the effect of surface functionalization of graphene … effect of surface functionalization of...

The Effect of Surface Functionalization of Graphene on the Electrical Conductivity

of Epoxy-based Conductive Nanocomposites

by

Behnam Meschi Amoli, PhD

Institute for Polymer Research, Waterloo Institute of Nanotechnology, Department of Chemical Engineering, University of Waterloo, Waterloo, ON, Canada

May 6, 20151

OUTLINE

2

Introduction

Hybrid Filler System using Graphene

Ag NP-decoration

SDS-stabilization

Concluding remarks

3

Introduction

INTRODUCTION

4

Interconnection Materials for Electronic Packaging Technologies

Electrically Conductive Pathways Between Different Elements

Li et al., Science, 2005

Lead-based solders

Lead-free materials

Electrical Conductive Adhesives (ECAs)

INTRODUCTION

5

Polymeric Matrix Conductive Fillers

Epoxy Micron-sized silver flakes

6

INTRODUCTION

Commercial ECAs

Environmental friendliness

Mild processing conditions

Low stress on substrate

Fine pitch interconnect capability

Advantages Disadvantages

Poor mechanical strength

Conductivity fatigue in harsh

conditions (reliability)

Low electrical conductivity

Addition of more silver flakes

Decreases the adhesive strength

Increases the final cost

Not effective after percolation threshold

7

Adding nano-sized fillers to the conventional formulation of ECAs to generate hybrid (micro-nano) filler system

INTRODUCTION

Objective:

Improving the quality of interactions between conductive fillers to

facilitate the electron transportation

8

NP

Adding nano-sized fillers to the conventional formulation of ECAs to generate hybrid (micro-nano) filler system

INTRODUCTION

Spherical Ag NPsHigh aspect-ratio Ag NBsGraphene

9

Hybrid Filler System

Using

Graphene

10

GRAPHENE

Flat monolayer of carbon atoms

Densely packed into a 2D honeycomb lattice structure

The thinnest and stiffest 2D nanostructure

Extremely high aspect-ratio and electrical conductivity

Surfactants (SDS)

Two functionalization approaches

Surface decoration with Ag NPs

Acid treatment

COOH

COOHCOOH

COOH

COOH

COOH

COOHCOOH

COOH

COOH

HOOC

COOH

COOH

COOH

COOH

OH

OH

OH

OHOH

OH

OH

OH

+

+

+

+

+

+

+

+ +

+

+

+

++

+

+ +

+

+

++

+

+

+

++

+

+

+

+

(1)

(4)(3)

(2)

Silv

er n

itrate

MPA+

NaBH4

S

O

OH

Ag NPs+

Ag nucleation sites

Ag ions

Covalent approachNon-covalent approach

11

Ag NP-DECORATED GRAPHENE

o Surface decoration of graphene with Ag NPs functionalized with MPA

Preparation of GO Initial nucleation

Formation and functionalization of NPs

B. Meschi Amoli et al., J. Mater. Sci: Mater Electron. 2015

12

AG NP-DECORATED GRAPHENE

B. Meschi Amoli et al., J. Mater. Sci: Mater Electron. 2015

The Average Size9.1 ± 3.1 nm

𝟒. 𝟔 × 𝟏𝟎−𝟓 𝜴. 𝒄𝒎

13

AG NP-DECORATED GRAPHENE

o Hybrid ECAs using the Ag NP-decorated graphene

B. Meschi Amoli et al., J. Mater. Sci: Mater Electron. 2015

Hybrid ECAs have1 wt% graphene

Bulk resistivity of lead-based solders ≈

2 × 𝟏𝟎−𝟓 𝜴. 𝒄𝒎

14

SDS-STABILIZED GRAPHENE

o The stabilization of graphene using SDS

B. Meschi Amoli et al., Carbon, accepted, 2015

Sonication

15

SDS-STABILIZED GRAPHENE

o Hybrid ECAs using the SDS-stabilized graphene

B. Meschi Amoli et al., Carbon, accepted, 2015

Small Gr≤ 1µm

Large Gr≤ 5µm

1. 𝟔 × 𝟏𝟎−𝟓 𝜴. 𝒄𝒎7 × 𝟏𝟎−𝟓 𝜴. 𝒄𝒎

Compared to 1.8 × 𝟏𝟎−𝟒 𝜴. 𝒄𝒎

16

Concluding remarks

o Both functionalization approaches improved the electrical conductivity of ECAs

o SDS-stabilization of graphene is more effective method for electrical conductivity improvement compared to Ag NP-decoration

o A relatively low electrical resistivity of 35 Ω.cm was achieved using only 10 wt% silver flakes and 1.5 wt% SDS-stabilized graphene

o A highly electrically conductive adhesive with the bulk resistivity less than that of lead-based solder was fabricated using 1.5 wt% SDS-stabilized graphene and 80 wt% silver flakes

17

• Meschi Amoli et al., J. Mater. Chem., 2012, 20048–20056.

• Gumfekar, Meschi Amoli et al., Poly. Sci. B: Poly. Phys., 2013, 1448–1455.

• Meschi Amoli et al., Macromol. Mater. Eng., 2014, 739–747.

• Meschi Amoli et al., J. Mater. Sci: Mater Electron., 2015, 590–600.

• Meschi Amoli et al., Carbon, 2015, accepted.

• Meschi Amoli et al., J. Mater. Sci: Mater Electron., 2015, accepted.

LIST OF PUBLICATIONS

18

AKNOWLEDGEMENTS

Supervisors

◦ Professor Boxin Zhao

◦ Professor Norman Zhou

19

THANK YOU!

20

Backup Slides

Curing Mechanism of Epoxy

21

22

INTRODUCTION

Electron conduction mechanism in an electrical network

23

MUA MPA

AgNO3 + HS(CH2)nCOOH

B. Meschi Amoli et al., J. mater. chem., 2012

Ag-MUA

Ag-MPA

24

Ag NP-DECORATED GRAPHENE

o Surface decoration of graphene with Ag NPs-functionalized with MPA

B. Meschi Amoli et al., J. Mater. Sci: Mater Electron. 2015, 590–600,

900 1400 1900 2400 2900 3400 3900

Ab

sorp

tio

n (

a.u

.)

Wavenumber (cm ¹ )

Gr-Ag NPs

Graphene

GrO

17041617

OH

1696

1228

1247 1587

25

Ag NP-DECORATED GRAPHENE

o Initial nucleation

B. Meschi Amoli et al., J. Mater. Sci: Mater Electron. 2015, 590–600,

26

Ag NP-DECORATED GRAPHENE

o UV-vis & XRD

B. Meschi Amoli et al., J. Mater. Sci: Mater Electron. 2015, 590–600,

27

AG NP-DECORATED GRAPHENE

o Thermal behaviour of the decorated graphene

B. Meschi Amoli et al., J. Mater. Sci: Mater Electron. 2015, 590–600,

145 °C

28

AG NP-DECORATED GRAPHENE

o Electrical Conductivity of Conductive fillers thin-films

B. Meschi Amoli et al., J. Mater. Sci: Mater Electron. 2015, 590–600,

Temperature Increase

29

SDS-STABILIZED GRAPHENE

o The stabilization of graphene using SDS

B. Meschi Amoli et al., Carbon, under revision, 2015

0.30 nm

0.38 nm

FTIR

XRD

Raman

30

SDS-stabilized Graphene

B. Meschi Amoli et al., Carbon, under revision, 2015

0.65

0.7

0.75

0.8

0.85

0.9

0.95

75 80 85 90 95 100 105 110 115 120 125 130 135 140

Re

v C

p (

J/g

)

Temperature (°C)

Cp Tg Analysis

Tg : 111.9 °C

103.95 °C

103.95 °C

Name

Description

Composition

Control 1

(Neat Epoxy)

Control 2

(Ethanol Diluted) HCA-SGN HCA-SGS

Ethanol ContentPHR 0 PHR 40.8 PHR 40.4 PHR 40.4 PHR

wt% 0 wt% 26.5 wt% 12.5 wt% 12.5 wt%

∆Htot J/g 452.7 380.5 132.7 148.3

∆Hnorm J/gmatrix 452.7 517.5 380.9 436.2

Tg °C 129.7 117.8 111.9 111.9

31

SDS-STABILIZED GRAPHENE

B. Meschi Amoli et al., Carbon, under revision, 2015

Name

Description

Composition

Control 1

(Neat Epoxy)

Control 2

(Ethanol Diluted) HCA-SGN HCA-SGS

Ethanol ContentPHR 0 PHR 40.8 PHR 40.4 PHR 40.4 PHR

wt% 0 wt% 26.5 wt% 12.5 wt% 12.5 wt%

∆Htot J/g 452.7 380.5 132.7 148.3

∆Hnorm J/gmatrix 452.7 517.5 380.9 436.2

Tg °C 129.7 117.8 111.9 111.9

32

SDS-stabilized Graphene

B. Meschi Amoli et al., Carbon, under revision, 2015

33

SDS-stabilized Graphene

o Thermal Stability

B. Meschi Amoli et al., Carbon, under revision, 2015

34

SDS-STABILIZED GRAPHENE

o Hybrid ECAs using the SDS-stabilized graphene

B. Meschi Amoli et al., Carbon, under revision, 2015

Small SDS-Gr

Large SDS-Gr Large non modified Gr

No Gr

35

5.50E-04

7.00E-53.50E-5

1.80E-04

3.00E-05 1.60E-05

0.00E+00

1.00E-04

2.00E-04

3.00E-04

4.00E-04

5.00E-04

6.00E-04

7.00E-04

Res

isti

vity

(Ω

∙cm

)

Conventional ECA Non-modified small Gr non-modified large Gr

AG NP decorated Gr SDS-Stabilized Gr (small) SDS Stabilized Gr (large)