基于阴极往复运动的TGV电铸铜实心填充工艺

Copper Filling Process of TGV Electroforming Based on Cathode Reciprocating Motion

玻璃通孔(TGV)转接板因其具有优良的高频电学特性,在先进封装领域受到广泛关注。然而随着TGV深宽比的不断增加,采用传统的阴极定轴旋转式电铸工艺,其填充难度与成本将随之提高。为实现高深宽比TGV的无缺陷填充,减少电铸耗时和成本,提出一种基于阴极往复运动的TGV无缺陷镀铜填充新工艺。在仿真和实验的基础上,系统研究了阴极运动方式对TGV孔内电铸液传质、离子浓度、填充速率的影响。仿真和实验结果均表明,采用阴极往复运动能有效地保证TGV孔内各处离子浓度分布的均匀一致性,减缓浓差极化,从而提高沉积速率及其上限值。在不含任何添加剂的体系中,同等沉积电位条件下平均填充速率从阴极定轴旋转式电铸工艺的6.1μm/h提高至9.2μm/h。当电位为0.5 V时,阴极往复运动方式下平均填充速率达到45.2μm/h,且电铸铜填充层中未发现孔隙缺陷。这为在无添加剂电铸铜体系中实现高深宽比TGV的无缺陷电铸铜填充提供了一种可行的低成本方案。

Through-glass via(TGV)has attracted much attention in the field of advanced packaging due to its excellent high-frequency electrical properties.However,as the aspect ratio of TGV increasing continously,the difficulty and cost of filling that using the traditional fixed axis rotary cathode electroforming process will increase.To achieve defect-free filling of TGVs with high aspect ratios and to reduce the electroforming time and cost,a novel process for defectfree filling of TGV using cathode reciprocation motion was proposed.Through simulations and experiments,the effects of the cathode motion mode on the mass transfer,ion concentration,and filling rate of the electroforming solution in the TGV holes were systematically investigated.The simulation and experimental results show that the reciprocating motion of cathode can effectively ensure the uniform distribution of ion concentration in the TGV holes,slow down the concentration polarization,and increase the deposition rate and its upper limit value.In the solution without any additives,the average filling rate increases from 6.1μm/h in the cathodic fixed axis rotary electroforming process to 9.2μm/h under the same deposition potential,and the average filling rate can reach 45.2μm/h in the cathodic reciprocating mode at a potential of 0.5 V,and no pore defects are found in the Cu filling layer.The study provides a feasible lowcost solution to achieve defect-free filling of TGVs with high aspect ratios in additive-free electroforming copper system.