LED English as（lightemittingdiode），LED light beads is the abbreviation of light-emitting diode abbreviation LED, which is a common name.
The terminal voltage of the PN junction constitutes a certain potential barrier, which decreases when a forward bias voltage is added, and the majority carriers in the P and N regions diffuse toward each other. As the electron mobility is much larger than the hole mobility, so there will be a large number of electrons to the P region diffusion, constituting an injection of minority carriers in the P region. These electrons are compounded with the holes on the valence band, and the energy obtained during compounding is released in the form of light energy. This is the principle of PN junction luminescence.
High-power LED can not be categorized into the SMD series, their power and current use are not the same, and photoelectric parameters are very different. Single high-power LED light source without heat sink base (generally hexagonal aluminum seat), its appearance and ordinary patch without much difference, high-power LED light source is round, the package is basically the same as the SMD chip, but with the SMD chip in the use of conditions/environment/effects, etc. have essential differences.
LED patch replacement tips
1.I would recommend reflow soldering under normal conditions and manual soldering just for patching.
2.The maximum power of the soldering iron used for manual soldering should not exceed 30W, the soldering temperature should be controlled within 300℃, and the soldering time should be less than 3 seconds.
3.The soldering iron tip must not touch the gel.
4.The pins must not be pressurized when they are heated to 85°C or higher, otherwise the gold wire solder will break.
Reflow soldering
1.Peak reflow temperature: 260°C or lower. (Package surface temperature)
2.Time required for temperature rise above 210°C: 30 seconds or less.
3.Number of times of reflow: not more than two times at the most.
4.After reflow soldering, the LED needs to be cooled to room temperature before contacting the gel.
Reflow soldering, if it is an aluminum substrate, you can also use a hot plate. Soldering iron heating aluminum substrate, but pay attention to the speed of the welded immediately removed.
It is easy to have a false soldering, it is the LED chip on the LED light soldered with a false soldering, and the gold wire in the soldering is not connected properly.
According to different styles of light bar open stencil, stencil and light bar can be consistent can, choose the solder paste with good; poor solder paste using LED lamp beads easy to fall off. Solder paste printing to the position to be welded, and then over the reflow soldering on the welding.