The electrical characteristics of some polymer thick film (PTF) resistors have been studied. There are four different kinds of carbon blacks and two different kinds of polymer resin, i.e., epoxy resin and polyimide resin, selected in the preparations of the PTF resistors. In this paper, the electrical characteristics, which include the sheet resistivity, current noise indices (CNI), temperature coefficient of resistance (TCR) and the percentage variations of resistance (

R/R, %), are discussed. It will be shown that there exists a correlation between the "structure" of the carbon blacks and the electrical characteristics of the PTF resistors. The effects of the blended carbon blacks on the electrical characteristics of the PTF resistors are also discussed.