Lead-free solder

Abstract

To provide a lead-free solder more excellent in creep characteristic.SOLUTION: An objective lead-free solder includes indium of 93.0-98.95 mass%, tin of 1.0-4.0 mass% and an added metal which is at least one among silver, antimony, copper and nickel different from indium and tin. The total mass% of the added metal is 0.05 or more and 6.0 or less, and the sum of the above total mass%, the mass% of indium and that of tin is 100 mass% or less.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to lead-free solder.

Background Art

[0002] Patent Document 1 discloses a lead-free solder. This lead-free solder contains about 4% by mass to about 25% by mass of tin, about 0.1% by mass to about 8% by mass of antimony, about 0.03% by mass to about 4% by mass of copper, about 0.03% by mass to about 4% by mass of nickel, about 66% by mass to about 90% by mass of indium, and about 0.5% by mass to about 9% by mass of silver. According to the invention disclosed in Patent Document 1, it is suitable for use on glass and can withstand use in a high-temperature environment.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, there is room for improvement in the creep characteristics of the lead-free solder disclosed in Patent Document 1. The present invention solves such problems. Its object is to provide a lead-free solder having more excellent creep characteristics.

Means for Solving the Problems

[0005] As a result of earnestly studying the above-described problems, the inventors of the present invention have found that a lead-free solder having excellent creep characteristics can be obtained when the amount of a predetermined metal added to indium is limited so as to satisfy certain requirements, and have completed the present invention. That is, the present invention is as follows.

[0006] In order to solve the above-described problems, according to an aspect of the present invention, the lead-free solder is 93.5% by mass or more 96.5 indium of % by mass or less, tin of 1.0% by mass or more and 4.0% by mass or less, and the total of the % by mass is 1.1 % by mass Exceeding 5.5 additive metals of % by mass or less and Consisting of . The additive metals are Of more than 1.0% by mass and not more than 3.0% by mass silver,[[]] Of 0.1% by mass or more and 1.0% by mass or less antimony, copper, and at least Silver and antimony nickel, which are metals different from indium and tin and contain them. The sum of the total of the % by mass of the additive metals, the % by mass of indium, and the % by mass of tin is 100% by mass % .

[0007]

[0008] In addition, it is desirable that the above-mentioned lead-free solder contains 0.05% by mass or more and 6.0% by mass or less of copper as part of the additive metals.[[]]

[0009]

[0010]

Advantages of the Invention

[0011] According to the present invention, a lead-free solder with further excellent creep characteristics is provided.[[]]

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be described.

[0014] 〈Explanation of the Components of Lead-Free Solder〉 The lead-free solder according to the present invention contains indium, tin, and an additive metal Consisting of . The mass percentage of indium in the lead-free solder according to the present invention is 93.5 mass% or more 96.5 mass% or less. The mass percentage of tin in the lead-free solder according to the present invention is 1.0 mass% or more 4 .0 mass% or less. The total mass percentage of the additive metal in the lead-free solder according to the present invention is 1.1 mass% Exceeding 5.5 mass% or less. In the lead-free solder according to the present invention, the sum of the total mass percentage of the additive metal, the mass percentage of indium, and the mass percentage of tin is 100 mass % There is.

[0015] The additive metal is a metal containing at least Silver and antimony among silver, antimony, copper, and nickel. The additive metal is a metal different from indium and tin. Except for the fact that at least Silver and antimony among silver, antimony, copper, and nickel is included and it is a metal different from indium and tin, the types of metals contained in the additive metal are not particularly limited. Therefore, the additive metal may be As long as silver and antimony are included silver, antimony, copper, And nickel Of the loop selected from the group consisting of any combination. In this case, the total mass percentage of the additive metal is 1.1 mass% Exceeding 5.5 mass% Below becomes. Each of the metals contained in the additive metal becomes a component of the lead-free solder according to the present invention. Therefore, in the lead-free solder according to the present invention, the total mass percentage of metals different from indium and tin is 1.1 mass% Exceeding 5.5 mass% or less.

[0016] On the premise that at least one of silver, antimony, copper, and nickel is included and the metal contained in the additive metal is different from indium and tin, the metal contained in the additive metal may be only a metal having predetermined characteristics. Examples of such "predetermined characteristics" include being a transition metal, being a noble metal, being a base metal, forming a crystal lattice belonging to a predetermined crystal system, having a close-packed structure, and forming twins. Examples of the predetermined crystal system include triclinic, monoclinic, orthorhombic, tetragonal, hexagonal, and cubic crystals. Silver and antimony

[0017] The lead-free solder according to the present invention contains antimony as part of the additive metal in an amount of 0.1 mass% or more 1.0 and 1 mass% or less. No The lead-free solder according to the present invention preferably contains copper as part of the additive metal in an amount of 0.05 mass% or more 4.4 and 1 mass%. Less than The lead-free solder according to the present invention preferably contains nickel as part of the additive metal in an amount of 0.05 mass% or more 4.4 and 1 mass% or less. The lead-free solder according to the present invention contains silver as part of the additive metal in an amount exceeding 1.0 mass% 3.0 and 1 mass% or less. No

[0018] The mass% of indium in the lead-free solder according to the present invention is 93.5 mass% or more and 96.5 mass% or less. Yes

[0019] <Explanation of manufacturing method> The manufacturing method of the lead-free solder according to the present invention is not particularly limited. For example, the lead-free solder according to the present invention is manufactured by melting ingots of indium, ingots of tin, and an additive metal in a crucible. The additive metal is at least one of silver, antimony, copper, and nickel. Silver and antimonyThe lead-free solder containing it may be melted in a crucible, or the ingots of each metal to be contained in the additive metal may be melted in the crucible. Instead of the ingots, metal powder may be melted. It is desirable that the purity of the indium ingot, the purity of the tin ingot, and the purity of the ingots of each metal to be contained in the additive metal be as high as possible. For example, it is desirable that the purity of these ingots be 99% or more in all cases.

[0020] <Description of Embodiments> Examples of the present invention will be described below, but the present invention is not limited to the following examples.

[0021] Reference Example 1 (Preparation of Lead-Free Solder Ingot) First, the operator put 98.0 grams of indium, 1.0 gram of tin, and 1.0 gram of silver into a crucible. When these metals were put into the crucible, the operator placed the crucible on a gas stove and heated it for 10 minutes. The molten metal temperature was 400 degrees Celsius (673.15 Kelvin). As a result, these metals became an alloy. Then, the operator poured the molten metal (molten alloy) in the crucible into a mold. The mold into which the molten metal was poured was air-cooled. As a result, the alloy in the mold was also air-cooled. When the alloy in the mold reached room temperature, the operator took out the alloy from the mold. This alloy is the Reference lead-free solder ingot according to this example. Samples for the following tests are prepared from this ingot.

[0022] (High-Temperature Creep Test) First, the operator Reference ​A test piece was made from the lead-free solder ingot according to the example. The total length of the test piece was 130 millimeters. Both ends of the test piece were thick and the central part was thin. Male threads were formed at both ends of the test piece. The nominal diameter of the male threads was M18 defined in JIS (Japanese Industrial Standard) B0205. The cross-sectional shape of the central part of the test piece was circular, and its outer diameter was 10 millimeters. The length of the central part of the test piece, and thus the gauge length, was 70 millimeters. A curved surface with a radius of curvature of 15 millimeters was formed at the boundary between the central part and both ends of the test piece. The operator attached the test piece to a triple creep testing machine (model number: YCR-250) manufactured by Yonekura Seisakusho Co., Ltd. and applied a load of 0.24 newtons. The operator measured the time from when the load was applied to the test piece until the test piece broke. The temperature of the test piece was maintained at 120 degrees Celsius (393.15 Kelvin) while the load was applied. This Reference The test piece according to the example had not broken at the time when 600 hours had elapsed since the load was applied. Therefore, the operator terminated this test.

[0023] (Joint Strength Test at Room Temperature for Silver Electrodes) First, the operator placed the lead-free solder according to this example, which was 2 millimeters × 3 millimeters × 0.4 millimeters thick, on the silver electrode (dimensions: 2.5 millimeters × 10 millimeters) formed on the ceramic substrate (dimensions: 11 millimeters × 11 millimeters). When the lead-free solder was placed, the operator applied a rosin-based flux (manufacturer: Uchibashi Estec Co., Ltd., model number: NUR-813). When the flux was applied, the operator placed a copper wire with a length of 40 millimeters and a diameter of 0.55 millimeters. When the copper wire was placed, the operator soldered the copper wire to the electrode by applying a soldering iron to the tip 3 millimeters of the copper wire. This is the ReferenceThis is the bonding strength test piece according to the example. When the bonding strength test piece was created, the operator placed a weight on the ceramic substrate of the bonding strength test piece. As a result, the ceramic substrate was fixed so as not to float. After the ceramic substrate was fixed, the operator pulled up the copper wire of the bonding strength test piece via a pull gauge (manufacturer: Aiko Engineering Co., Ltd., model number: AWF-30N). The operator measured the maximum value of the load indicated by the pull gauge from the start of the pulling until the lead-free solder used for soldering broke. In the case of this Reference example, the load was 9.2 newtons.

[0024] (Bonding Strength Test at High Temperature for Silver Electrodes) First, the operator created a bonding strength test piece in the same manner as in the "Bonding Strength Test at Room Temperature for Silver Electrodes". When the bonding strength test piece was created, the operator placed the bonding strength test piece on a hot plate (manufacturer: CORNING, model number: PC-400) where the temperature of the heating plate (the plate on which the object to be heated is placed and heated) was maintained at 120 degrees Celsius (393.15 Kelvin) and left it for 3 minutes. After leaving it for 3 minutes, the operator placed a weight on the ceramic substrate of the bonding strength test piece. As a result, the ceramic substrate was fixed on the hot plate so as not to float. After the ceramic substrate was fixed, the operator pulled up the copper wire of the bonding strength test piece via a pull gauge (manufacturer: Aiko Engineering Co., Ltd., model number: AWF-30N). The operator measured the maximum value of the load indicated by the pull gauge from the start of the pulling until the lead-free solder used for soldering broke. In the case of this example, the load was 4.7 newtons.

[0025] (Resistivity Test) First, the operator, this ReferenceTest pieces were prepared from the lead-free solder ingots according to the example. The test pieces were wires with a diameter of 2 millimeters (0.2 centimeters). Next, the operator measured the electrical resistance between two points (distance: 100 millimeters) of the wire using a milliohm high tester (model number: 3224) manufactured by Hioki E.E. Corporation. Once the electrical resistance was measured, the operator calculated the resistivity of the lead-free solder according to the formula described below Reference in the example. ρ = R × S ÷ L In the above formula, ρ is the resistivity. Its unit is microohm·centimeter. R is the measured electrical resistance. Its unit is microohm. S is the cross-sectional area of the wire. Its unit is square centimeter. L is the distance between the two points where the electrical resistance was measured. Its unit is centimeter. In the case of this Reference example, the resistivity was 10.0 microohm·centimeter.

[0026] (Measurement of solid phase temperature and liquid phase temperature) The operator measured the solid phase temperature and liquid phase temperature of the lead-free solder according to the example using a differential scanning calorimeter (manufacturer: Rigaku Corporation, model number: DSC8231). The measurement was carried out in air. The temperature increase rate during those measurements was 5 degrees Celsius (5 Kelvin) per minute. The mass of the sample used for the measurement was 15 milligrams. The sample was placed in an aluminum container and measured. The temperature measurement cycle was 1 second. The reference substance was air in an aluminum container of the same type as the sample. That is, by comparing the sample in the container with the air in the empty container, the heat absorption and heat release associated with the phase transition and the temperatures (solid phase temperature and liquid phase temperature) at which they occurred were measured. In the case of this Reference example, the solid phase temperature was 145 degrees Celsius (418.15 Kelvin). In the case of this Reference example, the liquid phase temperature was 152 degrees Celsius (425.15 Kelvin). Reference

[0027] [Example 1 (Preparation of lead-free solder) ​​First, the operator put 96.5 grams of indium, 1.0 gram of tin, 1.5 grams of silver, and 1.0 gram of antimony into a crucible. Then, Reference Following the same procedure as the lead-free solder ingot according to Example 1, a lead-free solder ingot according to this example was prepared.

[0028] (High-temperature creep test) The operator Reference Conducted a high-temperature creep test according to the same procedure as in Example 1. The test piece according to this example also did not break when 600 hours had elapsed since the load was applied. Therefore, the operator ended this test.

[0029] (Room-temperature joint strength test for silver electrodes) The operator Reference Conducted a room-temperature joint strength test for silver electrodes according to the same procedure as in Example 1. In the case of the joint strength test according to this example, the maximum value of the load indicated by the pull gauge was 12.3 Newtons between the start of pulling the copper wire of the joint strength test piece and the breakage of the lead-free solder used for soldering.

[0030] (High-temperature joint strength test for silver electrodes) The operator Reference Conducted a high-temperature joint strength test for silver electrodes according to the same procedure as in Example 1. In the case of the joint strength test according to this example, the maximum value of the load indicated by the pull gauge was 5.8 Newtons between the start of pulling the copper wire of the joint strength test piece and the breakage of the lead-free solder used for soldering.

[0031] (Resistivity test) The operator Reference Measured the resistivity according to the same procedure as in Example 1. The resistivity of the lead-free solder according to this example was 10.9 microohm·centimeter.

[0032] (Measurement of solidus temperature and liquidus temperature) The operator ReferenceIn the same procedure as in Example 1, the solid-phase temperature and the liquid-phase temperature were measured. The solid-phase temperature of the lead-free solder according to this example was 142 degrees Celsius (415.15 Kelvin). The liquid-phase temperature of the lead-free solder according to this example was 148 degrees Celsius (421.15 Kelvin).

[0033] Reference Example 2 (Preparation of Lead-Free Solder) First, the operator put 96.5 grams of indium, 1.0 gram of tin, 1.5 grams of silver, and 1.0 gram of copper into a crucible. Then, Reference through the same procedure as the lead-free solder ingot according to Example 1, the lead-free solder ingot according to this Reference example was prepared.

[0034] (High-Temperature Creep Test) The operator Reference performed a high-temperature creep test in the same procedure as in Example 1. The test piece according to this Reference example also did not break when 600 hours had elapsed since the load was applied. Therefore, the operator ended this test.

[0035] (Room-Temperature Bonding Strength Test for Silver Electrodes) The operator Reference performed a room-temperature bonding strength test for silver electrodes in the same procedure as in Example 1. In the case of the bonding strength test according to this Reference example, the maximum value of the load indicated by the pull gauge was 7.9 Newtons from the start of pulling the copper wire of the bonding strength test piece until the lead-free solder used for soldering broke.

[0036] (High-Temperature Bonding Strength Test for Silver Electrodes) The operator Reference performed a high-temperature bonding strength test for silver electrodes in the same procedure as in Example 1. In the case of the bonding strength test according to this Reference example, the maximum value of the load indicated by the pull gauge was 6.3 Newtons from the start of pulling the copper wire of the bonding strength test piece until the lead-free solder used for soldering broke.​​

[0037] (Specific Resistance Test) The operator Reference measured the specific resistance according to the same procedure as in Example 1. The specific resistance of the lead-free solder according to this Reference example was 9.9 microohm·centimeter.

[0038] (Measurement of Solid Phase Temperature and Liquid Phase Temperature) The operator Reference measured the solid phase temperature and the liquid phase temperature according to the same procedure as in Example 1. The solid phase temperature of the lead-free solder according to this Reference example was 145 degrees Celsius (418.15 Kelvin). The Reference liquid phase temperature of the lead-free solder according to this example was 151 degrees Celsius (424.15 Kelvin).

[0039] [Example 2 (Preparation of Lead-Free Solder) First, the operator put 93.5 grams of indium, 3.0 grams of tin, 1.5 grams of silver, 1.0 gram of antimony, and 1.0 gram of copper into a crucible. Then, Reference through the same procedure as the lead-free solder ingot according to Example 1, the lead-free solder ingot according to this example was prepared.

[0040] (High-Temperature Creep Test) The operator Reference performed a high-temperature creep test according to the same procedure as in Example 1. The test piece according to this example also did not break when 600 hours had elapsed since the load was applied. Therefore, the operator ended this test.

[0041] (Room Temperature Joint Strength Test for Silver Electrodes) The operator Reference ​In the same procedure as in Example 1, a joining strength test at room temperature for the silver electrode was conducted. In the case of the joining strength test according to this example, the maximum value of the load indicated by the pull gauge from the start of pulling up the copper wire of the joining strength test piece until the breakage of the lead-free solder used for soldering was 10.2 Newtons.

[0042] (Joining Strength Test at High Temperature for Silver Electrode) The operator Reference In the same procedure as in Example 1, a joining strength test at high temperature for the silver electrode was conducted. In the case of the joining strength test according to this example, the maximum value of the load indicated by the pull gauge from the start of pulling up the copper wire of the joining strength test piece until the breakage of the lead-free solder used for soldering was 5.9 Newtons.

[0043] (Specific Resistance Test) The operator Reference Measured the specific resistance in the same procedure as in Example 1. The specific resistance of the lead-free solder according to this example was 11.9 microohm·centimeter.

[0044] (Measurement of Solidus Temperature and Liquidus Temperature) The operator Reference Measured the solidus temperature and liquidus temperature in the same procedure as in Example 1. The solidus temperature of the lead-free solder according to this example was 143 degrees Celsius (416.15 Kelvin). The liquidus temperature of the lead-free solder according to this example was 149 degrees Celsius (422.15 Kelvin).

[0045] [Example 3 (Preparation of Lead-Free Solder) First, the operator put 94.0 grams of indium, 1.0 gram of tin, 3.0 grams of silver, 1.0 gram of antimony, and 1.0 gram of copper into a crucible. Then, Reference The lead-free solder ingot according to this example was prepared through the same procedure as the lead-free solder ingot according to Example 1.

[0046] (High-Temperature Creep Test) The operator​Reference The high-temperature creep test was conducted according to the same procedure as in Example 1. The test piece according to this example also did not break when 600 hours had elapsed since the load was applied. Therefore, the operator terminated this test.

[0047] (Room-temperature Bonding Strength Test for Silver Electrodes) The operator Reference conducted a room-temperature bonding strength test for silver electrodes according to the same procedure as in Example 1. In the case of the bonding strength test according to this example, the maximum value of the load indicated by the pull gauge was 8.8 N from the start of pulling up the copper wire of the bonding strength test piece until the breakage of the lead-free solder used for soldering.

[0048] (High-temperature Bonding Strength Test for Silver Electrodes) The operator Reference conducted a high-temperature bonding strength test for silver electrodes according to the same procedure as in Example 1. In the case of the bonding strength test according to this example, the maximum value of the load indicated by the pull gauge was 6.7 N from the start of pulling up the copper wire of the bonding strength test piece until the breakage of the lead-free solder used for soldering.

[0049] (Specific Resistance Test) The operator Reference measured the specific resistance according to the same procedure as in Example 1. The specific resistance of the lead-free solder according to this example was 11.8 microohm·centimeter.

[0050] (Measurement of Solidus Temperature and Liquidus Temperature) The operator Reference measured the solidus temperature and the liquidus temperature according to the same procedure as in Example 1. The solidus temperature of the lead-free solder according to this example was 144 degrees Celsius (417.15 Kelvin). The liquidus temperature of the lead-free solder according to this example was 149 degrees Celsius (422.15 Kelvin).

[0051] [Example 4 (Preparation of Lead-free Solder) ​First, the operator put 93.9 grams of indium, 1.0 gram of tin, 3.0 grams of silver, 1.0 gram of antimony, 1.0 gram of copper, and 0.1 gram of nickel into a crucible. Then, Reference Following the same procedure as the lead-free solder ingot according to Example 1, a lead-free solder ingot according to this example was prepared.

[0052] (High-temperature creep test) The operator Reference Conducted a high-temperature creep test according to the same procedure as in Example 1. The test piece according to this example also did not break when 600 hours had elapsed since the load was applied. Therefore, the operator ended this test.

[0053] (Room-temperature joint strength test for silver electrodes) The operator Reference Conducted a room-temperature joint strength test for silver electrodes according to the same procedure as in Example 1. In the case of the joint strength test according to this example, the maximum value of the load indicated by the pull gauge from the start of pulling up the copper wire of the joint strength test piece to the breakage of the lead-free solder used for soldering was 10.3 newtons.

[0054] (High-temperature joint strength test for silver electrodes) The operator Reference Conducted a high-temperature joint strength test for silver electrodes according to the same procedure as in Example 1. In the case of the joint strength test according to this example, the maximum value of the load indicated by the pull gauge from the start of pulling up the copper wire of the joint strength test piece to the breakage of the lead-free solder used for soldering was 6.4 newtons.

[0055] (Specific resistance test) The operator Reference Measured the specific resistance according to the same procedure as in Example 1. The specific resistance of the lead-free solder according to this example was 11.7 microohm·centimeter.

[0056] (Measurement of solidus temperature and liquidus temperature) The operator ReferenceThe solid-phase temperature and the liquid-phase temperature were measured by the same procedure as in Example 1. The solid-phase temperature of the lead-free solder according to this example was 143 degrees Celsius (416.15 Kelvin). The liquid-phase temperature of the lead-free solder according to this example was 148 degrees Celsius (421.15 Kelvin).

[0057] [Comparative Example 1] (Preparation of Lead-Free Solder) First, the operator put 70.0 grams of indium, 29.0 grams of tin, and 1.0 gram of silver into a crucible. Then, Reference a lead-free solder ingot according to this comparative example was prepared through the same procedure as the lead-free solder ingot according to Example 1.

[0058] (High-Temperature Creep Test) The operator Reference performed a high-temperature creep test by the same procedure as in Example 1. The test piece according to this comparative example broke within slightly less than 90 hours, that is, before 100 hours had elapsed since the load was applied to it.

[0059] (Room-Temperature Bonding Strength Test for Silver Electrodes) The operator Reference performed a room-temperature bonding strength test for silver electrodes by the same procedure as in Example 1. In the case of the bonding strength test according to this comparative example, the maximum value of the load indicated by the pull gauge from the start of pulling up the copper wire of the bonding strength test piece until the breakage of the lead-free solder used for soldering was 9.0 Newtons.

[0060] (High-Temperature Bonding Strength Test for Silver Electrodes) The operator Reference performed a high-temperature bonding strength test for silver electrodes by the same procedure as in Example 1. In the case of the bonding strength test according to this comparative example, the maximum value of the load indicated by the pull gauge from the start of pulling up the copper wire of the bonding strength test piece until the breakage of the lead-free solder used for soldering was 2.8 Newtons.

[0061] (Resistivity Test) The operator ReferenceThe resistivity was measured in the same procedure as in Example 1. The resistivity of the lead-free solder according to this comparative example was 17.3 microohm·centimeter.

[0062] (Measurement of solid-phase temperature and liquid-phase temperature) The operator Reference measured the solid-phase temperature and the liquid-phase temperature in the same procedure as in Example 1. The Comparison solid-phase temperature of the lead-free solder according to this example was 121 degrees Celsius (394.15 Kelvin). The Comparison liquid-phase temperature of the lead-free solder according to this example was 127 degrees Celsius (400.15 Kelvin).

[0063] [Comparative Example 2] (Preparation of lead-free solder) First, the operator put 78.0 grams of indium, 20.0 grams of tin, and 2.0 grams of silver into a crucible. Then, Reference through the same procedure as the lead-free solder ingot according to Example 1, the lead-free solder ingot according to this comparative example was prepared.

[0064] (High-temperature creep test) The operator Reference conducted a high-temperature creep test in the same procedure as in Example 1. The test piece according to this comparative example broke between 100 hours and 600 hours after the load was applied.

[0065] (Room-temperature joint strength test for silver electrode) The operator Reference conducted a room-temperature joint strength test for the silver electrode in the same procedure as in Example 1. In the case of the joint strength test according to this comparative example, the maximum value of the load indicated by the pull gauge was 8.1 Newtons from the start of pulling the copper wire of the joint strength test piece until the lead-free solder used for soldering broke.

[0066] (High-temperature joint strength test for silver electrode) The operator ReferenceIn the same procedure as in Example 1, a joint strength test at high temperature was conducted on the silver electrode. In the case of the joint strength test according to this comparative example, the maximum value of the load indicated by the pull gauge from the start of pulling up the copper wire of the joint strength test piece to the breakage of the lead-free solder used for soldering was 3.8 Newtons.

[0067] (Specific Resistance Test) The operator Reference measured the specific resistance in the same procedure as in Example 1. The specific resistance of the lead-free solder according to this comparative example was 15.9 microohm·centimeter.

[0068] (Measurement of Solidus Temperature and Liquidus Temperature) The operator Reference measured the solidus temperature and the liquidus temperature in the same procedure as in Example 1. The solidus temperature of the lead-free solder according to this Comparison example was 127 degrees Celsius (400.15 Kelvin). The liquidus temperature of the lead-free solder according to this Comparison example was 131 degrees Celsius (404.15 Kelvin).

[0069] [Comparative Example 3] (Preparation of Lead-Free Solder) First, the operator put 83.0 grams of indium, 10.0 grams of tin, 5.0 grams of silver, 1.0 gram of antimony, and 1.0 gram of copper into a crucible. Then, Reference through the same procedure as the lead-free solder ingot according to Example 1, the lead-free solder ingot according to this comparative example was prepared.

[0070] (High-Temperature Creep Test) The operator Reference conducted a high-temperature creep test in the same procedure as in Example 1. The test piece according to this comparative example broke from 100 hours to 600 hours after the load was applied.

[0071] (Joint Strength Test at Room Temperature for Silver Electrode) The operator ReferenceIn the same procedure as in Example 1, a joint strength test at room temperature was conducted on the silver electrode. In the case of the joint strength test according to this comparative example, the maximum value of the load indicated by the pull gauge from the start of pulling up the copper wire of the joint strength test piece to the breakage of the lead-free solder used for soldering was 9.9 Newtons.

[0072] (Joint Strength Test at High Temperature for Silver Electrode) The operator Reference In the same procedure as in Example 1, a joint strength test at high temperature was conducted on the silver electrode. In the case of the joint strength test according to this comparative example, the maximum value of the load indicated by the pull gauge from the start of pulling up the copper wire of the joint strength test piece to the breakage of the lead-free solder used for soldering was 4.2 Newtons.

[0073] (Specific Resistance Test) The operator Reference Measured the specific resistance in the same procedure as in Example 1. The specific resistance of the lead-free solder according to this comparative example was 13.6 microohm·centimeter.

[0074] (Measurement of Solidus Temperature and Liquidus Temperature) The operator Reference Measured the solidus temperature and liquidus temperature in the same procedure as in Example 1. The Comparison solidus temperature of the lead-free solder according to this example was 131 degrees Celsius (404.15 Kelvin). The Comparison liquidus temperature of the lead-free solder according to this example was 138 degrees Celsius (411.15 Kelvin).

[0075] <Explanation of Effects> Figure 1 is a diagram showing the components of the lead-free solder according to the And reference examples Example And and various test results. Figure 2 is a diagram showing the relationship between the passage of time and elongation in the high-temperature creep test according to Example 1 and Comparative Example 1. Figure 3 is a diagram showing the results of the joint strength test at high temperature for the silver electrode and the Reference Example And reference examples Comparative Example AndIt is a diagram showing the relationship with the indium component content in the lead-free solder according to And reference examples It is a diagram showing the relationship with the silver component content in the lead-free solder according to And reference examples The effects of the lead-free solder according to this example will be described below with reference to FIGS. 1 to 4.

[0076] As is clear from FIG. 1, the lead-free solder according to And reference examples this example has a much longer time until fracture compared to the lead-free solder according to the comparative example. As is clear from FIG. 2, Reference the lead-free solder according to Example 1 has almost no creep elongation even in a high-temperature environment compared to the lead-free solder according to Comparative Example 1. From these facts, it is clear that the lead-free solder according to this example And reference examples has significantly better creep resistance in a high-temperature environment than that of the lead-free solder according to the comparative example.

[0077] Also, according to FIG. 1, Reference Example 1 And Example 1 and Reference Example 2 has a lower specific resistance than the specific resistances of 2 Examples 4 to

[0078] It can be said that when the mass% of the additive metal in the lead-free solder according to the present invention is 2.5 mass% or less, the specific resistance becomes small.

[0079] According to FIG. 4, when the mass percentage of silver exceeds 1.0% by mass, the maximum value of the load indicated by the pull gauge (bonding strength in a high-temperature environment) until the breakage of the lead-free solder occurs in the high-temperature bonding strength test for the silver electrode is high. Therefore, in the case of the lead-free solder according to the present invention, it can be said that it is desirable that the mass percentage of silver in this solder exceeds 1.0% by mass 3.0 % by mass Below is true.

[0080] The embodiments disclosed this time are illustrative in all respects. The scope of the present invention is not limited based on the above-described embodiments, and of course, various design changes may be made without departing from the spirit of the present invention.

Claims

1. Indium of 93.5% by mass or more and 96.5% by mass or less, tin of 1.0% by mass or more and 4.0% by mass or less, silver exceeding 1.0% by mass and 3.0% by mass or less, at least the silver and the antimony among antimony, copper, nickel of 0.1% by mass or more and 1.0% by mass or less, and being a metal different from the indium and the tin, and an additive metal having a total of mass% exceeding 1.1% by mass and 5.5% by mass or less, wherein the sum of the total of the mass% of the additive metal, the mass% of the indium, and the mass% of the tin is 100% by mass, and a lead-free solder is characterized thereby.

2. The lead-free solder according to claim 1, characterized in that the lead-free solder contains 0.05% by mass or more and less than 4.4% by mass of the copper as part of the additive metal.

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