Preparation of PEDOT:PSS and Its Effect on Conductivity of Silver/Graphite Composite Conductive Adhesives
Date Issued
2012
Date
2012
Author(s)
Su, Chun-Ming
Abstract
This thesis presents the study of the Electrically Conductive Adhesives (ECAs) which includes preparation and analysis, and is presented in three parts. First part presents the synthesis of Poly(3,4-ethylenedioxythiophene):Poly- (StyreneSulfonate) (PEDOT:PSS). The second part illustrates the preparation of Silver-plated graphite conductive particles. In the last part, these two conductive materials are combined into ECAs for optimizing the conductivity with less Silver filling ratio.
TGA and conductivity measurements show that Nitrogen-bubbling and dialysis help the polymerization and purification of PEDOT:PSS, thus increasing the conductivity. Adding DMSO transforms the morphology of PEDOT:PSS, which have huge influence on conductivity. Increasing the weight ratio of PEDOT in PEDOT:PSS significantly enhances conductivity, but the solution will become less homogeneous. In this study, the highest conductivity of PEDOT:PSS film is 314.55 S/cm, which is reached as PEDOT:PSS weight ratio is 1:1.5 and with 7.5wt% DMSO.
In the study of conductive particles’ preparation, SEM images, EDX and XRD analysis show that sample with sensitization and activation has more silver exposure. ICP analysis evidences that sensitization and activation effectively raises the weight ratio of silver adsorbed, up to 40.1wt%. Sample is further investigated by Particle Size Analyzer and SEM to ensure the suitable size and morphology for conductive particles in ECAs.
In the study of ECAs, higher curing temperature and lower pressure guarantee better conductivity. Adding PEDOT:PSS does enhance the conductivity, but it is not so effective at high filling ratio. Silver nano-particles without butanethiol as dispersant will dramatically lower the conductivity. After surface modification with butanethiol, Silver nano-particle turns to be beneficial for conductivity at low weight ratio.
The highest conductivity measured in this study is 9.66 x 103 (S/cm). It’s obtained when total filling ratio is 70 wt% in which 20 wt% of conductive particles are butanethiol-treated silver nano-particles.
Subjects
PEDOT:PSS
ECA
Electroless Plating
Ag/C Composite.
Type
thesis
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