臺灣博碩士論文加值系統

中文摘要

現今電子產品朝向輕、薄、小、高功率、多功能的趨勢，電子構裝的可靠度是設計過程中必須重視的問題。電子元件中的錫球是重要的元件之一，除了電訊導通、增加機械結構強度，因此錫球的可靠度是研究人員所探討的重點。雖然有許多學者提出合理壽命預測有限元素模型，但文獻中提供完整的材料特性及相關封裝體的幾何尺寸往往不足，造成後續研究人員使用上的困擾，並無法驗證其成果的正確性。本文主要探討有鉛錫球在PBGA封裝壽命預測有限元素模型建立模式的探討，提供完整的有限元素模型資訊，以利有志之士進行相關研究。
針對有限元素模型，撰寫通用的ANSYS有限元素模型程式碼，適用於防焊綠漆設計且錫球為全域陣列分布的PBGA封裝體，程式可輸入想要分析的幾何尺寸。為了探討不同有限元素模型對壽限的影響，在全域模型中分為兩個模組。模組A為省略銅片之簡化有限元素模型、模組B為未省略銅片的有限元素模型。兩個模組又分別考慮1/4對稱與1/8對稱模型。每一個全域模型又可搭配次模型，因此每一個模組中每一個錫球共有四個預估壽命。
由結果顯示，模組B為未省略銅片的有限元素模型，四個模型的預估壽命收斂性良好。此點說明若全域模型考慮銅墊片時，進行1/8全域分析足以預測錫球壽命。模組A為省略銅片的有限元素模型，四個模型的預估壽命收斂性不佳，此點說明重要元件之銅墊片不可省略。
模組A配合次模型分析可修正預測錫球壽命，但與模組B相較仍有高於30 % 的預估壽命。1/8模組A全域配合次模型分析時，由於錫球對切的關係，對稱面不可用全域模型結果的導入，保持其對稱條件可得到更正確的預測錫球壽命。


關鍵詞：有限元素法、塑膠球柵陣列構裝體、錫球壽命、全域模型、次模型

Abstract
The trend of electronic products today is moving toward further miniaturization, high functionality and improved performance. To accomplish this, packaging needs to be able to integrate higher I/O counts, smaller pitches, and greater heat densities, while being pushed into smaller and smaller footprints. Solder joint reliability is of great concern to semiconductor and electronic product manufacturers.
This study focuses on the finite element strategy to the reliability of PBGA in solder joint life prediction. Firstly, the general purpose ANSYS finite element code was created. This code was satisfied with full array PBGA package and the designer could simply modify the geometric dimension, loading condition and nonlinear solder joint behavior.
Two types of model assumption were considered with (model A) and without (model B) copper pad on both sides of solder joint. There are two different finite element approaches in each model including 1/4 model A; 1/4 model A+submodel; 1/8 model B; 1/8 model B+submodel. Eutetic solder connections considering the hyperbolic sine creep model and thermal cycling test in ranging of -40 °C to 125 °C, are performed to demonstrate the overall results of this research.
According to the simulation results, the predicted life of model B was converged in all four models. Model A did not provide a good life convergence due to the neglected copper pad. The predicted life of model A + submodel can modified the convergence but still 30 % higher than those of model B. It is believed that the global model should be covered the major component which represented the mechanical behavior of the package.
As for the sobmodel combined with 1/4 model and 1/8 model, the cut boundary in the symmetric plane of 1/8 model has not to be imposed as traditional manner due to the solder joint presented in the symmetric plane. Instead of the cut boundary condition from the global analysis, the symmetric boundary applied to the submodel greatly enhances the predicted life.
Other thermal-mechanical behaviors of package were analyzed, such as von Mises stress and von Mises plastic strain, and plastic work density. It is found that the maximum values occur in the farthest ball due to DNP effect. In addition, the time domain responses of various thermal mechanical behaviors provided a further understanding on the thermal-mechanical behavior of the packages.


Keywords : Finite Element Method, Plastic Ball Grid Array, Solder Joint Fatigue Life, Global model, Submodel, Solder Joint Reliability

章節目錄
中文摘要........................i
Abstract......................ii
誌謝..........................iii
章節目錄.......................iv
圖目錄.........................vi
表目錄.......................viii
第一章 簡介......................1
1.1半導體封裝介紹................1
1.2研究動機與目的................7
1.3研究方法.....................8
第二章 PBGA封裝介紹.............10
第三章 錫球可靠度...............18
3.1Syed有鉛錫球壽命模式[6]......21
3.2Schubert 有鉛錫球壽命模式[8].22
3.3Zahn 有鉛錫球壽命模式[9].....23
3.4Pang 有鉛錫球壽命模式[10-11].25
第四章 PBGA有限元素分析模擬......27
4.1有限元素模型程式.............27
4.2有限元素分析模型.............32
4.3PBGA 材料特性..............34
4.4PBGA 負載及邊界條件.........36
第五章 結論與討論...............39
5.1有限元素模型模擬.............39
5.2 疲勞破壞模式...............42
5.3 有限元素模擬...............49
第六章 結論....................58
參考文獻......................60

參考文獻
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