With the rising awareness of global environmental protection, energy saving has become a trend today. The LED industry is one of the most watched industries in recent years. Up to now, LED products have the advantages of energy saving, power saving, high efficiency, fast reaction time, long life cycle, and no mercury, and have environmental benefits; However, usually the input power of LED high-power products is about 20%, which can be converted into light, and the remaining 80% of the energy is converted into heat.
In general, if the thermal energy generated by LED illumination cannot be exported, the junction temperature of the LED will be too high, which will affect the product life cycle, luminous efficiency and stability, and the junction temperature, luminous efficiency and lifetime of the LED. Relationships, which will be further explained below using the relationship diagram.
1, LED heat dissipation
According to different packaging technologies, the heat dissipation method is also different, and the various ways of cooling the LEDs can be roughly illustrated:
Description of the heat dissipation route:
(1). Cooling from the air
(2). Thermal energy is directly exported by the System circuit board
(3). Export thermal energy via gold wire
(4). For eutectic and Flip chip processes, thermal energy is derived via vias to the system board
In general, an LED die (Die) is bonded to a substrate (Substrate of LEDDie) by gold wire, eutectic or flip chip to form an LED chip, and then the LED chip is fixed to the circuit of the system. System circuit board. Therefore, the possible heat dissipation path of the LED is to dissipate heat directly from the air, or through the LED die substrate to the system board to the atmosphere. The rate at which heat is dissipated from the system board to the atmosphere depends on the design of the entire luminaire or system.
However, most of the thermal bottlenecks of the entire system at this stage occur mainly by transferring heat from the LED die to its substrate to the system board. The possible heat dissipation path of this part: one is to directly dissipate heat to the system circuit board by the die substrate. In this heat dissipation path, the heat dissipation capability of the LED die substrate material is a very important parameter. On the other hand, the heat generated by the LED will also pass through the electrode metal wire to the system board. Generally, the heat dissipation by the gold wire is limited by the elongated geometry of the wire itself. Recently, there is a eutectic (EutecTIc) or flip chip (Flipchip) bonding method. This design greatly reduces the length of the wire and greatly increases the cross-sectional area of ​​the wire. Thus, the heat dissipation efficiency of the LED electrode wire to the system board is effective. Upgrade.
Through the above explanation of the heat dissipation path, it can be known that the selection of the heat-dissipating substrate material and the packaging method of the LED die occupy an extremely important part in the LED heat dissipation management, and the latter section will briefly explain the LED heat-dissipating substrate.
2, LED heat sink substrate
The LED heat-dissipating substrate mainly uses the heat-dissipating substrate material itself to have better thermal conductivity, and the heat source is derived from the LED die. Therefore, from the description of the LED heat dissipation method, the LED heat dissipation substrate can be subdivided into two categories, namely, the LED die substrate and the system circuit board. The two different heat dissipation substrates respectively carry the LED die and the LED chip. The thermal energy generated when the LED die emits light is radiated to the system board through the LED die, and then absorbed by the atmospheric environment to achieve the effect of heat dissipation.
Window Optical Lenses,Optical Lenses,Window Optical Lens,Calcium Fluoride Glass Window
Danyang Horse Optical Co., Ltd , https://www.dyhorseoptical.com