Enhancing Surface Roughness and Tensile Strength of Electrodeposited Copper Foils by Composite Additives

It is urgent to develop copper foils with low surface roughness, high tensile strength, and good thermal conductivity in electronic equipment communication. Herein, the effect of three single additives (gelatin, polyacrylamide, and thiourea) and two composite additives (gelatin–polyacrylamide and thiourea–polyacrylamide (Tu‐PAM)) on the surface roughness, tensile strength, and thermal conductivity of copper foils fabricated by direct current electrodeposition is investigated. The results show that when Tu‐PAM additives are added to the electrolyte, the –NH2 in the composite additive forms a complex with Cu2+ in the electrolyte, which increases the deposition current density, accelerates the formation of crystal nuclei, and reduces the size of the deposited particles. The size of the deposited particles is smaller, and the surface of the copper foil is flatter than that when the additive is added alone. The surface roughness, tensile strength, and thermal conductivity of copper foils are 1.506 ± 0.147 μm, 258 ± 20 MPa, and 356 ± 18 W m−1 k−1, respectively. It is revealed that the ionic interaction and the deposited particle size play an important role in enhancing surface roughness and tensile strength. When thiourea–polyacrylamide (Tu‐PAM) additives are added to the electrolyte, the size of the deposited particles of copper foils is smaller than that when the additive is added alone, simultaneously enhancing surface roughness (1.506 ± 0.147 μm) and tensile strength (258 ± 20 MPa) of copper foils.