Saturday, July 30, 2011

Teardown of the Apple iPad

Teardown of the Apple iPad Reveals a Similar Pattern for Apple – Leveraging Tried and True Technology
iPad Line UpiPad-Small

Only one to two times per year does a device so much capture the minds of the market that it warrants braving planes, trains, automobiles, sleet, snow, and dead of night to get our hands on it. While Apple fans can’t wait to use the latest device, we can’t wait to . . . well . . . destroy it. We braved the lines at a “local” mall, got there early enough to be 20th in the pre-order line, only to bring the device home to our teardown lab. Notably, we have been collaborating with our good friends over at iFixit who have published a detailed iPad teardown in a step-by-step format. Chipworks’ unique angle in tearing down the iPad is to provide images down to the bare die. We confirm the source of some of the key silicon by publishing die markings and die photos. In addition, you can order very high magnification die photos of some of these key devices.

While tablet computing has been around for a while, outside of devices purpose built for artists, there has been no killer application to drive really mainstream adoption. We mean the kind of adoption that goes well beyond technology fans, to the kind that can result in the replication of Apple’s massive dominance in portable music players. Adoption that makes a mass market out of a relatively small, fragmented one. 
But if the market isn’t currently dominated by anyone, then what exactly is the Apple iPad, and how does it fit our current understanding of our needs? 
Put glibly, is this a touchscreen Mac or is it a really big iPod Touch
The iPad is a really big iPod Touch 
Not that there is anything wrong with that as countless reviews have already written
iPad-Image1(click image to enlarge)Apple has relied on tried and true technology for the first generation of this device. In some cases, technically speaking, Apple has even gone backwards from what we saw in the latest generation iPhone that we have torn down.Case in point, Apple is not using the do-all touchscreen controller from Texas Instruments that it used in the iPhone 3G, but has instead gone back to the three chip solution seen in the iPhone 2G. Of course, the same space limitations aren’t there in a large device, and so we would speculate that the three chip solution had a lower overall cost. You can see from the image that, relatively speaking, the iPad is basically a giant battery with a tiny board attached to it (outlined in red), with some space left over for a future 3G mobile communications board.
iPad Teardown Image 3(click image to enlarge)The printed circuit board is a straightforward board with no big surprises. At the thumbnail resolution to the left, you can see the Apple A4 processor (more on this later). You can also see the two Samsung K9LCG08U1M 8 GB MLC NAND flash memory chips. At Chipworks, we keep part number decoders on the major manufacturers, and the part number for these memory chips suggests that this is a first generation device, and not the latest advanced process technology from Samsung.We note that the FCC teardown shows Toshiba memory. This package has Samsung package and die markings. It is reasonable to assume that Apple has sourced memory from more than one manufacturer.
iPad Teardown Image 5(click image to enlarge)The backside image doesn’t reveal as many of the obviously newsworthy chips, but does appear to have the iPad’s inertial sensor.The accelerometer design win was by STMicroelectronics, continuing its success with Apple devices. The die markings can be found on the second page of this article.
iPad Teardown-Image7The Apple A4 processor is packaged just like the Apple iPhone processors using package-on-package technology. One for the microprocessor and one for the two DRAM die.
Summary of the iPad Design WinsDie photos are available for puchase on any device with die markings – download order form for details
ManufacturerDie MarkingsDevicePackage Markings
click to enlarge image
Microprocessor (with DRAM)Apple logo
N26CGM0T 1007 APL0398
339S0084 YNL215X0 1004
Samsung339S0084_K4X1G323PE_sm.gif 1 Gb mobile DDR SDRAM (x2)K4X1G323PE x2
BroadcomBCM5973KFBGH_diemrk2SM.gifMicrocontroller with NVM (used for touchscreen)Broadcom BCM5973KFBGH
952280 B1
Apple 343S0446
Texas InstrumentsCDA3240A_CD3240A_die1SM.gifTouchscreen line driverCD3240A
01D5AKT G1
HE 0950 P12
Unknown (TBD)S6T2MLC_S6T2MLCCX01_disSM.gifclick to enlarge imageSuspected power managementS6T2MLC
U1003 A1
NXPLO614_CBTL06141_die1_SM.gif Mux/demux part for DisplayPort and PCIe connectionsNXP L0614
01 37
Apple338S080-SM.gif TBD338S0805
A2 e1
Linear TechnologiesLinear-DC_3342_DieMrkSM.gifclick to enlarge imageDC-DC regulator3442
STMicroelectronics33DH_V583A_Die_DieMrkSM.gif  Accelerometer (confirmed by die markings of ASIC and MEMS device) – STM-LIS331DLH2949
Apple338S0589_CLI1495BO_DieSM.gif Cirrus Logic device – suspected audio processor338S0589 B0
BroadcomBCM4329XKUGB_DieMrk-SM.gif  Bluetooth and 802.11a/b/g/n wirelessBroadcom
CD1004 P21
950762 5EA
LGSW0627B_diemrk_SM.gif DisplaySW0627B
IntersilISL45AIRZ_ISL97645A_die2.gif  TBDi976

Other Devices
(no die photos)
DevicePackage Markings
AtmelSerial Flash MemoryAtmel
SamsungNAND flashK9LCG08U1M-LCBO
Texas InstrumentsTPS61045 Boost Converter (suspected, for WLED)BHT
Linear Technology (suspected)LTC4099 Power Management (suspected)005
O2 MicroWLED DriverAPP 1A


  After tearing down the Apple iPad last weekend, Chipworks lab staff quickly decapsulated and imaged the A4 processor chip that has received so much comment in the last few months.  What we found was an APL0398 chip, presumably the next-generation processor from the APL0298 that we found in the iPhone 3GS. 

Die Mark on Apple A4 Processor 
The die was approximately 7.3 mm square, giving a die area of 53.3 mm2, which is somewhat smaller than the 71.8 mm2 of its 65-nm predecessor that we looked at last year – a 26% shrink, so assuming comparable functionality, this could well be a 45-nm part.  
Die Photo of Apple APL0398 at Top Metal 
When we compare the top-metal layout, it does look rather like the APL0298, so we can probably assume that it has similar capabilities, with the possible exception of the 64-bit memory path. 
Die Photo of Apple APL0298 at Top Metal 
However, speculation as to the node is not evidence, so back into the lab it went, this time to do a cross-section and look at some transistors. That showed it to be fabbed in a nine-metal process, eight copper layers plus an aluminum bond pad/redistribution layer. Zooming in a bit, we can get some idea of transistor density and the metal/dielectric structure – here we see four levels of copper with barrier layers and surrounding dielectric, the pre-metal dielectric (PMD), some transistors and shallow-trench isolation (STI). 
SEM Cross-Section of Apple APL0398 
Closer examination of the sample shows that the contacted gate pitch is ~190 nm, and the 1X metal half-pitch is ~83 nm, both of which are right in the range of the other 45-nm parts we have looked at in the last couple of years. 
So now we’ve confirmed that the A4 is a 45-nm part; the common supposition has been that it was fabbed by Samsung, similar to its predecessors in the iPhones and iPods. As it happens, we have looked at another Samsung-fabbed 45-nm part, the Xilinx Spartan-6. Below is a similar image from our Xilinx analysis. 
Xilinx_Spartan 6 xs 
SEM Cross-Section of Xilinx Spartan-6 
The staining is slightly different, but the metal profiles, the nature of the PMD, the way the contact etch-stop layer wraps around the transistors, and the style of STI are enough to convince me that the A4 is from the same process as the Xilinx chip. 
The industry commentators appear to be right – the A4 is indeed a 45-nm part, and it’s manufactured by Samsung. Given that the associated two Gb of SDRAM and the 64 Gb of flash in the iPad are also Samsung parts, the Korean giant has achieved significant design wins and also pushed forward their ambition to be one of the top foundries.