The Redistributed Chip Package (RCP) is a substrateless embedded chip package that offers a low-cost, high performance, integrated alternative to current wirebond BGA and flip chip BGA packaging. Devices are encapsulated into panels while routing of signals, power, and ground is built directly on the panel. The RCP panel and signal build-up lowers the cost of the package by eliminating wafer bumping and substrates thereby enabling large scale assembly in panel form. The build-up provides better routing capabilities and better integration. Also, by eliminating bumping, the device interconnect is inherently Pb-free, and the stress of the package is reduced enabling ultra-low K device compatibility. The panel is created by attaching device active side down to a substrate, encapsulating and curing the devices, grinding to desired thickness, and then removing the substrate. Signal, power, and ground planes are created using redistribution-like processing. Multi-layer metal RCP packages have passed -40 to 125C air-to-air thermal cycling and HAST after MSL3/260 preconditioning.
In discrete radio frequency (RF) microelectromechanical systems (MEMS) packages, MEMS devices were fabricated on silicon or galium arsenide (GaAs) chips. The chips were then attached to substrates with die attach materials. In wafer-level MEMS packages, the switches were manufactured directly on substrates. For both types of packages, when the switches close, a contact resistance of approximately 1 exists at the contact area. As a result, during switch operations, a considerable amount of heat is generated in the minuscule contact area. The power density at the contact area could be up to 1000 times higher than that of typical power amplifiers. The high power density may overheat the contact area, therefore affect switch performance and jeopardize long-term switch reliabilities.In this paper, thermal analysis has been performed to study the heat dissipation at the switch contact area. The goal is to control the "hot spots" and lower the maximum junction temperature at the contact area. A variety of chip materials, including Silicon, GaAs have been evaluated for the discrete packages. For each chip material, the effect of die attach materials has been considered. For the wafer-level packages, various substrate materials, such as ceramic, glass, and low-temperature cofire ceramic (LTCC) have been studied. Thermal experiments have been conducted to measure the temperature at the contact area and its vicinity as a function of dc and RF powers. Several solutions in material selection and package configurations have been explored to enable the use of MEMS with chips or substrates with relatively poor thermal conductivity. For discrete MEMS packages, placing the die inside a copper cavity on the substrate provides significant heat dissipation. For wafer-level packages, thin diamond coatings on the substrate could reduce the hot-spot temperature considerably.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.