How solder paste is different from tin when soldering?
This &quot;solder paste&quot; is not what is typically called solder paste. Solder paste, which is used for reflow soldering, is a mixture of tiny alloy particles (Sn-Pb, Sn-Sb or Sn-Ag) and flux. Your paste is bare flux and contains no solder. A better translation for the german word &quot;Lötfett&quot; would be &quot;flux paste&quot;.
For reflow soldering, this kind of flux is usually not suitable because it typically contains acidic incredients which are corrosive and lead to leak currents on the pcb surface. It should only be used for soldering wires and non-electronic soldering.
Look for a solder paste that has the alloy specified on the package.