Dependence of thermal conductivity of boron nitride (BN)/poly(vinyl butyral) (PVB) composites on the orientation and particle size of BN with an amphiphilic agent was investigated. The platelet BN particles were oriented in the polymer matrix by physical processes such as tape-casting process. A comparison of the thermal conductivity of the specimens with that of pristine BN showed that the BN/PVB composite treated with amphiphilic agents such as C14H6O8 and C27H27N3O2 showed a higher thermal conductivity than the PVB composite with pristine BN. It was also found that the thermal conductivity of the C14H6O8-treated BN/PVB composite was higher than that of the C27H27N3O2-treated composite due to the good dispersion and interfacial adhesion with C14H6O8. Also, the thermal conductivity of the composite with an in-plane orientation of 8-mu m-sized BN was higher than that of the composites with different particles sizes because of the improvement in the high degree of orientation. (C) 2014 Elsevier B.V. All rights reserved.