Rapid Thermal Characterization of Materials with Ultra-High Resolution of Droplet Size Specimens using the Three-Omega Method

Measuring the thermal conductivity can be challenging, especially for liquids or pastes of small volumes. We developed a measurement chip which is suitable for a fast, accurate and convenient determination of the thermal conductivity and diffusivity of droplet size specimens. The measurement method is based on an extension of the 3-omega measurement technique, the so-called bidirectional 3-omega method. A characterization chip with through-glass vias has been developed, allowing for convenient sample positioning and insertion of the chip into the measurement setup. A very thin passivation layer fabricated by atomic layer deposition enables measuring electrically conductive samples while maintaining good thermal transport through the layer. Sample volumes down to 0.02 mm³ are sufficient for accurate measurements. The measurements can be performed within few minutes. Measurements of the thermal conductivity of different thermal interface materials, like pastes and pads, and several liquids and polymers were performed and compared with results obtained using a standard steady-state technique and literature values. The results obtained with both methods agree well within measurement uncertainty.