Flagship smartphones might look nice and have great specifications, but one key segment is hurting them - battery life, and although technology is improving each day, we are not seeing much improvements when it comes to batteries. To improve battery life, companies need to put bigger batteries, meaning they need more space, and that will be possible with new stacked logic boards.
Apple is rumoured to be one of the first companies to use such motherboard in iPhone 8, while Samsung is now rumoured to follow with Galaxy S9. The new stacked logic boards are called SLP (Substrate Like PCB) and can pack chips tighter together, reducing the overall size and that empty space can be used for larger battery.
However, that will only be possible with Exynos chipsets, since Qualcomm chipsets reportedly have "technical difficulties" to use the advanced system boards.