The upstream supply chain is expected to begin shipping Apple's upcoming next-generation iPhone products at the end of the third quarter. A new 4.7-inch iPhone will be handled by Pegatron Technology and Foxconn Electronics (Hon Hai Precision Industry), while the new 5.5-inch model will be made by Wistron and Foxconn, according to sources from the upstream supply chain. The ODMs all declined to comment on their orders.

Apple has been separating its component orders to multiple suppliers to lower risks, and the vendor currently has at least two suppliers for components such as batteries, hinges and chassis.

Wistron was a manufacturer of Apple's iPhone 5c and has already prepared sufficient capacity for the next-generation iPhone orders; however, the sources believe Wistron's yield rate will become a key factor influencing the company's profitability from the orders.

Wistron chairman Simon Lin recently said the company had a 5% revenue growth in 2015, but its operating profits and net profits dropped dramatically in the year due to weak demand for notebooks and LCD TVs.

For 2016, Wistron has been strengthening its PC, server and smartphone businesses and will accelerate its pace in new businesses such as display components, recycling, medical services and education technology. Since Wistron has already shrunk and stopped some of its businesses that seeing in losses, the company's profits are expected to improve significantly in 2016.

Sources said that Wistron's notebook shipments are expected to stay flat or drop slightly on year in 2016, but its server shipments are expected to grow in the second half thanks to increasing orders from US-based clients. With orders from Apple's new iPhone, Wistron is expected to perform much stronger in the second half than the first.