Abstract

A novel light-emitting diode (LED) packaging method, named the active packaging (AP) method, is presented in this paper. In this method, during the LED packaging process, the light emitted from a GaN LED chip itself is employed to package the LED encapsulant, thereby eliminating the need to utilize a mold. Current injection into a bare LED chip, triggers a photosensitive epoxy to polymerize, leading to the formation of mushroom lamp cap on the LED chip. The emission properties of LEDs fabricated by this method, including their emission beam profiles and light outputs, were characterized. The results showed that a self-focusing effect happened with the addition of an epoxy on the chip. The simulation demonstrated that the geometry the encapsulant controlled the beam pattern of emission. Further, the self-focusing effect was believed to be caused by the combination of the threshold energy of epoxy polymerization, the beam pattern and the power output of the LED chip.

© 2008 Optical Society of America

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  1. D. A. Steigerwald, J. C. Bhat, D. Collins, R. M. Fletcher, M. O. Holcomb, M. J. Ludowise, P. S. Martin, and S. L. Rudaz, "Illumination with solid state lighting technology," IEEE J. Selected Topics Quantum Electron. 8, 310-320 (2002).
    [CrossRef]
  2. R. J. M. Zwiers, H. J. L. Bressers, B. Ouwehand, and D. Baumann, "Development of a new low-stress hyperred LED encapsulant," Components, Hybrids, and Manufacturing Technology, IEEE Transactions on 12, 387-392 (1989).
    [CrossRef]
  3. R. N. Kumar, L. Y. Keem, N. C. Mang, and A. Abubakar, "Ultraviolet Radiation Curable Epoxy Resin Encapsulant for Light Emitting Diodes," J. Appl. Polym. Sci. 100, 1048-1056 (2006).
    [CrossRef]
  4. J. N. Tey, A. M. Soutar, S. G. Mhaisalkar, H. Yu, and K. M. Hew, "Mechanical properties of UV-curable polyurethane acrylate used in packaging of MEMS devices," Thin Solid Films 504, 384-390 (2006).
    [CrossRef]
  5. A. Hancock and L. Lin, "Challenges of UV curable ink-jet printing inks - a formulator's perspective," Pigment & Resin Technology 33, 280-286 (2004).
    [CrossRef]
  6. J. Serbin, A. Ovsianikov, and B. Chichkov, "Fabrication of woodpile structures by two-photon polymerization and investigation of their optical properties," Opt. Express 12, 5221-5228 (2004).
    [CrossRef] [PubMed]
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    [CrossRef] [PubMed]
  8. H. Wang, K. Lee, S. Li, L. Jin, S. Lee, Y. Wu, Y. Cho, and J. Cai, "Fabrication of CdSe-ZnS nanocrystal-based local fluorescent aperture probes by active polymerization of photosensitive epoxy," accepted by Opt. Comm. (2008) http://dx.doi.org/10.1016/j.optcom.2007.11.086.
  9. R. Bachelot, C. Ecoffet, D. Deloeil, P. Royer, and D. -J. Lougnot, Appl. Opt. 40, 5860 (2001).
    [CrossRef]

2006 (2)

R. N. Kumar, L. Y. Keem, N. C. Mang, and A. Abubakar, "Ultraviolet Radiation Curable Epoxy Resin Encapsulant for Light Emitting Diodes," J. Appl. Polym. Sci. 100, 1048-1056 (2006).
[CrossRef]

J. N. Tey, A. M. Soutar, S. G. Mhaisalkar, H. Yu, and K. M. Hew, "Mechanical properties of UV-curable polyurethane acrylate used in packaging of MEMS devices," Thin Solid Films 504, 384-390 (2006).
[CrossRef]

2004 (2)

A. Hancock and L. Lin, "Challenges of UV curable ink-jet printing inks - a formulator's perspective," Pigment & Resin Technology 33, 280-286 (2004).
[CrossRef]

J. Serbin, A. Ovsianikov, and B. Chichkov, "Fabrication of woodpile structures by two-photon polymerization and investigation of their optical properties," Opt. Express 12, 5221-5228 (2004).
[CrossRef] [PubMed]

2003 (1)

D. Therriault, S. White, and J. Lewis, "Chaotic mixing in three-dimensional microvascular networks fabricated by direct-write assembly," Nature Materials 2, 265-271 (2003).
[CrossRef] [PubMed]

2002 (1)

D. A. Steigerwald, J. C. Bhat, D. Collins, R. M. Fletcher, M. O. Holcomb, M. J. Ludowise, P. S. Martin, and S. L. Rudaz, "Illumination with solid state lighting technology," IEEE J. Selected Topics Quantum Electron. 8, 310-320 (2002).
[CrossRef]

2001 (1)

1989 (1)

R. J. M. Zwiers, H. J. L. Bressers, B. Ouwehand, and D. Baumann, "Development of a new low-stress hyperred LED encapsulant," Components, Hybrids, and Manufacturing Technology, IEEE Transactions on 12, 387-392 (1989).
[CrossRef]

Abubakar, A.

R. N. Kumar, L. Y. Keem, N. C. Mang, and A. Abubakar, "Ultraviolet Radiation Curable Epoxy Resin Encapsulant for Light Emitting Diodes," J. Appl. Polym. Sci. 100, 1048-1056 (2006).
[CrossRef]

Bachelot, R.

Baumann, D.

R. J. M. Zwiers, H. J. L. Bressers, B. Ouwehand, and D. Baumann, "Development of a new low-stress hyperred LED encapsulant," Components, Hybrids, and Manufacturing Technology, IEEE Transactions on 12, 387-392 (1989).
[CrossRef]

Bhat, J. C.

D. A. Steigerwald, J. C. Bhat, D. Collins, R. M. Fletcher, M. O. Holcomb, M. J. Ludowise, P. S. Martin, and S. L. Rudaz, "Illumination with solid state lighting technology," IEEE J. Selected Topics Quantum Electron. 8, 310-320 (2002).
[CrossRef]

Bressers, H. J. L.

R. J. M. Zwiers, H. J. L. Bressers, B. Ouwehand, and D. Baumann, "Development of a new low-stress hyperred LED encapsulant," Components, Hybrids, and Manufacturing Technology, IEEE Transactions on 12, 387-392 (1989).
[CrossRef]

Chichkov, B.

Collins, D.

D. A. Steigerwald, J. C. Bhat, D. Collins, R. M. Fletcher, M. O. Holcomb, M. J. Ludowise, P. S. Martin, and S. L. Rudaz, "Illumination with solid state lighting technology," IEEE J. Selected Topics Quantum Electron. 8, 310-320 (2002).
[CrossRef]

Deloeil, D.

Ecoffet, C.

Fletcher, R. M.

D. A. Steigerwald, J. C. Bhat, D. Collins, R. M. Fletcher, M. O. Holcomb, M. J. Ludowise, P. S. Martin, and S. L. Rudaz, "Illumination with solid state lighting technology," IEEE J. Selected Topics Quantum Electron. 8, 310-320 (2002).
[CrossRef]

Hancock, A.

A. Hancock and L. Lin, "Challenges of UV curable ink-jet printing inks - a formulator's perspective," Pigment & Resin Technology 33, 280-286 (2004).
[CrossRef]

Hew, K. M.

J. N. Tey, A. M. Soutar, S. G. Mhaisalkar, H. Yu, and K. M. Hew, "Mechanical properties of UV-curable polyurethane acrylate used in packaging of MEMS devices," Thin Solid Films 504, 384-390 (2006).
[CrossRef]

Holcomb, M. O.

D. A. Steigerwald, J. C. Bhat, D. Collins, R. M. Fletcher, M. O. Holcomb, M. J. Ludowise, P. S. Martin, and S. L. Rudaz, "Illumination with solid state lighting technology," IEEE J. Selected Topics Quantum Electron. 8, 310-320 (2002).
[CrossRef]

Keem, L. Y.

R. N. Kumar, L. Y. Keem, N. C. Mang, and A. Abubakar, "Ultraviolet Radiation Curable Epoxy Resin Encapsulant for Light Emitting Diodes," J. Appl. Polym. Sci. 100, 1048-1056 (2006).
[CrossRef]

Kumar, R. N.

R. N. Kumar, L. Y. Keem, N. C. Mang, and A. Abubakar, "Ultraviolet Radiation Curable Epoxy Resin Encapsulant for Light Emitting Diodes," J. Appl. Polym. Sci. 100, 1048-1056 (2006).
[CrossRef]

Lewis, J.

D. Therriault, S. White, and J. Lewis, "Chaotic mixing in three-dimensional microvascular networks fabricated by direct-write assembly," Nature Materials 2, 265-271 (2003).
[CrossRef] [PubMed]

Lin, L.

A. Hancock and L. Lin, "Challenges of UV curable ink-jet printing inks - a formulator's perspective," Pigment & Resin Technology 33, 280-286 (2004).
[CrossRef]

Lougnot, D. -J.

Ludowise, M. J.

D. A. Steigerwald, J. C. Bhat, D. Collins, R. M. Fletcher, M. O. Holcomb, M. J. Ludowise, P. S. Martin, and S. L. Rudaz, "Illumination with solid state lighting technology," IEEE J. Selected Topics Quantum Electron. 8, 310-320 (2002).
[CrossRef]

Mang, N. C.

R. N. Kumar, L. Y. Keem, N. C. Mang, and A. Abubakar, "Ultraviolet Radiation Curable Epoxy Resin Encapsulant for Light Emitting Diodes," J. Appl. Polym. Sci. 100, 1048-1056 (2006).
[CrossRef]

Martin, P. S.

D. A. Steigerwald, J. C. Bhat, D. Collins, R. M. Fletcher, M. O. Holcomb, M. J. Ludowise, P. S. Martin, and S. L. Rudaz, "Illumination with solid state lighting technology," IEEE J. Selected Topics Quantum Electron. 8, 310-320 (2002).
[CrossRef]

Mhaisalkar, S. G.

J. N. Tey, A. M. Soutar, S. G. Mhaisalkar, H. Yu, and K. M. Hew, "Mechanical properties of UV-curable polyurethane acrylate used in packaging of MEMS devices," Thin Solid Films 504, 384-390 (2006).
[CrossRef]

Ouwehand, B.

R. J. M. Zwiers, H. J. L. Bressers, B. Ouwehand, and D. Baumann, "Development of a new low-stress hyperred LED encapsulant," Components, Hybrids, and Manufacturing Technology, IEEE Transactions on 12, 387-392 (1989).
[CrossRef]

Ovsianikov, A.

Royer, P.

Rudaz, S. L.

D. A. Steigerwald, J. C. Bhat, D. Collins, R. M. Fletcher, M. O. Holcomb, M. J. Ludowise, P. S. Martin, and S. L. Rudaz, "Illumination with solid state lighting technology," IEEE J. Selected Topics Quantum Electron. 8, 310-320 (2002).
[CrossRef]

Serbin, J.

Soutar, A. M.

J. N. Tey, A. M. Soutar, S. G. Mhaisalkar, H. Yu, and K. M. Hew, "Mechanical properties of UV-curable polyurethane acrylate used in packaging of MEMS devices," Thin Solid Films 504, 384-390 (2006).
[CrossRef]

Steigerwald, D. A.

D. A. Steigerwald, J. C. Bhat, D. Collins, R. M. Fletcher, M. O. Holcomb, M. J. Ludowise, P. S. Martin, and S. L. Rudaz, "Illumination with solid state lighting technology," IEEE J. Selected Topics Quantum Electron. 8, 310-320 (2002).
[CrossRef]

Tey, J. N.

J. N. Tey, A. M. Soutar, S. G. Mhaisalkar, H. Yu, and K. M. Hew, "Mechanical properties of UV-curable polyurethane acrylate used in packaging of MEMS devices," Thin Solid Films 504, 384-390 (2006).
[CrossRef]

Therriault, D.

D. Therriault, S. White, and J. Lewis, "Chaotic mixing in three-dimensional microvascular networks fabricated by direct-write assembly," Nature Materials 2, 265-271 (2003).
[CrossRef] [PubMed]

White, S.

D. Therriault, S. White, and J. Lewis, "Chaotic mixing in three-dimensional microvascular networks fabricated by direct-write assembly," Nature Materials 2, 265-271 (2003).
[CrossRef] [PubMed]

Yu, H.

J. N. Tey, A. M. Soutar, S. G. Mhaisalkar, H. Yu, and K. M. Hew, "Mechanical properties of UV-curable polyurethane acrylate used in packaging of MEMS devices," Thin Solid Films 504, 384-390 (2006).
[CrossRef]

Zwiers, R. J. M.

R. J. M. Zwiers, H. J. L. Bressers, B. Ouwehand, and D. Baumann, "Development of a new low-stress hyperred LED encapsulant," Components, Hybrids, and Manufacturing Technology, IEEE Transactions on 12, 387-392 (1989).
[CrossRef]

Appl. Opt. (1)

IEEE J. Selected Topics Quantum Electron. (1)

D. A. Steigerwald, J. C. Bhat, D. Collins, R. M. Fletcher, M. O. Holcomb, M. J. Ludowise, P. S. Martin, and S. L. Rudaz, "Illumination with solid state lighting technology," IEEE J. Selected Topics Quantum Electron. 8, 310-320 (2002).
[CrossRef]

IEEE Transactions on (1)

R. J. M. Zwiers, H. J. L. Bressers, B. Ouwehand, and D. Baumann, "Development of a new low-stress hyperred LED encapsulant," Components, Hybrids, and Manufacturing Technology, IEEE Transactions on 12, 387-392 (1989).
[CrossRef]

J. Appl. Polym. Sci. (1)

R. N. Kumar, L. Y. Keem, N. C. Mang, and A. Abubakar, "Ultraviolet Radiation Curable Epoxy Resin Encapsulant for Light Emitting Diodes," J. Appl. Polym. Sci. 100, 1048-1056 (2006).
[CrossRef]

Nature Materials (1)

D. Therriault, S. White, and J. Lewis, "Chaotic mixing in three-dimensional microvascular networks fabricated by direct-write assembly," Nature Materials 2, 265-271 (2003).
[CrossRef] [PubMed]

Opt. Express (1)

Pigment & Resin Technology (1)

A. Hancock and L. Lin, "Challenges of UV curable ink-jet printing inks - a formulator's perspective," Pigment & Resin Technology 33, 280-286 (2004).
[CrossRef]

Thin Solid Films (1)

J. N. Tey, A. M. Soutar, S. G. Mhaisalkar, H. Yu, and K. M. Hew, "Mechanical properties of UV-curable polyurethane acrylate used in packaging of MEMS devices," Thin Solid Films 504, 384-390 (2006).
[CrossRef]

Other (1)

H. Wang, K. Lee, S. Li, L. Jin, S. Lee, Y. Wu, Y. Cho, and J. Cai, "Fabrication of CdSe-ZnS nanocrystal-based local fluorescent aperture probes by active polymerization of photosensitive epoxy," accepted by Opt. Comm. (2008) http://dx.doi.org/10.1016/j.optcom.2007.11.086.

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Figures (3)

Fig. 1.
Fig. 1.

The manufacturing process of the active packaging (AP) method. A To-Can-type LED was utilized to perform the polymerization. (a) The comparison of absorbance of the epoxy and the electroluminescence (EL) of the To-Can-type LED at 1 mA injection. (b) The light output profile of the LED chip under different work currents (The working curve at 1 mA was multiplied with a factor of 5). The dashed grey line indicates the proposed threshold energy of the epoxy polymerization. (c) The experiment process of the AP method. The LED chip was immersed in the photosensitive epoxy resins and then a polymerization current (PC) was injected into the LED chip so that it emitted blue light, thereby triggering the polymerization of the photosensitive epoxy, and resulting in a mushroom-shaped encapsulant. (d) Top view of the bare LED chip (inset shows the size of the chip: the scale bar is 0.1 mm). The yellow arrows indicate the measurement direction of the beam pattern (Fig. 3). (e) Top view of a LED (PC3) fabricated by our proposed process. Inset shows the side view of the encapsulant.

Fig. 2.
Fig. 2.

The geometry of LED lamps fabricated by the AP method. PT samples are shown in (a). The manufacturing parameters are as follows. PT1: 1 mA - 1 s, PT2: 1 mA - 2 s, PT3: 1 mA - 3 s, and PT4: 1 mA - 4 s. PT samples shown in (b). The manufacturing parameters are as follows. PC1: 1 mA - 1 s, PC2: 10 mA - 1 s, PC3: 20 mA - 1 s, and PC4: 30 mA - 1 s. (c) and (d) are the geometries for the PT and PC cases, respectively. (e) and (f) are the sizes for the PT and PC cases; the height, the diameter, and their ratio are also shown.

Fig. 3.
Fig. 3.

The beam profiles of (a) PT and (c) PC samples (driven at 50 mA). The orientation of the LED lamps is along 0° (direction shown by arrows in Fig. 1(c)). (b) and (d) are the simulated light output of the samples corresponding to (a) and (c).

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