In this work, the properties of solvent and solvent-free electrically conductive adhesives (ECAs) in four curing manners and after solder reflows are investigated for multi-chip module applications. The curing behaviors and thermal degradation of solvent and solvent-free ECAs are also studied by differential scanning calorimeter and thermogravimetric analysis, respectively. The bulk resistivity of ECAs in four curing manners is significantly different, even if they are cured at the same temperature and time. The conductive trends of solvent and solvent-free ECAs are also different. The good and poor conductive properties of solvent ECA are obtained at curing temperature starting from room temperature and setting temperature, respectively. However, the results of solvent-free ECA are opposite. All the bulk resistivity and the coefficients of thermal expansion of solvent and solvent-free ECAs tend to decrease after solder reflows. The reasons are studied by thermomechanical analyzer, thermogravimetric analysis, topography and deformation measurement, and scanning electron microscopy.