What are the reasons why the high power LED chip does not light up?
Philips Lumileds imitation lumen LED brand imitation brand LED package quality is far worse than the original, LED welding PCB board light emission is perpendicular to the PCB welding board to parallel to the PCB LED called side-emitting LED.
The reasons why the imitation lumen LED lamp beads are not bright are:
The imitation lumen LED is different from the 2835 lamp beads. The imitation lumen is a packaging process, and the 2835 lamp beads are a patch process. The light effect of the imitation lumen is higher than that of the patch, and the patch is more convenient. , high efficiency, another very important thing is that the patch is very efficient in production, the cost is relatively low, and the production efficiency of imitation lumens is relatively low.
Anti-lumen LED
1. Please check whether the contacts at the bracket are oxidized and open circuit
2. I don't know what the original text is based on "Solid crystal bonding wire is intact". Please confirm whether the pad position of the gold wire on the LED chip is misaligned or missed, and also check whether the gold wire is on the metal bracket. A good metal bond is not soldered to the oxide layer.
Because the LED package structure is very simple, if the die bonding wire is really intact, the chip can be lit, then the package can be lit. Please make sure that the die bonding wire is not 'looks good', but is really good.
LED anti-lumen lamp beads are reflow soldered or hand soldered
After reflow soldering, because the heat sink is soldered to the PCB, the thermal resistance will be smaller, and the thermal conductivity is better. There must be some thermal conductive silica gel below the manual soldering, which is difficult to ensure consistency, sometimes more, sometimes less And the thermal conductivity will definitely not be soldered directly on the PCB. In a short period of time, the silica gel can still be used, but after a long time, the thermal conductivity of the silica gel will be greatly reduced.
Due to the cost of equipment, most small factories are hand-soldered, and large factories are generally reflowed. In addition, there are many 1W lamp beads that imitate lumens on the market now, and the lamp beads of many factories need to be reflowed with low-temperature solder paste. After reflow soldering, the luminous flux will decrease a little, mainly because high temperature has a certain effect on the lens, but reflow soldering with low temperature solder paste will be much better.
