低固含量銀漿之基礎流變性質研究

Investigation on Rheological Properties of Low-Solid-Content Silver Pastes

梁肇恩(JAU-EN LIANG)

指導教授 ： 華繼中

國立中正大學/工學院/化學工程學系/碩士(2015年)

摘要

近年來，已有許多學者致力於研究導電銀漿之效能改質，多數研究著重於高金屬固含量的導電漿料;然而為減低生產成本，降低銀粒子的使用量並維持銀線的低電阻性成為現今產業的首要目標。為達此目的，本研究系統性地探討低銀含量導電銀漿 (47wt%) 的流變性質，並結合印刷後的分析，探討導電銀漿的流變性質如何影響銀導線的性質。此外，為了解個別成份對銀漿流變性質的影響，我們亦分別針對漿料中的高分子黏著劑 (polymer binder) 、表面活性劑 (surfactant) 以及銀粒子進行一系列的流變實驗探討。於本實驗中，我們利用轉動式 (rotational) 及振盪式 (oscillatory) 實驗探測導電銀漿及其個別成份的流變性質，並針對特定成份的銀漿同步進行流變量測及印刷分析，此分析包括:利用電子顯微鏡 (SEM) 分析燒結 (sintering) 前後銀線的微結構、燒結後銀線的拉力以及電性測試。於流變實驗中，我們發現在銀漿中加入特定的表面活性劑，漿料的黏彈性會隨著時間不斷的上升，且上升的劇烈程度可藉由改變高分子黏著劑、表面活性劑、銀粒子的大小與形狀來調控，這顯示此表面活性劑有助於提升銀粒子及高分子的相互作用。此外，同步進行流變及印刷測試的分析結果顯示，此表面活性劑同時也有助於提升銀粒子的分散性及銀線的導電性和抗拉性，這結果說明，從漿料的流變性質可以反映出銀粒子的分散性、銀線的微結構、抗拉性及導電性。以上發現，希望未來能於漿料的評估及開發方面，提供具體且有效的方式。

關鍵字

矽晶太陽能電池 ； 表面活性劑 ； 高分子黏著劑 ； 流變學 ； 太陽能導電銀漿

並列摘要

In the last decades, much research had been dedicated to improving the performance of high-solid-content silver pastes. However, reducing the silver content of the pastes while maintaining low resistance of silver thick films is a long-term goal in current industries. For this purpose, we systematically investigated the rheological behavior of low-solid-content silver pastes (47wt%) and the performance of their screen-printed thick films. Both rotational and oscillatory measurements were carried out to scrutinize the viscoelastic behavior of silver pastes under the influences of polymer binder, surfactant, and silver powder. Scanning electron microscope (SEM), tensile strength and sheet resistance were used to analyze the performance of silver thick films. From this study, it was found that silver pastes which contained polymer binder and a specific surfactant exhibited time-evolving behavior, which can be fine-tuned through a proper combination of binder, surfactant, and silver powder. This phenomenon implied that the interaction of silver powder and polymer binder is promoted, and showed the improvement of the dispersion state of silver powder as later confirmed by the SEM micrographs. In addition, the results from this study suggested that the rheological properties of pastes are highly associated with the dispersion state of silver powder, printability of pastes, and performance of silver films. Accordingly, the present findings provide more specific information for assessment of paste quality.

並列關鍵字

Crystalline solar cells ； Surfactant ； Polymer binder ； Rheology ； Silver pastes

參考文獻

Amalu, E. H., Lau, W., Ekere, N., Bhatti, R., Mallik, S., Otiaba, K. and Takyi, G., "A study of SnAgCu solder paste transfer efficiency and effects of optimal reflow profile on solder deposits", Microelectronic Engineering 88, 1610-1617 (2011).

Chen, D., Zhao, L., Diao, H., Zhang, W., Wang, G. and Wang, W., "Rheological properties and related screen-printing performance of low-temperature silver pastes for a-Si: H/c-Si heterojunction solar cells", Journal of Materials Science: Materials in Electronics 25, 5322-5330 (2014).

De Wolf, S., Descoeudres, A., Holman, Z. C. and Ballif, C., "High-efficiency silicon heterojunction solar cells: A review", Green 2, 7-24 (2012).

Durairaj, R., Ekere, N. N. and Salam, B., "Thixotropy flow behaviour of solder and conductive adhesive pastes", Journal of Materials Science: Materials in Electronics 15, 677-683 (2004).

Durairaj, R., Mallik, S., Seman, A., Marks, A. and Ekere, N. N. "Viscoelastic properties of solder pastes and isotropic conductive adhesives used for flip-chip assembly". Electronic Manufacturing Technology Symposium (IEMT), 2008 33rd IEEE/CPMT International, 1-8, (2008).