How to prevent the window of the membrane switch from being scratched

For membrane switches with display windows, users have very strict requirements regarding the transparency of the window, and they cannot tolerate any imperfections. Sometimes, they even compare the quality of the display window to that of eyeglass lenses. As someone once said, "The customer is always right." So, how should we control the quality of the display window of membrane switches? Firstly, a high sense of quality is required, with strict control over every production step. The window and buttons of the membrane switch are integrated, and the production process of the buttons is complex with multiple steps. Every production step of the membrane switch must take into account protecting the window from scratches. Regarding the control of raw materials, transparency and scratch resistance tests must be conducted on the purchased raw materials. When selecting materials for membrane switches with display windows, it is essential to choose scratch-resistant materials, with front scratch resistance being particularly important. After purchasing raw materials, both sides of the material must be covered with protective film to prevent damage during cutting. If the material is not properly selected, scratching on the window will be difficult to control. In the printing environment, printing is usually carried out in a dust-free workshop. However, "dust-free" is only relative. For semi-automatic screen printing machines, the window is exposed for a relatively long time, especially for membrane switches with multiple colors. We can consider printing water-based protective paint on the window during the second printing process, so that the window can be protected during subsequent printing steps to avoid dust sticking to the window. After the final printing process is completed, a protective film can be applied. For automatic machine printing, protective film should be applied during each printing process, At the same time, it is important to ensure that the rubber roller is free from dust particles to prevent scratching the window.

In terms of operational standardization, it is prohibited to touch the window area at any stage of the production process, and wiping the window is also forbidden. Even with finger covers, any contact with the window area will leave marks, and even the slightest wiping may scratch the window.

The production of membrane switches involves numerous molds. The window area of the mold must be bright and smooth. During the production process, it is essential to repeatedly inspect the mold for debris to prevent damage to the window. Special attention should be paid to the window area of the screen printing plate to ensure there are no sand holes and to prevent oil leakage in the window area.

After printing, the panel must be double-sided laminated before entering the assembly and gluing process. Usually, after the circuit assembly is completed, the next process is to affix the panel. The protective film on the back side is removed, and the panel is affixed. After affixing, protective film is immediately applied to the window area.

Admittedly, even with strict production control, there are still imperfections in the window. It is up to the user to judge

The above standards are not uniform, and the following standards are for reference only:

There should be no more than 5 areas with a scratch size of 0.08mm×2cm, no more than 2 areas with a scratch size of 0.08mm×3cm, and no more than 10 areas with a scratch size of 0.08mm×1cm. The scratch areas should not be located in the center of the window. (Inspection area range: 90m×50mm. The acceptance criteria should be adjusted accordingly based on the increase or decrease in area.),

Standard for black spots, stains, and impurities: no more than three spots with a diameter of 0.1mm or less, and no more than 10 spots with a diameter of 0.05mm or less, with the defective area not located in the center of the window. (The panel area covered by this standard is 180×170mm, and the acceptance criteria will be adjusted accordingly as the area increases or decreases)