| The increasing electronic system capacity brought with a great deal of factors that contribute to signal integrity (SI) during the manufacture of printed circuit board (PCB)interconnect structures came to the fore sequentially. Among those influence factors,surface roughness of transmission line had become one of the most active research problems.In this work, basing on the transmission line model and the lossy transmission theory,the surface roughness of PCB transmission line was taken into accounted for principal research, the primary and secondary factors contribute to the surface roughening result during the fabrication of PCB were analyzed, the effect of PCB copper surface roughening on signal integrity was discussed. The study deployed from following aspects:The impact of the copper foil surface roughness on transmission loss was analyzed according to the lossy transmission line theory and skin effect. The relationship between the copper foil surface roughness and the transmission loss factor was simulated with Hammerstad equation. The contribution of stripline surface roughness to signal transmission was emulated and dissected by SI9000 software, which provided the theoretical basis for the follow-up experimental research work.The influence of copper foil type on the signal transmission of stripline was analyzed.It was concluded that both the shiny and matt side roughness of copper foil determined the quality of signal transmission by comparing the surface roughness and roughening result of different types of copper foils.The roughening result of the inner-layer pretreatment and lamination pretreatment process was compared by orthogonal experiment. The result shows that the primary influence factors of stripline signal transmission in copper foil roughening process was brown oxide.The effect of brown oxide formulation on stripline signal transmission and the electrochemical mechanism of different brown oxide formulation were studied by comparing the roughening result of different formulation. The transmission line manufactured by Foumula H owned excellent electrical and reliable performance suit for high speed products. The primary and secondary factors of stripline signal transmission in process parameter of brown oxide were concluded through orthogonal experiment and variance analysis. The optimum parameters of stripline that owned the best electrical performance was obtained: low level concentration, brown speed 4m/min, brown temperature 30?, and the most balanced performance between reliability and electrical performance was obtained: medium level concentration, brown speed 3.5m/min, brown temperature 40?. The stripline signal transmission as a function of brown oxide speed were studied at the end, results show that the insertion loss of stripline decreased by an average of 0.013dB/inch at 12.9GHz, the peel strength decreased by an average of 0.03N/mm with the brown speed each increase 0.5m/min. |
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