9 - Water in Sealed Packages

Abstract

This chapter discusses various aspects of water in sealed packages which include water related corrosion and circuit failures, and water leaking into a sealed package from the outside environment. The contaminants that cause the corrosion are either negative or positive ions, using water as the carrier and the corrosion is often enhanced by electrical current in the circuit. The consensus, among scientists and engineers, is that the amount of liquid water necessary to promote corrosion is three monolayers. It is found that converting the three monolayers of liquid to water vapor yields different ppm for different size packages. It is suggested that the vapor pressure of the water on the inside of the package could be from outgassed materials in the package or from the water in the sealing chamber when the package was sealed. It is shown that the vapor pressure on the outside of the package is directly related to the relative humidity of the environment.