portion.

Further, as shown in Embodiment 10, Embodiment 9
In the above structure, by microencapsulating the anti-elution film forming agent 4, equivalent ion migration resistance and sulfidation reaction resistance can be obtained, and the range of choice of the anti-elution film forming agent 4 is expanded. . In Example 9, it is necessary to use the elution-preventing film-forming agent 4 having an activation temperature higher than the curing temperature. In Example 10, however, the melting temperature of the microcapsules is set higher than the curing temperature of the binder resin 2. As long as the reaction temperature (activation temperature) of the elution preventing film forming agent 4
Anything is fine. In Example 10, as the elution preventing film forming agent 4, an anthranilic acid having an activation temperature higher than the application temperature of the conductive adhesive 1 as a main component was used.
In the tenth embodiment, a material mainly containing a chelating agent having an activation temperature lower than the application temperature of the conductive adhesive 1 can be used.

When the conditions shown in Examples 6 to 10 are not used, the intended effect cannot be obtained. The example is referred to as Comparative Example 5,
6 is shown.

In Comparative Example 5, as the elution-preventing film-forming agent 4,
The case where the activation temperature of the chelating agent as the main component is lower than the application temperature of the conductive adhesive 1 is shown. In this case, the initial connection resistance becomes extremely high as compared with Example 6, that is, when the reaction temperature (activation temperature) of the elution preventing film is higher than the application temperature of the conductive adhesive 1.
This is because the elution preventing film forming agent 4 reacts with the conductive particles 3 in an uncured state to form an elution preventing film (metal complex).
This is because an insulating elution preventing film (metal complex) is present at a portion involved in conduction of the conductive particles 3 to increase the contact resistance.

In Comparative Example 6, the elution preventing film forming agent 4
Shows a case where the reaction temperature (activation temperature) is higher than the curing temperature of the conductive adhesive 1. In this case, as compared with Example 5, ie, the case where the reaction temperature (activation temperature) of the elution-preventing film forming agent 4 is lower than the curing temperature of the conductive adhesive 1, the ion migration resistance and the sulfidation resistance are compared. Is extremely poor. This is because the elution preventing film forming agent 4 does not react in the curing step of the conductive adhesive 1 (the binder resin 2), and the elution preventing film 5 cannot be formed on the surface of the conductive particles 3.

As described above, Examples 6 to 10 (flip chip mounting structures) are also Examples 1 to 5 (conductive adhesive).
The same effect can be obtained.

In Examples 6 to 10, the electrical connection between the semiconductor device and the circuit board was performed using the conductive adhesive 1 having a thermoplastic epoxy resin. Similarly to the above, it is needless to say that the same effect is exhibited even when a thermosetting epoxy resin is used.

Each example of the third embodiment (chip component mounting structure) will be described.

(Embodiment 11) This embodiment is a chip component mounting structure manufactured using the conductive adhesive of Embodiment 1. In addition, in Example 1, as the elution prevention film forming agent 4,
A substance containing anthranilic acid as a chelating agent as a main component is used. This chip component mounting structure is obtained by forming an electrode 13 on a circuit board (30 × 60 mm, thickness 1.6 mm) 12 made of a glass epoxy substrate by Au plating, and then forming a 0Ω chip resistor (3216 size, SnPb plating) 14 And a chip coil (diameter 8mmφ, height 4m
m) 15 and a chip capacitor (3216 size, Sn
Pb plating) 16 are mounted.

This chip component mounting structure is manufactured as follows. First, the conductive adhesive 1 is screen-printed on the electrodes 13 of the circuit board 12. And chip part 1
After mounting 4, 15, and 16 on the electrode 13 using an existing component mounting apparatus, the conductive adhesive 1 is cured by heating in an oven at 150 ° C. for 30 minutes.

Example 12 In this example, 1-nitroso-2 which is a chelating agent was used as the elution preventing film forming agent 4.
A chip component mounting structure is constituted by the conductive adhesive 1 of Example 2 using a material having naphthol as a main component,
There is a feature in this point. The configuration and manufacturing method of the chip component mounting structure are exactly the same as those of Example 11 except for the conductive adhesive.

Example 13 In this example, the conductive adhesive of Example 3 in which anthranilic acid as a chelating agent was used as the elution-preventing film-forming agent 4 and microencapsulated with hexamethylenephthalamide resin was used. Is used to manufacture a chip component mounting structure, which is characteristic. The configuration and manufacturing method of the chip component mounting structure are exactly the same as those of the eleventh embodiment except for the conductive adhesive 1.

(Example 14) In this example, an agent for forming a dissolution-preventing film-forming agent 4 containing bismuthyl II as a chelating agent as a main component was used, and a reheating step was performed after the conductive adhesive was cured. The chip component mounting structure is manufactured by using the configuration and the method of the third embodiment provided with the above, and is characterized in this point. The configuration and manufacturing method of the chip component mounting structure are exactly the same as those of Example 11 except for the conductive adhesive 1.

Embodiment 15 In this embodiment, as the elution-preventing film-forming agent 4, a material mainly containing anthranilic acid as a chelating agent and encapsulated with a hexamethylene phthalamide resin is used. Adhesive 1
According to the method of Example 5 in which a reheating step was provided after the curing of
A flip chip mounting structure is manufactured, and this is a feature. The configuration and manufacturing method of the flip-chip mounting structure are exactly the same as those of the eleventh embodiment except for the conductive adhesive 1.

(Comparative Examples 7 to 9) Examples 11 to 1 described above.
In correspondence with 5, the chip component mounting structures of Comparative Examples 7 to 9 are produced.

These chip component mounting structures have the same mounting structure as in Examples 11 to 15 after using the conductive adhesive of Comparative Example 1.

Examples 11 to 1 produced as described above
The reliability of the chip component mounting structures of Comparative Example 5 and Comparative Examples 7 to 9 is evaluated according to the following method.

With respect to these chip component mounting structures,
Under the high temperature and high humidity environment (temperature 85 ° C, humidity 85%, test time 10000) while applying the current (10 mA) during actual use.
By measuring the change in connection resistance in h), an evaluation measurement of ion migration resistance is performed. Similarly, while passing a current (10 mA) at the time of actual use, under a hydrogen sulfide atmosphere (temperature 40 ° C., humidity 90%, hydrogen sulfide concentration 3 ppm,
By measuring the change in the connection resistance at a test time of 96 h), an evaluation measurement of the resistance to sulfidation reaction is performed. Table 3 shows the results.

[0135]

[Table 3] The following can be seen from the chip component mounting structures of Examples 11 to 15 as compared with Comparative Examples 7 to 9. That is, in the ion migration resistance evaluation, the time until the current flows is longer than that in the case where the conventional conductive adhesive is used (Comparative Example 7), and it can be confirmed that the ion migration resistance is improved. In addition, in the evaluation of the sulfidation reactivity, the rate of change in the connection resistance before and after the test was smaller than that in Comparative Example 7, and it can be confirmed that the sulfidation reactivity was improved.

Further, comparing the examples, the following can be confirmed. That is, the metal complex formed on the surface of the conductive particles is compared with Example 11 having the property of being insoluble in water and an aqueous solution containing hydrogen sulfide or sulfur oxide, and Example 12 having the property of being soluble in water. It can be confirmed that Example 11 has better ion migration resistance and sulfurization reaction resistance. This is because the anti-elution film 5 to be formed has the property of being insoluble in water and an aqueous solution containing hydrogen sulfide or sulfur oxide. It is considered that it is difficult to peel off.

Further, comparing Example 11 in which the elution-preventing film forming agent 4 was directly added to the conductive adhesive 1 and Example 13 in which the elution-preventing film-forming agent 4 was added in a microencapsulated state, Example 13 had a higher initial state. It can be confirmed that the connection resistance is low. This is because the reaction of the anti-elution film forming agent 4 in the uncured state can be further suppressed by microencapsulation,
The contact points between the conductive particles 3 and the conductive particles 3 and the electrodes 21
Insulating elution prevention film (metal complex) existing at the point of contact with water
It is considered that the amount of In the thirteenth embodiment,
An example is shown in which the elution preventing film forming agent 4 containing anthranilic acid as a main component, which is a chelating agent having a higher activation temperature than the application temperature of the conductive adhesive 1, is microencapsulated. Since the elution-preventing film-forming agent 4 containing a chelating agent having a lower activation temperature than the application temperature as a main component can also be used, the range of choice of the elution-preventing film-forming agent 4 (chelating agent) is greater than in Example 11. spread.

Further, Example 13 using the elution-preventing film-forming agent 4 that reacts in the curing step of the conductive adhesive 1 and reaction in the reheating step using the elution-preventing film-forming agent 4 that does not react in the curing step. Example 14 is compared with Example 14
Can be confirmed to have a lower initial connection resistance and a value equivalent to the initial value of the result (Comparative Example 7) when the conventional conductive adhesive is used. This is probably because in Example 14, the elution-preventing film-forming agent 4 was reacted after the conduction was developed in the curing step, so that the elution-preventing film 4 was hardly formed at the conductive portion.

Also, as shown in Embodiment 15, Embodiment 1
In the configuration of No. 4, microencapsulation of the elution-preventing film-forming agent 4 provides equivalent ion-migration resistance and sulfidation-reactivity as well as the addition of the elution-preventing film-forming agent 4 (chelating agent). The range of choice is expanded. In Example 14, it is necessary to use the elution-preventing film-forming agent 4 mainly composed of a chelating agent having an activation temperature higher than the curing temperature. In Example 15, however, the melting temperature of the microcapsules was changed to the binder resin 2. The activation temperature of the elution-preventing film-forming agent 4 (chelating agent) may be any value as long as the temperature is higher than the curing temperature. In Example 15, the elution-preventing film-forming agent 4 containing anthranilic acid as the main component and having an activation temperature higher than the application temperature of the conductive adhesive 1 was used as the elution-preventing film-forming agent 4. The elution preventing film 4 containing a chelating agent having an activation temperature lower than the application temperature of No. 1 as a main component can also be used.

When the conditions shown in Examples 11 to 15 are not used, the intended effect cannot be obtained. Examples are shown in Comparative Examples 8 and 9.

Comparative Example 8 shows a case where the reaction temperature (activation temperature) of the elution preventing film forming agent 4 is lower than the application temperature of the conductive adhesive 1. As compared with Example 11, that is, the case where the reaction temperature (activation temperature) is higher than the application temperature of the conductive adhesive 1, the initial connection resistance becomes extremely high. This is because, in the uncured state, the elution preventing film forming agent 4
This is because the insulating elution preventing film 5 (metal complex) is present at a site involved in the conduction of the conductive particles 3 to form the elution preventing film 5 to increase the contact resistance.

In Comparative Example 9, the elution preventing film forming agent 4
Shows a case where the reaction temperature (activation temperature) is higher than the curing temperature of the conductive adhesive 1. As compared with Example 11, that is, when the reaction temperature (activation temperature) is lower than the curing temperature of the binder resin 2, the ion migration resistance and the sulfidation resistance are extremely poor. This is because the elution preventing film forming agent 4 does not react in the curing step of the conductive adhesive 1 and the elution preventing film 5 cannot be formed on the surface of the conductive particles 3.

As described above, the effects of Examples 11 to 15 (chip component mounting structure) are the same as those of Examples 1 to 5 (conductive adhesive) and Examples 6 to 10 (flip chip mounting structure). Is obtained.

In the embodiments 11 to 15, only the mounting structure of the chip component is shown as an example of the mounting structure of the component. However, other components, for example, QFP (quad flat package), CSP ( It can be used to mount all parts such as package parts such as chip scale package), BGA (ball grid array), chip parts and lead parts such as electrolytic capacitors, diodes and switches, and bare IC mounting. What you can do is obvious. The elution-preventing film-forming agent and the like are not limited to the embodiments described in the examples, as long as they satisfy the necessary conditions.

In each of the above embodiments, the elution preventing film forming agent 4 may be added to the conductive adhesive in a state of being dispersed in a non-polar solvent. Then, it becomes as follows.

Since the non-polar solvent has a function of suppressing the reaction of the chelating agent, if the elution preventing film-forming agent 4 is added to the conductive adhesive in a state of being dispersed in the non-polar solvent, the binder resin is not dispersed. In the cured state, little reaction of the chelating agent occurs. Then, in the step of curing the binder resin, the chelating agent reacts with the conductive particles to form an elution preventing film containing a metal complex. Therefore, the degree of formation of the elution preventing film 5 in the uncured state of the binder resin is further reduced, and the increase in connection resistance in the cured conductive adhesive 1 is reliably suppressed. Furthermore, since the activation temperature of the chelating agent may be lower than the application temperature of the conductive adhesive, the range of characteristics (especially, activation temperature) required for the chelating agent is widened, and the chelating agent can be used accordingly. The range of chelating agents that can be selected will be expanded.

[0147]

As described above, according to the present invention,
It is possible to obtain a mounting structure that is more excellent in ion migration resistance or sulfurization reaction resistance than the conventional one.

When the present invention is applied to a mounting structure such as a flip-chip mounting structure or a chip component mounting structure, it is possible to reduce the connection interval between electrodes or the like in order to improve insulation reliability. In addition, space saving of the mounting structure can be realized.

Further, according to the present invention, since the reliability of the sulfidation reaction is improved, it can be applied to products which may be used in a gas atmosphere containing a large amount of sulfur, such as near hot springs or volcanoes. It can be expected that the use will be greatly expanded.

[Brief description of the drawings]

FIG. 1 is an enlarged view of a main part of a conductive adhesive according to a first embodiment of the present invention. FIG. 1 (A) is in an uncured state, and FIG. 1 (B) is in a curing step. FIG. 1 (C) shows the state after conduction when the conduction is developed.

FIG. 2 is a sectional view of a flip-chip mounting structure according to a second embodiment of the present invention.

FIG. 3 is a plan view of a chip component mounting structure according to a third embodiment of the present invention.

FIG. 4 is a plan view of a circuit board used for evaluation of resistance to ion migration.

FIG. 5 is a plan view of a test sample used in the evaluation of resistance to sulfidation reactivity.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Conductive adhesive 2 Binder resin 3
Conductive particles 4 dissolution preventing film forming agent 5 dissolution preventing film 6
Circuit board 7 Semiconductor device 8 IC board 9
Bump electrode 10 I / O terminal electrode 11 Sealing resin 1
2 circuit board 13 electrode 14 chip resistor 1
5 Chip capacitor 16 Chip coil 17 Circuit board 1
8 Comb-shaped electrode 19 Comb-shaped electrode 20 Circuit board 2
1 electrode 22 0Ω resistance

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H05K 3/32 H05K 3/32 B (72) Inventor Takashi Kitae 1006 Kazuma Kazuma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. (72) Inventor Tsutomu Mitani 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. DA171 DB031 DC031 DC071 DC091 EB071 EB111 EB131 EC001 ED111 EE061 EG001 EH031 EJ021 EK031 HA066 HA36 HC09 HD03 HD43 JA11 JB02 JB10 KA25 KA32 KA42 DA06 LA07 LA09 NA19 NA20 PA30 5E319 AA03 AB06 BB11 NN11 DA47 DA51 DA53 DA55 DA57

Claims (21)

[Claims] 1. A binder resin, conductive particles, and an elution-preventing film-forming agent, wherein the elution-preventing film-forming agent is electrically conductive via the conductive particles when the binder resin is cured. A conductive adhesive which reacts after being developed inside the conductive adhesive to form an elution preventing film on the surface of the conductive particles. 2. The reaction temperature of the elution-preventing film-forming material satisfies the following condition: conductive adhesive application temperature <reaction temperature of elution-preventing film-forming material reaction temperature of elution-preventing film-forming material ≦ curing temperature of binder resin. The conductive adhesive according to claim 1. 3. The elution-preventing film-forming agent contains a chelating agent, and when the binder resin is cured, the electrical conduction through the conductive particles is caused by the conductive adhesive. The conductive adhesive according to claim 1, wherein the conductive adhesive reacts after being expressed inside to form an elution prevention film containing a metal complex on the surface of the conductive particles. 4. The activation temperature of the chelating agent satisfies the following condition: conductive adhesive application temperature <chelating agent activation temperature chelating agent activation temperature ≦ binder resin curing temperature. Item 4. The conductive adhesive according to Item 3. 5. The elution-preventing film-forming agent is encapsulated in a microcapsule, and the melting temperature of the microcapsule and the activation temperature of a chelating agent contained in the elution-preventing film-forming material are determined by a conductive adhesive. 5. The conductive adhesive according to claim 4, which satisfies the following conditions: application temperature of microcapsule, melting temperature of microcapsule, melting temperature of microcapsule, curing temperature of binder resin, activation temperature of chelating agent, curing temperature of binder resin. . 6. The conductive adhesive according to claim 1, wherein the elution-preventing film-forming agent is composed of a water-insoluble substance. 7. The conductive adhesive according to claim 1, wherein the elution-preventing film-forming agent is made of a substance that is insoluble in an aqueous solution containing hydrogen sulfide or sulfur oxide. 8. The conductive adhesive according to claim 3, wherein the elution preventing film forming agent is added to the conductive adhesive in a state of being dispersed in a non-polar solvent. 9. An electric structure and a conductive adhesive layer provided on the electric structure, wherein the conductive adhesive layer contains conductive particles, and the conductive particles A mounting structure, wherein the contact points and the contact points between the conductive particles and the electric structure are covered with an elution preventing film. 10. An electric structure further comprising another electric structure disposed on the electric structure, wherein the conductive adhesive layer electrically connects the other electric structure to the electric structure. The mounting structure according to claim 9. 11. The mounting structure according to claim 9, wherein the elution prevention film is made of a material containing a metal complex. 12. The mounting structure according to claim 9, wherein the elution prevention film is made of a water-insoluble substance. 13. The mounting structure according to claim 9, wherein the elution preventing film is made of a substance that is insoluble in an aqueous solution containing hydrogen sulfide or sulfur oxide. 14. A method of manufacturing a mounting structure having an electric structure and a conductive adhesive layer provided on an electrode of the electric structure, wherein a binder resin, conductive particles are used as the conductive adhesive. When,
The elution-preventing film-forming material, wherein the reaction temperature of the elution-preventing film-forming material is as follows: the application temperature of the conductive adhesive <the reaction temperature of the elution-preventing film-forming material; the reaction temperature of the elution-preventing film-forming material ≦ the curing of the binder resin. Temperature, the conductive adhesive is applied on the electrode at the application temperature to form the conductive adhesive, and the conductive adhesive is applied until the curing temperature is reached. Heating and reacting the anti-elution film-forming agent at the reaction temperature reaching the middle of the temperature rise, an anti-elution film forming step of forming an anti-elution film on the conductive particles, and the conductive adhesive Curing the binder resin by heating the binder resin to the curing temperature. 15. The mounting structure according to claim 14, wherein the conductive adhesive contains a chelating agent and the dissolution preventing film forming agent is added in a state of being dispersed in a non-polar solvent. How to make the body. 16. A chelating agent is contained as the elution-preventing film-forming agent, and the activation temperature of the chelating agent is as follows: the application temperature of the conductive adhesive <the activation temperature of the chelating agent. Prepare a material that satisfies the condition of activation temperature ≦ curing temperature of the binder resin. In the elution prevention film forming step, the conductive adhesive is heated until the curing temperature is reached, and reaches the middle of the temperature rise. The method of manufacturing a mounting structure according to claim 14, wherein the chelating agent is reacted at the activation temperature to form an elution prevention film containing a metal complex on the conductive particles. 17. An elution-preventing film-forming agent in which the elution-preventing film-forming agent is encapsulated in microcapsules, and the melting temperature of the microcapsules and activation of a chelating agent contained in the elution-preventing film. The temperature satisfies the following condition: conductive adhesive application temperature <microcapsule melting temperature microcapsule melting temperature ≦ binder resin curing temperature chelating agent activation temperature ≦ binder resin curing temperature. 3. The method of manufacturing a mounting structure according to claim 1. 18. A method for manufacturing a mounting structure having an electric structure and a conductive adhesive layer provided on an electrode of the electric structure, wherein a binder resin, a conductive particle and a conductive particle are used as the conductive adhesive. When,
Containing an anti-elution film-forming agent, wherein the reaction temperature of the anti-elution film-forming agent satisfies the condition of the curing temperature of the binder resin <the reaction temperature of the anti-elution film-forming agent,
On the electrode, a conductive adhesive forming step of forming a layer of the conductive adhesive in an uncured state, and a curing step of curing the binder resin by heating the conductive adhesive to the curing temperature, An anti-elution film forming step of reacting the anti-elution film forming agent by reheating the conductive adhesive to a temperature equal to or higher than the reaction temperature to form an anti-elution film on the conductive particles A method for manufacturing a mounting structure, comprising: 19. A heat treatment at a temperature lower than the activation temperature in the curing step, wherein a substance containing a chelating agent having an activation temperature higher than the curing temperature of the binder resin is used as the elution preventing film forming agent. Then, the binder resin is cured, and in the elution prevention film forming step, by reheating at a temperature equal to or higher than the activation temperature, the chelating agent is reacted, and The method for manufacturing a mounting structure according to claim 18, wherein an elution preventing film containing a metal complex is formed. 20. The method for manufacturing a mounting structure according to claim 18, wherein the conductive adhesive is obtained by adding the dissolution preventing film forming agent in a state of being dispersed in a nonpolar solvent. 21. The elution-preventing film-forming agent used is one in which the elution-preventing film-forming agent is encapsulated in microcapsules, and the melting temperature of the microcapsules and activation of a chelating agent contained in the elution-preventing film. 19. The temperature satisfies the following condition: conductive adhesive application temperature <microcapsule melting temperature microcapsule melting temperature ≦ binder resin curing temperature chelating agent activation temperature ≦ binder resin curing temperature. 3. The method of manufacturing a mounting structure according to claim 1.