First, outdoor lighting designers must consider the working environment of outdoor LED lamps
Due to the complicated working environment, LED outdoor lighting fixtures are affected by natural conditions such as temperature, ultraviolet light, humidity, rain, rain, sand, chemical gas, etc. Over time, the problem of LED light decay is serious. Therefore, in the end, outdoor lighting designers should consider the impact of these external environmental factors on LED outdoor lighting when designing.
Second, outdoor LED lamps should pay attention to the selection of heat dissipation materials
The outer casing and the heat sink are designed to be integrated to solve the heat generation problem of the LED. This method is preferable, and aluminum or aluminum alloy, copper or copper alloy, and other alloys with good heat conductivity are generally used. The heat dissipation has air convection heat dissipation, strong wind cooling heat dissipation and heat pipe heat dissipation. (Jet cooling heat dissipation is also a kind of heat pipe cooling, but the structure is more complicated.)
The choice of what kind of heat dissipation method has a direct impact on the cost of the luminaire should be considered comprehensively, and the plan should be selected in conjunction with the design product.
The design of the lampshade is also crucial. Currently, there are transparent plexiglass, PC materials, etc. The traditional lampshade is a transparent glass product. What kind of material is selected is related to the design of the product grade. Generally speaking, the outdoor lamp The lampshade is a traditional glass product that is the choice for long life and luminaires. The lampshade made of transparent plastic, plexiglass, etc. is better for the indoor lamp, and the outdoor life is limited. Because of the outdoor sunlight, ultraviolet light, sand dust, chemical gas, temperature difference between day and night, etc., the aging life of the lampshade is shortened. Secondly, the pollution is not easy to clean and clean, so that the transparency of the lampshade reduces the light output.
Third, the packaging technology of outdoor LED chips
At present, LED lamps (mainly street lamps) produced in China are mostly assembled by using 1W LEDs in multiple strings and parallels. This method has higher thermal resistance than advanced packaging technology, and it is not easy to produce high-quality lamps. Or it can be assembled with 30W, 50W or even larger modules to achieve the required power. The packaging materials of these LEDs are encapsulated in epoxy resin and encapsulated in silicone. The difference between the two is that the epoxy resin package has poor temperature resistance and is prone to aging over time. The silicone package is better in temperature resistance and should be selected when using.
It is better to use a multi-chip and a heat sink as a whole package, or to use an aluminum substrate multi-chip package and then connect the phase change material or the heat-dissipating grease to the heat sink, and the thermal resistance of the product is higher than that of the product assembled with the LED device. Less one to two thermal resistance, which is more conducive to heat dissipation. For the LED module, the module substrate is generally a copper substrate, and the connection with the external heat sink is to use a good phase change material, or a good heat dissipation grease to ensure that the heat on the copper substrate can be transmitted to the external heat sink in time. Going up, if the processing is not good, it will easily cause the heat accumulation to cause the module chip temperature to rise too high, which will affect the normal operation of the LED chip. The author believes that: multi-chip package is suitable for the manufacture of general lighting fixtures, module packaging is suitable for space-limited occasions to manufacture compact led lamps (such as headlights for automotive main lighting, etc.).
