本文所研究之兩顆CSP構裝模組,為業界實際產品。此CSP構裝模組分別由兩顆CSP晶片所組成,分別為U3及U4。利用Solidworks繪圖軟體,建立U3(橢圓形錫球)及U4(橢圓形錫球)、U3(圓柱形錫球)及U4(橢圓形錫球),透過ANSYS有限元素法軟體進行模擬分析,模擬分析加入膠材後之兩顆CSP構裝模組於迴焊製程及膠材硬化製程後之錫球塑性應變能密度值之差異,並探討改變U3四種不同晶片厚度、U3錫球形狀及膠材之熱膨脹係數對包覆成型兩顆CSP構裝模組塑性應變能密度之效應。 由模擬結果可得知,U3(橢圓形錫球)及U4(橢圓形錫球),隨著U3四種不同晶片厚度的改變,明顯降低錫球塑性應變能密度;將U3錫球形狀改為圓柱形錫球,而U3(圓柱形錫球)及U4(橢圓形錫球)構裝體受到U3錫球形狀改變效應,降低錫球塑性應變能密度。
In this study, the two-CSP module was a real product. The chips of CSP were U3 and U4, respectively. The two-CSP module 3D model was established by Solidworks software for U3 chip(oval and cylindrical solder balls) and U4 chip(oval solder ball), and simulated structural stress, strain and plastic strain energy density under the conditions of reflow and underfill curing process by ANSYS software. We also considered the effects of the U3 die thickness and coefficient of thermal expansion of molding material on stress, strain and plastic strain energy density of a two-CSP module. The simulation results showed the plastic strain energy density of solder ball decreased with decreasing the U3 die thickness. The shape of U3 solder balls changed from oval to cylindrical solder also obviously reduced the plastic strain energy density. The results showed the coefficient of thermal expansion of molding material can reduce the accumulation of plastic strain energy density under the conditions of the curing process.