Characterization of laser-sintered thick-film paste on polycarbonate substrates

• Laser sintered thick-film Ag paste on polycarbonate substrates was investigated.
• Electrical and mechanical properties and microstructure were characterized.
• Good results were observed in the adhesion tests, but SEM revealed large voids.
• Conductivity up to 15 % of bulk silver was achieved.
• Some further tuning of process parameters is needed to manage the process window.

This paper presents the results of a study of laser-sintered commercially available thick-film silver paste printed on polycarbonate (PC) substrates. This material combination would not be possible to manufacture by normal processing routes, i.e. furnace sintering at a high temperature, due to the substrate's decomposition. With laser, however, localized heating enables the use of low-temperature materials such as PC. Furthermore, with laser processing, patterning can be done very accurately, thus enabling precise manufacturing of dimensionally sensitive components, e.g. RF structures and their fine tuning, while also enabling customization of components.Since silver has less resistivity than e.g. aluminum or copper, it is a good choice as a conductor material. In addition, a thick-film printed conductor as an alternative to more expensive printed electronics nanomaterials could enable more cost-effective electronic structures.In this work the electrical and adhesion properties and the microstructure of sintered thick-film silver paste were investigated. The results show that work is still needed to tune the process so that more energy can be used to heat the silver paste to induce its sintering while the substrate temperature is kept below its glass transition temperature. Still, conductivity of 15% of bulk silver was achieved with studied setup and parameters.