The removal of organic flux residues in the fabrication of circuit boards has been obtained by using solutions whose formulation contain CFC-113 or other solvents. However, restriction on the use of ozone-depleting CFCs forced development of environmentally acceptive cleaners such as terpene hydrocarbon based cleaners. In this study, we examined the phase behavior of ternary systems containing NP series nonionic surfactant, water, and terpene hydrocarbon as a function of temperature. Phase compositions at the system PIT''s were determined by phase volume measurements and solubilization of abietic acid, triolein, n-hexadecane, and industrial lubricant by three different types of microemulsions was compared. Also spinning drop tensiometer was used to measure interfacial tension.