臺灣博碩士論文加值系統

四方扁平無腳封裝為接近晶片尺寸級封裝具有極細間距與小尺寸的特色，可提高印刷電路板的利用率，而與TSOP或QFP封裝體比較，體積縮小了60%，而且成本又低於CSP，非常適合於小型可移動產品之應用，再者，使用銅導線架之膠體封裝，並利用錫膏將QFN連接到印刷電路板上，因縮短連接距離，可增加電性能。此外，中央大的晶片墊，可將封裝體之熱量迅速地傳到印刷電路板上，具有良好的熱性能。
本研究將採用ANSYS9.0套裝分析軟體，根據JEDEC規範將QFN構裝體施予-40℃~125℃的溫度循環負載，而錫膏以亞蘭德黏塑性分析法，及使用Coffin-Manson疲勞壽命預測公式來計算QFN構裝體錫膏的疲勞壽命。
在本文中考慮溫度循環範圍振幅、溫度循環範圍平均溫度、晶片厚度、印刷電路板厚度、印刷電路板熱膨脹係數、封膠熱膨脹係數、結構黏膠熱膨脹係數、錫膏外觀形狀與晶片墊熱膨脹係數等因子，進行單一因子分析，以評估各因子對封裝結構疲勞壽命的效應，然後將上述各因子利用田口品質設計，建立直交表進行實驗，並經誤差統合，找出最佳化的參數組合，並且有效改善QFN構裝體之可靠度。
由單一因子分析結果顯示，藉由縮小溫度循環範圍振幅、減少印刷電路板厚度、降低晶片墊熱膨脹係數、增加印刷電路板熱膨脹係數、增加封膠熱膨脹係數、增加錫膏高度，皆能有效提高QFN構裝體疲勞壽命，其餘因子對QFN構裝體疲勞壽命的影響性並不大。最後，利用田口品質設計所得最佳製程參數之構裝體疲勞壽命為3587次，而原始製程參數設計之構裝體疲勞壽命為1050次，疲勞壽命約提昇3.42倍，因此有效改善QFN構裝體之可靠度。

Since the quad flat no-lead package (QFN) is closed to Chip scale package with characters of fine pitch and small outline.It is facilitated to increase the utility rate of PCB and Compared to TSOP or QFP, QFN is in favor of 60% reduction in volume and less costs than CSP which is good for the application of small size and portable products. Furthermore, with the lead frame filled with an epoxy mould compound, and connecting to PCB through the solder paste , QFN has advantage in shortening the circuit so that the electrical performance can be promoted. Besides, the large central Die pad is in favor of prompt heat transfer to PCB and hence has advantage in thermal performance.
This study will adopt ANSYS9.0 software for analysis.Based on JEDEC code,QFN will be loaded by a temperature cycle of -40℃~125℃.The solder paste is assumed to be Anand’s viscoplastic, then the Coffin-Manson fatigue life formula will be applied to predict the fatigue life of the solder paste in QFN package.
The single-factor experiment was adopted to predict the impact on fatigue life of QFN by following factor: the the control factors are the amplitude of temperature cycling range,the mean temperature of temperature cycling range ,thickness of Die, thickness of PCB,CTE of PCB,CTE of Mold Compound,CTE of structural adhensive,the shape of solder paste,CTE of Die pad.Finally,the Taguchi Method was applied to obtain an option parameter combination to improve the reliability of QFN package.
The results of single-factor study showed that by reducing the amplitude of temperature cycling range, thickness of PCB,CTE of Die pad as well as by increasing CTE of PCB, CTE of Mold Compound and the standoff of solder paste, will increase the solder fatigue life. On the other hand, the other factors have no significant effect on the solder paste fatigue reliability.
Finally,the optimal design from Taguchi Method optimized the fatigue life of 3587 cycles, but the original design had much less fatigue life of 1050 cycles, the optimal design had 3.42folds on the fatigue life over the original design, far improving the reliability of QFN module package.

摘要..............................................................................................Ⅰ
誌謝..............................................................................................V
目錄...............................................................................................VI
表目錄...........................................................................................X
圖目錄........................................................................................... XIII
符號說明.....................................................................................XVII
第一章 緒論
1-1 前言...................................................................................................1
1-2 研究動機與目的...............................................................................3
1-3 文獻回顧...........................................................................................4
1-4 研究方法...........................................................................................8
1-5 章節提要...........................................................................................9
第二章 理論基礎
2-1 研究主題..........................................................................................12
2-2無鉛錫膏之發展...............................................................................13
2-3塑性理論分析基礎............................................................................15
2-3-1塑性行為模式............................................................................15
2-3-2米澤斯降伏準則........................................................................16
2-4亞蘭德黏塑性本構模型....................................................................17
2-5 錫膏破壞模式...................................................................................24
2-6 疲勞機制...........................................................................................25
2-6-1 Coffin-Manson疲勞壽命預測公式.........................................25
2-7田口品質設計法...............................................................................27
2-7-1 機能品質特性值......................................................................29
2-7-2 直交表......................................................................................29
2-7-3 自由度......................................................................................29
2-7-4 損失函數..................................................................................30
2-7-5 信號雜訊比..............................................................................31
2-7-6回應表和輔助回應圖...............................................................32
2-7-7變異數分析...............................................................................33
2-7-8 信賴區間..................................................................................35
2-7-9 機能窗法..................................................................................36
第三章 分析模型之建立與評估
3-1 QFN構裝體之分析模型建立..........................................................43
3-1-1 QFN構裝體模型.....................................................................44
3-1-2 QFN構裝體模型之基本假設條件.........................................44
3-1-3分析型態與邊界條件..............................................................45
3-2 ANSYS有限元素分析.....................................................................47
3-3 QFN構裝體模型之網格收斂性分析..............................................50
3-4 QFN構裝體模型之結果探討.........................................................51
第四章 QFN構裝體之單一因子分析
4-1單一因子水準值之選擇....................................................................76
4-1-1單一因子的分析結果.................................................................77
4-2單一因子分析結果探討.....................................................................83
第五章 田口氏品質工程分析
5-1田口品質設計法之實驗設計............................................................100
5-1-1選定目標函數.............................................................................100
5-1-2判定品質特性之理想機能.........................................................101
5-1-3列出影響目標函數之控制因子.................................................101
5-1-4決定控制因子與其水準值.........................................................101
5-1-5選擇適當的田口直交表.............................................................102
5-2實驗結果............................................................................................103
5-3變異分析............................................................................................104
5-4預測與確認實驗................................................................................105

第六章 結論與未來研究方向
6-1 結論...................................................................................................115
6-2 未來研究方向...................................................................................118
參考文獻........................................................................................119
自述.................................................................................................123























表目錄
表2-1無鉛銲錫材料特性表......................................................................37
表2-2 Sn-Ag-Cu系無鉛銲錫之專利.........................................................37
表 2-3 Sn3Ag0.5Cu錫膏之Anand常數.......................................................38

表3-1各元件之尺寸....................................................................................53
表3-2各元件材料機械性質................... ....................................................53
表3-3 Sn3Ag0.5Cu錫膏亞蘭德模型參數..................................................54
表3-4原始QFN構裝體模型之各別元件元素個數..................................54
表3-5 QFN構裝體各元件沿厚度(Y)方向之線段分割對應元素數..........55
表3-6 QFN構裝體五個案例等效塑性應變、等效應力與最大位移值....55

表4-1 各控制因子之水準表........................................................................84
表4-2 改變溫度循環範圍之振幅變動因子分析結果................................85
表4-3 溫度循環範圍振幅對疲勞壽命之影響............................................85
表4-4 改變溫度循環範圍平均溫度變動因子之分析結果........................86
表4-5 溫度循環範圍平均溫度對疲勞壽命之影響....................................86
表4-6 改變晶片厚度變動因子之分析結果................................................87
表4-7 晶片厚度對疲勞壽命之影響............................................................87
表4-8 改變印刷電路板厚度變動因子之分析結果....................................88
表4-9印刷電路板厚度對疲勞壽命之影響.................................................88
表4-10 改變印刷電路板熱膨脹係數變動因子之分析結果......................89
表4-11 印刷電路板熱膨脹係數對疲勞壽命之影響..................................89
表4-12 改變封膠熱膨脹係數變動因子之分析結果..................................90
表4-13 封膠熱膨脹係數對疲勞壽命之影響...............................................90
表4-14 改變黏膠熱膨脹係數變動因子之分析結果...................................91
表4-15 黏膠熱膨脹係數對疲勞壽命之影響..............................................91
表4-16 改變錫膏外型變動因子之分析結果..............................................92
表4-17 錫膏外型對疲勞壽命之影響................................. ........................92
表4-18 改變晶片墊熱膨脹係數變動因子之分析結果..............................93
表4-19 晶片墊熱膨脹係數對疲勞壽命之影響..........................................93

表5-1各控制因子水準變動表.....................................................................108
表5-2 L18直交表..........................................................................................108
表5-3錫膏疲勞壽命實驗結果與S/N比.....................................................109
表5-4控制因子對S/N比反應表.................................................................109
表5-5各因子變異量與總變異量的平方和................................................110
表5-6對S/N比的第一次誤差統合............................................................110
表5-7對S/N比的第二次誤差統合............................................................111
表5-8原始與最佳設計之S/N預測值及確認實驗值比較........................111


















圖目錄
圖1-1 SOP.............................................................................................11
圖1-2 SOJ.............................................................................................11
圖1-3 TSOP...........................................................................................11
圖1-4 QFP.............................................................................................11

圖2-1應力-應變圖..................................................................................39
圖2-2降服軌跡圖...................................................................................39
圖2-3以電子顯微鏡下實際觀測錫膏之破壞情形...............................40
圖2-4 以有限元素分析法得出最大之SED位置.................................40
圖2-5 田口式品質工程概念圖...............................................................41
圖2-6 參數設計流程圖...........................................................................42

圖3-1 QFN封裝實體圖...........................................................................56
圖3-2 QFN結構圖...................................................................................56
圖3-3整體構裝體於厚度方向之尺寸....................................................56
圖3-4四分之ㄧ對稱模型邊界條件........................................................57
圖3-5溫度循環負載示意圖....................................................................57
圖3-6整個分析流程................................................................................58
圖3-7具塑性大變形之VISCO107元素..................................................59
圖3-8 SOLID45元素...............................................................................59
圖3-9 QFN構裝體模型之網格切割情形..............................................60
圖3-10 QFN構裝體模型錫膏網格化情形............................................60
圖 3-11 Case1構裝體整體位移圖...........................................................61
圖 3-12 Case1錫膏等效應力圖...............................................................61
圖3-13 Case1錫膏等效塑性應變圖.......................................................62
圖 3-14 Case2構裝體整體位移圖..........................................................62
圖 3-15 Case2錫膏等效應力圖................................................................63
圖3-16 Case2錫膏等效塑性應變圖.......................................................63
圖 3-17 Case3構裝體整體位移圖............................................................64
圖 3-18 Case3錫膏等效應力圖................................................................64
圖3-19 Case3錫膏等效塑性應變圖.......................................................65
圖 3-20 Case4構裝體整體位移圖............................................................65
圖 3-21 Case4錫膏等效應力圖................................................................66
圖3-22 Case4錫膏等效塑性應變圖.......................................................66
圖 3-23 Case5構裝體整體位移圖............................................................67
圖 3-24 Case5錫膏等效應力圖................................................................67
圖3-25 Case5錫膏等效塑性應變圖........................................................68
圖 3-26 Case6構裝體整體位移圖.............................................................68
圖 3-27 Case6錫膏等效應力圖.................................................................69
圖3-28 Case6錫膏等效塑性應變圖........................................................69
圖3-29 各分析案例之最大位移................................................................70
圖3-30 各分析案例之等效應力...............................................................70
圖3-31 各分析案例之等效塑性應變......................................................70
圖3-32 Case 4之QFN構裝體網格正視圖................................................71
圖3-33 Case 4之QFN構裝體細部網格圖................................................71
圖3-34 Case 4之錫膏網格圖....................................................................72
圖3-35高溫7864秒構裝體整體位移圖（放大20倍）............................72
圖3-36 低溫8764秒構裝體整體位移圖（放大20倍）.....................73
圖3-37 構裝體最大位移量與時間關係圖.............................................73
圖3-38 最大等效塑性應變發生處..........................................................74
圖3-39 最外側錫膏取點位置..................................................................74
圖3-40 錫膏等效應力與時間關係...................................................74
圖3-41 錫膏等效應變與時間關係...................................................75
圖3-42 錫膏剪應力與剪應變遲滯曲線關係圖.............................75

圖4-1 改變溫度循環範圍之振幅示意圖..............................................94
圖4-2改變平均溫度範圍示意圖...........................................................94
圖4-3錫膏外觀形狀1............................................................................95
圖4-4錫膏外觀形狀2............................................................................95
圖4-5錫膏外觀形狀3............................................................................96
圖4-6溫度循環範圍之振福對錫膏疲勞壽命影響趨勢.......................96
圖4-7溫度循環範圍平均溫度對錫膏疲勞壽命影響之趨勢...............97
圖4-8晶片厚度對錫膏疲勞壽命影響之趨勢.......................................97
圖4-9印刷電路板厚度對錫膏疲勞壽命影響之趨勢............................97
圖4-10印刷電路板熱膨脹係數對錫膏疲勞壽命影響之趨勢.............98
圖4-11封膠熱膨脹係數對錫膏疲勞壽命影響之趨勢.........................98
圖4-12黏膠熱膨脹係數對錫膏疲勞壽命影響之趨勢.........................98
圖4-13錫膏外型對錫膏疲勞壽命影響之趨勢......................................99
圖4-14晶片墊熱膨脹係數對錫膏疲勞壽命影響之趨勢......................99

圖5-1影響QFN構裝體疲勞壽命之魚骨圖..........................................112
圖5-2控制因子對S/N比的反應圖........................................................112
圖5-3原始製程參數設計之預測值與確認實驗值的信心區間............113
圖5-4最佳製程參數設計之預測值與確認實驗值的信心區間............114

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