In the world of the mobile industry, where every millimeter of the body matters, and manufacturers compete for the maximum ratio of screen area to device dimensions, you can often notice one striking detail. We are talking about the so-called “chin” - the bottom frame of the display, which in many models remains noticeably wider than the top or side edges. This visual imperfection irritates perfectionists and raises questions among users accustomed to the ideal symmetry of flagships from Apple or top-end Samsung models.
However, behind this apparent design omission lies a complex engineering reality associated with matrix production technologies and the logistics of supplying components. Smartphone chin this is not a whim of the designer, but a physical necessity for the placement of cables and control electronics, which cannot be “hidden” in the side edges without significantly increasing the cost of the final product. Understanding this process requires immersion in the design of modern displays.
In this article we will take a closer look at why the bottom frame is often wider than the top, what technologies can get rid of it, and whether it’s worth overpaying for ultra-thin devices. You will learn about the differences between the types of matrices and how the evolution of production processes is gradually changing the appearance of our gadgets.
Technology: where the cables are hidden
The main reason for the existence of the “chin” lies in the way the matrix is connected to the control board. At the heart of any modern screen is a panel that generates an image and a controller that sends signals to it. This controller is often placed directly on a flex cable that extends from the bottom of the display. In the classic design, this cable must be bent back, behind the matrix itself, in order to connect it to the main board of the smartphone.
The location of the bend and the thickness of the cable itself create a physical gap, which forms the very bottom frame. The thicker the train and the smaller the radius of its bend, the wider the “chin” becomes. Engineers are constantly working to reduce the thickness of these components, but there is always a physical limit. Technology (encapsulation) in this context determines how tightly electronic components can be packed at the edge of the screen.
⚠️ Attention: When replacing the screen yourself on models with a thin “chin”, it is extremely high risk of damaging the cable when bending. Use only specialized tools to heat the glue and carefully remove the matrix.
There are several methods for solving this problem, which are used depending on the class of the device. In the budget segment, manufacturers often use standard modules, where the cable takes up more space. Top models use more complex and expensive solutions to minimize this area or completely eliminate it.
Technical detail
What are COG and COP?: COG (Chip on Glass) - the chip is installed directly on the glass, which requires more space for the cable. COP (Chip on Plastic) - the chip is installed on a flexible base, which allows you to bend the cable more and reduce the frame.
Differences between IPS and OLED matrices
The type of matrix used plays a decisive role in the thickness of the lower frame. Traditional IPS screens (In-Plane Switching) have a rigid backlight and layer structure, which makes them less flexible in terms of placement of control electronics. In such displays, the cable usually exits from the bottom and requires a certain amount of space for bending, which often leads to a more pronounced “chin” compared to OLED counterparts.
Technology OLED (Organic Light-Emitting Diode) offers more room for maneuver. Since each pixel in an OLED matrix lights up independently, there is no need for a massive backlight layer, which allows for thinner screens. Moreover, the use of a flexible plastic base instead of glass (Flexible OLED technology) allows you to bend the cable almost at a right angle, reducing the bottom frame to a minimum.
When choosing a smartphone, pay attention not only to the diagonal, but also to the type of matrix. OLED screens not only provide better blacks, but also often allow the manufacturer to make the device more compact with thinner bezels.
However, even among OLEDs there are differences. Hard OLED panels can still have a noticeable “chin”, since their base does not allow for a critically small bend radius of the cable. Only flexible OLEDs (Flexible OLED) give the same “frameless” effect that we see in flagship devices of recent years.
| Characteristics | IPS LCD | Hard OLED | Flexible OLED |
|---|---|---|---|
| Presence of backlight | Required | Not required | Not required |
| Base flexibility | No (glass) | No (glass) | Yes (plastic) |
| Chin thickness | Medium/Large | Medium | Minimum |
| Production cost | Low | Medium | High |
This is why in budget smartphones, where (cost control) is a priority, we more often see IPS screens with noticeable frames. The transition to flexible OLED panels is a step that significantly increases the cost of the device, which is not always justified in the lower price segment.
Economic aspect: why is this beneficial for manufacturers
The issue of cost is acute for electronics manufacturers. The use of advanced technologies to reduce frames, such as COP (Chip on Plastic) or COF (Chip on Film), is significantly more expensive than a standard assembly. The price difference between a module with a wide “chin” and a screen with ultra-thin frames can be tens of dollars in terms of mass production.
For companies that produce millions of devices, this is a colossal amount. Therefore, in the mid-range and budget smartphone segment, manufacturers often compromise by leaving the bottom frame slightly wider than the top. This allows you to use cheaper components and maintain a competitive price on the store shelf, without sacrificing screen diagonal or battery capacity.
In addition, standardization of components simplifies logistics. The same screen with a certain frame size can be used in several smartphone models of different years. Developing a unique display with minimal frames for a specific model is an additional expense on R&D (research and development), which pays off only in the premium segment.
Evolution of technology: from COG to COP
To understand how engineers fight for every millimeter, you need to consider the evolution of control chip mounting methods. Previously, technology COG (Chip on Glass)was widely used, where the controller was placed directly on the glass part of the matrix. This required significant space, since the cable had to be brought out and bent, leaving a wide lower frame.
The next step was the introduction of technology COF (Chip on Film). In this option, the chip is transferred to a flexible film, which makes the film itself narrower and, accordingly, reduces the bending radius. This made it possible to significantly reduce the size of the “chin”, and we saw this progress in smartphones a couple of years ago.
Currently, the pinnacle of engineering is technology COP (Chip on Plastic). Here the chip is installed on a flexible plastic base, which is a continuation of the matrix itself. This allows you to bend the cable almost 180 degrees, hiding it completely behind the screen. It was thanks to COP that the bottom frame became visually equal to the top, creating the effect of a continuous canvas.
Evolution of technology:1. COG (Chip on Glass) -> Wide frame
2. COF (Chip on Film) -> Middle frame
3. COP (Chip on Plastic) -> Minimum frame
However, even COP technology has its limitations. It requires the use of flexible OLED panels, which, as mentioned earlier, are more expensive to produce. In addition, the folding space still takes up volume inside the case, which can affect the placement of other components, for example, a battery or a vibration motor.
Impact on the ergonomics and design of the device
The presence or absence of a “chin” directly affects the perception of the device in the hand. Smartphones with symmetrical thin frames look more modern and premium. Visually, the screen appears larger and the boundaries of the device are blurred, creating an immersive effect. This is especially important for devices with large diagonals, where one-handed operation is difficult.
On the other hand, the presence of a bottom frame is sometimes used by designers as a functional element. For example, some gaming or business devices may have a slightly wider bottom bezel to provide a more secure grip without accidentally touching the screen with your palm. This space is also sometimes used to place a brand logo, although in recent years this trend has become a thing of the past.
☑️ What to look for when buying a smartphone with thin frames
Ergonomics also suffers from attempts to make the frames minimal at any cost. Too thin side edges can lead to accidental presses (false touches) when the palm touches the edge of the screen. Manufacturers are forced to implement software algorithms to protect against false clicks, which, however, do not always work perfectly.
Future without frames: where the industry is heading
The industry is moving towards the complete disappearance of visible frames. Concepts of “waterfall smartphones”, where the screen is curved onto the side edges, have already become a reality, although not without controversial issues in terms of durability. The next logical step will be a complete abandonment of cutouts and holes in the screen, which will require moving the front camera under the display.
Under-screen camera technologies already exist, but are still inferior in quality to traditional solutions. Once this barrier is overcome, the "chin" will be the last bastion to fall under the onslaught of engineers. However, physical laws will not go away: cables and connections will always be needed, they will just become even thinner and more invisible.
⚠️ Attention: Screen production technologies are changing quickly. Features that are relevant for current year models may become standard for the mid-segment in 1-2 years. Keep an eye on the official specifications of the new processors and displays.
Ultimately, the "chin" is a temporary compromise between technological capabilities, cost and design. Every year it becomes smaller, and soon, perhaps, we will remember the wide bottom frames as a funny artifact of early smartphones.
Main conclusion: The width of the “chin” depends primarily on the type of matrix (IPS or OLED) and the cable mounting technology (COG, COF, COP). In the budget segment, a wide bottom frame is a way to reduce the cost of the device.
Understanding these processes helps to soberly evaluate offers on the market. If perfect visuals are important to you and you are willing to pay for it, choose flagships with Flexible OLED and COP technology. If the priority is autonomy and price, then the presence of a small “chin” on an IPS screen is an acceptable price to pay for savings.
FAQ: Frequently Asked Questions
Is it possible to programmatically hide the “chin”?
No, it is impossible to programmatically remove the physical frame. The “chin” is a hardware design feature of the display and case. Software black bars can only visually straighten the image if the screen has a non-standard aspect ratio, but they will not remove the frame itself.
Does a wide “chin” affect the strength of the screen?
Paradoxically, yes. Having a wider bottom bezel often means the display has a buffer zone. When dropped on an edge or corner, the impact load may fall on the frame and not on the glass of the matrix, which increases the chances of surviving the fall without cracks.
Why does the iPhone have a lower frame that is thinner than many Android smartphones?
Apple uses advanced technologies for the production of OLED panels (often of its own design or exclusive orders from Samsung/LG) and uses COP technology in mass production, which minimizes the plume. In addition, the high price of devices allows the use of more expensive components.
Will all screens in the future become frameless?
There is a desire for this, but a complete abandonment of frames is unlikely in the near future. The frame is needed to protect the edges of the matrix from chipping, to house the sensors, and to ensure the structural integrity of the case. Most likely, we will see a further thinning of the frames to the minimum possible physical limits.
Does the “chin” affect the quality of communication?
Directly - no. However, antenna modules are often located at the bottom of the case. The design of the bottom of the smartphone, including the screen frame, is taken into account by engineers when designing antennas to ensure optimal signal. Changing the geometry may require reconfiguring the antenna module.