Much has been made of Apple’s ARM-based processors, and deservedly so. Despite being a relative newcomer, they have consistently delivered industry leading performance where it counts for their phones and tablets. Better still, they have created a point of hardware differentiation in applications processors. In the early days of smartphone technology, the processor was almost an afterthought to the consumer, so this is good news for a group of companies working to drive up margins.
And the changes have been dramatic.
The Apple A4, which by all accounts is still commercially viable given the price of used Apple products on craigslist, measured in at 53.3 mm². Only two (and a half?) generations later, we have the Apple A5X weighing in at 165 mm² – a whopping 3.1x larger. Remember that all three of the Apple processors we are comparing here are (basically) at the same 45 nm generation, so we have a genuine apples-to-apples comparison (sorry about the bad pun). By way of further comparison, another flagship applications processor, the NVIDIA Tegra 3 is 82 mm², and fabricated in a similar 40 nm generation by TSMC, so it is (more or less) consistent with the prior generation A5.
For the A5X, Apple has also changed packaging, away from what has been package-on-package with the DRAM to putting the DRAM physically on the other side of the board. This type of packaging has been reported to have (theoretical) disadvantages in BoM simplification because it is no longer one module and in performance because of the more routing between the chip and memory. However, we wonder if all the horsepower required to play wicked-awesome games on that high pixel-count screen hasn’t created potential heat issues that required the move to a new layout. Regardless, we expect that in the future, as Apple moves to newer lower power process technology at 32 nm and below (perhaps employing high-k metal gates) that we’ll see a return to PoP designs.
But lets get to the cool stuff. A comparison of the sizes (scaled to relative actual size).
Apple A5 Polysilicon Die Photo – 10.09 mm x 12.15 mm
Now, polysilicon die photos are very cool – this we know. When you look at the weird fuzziness in the logic regions, you are not seeing sample preparation artifacts resulting from grinding off layers. You are actually seeing the different densities of the tiny logic cells showing up as lighter and darker areas.
Chipworks clients get full resolution versions that, in the case of the Apple A5X, are 31 MB in total size when shot with optical imaging, or in tens of gigabytes when shipped as scanning electron microscope (SEM) mosaics. At these sizes, there is no fun, and since we provide these teardowns as a bit of entertainment, we thought that there would be a group of people out there interested in using the Apple A5X as their wallpaper/background on their new iPads.
Here are shots, free of block annotations, for you to work with (you will still need to do some manipulation to get it the way you want it).