Microwave flash sintering of inkjet printed colloidal silver dispersions on thin polymer substrates was studied as a function of the antenna area and initial resistance. The presence of conductive antennae promotes nanoparticle sintering in pre-dried ink lines (see figure). For dried nanoparticle inks connected to antennae, sintering times of 1 s are sufficient: to obtain pronounced nanoparticle sintering and conductivities between 10 and 34% compared to bulk silver.