Fan-out system-in-board technology: Enabling RF and processor module and system-level integration

By Serena Brischetto

SEMI met with Martin Schrems, director of Strategy and Business Development at AT&S AG, to discuss Fan-Out technology trends ahead of SEMI 3D & Systems Summitin Dresden, Germany.

SEMI: What are the AT&S AG mission and vision and your role within the company?

Schrems: AT&S AG is evolving from a pure PCB manufacturer towards an interconnect solution provider. We can clearly see a continued trend towards miniaturization and modularization by (3D) integration of components such as integrated circuits and passives. Module sizes tend to increase by integrating more functions and system-level requirements. As a PCB maker, we have served such system-level requirements for a long time. Further integration offers opportunities to embed components in PCBs or substrates, offer layout and simulation services, as well as provide assembly and test services depending on specific customer requirements. As director of Strategy and Business Development, I work with my colleagues in AT&S, customers, and partners across the industry towards understanding and leveraging this major transformation in the electronics industry.

SEMI: What project are you currently working on that you think will make a difference in 2019?

Schrems: There are number of very exciting projects, many of them already involving AT&S contributions to module integration. Some of these projects involve key customers directly. We see exciting opportunities for integration of larger multi-function modules by combining PCB, substrate, and embedding core competences.

SEMI: The focus of your presentation at the 3D & Systems Summit will be on “Fan-Out System-in-Board technology enabling module and system-level integration.” What do you see as the key trend in this area?

Schrems: Fan-Out technologies are used to distribute I/O pad connections of nanoCMOS ICs over a larger area. This relaxes bump pitch and feature size requirements for subsequent system-level PCB interconnects. In some cases, Fan-Out layers already provide a substitute to currently used Flip-Chip substrates. Well-known examples are Fan-Out packages for application processors for smartphones. There is definitely a trend in the market towards Fan-Out for high-end processor applications. Advantages of such Fan-Out packages are shorter electrical connections and a reduced thickness.

However, one weakness of current Fan-Out packages is that only a limited number of components can be integrated due to mechanical stability challenges – a barrier to further component integration in larger modules. Currently, the only way to integrate more components is to use laminate-based PCBs and substrates with conventional Surface Mount Technology. Recent proposals like our “Fan-Out System-in-Board” (FO-SiB^TM) technology are expected to provide an alternative Fan-Out packaging option at the board-level in the future.

SEMI: Please elaborate.

Schrems: Fan-Out capability and integration of more components – typically up to the 100 and more needed for electronics integration at system level – can be achieved simultaneously by combining technologies from the PCB and the packaging world. PCB laminates such as glass particles and organic materials provide mechanical stability for large boards. The recent introduction of substrate-like PCBs (mSAP) has already paved the way to cover applications that were reserved for substrates and classical packaging in the past.

With FO-SiB^TM technology, we have taken it a step further and offer the option to integrate SAP substrate layers onto the PCB with lines/spaces below 10µm. FO-SiB^TM makes it possible to directly contact nanoCMOS chips on PCBs without any intermediate substrates. Further adding Cu pillar technology at panel level will enable Fan-Out structures even for surface-mounted components, making recent R&D on panel-level Cu pillar technology very important. Through joint R&D, we can drive progress in the industry to further enable cost-effective heterogeneous 3D integration.

SEMI: What are your expectations for the 3D & Systems Summit in Dresden, and why do you recommend your members and other industry leaders to attend?

Schrems: The 3D summit is the high-level conference where key electronics industry players discuss major heterogeneous integration trends. Therefore, we very much appreciate the opportunities to exchange ideas across the supply chain including users, developers of integrated electronics hardware and tool manufacturers.

Serena Brischetto is a marketing and communications manager at SEMI Europe.