JP2022083853A - Joint material and mounting structure using the same - Google Patents

Abstract

To provide a joint material capable of exhibiting higher joint strength.SOLUTION: A joint material is a joint material containing first metallic particles having a melting point of 200°C or lower, second metallic particles containing a first metallic element contained in the first metallic particles and a second metallic element that enables production of an intermetallic compound, TiO2 nanoparticles, and a flux. The first metallic particles is any one of only a first metallic element that enables production of a second metallic element and an intermetallic compound, or a composite of the first metallic element that enables production of the second metallic element and the intermetallic compound, and a third metallic element that disables production of the second metallic element and the intermetallic compound and has a melting point of a single metallic element of 250°C or higher. A ratio of the first metallic particles to the second metallic particles is a ratio in which all of the first metallic element contained int he first metallic particles and the second metallic element contained in the second metallic particles are intermetallic compounds in an equilibrium diagram of the first metallic element and the second metallic element.SELECTED DRAWING: Figure 1

Description

The present invention relates to a joining material for joining two members with a metal material and a mounting structure joined using the joining material, which are used in devices such as power devices.

In devices that generate heat, such as power devices, mounting is performed by joining two members, the board and the heat dissipation part, for heat transfer from the board on which the element is mounted to the heat dissipation part for the purpose of dissipating the generated heat. Some have a structure.

In recent years, there has been an increasing demand for large current control for the purpose of energy saving in devices such as power devices. Therefore, next-generation power device devices such as SiC and GaN, which have the advantage of being able to control power with high efficiency, are increasing in place of conventional Si devices.

These next-generation power device devices have the advantage of being able to operate even at high temperatures, and can withstand a larger amount of heat generation than conventional Si devices. Rising and high temperature occur.

As a result, the junction temperature Tj between the electrode such as the lead frame through which the current controlled by the element flows and the element electrode rises. For example, what was about 125 ° C for conventional Si, but rises to 200 to 250 ° C for SiC and GaN.

Therefore, the joint portion between the element electrode and the lead frame electrode is required to have thermal conductivity for efficiently dissipating the generated heat to the lead frame and heat resistance corresponding to the high temperature Tj of the joint portion.

Further, SiC and GaN used in next-generation power device elements have a high elastic modulus and high strength as compared with Si. For example, the elastic modulus of Si is 160 GPa, while that of SiC and GaN is 200 GPa or more. Therefore, the thermal stress at the time of temperature change due to the difference in the coefficient of linear expansion of the two members becomes large. Therefore, it is also required to increase the joint strength of the joint portion.

Conventionally, a solder material has been widely used as a joining material used for a joining portion of a mounting structure for joining an element and a lead frame electrode with a conductor because it can be joined at a low temperature. However, for a commonly used solder material containing Sn or Pb as a main component, 200 ° C. to 250 ° C. is a temperature near or higher than the melting point, which is a very harsh temperature. Therefore, a mounting structure using these solders is used. It is difficult for the body to ensure heat resistance.

One solution to such a problem is a bonding material in which a low melting point metal and a second metal forming an intermetal compound are mixed, and the low melting point metal is melted at the time of joining to form a second metal. A liquid-phase sintering method bonding material has been proposed in which a metal-to-metal compound is formed by reacting to form a high-melting point bonding portion.

As a bonding material of the conventional high heat resistance liquid phase sintering method, it is a bonding material containing at least two or more kinds of metal particles containing Cu and a polymer having a polydimethylsiloxane skeleton, and the metal particles are intermetal compounds. (See, for example, Patent Document 1).

WO2016 / 031551A Gazette

However, in the bonding material described in Patent Document 1, the low melting point metal melts and reacts with Cu to form a high melting point intermetallic compound, so that it exhibits high heat resistance, but the crystal grains of the intermetallic compound are coarse. It is difficult to improve the bonding strength.

An object of the present invention is to solve a conventional problem and to provide a bonding material capable of exhibiting a higher bonding strength.

In order to achieve the above object, the bonding material according to the present invention produces a first metal particle having a melting point of 200 ° C. or lower, and a first metal element and an intermetal compound contained in the first metal particle. It contains a second metal particle containing a second metal element capable of forming, TiO ₂ nanoparticles, and a flux.
The first metal particles are only the first metal element that produces the second metal element and the metal-to-metal compound, or the first metal element that produces the second metal element and the metal-to-metal compound, and the second. It is one of a composite containing a metal element and a third metal element having a melting point of the metal element alone having a melting point of 250 ° C. or higher without forming an intermetal compound.
The ratio of the first metal particle to the second metal particle is the first metal element contained in the first metal particle and the second metal element in the equilibrium state diagram between the first metal element and the second metal element. The ratio is such that the second metal element contained in the metal particles is a compound between metals.

According to the bonding material according to the present invention, it is possible to provide a bonding material capable of suppressing grain coarsening at the time of forming an intermetallic compound in a liquid phase sintering method and forming a bonding portion having a higher bonding strength. be.

It is a schematic diagram which shows the structure of the bonding material which concerns on Embodiment 1. Table 1 shows the components contained in the joining materials in Examples 1-1 to 1-8 and Comparative Examples 1-1 to 1-12, their weight ratios, and the evaluation results. Table 2 shows the components contained in the joining materials in Examples 2-1 to 2-6 and Comparative Examples 2-1 to 2-4, their weight ratios, and the evaluation results. Table 3 shows the components contained in the joining materials in Examples 3-1 to 3-11, their weight ratios, and the evaluation results.

The bonding material according to the first aspect is a second metal capable of producing a first metal particle having a melting point of 200 ° C. or lower, a first metal element contained in the first metal particle, and an intermetal compound. It contains a second metal particle containing an element, TiO ₂ nanoparticles, and a flux.
The first metal particles are only the first metal element that produces the second metal element and the metal-to-metal compound, or the first metal element that produces the second metal element and the metal-to-metal compound, and the second. It is one of a composite containing a metal element and a third metal element having a melting point of the metal element alone having a melting point of 250 ° C. or higher without forming an intermetal compound.
The ratio of the first metal particle to the second metal particle is the first metal element contained in the first metal particle and the second metal element in the equilibrium state diagram between the first metal element and the second metal element. The ratio is such that the second metal element contained in the metal particles of No. 1 is an intermetal compound.

The joining material according to the second aspect. In the first aspect described above, the TiO ₂ nanoparticles may have a median diameter of 20 to 80 nm.

The joining material according to the third aspect. In the first or second aspect, the content of the TiO ₂ nanoparticles is 0.1 wt% to 1 wt% of the total of the first metal particles, the second metal particles, and the TiO ₂ nanoparticles. You may.

The joining material according to the fourth aspect. In any one of the first to third aspects, the first metal particle is at least one selected from the group of Sn-Bi, Sn-In, Sn-Bi-In, Bi-In, and In. There may be.

The joining material according to the fifth aspect. In any one of the first to fourth aspects, the second metal particle may contain Cu.

The joining material according to the sixth aspect. In any of the first to fifth aspects, the first metal particles may include at least particles having a median diameter of 3 to 30 μm.

The joining material according to the seventh aspect. In any of the first to sixth aspects, the second metal particles may have a median diameter of 100 to 2000 nm.

The mounting structure according to the eighth aspect includes a bonding material according to any one of the first to seventh aspects, which joins a SiC or GaN power device element and an electrode and an external electrode of the power device element. To prepare for.

Hereinafter, the joining material and the mounting structure according to the embodiment will be described in detail with reference to the accompanying drawings.

(Embodiment 1)
<Joining material>
FIG. 1 is a schematic view showing the structure of the joining material according to the first embodiment.
The bonding material 101 according to the first embodiment can generate a first metal particle 102 having a melting point of 200 ° C. or lower, and a first metal element and an intermetal compound contained in the first metal particle 102. It contains a second metal particle 103 containing a second metal element, a TiO ₂ nanoparticle 104, and a flux 105.
By including the TiO ₂ nanoparticles, the second metal element of the second metal particle diffuses into the first metal particle 102, and when the metal-metal compound is formed, the formation of primary crystal nuclei is promoted. Conceivable. Further, it is considered that solid TiO ₂ inhibits the growth of the generated crystal nuclei as they grow. Thereby, the crystal grains of the intermetallic compound can be refined.

The first metal particles are only the first metal element that produces the second metal element and the metal-to-metal compound, or the first metal element that produces the second metal element and the metal-to-metal compound, and the second. It is one of a composite containing a metal element and a third metal element having a melting point of the metal element alone having a melting point of 250 ° C. or higher without forming an intermetal compound.

The ratio of the first metal particle to the second metal particle is the first metal element contained in the first metal particle and the second metal element in the equilibrium state diagram between the first metal element and the second metal element. The ratio is such that the second metal element contained in the metal particles of No. 1 is an intermetal compound.
As a result, the joint portion produced in the process of the liquid phase sintering method using this bonding material does not remelt at 250 ° C. or lower. Therefore, it is possible to exhibit high heat resistance that does not melt even when the operating temperature of the device after joining is 200 ° C. or higher.

Hereinafter, each member constituting this joining material will be described.

<First metal particle>
The first metal particles 102 become liquid phase components in the process of the liquid phase sintering method and contain a first metal element for reacting with the second metal particles 103 to form a high melting point intermetallic compound.
The first metal particles 102 are composed of an alloy having a melting point of 200 ° C. or lower or a single metal. This enables liquid phase sintering at a low temperature of 200 ° C. or lower.
The alloy or elemental metal constituting the first metal particle 102 may be an alloy having a melting point of 200 ° C. or lower or a single metal, and in particular, Sn-Bi, Sn-In, Sn-Bi-In, Bi. -In, and preferably one selected from the group of In.

The first metal element is, for example, Sn or In. The first metal element is not limited to one type, and may contain both Sn and In. The first metal element forms an intermetallic compound with the second metal element contained in the second metal particles 103.

<Second metal particle>
The second metal particle 103 contains a first metal element contained in the first metal particle 102 and a second metal element capable of producing an intermetallic compound. As a result, it is possible to dissolve in the first metal particles in a molten state and generate an intermetallic compound having a high melting point with the first metal element contained in the first metal particles 102.
The second metal particle 103 may contain the first metal element contained in the first metal particle 102 and the second metal element capable of producing at least one or more intermetallic compounds.
The second metal element is, for example, Cu. The second metal element is not limited to Cu, but it is desirable that it contains Cu.

Further, the first metal particles 102 include only the first metal element that produces the second metal element and the metal-to-metal compound, or the first metal element that produces the second metal element and the metal-to-metal compound. It is one of a composite containing a second metal element and a third metal element that does not generate an intermetal compound and has a melting point of the metal element alone of 250 ° C. or higher.
The third metal element is, for example, Bi. The third metal element is not limited to Bi.

Further, the ratio of the first metal particle 102 to the second metal particle 103 is the first metal element contained in the first metal particle in the equilibrium state diagram between the first metal element and the second metal element. And the ratio of the second metal element contained in the second metal particle to be an intermetal compound. As a result, the joint portion produced in the process of the liquid phase sintering method does not remelt at 250 ° C. or lower. Therefore, it is possible to exhibit high heat resistance that does not melt even when the operating temperature of the device after joining is 200 ° C. or higher.

<TiO ₂ nanoparticles>
The TiO ₂ nanoparticles 104 exist as a solid at the interface between the first metal particles 102 and the second metal particles 103 when an intermetallic compound is formed. It is considered that this causes the second metal element of the second metal particle to diffuse into the first metal particle 102 and promotes the formation of primary crystal nuclei when the intermetallic compound is formed. Further, it is considered that solid TiO ₂ inhibits the growth of the generated crystal nuclei as they grow. These are included to refine the crystal grains of the intermetallic compound.
The TiO ₂ nanoparticles 104 are preferably 0.1 wt% to 1 wt% of the total of the first metal particles 102, the second metal particles 103, and the TiO ₂ nanoparticles 104.

<Flux>
The flux 105 is included for removing the oxide film existing on the surfaces of the first metal particles 102 and the second metal particles 103 and for suppressing reoxidation. The flux 105 facilitates the melting of the first metal particles 102 and the diffusion of the second metal element on the surface of the second metal particles 103 into the melted first metal particles 102. The flux 105 is a component for removing the oxide film existing on the surfaces of the first metal particles 102 and the second metal particles 103, and the first metal particles for preventing reoxidation during the process of the liquid phase sintering method. Contains a solvent having a boiling point higher than the melting point of 102.

(Example)
In order to confirm the effect of the first embodiment, the types of the first metal particles 102 and the second metal particles 103 are used as Examples 1-1 to 1-8 and Comparative Examples 1-1 to 1-12. The modified bonding material 101 is produced. The components contained in the bonding material 101 in Examples 1-1 to 1-8 and Comparative Examples 1-1 to 1-12, their weight ratios, and the evaluation results are shown in Table 1 of FIG. The particle sizes of the first metal particles 102, the second metal particles 103, and the TiO ₂ nanoparticles 104 shown in Table 1 of FIG. 2 are all median diameters.

<Joining material 101>
As the first metal particles 102 in the first embodiment, Sn-58Bi, Sn-51In, Sn-55Bi-20In, In, Sn, Sn-3.5Ag, and Sn-5Sb are evaluated. Further, Cu, Cu-20Sn, and Zn are evaluated as the second metal particles. TiO ₂ nanoparticles of 30 nm are used.

The joining material 101 is produced as follows.
(1) First, the first metal particles 102, the second metal particles 103, and the TiO ₂ nanoparticles are weighed, mechanically kneaded, and uniformly mixed.
(2) After that, the flux is weighed and added, and the flux is kneaded with a twin-screw planetary kneader to obtain the joining material 101.

<Joining process>
A mounting structure is produced in order to confirm the effect of the first embodiment. The joining process is as follows.
First, joining is performed using the prepared joining material 101.
(A) The bonding material 101 is supplied on the Cu plate using a metal mask having a thickness of 100 μm and an opening of 1 mm × 1 mm.
(B) A SiC element is mounted on the supplied joining material 101. The electrodes of the SiC element to be joined with the joining material 101 are composed of Ti / Ni / An plating from the SiC side.
(C) A 1 MPa load is applied from above the mounted SiC element, and heating is performed at 200 ° C. for 10 minutes in an _N2 atmosphere to prepare a mounting structure in which the SiC element electrode and the Cu plate are bonded with the bonding material 101. ..

<Joining evaluation>
The results of the evaluation for confirming the effect of the first embodiment are also shown in Table 1 of FIG.
After performing this series of joining processes, it is confirmed whether the Cu plate and the electrodes of the SiC element are joined. In Table 1 of FIG. 2, when it is joined, it is judged as ◯, and when it is not joined, it is judged as x.

Next, the heat resistance of the bonded mounting structure is evaluated. The produced mounting structure is heated to 200 ° C. again, and it is evaluated whether or not the joining material 101 is remelted. The case where remelting does not occur and the bonding is secured is judged as ◯, and the case where remelting occurs is judged as ×.
Further, the joint strength of the joint structure in which remelting does not occur is evaluated. A force in the shear direction is applied to the SiC element of the produced bonded structure, and the fracture strength is measured. When it is larger than 20 MPa, which is the same as that of conventional solder, it is judged as ◯, when it is larger than 30 MPa, it is judged as ⊚, and when it is 20 MPa or less, it is judged as x.

As shown in Table 1 of FIG. 2, among Examples 1-1 to 1-8, in Examples 1-1 to 1-6, bonding, heat resistance is ◯, strength is ⊚, and Examples 1-7, 1 In -8, the bonding, heat resistance, and strength are ○, both of which exceed the evaluation criteria. In these examples, the second metal particle 103 contains Cu in Cu or Cu-20Sn, and the first metal particle 102 is in Sn-58Bi, Sn-51In, Sn-55Bi-20In, or In. Also reacts with one or more metal elements to form an intermetallic compound. The third metal element (here, Bi) that does not form an intermetallic compound has a melting point of 271 ° C.

Further, the ratio of the first metal particle 102 to the second metal particle 103 is 40:60, and in any of the embodiments, the first metal element and the second metal element of the first metal particle 102 are used. The ratio is such that Cu, which is a metal element, has a content of all metal-to-metal compounds in the equilibrium diagram.

On the other hand, in Comparative Examples 1-10, 1-11, and 1-12, no bonding was formed even after performing a series of bonding processes. This is because the compositions of the first metal particles 102 used in Comparative Examples 1-10, 1-11, and 1-12 are Sn, Sn-3.5Ag, and Sn-5Sb, respectively, and their melting points are 232 ° C., respectively. It is considered that this is because the temperature is 221 ° C, 235 ° C, which is higher than the heating temperature of 200 ° C. That is, in a series of joining processes, the first metal particles 102 do not melt and liquid phase sintering does not occur, so that sufficient joining cannot be ensured.

Further, in Comparative Example 1-9, remelting occurs in the heat resistance evaluation. It is considered that this is because In of the first metal particle 102 and Zn of the second metal particle 103 used in Comparative Example 1-9 do not form an intermetallic compound. It is considered that this is because liquid phase sintering does not proceed in the joining process, In and Zn remain, and In is remelted by reheating.

Similar to Comparative Example 1-9, Comparative Example 1-2, 1-4, 1-6, and 1-8 also undergo remelting in the heat resistance evaluation.
This is the first metal element in the first metal particle 102 (Sn in Comparative Example 1-2, Sn and In in Comparative Example 1-4 and Comparative Example 1-6, In in Comparative Example 1-8). It can be understood by focusing on the mixing ratio with Cu, which is the second metal element. That is, in Comparative Examples 1-2, 1-4, 1-6, and 1-8, the mixing ratio of the first metal particles 102 and the second metal particles 103 is 70:30. In this case, it is considered that the first metal element in the first metal particle 102 is present in excess of the ratio of the intermetallic compound with the second metal element in the equilibrium phase diagram.
Therefore, in the bonding material 101 after the bonding process, Sn remains in Comparative Example 1-2, Sn and In in Comparative Example 1-4 and Comparative Example 1-6, and In in Comparative Example 1-8, and these remain. Since the melting point is lower than 200 ° C, it is considered that remelting occurs at 200 ° C or lower.

Further, focusing on Comparative Examples 1-1, 1-3, 1-5, 1-7, the initial bonding and the heat resistance exceed the standard values, but the bonding strengths are 16.8, 13.4, and 14, respectively. It is not so large as 0.7 and 12.2 MPa, and the judgment is x.
Comparing Comparative Examples 1-1, 1-3, 1-5, 1-7 and Examples 1-1, 1-3, 1-5, 1-7, respectively, 30 nm TiO ₂ nanoparticles 104 were added. It can be seen that the bonding strength is more than doubled by doing so.

From the result of the first embodiment, the following is confirmed.
In order to exhibit the effects of the present disclosure, first, a first metal particle having a melting point of 200 ° C. or lower and a first metal element and an intermetallic compound contained in the first metal particle 102 can be produced. It is necessary to be a bonding material containing a second metal particle 103 containing 2 metal elements, a TiO ₂ nanoparticle 104, and a flux 105.

Further, the first metal particles 102 are composed of only the first metal element that produces the second metal element and the metal-to-metal compound, or the first metal element that produces the second metal element and the metal-to-metal compound. It is necessary to be one of a composite containing a second metal element and a third metal element having a melting point of 250 ° C. or higher without forming an intermetal compound.

Then, the ratio of the first metal particle 102 to the second metal particle 103 is the first metal element contained in the first metal particle in the equilibrium state diagram between the first metal element and the second metal element. And, it is necessary that the ratio of the second metal element contained in the second metal particle to be an intermetal compound.
In the joining material 101 satisfying these, it is possible to provide a joining material capable of forming a joining portion having a high joining strength.

(Embodiment 2)
As the second embodiment, the influence of the particle size and the content rate of the TiO ₂ nanoparticles 104 is evaluated. Table 2 of FIG. 3 shows the components contained in the bonding material 101 in Examples 2-1 to 2-6 and Comparative Examples 2-1 to 2-4 of the second embodiment, their weight ratios, and the evaluation results. show. The method for producing the bonding material 101, the bonding process, and the evaluation method are the same as those in the first embodiment.

Focusing on the particle size of the TiO ₂ nanoparticles 104 from Table 2 of FIG. 3, in Examples 2-1, 2-2, and 2-3 in which the particle sizes are 20, 50, and 80 nm, respectively, the bonding and heat resistance are high. ○, strength is ◎, and both exceed the evaluation criteria.

On the other hand, in Comparative Examples 2-1 and 2-2 in which the particle size of the TiO ₂ nanoparticles 104 is as large as 100 nm and 300 nm, the bonding strength is not as high as 17.1 MPa and 10 MPa, respectively, so the judgment is x.

This is because the TiO ₂ nanoparticles 104 have a large particle size, so that there are few starting points for nucleation during liquid phase sintering, and large foreign substances are mixed between the intermetallic compounds after bonding. Take shape.
Therefore, it is considered that the effect of containing the TiO ₂ nanoparticles 104 is reduced, the vicinity of the interface is structurally weakened, and the bonding strength is reduced.

Next, focusing on the content of the TiO ₂ nanoparticles 104, in Examples 2-4 to 2-6, the contents of the TiO ₂ nanoparticles are 0.1, 0.2, and 1.0 wt%, respectively. , Heat resistance is ○, and strength is ◎, both exceeding the evaluation criteria.

On the other hand, in Comparative Example 2-3 in which the content of the TiO ₂ nanoparticles 104 is as small as 0.05 wt%, the bonding strength is not as high as 18.1 MPa.
It is considered that this is because the effect of the addition is small because the content of the TiO ₂ nanoparticles 104 is small.

Further, the content of TiO ₂ nanoparticles 104 is 2.0 wt. In Comparative Example 2-4, which is as large as%, the bonding strength is as small as 14.3 MPa, and the determination is x. This is because the high content of the TiO ₂ nanoparticles 104 reduces the strength between the intermetallic compounds formed between the first metal particles 102 and the second metal particles 103. I think.

From the result of the second embodiment, the following is confirmed.
The particle size of the TiO ₂ nanoparticles 104 is preferably a median diameter of 20 to 80 nm.
The content of the TiO ₂ nanoparticles 104 is 0.1 to 1 wt. % Is preferable.
In the joining material 101 satisfying these, it is possible to provide a joining material capable of forming a joining portion having a high joining strength.

(Embodiment 3)
As the third embodiment, the influence of the particle sizes of the first metal particles 102, the second metal particles 103, and the TiO ₂ nanoparticles 104 is evaluated.

Table 3 of FIG. 4 shows the components contained in the bonding material 101 in Examples 3-1 to 3-11 of the third embodiment, their weight ratios, and the evaluation results. The method for producing the bonding material 101, the bonding process, and the evaluation method are the same as those in the first and second embodiments.

Focusing on the particle size of the first metal particles 102 from the results of Table 3 of FIG. 4, the particles of the first metal particles 102 are 3, 20, and 30 μm, respectively, in Examples 3-2 to 3-4. In the case, the judgment of bonding and heat resistance is ○, the judgment of strength is ◎, and in Examples 3-1 and 3-5 having particle sizes of 0.5 and 45 μm, the judgment of bonding, heat resistance and strength is ○. Is.

In the case of Example 3-1 in which the particle size of the first metal particles 102 is small, since the particle size is close to that of the second metal particles 103, there are many places in contact with the second metal particles 103. Therefore, the rate of liquid phase sintering is very high during heating in the joining process, and the formation of the intermetallic compound is completed before the electrodes of the two members to be joined are sufficiently wetted and spread, so that the strength is higher than that of other examples. Is thought to be smaller.
On the contrary, in the case of Example 3-5 in which the particle size of the first metal particles 102 is large, the particle size of the first metal particles 102 is much larger than that of the second metal particles 103, so that the bonding material 101 It is considered that the bonding strength is also relatively small as compared with other examples because the uniformity at the time of producing is reduced.

Focusing on the particle size of the second metal particles 103, in the cases of Examples 3-7 to 3-10 in which the particle sizes of the second metal particles 103 are 100, 400, 1200, and 2000 nm, respectively, the bonding and heat resistance The determination of is ◯, the determination of strength is ⊚, and in Examples 3-6 and 3-11 having 50 and 6000 nm, the determination of bonding, heat resistance and strength is ◯.
In Example 3-6 in which the particle size of the second metal particles 103 is small, the particle size of the second metal particles 103 is so small that the second metal is made during the production of the bonding material 101 or during the heating of the bonding process. It is considered that the bonding strength is relatively small as compared with other examples because the particles 103 are aggregated and the uniformity is lowered.
In Example 3-11 in which the particle size of the second metal particles 103 is large, the large particle size of the second metal particles 103 causes diffusion to the first metal particles 102 melted in the joining process. This is probably because the particle size of the intermetallic compound becomes large.

From the result of the third embodiment, the following is confirmed.
It is desirable that the first metal particle 102 contains at least particles having a median diameter of 3 to 30 μm.
The second metal particles 103 preferably have a median diameter of 100 to 2000 nm.
In the joining material 101 satisfying these, it is possible to provide a joining material capable of forming a joining portion having a high joining strength.

<Preferable conditions of the present invention>
As described above, from the results of the first to third embodiments, as suitable conditions for exhibiting the effect of the bonding material of the present disclosure, the bonding material includes the first metal particles 102 having a melting point of 200 ° C. or lower and the first metal particles 102. A junction containing a second metal particle 103 containing a first metal element contained in the metal particles 102 and a second metal element capable of producing an intermetal compound, a TIO ₂ nanoparticles 104, and a flux 105. Material 101.
Further, the first metal particles 102 include only the first metal element that produces the second metal element and the metal-to-metal compound, or the first metal element that produces the second metal element and the metal-to-metal compound. It is one of a composite containing a second metal element and a third metal element that does not generate an intermetal compound and has a melting point of the metal element alone of 250 ° C. or higher.
Further, the ratio of the first metal particle 102 to the second metal particle 103 is the ratio of the first metal contained in the first metal particle 102 in the equilibrium state diagram between the first metal element and the second metal element. The ratio is such that the element and the second metal element contained in the second metal particle 103 are all metal-to-metal compounds.

As more preferred conditions, the TiO ₂ nanoparticles 104 may have a median diameter of 20-80 nm.

As an even more preferable condition, the content of the TiO ₂ nanoparticles 104 is 0.1 wt% to 1 wt% of the total of the first metal particles 102, the second metal particles 103, and the TiO ₂ nanoparticles 104. There may be.

As an even more preferable condition, the first metal particle 102 may be at least one selected from the group of Sn-Bi, Sn-In, Sn-Bi-In, Bi-In, and In.

As an even more preferable condition, the second metal particle 103 may contain Cu.

As an even more preferable condition, the first metal particles 102 may contain at least particles having a median diameter of 3 to 30 μm.

As an even more preferable condition, the second metal particles 103 may have a median diameter of 100 to 2000 nm.

Further, the mounting structure includes a SiC or GaN power device element and the bonding material 101 for bonding an electrode of the power device element and an external electrode.

In the present embodiment, the electrode of the SiC element used for the evaluation is Ti / Ni / Au, but the present disclosure is not limited to this, and the electrode that can be bonded with the first metal particles 102 is used. If so, the effect of the present disclosure can be exhibited.

It should be noted that the present disclosure includes appropriately combining any of the various embodiments and / or embodiments described above, and the respective embodiments and / or embodiments. The effects of the examples can be achieved.

According to the bonding material according to the present invention, it is possible to realize a mounting structure having heat resistance and high strength required for a device that uses a device having a high elastic modulus such as SiC or GaN and that operates at a high temperature.

101 Bonding material 102 First metal particles 103 Second metal particles 104 TIO ₂ nanoparticles 105 Flux

Claims (8)

The first metal particles having a melting point of 200 ° C or less and
A second metal particle containing a first metal element contained in the first metal particle and a second metal element capable of producing an intermetallic compound, and a second metal particle.
With dio ₂ nanoparticles,
Flux and
Is a joining material containing
The first metal particle is
Only the first metal element that produces the second metal element and the intermetallic compound, or
The first metal element that produces the second metal element and the metal-to-metal compound, and the third metal element that does not generate the second metal element and the metal-to-metal compound and the metal element alone has a melting point of 250 ° C. or higher. Complexes containing metal elements,
Is one of
The ratio of the first metal particle to the second metal particle is the first metal particle contained in the first metal particle in the equilibrium state diagram between the first metal element and the second metal element. The ratio of the metal element and the second metal element contained in the second metal particle to be an intermetal compound.
Joining material. The bonding material according to claim 1, wherein the TiO ₂ nanoparticles have a median diameter of 20 to 80 nm. Claim 1 or 2 in which the content of the TiO ₂ nanoparticles is 0.1 wt% to 1 wt% of the total of the first metal particles, the second metal particles, and the TiO ₂ nanoparticles. The bonding material described in. One of claims 1 to 3, wherein the first metal particle is at least one selected from the group of Sn-Bi, Sn-In, Sn-Bi-In, Bi-In, and In. The joining material described in. The joining material according to any one of claims 1 to 4, wherein the second metal particles contain Cu. The joining material according to any one of claims 1 to 5, wherein the first metal particles contain at least particles having a median diameter of 3 to 30 μm. The joining material according to any one of claims 1 to 6, wherein the second metal particles have a median diameter of 100 to 2000 nm. With SiC or GaN power device devices
The joining material according to any one of claims 1 to 7, which joins the electrode of the power device element and the external electrode.
A mounting structure with.

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