Samsung's Galaxy Note 7 may have caught fire through regular use because the battery was too big and not tested enough before launch.
Hardware expert Instrumental studied the phone's design following several reports of it exploding and found that the battery had not been given enough room in the phone to account for typical swelling.
The battery's polymer separator layers were also found to be too small. This is said to have allowed the positive and negative layers of the battery to touch through regular stress on the device, causing it to explode.
As to why Samsung would build a phone destined to explode, Instrumental suggested it was due to pressures on engineers to produce a new, competitive phone without the time to properly test it.
The firm noted that Samsung could have put a smaller battery in the phone to avoid the explosion issue. However, a smaller battery would have meant it could not compete against the latest iPhones, which is likely why Samsung decided against it.
Samsung has ceased all production of its Galaxy Note 7 devices after several of them exploded during normal use. The disastrous launch caused a 96% drop year-on-year in profits for its mobile division.