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76 SMT007 MAGAZINE I MAY 2024 Signed Warpage Case Study; New Methods for Characterizing 3D Shapes rough Reflow Temperatures." 12 Additionally, sample shapes are considered from the perspective of both absolute shape at each given temperature as well as a relative shape change from a starting room tempera- ture shape. As starting shape can oen be a sig- nificant source of sample to sample variation, relative change of the surface over temperature can be an effective method to understand sam- ple warpage. In these cases, the same gauges are used for analysis. Results No "popcorning" was seen on any samples, so no extreme cases of delamination occurred. is suggests the moisture was well controlled and the samples do not easily show these extreme levels of delamination. Longer mois- ture exposure or faster and higher heating pro- files could change this case. Some example 3D surface renderings of the samples are shown in Figures 6 to 9. To give some understanding of surface shapes the most warped and least warped sample is shown from the smallest and the largest sample. e out-of-plane scale is consistent to the part type. Note that the most warped and least warped points occurred under different conditions between the two sample sizes. Quantitatively, the data is first summarized by the most basic gauge available here, coplanar- ity. In order to summarize the data, each sam- Figure 6: 10 x 11 mm, MSL3, 200°C cool down, low warp. Figure 8: 40 x 40 mm, MSL3, 175°C heat-up, low warp. Figure 7: 10 x 11 mm, MSL4, 217°C heat-up, high warp. Figure 9: 40 x 40 mm, MSL3, 250°C peak, high warp.