In addition to the company’s own internal investigation team, safety consulting firm UL and engineering and scientific consulting firm Exponent were hired to conduct their own independent tests. TUV Rheinland from Germany was also brought on to assess Samsung's factories and logistics.
Batteries sourced from the first supplier did not have enough room between the heat-sealed protective pouch around the battery and its internal components. This caused electrodes inside each battery to crimp, weaken the separator between the electrodes, and in the worst cases, caused short circuiting.
Issues from second battery supplier. Source: Samsung
Batteries from the second supplier had a separate issue. Some cells were missing insulation tape, and some cells had high welding burrs on the positive electrode that led to damage to the separator between the anode and cathode. The batteries also had thin separators in general, which increased the risks of separator damage and short circuiting.
The company said that it has recovered 96 percent of the 3.06 million Note 7s sold to consumers. Samsung mobile chief Koh Dong-jin said procedures had been put in place to avoid a repeat of the incident.
A new eight-point battery safety check would address safety from the component level to assembly and shipment of devices. Additionally, a battery advisory group was formed, comprising of of external advisers made up of academic and research experts to ensure the company maintains battery safety.
APMEN News, Jan 2017