Issue link: https://iconnect007.uberflip.com/i/1067105
JANUARY 2019 I SMT007 MAGAZINE 85 Conclusions The final reliability of an assembly relies heavily on the thermal profile used for solder- ing. When the peak temperature is too low, excess amounts of active flux residues are left behind. Further, when ample moisture is avail- able from a normal operating atmosphere or from condensing moisture anomalies, there is a greatly increased risk of failure due to electri- cal leakage and/or electrochemical migration. Active no-clean flux residues are conductive in general, and when moisture is absorbed into the residue across non-common conduc - in certain types of components. The data in Table 4 shows similar levels to that of Group 3. Group 4 SIR Results All locations with and without components passed the acceptance criteria, much as with Group 3. The data in Figure 10 shows that at no time did the resistance measurement dip below the 1.0e8 ohms of resistance. This indi- cates that in a normal field service environ- ment without excessive available atmospheric moisture, the product should not fail when voltage is applied. Figure 9: Group 4 thermal profile. Figure 8: SIR results for Group 3.