Sensors and Actuators A xxx (2010) xxx–xxx
Fabrication of various dimensions of high fill-factor
micro-lens arrays for OLED package
K.H. Liua, M.F. Chenb, C.T. Panb,∗, M.Y. Changc, W.Y. Huangc
a Department of Mechanical Engineering, R.O.C. Military Academy, Kaohsiung, Taiwan, ROC
b Department of Mechanical and Electro-Mechanical Engineering, Center for Nanoscience and Nanotechnology,
National Sun-Yat-Sen University, 70 Lien-hai Rd., Kaohsiung 804, Taiwan, ROC
c Department of Photonics, National Sun-Yat-Sen University, Kaohsiung 804, Taiwan, ROC
Paper Survey
Advisee ﹕ Sung-Wen Tsai
Institute of Mechanical Engineering
Date ﹕2010/06/18
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Outline
 The design principle
 Fabrication process of gapless hexagonal micro-lens array
 Results and discussions
 Conclusion
2
The design principle
 D1 D 2 
T  

2 
 2
 D1 D 2 
T  

2 
 2
(D1=D2=D)
1.T≧D：gap group
2.T＜D：gapless group
Fig. 1. The three smaller circles (A, B and C) are the patterns of a mask; three bigger circles which are
drawn in dotted line are used to describe the micro-lenses how to interwork; finally, the interworked
micro-lenses become hexagonal micro-lenses.Diameter (D) is the original diameter of a pattern on a mask;
vertical (V) is a distance of; period (T) is a distance of AB, and it is also a distance of centers of two circles. 3
T<D(gapless)
T
B
A
A
B
A
B
D
v
A
B
4
T=D(tangential)
T
D
A
v
B
A
B
5
T>D(Not gapless)
T
v
D
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The design principle
(aspect ratio = H/D)
No.
Diameter Thickness(H) Vertical(V) Period(T)
Hypotensue
Layout
Aspect ratio
1
40
12.5
100
50
55.90
gapless
0.313
2
30
12.5
100
40
53.85
gapless
0.416
3
25
12.5
100
35
52.97
gapless
0.5
4
15
5
100
25
51.54
gapless
0.33
5
40
12.5
100
50
55.90
Not gapless
0.25
6
25
12.5
100
35
52.97
Not gapless
0.5
7
15
5
100
25
51.54
Not gapless
0.313
Table 1 The designed variables of seven micro-lens arrays (unit: μ m)
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Fabrication process of gapless
hexagonal micro-lens array
V：constant value
D：variable
T：variable
Fig. 2. A sketch of a circle array on a mask with three parameters.
8
Fabrication process of gapless
hexagonal micro-lens array
Fig. 3.Schematic lithography process: (a) spin coating the photoresist AZ4620; (b) a cylindrical array was
obtained after development; (c) reflow the microstructures at 140 ◦C; (d) sputtering a Ni-film as a seed layer 9
Fabrication process of gapless
hexagonal micro-lens array
Fig. 3.(e) NiCo electroplating was used to wrap the photoresist micro-lenses to form a gapless mold;
(f) a passivation treatment with thermal method was applied on the surface of NiCo alloy; (g) a secondary
electroplating was performed, and CMP process was used to flat the surface; the substrate was removed.
10
Fabrication process of gapless
hexagonal micro-lens array
Fig. 4. A replication of UV-cured process: (a) spin coating the polymer on the secondary mold, and
exposed to UV light; (b) after several seconds, the polymer was cured.
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gapless
gapless
gapless
gapless
12
Not gapless
Not gapless
Not gapless
13
Results and discussions
T c
a b
V 
2 2
2
a b c
Hypotenuse       
 2 2 2
2
Fig. 4. The definition of three measured distance of a micro-lens. The three values can be
used to calculate the length of Hypotenuse as shown in Fig. 1. This figure was drawn by
computer software, Solidworks.
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Results and discussions
Error(C)=Diameter c –T
Error(hypotenuse)=measured value – designed value
No.
Diameter a
Diameter b
Diameter c
Hypotenuse
Error(c)
Error(hypotenuse)
1
38.01
62.21
50.80
56.18
0.80
0.28
2
40.09
59.10
40.09
53.49
0.09
-0.36
3
43.20
55.64
35.25
52.47
0.25
-0.5
4
47.35
52.53
25.23
51.51
0.23
-0.03
5
26.61
57.02
50.11
48.75
0.11
-7.14
6
39.40
52.18
35.25
49.06
0.25
-3.91
7
42.51
50.11
25.23
48.00
0.23
-3.54
Table 2 The measured data of seven different micro-lens arrays and the error of measured and designed
value. Positive errors mean the micro-lenses are bigger than designed one and negative errors mean they
are smaller (unit: μ m).
15
Results and discussions
Measurement instrument：SpectraScan Colorimeter PR-650
Fig. 5. Nine points of measurement of an optical film, and an OLED as light source
under the optical film (a region of a gray rectangle).
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Results and discussions
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Results and discussions
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Results and discussions
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Results and discussions
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Results and discussions
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Results and discussions
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Results and discussions
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Results and discussions
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Results and discussions
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Results and discussions
Fig. 11. The luminance comparison of a base and an optic film, Sample 3, (a) the comparison
of points 1, 3, 4, 6, 7 and 9 of a base and Sample 3, and the raising percentages are 120.59%,
830.90%, 313.42%, 502.86%, 512.35% and 599.82%, respec-tively
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Results and discussions
Fig. 11. (b) the comparison of points 2, 5 and 8 of a base and Sample 3, and the
decreasing percentages are 26.88%, 7.74% and 21.85%, respectively.
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Conclusion
1.A LIGA-like process was applied in this study,
because it has good replication for microstructures.
2.The effect of an optical film with gapless and high
aspect ratio micro-lens array can show more obvious
results than of the other designs.
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Thanks for your attention
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