聚亞醯 在鋁金屬上之黏著性之研究

Abstract

聚亞醯 與金屬間之著強度對多晶片模組(Multi Chip Module,MCM)構裝 的多層聯線傳導結構基板的可靠度有相當重要之影響o 本研究利用90度 剝離試驗(Peel Test)探討聚亞醯 (Polyimide,PI)薄膜在鋁上之黏著強 度之變化o實驗結果發現在剝離速度一定時,聚亞醯 其剝離強度先隨其厚 度增加而增加,在增至一最大值後,強度逐漸隨其厚度增加而下降o將剝離 強度之數據代入Gent和Hamed及Kim的剝離試驗理論分析得聚亞醯 在鋁上 真正之黏著強度約4g/mm o 在聚亞醯 薄膜固定時,剝離速度之效應與厚 度相似,剝離素度水平隨剝離賭強度增加而增加o濕度對聚亞醯 在鋁剝離 強度之影響的實驗顯示剝離強度僅在高濕度環境(大於90%RH)中出現劣化 之傾向;再85度,85%RH之時效試驗中,聚亞醯 的剝離強度在經過1000小時 之儲存後玻離強度並無明顯劣化產生,故聚亞醯 之前驅物(Polyamic acid,PAA)及NMP溶液在烘烤硬化時可能與鋁(氧化鋁)會產生對濕氣俱有抗 作用之界面之化學結構,此結果也說明水分子經由聚亞醯 薄膜之擴散應 非黏著強度之主要模式o 橫截面電子顯微鏡(XTEM)對界面形貌之觀察也顯 示交互鎖定(interlock)作用非聚亞醯 在鋁上黏著要性質發生之原因o Adhesion of polyimide (pI) on metal is one of most important factors affecting the realibility of multilayer interconnection structure used in multi-chip module packaging. In this work, the adhesion of PI on aluminum (Al) was evaluated by 90 -peel test. At fixed peel rate, it was found that peel strength increased as the polyimide thickness was increased. The peel strength reac- ached a peak value at some intermediate thickness,then decreased when thickness of PI further increased. At fixed PI thickness, the peel strength increased when peel rate was increases. The true adhesion strength of PI- on-Al interface was found to be 4 g/mm, as calculated by a combined peel test theory provided by Gent and Hamed and Kim et al. The effect of ambient humidity on peel strength of PI on Al was also investigated. For 85 C,1 hr storage at various ambient humidity, the deterioration of peel strength was observed when humidity level exceeded 90%RH; PI ad- hesion did not deteriorate when the specimen was aged in an 85 C 85%RH ambient for 1000hrs indicating that walter molecules reach- ing the PI/Al interface by diffusion through PI film is not the major cause of peel strength deterioration. Cross-section trans- mission electron microscopy (XTEM) revealed the mechanical inter- locking is not the major cause of PI adhesion on Al.