Application Note

Light Emitting DiodeHow Sulfur Corrosion of LEDs Occurs
and How to Avoid it

Table of contents
1. Overview ................................................................... 2
2. Verification of the Corrosion Test .............................. 4
3. LED Precautions for Corrosive Gas ........................ 13
4. Summary and References ........................................ 14

The Nichia part numbers NS6W183A, NFSW757D and NS2W757A-V1 within this document are
merely Nichia’s part numbers for those Nichia products and are not related nor bear resemblance toany other company’s product that might bear a trademark.

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Application Note
1. Overview
This document provides further explanation pertaining to the Nichia’s specifications (see Cautions,(1) Storage), for how corrosive gases (particularly, the sulfur content of these gases) can affect thecharacteristics and reliability of the LEDs and detailed cautions and suggestions on how tostore/use the LEDs.

After being exposed to a corrosive
environment containing sulfur

Light Emitting Diode

Before being exposed to a corrosive
environment containing sulfur

1.1 How the Lead Frames Discolor/Corrode
Most Nichia LEDs have internal lead frames that are made of silver-plated copper alloy. Silver is
excellent at both reflecting light and conducting electricity; however, if silver is exposed to a
corrosive gas (e.g. hydrogen sulfide, etc.), then it can react with the sulfur content and may discolor.
This is due to a chemical reaction between silver and sulfur (i.e. 2Ag + S → Ag2S) and the resulting
layer of silver sulfide on the surface. The level of discoloration can vary from yellow, then brown to
black depending on the thickness of this layer.
S

SS

Sulfur content
S

S

S
S

Lead frame

S
S

Encapsulating resin

S

S

S

S

Silver sulfide layer

S
S

Chemical
reaction

Figure 1. Schematic diagram of how sulfur causes a silver-plated lead frame to corrode (discolor)

1.2 Potential Issues Caused by Corroded Lead Frames
1) Reduction in the Luminous Intensity/Flux
If the lead frame discolors, the light that is reflected from the lead frame and extracted from thepackage is reduced; this causes the luminous intensity/flux to decrease (See Figure 2).
2) Color Shift
In order to produce white light, Nichia LEDs use a combination of phosphor with die that emits
blue light: when the blue light from the die excites the phosphor it fluoresces yellow light; asboth blue light and yellow light are combined together within the LED package, the light fromthe LED appears white, depending on the spectrum distribution. While most of the blue lightexits the LED after turning yellow through the phosphor, some of the blue light instead strikes
the lead frame surface first; if the lead frame is discolored, more of the yellow light may be
absorbed by the lead frame; this can cause the spectrum distribution to change and the color of
the light to shift to the blue region (See Figure 3).
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Application Note

Corrosion*When the lead frame becomes discolored, the amount of reflected light at the lead frame surface decreases.
Figure 2. How the Luminous Intensity/Flux Decreases

Light Emitting Diode

Corrosion*When the lead frame becomes discolored, the amount of reflected light at the lead frame surface decreases
and it changes the spectrum distribution of the LED.
Figure 3. How the Color Shift Occurs

3) Wire Breakage/Open Circuit
If corrosion extends under the surface of the lead frame, it can cause the bonds between the wires
and the lead frame to become easily damaged; this may cause the LED not to illuminate.
Wire

Wire breakage

Lead frame

Figure 4. How Wire Breakage occurs due to Corrosion

1.3 LED Failure Modes As a Result of Sulfide Corrosion
Based on both Nichia’s customer return history and test results, if the LEDs are used in indoor
environments, Nichia considers sulfide corrosion of LEDs to be due to the following reasons:1) In cases where corrosion occurs in general indoor environments(i.e. the concentration of corrosive gas is low)
It can depend on the concentration level of sulfur-containing gases; however, both luminous flux
reduction and color shift progress over time; after a long period of time has elapsed, LEDs canfail as an open circuit.

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Application Note2) In cases where either sulfur-containing materials/parts are used in the same product as the LEDsor many materials/parts containing corrosive substances are placed near the LEDs
(i.e. the concentration of corrosive gases is high)
These LEDs are exposed to high concentrations of corrosive gases and it can increase thepossibility that these LEDs will fail as an open circuit in a short period of time. For the details
about the differences in both the chemical composition and concentration of corrosive gas, see
Section 2.2.1.
1.4 Sources and Items that Release/Contain Corrosive Gas

Light Emitting Diode

Normally, a small amount of sulfur can be found in the general environment (i.e. the air). The
following are examples of where or when corrosive gases can be generated and items containing
sulfur.
- Sources that generate corrosive gases:
Diesel-powered cars, human waste treatment plants, livestock barns, kraft process, starch
factories, manufacturing/combustion facilities at plants (e.g. thermal power stations, petroleum
refineries, steel mills, workplace boilers, etc.), sulfur production, metalworking/smelting, hotsprings, etc.
- Items containing sulfur:
Cardboards, rubber products (e.g. rubber bands), rubber-based adhesives, moisturizers, ointments,
cosmetics, surface-active agents (e.g. detergents), etc.

2. Verification of the Corrosion Test
2.1 Corrosivity Categories of Indoor Atmospheres Defined in ISO 11844 and General Indoor
Environments
In order to determine the test conditions for Nichia’s corrosion test, Nichia performed aninvestigation on the relationship between the corrosivity categories of indoor atmospheres definedin the international standard specification ISO 11844 and field tests of general indoor environments
near Nichia facilities.
2.1.1 Corrosivity Categories of Indoor Atmospheres Detailed in ISO 11844-1
ISO 11844-1 classifies the corrosion that develops in general indoor atmospheres (see 1.3 1) for
examples) as shown in Table 1. The corrosivity categories for the ISO standard are based on
measurements of the corrosive effect on standard specimens of four reference metals (i.e. carbon
steel, zinc, copper and silver).
Since it is generally considered that silver corrosion can proceed lineally with time in actual indoor
atmospheres, in order to determine the corrosivity category of an indoor atmosphere, Nichia has
used silver plates as the standard samples for this evaluation.

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Application Note
Table 1. Description of typical environments related to the estimation of indoor corrosivity categories
with the rate of mass increase (i.e. silver) according to ISO 11844-1 1)
Corrosivity category

IC1

Light Emitting Diode

IC2

Very lowindoorLow
indoorIncrease of the mass
for the silver plates
2(mg/m per year)

Heatedspacesr<25
UnheatedspacesHeatedspaces25<r<100
UnheatedspacesHeatedspacesIC3

Mediumindoor100<r<450
UnheatedspacesHeatedspaces
IC4

IC5

High
indoorVeryhighindoorTypical environments

ExamplesHeated spaces with controlled stable relative humidity (<40%)
without risk of condensation, low levels of pollutants, no
specific pollutants.

Computer rooms, Museums
with controlled environment

Unheated spaces with dehumidification, low levels of indoor
pollution, no specific pollutants.

Military stores forequipment

Heated spaces with low relative humidity (<50%) with certain
fluctuation of relative humidity without risk of condensation,
low levels of pollution, without specific pollutants.
Unheated spaces with only temperature and humidity changes,
with no risk of condensation, low levels of pollution without
specific pollutants.
Heated spaces with risk of fluctuation of temperature andhumidity, medium levels of pollution, certain risks for specificpollutants.
Unheated spaces with elevated relative humidity (>50% - 70%)
with periodic fluctuation of relative humidity, without risk ofcondensation, elevated levels of pollution, low risk of specificpollutants.
Heated spaces with fluctuation of humidity and temperature,elevated levels of pollution including specific pollutants.

450<r<1000

Museums,
Control rooms
Storage rooms with low
frequency of temperaturechanges
Switchboards in the powerindustry
Churches in non-polluted
areas,
Outdoor telecommunication
boxes in rural areas
Electrical service rooms inindustrial plants

UnheatedspacesChurches in polluted areas,
Unheated spaces with high relative humidity (>70%) with some
Outdoor boxes forrisk of condensation, medium levels of pollution, possible effecttelecommunication inof specific pollutants.
polluted areas

HeatedspacesElectrical service rooms,
Heated spaces with limited influence of relative humidity, higher Cross-connection rooms inlevels of pollution including specific pollutants like H2S.
industries without efficient
pollution control

1000<r<2500
UnheatedspacesUnheated spaces with high relative humidity and risk forcondensation, medium and higher levels of pollution.

Storage rooms in basements
in polluted areas

2.1.2 Field Investigation Results – Categorization of the Surrounding Environments and Nichia
Facilities
To determine the corrosivity categories of both surrounding environments of Nichia facilities andgeneral outdoor atmospheres, Nichia conducted an investigation by using silver plates to measure
how much the mass increased as a result of corrosion in those atmospheres. For the results of thismeasurement refer to Figure 5 below.
The results of the investigation are as follows:
Nichia facilities- Production rooms/reliability laboratory fall into upper IC1 to lower IC2- Workshop/service entrance fall into middle IC2 to lower IC3- Bicycle parking area/the inside of instrument shelter fall into lower IC3 to middle IC4
General indoor atmospheres- Private residences (e.g. living room and kitchen) fall into lower IC2 to lower IC3- Commercial buildings (e.g. automobile repair shop/garage and clothing shop) fall into lower IC2
to lower IC3
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Application Note
Increase of the Mass for the Silver Plates

Silver plate
placement locations

Increase of the Mass for the Silver Plates (mg/m2 per year)

Light Emitting Diode

2500

IC5
1000
660

Instrument
shelter

IC4

450

IC3
151
104
100

Serviceentrance

Bicycleparking area

131

Kitchen

66

59

Workshop47

Living room
32
25

20

Reliability
laboratory
Production
room 1

113

Automobile repair shop
Garage (4)(4)

Automobile repair shop
Inside of shop (4)

(3)

IC2

38

Clothing shop (5)

28

(2)
(1)

(5)

Production
room 2(Google Earth)

IC1

10

Tatsumi plant
Naruto plant(1)(2)
Nichia facilities

PrivateCommercial
residences (3)buildings
General indoor atmospheres

Corrosivity
category

Instrument shelter

Figure 5. Field Investigation Results

2.2 Development and Evaluation of Accelerated Corrosion Test Conditions
LED corrosion tests that are performed under general environments can take significant time tocomplete; in order to shorten the test duration, accelerated testing is useful.
In order to determine the accelerated test conditions, Nichia has performed corrosion tests by using
different test conditions (e.g. gas composition, temperature, etc.). The test results and the evaluationof the test conditions used are shown in Pages 6 to 11.
2.2.1 Difference in the effect of corrosion due to the gas composition/concentration
Silver can corrode differently depending on the gas composition/concentration. In the case of LEDs,
if they are exposed to corrosive gas containing sulfur, it can cause the LED characteristics tochange and/or the wires to break. Since the effect on the LED can differ depending on the gas
composition/concentration and/or the conditions/environment where the corrosion occurs, thedegree of the change in the characteristics and the occurrence rate of the wire breakage are notdirectly proportional. In other words, if the luminous flux decreases to a certain level as a result of
exposure to corrosive gas, it will not necessarily cause the wires to break.

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Application Note
Nichia’s corrosive test results (see Figure 6 below) shows that the group of test LEDs with a greater
reduction in relative luminous flux (shown in blue) had no LEDs with broken wires (0/15 dice),while the other group with a smaller reduction in relative luminous flux (shown in red) had LEDs
with broken wires (3/9 dice).
Based on these results, when determining the conditions for the accelerated tests, it is important toconsider the conditions/environment where the LEDs are actually used and ensure that appropriate
conditions/environments are used for the tests.

Relative Luminous Flux (%)

Light Emitting Diode

120

Wire breakage:
3 wires out of 9 dice

100
80

×

60

× Wire breakage:
0 wires out of 15 dice40

-Test Condition B
Test LEDs are stored (unpowered) within a sealed
flask (360ml) with a rubber gasket/seal (0.5g).
Storage conditions: TA=100°C

Test Condition A

20

Test Condition B

0

0

100

200
Time (h)300- Test Condition A
Test LEDs are operated within a sealed flask(360ml) with rubber bands (4g).
Operating conditions: TA=65°C, IF=100mA

400

Figure 6. Reduction in Relative Luminous Flux and Occurrence of Wire Breakage in Corrosive Atmospheres

2.2.2 Verification of the Corrosion Test Conditions
When performing the corrosion tests, Nichia used Method 3 as defined in IEC 60068-2-60
Environmental testing – Part 2: Tests – Test Ke: Flowing mixed gas corrosion test. Nichia considers
it appropriate to use Method 3 as the accelerated test method/conditions for the following reasons:- Method 3 uses a mixed gas and will be able to provide a better test environment to obtain finesilver sulfide corrosion crystals than using a single component gas; these crystals are as fine as
crystals that could occur in natural atmospheres.
- Compared to the other three methods, Method 3 uses a higher concentration of hydrogen sulfide
and that can cause the silver corrosion to occur faster.
For the details of the different IEC 60068-2-60 Method test conditions, refer to Table 2.
Table 2. IEC 60068-2-60’s Test Methods and Conditions 2)
MethodGas Composition

Temperature and Humidity Level

1

SO2 0.5ppm + H2S 0.1ppm

25℃ 75%RH

2

H2S 0.01ppm + NO2 0.2ppm + Cl2 0.01ppm

30℃ 70%RH

3

H2S 0.1ppm + NO2 0.2ppm + Cl2 0.02ppm

30℃ 75%RH

4

H2S 0.01ppm + NO2 0.2ppm + Cl2 0.01ppm + SO2 0.2ppm

25℃ 75%RH

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Application Note
2.2.3 Optimizing the Accelerated Test Conditions

Based on this consideration, Nichia conducted an LED corrosion test by using the tentative
accelerated test conditions (see Table 3) to investigate the extent of the corrosion and the additional
weight created by the corrosion formed over the test silver plates.
Table3. Improved Corrosion Test Method

Gas Composition

Temperature and Humidity Level

Test Duration

H2S 2ppm + NO2 4ppm

40℃ 75%RH

240h

2.2.4 Accelerated Corrosion Test Results using the Improved Test Method
Nichia used two LED models (i.e. NFSW757D and NS2W757A-V1) for the improved accelerated
corrosion test (see 2.2.3). During this test the LEDs were not operated.
As the test results show (see Figure 7), the luminous flux of the NS2W757A-V1 LEDs decreased
more than that of the NFSW757D LEDs. Note that the NFSW757D is an improved model of the
NFSW757A-V1 with better gas barrier properties.
110
100

LED
Relative Luminous Flux （%）

Light Emitting Diode

In order to further optimize Method 3 and to develop more severe (accelerated) test conditions,
Nichia reviewed the composition and concentration of the gas used in Method 3 and performed a
corrosion test by: using the same mixed gas as used in Method 3 at the same ratio of the gas
ingredients (i.e. H2S:NO2=1:2) as well as an increased H2S gas concentration of up to 20 times thatof Method 3. The chlorine (Cl2) component in the original Method 3 composition was removed
from this improved Method. For tests that use Method 3, the resulting products of corrosion will
mostly consist of silver sulfide; very little silver chloride will be produced. With the improved
Method, the form of corrosion should remain the same but the speed of corrosion should be further
accelerated. 3)

9080

Test Duration
0h

48h

144h

240h

NFSW757D

70

60

NS2W757A-V1

NFSW757D
NS2W757A-V1

50
40
0

40

80

120

160

200

240

Time （h）

Figure 7. LED Accelerated Corrosion Test Results using the Improved Test Method

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Application Note
While performing the improved accelerated corrosion test on the test LEDs by using silver plates,
Nichia attempted to determine how much the mass of these silver plates increased during this test.
The silver plates were exchanged and measured every 48 hours and the cumulative sum of theincrease in the mass of the silver plates was calculated to obtain the gradient of the line. From thisinvestigation, Nichia confirmed that the mass of the silver plates increased linearly and a corrosive
atmosphere was kept constant within the test chamber. Figure 8 below shows how the mass of thesilver plates increased during this investigation.
20000
18000

Mass Increase (mg/m2)

Light Emitting Diode

16000
14000
12000
10000
8000
6000
4000
2000
0
0

40

80

120

160

200

240

Time (h)Figure 8. Increase in the Mass of the Silver Plates during the Corrosion Test

2.2.5 Estimation of the time to 70% lumen maintenance by using the corrosion test results
Nichia used the mixed gas corrosion test results (see 2.2.4), the corrosivity categories of indoor
atmospheres (ISO 11844 Part 1) and the amount that the mass of the silver plates increased in thefield tests (see 2.1.2) to estimate the time to 70% lumen maintenance.
- NFSW757D: The LEDs are less likely to corrode in atmospheres of each of the five ISO 11844
categories (i.e. IC1 to IC5); the resulting luminous flux reduction due to corrosion will not occur.
- NS2W757A-V1: The LEDs are less likely to corrode in atmospheres up to upper IC2 (potentially,
lower IC3); the resulting luminous flux reduction due to corrosion will rarely occur in these
atmospheres.
Figure 9 and Tables 4 to 5 show the estimated times to 70% lumen maintenance of both LED
models. These estimates do not include deterioration from use or during storage. Ensure that thisdata is only used for reference purposes.

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Application Note110

Equivalent to 10 years of
exposure to upper IC1

Relative Luminous Flux (%)

100
90
80

NS2W757A-V1

Equivalent to 10 years of
exposure to upper IC3

70

For the point at when the luminous flux decreases to
70% of its initial value, the amount that the mass of
silver plates will increase ≈ 13,070 mg/m2

60
50
40
0

Light Emitting Diode

Equivalent to 10 years of
exposure to upper IC2

NFSW757D

2500

5000

7500

10000

12500

Equivalent to 10 years of
exposure to upper IC4：NFSW757D：NS2W757A-V1

15000

17500

20000 Equivalent to 5 years of
exposure to upper IC5

Increase of the Mass for the Silver Plates (mg/m2)

Figure 9. Estimated Lumen Maintenance Curves for NFSW757D and NS2W757A-V1

Table 4. Estimated Time to 70% Lumen Maintenance for Each ISO 11844 Corrosivity Category
ISO 11844
Corrosivity
Categories

Increase of the Mass for
the Silver Plates(mg/m2 per 10 years)

Upper IC1

Calculated Lumen Maintenance by Using
Accelerated Corrosion Test Results(% in 10 years)

Estimated Time to 70% Lumen
Maintenance (Years)

NFSW757D

NS2W757A-V1

NFSW757D

NS2W757A-V1

250

100

99.7

＞100

＞100

Upper IC2

1000

99.9

98.8

＞100

＞100

Upper IC3

4500

99.3

90.2

＞100

29

Upper IC4

10000

98.4

76.4

＞100

13

Upper IC512500 (5 years)

97.9 (5 years)

71.1 (5 years)

＞100

5

* These estimates do not include deterioration from use or during storage. Ensure that this data is only used
for reference purposes.

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Application Note
Table 5. Estimated Time to 70% Lumen Maintenance by Field Test Location
Locations of the Silver Plates

TatsumiPlant
Atmosphereswithin Nichia
Facilities

Light Emitting Diode

Naruto Plant

PrivateResidences

General indoor
Atmospheres

Production
Room 1
Reliability
Laboratory
Service
Entrance
Instrument
Shelter
Production
Room 2

Calculated Lumen MaintenanceISO 11844
Increase of the Mass
by Using Accelerated Corrosion
Corrosivity
for the Silver Plates
Test Results (% in 10 years)
Categories of Indoor(mg/m2 per year)
Atmospheres
NFSW757D NS2W757A-V1

Estimated Time to 70% Lumen
Maintenance(Years)NFSW757D NS2W757A-V1

20

Around Upper IC1

100

99.7

Over 100

Over 10032

Around Lower IC2

100

99.6

Over 100

Over 100

104

Around Lower IC3

99.9

98.8

Over 100

Over 100660

Middle of IC4

98.9

84.8

Over 1002028

Around Lower IC2

100

99.6

Over 100

Over 100

Workshop59

Middle of IC2

99.9

99.3

Over 100

Over 100

Bicycle Parking
Area

151

Around Lower IC3

99.8

98.0

Over 100

Over 100

Living Room47

Around Lower IC2

99.9

99.4

Over 100

Over 100

Kitchen131

Around Lower IC3

99.8

98.4

Over 100

Over 100

113

Around Lower IC3

99.9

98.6

Over 100

Over 10066

Middle of IC2

99.8

99.2

Over 100

Over 100

38

Around Lower IC2

100

99.6

Over 100

Over 100

Automobile
Repair Shop
(Garage)
Commercial Automobile
Buildings
Repair Shop
(Inside of Shop)
Clothing Shop

* These estimates do not include deterioration from use or during storage. Ensure that this data is only used
for reference purposes.

Based on the results of the field tests and estimation, the following conclusions can be summarized:-NS2W757A-V1:
Even if the LEDs are used for 10 years in a semi-outdoor location (i.e. the instrument shelter
example in the field tests), the expected lumen maintenance is approximately 85%; there should
be no major concern that corrosion will occur as a result of being exposed to corrosive gas in theother locations of the field tests.
-NFSW757D:
The reduction in the luminous flux of the LEDs is expected to be small in any field test location;
there should be no major concern that corrosion will occur as a result of being exposed tocorrosive gas in the other locations of the field tests.
There will be little possibility of corrosion regarding the Nichia 757 series LEDs as far as whenLEDs are used in general indoor atmospheres similar to the locations of the field tests. However, if
the LEDs are used in corrosive atmospheres (e.g. used with parts/materials containing sulfur, etc.)
and the concentration of corrosive gas is high - as shown in Nichia’s data that as the mass of silver
plate increases, the luminous flux decrease - it may cause the luminous flux to decrease.

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Application Note

Nichia also has used a different ambient temperature (i.e.TA=60°C) to perform further evaluation of
the test conditions for the corrosion test. When using silver plates for this high temperature
corrosion test, the corrosion rates were not much different compared to when tested at TA=40°C; on
the other hand, when using LEDs, the corrosion rates of the test LEDs were different between theseambient temperatures and these LEDs corroded faster when they were tested at T A=60°C. This canbe explained by the deterioration of the encapsulating resin used in these LEDs; the gas barrier
property of this encapsulating resin can deteriorate faster when the ambient temperature is high.
During the tests, at a certain point of time the luminous flux of the test LEDs decreased followed bya slower decline. When the LEDs were tested at TA=60°C, the luminous flux reached this point
faster than when tested at TA=40°C. This explains that the test conditions that were used for thehigh temperature corrosion test was too severe and is not suitable to evaluate the LEDs.
For the details of the test conditions and results, see Table 6 and Figures 10, 11 and Table 7
respectively.
Table 6. High Temperature Corrosion Test Conditions for NS2W757A-V1
Temperature and Humidity Level
Test Conditionsin Table 3

Gas Composition

Test Duration

H2S 2ppm + NO2 4ppm

240h

40℃ 75%RH

High Temperature
Test Conditions

60℃ 75%RH

110

20000

100

40℃ 75%RH

18000

60℃ 75%RH

16000

90

Mass Increase (mg/m2)

Relative Luminous Flux (%)

Light Emitting Diode2.2.6 Corrosion Test Results under High Temperature Conditions

80
70
60
50
40

14000
12000
10000
8000
6000
4000

40℃ 75%RH

2000

60℃ 75%RH

0
0

40

80

120

160

200

240

Time (h)Figure 10. Lumen Maintenance for NS2W757A-V1

0

40

80

120

160

200

240

Time (h)Figure 11. Increase in the Mass of the Silver PlatesThis document contains tentative information, Nichia may change the contents without notice.
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Application Note
Table 7. Corrosion Test Results - Change in LED Appearance
Temperatureand Humidity
Level

Test Duration
0h

48h

144h

240h

40℃ 75%RH

60℃ 75%RH

Light Emitting Diode2.2.7 Accelerated Corrosion Tests Overview and Planned Further Improvements
Nichia’s accelerated corrosion test results show that in the case of the corrosion of LEDs: theluminous flux does not decrease linearly with time; however in the case of the corrosion of thesilver plates, the mass of the silver plates does increase linearly with time. A possible cause of thisdifference is the gas barrier function of the encapsulating resin used in LEDs.
The test conditions provided in this document are tentative. Nichia considers that its accelerated
corrosion test should be effective and fit for the intended purpose (i.e. using Nichia LEDs ingeneral indoor atmospheres); after reviewing all the data/results detailed in this document, Nichia
believes that the accelerated test conditions used have achieved a satisfactory level of
effectiveness/fitness for purpose. However, Nichia plans to make improvements to these test
conditions and perform further accelerated corrosion tests to provide more accurate and useful
data/results to Nichia customers.

3. LED Precautions for Corrosive Gas
3.1 Storage Considerations
Nichia LEDs have alloy-plated parts containing silver both inside and outside of the package body.
Exposure to a corrosive environment may tarnish the plating, which may result in a reduction in thesolderability and may also cause an adverse effect on the optical characteristics. When storing theLEDs, a hermetically-sealed container should be used.
It is possible to protect the lead frames from corrosion by preventing them from being exposed tocorrosive gas. In order to store the LEDs properly after opening the aluminum bag, the following
examples are recommended:- Storing the LEDs in a desiccator filled with nitrogen.
- Placing the LEDs into a hermetically-sealed container (e.g. the original aluminum bag andresealing).
* Do not store the LEDs in the same desiccator/container with parts/materials that can produce
corrosive gas.
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Application Note
3.2 Design Considerations
When using Nichia LEDs for the chosen application, ensure that the following points are
considered.
- Materials/parts (e.g. gaskets/seals, glue, adhesive, etc.) containing sulfur may affect the plated
surfaces; do not use these materials/parts for the chosen application. If gaskets/seals are used,silicone rubber gaskets/seals should be used with great care to ensure that contact failure does
not occur due to low-molecular weight siloxane.

Light Emitting Diode- In addition to outgassing from some items (e.g. cardboard boxes, rubber items, etc.), a trace
amount of corrosive gas may be found in the ambient air. Halogen-based compounds can also
have an adverse effect on the plated surface and they are found in some resin or resin-basedmaterials/parts.
- Even if the LEDs have been soldered to a PCB and/or the PCB has been installed in an end
product, the plated surfaces may be adversely affected by gas that is released frommaterials/parts near the LEDs and/or gas that enters from the outside environment.

4. Summary and References
LED corrosion occurs due to multiple factors that are intricately linked, rather than a single
independent factor. Examples of these factors are the concentration/composition of gas,
temperature/humidity, etc. When designing a product that will use Nichia LEDs, consider theambient conditions of the environment where the LEDs will be used (e.g. temperature, humidity,etc.) and the possibility that corrosive gas exists in this environment; if any, thecomposition/concentration of the gas should be identified. Materials/parts that will be used with ornear the LEDs should also be checked to see if there is any possibility of these materials/parts
generating corrosive gas. Additionally, if corrosive tests are performed on the LEDs, ensure thatthese factors are considered for the intended environment and that appropriate test conditions are
determined.
The evaluation results/data in this document are provided for illustrative purposes; ensure thatnecessary evaluations/tests are carried out for the chosen application.
References
1) ISO 11844 Corrosion of metals and alloys – Classification of low corrosivity of indoor
atmospheres- Part 1: Determination and estimation of indoor corrosivity- Part 2: Determination of corrosion attack in indoor atmospheres- Part 3: Measurement of environmental parameters affecting indoor corrosivity2) IEC60068-2-60: 2015 Environmental testing - Part 2-60: Tests - Test Ke: Flowing mixed gas
corrosion test
3) Japan Society of Corrosion Engineering. Questions and Answer regarding the Corrosion andCorrosion Protection of Electrical Equipment Parts. Tokyo: Maruzen, 2006.
This document contains tentative information, Nichia may change the contents without notice.
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Application Note

Light Emitting Diode

Disclaimer
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