喷墨打印中的界面润湿问题

Interfacial Wetting in Inkjet Printing

近年来,印刷电子因成本低、能耗低、工艺简便等优势,在微电子制造领域展现出巨大的应用潜力,引起了人们的广泛重视。喷墨打印作为一种重要的印刷电子工艺,能够通过电脑编程直接实现图形化,相比真空光刻工艺,具有快速、灵活等优势,因此一直以来都是学术研究的热点。喷墨打印中涉及到墨水材料的喷射及其在打印基底上的沉积过程,在这个过程中墨水将接触到喷头及基板材料并发生润湿行为,因此材料界面的润湿问题关系到打印的图形化以及功能化效果,对最终打印结果有着重要影响。从界面的角度来看,喷墨打印中的润湿问题主要是墨水-打印基底的界面润湿问题;单纯从表面的角度来看,喷墨打印中的润湿问题可以分为墨水(液相)的润湿性问题以及基板(固相)的润湿性问题。研究中通常对液相或固相的润湿性进行控制来实现预期的打印效果。研究表明,墨水的润湿性主要在喷墨过程中影响其喷墨状态,以及在铺展过程中影响打印精度和表面形貌等,而基板的润湿性则主要在墨水铺展成形的过程中决定打印图形化的效果。墨水成分、基板材料很大程度上决定了其表面张力以及表面自由能,通过调整墨水溶剂的配方或加入添加剂以及改变基板材料成分能够显著改变其润湿性。此外,对固体基板来说,还可以对其进行各种表面修饰和处理,通过改变其表面物理化学结构来调整表面自由能,从而改善液相与固相的润湿效果,或使基板不同区域产生润湿性差异,约束液相在特定固相区域上的润湿行为,从而实现特殊的打印需求。本文归纳了近年来喷墨打印中界面润湿问题的相关研究进展,从墨水材料润湿性研究以及基板材料润湿性研究两个方面分析了界面润湿对喷墨打印效果的影响,总结了喷墨打印制备电子器件中的一些重要问题(如打印精度、表面形貌控制等)以及不同处理工艺的特点和优势。随着新时代微电子制造业提出更高集成度的要求,喷墨打印作为新兴制造技术,势必进一步提高其打印分辨率。在此背景下,润湿性研究作为关系到图形化的重要问题,仍旧是挑战与机遇并存。

Recently,printing electronic has attracted wide attention for its low cost,low energy consumption and simple process,which shows promising application prospect in microelectronics manufacturing.Inkjet printing is one of the most important methods of printing electronics allowing editing patterns through computer programming,which has always been a hot pot of research for its high speed and flexibility compared with vacuum process.During inkjet printing,deposition of ink on substrate involves interfacial wetting between ink and nozzle and between ink and substrate so that wetting can significantly affect graphing and function of printing patterns. From the aspect of interface,wetting in inkjet printing mainly refers to wetting between ink and substrate;from the aspect of surface,wettabilities of ink and substrate are two main issues of wetting in inkjet printing.One of the two issues is investigated to achieve expected printing results in general.Researches show that wettability of ink can evidently affect droplet jetting behavior,printing resolution and printing morphology,while wettability of substrate mainly affects quality of printing pattern graphing.By adjusting components of ink and substrate,surface tension of ink and surface free energy of substrate can be significantly adjusted.For substrate,it is also effective to make it under different kinds of surface treatment to change its surface physical or chemical structure,and thus change its surface free energy,or make its different regions obtain different wettabi- lities,which achieves special printing results by limitation of ink on particular region. In this review,recent progress in wetting of inkjet printing has been summarized and effect of interfacial wetting on printing results has been demonstrated from aspects of ink wettability and substrate wettability.Important questions such as printing resolution and morphology modulation have been proposed and characteristics and advantages of each methods have been discussed.As higher integration is demanded,it is sure that printing resolution needs to be further improved.As such an important role wettability plays in inkjet printing patterning,it still remains a challenge and opportunities.