Comparative analysis of pulse and active thermography for investigating solder joint geometry prediction
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Solder joint defects are a major variable in the failure of many printed circuit boards in the electronics industry. These defects are often missed, because they are hidden underneath layers of the printed circuit boards. In this study, we utilized a heat source and infrared camera to construct an experiment that tests the visibility of solder joints of different geometries with and without a cover. The objective of this work was to (1) understand the effects of different amounts of energy on soldering metal and the printed circuit board; (2) use Active Thermography and Pulse Thermography for the inspection of three solders of three different geometries: 60, 90, and 120; (3) create plots depicting the relationship between the average cooling rate for each solder geometry and time per data set collected. Task objectives include: (1) construction of a fully automated heating and imaging chamber along with written PLC program; (2) create hypotheses and conduct experiments; (3) capture and analyze infrared images of each printed circuit board; (4) create models and evaluate data. Results present that (1) Active and Pulse Thermography can be used to visibly see solders of different geometries without a cover; (2) Average cooling rates plotted over time are a good indicator of calculating prediction rates between the solders; (3) as the difference in cooling rates increases, the better the prediction rates; (4) Active Thermography performed better than Pulse with a prediction rate of 84.3% as opposed to 61.9% without a cover. 2011 SPIE.