Guide · 7 min read
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COB vs SMD vs GOB: What the Packaging Actually Changes
Three ways of attaching an LED to a board. One of them matters for durability far more than the brochures admit, and one is mostly a coating.
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These three letters turn up on quotations without explanation, usually with the more expensive option presented as simply better. They describe how the LED is physically attached and protected on the board, and the difference is real — but it matters in specific situations rather than universally.
| SMD | GOB | COB | |
|---|---|---|---|
| What it is | Individual LED packages soldered to the board — the standard | SMD with a clear resin poured over the surface | LED dies bonded directly to the board, then encapsulated |
| Surface | Exposed lamps with gaps between them | Continuous sealed face | Continuous sealed face |
| Physical knocks | Vulnerable — a lamp can be sheared off | Well protected | Well protected |
| Moisture and dust | Ingress reaches the lamps | Sealed at the face | Sealed at the face |
| Repair | Individual lamp replaceable | Harder — the resin has to be worked through | Not lamp-level; module replacement |
| Cost | Lowest | Modest premium over SMD | Highest |
| Fine pitch | Standard at signage pitches, and commonly quoted down to around P1.5 | Same as the SMD underneath it | The usual answer at the finest pitches, and increasingly so as they get fine |
SMD is the default, and usually correct
Almost every screen sold in India is SMD, and for a board mounted above a shutter or on a first-floor facade that is the right answer. Nothing touches it, the enclosure keeps water out, and paying for a sealed face protects against a risk that is not present.
The weakness of SMD is mechanical. The lamps stand proud of the board, so anything dragged across the surface can shear them off — and the most common cause is not the public but installation and transport.
GOB is a coating, and worth it where things get touched
GOB — glue on board — is an SMD panel with a clear resin poured over the face. The LEDs underneath are ordinary SMD; what changes is that they are now sealed under a continuous surface.
That makes a real difference in three cases: rental and event screens that are packed, trucked and rigged repeatedly; screens within arm’s reach of the public; and humid or coastal installations where moisture at the lamp is the failure mode. In those settings the modest premium buys years.
COB is a different construction, not a coating
COB — chip on board — bonds the LED dies directly to the board and encapsulates them, rather than soldering pre-packaged lamps. Removing the package is what makes COB increasingly attractive as the pitch gets very fine: the finer it goes, the harder and more expensive packaged approaches become to manufacture economically. Where the crossover falls is not a fixed pitch, and it keeps moving — MiniLED and MIP packaging have pushed packaged constructions finer than they used to go. Judge it on the two quotes in front of you rather than on a number.
For ordinary signage at P2.5 and coarser, COB is generally not the value choice. It costs materially more and the visible benefit at normal viewing distances is small. It comes into its own on fine-pitch indoor walls — control rooms, broadcast, premium lobbies — where viewers are close and the pitch is already the reason for the project.
What to do with this on a quotation
- If the screen is out of reach and outdoors in an enclosure, SMD is fine. Do not pay for more.
- If it is a rental screen, or reachable, or in a humid or coastal location, ask for GOB and expect a modest premium.
- If it is fine pitch indoors and viewers are within two metres, COB is a legitimate specification rather than an upsell.
- If a quotation says only "COB" or "GOB" with no pitch, brightness or refresh rate, the packaging is being used to distract from the specification. Ask for the rest.
The last one is the pattern worth watching. Packaging is easy to name and sounds technical. Pitch, nits, refresh rate and warranty terms are what actually determine whether you are happy with the screen in three years.