As an important part of modern electronic devices, the performance of touch panels directly affects the user experience. Among them, the hardness of the touch panel is a key indicator, which is directly associated with the screen's wear resistance and durability. The following is an in-depth discussion of the touch panel hardness of touch screens:
1. Definition of touch panel hardness
The hardness of a touch panel refers to the ability of the touch screen to resist abrasion. Higher hardness means that the screen is more resistant to scratches and abrasion, resulting in a longer lifespan. Hardness is usually expressed in terms of Mohs hardness, a measure of mineral hardness, proposed by the German mineralogist Mohs in 1822. The Mohs hardness scale divides hardness into 10 levels, from talc (the softest) to diamond (the hardest).
2. Test methods for touch panel hardness
Touch screen hardness test methods are varied, including punching test, writing test, surface hardness test, impact resistance test, static pressure resistance test, peeling test and anti-electromagnetic interference test. Among them, the surface hardness test is an important means of verifying whether the hardness of the surface layer of the touch screen meets the specifications. The following two methods are mainly used:
2.1. Pencil hardness test: This is one of the common methods to test the hardness of the touch screen. During the test, choose a pencil that meets the standard, sharpen the front end of the pencil into a cone, and polish the end of the lead core with sandpaper. Then, the pencil will be loaded onto the hardness test frame chuck, plus standard weights, so that the tip of the pen pressed on the surface of the touch screen. After pushing a distance at a constant speed, observe whether scratches appear on the surface of the touch screen. If deep scratches have appeared, the hardness of the touch screen does not meet the requirements. This method is simple and easy to implement, is one of the effective means of assessing the hardness of the touch screen.
2.2. Scratch test: Apply a certain pressure to the touch screen through mechanical devices, and use a specific hardness of the object (such as diamond) on the surface of the touch screen scratch test. Observe and record the depth and width of the scratches as well as the changes in the surface of the touch screen, so as to assess its hardness.
3. Factors affecting the hardness of the touch screen
3.1 Material Composition
The material composition of the touch screen panel has a direct impact on its hardness. In resistive and capacitive touch screen, glass is the commonly used panel material. The composition of glass panels can be divided into sodium calcium silicate, alkali aluminum silicate and borosilicate glass. Sodium calcium silicate glass and alkali aluminum silicate glass can be chemically strengthened by forming a stress layer on the surface of the glass through ion exchange, thus enhancing the hardness and toughness of the glass.
In addition, with the development of plastic materials, some new plastic materials are also used in touch screen panels. These plastic materials usually have similar transparency with glass and higher heat resistance and hardness, which can be used as an alternative material for reinforced glass.
3.2 Manufacturing Process
The manufacturing process is equally important to the hardness of the touch screen. For example, in the chemical toughening of glass panels, this is mainly achieved by a low-temperature type of ion exchange. During the exchange process, potassium positive ions exchange sodium positive ions in the glass. Since the radius of potassium positive ions is larger than that of sodium positive ions, the volume of the glass surface expands after the exchange is completed, forming compressive stress, thus increasing the hardness of the glass.
3.3 Environment
The use of the touch screen environment will also have an impact on its hardness. For example, the hardness of the touch screen may change in a low temperature environment. Therefore, in the design and testing process of the touch screen, it is necessary to consider its performance under different temperatures.
4. Technical methods to improve the hardness of touch panels
4.1 Chemical Reinforcement
As mentioned earlier, chemical strengthening is an effective method to improve the hardness of glass panels. By forming a stress layer on the glass surface through ion exchange, the hardness and toughness of the glass can be significantly enhanced.
4.2. Edge Strengthening
To address the robustness of integrated capacitive touch panels, researchers have developed a new process for edge strengthening. The use of ammonium fluoride instead of hydrofluoric acid as the main component of the strengthening etching solution, through the non-hydrofluoric acid salt solution to achieve the touch screen edge polishing and strengthening. This new process not only improves the edge strength of the touch screen, but also avoids the damage of the edge polishing process on the touch sensing layer and improves the reliability of the product.
4.3 Use of new materials
With the development of material science, some new materials are used in the manufacture of touch screen panels. These new materials usually have higher hardness and better wear resistance, which can effectively improve the durability of the touch screen.
With the continuous emergence of new materials and manufacturing processes, the hardness test methods and standards for touch panels also need to be updated and improved. Only by establishing scientific and reasonable test methods and standards can we accurately assess the hardness performance of touch panels and provide strong technical support for manufacturers.
In conclusion, the hardness of touch screen is an important part of its performance, which is significant for improving user experience and device durability. In the future, with the continuous progress of technology and the continuous development of the market, the hardness of touch screen will be further improved and perfected.