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Title :物理特性を能動的に利用した機能材料高品位加工技術の探索
Title alternative :Feasibility study on effective use of material's physical properties in machining of functional crystal
Authors :周, 立波
Authors alternative :Zhou, Libo
Issue Date :9-Jun-2017
Abstract :研究成果の概要(和文):強誘電体は,強い焦電性(温度変化による分極)及び圧電性(応力による分極)を併せ持つため,携帯電話用SAWフィルタなどへの応用が期待される一方,加工時の高い圧力と温度に晒され,結晶の対称性が破れ極めて脆く割れ易い難加工材料である.本研究は,まず,温度変化によりLiTaO3の硬度が20%,破壊靭性が45%ほど低下することを押込実験で解明した.圧電・焦電効果による内部応力が研削中LTウエハの作用力の8~9割を占め,ウエハを破壊する主因であることを理論的な推定した.最後に①研削液の温度制御,②電解質添加による表面電荷の中和二つの方策を考案し,LTウエハを100um以下に薄く研削しその有効性を検証した.研究成果の概要(英文):Single crystal LiTaO3 (LT) is multi-functional, exhibits extraordinary piezo-/pyro-electricity, and expected to be utilized in sensors and SAW filters. Due to these physical properties, the LT single crystal is polarized and followed by structure phase transition when the temperature varies. The LT wafer is subjected to not only the external mechanical stress, but also the internal stresses which are resulted from polarization during grinding. The indentation results show the LT crystal degrades 20% in its hardness and 45% in toughness when temperature varied. Theoretical estimation on three stress components induced by the mechanical effect, the electronic effect and thermal effect in LT wafer during grinding suggest that the internal stress account for 80% of the total stress on the wafer, and stand out as the major fact for fracture. Temperature control and electrolyte utilization are proposed to suppress the internal stress, and successfully to grind wafer as thin as 100um.
Type Local :科研等報告書
Publisher :茨城大学
URI :http://hdl.handle.net/10109/14201
Appears in Collections:Grants-in-aid for scientific research Report (College of Engineering)

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