CHARACTERIZATION OF OSP FOR FLIP CHIP PBGA PACKAGING
Authors: Li Ann Wetz, Keri Kirschenbaum Company: Motorola, SPS Date Published: 2/13/2001
Pan Pacific Symposium
Abstract: For years surface finish, specifically on the ball grid array (BGA) side of chip scale packages (CSP), has been a source of concern. Organic Solderability Preservative (OSP) is an organic coating used to prevent the corrosion of copper surfaces on BGA substrates. OSP coatings can be affected by exposure to elevated temperatures (particularly those required by lead-free solder processing), humidity and other process parameters. Degradation of the OSP coating prior to sphere attach could adversely affect wetting and joint integrity of BGA joints. This paper studies the effects of: OSP type, OSP thickness, solder alloy, flux type, and thermal processing.