JP2008280601A - Joining method and joining structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a joining method using metal nanoparticles by which the joinability of a joining material is increased while evading the resistance value of joined parts from increasing and also cost from raising. <P>SOLUTION: By tightly sticking the surface of a member 10 to be joined with a first joining material 12A in which the containing ratio of metal nanoparticles 18S with relatively small particle sizes is increased, the joinability between the member 10 and the metal nanoparticles 18S increases. Further, the relatively small metal nanoparticles 18S largely comprised in the first joining material 12A can not absorb the ruggedness in the surface of the member 10 since the size of the metal nanoparticles is smaller than that of the ruggedness in the surface of the member 10, but the ruggedness can be absorbed by a second joining material 12B having excellent ruggedness absorbability owing to the incorporation of metal nanoparticles 18L with relatively large particle sizes. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a joining method for joining joined members by heating and firing in a state where metal nanoparticles are held at predetermined positions between the joined members.

Conventionally, various methods such as soldering, bonding, and welding have been used as methods for joining members together. On the other hand, in consideration of the fact that in recent years, further consideration for environmental pollution has been demanded and depending on the nature of the members to be joined, these conventional joining methods may be inappropriate. Are different from each other, and a joining technique using metal nanoparticles is used (see, for example, Patent Document 1).
In this bonding technique using metal nanoparticles, a bonding material containing metal nanoparticles coated with an organic protective film and a binder is applied to a predetermined position of a member to be bonded and held between the members to be bonded. In this state, the members to be joined are bonded to each other by heating and pressurizing the members to be joined and the joining material and firing the joining members. The metal nanoparticles used here are covered with an organic protective film to prevent the particles from adhering to each other, and are further treated as a paste-like bonding material at room temperature by mixing a binder and a solvent. And when baking a joining member, by heating a to-be-joined member and joining material, and pressurizing to-be-joined members, a binder, a solvent, and an organic protective film are decomposed | disassembled and evaporated, and metal nanoparticles are closely_contact | adhered , To be joined.

JP 2004-130371 A

The specific joining procedure in the joining technique using metal nanoparticles is as shown in FIG.
(I) Application process: The bonding material 12 in which the metal nanoparticles 18 covered with the organic protective film 16, the binder 20, and the solvent 22 are mixed is applied to the bonding surface of the member to be bonded 10 (10A). In the illustrated example, the bonded member 10 is a copper plate, the metal nanoparticles 18 are silver nanoparticles, the binder 20 is a resin flux for soldering, and the solvent 22 is alcohol.
(Ii) Drying step: The bonding material 12 applied to the bonding surface of the member to be bonded 10 in the application step is dried, and the solvent 20 is evaporated from the bonding material 12.
(Iii) Assembling step: The member 10 (10B) to be joined is applied to the member 10 (10A) to which the joining material 12 is applied, and the joining material 10 (10A, 10B) is joined by the two members 10 (10A, 10B). 12 is pinched.
(Iv) heating and pressurizing step: bonding material 12 while heating so that the junction temperature or higher, at a pressure _{P 1,} pressurizing the bonded member to each other 10 (10A, 10B).
(V) Joining step (joining completion step): Applying pressure to obtain the required joining strength to the member to be joined 10 (10A, 10B) in a state where the joining material 12 is maintained at or above the joining temperature. Thus, the members 10 (10A, 10B) to be joined are joined together.

  In the bonding method using the metal nanoparticles described above, at the time of pressure and firing (step (iv)), the decomposed organic protective film 16 reduces the oxide film formed on the surface of the member to be bonded 10, and the member to be bonded By activating the surface of 10, high bondability can be obtained between the member to be bonded 10 and the metal nanoparticles 18. In addition, the smaller the particle size of the metal nanoparticles 18, the better the bondability at a low temperature. Therefore, the bondability between the member to be bonded 10 and the metal nanoparticles 18 is further enhanced.

  On the other hand, when the particle size of the metal nanoparticles 18 is small, the amount of decomposition gas of the organic protective film generated at the time of pressurization / firing increases, and the decomposition gas is ejected from the bonding material at a stretch to bond the binder 20 and the metal nanoparticles 18 together. As a result, the bonding strength is reduced. FIG. 5 schematically shows a fracture surface obtained by peeling the members joined using the metal nanoparticles 18. Here, (a) shows a normal fracture surface, and (b) shows a defective fracture surface when the metal nanoparticles 18 are blown off from the joint surface. In the normal fracture surface of (a), the bonding material 12 spreads uniformly on the surface of the member 10 to be joined. On the other hand, in the defective fracture surface of (b), the gas ejection trace 14 causes unevenness in the bonding material 12. You can see that

On the other hand, when metal nanoparticles 18 having a small particle size are used, and when the coating thickness of the bonding material 12 is reduced in order to avoid an increase in the decomposition gas of the organic protective film, the metal is larger than the unevenness on the surface of the bonded member 10. Since the size of the nanoparticles 18 is small and it is impossible to absorb the irregularities on the surface of the member to be bonded 10 by the metal nanoparticles 18, there arises a problem that both the bonding property and the conductivity decrease, and the firing state Depending on the above, there arises a problem that the resistance value increases. Of course, the smaller the particle size of the metal nanoparticles 18, the higher the production cost of the metal nanoparticles 18.
The present invention has been made in view of the above-mentioned problems, and the object of the present invention is to join the metal nanoparticle in the joining method while avoiding an increase in the resistance value of the joining portion and an increase in cost. It is to improve the bondability of the material.

(Aspect of the Invention)
The following aspects of the present invention exemplify the configuration of the present invention, and will be described separately for easy understanding of various configurations of the present invention. Each item does not limit the technical scope of the present invention. Therefore, the technical aspects of the present invention also apply to those in which some of the constituent elements in each section are replaced, deleted, or other constituent elements are added while taking into account the best mode for carrying out the invention. It can be included in the range.

(1) Joining joining members to be joined by heating and baking a joining material containing metal nanoparticles coated with an organic protective film in a predetermined position between two joined members. A method,
The surface of one member to be bonded is coated with a first bonding material with a high content ratio of metal nanoparticles having a relatively small particle size, and the surface of the member to be bonded has excellent irregularity absorbability. The second bonding material is further stacked, and further, the first bonding material is stacked on the second bonding material or applied to the surface of the other bonded member, and the bonded members are stacked, A joining method comprising pressurizing the members to be joined together while heating so that the joining material has a temperature equal to or higher than the joining temperature (Claim 1).

  In the bonding method described in this section, the first bonding material having a higher content ratio of metal nanoparticles having a relatively small particle size is in close contact with the surface of the member to be bonded. The bondability of is increased. On the other hand, the size of the metal nanoparticles contained in the first bonding material is smaller than the unevenness on the surface of the member to be bonded, and the metal nanoparticles cannot absorb the unevenness on the surface of the member to be bonded. Instead, the unevenness can be absorbed by the second bonding material. Therefore, it is possible to secure sufficient bondability and conductivity while reducing the coating thickness of the first bonding material and avoiding an excessive increase in the decomposition gas of the organic protective film generated from the entire bonding material.

(2) In the above item (1), the first bonding material is a bonding material containing 75 vol% or more of metal nanoparticles having a particle size of 50 nm or less, and the second bonding material is metal nanoparticles of 100 nm or more. Is a bonding material containing 50 vol% or more (Claim 2).
In the bonding method described in this section, the first bonding material contains 75 vol% or more of metal nanoparticles having a particle size of 50 nm or less, so that the bonding property between the bonded member and the metal nanoparticles in the vicinity of the bonded member is increased. Rise. In addition, since the second bonding material contains 50 vol% or more of metal nanoparticles having a size of 100 nm or more, the metal member having a particle size of 50 nm or less contained in the first bonding material cannot be absorbed. The surface irregularities are absorbed by metal nanoparticles of 100 nm or more. In addition, the bondability between metal nanoparticles is good regardless of the particle size.

(3) In the above item (1), the first bonding material is a bonding material containing 75 vol% or more of metal nanoparticles having a particle size of 50 nm or less, and the second bonding material includes coarse metal particles and metal nanoparticles. A bonding method which is a bonding material containing mixed particles with particles (claim 3).
In the bonding method described in this section, the first bonding material contains 75 vol% or more of metal nanoparticles having a particle size of 50 nm or less, so that the bonding property between the bonded member and the metal nanoparticles in the vicinity of the bonded member is increased. Rise. In addition, the second bonding material contains mixed particles of coarse metal particles and metal nanoparticles, so that the irregularities on the surface of the member to be joined are absorbed by the coarse metal particles and the metal nanoparticles. Note that the bonding properties of the coarse metal particles and the metal nanoparticles are good regardless of the particle size.

That is, in the above items (2) and (3), the bonding material containing the metal nanoparticles coated with the organic protective film is heated and fired in a state where the bonding material is held at a predetermined position between the two bonded members. A joining method for joining members to be joined together,
The bonding material is configured in multiple layers so that the ratio of the particle size of the metal nanoparticles contained in the surface of the member to be bonded and its vicinity and the other part are different, and the members to be bonded are overlapped. The members to be joined are pressurized while being heated so that the joining material has a temperature equal to or higher than the joining temperature.

(4) In the method (1), the first bonding material is a bonding material containing 75 vol% or more of metal nanoparticles having a particle size of 50 nm or less, and the second bonding material is a metal foil. (Claim 4).
In the bonding method described in this section, the first bonding material contains 75 vol% or more of metal nanoparticles having a particle size of 50 nm or less, so that the bonding property between the bonded member and the metal nanoparticles in the vicinity of the bonded member is increased. Rise. Moreover, the unevenness | corrugation on the surface of a to-be-joined member is absorbed with metal foil because the 2nd joining material is metal foil. In addition, the bondability between the metal foil and the metal nanoparticles is good. Moreover, it is desirable to use a silver foil or a copper foil as the metal foil in consideration of the balance between bondability and material cost.

In the above items (2) to (4), that is, a bonding material containing metal nanoparticles coated with an organic protective film is heated and fired in a state where the bonding material is held at a predetermined position between two bonded members. A joining method for joining members to be joined together,
A first bonding material excellent in reducing the oxide film on the surface of the member to be bonded is applied to the surface of one member to be bonded, and the surface of the member to be bonded has excellent irregularity absorbability. The second bonding material is stacked, and the first bonding material is stacked on the second bonding material or applied to the surface of the other bonded member, and the bonded members are overlapped with each other, and the bonding is performed. The members to be joined are pressurized while being heated so that the material becomes equal to or higher than the joining temperature.

(5) The bonding material containing the metal nanoparticles coated with the organic protective film is heated and fired in a state where the bonding material is held at a predetermined position between the two bonded members, thereby bonding the bonded members to each other. A bonded structure formed by bonding,
A first bonding material having a higher content ratio of metal nanoparticles having a relatively small particle size is applied to the surface of one of the members to be bonded, and the first bonding material has excellent unevenness absorbability on the surface of the member to be bonded. The second bonding material is stacked, and further, the first bonding material is stacked on the second bonding material or applied to the surface of the other bonded member, and the bonded members are stacked. The joining members are pressed while being heated so that the joining material has a temperature equal to or higher than the joining temperature (Claim 5).

  In the bonding structure described in this section, the first bonding material having a higher content ratio of metal nanoparticles having a relatively small particle size is in close contact with the surface of the member to be bonded, thereby bonding to the surface of the member to be bonded. Is improved, and the bondability between the member to be bonded and the metal nanoparticles is increased. On the other hand, the size of the metal nanoparticles contained in the first bonding material is smaller than the unevenness on the surface of the member to be bonded, and the metal nanoparticles cannot absorb the unevenness on the surface of the member to be bonded. Instead, since the unevenness can be absorbed by the second bonding material, the coating thickness of the first bonding material is reduced, and the decomposition gas of the organic protective film generated from the entire bonding material is excessively increased. It is possible to ensure sufficient bondability and conductivity while avoiding the above.

(6) In the item (5), the first bonding material is a bonding material containing 75 vol% or more of metal nanoparticles having a particle size of 50 nm or less, and the second bonding material is metal nanoparticles of 100 nm or more. Is a bonding structure containing 50 vol% or more.
In the bonding structure described in this section, when the first bonding material contains 75 vol% or more of metal nanoparticles having a particle size of 50 nm or less, the bonding property between the bonded member and the metal nanoparticles in the vicinity of the bonded member is improved. Rise. In addition, since the second bonding material contains 50 vol% or more of metal nanoparticles having a size of 100 nm or more, the bonded member that cannot be absorbed by the metal nanoparticles having a particle size of 50 nm or less contained in the first bonding member. Surface irregularities are absorbed by metal nanoparticles of 100 nm or more. In addition, the bondability between metal nanoparticles is good regardless of the particle size.

(7) In the item (5), the first bonding material is a bonding material containing 75 vol% or more of metal nanoparticles having a particle size of 50 nm or less, and the second bonding material includes coarse metal particles and metal nanoparticles. A bonding structure which is a bonding material containing mixed particles with particles (claim 7).
In the bonding structure described in this section, the first bonding material contains 75 vol% or more of metal nanoparticles having a particle size of 50 nm or less, so that the bonding property between the member to be bonded and the metal nanoparticles is increased. In addition, the second bonding material includes mixed particles of coarse metal particles and metal nanoparticles (particles in which coarse metal particles and metal nanoparticles are mixed), so that irregularities on the surface of the member to be joined can be obtained. It is absorbed by particles and metal nanoparticles. Note that the bonding properties of the coarse metal particles and the metal nanoparticles are good regardless of the particle size.

That is, in the above items (6) and (7), the joining material containing the metal nanoparticles coated with the organic protective film is heated and fired in a state where the joining material is held at a predetermined position between the two members to be joined. It is a joining structure formed by joining members to be joined,
The bonding material is configured in multiple layers so that the ratio of the particle size of the metal nanoparticles contained in the surface of the member to be bonded and the vicinity thereof and the other parts are different, and the members to be bonded are overlapped. The members to be joined are pressed while being heated so that the joining material has a temperature equal to or higher than the joining temperature.

(8) In the item (5), the first bonding material is a bonding material containing 75 vol% or more of metal nanoparticles having a particle size of 50 nm or less, and the second bonding material is a metal foil. (Claim 8).
In the bonding structure described in this section, the first bonding material contains 75 vol% or more of metal nanoparticles having a particle size of 50 nm or less, so that the bonding property between the member to be bonded and the metal nanoparticles is increased. Moreover, the unevenness | corrugation on the surface of a to-be-joined member is absorbed with metal foil because the 2nd joining material is metal foil. In addition, the bondability between the metal foil and the metal nanoparticles is good. Moreover, it is desirable to use a silver foil or a copper foil as the metal foil in consideration of the balance between bondability and material cost.

That is, in the above items (6) to (8), the bonding material containing the metal nanoparticles coated with the organic protective film is heated and fired in a state where the bonding material is held at a predetermined position between the two bonded members. It is a joining structure formed by joining members to be joined,
The 1st joining material excellent in the joining property to this to-be-joined member surface is apply | coated to the surface of one to-be-joined member, and the 2nd which was excellent in the uneven | corrugated absorbability of the to-be-joined member surface to this 1st joining material Further, the first bonding material is superimposed on the second bonding material or applied to the surface of the other bonded member, and the bonded members are overlapped with each other, The members to be joined are pressed while being heated so that the joining material has a temperature equal to or higher than the joining temperature.

  Since this invention was comprised in this way, in the joining method using a metal nanoparticle, it becomes possible to improve the joining property of joining material, avoiding the increase in resistance value of a junction part, and the increase in cost.

The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the part which is the same as that of a prior art, or an equivalent part, and detailed description is abbreviate | omitted.
As shown in FIG. 1 (a), the bonded structure between the bonded members using metal nanoparticles according to the first embodiment of the present invention is on the surface of one bonded member 10 (10A). The first bonding material 12A is applied, the second bonding material 12B is overlapped on the surface of the first bonding material 12A, and the first bonding material 12A is further stacked on the second bonding material 12B, or It is applied to the surface of the other member to be bonded 10 (10B), and the members to be bonded 10A and 10B are superposed.

  Here, the first bonding material 12A is obtained by increasing the content ratio of the metal nanoparticles 18S having a relatively small particle size. Specifically, the metal nanoparticles having a particle size of 50 nm or less are used as the metal nanoparticles. It contains 75 vol% or more of the total mass. The second bonding material 12B mainly includes metal nanoparticles 18L having a relatively large particle size. Specifically, the metal nanoparticles having a size of 100 nm or more are mixed with 50 vol% of the total mass of the metal nanoparticles. Including the above.

  Further, as a procedure of the bonding operation, the second bonding material 12B is obtained by evaporating the solvent 20 from the first bonding material 12A applied to the surface of one of the members to be bonded 10 (10A). It is applied over the material 12A. Similarly, when the first bonding material 12A is applied again on the second bonding material 12B, the first bonding material 12A is evaporated after the solvent 20 is evaporated from the second bonding material 12B. Is applied. Furthermore, after evaporating the solvent 20 from the first bonding material 12A applied over the second bonding material 12B or applied to the surface of the other bonded member 10 (10B), the bonded material is bonded. The members 10A and 10B are overlapped. And while joining material 12 (12A, 12B) is heated so that it may become the joining temperature or more, to-be-joined members are pressurized, the binder 20 decomposes | disassembles and evaporates, and finally FIG. 1 ( As shown in b), the member to be bonded 10 and the metal nanoparticles 18S and 18L are bonded in a state of being in close contact with each other.

  Note that FIG. 4 illustrates a process in which the members to be bonded are pressed while being superposed on each other and heated so that the bonding material 12 (12A, 12B) is equal to or higher than the bonding temperature. Since it is the same as the conventional (iii) assembly process, (iv) heating / pressurization process, and (v) joining process (joining completion process), detailed description is omitted.

  Moreover, the joining structure of the to-be-joined members using the metal nanoparticle based on the 2nd Embodiment of this invention is the surface of one to-be-joined member 10 (10A), as FIG. 2 (a) shows. In addition, the first bonding material 12A is applied, the second bonding material 12C is superimposed on the surface of the first bonding material 12A, and the first bonding material 12A is further stacked on the second bonding material 12C. Or it apply | coats on the surface of the other to-be-joined member 10 (10B), and the to-be-joined members 10A and 10B are piled up.

Here, as in the first embodiment of the present invention, the first bonding material 12A is obtained by increasing the content ratio of the metal nanoparticles 18S having a relatively small particle size. Metal nanoparticles having a size of 50 nm or less are contained by 75 vol% or more of the total mass of the metal nanoparticles.
On the other hand, unlike the first embodiment of the present invention, the second bonding material 12C includes mixed particles of coarse metal particles 24 and metal nanoparticles 18S. The coarse metal particles 24 are coarse particles (particles larger than nanoparticles) made of a conductive metal such as silver or copper, and the size of the particles and the content ratio in the second bonding material 12C are not included in the bonding portion. It is determined in consideration of required conductivity and cost. For example, the particle size of the coarse metal particles 24 is appropriately about 1 to 10 μm (microns) in consideration of the unevenness absorbability of the surface of the bonded member 10. The coarse metal particles 24 need not be covered with an organic protective film in order to prevent the particles from adhering to each other, unlike the metal nanoparticles 18S. In general, the larger the size of the coarse metal particles 24 and the higher the content ratio, the lower the cost and the higher the conductivity. As for the metal nanoparticles contained in the second bonding material 12C, the content of the metal nanoparticles 18L having a relatively large particle size as well as the metal nanoparticles 18S having a relatively small particle size may be increased as necessary. good.

  Further, as a procedure of the joining operation, the second joining material 12C is obtained by evaporating the solvent 20 from the first joining material 12A applied to the surface of one of the members to be joined 10 (10A). It is applied over the material 12A. Similarly, when the first bonding material 12A is applied again on the second bonding material 12C, the first bonding material 12A is evaporated after the solvent 20 is evaporated from the second bonding material 12C. Is applied. Furthermore, after evaporating the solvent 20 from the first bonding material 12A applied over the second bonding material 12C or applied to the surface of the other bonded member 10 (10B), the bonded material is bonded. The members 10A and 10B are overlapped. And while joining material 12 (12A, 12B) is heated so that it may become the joining temperature or more, to-be-joined members are pressurized, the binder 20 decomposes | disassembles and evaporates, and finally FIG. 2 ( As shown in b), the member to be joined 10, the metal nanoparticles 18S, and the coarse metal particles 24 are joined in close contact with each other.

  Also in the second embodiment of the present invention, the members to be bonded 10A and 10B are overlapped with each other and the members to be bonded are heated while being heated so that the bonding material 12 (12A, 12B) is equal to or higher than the bonding temperature. The pressurizing process is the same as the conventional (iii) assembly process, (iv) heating / pressurizing process, and (v) joining process (joining completion process) shown in FIG. Is omitted.

  Moreover, the joining structure of the to-be-joined members using the metal nanoparticle based on the 3rd Embodiment of this invention is the surface of one to-be-joined member 10 (10A), as FIG. 3 (a) shows. In addition, the first bonding material 12A is applied, the second bonding material 12D is overlaid on the surface of the first bonding material 12A, and the first bonding material 12A is further stacked on the second bonding material 12D. Or it is apply | coated to the surface of the other to-be-joined member 10 (10B), and the to-be-joined members 10A and 10B are piled up.

Here, as in the first and second embodiments of the present invention, the first bonding material 12A is obtained by increasing the content ratio of the metal nanoparticles 18S having a relatively small particle size. Contains 75 vol% or more of metal nanoparticles having a particle size of 50 nm or less of the total mass of the metal nanoparticles.
On the other hand, the second bonding material 12D is a metal foil 26, and specifically, a silver foil or a copper foil is used. The thickness of the metal foil 26 is determined in consideration of required conductivity, unevenness followability, handling property of the single piece, cost, and the like, and about 10 to 50 μm is appropriate.

  Further, as a procedure of the joining operation, the second joining material 12D is obtained by evaporating the solvent 20 from the first joining material 12A applied to the surface of one of the members to be joined 10 (10A). Overlaid on material 12A. Furthermore, after evaporating the solvent 20 from the first bonding material 12A applied over the second bonding material 12C or applied to the surface of the other bonded member 10 (10B), the bonded material is bonded. The members 10A and 10B are overlapped. And while joining material 12 (12A, 12B) is heated so that it may become the joining temperature or more, to-be-joined members are pressurized, the binder 20 decomposes | disassembles and evaporates, and finally FIG. 2 ( As shown in b), the member to be joined 10, the metal nanoparticles 18S, and the metal foil 26 are joined in close contact with each other.

  Note that FIG. 4 illustrates a process in which the members to be bonded are pressed while being superposed on each other and heated so that the bonding material 12 (12A, 12B) is equal to or higher than the bonding temperature. Since it is the same as the conventional (iii) assembly process, (iv) heating / pressurization process, and (v) joining process (joining completion process), detailed description is omitted.

The effects obtained by the embodiment of the present invention having the above-described configuration are as follows.
First, in any of the first to third embodiments of the present invention, the first bonding material 12A in which the content ratio of the metal nanoparticles 18S having a relatively small particle size is increased on the surface of the member to be bonded 10. As a result, the bondability between the member to be bonded 10 and the metal nanoparticles 18S is enhanced. On the other hand, the relatively small metal nanoparticles 18 </ b> S contained in the first bonding material 12 </ b> A are smaller in size than the unevenness on the surface of the member to be bonded 10, so that the members to be bonded are formed by the metal nanoparticles 18 </ b> S. However, the unevenness is absorbed by the second bonding material 12B (FIG. 1), 12C (FIG. 2), and 12D (FIG. 3) having excellent unevenness absorbability instead. can do. Therefore, the application thickness of the first bonding material 12A is reduced (specifically, about 5 μm), and sufficient bonding is achieved while avoiding an excessive increase in the decomposition gas of the organic protective film generated from the entire bonding material 12. Property and conductivity can be secured.

In the first embodiment of the present invention, the second bonding material 12B contains 50 vol% or more of metal nanoparticles having a size of 100 nm or more as the metal nanoparticles 18L having a relatively large particle size. The unevenness on the surface of 10 can be sufficiently absorbed by the metal nanoparticles of 100 nm or more, and necessary bonding properties and conductivity can be ensured. Moreover, since the content ratio of the metal nanoparticles 18S having a relatively small particle size in the entire bonding material 12 is reduced, the cost of the bonding material 12 is reduced.
In addition, since the bondability between the metal nanoparticles 18S and 18L is good regardless of the particle size, the two members to be bonded 10A and 10B are in the bonded state shown in FIG. In addition, it is in a state of being securely joined while preventing an increase in resistance value.

  Further, in the second embodiment of the present invention, the second bonding material 12C includes mixed particles of the coarse metal particles 24 and the metal nanoparticles 18S, so that the unevenness on the surface of the member to be joined 10 is coarse. It is sufficiently absorbed by the metal particles 24 and the metal nanoparticles 18S to ensure the necessary bondability and conductivity. In addition, since the low-cost coarse metal particles 24 are included, the content ratio of the metal nanoparticles 18S having a relatively small particle size in the entire bonding material 12 is reduced, so that the cost of the bonding material 12 can be further reduced. It is done. Note that the bonding properties of the coarse metal particles and the metal nanoparticles are good regardless of the particle size, and due to the effect of reducing the resistance value by the coarse metal particles 24, the bonding completion state shown in FIG. The two members to be joined 10A and 10B are in a state of being securely joined while further reducing the resistance value.

  Further, in the third embodiment of the present invention, since the second bonding material 12D is the metal foil 26, the unevenness on the surface of the member to be bonded 10 is sufficiently absorbed by the metal foil 26 and necessary bonding is performed. It ensures the property and conductivity. Further, since the bonding material 12 includes the metal foil 26 having a lower cost than the bonding material 12A including the metal nanoparticles 18S, the cost of the entire bonding material 12 can be further reduced. Note that the bonding property between the metal foil 26 and the metal nanoparticles 18S is good, and the bonding property shown in FIG. 3B is due to the effect of reducing the resistance value due to the stable and high conductivity of the metal foil 26. In the completed state, the two bonded members 10A and 10B are in a state of being securely bonded while further reducing the resistance value.

BRIEF DESCRIPTION OF THE DRAWINGS The junction structure which joins to-be-joined members using the metal nanoparticle based on the 1st Embodiment of this invention is shown typically, (a) is sectional drawing which shows the state before pressurization and baking. (B) is sectional drawing which shows a joining completion state. The sectional view which shows typically the joined structure which joins to-be-joined members using metal nanoparticles concerning the 2nd embodiment of the present invention, and (a) shows the state before pressurization and baking. (B) is sectional drawing which shows a joining completion state. The sectional view which shows typically the joined structure which joins to-be-joined members using metal nanoparticles concerning the 3rd embodiment of the present invention, and (a) shows the state before pressurization and baking. (B) is sectional drawing which shows a joining completion state. It is a schematic diagram which shows the procedure which joins to-be-joined members using the conventional metal nanoparticle. The fracture surface obtained by peeling the members joined using metal nanoparticles is schematically shown. (A) shows the normal fracture surface when an appropriate pressure is applied, (b) Indicates a defective fracture surface when excessive pressure is applied.

Explanation of symbols

  10, 10A, 10B: Member to be joined, 12: Joining material, 12A: First joining material, 12B, 12C, 12D: Second joining material, 16: Organic protective film, 18: Metal nanoparticles, 18S: Particles Metal nanoparticles with relatively small size, 18L: Metal nanoparticles with relatively large particle size, 20: Binder, 22: Solvent, 24: Coarse metal particles, 26: Metal foil

Claims (8)

This is a joining method for joining members to be joined by heating and firing a joining material containing metal nanoparticles coated with an organic protective film in a state where the joining material is held at a predetermined position between two members to be joined. And
The surface of one member to be bonded is coated with a first bonding material with a high content ratio of metal nanoparticles having a relatively small particle size, and the surface of the member to be bonded has excellent irregularity absorbability. Layer the second bonding material
Furthermore, the first bonding material is applied to the surface of the other member to be bonded or overlaid on the second bonding material,
A joining method, wherein the members to be joined are overlapped and the members to be joined are pressurized while being heated so that the joining material has a temperature equal to or higher than the joining temperature. The first bonding material is a bonding material containing 75 vol% or more of metal nanoparticles having a particle size of 50 nm or less, and the second bonding material is a bonding material containing 50 vol% or more of metal nanoparticles of 100 nm or more. The bonding method according to claim 1. The first bonding material is a bonding material containing 75 vol% or more of metal nanoparticles having a particle size of 50 nm or less, and the second bonding material is a bonding material containing mixed particles of coarse metal particles and metal nanoparticles. The bonding method according to claim 1, wherein the bonding method is provided. 2. The bonding method according to claim 1, wherein the first bonding material is a bonding material containing 75 vol% or more of metal nanoparticles having a particle size of 50 nm or less, and the second bonding material is a metal foil. . Joining materials containing metal nanoparticles covered with an organic protective film are heated and baked in a state where they are held at a predetermined position between two joined members, so that the joined members are joined together. A joining structure comprising
A first bonding material having a higher content ratio of metal nanoparticles having a relatively small particle size is applied to the surface of one of the members to be bonded, and the first bonding material has excellent unevenness absorbability on the surface of the member to be bonded. The second bonding material is overlaid,
Further, the first bonding material is superimposed on the second bonding material or applied to the surface of the other member to be bonded,
A joining structure in which the members to be joined are superposed and the members to be joined are pressurized while being heated so that the joining material has a temperature equal to or higher than the joining temperature. The first bonding material is a bonding material containing 75 vol% or more of metal nanoparticles having a particle size of 50 nm or less, and the second bonding material is a bonding material containing 50 vol% or more of metal nanoparticles of 100 nm or more. The joint structure according to claim 5. The first bonding material is a bonding material containing 75 vol% or more of metal nanoparticles having a particle size of 50 nm or less, and the second bonding material is a bonding material containing mixed particles of coarse metal particles and metal nanoparticles. The bonding structure according to claim 5, wherein the bonding structure is provided. The bonding structure according to claim 5, wherein the first bonding material is a bonding material containing 75 vol% or more of metal nanoparticles having a particle size of 50 nm or less, and the second bonding material is a metal foil. .