Abstract: A packaging container including a humidity indicator system specifically designed for use in packaging electronic circuits, such as integrated circuits. The packaging container is prepared from a water and water vapor proof, anti-static packaging material and contains an opening therein. The humidity indicator system includes a humidity indicator element, a humidity comparison element and a securing system for securing the humidity indicator element to the packaging container, wherein the opening in the packaging material is closed by the humidity indicator system.

Abstract: An irreversible humidity indicator having a delayed response time includes a porous plastic carrier having upper and lower opposing surfaces, the upper surface including a depressed region for containing a deliquescent agent coated with a water soluble dye. A sheet of blotter paper overlies the upper surface of the porous plastic carrier and contacts the dye-coated deliquescent agent for absorbing the water soluble dye, and thereby providing an irreversible indication, when the humidity level directly surrounding the deliquescent agent is sufficiently high to dissolve the deliquescent agent. The plastic porous carrier is packaged to isolate the upper surface thereof from direct exposure to the environment to be monitored, and the density and thickness of the plastic porous carrier are selected to delay the passage of moisture-laden air from the lower surface to the depressed region thereof for a predetermined time.