When the requirement of a membrane keypad comes to water proofing, it is very often related to the term: IP Liquid Ingress Protection Marking.
Central Midori has its first product IP67 certified in the Year 2007.
A conventional membrane keypad comprises subparts like the Graphic Overlay, Overlay Adhesive, Dome Holder, Spacer, Conductive Printed PET, Backer & components like Tactile Domes & LEDs. The Gasket is integrated with all mentioned above to construct a water proofing membrane keypad.
There are few key points to a water proofing membrane keypad.
- Construction Concept: Mainly, settling the membrane switch profile within a gasket, encircling the initial & protecting it from the environment.
- Overall Bill of Material (BOM): Thickness of the membrane switch whereby the switch layer printing thickness also taken into consideration, should flush with the gasket making them even as a whole.
One whose height is greater than the gasket will budge and cause delamination over time between the product & the interfacing panel, eventually water leakage.
- Width of the gasket: It holds one of the crucial factor dictating the strength of water immerse pressure protection.
- Gasket Adhesive Tape Selection: Not neglecting the gasket, industrial closed cell foam carrier tapes are among the options providing superb adhesion strength.
- Enhancement: For an even more stringent environmental requirement, the conductive printed PET can be substituted with a double-sided through-hole, single conductive print design where the insulator between the two conductive print is the substrate itself, posing an advantage over the insulating dielectric print depreciation between conductive prints of a single sided design when functioning in a high humidity environment.
We discussed on the details of a water-proofing membrane keypad, a well designed BOM of the membrane keypad while limited to the gasket adhesive thickness should not be disregarded of its desirable tactile feedback.
This is important to us as membrane keypad manufacturer. Details of exemplary cross-sectional BOM of a water-proofing membrane keypad will be discussed in continuation on the next post.
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