Elaborate on the heat dissipation of lamps and lanterns

　　Hello, Miss Sister, I’m here. day I will show you the heat dissipation of lamps and lanterns. I hope you can learn something.

　　As we all know, LED (Light Emitting Diode), light-emitting diode, is a solid-state semiconducr device that can directly convert electrical energy in light energy. The heart of the LED is a semiconducr chip. One end of the chip is attached  a support, which is the negative electrode, and the other end is connected  the positive electrode of the power supply. The entire chip is encapsulated by epoxy resin.

　　The semiconducr wafer is composed of two parts, one part is a P-type semiconducr, in which holes dominate, and the other end is an N-type semiconducr, which is mainly electrons. But when these two semiconducrs are connected, a "P-N junction" is formed between them. When the current acts on the chip through the wire, the electrons will be pushed  the P area, where the electrons and holes recombine, and then emit energy in the form of phons. This is the principle of LED light emission. The wavelength of light determines the color of light, which is determined by the material forming the P-N junction.

　　When the LED converts electrical energy in light energy, when the current flows through the LED components, the temperature of the PN junction will rise, forming the so-called luminous heating, that is, the higher the current, the higher the temperature, and the higher the brightness of the light. Many people here may say, in that case, why control the temperature of the LED?

　　understand this problem, let's first take a look at how high temperature affects LEDs and LED lamps.

　　The influence of temperature on LED

　　①LED is mainly composed of bracket, silver glue, chip, gold wire (copper wire), epoxy resin. In addition  bracket and epoxy resin, the damage of the other three materials can directly cause the LED  sp working, which is o high. The temperature of the above three materials is exactly the nemesis of the above three materials. In a high temperature environment, the light attenuation of the LED will increase, reducing the service life of the LED, and even worse, it can even burn the gold wire (copper wire) in an instant  cause the LED Direct damage.

　　② A single LED cannot directly meet the needs of use. Often accompanied by LEDs, there is also an LED power supply (driver). The power supply itself is a heating element and has its own temperature resistance requirements. If the temperature is o high, it will cause the power supply. The disabling or even damage of the LED lamps causes the LED lamps  not work normally.

　　Therefore, it is imperative  solve the temperature problem of LEDs and LED lamps, that is, heat dissipation.

　　Principle of heat dissipation

　　Heat dissipation in the traditional sense is the so-called heat transfer, and the principle of heat transfer has the following three points:

　　1 Conduction

　　As everyone knows, heat can be conducted through the medium, and it can be transferred from a location where the temperature is o high  a location where the temperature is o low. In this case, the conductivity of the material, the thermal resistance caused by the structure of the radiar, and the shape and size are all May interfere with heat conduction.

　　2 Radiation

　　The high school physics teacher ld us that the heat goes up. In fact, this is the so-called radiation. It is very limited  the surrounding environment and the material of the radiar itself.

　　3 Convection

　　People who buy a house should have heard the concept of a one-floor building. Sales generally say that such a building is very cool. It is true. The so-called convection is  dissipate heat through the flow of gas or liquid, and its heat dissipation rate generally depends on the flow. Speed, if you want  realize on the lamp body is difficult (considering facrs such as waterproof, safety regulations, etc.), but it is not without specific reference  the products shown below.

　　The heat dissipation of the above three points, the most commonly used in lamps and lanterns now is heat conduction, which is also the pic we focus on day.

　　Heat Conduction

　　Friends who read the above text should notice that there are three facrs that affect heat conduction: material, structure, and size.

　　1 Material

　　Speaking of materials, we have  talk about the composition of LED lamps. First of all, one of the most common LED lamps is composed of a heat sink (lamp body), LED, substrate, power driver, and optical components. Among them, the heating element has two LEDs and two drivers, and the heat sink has a radiar, a substrate, or an optical element made of aluminum (the amount of heat conduction is almost negligible).

　　heat sink

　　The radiars of LED lamps are generally made of aluminum, which can be divided in two categories, stretched aluminum mainly made of aluminum such as AL6060, and die-cast aluminum mainly made of ADC12. Among them, the thermal conductivity of ADC12 is 96.7w/m ℃, and aluminum materials such as AL6060 are 198~250w/m ℃. The latter is better than the former in terms of heat conduction. Someone may ask here, since aluminum materials such as AL6060 The heat conduction is so good, why is there still ADC12 appearing?

　　① ADC12 die-cast aluminum, it is mass-produced quickly, and can meet the general requirements of design aesthetics (almost the shape you can think of can be presented), but because of the low modification and high cost of designing molds, it is generally used when the size is not very large. For products that do not need  be modified, it is also relatively cheap, so it has occupied the shell market for a long time.

　　② Stretched aluminum has strong thermal conductivity, and the mold cost is generally one-tenth that of die-casting molds. The length change is also very flexible, and the processing and mass production are fast. However, it cannot completely occupy the shell market due  the following reasons: insufficient hardness, It is easy  deform, and the appearance can only be stretched, with few changes, which cannot meet the requirements of market appearance.

　　Based on the above two points, it can be concluded that heat-dissipating stretched aluminum is better than die-cast aluminum, and the appearance of the latter is better than the former, depending on the cost requirements and appearance requirements of the design.

　　Substrate

　　In addition  the housing, the substrate is also one of the important heat sinks. Commonly used heat sink substrates for LED lamps on the market include copper substrates and aluminum substrates. Among them, the thermal conductivity of copper substrates is better than that of aluminum substrates, but the price is relatively high. , A large part of designers or companies will choose aluminum substrate as a heat sink.

　　2 Structure

　　①The fin design in the following figure can be adopted in appearance.

　　②In the initial stage of design, the placement of electronic components should be well thought out  avoid common heat sources in the following diagrams.

　　③With the permission of the structure, it is best not  fix the position of the power supply under the light source, because according  the principle of heat circulation, the heat goes upwards. If there is really no way  control it, it is best  reserve the conduction distance  3CM or more (As for why, please Baidu heat conduction related knowledge). The design plan is shown in the figure below.

　　3 Size

　　I won’t elaborate on this. For example, one square meter of material can derive 1W of heat, and one square meter of material can derive 100W of heat. The concept is very clear, and there is no need  elaborate. It can only be recommended here, within a reasonable range. Choose reasonable size inside.

　　Misunderstanding of heat dissipation

　　Reading the above information, many people should understand that heat conduction is very important for the heat dissipation of lamps, so many people will choose better heat dissipation materials, so they are superstitious in the so-called high-tech high-tech