本論文以寬頻超音波的量測決定薄膜鍍層材料之彈性係數。首先，以改良式之旋轉塗佈/熱結晶法製作高頻且寬頻之Poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)]無鏡頭式聚焦換能器，於加工成曲面之鋁金屬背層材料上，直接旋鍍與極化此一P(VDF-TrFE)高分子薄膜，使之具有壓電性質；其次，搭配V(z)與V(f,z)二種散焦量測系統與波形分析法，測量鍍層材料表面聲波與板波之頻散曲線；最後，再以改良之數值反算方式萃取鍍層材料之機械性質。
本論文使用數個無鏡頭式P(VDF-TrFE)聚焦換能器，可精準量測寬頻範圍內之頻散曲線，操作頻率可達5～120 MHz，中心頻率則介於5～60 MHz 之間。本研究準備兩種不同的鍍層試片：（1）於半無限域之等向性玻璃或銅基材上電鍍之鎳薄膜;（2）於非等向性之(100)矽晶片上電鍍鎳薄膜。鎳鍍層厚度介於為15~65 μm。此外，為了研究電鍍速率對鎳鍍層材料機械性質的影響，同時驗證反算鍍層機械性質的分辨能力，本研究亦以不同的電鍍速率製作鍍層試片進行測試。
為了建立更合理與正確的反算方法，本研究執行鍍層試片之頻散曲線敏感度分析，並利用頻散曲線的敏感度特性建立一套新的材料性質反算方法。結果顯示：高、低頻段頻散資料之權重調配將是反算方法的關鍵，因此在反算過程中必須被考慮進去，以期準確地得到鍍層材料的彈性係數。為了驗證反算的結果，奈米壓痕試驗機（Nano-indentation system）亦用於量測鎳鍍層材料的楊氏係數，結果顯示反算結果具有相當的準確性，因此更驗證了頻散曲線敏感度分析的重要性。

This dissertation investigates the non-destructive determination of elastic constants of coating layers using measured dispersion relation of acoustic waves. Wideband lens-less acoustic microscopy measurement systems are developed based on several high-frequency Poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] focusing transducers, which are fabricated by a fast and combined spin-coating and thermal-crystallization method. The wave measurement is based on transducer defocusing measurement methods and V(f, z) or V(z) waveform processing analysis. P(VDF-TrFE) focusing transducers with central frequency from several few MHz to higher frequency (~56 MHz) and an aperture angle ranging from 30 to 95 degrees are successfully fabricated in laboratory and the wave measurements can cover a wide frequency range of 4~120 MHz with great measurement accuracy.
In experiment, samples with two different configurations are considered and investigated: (1) layered half-space sample, nickel layer is electroplated on thick isotropic glass and brass substrates, and (2) composite plate, nickel film is deposited on (100) silicon wafer. Nickel films with thickness ranging from 15 to 65 μm are prepared and tested. Additional samples of type (1) are also prepared with different coating rate for investigating the influence of coating rate on the elastic constants of coating materials.
Theoretical analysis on the sensitivity of dispersion curves is also carried out in this dissertation for discovering a better algorithm for inversely determining elastic constants of a coating layer from measured dispersion data. As a result of the analysis, a new inverse process having different weightings on different range of frequency or different modes of dispersion curves is proposed. Based on this method, elastic constants of few coating layers are determined from their measured wideband dispersion curves. The results show good agreement with the measured data from a nano-indentation system and its destructive measurement method. Measurement accuracy and potential applications for other types of nondestructive evaluation of the focusing transducers and measurement system are addressed.

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