Investigation of solder joints by thermographical analysis

The present stage of development of electronics technology there is an increased interest in the study of new materials used as solder that replaces the already banned tin-lead alloy. Many investigations were done in direction of metallurgic compatibility between the printed circuit board finishing, component terminal finishing and solder itself. Other studies are taken in direction of mechanical characterization of lead free alloys. We propose a study from electrical point of view. So we will analyze the current capabilities of solder joints by thermographical investigations. The finite conductivity of the solder alloy will act as a dissipating media and will heat the adjacent region to the joint. In order to make this effect more pregnant it is necessary to dispose of very precise low-ohm resistors and to pass through them relatively high currents. Based on a high resolution infrared camera the temperature gradient will be better observed. The measured results are compared to the results derived from finite element modeling and simulation. In the simulations, the whole 3D structure of solder joint is modeled. It has practically a very complex shape and is difficult to be analyzed using other methods. Our tests will be realized on organic rigid substrates using a configuration that was intended to characterize the solder joint dissipation. The data derived from this analysis will be very useful in the design process of high power circuits that could be used in advanced electronic modules.