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Paper Survey

Fabrication of various dimensions of high fill-factormicro-lens arrays for OLED package

Sensors and Actuators A xxx (2010) xxx–xxx

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

Advisee ﹕ Sung-Wen Tsai

Institute of Mechanical EngineeringDate 2010/06/18﹕

K.H. Liua, M.F. Chenb, C.T. Panb, , M.Y. Changc, W.Y. Huangc∗

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Outline

The design principle

Fabrication process of gapless hexagonal micro-lens array

Results and discussions

Conclusion

The design principle

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21 DDT

1.T D≧ ： gap group

2.T ＜ D ： gapless

groupFig. 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.

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(D1=D2=D)

T<D(gapless)

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A B A B

A B A B

D

T

v

5

A B A

T

DB

T=D(tangential)

v

T>D(Not gapless)

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D

T

v

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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

The design principle

Table 1 The designed variables of seven micro-lens arrays (unit: μ m)

(aspect ratio = H/D)

Fabrication process of gapless hexagonal micro-lens array

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Fig. 2. A sketch of a circle array on a mask with three parameters.

V ： constant valueD ： variableT ： variable

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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

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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.

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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.

Fabrication process of gapless hexagonal micro-lens array

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gapless gapless

gapless gapless

13Not gaplessNot gapless

Not gapless

Results and discussions

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cbaHypotenuse

baV

cT

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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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

Error(C)=Diameter c –TError(hypotenuse)=measured value – designed value

Results and discussions

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).

Results and discussions

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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 thedecreasing percentages are 26.88%, 7.74% and 21.85%, respectively.

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