The no-clean flux-residues pose a high reliability risk, thus controlled strictly in the modern electronics assembly industry. A series of customized Surface Insulation Resistance (SIR) Experiments and AC impedance analysis under various test patterns demonstrate the dramatic impact of the partial activation of the fluxes unevaporated solvents, and non-decomposed activators on the reliability of the final assembly. Although the mainstream no-clean pastes and liquid fluxes are qualified under all the standard SIR and electrochemical migration (ECM) reliability tests, the solder mask filled SIR patterns are more realistic and the tests results more accurate. The spaces are filled with solder mask thus the ionic migration analysis is more complex. From this perspective, we demonstrate a thorough examination of these more realistic structures with classic DC SIR method and AC impedance measurements. This study examined the impact of no-clean flux residues on capacitance and resistance in case of solder mask filled comb patterns.

19^th IMEKO TC10 Conference "Measurement for Diagnostics, Optimisation and Control to Support Sustainability and Resilience"