Specific methods of build high-efficiency LED COB packaging products

As LED packaging technology innovation and implementation of energy saving policies at home and abroad, LED light source used in the lighting field are increasing, new form package Keep on launching. COB is the LED packaging products under this background of the industry. Compared with the traditional discrete LED packaging products, COB has a better heat dissipation ability, high luminous flux of output. We will focus on how to improve the efficiency of COB LED bulb and Looking for ways to meet the core value point of lighting following.

1.       COB has good heat dissipation capacity

When designing the LED encapsulation structure, should as far as possible to reduce the chip junction temperature. COB packaging chip is cooling way of the shortest, the main work can be rapid heat transfer to the metal substrate of the chip, Then passed to the heat sink, so COB have better heat dissipation capacity than traditional discrete components assembly. The current choice of COB metal substrate material selection are copper, aluminum, alumina, aluminum nitride, consider the overall costs, cooling capacity, corrosion, etc., the aluminum is the main choice as the metal substrate to produce COB.

2.       COB can achieve high-density flux output

When we are in the modularization design using the LED usually give light space not much, at the same time hope that there is high enough in the size of the small the brightness of the output, and almost impossible to find the solution on the discrete component LED, of course, some may choose 3535 ceramic or other product which is size small and flux is relatively high, but can't comparable to COB or MCOB high luminous flux of output.  Then the advantage of the COB in the product modularization reflected: help the modularization design and maintain the high luminous flux. COB driver design is very flexible, application side can be combined with the existing driving condition choose COB, suffice many alternatives from Low Voltage to high Voltage.

3.       COB packaging defects

COB has many advantages, but it is not the mainstream lighting of market. We are optimistic about the current COB, at the same time more should see its defects in order to find the reasons for restricting its application. First, COB light is still low efficiency, COB is a flat luminous, cannot have PPA chip side auxiliary light output as discrete LEDs, so will loss a portion of the light. Secondly, COB currently has not standardized form, most domestic manufacturers match the corresponding fixture, drive mode according to their respective partners manufacture COB, the shape of each one without unity, so will limit large-scale use of COB.

4.       Method to enhance COB light efficiency

Due to COB light on the problem of low efficiency, I thought that we should think about the solution from substrate Principle. LED encapsulation of photosynthetic efficiency improvement, like we often speak of external quantum efficiency, how to improve the packaging of products or the whole module flux while as the same as chip. First, the high reflectivity of the substrate material, the chip placement area directly affects the reflectance of the light output, regardless of the copper substrates, aluminum plate, a ceramic substrate, should follow this rule. And it is important  to note that at the time of assembly application COB, substrate shiny surface area also needs to consider, if not on the surface of the light-emitting reflective glass, reflective material should be outside of the shiny surface area. Second, larger particles and micromixer mixing effect degrees of phosphor, high light transmittance of encapsulated silica gel, which is identical with the traditional discrete LEDs luminous efficiency ascension .Third, solid crystal arrangement of the chip and drive mode spacing should be reasonable, under the same power, using the drive current of small programs to avoid excessive heat stays inside the substrate. In addition, when the light emitting surface is a little small, points silicone lens shape on the phosphor surface can not only increase the angle, but also can further improved the light efficiency.