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May 2015 • SMT Magazine 21 but that the breakpoint is the same. The usage of nitrogen shows no impact with regards to spacing DPMO. All defects were related to solder bridges in between passive components and no issues were seen between passive components and CSP/PoP components (Figures 9, 10). During cross-sectioning and visual inspec- tion of the air reflowed samples it was noticed that some of the 0.4 mm pitch PoP components showed head-on-pillow (Figure 11) and that the solder joint did not wet the whole pad. This was expected and proven in earlier builds, but it was decided to still run in air reflow to be able to validate potential spacing differences between air and nitrogen reflow. The samples reflowed in nitrogen did not show any issues for the 0.3 mm pitch CSP and PoP components. For the 01005 components the wetting is not as good in air reflow compared to nitrogen reflow, but still considered as acceptable accord- ing to IPC-610 E standard (Figures 12, 13). Conclusions There are many ways to achieve minia- turization and the key is to have a toolbox of technologies to fulfill various requirements. Depending on the product, several options mINIaTURIzaTION WITH THE HELP OF REDUCED COmPONENT-TO-COmPONENT SPaCING continues Feature Figure 10: Solder bridges in the mixed spacing section. figure 12: cross-section of a 01005 component reflowed in air. Figure 9: Solder bridge on 01005 at 100 µm spacing. Figure 11: Cross-section of a 0.4 mm pitch top pop reflowed in air.