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A new technics -Vapor chamber applicate in Semlight new LED high bay light


Nowadays, high power COB LED high bay light encounter the heat dissipation problems: far more concentration heat on LED. To solve this big problem, LED industry tried various settlements. Technical of vapor chamber is a typical heat dissipation solutions.

Since 2006, SEMLIGHT SEMICONDUCTOR LIGHTING CO.,LIMITED, invest  hundreds of thousands of US dollars on the vapor champer producing craft and its equipments , our development team finally developed vapor chamber specially for high power COB LED high bay, as LED packaging base board. And recently, this technic honored National Innovation Invention Prize, regarded as a fresh light in China LED lighting Industry.        Production of vapor chamber:

We use sintered copper powder as liquid absorption capillary core structure. Since inner cavity area of vapor chamber is relative big but cavity gap is relative small, in the same time ,setting liquid absorption capillary core structure in the small cavity need to solve suitable cooper powder un-finalize sintering, including welding the gap in the vacuum tube,  inject heat transfer working medium, forming vacuum and keep vacuum etc a lot of problem. Finally to assure that heat transfer performance and board surface un-deformation. It looks vapor chamber is simple but the production technic is very difficult. Our company mastered the key technics of vapor chamber : Inner cavity core structure all linked, Support flow confined tensile strength.Sintering and silver soldering process, Working medium filling ,Vacuum degassing,Performance test. 4 patents be applied already.        Structure of Vapor chamber:

Vapor chamber is a totally sealed panel cavity composed of base board , frame, cover board.Liquid absorption capillary core structure in wall of cavity, the capillary core structure could be metal wire net, micro groove , cello silk, also could be metal powder un-sintering core and several structure combination .In cavity, support structure needed when necessary, to avoid deformation because air suction sage and heated up after vacuum degassing.

Since changes in capillary micro structure on  wall of vapor chamber,vacuum cavity and liquid working medium( industrial pure water or acetone), so it own perfect constant temperature and conduction features. It can make high heating flux from a point to a big heating dissipation area instantaneously. And then transfer the heat via the cooling fins

LED light working stable or not, life span long or short, all related with capacity of heat dissipation. Since SEMLIGHT SEMICONDUCTOR LIGHTING CO.,LIMITED的LED high bay LED with vapor chamber heat dissipation technics, assured its lift time to 50000 hours above, make ours LED become authentic long-life new light source


 

Semlight LED high bay light Radiator Technical Introduction-Micro Grooves composite phase change


Since 2006 Semlight company began working on research and development of high-power LED high baylight , and has made a number of technologies innovation breakthroughs in the field of high power LED high baylight. Its mission is to develop a new generation of LED lighting products with more green, environmentally friendly, energy-saving features.

Above 150w led high bay light, Semlight adopts Micro Grooves composite phase change radiator. Working principle as follows: When one end of the radiator heat, its internal heat transfer medium filled (usually industrial water or acetone) will heat vaporized into vapor phase fluid, vapor phase fluid rapidly transfer heat to the heat sink through the internal micro-channel structure the other end or other parts. When the fluid reaches the vapor condensing end, will become condensate liquid form, releasing latent heat of vaporization, then the liquid fluid from the interior of the subtle groove group, returned to the heating side, so that through continuous media condensation and evaporation cycle, to achieve a micro grooves composite phase change heat sink fast, cooling function.

Micro Grooves composite phase change has following features:

1. Super thermal capacity: Micro Grooves composite phase change LED high bay radiator has superconducting heat conduction, the heat capacity is 10,000 times than the aluminum plate.Such technology make heat from led transfer to the area large aluminum fins. LED chip operating temperature is below 90 ℃. Thermal conductivity of copper is about 400W / (m * ℃); Compare with copper,micro capillary groove composite phase change has superconducting heat capacity. With a long 50cm, diameter 1cm  solid copper heat energy transport 200W at 100 ℃ operating temperature, copper ends of the temperature difference of up to 70 ℃, but half of the length and weight, and the same work condition, micro-groove group phase change radiator reach the same effect, and the temperature drop of only 0.5 ℃, the experiment shows micro-groove group phase change technology has superconducting transition heat conduction.

2. Super cooling capacity: Take hot flow density reached 400W / c ㎡, its ability 1000 times higher than the water-cooled, approximately 100 times higher than the heat pipe. Take the heat capacity 100 times than forced water cooling, 1000 times higher than the forced air cooling. Under a standard atmospheric pressure, the boiling point of water is 100 ℃, 1Kg water temperature from 99 ℃ to 100 ℃, require the thermal energy of 4200 joules; 1Kg 100 ℃ water absorbing heat becomes steam 100 ℃, the temperature does not change, but absorb 2260000 joules. Water cooling for the sensible heat exchange, low heat, MGCP technology is latent heat exchange, super heat capacity . That 1Kg water rise 1 ℃ only need 4200 Joule heat, 1Kg 100 ℃ water absorbing heat becomes steam 100 ℃, the temperature does not change, but absorb 2260000 joules. the absorbed heat is 500 times different, therefore, there is a huge difference between the heat transfer capacity.

3. No-power consumption cooling: passive cooling without fans or pumps, no cooling energy, no power running, saving energy. Micro Grooves composite phase change technology make use of high-power electronic devices generate heat energy to take the heat medium kinetic and potential evaporation, steam flow to the condenser heat condensed into a liquid by means of heat taken micro-groove group capillary forces and liquid gravity back into the high-power electronic heat taken devices,in order to achieve closed cooling cycle without external power.

4. Light weight, small size: the same power LED high bay light, micro capillary groove composite phase change weight radiator is 50% less than aluminum extrusion heat sink, the volume is less than 60%.

High reliability: stable, no startup problems, the reliability is much higher than the fan, water cooling and heat pipe radiator.

The difference between Semlight Micro Grooves composite phase change radiator and heat pipe as below:

1, the form is similar with that of heat pipe, but there are essential difference in the heat transfer mechanism, structure, and performance;

2, using powerful micro-size composite phase change heat transfer enhancement principle; heat pipe is only an ordinary film evaporation;

3, no inherent boiling heat pipe, entrainment, capillary forces, and many other heat transfer limit;  

4, no such problems as that from heat pipe: high contact resistance and complex equipment;

5, no heat pipe problem starts with work stability aspects;  

6, the same temperature per unit area, its heat removal capacity is about 100 times higher than that of the heat pipe , and the system is simple and compact.

Semlight led high bay light due to use this advanced cooling technology, chip junction temperature is 15-20 ℃ lower than that of conventional aluminum radiator.  Thus, LED light decay is very small, greatly extending the life of   the LED light source.


 

New technical : PCB with DLC adopt on SEMLIGHT 65W E40 led street light  


SEMLIGHT developed a new style 65W E40 led street light: using PCB with DLC. Heat dissipation is always a big problem to LED engineer, with the temperature increment the luminance will decrease, the luminous decay will increase also, even burn out. When LED power rise, the heat dissipation is especially problem. From earlier glass fiber PCB to nowadays aluminum substrate PCB, the heat dissipation is still undesirability. Currently, general aluminum substrate PCB use Epoxy as insulation layer on aluminum substrate, then make circuit on Epoxy layer. Heat conduction ratio of Epoxy layer( 0.5W/mK)  is lower than aluminum (275W/mK) hundreds times, the heat generated on LED chip is difficult to diffuse. However, SEMLIGHT LED street light, using PCB with DLC, which be plated on LED metal basic board, formed the high performance heat transfer plating film, compare to copper(400W/mK), DLC heat conduction ratio higher to 500W/mK above, moreover insulation performance is excellent, so Print Circuit Board with DLC plating level could realize noticeable heat dissipation effect. SEMLIGHT using PCB with DLC at E40 65W led street light have been doing mass production already, as replacement for traditional 200W HPS or MHL.  

Since PCB with DLC new technical adopt, SEMLIGHT 65W E40 led street light enable heat generated on LED chip be diffused instantly, decrease junction temperature of LED ,so that LED chip keep work at lower temperature, can reduce LED luminance decay, extend the led street light life time.