Evaluation of long-term reliability of potassium ion electret film and its verification by device performance

2017 Fiscal Year Final Research Report

• Project/Area Number: 15H03946
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Intelligent mechanics/Mechanical systems
• Research Institution: Shizuoka University
• Principal Investigator: Hashiguchi Gen 静岡大学, 電子工学研究所, 教授 (70314903)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: エレクトレット / カリウムイオン / MEMS / 高温高湿加速試験 / コンデンサーマイクロフォン

Outline of Final Research Achievements

In order to ensure the long-term reliability of the potassium ion electret film, I have examined passivation film against humidity. I first investigated charging principle of the electret and conducted electret charging experiment for the film on which SiN layer is deposited. This resulted in no electret voltage because SiN layer acts as barrier of potassium ion moving during charging process. Therefore we examined Parylene film that can coat after charing. The acceleration tests under 85 degree C and 90 %Rh humidity conditions shows over 50hour life-time to -1dB degradation. I also developed an condensor microphone by using potassium ion electret technique and tested degradation of sound pressure sensitivity under 85 degree C and 70%Rh humidity condition. After 20 hours test , the remarkable deterioration was not observed to the sound pressure sensitivity.

Free Research Field

MEMS