AN1149-6 Lumileds Lighting, LLC, AN1149-6 Datasheet - Page 3

• Manufacturer Part Number: AN1149-6
• Description: Reliability Considerations for SuperFlux LEDs
• Manufacturer: Lumileds Lighting, LLC

the lamp housing to the lens has not produced
any known LED failures it has been identified as
the root cause of some catastrophic failures of
resistors and other leaded components. In
addition, ultrasonic welding of mounting posts
has been identified as the root cause of some
catastrophic failures of LEDs. In these cases,
the transfer of ultrasonic energy from the
mounting posts resulted in a broken wire within
the immediately adjacent LEDs. Although no
Operating Life
Because SuperFlux LEDs are solid state
devices, they survive thousands of hours of
operation. As summarized in Table 6.1,
Lumileds used several ambient temperatures to
Weatherability
SuperFlux LEDs also perform well in
weatherability tests. As summarized in Table
6.1, Lumileds used both forward biased and
reverse biased humidity tests to validate
Corrosion Resistance
The metal leadframe used in SuperFlux LEDs is
made from a copper alloy. The portion of the
leadframe that is inside the plastic body is first
plated with nickel and then silver. The portion of
the leadframe that is outside the plastic body is
coated in tin lead solder. Therefore, SuperFlux
LEDs perform well in corrosion resistance tests.
Temperature Cycle
The semiconductor that emits the light in
SuperFlux LEDs, the leadframe that it is
mounted on, the bond wire that connects the
anode of the chip to the anode of the
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failures of SuperFlux LEDs have been attributed
to ultrasonic welding, the potential for this failure
mode still exists. For this reason, heat staking or
a lower frequency joining process such as
vibration welding is preferred for securing the
mounting posts of the lamp housing to the PCB.
In cases where ultrasonic welding must be used,
it is extremely important to build many evaluation
units to prove the design’s ability to withstand
ultrasonic vibrations.
validate the operating life performance of the
SuperFlux LEDs. These LEDs perform well over
their operating temperature range of –40 °C to
100 °C.
performance after exposure to humidity. These
tests were performed with the LEDs mounted on
a PCB. No housing was used for this test.
The two tests listed in Table 6.1 were used to
validate SuperFlux LED performance during
corrosion testing. The MIL STD 883 test was
performed using individual LEDs, while the SAE
576 test was performed using LEDs mounted on
a printed circuit board. No housing was used for
either test.
leadframe, and the plastic that forms the LED’s
body all have different coefficients of thermal
expansion. Therefore, thermal cycle test
performance is an important measure of