Our new semiconductor laser T-SMILS is a laser-heat processing system with an effective temperature control function. Based on real-time temperature measurements directly at the operation point, the laser automatically reacts to overheating e.g. caused by scanning speed changes or deviation in the absorption material. This means in the field of electronic printing, that small changes in the absorption ratio or the ink layer thickness are automatically adjusted by changing laser power during the process. This guarantees a stable conductivity in flexible printed circuit boards. Laser sintering with the two-color thermometry method using Hamamatsu Photonics´ high-precision and low-noise infrared detectors, enables temperature measurements from 200°C. The laser process itself reaches temperatures of more than 400°C. These high temperatures lower the electrical resistivity significantly without damaging of the ink substrate.