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过去,在金属介质上进行倒装芯片组装时,如何在有凹槽空间的介质上实现焊膏印刷成为一大挑战。主要瓶颈是限流器有限区域内的模腔(深度小于2.0mm)。一种做法是印刷焊膏时使用多孔焊膏喷嘴,其带来的问题在于喷嘴堵塞会造成焊膏量不一致。而喷嘴口的多重设计和焊膏尺寸的一致性对于提高焊膏性能至关重要。焊膏印刷技术已经使用多年。然而,传统的二维模版技术主要适用于平面介质。最近,相关模版制造商研发了一种新的模版技术,能够在小于100μm的凹槽上印刷。最新的研发成果是使用3D模版,配合一个专门设计的刮刀,以实现在受力变形的有限空间上良好的印刷效果。本文研究的是采用3D模版在凹槽深300μm、小于2.0mm区域上实现焊膏印刷的技术,该技术可在有限空间内实现一致的焊膏印刷效果;此外,本文还研究了在间隔400μm、凹槽深150μm的区域上实现焊膏印刷的技术。3D模版可帮助焊膏印刷在凹槽空间内更好地控制焊膏质量。以下几个因素会影响焊膏印刷质量:焊料类型、模版布局、刮刀类型、凹槽形态及深度,此外还包含印刷参数。上述因素的相互作用使得在凹槽上进行连续的焊膏印刷成为可能。
In the past, how to achieve solder paste printing on a grooved medium was a challenge when flip-chip assembly on metal media. The main bottleneck is the cavity within a limited area of the flow restrictor (depth less than 2.0 mm). One approach is to use a porous solder paste nozzle when printing pastes, which poses the problem that nozzle jams can result in inconsistent amounts of solder paste. The multiple design of the nozzle orifice and the consistency of the solder paste size are crucial for improving the solder paste performance. Solder paste printing technology has been used for many years. However, the traditional two-dimensional template technology is mainly suitable for planar media. Recently, the relevant stencil maker has developed a new stencil technique that can print on grooves smaller than 100 μm. The latest research and development is the use of 3D templates, with a specially designed scraper, in order to achieve a good deformation in the limited space on the printing effect. In this paper, we study the technology of using 3-D stencil to achieve the solder paste printing in the area of 300μm and less than 2.0mm in the groove, which can achieve consistent solder paste printing effect in a limited space. In addition, The technology of solder paste printing is realized in the area of 150μm depth. 3D templates help solder paste printing to better control solder paste quality in the recessed space. The following factors can affect solder paste print quality: solder type, stencil layout, doctor blade type, groove geometry and depth, as well as printing parameters. The interaction of the above factors makes it possible to perform continuous paste printing on the grooves.