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April 2015 • SMT Magazine 11 For each peak temperature, reflow profiles rep- resenting a "ramp to peak" and "soak" profile were created (Figures 2–9). The purpose of creat- ing both a ramp to peak and a soak profile was to see if and how, not only the peak tempera- ture, but also the "shape" of the profile, has an impact on SIR performance. For the sake of this work, the "soak" is defined as the period dur- ing which the PCB is between 200°C and 215°C. Figure 1 shows the SIR (IPC-B-24) test coupon used for profiling and the location of the ther- mocouples. All SIR board preparation, materi- als and processes were in accordance with IPC- TM-650 2.6.3.3 and 2.6.3.7. Table 1 shows a compilation of the averaged parameters for each reflow profile scenario. As mentioned at the beginning of this pa- per, two no-clean solder pastes were tested figure 3: 225°c soak reflow profile. Table 1: compiled reflow profile parameters. ElECTriCal rEliaBiliTy OF NO-ClEaN SOlDEr paSTE Flux rESiDuES continues FeAture