Feasibility study of silicon nitride protection of plastic encapsulated semiconductors

The application of low temperature silicon nitride protective layers on wire bonded integrated circuits mounted on lead frame assemblies is reported. An evaluation of the mechanical and electrical compatibility of both plasma nitride and photochemical silicon nitride (photonitride) passivations (parallel evaluations) of integrated circuits which were then encapsulated in plastic is described. Photonitride passivation is compatible with all wire bonded lead frame assemblies, with or without initial chip passivation. Plasma nitride passivation of lead frame assemblies is possible only if the chip is passivated before lead frame assembly. The survival rate after the environmental test sequence of devices with a coating of plasma nitride on the chip and a coating of either plasma nitride or photonitride over the assembled device is significantly greater than that of devices assembled with no nitride protective coating over either chip or lead frame

Spatial and seasonal patterns and long term variability of the composition of the haze in the United States: an analysis of data from the IMPROVE network

July 1996.Principal investigators: William C. Malm, Marc L. Pitchford.Includes bibliographical references.This report describes data for the three year period, March 1992 through February 1995, of the Interagency Monitoring of Protected Visual Environments (IMPROVE) measurement program. IMPROVE is a cooperative visibility monitoring effort between the United States Environmental Protection Agency, (EPA) federal land management agencies, and state air agencies