Packaging Technologies For High Frequency Applications Using Polymer Materials

Inhalt:
Technological advancement requires increasing data rates in high user-density environments as well as very high bandwidth for wireless connections in general. The need for more bandwidth is closely associated with an increase of operating frequency for wireless links. Limited available bandwidth in lower frequency bands due to existing wireless applications and greater available bandwidth per channel at these higher frequencies are key factors for the push to higher operating frequency requirements. While solutions exist to satisfy these requirements from a standpoint of performance driven engineering, there is still a great need to satisfy such requirements using cost effective technologies. Traditional approaches to RF engineering at frequencies in the mm wave spectrum are not ideally suited for applications requiring low-cost and high miniaturization. These requirements will play a key role in the creation of viable products based on mm wave communication technologies. Using established technologies like laser direct structuring (LDS) and film-assisted transfer molding (FAM) enable packaging technologies capable of being used to 50 GHz and beyond. Technological advantages of these technologies include dimensional stability, low tolerances and availability of materials with good dielectric properties. FAM is used to present a customizable packaging concept, which enables the user to have freedom of design for RF ports while retaining full compatibility to existing packaging concepts and SMD processing lines with excellent thermal performance. Using an air cavity for the die enables to avoid losses occurring directly over the active surface of monolithic microwave integrated circuits (MMIC). LDS processing of injection molded polymer parts is used to present a concept for an antenna array for spatial beamforming in a half-sphere (360degx180deg) using a total of 64 channels. PEEK as thermoplastic material is selected with regard to its suitable dielectric properties. Key challenges of integrating beamforming ICs close to the antennas are identified and addressed. Embedding of dies into LDS compatible thermoset material is demonstrated and possibilites for future applications in high frequency components are discussed. Challenges for successful processing are identified and requirements for dies to be successfully embedded are discussed.