In order to solve the serious light attenuation problem of LED roadway lighting products, LED street light manufacturers need to start with basic materials, solving the cooling problem from inside. For example, when light-emitting components stick with aluminum plates, heat conducting glue plays a rather important role. Some makers believe that heat conducting films and heat conducting pads have much better performance, the thicker the better. However, they do not take into account of the thermal resistance. In addition, heat conducting films or soft heat conducting pads actually cannot really fit the substrate surface. There are many pores, which is another form of thermal resistor. Under the interference of so many resistances, the heat conduction efficiency has been virtually reduced.
It does not mean that LED makers should find other materials to take place of heat conducting glue. In fact, heat conducting glue is still the most suitable material in LED package. Right glue may have quite low thermal resistance, such like screen printed soft ceramic heat conducting glue (SPSCHCG), which is quite different from traditional paste-fit heat conducting glues. SPSCHCG is a type of soft semi-liquid material. When coat this material up on the aluminum plates, heat conducting particles will penetrate into the pores of the substrate surface and fill them to full to form a completely flat plane. Therefore the thermal resistance can be reduced to a minimum level, and the heat generated by LED roadway lighting products can be quickly conducted outwards. In addition, due to the good ductility of SPSCHCG, this material can expand and contract along with aluminum plates in the high temperature of baking and reflow. The stress is very small, will not cause a warp or burst of aluminum plates.
With the continuous improvement of packaging technology, carrier board design and cooing module structure, the production costs of LED roadway lighting products are also further reduced. But only a few Chinese manufacturers spent energy and money on the research and development of materials. In issues of solving technical problems and reducing costs, they are more in favor of purchasing. In this part, manufacturers from North America and Japan have much better performances. They are more like to find breakthroughs on basic materials, reducing production costs by innovations.