7
Precautions:
Lead Forming
• The leads of an LED lamp may be preformed or cut to
length prior to insertion and soldering into PC board.
• If lead forming is required before soldering, care must
be taken to avoid any excessive mechanical stress
induced to LED package. Otherwise, cut the leads of LED
to length after soldering process at room temperature.
The solder joint formed will absorb the mechanical
stress of the lead cutting from traveling to the LED chip
die attach and wirebond.
• It is recommended that tooling made to precisely form
and cut the leads to length rather than rely upon hand
operation.
Soldering Conditions
• Care must be taken during PCB assembly and soldering
process to prevent damage to LED component.
• The closest LED is allowed to solder on board is 1.59
mm below the body (encapsulant epoxy) for those
parts without standoff.
• Recommended soldering conditions:
Wave Soldering
Manual Solder
Dipping
Pre-heat Temperature 105 °C Max. –
Pre-heat Time 30 sec Max. –
Peak Temperature 250 °C Max. 260 °C Max.
Dwell Time 3 sec Max. 5 sec Max.
• Wave soldering parameter must be set and maintained
according to recommended temperature and dwell
time in the solder wave. Customer is advised to
periodically check on the soldering profile to ensure
the soldering profile used is always conforming to
recommended soldering condition.
• If necessary, use fixture to hold the LED component
in proper orientation with respect to the PCB during
soldering process.
• Proper handling is imperative to avoid excessive
thermal stresses to LED components when heated.
Therefore, the soldered PCB must be allowed to cool to
room temperature, 25°C, before handling.
• Special attention must be given to board fabrication,
solder masking, surface plating and lead holes size and
component orientation to assure solderability.
• Recommended PC board plated through hole sizes for
LED component leads:
LED Component Plated Through
Lead Size Diagonal Hole Diameter
0.457 x 0.457 mm 0.646 mm 0.976 to 1.078 mm
(0.018 x 0.018 inch) (0.025 inch) (0.038 to 0.042 inch)
0.508 x 0.508 mm 0.718 mm 1.049 to 1.150 mm
(0.020 x 0.020 inch) (0.028 inch) (0.041 to 0.045 inch)
Note: Refer to application note AN1027 for more information on
soldering LED components.
Figure 11. Recommended wave soldering profile.
LAMINAR WAVE
BOTTOM SIDE
OF PC BOARD
HOT AIR KNIFE
TURBULENT WAVE
FLUXING
PREHEAT
01020
30
50
100
150
200
250
30 40 50
TIME – SECONDS
TEMPERATURE – °C
60 70 80 90 100
TOP SIDE OF
PC BOARD
CONVEYOR SPEED = 1.83 M/MIN (6 FT/MIN)
PREHEAT SETTING = 150°C (100°C PCB)
SOLDER WAVE TEMPERATURE = 245°C
AIR KNIFE AIR TEMPERATURE = 390°C
AIR KNIFE DISTANCE = 1.91 mm (0.25 IN.)
AIR KNIFE ANGLE = 40°
NOTE: ALLOW FOR BOARDS TO BE
SUFFICIENTL Y COOLED BEFORE EXERTING
MECHANICAL FORCE.
