The Edge Effects of Au Films on Electrical and Mechanical Properties

With the development of three-dimensional high-density integration, low-temperature co-fired ceramic (LTCC) technology has become an important substrate platform for electronic packaging. However, screen-printed Au films on LTCC substrates often contain boundary roughness, local thickness variation, pores, and particle-packing non-uniformity caused by the printing process. These features may affect both the macroscopic resistivity of printed patterns and the local mechanical response of the film. In this study, edge-related structural non-uniformity in screen-printed Au/LTCC films was evaluated using SEM observation, macroscopic resistivity–temperature fitting, nano-indentation, XRD, and nano-scratch testing. The resistivity results show that the stripe pattern has approximately 10–13% higher resistivity than the grid patterns within the measured temperature range, indicating a geometry-dependent electrical response. Nano-indentation results reveal large spatial dispersion in reduced modulus and hardness, and statistical analysis shows that differences among annealing conditions are not significant at the 0.05 level when indentation data alone are considered. Therefore, nanomechanical data are treated as an indirect structural indicator rather than a direct proof of local electrical uniformity. Among the investigated temperatures, 200 °C provides a favorable balance of local hardness, scratch resistance, and microstructural stability, whereas 300 °C should be interpreted cautiously because the higher scratch load is not supported by direct post-scratch failure analysis. Overall, the results provide a cautious but clear structure–property correlation for screen-printed Au/LTCC conductors and identify 200 °C as the preferred annealing condition among the investigated temperatures. These results provide practical guidance for evaluating structural non-uniformity in screen-printed Au/LTCC conductors.