Design: Electrical, Mechanical, Thermal

Design Research Overview

Georgia Tech PRC proposes new and innovative low-cost 2.5D and 3D glass architectures with unparalleled interconnection densities, the figure below shows how 3D glass interposer architectures meet bandwidth goals by providing ultra-small pitch interconnections between logic and memory die(s) at 20μm pitch in the short-term and 5μm pitch in the long-term.

3D glass interposer architectures to enable ultra-high die-to-die bandwidth.

Electrical Design

Electrical Design involves signal and power integrity research in 2D, 2.5D and 3D Package architectures. 

Three Package Architectures at Georgia Tech PRC.

The goal of 2.5D Interposer is to demonstrate glass interposers that are as large as 40-60 mm size at 20 µm pitch to demonstrate the intrinsic bandwidth capabilities of glass interposer technology.

The key challenges that are being addressed in this program include:

a.Reducing resonance in the power delivery network

b.Decreasing insertion loss for signal lines with a via transition in the presence of a power/ground plane

c. Improving crosstalk between ultra-fine line and space interconnects.

the Goal of 3D Interposer BGAs are many for digital, R , Power and other applications with double-side mounting of components interconnected by ultra-short through-via interconnections. 

Mechanical Design

This research focuses on modeling, design and experimental characterization to quantify the warpage, reliability and glass cracking as a result of dicing. This will include a design of experiments to study parameters such as stack thickness, copper distribution, dicing method (e.g. mechanical and laser) and interposer core mechanical properties. To validate the models, warpage data as well as strain measurements will be used. Subsequently, the information gained from the experimental characterization will be used to develop finite element models to design the package and interconnection structure for via and interconnection reliability, and also predict the occurrence of other failures in glass.

Thermal Design

The overall strategy is to develop thermal solutions for 2.5D and 3D Glass interposers to meet both portable and high performance needs in spite of low thermal conductivity of glass. The R&D focus is to model, design and characterize the thermal response of glass substrates with copper through vias and Redistribution Layers (RDLs), and develop novel cooling schemes and structures to meet the thermal requirements for mobile devices. The overall target of this research is to design and develop solutions to address the thermal issues in glass interposer-based 3D technology. The first year of the program will focus on developing computational models to investigate the effect of copper structures including through vias and copper traces in RDLs to qualify the thermal enhancement of in-plane and out-of-plane thermal conductivity of glass structures. The second year R&D focuses on design and fabrication if novel cooling structures to remove heat from the glass interposer effectively and also validate the models and designs.

For more information about Design Research at GT PRC, please contact, Dr. Raj Pulugurtha, at raj.pulugurtha@prc.gatech.edu​.