We Now Know Why The Samsung Galaxy Note 7 Caught Fire


Ever since Samsung’s flagship Galaxy Note 7 was pulled off the shelves in a global recall, we’ve all had a burning question within us: Why did that happen? What was the reason for a flagship Samsung device to catch fire like that (akin to Katniss in The Hunger Games)? Most people put it down to poor QC (quality control) or an issue with the inbuilt battery. But no exact answer was given.

Now we finally have the answer.

Assault and Battery

Samsung reportedly performed numerous complicated tests across an estimated 200 thousand devices. The tests were focused on finding abnormalities with features such as water resistance, fast charging, wireless charging, the iris scanner, the USB Type C port and finally, the software itself. All tests came back negative for any issues. The folks at Samsung then proceeded to scrutinize the production process and sought assistance from a number of 3rd party investigators. These included UL, Exponent and TUV Rheinland AG.

According to their finding, there were a couple of issues. Firstly, both recalled units and their  replacements suffered from design flaw in the top corner of the battery. To be a bit more precise, the upper-right corner.

Usually Positive and negative electrodes in batteries are separated via a protective layer. Damage to this layer can result in the electrodes meeting, thus causing a short circuit. This seems to be one of the issues with the second batch.

Image taken from: The Verge

According to the results of the battery test, an unusual high welding bar was formed during the ultrasonic welding process. This process is required to attach the positive tab. These bars then penetrated the insulation tape and the separator. This resulted in direct contact with the negative electrode. Thus, a short circuit is created. Furthermore, a number of batteries were also missing insulation tape.

According to 3rd-party research firm UL, units affected by this issue show common abnormalities in the same areas. They also confirmed that the root cause was the deformations in the upper corners of the battery, and the separator within the battery being too thin.

Has Samsung learnt from their mistakes?

Whatever the issues may be, it’s still sad that we had to bid farewell to what was to be the flagship smartphone of the year. Hopefully Samsung has learnt from their mistakes. Indeed, they have promised to implement more stringent quality control measures. Let’s just hope it’s not too late for them.


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