目前隨著電子元件均朝向輕、薄、短、小的方向發展，造成電路積體密度增高，相對也使得熱通量更為上升，因此散熱問題遂成為電子產品設計的重點之一，熱管是一種可有效解決此問題之技術。熱管為一種具有高導熱元件，其乃是藉由熱管內流體的兩相轉換去達到熱擴散的效果，進而降低熱源集中的問題。但目前市售的圓柱狀熱管對於平面熱源會遇到接觸上的問題，而平板式的優點就是可以降低與熱源的接觸熱阻，而得到良好的熱傳效果。 本實驗製作一平板式輻射狀熱管，使用紅銅為熱管主體材質，其熱管上蓋分別為紅銅與壓克力，內部的毛細組織為多孔性陶瓷，使用去離子水做為工作液體，加熱功率2W~70W之間不等，並藉由可視化來觀察熱管內部之作動行為。實驗結果顯示，在熱管上蓋為紅銅材質時，充填30%較0%及15%之性能佳，而充填60%於40W之後開始變差。熱管充填30%時，於垂直擺放時又比水平擺放時有較低的蒸發端底部溫度及總熱阻抗；在壓克力為熱管上蓋時，其熱阻抗表現比紅銅上蓋時及垂直擺放時來得更好，而在毛細增厚測試下，性能表現於1.5mm厚度時較3mm厚度佳。 Heat pipes have been applied to cool high power density electronic devices. The main characteristic of two-phase changed of heat pipe can obtain reducing operation temperature of electronic devices, and achieving heat spreading effect. In this study, flat heat pipes instead of conventional cylindrical heat pipe were investigated experimentally. The cylinder heat pipe is not a good choice because the contact between heat pipe and flat heat source is not compact. Thus flat heat pipe is more suitable for improving. In this thesis, we study a flat radial heat pipes with porous ceramics wick structure and copper and acrylics top cover. Those heat pipes can operate at input power 2-to-70W. Work fluid charging fraction from 0% to 60%. The performance of flat radial heat pipe and permeability are also investigated experimentally in this study. For the measurement of performances with copper top cover, charging ratio at 30% is better than 0% and 15% with heat input increasing. However, the charging ratio becomes 60%, the thermal dispassion efficiency decays at input power 40W. In addition, the charging ratio at 30% has a lower operation temperature and thermal resistance under vertical orientation. The different material test of top cover, we found that the thermal resistance of heat pipe has more significant reduction on acrylics material than copper material. However, the thickness of wick structure increased from 1.5mm to 3mm, the thermal dispassion efficiency is not improved significantly.