It’s been months since the intense drama regarding Samsung’s newest flagship handset, the Galaxy Note 7, went down. After it blew over, we were all left with a few questions that needed to be answered. One of those questions was, “Why were the Note 7 units catching fire?” Daunting enough, even Samsung was asking the very same question. The company put forth a lot of energy and time in trying to bring the reason behind this whole fiasco to light, and after months of hard work, it seems like that question was finally answered.
Samsung held a live streamed press conference on January 23rd at 10 am Korean time (which equates to January 22nd at 8:00 Pm EST) where it revealed the results of its hard labor. They didn’t go at it alone however. They reached out to three independent science research facilities in order to aid in getting to the bottom of this whole problem: UL (Based in America), Exponent (Based in America) and TÜV Reiland (Based in Germany). Each company conducted research on different aspects of the Note 7 devices, from the batteries themselves, to the means in which they were transported, to even the software, and they presented their findings separately, but the majority of their findings overlap.
Samsung ran extensive tests to replicate the conditions in which the phones would explode. They ran tests dealing with the charging (both with and without fast charging), wireless charging, the device’s water resistance, ran tests with the device’s back cover off, ran tests dealing with the iris scanner and the USB- type C port, tested third party applications and reinstalled applications. A force of over seven hundred employees spent months slaving over the Note 7’s and they concluded that the culprit is indeed 100% the battery, and not the . A little background science on how the lithium ion battery works: There are a few main components at work: two electrodes (a positive one and a negative one), a substance between them that keep the electrodes from coming into contact (separator layer), two tabs that connect to the electrodes and extend outside of the battery, and insulator tape that keeps the tabs from touching the opposite electrodes. All of these materials are layered, and rolled up several times in a structure called a “jelly roll.” The positive and negative electrode absolutely can NOT come into contact with one another what so ever. If they do, then a chemical reaction will release a massive amount of heat, causing dangerous issues.
The batteries are grouped into two groups: Batteries A (the first batch released to the public) and batteries B (the second batch), and each groups showed different causes for failure. Batteries A had consistently shown damage to the negative electrode near the top right of the battery, and batteries B showed penetration of the separator layer due to abnormally high welding bars in the negative electrode.
For Batteries A, the top right corner of the battery is where the issue had began. The positive and negative electrodes were kept separate for the most part, but at top right corner, near the outer layer, there was damage done to the negative electrode due to the fact that there was not sufficient room inside of the battery. The top of the cell was curved where it was supposed to be straight- an attempt to squeeze material into a tighter space. This damage lead to several issues, including the electrodes coming into contact with one another.
The cause of the failures in batteries B is a combination of various manufacturing issues. Short circuits were found in multiple places throughout the battery. One issue was the high welding joints of the positive electrode tab. The tabs are the parts of the battery that which carry the current from the electrodes and extend outside of the battery. These tabs are welded to the respective electrode, and are kept separate by insulation tape. The problem is that poor welding caused parts of the positive electrode tab to protrude and puncture the insulation tape, leading to contact with the negative electrode. This happens when the battery expands and contracts while charging. Some cases showed the insulation tape actually missing, due to manufacturing issues. This, coupled with the fact that the separator layer itself was rather thin to begin with, lead to the explosions in batteries B.
These reasons are a combination of the information gathered from Samsung, UL and Exponent. TÜV Reiland examined the transportation and handling of the batteries and found that nothing in that department lead to the issues.
With that, we know what lead to the failures of the Galaxy Note 7 batteries. A combination of multiple manufacturing issues across two different batteries from two different companies. But how did this happen if Samsung’s batteries were functioning just fine before? Well, closer to the end of the press conference, the speaker, DJ Koh, very subtly indicated that Samsung wanted to make the battery of Note 7 thinner while retaining a high capacity of 3,500 mAh. This lead to them completely changing their manufacturing processes. This new direction didn’t go so well (obviously) and we now see that. In light of this, Samsung has implemented a radically new 8 point quality control inspection procedure for the batteries before they go out into circulation. They’ve created a new standard of quality control that they plan to share it with the entire industry which will lead to the prevention of anything like this from happening ever again. This is noble of Samsung. We know that they are deeply sorry and are committed to providing cool, quality and SAFE devices to its many users.
With that, the spirit of the Note 7 can finally rest in peace, we can all rest a bit easier now that we know the causes. This marks a turning point in the company, and a reminder that safety and quality assurance should come first, no matter what.