Samsung was too “aggressive” in the design of its now-recalled Galaxy Note 7 devices causing its batteries to explode, a new report claims.

Engineering firm Instrumental performed a teardown of the Note 7 and found the issue was likely due to Samsung “pushing the manufacturing parameters a little too far in order to make the highest capacity battery in the smallest package”.

The South Korean electronics giant recalled the Note 7 in September amid numerous reports of the handset catching fire, before stopping production of the phone altogether in October.

According to Instrumental, the battery in the Note 7 is made up of a positive layer of lithium cobalt oxide, a negative layer of graphite, and a layer to separate those two materials.

The layer in the middle allows energy to flow between the positive and negative layers.

But if those layers touch, the battery can overheat and lead to an explosion, Instrumental chief executive Anna Shedletsky found.

The engineering firm said the device wasn’t manufactured to handle the pressure of everyday use and that the battery was too tightly packed inside the case.

“When batteries are charged and discharged, chemical processes cause the lithium to migrate and the battery will mechanically swell,” Ms Shedletsky said.

“Any battery engineer will tell you that it’s necessary to leave some percentage of ceiling above the battery, 10 per cent is a rough rule-of-thumb, and over time the battery will expand into that space.”

Ms Shedletsky said the Galaxy Note 7 should have had a 0.5mm ceiling; it had none.

“This is what mechanical engineers call line-to-line – and since it breaks such a basic rule, it must have been intentional.”

Samsung Note 7 0.5mm ‘ceiling’ and less than 0.1mm between the “machined pocket” and the top of the battery. Photo: Instrumental

Exploding phones

Samsung issued the recall of 2.5 million Note 7 devices in September – including 55,000 Australian handsets – after more than 90 reports of exploding batteries were made in the US that month alone.

The company provided customers new versions of the phone, but it didn’t solve the battery issues in the problematic device.

In October, a US plane was evacuated after a faulty replacement Samsung Galaxy Note 7 reportedly filled the cabin with smoke.

All 75 passengers and crew onboard a Southwest Airlines flight from Louisville to Baltimore exited the plane safely and no one was injured.

It caused several airlines to ban passengers from bringing the device on board.

Pushing boundaries to beat Apple

Samsung could have solved its design problem by using a smaller battery, according to the Instrumental report, but this would have put it at a disadvantage to rival Apple.

A Samsung Galaxy Note 7 reportedly filled a US plane with smoke in October. Photo: Twitter

“A smaller battery using standard manufacturing parameters would have solved the explosion issue and the swell issue,” Instrumental noted.

“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.

“Either way, it’s now clear to us that there was no competitive salvageable design.

“Samsung took a deliberate step towards danger, and their existing test infrastructure and design validation process failed them. They shipped a dangerous product.”