Effect Of Discrete Cr Nano-Nuclei On The Stripping Property Of Ultra-Thin Copper Foil By Electrodeposition

Copper foil is widely used in the field of electronics because of its superior electrical conductivity,thermal conductivity and ductility.With today’s mobile communication technology is moving towards the era of high frequency and high speed digital information transmission,the global electronic components are developing in the direction of miniaturization,light quality and multi-function,which puts forward higher requirements for the thickness and performance of copper foil.China’s high-end copper foil production technology independent research and development is limited,long-term dependence on foreign imports.In order to improve the production technology of domestic copper foil and adapt to the upgrading of electronic products,it is of great practical significance to study the preparation of high-performance ultra-thin copper foil.To prepare high-performance ultra-thin copper foil with low roughness,high tensile strength,and low resistivity,the selection of a stripping layer is crucial.In this study,a layer of uniformly distributed discrete Cr nano-nuclei was electrodeposited on the substrate,with discrete Cr nano-nuclei as the stripping layer,successfully prepared ultra-thin copper foil with a thickness of 1.34μm.The effects of different Cr nuclei density on the stripping properties,roughness,resistivity,and tensile strength of copper foil were further investigated.The experimental results show that:With the increase of Cr nuclei density,the easier the copper foil is to strip,the better the stripping performance.The roughness of copper foil gradually decreases with the increase of the Cr nuclei density.When the nuclei density is15.7×10⁹/cm²,the roughness is the least,at 0.21μm.Compared with the Cr nuclei density of2.61×10⁹/cm²,the roughness is reduced by 138%;The resistivity of copper foil increases with the increase of the Cr nuclei density.When the Cr nuclei density is 15.7×10⁹/cm²,the resistivity is the largest,4.95×10^-7Ω·m,which is 9.2%lower than that of the Cr layer with conventional electrodeposition thickness of the Cr layer with conventional electrodeposition thickness of 0.67μm,and 15.8%lower than that of the potassium dichromate layer;And its tensile strength exceeds 248.80 MPa.To further study the process parameters:The influence of process parameters such as discrete Cr nano-nuclei density,Cl^-mass density,current density,Cu SO₄mass concentration and temperature on the roughness,resistivity and tensile strength of ultra-thin copper foils,The L16（4⁵）orthogonal test is established,and the largest factors affecting the roughness,resistivity and tensile strength are respectively:discrete Cr nano-nuclei density,discrete Cr nano-nuclei density and current density.Using matrix analysis,the combined effects of process parameters on roughness,resistivity and tensile strength are:discrete Cr nano-nuclei density>current density>Cl^-mass concentration>temperature>Cu SO₄mass concentration;The optimal orthogonal test scheme is:Cu SO₄mass concentration of 100 g/L,current density of 5 A/dm²,temperature of25℃,discrete Cr nano-nuclei density of 15.7×10⁹/cm²,and Cl^-mass concentration of 60 mg/L.Using the optimal experimental protocol,the implementation results show:The copper foil with a thickness of 1.343～1.348μm was stripped,the surface roughness Ra is 0.12μm,the resistivity is 5.21×10^-7Ωm,and the tensile strength is 496.26 MPa.All three indexes can meet the design requirements,which verified the feasibility of determining the optimal plating composition of electrodeposited copper foil and process parameters by orthogonal experimental matrix method.