Poor welding, incorrect positioning of crucial parts, deformed corners and missing insulation tape in the batteries in Samsung's Galaxy Note 7's phones all contributed to the phone catching fire and being withdrawn from the market late last year, Samsung officials said, announcing the results of a comprehensive investigation into the unprecedented engineering and public relations disaster.
After a several-months-long investigation involving 700 Samsung engineers, 200,000 Note 7 phones and 30,000 batteries being continually charged and discharged, and analysis from three independent testing agencies from around the world, the Note 7 itself was also found to have contributed to some of the battery failures: the "cell pouch" that held the batteries was too tight, causing one of the tabs on the batteries to bend and break, leading to overheating and explosions.
That problem would be rectified in coming Samsung phones, which would have a larger area for holding batteries, one that would be reinforced against damage, Samsung officials said.
But the electronics and software in the phone, as well as its battery charging system, were found to be free from blame for the explosions, and in fact exceeded generally expected safety standards in mobile phones, independent testing found.
Two different, un-named battery manufacturers made the batteries for the Note 7, and batteries from these two plants were both found to have problems. Batteries from one plant had problems in their top right hand corner, and batteries from the other plant were found to have problems in the top left corner and sometimes were missing insulation tape designed to prevent short circuits. Poor welding, which caused protrusions that ultimately led to short circuits, was also found in many of the batteries tested.
The high energy capacity of the lithium-ion batteries, which Samsung had increased in the Note 7 compared to the previous model, didn't cause the flaws, but it did exacerbate problems when they occurred, independent testing found.
None of the other new features in the Note 7, such as its retina scanner, its waterproofing or its faster-than-ever charging, were found to have contributed to the problems, said the president of Samsung's Mobile Communications Business, DJ Koh, who announced the findings during a press conference in Korea.
Samsung is the number one maker of smart phones, and the largest consumer electronics company in the world.
It released the Note 7, its most expensive model, in August last year, but quickly withdrew it from the market after multiple users reported their phones catching fire, generally while charging. More than 96 per cent of the roughly 3 million phones that reached the market have now been returned to Samsung, said Mr Koh.
Absent the well-regarded flagship phone, Samsung recorded its worst ever quarterly decline in the third quarter of 2016, according to figures from the research outfit Gartner. Sales declined 14.2 per cent in that quarter, compared to the same quarter a year prior. Prior to that, Samsung's worst quarterly drop had been the 12.3 per cent year-on-year decline it suffered in Q3 2014.
"The decision to withdraw the Galaxy Note 7 was correct, but the damage to Samsung's brand will make it harder for the company to increase its smartphone sales in the short term," said Garner research director Anshul Gupta. "For Samsung, it's crucial that the Galaxy S8 launches successfully, so that partners and customers regain trust in its brand."
Mr Koh announced that the company had formed an independent advisory board to help prevent battery explosions in not just Samsung's phones, but in all devices from all manufacturers.
The company said it would also increase the testing of batteries it received from third-party manufacturers, including random x-raying of the batteries, large-scale charging and discharging of batteries to simulate two-weeks of real-world usage before the batteries made it onto the market. There would also be increased training for all people involved in manufacturing and shipping batteries.
"We hope that this case will be an opportunity to improve the safety of lithium-ion batteries for the whole industry," Mr Koh said.
