Elucidation of the effect of added elements on non-proportional fatigue properties of lead-free solders and development of models for lifetime evaluation

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K14562
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Materials/Mechanics of materials
• Research Institution: Ritsumeikan University
• Principal Investigator: Ogawa Fumio 立命館大学, 理工学部, 助教 (00424812)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 多軸疲労 / クリープ / はんだ材料 / 材料試験

Outline of Final Research Achievements

In this study, experimental and theoretical approach was taken to elucidate the effect of addition of elements to Sn1.0Ag0.7Cu solder on their creep-fatigue lives. In the following, experimental aspect is mentioned. Load cell with cylindrical shape, to detect load with high precision at low value was developed to achieve multiaxial fatigue and creep-fatigue tests under tension and torsion using miniature test specimen with gage diameter of 4 mm. As a result, its applicability to multiaxial tests in circle path was confirmed. Testing machine to perform fatigue and creep-fatigue test for specimen with gage diameter of 2 mm was newly developed. This test machine gives constant torsion torque to specimen and then push-pull load to specimen. It achieves fatigue testing by applying displacement from both sides of cylinder.

Free Research Field

材料力学

Academic Significance and Societal Importance of the Research Achievements

はんだ材料について小型のミニチュア試験片を用いた多軸の疲労試験、クリープ疲労試験はこれまでにほとんど実施されておらず、はんだ接合部の長期寿命については明らかとされていない。クリープ疲労を考慮すると、元素添加が有効であるかどうかも確認されていない。本研究では実験、理論の両面から多軸クリープ疲労寿命を明らかにするためのアプローチを行うとともに、クリープと疲労に関する実験データ蓄積と寿命解析を行った。