Application Note

Light Emitting Diode

Assembly and Handling Precautions
for LEDs

Table of contents
1. Overview ........................................................... 2
2. Applicable Part Numbers .................................. 2
3. Storage .............................................................. 3
4. Directions for use .............................................. 5
5. Handling Precautions ........................................ 6
6. Design Precautions ............................................ 7
7. Precautions for the Mounting Process ............ 10
8. Electrostatic Discharge (ESD) .........................11
9. Thermal Management ..................................... 12
10. Cleaning ........................................................ 12
11. Eye Safety ..................................................... 12
12. Summary ....................................................... 13

NJSx170x, NCSx170x, NC2x170x, NCSx131x, NC2x131x, NC2W121x, NC3W121x, NC4W121x,
NC5W121x, NJ2W270x, NJ3W270x, NJSx172x, NFSx172x, NFSx123x, NC2W093x, NC3W093x,
NC4W093x, NC5W093x, NSSx146x, NESx146x, NHSx146x, NHSx046x, NSSx064x, NESx064x,
NHSx064x, and NSSx063x refer to Nichia part numbers. These Nichia part numbers within thisdocument are merely Nichia’s part numbers for those Nichia products and are not related nor bearresemblance to any other company’s product that might bear a trademark.
This document contains tentative information, Nichia may change the contents without notice.
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Application Note
1. Overview
When handling LEDs, care should be taken to ensure that they are handled in a proper manner; if
LEDs are improperly handled, it may cause damage to the LEDs and/or an adverse effect on theirperformance.
This application note provides assembly and handling precautions for Nichia LEDs.

2. Applicable Part Numbers
This application note applies to the LEDs shown in Table 1.

Light Emitting Diode

Table 1. Applicable LED Part/Series Numbers
Category
Part Number2

Nichia 170/131 Series1
NJSx170x
NCSx170xNC2x170x
NCSx131xNC2x131x

Nichia 121 Series
NC2W121x

NC3W121x

NC4W121x

NC5W121x3.1×2.6×0.75

3.1×3.75×0.75

3.1×4.9×0.75

3.1×6.05×0.75

Examples ofLED
Series1
PackagePart Number2
Appearance
Package Size
(Unit: mm)

1.6×1.2×0.75

Category
Part Number

1.8×1.45×0.75

3.0×1.6×0.75

Nichia 270 Series
2

Nichia 172 Series

NJ2W270x

NJ3W270x

3.5×3.5×0.75

3.5×3.5×0.75

NJSx172x

NFSx172x

Nichia 123 Series
NFSx123x

Examples of
Package
Appearance
Package Size
(Unit: mm)

Category
Part Number

3.0×3.0×0.8

Nichia 093 Series2

3.0×2.0×0.7

Nichia 146 Series

NC2W093x

NC3W093x

NC4W093x

NC5W093x8.5×8×1.5

8.5×8×1.5

8.5×8×1.5

8.5×8×1.5

NSSx146x

NESx146x

NHSx146x

Examples of
Package
Appearance
Package Size
(Unit: mm)

Category
Part Number

Nichia 046 Series
2

NHSx046x

2.2×1.4×0.7

Nichia 064 Series
NSSx064x

NESx064x

Nichia 063 Series
NHSx064x

NSSx063x

Examples of
Package
Appearance
Package Size
(Unit: mm)

2.2×1.4×1.3

3.5×2.8×2.0

3.5×2.8×2.0

Note:
1 The electrode pattern on the back of the package for the Nichia 170 Series and Nichia 131 Series is different.
2 The x represents a letter that follows the alphanumeric code of the same LED type.
(e.g.: NCSx170x → NCSW170C, NCSW170D, NCSW170D-PCA, NCSA170D, NCSW170F, NCSA170F, etc.)
This document contains tentative information, Nichia may change the contents without notice.
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Application Note
3. Storage
3.1 Storage Conditions
If the LED package absorbs moisture and is exposed to heat during soldering, it may cause themoisture to vaporize and the package to expand and the resulting pressure may cause internaldelamination. To minimize moisture absorption in storage/transit, moisture-proof aluminum bags
are used for the LEDs with a silica gel packet to absorb any air moisture in the bag.
Table 2 provides the required storage conditions before and after opening the moisture-proof
aluminum bag.

Light Emitting Diode

Table 2. Storage Conditions
Conditions

Temperature

HumidityTime

Before Opening the Moisture-proof
Aluminum Bag≤30℃≤90%RHWithin 1 Year from Delivery Date

After Opening the Moisture-proof
Aluminum Bag≤30℃≤70%RHMSL2
Within1 YearMSL2aWithin4 Weeks

MSL3
Within168 Hours

The “After Opening” storage time is different depending on the Moisture Sensitivity Level (MSL)3of the LED. Refer to the specification for each LED part number for the MSL to ensure that soldering
is completed within the specified storage time.
Once the moisture-proof aluminum bag is open, ensure that the LEDs are not exposed to a corrosive
environment since the LEDs have metal-plated parts both inside and outside of the package; if theplated surfaces tarnish due to a corrosive environment, it may cause issues (i.e. solderability, opticalcharacteristics).
To store any remaining unused LEDs, use a hermetically sealed container with silica gel desiccants.
Nichia recommends placing them back to the original moisture-proof aluminum bag and reseal it.
3.2 If the Storage Time has been Exceeded
If the storage time has been exceeded for the LEDs whose “After Opening” storage time is fourweeks or 168 hours, ensure that the LEDs are baked for ≥24 hours at a temperature of 65±5ºC beforeuse.
If any pink silica gel beads are found within the storage times, ensure that the LEDs are baked in
the same manner.
Baking should only be done once.

Note:
3 Refer to IPC/JEDEC STD-020 for detailed information regarding the MSL.
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Application Note

The blue silica gel beads absorbed
moisture and turned pink.
B. After being left for 168 hours at

A. When packed forshipment

30ºC and 70%RH

Figure 1. Appearance of Silica Gel DesiccantsLight Emitting Diode3.3 Deformation of the Embossed Carrier Tape
Do not store the LEDs in a manner where excessive external force may be applied to the reel (e.g.
the reel is stored using a vacuum seal, heavy objects are stacked onto the reel, etc.) since it may
cause the embossed carrier tape to deform; see Figure 2. If the embossed carrier tape deforms, theLEDs inside the pockets of the embossed carrier tape may tilt, causing damage to the LEDs and/or
pick-up errors.

Correct

Incorrect
Deformed

Deformed

Tilted LED in Pocket

Before Opening the
Bag with a Reel in it

Squashed Reel as a Resultof Vacuum Sealing

Figure 2. Vacuum Storage and Deformation of the Embossed Carrier Tape
3.4 Storage Environment
To avoid condensation, the LEDs must not be stored in areas where temperature and humidity
fluctuate greatly. Also, ensure that the LEDs are not exposed to direct sunlight and/or anenvironment over a long period of time where the temperature is higher than normal room
temperature, and are not stored in a dusty environment.

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Application Note
4. Directions for use
4.1 Absolute Maximum Ratings
Absolute maximum ratings of the LEDs are the maximum values that must not be exceeded evenfor a short period of time. It must be ensured that the absolute maximum ratings are taken into
consideration when designing a system/application using the LED and will not be exceeded in theconditions/environments in which the LED will actually be used even for a short period of time.
For the absolute maximum rating values for the LED, refer to the applicable specification.

The circuit must be designed to ensure that the absolute maximum ratings are not exceeded for eachLED. The LEDs should be operated at a constant current per LED. In the case of operating at aconstant voltage, Circuit B is recommended. If Circuit A is used, it may cause the currents flowing
through the LEDs to vary due to the variation in the forward voltage characteristics of the LEDs on
the circuit.

Incorrect

Correct

(A)

(B)

(A)

(B)

...

...

Light Emitting Diode

4.2 Circuit Design Considerations

Figure 3. Examples of a Parallel Circuit
4.3 Operating Current
These LEDs are designed to be operated at a forward current. To stabilize the LED characteristics
while in use, Nichia recommends that the LEDs are operated at currents ≥10% of the sorting current.
For the sorting current for the LED, refer to the applicable specification.
4.4 Precautions for when the LED is Off
Ensure that no voltage is applied to the LED in the forward/reverse direction while the LED is off.
If the LEDs are used in an environment where reverse voltages are applied to the LED continuously,
it may cause electrochemical migration to occur causing the LED to be damaged. When not in use
for a long period of time, the system’s power should be turned off to ensure that there are noissues/damage.
4.5 Precautions for Environmental Conditions
Ensure that transient excessive voltages (e.g. lightning surge) are not applied to the LEDs. If theLEDs are used for outdoor applications, ensure that necessary measures are taken (e.g. protecting
the LEDs from water/salt damage and high humidity).
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Application Note
5. Handling Precautions
5.1 Handling with bare hands
Do not handle the LEDs with bare hands. This may contaminate the LED surface and have an effecton the optical characteristics. Also, the electrodes, package, etc. may cause injuries when the LED
is handled with bare hands.
5.2 Handling with tweezers

Light Emitting Diode

Ensure that when handling the LEDs with tweezers, excessive force is not applied to the LED.
Otherwise, it may cause damage to the light emitting area and/or the silicone resin (e.g. cut, scratch,chip, crack, etc.) and have an effect on the optical characteristics and/or the reliability.
Table 3. Correct/Incorrect Examples of Handling the LEDs with Tweezers
Correct Examples

Correct

Incorrect Examples

Incorrect

Incorrect

NCSW170F

NJ2W270B

NC5W093B

For the LEDs with ceramic substrates (e.g. the 170/270 series LEDs), grab/hold the LEDs by thesides of the substrate. For the resin packaged LEDs (e.g. the 093 series LEDs), grab/hold the LEDsby the sides of the package. See the Correct Examples in Table 3. Do not apply excessive force tothe emitting area and/or the silicone resin as shown by the Incorrect Examples in Table 3.

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Application Note
5.3 Other Precautions
Do not drop the LEDs; this may cause issues (e.g. crack, chip, and/or deformation of the LED, and/or
cut, scratch, etc. on the emitting area) causing the optical characteristics and/or the reliability to be
adversely affected.

6. Design Precautions

Light Emitting Diode6.1 LED Position/Orientation on the PCB Assembly
If the LEDs are soldered to a PCB and the PCB assembly is bent (e.g. PCB depaneling process), it
may cause the LED package to break. The PCB layout should be designed to minimize themechanical stress on the LEDs when the PCB assembly is bent/warped; see Figure 4.

Soldering Pad
Soldering Pad
Bending
Direction

A. Recommended Direction

Bending
Direction
B. Not Recommended Direction(Excessive force may be applied to the LED)

Figure 4. Examples of the LED Orientation for the PCB Bending Direction
for a NC2x170x LED
The amount of mechanical stress exerted on the LED from depaneling may vary depending on the
LED position/orientation on the PCB assembly (e.g. especially in areas near the slits and/or
perforations). The PCB layout should be designed to minimize the mechanical stress on the LEDs
when the PCB is separated into individual PCB assemblies. For example, in Figure 5 the amount ofstress on the LED from depaneling would be smallest for LED E.
To separate a PCB populated with the LEDs, use a specially designed tool. Do not break the PCB
by hand; this may cause excessive stress to be applied to the LEDs.

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Application Note

LED E

Slit

LED D

Soldering Pad
Perforation

LED C

Light Emitting Diode

LED A

LED B

Amount of Stress on the LED:
A＞B＞C＞D＞E

Figure 5. Examples of the LED Position/Orientation near the slits and perforations
on a PCB for a NC2x170x LED
6.2 Volatile Organic Compounds (VOCs)
Materials present around the LEDs (e.g. housing, gasket/seal, adhesive, secondary lens, lens cover,grease, etc.) may contain volatile organic compounds (VOCs); the VOCs that have been released
from them may penetrate the encapsulating resin of the LED. If the LEDs are being used in ahermetically/near-hermetically sealed environment, VOCs can discolor after being exposed to heat
and/or photon energy and it may greatly reduce the LED light output and/or cause color shift (seeFigure 6). Perform a light-up test of the chosen application for optical evaluation to ensure that there
are no issues before use.
Ventilating the environment may improve the reduction in light output and/or color shift that may
occur due to VOCs.

Discolored

DiscoloredNC2W170B LED

NFSW172 LED

Figure 6. Examples of Discoloration due to VOCs

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Application Note
6.3 Corrosive Gases
To prevent substances/gases from affecting the plated surfaces of the LEDs, ensure that theparts/materials used with the LEDs (e.g. gasket/seal, adhesive, etc.) in the same assembly/system do
not release corrosive gases (i.e. the parts/materials do not contain sulfur, halogens, etc.). If theplating becomes contaminated, it may cause issues (e.g. electrical connection failures, an adverse
effect on the optical characteristics, etc.). If a gasket/seal is used, silicone rubber gaskets/seals arerecommended; ensure that this use of silicone does not result in issues (e.g. electrical connection
failures) caused by low molecular weight volatile siloxane.

Light Emitting Diode6.4 How to Select an Appropriate PCB
Note that solder cracks are more likely to occur when a ceramic material is used for the substrates
or packages of the LED (see Table 4) and a metal-core PCB (especially an aluminum PCB) is
selected to mount the LED on.
Table 4. LEDs with Ceramic Substrates/Packages
LEDs with Ceramic Substrates

LEDs with Ceramic Packages

Nichia 170 Series

Nichia 131 Series

Nichia 172 Series

Nichia 121 Series

Nichia 270 Series

Nichia 123 Series

Solder cracks are more likely to occur when the difference in the coefficient of thermal expansion(CTE)4 between the LED and the PCB is large due to the thermal stress generated during operation.
For example, the magnitude of the CTE values for aluminum, copper, and ceramic can be describedas aluminum > copper > ceramic; using a copper-core PCB for the LED with a ceramic
substrate/package is a better option than using an aluminum substrate to prevent solder cracks.
Nichia recommends that a metal-core PCB with an insulting layer with a low elastic modulus (i.e.
low modulus elasticity insulating layer) is used to reduce the possibility of solder cracks. Using Nonsolder Mask Defined (NSMD)5 to create the soldering pad pattern on the PCB is also effective.
The solder crack resistance varies depending on the types of solder paste (i.e. composition) as wellas the specifications of the PCBs. Ensure that sufficient verification is performed to determine theappropriate PCB and solder paste for the chosen application.

Note:
4 CTE describes how the size of an object changes with an increase in temperature per degree of Celsius (i.e. /°C).
5 For NSMD, the soldering pad pattern is defined by the dimensions of the copper layer with gaps between thesolder resist and copper layer. For Solder Mask Defined (SMD), the soldering pad pattern is defined by theaperture of the solder resist with a large copper layer under it.
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Application Note
7. Precautions for the Mounting Process
7.1 Pick-and-place Nozzle

Light Emitting Diode

Ensure that the size and shape of the nozzle tip are appropriate for the LEDs. Otherwise, this may
damage the LED (i.e. scratch, chip, crack, etc.), affecting the optical characteristics and/or the
reliability. This may also lead to an incorrect pick up (i.e. the LED is picked up in a tilted position).
Refer to the applicable specification for the recommended nozzle dimensions for the LED. For
products that do not have the recommended nozzle dimensions described in the specification,
contact a local Nichia sales representative.
When setting the LED pick-up position, ensure that the center of the nozzle and the center of theemitting area of the LED are aligned. Do not apply excessive force to the emitting area when picking
up the LED. If the nozzle does not pick up the LED at the center of the emitting area, and/or if
excessive force is applied to the LED, this may damage the LEDs (i.e. scratch, chip, crack, etc.),
affecting the optical characteristics and/or the reliability. This may also lead to an incorrect pick up(i.e. the LED is picked up in a tilted position).
7.2 Precautions When Soldering
When soldering, do not apply stress to the LED while the LED is hot.
When flux is used, it should be a halogen-free flux. Ensure that the manufacturing process is notdesigned in a manner where the flux will come in contact with the LEDs.
7.3 Reflow Conditions
The LEDs are designed to be reflow soldered to a PCB. Reflow soldering must not be performed
more than twice.
Nichia recommends using the reflow soldering conditions detailed in Figure 7; use therecommended reflow conditions specified by the manufacturer of the solder paste being used if itworks better for the chosen application. To ensure that these reflow conditions have no negative
effect on the LEDs, perform sufficient verification prior to use. When cooling the LEDs from thepeak temperature, a gradual cooling slope is recommended; do not cool the LEDs rapidly.
During reflow soldering, the heat andatmosphere in the reflow oven may cause
the optical characteristics to degrade. In
particular, reflow soldering performed withan air atmosphere may have a greater
negative effect on the optical characteristics
than if a nitrogen atmosphere is used; Nichia
recommends using a nitrogen reflow
atmosphere.
Figure 7. Recommended Reflow Soldering Condition
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Application Note
7.4 Precautions for Assembled PCBs
Do not stack assembled PCBs together. Otherwise, it may cause damage to the emitting area and/or
the resin (e.g. cut, scratch, chip, crack, etc.) and have an effect on the optical characteristics and/or
the reliability.
Refer to the applicable application notes for the detailed information for the assembly precautions.

8. Electrostatic Discharge (ESD)

Light Emitting Diode

8.1 ESD Precautions for Handling the LEDs
The LEDs are sensitive to transient excessive voltages (e.g. ESD, lightning surge). If this excessive
voltage occurs in the circuit, it may cause the LED to be damaged causing issues (e.g. the LED to
become dimmer or not to illuminate [i.e. catastrophic failure]). Ensure that when handling the LEDs,
necessary measures are taken to protect them from an ESD discharge. The following examples arerecommended measures to eliminate the charge:- Grounded wrist strap, ESD footwear, clothes, and floors- Grounded workstation equipment and tools- ESD table/shelf mat made of conductive materials
Ensure that all necessary measures are taken to prevent the LEDs from being exposed to transient
excessive voltages (e.g. ESD, lightning surge):- tools, jigs, and machines that are used are properly grounded- appropriate ESD materials/equipment are used in the work area
- the system/assembly is designed to provide ESD protection for the LEDs
8.2 ESD Precautions for Tools/Equipment
If the tool/equipment used is an insulator (e.g. glass cover, plastic, etc.), ensure that necessary
measures have been taken to protect the LED from transient excessive voltages (e.g. ESD). The
following examples are recommended measures to eliminate the charge:- Dissipating static charge with conductive materials- Preventing charge generation with moisture- Neutralizing the charge with ionizers
8.3 Identifying ESD Damaged LEDs
To identify if an LED was damaged by transient excess voltages (i.e. an ESD event during thesystem’s assembly process), perform a characteristics inspection (e.g. forward voltage measurement,
light-up test) at low current (≤1mA). If the LED was damaged by transient excess voltages (e.g.
ESD), it would cause the forward voltage (VF) to decrease, the LED not to illuminate at a low current,
etc.
For the failure criteria for the LED, refer to the applicable specification; the failure criteria for the
VF at the forward current of 0.5mA is specified.
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Application Note
9. Thermal Management
The absolute maximum junction temperature (TJ) must not be exceeded under any circumstances.
The increase in the temperature of an LED while in operation may vary depending on the PCB
thermal resistance and the density of LEDs on the PCB assembly. Ensure that when using the LEDs
for the chosen application, heat is not concentrated in an area and properly managed in thesystem/assembly.
The operating current should be determined by considering the temperature conditions surrounding
the LED (i.e. TA). Ensure that when operating the LED, proper measures are taken to dissipate theheat.

Light Emitting Diode10. Cleaning
Do not clean and/or wipe the emitting surface of the LED. If an area of the LED other than theemitting surface is contaminated (e.g. dust/dirt), use a cloth, swab, etc. soaked with a small amountof isopropyl alcohol (IPA) and wipe the LED with it in a manner that does not touch the emitting
surface. If another solvent is used, it may cause the LED package/resin to be damaged causing theoptical characteristics and/or the reliability to be affected; ensure that sufficient verification is
performed prior to use.
Do not clean the LED with an ultrasonic cleaner. This may cause the optical characteristics and/or
the reliability to be affected.

11. Eye Safety
There may be two important international specifications that should be noted for safe use of theLEDs: IEC 62471:2006 Photobiological safety of lamps and lamp systems and IEC 60825-1:2001(i.e. Edition 1.2) Safety of Laser Products - Part 1: Equipment Classification and Requirements.
Ensure that when using the LEDs, there are no issues with the following points:- LEDs have been removed from the scope of IEC 60825-1 since IEC 60825-1:2007 (i.e. Edition
2.0) was published. However, depending on the country/region, there are cases where therequirements of the IEC 60825-1:2001 specifications or equivalent must be adhered to.
- LEDs have been included in the scope of IEC 62471:2006 since the release of the specification in2006.
- Most Nichia LEDs will be classified as the Exempt Group or Risk Group 1 according to IEC
62471:2006. However, in the case of high-power LEDs containing blue wavelengths in the emission
spectrum, there are LEDs that will be classified as Risk Group 2 depending on the characteristics(e.g. radiation flux, emission spectrum, directivity, etc.)- If the LED is used in a manner that produces an increased output or with an optic to collimate thelight from the LED, it may cause damage to the human eye.
If an LED is operated in a manner that emits a flashing light, it may cause health issues (e.g. visual
stimuli causing eye discomfort). The system should be designed to ensure that there are no harmful
effects on the human body.
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Application Note
12. Summary

Light Emitting Diode

The LEDs need to be handled and assembled in a proper manner to obtain the required
characteristics and the reliability. Follow the cautions/suggestions detailed in this application noteand the applicable specification for the LED to ensure that the LED is used properly.
In addition, perform sufficient verification with the conditions/environments in which the chosen
application containing the LED will actually be used to ensure that the characteristics and/or the
reliability for the LED are not adversely affected before selecting other components to be used with
the LED.

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Application Note
Disclaimer
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 chosen
application.

Light Emitting Diode・ The information/data contained herein are only typical examples of performances and/or
applications 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
damages or losses arising out of exploiting, using, or downloading or otherwise this document,or any other acts associated with this document.
・ The content of this application note may be changed without any prior or subsequent notice.
・ Copyrights and all other rights regarding the content of this document are reserved by Nichia or
the right holders who have permitted Nichia to use the content. Without prior written consent of
Nichia, republication, reproduction, and/or redistribution of the content of this document in any
form or by any means, whether in whole or in part, including modifications or derivative works
hereof, is strictly prohibited.

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Phone: +81-884-22-2311 Fax: +81-884-21-0148

NICHIA CORPORATION
http://www.nichia.co.jp

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