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 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:
Manual Solder
Wave Soldering 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.
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 8. 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°
SOLDER: SN63; FLUX: RMA
NOTE: ALLOW FOR BOARDS TO BE
SUFFICIENTLY COOLED BEFORE EXERTING
MECHANICAL FORCE.
