What is SMD LED packaging

What is SMD LED packaging



SMD LED stands for surface mount LED, specifically, through this process, chip is mounted onto a small “desk”, then becomes an LED.

LED packaging process takes three steps:
1. Mount the chip onto a desk with adhesive;
2. Connect the chip to system with bond wire;
3. Cover the chip with phosphor to make the color.



Each packaging process is named after the dimension of LED, e.g., 3528 meaning 3.5*2.8mm.






2835, 3014, 3528



2835, 3014 and 3528 are three packaging process based on Epistar and similar dimension chips.




Generally speaking, SMD 2835 design is newer and more advanced than 3014 than 3528. Because 2835 has more effective thermal dissipation system, specifically, a larger heat sink than 3014 on the back, and 3528 has no back heat sink at all, therefore 2835 is able to take higher current and generates more luminous flux.


The form below is the common spec of these LED solutions in these days. The data is based on June, 2013.




The followings can be concluded from the form.
1.Larger chip, the better


Taking 3528 for example, manufacturer could use 10*16, 10*18 or 10*23 chip to make the LED, all can be driven by 20ma, three plans get different luminous flux. Because smaller chip would generate more heat while being driven by same current as the larger chip, it also has shorter longevity and worse quality. However, for most of lamp buyers it is almost impossible to know what brand and dimension of the chip is really being used, the only way is to conclude it from the lamp’s optical performance test.
2.A controversial trick


Higher drive current will make more luminous flux to one chip, and also more heat. 3528, 3014 and 2835 all use 10*23mil chip, but the drive current are different .It is controversial that because 3014 and 2835 have large heat sink, one chip in these packagings could be driven by higher current. However this has become the most popular design.




COB



COB stands for chips on board, which is a different solution than SMD packaging. Generally, an SMD LED is mounts onto a desk, then the desk is mounted onto a PCB, instead, COB skips the middle step and mounts the chips onto PCB directly, and thus, the cost is lower. Saving money is merely one of the advantages of COB.




SMD LED is a point light source solution, Putting many point light source in a lamp would cause certain optical problems, such as, lens flare and Double Vision COB packaging is an integrated area light source solution, it can solve the two problems above. Besides, it has lower thermal resistance due to its structure, and higher CRI could be reached by simply adding red chip to the light source.

Check out our COB LED high bay light and motion sensor LED floodlight.


Nevertheless, COB process still has obstacles in its luminance efficacy limit, but it is the tendency of LED light source solution.


Thanks for reading this article, and you are welcome to take a look at our LED lights.