Effect of internal silver conductor on heat spreading capability of LTCC membrane

LTCC membranes are used as substrates of screen printed unimorph deformable mirrors. A high piezoelectric stroke is attributed to thin substrate materials. The application of deformable mirrors with high laser loads calls for a large heat spreading capability of the deformable unimorph mirrors. A large heat spreading capability is attributed to high thermal conductivity of the materials that is not allocated by LTCC. The present paper reports on the effect of internal silver conductor (DuPont 6145) on the heat spreading capability of the LTCC membrane. Therefore, internal silver conductor is applicated into a 570 µm thin membrane on a diameter of 49.8mm. The optical absorption of plain LTCC membranes and membranes with internal metallization is characterized by an Ulbricht sphere. Membranes with internal silver conductor and a reference sample without internal metallization (plain LTCC) are loaded with a laser beam. The absorbed laser power heats the LTCC membrane. We investigate the temperature increase upon one-Watt laser loading and prove a 37% lower setting maximum temperature (Tmax) for membranes with internal silver conductor compared to plain LTCC membranes. The characteristics of temperature over time are similar to the charging of a capacitor. The time constant for the internally metallized and plain LTCC membrane at same peak temperatures are similar. These results show the potential of internal silver conductor to increase the heat spreading capability of LTCC membranes.