玻纤效应对不确定度的影响研究

The influence of glass fiber effect on uncertainty

随着高速互联链路信号传输速率的不断提高,作为器件和信号传输的载体,印制电路板(PCB)的信号完整性对通信系统的电气性能有着至关重要的影响。Intel对信号损耗不确定度定义为,可以提供实时定量的测量质量反馈,也可用于监测测量异常。不确定度的产生在某种程度上可以理解为信号传输时出现传输偏差,在一组差分线进行信号传输时,信号同时从发送端输出,到达接收端的时间差,就是传输的时间差。PCB叠层中的介质层是由环氧树脂和玻纤布交织组成,而玻纤布是经向纱和纬向纱组成,经向和纬向交织的间隙会导致介电常数在局部发生变化,这种局部变化的现象就是玻纤效应。玻纤布和环氧树脂的介电常数相差较大,因此信号在传输时随走线位置改变而出现不确定度影响。本文从不同规格的玻纤布的玻纤效应出发,分析了不同玻布类型、不同材料和不同布线方式对不确定度的影响程度,提出了减少差分线不确定度的处理方法,可以为后续高速信号传输的选材及设计提供数据参考。

As the signal transmission rate of high-speed interconnected links continues to improve,the signal integrity of printed circuit boards(PCBS),as the carrier of devices and signal transmission,has a crucial impact on the electrical performance of communication systems.Intel defines signal loss uncertainty as providing real-time quantitative feedback on measurement quality,and can also be used to monitor measurement anomalies.The generation of uncertainty can be understood to some extent as the transmission deviation when the signal is transmitted.When the signal is transmitted by a group of difference lines,the signal is output from the sending end at the same time,and the time difference to the receiving end is the transmission time difference.The medium layer in the PCB lamination is composed of epoxy resin and glass fiber cloth interwoven,and glass fiber cloth is composed of warp yarn and weft yarn,warp and weft interwoven gap will lead to local changes in the dielectric constant,this local change phenomenon is the glass fiber effect.The dielectric constant of glass fiber cloth and epoxy resin is very different,and the uncertainty of signal will appear when the signal is transmitted.Based on the glass fiber effect of glass fiber cloth of different specifications,this paper analyzes the influence of different types of glass fiber cloth,different materials and different wiring methods on the uncertainty,and puts forward the processing method to reduce the uncertainty of difference line,which can provide data reference for the material selection and design of high-speed signal transmission.