why Samsung Note 7 phones are catching fire
How could this have happened? Simple: your phone is a Samsung Galaxy Note 7 — and it’s one of over a hundred that have spontaneously burst into flames.
After 35 reported incidents of overheating smartphones worldwide, Samsung made the unprecedented decision to recall every single one of the Galaxy Note 7 smartphones sold. That’s said to be 1 million of the 2.5 million that were manufactured. (Since the recall was first announced, the number of explosive Note 7s has nearly quadrupled.) The company says it’s stopped all sales and shipments of the Note 7 and is working with government agencies and cellular carriers around the world to provide refunds and exchanges for the phone.
In every country, the message is the same: return your Samsung Galaxy Note 7 now, just in case something bad might happen to you.
Read the details here
https://www.cnet.com/news/why-is-samsung-galaxy-note-7-exploding-overheating/

Packing density of components and blocks, and right amount of power delivery to different parts inside a portable device are major concern.
Such examples highlights the difference in virtual simulation and practical working of device.
Sometimes meanwhile i thought that how Samsung has avoided the catching fire issue of s4. That time they didn’t paid much attention. After that s6 edge series was catchy, but now note 7 made same bad its impact. i doubt samsung’s Exynos reliability.