4x4 Matrix Membrane Keypad, 16 Keys, Adhesive Back

This 4x4 membrane keypad packs 16 keys (digits 0-9 plus A, B, C, D, star, and pound/hash) into a thin, flexible membrane that can be mounted flush against an enclosure surface using its adhesive backing, rather than needing bulky mechanical push-button switches that protrude and require panel cutouts for each individual key.

Wiring follows the standard matrix-scan approach used across virtually all keypads this size: rather than needing one dedicated pin per key (which would require 16 separate microcontroller pins for 16 keys), the keys are arranged in a 4x4 grid where rows and columns are wired separately, letting a microcontroller scan through row/column combinations to determine which single key is pressed using only 8 pins total rather than 16 - a meaningful pin-count saving that's exactly why matrix-scan keypads are the standard approach for anything beyond a handful of buttons.

The membrane construction keeps the keypad extremely thin at just 1mm, with an overall footprint of 165 x 70mm, light enough and flat enough to mount directly onto a project enclosure's front panel without adding bulk. Electrical ratings are modest and appropriate for logic-level switching (0.1A operating current, 250VRms dielectric strength for insulation safety), confirming this is meant purely as a logic-level input device rather than anything carrying real power.

Builders working on a PIN-entry door lock, a numeric input panel for a menu-driven embedded project, a calculator-style interface, or any application needing compact, flush-mountable numeric and function key input will find this membrane keypad a well-proven, extremely common component, with mature matrix-scan library support across Arduino and most other microcontroller platforms.