Overview of Fan-out Wafer Level Package (FO-WLP)

Summary form only given. IC packaging technology has been evolving fast and diversely in the past decade, from high-end to low-end application, such as 3D IC integration with TSV, 2.5D with TSV-Si interposer, Package-on-Package (PoP), Fan-Out Wafer-Level-Package (FO-WLP), and so on. Among the various technologies, FO-WLP get significant attention with its high-degree heterogeneous integration capability, small form factor, and total reduced system cost. FO-WLPs cover wide range of applications, e.g., FPGA, GPU, networking, smartphone / tablet Application Processor (AP), Base Band (BB) module, RF / WiFi module, Power Amplifier (PA) module, etc. There are two categories of FO-WLP, one is characterized with molding encapsulant plus wafer-like process; the other one is characterized with PCB-like (or substrate-like) process. In order to distinguish the two categories, the later one is called Panel FO-WLP, while the former one is still called FO-WLP. According to the nature of wafer-like processed FO-WLP, it possesses fine-line-fine-space, typically 1um ~ 5um, and small via capability, which implies the package could accommodate more I/Os, better electrical performance, and thus high-end to mid-range application. Nevertheless Panel FO-WLP uses substrate-like process, it cannot provide too fine-line trace, typically the line width is wider than 10um, but with lower cost. Thus, its application is limited to mid-range to low-end devices. For FO-WLP, several companies have its own intellectual proprietary (IP), such as Infineon's eWLB (embedded Wafer Level Ball Grid Array), Freescale's RCP (Redistributed Chip Package), and TSMC's InFO WLP (Integrated Fan-Out WLP). For Panel FO-WLP, the same, each company has its own IP: such as Imbera's 1MB (Integrated Module Board), AT&S's ECP (Embedded Components Packaging), ASE's a-EASI (advanced - Embedded Assembly Solution Integration), and J-Devices' WFOP (Wide Strip Panel Fan-out Package). This paper will review and compare the major players' package construction, their process uniqueness, and discuss the potential extension and application of the FO-WLPs.