Report: Samsung’s Galaxy Note 7 did not follow basic engineering rules
Samsung faced a harrowing time for more than two months ever since it launched Galaxy Note 7 in August 2016, causing the company to officially issue a worldwide recall of its devices exploding due to defective batteries. However, Samsung had to eventually shut down sales and stop production of Galaxy Note 7 after replacement devices were also reported to be combusting.
Now, engineers from the manufacturing technology company Instrumental have reported that the Samsung Galaxy Note 7 exploded as the battery was too tightly packed inside the body of the device that any pressure from battery expansion, or stress on the body itself, could squeeze together layers inside the battery that are never supposed to touch with explosive results.
Chief Executive Anna Shedletsky in a post written on the company’s blog said that after acquiring a Galaxy Note 7 and a teardown — with a fire extinguisher kept nearby — Chief Technology Officer Sam Weiss and she had discovered that the design of the Note 7 crushed the battery even during normal operation.
During design, tolerances for battery expansion are built into a smartphone, and Samsung used, “a super-aggressive manufacturing process to maximize capacity,” Instrumental notes. In other words, the Galaxy Note 7 while containing the maximum battery capacity for long use, was designed to be as thin and sleek as possible, thereby competing better against rival devices such as the iPhone 7 Plus and improving on previous Note models.
“When batteries are charged and discharged, chemical processes cause the lithium to migrate and the battery will mechanically swell,” said Shedletsky.
“Any battery engineer will tell you that it’s necessary to leave some percentage of ceiling above the battery, 10% is a rough rule-of-thumb, and over time the battery will expand into that space.”
She said the two-month-old Note 7 unit had no ceiling. “The battery and adhesive was 5.2mm thick, resting in a 5.2mm deep pocket. There should have been a 0.5mm ceiling. This is what mechanical engineers call line-to-line – and since it breaks such a basic rule, it must have been intentional. It is even possible that our unit was under pressure when we opened it.”
Shedletsky said a smaller battery using standard manufacturing parameters would have resolved the explosion issue and the swell problem.
“But, a smaller battery would have reduced the system’s battery life below the level of its predecessor, the Note 5, as well as its biggest competitor, the iPhone 7 Plus,” she wrote.
“Either way, it’s now clear to us that there was no competitive salvageable design.”
She said the design and validation process for a new product was challenging for everyone. “In this case, Samsung took a deliberate step towards danger, and their existing test infrastructure and design validation process failed them. They shipped a dangerous product.
“That this is possible at one of the top consumer electronic companies in the world is humbling – and demonstrates the need for better tools. Instrumental is building them.”
Source: Digital Trends