Au-sn alloy, au-sn alloy powder, au-sn alloy paste, and au-sn alloy joining layer

Abstract

This Au-Sn alloy has an Sn content of 15.0–25.0 mass%, the remainder being Au and impurities, and an α-ray emission amount of no more than 0.010 cph / cm2. The amount of Cu, Pb, As, Sb, and Ag included as impurities is no more than 10 mass ppm each.

Description

Au—Sn alloy, Au—Sn alloy powder, Au—Sn alloy paste, and Au—Sn alloy bonding layer

[0001] The present invention relates to an Au—Sn alloy, an Au—Sn alloy powder, an Au—Sn alloy paste, and an Au—Sn alloy bonding layer. This application claims priority to Japanese Patent Application No. 2024-064183 filed on April 11, 2024, and Japanese Patent Application No. 2025-65628 filed on April 11, 2025, the contents of which are incorporated herein by reference.

[0002] Generally, various devices such as LEDs and power modules have a structure in which electronic components such as semiconductor elements are bonded to a circuit layer formed on a substrate. When bonding electronic components such as semiconductor elements to the circuit layer, a method using a solder material is widely used, as shown in Patent Document 1, for example. Conventionally, Sn—Pb alloy solder material, for example, has been widely used as the above-mentioned solder material.

[0003] In recent years, regulations on environmentally harmful chemical substances have become increasingly strict, and the use of Pb in solder materials has also been restricted. In response to this, lead-free solders such as Sn—Ag alloy solder materials and Sn—Ag—Cu alloy solder materials have been proposed, as shown in Patent Document 2, for example.

[0004] Recently, the heat resistance of semiconductor elements themselves has improved, and the amount of heat generated by semiconductor elements has increased due to the large currents that are loaded onto the semiconductor elements. Therefore, solder materials are required to have even higher heat resistance than before. However, lead-free solders such as the Sn—Ag alloy solder and Sn—Ag—Cu alloy solder have relatively low melting points (eutectic temperatures), and therefore have insufficient heat resistance.

[0005] Therefore, as a solder material with excellent heat resistance, for example, an Au—Sn alloy solder material is proposed in Patent Document 3. This Au—Sn alloy solder material has a higher melting point (eutectic temperature) than the above-mentioned Sn—Ag alloy solder material, Sn—Ag—Cu alloy solder material, etc., and has excellent heat resistance.

[0006] JP 2004-172378 A JP 2001-321982 A JP 2014-200794 A

[0007] Incidentally, it is known that in semiconductor devices equipped with semiconductor elements, alpha rays are emitted from the solder that constitutes the bonding layer, and these alpha rays may affect the semiconductor elements and cause soft errors. In particular, recent semiconductor devices, etc., have become increasingly dense, and the risk of soft errors occurring due to the influence of alpha rays from solder located near the semiconductor elements is increasing. Lead contains alpha rays, a radioactive nuclide that emits alpha rays. ２１０ Po and its parent nuclide ２１０ Since a small amount of Pb is contained, there is a risk that alpha rays may also be emitted from the Pb contained in the Sn-Pb alloy solder material.

[0008] Lead-free solder materials such as the above-mentioned Sn—Ag alloy solder material and Sn—Ag—Cu alloy solder material are primarily composed of Sn and do not contain Pb, and are therefore expected to have lower alpha-ray counts than Sn—Pb alloy solder materials. However, even these lead-free solders may not be able to sufficiently reduce the amount of alpha rays emitted, and studies are underway to reduce the amount of alpha rays emitted. On the other hand, no studies have been conducted on the alpha rays of the above-mentioned Au—Sn alloy solder material. Currently, general Au raw materials and Sn raw materials emit high amounts of alpha rays, and it is not easy to reduce the amount of alpha rays emitted by Au—Sn alloy solder materials.

[0009] The present invention has been made in view of the above-mentioned circumstances, and aims to provide an Au—Sn alloy, an Au—Sn alloy powder, an Au—Sn alloy paste, and an Au—Sn alloy bonding layer that have excellent heat resistance, low alpha ray emission, and excellent reliability.

[0010] In order to solve the above problems, the Au—Sn alloy of aspect 1 of the present invention has an Sn content in the range of 15.0 mass % to 25.0 mass % and the balance consisting of Au and impurities, and has an α-ray emission rate of 0.010 cph / cm ２ It is characterized by the following:

[0011] According to the Au—Sn alloy of the first aspect of the present invention, the Sn content is within the range of 15.0 mass % to 25.0 mass % and the remainder is composed of Au and impurities, so that the melting point is relatively high and the heat resistance is excellent. ２ Since the resistance is limited to the following value, it is possible to suppress the occurrence of soft errors in semiconductor devices and the like, resulting in excellent reliability.

[0012] The Au—Sn alloy of Aspect 2 of the present invention is characterized in that, in the Au—Sn alloy of Aspect 1 of the present invention, the contents of Cu, Pb, As, Sb, and Ag contained as the impurities are each limited to 10 mass ppm or less. According to the Au—Sn alloy of Aspect 2 of the present invention, the contents of Cu, Pb, As, Sb, and Ag contained as the impurities are each limited to 10 mass ppm or less, so that a decrease in strength due to ion migration or the formation of unintended intermetallic compounds does not occur, and the alloy has excellent reliability.

[0013] The Au—Sn alloy of Aspect 3 of the present invention is characterized in that the contents of Pb and Bi contained as impurities in the Au—Sn alloy of Aspect 1 or Aspect 2 of the present invention are each limited to less than 1 ppm by mass. According to the Au—Sn alloy of Aspect 3 of the present invention, the contents of Pb and Bi contained as impurities are each limited to less than 1 ppm by mass, which reduces the contents of Pb and Bi, which contain radioactive isotopes, and makes it possible to further reduce the possibility of soft errors in semiconductor devices and the like due to α-ray emission.

[0014] The Au—Sn alloy powder of Aspect 4 of the present invention is characterized by being made of the Au—Sn alloy of any one of Aspects 1 to 3 of the present invention. The Au—Sn alloy powder of Aspect 4 of the present invention is made of the Au—Sn alloy of any one of Aspects 1 to 3 of the present invention, and therefore has excellent heat resistance, sufficiently low alpha ray emission, can suppress the occurrence of soft errors in semiconductor elements and the like, and is therefore excellent in reliability.

[0015] The Au—Sn alloy paste of Aspect 5 of the present invention is characterized by containing the Au—Sn alloy powder of Aspect 4 of the present invention. Since the Au—Sn alloy paste of Aspect 5 of the present invention contains the Au—Sn alloy powder of Aspect 4 of the present invention, by applying and firing it, it is possible to obtain a molten solid of an Au—Sn alloy that has excellent heat resistance, emits sufficiently low α-rays, can suppress the occurrence of soft errors in semiconductor elements and the like, and is therefore highly reliable.

[0016] The Au—Sn alloy bonding layer of Aspect 6 of the present invention is an Au—Sn alloy bonding layer formed between a first member and a second member in a bonded body in which the first member and the second member are bonded, and is characterized in that it is made of a molten solidified product of the Au—Sn alloy paste of Aspect 5 of the present invention. The Au—Sn alloy paste of Aspect 6 of the present invention is made of a molten solidified product of the Au—Sn alloy paste of Aspect 5 of the present invention, and therefore has excellent heat resistance and a sufficiently low amount of alpha-ray emission, which can suppress the occurrence of soft errors in semiconductor elements and the like, and is therefore excellent in reliability.

[0017] According to the present invention, it is possible to provide an Au—Sn alloy, an Au—Sn alloy powder, an Au—Sn alloy paste, and an Au—Sn alloy bonding layer that have excellent heat resistance, low alpha ray emission, and excellent reliability.

[0018] 1 is an explanatory diagram of a bonded body having an Au—Sn alloy bonding layer according to one embodiment of the present invention; FIG. 2 is a phase diagram of an Au—Sn alloy; FIG. 3 is a flow chart of a method for producing an Au—Sn alloy powder according to the present embodiment; FIG. 4 is a flow chart of a method for producing the bonded body shown in FIG. 1; and FIG. 5 is an explanatory diagram of a method for producing the bonded body shown in FIG.

[0019] Hereinafter, an Au—Sn alloy, an Au—Sn alloy powder, an Au—Sn alloy paste, and an Au—Sn alloy bonding layer according to embodiments of the present invention will be described with reference to the accompanying drawings.

[0020] The Au—Sn alloy, Au—Sn alloy powder, and Au—Sn alloy paste according to this embodiment are used to manufacture a bonded body 10 by bonding a first member 11 and a second member 12, as shown in FIG. 1 . The Au—Sn alloy bonding layer 13 according to this embodiment is formed between the bonded first member 11 and second member 12. Here, in this embodiment, the bonded body 10 is a semiconductor device in which a circuit layer (first member 11) of an insulating circuit board and a semiconductor element (second member 12) are bonded via the Au—Sn alloy bonding layer 13.

[0021] The Au—Sn alloy of this embodiment has a Sn content in the range of 15.0 mass % to 25.0 mass % inclusive, with the remainder consisting of Au and impurities. The Sn content is preferably 19.0 mass % to 23.0 mass % inclusive. A phase diagram of the Au—Sn alloy is shown in FIG. 2. As shown in FIG. 2, the Au—Sn alloy is a eutectic alloy that undergoes a eutectic reaction, with a Sn content of approximately 20.0 mass % forming a eutectic composition, and its melting point is the eutectic temperature of 278°C.

[0022] In the Au—Sn alloy of this embodiment, the α-ray emission rate is 0.010 cph / cm ２ The amount of alpha rays emitted is 0.005 cph / cm ２ Preferably, it is 0.002 cph / cm or less. ２ The lower limit of the amount of α-ray emission is not particularly limited, but is preferably 0.0005 cph / cm ２ Here, the amount of α-ray emission from the Au—Sn alloy in this embodiment is measured at room temperature using a gas flow type α-ray measurement device manufactured by Alpha Science (MODEL-1950, lower limit of measurement: 0.0005 cph / cm ２ ) for 96 hours.

[0023] Here, in the Au—Sn alloy of this embodiment, the contents of Cu, Pb, As, Sb, and Ag contained as impurities are preferably 10 mass ppm or less. The contents of Cu, Pb, As, Sb, and Ag are more preferably 3 ppm or less. Furthermore, the lower limits of the contents of Cu, Pb, As, Sb, and Ag are not particularly limited, but may be 0.001 ppm. As described above, by specifying the contents of specific elements contained as impurities, the amount of α-ray emission can be sufficiently reduced, and various properties such as electrical conductivity, thermal conductivity, and strength can be stabilized.

[0024] In the Au—Sn alloy of this embodiment, the content of Pb and Bi contained as impurities is preferably less than 1 ppm by mass each. As described above, since the content of Pb and Bi contained as impurities is limited to less than 1 ppm by mass each, the content of Pb and Bi, which contain radioactive isotopes, is reduced, thereby further reducing the possibility of soft errors in semiconductor devices and the like due to α-ray emission. Furthermore, the lower limit of each of the Pb and Bi contents is not particularly limited, but may be 0.001 ppm.

[0025] The Au—Sn alloy powder of this embodiment is composed of the Au—Sn alloy of this embodiment. Here, the Au—Sn alloy powder of this embodiment is produced, for example, by gas atomizing a molten Au—Sn alloy. The average particle size (D50) of the Au—Sn alloy powder of this embodiment is preferably in the range of 5 μm to 30 μm. The particle size of the Au—Sn alloy powder can be obtained, for example, by measuring the projected area of ​​the Au—Sn alloy powder using a scanning electron microscope (SEM), calculating the equivalent circle diameter from the obtained projected area, and converting the calculated particle size to a volumetric particle size.

[0026] An example of the method for producing the Au—Sn alloy powder according to this embodiment will now be described with reference to the flow diagram of Fig. 3. In this embodiment, the Au—Sn alloy powder is produced by gas atomization.

[0027] (Melt raw material preparation step S01) First, a melt raw material for the gas atomization method is prepared. As the melt raw material, for example, the following (1) to (4) can be applied. (1) The alpha ray emission amount is measured in advance, and the alpha ray emission amount is 0.010 cph / cm ２ The following Au raw material and Sn raw material are selected and weighed so that the Sn content is within the range of 15.0 mass % to 25.0 mass %. The selection method may involve measuring each raw material lot, or cutting and dividing one lot and selecting the low-alpha-ray portion.

[0028] (2) The amount of alpha ray emission is measured in advance, and the amount of alpha ray emission is 0.010 cph / cm ２ The Au—Sn alloy ingot is obtained by selecting the following Au raw material and Sn raw material, weighing them so that the Sn content is within the range of 15.0 mass % to 25.0 mass %, and melting and casting them. The selection method may involve measuring each raw material lot, or cutting and dividing one lot and selecting the low-alpha-ray portion.

[0029] (3) The Au raw material and the Sn raw material are weighed so that the Sn content is in the range of 15.0 mass% or more and 25.0 mass% or less, and the Au—Sn alloy ingot obtained by melting and casting is divided, and the α-ray emission amount is measured for each divided block. ２ The following blocks are selected: In the case of an ingot whose surface layer has become highly alpha-ray emitting due to prolonged heating, the surface layer may be removed and an inner block with low alpha-ray emission may be selected.

[0030] (4) Au-Sn alloy ingots are produced by weighing out Au raw materials and Sn raw materials, melting them in the atmosphere to generate Sn oxides (dross), and then removing the dross to cast them. When Sn oxides (dross) are generated, the impurity Pb ​​is sublimated as PbO and removed, which makes it possible to reduce the amount of alpha ray emission. In addition to Pb, Bi is also easily oxidized, so Bi ２ O ３Therefore, compared to the above-mentioned methods, the method shown in (4) can further reduce the amount of Pb and Bi contained as impurities.

[0031] (Atomization step S02) The above-mentioned raw material is melted, for example, in a high-frequency melting furnace, and gas atomized to produce an Au—Sn alloy powder. There are no particular restrictions on the Au—Sn alloy powder, but the molten metal temperature is preferably in the range of 600° C. to 1000° C.

[0032] (Classification Step S03) If necessary, the obtained gas atomized powder is classified, for example, by sieving with a sieve, to obtain an Au—Sn alloy powder having a predetermined particle size distribution.

[0033] The Au—Sn alloy powder of this embodiment is produced by the melting raw material preparation step S01, the atomization step S02, and the classification step S03.

[0034] The Au—Sn alloy paste of this embodiment contains the Au—Sn alloy powder of this embodiment and a flux. Here, the flux contains one or more of a solvent, an activator, a plasticizer, and a resin. As the flux, for example, a general flux (e.g., a flux containing rosin, an activator, a solvent, and / or a thickener) can be used. Note that the viscosity of the Au—Sn alloy paste of this embodiment is preferably in the range of 20 Pa·s to 300 Pa·s.

[0035] Examples of the solvent that can be used include alcohols, ketones, esters, ethers, aromatic solvents, hydrocarbons, terpenes, and terpenoids. Specifically, benzyl alcohol, ethanol, ethyl alcohol, isopropyl alcohol, butanol, diethylene glycol, ethylene glycol, ethyl cellosolve, butyl cellosolve, butyl carbitol, isopropyl alcohol, ethyl acetate, butyl acetate, butyl benzoate, diethyl adipate, dodecane, tetradecene, α-terpineol, 2-methyl-2,4-pentanediol, 2-ethyl-1,3-hexanediol, toluene, xylene, propylene glycol monophenyl ether, diethylene glycol monohexyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, diisobutyl adipate, hexylene glycol, cyclohexanedimethanol, 2-terpinyloxyethanol, 2-dihydroterpinyloxyethanol, citral, linalool, limonene, carvacrol, pinene, farnesene, and the like are used alone or in combination of two or more of these.

[0036] Examples of plasticizers that can be used include hydrogenated castor oil, hydrogenated castor oil, carnauba wax, amides, hydroxy fatty acids, dibenzylidene sorbitol, bis(p-methylbenzylidene)sorbitols, beeswax, stearic acid amide, and hydroxystearic acid ethylene bisamide, either alone or in combination. Examples of surfactants that can be used include one or more selected from fatty acids such as adipic acid, caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, and behenic acid, hydroxy fatty acids such as 1,2-hydroxystearic acid, antioxidants, surfactants, and amines. Examples of resins that can be used include one or more selected from polymerized rosin, natural rosin, and purified rosin.

[0037] The Au—Sn alloy paste of this embodiment is produced by kneading the above-mentioned flux with the Au—Sn alloy powder of this embodiment. There are no particular limitations on the kneading method, and manual stirring or a kneading device such as a three-roll mill may be used as appropriate.

[0038] Next, a method for manufacturing the bonded body 10 shown in FIG. 1 (the bonded body 10 having the Au—Sn alloy bonding layer 13 of this embodiment) using the Au—Sn alloy paste of this embodiment will be described with reference to FIGS. 4 and 5.

[0039] 5, the Au—Sn alloy paste 23 of the present embodiment is applied to the bonding surface of the first member 11 with the second member 12. The Au—Sn alloy paste 23 of the present embodiment may be applied to one or both of the bonding surface of the first member 11 and the bonding surface of the second member 12. The application method is not particularly limited, and examples of applicable methods include a metal mask method, a screen printing method, and a dispensing method.

[0040] (Laminating Step S12) Next, as shown in FIG. 5, the first member 11 and the second member 12 are laminated together with the Au—Sn alloy paste 23 interposed therebetween.

[0041] (Joining step S13) Next, as shown in FIG. 5, the first member 11 and the second member 12 stacked with the Au—Sn alloy paste 23 interposed therebetween are heat-treated to melt the Au—Sn alloy paste 23 to generate a liquid phase, and then the liquid phase is solidified to form an Au—Sn alloy bonding layer 13 made of a molten solid of the Au—Sn alloy paste 23, thereby joining the first member 11 and the second member 12.

[0042] The holding temperature in the bonding step S13 is preferably within a range of the melting point of the Au—Sn alloy paste 23 +5° C. to the melting point +20° C. Furthermore, the holding time at the holding temperature is preferably within a range of 1 second to 30 minutes. In addition, in the bonding step S13, a pressure of 0.1 MPa to 10 MPa in the stacking direction may be applied. Furthermore, the atmosphere in the bonding step S13 may be Ar or N ２ It is preferable to select an appropriate atmosphere depending on the flux contained, such as an inert gas atmosphere or a reducing atmosphere containing formic acid or hydrogen.

[0043] The bonded body 10 shown in FIG. 1 is manufactured by the paste application step S11, the lamination step S12, and the bonding step S13 described above.

[0044] The Au—Sn alloy, Au—Sn alloy powder, Au—Sn alloy paste, and Au—Sn alloy bonding layer 13 of this embodiment configured as described above have a Sn content in the range of 15.0 mass % to 25.0 mass % with the remainder being composed of Au and impurities, and therefore have a relatively high melting point and excellent heat resistance. Furthermore, the α-ray emission rate is 0.010 cph / cm ２ Since the resistance is limited to the following value, it is possible to suppress the occurrence of soft errors in semiconductor devices and the like, resulting in excellent reliability.

[0045] Furthermore, in this embodiment, when the content of each of Cu, Pb, As, Sb, and Ag contained as impurities is 10 mass ppm or less, various characteristics are stable and reliability is excellent.

[0046] Furthermore, in this embodiment, when the contents of Pb and Bi contained as the impurities are each less than 1 mass ppm, the occurrence of soft errors in semiconductor elements and the like can be suppressed, and the impurities can be further reduced.

[0047] Although the present invention has been described above as an embodiment, it is not limited thereto and can be modified as appropriate within the scope of the technical concept of the invention. In this embodiment, the Au—Sn alloy powder is produced by gas atomization, but it is not limited thereto and may be produced by other powdering techniques such as pulverization or wet synthesis.

[0048] The results of experiments conducted to confirm the effectiveness of the present invention are described below. The alpha dose of the Au raw material and the Sn raw material used was measured in advance, and the alpha dose was 0.010 cph / cm ２ and 0.010 cph / cm ２ We used products that had undergone a selection process to separate those that exceeded the standard.

[0049] (Examples 1-3, Example 7, Comparative Examples 1-3) The Au raw material and the Sn raw material with the alpha dose and impurity amount shown in Table 1 were weighed so as to have the Sn content shown in Table 1, and these were used as melted raw materials and gas atomized to produce Au—Sn alloy powder.

[0050] (Example 4, Comparative Example 4) Au raw materials and Sn raw materials with α-ray doses and impurity amounts shown in Table 1 were weighed to obtain the Sn contents shown in Table 1, and then melted and cast to produce Au—Sn alloy ingots. Gas atomization was carried out using this Au—Sn alloy ingot as a melting raw material to produce Au—Sn alloy powder.

[0051] (Example 5) The Au raw material and Sn raw material with the α-ray dose and impurity amounts shown in Table 1 are conventional general products for which no consideration has been given to reducing the α-ray emission dose. These were weighed to have the Sn content shown in Table 1, and then melted and cast to produce an Au—Sn alloy ingot. This Au—Sn alloy ingot was divided into six blocks, and the α-ray emission dose of each block was measured. The α-ray emission dose was found to be 0.010 cph / cm ２ The following selected blocks were used as melted raw materials and gas atomized to produce Au—Sn alloy powder.

[0052] (Example 6) The Au raw material and Sn raw material with the α-ray dose and impurity amounts shown in Table 1 are conventional general products for which no consideration has been given to reducing the amount of α-ray emission. These were weighed to have the Sn content shown in Table 1, and then melted and cast to produce an Au—Sn alloy ingot. At this time, Sn oxide (dross) was generated by melting in air, and this Sn oxide (dross) was removed to produce an Au—Sn alloy ingot. This Au—Sn alloy ingot was used as a melting raw material and gas atomized to produce an Au—Sn alloy powder.

[0053] The Au—Sn alloy powder obtained as described above was mixed with a commercially available mildly activated rosin base (RMA) flux to obtain an Au—Sn alloy paste, with the Au—Sn alloy powder content being 93% by mass and the flux content being 7% by mass.

[0054] A copper substrate (2 mm thick) with a gold-plated bonding surface and a 1 mm square Si element (400 μm thick) with a gold-plated bonding surface were prepared. The above-mentioned Au—Sn alloy paste was applied to the surface of the copper substrate using a metal mask method to form a paste layer with a thickness of 50 μm and an area of ​​φ1 mm. Next, the Si element was stacked on this paste layer, and the assembly was placed in a heating furnace with a nitrogen atmosphere and held at 300°C for 1 minute to produce a bonded assembly in which the copper substrate and Si element were bonded via an Au—Sn alloy bonding layer. The impurity concentration and α-ray emission of the resulting Au—Sn alloy bonding layer were then measured. The measurement results are shown in Table 1.

[0055] The amount of alpha-ray emission was measured at room temperature using a gas flow type alpha-ray measuring device manufactured by Alpha Science (Model 1950, lower limit of measurement: 0.0005 cph / cm ２ ) for 96 hours.

[0056] The amount of impurities was determined by dissolving the sample in aqua regia and analyzing the resulting solution with an ICP (plasma emission spectrometer, lower limit of quantification: 1 mass ppm).

[0057] The bond strength of the resulting bonded structure was measured using a shear strength evaluation tester (TryPrecision Bond Tester MFM1500HF). The copper substrate of the bonded structure was fixed horizontally, and a shear tool was used to press the Si element horizontally from the side at a position 100 μm above the surface of the bonding layer, measuring the strength at which the Si element broke. The shear tool movement speed was 0.1 mm / s. Three tests were performed for each condition, and the arithmetic average of these values ​​was used as the measured value. A bond strength of 50 MPa or more was rated "A," and a bond strength of less than 50 MPa was rated "B."

[0058]

[0059] In Comparative Example 1, the alpha ray emission rate of the Au—Sn alloy bonding layer was 0.010 cph / cm ２In Comparative Example 2, the Sn content was as high as 30 mass %, and an Au—Sn alloy bonding layer could not be formed. In Comparative Example 3, the Sn content was as low as 10 mass %, and an Au—Sn alloy bonding layer could not be formed. In Comparative Example 4, the alpha ray emission from the Au—Sn alloy bonding layer was 0.010 cph / cm ２ It exceeded that.

[0060] In contrast, in Examples 1 to 7, the Au—Sn alloy bonding layer was stably formed, and the α-ray emission rate of the Au—Sn alloy bonding layer was 0.010 cph / cm ２ It was confirmed that the occurrence of soft errors in semiconductor elements can be suppressed.

[0061] In particular, in Example 6, it was confirmed that as a result of removing Sn oxides (dross), Pb and Bi were also removed as oxides, resulting in a further reduction in impurities.

[0062] From the above, it has been confirmed that the present invention can provide an Au—Sn alloy, Au—Sn alloy powder, Au—Sn alloy paste, and Au—Sn alloy bonding layer that have excellent heat resistance, low alpha ray emission, and excellent reliability.

[0063] 10 Bonded body 11 First member 12 Second member 13 Au—Sn alloy bonding layer

Claims

1. The Sn content is within the range of 15.0 mass% or more and 25.0 mass% or less, with the remainder consisting of Au and impurities, and the alpha ray emission rate is 0.010 cph / cm ２ An Au—Sn alloy characterized by:

2. The Au-Sn alloy according to claim 1, characterized in that the content of Cu, Pb, As, Sb, and Ag contained as impurities is each 10 mass ppm or less.

3. The Au-Sn alloy according to claim 1, wherein the content of Pb and Bi contained as impurities is each less than 1 ppm by mass.

4. The Au-Sn alloy according to claim 2, wherein the content of Pb and Bi contained as impurities is each less than 1 ppm by mass.

5. Au-Sn alloy powder characterized by comprising the Au-Sn alloy according to any one of claims 1 to 4.

6. A Au-Sn alloy paste containing the Au-Sn alloy powder according to claim 5.

7. An Au-Sn alloy bonding layer formed between a first member and a second member in a bonded structure in which the first member and the second member are bonded, characterized in that the Au-Sn alloy bonding layer is made of a molten solid of the Au-Sn alloy paste according to claim 6.

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