John Wing-Keung Lau

Design of metallizations and components for aluminum nitride packages for VLSIC

A program to produce large cofired aluminum nitride (AIN) packages for support of silicon-based high-density multichip modules (MCMs) is discussed. Perimeter leaded packages measuring over 4 in in length and having over 600 leads on 0.025-in centers have been developed. The size and fine lead pitch require tight dimensional control, including 0.1% on both the flatness and the placement of cofired lead pads. These dimensional requirements, as well as the hermeticity and thermal-mechanical reliability requirements for military use, have been met through a combination of engineering/design solutions and the implementations of new material systems and processes. >

Metallization Behavior in Aluminum Nitride Electronic Packages

Characteristics such as CTE close to that of silicon, high thermal conductivity, and good dielectric properties make aluminum nitride (AIN) an excellent dielectric for packaging silicon-based high density multichip interconnects. However, there remains many aspects of its behavior that have not been characterized. One such example is the behavior of the various metallizations used within a package. As with A1 2 O 3 , these metallizations must contribute toward a hermetic seal separating the die from the environment. However, the chemical behavior of the metallization systems used for A1 2 O 3 may not be compatible with non-oxide ceramics such as AIN. Consequently, these chemical interactions are investigated in view of the requirements for each application within electronic packages. Hermeticity testing results are also included in the discussion.

The Effect of Process on Performance and Reliability in a One Step Silver-Glass Die Attach Adhesive

Silver-glass die attach adhesives provide a cost effective means of producing high reliability parts which can withstand the environmental testing required of electronic components. One step processing of these adhesives provides the additional advantages of increased throughput and processing flexibility compared to eutectically bonded assemblies. This paper describes the performance of a one step silver-glass die attach adhesive processed under various time and temperature conditions. The effect of peak firing temperature and dwell time on the ultimate tensile strength of the adhesive will be discussed. Tensile data from parts subjected to thermal shock, thermal cycle and high temperature aging will be presented as an indication of the materials long term reliability.