The Advantages of HOB Technology Over GOB in LED Display Manufacturing

In the LED manufacturing industry, the choice between HOB (High Optical Brightness) and GOB (General Optical Brightness) technologies can significantly impact the quality and performance of the final product. This article will explore the advantages of HOB technology over GOB, based on a comparative analysis of their processes and outcomes.

What is GOB？

GOB stands for Glue On Board, an advanced packaging technology used for LED display screens. This technology involves injecting a special optical thermal conductive nanometer-grade potting material between the LED lamps and the PCB (Printed Circuit Board) to enhance the stability of the connections between the lamps and provide various protective functions such as waterproofing, moisture-proofing, dust-proofing, anti-shock, anti-static, and more.

A GOB LED module is an LED display made using GOB technology, featuring high protectiveness and the ability to work in a variety of harsh environments, such as outdoors or indoors. This comprehensive protective function is particularly suitable for indoor small-pitch LED displays, ensuring their stability and durability in complex environments. Moreover, GOB technology integrates the midstream packaging and downstream display technology of the LED industry, saving costs in the manufacturing process and increasing production efficiency. Additionally, the cost of GOB LED modules is relatively low, which can reduce the overall cost when manufacturing indoor small-pitch LED displays.

What is HOB？

HOB stands for High Optical Brightness, which refers to a state-of-the-art LED packaging technology. This technique involves injecting a special optical thermal conductive nanometer-grade potting material between the LED lamps and the PCB (Printed Circuit Board) to enhance the stability of the connections between the lamps and to provide various protective functions such as waterproofing, moisture-proofing, dust-proofing, anti-shock, and anti-static properties. The features of HOB technology include superior stability, comprehensive protection, excellent optical performance, and efficient heat dissipation.

What is the difference between GOB and HOB?

HOB uses a high-temperature molding process, while GOB uses a normal-temperature dispensing process. HOB has better thermal stability, accuracy, flatness, and thickness control than GOB. Moreover, high-temperature molding can prevent the glue from cracking due to heat generation during LED operation causes the undesirable phenomenon of dead lights.

1.  HOB has better thermal stability and environmental adaptability than current GOB.

2.  Compared with conventional COB technology (which cannot accurately repair a single lamp bead), 

     HOB technology can repair a single lamp bead and save costs.

3.  HOB technology is more effective in reducing moiré pattern（optical phenomena）than conventional SMD\GOB technology LED display products.

4.  HOB technology has a longer life than ordinary SMD\GOB technology LED display products. 

5.  HOB technology has higher moisture-proof, anti-collision and anti-static effects than conventional SMD technology LED display products.

Appearance

HOB technology excels in providing a natural and smooth granular texture to the LED surface, which is a result of its one-time curing process. This addresses the issues of flat mirror-like reflections and uneven micro-granularity often seen in GOB technology. Furthermore, HOB's tunnel furnace curing process ensures consistent ink color, unlike GOB, which can suffer from color variations due to its longer curing cycle that involves surface drying for 2-3 days and deep curing over 3-6 months.

GOB and HOB ink color consistency contrast

The flatness of HOB is superior, as it utilizes fully automated equipment with specialized jigs for vacuum glue filling and tunnel furnace curing, which solves the issue of poor flatness associated with GOB's room temperature curing. Additionally, HOB's uniform colloid thickness contributes to better light damage and heat dissipation compared to GOB, reducing potential issues with the lifespan of the LEDs.

Contrast 

The surface of the final product of the ordinary GOB process is a mirror surface, which cannot achieve a frosted or matte surface.

HOB uses mold design and pressure molding to create a frosted surface, which is similar to matte black light. This increases the contrast of the entire screen by 40%.

Display Effects

In terms of display effects, HOB technology ensures that there is no light leakage between seams, a common issue with GOB's mirror-like light sources that can lead to light leakage and easier modularization. HOB also improves the appearance of ink color and eliminates the yin and yang face effect, allowing customers to avoid the need to manually select and color-match boards as is often required with GOB technology.

Performance

HOB technology demonstrates superior performance in terms of temperature resistance, withstanding a range of -20℃ to +80℃, compared to GOB, which can lead to module deformation at around -5℃. This makes HOB more reliable in extreme temperature conditions. Moreover , HOB's high-temperature curing process ensures that the glue retracts around the LEDs, providing long-term protection against pulling and potential cold welding of the LEDs, a problem that can arise with GOB due to its longer curing times.

Durability

HOB adopts the COB process of high-temperature molding with a polymer synthetic colloid, which contains various additives, coagulants, and anti-UV agents. This can prevent the yellowing problem of ordinary epoxy, and also adjust the black pigment and design the mold frosted surface.

Anti-Scratch and  Water-Proofing, Moisture-Proofing, Dust-Proofing, Anti-shock, and Anti-Static properties.

When you place a conventional GOB product and a HOB product side by side, and scratch the surface with a screwdriver, you will see a clear difference. The GOB product is not scratch-resistant and will show scratches and cracks immediately, while the HOB product will remain intact. This is because the HOB product uses the COB process of high-temperature molding with a polymer synthetic colloid, which has various additives, coagulants, and anti-UV agents. This can avoid the yellowing problem of common epoxy, and also modify the black pigment and create the mold frosted surface.

Optical performance

GOB process has a variable thickness of the final product, and a difference in the flatness of the self-leveling colloid, which results in a thicker GOB product. This causes a more noticeable edge refraction problem when splicing on a large scale, which is commonly known as the bright line problem of the writing angle.

HCOB uses precision molding tools, which ensure that its thickness is only up to 0.2mm higher than the LED height, and the light hardly undergoes secondary refraction at the edge of the colloid.

Production Process

The production process of HOB is more advanced, utilizing fully automated equipment. This includes integrated mold formation, automatic imaging inspection, and a 40-meter long high-temperature automatic line that can complete the process in just 1.5 hours. This not only ensures consistent quality but also significantly reduces production time and enhances delivery efficiency. In contrast, GOB relies on manual or semi-automatic equipment, which can lead to inconsistencies and longer production times.

Precision 

HCOB uses high-precision mold technology, which allows the overall molding accuracy to be controlled within 0.2mm, according to conventional mold precision. GOB uses room temperature molding, which depends on the molecular internal coagulation curing, and has a shrinkage problem. The best progress of GOB so far is 0.5mm, and some products need secondary processing. HCOB technology has been applied in batches on the mainstream pitches of 1.2, 1.5, and 1.8.