iPad Wi-Fi
First generation Apple iPad with Wi-Fi, available with 16, 32, or 64 GB. Model Number A1219. Repairs are straightforward and do not require heat.
Apple A4 Teardown
Teardown
Teardowns provide a look inside a device and should not be used as disassembly instructions.
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Deconstructing processors like the A4 usually happens behind the closed doors of only a handful of companies. These global reverse engineering firms are the investigative arm of the electronics marketplace, gumshoes who do research for people who need to find out who is making what circuitry, as well as what manufacturing process they're using to do it. They're the ones who delve deep into processors, audio controllers, and every other part you'd find inside a cell phone or iPad, figuring out layer by layer the exact composition of each package.
We partnered with the best company in the semiconductor reverse engineering trade, Chipworks, to bring you a closer look at how semiconductor teardowns are conducted, as well as a peek inside the iPad's chips. The engineers at Chipworks are a wonderful bunch of people who are just as interested in today's electronics as we are.
Their analysis of the iPad's packages will give you a better understanding of how the new tablet really works—on an almost molecular level.
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Step 1
— A4 Processor Basics
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Apple's A4 microprocessor is the brain of the iPad.
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The A4 is an ARM processor featuring package-on-package construction to improve the speed and efficiency of internal processes.
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The silkscreen on the A4 reads N26CGM0T APL0398 339S0084 YNL215X0. But that's not very interesting—those numbers don't mean much to us, either. Let's see what we can find inside.
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Step 2
— How to dissect a processor
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Back when the original iPhone came out, we worked with some friends of ours in Silicon Valley to dissect the processor. The equipment we used wasn't nearly as cutting-edge as what Chipworks has, but it got the job done.
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This is a silicon wafer. Each small square is a chip, called a die. The processor die in the A4 is 7.3 mm on each side, for a 53 square mm total area. The percent of working dies that you can get from a wafer like this is called the yield.
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The A4 is actually much more than just a processor— it's a Package on Package, or PoP. In fact, there are three silicon dies inside the A4!
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Step 3
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Our illustrious leader preparing to enter a cleanroom for some silicon surgery on the original iPhone.
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Step 5
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Next, cut the processor in half to take a cross-section photo.
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Band saws are much too crude for this, so we actually grind through the processor slowly, taking off very small amounts of material as we go.
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You can see why it can be tough to take a clear, solid photo of a package's cross-section. The processor is actually one of the larger packages in the iPhone, and still very finicky to handle. Imagine trying to do this with a package a tenth of its size.
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Step 6
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So what is a package? You're looking at one.
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This is a cross-section of the iPhone's ARM processor + RAM package. Click here to see it in its full, 2854x313 glory.
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The processor itself is the center rectangle. The silver circles underneath it are solder balls.
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The two rectangles above the processor are RAM dies. They are offset from each other to make room for the wirebonds, which you can't see in this shot.
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Having the RAM so close to the processor both reduces latency—making RAM access faster—and cuts power consumption, helping your battery last longer.
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Step 8
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This is a typical cleanroom. Regular people—people who might even shop at the same supermarkets as you—suit up every day and go to work in rooms like these. It's absolutely imperative to keep dust, lint, and hair away from the task at hand.
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Tools of the trade:
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Scanning electron microscopes
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High resolution X-ray machines
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Really big magnifying glasses and microscopes
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A number of other gadgets you might find in Q's lab
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