为提高产能, 笔记本电脑超高级超维场开关(HADS)产品的聚酰亚胺(PI)膜涂布方式从辊涂的感光树脂转印版(APR版)转印变更为喷墨打印, 涂布方式的变更造成了PI液滴无法填充到高段差钝化层(PVX)过孔内, 进而在过孔周围PI液堆积产生宏观“线Mura”不良。我们通过变更产品设计与工艺参数调整以及工艺过程优化, 设法降低或消除不良产品, 使良率满足量产需求。首先, 通过变更钝化层掩膜版使得钝化层过孔和Com走线有一定偏移量(钝化层半过孔), 半过孔设计利于PI液通过半过孔缺口设计进入钝化层过孔内。为了减小钝化层过孔尺寸和数量对PI液扩散的不利影响, 钝化层过孔周期从1/3变更为1/6,过孔尺寸从5.7 μm增大到7.5 μm。钝化层掩膜版设计的变更极大改善了PI液进入过孔内, 将“线Mura”不良率从100%降为15%。其次, 从提高PI液滴涂布均匀性方向出发, 将喷墨打印涂布方式从1次涂布变更为2次涂布, 2次涂布的叠加效果使相邻液滴间扩散时间更久, 液滴间距更小, 膜厚更均匀, 使“线Mura”不良率从15%降为1%。再次, 通过改变PI液滴在过孔周围走线的扩散方向来提高扩散均匀性, 通过将喷墨打印机台角度从0°变为2°, 进一步使“线Mura”不良率从1%降为0.2%。

To improve the production capacity, the polyimide (PI) film coating method of High Advanced Dimension Switch (HADS) products is changed from APR transfer printing (Roller Coater) to inkjet printing(Inkjet Printer). The change of the coating method caused PI droplets can not to fill into the PVX (passivation SiNx) via hole because of its high thickness, and the PI solution accumulated around the PVX via hole caused “line Mura” issue. By changing product design and process parameter adjustments and process optimization, we try to reduce or eliminate defective products ratio, so that yields could meet the demand for mass production. Firstly, we change the PVX mask to make a shift between PVX via hole and Com electrode (half via hole on metal). The design of half via hole helps PI solution to enter PVX via hole. In order to reduce the adverse effect of PVX via size and number on PI solution diffusion, the PVX via hole period is changed from 1/3 to 1/6, and the via hole size is changed from 5.7 μm to 7.5 μm. The design of the PVX mask has greatly improved the entry of PI solution into via hole, which reduces the failure rate from 100% to 15%. Secondly, to improve the uniformity of PI thickness, we change the coating frequency of inkjet printer from 1 time to 2 times, which improves the diffusion time between adjacent droplets, then the droplets spacing is smaller and the film thickness has higher uniformity, its failure rate reduces from 15% to 1%. Thirdly, we improve the diffusion uniformity by changing the diffusion direction of PI solution, and by changing the coating direction of inkjet printer from 0° to 2°, the failure rate is reduced from 1% to 02%.