新型流磁巨量转移用永磁偏置定位磁针

Permanent magnet bias positioning magnetic needle for novel fluid magnetic mass transfer

针对现有Mini/Micro LED巨量转移技术转移效率及自组装转移良率普遍较低,提出一种“永磁+电磁”磁场耦合的新型流磁巨量转移用定位磁针。为实现磁针上表面对芯片的精准抓取,设计了电磁偏置线圈,精准控制磁针上表面的磁力,利用磁路分析法建立磁针结构与磁针针尖的数学模型,获取影响磁针上表面气隙磁密的结构参数,借助有限元法对结构参数进行优化设计。优化后磁针上表面的Bmax由最初的57 mT提高至68 mT,相较初始方案增加了19.2%;峰谷变化率δ由50.8%提升至70.5%,两大指标参数均优于原方案。基于优化结果研制了一套永磁偏置定位磁针装置,并进行气隙磁密测试与芯片转移效果测试。结果表明,优化后的磁针上表面的磁密值Bmax为60 mT,峰谷变化率δ为66.6%,可在1 min内实现上千颗芯片的吸引固定,满足巨量转移精准抓取芯片的要求,可配合流体实现芯片的巨量转移过程,提升了自组装巨量转移技术的效率。

To improve the efficiency and yield of Mini/Micro LED mass transfer and self-assembly,a new positioning magnetic needle using a permanent magnet+electromagnetic magnetic field coupling is pro⁃posed.An electromagnetic bias coil is designed to precisely control the magnetic force on the needle's up⁃per surface for accurate chip grasping.Magnetic circuit analysis establishes a mathematical model for the magnetic needle structure,identifying parameters affecting the magnetic flux density in the air gap.The fi⁃nite element method optimizes these parameters,increasing the Bmax on the needle's upper surface from 57 mT to 68 mT,a 19.2%improvement,and enhancing the peak-to-valley variation rateδfrom 50.8%to 70.5%.Based on these optimizations,a permanent magnet bias positioning magnetic needle device was developed.Tests show the optimized needle achieves a Bmax of 60 mT and aδof 66.6%,efficiently securing thousands of chips per minute.This meets precise chip grasping requirements and enhances the yield of self-assembly mass transfer technology when combined with fluid.