In the year 2006 a ban of lead containing solders in the EU required the qualification of lead-free solder alloys. However, these do not provide the same characteristics as lead containing solders do. Also their costs are higher due to expensive machinery use and increased tin and silver contents. The aim of our research is to develop assemblies based on electrically conductive adhesives that have better characteristics than solder. In this paper three electrically conductive adhesives are investigated. Their thermal and electrical conductivities are compared to the respective properties of solders. In addition mechanical analyses are accomplished so that adhesive strengths on several substrates can be compared even after aging and fatigue. Overall, this work showed that electrically conductive adhesives can be an alternative to solders for the conductive assembly of high-power devices.