柔性屏COF弯折结构的正交试验优化设计

Optimization of flexible-screen COF bending structures by orthogonal design of experiment

OLED(Organic Light-Emitting Diode)屏幕COF(Chip on Film)连接过渡区的金属层在模组弯折阶段和可靠性验证阶段容易发生断裂,导致屏幕显示异常。本文采用试验设计(Design of Experiment,DOE)方法,以弯折成型状态和可靠性状态下的金属层应力最小作为试验指标,以泡棉厚度、泡棉偏移、金属包覆层(Metal Cover Layer,MCL)厚度和U型膜偏移作为影响因子,设计L9(34)正交试验方案,使用有限元方法对9组试验方案进行数值模拟和分析,并进行弯折成型和可靠性状态下的试验验证,最终获得了最优组合方案。有限元方法和试验结果表明,U型膜贴附偏移量对COF区的金属层弯折应力的影响最大,其次是泡棉厚度,再次是MCL厚度和泡棉贴附偏移量。最优组合方案在弯折成型和可靠性状态下皆具有最小的金属层应力,其值分别为57 MPa和523 MPa。最优组合方案的弯折成型和可靠性试验达到了100%的产品良品率,满足设计和生产要求。

Fracture often occurs in the metal layer of the COF(Chip on Film)transition zone when OLED(Organic Light-Emitting Diode)screens are at the module-bending stage and the reliability verification stage.Based on the design of experiment(DOE),this paper uses a L9(34)orthogonal test scheme to optimize four influence factors:the thickness of the foam,the offset of the foam,the thickness of the MCL(Metal Cover Layer),and the offset of the U-film.Two indexes,the metal layer stress in modulebending stage and the reliability state,respectively are employed and optimized to be minimal.In the L9(34)orthogonal DOE test scheme,finite element method are used to analyze nine groups of COF zones with different influence-factor combinations,and experimental tests are also carried out for verification.The results show that the U-film attachment offset has the greatest influence on the bending stress of the COF metal layer,while the foam thickness has a weaker influence,and the MCL thickness and foam attachment offset have the least influence.For the optimal influence-factor combination,both the module-bending stage and the reliability state have the least metal layer stress,with values of 57 MPa and 523 MPa,respectively.Compared with other combinations,the optimal influence-factor combination have 100%of the yield rate during the experimental tests,satisfying design and production requirements.