In this paper, a technology based on thin flexible polyimide substrate (Kapton) to develop antennas for millimeter wave wireless power transmission is presented. Firstly, we characterize the Kapton polyimide (relative permittivity and loss tangent) by using a ring resonator method up to V band. A 60 GHz patch antenna is designed, fabricated, and measured to validate our technology. Crossed dipoles array antennas at Ku band and K band for energy harvesting are also designed, fabricated and measured. Then a prototype of crossed slot dipole antenna at V band is proposed. Finally, a resistivity characterization of Au bump used in flip chip packaging is done, which leads us one step further towards a heterogeneous integration on flexible substrate of different components for Wireless Sensor Network nodes.