PURPOSE: To obtain a binary azeotropic compsn. which is nonflammable and is useful for cleaning printed circuit boards by mixing 2,2-dichloro-1,2- difluoroethane with methanol, ethanol, or trans-1,2-dichloroethylene.

CONSTITUTION: 85-95 wt.%, pref. about 90.5 wt.%, 2,2-dichloro-1,2-difluoroethane (A) is mixed with 5-15 wt.%, pref. about 9.5 wt.%, methanol (B) to give an azeotropic compsn. having a b.p. of about 44.0°C. Separately, 92-98 wt.%, pref. about 94.7 wt.%, ingredient A is mixed with 2-8 wt.%, pref. about 5.3 wt.%, methanol (C) to give an azeotropic compsn. having a b.p. of about 45.8°C. Likewise, 45-55 wt.%, pref. about 50.2 wt.%, ingredient A is mixed with 45-55 wt.%, pref. about 49.8 wt.%, trans-1,2-dichloroethylene (D) to give an azeotropic compsn. having a b.p. of about 44.5°C.