Unlike Samsung, Apple does none of its own production - relying on Asia's contract makers instead.

The biggest of the bunch is Apple's old flame Hon Hai - known better by its trade name Foxconn.

But it's not exactly been a fairy tale romance.

Over the past four years as Apple's shares rose six-fold to briefly make it the world's most valuable company, Hon Hai - after a little spurt - has basically stayed flat.

That's in part because of what you see here: Hon Hai's earnings have stayed relatively stable over the last few years versus this huge ramp-up for Apple - which has been very successful squeezing every single possible drop of cash out of its suppliers.

In fact, it commands an estimated 55% margin for the iPhone alone, according to Piper Jaffray.

And now there's talk Apple will turn to Hon Hai's rival Pegatron to assemble the long-rumored lower-end iPhone, with Pegatron increasing its China factory staffing by up to 40% in the second half of the year.

Keeping the squeeze on its supplier's margins will be key for Apple if it does indeed go ahead with emerging-market priced iPhone.

In the first quarter of 2013 Apple's overall gross margins were 37.5 percent - that's industry leading.

If you compare that with Hon Hai, analysts expect it to come in at about 8.3 percent.

Pegatron, with its more aggressive pricing, had even lower figures - just 3.1 percent.

Hon Hai is trying to move up the value chain, by doing more profitable activities for Apple - like manufacturing the components instead of just assembling the phones.

 REUTERS REPORTER, JON GORDON, 

"But the kind of industry-topping margins enjoyed by Apple will remain a distant dream for its suppliers. That means more of the same: limited profits and cutthroat competition as they continue to compete for Apple's affections."