Issue link: https://iconnect007.uberflip.com/i/1546933
56 SMT007 MAGAZINE I OCTOBER 2026 beginning an analysis, the surface brightness is adjusted to both illuminate the unpainted surface and saturate the ball pixels. Figure 1 shows a side- by- side comparison of a sample with saturated solder balls and the detection of their pixels. Atten- tion should be given to the edges of the high- lighted regions to notice the entire ball region is not selected. To account for this, the masked regions are expanded to remove the balls completely. Once the balls are removed, further data processing is performed, including plane rotation, noise removal, and smoothing. Figure 2 shows a comparison of the same BGA at room temperature, painted and processed using a function known as feature detection, and not painted using the surface brightness feature. Feature detection is a software function that identifies repeating patterns based on height and shape, allowing them to be categorized automatically and, in this case, removed from the data set. Unpainted Bottoms Figure 3 shows the results for six of BGA 1, both in unpainted and painted conditions. Each line represents an average of three separate runs, with green indicating unpainted BGAs and red indi- cating painted BGAs. The two sets display a similar overall pattern. However, unpainted samples show a higher standard deviation, averaging 2.57 µm, compared to 1.81 µm for painted samples. It was observed that the solder balls on the unpainted BGAs reflected light, creating secondary fringe patterns that increased noise in each measure- ment. While smoothing can help reduce some of this error, it does not fully eliminate it. The painted BGAs do not exhibit this issue because the solder balls' reflectivity matches that of the surface. Digitally removing solder balls on the painted BGAs using the feature detection option took approximately three and a half hours, whereas solder ball removal on the unpainted BGAs using Figure 3: Coplanarity over temperature profile of painted (red) versus unpainted (green) for BGA 1.