Kev cuam tshuam ntawm pob substrate ntawm lub tshav kub dissipation ntawm LED
The problem of heat dissipation is a problem that must be addressed in high-power LED packaging. Since the heat dissipation effect directly affects the life and luminous efficiency of the LED lamp, effectively solving the heat dissipation problem of the high-power LED package plays an important role in improving the reliability and life of the LED package. So what are the main factors that affect the heat dissipation of the LED package.
First factor:Package structure
The package structure is divided into two types: micro spray structure and flip chip structure.
1.Micro spray structure
In this sealing system, the fluid in the fluid cavity forms a strong jet at the micro nozzle under a certain pressure. The jet directly impacts the surface of the LED chip substrate and takes away the heat generated by the LED chip, which acts on the micro pump. Bottom, the heated fluid enters the small fluid cavity to release heat to the external environment, so that its temperature drops, and then flows into the micropump again to start a new cycle.
Advantages: The micro-spray structure has high heat dissipation performance and uniform temperature distribution of the LED chip substrate.
Disadvantages: The reliability and stability of the micropump have a great influence on the system, and the structure of the system is more complicated, which increases the operating cost.
2.Flip chip structure
Flip-chip. For the traditional formal chip, the electrode is located on the light-emitting surface of the chip, which will block part of the light emission and reduce the light-emitting efficiency of the chip.
Advantages: The light is taken out from the sapphire on the top of the chip with this structure, which eliminates the shading of electrodes and leads and improves the luminous efficiency. At the same time, the substrate uses silicon with high thermal conductivity, which greatly improves the heat dissipation effect of the chip.
Disadvantages: The heat generated by the PN of this structure is exported through the sapphire substrate. The thermal conductivity of sapphire is low and the heat transfer path is long. Therefore, the chip of this structure has a large thermal resistance and the heat is not easily dissipated.
The second biggest factor:Packaging materials LED packaging materials are divided into two types: thermal interface materials and substrate materials.
1.thermal interface materials
Currently, the commonly used thermal interface materials for LED packaging include thermal conductive glue and conductive silver glue.
(a) Thermal conductive glue
The main component of commonly used thermal conductive glue is epoxy resin, so its thermal conductivity is small, thermal conductivity is poor, and thermal resistance is large.
Advantages: Thermal conductive glue has the characteristics of insulation, heat conduction, shockproof, easy installation, simple process and so on.
Disadvantages: Due to the low thermal conductivity, it can only be applied to LED packaging devices that do not require high heat dissipation.
(b) Conductive silver glue
Conductive silver glue is a GeAs, SiC conductive substrate LED, a key packaging material in the process of dispensing or preparing a red, yellow, and yellow-green chip LED with a back electrode.
Advantages:
It has the functions of fixing and bonding the chip, conducting and conducting heat, and transferring heat, and has an important influence on the heat dissipation, light reflectivity, and VF characteristics of the LED device. As a thermal interface material, conductive silver glue is currently widely used in the LED industry.
2.substrate materials
A certain heat dissipation path of LED package devices is from the 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 substrate is important for the heat dissipation of the LED package. Therefore, the heat dissipation substrate must have the following characteristics: high Thermal conductivity, insulation, stability, flatness and high strength.
