RELIABILITY PERFORMANCE ASSESSMENT AND CHAFtACTERIZATION OF FINE PITCH MOLD ARRAY BGA
Author: Trent Thompson Company: Motorola Semiconductor Product Date Published: 8/23/1998
Surface Mount International
Abstract: This report summarizes evaluations performed to characterize and determine the moisture sensitivity level performance of the fine pitch (0.8 mm and 1 .O mm pitch) mold array process (MAP) ball grid array packages. The advantages of the MAP BGA versus the standard PBGA and glob top BGA (GTBGA) from a cost and package design stand point to meet the Cellular phone market’ s demand for thinner, smaller and lighter packaging are also discussed. There are multiple issues to consider for both thin (1.3 mm) and thick (1.7 mm) MAP BGAs. This report also addresses the impact on assembly from warpage due to thinner substrates, low loop wire bonding and thin molding. It will also cover the materials used and their advantages. For example, non conductive die attach epoxies and advanced molding compounds that decrease strip warpage and wire sweep at mold. Results using an optimized flag design will also be reported.. Also discussed in this report are solder ball adhesion and solder joint reliability obtained in characterizing the 1 .O mm pitch BGAs. Various studies have been conducted to determine the moisture sensitivity level of this new package family which range in body size from 7x7 mm to 17x17 mm for both thick and thin profiles. The reliability test response used was C-SAM (C-Mode Scanning Acoustic Microscopy) to inspect for delamination at various package interfaces abler moisture sensitivity level 1, 2 and 3 preconditioning. Also included are studies that were conducted to further improve the moisture performance of the package by using special flag coatings and pre-bakes on the BT resin substrates. Thermal and electrical characterization data will be included to give a base line comparison between this package and the standard LQFP. Future work and recommendations will be provided on package performance improvement and the demand for even lower ball pitch (0.65 or 0.5 mm) and profile BGAs (1 .O mm) on future product.