Discussion on the effect of precipitation process on COB phosphor light type products

With the domestic LED industry chain matures, performance of the product raw material optimization, the LED packaging manufacturers product performance difference gradually decreases, the competition for market share, the price war continues, product prices continue to refresh the record. The optimal combination of materials, equipment, large-scale production industry has become an important way to earn profits at the same time, the details of product promotion, will also be an important factor of packaging products stable performance, stable development details determine success or failure.

Siu Chi energy COB Dai Xiaodong Research Center (hereinafter referred to as "the author") visited some customers, most of the applications and technical personnel forecast, COB precipitation process product application will outbreak, because most of the international well-known COB manufacturers are using this technology, the appearance of high-end atmosphere, on the grade, the product colloid temperature is low, the same light The product surface power can be further improved, the optical density is bigger, with obvious advantages, most of the domestic COB manufacturers can precipitate product batch production, international COB manufacturers to gradually reduce the advantage. Then the process of light type products whether there is qualitative change? Here, the author of the fluorescent powder precipitation technology affects light type products.

The blue chip to excite the phosphor is the most common method of making white light, the ideal state, the fluorescent powder uniformly by the uniform blue light out surface will derive uniform white light products, light type perfect figure, but most COB products are not so large, luminous surface of chip, low power chip week Wai phosphor is fully excited, white color or blue chip, and from the fluorescent powder can not be relatively far completely excited, the color yellow, as shown in Figure two, which leads to problems, such as uneven blueheart abnormal macular, etc..

Usually we can modify the light-emitting surface or increase the number of chips, optimized arrangement, solve the optimization of rubber surface structure methods. The finished application end through the lens optical design, increase grain drying, grinding processing mode is optimized, but through the design of two optical lens optimization products light will sacrifice too much flux, and the open design high input on corporate profits, so the optimum design is the key of the whole lamp bulb high price, we not only The lamp shape design, we pay more attention to the quality of light products, we are faced with choices in power, heat, light, light price consideration, which may consider precipitation process lamp effect, how to light effect, but also need to test the lens (reflector) combination test or simulation.

The author has found the light distribution lens, light type fluorescent powder deposition process products uniformity than the conventional process, the light edge is jagged, light blue spots were local and so on, it seems to let us down, precipitation process did not bring us the perfect effect of light, of course, light precipitation technology products it is the Can optimize, but will increase the cost of sacrificing brightness. Part of the lens maker said, COB phosphor thin lens (reflector) to design challenges, lens requires more complex optical processing of stray light. Because some lens imaging problem is obvious, according to the convex lens or Finel imaging principle, the product will light the internal structure of the beads reduction precipitation process, products of fluorescent powder into bottom of the substrate, adhesive surface becomes more clear, chip arrangement is more obvious, when the lens is obvious precipitation process than the conventional precipitation process The more difficult the light distribution. Some of these products appear even blue spot.

I have always believed that the key to solve the problem is the nature and origin of the need to understand the problem, solve the problem from the source, to remedy only when the temporary measures are not universal. The distribution of the fluorescent powder deposition process and conventional process of micro analysis:

Conventional precipitation products even light, such as a map, and around the chip is arranged on the top of the fluorescent powder distribution, a relatively uniform light; light blue spot precipitation technology products, as shown in Figure two, the conventional chip for five surface light, above the chip fluorescent powder is covered, but the four sides of a chip without phosphor package. Other fluorescent powder into the bottom of substrate Department of plastic package without the fluorescent powder, blue chip side leads directly to the rubber surface, a light type in blue spot.

The face of the impact, light type precipitation process products on how to improve?

The author summarizes some methods to improve:

1, choose the chip height.

In order to increase the brightness of a chip, part of chip manufacturers through thickening chip increases the light output surface, increase the brightness, precipitation process products should not be used too thick chip;

2, the fluorescent powder thickness control.

Control of the phosphor precipitation degree, keep the chip side phosphor package, no blue chip overflow;

3, the chip density adjustment.

High density chip spacing is small, light density, if precipitation process is subtly solves the problem of light type, as shown below, a product chip spacing is small, no blue chip side overflow problem, light type products, two products are marked uneven spot. But the chip density is too high, the chip side light will not be derived, resulting in low efficiency of light products, the chip utilization rate is not high, the cost increase.

4, the product selection process.

High density blue light in phosphor, phosphor can be excited by blue light will be in the form of light and heat conversion ability, light can be easily derived colloid, but the reason is difficult to distribute the heat, the heat conductivity of silicone, fluorescent powder heat can not be quickly export, resulting in high temperature aging products COB colloid, glue crack problems in fact, with colloid Temperature is very large, so high wattage and high density products using colloidal precipitation process, the heat is small, there is no obvious blue chip side spillover effect is perfect. But a small number of watt products colloidal low temperature, using little precipitation process, product light type and no advantage, product recommendations based on the optical density and size of the colloid temperature process choice. (text: Dai Xiaodong)

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