Display Windows of Membrane Switches: How to Prevent Scratches

Label:Display Windows, Membrane Switches

Sep 5, 20232020

Display Windows of Membrane Switches: How to Prevent Scratches

We have all seen membrane switches with display windows. Customers have strict requirements on the transparency of the windows. We cannot tolerate any flaws. I remember someone said that customers are always right. How do we control the quality of display windows?


First of all, there must be a high degree of quality awareness, and strict control of each production link. The window of the membrane switch is integrated with the button. The production process of the button is complicated, and there are many processes. Every production link of the membrane switch must consider protecting the window from scratches.


What about raw materials? Test the transparency and scratch resistance level of purchased raw materials. When selecting materials for membrane switches with display windows, it is necessary to choose anti-scratch materials. The front-side anti-scratch level is particularly important. When we get raw materials, there must be protective films on both sides of the materials. Choose bad things, the scratches of the window are difficult to control.


Let's talk about printing environment. Printing is usually done in a dust-free workshop. Dust-free is only theoretical. For semi-automatic screen printing, the window is stored for a long time, especially for membrane switches with more colors. We can consider printing on the window in the second pass. The position is printed with water-based protective paint, so that the subsequent printing process can protect the window to prevent dust from sticking to the window, and then cover the protective film after the last printing. For automatic printing, each printing process must be covered with a protective film.


At the same time, it should be noted that the rubber roller cannot be stuck with dust particles to prevent the window from being scratched.


The standardization of operation is important. It is forbidden to touch the window area in every link of the production process. It is also forbidden to wipe the window. Even if it has finger cots, if it touches the window area, it will leave a print. Even a slight wipe may scratch the window.


There are many moulds in membrane switch production. The window area of the mold must be bright and flat. During the production process, check repeatedly whether there is debris on the mold to prevent the window from being crushed. Special attention should be paid to the window area of the screen printing screen. There should be no trachoma, and oil leakage in the window area should be strictly prevented.


After printing, the panels must be laminated on both sides and enter the assembly and glue link. Usually, after the circuit assembly is completed, the next process is to attach the panel. Remove the protective film on the back and attach the panel, and immediately cover the window area with a protective film.


It is true that after strict production control, the window is still flawed. Customers have different standards for judgment. The following standards are for reference only:


No more than 5 scratches with an area of 0.08mm×2cm, no more than 2 places with an area of 0.08mm×3cm, no more than 10 places with an area of 0.08mm×1cm. The scratched area is not in the center of the window. (Range of inspection area: 90m×50mm, according to the increase and decrease of the area, the acceptance criteria will be adjusted accordingly)


Standards for black spots, stains, and miscellaneous spots: no more than three spots with a diameter of 0.1mm or less, no more than 10 spots with a diameter of 0.05mm or less. The spot area is not in the center of the window. (The area range of this standard panel is 180×170mm, according to the increase and decrease of the area, the acceptance standard will be adjusted accordingly)


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