In the field of LED display screens, COB (Chip on Board) LED display screens and SMD (Surface Mounted Devices) LED display screens are two mainstream technical solutions.
Each of these two technologies has its own unique advantages and applicable scenarios. Below we will analyze and compare them in detail from multiple dimensions.
Technical Principle and Process Introduction
COB LED Display Screen
COB LED display screen, namely Chip on Board LED display screen, is a high-end display technology that directly encapsulates LED chips on PCB boards.
Its core technology is to directly solder the LED light-emitting chip on the PCB board, then coat the entire unit module with a film, and finally splice it into a whole LED screen.
The COB packaging process uses thermal conductive epoxy resin to place the silicon chip directly on the substrate surface, fix it firmly on the substrate through heat treatment, and then use wire welding to establish an electrical connection between the silicon chip and the substrate.
SMD LED display
SMD LED display encapsulates the light-emitting chip (wafer) into lamp beads, then solders the lamp beads to the PCB board to form a unit module, and finally splices them into a whole LED screen. The SMD surface mounting process technology mainly encapsulates the lamp cup, bracket, wafer, lead, epoxy resin and other materials into lamp beads of different specifications, and then solders the lamp beads to the circuit board through a high-speed placement machine and high-temperature reflow soldering.
Product feature comparison
Image display effect
- COB LED display: Due to the overall coating above the light-emitting chip, the light source becomes a surface light source after scattering and refraction of the coating. Compared with point light sources, surface light sources have a better overall visual perception, no graininess when watching, and can reduce the stimulation of light sources to the human eye, which is more suitable for long-term close-up viewing. The contrast of COB screen can be higher, up to 20000:1 or more, with bright and colorful colors and better details. However, color difference is prone to occur when squinting.
- SMD LED display: The lamp beads are single-body luminous, showing a point light source effect. Although the contrast ratio of SMD screen will not exceed 10000:1, the display effect is still relatively clear when viewed from the front.
Stability and maintainability
- COB LED display: It has a high protection level, good waterproof and moisture-proof performance, and the surface is smooth and hard, and has strong pressure resistance. Because it is a fully sealed structure, the screen stains can be directly wiped with clean water. However, it cannot be repaired on site and needs to be returned to the factory for repair using professional equipment.
- SMD LED display: The overall protection is weak, it is easy to knock and drop the light, and the waterproof, moisture-proof and dust-proof performance are poor, and it cannot be wiped. However, it is convenient to repair on site, which is conducive to later maintenance.
Energy efficiency and cost
- COB LED display: Most of them are flip-chip processes, and the light source is not blocked, so when the same brightness is achieved, the power consumption is lower. In addition, the overall film transparency used is high, which further improves the economic use. However, due to the high technical threshold of COB production process and low product yield, the current cost is still higher than SMD screen.
- SMD LED display: The luminous crystals in the lamp beads of mainstream products are mostly positive-mounted, and there are leads above the light source. Due to the low technical threshold, there are more than a thousand manufacturers in the country, with sufficient competition and relatively low costs.
Application fields and market demand
COB LED display
COB LED display is widely used in high-end occasions for small-pitch LED display screens due to its advantages such as high definition, high brightness, high contrast, and high color reproduction, such as multi-functional hall conference rooms, studios, military dispatching and command, power dispatching, aerospace monitoring, public security command centers, traffic monitoring management, industrial production dispatching, security monitoring, water conservancy monitoring and other fields. These occasions have high requirements for the stability and picture quality of the display screen, and COB screens can meet these requirements.
SMD LED display
SMD LED display screens are more used in some cost-sensitive scenarios, such as outdoor billboards, commercial displays, etc. Although its display effect and stability are not as good as COB screens, it still occupies a certain market share due to its lower cost and relatively stable performance.
Summary
To sum up, COB LED display and SMD LED display each have their own advantages and applicable scenarios.
COB screens have won the favor of the high-end market with their excellent display effects, stability and energy efficiency, while SMD screens have occupied a place in the mid-to-low-end market with their low cost and certain performance stability.
In the future, with the continuous advancement of technology and the continuous changes in market demand, both technologies will continue to develop and improve.