Conductive ink

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Conductive ink is an ink that conducts electricity, allowing a circuit to be drawn or printed on a variety of materials including paper. It usually contains powdered silver and carbon.

Conductive ink is a cheap way to print circuit boards on paper. Silver ink is used to improvise or repair circuits on circuit boards. Computer keyboards contain membranes with printed circuits that sense when a key is pressed. Windshield defrosters are also printed.

Printed paper and plastic sheets have problematic characteristics, primarily high resistance and lack of rigidity. The resistances are too high for the majority of circuit board work, and the non-rigid nature of the materials permits undesirable forces to be exerted on component connections, causing reliability problems. Consequently such materials are only used in a restricted range of applications, usually where the flexibility is important and no parts are mounted on the sheet.