what is the difference between COB and SMD?

Now in the application field, COB and SMD two technologies are “equally divided into spring color”, but in the field of small pitch LED, COB is becoming the major manufacturers are competing for research and development of the industry's mainstream technology. So what is the difference between COB and SMD?
Stability

SMD method using lamp bead bracket and epoxy resin, due to the coefficient of expansion is not the same, in the process of reflow soldering is very easy to cause the bracket and the epoxy resin encapsulation shell fall off, there is a gap in the later use of the phenomenon of dead lamps, resulting in a high defective rate.

COB integrated package does not need reflow soldering to stick the lamp, avoiding the problem of gaps between the lamp bead bracket and epoxy resin caused by high temperature welding in the welding machine, and the product is not easy to appear dead lamp phenomenon after leaving the factory. Surface use of lens package, effective protection of light-emitting diode chips, enhanced protection.

Excellent heat dissipation

SMD products mainly through the gel and four pads heat dissipation, heat dissipation area is small, the heat will be concentrated in the chip for a long time will cause serious light attenuation phenomenon, or even dead phenomenon, reducing the service life and quality of the display.

COB integrated packaging products encapsulate the chip on the PCB board, directly through the entire PCB board area for heat dissipation, heat is easy to emit, extending the life of the display.

Anti-compression and anti-collision performance

SMD high-density display using solder to paste the LED lights on the light board, is a raised structure, each light has only four very small pads, it is easy to squeeze, touch and other reasons for the drop lights, dead lights phenomenon.

COB integrated package will be light-emitting diode chip through the solid crystal encapsulation on the PCB board, the surface of the use of lens package, smooth and flat, more resistant to wear.

Moisture, dust and anti-static performance

SMD products display the exposed pin pads, water or moisture is prone to short-circuit between the pin pads; the use of the mask uneven, dusty and difficult to clean up; the use of metal brackets are prone to oxidation; exposed pin pads, it is easy to be affected by electrostatic discharge, the phenomenon of dead lights. Waterproof, moisture-proof, dust-proof, anti-static, anti-oxidation deficiencies exist.

COB integrated encapsulation display adopts panel encapsulation technology, there is no exposed lamp foot problem, with moisture-proof, dust-proof, anti-static and other functions.

Wide Viewing Angle

SMD mode display due to the higher lamp cup package, precision errors in the SMD process, mask unevenness and other reasons, resulting in a reduced viewing angle.

COB small pitch display integrated package without mask protection, left and right viewing angle increased to 160 °. SMD discrete device by the bracket blocking, the viewing angle is only 140 °.

Anti-noise lens technology

SMD: Due to the selection of the chip wavelength band spanning a large, each pixel point of the chip has a tiny stray color noise phenomenon.

COB: Pick the chip with very small wavelength difference and adopt unique optical lens technology, so that the brightness and color difference between pixel points become imperceptible to the naked eye, completely free of picture noise, and the color is more saturated and pure.

And COB package is mainly to solve the problem of LED small pitch, its product line is also more concentrated in the P1.25 below, like P1.25, P0.9, P0.6, etc. are almost all used in the COB structure. Smaller point spacing can bring higher resolution, thus displaying images with higher clarity and better picture quality.