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

Abstract

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.

Relationship between the Orientation of the (100) Crystal Plane and Elongation in Ultrathin Electrolytic Copper Foils

“…Generally, there exists a mechanical performance trade-off between the elongation and tensile strength of ECFs, indicating that an increase in elongation often comes at the expense of sacrificing tensile strength. 11 In the 8 μm ECFs, a strict positive correlation between the RTC of the (100) plane and elongation is not distinctly evident. Moreover, a law similar to that observed in the 6 μm ECFs is also present.…”

“…It can be observed that the RTC values of (100) and (111) are positively correlated with the elongation, while that of (110) is negatively correlated with the elongation. Generally, there exists a mechanical performance trade-off between the elongation and tensile strength of ECFs, indicating that an increase in elongation often comes at the expense of sacrificing tensile strength …”

“…The mechanical properties of ECF are intimately linked to its microstructural features, including grain size, grain morphology, twin, the size of grain boundaries, and the preferential orientation of crystal planes. − In polycrystalline materials, each grain exhibits a distinct crystal orientation and these orientations are randomly distributed. , However, in certain specific cases, due to the different growth rates of each crystal plane, the grains will be arranged to some extent according to certain specific orientations, exhibiting a phenomenon of preferred orientation of crystal planes at the macroscopic level, and it is called texture. , Copper possesses a face-centered cubic structure (FCC), and the prevalent textures in ECFs are (111), (100), and (110). Numerous studies reveal a connection between the mechanical properties of ECF and texture, but theoretical research regarding the intrinsic correlation between texture and mechanical properties is noticeably scarce. − …”

Effects of DPS on Surface Roughness and Mechanical Properties of Electrodeposited Copper Foils

“…[ 18,22,36 ,] The potential rapidly decreases by about 111.1 mV and then tends to be stable which the addition of HAP in the 1500 s. HAP can uniformly cover a large area of active sites on the cathode surface, which will hinder the discharge of Cu 2+ ions and increase the overpotential of copper reduction, indicating that HAP has a strong inhibitory effect. [ 37–39 ]…”

“…[18,22,36,] The potential rapidly decreases by about 111.1 mV and then tends to be stable which the addition of HAP in the 1500 s. HAP can uniformly cover a large area of active sites on the cathode surface, which will hinder the discharge of Cu 2+ ions and increase the overpotential of copper reduction, indicating that HAP has a strong inhibitory effect. [37][38][39] Add different additives (HAP 80 mg L −1 , HP 10 mg L −1 , DPS 8 mg L −1 ) to the VMS. form competitive adsorption on the copper surface, which plays a depolarizing role and accelerates the reduction of Cu 2+ ions.…”