臺灣博碩士論文加值系統

本文主要為電子基板構裝技術中BGA (Ball Grid Array)基板金屬球墊表面處理與無鉛焊錫焊點結合問題研究，目前BGA 基板金屬球墊表面處理大多以電鍍方式用導電線路加上電鍍鎳與電鍍金方式進行生產，但隨電子業輕、薄、短、小需求下，需要拉導電線線路去做電鍍鎳金方式將會浪費設計空間，降低細線路電子業設計需求。
所以本實驗重點在於選擇不需拉導電線表面處理方式，變化不同BGA 基板金屬球墊表面處理，再配合目前電子業使用較多無鉛錫球中Sn-3.5Ag-0.5Cu與Sn-7.0Zn-100ppmAl進行實驗，而BGA基板金屬球墊表面處理選擇主要有三種:為有機抗氧化劑OSP(Organic Solderability Preservative )、化學鎳金ENIG (Electroless Nickel Immersion Gold )、化學銀Im-Ag (Immersion Silver)進行各項實驗分析進行討論。
主要分析為將完成不同BGA基板金屬球墊表面處理與無鉛錫球，過IR Reflow後進行高溫老化實驗，再利用切片分析IMC (Intermetallic Compound)成長狀況，並進行錫球推力試驗了解何種表面處理使用上較佳，並分析較佳與較差原因，再加上介金屬成長及界面反應分析各項實驗，而實驗結果歸納主要結論如下:
1.由錫球推力發現，不同基板金屬球墊表面處理加上錫銀銅雖受溫度影響，但降低狀況不會因表面處理不同而改變，而錫鋅鋁則會受不同基板金屬球墊表面處理影響，其中以OSP銅面與化學銀表面處理最顯著。
2.觀察錫鋅鋁錫球在OSP銅面與化學鎳金表面處理介金屬成長狀況，發現OSP銅面表面處理隨時間與溫度成長快速，而化學鎳金表面處理相對較慢，顯示鎳層對於阻絕熱傳與介金屬擴散相當明顯。
3.另外發現錫鋅鋁加上OSP銅面或化學銀表面處理，於時效熱處理120 oC、1000小時下就會產生基板球墊銅面咬蝕狀況，隨溫度上升而更加嚴重，容易造成焊點推力降低問題產生。
4.化學銀表面處理可以觀察到明顯較大香濱泡沫(Micro Voids)，而其他表面處理界面Kirkendall Voids問題也非常明顯，但相對焊點強度與信賴性而言，化學銀表面處理則有較大風險。
總結本研究結果可看出BGA基板金屬球墊表面處理與無鉛錫球配合選擇必須相當注意，而以實驗結果做最佳組合排列為，錫銀銅配合化學鎳金高磷表面處理最穩定，其次分別為錫銀銅與OSP銅面與化學銀表面處理，再來為錫鋅鋁與化學鎳金表面處理，最差為錫鋅鋁搭配OSP銅面及化學銀表面處理，最差組合主要原因在於時效熱處理老化後，容易出現嚴重咬蝕基板金屬球墊銅面效應，使錫球推力急速下降產生焊點強度問題，所以該搭配並不適用於高信賴性電子構裝上。

This research paper includes surface finish of BGA (Ball Grid Array) solder pads and the lead-free solder ball combine with solder joints uses in electronic package technology. Nowadays, BGA metal surface finish, is produced to regard electroplating the way as mostly to deal with electroplate nickel and electricity gold-plated methods. But, in the electron industry, under the thin, short, & small demand, it wastes the design space and reduces the electron industry demand for fine pitch when BGA needs to draw the conductive line circuit to do plating with Nickel and Gold.

Consequently, the focal point of an experiment lies in choosing not to need drawing the conductive line surface finish and dealing with the way to change different BGA solder pads metal surface finish and to cooperate with uses of a lead-free solder ball, such as Sn-3.5Ag-0.5Cu and Sn-7.0Zn-100ppmAl at the electron industry under this experiment. And, BGA solder pads metal surface finish is it chosen for 3 kinds to deal with. That is, OSP (Organic Solderability Preservative), ENIG (Electroless Nickel Immersion Gold), & the chemical silver (Immersion Silver) are carried on every experimental analysis and discussed.

Analysis for different BGA solder pads surface finish and lead-free solder ball combine with solder joints , that after the IR Reflow carrying on the aging experiment of the high temperature mainly. Through x-section, to analyze the state that IMC grows up, and it carried on the shear force to search for solder joints reliability to check which metal surface finish was the best choice. Then, to analyze which surface finish has its own advantage and disadvantage for the root cause of low shear force and to check metal growing up and interface analysis of reacting of every experiment. Moreover, the experimental result is summed up for the main conclusion as follows:
1.It was found different surface finish by solder ball shear force. Although, the Sn-3.5Ag-0.5Cu were influenced by temperature, reduction did not change on various surface finish effects. It was the most significant for low shear force that it influenced dealing with OSP copper and chemistry silver surface finish among them that the Sn-7.0 Zn-100ppm Al would be dealt with by different kinds of surface finish.
2.To observe Sn-7.0 Zn-100ppmAl solder ball & IMC growing-up state of ENIG and OSP copper surface finish, it was found that OSP copper surface finish growing up with time and temperature fast. Nonetheless, ENIG glowed up slower. It was shown that the layers for hindering nickel was more adiabatic to spread and diffusion between metal not to spread quite obviously. Based on above analysis, it was found OSP higher than ENIG. Due to that reason, it could get stable shear force by ENIG surface finish.
3.In addition, it was found that a Sn-7.0 Zn-100ppm Al solder ball shear force OSP and chemistry silver surface finish dealt with 120oC under 1000 hours was it produced that solder pads copper face was copper etching condition . As temperature rises, it condition seriously causes solder joints shear force reduced.
4.The chemistry silver surface finish was observed for the obvious larger micro voids, but other finish surface interfaces had a ‘Kirkendall Voids’ problem obviously even under this experiment. Nevertheless, relative solder joint & reliability silver surface were they had heavy risk to deal with.

In conclusion, a result of study shows it needs very carefully that Ball Grid Array solder pad surface finish and selection of lead free solder ball. It was finally found with an experimental result that we can give to arrange in order from follow: Sn-3.5 Ag-0.5Cu+ ENIG P%> Sn-3.5Ag-0.5 Cu+ OSP> Sn-3.5Ag-0.5Cu+ Im-Ag > Sn-7.0Zn-100ppm Al+ ENIG P%> Sn-7.0Zn-100ppm Al+ OSP >Sn-7.0 Zn-100ppm Al+ Im-Ag . That is main a reason Sn-7.0 Zn-100ppm Al collocated OSP copper face or chemistry silver surface was apt to appear solder ball shear force reduced & insufficient solder-joint strength. Moreover, It was also found copper etching due to high diffusion reaction. In brief, those kinds of combination should not used for are high reliability electronic package construct.

中文摘要 I
英文摘要 IV
誌謝 VII
總目錄 VIII
圖目錄 XII
表目錄 XX
第一章 緒論1
1.1電子構裝簡介1
1.2錫鉛合金簡介3
1.3世界各主要國家禁鉛立法4
1.4世界各主要國家無鉛研究發展5
第二章 文獻回顧7
2.1電子構裝可靠度測試7
2.2無鉛焊錫特性7
2.3無鉛焊錫合金元素變化8
2.4常見無鉛材料簡介9
2.4.1錫-銀系統9
2.4.2錫-鋅系統12
2.5焊接基板表面處理簡介15
2.5.1有機抗氧化劑15
2.5.2化學鎳金18
2.5.3化學銀流程23
2.6不同基板金屬表面處理與無鉛焊錫合金反應相關研究25
2.7研究動機與目的28
第三章 實驗步驟及方法29
3.1實驗構想29
3.2BGA基板與不同表面處理製作31
3.2.1BGA基板之設計31
3.2.2BGA基板之製作32
3.2.3BGA基板不同表面處理製作33
3.2.3.1OSP表面處理製作33
3.2.3.2高低溫有機抗氧化劑處理銅表面特性分析33
3.2.3.3鍍鎳金不同磷含量表面處理製作34
3.2.3.4變化磷含量製作Cu/Ni-P/Au表面特性分析35
3.2.3.5化學銀表面處理製作36
3.2.3.6化學銀表面特性分析36
3.3不同金屬焊墊表面處理之BGA基板球墊與無鉛錫球接合37
3.3.1無鉛錫球之採用37
3.3.2無鉛錫球與基板球墊間之黏合固定助焊劑37
3.3.3迴焊製程39
3.4焊錫球之推力強度試驗40
3.4.1迴焊錫球推力後DSC試驗40
3.4.2迴焊時效熱處理後焊錫球之推力強度試驗40
3.5錫銀銅與錫鋅鋁界面介金屬化合物成長狀況40
3.6錫銀銅與錫鋅鋁焊錫與不同表面處理基板界面反應分析41
3.6.1界面介金屬化合物分析41
3.6.2界面介金屬反應孔洞(Voids)分析41
3.6.3其他界面介金屬反應現象觀察41
第四章 結果與討論42
4.1BGA球墊不同金屬表面處理製作分析42
4.1.1有機抗氧化劑(OSP)製作分析42
4.1.1.1有機抗氧化劑GC/Mass原料分析42
4.1.1.2有機抗氧化劑TGA原料分析42
4.1.1.3有機抗氧化劑DSC原料分析42
4.1.1.4有機抗氧化劑製作後進行IR Reflow分析43
4.1.1.5有機抗氧化劑IR Reflow後進行FTIR分析43
4.1.1.6有機抗氧化劑焊錫能力分析44
4.1.2化學鎳金基板球墊表面製作分析50
4.1.2.1不同磷含量化學鎳金板製作分析50
4.1.2.2不同磷含量化學鎳金板分析54
4.1.3化學銀面製作分析58
4.1.4BGA基板球墊AFM表面粗糙度分析60
4.1.5小結61
4.2.BGA球墊焊錫球之結合強度62
4.2.1迴焊後焊錫球之表面型態62
4.2.2迴焊後將錫球由基板取下做DSC分析63
4.2.3迴焊後變化時間與溫度焊錫球之推力強度分析64
4.2.4變化球墊表面處理時間與溫度焊錫球之推力強度分析68
4.2.5.變化球墊表面處理時間與溫度焊錫球之推力強度趨勢分析75
4.2.6焊點強度下降原因探討80
4.2.7小結82
4.3無鉛錫球與不同球墊表面處理基板之材料界面反應83
4.3.1錫球與不同球墊表面處理基板之材料介金屬表面形態84
4.3.2錫球與不同表面處理基板之材料介金屬厚度量測分析87
4.3.3時效熱處理後材料介金屬化合物變化分析90
4.3.3.1球墊表面處理與無鉛錫球所形成介金屬化合物分析90
4.3.3.2變化溫度不同球墊表面處理形成介金屬化合物形態分析98
4.3.3.3溫度變化下不同球墊表面處理咬蝕現象分析104
4.3.4球墊表面處理變化對孔洞(Voids)影響分析110
4.3.4.1 Kirkendall Voids現象分析110
4.3.4.2香濱泡沫(Micro Voids)現象分析112
4.3.4.3錫鬚(Tin Whisker)生成原因分析113
4.3.5小結114
第五章 結論116
第六章 參考文獻119

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