1.0mm BGA/0.20mm过孔背钻走2线工艺技术研究

The study on the process of back drilling in 1.0 mm/0.20 mm via BGA with 2 trace routing

随着通讯设备高频高速的发展需要和信号传输损耗的要求,在板级设计上,承载芯片的BGA布线设计也发生了巨大的改变,仿真结果表明在0.20mm过孔相比0.25mm过孔,并设计背钻以减小过孔stub带来的"残桩效应",对减少孔链路损耗越有利和更能保证信号的完整性。随着布线空间越来越紧张,BGA背钻孔间设计走线,可以减少出线层数,降低PCB厚度,节省成本,如果内层走双线的话(线宽/间距:0.1/0.1mm),相比单线,抗干扰性好,同时信号损耗也小,有利于提高传输信号质量。但这样以来,在PCB加工方面,背钻对准度和背钻堵孔将是最艰难的一大挑战。文章将针对背钻堵孔和背钻对准度进行了系统研究和改进,开发成熟的技术能力以满足批量生产的要求。通过在常规流程上通过优化钻孔方式、钻尖角和盖板类型等,结果表明在增加预背钻、110°钻尖角和铝片盖板可以大幅度降低堵孔的问题。针对对准度问题,通过研究不同的定位方式和钻机,结果表明在采用PCB单元内定位方式,采用CCD钻机加工背钻孔的背钻对准度能力最好,可以满足≤0.076mm,采用常规PCB内定位和普通钻机的方式,辅助层间对准度和通孔精度的控制,可以满足1mm BGA出2线的对准度的要求。

Along with the needs of communication device at a high frequency and high speed development and the requirements of the signal transmission loss, in board level design, the BGA which support the chip layout design also had a tremendous change, the simulation results show that compared with 0.25mm in 0.20mm via, and the design of back drilling to reduce stub brings ＂＂ stump effect ＂, which can be beneficial to reducing the loss and can guarantee the signal integrity. As the layout space is becoming more and more limited, the BGA back drilling design with line routing can reduce layer counts, cut down the thickness of PCB, save the cost, if tracking two lines in the tuner （width/spacing： 0.10/0.10mm）, compared with the single line, it can be of good anti-interference performance, and low signal loss, is beneficial to improve the signal quality. But such since, in PCB processing, back drilling registration and back drilling ph, gging hole will be the most difficult challenges.This paper will elaborate back drilling registration, back drilling hole plugging system research and improvement, development of sophisticated technical capabilities to meet the requirements of mass production, by optimizing back drilling method, drill bit angle and the entry board on typical process, it shows that pre-drill before back drilling, 110 degree angle drill bit ＆ aluminum entry board can reduce lhe issue of plugging hole. Through the research of different alignment system design ,the results showed that using internal localization design, using CCD drilling machine processing, back drilling registration capability can meet the≤0.076mm, using internal localization and normal machine with layer registration and first hole position precision controlling can meet requirements for the design trend.