White LED modules encapsulation features
The behaviour and causes of changes for correlated color temperature (CCT) and radiant spectral power in white LED modules of different design at their encapsulation by optical compounds are investigated. It is shown that CCT of original white LED radiation can both decrease and increase after po...
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| Date: | 2013 |
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України
2013
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| Series: | Semiconductor Physics Quantum Electronics & Optoelectronics |
| Online Access: | https://nasplib.isofts.kiev.ua/handle/123456789/117691 |
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| Cite this: | White LED modules encapsulation features / Yu.V. Trofimov, V.S. Posedko, E.F. Ostretsov, V.I. Tsvirko, L.N. Survilo, N.N. Marus // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2013. — Т. 16, № 2. — С. 194-197. — Бібліогр.: 2 назв. — англ. |
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nasplib_isofts_kiev_ua-123456789-1176912025-02-09T17:10:57Z White LED modules encapsulation features Trofimov, Yu.V. Posedko, V.S. Ostretsov, E.F. Tsvirko, V.I. Survilo, L.N. Marus, N.N. The behaviour and causes of changes for correlated color temperature (CCT) and radiant spectral power in white LED modules of different design at their encapsulation by optical compounds are investigated. It is shown that CCT of original white LED radiation can both decrease and increase after polymeric covering application. The ССT variation direction is determined mainly by primary lens presence on LED. The variation value of color parameters of white LED modules is determined by created optical surface curvature and spectral characteristics of deposited polymer. 2013 Article White LED modules encapsulation features / Yu.V. Trofimov, V.S. Posedko, E.F. Ostretsov, V.I. Tsvirko, L.N. Survilo, N.N. Marus // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2013. — Т. 16, № 2. — С. 194-197. — Бібліогр.: 2 назв. — англ. 1560-8034 PACS 85.60.Jb https://nasplib.isofts.kiev.ua/handle/123456789/117691 en Semiconductor Physics Quantum Electronics & Optoelectronics application/pdf Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
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The behaviour and causes of changes for correlated color temperature (CCT)
and radiant spectral power in white LED modules of different design at their
encapsulation by optical compounds are investigated. It is shown that CCT of original
white LED radiation can both decrease and increase after polymeric covering application.
The ССT variation direction is determined mainly by primary lens presence on LED. The
variation value of color parameters of white LED modules is determined by created
optical surface curvature and spectral characteristics of deposited polymer. |
| format |
Article |
| author |
Trofimov, Yu.V. Posedko, V.S. Ostretsov, E.F. Tsvirko, V.I. Survilo, L.N. Marus, N.N. |
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Trofimov, Yu.V. Posedko, V.S. Ostretsov, E.F. Tsvirko, V.I. Survilo, L.N. Marus, N.N. White LED modules encapsulation features Semiconductor Physics Quantum Electronics & Optoelectronics |
| author_facet |
Trofimov, Yu.V. Posedko, V.S. Ostretsov, E.F. Tsvirko, V.I. Survilo, L.N. Marus, N.N. |
| author_sort |
Trofimov, Yu.V. |
| title |
White LED modules encapsulation features |
| title_short |
White LED modules encapsulation features |
| title_full |
White LED modules encapsulation features |
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White LED modules encapsulation features |
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White LED modules encapsulation features |
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white led modules encapsulation features |
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
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2013 |
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https://nasplib.isofts.kiev.ua/handle/123456789/117691 |
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White LED modules encapsulation features / Yu.V. Trofimov, V.S. Posedko, E.F. Ostretsov, V.I. Tsvirko, L.N. Survilo, N.N. Marus // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2013. — Т. 16, № 2. — С. 194-197. — Бібліогр.: 2 назв. — англ. |
| series |
Semiconductor Physics Quantum Electronics & Optoelectronics |
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AT trofimovyuv whiteledmodulesencapsulationfeatures AT posedkovs whiteledmodulesencapsulationfeatures AT ostretsovef whiteledmodulesencapsulationfeatures AT tsvirkovi whiteledmodulesencapsulationfeatures AT surviloln whiteledmodulesencapsulationfeatures AT marusnn whiteledmodulesencapsulationfeatures |
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2025-11-28T10:53:10Z |
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Semiconductor Physics, Quantum Electronics & Optoelectronics, 2013. V. 16, N 2. P. 194-197.
© 2013, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
194
PACS 85.60.Jb
White LED modules encapsulation features
Yu.V. Trofimov, V.S. Posedko, E.F. Ostretsov, V.I. Tsvirko, L.N. Survilo, N.N. Marus
Center of LED and Optoelectronic Technologies of National Academy of Sciences of Belarus,
Logoisky trakt 22, 220090 Minsk, Belarus
Phone/fax: +375(017)-281-13-62, e-mail: senso@inel.bas-net.by
Abstract. The behaviour and causes of changes for correlated color temperature (CCT)
and radiant spectral power in white LED modules of different design at their
encapsulation by optical compounds are investigated. It is shown that CCT of original
white LED radiation can both decrease and increase after polymeric covering application.
The ССT variation direction is determined mainly by primary lens presence on LED. The
variation value of color parameters of white LED modules is determined by created
optical surface curvature and spectral characteristics of deposited polymer.
Keywords: LED, encapsulation, color temperature.
Manuscript received 11.12.12; revised version received 24.01.13; accepted for
publication 19.03.13; published online 25.06.13.
1. Introduction
One way of LED modules protection against negative
environment impact and vandalism is their encapsulation
by special optically transparent compounds [1]. In
practice, it provides the effective moisture protection,
vibration and shock resistance of LED modules, allows
to exclude the air spaces between LED module and
protective glass, to reduce the losses at optical medium
boundaries, as well as to reject the protective glass in
certain cases.
However, the compound application directly on
LED produces inevitable changes of optical parameters
of resultant light radiation [2]. First, applied polymer
layer changes the configuration of LED optical system
and radiation angular distribution. Second, the polymer
serves as an additional light filter reducing the total light
flux and changing colour parameters in accordance with
the spectral transmission characteristic of used polymer.
2. Experimental results and discussion
LED and polymer compound light characteristics were
measured with scanning spectrophotometer SPECTRO 320
and goniophotometer LEDGON 100 (Instrument Systems).
All measured LEDs were based on white luminophor.
Under white LED encapsulation, the change of
correlated color temperature and other colour parameters
is occurred. The radiation chromaticity changing the
mechanism of white luminophor LEDs is provided by
radiation redistribution between blue and yellow-green
spectral regions (Fig. 1).
So, filling of LED without primary lens, i.e. with
flat or slightly concaved optical surface, results in
formation of the convex or flat surface. It, in its turn,
increases the part of output light radiation in blue
spectral region B and decreases the luminophor-
transformed part of radiation Y. As a result, ССТ of the
total light flux W is shifted to cooler region.
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2013. V. 16, N 2. P. 194-197.
© 2013, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
195
The radiant spectral power change of NS6W083A
(Nichia) LED after silicon lens formation is shown in
Fig. 2.
Essential LED optical surface curvature change at
the lens-air boundary results in ССТ averaged value
growth from 5240 up to 9060 K.
Layer-to-layer application of compound with
uniform transmission characteristic in white LED
radiation range on LED without lens results in a
monotonous increase of the blue component in the total
light flux and respective ССТ growth.
The radiant spectral power density change and
ССТ for NS6W083A LED with layer-to-layer acrylic
compound PLASTIK (Cramolin, Germany) application
are shown in Fig. 3.
Fig. 2. The NS6W083A LED radiant spectral power
dependence on the wavelength before and after silicon lens
formation.
Compound is applied by pulverization and gets air-
dried at room temperature. The thickness of single layer
is equal to 25…30 µm. The compound uniform
transmission characteristic practically excluded its
influence on colour parameters as an additional light
filter.
With layer-to-layer application of polyurethane
compound URETHANE (Cramolin, Germany) with the
non-uniform transmission characteristic, its influence as
additional light filter is evident only for two layers, not
essentially changing the optical system curvature
(Fig. 4b).
This becomes apparent in initial decrease of the
blue component fraction in the total light flux and, as a
consequence, ССТ. At further layers application, when
the compound – air boundary curvature is changed from
concave to flat or even convex form, the blue component
fraction in the total light flux and ССТ are increased
again.
It is confirmed in practice at LED lamp production
when LED without primary lens has a contact with
transparent compound. The light color is turned into cool
white, and its temperature is changed, for example from
5000 up to 8000 K.
At compound application of LEDs with primary
lens, another dynamics of chromaticity changing is
observed. In this case, the optical system surface
curvature is changed from convex to flat or even to
concave form (Fig. 1). The blue component fraction in
the total light flux is decreased, and ССТ is shifted to a
warmer region.
The dependences of radiant spectral power
density change for cool white (NFSW036L, Nichia) (а)
and warm white (NFSL036L, Nichia) (b) LEDs with
Fig. 1. Simplified comparative model of radiation coupling for LED with and without lens before (a) and after (b) compound
application.
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2013. V. 16, N 2. P. 194-197.
© 2013, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
196
acrylic compound encapsulation on wavelength are
shown in Fig. 5. The corresponding ССТ values are
indicated inside the figure. The filling is prolonged until
flat surface adjoining with air is formed.
a
b
Fig. 3. The radiant spectral power density change (a) and
ССТ (b) for NS6W083A LED with layer-to-layer applied
acrylic compound.
a
b
Fig. 4. The radiant spectral power density (a) and ССТ (b)
change for NS6W083A LED with layer-to-layer applied
polyurethane compound.
a
b
Fig. 5. The dependence of radiant spectral power density
change for cool white (а) and warm white (b) LEDs on the
wavelength before and after acrylic coating formation.
Fig. 6. ССТ angular distribution for cool white NFSW036L
and warm white NFSL036L LEDs before and after acrylic
coating formation.
The correlated color temperature for cool white
LEDs (CCT = 12483 K) was decreased by 27%, and for
warm white LEDs (CCT = 3106 K) – by 7%,
respectively. As seen from Fig. 6, ССТ angular
distribution becomes more uniform.
The carried out investigations are shown that
compound type does not affect much on both CCT
change and CCT angular distribution.
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2013. V. 16, N 2. P. 194-197.
© 2013, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
197
3. Conclusion
At white LED modules encapsulation by compound
application, the significant ССТ change takes place. The
basic reason for this is the change of LED optical system
curvature at the boundary with air.
The modification tendency is defined by the
primary lens presence or absence: when it is present, the
ССT is decreased, when it is absent, the ССT is
enhanced.
The possible ways for avoiding the changing of
color parameters are as follows:
– sharing LEDs with and without lens for ССТ
cancellation after filling;
– encapsulation technology development with a
small air gaps under LED formation.
References
1. A. Petrov, Let be light! Modern LED lighting.
Trends. Objectives. Solutions // Sovremennaya
svetotekhnika, 2(09), p. 43-46 (2011), in Russian.
2. Yu.V. Trofimov, V.S. Posedko, E.F. Ostretsov,
V.I. Tsvirko, L.N. Survilo, Influence research of
waterproof coatings on lighting parameters of
LEDs // 8-th Belarusian-Russian Workshop
“Semiconductor lasers and systems”, р. 206-209
(2011).
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