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Purpose The purpose of this paper is to establish an accurate model to quantify the effect of conductor roughness on insertion loss (IL) and provide improved measurements and suggestions for manufacturing good conductive copper lines of printed circuit board. Design/methodology/approach To practically investigates the modified model of conductor roughness, three different kinds of alternate oxidation treatments were used to provide transmission lines with different roughness. The IL results were measured by a vector net analyzer for comparisons with the modified model results. Findings An accurate model, with only a 1.8% deviation on average from the measured values, is established. Compared with other models, the modified model is more reliable in industrial manufacturing. Originality/value This paper introduces the influence of tiny roughness structures on IL. Besides, this paper discusses the effect of current distribution on IL.

A novel additive system comprising bis-(sodium sulfopropyl)-disulfide, polyethylene glycol and hydroquinone (HQ) was developed and investigated to achieve high rate copper electrodeposition at high temperature. HQ, as the key additive compound in this system, refines the Cu grain, makes the coating surface bright and smooth at high current density. The underlying mechanism of the additive-assisted electroplating was investigated through electrochemical, morphological characterizations and molecular dynamics simulation. Nanocubical copper particles were found through chronoamperometry tests, which explains the fine crystalline Cu grains and the bright coating surface. Additionally, the formation of the nanocubical copper particles is caused by the different adsorption energies of HQ on (311), (111) and (220) crystal faces and further leads to a strong suppression on the (220) orient crystal faces. Moreover, the electroplating results of through-holes illustrate the feasibility of this additive system in practical applications.