Polydimethylsiloxane (PDMS) has widely appeared in different electronic and medical applications. The knowledge of the thermal properties of PDMS and especially its thermal conductivity is required while processing PDMS to design a particular device. In this paper measurement of the thermal conductivity of PDMS using the three omega method is presented at different temperatures. The three omega method has been chosen because of its ease of use and accuracy. It requires the fabrication of metallic lines which act as heaters and thermometers on the surface of the material under test. A different procedure is introduced in this paper through which the metallic lines are embedded in the surface of PDMS. Experimental results are then compared to Cahill's approximate solution and to the results obtained by numerical simulations using a finite element method.

a b s t r a c tThe three omega method has proven ability to accurately measure the thermal conductivity of solid and soft materials. Nevertheless, in the case of soft materials, the application of the three omega method is still challenging because up to now it generally requires techniques that are time consuming and costly, such as lithography. In this paper, we present an alternative for this kind of material based on inkjet printing technology. To evaluate the performance of this technique, polyimide samples have been prepared by photolithography and inkjet printing. We show that the thermal conductivities measured in both cases by means of the 3u method are very close; demonstrating that inkjet printing technology is a good candidate for characterization of flexible materials in terms of thermal conductivity. Besides the experimental study, a theoretical investigation based on an analytical approach, namely Cahill's method, and a numerical method based on a FEM tool is proposed.