Method of preparing conductive magnetic composite sheet and antenna device

A method of preparing a conductive magnetic composite sheet, the method comprising:

• preparing a magnetic sheet comprising a magnetic powder and a binder resin;
• stacking a first conductive foil, the magnetic sheet and a second conductive foil;
• and
• applying heat and pressure to the obtained stack to bond the first conductive foil, the magnetic sheet and the second conductive foil together,
• wherein the magnetic sheet comprises 70 wt % to 90 wt % of the magnetic powder, and 6 wt % to 12 wt % of a polyurethane-based resin, 0.5 wt % to 2 wt % of an isocyanate-based hardener, and 0.3 wt % to 1.5 wt % of an epoxy-based resin, as the binder resin, based on the total weight of the magnetic sheet.

A method of preparing an antenna device, the method comprising:

• preparing a magnetic sheet comprising a magnetic powder and a binder resin;
• stacking the magnetic sheet and a first conductive foil;
• applying heat and pressure to the obtained stack to bond the magnetic sheet and the first conductive foil;
• and
• etching the first conductive foil to form an antenna pattern therein,
• wherein the magnetic sheet comprises 70 wt % to 90 wt % of the magnetic powder, and 6 wt % to 12 wt % of a polyurethane-based resin, 0.5 wt % to 2 wt % of an isocyanate-based hardener, and 0.3 wt % to 1.5 wt % of an epoxy-based resin, as the binder resin, based on the total weight of the magnetic sheet.