A Study on RF High Power Durability of Al-Cu Alloy Electrodes Used in Ladder-type SAW(surface acoustic wave) Filters

Al-Cu 합금 전극막 구조를 갖는 사다리형 SAW filter의 RF-고전력 내구성 특성 고찰

  • 김남철 (공주대학교 신소재공학부 생산기술연구소) ;
  • 이기선 (공주대학교 신소재공학부 생산기술연구소) ;
  • 서수정 (성균관대학교 공과대학 금속재료공학부) ;
  • 김지수 (삼성전기(주) 적층박막사업부) ;
  • 김윤동 (삼성전기(주) 적층박막사업부)
  • Published : 2001.05.01

Abstract

As power durable RF SAW filters, AL-(0∼2wt%)Cu alloy multi-layered thin electrodes were deposited on 42° LiTaO$_3$ piezoelectric substrates by magnetron sputtering process, and then ladder-type RF SAW filters, satisfying the electrical specification of CDMA transmission band, were fabricated through optimizing SAW resonator structures. The temperature of film electrodes in SAW filter was increased with RF power, and reached the maxima to cause a failure of SAW filters at the cut-off frequencies of the RF filter band. As RF power increases, the electrodes of Al-Cu alloy showed higher power durability than that of pure Al. The multi-layer laminated film of Al-1wt.% Cu/Cu/Al-1wt%Cu resulted in the best power durability up to 4W of RF power. Every film electrode, however, was destroyed within seconds whenever applying a critical RF power to SAW filters, regardless of the composition and structure of film electrodes. The breakdown of film electrodes under FR power seems to believe due to the fatigue of electrodes caused by repetitive cyclic stress of surface acoustic wave, which is amplified as RF power increases.

Keywords

References

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