Layer separation behavior in Ni-Zn-Cu ferrite green sheets with using poly (Butyl methacrylate) copolymer

The increasing use of NFC antennae in mobile phones has led to the increase in usage of ferrite sheets. In accordance with the trend for mobile terminals to be high intensity and to have thinner layers, and the need for high-strength materials that can withstand external shocks has increased In this study, the manufacturing process of the green sheet was optimized by using PVB and acrylate binder in the ferrite sheet fabrication process. In this process, a skin forms on the sheet surface in the acrylate binder drying process. This phenomenon was determined to be caused by non-uniform drying due to the high Peclet number of the acrylate binder. In order to resolve this skin problem in the drying process, change in T_g was induced by varying the plasticizer content in the binder. Its relationship with the layer separation phenomenon was defined. As a result, layer separation was reduced by increasing the P/B ratio, and fabrication of a uniform sheet was possible when the P/B ratio was 0.5. Also, layer separation was reduced when using a binder of lower molecular weight among the various acrylate binders. This result was in good agreement with the reported effects related to the Peclet number. Furthermore, changes in the binder distribution state within the sheet, binder adhesion condition, and mechanical properties of the green sheet were observed according to the P/B ratio variation.