An extremely thin BGA format chip-scale package and its board level reliability

This paper outlines a study of an extremely thin (0.50 mm overall profile height) CSP (etCSP) and its board level reliability. This BGA format CSP has lead free solder balls and has been developed to meet the demands of the products for the compact and light portable consumer market segment. The package contains a cavity in the center where the die is placed. Due to its low profile, the properties of the molding resin used affected the amount of warpage in this CSP. In order to keep the package as flat as possible, different mold cap resins were evaluated and two of them were compared in component and board level testing. Because of the package design and the fact that die bonding is not required the etCSP showed a very robust moisture resistance test (MRT) performance of Level 1 260°C to JEDEC/IPC J-STD-020A Moisture Sensitivity Classification Testing. Board level reliability for the etCSP (176 I/Os) was examined and compared with that for a conventional laminate CSP (168 I/Os) with the same 12.00 mm sq. body size. It was found that the etCSP showed better results than the referenced CSP in some mechanical tests even though the ball pitch of the etCSP was 0.50 mm, while the reference package was 0.80 mm ball pitch.