Membrane assembly
Provided by the ASK Keyboard Dictionary
A membrane assembly is a form of layered circuitry primarily used as the sensor for key-switches that rely on ohmic sensing. It is comprised of plastic (such as Mylar/BoPET) sheets with electrical traces and predefined contact points screened onto them. Typically, an IBM and family keyboard membrane assembly will have three layers - a sense line circuit membrane on top, an insulator layer acting as a spacer, and a drive line circuit membrane on the bottom. The sense and drive circuits are the two axes of the keyboard's matrix, with sense being the matrix rows that electricity is fed through and the drive being the matrix columns that are monitored from returning electricity. On its own, a membrane assembly is incapable of providing any meaningful auditory and/or tactile feedback. Thus, a common and economical pairing for them are rubber dome actuators to provide a tactile response. However, more complex
