Back when the iPhone 5 came out in 2012, Samsung had a huge hand in the user experience and performance of each iPhone coming off of the line. Two crucial components, the internal memory, or NAND, as well as the processor, were manufactured by Samsung. From the iPhone 5S onward, however, Apple wanted to use special electromagnetic shielding on the NAND for their iPhones. For whatever reason, Samsung did not meet this demand and their provision of Apple's NAND chips ended. They still made the processors, but that was about the end of Samsung's relations with Apple. On Monday, however, Samsung announced that they had rekindled their previous relationship with Apple and would likely be providing the NAND for the next generation of iDevices.
Samsung won't be developing the shielded NAND chip that Apple is asking for on their own. Specifically, they'll be partnering up with dispenser manufacturer Protec and equipment specialist Asymtek, along with Hansol Chemical and Nitrium to develop the actual coating compound. The companies will be banding together for the massive undertaking of equipping Samsung's assembly lines to be able to mass-produce coated NAND on the scale that Apple would demand of them if the deal goes through. This will require extensive retrofitting of Samsung's current equipment, as well as the creation of brand new equipment. Essentially, the coating process places a near-microscopically thin layer of metal over the surfaces of the chips in just such a way as to protect components from magnetic interference without causing any electrical misfires.
The anti-EMI coating gives Apple a bit more freedom with the design of their phones, allowing for components to be placed closer together or even on top of each other inside the phone. This means a thinner phone with more room for a battery and more room to experiment with designs to mitigate heat and CPU latency. As well as possibly scoring them the deal with Apple, Samsung's new process and coated NAND are likely to leak into their own devices, giving them the same benefits. There was no word on when the deal will be official or when manufacturing of the new components will begin.