The sandwich structure Cu/Sn/Cu solder joints with different thicknesses of the solder layers (δ) are fabricated using a reflow solder method. The microstructure and composition of the solder joints are observed and analyzed by scanning electron microscopy (SEM). Results show that the thickness of intermetallic compound (IMC) and Cu concentration in the solder layers increase with the decrease of δ after reflow. During thermal aging, the thickness of IMC does not increase according to the parabolic rule with the increase of aging time; the solder joint thickness affects markedly the growth rate of IMC layer. At the beginning of thermal aging, the growth rate of IMC in the thinner solder joints (δ ≤ 25 μm) is higher than that in the thicker ones (δ ≥ 30 μm). The growth rate of IMC (δ ≤ 25 μm) decreases in the thinner solder joints, while increases in the thicker solder joints (δ ≥ 40 μm) and is nearly invariable when the δ equals to 30 μm with aging time extending. The growth rate of IMC increases first and then decreases after reaching a peak value with the increase of δ in the later stage during aging. The main control element for IMC growth transfers from Cu to Sn with the reduction of size.

References

References
1.
Lu
,
H.
,
Takagi
,
Y.
,
Suzuki
,
Y.
,
Sawyer
,
B.
,
Taylor
,
R.
,
Sundaram
,
V.
, and
Tummala
,
R.
,
2014
, “
Demonstration of 3-5μm RDL Line Lithography on Panel-Based Glass Interposers
,”
2014 IEEE 64th Electronic Components and Technology Conference
(
ECTC
), Orlando, FL, May 27–30, pp.
1416
1420
.
2.
Ouyang
,
F. Y.
, and
Jhu
,
W. C.
,
2013
, “
Comparison of Thermomigration Behaviors Between Pb-Free Flip Chip Solder Joints and Microbumps in Three Dimensional Integrated Circuits: Bump Height Effect
,”
J. Appl. Phys.
,
113
, p.
043711
.
3.
Wu
,
F.
,
Wang
,
B.
,
Du
,
B.
,
An
,
B.
, and
Wu
,
Y.
,
2009
, “
Effect of Stand-Off Height on Microstructure and Tensile Strength of the Cu/Sn9Zn/Cu Solder Joint
,”
J. Electron. Mater.
,
38
(
6
), pp.
860
865
.
4.
Wang
,
B.
,
Wu
,
F.
,
Wu
,
Y.
,
Liu
,
H.
,
Zhou
,
L.
, and
Fang
,
Y.
,
2010
, “
Effect of Stand-Off Height on the Microstructure and Mechanical Behaviour of Solder Joints
,”
Soldering Surf. Mount Technol.
,
22
(
1
), pp.
11
18
.
5.
Tian
,
Y.
,
Hang
,
C.
,
Wang
,
C.
,
Yang
,
S.
, and
Lin
,
P.
,
2011
, “
Effects of Bump Size on Deformation and Fracture Behavior of Sn3.0Ag0.5Cu/Cu Solder Joints During Shear Testing
,”
Mater. Sci. Eng. A
,
529
, pp.
468
478
.
6.
Yang
,
M.
,
Li
,
M.
,
Wang
,
L.
,
Fu
,
Y.
,
Kim
,
J.
, and
Weng
,
L.
,
2011
, “
Cu6Sn5 Morphology Transition and Its Effect on Mechanical Properties of Eutectic Sn-Ag Solder Joints
,”
J. Electron. Mater.
,
40
(
2
), pp.
176
188
.
7.
Che
,
F.
, and
Pang
,
J. H.
,
2012
, “
Characterization of IMC Layer and Its Effect on Thermomechanical Fatigue Life of Sn-3.8Ag-0.7Cu Solder Joints
,”
J. Alloys Compd.
,
541
, pp.
6
13
.
8.
Li
,
X.
,
Xia
,
J.
,
Zhou
,
M.
,
Ma
,
X.
, and
Zhang
,
X. P.
,
2011
, “
Solder Volume Effects on the Microstructure Evolution and Shear Fracture Behavior of Ball Grid Array Structure Sn-3.0Ag-0.5Cu Solder Interconnects
,”
J. Electron. Mater.
,
40
(
12
), pp.
2425
2435
.
9.
Yang
,
L.
,
Zhang
,
Q.
, and
Zhang
,
Z. F.
,
2012
, “
Effects of Solder Dimension on the Interfacial Shear Strength and Fracture Behaviors of Cu/Sn-3Cu/Cu Joints
,”
Scr. Mater.
,
67
(
7–8
), pp.
637
640
.
10.
Anderson
,
I. E.
,
Boesenberg
,
A.
,
Harringa
,
J.
,
Riegner
,
D.
,
Steinmetz
,
A.
, and
Hillman
,
D.
,
2012
, “
Comparison of Extensive Thermal Cycling Effects on Microstructure Development in Micro-Alloyed Sn-Ag-Cu Solder Joints
,”
J. Electron. Mater.
,
41
(
2
), pp.
390
397
.
11.
Tian
,
Y.
,
Chow
,
J.
,
Liu
,
X.
, and
Sitaraman
,
S. K.
,
2015
, “
The Size Effect on Intermetallic Microstructure Evolution of Critical Solder Joints for Flip Chip Assemblies
,”
Soldering Surf. Mount Technol.
,
27
(
4
), pp.
178
184
.
12.
Li
,
X.
,
Sun
,
F.
,
Liu
,
Y.
,
Zhang
,
H.
, and
Xin
,
T.
,
2014
, “
Geometrical Size Effect on the Interface Diffusion of Micro Solder Joint in Electro-Thermal Coupling Aging
,”
J. Mater. Sci.: Mater. Electron.
,
25
(
9
), pp.
3742
3746
.
13.
Ostrowicki
,
G. T.
,
Fritz
,
N. T.
, and
Sitaraman
,
S. K.
,
2012
, “
Domed and Released Thin-Film Construct—An Approach for Material Characterization and Compliant Interconnects
,”
IEEE Trans. Device Mater. Reliab.
,
12
(
1
), pp.
15
23
.
14.
Liu
,
X.
,
Chen
,
Q.
,
Sundaram
,
V.
,
Wachtler
,
K. P.
,
Tummala
,
R. R.
, and
Sitaraman
,
S. K.
,
2012
, “
Reliability Assessment of Through-Silicon Vias in Multi-Die Stack Packages
,”
IEEE Trans. Device Mater. Reliab.
,
12
(
1
), pp.
263
271
.
15.
Ho
,
C. E.
,
Lin
,
Y. W.
,
Yang
,
S. C.
,
Kao
,
C. R.
, and
Jiang
,
D. S.
,
2006
, “
Effects of Limited Cu Supply on Soldering Reactions Between SnAgCu and Ni
,”
J. Electron. Mater.
,
35
(
5
), pp.
1017
1024
.
16.
Chada
,
S.
,
Fournelle
,
R. A.
,
Laub
,
W.
, and
Shangguan
,
D.
,
2000
, “
Copper Substrate Dissolution in Eutectic Sn-Ag Solder and Its Effect on Microstructure
,”
J. Electron. Mater.
,
29
(
10
), pp.
1214
1221
.
17.
Islam
,
M. N.
,
Sharif
,
A.
, and
Chan
,
Y. C.
,
2005
, “
Effect of Volume in Interfacial Reaction Between Eutectic Sn-3.5% Ag-0.5% Cu Solder and Cu Metallization in Microelectronic Packaging
,”
J. Electron. Mater.
,
34
(
2
), pp.
143
149
.
18.
Massalski
,
T.
,
1996
,
Binary Alloy Phase Diagrams
, Vol.
3
,
ASM International
,
Metals Park, OH
.
19.
Rhee
,
H.
,
Guo
,
F.
, and
Lee
,
J. G.
,
2003
, “
Effects of Intermetallic Morphology at the Metallic Particle/Solder Interface on Mechanical Properties of Sn-Ag-Based Solder Joints
,”
J. Electron. Mater.
,
32
(
11
), pp.
1257
1264
.
20.
Sharif
,
A.
,
Chan
,
Y. C.
, and
Islam
,
R. A.
,
2004
, “
Effect of Volume in Interfacial Reaction Between Eutectic Sn-Pb Solder and Cu Metallization in Microelectronic Packaging
,”
Mater. Sci. Eng. B
,
106
(
2
), pp.
120
125
.
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