高密度封裝之無鉛銲錫的潛變與疲勞強度預估

本文首先引用文獻來做一連串的比對驗證，以確保本文研究內涵的可信度，然後再利用有限元素分析軟體ANSYS模擬分析無鉛(95.5Sn-3.9Ag-0.6Cu)及含鉛(62Sn-36Pb-2Ag)錫球之PBGA-256條狀模型在熱循環負載下分別依兩大議題(Topics)進行詳細的研究與論述。第一部分，探討使用間距比切割法與等份切割法網格被細分錫球對應力-應變分析的效應與比較，且比較四種不同錫球網格切割間距比之條狀模型與八分之一模型的研究並詳述其優劣性。第二部分，探討無鉛與含鉛錫球之熱疲勞壽命模型的可靠度分析與比較，即將錫球受到熱循環負載模擬分析後所得到累積潛變應變及累積潛應變能密度之結果，帶入錫球疲勞壽命預測公式裡計算作詳盡的比較，並進一步研究四種不同PCB厚度尺寸對疲勞壽命預測之影響。第一部分結果顯示錫球網格使用間距比切割法與等份切割法對PBGA-256封裝體之機械行為的特性非常相似，但以間距比法較省時；除此之外，錫球網格之間距比絕對值數值越大，則封裝體所承受之剪應力、潛剪應變、剪應力-潛剪應變之遲滯迴圈與潛變應變能密度的值都隨著增加，且無鉛錫球受到的影響會比含鉛錫球小。第二部分結果顯示，不論是無鉛錫球還是含鉛錫球，當PCB厚度增加，疲勞壽命預測值會減少，而無鉛錫球的可靠度都會較含鉛錫球高。

關鍵字

有限元素分析；累積潛應變能密度；無鉛銲錫；潛變行為；等份切割法；疲勞壽命；網格間距比；累積潛變應變

並列摘要

In the beginning, this paper compares a series of results of the literature on the subject to prove the correctness of the article, so as to ensure the credibility of this research. Then, by using finite element analysis software to simulate lead-free (95.5Sn-3.9Ag-0.6Cu) and tin-lead (62Sn-36Pb-2Ag) solder bumps under thermal cyclic loading, two topics are extended. The first topic is comparison with the solder bumps meshed by the methods of spacing ratio and equal division, and the effect on creep responses by difference spacing ratio in slice model and octant model. The second topic is to research on different fatigue life prediction models for lead-free and tin-lead solder bumps by using accumulated creep strain methods and accumulated creep strain energy density methods and to investigate into four thickness of PCB. The results of the first tropic show that solder bumps meshed by the methods of spacing ratio and equal division have great similarities. However, spacing ratio method can save much more CPU time on simulation. Besides, the modulus of spacing ratio is greater, the creep responses (shear stress, creep shear strain, hysteresis, and creep strain energy density) of solder bumps will be augmented. And the variation for lead-free solder is smaller than tin-lead. The results of the second topic show that no matter it is lead-free alloy or tin-lead one, when the thickness of PCB increases, fatigue life prediction decreases. And the reliability of lead-free alloy is higher than tin-lead one.

並列關鍵字

Spacing Ratio ； Equal Division ； Accumulated Creep Strain ； Fatigue Life ； Accumulated Creep Strain Energy Density ； Lead-Free Solder Bump ； Finite Element Analysis

參考文獻

[5] S. Wiese, A. Schubert, H. Walter, R. Dudek, F. Feustel, E. Meusel, and B. Michel, “Constitutive Behaviour of Lead-free Solders vs. Lead-Containing Solders-Experiments on Bulk Specimens and Flip-Chip Joints”, Electronic Components and Technology Conference, pp.890-902, 2001.

[6] A. Schubert, R. Dudek, H. Walter, E. Jung, A. Gollhardt, B. Michel, and H. Reichl, ”Reliability Assessment of Flip-Chip Assemblies with Lead-free Solder Joints”, IEEE Electronic Component and Technology Conference, pp.1246-1255, 2002.

[7] B. A. Zahn, “Solder joint fatigue life model methodology for 63Sn37Pb and 95.5Sn4Ag0.5Cu materials”, Electronic Components and Technology Conference, pp.83-94, 2003.

[9] A. Yeo, C. Lee, J. H. L. Pang, “Flip Chip Solder Joint Fatigue Analysis Using 2D and 3D FE Models, ” The 5th Thermal and Mechanical Simulation and Expertments in Micro-electronics and Micro-Systems Conference, pp. 549-555, 2004.

[10] A. Syed, “Accumulated creep strain and energy density based thermal fatigue life prediction models for SnAgCu solder joints”, Electronic Components and Technology Conference, Vol.1, pp.737-746, 2004.

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高密度封裝之無鉛銲錫的潛變與疲勞強度預估

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