Following a pilot production at the end of 2014, Apple's new 12-inch MacBook Air is expected to enter mass production in the first quarter of 2015, according to sources from the upstream supply chain. And with the Apple Watch also beginning production at about the same time, Apple's supply chain players have started accelerating their supplies of related components.

Apple's new MacBook Air features Intel's Broadwell processors and a new chassis design to reduce the device's overall thickness and weight, but the start of mass production has been hampered by low yield rates, the sources said. As the yield issue is gradually being resolved, mass production is expected to come in the first quarter of 2015, the sources explained.

The new 12-inch MacBook Air will target mainly the high-end market segment and therefore will only have limited shipments, but the product will allow Apple to stay firmly as the leader in the ultra-thin notebook sector in terms of technology, the sources said.

Quanta Computer is the manufacturer of the new device, the sources disclosed. But the ODM declined to comment about its clients or orders.

Apple's supply chain has also been preparing components for the Apple Watch and mass production of the wearable device is believed to start in three months.