A Technological Study Examining the Implementation of Sub-15 μm Finelines using Photoimageable Thick-Film Pastes on Low-Temperature Cofired Ceramics

This work details the fabrication of structures with feature sizes smaller than $15 \mu \mathrm{~m}$ on Micromax<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">™</sup> GreenTape<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">™</sup> 951 (Celanese) Low-Temperature-Cofired Ceramic substrates. A photoimageable silver paste, developed by Fraunhofer IKTS, Dresden Germany serves as conductor material in combination with photolithographical processing via laser direct imaging. Evaluations are being conducted focusing on stability and reliability of the process, utilizing optical characterization through laser scanning microscopy, scanning electron microscopy and 3D X-ray imaging. Furthermore, a comparison of the emerging photoimageable paste technology to conventional thin-film processing is made utilizing equivalent thin film structures. The implementation of high-resolution structures with feature sizes smaller than $15 \mu \mathrm{~m}$ in cofire-processing marks an important step in the miniaturization of thick-film-technology, facilitating future advancements in wiring and integration density.