Temperature control with a thermoelectric cooler (TEC) during laser decapsulation of plastic packages
Ablation was carried out on high voltage Schottky rectifiers at 25°C and −5°C (with a thermoelectric cooler or TEC), at 1.0 W and 3.9 W of laser power. In-situ measurement of the reverse current was conducted and correlated to the device junction temperature. It was found that the usage of a TEC increases the number of laser scans to reach the set current compliance of 100 µA after exposing the die, for ablation at 3.9 W, although eventual damage to the device is still unavoidable. The incorporation of a TEC below the sample is also demonstrated to be effective in reducing the device junction temperature during laser ablation.
Design of Automatic Temperature Control System on Laser Diode of Erbium-Doped Fiber Source
Designed an automatic temperature control (ATC) system to arise the stability of laser diode (LD). Established a mathematical model of thermoelectric cooler (TEC) based on the peltier cooling principle. Simulated ATC by MATLAB and analyzed on the simulation results. Designed ATC circuit driver of the TEC of LD. Obtain high speed and high precision ATC system in the room temperature environment. Its temperature precision is lower than 0.1%.
2D modeling of laser-induced plume expansion near the plasma ignition threshold
An axisymetric two-dimensional modeling of laser-induced plume dynamics near the plasma ignition threshold in the ambient gas is carried out to provide a better understanding of the pulsed laser deposition process. In our modeling the ionization process is absent and the plume consists of neutral gas. The numerical investigations are performed with initial conditions close to an irradiance of about 100 MW/cm 2 . This model takes into account different initial conditions in the plume just after the ablation pulse and follows the hydrodynamic behaviour of the subsequent plume expansion. The hydrodynamics induced by the plume expansion are govemed by the two-dimensional unsteady Euler equation which are solved with the numerical method, based on a finite difference scheme associated with a flux corrected transport algorithm LCPFCT. The modeling was able to account for many important features of the gas plume dynamics. In particular, it is shown that the hydrodynamic behaviour and thermal relaxation of the gas plume are strongly dependent on the initial gradient of pressure and density between gas plume and background gas. Reversed flow of particles moving toward the target at certain distances along the R axis is clearly observed at a late expansion stage ( > 2 μs).