Investigation of thick film electronic packaging materials in dynamic contact with artificial body fluids

Thick film electronic packaging materials based on Ag-Pt (C4729), Ag-Pd (C2030) and Pt (LPA 88-11) conductive pastes were tested on their properties under the influence of flowing artificial blood plasma (ABP), artificial cerebrospinal fluid (ACF) and physiological solution (0.9% NaCl) for the evaluation of their biostability grade in vitro. The degradation effects were studied by means of microscopic investigations, measurements of a surface free energy, determination of mass losses and analysis of a chemical content. Materials were stressed in fluid mediums during the periods of up to 60 days at the temperature of 60degC, pH value of (8-10) and flow velocity of 0.15 m/s in systems with a directional flow and by an unidirectional fluid circulation. Based on SEM-EDX analysis, formation of silver sulphide (Ag2S) in form of yellow-brown precipitate has been observed on Ag-Pt surfaces, which were influenced by ABP and ACF; a partly dissolution of Zn and Na particles from pastes glass matrix was supposed. No significant alterations in chemical content were revealed in case of interactions between Ag-Pt thick films and 0.9% NaCl. Ag-Pd surfaces were more stable due to formation of the protection palladium oxide (PdO) film. A very good stability have shown Pt-layers.