A New Wafer Level Packaging Approach: Encapsulation, Metallization and Laser Structuring for Advanced System in Package Manufacturing

Abstract

One of the general trends in microelectronics packaging is the constant miniaturization of devices. This has led to the development of maximum miniaturization of components on Si level, i.e., CSPs and Flip Chips. To further integrate more functionality into devices, and to further increase the degree of miniaturization, packaging development focus is switching from single chip packaging to the realization of systems in package, SiPs. Two main approaches do exist to realize this goal: one is to integrate all components into one dedicated package, yielding maximum miniaturization for a special application, but little flexibility as far as system design is concerned. The other is to create modular stackable components that can be assembled into a functional system. This integrates both flexibility in system design by exchangeable components and increased reliability potential, as single components can be tested separately. This last approach was considered a promising choice for the generation of SiPs. Within this paper a packaging process is introduced that allows the wafer level manufacturing of stackable, encapsulated devices. Using a transfer molded epoxy demonstrator, a proof-of-concept is performed showing the feasibility of the stackable package approach. This is achieved by combining wafer level encapsulation and molded interconnect device technology. An electroless process for metallization and laser techniques for structuring the metallization layer have been applied to generate structures for reliable interconnects capable for the use of lead-free solders. Summarized, this paper presents the process development and feasibility analysis of wafer level packaging technologies for modular SiP solutions based on a duromer MID approach.