Stress Analysis of the Vertical Interconnect for Three-Dimensional Packaging

Abstract

Three-dimensional (3-D) packaging is critical to developing supercompact electronic systems. Its representative configuration consists of several circuit packs connected by pressure sensitive vertical interconnects. The sensitive characteristics of the interconnects demand a uniform distribution of acceptable pressure levels. Solutions to analyze and generate such a distribution are derived for a multilayer configuration under an isothermal assembly condition. They are proved to be insensitive to the unknown interface conditions, and applied to study 1) a five-layer model representing a surface mount assembly and a basic building block for 3-D packaging and 2) multilayer models representing a complete system. A uniform pressure distribution may result from 1) thick metal loading plates with a high modulus, 2) thick polymer interconnects with a low modulus, 3) short loading distances, and 4) addition of more layers. The last factor informs designers a good surface mount fixture design can be readily applied to 3-D packaged systems.