This study is to observe the exact behavior of anisotropic conductive adhesion (ACF) package under humid environments by obtaining the moisture-induced properties such as diffusion coefficient (the rate of moisture movement into the materials), saturated moisture content (the maximum absorbed quantity), and swelling coefficient (length change due to the chemical interaction). So the experiments were performed to get the moisture-induced properties of ACF and FR4 using newly developed method at various temperature and relative humidity conditions. Experimental results showed that the diffusion coefficient of ACF and FR4 follows Arrhenius’ equation very well, and the saturated moisture content of them follows Henry’s law, which means linear relationship between saturated moisture content and relative humidity, but the saturated moisture content of ACF is influenced by temperature as well as relative humidity. And the swelling coefficient of ACF and FR4 increases with temperature. Especially in the case of ACF, it shows the dramatic degradation due to $Tg$ (glass transition temperature) at nearby $85°C$. Finally, as using these experimental results, the behavior of the ACF package under humid environment is predicted through finite element simulation. When wetness defined by moisture content over saturated moisture content changes from 0 to 0.9, the center of the ACF package is subject to compression and the edge of the ACF package is subject to tension in the case of transient state. After all, because the edge of the ACF package is very weak due to bending moment, the failure is easy to occur under humid environment.

1.
Chan
,
Y. C.
,
Hung
,
K. C.
,
Tang
,
C. W.
, and
Wu
,
C. M. L.
, 2000, “
Degradation Mechanism of Anisotropic Conductive Adhesive Joints for Flip Chip on Flex Application
,”
Proceedings of the Fourth International Conference on Adhesive Joining and Coating Technology in Electronics Manufacturing
, pp.
141
146
.
2.
Yim
,
M. J.
,
Paik
,
K. W.
,
Kim
,
Y. K.
, and
Hwang
,
H. N.
, 1997, “
A Study on the Electrical Conduction Mechanism of Anisotropically Conductive Film for LCD Packaging Application
,”
, Vol.
19–1
,
EEP
,
New York
, pp.
65
72
.
3.
Fu
,
Y.
,
Wang
,
Y.
,
Wang
,
X.
,
Liu
,
J.
,
Lai
,
Z.
,
Chen
,
G.
, and
Willander
,
M.
, 2000, “
Experimental Characterization and Theoretical Characterization of Electrical Contact in Anisotropically Conductive Adhesives
,”
1521-3323,
23
(
1
), pp.
15
21
.
4.
Lai
,
Z.
, and
Liu
,
J.
, 1990, “
Anisotropically Conductive Adhesive Flip-Chip Bonding on Rigid and Flexible Printed Circuit Substrates
,”
,
19
(
3
), pp.
644
660
.
5.
Tanaka
,
N.
,
Kitano
,
M.
,
Kumazawa
,
T.
, and
Nishimura
,
A.
, 1997, “
Evaluation of Interface Delamination in IC Packages by Considering Swelling of the Molding Compound Due to Moisture Absorption
,”
47th ECTC
, pp.
84
90
.
6.
Wong
,
E. H.
,
Chan
,
K. C.
,
Tee
,
T. Y.
, and
Rajoo
,
R.
, 2002, “
Comprehensive Treatment of Moisture Induced-Recent Advances
,”
IEEE Trans. Electron. Packag. Manuf.
1521-334X,
25
(
3
), pp.
223
230
.
7.
Xu
,
T.
, and
Farris
,
R. J.
, 2006, “
Stresses Associated With Diffusion in Polyimide and Polyacrylic Films
,”
J. Appl. Polym. Sci.
0021-8995,
99
(
5
), pp.
2661
2670
.
8.
Wong
,
E. H.
,
Rajoo
,
R.
,
Koh
,
S. W.
, and
Lim
,
T. B.
, 2002, “
The Mechanics and Impact of Hygroscopic Swelling of Polymeric Materials in Electronic Packaging
,”
ASME J. Electron. Packag.
1043-7398,
124
(
2
), pp.
122
126
.
9.
Springer
,
G. S.
, 1981,
Environment Effect on Composite Materials
,
Technomic
,
Lancaster
.
10.
Park
,
C. -O.
, 2003,
The Book: Diffusion in Solids
,
BRAINKOREA
,
Seoul, South Korea
.
11.
Vanderhart
,
D. L.
,
Schen
,
M. A.
, and
Davis
,
G. T.
, 1999, “
Partitioning of Water Between Voids and the Polymer Matrix in a Polymer Compound by Proton NMR: The Role of Larger Voids in the Phenomena of Popcorning and Delamination
,”
Int. J. Microcircuits Electron. Packag.
1063-1674,
22
(
4
), pp.
423
441
.
12.
Toprak
,
C.
,
Agar
,
J. N.
, and
Falk
,
M.
, 1979, “
State of Water in Cellulose Acetate Membranes
,”
J. Chem. Soc., Faraday Trans. 1
0300-9599,
75
, pp.
803
815
.
13.
,
M. J.
, 1980, “
Thermal Expansion and Swelling of Cured Epoxy Resin Used in Graphite/Epoxy Composite Materials
,”
J. Mater. Sci.
0022-2461,
15
(
7
), pp.
1736
1745
.
14.
Post
,
D.
,
Han
,
B.
, and
Ifju
,
P.
, 1994,
High Sensitivity Moiré
,
Springer-Verlag
,
New York
.
15.
Yin
,
C.
,
Lu
,
H.
,
Bailey
,
C.
, and
Chan
,
Y. -C.
, 2005, “
Moisture Effects on the Reliability of Anisotropic Conductive Film Interconnection for Flip Chip on Flex A Applications
,”
IPACK2005, Proceeding of the ASME/Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS and Electronic Systems
, pp.
1293
1298
.