NICHIA STS-DA1-2009E <Cat.No.120828>
(4) Design Consideration
● PCB warpage after mounting the products onto a PCB can cause the package to break.
The LED should be placed in a way to minimize the stress on the LEDs due to PCB bow and twist.
● The position and orientation of the LEDs affect how much mechanical stress is exerted on the LEDs placed near the score lines.
The LED should be placed in a way to minimize the stress on the LEDs due to board flexing.
● Board separation must be performed using special jigs, not using hands.
● If an aluminum PCB is used, customer is advised to verity the PCB with the products before use.
Thermal stress during use can cause the solder joints to crack.
(5) Electrostatic Discharge (ESD)
● The products are sensitive to static electricity or surge voltage. ESD can damage a die and its reliability.
When handling the products, the following measures against electrostatic discharge are strongly recommended:
Eliminating the charge
Grounded wrist strap, ESD footwear, clothes, and floors
Grounded workstation equipment and tools
ESD table/shelf mat made of conductive materials
● Proper grounding is required for all devices, equipment, and machinery used in product assembly.
Surge protection should be considered when designing of commercial products.
● If tools or equipment contain insulating materials such as glass or plastic,
the following measures against electrostatic discharge are strongly recommended:
Dissipating static charge with conductive materials
Preventing charge generation with moisture
Neutralizing the charge with ionizers
● The customer is advised to check if the LEDs are damaged by ESD
when performing the characteristics inspection of the LEDs in the application.
Damage can be detected with a forward voltage measurement or a light-up test at low current (≤1mA).
● ESD damaged LEDs may have current flow at a low voltage or no longer illuminate at a low current.
Failure Criteria: VF<2.0V at IF=0.5mA
(6) Thermal Management
● Proper thermal management is an important when designing products with LEDs. LED die temperature is affected
by PCB thermal resistance and LED spacing on the board. Please design products in a way that the LED die temperature
does not exceed the maximum Junction Temperature (TJ).
● Drive current should be determined for the surrounding ambient temperature (TA) to dissipate the heat from the product.
● The following equations can be used to calculate the junction temperature of the products.
1) TJ=TA+RθJA･W
2) TJ=TS+RθJS･W
*TJ=LED junction temperature: °C
TA=Ambient temperature: °C
TS=Soldering temperature (cathode side): °C
RθJA=Thermal resistance from junction to ambient: °C/W
RθJS=Thermal resistance from junction to TS measuring point: °C/W
W=Input power(IF×VF): W
Ts Point
18
NICHIA [ NICHIA CORPORATION ]
