Reliability Evaluation of 25 and 50 Mil Pitch Surface Mounted Plastic Leaded Packages

This paper addresses the attachment reliability of 25 and 50 mil pitch Surface-Mount (SM) plastic leaded perimeter packages for the thermal operating conditions and design life of telecommunications products. A comparative study was conducted on 25 and 50 mil pitch 68 I/O Plastic Leaded Chip Carriers (PLCCs) and 25 mil pitch JEDEC Standards Plastic Quad Flat Packs (PQFPs) with up to 244 I/Os. The JEDEC PQFP Leads were found to be four to five times more compliant than the standard 68 I/O PLCC J lead. The 6 mil leadframe thickness, to be compared to 8 mil for the J leads of interest, and the 95 mil overall height of the fine-pitch PQFP gull-wing leads are major contributors to lead compliancy.