添加奈米級Cu6Sn5粉末對錫銀銅銲料接點之微結構及機械性質的影響

Effect of Nano-Sized Cu6Sn5 Additive on Microstructure and Mechanical Properties for SnAgCu Solder Joints with Au/Ni-P/Al UBM

邱國峻(Guo-Jyun Chiou)

指導教授 ： 杜正恭

國立清華大學/工學院/材料科學工程學系/碩士(2006年)

https://doi.org/10.6843/NTHU.2006.00542

摘要

增進銲料接點的機械強度在現今電子構裝的研發中是重要的議題。本研究探討添加奈米(nano)級之Cu6Sn5粉末的錫銀銅複合銲料與商用錫銀銅銲料之微結構與機械性質的比較。本研究中發現：複合銲料和金/無電鍍鎳磷/鋁基板在經過240°C一次迴銲後，在銲料/無電鍍鎳磷的界面生成Ni3Sn4介金屬化合物(IMC)，Ni3Sn4的厚度會隨著迴銲次數增加而成長。而商用錫銀銅銲料接點在經過一次迴銲後，銲料/無電鍍鎳磷界面除了Ni3Sn4介金屬化合物生成外，還有Cu6Sn5介金屬化合物。經過多次迴銲後，由於界面Cu6Sn5介金屬化合物的剝離，在界面僅發現Ni3Sn4介金屬化合物，且Ni3Sn4介金屬化合物亦隨著迴銲次數的增加而成長。此外也觀察銲料凸塊內微結構之衍進，並藉由場發射電子微探儀(FE-EPMA)以進而分析銲料內元素分布的情形。
在機械性質方面，利用奈米壓痕量測銲料凸塊之潛變特性，發現複合銲料有較高的潛變應變速率感應指數(creep strain rate sensitivity)。另外藉由微推拉力機量測銲料接點的推球強度，亦發現在每秒一百微米的推球速率下，當銲料接點經過一次到三次迴銲，添加奈米級Cu6Sn5粉末之複合銲料接點強度優於商用錫銀銅銲料接點強度。惟在超過五次迴銲後，複合銲料和商用錫銀銅銲料接點強度相若。此外，本文也探討在每秒一千微米的推球速率下複合銲料和商用錫銀銅銲料之接點強度，並發現在此推球速率條件下複合銲料接點強度明顯優於商用錫銀銅銲料。

關鍵字

銅六錫五 ； 錫銀銅銲料 ； 介金屬化合物 ； 金/鎳-磷/鋁基板 ； 推球測試 ； 複合銲料 ； 奈米壓痕機 ； 潛變測試 ； 場發射式電子微探儀

並列摘要

Improving mechanical strengths of solder joints is a crucial issue in electrons packaging, and using composite solders is one of the potential methods to increase the joints strengths. In this study, Cu6Sn5-contained solder paste was produced by mechanical mixing Cu6Sn5 nano powder into commercial SnAg solder paste. The Au/Ni-P/Al UBM was first deposited onto the silicon wafer, and the Cu6Sn5-contained solder paste was then stencil printed on the UBM and reflowed at 240°C. The interfacial morphology and microstructure of solder bumps were evaluated by FE-EPMA. With different reflows, the microstructures of solder matrixes and IMCs at interface of solder/UBM joint in both Cu6Sn5-contained solder and commercial Sn3.0Ag0.5Cu solder were evaluated and discussed. Besides, the elemental distribution of Cu6Sn5-contained solder was detected by X-ray color mapping in a newly developed FE-EPMA.
To realize the effect of Cu6Sn5 nano powder doping, the creep characteristics and ball shear strengths of the joints were further investigated. Nanoindentation was employed to measure the creep characteristics of solder alloys. It was revealed that the creep strain rate sensitivity of Cu6Sn5-contained solder was higher than that of SnAgCu solder although the creep hardness of both solders was identical.
Ball shear strengths of both solder joints were applied at two different shear speeds. In addition, the ball shear strengths of Cu6Sn5-contained solder and SnAgCu solder joints were probed with respect to the fracture surfaces, interfacial morphologies, and fracture modes. The effects of nano-sized Cu6Sn5 additive were summarized and the feasibility of this composite SnAgCu solder in electronic packaging was discussed.

並列關鍵字

Cu6Sn5 ； Sn-Ag-Cu solder ； intermetallic compound ； Au/Ni-P/Al UBM ； ball shear test ； composite solder ； nano-indentation ； creep test ； FE-EPMA

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