AOB and GOB: protection tecnologies for LED modules

LED screens use more advanced technologies every day and the distance between pixels is being reduced considerably to such an extent that the LEDs of the panels are so small that it is difficult to see them with the naked eye. When using such a high pixel density it is advisable to use systems that protect the LEDs and make them more resistant. For this purpose, there are two solutions for small pixels. The AOB and GOB solutions provide additional resistance to the LED panels to make them more resistant and easier to handle.

AOB technology (Admixture On Board)

AOB literally means “admixture on board” referring to an adhesive resin. A layer of resin is sprayed covering the bottom of the LED and the top of the PCB so that it strengthens the bond between the LED and the board. In addition, this system does not affect the display quality at all.

–Improves the impact resistance of the LEDs. Thanks to the AOB resins, the resistance of the junction of the LEDs with the board is multiplied by 6. Protecting much better against scratches, impacts and scratches that may occur during the process of handling, installation and use of the screen.
–Improves the front sealing of the LED module by protecting the soldering points against water and dust.
–Allows LED boards with smaller pixels and wider viewing angles.
–Slightly improves the color consistency and contrast of the boards by coating the sides and soldering feet of the LED with a resin.
–Reduces the rate of defective LEDs during manufacturing by providing more secure and durable joints and improving board reliability.

How is an AOB resin applied?

AOB is the last process in the SMD system of electronic board manufacturing. After component placement and soldering, the LED module is subjected to a 72-hour series of performance tests to ensure good color balance and uniformity. This allows correcting or discarding any factory defect before applying the resin protection. Finally, after passing the performance tests, a layer of polymer resin is dispersed on the surface of the module which will build up between the LEDs, reinforcing their bond with the board and providing additional protection.

Visually you will notice a matte translucent black resin layer between the LEDS and the LED module PCB. This resin layer provides some enhancements to the contrast and reflectivity of the display. The matte black color allows for an enhanced contrast effect comparable to using black front side SMD LEDs. In addition the reflectivity of the resin slightly improves the viewing angles of the display. This is achieved by improving the reflectivity alleviating color consistency losses when viewing the display from a wide viewing angle.

GOB technology (Glue On Board)

A patented transparent resin is used to cover the entire module or LED panel on its upper part. This system has the advantage of protecting the LED panels much better against manipulation and transport, preventing LEDs from breaking or jumping out of the screen when receiving a scratch or accidental impact. These events are a much more common factor than it may seem and cause most of the maintenance interventions of a LED display. Buying a screen with GOB protection guarantees a foolproof resistance of the screen surface. The only drawback is that this resin may lose its properties over time and slightly affect the display quality. 

GOB LED modules are especially useful for installing screens that are highly exposed to elements that can damage the integrity of the screen: weather conditions, contact with the public, accidental impacts, etc.

The best protection available for your display. This is achieved by completely sealing the front of the LED module. This technology creates a tough transparent resin layer on top of the LEDS protecting them from impact, dust and weathering in the most effective way.

Increased durability. Avoids breakage of LEDs during installation, transportation and use. Increased reliability of the LEDs is remarkable since the resin is only applied on tested and verified LED boards.

Better contrast: The matte finish of the resin coating slightly increases the contrast of the image and reduces reflections on the screen surface.

Better image consistency: The resin coating acts as a lens that improves the light diffusion of the screen, resulting in greater image consistency and uniformity and wider viewing angles.

Improved screen flatness. GOB protection results in a totally flat LED module surface that provides a uniform and robust appearance to the display.

Avoidance of maintenance. The superior strength of these LED modules means far fewer module replacements in a display, which is much more common in displays that do not have this protection system.

Reduction of blue light: The screens with GOB resin emit very little blue light and are less aggressive than traditional LEDs.

Inconveniences of the GOB technology

Difficulty of repair. In the event that a GOB module requires repair on the front of the module, this will be much more complicated or impossible because the protective resin will be permanently bonded. In these cases the costs of part replacement versus repair must be evaluated.

Alteration of the transparency of the resin over time. Over the years the surface of the resin may lose transparency due to wear caused by the heat of the LEDS themselves. The appearance of this problem is very variable and depends on the environmental conditions in which the screen works.

Loss of flatness of the screen. Temperature differences over the years can cause slight deformations in the resin layer showing a less flat appearance than at the beginning of its useful life.

Applications of GOB LED displays

LED screens for shows, fairs and events

These types of screens are often subject to multiple assemblies, disassemblies and transport operations in short periods of time. This considerably increases the risk of receiving impacts or abrasion damage to the display surface causing higher maintenance costs. GOB LED module displays are ideal for this type of application due to their high strength and durability

Floor LED screens 

Traditionally, to install a screen on the floor, a layer of transparent acrylic material has to be added on top of the screen. With the GOP system this additional layer can be replaced and GOP modules with thick resin layers can be used directly as a floor screen. 

See-through LED displays

LED displays with transparency allow you to see through the display when it is not operating. This is achieved by openings between the individual rows of LEDs that allow light to pass through the screen. A disadvantage of this type of display is its relative fragility compared to conventional LED displays.
This is because the structures that sioportant this type of screens are much thinner and fragile. In these cases the use of a GOB resin protection can be a differential factor to improve the durability and resistance of this type of screens.

Flexible LED displays and special shapes.

There is increasing demand for flexible LED displays in commercial applications. Interior and commercial designers appreciate the impact of circular or adaptable displays in complex shapes. However, these types of displays also suffer from the ills associated with having a less robust structure than traditional displays. Therefore, the application of special GOB resins in flexible displays makes it possible to use this type of design solution with a greatly improved level of reliability and strength.

Differences between AOB and GOB

The application methodology is similar between the 2 systems, but with a different resin formulation resin is used since in the case of GOB a total coating of the LED is performed. This creates a totally uniform resin layer that protects the entire screen surface.

• GOB has a considerably higher cost than AOB.
• Protection: GOB has better protection than AOB. Since the LED will be completely covered by the resin if we use GOB, the protection of GOB is much better. AOB offers less protection than GOB, but it can still protect the LED to some degree. Even if the LED module has AOB protection, we still need to handle the LED module with care during assembly and transportation of the display.
• LED light output. When we use GOB, since the LED is completely covered by the resin, the heat dissipation will be slightly reduced.  Therefore the LED light output will be slightly lower than in an AOB module after a few years.
• Transparency of the resin layer. Although the resin is transparent or slightly dark at first, its appearance may change over the years due to the effect of heat, surface wear and abrasion. This can cause the protective layer to turn slightly white after a few years, affecting the white balance of the display. AOB does not have this type of problem as the resin is only on the LED leg so the durability of the resin does not affect the picture quality. 

WHEN TO USE EACH ONE: AOB or GOB

For very small pixels such as P1.9 and below (P0.9, P1.2 and P1.5) we recommend GOB. In these cases the extra protection of the GOB system is more than justified by the cost of the modules for these types of pixels. With such small LED sizes, the force required to cause damage to the display surface is very low and the risk of damage to the LEDs is very high. To mitigate this risk, the use of LED modules with GOB protection is highly recommended.

For P2.5 pixels and larger we recommend AOB. It is an excellent protection system that will protect your investment without adding excessive overhead. These LEDs already have a larger contact area, but it is still highly recommended to protect your investment.

Of course you can also choose the level of protection you want for your project as we offer custom made screens. If you need more information please contact us.