Shanghai dragon company: plastic radiator for LED

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