7

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 opera-

tion, as the excess lead length also acts as small heat

sink.

Soldering and Handling:

• CaremustbetakenduringPCBassemblyandsoldering

process to prevent damage to the LED component.

• LED component may be effectively hand soldered

to PCB. However, it is only recommended under un-

avoidable circumstances such as rework. The closest

manual soldering distance of the soldering heat

source (soldering iron’s tip) to the body is 1.59mm.

Note:

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. Avago Technologies’ high brightness LED are using high efficiency

LED die with single wire bond as shown below. 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.

Avago Technologies LED configuration

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 sol-

dering 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 sol-

dering 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.

-

Preheat time

60 sec Max

-

Peak temperature

250 °C Max.

260 °C Max.

Dwell time

3 sec Max.

5 sec Max

Note:

1) Above conditions refers to measurement with thermocouple

mounted at the bottom of PCB.

2) It is recommended to use only bottom preheaters in order to reduce

thermal stress experienced by LED.

• Wave soldering parameters must be set and main-

tained according to the recommended tempera-

ture 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.

Note: Electrical connection between bottom surface of LED die and

the lead frame is achieved through conductive paste.

• 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 mate-

rial 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 recommend-

ed 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 sol-

dered 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

0.45 x 0.45 mm

(0.018x 0.018 inch)

0.636 mm

(0.025 inch)

0.98 to 1.08 mm

(0.039 to 0.043 inch)

0.50 x 0.50 mm

(0.020x 0.020 inch)

0.707 mm

(0.028 inch)

1.05 to 1.15 mm

(0.041 to 0.045 inch)

• 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.

AllnGaP Device

CATHODE