Core Differences Between GOB and COB in LED Display Packaging

2 views admin 2026-01-15

In the field of LED display packaging, the core differences between GOB and COB stem from the essential positioning of their packaging systems: GOB is a protective upgrade solution for traditional SMD packaging that retains independent SMD lamp beads throughout the process; COB is a brand-new chip-level packaging system that skips the lamp bead prefabrication process and has no independent lamp bead structure. The technical characteristics, performance, and application suitability of the two are all based on this core difference, and all statements are in line with actual industry technical specifications and application status.

Fundamental Differences in Packaging Principles and Process Routes
COB (Chip On Board) is a new packaging mode originating from the chip end. Its core lies in directly fixing vertical or flip-chip LED chips on the PCB substrate without prefabricating them into SMD lamp beads, realizing electrical connection through wire bonding, and then completing production through processes such as phosphor coating, integral packaging protection, and cutting and board separation. In the entire process, the chip is directly interconnected with the PCB substrate without an independent lamp bead link, making it a typical "chip-level" packaging process.

GOB (Glue On Board) is essentially a supplementary upgrade of SMD packaging, and its process is built on the mature SMD packaging foundation: first, complete the procurement and reflow soldering fixation of SMD lamp beads, and after module testing and surface cleaning, pour high-transparency special protective adhesive on the module surface, and complete the finished product testing after curing treatment. This process does not change the core electrical structure of SMD packaging, but only adds an integrated protective layer for lamp beads and solder joints through the glue pouring process, retaining the essential characteristics of SMD point light sources.

Core Differences in Key Performance

1. Pixel Density and Resolution Freed from the physical limitations of lamp bead brackets, COB has a higher upper limit of pixel density, which is mainly used in indoor ultra-small pitch scenarios from P0.4 to P1.2, and is the core technology to achieve ultra-high-resolution display. Restricted by the size of SMD lamp beads, GOB has a lower resolution upper limit, which is mainly suitable for medium and high pitch scenarios from P1.0 to P2.5, and it is difficult to break through the pitch lower limit of P0.8.

2. Protection Capability Both of them have better protection levels than traditional bare-board SMD, reaching IP54 to IP65, but their protection logic is different. COB adopts a fully sealed integral packaging, which completely isolates the chip from the external environment, and has more thorough moisture-proof, dust-proof and sealing performance. GOB achieves protection through the surface adhesive layer, focusing on protecting the lamp bead surface and solder joints, and the protection effect is concentrated on the module surface layer, with slightly inferior sealing performance compared with COB.

3. Heat Dissipation Performance The COB chip is in direct contact with the PCB substrate, so heat can be directly conducted, resulting in lower thermal resistance and better heat dissipation efficiency, which can effectively improve the long-term operation stability of the display and is suitable for 7×24-hour continuous operation scenarios. The GOB adhesive layer will form a slight thermal insulation layer. Although it does not affect conventional use, it will slightly reduce the heat dissipation efficiency, and additional heat dissipation design is required for high-power application scenarios.

4. Display Effect Without the occlusion of lamp bead brackets, COB forms a continuous light-emitting surface, eliminating dark areas and "graininess" between lamp beads, with better display uniformity and contrast, lower glare, and a more delicate visual effect. The GOB adhesive layer can optimize the optical refraction effect and weaken the characteristics of SMD point light sources, but it still retains the independent lamp bead structure, and its display uniformity and delicacy are slightly inferior to COB.

5. Maintenance and Cost In terms of maintenance, COB is a chip-level integral package. In case of failure, it needs to be returned to the factory for processing with professional equipment, resulting in a long maintenance cycle and high cost. GOB retains the electrical connection structure of SMD lamp beads. If a single lamp bead fails, the local adhesive layer can be peeled off for replacement on site, with low maintenance difficulty and controllable after-sales cost. In terms of cost structure, COB does not need to purchase SMD lamp beads, so the material cost is relatively low, but the precision requirements for die bonding and wire bonding processes are high, and the yield rate has a great impact on the cost. GOB needs additional investment in SMD lamp beads and glue pouring materials, resulting in higher material costs, but it is compatible with existing SMD production lines, with low process difficulty and stable yield rate, and has higher cost performance in medium and high pitch scenarios.

Summary of Core Advantages and Disadvantages
1. COB Packaging Its advantages focus on display performance and long-term stability: strong resolution breakthrough capability, suitable for ultra-small pitch high-end needs; excellent heat dissipation efficiency, extending service life; good display uniformity and visual experience, no graininess and glare; fully sealed structure with more thorough protection. Its disadvantages stem from the characteristics of chip-level packaging: high maintenance difficulty and insufficient on-site maintenance capability; high production process threshold and strict requirements for equipment and technical level; slightly lower brightness under the same power consumption, requiring optical compensation for high-light scenarios.

2. GOB Packaging Its advantages are reflected in protective upgrading and practicality: the adhesive layer protection greatly reduces the lamp bead shedding rate, improves impact resistance and collision resistance, and is suitable for harsh environments and mobile scenarios; compatible with existing SMD production lines, with low technical implementation threshold; supports on-site local maintenance, with excellent maintenance convenience and economy; achieves a balance between protection and display effect, with prominent cost performance in mid-to-high-end scenarios. Its disadvantages stem from the dependence on SMD packaging: the adhesive layer affects heat dissipation, and enhanced design is required for high-power scenarios; the upper limit of resolution is limited, and ultra-small pitch display cannot be realized; the adhesive layer causes 10%-15% brightness attenuation, which needs to be compensated through lamp bead selection or driver design.

Application Scenario Adaptation Principles COB is mainly suitable for indoor ultra-small pitch high-end display scenarios, such as command and dispatch centers, high-end conference rooms, radio and television studios, etc. Such scenarios have extremely high requirements for resolution, display uniformity and long-term operation stability, and low sensitivity to maintenance cycles. GOB is more suitable for outdoor/semi-outdoor display scenarios and rental and mobile display scenarios, such as outdoor advertising screens, stadium display screens, stage rental screens, etc. Such scenarios focus on protection capability, impact resistance and on-site maintenance convenience, with pixel pitch requirements mainly in medium and high pitches. In conventional commercial indoor display scenarios around P1.0, the two can be flexibly selected according to project budget, display effect requirements and maintenance requirements.

Summary and Industry Development Trends GOB and COB are not substitutive but technical subdivisions targeting different needs: COB is a chip-level packaging revolution oriented to ultra-high-definition display, which mainly solves the ultimate problems of resolution and display performance; GOB is an SMD packaging upgrade oriented to practical needs, which mainly solves the pain points of protection and maintainability.

In terms of industry development trends, COB technology is developing towards flip chips, phosphor-free quantum dot coating and integrated driver chips, with the core goal of reducing process difficulty, improving yield rate and cost performance, and consolidating the leading position in the ultra-small pitch market; GOB technology focuses on adhesive formula optimization, reduces optical loss and heat dissipation impact by improving light transmittance and reducing thermal resistance, and expands the application scope of outdoor small pitch in combination with lamination technology. The two will jointly squeeze the market share of traditional bare-board SMD packaging, forming a differentiated competition pattern in the ultra-high-end and mid-to-high-end markets.