Lead Forming
General Rules for lead bending; -
1. Any lead bending should be done prior to soldering, never after or during soldering.
2. Avoid bending the leads at the same point more than once
3. Never bend the leads at the junction with epoxy, there should be a clearance (min 2mm) between the base of the LED and bend point
4. During the lead forming (bending) process the leads must be held securely to prevent any bending stress being transmitted to the internal structure of the LED
5. Avoid placing any stress on the LED lens in order to prevent fracture of the epoxy layer and damage to the internal structure of the LED.
6. Avoid any stress to LED once it has been mounted, i.e. all lead forming should be undertaken prior to soldering
7. When using an unformed LED, the mounting holes in the PCB must match the lead pitch of the LEDs. Where the pitch of the PCB mounting holes and the LED lead pitch differs, then the LED leads must be preformed to exactly match the mounting hole pitch. This should be performed using the above guidelines.
The diagrams below illustrate of acceptable and unacceptable lead forming practices: -
Acceptable
Not Acceptable
Diagrams courtesy of SunLED Company