RF Packaging Research Articles

Robust Aluminium Nitride Package Technology for Multichip Modules

The advent of novel advanced packaging technologies such as multilayer thin‐film interconnect, combined with continuous improvements in IC clock speed and circuit performance, has placed extreme demands on electronics packaging and package materials. Aluminium nitride (AIN) ceramic offers significant opportunities and advantages for package design, particularly where the effective thermal management and overall reliability of large devices are a high priority. AIN has already been successfully employed at the substrate level for the enhanced thermal relief of power devices. Examples of these applications include heat sinks and device mounts for thyristor modules, power transistors, solid state relays, power SCRs, switching modules, LEDs and various RF package configurations. Both bare and metallised AIN substrates are beginning to find application as a substitute for beryllia (BeO) in mass market and high reliability automotive electronics applications. Successfully implementing AIN in a high level electronics packaging application requires a systems approach in which the intrinsic properties of AIN are considered as ‘first principles’ in shaping the package design process. The unique physicochemical and mechanical properties of AIN require the development of specialised metallisation and co‐firing processes to fabricate the advanced components necessary for hermetic packaging of complex devices and multichip modules. This paper presents a practical and mass manufacturable AIN‐based package tailored to these high level applications. The package design is unique in that it provides for the total separation of the electrical‐signal conduction from the mechanical support/mounting functions of the package. Such a separation of the functions improves both the package durability and reliability relative to currently available electronics packages of conventional designs.

HDS/NA-6: an analog simulcast high definition television system

A high-definition system for North America (HDS/NA) embracing the simulcast mode of transmission for amplitude-modulated terrestrial and cable environments is described. The AM RF packaging techniques and the pertinent concerns for future tailoring of the system format for taboo channel utilization for broadcast-compatible terrestrial HDTV delivery in 6 MHz are highlighted. Without the constraint of direct NTSC compatibility with this system, carriers may be suppressed and standard NTSC sync headroom may be eliminated. Due to time expansion of all video components, there is a built-in advantage in multipath/echo performance, particularly beneficial for the cable short-echo scenario. The system is naturally expandable to permit an increase in resolution in the presence of additional channel bandwidth. This simulcast format is linked to a linear analog subband subsampling scheme used as a cornerstone for all HDS/NA analog transmission systems, including satellite (FSS and DBS) and augmentation terrestrial and cable formats. The generic HDS/NA subsampling scheme and the packaging of the components for a 6-MHz AM environment are described.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>