A teardown performed by manufacturing company Instrumental suggests that the industry’s ongoing obsession with slimness was the Note 7’s downfall.
Its report pins the blame on Samsung’s “aggressive” design, claiming that the handset’s battery was squeezed in too tight and wasn’t afforded any space to deal with day-to-day pressure. It notes that manufacturers tend to build “10%” of extra space into handsets, as batteries swell a little when they’re charged. According to the report, Samsung decided against this.
“Our two-month old unit had no ceiling: the battery and adhesive was 5.2 mm thick, resting in a 5.2 mm deep pocket,” the report reads. “There should have been a 0.5 mm ceiling. This is what mechanical engineers call line-to-line -- and since it breaks such a basic rule, it must have been intentional.”
Why did Samsung take such a risk? Almost certainly to make the phone as thin as possible.
“What’s interesting is that there is evidence in the design of an intellectual tension between safety and pushing the boundaries,” the report adds. “Samsung engineers designed out all of the margin in the thickness of the battery, which is the direction where you get the most capacity gain for each unit of volume.
“Looking at the design, Samsung engineers were clearly trying to balance the risk of a super-aggressive manufacturing process to maximize capacity, while attempting to protect it internally.
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"In this case, Samsung took a deliberate step towards danger, and their existing test infrastructure and design validation process failed them.” [Instrumental]