Tips for making LED energy-saving lamps: The soldered LED does not light up

If you often encounter this situation "the soldered LED does not light up for no reason", please read the following article carefully

1. The design requires pins or bent feet

When bending and cutting the LED pins, the position of the bending and cutting pins should be greater than 3mm from the bottom surface of the colloid;

Bend the legs before welding;

When using LED plug-in lamps, the PCB hole spacing should correspond to the LED foot spacing;

When cutting pins, the vibration and friction of the cutting machine will generate very high voltage static electricity, so the machine must be reliably grounded and anti-static measures must be taken (an ion fan can be used to eliminate static electricity).

2. Welding conditions

The LED cannot be powered during soldering;

Do not put any pressure on the LED while heating;

Maximum welding conditions:

Manual soldering wave soldering

a. Maximum power of soldering iron: 50 W a. Maximum preheating temperature: 100℃

b. Maximum temperature: 300 ℃ b. Maximum dip soldering temperature: 260 ℃

c. Maximum soldering time: 3 seconds c. Maximum dip soldering time: 5 seconds

d. Soldering position: more than 3mm from the bottom of the colloid d. Dip soldering position: more than 3mm from the bottom of the colloid

3. Anti-static precautions

All equipment and instruments that come into contact with LEDs must be grounded;

All personnel who come into contact with LEDs must wear anti-static wrist straps or anti-static gloves; Do not handle the product with bare hands

If an LED is damaged by static electricity, it will show some undesirable characteristics, such as increased leakage current, decreased or increased static forward voltage, and no light or abnormal light emission during low current testing.

4. Overcurrent protection

Connect a protective resistor in series with the LED to make it work stably

The resistance value calculation formula is: R=(VCC-VF)/IF VCC is the power supply voltage, VF is the LED drive voltage, IF is the forward current

5. Electrical testing and product use

When testing VF, brightness, and wavelength, the current must be set to 20mA, when testing VR, the IR must be set to 10uA, and when testing IR, the VR must be set to 5V;

When testing and using LEDs, the same current must be provided to each LED, i.e., a constant current source must be used for testing to ensure the consistency of the tested brightness and other characteristics.

LED is used in an ambient temperature between -30 ℃ ~ +60 ℃;

When using products with good spectrophotometry and color separation, do not mix products with different grade box numbers (marked on each package label) on the same product to avoid color and brightness differences. If you really need to mix grade box numbers, adjacent grade box numbers can be used together, but try to avoid this.