In few cases specially manufacturers of Membrane Key boards are using silver conductive paint/inks for making circuits,

Also the customer never learns about the disadvantages and risks of using silver ink while making "Membrane Key Boards".

However it works and low cost but to avoid failure risk we strongly recommend not to use silver paint/inks for making circuits. Flexible printed circuit boards (etched copper) is the ultimate solution for making flexible Key Boards and now its available in Indian Markets.

The flexible copper clad sheets is available in different base material, copper thickness even some are extremely flexible which you can fold it up-to 360 degree. The problem like silver migration or can say track or pad lifting is impossible.

Tin, Nickel or Gold platting options are also available and instead of using an adhesive as in the case of conductive silver ink technology, you can safely and permanently solder the LEDs and other components over the etched copper Key Boards.