衛星天線表面金屬濺鍍層受重複性彎曲之研究

Abstract

人造衛星天線各部件中，以反射面最為重要，因其電器特性會影響通訊品質。本研究探討可收摺的薄膜反射面，反射面的薄膜是以高分子材料 Kapton 為基材，並濺鍍一層薄金屬 Au 於基材上。本研究關注其薄膜反射面的薄膜電阻值與濺鍍層的外觀，因為這些因素與電器性質息息相關，當薄膜電阻急遽上升表面出現裂紋，代表反射面的精確度以及電磁波反射的成效已不具有足夠的可靠度。實驗結果顯示薄膜電阻在金屬薄膜表面承受彎折數次後，會有上升的趨勢，此現象是由於表面金屬層已超過其彈性限度205 MPa，導致塑性變形，而其殘留的應變使斷面幾何形狀改變。另一原因為表面產生破壞，例如裂紋、脫層、皺褶之情形。本研究藉由重複性完全對摺的實驗，模擬人造衛星反射面的收摺行為，並透過量測其電阻值的變化與電子顯微鏡之影像，觀察對濺鍍層之影響。經由實驗，觀察到高分子基材上有明顯的摺痕，然而因為鍍層金屬具有極佳的延展性，所以未於鍍層上發現完全斷裂。

Reflector surfaces on satellite antennas deserve research, since its electrical characteristics affect communication quality. This study deals with foldable reflectors. Kapton, as a substrate material, is sputtered with a thin layer of Au. The main concern of this research is the film resistance of the reflecting surface and the appearance of the coating layer, because these factors are highly related to electrical characteristic. When the electrical resistance of film increases rapidly and the coating occurs damage, the accuracy of the reflector and the reflection performance of electromagnetic wave do not have enough reliability anymore. Experimental results show that the electrical resistance of film will increase after the thin film has been bent several times. These results are caused by plastic deformations because the thin film has exceeded its elastic limit 205 MPa. The residual strain caused by plastic deformations leads to changes in cross-sectional shape. Additionally, the damages on the surface can also be another reason, such as cracks, delamination and wrinkles. This study simulates the behavior of satellite reflectors to observe the effects on the coating layer by measuring the variation of electrical resistance and scanning electron microscope images by repeated bending tests. Experimental results show that a crease obviously appears on the polymer substrate. However, fractures are not found on the surface of coated metal because of excellent ductility.