KR20220072732A - Joining material and mounting structure using the same - Google Patents

Abstract

The bonding material includes a first metal particle having a melting point of 200° C. or less, a second metal particle including a first metal element contained in the first metal particle, and a second metal element capable of forming an intermetallic compound, TiO ₂ It is a bonding material containing nanoparticles and a flux. The first metal particles include only the first metal element that generates the second metal element and the intermetallic compound, or the first metal element that generates the second metal element and the intermetallic compound, and the second metal element and the intermetallic compound. It is any one of the composites containing a 3rd metal element which does not generate|occur|produce and the melting|fusing point of the metal element single-piece|unit is 250 degreeC or more. The ratio of the first metal particles to the second metal particles is the first metal element contained in the first metal particle and the second metal contained in the second metal particle in the equilibrium diagram of the first metal element and the second metal element. The ratio at which all elements become intermetallic compounds.

Description

A bonding material and a mounting structure using the same

TECHNICAL FIELD The present invention relates to a bonding material for bonding two members to be used in equipment such as a power device with a metallic material, and to a mounting structure joined using the bonding material.

In devices that generate heat, such as power devices, for the purpose of dissipating the generated heat, and for transferring heat from the substrate on which the element is mounted to the heat dissipation unit, it is desirable to have a mounting structure in which two members of the substrate and the heat dissipation unit are joined. have.

In recent years, in devices, such as a power device, the request|requirement of large current control for the purpose of energy saving is increasing. Therefore, next-generation power device elements such as SiC and GaN, which have the advantage of being able to control electric power with high efficiency, are increasing in place of the conventional Si elements.

These next-generation power device elements have the advantage of being able to operate at high temperatures, and can withstand greater heat generation than conventional Si elements.

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

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

In addition, SiC and GaN used for next-generation power device elements have a higher modulus of elasticity and higher strength than Si. For example, the elastic modulus of Si is 160 GPa, whereas SiC or GaN is 200 GPa or more. Therefore, the thermal stress at the time of a temperature change resulting from the linear expansion coefficient difference of two members becomes large. Then, it is also calculated|required to make the joint strength of a joint part higher.

Conventionally, a solder material has been widely used as a bonding material used for a bonding portion of a mounting structure for bonding between an element and a lead frame electrode with a conductor since bonding at a low temperature is possible. However, in the generally used solder material containing Sn or Pb as a main component, 200°C to 250°C is a temperature near or above the melting point, which is a very severe temperature. is difficult

As one solution to such a problem, as a bonding material in which a low-melting-point metal and a second metal forming an intermetallic compound are mixed therewith, the low-melting-point metal is melted at the time of bonding and reacted with the second metal A bonding material of a liquid phase sintering method in which a high-melting-point bonding portion is formed by forming an intermetallic compound has been proposed.

As a bonding material for a conventional high heat-resistant liquid phase sintering method, a bonding material containing at least two kinds of metal particles containing Cu and a polymer having a polydimethylsiloxane skeleton, wherein the metal particles can form an intermetallic compound There is a thing (for example, refer patent document 1.).

Publication WO2016/031551

The bonding material according to the present invention includes a first metal particle having a melting point of 200° C. or less, and a second metal particle including a first metal element included in the first metal particle and a second metal element capable of forming an intermetallic compound. and TiO ₂ nanoparticles, and a flux.

The first metal particles include only the first metal element that generates the second metal element and the intermetallic compound, or the first metal element that generates the second metal element and the intermetallic compound, and the second metal element and the intermetallic compound. It is any one of the composites containing the 3rd metal element which does not generate|occur|produce and the melting|fusing point of the metal element single-piece|unit is 250 degreeC or more.

The ratio of the first metal particles to the second metal particles is the first metal element included in the first metal particle and the second metal element included in the second metal particle in the equilibrium diagram of the first metal element and the second metal element. are all intermetallic compounds.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows the structure of the bonding material which concerns on this Embodiment 1. FIG.
2 is Table 1 showing the components contained in the bonding materials in Examples 1-1 to 1-8 and Comparative Examples 1-1 to 1-12, their weight ratios, and evaluation results.
3 is Table 2 showing the components contained in the bonding materials in Examples 2-1 to 2-6 and Comparative Examples 2-1 to 2-4, their weight ratios, and evaluation results.
4 is Table 3 showing the components contained in the bonding material in Examples 3-1 to 3-11, the weight ratio thereof, and the evaluation results.

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

The present invention solves the conventional problems, and an object of the present invention is to provide a bonding material capable of exhibiting higher bonding strength.

The bonding material according to the first aspect includes a first metal particle having a melting point of 200° C. or less, and a second metal including a first metal element included in the first metal particle and a second metal element capable of forming an intermetallic compound. It contains particles, TiO ₂ nanoparticles, and a flux.

The first metal particles include only the first metal element that generates the second metal element and the intermetallic compound, or the first metal element that generates the second metal element and the intermetallic compound, and the second metal element and the intermetallic compound. It is any one of the composites containing the 3rd metal element which does not generate|occur|produce and the melting|fusing point of the metal element single-piece|unit is 250 degreeC or more.

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 contained in the second metal particle in the equilibrium diagram of the first metal element and the second metal element. The ratio at which all elements become intermetallic compounds.

In the bonding material according to the second aspect, in the first aspect, the TiO ₂ nanoparticles may have a median diameter of 20 to 80 nm.

A bonding material according to a third aspect is provided. In the first or second aspect, the content of the TiO ₂ nanoparticles may be 0.1 wt% to 1 wt% in the total of the first metal particles, the second metal particles, and the TiO ₂ nanoparticles.

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

A bonding material according to a fifth aspect. The aspect in any one of said 1st - 4th WHEREIN: The 2nd metal particle may contain Cu.

A bonding material according to a sixth aspect. The aspect in any one of said 1st - 5th WHEREIN: 1st metal particle|grains may contain at least particle|grains with a median diameter of 3-30 micrometers.

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

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

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

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

(Embodiment 1)

<Joint material>

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows the structure of the bonding material which concerns on this Embodiment 1. As shown in FIG.

The bonding material 101 according to the first embodiment is capable of generating an intermetallic compound with the first metal particles 102 having a melting point of 200° C. or less, and the first metal element contained in the first metal particles 102 . A second metal particle 103 including a second metal element, TiO ₂ nanoparticles 104, and a flux 105 are included.

By including TiO ₂ nanoparticles, when the second metal element of the second metal particle diffuses into the first metal particle 102 and an intermetallic compound is generated, the generation of crystal nuclei of primary crystal is prevented. is thought to promote Moreover, when _the generated crystal nuclei grow, it is thought that solid TiO2 inhibits growth. Thereby, the crystal grains of an intermetallic compound can be refine|miniaturized.

The first metal particles include only the first metal element that generates the second metal element and the intermetallic compound, or the first metal element that generates the second metal element and the intermetallic compound, and the second metal element and the intermetallic compound. It is any one of the composites containing the 3rd metal element which does not generate|occur|produce and the melting|fusing point of the metal element single-piece|unit is 250 degreeC or more.

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 contained in the second metal particle in the equilibrium diagram of the first metal element and the second metal element. The ratio at which all elements become intermetallic compounds.

Thereby, re-melting does not occur in the joint part produced|generated by the process of the liquid phase sintering method using this joining material at 250 degrees C or less. Therefore, even if the operating temperature of the device after bonding becomes 200 degreeC or more, high heat resistance which does not melt can be expressed.

Below, each member which comprises this bonding material is demonstrated.

<First metal particle>

The first metal particles 102 are liquid phase components in the liquid phase sintering process, and contain a first metal element for reacting with the second metal particles 103 to produce an intermetallic compound having a high melting point.

The first metal particles 102 are made of an alloy having a melting point of 200° C. or less or a single-piece metal. This enables liquid phase sintering at a low temperature of 200°C or less.

The alloy or single metal constituting the first metal particle 102 may be an alloy or a single metal having a melting point of 200° C. or less, but in particular, Sn-Bi, Sn-In, Sn-Bi-In, Bi-In, and Any one selected from the group of In is preferable.

The first metal element is, for example, Sn or In. In addition, a 1st metal element is not limited to one type, You may also 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 Particles>

The second metal particle 103 includes a first metal element included in the first metal particle 102 and a second metal element capable of forming an intermetallic compound. Thereby, it can melt|dissolve in the 1st metal particle in a molten state, and can produce|generate the high melting|fusing point intermetallic compound with the 1st metal element contained in the 1st metal particle 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 forming at least one or more intermetallic compounds.

The second metal element is, for example, Cu. In addition, although a 2nd metal element is not limited to Cu, it is preferable that Cu is included.

In addition, the first metal particles 102 contain only the first metal element that generates the second metal element and the intermetallic compound, or the first metal element that generates the second metal element and the intermetallic compound, and the second metal element. and a third metal element that does not form an intermetallic compound and the melting point of the metal element alone is 250° C. or higher.

The third metal element is, for example, Bi. In addition, the 3rd metal element is not limited to Bi.

Furthermore, the ratio of the first metal particles 102 and the second metal particles 103 is the first metal element contained in the first metal particle in the equilibrium diagram of the first metal element and the second metal element, and the second metal element It is a ratio in which all the 2nd metal elements contained in a metal particle become an intermetallic compound. Thereby, re-melting does not occur in the joint part produced|generated by the process of the liquid phase sintering method at 250 degrees C or less. Therefore, even if the operating temperature of the device after bonding becomes 200 degreeC or more, high heat resistance which does not melt can be expressed.

<TiO ₂ nanoparticles>

When the TiO ₂ nanoparticles 104 form an intermetallic compound between the first metal particle 102 and the second metal particle 103 , the TiO 2 nanoparticles exist as a solid at the interface. As a result, it is thought that when the second metal element of the second metal particle diffuses into the first metal particle 102 and an intermetallic compound is generated, the production of primary crystal nuclei is promoted. Moreover, when _the generated crystal nuclei grow, it is thought that solid TiO2 inhibits growth. Thereby, it is included in order to refine|miniaturize the crystal grain of an intermetallic compound.

The TiO ₂ nanoparticles 104 are preferably 0.1 wt% to 1 wt% in 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 removal of the oxide film existing on the surface of the 1st metal particle 102 and the 2nd metal particle 103, and suppression of re-oxidation. The flux 105 facilitates the melting of the first metal particles 102 and diffusion of the second metal element on the surface of the second metal particles 103 into the molten first metal particles 102 . The flux 105 is a component that removes the oxide film present on the surface of the first metal particles 102 and the second metal particles 103, and the first metal particles ( 102) a solvent having a boiling point higher than the melting point.

(Example)

In order to confirm the effect of this Embodiment 1, as Examples 1-1 to 1-8 and Comparative Examples 1-1 to 1-12, the types of the first metal particles 102 and the second metal particles 103 were selected. The replaced 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, the weight ratio thereof, and the evaluation results are shown in Table 1 of FIG. 2 . The particle diameters of the 1st metal particle 102, the 2nd metal particle 103, and the TiO ₂ nanoparticle 104 shown in Table 1 of FIG. 2 are all median diameters.

<Joining material 101>

As the 1st metal particle 102 in this Embodiment 1, Sn-58Bi, Sn-51In, Sn-55Bi-20In, In, Sn, Sn-3.5Ag, and Sn-5Sb are evaluated. Further, as the second metal particles 103, Cu, Cu-20Sn, and Zn are evaluated. TiO ₂ Nanoparticles of 30 nm are used.

The bonding material 101 is produced as follows.

(1) First, the first metal particles 102 , the second metal particles 103 , and TiO ₂ nanoparticles are weighed and mechanically kneaded to uniformly mix.

(2) Thereafter, the bonding material 101 is obtained by weighing, adding, and kneading the flux using a twin-screw planetary kneader.

<Joining process>

In order to confirm the effect of this Embodiment 1, a mounting structure is produced. The bonding process is as follows.

First, bonding is performed using the produced bonding material 101 .

(a) A bonding material 101 is supplied on a 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 bonding material 101 . The electrode of the SiC element to be joined with the bonding material 101 is composed of Ti/Ni/An plating from the SiC side.

(c) A load of 1 MPa is applied from the top of the mounted SiC element, and heating is performed at 200° C. for 10 min in an N ₂ atmosphere to prepare a mounting structure in which an electrode of the SiC element and a Cu plate are joined with a bonding material 101 .

<Joint evaluation>

The result of evaluation for confirming the effect of this Embodiment 1 is also combined with Table 1 of FIG. 2, and is shown.

After performing this series of bonding processes, it is confirmed whether the Cu plate and the electrode of a SiC element are joined. In Table 1 of FIG. 2, when it is joined, it is indicated by Yes, and when it is not joined, it is indicated by No.

Next, the heat resistance of the joined mounting structure is evaluated. The produced mounting structure is heated to 200°C again to evaluate whether the bonding material 101 is re-melted. In Table 1 of FIG. 2, when bonding is secured without re-melting (that is, when the bonding material 101 has heat resistance), Yes, when re-melting occurs (ie, when the bonding material 101 has heat resistance). ) is marked as No.

Furthermore, for the bonded structure in which re-melting does not occur, the bonding strength is evaluated. A force in the shear direction is applied to the SiC element of the produced bonded structure, and the breaking strength is measured. A case larger than the conventional solder average of 20 MPa is determined as B (family registration), a case larger than 30 MPa is determined as A (more family registration), and a case of 20 MPa or less is determined as C (negative).

As shown in Table 1 of Fig. 2, among Examples 1-1 to 1-8, in Examples 1-1 to 1-6, bonding and heat resistance were Yes, and strength was A, and Examples 1-7 and 1-8. In this case, the bonding and heat resistance were Yes, and the strength was B, all exceeding the evaluation criteria. In these embodiments, the second metal particles 103 include Cu as Cu or Cu-20Sn, and the first metal particles 102 include Sn-58Bi, Sn-51In, Sn-55Bi-20In, and In. In either case, it reacts with one or more metal elements to form an intermetallic compound. The third metal element that does not form an intermetallic compound (here, Bi) has a melting point of 271°C.

Furthermore, the ratio of the first metal particles 102 to the second metal particles 103 is 40:60, and in any embodiment, Cu as the first metal element and the second metal element in the first metal particle 102 . A is a ratio which becomes the content rate which turns into an intermetallic compound all in an equilibrium state diagram.

On the other hand, in Comparative Examples 1-10, 1-11, and 1-12, even if a series of bonding processes were performed, bonding was not formed. As for this, the composition of the 1st metal particle 102 used in Comparative Examples 1-10, 1-11, and 1-12 is Sn, Sn-3.5Ag, Sn-5Sb, respectively, The melting|fusing point is 232 degreeC and 221 degreeC, respectively. , 235°C, which is considered to be higher than the heating temperature of 200°C. That is, in a series of bonding processes, since the 1st metal particle 102 does not melt and liquid phase sintering does not occur, it is thought that sufficient bonding is not ensured.

Further, in Comparative Examples 1-9, re-melting occurred in the heat resistance evaluation. This is considered to be because In of the 1st metal particle 102 used in Comparative Example 1-9, and Zn of the 2nd metal particle 103 do not form an intermetallic compound. It is thought that this is because liquid phase sintering does not proceed in the bonding process, In and Zn remain, and In is re-melted by reheating.

Similarly to Comparative Examples 1-2, 1-4, 1-6, and 1-8 and Comparative Example 1-9, remelting occurs in the heat resistance evaluation.

This is the first metal element in the first metal particles 102 (Sn in Comparative Example 1-2, Sn and In in Comparative Examples 1-4 and 1-6, and In in Comparative Example 1-8) , it can be understood that attention is paid to the mixing ratio of 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 thought that it is because the 1st metal element in the 1st metal particle 102 exists in excess than the ratio which becomes an intermetallic compound with a 2nd metal element all in an equilibrium state diagram.

Therefore, in the bonding material 101 after the bonding process, Sn in Comparative Example 1-2, Sn and In in Comparative Examples 1-4 and Comparative Examples 1-6, and In in Comparative Example 1-8 remain, , since their melting point is lower than 200°C, it is considered that re-melting occurs at 200°C or less.

Furthermore, paying attention to Comparative Examples 1-1, 1-3, 1-5, and 1-7, although the initial bonding and heat resistance exceed the standard values, the bonding strength is not so great as 16.8, 13.4, 14.7, and 12.2 MPa, respectively, The verdict is C.

Comparative Examples 1-1, 1-3, 1-5, 1-7 and Examples 1-1, 1-3, 1-5, and 1-7 are compared respectively, 30nm TiO ₂ nanoparticles (104) It can be seen that the bonding strength is doubled or more by adding .

From the result of this Embodiment 1, the following is confirmed.

In order to express the effects of the present disclosure, first, a first metal particle having a melting point of 200° C. or less, and a first metal element included in the first metal particle 102 and a second metal element capable of generating an intermetallic compound It is necessary to be a bonding material including the second metal particles 103 including the TiO ₂ nanoparticles 104 and the flux 105 .

Furthermore, the first metal particles 102 contain only the first metal element that forms the intermetallic compound with the second metal element, or the first metal element that forms the second metal element and the intermetallic compound, and the second metal element It is necessary to be any one of a complex containing a third metal element with a melting point of 250° C. or higher without generating an intermetallic compound.

And the ratio of the 1st metal particle 102 and the 2nd metal particle 103 is the 1st metal element contained in the 1st metal particle in the equilibrium diagram of a 1st metal element and a 2nd metal element, and the 2nd It is necessary that all the 2nd metal elements contained in a metal particle are a ratio used as an intermetallic compound.

In the bonding material 101 satisfying these requirements, it is possible to provide a bonding material capable of forming a bonding portion having high bonding strength.

(Embodiment 2)

As this Embodiment 2, the influence of the particle size and content rate of the TiO ₂ nanoparticles 104 is evaluated. The components contained in the bonding material 101 in Examples 2-1 to 2-6 of this Embodiment 2 and Comparative Examples 2-1 to 2-4, the weight ratio thereof, and the evaluation result are shown in the table of FIG. 3 . 2 is shown. The manufacturing method of the bonding material 101, the bonding process, and the evaluation method are the same as that of Embodiment 1.

From Table 2 of FIG. 3, when paying attention to the particle size of the TiO ₂ nanoparticles 104, in Examples 2-1, 2-2, and 2-3 having a particle size of 20, 50, and 80 nm, respectively, bonding and heat resistance are Yes, The intensity|strength is A, and all are exceeding evaluation criteria.

On the other hand, in Comparative Examples 2-1 and 2-2 where the TiO ₂ nanoparticles 104 have large particle diameters of 100 nm and 300 nm, the bonding strength is not as high as 17.1 MPa and less than 10 MPa, respectively, so the determination is C.

In this case, since the particle size of the TiO ₂ nanoparticles 104 is large, the locations serving as the starting point of nucleation during liquid phase sintering are reduced, and after bonding, large foreign substances are mixed between the intermetallic compounds.

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, paying attention to the content of TiO ₂ nanoparticles 104, in Examples 2-4 to 2-6 in which the content of TiO ₂ nanoparticles is 0.1, 0.2, and 1.0 wt%, respectively, bonding and heat resistance are Yes, and strength is is A, all exceeding the evaluation criteria.

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

This is considered to be because the effect of addition is small because the content rate of the TiO ₂ nanoparticles 104 is small.

Further, in Comparative Example 2-4 in which the content of the TiO ₂ nanoparticles 104 is 2.0 wt.% and large, the bonding strength is as small as 14.3 MPa, and the determination is x. This is considered to be because the strength between the intermetallic compound formed between the first metal particle 102 and the second metal particle 103 is lowered because the content of the TiO ₂ nanoparticles 104 is high.

From the result of this Embodiment 2, the following is confirmed.

The particle size of the TiO ₂ nanoparticles 104 is preferably 20 to 80 nm in median diameter.

In addition, the content of the TiO ₂ nanoparticles 104 is preferably 0.1 to 1 wt.%.

In the bonding material 101 satisfying these requirements, it is possible to provide a bonding material capable of forming a bonding portion having high bonding strength.

(Embodiment 3)

In this Embodiment 3, the influence of the particle diameter of the 1st metal particle 102, the 2nd metal particle 103, and the TiO ₂ nanoparticle 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, the weight ratio thereof, and the evaluation results. The manufacturing method of the bonding material 101, a bonding process, and an evaluation method are the same as that of Embodiment 1 and Embodiment 2.

From the results of Table 3 in FIG. 4 , paying attention to the particle diameter of the first metal particle 102 , in the case of Examples 3-2-3-4 in which the particle diameter of the first metal particle 102 is 3, 20, and 30 μm, respectively is, the judgment of bonding and heat resistance is Yes, the judgment of strength is A, and in Examples 3-1 and 3-5 with particle diameters of 0.5 and 45 μm, the judgment of bonding and heat resistance is Yes, and the judgment of strength is B.

In the case of Example 3-1 in which the particle diameter of the first metal particle 102 is small, since the particle diameter of the second metal particle 103 is close to that of the second metal particle 103, the number of points in contact with the second metal particle 103 increases. Therefore, the speed of liquid phase sintering during heating in the bonding process is very large, 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 the strength is lower than in other examples. I think it gets smaller

Conversely, in the case of Example 3-5 in which the particle diameter of the first metal particle 102 is large, compared to the second metal particle 103, the particle diameter of the first metal particle 102 is very large, so that the bonding material 101 Since the uniformity at the time of manufacturing fell, compared with the other Example, it is thought that the joint strength also becomes comparatively small.

Paying attention to the particle diameter of the second metal particle 103, in the case of Examples 3-7 to 3-10, wherein the particle diameter of the second metal particle 103 is 100, 400, 1200, and 2000 nm, respectively, bonding and heat resistance determination This Yes, determination of strength is A, and in Examples 3-6 and 3-11 which are 50 and 6000 nm, determination of bonding and heat resistance is Yes, and determination of strength is B.

In Example 3-6 in which the particle diameter of the second metal particle 103 is small, the particle diameter of the second metal particle 103 is very small, so that the second metal during production of the bonding material 101 or during heating of the bonding process. Since aggregation of the particle|grains 103 arises and uniformity falls, it is thought that this is because the bonding strength also becomes comparatively small compared with the other Example.

In Example 3-11 in which the particle diameter of the second metal particles 103 is large, diffusion into the melting first metal particles 102 in the bonding process is slow due to the large particle diameter of the second metal particles 103, and the metal particles It is thought that this is because the particle size of the liver compound becomes large.

From the result of this Embodiment 3, the following is confirmed.

It is preferable that the 1st metal particle 102 contains the particle|grains with a median diameter of 3-30 micrometers at least.

It is preferable that the 2nd metal particle 103 has a median diameter of 100-2000 nm. In the bonding material 101 satisfying these requirements, it is possible to provide a bonding material capable of forming a bonding portion having high bonding strength.

<Suitable conditions for the present invention>

As described above, from the results of Embodiments 1 to 3, as suitable conditions for expressing the effect of the bonding material of the present disclosure, the bonding material has a melting point of 200° C. or less, the first metal particles 102 , and the first metal particles. A first metal element included in 102 and a second metal particle 103 including a second metal element capable of generating an intermetallic compound, TiO ₂ nanoparticles 104 , and a flux 105 . It is a bonding material 101 that

In addition, the first metal particles 102 contain only the first metal element that generates the second metal element and the intermetallic compound, or the first metal element that generates the second metal element and the intermetallic compound, and the second metal element. and a third metal element that does not form an intermetallic compound and the melting point of the metal element alone is 250° C. or higher.

Furthermore, the ratio of the first metal particle 102 and the second metal particle 103 is the first metal element contained in the first metal particle 102 in the equilibrium diagram of the first metal element and the second metal element, and , a ratio in which all of the second metal elements included in the second metal particles 103 become intermetallic compounds.

As a more suitable condition, the TiO ₂ nanoparticles 104 may have a median diameter of 20 to 80 nm.

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

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

As more suitable conditions, the 2nd metal particle 103 may contain Cu.

As more suitable conditions, the 1st metal particle 102 may contain the particle|grains with a median diameter of 3-30 micrometers at least.

As a more suitable condition, the second metal particle 103 may have a median diameter of 100 to 2000 nm.

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

In addition, in this embodiment, although Ti/Ni/Au is used for the electrode of the SiC element used for evaluation, this indication is not limited to this, If it is an electrode which can be joined by the 1st metal particle 102, it is this indication can exhibit the effect of

On the other hand, in the present disclosure, any embodiment and/or example among the various embodiments and/or examples described above is appropriately combined, and the effect of each embodiment and/or example can be exhibited. have.

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

101 bonding material
102 first metal particles
103 second metal particles
104 TiO ₂ Nanoparticles
105 flux

Claims (8)

A first metal particle having a melting point of 200° C. or less, and
a second metal particle including a first metal element included in the first metal particle and a second metal element capable of forming an intermetallic compound;
TiO ₂ nanoparticles and,
flux
As a bonding material comprising:
The first metal particles,
only the first metal element forming an intermetallic compound with the second metal element, or
The first metallic element that forms the second metallic element and the intermetallic compound, and the third metallic element that does not form the second metallic element and the intermetallic compound and the melting point of the metallic element alone is 250° C. or higher a complex comprising
any one of
The ratio of the first metal particle to the second metal particle is the first metal element contained in the first metal particle in the equilibrium diagram of the first metal element and the second metal element, and the second metal The ratio in which all of the second metal elements contained in the particles are intermetallic compounds,
bonding material. The method of claim 1,
The said TiO ₂ nanoparticles are a median diameter of 20 to 80 nm, a bonding material. 3. The method of claim 1 or 2,
The content of the TiO ₂ nanoparticles is 0.1 wt% to 1 wt% in the total of the first metal particles, the second metal particles, and the TiO ₂ nanoparticles. 4. The method according to any one of claims 1 to 3,
The bonding material, wherein the first metal particles are at least one selected from the group consisting of Sn-Bi, Sn-In, Sn-Bi-In, Bi-In, and In. 5. The method according to any one of claims 1 to 4,
The bonding material in which the said 2nd metal particle contains Cu. 6. The method according to any one of claims 1 to 5,
The bonding material in which the said 1st metal particle contains at least particle|grains with a median diameter of 3-30 micrometers. 7. The method according to any one of claims 1 to 6,
The bonding material, wherein the second metal particles have a median diameter of 100 to 2000 nm. A power device element of SiC or GaN;
The said bonding material in any one of Claims 1-7 which joins the electrode of the said power device element, and an external electrode.
A mounting structure provided with.

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