Applications Engineering Notes
LED Handling and Manufacturing Precautions
lamps should be stored at 30 �C,
or less, and 70% RH, or less, in its original sealed container
(anti-static bag) in a dry location.
life is about 3 to 6 months (depending on ambient conditions).
If the LED lamps are
to be stored for more then 6 months, they can be stored for a year in a
perfectly sealed container with a nitrogen atmosphere and moisture
Rapid transitions in ambient temperature, especially in high humidity
environments, where condensation can occur should be avoided.
electricity and/or surge voltages will damage LED die, LED lamps, and
LED based products. Electrostatic discharge can be at times
All LEDs are
susceptible to ESD damage and GaN based LEDs (blue, white, green) are
particularly more sensitive to surge voltages caused by ESD.
ESD damage can vary
in its degree; from very subtle to catastrophic, and invariably will
affect the LED�s performance and life.
exhibit some unusual operating characteristics such as: increase in
reverse leakage current, increase or decrease in forward voltage (VF),
increase on the turning ON point
(not lighting at low currents), flickering, erratic behavior or
It is recommended
that anti-electrostatic wristbands and/or anti-electrostatic gloves be
used when handling LED products. All
personnel, devices, equipment, instruments and machinery must be
properly grounded at all times.
to ensure that the proper and true grounding indeed exists and check
the ground path�s continuity.
is recommended that measures be taken to avoid surge voltage to/from
the equipment that handles, touches, mounts
and solders LED lamps.
anti-static environment by using electrically conductive mats (below
106W) and/or other anti-static equipment such as ionizing fans.
Avoid any friction
between LED lamps or PCB boards containing LED lamps and tools,
instruments and housings made of plastics, metals, or other easily
electrically charged materials.
buildup occurs (and/or increases) easily in dry environmental
conditions (low relative humidity). A relative humidity of 50% or
higher is recommended for electronic-components manufacturing
environments. Be extremely careful when the RH drops below 50%.
should be kept below 200 V in the working area.
handling care should be taken when intentionally submitting LEDs to
voltages (or currents) well above the specified operating maximum
ratings (be aware of surge voltages produced when power to an LED is
generation and dissipation:
design of the end product is of the most importance for long-term
reliability and optimum lumen maintenance of the LED base product.
generation of the LED(s) and other components is to be considered
while designing the circuit layout and the complete system.
thermal resistance of the circuit board and density of LEDs and other
components on the board will all affect the coefficient of temperature
increase per input electric power.
heat dissipation (heat
sinking and heat extraction) of internally and externally generated
heat build-up needs to be included in any end product containing a
large LED and component density.
generation must be lowered and should be well maintained within the
current should be decided and adjusted (de-rating) after considering
the maximum ambient temperature in which the LEDs will be operating.
(4) Lead forming:
(bending) the leads of an LED lamp,
a distance of at least 3mm, from the base of the epoxy lens,
should be maintained.
Do not use the base
of the lead frame as a fulcrum during lead forming. Use proper tools.
forming should be done before soldering.
not apply any bending stress to the base of the lead since the stress at the base may damage the
physical characteristics of the LED lamp or it may break the lens or the internal wire bond.
When mounting the
LEDs onto a PCB, the holes on the circuit board should be exactly
aligned with the leads of the LEDs as to avoid stress on the leads
during insertion and mounting of the LEDs and later operation. Such
stress could cause damage to the epoxy resin leading to potential
early failure of the LED lamp.
is recommended that isopropyl alcohol be used as a solvent for
cleaning the LED lamps.
case other solvents are being considered, it needs to be confirmed if
such solvents will dissolve, damage or
affect the lens resin. Freon solvents should not be used to clean LED lamps because of
Do not clean LED
lamps using ultrasonic vibrating devices. If it is absolutely
necessary to do so, be aware that the influence of ultrasonic cleaning
on the LED lamps will depend on factors such as the applied ultrasonic
power and assembly conditions.
performing any cleaning, a pre-test should
be done to check whether any damage would occur to the LED lamp.
temperature of the PCB, LED lamp, and soldering equipment should be
measured, controlled and maintained before and during and soldering
While soldering, if
the temperature of the LED lamp is allowed to reach an exceed the
glass-transition temperature (Tg) point of the lens epoxy, the
internal LED bonding gold wire could potentially break once the epoxy
hardens upon cooling.
The LED lamp(s)
soldered to a PCB should not be subjected to physical shock
immediately after soldering is finished since the lens epoxy might
still be soft inside the LED lamp. Shock may cause the gold wire to
The best way to
harden the epoxy is to have a cooling fan to provide gradual cooling.
(7) Safety guidelines for the human
In 1993, the
International Electric Committee (IEC) issued a standard con�cerning
laser product safety (IEC 825-1). Since then, this standard has been applied for diffused light sources (LEDs) as well as lasers.
In 1998 IEC 60825-1 Edition 1.1 evaluated the magnitude of the
2001 1C 60825-1 Amendment 2 converted the laser class into 7 classes
for end products.
Lamps) are excluded from this system.
Products that contain visible LEDs are now classified as class
1. Products containing UV LEDs can be classified as class 2 in cases
where viewing angles are narrow, optical manipulation intensifies the
light, and/or the energy emitted is high. For these systems
it is recommended to avoid long-term exposure. It is also recommended
to follow the ICE regulations regarding the safety and labeling of products.
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