無鉛銲錫球格陣列構裝製程與可靠度分析─總計畫

Abstract

本計畫針對球格陣列構裝（BGA）製程及其可靠度做相關研究。材料方面則選用目前極為熱門Sn3.5Ag 無鉛銲錫並以Sn37Pb 銲錫作為對照組。研究內容則為建立Sn3.5Ag 無鉛銲錫之迴銲曲線，及探討不同迴銲次數及長時間時效對機械性質的影響，並利用微結構作破損分析。實驗發現迴銲的次數對接點強度並無太大的影響。而在在長時間時效方面，接點強度隨著時效時間的增加而下降，且對於不同的時效時間，Sn3.5Ag 的強度都高於 Sn37Pb。Sn3.5Ag 在經過120℃、480 小時的時效處理後仍顯示延性破斷面，PbSn 則在經過120℃、115 小時時效後即出現介金屬層破斷型態。

The study focuses on the process and reliability of the ball grid array package. We select the popular Sn-3.5Ag lead-free solder for this test and use Sn-37Pb solder as comparison with Sn-3.5Ag solder. The study includes the reflow profile of Sn-3.5Ag solder, the effect of mechanical properties for different reflow cycles and long-term aging time and analysis of failure mode by microstucture. The results appear that there is no effect on the solder joint strength for different reflow cycles. In the aspect of long-term aging, we find that the strength of solder joints decreases by increasing the aging time and in each different aging time, the strength of Sn-3.5Ag solder joint is higher than Sn-37Pb one. After 480 hours at 120℃ in the aging treatment, the fractography still appears the ductile fracture mode but the Sn-37Pb solder fractures in the intermetallic compound layers after 115 hours at 120℃.