Protective Materials Over LEDs - Dow

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Protective Materials Over LEDs –and Associated Optical Effects

Presented by Jake Steinbrecher • Dow Performance SiliconesStrategies In Light, February 13, 2018

Why Can’t We Just Have “White” Light?

2

Paul AndreauPhoto: ® 2008 Artists Rights Society (ARS), New York / ADAGP, Paris

Benefits of Protective Materials - Conformal Coatings

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4000K test part with DOWSIL™ 1-2577 Low VOC Conformal Coating

Silicone, Acrylic, Urethane

• Protect against environmental ingress, corrosion, etc.

• Thin layer provides little impact on light quality

Protective Materials – Conformal Coatings

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4000K Test Part, No Material4000K Test Part with DOWSIL™ 1-2577

Low VOC Conformal Coating

Benefits of Protective Materials - Encapsulants

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4000K test part with DOWSIL™ EI-1184 Encapsulant

• Protect against environmental ingress, corrosion, etc.

• Impact protection

Silicone, Acrylic, Urethane

Protective Materials - Encapsulants

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4000K Test Part, No Material4000K Test Part with DOWSIL™

EI-1184 Optical Encapsulant

Benefits of Protective Materials - Molded Lens

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4000K test part with DOWSIL™ MS-1002 Moldable Silicone

Silicone, PC, PMMA

• Protect against environmental ingress (when sealed)

• Impact protection• Little impact on light quality

Protective Materials - Molded Lens

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4000K Test Part, No Material4000K Test Part with DOWSIL™

MS-1002 Moldable Silicone

Lens design courtesy of:

Disadvantages of Protective Materials

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Effects on Light Quality• Color shift• Lumen depreciation

Cost

Test parts, using DOWSIL™ 1-2577 Low VOC Conformal Coating, DOWSIL™ EI-1184 Encapsulant , and DOWSIL™ MS-1002 Moldable Silicone

4000K3000K

5000K HOK International, Photo: Farid Khayrulin

Protective Materials – Effects on Light QualityTypical LED Package

Blue rays from the LED chip will:1) Go to air through silicone encapsulant material (RI 1.53)2) Hit phosphor particles and emit rays with other spectrum (e.g. yellow, red)

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Phosphor Silicone Encapsulant(RI 1.53)

Reflector CupLED Chip

1

2

Air (RI 1.00)

Protective Materials – Effects on Light QualityTypical LED Package

Blue rays from the LED chip may:3. Reflect at the interface of silicone encapsulant and air, due to Total Internal

Reflection (TIR). In this example, the critical angle θ1 is equal to sin-1 (1/1.53), which is 40.8 degrees. Any rays that hit this interface with an angle bigger than 40.8 degrees will be reflected, and may interact further with phosphor particles.

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Phosphor Silicone Encapsulant(RI 1.53)


1

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Air (RI 1.00)

Protective Materials – Effects on Light QualityTypical LED Package + Protective Material(s)

Blue rays from the LED chip may:4. Have a better chance of escaping at the interface of silicone encapsulant and

protective material due to TIR. In this example, the critical angle θ1 is equal to sin-1

(1.41/1.53), which is 67 degrees. This leads to more blue light rays escaping and less interaction with phosphor, leading to increased color temperature.

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PhosphorSilicone Encapsulant(RI 1.53)


1

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Air (RI 1.00) Silicone Protective Material (RI ~1.41)

Protective Materials –DOWSIL™ 1-2577 Low VOC Conformal Coating

133000K, 4000K , and 5000K test parts with

DOWSIL™ 1-2577 Low VOC Conformal Coating

2000

2500

3000

3500

4000

4500

5000

5500

3000K 4000K 5000K

Cor

rela

ted

Col

or T

empe

ratu

re (º

K)

LED Linear Type

DOWSIL™ 1-2577 Low VOC Conformal Coating, Effects on Correlated Color Temperature

BareCoated

0.00

20.00

40.00

60.00

80.00

100.00

120.00

140.00

3000K 4000K 5000K

Lum

inou

s Fl

ux (l

umen

s)

LED Linear Type

DOWSIL™ 1-2577 Low VOC Conformal Coating, Effects on Luminous Flux

BareCoated

Protective Materials –DOWSIL™ EI-1184 Optical Encapsulant

143000K, 4000K, and 5000K test parts with DOWSIL™ EI-1184 Optical Encapsulant

0.0020.0040.0060.0080.00

100.00120.00140.00

3000K 4000K 5000K

Lum

inou

s Fl

ux (l

umen

s)

LED Linear Type

DOWSIL™ EI-1184 EncapsulantEffects on Luminous Flux

Bare

Encapsulant

0.00

20.00

40.00

60.00

80.00

100.00

120.00

140.00

3000K 4000K 5000K

Lum

inou

s Fl

ux (l

umen

s)

LED Linear Type

DOWSIL™ EI-1184 EncapsulantEffects on Luminous Flux

Bare

Encapsulant

2000

3000

4000

5000

6000

7000

8000

9000

3000K 4000K 5000KCor

rela

ted

Col

or T

empe

ratu

re (º

K)

LED Linear Type

DOWSIL™ EI-1184 EncapsulantEffects on Correlated Color Temperature

Bare

Encapsulant

Protective Materials –DOWSIL™ MS-1002 Moldable Silicone

153000K, 4000K, and 5000K test parts with DOWSIL™ MS-1002 Moldable Silicone

0.00

20.00

40.00

60.00

80.00

100.00

120.00

140.00

3000K 4000K 5000K

Lum

inou

s Fl

ux (l

umen

s)

LED Linear Type

DOWSIL™ MS-1002 Moldable SiliconeEffects on Luminous Flux

Bare

Lens

2000250030003500400045005000550060006500

3000K 4000K 5000KCor

rela

ted

Col

or T

empe

ratu

re (º

K)

LED Linear Type

DOWSIL™ MS-1002 Moldable SiliconeEffects on Correlated Color Temperature

Bare

Lens

DOWSIL™ Protective Materials – Effects at 3000K

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0.00

20.00

40.00

60.00

80.00

100.00

120.00

140.00

Bare DOWSIL™ 1-2577 Low VOC Conformal Coating

DOWSIL™ EI-1184 Encapsulant

DOWSIL™ MS-1002 Moldable Silicone

Lum

inou

s Fl

ux (l

umen

s)

Luminous Flux


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0.00

500.00

1000.00

1500.00

2000.00

2500.00

3000.00

3500.00

4000.00

4500.00




Cor

rela

ted

Col

or T

empe

ratu

re (º

K)

Correlated Color Temperature


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0.00E+00

5.00E-04

1.00E-03

1.50E-03

2.00E-03

2.50E-03

3.00E-03

350 450 550 650 750 850

Spec

tral

Flux

Wavelength (nm)

Spectral Flux

Bare





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0.00

20.00

40.00

60.00

80.00

100.00

120.00

140.00




Lum

inou

s Fl

ux (l

umen

s)

Luminous Flux


20

0.00

1000.00

2000.00

3000.00

4000.00

5000.00

6000.00




Cor

rela

ted

Col

or T

empe

ratu

re (º

K)



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0.00E+00

5.00E-04

1.00E-03

1.50E-03

2.00E-03

2.50E-03

3.00E-03

350 450 550 650 750 850

Spec

tral

Flux

Wavelength (nm)

Spectral Flux

Bare





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0.00

20.00

40.00

60.00

80.00

100.00

120.00

140.00




Lum

inou

s Fl

ux (l

umen

s)

Luminous Flux


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0.00

1000.00

2000.00

3000.00

4000.00

5000.00

6000.00

7000.00

8000.00

9000.00




Cor

rela

ted

Col

or T

empe

ratu

re (º

K)



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0.00E+00

5.00E-04

1.00E-03

1.50E-03

2.00E-03

2.50E-03

3.00E-03

3.50E-03

4.00E-03

4.50E-03

350 450 550 650 750 850

Spec

tral

Flux

Wavelength (nm)

Spectral Flux

Bare

DOWSIL™ 1-2577 Low VOC Conformal CoatingDOWSIL™ EI-1184 Encapsulant


DOWSIL™ Protective Materials

DOWSIL™ 1-2577 Low VOC Conformal Coating• Minimally effects Luminous Flux and CCT

― But, provides the least amount of protection above bare components

DOWSIL™ EI-1184 Optical Encapsulant• Provides significant protection above

bare components ― But, reduces Luminous Flux and increases CCT

DOWSIL™ MS-1002 Moldable Silicone• Slightly increases Luminous Flux and CCT

― And, provides significant protection above bare components

25Ingarden & Ewy Architekci; Arata Isozaki & Associates Photo: Wojciech Wandzel

Protective Materials Over LEDs - Dow

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