WO2024069866A1

WO2024069866A1 - Bonding member and semiconductor device

Info

Publication number: WO2024069866A1
Application number: PCT/JP2022/036485
Authority: WO
Inventors: 浩次山▲崎▼; 紀和境
Original assignee: 三菱電機株式会社
Priority date: 2022-09-29
Filing date: 2022-09-29
Publication date: 2024-04-04
Also published as: JP7267522B1

Abstract

Provided is a bonding member (1) that bonds a first object (2) and a second object (3). The bonding member (1) includes: metal particles (11) containing Ni as a main component; a low-melting-point phase (12) including Sn as a main component and having a melting point of less than 300°C; and an intermetallic compound (13) that is the result of interdiffusion between the Sn and the metal particles (11) and has a melting point of 300°C or greater. The percentage of the amount of the low-melting-point phase (12) to the total amount of the bonding member (1) is greater than or equal to 2 vol% and less than 20 vol%. The thermal expansion coefficients of the first object (2) and the second object (3) are greater than or equal 3 x 10^-6/K and less than 13 x 10^-6/K, and the difference between the thermal expansion coefficients of the first object (2) and the second object (3) is less than 5 x 10^-6/K. The thermal expansion coefficient of the bonding member (1) is greater than or equal to 16 x 10^-6/K and less than 20 x 10^-6/K.

Description

Bonding member and semiconductor device

This disclosure relates to a joining member and a semiconductor device.

In recent years, there has been an increasing demand for reliability in semiconductor devices. In particular, there is a demand for improved life reliability in joints between parts with different thermal expansion coefficients (for example, the joint between a semiconductor element and a circuit board, or the joint between a circuit board and a heat sink).

Traditionally, semiconductor elements with substrates made of silicon (Si), gallium arsenide (GaAs), etc. are widely used. The operating temperature of such semiconductor elements is 100°C to 125°C. The solder material used to join these semiconductor elements to circuit boards is required to have a high melting point to accommodate the multi-stage soldering that occurs during manufacturing, crack resistance to repeated thermal stress associated with startup and shutdown, and resistance to contamination of the device.

To meet these requirements, for example, 95Pb-5Sn (mass%) has been used as a solder material for Si devices, and 80Au-20Sn (mass%) has been used as a solder material for gallium arsenide devices.

However, 95Pb-5Sn contains a large amount of harmful lead (Pb), which is problematic from the perspective of reducing the environmental impact. Also, 80Au-20Sn, which contains a large amount of precious metals, is problematic in terms of the rising price of precious metals and their limited reserves. Therefore, there has been a strong demand for alternative materials for both.

On the other hand, from the perspective of energy conservation, there has been active development of next-generation devices with substrates made of silicon carbide (SiC) or gallium nitride (GaN). The operating temperature of these devices is expected to be 175°C or higher, and it is said that this will reach 300°C in the future.

This means that the temperature at the junction between the semiconductor element and the circuit board will reach 175°C. Furthermore, the temperature at the junction between the circuit board and the heat sink will also rise to a temperature close to this, depending on the operating conditions and heat dissipation performance. For this reason, high reliability is required for the junction between the circuit board and the heat sink, as well as the junction between the semiconductor element and the circuit board.

As described above, conventional and next-generation devices require materials (joint materials) that have high melting points and excellent heat resistance to form the above-mentioned joints.

A conventional method for manufacturing a highly heat-resistant bonded body is to add a large amount of metal particles such as Ag or Cu to Sn, and form a bonding layer from an Ag-Sn alloy phase (e.g., Ag ₃ Sn: melting point 480°C), a Cu-Sn alloy (e.g., Cu ₆ Sn ₅ : melting point 415°C, Cu ₃ Sn: melting point 676°C), etc. by metal diffusion caused by heating (300°C or less) during bonding.

For example, Patent Document 1 (JP Patent Publication 2002-314241 A) discloses a connection method or electronic device using solder, in which the Sn in the solder ball melts and forms an intermetallic compound at the interface with the Cu in the metal ball, connecting the Cu metal balls. The molten Sn also forms an intermetallic compound with the electrodes of the semiconductor chip and the electrodes of the intermediate substrate, connecting the Cu metal balls to these electrodes.

Furthermore, Patent Document 1 describes that the connection portion has sufficient strength to withstand the process of subsequent solder connection, as the Sn in the solder ball becomes a Cu-Sn intermetallic compound (Cu ₆ Sn ₅ , melting point: approximately 630° C.), causing the contact portion and its vicinity to have a high melting point, and even if some of the Sn remains, as long as other portions do not melt.

In addition, the metal balls are not limited to Cu, and may be Ag, Au, Al, Ni, Cu alloys, Cu-Sn compounds, Ag-Sn compounds, Au-Sn compounds, Al-Ag compounds, Zn-Al compounds, etc., and Patent Document 1 also states that Au has good wettability and therefore has the effect of reducing voids in the connection.

Patent Document 2 (WO 2012/108395) describes that by heating and melting solder containing Sn-based metal and Cu-based metal at the connection, an intermetallic compound with a melting point of 310°C or higher is formed. It also discloses that the ratio of Sn-based metal components contained in the connection is 30% by volume or less.

JP 2002-314241 A International Publication No. 2012/108395

However, in the conventional semiconductor device manufacturing methods shown in

Patent Documents

1 and 2, the amount of metal particles added relative to Sn particles has not been evaluated in terms of crack resistance in thermal shock tests.

For example, adding a large amount of metal particles such as Cu particles or Ag particles reduces the fluidity of Sn, leaving the areas sealed between the metal particles unjoined, creating voids and making the joints susceptible to cracks when subjected to thermal shock.

In addition, Ag-Sn alloys such as Ag ₃ Sn or Cu-Sn alloys such as Cu ₆ Sn ₅ have a solid solution region of about 5 mass % Ag or Cu and Sn in terms of the metal phase diagram. However, since they show a two-phase separation type phase, the interface between Ag ₃ Sn and Cu ₆ Sn ₅ becomes a void if there is no Sn phase with a low melting point, and becomes the starting point of cracks.

On the other hand, the inventors of the present invention believe that in semiconductor devices that operate at high temperatures, it is important to ensure not only the mechanical properties of the material or the heat cycle resistance of the individual parts to which it is applied, but also the reliability of the device in the power cycles that accompany actual operation (repeated heating and cooling caused by repeatedly turning the application of power to the semiconductor device on and off).

The objective of this disclosure is to provide a joining member with high joining reliability against power cycles in semiconductor devices that operate at high temperatures.

A joining member that joins the first object and the second object.
The joining member includes metal particles containing Ni as a main component, a low-melting point phase containing Sn as a main component and having a melting point of less than 300°C, and an intermetallic compound having a melting point of 300°C or higher that is formed by interdiffusion between Sn and the metal particles.
The ratio of the amount of the low melting point phase to the total amount of the joining members is 2 vol % or more and less than 20 vol %.
The thermal expansion coefficients of the first object and the second object are equal to or greater than 3×10 ⁻⁶ /K and less than 13×10 ⁻⁶ /K, and the difference in thermal expansion coefficient between the first object and the second object is less than 5×10 ⁻⁶ /K.
The thermal expansion coefficient of the joining member is 16×10 ⁻⁶ /K or more and less than 20×10 ⁻⁶ /K.

According to the present disclosure, it is possible to provide a joining member with high joining reliability against power cycles in a semiconductor device that operates at high temperatures.

Specifically, in the joining member disclosed herein, a low melting point phase (e.g., a Sn-only phase) is left remaining, ensuring wettability to the joined members (objects to be joined), and by optimizing the amount of this remaining phase, vertical cracks during power cycles can be suppressed.

In addition, the joining member disclosed herein is applied to joining multiple objects whose thermal expansion coefficient difference is within a specific range, and therefore can suppress lateral cracks caused by shear stress resulting from the difference in thermal expansion coefficient between multiple objects to be joined.

Furthermore, by using a joining material with a thermal expansion coefficient within a specific range, the tensile stress and compressive stress (tensile-compressive stress) caused by the difference in thermal expansion coefficient between the objects to be joined and the joining material is suppressed, resulting in excellent joining reliability even when operating at high temperatures (e.g., 175°C).

1 is a flowchart showing a manufacturing procedure of a semiconductor device (bonding member). FIG. 2 is a schematic cross-sectional view showing a first step in FIG. 1 . FIG. 2 is a schematic cross-sectional view showing a second step in FIG. 1 . FIG. 2 is a schematic cross-sectional view showing a third step in FIG. 1 . FIG. 2 is a schematic cross-sectional view showing a fourth step in FIG. 1 . FIG. 2 is a schematic cross-sectional view showing a fifth step in FIG. 1 .

The following describes an embodiment of the present disclosure. Note that in the drawings, dimensional relationships such as length, width, thickness, and depth have been changed as appropriate to clarify and simplify the drawings, and do not represent actual dimensional relationships.

Embodiment 1.
<Joining materials>
The joining member 1 of this embodiment is a member that joins a first object 2 (e.g., a heat sink) and a second object 3 (e.g., a circuit board having a semiconductor element and a wiring circuit) (see FIG. 6). Note that, unlike a solder sheet 10 described later, the joining member 1 is a member made of solder (solder alloy) that is melted by a heating process and then solidified, and exists in a state where it is joined to both of the members to be joined (the first object 2 and the second object 3).

The joining member 1 of this embodiment includes metal particles 11, a low melting point phase 12, and an intermetallic compound 13.

Metal particles 11 contain Ni as a main component. Here, the "main component" refers to the component contained in metal particles 11 that is present in the largest amount. The content of Sn in metal particles 11 is preferably 60 mass% or more, more preferably 70 mass% or more, and even more preferably 80 mass% or more.

The metal particles 11 may further contain at least one component selected from the group consisting of Fe, Cr, C, Cu, and Si.

The low melting point phase 12 contains Sn as a main component and has a melting point of less than 300°C. Here, the "main component" refers to the component contained in the low melting point phase 12 in the greatest amount. The content of Sn in the low melting point phase 12 is preferably 60 mass% or more, more preferably 70 mass% or more, and even more preferably 80 mass% or more.

The low melting point phase may further contain, for example, Ag and Cu (in addition to Sn). In this case, for example, the Ag content may be 3 mass% or more and less than 4 mass%, and the Cu content may be 0.5 mass% or more and less than 1.0 mass%. If the Ag and Cu contents are within this range, it is expected that the effects of the present disclosure can be obtained more reliably.

The intermetallic compound 13 is a compound (phase) formed by interdiffusion between Sn and metal particles 11, and has a melting point of 300°C or higher.

In addition, in the joining member 1 of this embodiment, the ratio of the amount of the low melting point phase 12 to the total amount of the joining member 1 is 2 volume % or more and less than 20 volume %.

Furthermore, the thermal expansion coefficients of the first object 2 and the second object 3 are greater than or equal to 3×10 ⁻⁶ /K and less than 13×10 ⁻⁶ /K, and the difference in thermal expansion coefficient between the first object 2 and the second object 3 is less than 5×10 ⁻⁶ /K.

The thermal expansion coefficient of the joining member is not less than 16×10 ⁻⁶ /K and less than 20×10 ⁻⁶ /K.

The inventors conducted reliability tests on semiconductor devices using power cycles and found that suppressing cracks (vertical cracks) that occur in the thickness direction of the layers of the joining material during power cycles is important for improving joining reliability.

Furthermore, the reliability of the joint depends not only on the material that makes up the joining member, such as solder, but also on the composition of the joined members (objects to be joined). For this reason, in order to improve the reliability of power modules, it is necessary to consider not only the composition of the materials of the joining members, but also the composition of the joined members.

In regards to these vertical cracks, the reference (Yamazaki Koji, "Research into the conditions for vertical cracks in lead-free solder joints", 26th Electronics Packaging Academic Lecture Conference, 9C-14) states that when a high-speed heat cycle test (+50°C/+175°C, temperature difference: 125°C) was conducted on a sample in which Cu plates were soldered together, and a sample in which Mo plates were soldered together, vertical cracks did not occur in the former, but did occur in the latter, even though both were joined using the same solder material.

This is related to the tensile stress and compressive stress (tensile-compressive stress) caused by the difference in the thermal expansion coefficient between the solder material and the joined parts. When solder is restrained by a low-thermal expansion material, the solder, which has a large thermal expansion coefficient, is subjected to tensile-compressive stress, and when heated, dynamic recrystallization occurs in the solder, causing vertical cracks to form along the grain boundaries or internal precipitates of Sn, the main component of the solder.

It is known that when there is a large difference in the thermal expansion coefficient between the joined components (between two objects to be joined), horizontal cracks tend to occur rather than vertical cracks.

As a result of the above-mentioned investigations, the inventors have discovered the bonding material disclosed herein that has high bonding reliability against power cycles in semiconductor devices that operate at high temperatures.

Embodiment 2.
<Semiconductor Device>
The semiconductor device according to the present embodiment includes a heat sink 2 and a circuit board 3 (a board having a semiconductor element and a wiring circuit). The heat sink 2 and the circuit board 3 are joined via the highly reliable joining member 1 described in the first embodiment. This provides a highly reliable semiconductor device.

The semiconductor device of this embodiment can be manufactured by a manufacturing method that includes a step of joining a heat sink and a circuit board (see Figures 1 to 6).

Below, an example of the procedure for joining a circuit board and a heat sink in the semiconductor device manufacturing method of this embodiment will be described with reference to the flowchart shown in Figure 1.

First, in the first step (S1), a solder sheet 10 is cut to a predetermined size (see Figure 2), which is made of a low-melting-point phase 12 containing Sn as the main component and having a melting point of 300°C or less, and in which metal particles 11 made of Ni are dispersed.

Specifically, as a representative example of the solder composition of the low melting point phase 12, each element was added and melted to obtain the composition shown below (the values indicate mass percentages. Sn is the remainder of the composition ratio of the other elements), and a bulk body was produced.

Next, a rolled solder sheet 10 was produced using a rolling process at 100°C or less so that the thickness was 100 μm.

Then, Ni particles (metal particles 11) are uniformly dispersed in the solder sheet 10, and a sheet made of a low melting point phase 12 is layered on top of it to create a mixed sheet. In this embodiment, the thickness is 100 μm, but this is not essential. The cut size is the same as the upper member, 10 mm x 10 mm.

In addition, the solder sheet 10 may be manufactured not only by rolling, but also by melting the bulk and sequentially pouring the molten solder through thin slits. Also, when the combination of elements is more than three elements as described above (for example, when Bi, In, Sb, etc. are added to Sn-Ag-Cu), the composition of the bulk may become non-uniform due to temperature variations in the melting furnace. In that case, the solder composition may be adjusted by first manufacturing a bulk of Sn-Ag-Cu, melting it again, and adding a specified amount of the remaining Bi, In, Sb, etc. Alternatively, the solder sheet 10 may be manufactured by first forming solder balls, uniformly scattering the solder balls on a flat plate, and compression molding the solder sheet 10.

Next, in the second step (S2), the solder sheet 10 is placed on the first object 2 (lower member) (see Figure 3).

In addition, to prevent oxidation, a predetermined amount of rust inhibitor with a decomposition temperature of 100°C or less that does not affect the bonding properties may be applied to the outermost surface of the CuMo alloy plate. Also, when placing the solder sheet 10, an organic agent that thermally decomposes at a high temperature of 100°C or more may be used as a tack material to prevent the solder sheet 10 from shifting from its designated position. The viscosity of the tack material is preferably 200 Pa·s or more. Alternatively, a resist film may be applied to the areas other than the joint of the first object 2 to prevent the solder sheet 10 from shifting.

The solder sheet 10 may be slightly curved during cutting or handling. This is because the solder sheet 10 melts to some extent when heated, so the effect of the initial shape of the solder sheet is small. However, if the solder sheet 10 is curved so much that the second object 3 (upper member) cannot be placed on it in the next process, the solder sheet 10 is straightened so that it is parallel on another flat plate.

Next, in the third step (S3), the second object 3 (upper component) is placed on the solder sheet 10 (see Figure 4).

The above-mentioned tack material may be applied between the joined member (upper member) 1 and the solder sheet 10 to fix the mounting position.

It is preferable that the surfaces of the members to be joined (first object 2 and second object 3) on the joining side are plated with Cu or Ni, or are coated with a film of Au, Ag, Pt, etc., on the order of several tens of nanometers.

Next, in the fourth step (S4), the laminate of each component obtained in the above steps was placed on a hot plate 5 in a heating furnace 5 (see FIG. 5). Then, formic acid, a typical organic acid capable of reducing oxide films, was sealed in the heating furnace 5, and the solder sheet 10 was melted by heating at 180°C for 5 minutes and then at 260°C for 3 minutes to form the joining member 1.

Here, the low melting point phase 12 and metal particles 11 in the solder sheet 10 form a compound through thermal diffusion. The ratio of compounds (intermetallic compounds) formed between the metal particles 11 and Sn varies depending on the particle size and amount of the metal particles 11 added. For this reason, it is preferable to adjust the particle size and amount of the metal particles 11 added so that the low melting point phase 12 remains.

Firstly, the reason for this is that if most of the joining member 1 is made up of metal particles 11 and intermetallic compounds 13, the Sn in the low melting point phase 12 cannot deform, so there is no problem with the reliability of the joining.

On the other hand, the surfaces of the general-purpose members to be joined (first object 2 and second object 3) are rough, and the surface roughness (unevenness) may be on the order of a few μm. For this reason, when joining without pressure, the low-melting point phase 12 needs to wet and spread over the volume of the unevenness on the surface. However, if a large amount of metal particles 11 is present, the surface area of the metal particles 11 in the solder sheet 10 becomes large, and the low-melting point phase 12 reacts preferentially with the metal particles 11, and the low-melting point phase 12 does not wet sufficiently to the surfaces of the members to be joined.

For this reason, in this embodiment, it is preferable to adjust the particle size and amount of metal particles 11 added so that the low melting point phase 12 remains. For example, the particle size (average particle size: D50) of metal particles 11 added to solder sheet 10 is 5 to 20 μm, and the compounding ratio of metal particles in solder sheet 10 is 8 to 30 mass %.

If there is no concern about damage to the joined parts, pressure may be applied to join them.

Next, in the fifth step (S5), the sample on which the joining member 1 was formed was placed on a cooling plate 6 and cooled (see Figure 6).

In this case, if the solder joint is made of a material that melts completely, like regular solder, there is a possibility that the joined parts (upper or lower parts) will warp or swell (causing unevenness) due to thermal contraction. For this reason, it is desirable to cool gradually during the cooling process. For example, it is generally cooled to 100°C within 60 seconds, but in order to reduce warping, it may take approximately 400 seconds to reach 100°C.

In the present disclosure, since the main component of the metal particles 11 is Ni, which has a lower thermal expansion coefficient than Sn, the amount of thermal contraction of the solder sheet 10 is small, and since the thermal expansion coefficients of the members to be joined (first object 2 and second object 3) are each 3×10 ⁻⁶ /K or more and less than 13×10 ⁻⁶ /K, and the difference in the thermal expansion coefficient between the first object 2 and the second object 3 is less than 5×10 ⁻⁶ /K, warping is small and it is possible to reduce residual stress generated in the joining member 1. For this reason, there is no particular need to extend the time of the cooling process.

In actual application to a power module, for example, a circuit board on which a semiconductor element and a circuit pattern are formed can be joined to a heat sink via the above-mentioned joining member 1. The joining member 1 (solder sheet 10) can be applied to the die bond portion, base attachment portion, etc. of a power module, regardless of the size of the joining area.

The oxygen concentration in the solder sheet 10 is also important. The metal particles 11 contain Ni, which is easily oxidized, and the surface area of the metal particles 11 is large. For this reason, even if only a small amount of surface oxidation of the metal particles 11 occurs, if the oxidation progresses from the interface of the metal particles 11, the overall amount of oxidation will become large, significantly affecting wettability. Therefore, if the oxygen concentration in the solder sheet 10 is high, a good bonding member will not be formed unless it is stored in a vacuum desiccator or the like. Therefore, in order to form a good bonding member, it is preferable that the oxygen concentration in the solder sheet 10 is greater than 0 and less than 500 ppm.

The present disclosure will be explained in more detail below with reference to examples, but the present disclosure is not limited to these examples.

(Test Example 1)
Following the procedure of the above embodiment described with reference to Fig. 1, bonding samples (samples 1 to 7) were produced by changing the thermal expansion coefficients of the first object 2 and the second object 3 as shown in Table 1. The particle size (average particle size: D50) of the metal particles 11 added to the solder sheet 10 was 10 µm.

A CuMo alloy plate (thickness: 1 mm, size: 20 mm x 20 mm) was used as the first object 2. The outermost surface of the CuMo alloy plate was solid copper, and no plating was applied to this outermost surface. In this CuMo alloy plate, the compounding ratio of Cu and Mo was changed to change the thermal expansion coefficient as shown in Table 1. However, an Invar alloy was used as the first object with a thermal expansion coefficient of 2.

In addition, with DBC (Direct Bonded Copper) boards or CIC (Copper-Invar-Copper) boards, the thermal expansion coefficient can be adjusted as desired by changing the thickness of the three layers that make up the board.

The second object 3 has a thickness of 100 μm and a size of 10 mm × 10 mm. The thermal expansion coefficient of this second object 3 was changed as shown in Table 1 by changing the compounding ratio of the CuMo alloy and the Invar alloy, as in the first object 2.

In order to ensure that the wettability does not differ depending on the type of joined material, the surfaces of the joining sides of the first object 2 and the second object 3 were plated with Ni to a thickness of 3 μm.

A high-speed thermal shock test simulating a power cycle test was conducted on the bonded samples of the combinations shown in Table 1 obtained as described above. Specifically, a thermal shock test was conducted in which one cycle consisting of 10 seconds of power ON (attained temperature: 175°C) and 10 seconds of power OFF (attained temperature: 50°C) was repeated 100,000 times.

After the thermal shock test, a cross section was made in the thickness direction of the layers of the bonding members of the bonded sample, and the transmitted X-ray image of the cross section was binarized and subjected to image analysis to measure the area ratio of voids that had occurred in the bonding members to the total area (100%) of the bonding members in the cross section. If the area ratio of voids was 10% or more, it was evaluated as "NG", and if it was less than 10%, it was evaluated as "OK" since there was no problem in practical use. The evaluation results are shown in Table 1.

From the results shown in Table 1, it can be seen that when the thermal expansion coefficients of the first object 2 and the second object 3 are equal to or greater than 3×10 ^{-6 /} K (3.0× ^{10 -6} /K) and less than 13×10 ^{-6 /} K (13.0×10 ^-6 /K), and the difference in the thermal expansion coefficients between the first object 2 and the second object 3 is less than 5×10 ^-6 /K (5.0× ^{10 -6} /K), the evaluation result is OK, and voids are unlikely to occur in the bonding member after the high-speed thermal shock test. Therefore, it can be seen that the present disclosure can provide a bonding member having high bonding reliability against power cycles in a semiconductor device operating at high temperatures, and a semiconductor device using the same.

Note that this result is also related to the thermal expansion coefficient of the joint (joining member and joined member). As mentioned above, a lateral tensile and compressive stress is applied to the joining member restrained by the joined members (first object 2 and second object 3), causing vertical cracks. In other words, if the thermal expansion coefficient of the joining member 1 is small, the generated stress can also be reduced. In this disclosure, metal particles 11 containing Ni as a main component are used. It is difficult to predict from publicly known literature the extent to which the thermal expansion coefficient of the joining member 1 using the metal particles 11 will affect the joining reliability.

As a result of the inventors' actual investigation of the thermal expansion coefficient etc. of the joining member 1, it was found that good results (samples 2 to 4 in Table 1) can be obtained when the thermal expansion coefficient of the joining member is 16×10 ⁻⁶ /K or more and less than 20×10 ⁻⁶ /K, and when the ratio of the area of the above-mentioned low melting point phase (a phase containing Sn as a main component and having a melting point of less than 300°C) to the total area (100%) of the joining member in the cross section of the joining member (cross section in the thickness direction of the layers of the joining member) is 2% or more and less than 20% (i.e., when the ratio of the amount of the low melting point phase 12 to the total amount of the joining member 1 is 2% or more and less than 20% by volume).

The embodiments and examples disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is indicated by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

1. Joining material, 10. Solder sheet, 11. Metal particles, 12. Low melting point phase, 13. Intermetallic compound, 2. First object (heat sink), 3. Second object (circuit board), 4. Heating furnace, 5. Hot plate, 6. Cooling plate.

Claims

A joining member for joining a first object and a second object,
Metal particles containing Ni as a main component;
A low melting point phase containing Sn as a main component and having a melting point of less than 300°C;
an intermetallic compound having a melting point of 300° C. or higher produced by interdiffusion between Sn and the metal particles;
Including,
A ratio of the amount of the low melting point phase to the total amount of the joining members is 2 vol% or more and less than 20 vol%,
the thermal expansion coefficients of the first object and the second object are 3×10 −6 /K or more and less than 13×10 −6 /K, and the difference in thermal expansion coefficient between the first object and the second object is less than 5×10 −6 /K;
The bonding member has a thermal expansion coefficient of 16×10 −6 /K or more and less than 20×10 −6 /K.
The joining member according to claim 1, wherein the low melting point phase further contains Ag and Cu.
The joining member according to claim 1 or 2, wherein the metal particles further contain at least one component selected from the group consisting of Fe, Cr, C, Cu and Si.
the first object is a heat sink,
The joining member according to any one of claims 1 to 3, wherein the second object is a circuit board having a semiconductor element and a wiring circuit.
a heat sink and a circuit board having a semiconductor element and a wiring circuit;
A semiconductor device, wherein the heat sink and the circuit board are joined via the joining member according to claim 4 .