Why the led light heat sink is so important for a led lighting product?
The lighting manufacturers always concern much about the led lighting product heat dissipate solution.
By now, the biggest technical problem of LED lighting fixtures is the heat dissipation problem.
In the luminaire scheme using the LED light source, since the LED light source operates at a low voltage (VF=3.2V) and a large current (IF=300-700 mA), the heat is very strong, and the space of the conventional light product is limited. It is difficult to derive heat quickly.
after the LED light source is powered up, about 30% of the electrical energy is converted into light energy, and the rest is converted into heat energy.
Therefore, it is a key point to design the LED luminaire structure to dissipate the thermal energy as soon as possible.
Many people try variety of cooling solutions, the results are still not satisfactory, and become a problem with LED lighting. Looking for easy to use, good thermal conductivity, and low-cost heat sink materials are always difficult point.
Cooling way for LED lighting
As the LED light source itself does not have infrared and UV rays, the LED light itself has no radiation heat dissipation function.
The heat dissipation way of LED lighting lamps can only be derived through the radiator which is closely combined with the LED chip board.
Thermal energy will be dissipated through heat conduction, heat convection and heat radiation.
How the heat sink working ?
Any heat sink, in addition to the rapid transfer of heat from the source to the surface of the radiator, relies mainly on convection and radiation to transmit heat to the air. Thermal conduction only solves the heat transfer path, in fact thermal convection is the main function of the heat sink.
The heat dissipation performance is mainly effected by the heat dissipation area, shape, and natural convection strength. Thermal radiation is only an auxiliary function.
In general, if the distance from the heat source to the surface of the heat sink is less than 5 mm, then as long as the thermal conductivity of the material is greater than 5, the heat can be derived, and the rest of the heat must be dominated by heat convection.
For most LED lighting sources, due to high heat operation, we really suggest to use aluminum alloy with high thermal conductivity.
In commercial led lighting Manufacturer, usually there are die-cast aluminum heat sink, extruded aluminum heat sink, and stamped aluminum heat sink.
Die-cast aluminum heat sink
is a kind of technology for pressure casting parts. The liquid zinc-copper-aluminum alloy is poured into the inlet of the die-casting machine, and die cast a shape heat sink defined by designed mold.
The die cast heat sink unit price is controllable, but the heat dissipation fins can’t be made thin, so it’s difficult to make the heat dissipation area large. Normally used die-cast materials for ADC10 and ADC12.
They have been widely used by China led lighting factories on the low wattage regular led downlights ,wall lights product due to the low unit cost and so far the result is good.But for some customize products, die cast are not the good choice due to the expensive tooling cost。
Stamped aluminum heat sink
The quality of stamping parts is small and the material utilization rate is high, which is a low-cost solution.
It is stamped and stretched on steel and aluminum alloy plates by punching, making it a cup shape radiator.
The inner and outer periphery of the stamped heat sink is smooth, and the heat dissipation area is limited due to the wingless. Commonly used aluminum alloy materials are 5052, 6061, 6063.
This type heat sink usually used on the led bulb for the low cost but not suitable for other light fixtures.
Extruded aluminum heat sink
The liquid aluminum is extruded through a mold, and then the profiles is machined and cut into a heat sink of a desired shape.
The heat dissipating wings can be made very thin, and the heat dissipating area is maximized. When the cooling fins work, the air convection heat is automatically formed, and the heat dissipating effect is better. Normally use materials AL6061 and AL6063.
This is the most high cost performance ratio for now and many LED lighting manufacture use them as major method. You can easy to find them in many commercial led lighting products.
Plastic aluminum heat sink
It is a heat sink with a heat-conductive plastic outer casing aluminum core. The heat-conducting plastic and the aluminum heat-dissipating core are formed on the injection molding machine at one time.The aluminum heat-dissipating core is embedded, and it is required to be processed in advance.
The thermal conductive plastic density is 40% smaller than that of die-cast aluminum and ceramics. The weight of the same shape can reduce the weight of the plastic-coated aluminum by nearly 1/3;
compared with the all-aluminum heat sink, the cost is low, need shorter time, and the processing temperature is low; The finished product is not easy to break;
The only problem for plastic aluminum heat sink are the higher cost compare to the all aluminium one. That’s why the plastic aluminium is not popular for application of downlights, but it is expected to increase little by little.
High thermal conductivity plastic heat sink
High thermal conductivity plastic heat sink is a full plastic heat sink which has recently developed rapidly. Its thermal conductivity is several times higher than that of ordinary plastic, up to 2-9w/mk, and it has excellent heat conduction and heat radiation capability.
The new insulating heat dissipating material that can be applied to various power lamps can be widely used in various types of LED lamps from 1W to 200W.
The high thermal conductivity plastic radiator can be produced in traditional injection molding and extrusion machines.This type of LED lighting fixture is easy to pass the strict safety inspection of CE, TUV, UL and so on.
Once formed, the finished product has a good finish and do not need more process which greatly improve the efficiency of the production. And it can design in all kinds of shape so that the designer’s design concept can be fully utilized.
The HVLED uses a high voltage (VF=35-280 VDC) and a small current (IF=20-60 mA) to operate, reduced the heat of the HVLED lamp bead.
The high thermal conductivity plastic heat sink can be designed with many precise cooling fins. The cooling fins can be made very thin and the heat dissipation area is maximized. When the cooling fins work, the air convection heat is automatically formed, and the heat dissipation effect is better. The heat of the LED lamp beads passes through the high thermal conductivity plastic directly to the heat sink, which dissipates heat quickly through air convection and surface radiation.
Especially suitable for the application of fluorescent tubes and high-power industrial and mining lamps.