高速产品应用中的铜箔表面粗糙度测量

Measurement of copper foil surface roughness in high-speed product applications

本文利用光学轮廓仪基于光干涉法原理研究了PCB“棕化”工序前后不同类型铜箔表面粗糙度的相关参数变化情况。同时讨论了在测量铜表面粗糙度时,一些传统测量参数的局限性和缺陷。因信号传输过程的“趋肤效应”,铜箔的粗糙度成为影响信号完整性的重要因素,且铜箔自身的粗糙度对信号的影响远大于PCB加工制程中带来粗糙度的变化已成为行业共识。因此对不同类型的铜箔在PCB加工制程后的粗糙度变化研究极为重要。本文将从铜箔粗糙度对信号影响的相关理论出发,再对比HTE铜箔和RTF铜箔在表面粗糙度上指标的异同,进而探讨不同铜箔在经过“棕化”工序后对信号的影响。

This article uses an optical profiler based on the principle of light interference to study the changes in the related parameters of the surface roughness of different types of copper foil before and after the PCB"Brown oxide"process.At the same time,the limitations and defects of some traditional measurement parameters in measuring the roughness of the copper surface are discussed.Due to the"skin effect"in signal transmission,the roughness of the copper foil has become an important factor affecting signal integrity,and it is an industry consensus that the impact of the inherent roughness of the copper foil on the signal is far greater than the changes in roughness brought about by the PCB manufacturing process.Therefore,it is extremely important to study the changes in the roughness of different types of copper foil after the PCB manufacturing process.This article will start with the relevant theory of the impact of copper foil roughness on signals,then compare the similarities and differences in the characterization of roughness between HTE copper foil and RTF copper foil,and subsequently discuss the impact on signals after different copper foils undergo the"browning"process.