As we all know, the vivo X21 with the under-display fingerprint scanner will start the pre-orders on March 28. Except for under-display fingerprint technology, the X21 also adopts Face Wake. Today, we will start the teardown of this phone to explore its internal structure and the secret of the under-display fingerprint reader.
First of all, remove the SIM card tray.
The top part of the SIM card tray uses a rubber ring to prevent vapor and dust from entering inside of the phone body, and that’s the design that most water-resistant phones have adopted. It is not surprising for me to see the X21 adopt such a design since we have found that vivo attaches much importance to the phone’s sealing effect.
Take out two screws at the bottom.
The back cover uses many graphite stickers, and its surface is covered with a foam framework.
After removing the key cap from the phone body, we find that this part hasn’t adopted a rubber ring like the iPhone does.
The vivo X21’s internal design is quietly different from its predecessors. The motherboard occupies less area, and modules at the bottom increase the area they occupy, which results from the SIM card tray’s removal from the top to the bottom. Remaining the 3.5mm earphone jack, the phone inherited powerful HiFi capability from the vivo family.
We find that all the connectors on the motherboard are fixed by the metal plate to avoid getting disconnected by falling down, except the coaxial line connection. Besides, all the visible capacitors are processed with black glue to avoid short circuits caused by vapor. The earphone port is sealed by a black rubber ring, which shows the phone’s excellent sealing.
Next, we need to disconnect the ribbon cable of the motherboard. Firstly, we need to uncover the graphite sticker on the shield cover. There is heat dissipation copper sheet under the graphite sticker. Such heat dissipation design is not common since most phones usually choose either graphite sticker or heat dissipation copper pipe.
There is a screw hidden under the graphite sticker. This screw and the other two screws are used to fix connectors at the bottom to protect the cover plate. We remove these screws.
After uncovering the cover plate, we find five ribbon cables at the bottom. So, we need to use an insulating pry to disconnect the battery connector on the right to power off the system in case of a short circuit.
With all the screws and ribbon cable removed, we can easily take out the motherboard.
Both the motherboard’s front and back parts have high space utilization, and two shield covers are placed extremely close. If not taking the camera into consideration, the area that the phone’s motherboard occupies is basically the same as the iPhone X’s dual-layer motherboard. However, the iPhone X’s motherboard contains a single SIM card slot, while the vivo X21’s remains the 3.5mm earphone port.
The phone has a 12MP camera with an F/1.8 aperture on the back and a secondary 5MP camera with an F/2.4 aperture on the front. It also features a 12MP front camera with an F/2.0 aperture. The model focuses on AI functions.
The orange part is an octa-core Qualcomm Snapdragon 660AIE processor, which has four cores up to 2.2GHz and four cores up to 1.8GHz. The memory and flash are placed in the green area. There is no information on them, but the official party announces that it has 6GB RAM and 128GB storage. The blue area is skyworks77643-31. The red part is the Qualcomm frequency transceiver SDR660.
Uncover the heat dissipation copper sheet on the shield cover of the front of the motherboard. We find that the shield cover is welded to the motherboard, so it can’t be removed. Considering that the device’s internal components can’t be destroyed, we stopped removing the shield.
The X21 sports a Li-Polymer battery. Its normal voltage is 3.85V, and its limited charge voltage is 4.4V. Its capacity is 3200mAh, or 11.85Wh.
Then, remove the loudspeaker module. We know that the loudspeaker is from ACC. We infer that it is a new patent of ACC technology to make it sound clearer.
Later, take out PCB. The front connector and visible circuit adopt a rigid sealing design as the motherboard. Besides, the charge port is protected by a black rubber ring. The back of the PCB is basically occupied by a SIM card slot. It is not common to see that the phone features the PCB with its back part utilized.
Now, we will unveil the secret of the under-display fingerprint scanner. Heat screen edges, and then insert a pick along the slot into the screen plate to separate the screen from the roll cage.
The screen’s verge is less than 1mm away from the verge of the glass plate. The little space needs to be covered with a double-sided adhesive, which is used to fix the screen tightly to the phone’s body. Such a small space has been left for the super narrow bezel.
The under-display fingerprint reader is placed right under the middle of the screen. This fingerprint reader looks no different than other fingerprint readers, but it needs to be recognized through a screen and a glass pane. That’s the difference between it and other fingerprint readers since the common fingerprint reader can only identify fingerprints through thin glass.
Besides, we find that the phone applies COG sealing technology to the bottom of the screen. This technology is to curl the ribbon cable of the screen under the screen to make it much more convenient to make the screen chin occupy less space. The picture shows that the chin is extremely narrow but still thicker than the bezels on two sides since it needs to leave space for the ribbon cable.
Summary
We have removed 17 screws from the phone body in total. The vivo X21 has left a deep impression on me with its rigid sealing design, compact internal structure, and high space utilization. Besides, the phone’s CFM process has improved a lot compared with its predecessor. We are looking forward to seeing its performance in the market.
