Application Note

Light Emitting Diode

Heat Dissipation Performance of the Nichia
NVSxx19C Series LEDs at the Module Level

Table of contents
1. Overview ............................................................................... 2
2. Difference in the Electrode Configurations ........................... 2
3. Evaluation of the Heat Dissipation Capabilities .................... 3
4. Summary................................................................................ 7

The Nichia part numbers NVSx119C and NVSx219C within this document are merely Nichia’spart numbers for those Nichia products and are not related nor bear resemblance to any othercompany’s product that might bear a trademark.

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Application Note
1. Overview

Nichia presumes that the NVSxx19C series LEDs will be used for applications that are operated athigh currents. When the LED is operated at a high current, it produces a large amount of heat; if
this causes the LED temperature (TJ) to increase, it may cause issues (e.g. reduction in the luminous
flux according to the LED temperature characteristics). Ensure that when designing the PCB andthe luminaire, there are no issues with the thermal designs for the chosen application.
3.5
2.9 0.4

3.5
2.9

3.5

3.5

This application note provides the results of the evaluation of the heat dissipation capabilities of theNVSxx19C series LEDs at the module level with an emphasis on the difference in the LED
electrode configuration between the NVSx219C and NVSx119C LEDs.

2. Difference in the Electrode Configurations
Cathode Mark

Cathode Mark

22As mentioned in the Overview, there is a difference in the electrode configuration between thesemodels: the NVSx219C LEDs have a die heat sink that is electrically isolated from both the anodeelectrode and cathode electrode and the NVSx119C LEDs do not have a die heat sink. This is theonly difference that exists between these models, the other parts/materials used are the same.
Refer to Figure 1 for the common appearance of the NVSxx19C series LEDs, and Figures 2 and 3
for the electrode configurations of the NVSx119C and NVSx219C LEDs.
3.2
0.5

3.2

1.3

0.5

3.2

0.45

3.2
2.4

Light Emitting Diode

Nichia’s NVSxx19C series LEDs offer two different types of electrode designs: LEDs with one
cathode and one anode electrode (i.e. NVSx119C) and LEDs with an electrically isolated die heatsink in addition to these two electrodes (i.e. NVSx219C). The thermal resistances (RθJS) from theLED die to the TS measurement point are the same for both of those types. However, the LED typechosen for the design of the module (i.e. electrodes/heat sink pad on the back of the LED package)
and/or the soldering pad pattern of the printed circuit board (PCB) may cause the thermal path tochange causing a difference in the heat dissipation.

CathodeAnodeダイヒートシンク
Die Heat
Heat Sink
SinkDie

Figure 1. Appearance of theNVSxx19C series LEDs

Figure 2. Electrode Configurationof the NVSx219C LEDs

CathodeAnodeFigure 3. Electrode Configurationof the NVSx119C LEDs

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Application Note
When the LED is operated, it produces heat at the LED die. This heat is conducted to the LED
ceramic substrate and then to the PCB (i.e. the copper layer) via the electrodes, spreading over thePCB. For the NVSx219C LEDs, heat is conducted to the PCB (i.e. the copper layer) via the cathodeelectrode, die heat sink, and anode electrode; for the NVSx119C LEDs, it is conducted via thecathode and anode electrodes.
Refer to Figure 4 for the NVSx219C LEDs’ thermal path from the LED die to the PCB and Figure
5 for the NVSx119C LEDs’ thermal path.
LED Chip
Ceramic Substrate

Flow of Heat

Copper Layer

Light Emitting DiodeTS Measurement
Point

Solder Mask

LED Chip
Ceramic Substrate

Flow of HeatCopper Layer

TS Measurement
PointPCB

Figure 4. Thermal Path of the NVSx219C LEDs

Solder Mask

PCB

Figure 5. Thermal Path of the NVSx119C LEDs

3. Evaluation of the Heat Dissipation Capabilities
3.1 Evaluation by PCB Material and Heat Sink Size
3.1.1 Evaluation Method/Conditions
To evaluate the heat dissipation at the module level by PCB copper layer/LED electrode designs,
Nichia has designed PCB layouts/modules specifically for this evaluation, each with 24 LEDs ofeither NVSx119C LEDs or NVSx219C LEDs. The details of the evaluation methods/conditions areas follows:• There is no difference in the specifications (e.g. PCB materials, dimensions) between the PCBs
used for the evaluation, except for the PCB copper layer patterns.
• Two different copper layer patterns (i.e. Pattern 1 and Pattern 2) were used for NVSx219C LEDs
and one copper layer pattern (i.e. Pattern 3) was used for NVSx119C LEDs (See Table 1 for thePCB layout).
• To reproduce typical operating conditions used for actual applications, three different heat sinks(i.e. Rjhs ≈ 1.1°C/W, Rjhs ≈ 0.7°C /W and Rjhs ≈ 0.45°C /W) were used with the aluminum corePCBs.
• The input currents to the test modules (i.e. IF = 700mA, IF = 1200mA, and IF = 1800mA) weredetermined according to the heat dissipation capability of the heat sink being used (See Table 2
for the heat sinks and aluminum core PCBs used).
• Four LEDs were chosen from the 24 LEDs per aluminum core PCB. Once the saturation
temperature had been reached for those four LEDs, they were measured at the TS measurement
point (See Table 1).
• To evaluate the effect of the temperature saturation on the module’s luminous flux (i.e. reductionin the luminous flux), measurements were performed immediately after the LEDs were turnedon and once the saturation temperature at the TS measurement point had been reached.
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Application Note
Table 1. Evaluation Conditions
Part Number

NVSx219C
Pattern 1

Pattern 2

NVSx119C
Pattern 3

Light Emitting Diode

Copper Layer
Pattern

PCB Copper Foil
PatternTS Measurement PointTS Measurement Point

Thermal Grease
How to attach thePCBs
to the heat sinks
PCBSpecifications

Sunhayato Co., Ltd. SCH-301 Approximately 4.0 g (silicone resin)
M4 stainless screws with washers, Tightening torque: 50cN·m
Material: Aluminum
Dimensions: 119mm (L) x 136mm (W) x 1.6mm (T)Copper Layer Thickness: 35μm
Insulation Layer’s Thermal Conductivity: 2.7W/m·K

Table 2. Heat Sink Specifications and Operating Conditions
Heat Sink Thermal
Resistance
Current Conditions
Heat Sink
Dimensions

Rjhs ≈ 1.1°C/W

Rjhs ≈ 0.7°C /WRjhs ≈ 0.45°C /W

700mA
136mm(L)×150mm(W)×40mm(H)

1200mA
133mm(L)×150mm(W)×64mm(H)

1800mA
200mm(L)×250mm(W)×40mm(H)

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Application Note
3.1.2 Evaluation Results
The evaluation verified that when NVSx119C/NVSx219C LEDs were used in a module attached
to a heat sink, the NVSx119C LEDs had a lower temperature at the TS measurement point and asmaller reduction in the luminous flux once the saturation temperature had been reached; this could
lead to the conclusion that the NVSx119C LEDs have a better heat dissipation capability.
In comparison, of the two copper layer patterns used for the NVSx219C LEDs (i.e. Pattern 1 andPattern 2), the LEDs soldered to Copper Layer Patten 2 showed better heat dissipation. Refer toTable 3 for more details on the evaluation results.
Table 3. Evaluation Results: Heat Dissipation Capability by Operating Conditions(i.e. Copper Layer Patten, Current [IF], Heat Sink Size)

Heat Sink

Luminous Flux Reduction Rate

Temperature at the TS measurement point once

Measured from TJ ≈ 25°C (Initial) to TJ

the saturation temperature has been reachedin saturation mode Sample size = 1 PCB

Sample Size = Avg. TS measurement points of
4 LEDs per PCB

IF=1800mA
Rjhs ≈
0.45°C/W
Size
200mm(L)
250mm(W)
40mm(H)

9085807570

Measurement Condition
25Relative Lumen Decrease Rate[a.u.]

Copper Layer Pattern 1 (NVSx219C)
Copper Layer Pattern 2 (NVSx219C)
Copper Layer Pattern 3 (NVSx119C)

65

Measurement Condition
9585807570807510Measurement Condition

TA=25℃, 1200mA/1hr, Rjhs≈0.7℃/W
Copper Layer Pattern 1 (NVSx219C)
Copper Layer Pattern 2 (NVSx219C)
Copper Layer Pattern 3 (NVSx119C)

2015

105Measurement Condition

85

15256590

Copper Layer Pattern 1 (NVSx219C)
Copper Layer Pattern 2 (NVSx219C)
Copper Layer Pattern 3 (NVSx119C)

20

TA=25℃, 1200mA/1hr, Rjhs≈0.7℃/W
Copper Layer Pattern 1 (NVSx219C)
Copper Layer Pattern 2 (NVSx219C)
Copper Layer Pattern 3 (NVSx119C)

90

95

TA=25℃, 700mA/1hr, Rjhs≈1.1℃/W

5Relative Lumen Decrease Rate[a.u.]Size
133mm(L)
150mm(W)
64mm(H)

TA=25℃, 700mA/1hr, Rjhs≈1.1℃/W

TA=25℃, 1800mA/1hr, Rjhs≈0.45℃/W
Copper Layer Pattern 1 (NVSx219C)
Copper Layer Pattern 2 (NVSx219C)
Copper Layer Pattern 3 (NVSx119C)

Measurement Condition
25

Relative Lumen Decrease Rate[a.u.]

IF=1200mA
Rjhs ≈
0.7°C/W

Solder Temperature[℃]

Size
136mm(L)
150mm(W)
40mm(H)

Measurement Condition
95

Solder Temperature[℃]

IF=700mA
Rjhs ≈
1.1°C/W

Solder Temperature[℃]Light Emitting Diode

TS Temperature

TA=25℃, 1800mA/1hr, Rjhs≈0.45℃/W
Copper Layer Pattern 1 (NVSx219C)
Copper Layer Pattern 2 (NVSx219C)
Copper Layer Pattern 3 (NVSx119C)

20151070
565

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Application Note
3.2 Heat Dissipation by Operating Current Value
3.2.1 Evaluation Method/Conditions
The evaluation in section 3.1.1 was designed to simulate actual operating conditions: if the heatsink is large enough, then it will be possible to use a large amount of current for the module. For
this purpose, three different sizes of heat sinks were used and the current to the module was set
according to the heat dissipation capability of the heat sink used with the module.

Light Emitting DiodeIn this section, the application note evaluates the heat dissipation of NVSx219C and NVSx119C
due to changes in the operating current when the module size is the same. The evaluation procedure
is detailed as follows:• The same three aluminum core PCBs were used as in the evaluation from section 3.1.1 (i.e. twocopper layer patterns for NVSx219C LEDs and one copper layer pattern for NVSx119C LEDs)(See Table 1).
• Only one of the heat sinks used from the evaluation in section 3.1.1 was used: the heat sink witha thermal resistance Rjhs ≈ 0.7°C/W (See Table 2).
• Three predetermined input current values were used: IF=1200mA, IF=1500mA and IF=1800mA.
• Four LEDs were chosen from the 24 LEDs per aluminum core PCB. Once the saturation
temperature had been reached for those four LEDs, they were measured at the TS measurement
point (See Table 1).
• To evaluate the effect of the temperature saturation on the module’s luminous flux (i.e. reductionin the luminous flux), measurements were performed immediately after the LEDs were turnedon and once the saturation temperature at the TS measurement point had been reached.
3.2.2 Evaluation Results
The evaluation verified that when NVSx119C/NVSx219C LEDs were used in a module attached
to a heat sink, the NVSx119C LEDs had a lower temperature at the TS measurement point and asmaller reduction in the luminous flux once the saturation temperature had been reached; this leads
to the conclusion that the NVSx119C LEDs could have a better heat dissipation capability.
In comparison, of the two copper layer patterns used for the NVSx219C LEDs (i.e. Pattern 1 andPattern 2), the LEDs soldered to Copper Layer Patten 2 showed better heat dissipation. Refer toTable 4 for more details on the evaluation results.

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Application Note
Table 4. Evaluation Results: Heat Dissipation Capability by Operating Conditions(i.e. Copper Layer Patten and Current [IF])TS Temperature

Luminous Flux Reduction Rate

Temperature at the TS measurement point once theMeasured from TJ ≈ 25°C (Initial) to TJ in saturation modesaturation temperature has been reached Sample Size =Sample size = 1 PCB

Avg. TS measurement points of 4 LEDs per PCB
Measurement Condition：TA=25℃,Rjhs≈0.7℃/W

25120

Copper Layer Pattern 1 (NVSx219C)
Copper Layer Pattern 2 (NVSx219C)
Copper Layer Pattern 3 (NVSx119C)

Relative Lumen Decrease Rate[a.u.]

Solder Temperature[℃]Light Emitting Diode

130

110

10090

Measurement Condition：TA=25℃, Rjhs≈0.7℃/W
Copper Layer Pattern 1 (NVSx219C)
Copper Layer Pattern 2 (NVSx219C)
Copper Layer Pattern 3 (NVSx119C)

20

15

1080
IIF=1200mA
F=1200mA

IIF=1500mA
F=1500mA

IIF=1800mA
F=1800mA

5IF1200mA=1200mA

IF=1500mA
1500mA

IF1800mA=1800mA

4. Summary
Under any of the evaluation conditions above, Nichia has verified that NVSx119C LEDs had
better heat dissipation on average than NVSx219C LEDs. One of the possible reasons for theseresults is that the NVSx119C LEDs have electrodes that are larger in area than the NVSx219C
LEDs allowing for better heat conduction from the LED to the PCB. Ensure that if NVSx219C
LEDs are used for the chosen application, there are no issues with the copper layer design (i.e. poor
heat dissipation).
In either case, it is important to ensure that the area of the copper layer is sufficiently large; however,since the NVSx119C LEDs have electrodes that are larger in area than the NVSx219C LEDs, evenif the operating conditions/environment where the LED is operated do not allow the LED to
sufficiently dissipate the heat, they will be able to offer better heat dissipation than the NVSx219C
LEDs. Additionally, the NVSx119C LEDs have a simple design for the electrodes (i.e. only twoelectrodes: anode and cathode) that is an advantage over LEDs with anode/cathode electrodes anda die heat sink (e.g. easy to determine the copper layer pattern, size, position, etc.).
Note that the evaluation methods/conditions provided in this application note are examples and thedata may vary depending on the LED model and/or the chosen operating conditions/environment;
the contents of this document should be used for reference purposes only.

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Application Note

Light Emitting DiodeDisclaimer
This application note is a controlled document of Nichia Corporation (Nichia) published to provide
technical information/data for reference purposes only. By using this application note, the user agrees
to the following: This application note has been prepared solely for reference on the subject matters incorporated
within it and Nichia makes no guarantee that customers will see the same results for their chosenapplication.
 The information/data contained herein are only typical examples of performances and/orapplications for the product. Nichia does not provide any guarantees or grant any license underor immunity from any intellectual property rights or other rights held by Nichia or third parties.
 Nichia makes no representation or warranty, express or implied, as to the accuracy, completenessor usefulness of any information contained herein. In addition, Nichia shall not be liable for any
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