The goal of the project was to not only make the iPhone visually more appealing but to dramatically increase its duribility.
The iPhone Custom process took over a month of hard work to complete the first device. That first device received so much positive attention that a manufacturing company was commissioned for a small scale, limited edition, production run. Less than 100 units were ever produced. The team that worked on the original iPhone Custom, detailed here, is now hard at work on the iPhone 3G.
TiAlN/TiN treated 304 stainless steel bezel and logo
Black type II anodized rear housing and SIM tray
- Carl Zeiss Optical Microscope - Understanding wear characteristics / Surface treatments
- Personal SEM - Material characterization
- Plasma Enhanced Chemical Vapor Deposition (PECVD) - TiN / TiAlN treatment
- DC power supply - Anodizing
Process Part 1 - Examine the iPhone
To achieve all the project goals a complete understanding of the iPhone hardware was necessary. The process began using a Carl Zeiss optical microscope. Such a tool was chosen to analyze the wear characteristics of the iPhone on the microscopic level. I think its safe to say that after a few months of pocket use an un-cased iPhone begins to loose some of its gloss and sparkle. Understanding how and why these tinny flaws occur helped shed light on ways to improve the wear characteristics of the iPhone. Here are some photos taken during the optical microscope session with the iPhone:
Figure 1: iPhone LCD 162ppi 100X
Figure 2: iPhone LCD 162ppi 1000X
Figure 1 & 2 show the LCD of the iPhone up close. Notice how each pixel is made up of 3 individual colors; Blue, Red, Green. Figure 1 shows the iPhone contacts screen with the letter “V” clearly visible tilted 90 degrees to the right. It is interesting to see how the intensity of each pixel can be controlled acting as an anti aliasing mechanism at the edge of each letter.
Figure 3: iPhone Home button 100X
Figure 3 shows the edge of the home button. Notice the gap between the plastic button and the glass screen. This gap measures between 90-110 microns.
Figure 4: iPhone front speaker 100X
Figure 4 shows the other disguising feature of the front side of the iPhone, the front speaker. The wire mesh used is very fine keeping out even tinny dust particles. The photo shows some microscopic pieces of lint caught inside the mesh.
Figure 5: iPhone front bezel 100X
Figure 6: iPhone front bezel 1000X
Figures 5 & 6 are some of the most valuable taken with the optical microscope. Notice the hairline scuffs and scratches. The majority of these blemishes measure only 10-20 micron across. The larger scratches measure between 100-150 microns. From this information it was determined tinny pieces of lint and dust are the cause of these microscopic blemishes. The result of these imperfections is the overall loss of the “new” and glossy effect the new device exuded.
Figure 7: iPhone rear housing 100X
Figure 8: iPhone rear housing 1000X
Figures 7 & 8 show the rear housing of the iPhone. Notice how the smooth bead blasted finish appears very angular under high magnification. This texture along with its surface treatment make the rear housing, one of the most durable surfaces of the entire stock iPhone. Figure 8 shows the gap between the rear housing and the apple logo.
Now, with a general idea of how the different surfaces of the iPhone wear, I needed to know a little bit more about the different materials themselves.
Part 2 - Scanning Electron Microscope spectroscopy of the iPhone
I set forth with the task of figuring out everything there is to know about what goes into the exterior of the iPhone. I had some assumptions but the only way to know for sure was to analyze the atomic makeup of these parts. I had 3 main interests.
1) The screen, I had heard tall tales about Apple secretly using sapphire crystal for the front display. The reasoning behind this was of course the scratch resistant nature of the iPhone screen. Apple says it is "optical quality glass." Wouldn't Apple advertise such an extravagant feature? I had to know...
2) The shinny outer bezel. Was it aluminum, or steel? And what gave it that shinny finish?
3) The rear housing. Again aluminum? or something else?
With access to PSU's new $190 million nano fabrication facility I set my eyes on the "PERSONAL SEM". A small tabletop device located just outside the class 1,000 clean room. A cool $250,000 dollar machine with a single feature I had to try out, X-ray diffraction spectroscopy.
In short X-rays are shot toward the sample causing electron diffraction (X-rays hit the surface and knock off electrons). Specific elements give off characteristic signals that can be picked up and output by the machine. On a side note the X-ray producing portion of the microscope has to be cooled with liquid nitrogen prior to use.
Here we go...
On a cold November morning I set foot in the clean room with the sole purpose of determining what the heck my $500 iPhone was really made of. This may not seem like a big deal at first but let me again describe what goes into taking SEM images. The sample is placed in a small chamber which is pumped down to an operating pressure of .00005torr. Normal atmosphere is 760torr.... So you are basically subjecting whatever you put in that chamber to the vacuum of space. iPhone LCD, battery electronics...
Why is such a vacuum necessary you ask? To take an image 20,000 Volts of electricity are shot at the sample, knocking free electrons. Air in the chamber would cause the filament producing this charge to instantly vaporize, not to mention it would wreak havoc with the imaging. So again I was willingly, going to apply a 20,000V potential directly to my sensitive, new $500 iPhone.
I placed the phone in the chamber and began pump down. First with a roughing pump, kicking in the turbo-molecular pump at crossover. Then the waiting began. Not only did this pump have to pull all the gas out of the chamber but also all the moisture and gunk from all the crevices from within the phone. If you remember from science class water evaporates at room temperature at low pressure. While this process usually takes 5-10minutes the iPhone took an hour to pump down.
It was time. Turn on the electron gun and apply the 20kV.
Finally the pictures. They may not seem like much picture-wise but any geek would cream himself at the amazing spectrometry graphs generated.
Figure 9: iPhone Screen SEM
iPhone screen, main element: Si (Glass)!
Figure 10: iPhone Bezel SEM
iPhone Bezel, main element Fe (iron) secondary element Cr (chrome). With further analysis of the graphs it was determined both the bezel and rear logo are made out of 304 stainless steel.
Figure 11: iPhone Rear Housing SEM
iPhone rear housing, main element Al (Aluminum) secondary element (oxygen) Aluminum Oxide or anodized aluminum here!
I am fairly confident these are the first ever SEM images of an iPhone.
Part 3 - Plasma Enhanced Chemical Vapor Deposition of TiN
Now that the phone had been characterized I could set my attention on how to make it better. I focused on the front bezel and rear logo. Had they been chrome plated aluminum, plastic or anything other than hard steel, it would not have been to my advantage to utilize the unique properties of TiN. One engineer described it to me like this:
TiN is indeed very strong and wear resistant. Placing this hard "shell" over something soft would be like standing on mud covered in ice. The underlying material will not provide enough support to the TiN; thus allowing objects to deform the outer layer of TiN, resulting in a scratch. TiN will never crack or peel, but it must move with the underlying material.
One of the reasons it is used on hard cutting tools, Jet engine blades and surgical implants is its ability to magnify the strength and hardness of the all-so-important underlying material. Take stainless steel for example. On its own very strong and durable a TiN coating magnifies these properties creating a supper hard, durable surface.
The process to deposit TiN is also quite unique compared to other surface treatments such as plaiting and anodizing. TiN is deposited under vacuum in a plasma enhanced chemical vapor deposition (PECVD or PVD) tool. I find this process to be very cool.
A large disk of pure titanium called a target is inserted into the machine. Once at vacuum, nitrogen gas is flowed into the system and an electrical bias between the target and the gas generates a plasma. These positively charged particles are accelerated at high velocity toward the negatively charged titanium target. On impact these nitrogen ions knock free titanium atoms. You can think of it as atomic sand blasting. These atoms then fall coalescing on the surface of the parts to be treated with TiN.
Overall system, it is used for A LOT more than just TiN deposition, mostly for semiconductor manufacturing.
Here are some fun pictures of the PECVD tool:
Figure 12: PECVD
Figure 13: PECVD
The remaining rear housing now needed to be anodized black. A sample housing was stripped of its stock silver anodized treatment and anodized in a small scale acid bath with a DC power supply. The results were great but resulted in a surface that was very similar in durability to the stock apple anodizing treatment. With the goal set to not only change the appearance by also increase durability a more industrial treatment was needed. After some negotiations; a local hard anodizing shop took on the task of hard anodizing “Type II” some blank rear housings. Type II anodizing is 3-5 times thicker than regular anodizing. It must be performed under very strict conditions as to not burn the parts during the process. The acid tanks themselves are cooled to negative 35 degrees celsius while a DC bias is placed across the parts, oxidizing the surface. The finished parts are pictured below.
Figure 14: Finished housing components
Figure 14 shows the finished components. The rear housing has been hard anodized black and the two bezels have been treated with TiN (Gold) and TiAlN (Black).
Late at night a test fit was done easing everyones’ minds about fit and finish.
Figure 15: They Fit!
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