Thermal analysis of the ceramic material and evaluation of the bonding behavior of silicon-ceramic composite substrates

Abstract

Thermal bonding of silicon and low-temperature cofired ceramics (LTCC) at sintering temperatures of 900 °C represents currently the standard process in silicon-ceramic composite (SiCer) substrate fabrication. We analyse the thermal behavior of the LTCC using thermogravimetric analysis, differential scanning calorimetry and laser flash analysis. The thermal decomposition could be identified with a mass loss of 24% in the temperature range up to 1000 °C what influences the thermal diffusivity with values from about 0.19 mm2 s−1 before thermal treatment to below 0.10 mm2 s−1 after thermal treatment. A specific heat capacity of 1–2 J (g · K)−1 is calculated. Further, an influence of low-temperature lamination of the LTCC seems to have an influence on the thermal behaviour. The sintering process was investigated with temperatures of 550 °C, 730 °C and 900 °C, applied pressures of 12.2 kPa and 6.1 kPa and intermediate wetting layers of TiO2 (normal deposition and oblique angle deposition). Optical observations, ultrasonic and scanning electron microscopy, and pull-tests are used to compare the properties of the sintered SiCer substrates. Whereas the sintering temperature has an obvious impact on the sintering behaviour of the LTCC, a direct conclusion of parameter variation on the bonding result was not observed.