Foldable smartphones have long been associated with a major constraint: their thickness. Stacking two screens, integrating a complex hinge, and maintaining sufficient rigidity led early models to display dimensions significantly larger than traditional smartphones.
Since then, manufacturers have been striving to slim down these devices to bring them closer to traditional formats. This quest for thinness is not solely based on an aesthetic goal. It directly affects ergonomics, transport, and the overall perception of the product.
However, reducing the thickness of a foldable smartphone is not simply about compressing its components. Every millimeter gained imposes technical compromises concerning the solidity, durability, and reliability of the whole.
In a foldable smartphone, each component is subject to specific mechanical constraints. Unlike a monoblock device, the structure must withstand repeated cycles of folding and unfolding.
Reducing the thickness involves thinning the internal layers: screen, battery, chassis, protection. However, the thinner these elements are, the more sensitive they become to deformations. The overall rigidity of the device then depends on a delicate balance between flexibility and resistance.
Manufacturers like Samsung or Huawei are working on metal alloys and composites capable of maintaining high strength despite reduced dimensions. These materials must absorb mechanical stresses without cracking or deforming in the long term.
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The hinge is the mechanical heart of a foldable smartphone. Its design directly influences the final thickness of the device.
The first generations used relatively bulky mechanisms necessary to ensure stable opening. Recent models adopt more compact systems, integrating multiple axes, miniaturized gears, and waterdrop structures that reduce the space occupied by the screen when folded.
Brands like Honor or Oppo have introduced thinner hinges capable of limiting the gap between the two parts of the screen once folded.
However, this size reduction requires extreme precision in assembly. Too low a tolerance can accelerate wear, while too much play can affect the stability of the screen.
The screen of a foldable smartphone is not just a simple flexible surface. It is a complex stack of several layers: substrate, OLED layer, protection, touch film.
Reducing the overall thickness involves thinning each of these layers without compromising their strength. Manufacturers use materials like ultra-thin glass (UTG), capable of bending while retaining some rigidity.
However, the thinner the glass, the more fragile it becomes against shocks or localized pressures. Screen protection remains a major issue, especially to avoid visible marks or damage related to daily use.
The battery also plays a central role in the thickness of a foldable smartphone. Unlike classic models, it is often divided into two modules distributed on either side of the hinge.
This configuration allows for weight balance and frees up space for the folding mechanism. However, reducing the thickness requires decreasing the size of these modules or increasing their energy density.
Companies like Xiaomi are exploring more compact battery technologies capable of storing more energy in a reduced volume. This approach allows devices to be slimmed down without sacrificing their autonomy.
A foldable smartphone undergoes complex internal forces. During folding, some areas are compressed while others are stretched. This distribution of constraints must be perfectly managed to avoid any premature degradation.
Reducing the thickness accentuates these phenomena. Materials have less margin to absorb constraints, which can increase the risk of mechanical fatigue in the long term.
Engineers use advanced simulations to analyze these constraints and optimize the internal structure. Each component must be positioned to distribute forces evenly, thus avoiding weak points.
A thinner device is generally more sensitive to shocks. In the case of foldable smartphones, this sensitivity is amplified by the presence of the hinge and the flexible screen.
Manufacturers must therefore reinforce certain strategic areas, such as edges or contact points, while maintaining reduced thickness. This involves integrating internal reinforcements or shock-absorbing materials.
This search for balance between thinness and resistance is one of the major challenges in the design of foldable smartphones.
Reducing thickness also complicates the integration of sealing systems. With internal spaces being more restricted, it becomes more difficult to add seals or protections against dust and moisture.
Some recent models have nevertheless managed to integrate a water resistance certification, proof of progress made in this area. However, this integration requires extreme precision in design and assembly, especially at the hinge level.
Reducing thickness does not only result in a technical improvement. It also influences the user’s perception of the product.
A thinner foldable smartphone is often perceived as more modern, more pleasant to handle, and closer to the standards of classic smartphones. This perception plays an important role in the adoption of these devices.
However, excessive thinness can also make the device more difficult to handle, especially in the open position, where the grip must remain stable and comfortable.
The reduction of the thickness of foldable smartphones depends on several factors:
Current progress shows that it is possible to approach the dimensions of classic smartphones once folded. However, achieving equivalent thinness while maintaining high durability remains a complex goal.
Every millimeter gained requires innovations on several fronts simultaneously. An isolated advance is not enough; the entire system must evolve coherently.