Alloy ingots for bonding materials

Abstract

The present invention provides an alloy ingot for joining materials that possesses flexibility characteristics capable of withstanding continuous vibration and operation, and can serve as a joining material with excellent mechanical strength. [Solution] The above problem was solved by providing an alloy ingot for joining materials, which has an intermetallic compound crystal containing Sn, Cu, Ni, Ge, Si, and Ti in a matrix phase containing Sn, Sn-Cu alloy, and Sb, with a composition of Cu 0.7-15 mass%, Ni 0.1-5 mass%, Sb or Bi or Ga 0.1-14 mass%, Ge 0.001-0.1 mass%, Si 0.001-0.1 mass%, Ti 0.001-0.1 mass%, and the remainder being Sn, and at least a portion of the matrix phase and the intermetallic compound crystal are endotaxially joined.

Description

Technical Field

[0001] The present invention relates to an alloy ingot for a bonding material.

Background Art

[0002] With the progress of IoT (Internet of Things) and the increasing demand for further energy conservation, the importance of power semiconductors, which are the core of such technologies, is becoming increasingly high. However, there are many issues in its utilization. Since power semiconductors handle large amounts of power at high voltages and large currents, they generate a lot of heat and become high in temperature. The heat resistance required for current Si power semiconductors is to cope with about 175°C, but the development of Si power semiconductors that can withstand temperatures of about 200°C is in progress. Also, next-generation power semiconductors such as SiC, GaN, and Ga2O 3、 can withstand 250 to 500°C, and when mounted on a vehicle, flexibility characteristics (hereinafter also referred to as vibration continuous operation state characteristics) that can withstand severe vibration continuous operation states are required.

[0003] On the other hand, regarding bonding materials, those having high heat resistance and vibration continuous operation state characteristics required for next-generation power semiconductors such as SiC and GaN as described above do not exist in the prior art. For example, the SnAgCu-based bonding material (solder material) disclosed in Patent Document 1 can only be applied to power semiconductors corresponding to about 125°C and cannot be applied to next-generation power semiconductors. Also, the low-melting-point brazing materials and solder alloys disclosed in Patent Document 3 and Patent Document 4 do not have vibration continuous operation state characteristics.

[0004] On the other hand, in Patent Document 2, the applicant has proposed a metal particle comprising an outer shell and a core, wherein the core contains a metal or alloy, the outer shell is made of an intermetallic compound and covers the core, the core contains Sn or a Sn alloy, and the outer shell contains an intermetallic compound of Sn and Cu. It has been confirmed that joints formed by these metal particles can maintain high heat resistance, joint strength, and mechanical strength over a long period of time, even when used in harsh environments with large temperature fluctuations from high-temperature operating conditions to low-temperature stopped conditions over a long period of time. However, when the joint structure is subjected to harsh continuous vibration conditions, the brittleness, which is a drawback of intermetallic compounds, becomes an obstacle.

[0005] Furthermore, in Patent Document 5, the applicant proposed metal particles having an intermetallic compound composed of Sn, Cu, and Ni in a matrix phase containing Sn and a Sn-Cu alloy, wherein at least a portion of the Sn-Cu alloy and the intermetallic compound in the matrix phase are endotaxially bonded. However, it was found that at temperatures above 260°C, the matrix phase surrounding the intermetallic compound shrinks, causing the endotaxial bonding to collapse and promoting the formation of voids. Therefore, when used in harsh environments at high temperatures, it may not be possible to maintain high heat resistance, bonding strength, and mechanical strength over the long term, and there is a risk of impairing the characteristics of continuous vibration operation. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2007-268569 [Patent Document 2] Patent No. 6029222 [Patent Document 3] Patent No. 6369620 [Patent Document 4] International Open Brochure WO2014 / 084242A1 [Patent Document 5] Patent No. 6799649 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The object of the present invention is to provide an alloy ingot for joining materials that can serve as a joining material having flexibility characteristics that can withstand continuous vibration operation and excellent mechanical strength. [Means for solving the problem]

[0008] As a result of diligent research, the inventors discovered that the collapse of the endotaxial junction can be suppressed by introducing an expanding metal (Sb, Bi, Ga) that does not cause shrinkage of the matrix phase into the matrix phase, thus completing the present invention.

[0009] In other words, the present invention is Sn and; Sn-Cu alloy and; With Sb, Bi, or Ga; An alloy ingot for bonding materials having intermetallic compound crystals containing Sn, Cu, Ni, Ge, Si, and Ti in a matrix containing, The composition of the alloy ingot for the joining material is Cu 0.7-15 mass%, Ni 0.1-5 mass%, Sb or Bi or Ga 0.1-14 mass%, Ge 0.001-0.1 mass%, Si 0.001-0.1 mass%, Ti 0.001-0.1 mass%, and the remainder is Sn (however, unavoidable impurities may be included in amounts of 0.1 mass% or less), The composition of the matrix phase is Sn 85-99.9% by mass, Cu 5% or less by mass, and Sb or Bi or Ga 0.1-14% by mass. At least a portion of the matrix phase and the intermetallic compound crystal are endotaxially bonded, This invention provides an alloy ingot for joining materials characterized by the following features. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide an alloy ingot for a bonding material that can have flexibility characteristics capable of withstanding a vibration continuous operation state and has excellent mechanical strength, and can be a bonding material.

Brief Description of the Drawings

[0011] [Figure 1] It is a SEM image of a cross-section obtained by resin-embedding and thinly cutting the alloy ingot of the present invention. [Figure 2] It is a TEM image of a cross-section of the alloy ingot obtained in Example 1 and a transmission electron diffraction pattern. [Figure 3] It is a SEM image of a cross-section obtained by resin-embedding and thinly cutting the alloy ingot of Comparative Example 1. [Figure 4] It is a SEM image of a cross-section obtained by resin-embedding and thinly cutting the alloy ingot of Comparative Example 2. [Figure 5] It is an optical micrograph showing the results of the flexibility characteristic tests of the alloy ingots of Example 2, Comparative Example 1, and Comparative Example 2. [Figure 6] It is a diagram for explaining a 190-degree bending test. [Figure 7] It is a schematic cross-sectional view for explaining a structure that can be joined using the alloy ingot of the present invention.

Modes for Carrying Out the Invention

[0012] Hereinafter, the present invention will be described in more detail. First, the terminology in this specification shall be as follows even without special explanation. (1) When referring to a metal, it may include not only a single metal element but also an alloy containing a plurality of metal elements and an intermetallic compound. (2) When referring to a single metallic element, it does not mean only a substance consisting entirely and purely of that metallic element, but also includes cases where it contains minute amounts of other substances. That is, it is not meant to exclude those containing trace amounts of impurities that have little effect on the properties of the metallic element. Of course, for example, in the case of a matrix phase, it is not meant to exclude cases where some of the atoms in the Sn crystal are replaced by other elements (e.g., Cu). For example, the above-mentioned other substances or other elements may be contained in the target substance at 0 to 0.1% by mass. (3) Endotaxial bonding means that intermetallic compound crystals precipitate in a substance that becomes a metal or alloy (in the present invention, the matrix phase), and during this precipitation, the Sn-Cu alloy and the intermetallic compound crystals are joined at the crystal lattice level to form crystal grains. The term "endotaxial" is well-known and is described, for example, in the left column last paragraph on page 160 of Nature Chemistry 3(2):160 - 6, 2011.

[0013] The alloy ingot for a bonding material of the present invention has high toughness, and thus can solve the above problems. This high toughness is particularly due to having intermetallic compounds with a specific composition in the matrix phase, that is, having intermetallic compound crystals containing Sn, Cu, Ni, Ge, Si, and Ti, and at least a part of the Sn-Cu alloy and the intermetallic compound crystals in the matrix phase being endotaxially bonded. According to this configuration, it is possible to impart, in particular, flexible characteristics that can withstand a vibration continuous operating state to the alloy ingot for a bonding material.

[0014] The alloy ingot for a bonding material of the present invention (hereinafter sometimes referred to as the alloy ingot of the present invention) will be further described.

[0015] FIG. 1 is a SEM image of a cross-section obtained by resin-embedding and thinly cutting the alloy ingot of the present invention. When analyzing the alloy ingot of the present invention shown in FIG. 1, it was found that the alloy ingot 10 has intermetallic compound crystals 120 containing Sn, Cu, Ni, Ge, Si, and Ti in a matrix phase 140 containing Sn, an Sn-Cu alloy, and Sb. Furthermore, it was found that intermetallic compound crystal 120 contains both monothorhombic and hexagonal crystal structures. This intermetallic compound crystal structure was confirmed using a Shimadzu XRD-6100 observation device and the database ICDD (International Centre for Diffraction Data).

[0016] The composition of the alloy ingot of the present invention is 0.7-15 mass% Cu, 0.1-5 mass% Ni, 0.1-14 mass% Sb or Bi or Ga, 0.001-0.1 mass% Ge, 0.001-0.1 mass% Si, 0.001-0.1 mass% Ti, with the remainder being Sn. However, unavoidable impurities may be present in amounts of 0.1 mass% or less.

[0017] Furthermore, the composition of the matrix phase in the alloy ingot of the present invention is 85-99.9% by mass of Sn, 5% or less by mass of Cu, and 0.1-14% by mass of Sb, Bi, or Ga.

[0018] Furthermore, the composition of the alloy ingot of the present invention, including the intermetallic compound crystals and the endotaxial bonding portion, Sn 50~70% by mass, Cu 30~50% by mass, Sb 0~3% by mass, Ni 0.1~6.5% by mass, Ge 0.001~0.1% by mass, Si 0.001~0.1% by mass, Ti 0.001~0.1% by mass, It is preferable that this be the case. The intermetallic compound is contained within the matrix phase.

[0019] The alloy ingot of the present invention can be manufactured from raw materials having a composition of, for example, 8 mass% Cu, 5 mass% Sb or Bi or Ga, 0.1 mass% Ni, 0.001 mass% Ge, 0.001 mass% Si, 0.001 mass% Ti, and the remainder being Sn. For example, the alloy ingot of the present invention can be obtained by melting the raw materials under vacuum by high-frequency induction heating, casting it into a mold under atmospheric pressure in a nitrogen gas atmosphere, and then cooling and solidifying it.

[0020] The above-described high-frequency induction heating and cooling solidification conditions are important for forming the alloy ingot of the present invention. For example, the following conditions can be cited. High-frequency induction heating: 9 × 10 -2 A high-frequency induction melting crucible is placed in a vacuum chamber capable of reducing the pressure to approximately Pa. The raw materials are introduced into the crucible, and high-frequency induction heating is performed on the raw materials while maintaining a reduced pressure of approximately Pa. The heating temperature is raised to 600°C to 800°C to melt the raw materials, and this temperature is maintained for 5 to 15 minutes. Cooling and solidification: Next, while flowing nitrogen gas at 15-50°C into the tank, the heating temperature is set to approximately 400°C or higher under atmospheric pressure, the material is poured into the mold, and then cooled and solidified at 30°C or lower.

[0021] Furthermore, the proportion of intermetallic compound crystals in the alloy ingot of the present invention is, for example, 20 to 60% by mass, and preferably 30 to 40% by mass. The composition and proportion of the intermetallic compound crystals can be satisfied by following the manufacturing conditions of the alloy ingot.

[0022] Furthermore, the composition of the matrix phase in the alloy ingot of the present invention is preferably 85-99.9% by mass of Sn, 5% by mass or less of Cu (for example, 0.3-5% by mass), 0.1-14% by mass of Sb, Bi, or Ga, and 0.1% by mass or less of unavoidable impurities.

[0023] The alloy ingot of the present invention is formed by endotaxial bonding of at least a portion of the Sn-Cu alloy and the intermetallic compound crystals in the matrix phase. As described above, endotaxial bonding is a process in which an intermetallic compound precipitates in the metal-alloy material (matrix phase in the present invention), and during this precipitation, the Sn-Cu alloy and the intermetallic compound crystals bond at the crystal lattice level, forming crystal grains. The formation of endotaxial bonding solves the problem of brittleness of the intermetallic compound crystals and also suppresses the decrease in mechanical strength due to the change in the crystal structure of Sn, as described below, thereby providing a bonding material with even higher heat resistance, bonding strength, and mechanical strength. The inventors have confirmed that the solder wire formed using the alloy ingot of the present invention maintains the endotaxial bonding between the Sn-Cu alloy and the intermetallic compound crystals in the alloy ingot.

[0024] The crystal structure of Sn is tetragonal in the temperature range of approximately 13°C to 160°C (Sn with a tetragonal crystal structure is called β-Sn), and changes to a cubic crystal structure at lower temperatures (Sn with a cubic crystal structure is called α-Sn). Furthermore, the crystal structure of β-Sn changes to an orthorhombic high-temperature phase crystal in the temperature range above approximately 160°C (Sn with an orthorhombic crystal structure is called γ-Sn). It is generally known that a large volume change occurs during the phase transition between tetragonal β-Sn and cubic α-Sn. The bonding material (e.g., solder wire) manufactured from the alloy ingot of the present invention contains high-temperature phase crystals even at temperatures below approximately 160°C (for example, at room temperature). For example, if the bonding material is heated in the bonding process in a semi-molten state without being completely melted, and a state including endotaxial bonding between the intermetallic compound crystal and the matrix phase is maintained, the state containing high-temperature phase crystals is maintained even in the temperature range below 160°C after cooling. Furthermore, even if the temperature is lowered to a certain extent, these high-temperature phase crystals are less likely to undergo a phase transition to tetragonal low-temperature phase crystal β-Sn, and for Sn that does not undergo a phase transition to tetragonal β-Sn, a phase transition to α-Sn does not occur, and a large volume change associated with the phase transition to α-Sn due to the decrease in temperature does not occur. Therefore, bonding materials containing Sn that have a high-temperature phase crystal even in temperature ranges below 160°C (for example, at room temperature) exhibit reduced volume changes due to temperature changes compared to other bonding materials containing Sn in their composition (i.e., those that do not intentionally contain a high-temperature crystalline phase even in temperature ranges below 160°C). Furthermore, various metals such as Cu, Ag, Au, Ni, and others are used in electronic components, and Sn bonds well with these various metals. Therefore, the bonding material manufactured from the alloy ingot of the present invention contains a high-temperature crystalline phase over a wide temperature range (for example, even at room temperature), and by avoiding the formation of the tetragonal low-temperature phase β-Sn as much as possible, it has the property of being less susceptible to large volume changes associated with the phase transition from tetragonal β-Sn to cubic α-Sn due to temperature changes, and also bonds well with various metals used in electronic components, making it particularly useful as a bonding material for fine bonding locations.

[0025] The effect of suppressing the change in the crystal structure of Sn, as described above, is well achieved through endotaxial bonding between the matrix phase and the intermetallic compound crystal in the alloy ingot.

[0026] Furthermore, in the alloy ingot of the present invention, the endotaxial bonding is preferably 30% or more, and more preferably 60% or more, when the entire bonding surface between the matrix phase and the intermetallic compound crystal is considered to be 100%. The proportion of the endotaxial bonding can be calculated, for example, as follows. As shown in Figure 1 below, an electron microscope image of the cross-section of the alloy ingot is taken, and 50 arbitrary locations are sampled at the bonding surface between the Sn-Cu alloy and the intermetallic compound crystal. Subsequently, the bonding surfaces are image-analyzed to determine the extent to which endotaxial bonding, as shown in the example below, exists on the sampled bonding surfaces.

[0027] On the other hand, the alloy ingot of the present invention can also be atomized by conventional methods. The particle size of the metal particles obtained in this way is preferably in the range of 1 μm to 50 μm. By processing these metal particles into a sheet or paste, and holding it in contact with the object to be joined at 160°C to 180°C for 3 minutes or more, then melting it at 235°C to 265°C and solidifying it, a good bond can be formed. Alternatively, a good bond can also be formed by holding it under reduced pressure conditions (reduced pressure of 50 cmHg to 100 cmHg) for about 1 second, then heating it to about 230°C under atmospheric pressure, then maintaining the atmospheric pressure at this temperature at 0.5 to 2 MPa, and finally solidifying it at room temperature. Furthermore, the inventors have confirmed that the metal particles formed using the alloy ingot of the present invention maintain endotaxial bonding between the Sn-Cu alloy in the matrix phase and the intermetallic compound crystal within the metal particles.

[0028] A sheet of the above-mentioned metal particles can be obtained, for example, by pressing the metal particles with rollers as follows: The metal particles are supplied between a pair of pressing rollers that rotate in opposing directions, and heat of about 100°C to 150°C is applied to the metal particles from the pressing rollers, thereby pressing the metal particles together to obtain a sheet. Furthermore, the above paste can be obtained by mixing metal particles into an organic vehicle. Furthermore, the inventors have confirmed that the metal particles, even after being processed into a sheet or paste form, have the same crystal structure as the alloy ingot of the present invention.

[0029] Furthermore, the sheet or conductive paste may be a mixture of metal particles with other particles, such as SnAgCu alloy particles, Cu, Cu alloy particles, Ni, Ni alloy particles, or mixtures thereof. These other particles may be coated with a metal such as Si as needed. For example, when combined with Cu or Ni alloy particles, which have higher conductivity than Sn, a bonded layer can be obtained that has good conductivity and suppresses volume change over a relatively wide temperature range.

[0030] The proportion of the metal particles in the sheet or conductive paste is, for example, 50% by mass or more, and preferably 70-80% by mass.

[0031] Furthermore, even if the alloy ingot of the present invention is not granulated, the joining conditions as a joining material are the same as described above.

[0032] Figure 7 is a schematic cross-sectional view illustrating a structure that can be joined using the alloy ingot of the present invention. The substrates 100 and 500 are substrates equipped with semiconductor elements and constitute electronic and electrical equipment such as power devices, while the metal / alloy bodies 101 and 501 are connecting members integrally provided on the substrates 100 and 500 as electrodes, bumps, terminals, or lead conductors. In electronic and electrical equipment such as power devices, the metal / alloy bodies 101 and 501 are generally composed of Cu or an alloy thereof. However, this does not exclude cases where the portion corresponding to the substrates 100 and 500 is composed of a metal / alloy body. [Examples]

[0033] The present invention will be further described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0034] Example 1 Using raw materials with a composition consisting of 8 mass% Cu, 5 mass% Sb, 0.1 mass% Ni, 0.001 mass% Ge, 0.001 mass% Si, 0.001 mass% Ti, and the remainder being Sn, high-frequency induction heating and cooling solidification were performed under the following conditions to form the alloy ingot 1 of the present invention. High-frequency induction heating: 9 × 10 -2 A high-frequency induction melting crucible was placed in a vacuum chamber capable of reducing the pressure to approximately Pa. The raw materials were introduced into the crucible, and high-frequency induction heating was performed on the raw materials while maintaining a reduced pressure of approximately Pa. The heating temperature was set to 650°C to melt the raw materials, and this temperature was maintained for 5 minutes. Cooling and solidification: Next, while circulating nitrogen gas at 15-50°C into the tank for 10 minutes, the raw material was heated to approximately 400°C under atmospheric pressure, cast into a mold, and then cooled and solidified at room temperature. The resulting alloy ingot 1 of the present invention was rectangular in shape, with a thickness of 2 cm, a length of 20 cm, and a width of 3 cm, and had a cross-section as shown in Figure 1. Elemental mapping analysis using EDS was performed on the alloy ingot, intermetallic compound crystal, and endotaxial joint shown in Figure 1. The analysis revealed that the composition of the alloy ingot is Cu 7.32 mass%, Sb 4.35 mass%, Ni 0.13 mass%, Ge 0.001 mass%, Si 0.001 mass%, Ti 0.001 mass%, and the remainder is Sn. Furthermore, the composition of the matrix phase was found to be Sn 85-99.9% by mass, Cu 5% or less by mass, and Sb, Bi, or Ga 0.1-14% by mass. Furthermore, the composition including the intermetallic compound crystal and the endotaxial junction portion is Sn 50~65% by mass, Cu 30~45% by mass, Sb 1~2.5% by mass, Ni 0.3~0.5% by mass, Ge 0.001% by mass, Si 0.001% by mass, Ti 0.001% by mass It was found that this was the case.

[0035] Figure 2 shows the TEM image and transmission electron diffraction pattern of the cross-section of the obtained alloy ingot 1. The transmission electron diffraction pattern in Figure 2 shows the state of the endotaxial junction. From the transmission electron diffraction pattern in Figure 2, it was confirmed that the Sn-Cu alloy in the matrix phase, represented by the light-colored areas, and the intermetallic compound crystals composed of Sn, Cu, Ni, Ge, Si, and Ti, represented by the dark-colored areas, are endotaxially bonded. It was also confirmed that there is no buffer layer between the crystals. Furthermore, it was confirmed that the lattice constants (and crystal orientations) are aligned between the Sn-Cu alloy in the matrix phase and the intermetallic compound, and that each crystal is continuously bonded at the crystal lattice level.

[0036] Comparative Example 1 The test was conducted based on the description of the example in Patent Document 3 (Japanese Patent Publication No. 6369620). The raw materials consisted of 8 mass% Cu, 1 mass% Ni, 0.001 mass% Ge, and the remainder Sn. The raw materials were melted in a melting furnace set to 450°C, and then the molten material was poured into the grooves of a rotating mold through which water was circulated. The cooling rate was approximately 30°C / s. An ultrasonic oscillator was attached to the rotating mold, and 60 kHz ultrasonic waves were applied when pouring the molten solder. The resulting alloy ingot of Comparative Example 1 is rectangular in shape, with a thickness of 2 cm, a length of 20 cm, and a width of 3 cm. Figure 3 is an SEM image of a cross-section of the alloy ingot of Comparative Example 1, which was embedded in resin and thinly cut. Figure 3(b) is a magnified view of a portion of Figure 3(a). Referring to Figure 3(a), the alloy ingot of Comparative Example 1 has intermetallic compound crystals 220 containing Sn, Cu, Ni, and Ge in a matrix phase 240 containing Sn and Sn-Cu alloy. However, as shown in Figure 3(b), fracture occurred at the interface between the matrix phase and the intermetallic compound crystals, and endotaxial bonding could not be confirmed.

[0037] Comparative Example 2 The test was conducted based on the method described in Patent Document 4 (International Publication WO2014 / 084242A1). Raw materials consisting of 8 mass% Cu, 1 mass% Ni, 0.001 mass% Ge, and the remainder Sn were used. After melting the raw materials, the molten material was poured into the grooves of a mold and cooled at room temperature. The resulting alloy ingot of Comparative Example 2 is rectangular in shape, with a thickness of 2 cm, a length of 20 cm, and a width of 3 cm. Figure 4 is an SEM image of a cross-section of the alloy ingot of Comparative Example 2, which was embedded in resin and thinly cut. Figure 4(b) is a magnified view of a portion of Figure 4(a). Referring to Figure 4(a), the alloy ingot of Comparative Example 2 has intermetallic compound crystals 320 containing Sn, Cu, Ni, and Ge in a matrix phase 340 containing Sn and Sn-Cu alloy. However, as shown in Figure 4(b), fracture occurred at the interface between the matrix phase and the intermetallic compound crystals, and endotaxial bonding could not be confirmed.

[0038] Example 2, Comparative Examples 3-4 Using the alloy ingots prepared in Example 1, Comparative Example 1, and Comparative Example 2, thin sheets with a thickness of 100 μm × 15 mm × 15 mm were created by pressure welding. A thin sheet and a copper foil measuring 300 μm × 30 mm × 30 mm thick were fired and bonded together in a formic acid atmosphere at 260°C to obtain a test specimen. The center of the laminated specimen was bent 190 degrees, and the crack state on the surface of the specimen was observed using an optical microscope. The results are shown in Figure 5. The results in Figure 5(a) show that the test specimens made using the alloy ingot prepared in Example 1 maintained their joints without fracture or cracking (reference numeral 701), indicating that they possess the flexibility to maintain continuous vibration operation characteristics. Furthermore, the results in Figure 5(b) show that the test specimen prepared using the alloy ingot created in Comparative Example 1 exhibited cracks on the 190-degree bent material surface (reference numeral 702). This indicates that it could not withstand the bending tensile force in the above test, leading to crack formation and a lack of flexibility to maintain continuous vibration operation characteristics. Furthermore, the results in Figure 5(c) show that the test specimen prepared using the alloy ingot created in Comparative Example 2 exhibited cracking on the 190-degree bent material surface (reference numeral 703). This indicates that it could not withstand the bending tensile force in the above test, leading to crack formation and a lack of flexibility to maintain continuous vibration operation characteristics.

[0039] Figure 6 is a diagram illustrating the 190-degree bending test. First, as shown in Figure 6(a), several jigs are prepared, and thin sheets made of copper foil and alloy ingots are placed in contact with the jigs. Here, the line extending horizontally from the bottom surface of the copper foil is called the "reference line". Next, as shown in Figure 6(b), a load is applied in the direction of the arrow via a jig, causing the copper foil to bend upward (this is called the compression direction). Next, as shown in Figure 6(c), when the copper foil has bent at an angle of 10 degrees in the compression direction with respect to the reference line (i.e., when the thin sheet has also bent in the same way), the load applied to the jig in the direction of the arrow is stopped. Next, as shown in Figure 6(d), the jig is moved, and the thin sheet and copper foil are folded in the opposite direction to the compression direction (called the stretching direction). In Figure 6(d), the angle in the stretching direction is approximately 90 degrees with respect to the reference line. Finally, as shown in Figure 6(e), the thin sheet and copper foil are further bent in the stretch direction, and the bending is continued until it reaches an angle of 180 degrees with respect to the reference line. In other words, the 190-degree bending test involves first bending a thin sheet 10 degrees in the compression direction, then returning it to the reference line, and then bending it 180 degrees in the elongation direction opposite to the compression direction. Therefore, it is called a 10-degree + 180-degree = 190-degree bending test. Furthermore, continuously bending the thin sheet in both the compression and elongation directions is equivalent to simulating the characteristics of a continuous vibration operation state. Since the sample in the above embodiment possesses flexibility that does not cause cracks, it can be determined that "the characteristics of a continuous vibration operation state can be maintained."

[0040] Although the present invention has been described in detail above with reference to the attached drawings, the present invention is not limited thereto, and it will be obvious to those skilled in the art that various modifications can be conceived based on the basic technical concept and teachings. [Explanation of Symbols]

[0041] 120,220,320 Intermetallic compounds 140,240,340 Mother phase 100,500 circuit boards 101,501 Alloy / Alloy Body

Claims

[Claim 1] (1) Sn (2) Sn-Cu alloy (3) Sb or Bi or Ga In the matrix phase including (1), (2) and (3) above, An alloy ingot for bonding materials having intermetallic compound crystals containing Sn, Cu, Ni, Ge, Si, and Ti, The composition of the alloy ingot for the joining material is 0.7 to 15 mass% Cu, 0.1 to 5 mass% Ni, 0.1 to 14 mass% Sb or Bi or Ga, 0.001 to 0.1 mass% Ge, 0.001 to 0.1 mass% Si, 0.001 to 0.1 mass% Ti, and the remainder being Sn (however, unavoidable impurities may be included in amounts of 0.1 mass% or less). The composition of the matrix phase is 85 to 99.9 mass% of Sn, 0.3 to 5 mass% of Cu, and 0.1 to 14 mass% of Sb, Bi, or Ga (wherein the matrix phase, the total of Sn, Cu, Sb, Bi, or Ga, and unavoidable impurities of 0.1 mass% or less is 100 mass%). At least a portion of the matrix phase and the intermetallic compound crystal are endotaxially bonded, The proportion of intermetallic compound crystals in the aforementioned alloy ingot for joining materials is 20 to 60% by mass. The proportion of the endotaxial junction is 30% or more, when the entire junction surface between the matrix phase and the intermetallic compound crystal is considered to be 100%. An alloy ingot for joining materials characterized by the following features.

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