Aug 23, 2019
As a facial-recognition technology initially launched on iPhone X, Face ID has been applied to latest iPhones, including iPhone XS，XS Max and XR. With this amazing Face ID system, users can unlock their devices by scanning and confirming facial identity. Whether you are wearing a hat, putting on glasses or you are in the dark.
There are 8 components packed into the front of the phone.
Ambient Light Sensor
Dot ProjectorThe infrared camera, the dot projector and the front camera are located on the back glass assembly. The flood illuminator, the proximity sensor, the ambient light sensor, the speaker and the microphone are located on the display assembly. Please be careful when disassembling or repairing the phone. Damage of any component will cause Face ID failure.
Next, we will disassemble the flood illuminator module and the dot projector and find out the reason why Face ID can be so easily damaged.
Let’s disassemble the flood illuminator module first. Pry open the glass cover with a blade. We can see that there are many holes on the flood illuminator that are arranged in a matrix of 11x11. The chip is connected to the circuit board with the help of gold wires. Once water damaged, these holes can be blocked. And you will be faced up with Face ID failure.
Chip 1 is an unencrypted chip. Since some repair technicians have replaced it before, our guess is that chip 1 might be a boost chip or an EEPROM chip. So chip 2, chip 3, or chip 4 might be the encrypted chip. Still, due to the difficulty of replacing, no one has verified that. As you can see, with thousands of components integrated, the composition of the flood illuminator module is very precise.
Chip 2 is the flood illuminator.
Chip 3 and Chip 4 are proximity sensors that are responsible for receiving and transmitting respectively. The infrared light emitted from the two proximity sensors could be a single dot or a single set of dots. Independent of each other, the three chips are indispensable. And this is what you should know about the flood illuminator module. Let’s move on to the dot projector.
The camera parts of iPhone X work in the same way as front cameras of other iPhone series. Now we will focus on the dot projector. The outer layer of the dot projector is sealed with resin and protected by metal welding techniques. Pay attention to these welding points.
They can easily fall off once the phone is dropped. And once off, they cannot be restored. When disassembling, we need to cut open the outer metal cover at first. Then heat with the Hot Air Gun and remove the resin with tweezers. Once the dot projector has been detached, we can see a crystal that looks just like a diamond lens. The infrared light is emitted from here. Then reflected by the crystal. Its projection range is determined by the lens afterwards.
Pry open the crystal, here we can see the complete internal structure of the dot projector.
The chip on the left is used to store data, whereas the chip on the right side acts just like a projector. We can see that there are thousands of dots arranged here. The infrared light is emitted from here. Since necessary power supply is needed for chip on the right side to work normally, once water damaged, circuits here are most likely to get short. Which can also result in Face ID not working. And please be noted that the chip is exposed without black adhesive seal. So it can be easily damaged once water-damaged or dropped. What’s more, it also can not be restored once damaged. And this is the internal structure of the dot projector. Let’s continue with the crystal part of the dot projector.
We can see that there is a concave lens and a convex lens on the crystal. And the two are made of glass. Once dropped, Face ID can also be affected.
Judging by what we have learned during the disassembling, main circuits of the Face ID are exposed. Once water damaged or exposed to a relatively humid environment, there might be electricity leakage or short-circuit problem that can result in Face ID failure. What’s more, most of the Face ID parts are made of glass. Once dropped, Face ID is most likely to be unavailable.
In summary, Face ID can be easily damaged and hard to be restored. Therefore, please be very careful in daily use. Make sure the phone is protected from water-damage or heavy falling. Repair technicians must exercise caution when repairing the logic board or replacing the display assembly. Also, for those in need, we have summarized repair experience of REWA repair technicians and hereby present you the following troubleshooting guide on common Face ID failure.
Here is the detailed video for your reference.
When repairing iPhone logic boards, we identify the issue first, find out why it occurred next, and figure out how to fix it in the end. This is a general process adopted by professional repair technicians around the world.
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Apr 23, 2021
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