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 effectively 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 personnel to prevent ESD

damage to the LED component that is ESD sensitive.

Do refer to Avago application note AN 1142 for details.

The soldering iron used should have grounded tip to

ensure electrostatic charge is properly grounded.

• Recommended soldering condition:

Wave

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 thermocouple

mounted at the bottom of PCB.

2. To reduce thermal stress experienced by LED, it is recommended

that you use only bottom preheaters.

1.59 mm

• 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 profile to

ensure that it is always conforming to recommended

soldering conditions.

Notes:

1. PCB with different size and design (component density) will

have different 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 profile 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 fixture that is being applied during

wave soldering should be loosely fitted 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 fixture 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 reflow 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 (typ.) 0.45 × 0.45 mm

(0.018 × 0.018 in.)

0.636 mm

(0.025 in)

0.98 to 1.08 mm

(0.039 to 0.043 in)

Dambar shear-

off area (max.)

0.65 mm

(0.026 in)

0.919 mm

(0.036 in)

Lead size (typ.) 0.50 × 0.50 mm

(0.020 × 0.020 in.)

0.707 mm

(0.028 in)

1.05 to 1.15 mm

(0.041 to 0.045 in)

Dambar shear-

off area (max.)

0.70 mm

(0.028 in)

0.99 mm

(0.039 in)

• Over-sizing the PTH can lead to twisted LED after

clinching. On the other hand under sizing the PTH can

cause difficulty inserting the TH LED.

For more information about soldering and handling of

TH LED lamps, refer to application note AN5334.