Skin effect on signal integrity As the signal transmission speed becomes higher and higher, the operating frequency becomes higher and higher, and the current tends to flow more and more on the surface. The relationship between the operating frequency and the skin depth is as follows: The following is a comparison table of frequencies and skin depths of copper commonly used in current high-speed products: In terms of PCB design, it is usually necessary to reduce the roughness of the copper surface due to signal integrity considerations. However, if the roughness is too low, the bonding force between copper and P.P. of the PCB will be insufficient, thus affecting its reliability. 趨膚效應對訊號完整性的影響 由於訊號傳輸時速度愈高，操作頻率就愈高，而電流就會愈趨向導體表面流動，其中操作頻率與趨膚深度的關係如下： 以下列舉一些目前高速產品常用的頻率與銅材質趨膚深度的對照表： 以PCB設計而言，通常因為訊號完整性考量需要降低銅表面的粗糙度，但是粗糙度太低也會造成PCB的銅與P.P.結合力不足，進而影響其可靠度。