SUMMARY

Flexible substrates with printed electronics are being increasingly sought for the widespread and cost-effective use of flexible electronics. With printed ink on flexible substrates, several items need to be examined: synthesis of ink, deposition of ink, curing of ink, line and spacing of ink, adhesion of ink, fracture strength of ink, electrical characteristics of ink, etc. Among these items, adhesion of ink to the substrate plays an important role in the overall reliability of printed ink on flexible substrate. When ink is printed on flexible substrates, assembly of surface mount devices on such printed pads is a challenge, especially if one desires to use fully additive process. For such assembly techniques various process parameters need to be identified and the strength of the joints needs to be assessed. Furthermore, detailed understanding of stress/strain profile in the printed elements as well as in the assembled devices through simulations and appropriate experimental techniques will provide insight into designing against potential failures.
The objectives of this research are three-fold: 1) To determine the adhesion and interfacial characteristics of printed conductors through an innovative experimental technique that can be used to wide range of substrate and ink materials. By exploring a number of interfacial geometries, this work aims to provide a comprehensive understanding of interfacial delamination of printed ink on flexible substrates. 2) To develop and assess a fully-additive printing process for assembling surface mount devices on flexible substrates. Using different process parameters, this work will examine the joint integrity of such fully-additive printing process for assembly. 3) To develop a numerical modeling scheme to extract interfacial parameters for printed ink as well as fracture parameters for device-to-substrate joints. This work will employ such models to develop design and process guidelines for a fully-additive printed assembly technique.