End-Of-Line Ionograph Clean Modification
Original Publication Date: 1987-Sep-01
Included in the Prior Art Database: 2005-Feb-01
A cleaning process used on first level metallized ceramic polyimide (MCP) circuit packages was determined to be the source of a white crystal contamination on the substrate surface. Spacing violations caused by the contaminant result in defective product. Scanning electron microscopy analysis was used to characterize the contamination as lead oxide and lead carbonate hydroxide. (Image Omitted) Formation of the contaminant is a result of interactions between water-air-lead-nucleation sites, with the nucleation sites taking the form of molecules, dust, etc. Experimentation shows crystal growth is a result of the following reactions: 1. MCP substrates removed from the ionograph clean have a thin film of highly reactive D.I. water (20+ megohm) on their surface. 2. The D.I.