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statistically similar. This test is similar to Stu- dent's t-test used to compare means. The out- put of the Tukey-Kramer HSD test is a chart that shows the data sets and several data cal- culations and reports (Figure 16). The Tukey-Kramer HSD analysis shows whether the data sets under comparison are significantly different. This analysis is used to draw general conclusions and show trends in performance. Results and Discussion Standard Solder Paste Tests The viscosity of each solder paste was mea- sured using the T-bar spindle and spiral pump methods from J-STD-005 [1] . Figure 17 shows the results. The viscosity of the no-clean solder paste increased with decreasing solder powder size for both the T-bar spindle and spiral pump methods. The viscosity of the water-soluble solder paste was more stable with respect to solder powder size regardless of the method used. The T-bar spindle method gave a higher viscosity for the no-clean SAC Type 5 and 6 solder pastes than for the water-soluble solder pastes while this was not true for the spiral pump method. The slump of each solder paste was mea- sured according to IPC-J-STD-005 methods. Table 6 shows the pass and fail results. All solder pastes passed cold (25°C) slump, but there were some failures with hot slump (180°C). The no-clean Type 6 and the water- soluble Type 5 and 6 solder pastes failed hot slump. These solder pastes were formulated originally for use with Type 3 and 4 solder powders and are not necessarily optimized for the smaller solder powders. The IPC J-STD-005 solder balling test was run using frosted glass slides and a hot plate set to 245–250°C. Table 7 shows the results. Figure 16: Explanation of Tukey-Kramer HSD report. Table 6: IPC slump pass and fail results for each solder paste. Figure 17: Viscosity of each solder paste using both T-bar spindle (L) and spiral pump methods (R). 42 SMT007 MAGAZINE I JULY 2019