A new planar micro-transformer having sandwich spiral coil structure is fabricated using MEMS micro-fabrication technique. Stack interwinding coil is designed to achieve high coupling and higher winding number at relatively small coil area. In this work, stack sandwich interwinding coil structure is fabricated by bonding the substrates of the coil at connection pads using conductive epoxy material. This method replaces the use of conventional via connections that cause the most problem of current conductance in planar structures. The inductance of fabricated coil are measured at wide range of operating frequency using cascade GSG probe. The results show that the proposed technique is an alternative way in fabricating a simple and cost effective 3-dimensional structure of stack micro-transformer.