Duixian Liu - Antenna-in-Package Technology and Applications

AiP technology balances performance, size, and cost, hence it has been widely adopted by chipmakers for 60‐GHz radios, augmented/virtual reality gadgets, and gesture radars. It has also found applications in 79‐GHz automotive radars, 94‐GHz phased arrays for imaging and data communications, 122‐GHz, 145‐GHz, and 160‐GHz sensors, as well as 300‐GHz wireless links. Recently, AiP technology has been under further development for millimeter‐wave (mmWave) fifth‐generation (5G) technology. Scalable large AiPs and multiple small AiPs have been successfully demonstrated in base stations, mobile phones, and networked cars at 28 GHz. We therefore believe that AiP technology will cause fundamental changes in the design of antennas for mobile communications for 5G and beyond operating in mmWave bands.

The development of mmWave AiP technology is particularly challenging because of the associated complexity in design, fabrication, integration, and testing. This book aims to face these challenges through disseminating relevant knowledge, addressing practical engineering issues, meeting immediate demands for existing systems, and providing the antenna and packaging solutions for the latest and emerging applications.

This book contains 11 chapters. The first five chapters lay some foundation and introduce fundamental knowledge. After the introductory chapter about how AiP technology has been developed as we know it today, several types of antennas are discussed in Chapter 2. An attempt is made to summarize the basic antennas and those antennas specifically developed for AiP technology. Emphasis is given to microstrip patch antennas and arrays, grid array antennas, Yagi–Uda antennas, and magneto‐electric dipole antennas because of their dominance in AiP technology. Performance improvement techniques of antennas for AiP technology are also described. Chapter 3describes today's mainstream packaging solutions with either wire‐bond or flip‐chip interconnects, wafer‐level package, and fan‐out wafer‐level package. Chapter 4focuses on the electrical, mechanical, and thermal co‐design for AiP modules. More importantly, the thermal management considerations for next‐generation heterogeneous integrated systems are reviewed in order to address the growing need for cooling the high‐power devices of future radio systems. Chapter 5presents the design and optimization of an anechoic test facility for testing mmWave integrated antennas. This facility can be used for both probe‐based and connector‐based measurements.

The next five chapters are related to the design, fabrication, and characterization of AiPs in different materials and processes for mmWave applications. Chapter 6discusses low‐temperature co‐fired ceramic (LTCC)‐based AiP. LTCC has unique properties for packaging mmWave circuits since it can provide a durable hermetic package with antennas, cavities, and integrated passive components. Chapter 7illustrates how industrial organic packaging substrate technology used for classical integrated circuit (IC) packaging can support the development of innovative, efficient, and cost‐effective mmWave AiPs from 60 GHz up to 300 GHz. Chapter 8focuses on embedded wafer‐level ball grid array (eWLB)‐based AiP. Unlike LTCC or high‐density integr (HDI), eWLB eliminates the need for a laminate substrate and replaces it with copper redistribution layers. Polymers are used for the electrical isolation between the metal layers. The metal routings are deposited by a combination of sputtering and electroplating with a thin film process. eWLB has historically been developed for mmWave automotive radar systems and therefore has naturally been used for mass production of mmWave AiPs. Chapter 9presents surface laminar circuit (SLC)‐based AiP. Compared to LTCC, HDI, and eWLB, SLC is more suitable for fabrication of very large or dense AiPs. The chapter describes SLC materials and design guidelines, and then addresses the design challenges and solutions for 8 × 8 dual‐polarized phased arrays at 94 GHz for imaging and 28 GHz for 5G base station applications, respectively. Chapter 10introduces different additive manufacturing technologies, methods to characterize three‐dimensional (3D)‐printed materials, a hybrid printing process by integrating 3D and inkjet printing, and a broadband 5G AiP realized with the hybrid process.

The last chapter turns to 3D AiP for power transfer, sensor nodes, and Internet of Things applications. This package has a cubic geometry with radiating antennas on its surrounding faces. The chapter highlights small antenna design and miniaturizing techniques as well as multi‐mode capability as a way to achieve wideband antennas.

This book is the result of the joint efforts of the 21 authors in eight different institutions in Asia, Europe, and the United States. A book on an emerging topic like AiP technology would not have been possible without such collaborations. We thank all authors for their creative contributions and careful preparation of manuscripts. We are also pleased to acknowledge the professional cooperation of the publishers.

Duixian Liu IBM Thomas J. Watson Research Center Yorktown Heights, NY, USA

Yueping Zhang School of Electrical and Electronic Engineering Nanyang Technological University Singapore