Improving high-speed signal transmission loss by low conductor surface roughness

The effect of the conductor surface roughness for high-speed signal transmission on package substrate is analyzed. When skin depth becomes smaller than surface roughness at high frequency, the loss of surface roughness becomes important. In this paper, the transmission line patterns are designed on substrate of different conductor surface treatment processes for measuring and comparing the performance. In the GB/s regime, the accurate modeling of conductor losses is important to successfully simulate high-speed serial link designs. The Huray model [1] is used in 3D full-wave solver and good correlation exists between measurement and simulation. Finally, current distribution of different layout design is also studied to reduce surface roughness effect.