This paper reports the peel strength and surface morphology of a Cu/Ni/PI structure flexible copper clad laminate (FCCL) based on polyimide (PI) according to the preprocessing output (plasma power). Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were used to analyze the surface morphology, crystal structure, and interface binding structure, respectively, of sputtered Ni, Cu, and electrodeposited copper foil layers. The surface roughness of the Ni and Cu sputtered layers and the crystal structure of the electrodeposited Cu layer changed according to the preprocessing output of PI. In the case of 200W preprocessing versus non-plasma processed groups, XPS showed increases in C-O and C=O bonding fractions. In addition, the non-plasma processed case showed a very low peel strength of 3.57 gf/mm, which was improved approximately three-fold to 10.5 gf/mm by plasma preprocessing. Considering the change in FWHM, which provides an estimate of the changes in the crystal structure of the deposited layers as well as those of the peel strength and plastic strain, the optimal preprocessing plasma power was estimated to be approximately 200 W.

No abstract

This study represents the results of an investigation of the peel strength and surface morphology according to the Ni sputtering power in producing Cu/Ni/PI structured flexible copper clad laminate (FCCL) using polyimide (PI). In order to analyze the surface morphologies of the sputtered Ni, Cu, and electrodeposited copper foil, and their crystal structure and interface binding structure, field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were used. The surface roughness of the deposited layers and the crystal structure of the electrodeposited Cu layers varied according to the Ni sputtering power. In the range of RF output of 100~400 W in the Ni deposition process, the metal layers deposited at a power of about 300 W showed a homogeneous surface morphology and also exhibited a high peel strength for polyimide. The peeling that occurred at the interface of NiPI in the specimen fabricated using an Ni sputtering power of 300 W was due to the fact that the peeling usually occurs inside the polyimide. In the results of the XPS analysis on the separated Ni surface, the peaks of C and N, which are the major elements in polyimide, showed higher levels compared to those observed under the other conditions.

This study examined the effect of copper and sulfuric acid concentrations on the surface morphology and physical properties of copper plated on a polyimide (PI) film. Electrochemical experiments with SEM and a four-point probe were performed to characterize the morphology and mechanical characteristics of copper electrodeposited in the composition of an electrolyte. The resistivity and peel strength were controlled using a range of electrolyte compositions. A lower resistivity and high flexibility were obtained when an electrolyte with 20 g/l of copper was used. However, a uniform surface was obtained when a high current density that exceeded 20 mA/cm 2 was applied, which was maintained at copper concentrations exceeding 40 g/l. Increasing sulfuric acid to > 150 g/l decreased the peel strength and flexibility. The lowest resistivity and fine adhesion were detected at a Cu 2+ : H 2 SO 4 ratio of 50:100 g/l.

No abstract