探討噴霧清洗過程中微結構之行為

Abstract

本研究主要探討微結構於噴霧清洗過程之應力分析。由於微結構於噴霧清洗過程中，容易受到水流衝擊而被破壞。為了提升良率並瞭解清洗過程之受力情形，藉由有限元素分析(Finite Element analysis, FEA)來模擬微結構受力情況，並針對各項清洗與微結構參數進行探討。 首先，建立流固耦合(Fluid-Structure Interaction, FSI)分析模型探討微結構於噴霧清洗過程之應力狀態。二維微結構分析結果顯示，高寬比(aspect ratio)愈大，結構所承受的應力愈大。透過三維微結構模型，探討三種水流衝擊方向與微結構間距對其應力之影響，結果顯示當水流衝擊方向與結構長邊垂直時，其所承受應力最大。此外，當微結構間距小於200nm時，此微結構具較低之應力。接著，建立噴霧模型探討流場與微結構破壞之關係，結果發現高速水流區分佈於內徑2.86mm、外徑6.64mm的環狀分佈，此分析結果與實驗相近。此外，分析結果顯示微結構間距愈大，其愈容易被破壞，此結果亦與實驗相符。最後，本研究探討微結構間距對殘留氣泡之影響，分析結果顯示，微結構間距大於100nm能有效降低殘留氣泡量，而加入表面活性劑(surfactant)亦可降低殘留氣泡量。

This research aims to characterize the stress distribution of the microstructures during spray cleaning process, since the water spray may impact the microstructures and result in the structural damage. In order to improve the yielding rate, it is required to understand the stress distribution during the cleaning process. Finite element analysis was performed to simulate the behavior of the microstructure. Moreover, several parameters associated with the cleaning process and the geometric dimensions of microstructure were discussed. Based on the Fluid-Structure Interaction (FSI) analysis, the spray cleaning model for the microstructures was established initially, from which the stress analysis of the microstructures during spray cleaning process was calculated. Simulation results from the two-dimensional model of single microstructure indicated that the states of stress in the structures with high aspect ratio are high. In addition, from the analysis of the three-dimensional pattern containing three microstructures subjected to three different directional flows, it was shown that the microstructures have high stress when the flow direction is perpendicular to the length of microstructures. Furthermore, when the space of the microstructures is less than 200nm, the stress in the microstructure is relatively low. Subsequently, the damage zone size of microstructures with inner diameter 2.86mm and outer diameter 6.64mm affected by flow field were evaluated which is close to the experimental observation. In addition, when the space of the microstructures increase, the structures are prone to be damaged. Simulation results also show that when either spacing is larger than 100nm or surfactant is included in the water, the extent of air trapped in the microstructure can be reduced.