6
Precautions:
Lead Forming:
• The leads of an LED lamp may be preformed or cut to
length prior to insertion and soldering on PC board.
• For better control, it is recommended to use proper
tool to precisely form and cut the leads to applicable
length rather than doing it manually.
• If manual lead cutting is necessary, cut the leads after
the soldering process. The solder connection forms a
mechanical ground which prevents mechanical stress
due to lead cutting from traveling into LED package.
This is highly recommended for hand solder operation,
as the excess lead length also acts as small heat sink.
Soldering and Handling:
• Care must be taken during PCB assembly and soldering
process to prevent damage to the LED component.
• LED component may be eectively hand soldered
to PCB. However, it is only recommended under
unavoidable circumstances such as rework. The closest
manual soldering distance of the soldering heat source
(soldering iron’s tip) to the body is 1.59mm. Soldering
the LED using soldering iron tip closer than 1.59mm
might damage the LED.
• ESD precaution must be properly applied on the
soldering station and by personnel to prevent ESD
damage to the LED component that is ESD sensitive.
For details, refer to Avago application note AN 1142.
The soldering iron used should have grounded tip to
ensure electrostatic charge is properly grounded.
• Recommended soldering conditions:
Wave
Soldering
[1],[2]
Manual Solder
Dipping
Pre-heat Temperature 105°C Max. –
Pre-heat Time 60 sec Max. –
Peak Temperature 250°C Max. 260°C Max.
Dwell Time 3 sec Max. 5 sec Max.
Notes:
1. These conditions refer to measurement with a thermocouple
mounted at the bottom of PCB.
2. To reduce thermal stress experienced by LED, it is recommended
that you use only bottom preheaters.
• Wave soldering parameters must be set and maintained
according to the recommended temperature and dwell
time. Customer is advised to perform daily check on the
soldering prole to ensure that it is always conforming
to recommended soldering conditions.
Note:
1. PCB with dierent size and design (component density) will
have dierent heat mass (heat capacity). This might cause a
change in temperature experienced by the board if same wave
soldering setting is used. So, it is recommended to re-calibrate
the soldering prole again before loading a new type of PCB.
2. Customer is advised to take extra precaution during wave
soldering to ensure that the maximum wave temperature
does not exceed 250°C and the solder contact time does not
exceeding 3sec. Over-stressing the LED during soldering process
might cause premature failure to the LED due to delamination.
• Any alignment xture that is being applied during
wave soldering should be loosely tted and should
not apply weight or force on LED. Non metal material
is recommended as it will absorb less heat during wave
soldering process.
• At elevated temperature, LED is more susceptible to
mechanical stress. Therefore, PCB must allowed to cool
down to room temperature prior to handling, which
includes removal of alignment xture or pallet.
• If PCB board contains both through hole (TH) LED and
other surface mount components, it is recommended
that surface mount components be soldered on the
top side of the PCB. If surface mount need to be on the
bottom side, these components should be soldered
using reow soldering prior to insertion the TH LED.
• Recommended PC board plated through holes (PTH)
size for LED component leads.
LED Component Lead Size Diagonal
Plated Through
Hole Diameter
Lead size
(Typical)
0.45 x 0.45 mm
(0.018 x 0.018 in)
0.636 mm
(0.025 in)
0.98 to 1.08 mm
(0.039 to 0.043 in)
Dambar shear-
o area (max)
0.65 mm
(0.026 in)
0.919 mm
(0.036 in)
Lead size
(Typical)
0.50 x 0.50 mm
(0.020 x 0.020 in)
0.707 mm
(0.028 in)
1.05 to 1.15 mm
(0.041 to 0.045 in)
Dambar shear-
o area (max)
0.70 mm
(0.028 in)
0.99 mm
(0.039 in)
• Over-sizing the PTH can lead to a twisted LED after it is
clinched. On the other hand, undersizing the PTH can
cause diculty in inserting the TH LED.
For more information about soldering and handling of TH
LED lamps, refer to application note AN5334.
1.59 mm
