Membrane circuit board and keyboard device with same

A keyboard device, comprising:

• a membrane circuit board comprising:
• a first flexible circuit board, wherein a first circuit pattern is formed on the first flexible circuit board, and the first circuit pattern comprises an upper metallic conductor line and an upper contact;
• a second flexible circuit board, wherein a second circuit pattern is formed on the second flexible circuit board, and the second circuit pattern comprises a lower metallic conductor line and a lower contact corresponding to the upper contact, wherein the upper contact and the lower contact are separated from each other by a spacing distance, and the upper contact and the lower contact collectively defined as a membrane switch;
• and
• a nanomaterial layer comprising plural polymeric structures,
• wherein the nanomaterial layer is formed on the first flexible circuit board, the second flexible circuit board and/or a junction region between the edge of the first flexible circuit board and the second flexible circuit board to prevent at least one of the upper metallic conductor line and the lower metallic conductor line from contacting with a specified chemical element, so that conductive impedance of the upper metallic conductor line and the lower metallic conductor line is not affected by the specified chemical element;
• and
• a key structure for triggering the membrane switch.