What are the main factors that affect the heat dissipation of LED packaging?

The problem of heat dissipation is high power LED Encapsulating the challenges that must be addressed . Because the effect of heat dissipation directly affects

LED product

Lifetime and luminous efficiency , Therefore, the problem of high power LED Package heat dissipation problem , To improve LED The reliability and life of the package play an important role .

The first factor ： Packaging structure   The packaging structure is divided into two types: micro spray structure and flip chip structure .

1、 Micro jet structure   In this sealing system , The fluid in the fluid cavity forms a strong jet at the micro nozzle under a certain pressure , This jet impinges directly on LED Chip substrate surface and take away LED The heat produced by the chip , Under the action of micropump , The heated fluid enters the small fluid cavity to release heat to the external environment , Make oneself temperature drop , It flows into the micropump again to start a new cycle .  advantage ： Micro jet structure has high heat dissipation performance and LED The temperature distribution of the chip substrate is uniform .  shortcoming ： The reliability and stability of the micropump have a great impact on the system , And the structure of the system is more complex, which increases the running cost .

2、 Flip chip structure   Flip chip for traditional formal chip , The electrode is located on the light-emitting surface of the chip , So it will block part of the light , Reduce the luminous efficiency of the chip .  advantage ： The chip with this structure , Light comes out of the sapphire at the top , Eliminate the shading of electrodes and leads , Improved luminous efficiency , At the same time, the substrate adopts silicon with high thermal conductivity , The heat dissipation effect of the chip is greatly improved . shortcoming ： The structure of PN The generated heat is exported through the sapphire substrate , Sapphire has low thermal conductivity and long heat transfer path , Therefore, the chip with this structure has a large thermal resistance , Heat doesn't easily escape .

The second factor ： Packaging materials LED Packaging materials are divided into thermal interface materials and substrate materials .

1、 Thermal interface material   At present LED The commonly used thermal interface materials for packaging are thermal conductive adhesive and conductive silver adhesive .

(a) Heat conductive adhesive   The main component of commonly used thermal conductive adhesive is epoxy resin , Therefore, its thermal conductivity is small , Poor thermal conductivity , High thermal resistance .

advantage ： The thermal conductive adhesive has insulation 、 heat conduction 、 Quakeproof 、 Easy to install 、 The process is simple .

shortcoming ： Because the thermal conductivity is very low , Therefore, the utility model can only be applied to those that do not have high requirements for heat dissipation LED On the package device .

(b) Conductive silver glue   Conductive silver glue yes GeAs、SiC Conductive substrate LED, Red light with back electrode 、 Yellow light 、 Yellow and green chips LED Key packaging materials in the process of package dispensing or preparation .

advantage ： With fixed bonding chip 、 Conduct electricity and heat 、 The role of heat transfer , And right LED Heat dissipation of devices 、 Light reflectance 、VF Characteristics have an important impact . As a thermal interface material , At present, conductive silver glue is in LED Widely used in the industry .

2、 Substrate material  LED A certain way of heat dissipation for packaged devices is from

LED chip

To the bonding layer, to the internal heat sink, to the heat dissipation substrate, and finally to the external environment , It can be seen that the heat dissipation base plate is right LED The importance of package cooling , Therefore, the heat dissipation substrate must have the following characteristics ： High thermal conductivity 、 Insulation 、 stability 、 Flatness and high strength .