Lead Free Solder Paste Unit of Per Kg. Physical condition Uniform paste Color : Gray Smell : Mild flavors Melting point(alloy metal) : 217°C-219°C Viscosity:200±30 Pa.s (Malcom PCU-205:10rpm, 25°C) Specific gravity:4.1~4.3g /cm3 Explosive limits :No explosion hazard Solubility: Unable or difficult to be united with water Flash point : No applicable Self-ignition temp.