With the continuous innovation of LED growth light, horticultural production is at the forefront of the revolution. However, the British Cambridge Nanotherm company marketing manager John Cafferkey said, this revolution's success may depend on how to find to improve the thermal efficiency of LED modules.
The horticulture industry people, now is a good time. It can be said that the industry, few people are aware of our current production of agricultural products is what kind of fundamental change, and has some profound influence.
Over the years, high pressure sodium (HID) has been used to supplement the sun. The use of these devices is economy, a key factor is to enable farmers to HPS in a controlled environment in the indoor cultivation of crops, and can arrange the time more flexible (regardless of season, is often the year).
Although the high-pressure sodium lamp has become the main choice of many horticultural growers, but they are quickly replaced by LED. Compared with the high pressure sodium lamp, LED can be opened and closed fast, easier to adapt to the automatic growth cycle. Moreover, LED can also send a specific wavelength of light, it can be adjusted according to different stages of different crops and the growth cycle of".
First of all, the operating costs of LED significantly reduce the expansion of crop area, including many because of the lighting requirements or sales price cheap but not suitable for crops growth light. In other words, LED lighting is turning from the high price of agricultural products and agricultural daily.
Secondly, low operating temperature means farmers can more closely in the form of planting crops, without causing thermal damage to the plant, which makes the vertical agricultural applications such as possible.
The waste heat is still a problem faced by LED design
The LED package is covered by the lens, to isolate the air, and can spread the light. Is not good, is the adiabatic lens package. Therefore, heat generated by the LED radiation cannot pass out, like high pressure sodium lamp. On the contrary, the heat must be poured out through the bottom of the LED design.
Moreover, the removal of heat from the LED is becoming a pressing issue. Due to cost considerations, designers are seeking higher power LED (1-5W) into a smaller space, in order to reduce the design cost of materials. In this way, a single LED to run at a higher power density, will bring great challenges to the thermal management.
The basic elements of the design of LED high heat dissipation efficiency
Assume an example we use "package design" LED. The separate LED chip is encapsulated in the radiating substrate (the "LED package" can be easily mounted to the PCB). In general, the substrate used below is the ceramic chip. Although the price is expensive, but the ceramic is excellent heat conduction and diffusion.
The next stage of heat transfer must be carried out on the substrate. The printed circuit board can not meet the standard cooling demand for horticultural lighting, because the glass fiber / epoxy resin composites are good heat conductors. For this reason, the metal substrate (MCPCB) is usually used for the design of high power LED.
MCPCB what is it? In all MCPCB, there are several similar structural elements. First there is a copper circuit layer, and a dielectric layer, the circuit below above the metal is separated, to prevent the short circuit. Finally, there is a metal plate, usually aluminum, but sometimes copper, effective components of heat transfer to the system level (such as fins).
Put forward the challenge of effective thermal management of MCPCB dielectric
As expected, the MCPCB of the circuit board and the circuit board copper aluminum layer is excellent thermal conductivity. The dielectric layer is not the same. Found in the industry, to find a dielectric (breakdown voltage is reached right) but has a high thermal conductivity material is a real challenge.
The most commonly used method is made with a layer of epoxy resin medium, ceramic crystal doped conductivity, in order to improve the overall thermal conductance. However, before the epoxy resin is brittle and began to break down, to add a lot of ceramic. Even if the market is the best material for horticultural lighting system can not meet the heat demand.
In order to realize the sustainable development of horticultural lighting applications, thermal conductive epoxy resin many of today's designers are demanding than ceramic filled can provide a higher rate of plate. Obviously, this requires a new method.
Nano ceramic: a new method of effective thermal management in MCPCB
A Cambridge based nanotechnology company has developed a new method to solve the "dielectric" problem, using a unique method to construct the dielectric high thermal efficiency.
The company uses patented electrochemical oxidation (ECO) process, the aluminum surface MCPCB into thin (10-30 m) of alumina (Al2O3) layer.
Although alumina in thermal efficiency is not the best material, but the dielectric layer thickness played a very good effect. Because of the heat need only a few microns, the overall thermal performance circuit, nano ceramic dielectric and aluminum reached 115 W/mK.
Finally, gardening lighting designers hope that their products are cool, smaller, lighter, more cost-effective. They want to make sure that the product can continue to use life. All of these factors for horticultural lighting industry and the sustainable development is very important to realize the new wave of agricultural technology. With the continuous development of the market, can expect to see the nano ceramic will become the core of gardening design LED. (compiled: LED James)