Abstract Aiming at higher cell efficiency and lower Ag consumption, research focuses on achieving smaller finger lines for silicon solar cell front side metallization. In-depth understanding of the printing process is mandatory to achieve uniform, defect free lines with high aspect ratio. An innovative high-speed video imaging setup allows for tracking of the mechanisms happening within ≈10–50 ms during the screen printing process. Two pastes differing significantly with respect to their rheological as well as wetting properties are used in this study. A paste spreading mechanism consisting of different consecutive process steps determines the final line shape. During nip contact the paste is squeezed between screen emulsion and substrate. Paste spreading further proceeds as long as the screen clings to the substrate, it occurs in a regular pattern and is most pronounced in the regions were mesh wires approach the emulsion surface. Then sudden retraction takes place during snap-off and the final line width is essentially fixed. Spreading is more pronounced for the paste exhibiting low viscosity at high shear rates and strong wetting of screen emulsion and substrate. The overall paste transfer is promoted by poor screen wetting and strong paste cohesion. These insights will stimulate further improvement of Ag paste formulation for solar cell metallization.

中文翻译：

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硅太阳能电池的正面金属化——丝网印刷过程的高速视频成像分析

摘要 针对更高的电池效率和更低的银消耗，研究重点是实现更小的硅太阳能电池正面金属化指状线。必须深入了解印刷过程，才能获得具有高纵横比的均匀、无缺陷的线条。创新的高速视频成像设置允许跟踪丝网印刷过程中大约 10-50 毫秒内发生的机制。本研究中使用了两种在流变学和润湿性能方面存在显着差异的糊剂。由不同的连续工艺步骤组成的糊剂铺展机制决定了最终的线条形状。在辊隙接触期间，糊状物被挤压在丝网乳液和基材之间。只要筛网紧贴基材，糊料就会进一步铺展，它以规则的模式出现，在靠近乳液表面的网状线区域最为明显。然后在折断过程中突然缩回，最终的线宽基本上是固定的。对于在高剪切速率下表现出低粘度和丝网乳液和基材的强润湿性的浆料，铺展更为明显。屏幕润湿性差和膏体内聚力强，促进了整体膏体转移。这些见解将刺激用于太阳能电池金属化的银浆配方的进一步改进。对于在高剪切速率下表现出低粘度和丝网乳液和基材的强润湿性的浆料，铺展更为明显。屏幕润湿性差和膏体内聚力强，促进了整体膏体转移。这些见解将刺激用于太阳能电池金属化的银浆配方的进一步改进。对于在高剪切速率下表现出低粘度和丝网乳液和基材的强润湿性的浆料，铺展更为明显。屏幕润湿性差和膏体内聚力强，促进了整体膏体转移。这些见解将刺激用于太阳能电池金属化的银浆配方的进一步改进。