Influence of the alkalis (KOH, NaOH), acids (HNO<sub>3</sub>, HCl, H<sub>3</sub>PO<sub>4</sub>, H<sub>2</sub>SO<sub>4</sub>) and solvents (C<sub>3</sub>H<sub>7</sub>NO, deionized water) on the Ge<sub>2</sub>Sb<sub>2</sub>Te<sub>5</sub> thin films was investigated. Most possible etching mechanism of GST225 thin films by HNO<sub>3</sub> solution was proposed.
The investigation of promising materials used as lead-free solders has been conducted for a long time. In this connection, special attention is paid to low-melting-point metals and alloys, however the search for optimal systems is still going on. The systems Ag-Sn due to excellent electronic conductivity are the most attractive ones. The aim of this work is the development of modes of the electrochemical formation of Ag-Sn layers of the required composition on the surface of the copper plate, and also the investigation of the Ag-Sn structure composition influence on thermodynamic properties in the range of temperatures from the room temperature to 500 °С. During the investigation there has been developed a set of recommendations on the choice of appropriate electrolytes for deposition of Sn and Ag, optimal current density for obtaining a high-quality coating. On the basis of the differential scanning calorimetry data, it has been established that the Ag-Sn systems of a certain composition have the optimal characteristics. The obtained results allow us to develop the formation methods of solders with given thermodynamic characteristics and to set the temperature ranges of stability for application as metallization systems. Begin the abstract two lines below author names and addresses. The abstract summarizes key findings in the paper.