臺灣博碩士論文加值系統

在電子元件高功率及及輕、薄、短、小化的要求下，熱一直是造成電子元件失效的原因之一，BGA封裝的主要失效原因是作為接點的錫鉛共熔合金（63Sn-37Pb；或稱錫球）的疲勞破裂，這是導因於封裝體不同材料間熱膨脹係數的差異所造成的熱應變。因此本研究著重於溫度及熱應力對BGA封裝錫球接點損壞的影響。文中主要是利用ANSYS軟體分析，經由-55℃至125℃每小時2個循環的溫度負載下，探討銲錫材料的機械塑性行為，並代入Coffin-Manson的經驗公式內求出疲勞的半生期。
分析結果發現錫球的最大應力值皆發生於構裝體最外角落的錫球，而外凸形錫球接點的塑性應變範圍較內凹形大。錫球間距（pitch，指錫球中心點距離）愈小，銲墊面積愈大，錫球的應力較小。
在封裝體中，錫球的幾何形狀，或是其材料性質，多少會對錫球接點的應力結果有所影響；故本文也參考國內外的BGA構裝相關文獻，並取用文獻中對應力、應變量與疲勞壽命較具影響力的參數加以整合分析，藉以預防構裝過程中因為加熱所產生的諸多問題，提高產品的可靠度。

The major reliability issue of Ball Grid Array package is solder joint crack due to thermal expansion mismatch between joined materials.In this study, a nonlinear finite element mode was used to analyze solder joints under the thermally induced stress and failure mechanism during thermal cycling between -55℃ and 125℃. The Ansys software was performed to compute the thermal stress and plastic strain. The Coffin-Manson formula was used to predict the fatigue life.It is found that the maximum von Mises stress occurs at the outest corner solder joint . The plastic strain range of solder joints in hourglass shape is less than the ones in barrel shape. The smaller pitch and the joints with larger solder pad area result in less stress. The reliability of BGA package is dramatically improved by decreasing the peak thermal stress.　These empirical correlations would be very useful to design engineers in selecting the electronic packaging materials and their properties to reduce the peak stress on the critical electronic devices.

目 錄

表目錄---------------------------------------------Ⅳ
圖目錄------------------------------------------------ V
符號說明---------------------------------------------VIII

第一章 緒論--------------------------------------------1
1-1、前言----------------------------------------2
1-2、IC封裝簡介----------------------------------2
1-2-1、BGA封裝製程介紹-----------------------2
1-2-2、TF-BGA晶片級尺寸封裝結構---------------4
1-3、研究方向------------------------------------4
1-4、文獻回顧-----------------------------------5
1-5、組織與章節-----------------------------------7

第二章 理論分析-----------------------------------------8
2-1、非線性分析理論-------------------------------8
2-2、彈塑性理論----------------------------------12
2-2-1、應力應變曲線---------------------------12
2-2-2、降伏點規範--------------------------14
2-2-3、塑性變形理論---------------------------15
2-2-4、三維應力應變關係-----------------------18
2-3、疲勞與Coffin-Manson可靠度公式--------------20
2-4、銲錫接點損壞模式----------------------------21

第三章 數值模擬---------------------------------------25
3-1、模型架構----------------------------------25
3-2、基本假設----------------------------------28
3-3、ANSYS有限元素分析軟體---------------------32

第四章 結果分析與討論----------------------------------39
4-1、二維與三維分析結果及討論-------------------39
4-2、不同參數對錫球損壞的影響-----------------------47
4-3、錫球幾何外型對損壞及可靠度結果分析--------------55
4-3-1、不同錫球幾何外型對熱應力及損壞之分析-------56
4-3-2、錫球接點疲勞壽命分析-------------------62

第五章 結論與未來發展-----------------------------------64
5-1、結論----------------------------------------64
5-2、未來發展-----------------------------------65
參考文獻---------------------------------------------67
自述

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