the present invention relates to switched - mode power supply module and discloses a ferrite mosaic and a magnetic core structure for passive substrate for switched - mode power supply module . the ferrite mosaic includes a supporting plate and numbers of ferrite units stuck on the supporting plate , with each ferrite unit being rectangular . wherein the ferrite mosaic comprises air - gaps defined between the ferrite units and ferrite glue polymer composites cured in air - gaps , and the magnetic core structure is finished after cutting , laminating and assembling said ferrite mosaics .