The Adsorption of Water on Mietallic Packages

This study presents data on both the chemical and physical processes of water adsorption/desorption on gold plated Kovar lids under various conditions of temperature cycling and ambients. In order to distinguish between chemical and physical adsorption of water on the surface, two analytical techniques have been employed. X-ray photoelectron spectroscopy (XPS), which is sensitive to a depth of approximately 20Å, provides the chemical data while the physical data are available via a quartz crystal oscillator technique which is sensitive to 1 Å (equivalent) of water on the surface. The data indicate that amounts of surface water can vary by more than an order of magnitude depending on materials and processing history. Under various operatinig conditions this surface water can be freed and thereby contribute to moisture related failure mechanisms.