JP2002141372A - Mounting structure, its manufacturing method and conductive adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mounting structure having excellent insulating reliability and sulfurization resistance. SOLUTION: The mounting structure comprises a conductive adhesive layer 1A constituted of a conductive adhesive 1 having a charge transfer metal complex 3 at least at a part of a conductive filler 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounting structure for mounting an electronic component such as a semiconductor device, a method for manufacturing the same, and a conductive adhesive used for manufacturing the mounting structure.

[0002]

2. Description of the Related Art Conventionally, when a semiconductor device is mounted on input / output terminal electrodes of a circuit board, a wire bonding method using soldering has been often used. However, in recent years,
With the miniaturization of the package of the semiconductor device and the increase in the number of connection terminals, the interval between the connection terminals has been narrowed, and it has become increasingly difficult to cope with the conventional soldering technology.

Therefore, recently, a method has been proposed in which a semiconductor device such as an integrated circuit chip is directly mounted on input / output terminal electrodes of a circuit board to reduce the mounting area and achieve efficient use.

In particular, flip-chip mounting, in which a semiconductor device is mounted on a circuit board in a face-down state, requires that electrical connection between the semiconductor device and the circuit board can be made collectively.
It is considered to be a useful method because of its high mechanical strength after connection. As a connection material for flip-chip mounting, a method using a conductive adhesive has been proposed or put into practical use.

This method is a promising method for improving reliability and environmental measures for the following two reasons.

First, the conductive adhesive contains a resin material such as an epoxy resin, and has a more flexible connection with respect to external force and thermal stress as compared with solder which is a metal material, thereby improving reliability. realizable. Second, the conductive adhesive mainly uses silver particles as a conductive component, and clean mounting without using lead can be realized.

On the other hand, conventionally, in the structure for mounting electronic parts such as chip parts and package parts on a printed circuit board, a structure using a conductive adhesive as described above has been proposed in order to improve reliability and environmental measures. I have.

As described above, the mounting structure using the conductive adhesive will be a promising method in the future in view of both improvement in reliability and environmental measures.

[0009]

However, the mounting structure using the conductive adhesive has the following two problems.

The first problem is a decrease in insulation reliability due to ion migration. Ion migration is a kind of electrolytic action, and is a phenomenon in which, when an electrolyte such as water is present 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) Deposition of metal ions transferred to cathode Step 4) Repeat steps 1) to 3) Due to such an ion migration phenomenon, the metal grows in a dendritic manner between the electrodes, and finally, the metal is bridged between the electrodes to cause dielectric breakdown.

Silver used as a conductive filler of a conductive adhesive has a property of easily dissolving, and easily causes ion migration. Further, with the recent trend toward further miniaturization and weight reduction of electronic devices, the pitch of electrodes provided on semiconductor devices, electronic components, or circuit boards has become narrower, and ion migration is becoming more likely to occur. . Therefore, solving the problem of ion migration is indispensable for putting the conductive adhesive into practical use.

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

Proposal 1) Alloying of conductive filler (silver-copper, silver-palladium, etc.), Proposal 2) Sealing of conductive adhesive with insulating resin such as epoxy resin, Proposal 3) Conductive adhesive Of eluted metal ions and conversion to insoluble material by the addition of an ion-trapping agent such as an ion-exchange resin or a chelating agent, however, these proposals may have the following disadvantages. In Proposal 1), the filler metal becomes very expensive, which raises the production 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 the manufacturing cost. In Proposal 3), metal ions dissolve out of the conductive filler, thereby lowering the contactability of the conductive filler and causing an increase in connection resistance.

As described above, although each of the above proposals has an effect of suppressing ion migration, it has other problems, and it has been difficult to put it to practical use except in special fields.

The second problem is an increase in connection resistance due to sulfuration. Sulfidation 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 sulfuration is still largely unknown, it 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 ion and metal ion As described above, the conductive filler mainly contains silver as a main component. Although silver is a metal that is easily sulfided, when silver is sulfided, the volume specific resistance of the conductive adhesive increases, which causes an increase in connection resistance. Very few solutions to this problem have been reported so far 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. However, it has been difficult to apply a mounting structure using a conductive adhesive. Therefore, the application field of the mounting structure using the conductive adhesive has been greatly limited.

In view of the above problems, the present invention can maintain reliability in a mounting structure using a conductive adhesive even under relatively harsh conditions such as a humid condition and a gas atmosphere containing sulfur. It is intended to be.

[0019]

The mounting structure according to the present invention comprises:
An electrical structure, and a conductive adhesive layer provided on the electrical structure, wherein the conductive adhesive layer has a conductive filler, and at least a part of the conductive filler has a charge transfer metal complex. Which solves the above-mentioned problem. Here, the charge transfer metal complex is a kind of an organometallic compound formed by coordinating a metal with a metal, that is, a chelate ligand, and is characterized in that the ligand and the metal are bonded by a π bond. And

[0020]

DETAILED DESCRIPTION OF THE INVENTION The invention according to claim 1 of the present invention has an electric structure and a conductive adhesive layer provided on the electric structure, wherein the conductive adhesive layer is formed of a conductive material. A conductive filler, and a charge transfer metal complex in at least a part of the conductive filler to form a mounting structure. With this configuration, the mounting structure of the present invention exhibits good insulation reliability even under high temperature and high humidity. This is because the charge-transfer metal complex protects the conductive filler, so that the metal of the conductive filler is prevented from being eluted even under high temperature and high humidity, so that the ion migration reaction can be fundamentally prevented. .

The invention according to claim 2 of the present invention is characterized in that the charge transfer metal complex is an organometallic compound formed by coordinating a metal with a chelating ligand. The invention according to claim 3 of the present invention is characterized in that the organometallic compound has a ligand and a metal bonded by a π bond. Thus, in a normal metal complex, the chemical bond between the chelating ligand and the metal is a σ bond, that is, a single bond,
As described above, in the charge transfer metal complex, the metal and the chelate ligand are bonded by a π bond. The π bond is a bond state in which electrons can freely move through a chemical bond, and has a bond strength comparable to a double bond. Therefore, the charge transfer metal complex has an extremely strong binding force between the ligand and the metal as compared with the ordinary metal complex, and has a high effect of preventing the elution of the conductive filler metal. Furthermore, the present mounting structure does not cause sulfidation of the conductive filler even when left in a gas containing sulfur, and shows good connection reliability. This is because the sulfurization reaction can be fundamentally prevented by preventing the elution of the conductive filler.

According to a fourth aspect of the present invention, there is provided another electric structure disposed on the electric structure, wherein the conductive adhesive layer is provided on the electric structure. Is electrically connected, the effect of ion migration reaction and sulfurization of the conductive filler on the connection resistance becomes remarkable, so that the present invention is particularly effective.

[0023] As described in claim 5, the conductive filler is at least partially exposed on the surface of the conductive adhesive layer. What is necessary is just to provide in this exposed part at least. More specifically, as described in claim 6, the conductive adhesive layer has a large number of holes that communicate with each other and communicate with the surface of the adhesive layer, At least a part of the filler is exposed on the inner surface of the hole, and the charge transfer metal complex may be provided on at least the conductive filler exposed on the inner surface of the hole.

Further, according to the fifth and sixth aspects, the charge transfer metal complex is selectively provided only in the portion where the conductive filler communicates with the surface and the conductive filler is easily eluted. As a result, the following effects are exhibited.

If a charge transfer metal complex is provided at a portion of the filler involved in electrical conduction, electrical conduction may be slightly hindered. Therefore, when a charge transfer metal complex is present at this site, the charge transfer metal complex at this site is broken by applying measures such as applying external pressure along the conduction direction to secure electrical conduction. become. On the other hand, according to the configuration of the fifth and sixth aspects, the charge transfer metal complex is selectively provided only in the portion where elution is likely to occur. Is almost nonexistent. Therefore, the electrical continuity is further improved accordingly.

As described in claim 7, when the conductive filler contains silver, the effect of suppressing the ion migration and the sulfurization reaction are relatively large, so that the effect of the present invention, namely, the ion migration The suppression effect and the sulfurization reaction suppression effect become remarkable.

As described above, specific examples of the mounting structure to which the inventions described in claims 1 to 7 can be applied include those in which electronic components are mounted on a circuit board as described in claim 8 and those described in claim 9. As described, an example in which a semiconductor device is flip-chip mounted on a circuit board can be exemplified.

According to a tenth aspect of the present invention, there is provided a conductive adhesive containing a conductive filler, wherein at least a part of the conductive filler has a charge transfer metal complex. With this configuration, the mounting structure mounted using the conductive adhesive of the present invention does not generate ion migration even under high temperature and high humidity and has good insulation reliability, as described in the first aspect of the present invention. Show. In addition, even when the conductive filler is left in a gas containing sulfur, the conductive filler does not undergo sulfidation and exhibits good connection reliability.

When the conductive filler contains silver as described in claim 11, the effect of the present invention, that is, the effect of ion migration, is relatively large because the effect of suppressing ion migration and the sulfurization reaction are relatively large. The suppression effect and the sulfurization reaction suppression effect become remarkable.

[0030] According to a twelfth aspect of the present invention, there is provided a method for forming a conductive adhesive layer having a conductive filler on an electric structure, comprising the steps of: Forming a charge transfer metal complex on the conductive filler communicating with the surface of the agent layer. The mounting structure manufactured by this manufacturing method forms a charge-transfer metal complex to maintain good electrical conduction of the electrical structure and to improve the ion migration resistance and sulfidation reactivity. The effect can be demonstrated. The reason is the above-mentioned claim 1.
Etc., and are omitted here. Furthermore, according to the present invention, since the charge-transfer metal complex is formed on the conductive filler after the conductive adhesive layer is cured, the charge-transfer metal complex enters the electrical connection portion of the conductive adhesive layer. Therefore, good electrical conduction can be ensured without adversely affecting the conduction state. In addition,
The electric structure manufactured by the method of the present invention specifically has the structure described in the above-described fourth and fifth aspects.

Further, as a method for forming the charge transfer metal complex, there is a complexing treatment as described in claim 13. According to the complexing treatment, the following effects can be exerted. The complexing treatment is performed by pouring in a complexing agent, for example.
Such a complexing treatment can be performed using existing equipment. For this reason, new capital investment is unnecessary, and there is almost no increase in manufacturing costs. Also, since the complex is generally insulative, if a complex film is formed at the contact point between the conductive fillers or at the contact point between the conductive filler and the electrode metal, the conductivity of the conductive adhesive and the mounting There is a possibility that the electrical characteristics of the structure are slightly impaired.

On the other hand, when the manufacturing method of the present invention is used, the conductive filler is cured and its electrical conduction is ensured, and then the conductive filler is complexed. Complexing only those parts that are not involved in electrical conduction, leaving the points of contact between the conductive fillers and the points of contact between the conductive filler and other electrical structures that are conducted to the conductive adhesive layer Can be. Therefore, the charge transfer metal complex can be effectively formed while securing the electrical characteristics of the mounting structure, and a low connection resistance can be obtained.

At this time, since the complexing agent selectively reacts with the metal portion, a portion that does not require complexing treatment, that is, a resin component (such as a binder resin) of the conductive adhesive layer,
No charge transfer metal complex is formed on the surface of the electric structure (such as the surface of the substrate). Further, in the method of the present invention, since the mounting structure is manufactured using an arbitrary conductive adhesive and then complexed, the present invention is applied to a mounting structure using any type of conductive adhesive. Can be applied, its economic effect is great.

[0034] Claim 14 describes specific means for performing the above-mentioned complexing treatment. O in one molecule
Using a processing solution in which a complexing agent is dispersed in a solvent containing alcohols, ethers, esters, and ketones having at least two H groups, bringing the solution into contact with the conductive adhesive layer, and further evaporating the solvent Alternatively, the charge transfer metal complex of the present invention can be formed on the surface of the conductive filler by decomposition. The reasons are as follows. One is that by using a solvent having at least two OHs, the oxide film on the surface of the conductive filler is reduced, and a normal metal surface appears, thereby assisting the formation of the complex. Second, the presence of the OH group can strengthen the hydrogen bond between the complexing agent and the solvent, and can prevent the complexing agent from rapidly reacting with the filler during the evaporation of the solvent. That is, a film can be formed. Further, when the complexing agent has sublimability, it is possible to suppress the complexing agent from volatilizing rapidly in the solvent evaporation step.

The ligands of the complexing agent for forming the metal complex applicable to the present invention include acetylacetone, ethyl acetoacetate, allyl, cyclopentadiene,
Butene, indene, 1-methylpyridine, tropenium, chlorobutenyl, cyclohexene, cycloheptene, and derivatives thereof. The complexing agent actually used has a molecular structure in which an alkyl group, a halogen atom, a phenyl group and other appropriate molecular chains are bonded to these ligands.

If conditions other than those described in the present invention are used, a desired charge transfer metal complex cannot be formed. When the solvent in which the complexing agent is dispersed has no OH in one molecule or contains only a compound having one OH group,
Since the effect of reducing the groups is insufficient, the oxide film on the surface of the conductive filler of the conductive adhesive remains, so that the formation of the charge transfer metal complex becomes non-uniform, and the sulfidation resistance and migration resistance The improvement effect decreases. Further, since the complexing agent rapidly reacts with the conductive filler in the drying step, the obtained charge transfer metal complex becomes non-uniform, and the effect of improving the sulfidation resistance and migration resistance is reduced.

The ratio of the complexing agent to the treatment solution is as follows:
It is preferably from 1% by weight to 10% by weight. When the amount of the complexing agent is less than 1% by weight, the amount of the charge transfer metal complex formed on the filler surface is not sufficient, and the degree of improvement in the sulfuration resistance and migration resistance is reduced. The complexing agent is 10
If the amount is not less than% by weight, the unreacted complexing agent remains on the filler surface, which may undesirably cause the conductivity of the conductive adhesive to decrease.

The content of the compound having at least two OH groups is from 5% by weight to 20% by weight of the entire solvent.
Is preferable, and the rest is preferably a general solvent having one or less OH groups. If the compound having at least two OHs is less than 5% by weight of the whole solvent, the effect of reducing the surface of the filler metal and the effect of suppressing the abrupt reaction of the complexing agent become insufficient. Is undesirably low. On the other hand, if the content exceeds 20% by weight, the reaction of the complexing agent becomes too slow, the formation of the charge transfer metal complex becomes insufficient, and the effect of the present invention is unpreferably reduced. Further, the solvent may remain on the surface of the conductive filler in the drying step, which may adversely affect the humidity resistance and the like.

As described in claim 15, as a specific example of a mounting structure that can be manufactured by applying the invention described in claims 12 to 14, the conductive structure is applied to the electric structure by the conductive adhesive layer. An electrical component for electrically connecting another electrical structure, an electronic component mounted on a circuit board as described in claim 16, or a flip-chip mounting of a semiconductor device on a circuit board as described in claim 17. Can be exemplified. In particular, if the present invention is applied to a mounting structure in which an electronic component including a chip component such as a chip resistor is mounted on a circuit board, the following effects can be exerted.

When the above-mentioned electronic component is mounted, the connection site is exposed. Therefore, by performing a complexing process after the completion of the mounting structure, the charge transfer metal complex can be applied to all the connection sites at once. Can be formed. Therefore, the time required for forming the charge transfer metal complex can be reduced. In the complexing treatment, since the complexing agent selectively reacts with the metal portion, the charge transfer metal complex is not formed on a portion that does not require the complexing treatment, that is, on the surface of the substrate or the surface of the component.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1) In Embodiment 1, the present invention is applied to a conductive adhesive. FIG. 1 is an enlarged view of a main part of the conductive adhesive 1 of the present embodiment. This conductive adhesive 1 is characterized by the structure itself of the conductive adhesive 1. That is, the conductive adhesive 1 includes the conductive filler 2 having the charge transfer metal complex 3 and the organic binder 4, and is configured by mixing and dispersing the conductive filler 2 and the organic binder 4.

Here, as the conductive filler 1, in addition to silver (Ag), gold (Au), Ag-coated Cu, Cu-Ag alloy, copper (C
u), nickel (Ni), Ag-Pd alloy or the like may be used.
However, silver (Ag) is preferable in consideration of the volume resistivity and the material cost.

In the case where the conductive filler 1 is silver, the charge transfer metal complex 3 is formed of silver acetylacetone, ethyl acetoacetate silver, allyl silver, silver cyclopentadiene, silver butene, indene silver, 1-methylpyridine silver, tropenium silver, It is composed of silver chlorobutenyl, silver cyclohexene, silver cycloheptene, or the like.

(Embodiment 2) This embodiment shows a structure of a flip-chip mounting structure of a semiconductor device. As shown in FIG. 2, the mounting structure includes a circuit board 5 which is an example of an electric structure, and a semiconductor device 6 which is an example of another electric structure. Semiconductor device 6
Includes an IC substrate 7 and a bump electrode 8 provided on the surface of the IC substrate 7. The circuit board 5 has input / output terminal electrodes 9 on its surface. Then, a conductive adhesive layer 1A made of the conductive adhesive 1 described in the first embodiment is provided on the input / output terminal 9, and the input / output terminal 9 and the bump electrode 8 are connected by the conductive adhesive layer 1A. Are electrically connected. Further, a sealing resin 10 is provided in a gap between the semiconductor device 6 and the circuit board 5. As described above, the flip-chip mounting structure is configured.

(Embodiment 3) In the present embodiment, the present invention is implemented in a mounting structure of a chip component. As shown in FIG. 3, in this mounting structure, a chip resistor 13, a chip coil 14, and a chip capacitor 15, which are examples of other electric structures, are surface-mounted on electrodes 12 of a circuit board 11, which is an example of an electric structure. It is configured. The electrode 12 is provided with a conductive adhesive layer 1A made of the conductive adhesive 1 described in the first embodiment, and the conductive adhesive layer 1A allows the electrode 12 and the chip components 13, 1
4 and 15 are electrically connected.

(Embodiment 4) The above-described Embodiments 1 to
3, the conductive filler 2 included in the conductive adhesive 1 and the conductive adhesive layer 1A has the charge transfer metal complex 3 in advance. Was. In contrast, the present embodiment is characterized in that after forming a conductive adhesive layer on an electric structure, a charge transfer metal complex is formed on a conductive filler included in the conductive adhesive layer. Here, as an example, as shown in FIG. 4, a circuit board 16 which is an example of an electric structure is used.
The present invention is embodied in an electric structure in which the conductive adhesive layers 17 and 18 in the form of comb electrodes are formed by a screen printing method. It is needless to say that the same can be applied to the conductive adhesive layer provided in the above.

Hereinafter, the manufacturing method of this embodiment will be described.

First, the conductive adhesive layer 1 was formed on the circuit board 16 using the same conductive adhesive having no charge transfer metal complex.
7 and 18 are formed.

Next, a complexing agent solution is prepared by mixing a complexing agent in a solvent. Note that, depending on the surface state of the conductive filler 2 and the thickness of the charge-transfer metal complex 3 formed in the subsequent processing, the compounding ratio of the complexing agent solution and the type of solvent are different. It is not limited.

Next, the circuit board 16 is immersed in a complexing agent solution, pulled up, and then heated. Thereby, the solvent is evaporated, and the charge transfer metal complex 3 is formed on the surface of the conductive filler 2.

Hereinafter, the shape of the produced charge transfer metal complex 3 will be described in detail with reference to FIG. Conductive adhesive layer 1
The conductive adhesive 1A constituting 7, 18 is formed by mixing the conductive filler 2, the organic binder 4, and various additives.

The conductive adhesive layers 17 and 18 are formed by heat-curing the conductive adhesive 1A thus configured. At that time, many components (organic binders and the like) other than the conductive filler 2 evaporate by heating. Therefore, the conductive adhesive layers 17, 1
In FIG. 8, a large number of holes 19 from which the evaporation component has escaped are formed (see FIG. 5A).

Many of these holes 19 communicate with each other and even with the surface of the conductive filler 2. Therefore, the conductive filler 2 exposed on the inner surface of these holes 19 is exposed to the external environment. Therefore, the conductive filler 2 is easily eluted from these sites.

When the conductive adhesive layers 17 and 18 having the above structural features are immersed in the complexing agent solution, the conductive adhesive layers 17 and 18 reach the surface of the conductive filler 2 exposed at the bottom of the communicating holes 19. The complexing agent solution will arrive. Therefore, when the complexing agent solution is heat-treated to form the charge transfer metal complex 3, the charge transfer metal complex 3 is formed in the hole 19, whereby the conductive material exposed at the bottom of the hole 19 is exposed. The surface portion of the filler 2 is covered with the charge transfer metal complex 3. Therefore, the charge transfer metal complex 3 can be selectively formed only on the surface portion of the conductive filler 2 where the elution is likely to occur, and the conductive portion between the conductive fillers 2 and
The charge transfer metal complex 3 is not formed at a place where conduction is made between the other electric structure and the conductive filler 2.

Next, examples of the above-described embodiments will be described below.

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

(Example 1) This example is characterized in that the charge transfer metal complex 3 is made of allyl silver in the conductive adhesive 1 shown in the first embodiment.

A method for producing the conductive adhesive 1 of this embodiment will be described. For 10 parts by weight of allyl chloride as a complexing agent,
An alcohol solution of the complexing agent is prepared by dissolving and mixing 100 parts by weight of isopropyl alcohol. The metal complex obtained by reacting allyl chloride with a metal is a charge transfer metal complex. Since the complexing agent and the metal are bonded by a π bond, the charge transfer metal complex has a stronger bond strength than a normal metal complex and has an excellent metal elution prevention ability.

The compounding ratio of the complexing agent solution to be prepared and the type of the solvent differ depending on the surface condition of the conductive filler 2 and the thickness of the charge transfer metal complex 3 to be formed, and therefore are particularly limited to the above-mentioned conditions. Not something.

Next, the conductive filler 2 is added to the prepared complexing agent solution and sufficiently stirred. When the surface of the conductive filler 2 becomes wet with the complexing agent solution, the conductive filler 2 is removed from the complexing agent solution and dried in an oven at 100 ° C. for 30 minutes to remove the solvent isopropyl alcohol. Allow sufficient evaporation. Thereby, the allyl chloride reacts with the conductive filler 2 on the surface of the conductive filler 2, and the charge transfer metal complex 3 is formed on the conductive filler 2.

The temperature and time for this drying are also
Since it differs depending on the concentration of the complexing agent in the complexing agent solution and the amount of the conductive filler 2 to be treated, the treatment conditions are not specified.

Thus, 92% by weight of the conductive filler 2 provided with the charge transfer metal complex 3, 7% by weight of the organic binder 4 made of epoxy resin, and 1% by weight of the additive (dispersant, adhesion , Etc.) to obtain a conductive adhesive of this example.

(Example 2) In this example, in the conductive adhesive of Example 1, 1 was used as the solvent for dissolving the complexing agent.
It is characterized in that a mixed solvent of 10 parts by weight of diethylene glycol, which is a solvent containing two OH groups in a molecule, and 90 parts by weight of isopropyl alcohol is used.

The conductive adhesives of Comparative Examples 1 and 2 were prepared corresponding to Examples 1 and 2 described above.

(Comparative Example 1) This conductive adhesive was made of silver (A
g), 92% by weight of the conductive filler 2 composed of g), 7% by weight of the organic binder 4 composed of an epoxy resin, and 1% by weight of an additive (dispersant, adhesion improver, etc.) are dispersed and mixed. It is configured.

(Comparative Example 2) This conductive adhesive has a configuration in which pyrogallol is used as the complexing agent in Example 1 of the present invention. The metal complex obtained by the reaction between pyrogallol and a metal is a normal metal complex, and the complexing agent and the metal are bonded by a σ bond (single bond).

Using the conductive adhesives 1 of Examples 1 and 2 and Comparative Examples 1 and 2 produced as described above, a conductive adhesive layer was formed and evaluated and measured according to the following method.

(1) Evaluation of Ion Migration Resistance (Water Drop Test) The water drop test is a test method for simply and simply evaluating the migration property of a material. Details of the test method are as follows. As test samples,
A structure similar to the structure of the circuit board described in Embodiment 4 is employed. That is, as shown in FIG.
Comb-shaped electrode-shaped conductive adhesive layers 17 and 18 are formed thereon by a screen printing method. Here, the circuit board 16
, A ceramic substrate is used. Further, the conductive adhesive layers 17 and 18 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 during

The conductive adhesive layer 1 thus formed
Deionized water is dropped on the layers 7 and 18 to form the conductive adhesive layer 1
A DC voltage (1 V) is applied between 7 and 18. Then, the time from when the conductive adhesive layers 17 and 18 were short-circuited to when the current flowed was measured, and the migration resistance was evaluated based on the length of the short-circuit time.

(2) Evaluation of anti-sulfuration reactivity As shown in FIG. 6, after a gold-plated electrode 20 is formed on a circuit board 23 made of a glass epoxy substrate, the gold-plated electrode 20 is further formed from a conductive adhesive by a screen printing method. The conductive adhesive layer 21 is formed. Then, on the conductive adhesive layer 21, 3 is mounted using a mount mounting machine.
216 size 0Ω resistance (terminal plating: SnPb solder) 2
2 is mounted. Next, in order to cure the conductive adhesive layer layer 21, it is heated in an oven at 150 ° C. for 30 minutes.
After measuring the initial connection resistance of the sample prepared in this manner, the sample is left to stand in a closed tank filled with hydrogen sulfide, and the change in the connection resistance is measured to evaluate the resistance to sulfuration reaction. The test conditions were a temperature of 40 ° C and a humidity of 90.
%, The concentration of hydrogen sulfide was 3 ppm, and the test time was 96 hours.

Table 1 shows the results of the evaluation and measurement.
Shown in

[0073]

[Table 1]

With the conductive adhesive 1 of Examples 1 and 2, the following was found as compared with Comparative Examples 1 and 2. That is, in the evaluation of the resistance to ion migration, the time until current flow was longer than in Comparative Examples 1 and 2, and it was confirmed that the resistance to ion migration was improved.
Also in the evaluation of the sulfurization reactivity, the change in the connection resistance before and after the test was smaller than in Comparative Examples 1 and 2, and it was confirmed that the sulfuration reactivity was improved.

From these facts, the conductive adhesive of the present invention has a conventional conductive adhesive having no metal complex on the surface of the metal filler (Comparative Example 1) and a conventional metal complex on the surface of the metal filler. Than the conductive adhesive (Comparative Example 2)
It was found that the ion migration resistance and the sulfidation resistance were improved.

Further, when Examples 1 and 2 were compared, the following was confirmed. That is, Example 2 containing diethylene glycol having two OH groups in the molecule was more effective than Example 1 using only isopropyl alcohol having one OH group in the molecule as the dispersing solvent for the complexing agent, It was confirmed that the ion migration resistance and the sulfidation resistance were good.

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

Example 3 In this example, the conductive adhesive of Example 1 using allyl resin as the charge transfer metal complex 3 and isopropyl alcohol as a dispersing solvent for the complexing agent (however, the organic binder was used as the organic binder) The semiconductor device 6 is flip-chip mounted on the circuit board 5 by only using an epoxy resin having thermoplasticity), which is characteristic.

That is, the bump electrode 8 of the semiconductor device 6
Then, the conductive adhesive 1 described in the mounting example 1 is transferred by a known method. Then, the semiconductor device 6 is flip-chip mounted on the circuit board 5 with the transferred conductive adhesive 1 aligned with the input / output terminal electrodes 9 of the circuit board 5. Then, an electrical inspection is performed after the conductive adhesive 1 is cured, and when a good result is obtained, the sealing resin 10 of the epoxy resin is supplied between the circuit board 5 and the semiconductor device 6 to be cured. The connection was sealed to form a flip-chip mounting structure.

(Example 4) In this example, allyl silver was used as the charge transfer metal complex 3, and as the solvent in which the complexing agent was dispersed, a mixed solvent of isopropyl alcohol and diethylene glycol was used. The flip chip mounting structure is constituted by using the agent 1, which is characterized in this point. Except for the conductive adhesive 1, the configuration and the manufacturing method of the flip-chip mounting structure are exactly the same as those of the third embodiment.

(Comparative Examples 3 and 4) Flip-chip mounting structures of Comparative Examples 3 and 4 were produced corresponding to Examples 3 and 4 described above.

These flip-chip mounting structures had the same mounting structure as in Examples 3 and 4, using the conductive adhesives of Comparative Examples 1 and 2.

The reliability of the flip-chip mounted structures of Examples 3 and 4 and Comparative Examples 3 and 4 manufactured as described above was evaluated according to the following method.

That is, by applying a current (10 mA) during actual use to these flip-chip mounting structures and measuring the change in connection resistance under a high-temperature and high-humidity environment (85 ° C., 85%). The evaluation measurement of migration resistance was performed. Similarly, by measuring the change in connection resistance in a hydrogen sulfide atmosphere (40 ° C., 90%, hydrogen sulfide concentration 3 ppm) while passing a current (10 mA) during actual use, an evaluation measurement of the resistance to sulfidation was carried out. did. The results are shown in (Table 2).

[0085]

[Table 2]

In the flip chip mounting structures of Examples 3 and 4, the following was found as compared with Comparative Examples 3 and 4. That is, in the evaluation of the resistance to ion migration, the time until current flow was longer than in Comparative Examples 3 and 4, and it was confirmed that the resistance to ion migration was improved. Also, in the evaluation of the sulfidation reactivity, the change in the connection resistance before and after the test was smaller than in Comparative Examples 3 and 4, confirming that the sulfidation reactivity was improved.

From the above, the conductive adhesive of the present invention has a conventional conductive adhesive having no metal complex on the surface of the metal filler (Comparative Example 3) and a conventional metal complex on the surface of the metal filler. More than the conductive adhesive (Comparative Example 4)
It was found that the ion migration resistance and the sulfidation resistance were improved.

Further, when Examples 3 and 4 were compared, the following was confirmed. That is, Example 4 containing diethylene glycol having two OH groups in the molecule was more resistant than Example 3 using only isopropyl alcohol having one OH group in the molecule as the dispersing solvent for the complexing agent. It was confirmed that the ion migration property and the sulfidation resistance were good.

As described above, the third and fourth embodiments (flip-chip mounting structure) can obtain the same effects as those of the first and second embodiments (conductive adhesive).

In Examples 3 and 4, the electrical connection between the semiconductor device 6 and the circuit board 5 was made using the conductive adhesive 1 having the organic binder 4 of a thermoplastic epoxy resin. As in the first embodiment, it goes without saying that the same effect is exhibited even when a thermosetting epoxy resin is used.

In Examples 3 and 4, the charge-transfer metal complex 3 was used to replace the connection points (the conductive filler 2 and the bump electrode 8, the conductive fillers 2 and the conductive filler 2 and the input / output terminal electrode 9). It is considered that it may hinder the electrical connection. However, when performing flip chip mounting,
Since the circuit board 5 and the semiconductor device 6 are pressure-bonded, the charge transfer metal complex 3 at the location where the pressure is applied (connection location) is damaged, and the connection location is directly electrically connected. Does not interfere with

Next, examples of the third embodiment (chip component mounting structure) will be described.

(Embodiment 5) This embodiment is a chip component mounting structure manufactured by using the conductive adhesive of Embodiment 1. In Example 1, the charge-transfer metal complex 3 made of allyl silver was used, and isopropyl alcohol was used as a dispersion solvent for the complexing agent. This chip component mounting structure is a circuit board 11 (3
After the electrodes 12 are formed by gold (Au) plating on 0 mm × 60 mm, 1.6 mm in thickness, five chip resistors 13 (32
16 size, SnPb plating).

This chip component mounting structure was manufactured as follows. First, the conductive adhesive 1 is screen-printed on the electrode 12 of the circuit board 11. And chip part 1
3, 14 and 15 were converted to electrodes 1 using existing component mounting equipment.
After being mounted on 2, the conductive adhesive 1 was cured by heating in an oven at 150 ° C. for 30 minutes.

(Embodiment 6) In this embodiment, a chip component mounting structure is formed using the conductive adhesive 1 of Embodiment 2, which is characterized in this point. In Example 2, allyl silver was used as the charge transfer metal complex, and a mixed solvent of isopropyl alcohol and diethylene glycol was used as the dispersing solvent for the complexing agent. Except for the conductive adhesive 1, the configuration and manufacturing method of the chip component mounting structure are exactly the same as those of the fifth embodiment.

(Comparative Examples 5 and 6) Chip component mounting structures of Comparative Examples 5 and 6 were produced corresponding to Examples 5 and 6 described above.

These chip component mounting structures had the same mounting structure as in Examples 5 and 6, using the conductive adhesives of Comparative Examples 1 and 2.

The reliability of the chip component mounting structures manufactured as described above and the chip component mounting structures of Comparative Examples 5 and 6 were evaluated in the same manner as in Examples 3 and 4.

The results are shown in (Table 3).

[0100]

[Table 3]

In the chip component mounting structures of Examples 5 and 6, the following was found as compared with Comparative Examples 5 and 6. That is, in the evaluation of the ion migration resistance, the time until the current flows is longer than in Comparative Examples 5 and 6,
It was confirmed that the ion migration resistance was improved. Also in the evaluation of the sulfidation reactivity, the change in the connection resistance before and after the test was smaller than in Comparative Examples 5 and 6, confirming that the sulfidation reactivity was improved.

Further, when Examples 5 and 6 were compared, the following was confirmed. That is, Example 6 containing diethylene glycol having two OH groups in the molecule was more resistant than Example 5 using only isopropyl alcohol having one OH group in the molecule as the dispersing solvent for the complexing agent. It was confirmed that the ion migration property and the sulfidation resistance were good.

As described above, Embodiments 5 and 6 (chip component mounting structure) have the same effects as Embodiments 1 and 2 (conductive adhesive) and Embodiments 3 and 4 (flip chip mounting structure). can get.

Hereinafter, examples of the fourth embodiment of the present invention will be described.

A circuit board 6 (see FIG. 4) having the same structure as that manufactured for evaluation and measurement in Examples 1 and 2 is prepared. Then, the conductive adhesive layers 17 and 18 are formed on the circuit board 6 using the conductive adhesive of Comparative Example 1 (conventional example). The method of forming the conductive adhesive layers 17 and 18 is the same as that of the test samples of Examples 1 and 2 and Comparative Example 1.

Next, a complexing agent solution is prepared by mixing 10 parts by weight of allyl chloride with 90 parts by weight of isopropyl alcohol and 10 parts by weight of diethylene glycol. Note that, depending on the surface state of the conductive filler 2 and the thickness of the charge transfer metal complex 3 to be formed in the subsequent processing, the compounding ratio of the complexing agent solution and the type of solvent are different. It is not so limited.

The circuit board 16 was immersed in the complexing agent solution for 30 seconds, pulled up, and dried at 100 ° C. for 30 minutes, so that the conductive filler 2 contained in the conductive adhesive layers 17 and 18 was added to the metal. While forming the charge transfer metal complex 3 composed of a complex, isopropyl alcohol is evaporated.
Thus, a test sample shown in FIG. 4 was obtained.

The test samples manufactured as described above are structurally similar to the test samples of Examples 1 and 2, which are examples of the first embodiment. Therefore, in order to compare this example with Example 2, an evaluation test was performed according to the same test method as in Example 1. The results are shown in Table 1 above.

As a result, in the mounting structure manufactured by the manufacturing method of this embodiment, in the evaluation of the resistance to ion migration, a charge transfer metal complex 3 was previously formed on the conductive filler 2 in the same manner as in Example 2 It was confirmed that characteristics were obtained. Also, in the evaluation of the sulfidation resistance, it was confirmed that there was no increase in the connection resistance, and that the absolute value of the connection resistance was lower than that in Example 2.

(Example 8) A flip-chip mounting structure having the same configuration as that of Comparative Example 3 is formed. However, at this time, the gap between the semiconductor device 6 and the circuit board 5 is not sealed with the sealing resin 10. In this state, the same complex processing agent as in Example 7 is injected into the gap between the semiconductor device 6 and the circuit board 5 using a syringe. And at 100 ° C
By drying for 0 minutes, the charge transfer metal complex 3 composed of a metal complex was formed on the surface of the conductive filler 3, and the solvent was further evaporated.

Next, a test sample of the flip-chip mounting structure was obtained by injecting the sealing resin 10 into the gap between the semiconductor device 6 and the circuit board 5 and curing the resin.

The test samples manufactured as described above are structurally the same as the test samples of Examples 3 and 4, which are examples of the second embodiment. Therefore, in order to compare this example with Example 3, an evaluation test was performed according to the same test method as that of Example 3. The results are also shown in Table 2 above.

As a result, in the flip-chip mounting structure manufactured by the manufacturing method of the present embodiment, the charge transfer metal complex 3 was previously formed on the conductive filler 2 in the ion migration resistance evaluation. It was confirmed that equivalent characteristics could be obtained. Also, in the evaluation of the sulfidation reactivity, it was confirmed that there was no increase in the connection resistance, and that the absolute value of the connection resistance was lower than that in Example 3.

Example 9 A chip component mounting structure having the same configuration as that of Comparative Example 5 is formed. And Example 7
Dipping in a complexing agent solution similar to the complexing agent solution used in step 30 for 30 seconds, pulling it up, and drying it at 100 ° C. for 30 minutes to form the conductive filler 2 contained in the conductive adhesive layer 21
Next, a charge transfer metal complex 3 composed of a metal complex is formed, and the solvent is evaporated. Thus, a test sample shown in FIG. 6 was obtained.

The test samples manufactured as described above are structurally similar to the test samples of Examples 5 and 6 which are examples of the third embodiment. Therefore, in order to compare this example with Example 5, an evaluation test was performed according to a test method similar to that of Example 5. The results are also shown in Table 3 above.

As a result, in the chip component mounting structure manufactured by the manufacturing method of the present example, the charge transfer metal complex 3 was formed in advance on the conductive filler 2 in the ion migration resistance evaluation. It was confirmed that equivalent characteristics could be obtained. Also, in the evaluation of the sulfidation resistance, it was confirmed that there was no increase in the connection resistance, and that the absolute value of the connection resistance was lower than that of Example 5.

In the examples of the present invention, only the allyl silver is described as a specific example of the charge transfer metal complex formed on the surface of the metal filler of the conductive adhesive, but as described in the embodiment. It is clear that other charge transfer metal complexes may be used.

[0118]

As described above, according to the present invention, it is possible to obtain a mounting structure having better ion migration resistance or sulfurization reaction resistance than the conventional one.

Further, if 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 a connection interval between electrodes or the like in order to improve insulation reliability. It is also possible to realize space saving of the mounting structure.

Further, according to the present invention, since the reliability of the sulfidation reaction is improved, it can be applied to products that may be used in a gas atmosphere containing a large amount of sulfur, such as near a hot spring or near a volcano. 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. 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 manufactured by a method according to Embodiment 4 of the present invention.

FIG. 5 is a cross-sectional view of a conductive adhesive layer manufactured by the method of Embodiment 4.

FIG. 6 is a plan view of a test sample used in the evaluation of resistance to sulfidation reactivity.

[Explanation of symbols]

 Reference Signs List 1 conductive adhesive 1A, 17, 18, 21 conductive adhesive layer 2 conductive filler 3 charge transfer metal complex 4 organic binder 5, 11, 16, 23 circuit board 6 semiconductor device 7 IC substrate 8 bump electrode 9 input / output Terminal electrode 10 Sealing resin 12 Electrode 13 Chip resistor 14 Chip coil 15 Chip capacitor 19 Void 20 Gold plated electrode 220 OΩ resistance

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takashi Kitae 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. 72) Inventor Tosaku Nishiyama 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture F-term in Matsushita Electric Industrial Co., Ltd. 4J040 EC001 HA066 HD43 KA10 KA32 LA07 LA09 NA20 PA29 PA38 QA01 5E319 AA03 AB05 BB11 CD25 GG20 5F044 LL07

Claims (17)

[Claims] 1. An electric structure, and a conductive adhesive layer provided on the electric structure, wherein the conductive adhesive layer has a conductive filler, and at least a part of the conductive filler. And a charge transfer metal complex. 2. The mounting structure according to claim 1, wherein the charge transfer metal complex is an organometallic compound formed by coordinating a chelate ligand to a metal. 3. The mounting structure according to claim 2, wherein in the organometallic compound, the ligand and the metal are bonded by a π bond. 4. 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 1, wherein: 5. The conductive filler according to claim 1, wherein at least a part of the conductive filler is exposed on the surface of the conductive adhesive layer, and the charge transfer metal complex is provided at least on the exposed portion. Mounting structure. 6. The conductive adhesive layer has a large number of holes communicating with each other and communicating with the surface of the adhesive layer.
At least a part of the conductive filler is exposed on an inner surface of the hole, and the charge transfer metal complex is provided on at least the conductive filler exposed on the inner surface of the hole. 6. The mounting structure according to any one of 1 to 5. 7. The mounting structure according to claim 6, wherein the conductive filler contains silver. 8. The mounting structure according to claim 4, wherein the electric structure is a circuit board, and the other electric structure is an electronic component mounted on the circuit board. 9. The mounting structure according to claim 8, wherein the other electric structure is a semiconductor device that is flip-chip mounted on the electric structure formed of the circuit board. 10. An electrically conductive adhesive comprising an electrically conductive filler, wherein at least a part of the electrically conductive filler has a charge transfer metal complex. 11. The conductive adhesive according to claim 10, wherein the conductive filler contains silver. 12. A step of forming a conductive adhesive layer having a conductive filler on an electric structure, and wherein the conductive adhesive layer is cured and then communicates with a surface of the conductive adhesive layer. Forming a charge-transfer metal complex on the conductive filler. 13. After the conductive adhesive layer is cured, a complexing agent that reacts with a metal to form a charge transfer complex acts on the conductive adhesive layer to form the charge transfer metal complex. The method for manufacturing a mounting structure according to claim 12, wherein: 14. A complexing agent which forms a charge transfer metal complex is dispersed in a solvent containing at least one of alcohols, ethers, esters or ketones having at least two OH groups in one molecule. 2. A charge transfer metal complex is formed on the filler surface of the conductive adhesive by contacting the treated solution with the conductive adhesive layer and evaporating or decomposing the solvent.
3. The method for manufacturing the mounting structure according to 3. 15. The method according to claim 12, wherein the conductive adhesive layer electrically connects another electric structure to the electric structure. 16. The method according to claim 12, wherein the electric structure is a circuit board, and the other electric structure is an electronic component mounted on the circuit board. 17. The method according to claim 10, wherein the other electric structure is a semiconductor device that is flip-chip mounted on the circuit board.