Drilling plate-through holes in multilayered printed circuit boards usually leaves a smear of dielectric material on the conductive surfaces which needs to be removed prior to deposition of conductive material. Desmearing utilizes sweller solutions to enhance smear removal. This study investigated the effects of varying the concentration of n-methyl-2-pyrrolidinone-based (NMP-based) sweller, temperature, and application time on smear removal. Diffusion coefficients were computed from weight gain versus time data, then correlated with temperature using an Arrhenius-type equation. The degree of smear removal was determined by measuring the amount of polymer oxidized over time. From the weight loss versus time data, the desmearing conditions that yielded a maximum weight loss of 0.42 mg cm⁻² smear (at constant oxidation conditions) were determined to be 75 vol.% sweller solution, 353.2 K, and 2 min treatment time. Changes in surface characteristics due to sweller treatment and subsequent smear removal were qualified by examining the surface morphology of the polymer by scanning electron microscopy (SEM), identifying changes in functional groups by Fourier-transform infrared (FTIR) spectroscopy, and measuring changes in contact angles.