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78 SMT007 MAGAZINE I OCTOBER 2018 ASSEMBLY MATERIALS & COMPONENTS Substrate The substrate used in this study is a custom designed aluminum core PCB. The particular parameters for this board are detailed in Table 6 below. LED Components For this study, a commercially available ceramic LED was selected. Details of the LED are show in Figure 10. Solder Pastes Two commercially available no-clean Lumet solder pastes were used. Paste A has been formulated from the ground up to deliver low voiding while Paste B served as the standard control. PROCESS AND TEST METHOD Equipment Processing Details Solder paste printing was done using DEK Horizon 03iX printer with a 4 mil thick laser cut stainless steel stencil with a 1 to 1 ratio of aperture size to pad size. Stencil print- ing parameters used for all solder pastes are shown in Table 7. Reflow Soldering Using the learnings from the Process Case, a soak reflow profile was generated the condi- tions are 180-200°C/90s Soak 255°C Peak 80s TAL Figure 11 shows the profile. Table 6: Test vehicle details. Table 7: Print conditions. Figure 10: Commercially available ceramic LED package.