were prepared by distilling mixtures of the chlorofluorohydrocarbon and the other component until the overhead temperature reached a constant value and the composition of the distillate remained unchanged as verified by glc analysis thereby establishing the existence of a minimum boiling azeotrope in each case the azeotropes were tested as solvents for solder flux on printed circuits azeotropic compositions were prepared and characterized by the properties tabulated below table i__________________________________________________________________________ composition of azeotropeazeotrope sup a chlorofluoro chlorofluoro b p pressure hydrocarbon alcohol hydrocarbon alcohol__________________________________________________________________________56 u00b0 c 742 mm 141 sup b methanol 73 5 26 5 wt 64 4 35 6 area 65 u00b0 c 749 mm 141 ethanol 81 2 18 8 wt 68 u00b0 c 740 mm 141 isopropanol 81 3 16 6 sup d wt 52 u00b0 c 741 mm 132 sup c methanol 90 4 9 6 wt 56 57 u00b0 c 748 mm 132 ethanol 94 9 95 5 5 1 wt 47 u00b0 c 744 mm 132 isopropanol 98 7 1 3 wt __________________________________________________________________________ sup a b p is the boiling point for the azeotropic composition at substantially atmospheric in each case the pressure showing was the atmospheric barometric pressure taken from daily laboratory readings sup b 141 represents 1 2 dichloro 1 fluoroethane sup c 132 represents 1 2 dichloro 1 2 difluoroethane sup d remaining 2 1 weight per cent not identified the azeotropes were tested as solvents for removal of solder flux from commercial circuit boards with results as shown below along with comparative runs table ii______________________________________ wt of fluxruns solvent systems dissolved______________________________________1 141 methanol 97 02.