Abstract

High angular color uniformity (ACU) is strongly required in many illumination applications. In this study, we presented the phosphor dip-transfer coating method to realize high ACU for phosphor-converted white LEDs. The phosphor mixture was coated on top surfaces of LED chips and formed thin and convex phosphor layers by the dip-transfer coating. The optical simulations and experiments were conducted for performance verifications. Both numerical and experimental results show that the present method can obtain very high ACU. The angular correlated color temperature (CCT) deviation reaches 378 K when the average CCT of white LEDs is around 6200 K and it reduces to 63 K at the average CCT of about 4000 K.

© 2013 IEEE

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  1. S. Liu, X. B. Luo, LED Packaging for Lighting Applications: Design, Manufacturing and Testing (Wiley, 2011).
  2. A. Zukauskas, M. S. Shur, R. Caska, Introduction to Solid-state Lighting (Wiley, 2002).
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  4. Z. Y. Liu, C. Li, B. H. Yu, Y. H. Wang, H. B. Niu, "Effects of YAG: Ce phosphor particle size on luminous flux and angular color uniformity of phosphor-converted white LEDs," J. Disp. Technol. 8, 329-335 (2012).
  5. B. L. Wu, X. B. Luo, H. Zheng, S. Liu, "Effect of gold wire bonding process on angular correlated color temperature uniformity of white light-emitting diode," Opt. Exp. 19, 24115-24121 (2011).
  6. R. Y. Yu, S. Z. Jin, S. Y. Cen, P. Liang, "Effect of the phosphor geometry on the luminous flux of phosphor-converted light-emitting diodes," IEEE Photon. Technol. Lett. 22, 1765-1767 (2010).
  7. R. Hu, X. B. Luo, H. Feng, S. Liu, "Effect of phosphor settling on the optical performance of phosphor converted LED," J. Lumin. 132, 1252-1256 (2012).
  8. Z. Y. Liu, S. Liu, K. Wang, X. B. Luo, "Optical analysis of color distribution in white LEDs with various packaging methods," IEEE Photon. Technol. Lett. 20, 2027-2029 (2008).
  9. R. Hu, X. B. Luo, H. Zheng, Z. Qin, Z. Q. Gan, B. L. Wu, S. Liu, "Design of a novel freeform lens for LED uniform illumination and conformal phosphor coating," Opt. Exp. 20, 13727-13737 (2012).
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  13. C. Sommer, J. R. Krenn, P. Hartmann, P. Pachler, M. Schweighart, S. Tasch, F. P. Wenzl, "The effect of the phosphor particle sizes on the angular homogeneity of phosphor-converted high-power white LED light sources," IEEE J. Sel. Topics Quantum Electron. 15, 1181-1188 (2009).
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  19. H. T. Huang, C. C. Tsai, Y. P. Huang, "Conformal phosphor coating using pulsed spray to reduce color deviation of white LEDs," Opt. Exp. 18, A201-A206 (2010).
  20. Z. Y. Liu, C. Li, B. H. Yu, Y. H. Wang, H. B. Niu, "Uniform white emission of WLEDs realized by multilayer phosphor with pyramidal shape and inversed concentration distribution," IEEE Photon. Technol. Lett. 24, 1558-1560 (2012).
  21. C. Sommer, F. P. Wenzl, P. Hartmann, P. Pachler, M. Schweighart, G. Leising, "Tailoring of the color conversion elements in phosphorconverted high-power LEDs by optical simulations," IEEE Photon. Technol. Lett. 20, 739-741 (2008).
  22. C. Sommer, F. Reil, J. R. Krenn, P. Hartmann, P. Pachler, S. Tasch, F. P. Wenzl, "The impact of inhomogeneities in the phosphor distribution on the device performance of phosphor-converted high-power white LED light sources," J. Lightw. Technol. 28, 3226-3232 (2010).
  23. H. Kuo, C. Hung, H. Chen, K. Chen, C. Wang, C. Sher, C. Yeh, C. Lin, C. Chen, Y. Cheng, "Patterned structure of REMOTE PHOSPHOR for phosphor-converted white LEDs," Opt. Exp. 19, A930-A936 (2011).
  24. A. A. Darhuber, S. M. Troian, J. M. Davis, S. M. Miller, S. Wagner, "Selective dip-transfer coating of chemically micropatterned surfaces," J. Appl. Phys. 88, 5119-5126 (2000).
  25. J. Berthier, K. Brakke, F. Grossi, L. Sanchez, L. Di Cioccio, "Self-alignment of silicon chips on wafers: A capillary approach," J. Appl. Phys. 108, 054905-1-054905-10 (2010).
  26. H. Zheng, X. B. Luo, "Correlated color temperature consistency enhancement of white light-emitting diodes through substrate structure design," IEEE Photon. Technol. Lett. 25, 484-487 (2013).
  27. Y. H. Jang, K. Lee, Y. K. Kim, "Controlled volume transfer and lens shape formation by liquid bridge disconnection," Appl. Phys. Lett. 100, 214103-1-214103-3 (2012).
  28. Z. Y. Liu, S. Liu, K. Wang, X. B. Luo, "Measurement and numerical studies of optical properties of YAG: Ce phosphor for white light-emitting diode packaging," Appl. Opt. 49, 247-257 (2010).

2013 (1)

H. Zheng, X. B. Luo, "Correlated color temperature consistency enhancement of white light-emitting diodes through substrate structure design," IEEE Photon. Technol. Lett. 25, 484-487 (2013).

2012 (7)

Y. H. Jang, K. Lee, Y. K. Kim, "Controlled volume transfer and lens shape formation by liquid bridge disconnection," Appl. Phys. Lett. 100, 214103-1-214103-3 (2012).

Z. Y. Liu, C. Li, B. H. Yu, Y. H. Wang, H. B. Niu, "Effects of YAG: Ce phosphor particle size on luminous flux and angular color uniformity of phosphor-converted white LEDs," J. Disp. Technol. 8, 329-335 (2012).

R. Hu, X. B. Luo, H. Feng, S. Liu, "Effect of phosphor settling on the optical performance of phosphor converted LED," J. Lumin. 132, 1252-1256 (2012).

R. Hu, X. B. Luo, H. Zheng, Z. Qin, Z. Q. Gan, B. L. Wu, S. Liu, "Design of a novel freeform lens for LED uniform illumination and conformal phosphor coating," Opt. Exp. 20, 13727-13737 (2012).

H. Zheng, X. B. Luo, R. Hu, B. Cao, X. Fu, Y. M. Wang, S. Liu, "Conformal phosphor coating using capillary microchannel for controlling color deviation of phosphor-converted white light-emitting diodes," Opt. Exp. 20, 5092-5098 (2012).

C. C. Sun, C. Y. Chen, C. C. Chen, C. Y. Chiu, Y. N. Peng, Y. H. Wang, T. H. Yang, T. Y. Chung, C. Y. Chung, "High uniformity in angular correlated-colortemperature distribution of white LEDs from 2800 K to 6500 K," Opt. Exp. 20, 6622-6630 (2012).

Z. Y. Liu, C. Li, B. H. Yu, Y. H. Wang, H. B. Niu, "Uniform white emission of WLEDs realized by multilayer phosphor with pyramidal shape and inversed concentration distribution," IEEE Photon. Technol. Lett. 24, 1558-1560 (2012).

2011 (4)

H. Kuo, C. Hung, H. Chen, K. Chen, C. Wang, C. Sher, C. Yeh, C. Lin, C. Chen, Y. Cheng, "Patterned structure of REMOTE PHOSPHOR for phosphor-converted white LEDs," Opt. Exp. 19, A930-A936 (2011).

S. A. Yun, Y. Z. He, N. T. Tran, F. G. Shi, "Angular CCT uniformity of phosphor converted white LEDs: Effects of phosphor materials and packaging structures," IEEE Photon. Technol. Lett. 23, 137-139 (2011).

R. Hu, X. B. Luo, S. Liu, "Study on the optical properties of conformal coating light-emitting diode by Monte Carlo simulation," IEEE Photon. Technol. Lett. 23, 1673-1675 (2011).

B. L. Wu, X. B. Luo, H. Zheng, S. Liu, "Effect of gold wire bonding process on angular correlated color temperature uniformity of white light-emitting diode," Opt. Exp. 19, 24115-24121 (2011).

2010 (6)

R. Y. Yu, S. Z. Jin, S. Y. Cen, P. Liang, "Effect of the phosphor geometry on the luminous flux of phosphor-converted light-emitting diodes," IEEE Photon. Technol. Lett. 22, 1765-1767 (2010).

K. Wang, D. Wu, F. Chen, Z. Y. Liu, X. B. Luo, S. Liu, "Angular color uniformity enhancement of white light-emitting diodes integrated with freeform lenses," Opt. Lett. 35, 1860-1862 (2010).

H. T. Huang, C. C. Tsai, Y. P. Huang, "Conformal phosphor coating using pulsed spray to reduce color deviation of white LEDs," Opt. Exp. 18, A201-A206 (2010).

Z. Y. Liu, S. Liu, K. Wang, X. B. Luo, "Measurement and numerical studies of optical properties of YAG: Ce phosphor for white light-emitting diode packaging," Appl. Opt. 49, 247-257 (2010).

C. Sommer, F. Reil, J. R. Krenn, P. Hartmann, P. Pachler, S. Tasch, F. P. Wenzl, "The impact of inhomogeneities in the phosphor distribution on the device performance of phosphor-converted high-power white LED light sources," J. Lightw. Technol. 28, 3226-3232 (2010).

J. Berthier, K. Brakke, F. Grossi, L. Sanchez, L. Di Cioccio, "Self-alignment of silicon chips on wafers: A capillary approach," J. Appl. Phys. 108, 054905-1-054905-10 (2010).

2009 (1)

C. Sommer, J. R. Krenn, P. Hartmann, P. Pachler, M. Schweighart, S. Tasch, F. P. Wenzl, "The effect of the phosphor particle sizes on the angular homogeneity of phosphor-converted high-power white LED light sources," IEEE J. Sel. Topics Quantum Electron. 15, 1181-1188 (2009).

2008 (2)

Z. Y. Liu, S. Liu, K. Wang, X. B. Luo, "Optical analysis of color distribution in white LEDs with various packaging methods," IEEE Photon. Technol. Lett. 20, 2027-2029 (2008).

C. Sommer, F. P. Wenzl, P. Hartmann, P. Pachler, M. Schweighart, G. Leising, "Tailoring of the color conversion elements in phosphorconverted high-power LEDs by optical simulations," IEEE Photon. Technol. Lett. 20, 739-741 (2008).

2000 (1)

A. A. Darhuber, S. M. Troian, J. M. Davis, S. M. Miller, S. Wagner, "Selective dip-transfer coating of chemically micropatterned surfaces," J. Appl. Phys. 88, 5119-5126 (2000).

Appl. Phys. Lett. (1)

Y. H. Jang, K. Lee, Y. K. Kim, "Controlled volume transfer and lens shape formation by liquid bridge disconnection," Appl. Phys. Lett. 100, 214103-1-214103-3 (2012).

Appl. Opt. (1)

IEEE Photon. Technol. Lett. (1)

R. Y. Yu, S. Z. Jin, S. Y. Cen, P. Liang, "Effect of the phosphor geometry on the luminous flux of phosphor-converted light-emitting diodes," IEEE Photon. Technol. Lett. 22, 1765-1767 (2010).

IEEE J. Sel. Topics Quantum Electron. (1)

C. Sommer, J. R. Krenn, P. Hartmann, P. Pachler, M. Schweighart, S. Tasch, F. P. Wenzl, "The effect of the phosphor particle sizes on the angular homogeneity of phosphor-converted high-power white LED light sources," IEEE J. Sel. Topics Quantum Electron. 15, 1181-1188 (2009).

IEEE Photon. Technol. Lett. (1)

Z. Y. Liu, S. Liu, K. Wang, X. B. Luo, "Optical analysis of color distribution in white LEDs with various packaging methods," IEEE Photon. Technol. Lett. 20, 2027-2029 (2008).

IEEE Photon. Technol. Lett. (5)

S. A. Yun, Y. Z. He, N. T. Tran, F. G. Shi, "Angular CCT uniformity of phosphor converted white LEDs: Effects of phosphor materials and packaging structures," IEEE Photon. Technol. Lett. 23, 137-139 (2011).

R. Hu, X. B. Luo, S. Liu, "Study on the optical properties of conformal coating light-emitting diode by Monte Carlo simulation," IEEE Photon. Technol. Lett. 23, 1673-1675 (2011).

Z. Y. Liu, C. Li, B. H. Yu, Y. H. Wang, H. B. Niu, "Uniform white emission of WLEDs realized by multilayer phosphor with pyramidal shape and inversed concentration distribution," IEEE Photon. Technol. Lett. 24, 1558-1560 (2012).

C. Sommer, F. P. Wenzl, P. Hartmann, P. Pachler, M. Schweighart, G. Leising, "Tailoring of the color conversion elements in phosphorconverted high-power LEDs by optical simulations," IEEE Photon. Technol. Lett. 20, 739-741 (2008).

H. Zheng, X. B. Luo, "Correlated color temperature consistency enhancement of white light-emitting diodes through substrate structure design," IEEE Photon. Technol. Lett. 25, 484-487 (2013).

J. Appl. Phys. (1)

A. A. Darhuber, S. M. Troian, J. M. Davis, S. M. Miller, S. Wagner, "Selective dip-transfer coating of chemically micropatterned surfaces," J. Appl. Phys. 88, 5119-5126 (2000).

J. Appl. Phys. (1)

J. Berthier, K. Brakke, F. Grossi, L. Sanchez, L. Di Cioccio, "Self-alignment of silicon chips on wafers: A capillary approach," J. Appl. Phys. 108, 054905-1-054905-10 (2010).

J. Disp. Technol. (1)

Z. Y. Liu, C. Li, B. H. Yu, Y. H. Wang, H. B. Niu, "Effects of YAG: Ce phosphor particle size on luminous flux and angular color uniformity of phosphor-converted white LEDs," J. Disp. Technol. 8, 329-335 (2012).

J. Lightw. Technol. (1)

C. Sommer, F. Reil, J. R. Krenn, P. Hartmann, P. Pachler, S. Tasch, F. P. Wenzl, "The impact of inhomogeneities in the phosphor distribution on the device performance of phosphor-converted high-power white LED light sources," J. Lightw. Technol. 28, 3226-3232 (2010).

J. Lumin. (1)

R. Hu, X. B. Luo, H. Feng, S. Liu, "Effect of phosphor settling on the optical performance of phosphor converted LED," J. Lumin. 132, 1252-1256 (2012).

Opt. Exp. (1)

H. Zheng, X. B. Luo, R. Hu, B. Cao, X. Fu, Y. M. Wang, S. Liu, "Conformal phosphor coating using capillary microchannel for controlling color deviation of phosphor-converted white light-emitting diodes," Opt. Exp. 20, 5092-5098 (2012).

Opt. Lett. (1)

K. Wang, D. Wu, F. Chen, Z. Y. Liu, X. B. Luo, S. Liu, "Angular color uniformity enhancement of white light-emitting diodes integrated with freeform lenses," Opt. Lett. 35, 1860-1862 (2010).

Opt. Exp. (5)

H. T. Huang, C. C. Tsai, Y. P. Huang, "Conformal phosphor coating using pulsed spray to reduce color deviation of white LEDs," Opt. Exp. 18, A201-A206 (2010).

C. C. Sun, C. Y. Chen, C. C. Chen, C. Y. Chiu, Y. N. Peng, Y. H. Wang, T. H. Yang, T. Y. Chung, C. Y. Chung, "High uniformity in angular correlated-colortemperature distribution of white LEDs from 2800 K to 6500 K," Opt. Exp. 20, 6622-6630 (2012).

R. Hu, X. B. Luo, H. Zheng, Z. Qin, Z. Q. Gan, B. L. Wu, S. Liu, "Design of a novel freeform lens for LED uniform illumination and conformal phosphor coating," Opt. Exp. 20, 13727-13737 (2012).

B. L. Wu, X. B. Luo, H. Zheng, S. Liu, "Effect of gold wire bonding process on angular correlated color temperature uniformity of white light-emitting diode," Opt. Exp. 19, 24115-24121 (2011).

H. Kuo, C. Hung, H. Chen, K. Chen, C. Wang, C. Sher, C. Yeh, C. Lin, C. Chen, Y. Cheng, "Patterned structure of REMOTE PHOSPHOR for phosphor-converted white LEDs," Opt. Exp. 19, A930-A936 (2011).

Other (6)

S. Liu, X. B. Luo, LED Packaging for Lighting Applications: Design, Manufacturing and Testing (Wiley, 2011).

A. Zukauskas, M. S. Shur, R. Caska, Introduction to Solid-state Lighting (Wiley, 2002).

W. D. Collins, M. R. Krames, G. J. Verhoeckx, N. J. M. Leth, Using Electrophoresis to Produce a Conformally Coated Phosphor-Converted Light Emitting Semiconductor U.S. Patent 6 576 488 B2 (2003).

J. H. Yum, S. Y. Seo, S. Lee, Y. E. Sung, "Comparison of Y3Al5O12: Ce0.05 phosphor coating methods for white light emitting diode on gallium nitride," Proc. SPIE (2001) pp. 60-68.

B. Braune, K. Petersen, J. Strauss, P. Kromotis, M. Kaempf, "A new wafer level coating technique to reduce the color distribution of LEDs," Proc. SPIE (2007) pp. 68460x.

H. Zheng, X. Fu, R. Hu, S. Liu, X. B. Luo, "Angular color uniformity improvement for phosphor-converted white light-emitting diodes by optimizing remote coating phosphor geometry," Proc. 13th Int. Conf. Electronic Packaging Technol. High Density Packaging (2012) pp. 1483-1486.

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