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Figure 5: IPC-B-52 SIR test results of paste B at small QFP leads.
Figure 6: Mean B52-SIR all patterns paste A and paste B.
Figure 7 compares the results for ionic contamination measured on the IC part of the B-52 test vehicles with solder paste A and B. Contrary to the SIR readings, the test coupons processed with solder paste A exhibit an ionic contamination level that were three times larger than solder paste B. The discrepancy is a result of the easy extraction of benign ionics in the alcohol/water mixture from solder paste A, and insoluble contributors to reduced surface insulation in solder paste B. A detailed analysis of the chemical nature of the ionic residues was not performed. The results are a borderline pass for solder paste A with high SIR values and a pass with a wide margin for the samples that used solder paste that failed to consistently maintain a SIR above 100 MΩ during the constant climate test.
Figure 7: Box plots of ionic contamination measurements of the IC part of B-52 test vehicles processed with solder pastes A and B.
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