Recently plastic radiator also attracted people's attention. Normally good thermal conductivity of the material is usually a good conductivity of the material, which in turn conductive properties of plastic, its thermal conductivity is poor. This is inevitable. So it is clear that the metal is better than plastic. And so it is. So, is not plastic can not be used to do the radiator? Not so!
International recently developed a variety of conductive plastics, the materials are mostly in engineering plastics and general plastic material, such as PP, ABS, PC, PA, LCP, PPS, PEEK etc.. The metal is then filled with some metal oxide powder, carbon, fiber or ceramic powder. For example, polyphenylene sulfide (PPS) and large particles of Magnesium Oxide (40 ~ 325 mesh) can be mixed to form a kind of insulating thermal conductive plastic. The typical range of thermal conductivity is 1-20W/m-K, some grades can reach 100W/m-K. This value is about 5-100 times the traditional plastic, general plastic thermal conductivity is only 0.2W/m-K. However, in order to get a high thermal conductivity and add too much metal powder, it will become conductive. That cannot be applied on certain occasions. The performance of some of Coolploy's conductive plastics is as follows.
E4505 (PC): 10w/mk thermal conductivity of thermal conductive application: shell and radiator
D5108 (PPS): 10w/mk application: thermal conductivity of thermal insulation board / chip
D5506 (LCP): 10w/mk application: thermal conductivity of thermal insulation board / chip
D8102 (TPE): 3w/mk thermal conductivity of thermal insulation: application interface
E5101 (PPS): 20w/mk application: thermal conductivity of thermal conductive radiator.
Why conductive plastics can be made into the radiator? The cooling performance than the traditional and aluminum radiator? It can be even better! Can you believe it?
We know that, in addition to any radiator, can quickly put heat from a heat source to export to the surface of the radiator, and finally on the convection and radiation heat into the air. High thermal conductivity, only to solve the problem of rapid heat transfer, and heat dissipation is mainly determined by the area of heat dissipation, shape, natural convection and thermal radiation, which almost has nothing to do with the thermal conductivity of the material. So as long as there is a certain degree of heat transfer capacity, plastic radiator can still be a good radiator!
In general, if the heat from the heat source to the heat sink surface distance is less than 5mm, so as long as the heat conduction coefficient is greater than 5, the heat dissipation is dominated by convection, and heat conduction is not what. This can be seen from the following curve.
Fig. 1 Relationship between thermal conductivity and conduction convection
Figure 1 presents the relationship between the thermal conductivity and convection heat conduction. The abscissa is the thermal conductivity and the ordinate is the temperature difference between the heat source and the environment. Curves of various colors are the distance between the heat source and the surface of the radiator. If the distance is less than 5mm (green curve), as long as the thermal conductivity is greater than 5, its heat dissipation is completely determined by convection. The smaller the temperature difference, the smaller the distance, the less important the thermal conductivity.
And for the ideal radiator, about 7 into heat by convection, and 3 into heat by radiation.
And radiation capability of thermal conductive plastics is not inferior at. The following is the thermal radiation coefficient of various materials.
Material Science
steel
cast iron
aluminum
copper
Black plastic
Polishing without oxidation
0.05-0.1
Zero point three
0.02-0.1
Zero point zero six
0.8-0.9
Rough oxidation
0.5-0.6
Zero point seven five
0.3-0.4
Zero point five
Severe oxidation
0.8-0.95
0.8-0.95
0.4-0.45
Zero point eight
So it can be said that if the radiator exactly the same two shapes, one is made of aluminum, a heat conduction is made of plastic and aluminum radiator if do not by blackening the cooling capacity, the radiator is not made of black conductive plastics! Because the two convection heat dissipation is the same, and radiation cooling is better plastic!
The following plastic cooling in a Shanghai new materials company as an example, the material index:
Main performance parameters
Therpoxy
Thermal denaturation temperature
180 degrees @3.2 mm
Thermal conductivity
2.9 w / M
Surface resistance
>1012 ohm
breakdown voltage
4000 volt
Flame retardant
UL94 V0@1.3 mm
Hot wire GWIT
750 degrees @1.3 mm
Compared and aluminum radiator commonly used, can not be ignored and some other advantages of plastic heat conducting materials.
Cast aluminum radiator
Thermal engineering plastics
Thermal conductivity
Relatively high
Relatively low metal
Cooling effect
commonly
Pretty good
Insulation property
No insulation
Excellent insulation
Processing method
Die casting
injection molding
Led connection
Mechanical bonding, bonding, welding
Mechanical bonding, bonding, welding
Processing temperature
>500 degree
>250 degree
Two processing
Need
Unwanted
System cost
secondary
higher
Compared with traditional materials, conductive polymer has high flexing resistance and tensile stiffness, but the impact strength is poor, and its inherent low expansion coefficient can effectively reduce shrinkage.
Can actually think the biggest advantage is insulation. Aluminum radiator due to its good conductivity are often a factor in non isolated power supply concerns on CE or UL certification, and the use of plastic radiator can also use non isolated power supply and not have to worry about the safety problems.
In addition, its density must be lighter than aluminum. Density of aluminum
Contact: mack
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E-mail: mack@archled.net
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