BEHAVIOR OF PACKAGE WITH INTEGRATED HEAT SPREADER

摘要

FCBGA has been a common package technology to achieve higher Input/Output (IO) count. In moving toward higher IO count without increasing the package size, FCBGA package with tighter pitch is required. Finer pitch BGA creates challenges in solder joint reliability (SJR) and package-board interaction on the SJR becomes more obvious. Power requirement is on the increasing trend together with the IO density. Heat sink is normally used as a means of thermal enhancement for the FCBGA package. It is usually attached to the FCBGA package with a mechanical load exerting to the die backside through a heat sink clip. As the power requirement increases, heat sink alone is not sufficient to control the die junction temperature and degrade the package performance. One of the means to enhance heat dissipation from the die is by adding an integrated heat spreader (I-HS) to the package. I-HS improves the thermal performances by increasing the effective heat transfer area exposed to the heat sink. Package-board-system interaction on SJR is a key factor to be considered for BGA packages with finer pitch & stringent thermal requirement. Extensive studies were performed on 1mm ball pitch FCBGA package to identify critical design factor for reliable solder joints. The studies focus on the thermo-mechanical performance and mechanical performance of package with and without I-HS. Careful design and selection of package, board and thermal solution design are required for SJR. This paper discusses factors to be considered in the design for SJR and compares the differences between package with and without I-HS.