LEAD-FREE SOLDER ALLOY, SOLDER JOINING MATERIAL, ELECTRONIC CIRCUIT MOUNTED SUBSTRATE AND ELECTRONIC CONTROL DEVICE

• Main Authors: SHIMAZAKI TAKANORI, MUNEKAWA YURIKA, ARAI MASAYA, NAKANO KEN, KATSUYAMA TSUKASA
• Format: Patent
• Language: English; Japanese
• Published: 02.07.2020
• Subjects: ALLOYS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; CHEMISTRY; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; FERROUS OR NON-FERROUS ALLOYS; MACHINE TOOLS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS; METAL-WORKING NOT OTHERWISE PROVIDED FOR; METALLURGY; PERFORMING OPERATIONS; PRINTED CIRCUITS; SOLDERING OR UNSOLDERING; TRANSPORTING; TREATMENT OF ALLOYS OR NON-FERROUS METALS; WELDING; WORKING BY LASER BEAM

To provide a lead-free solder alloy which can exhibit thermal fatigue resistance, for example, even in an environment with a very severe temperature difference of -40°C to 175°C, can suppress progress of crack occurring at a solder joint even in an environment in which such a very severe temperature difference and vibration are loaded, and further, can suppress occurrence of void at the solder joint, a solder joining material, and an electronic circuit mounted substrate having a solder joint formed by use of the lead-free solder alloy and an electronic control device.SOLUTION: A lead-free solder alloy contains Ag of 2% by mass or more and 4% by mass or less, Cu of 0.3% by mass or more and 0.7% by mass or less, Bi of 1.2% by mass or more and 2% by mass or less, In of 0.5% by mass or more and 2.1% by mass or less, Sb of 3% by mass or more and 4% by mass or less, Ni of 0.001% by mass or more and 0.05% by mass or less, and Co of 0.001% by mass or more and 0.01% by mass or less, and the remainder comprising Sn.SELECTED DRAWING: Figure 1 【課題】例えば−４０℃から１７５℃といった非常に激しい寒暖差にある環境下であっても耐熱疲労特性を発揮し得ると共に、このような非常に激しい寒暖差及び振動が負荷されるような過酷な環境下においてもはんだ接合部に発生する亀裂の進展を抑制でき、またはんだ接合部におけるボイドの発生を抑制できる鉛フリーはんだ合金、はんだ接合用材料並びに当該鉛フリーはんだ合金を用いて形成されるはんだ接合部を有する電子回路実装基板及び電子制御装置の提供。【解決手段】Ａｇを２質量％以上４質量％以下と、Ｃｕを０．３質量％以上０．７質量％以下と、Ｂｉを１．２質量％以上２質量％以下と、Ｉｎを０．５質量％以上２．１質量％以下と、Ｓｂを３質量％以上４質量％以下と、Ｎｉを０．００１質量％以上０．０５質量％以下と、Ｃｏを０．００１質量％以上０．０１質量％以下含み、残部がＳｎからなることを特徴とする鉛フリーはんだ合金。【選択図】図１