Package On Package (PoP) Process Characterization And Capability Study
Authors: Kenny Chiong Kung Chuan, Tan Seak Huat, Ricky Liew and Tan How Chuan Company: Motorola Technology Sdn. Bhd. Date Published: 4/8/2014
Abstract: Basic functions for electronic devices are no longer adequate in our advanced society which now demands further miniaturization and higher performance portable terminal that supports worldwide application needs. As a result, Package on package (POP) has become a mainstream technology that emerges alongside with these demands. It is a configuration where two packaged integrated circuits are placed directly on top of each other to achieve mounted space savings on the board. POP stacks which currently in production or development consist of a bottom package containing a high performance logic device designed to receive a mating top package typically containing high capacity memory devices. This technology has been successfully applied in some of the Motorola laser scanner products but yet to be adopted in two way radios products in Motorola Penang. Solder paste dipping is a popular process to overcome the variations that occur between the ball mounting positions on the different levels of the POP device. The dip paste is applied directly onto the balls of the device on the placement platform using paste dipping feeder with the ideal dipping depth is 50-60% of the package ball height. When using dip paste on a placement system, the total tack force on the package must also be considered to avoid poor or incomplete pickups as well as the dipping depth during solder dipping. Meanwhile, reflow process parameters, such as preheat ramp rate, peak temperature, temperature above liquidus, and etc. using air flow or nitrogen oven play significant roles in achieving higher yield rate. The main industry problems associated with POP technology are solder short, open joints, and warping of the two levels of component substrate. Therefore, this paper will focus on evaluating the 0.5/0.65 mm pitch POP process characterization and capability using both Fuji and Siemens platform together with air vs. nitrogen reflow is a big part of this study.
Package on Package, Warpage, Solder Dipping, 0.4/0.5 mm Pitch, Fuji, Siemens, Reflow, Head-in-Pillow, 2D X-ray