iPhone SiP, PoP, SoC

Confusion abounds about the manufacturer and type of microprocessor found in Apple’s iPhone. With over a million units shipped to date and Apple on the verge of launching their revolutionary computing platform into Europe, the timing is right to reveal the “secret.” Actually, I am just revisiting Semiconductor Insights’ revelation from July as reported in EETimes. Our own Greg Quirk was quoted identifying an Apple branded Samsung stacked die package containing the S5L8900 processor.

Although nearly three months have passed since Quirk and his team first laid bare the guts of the iPhone, a search for “iPhone processor” information still yields primarily speculation and conclusions based on software tests. I’m hopeful this post will get Google taking Semi Serious a lot more seriously.

But the source of the iPhone’s brainpower is not the end of the story (fortunately for this scribe). The chip Samsung supplied to Apple contains a significant first. The iPhone processor is the first package-on-package or PoP device with significant market presence. Unlike earlier devices that contained multiple die that were stacked, bonded, and then encapsulated with plastic molds, the Samsung processor chip takes two independently packaged devices and stacks them. This decreases the board footprint of an apps processor in the same way a single package with stacked die would. However, the package gets taller. The Samsung PoP configuration is 1.3mm high (not including solder ball height at the system PCB interface). Most of the difference comes from the inter-package solder balls that are about 0.35mm in diameter. That’s still a fairly low profile package and a very small price to pay since 1.3mm presents little if any challenge for Apple’s contract manufacturers. After all, the iPhone includes a camera and the image sensor module is typically the limiting factor in keeping the final product thin.

There is a big upside to using PoP. It allows package and test of the cheap commodity DRAM independent of the more precious high performance logic IC. This creates flexibility in the test programs and allows a kind of “final” test on each packaged device before marrying them into the system-in-package (SiP). But there is a big manufacturing cost advantage because of de-risking potential loss of the logic IC. An expensive advanced process logic IC could easily end up in the junk pile because of the relatively complex assembly process required to stack memory and logic in the same package.

But wait. There’s even more to the Samsung apps processor at the die level. The device is manufactured in 90nm technology. That’s not cutting edge, but there is DRAM embedded on the die. Samsung integrates approximately 1.2M of e-DRAM along with about 375K of the more traditional SRAM SoC memory.

Has Samsung concluded the SiP versus SoC debate by bundling them all together in a single device?

Posted in Industry News, Packaging, Process | 1 Comment »