COB, GOB, SMD and MIP LED packaging: what they actually mean and when each wins

Four LED packaging technologies are competing for the same AU market right now. The marketing for each uses similar language — “rugged,” “high-contrast,” “broadcast-grade” — and the pitch ranges overlap. Without understanding what each technology actually does at the component level, comparing them is comparing slogans.

This is the ground-truth explainer. No marketing language.

SMD: the baseline all others are measured against

Surface-Mount Device (SMD) packaging has been the LED display industry standard since approximately 2008. Each pixel consists of a single pre-assembled component — three LED dies (red, green, blue) encased inside a small plastic carrier with a clear or diffuse lens, typically 1.5 mm × 1.5 mm to 3.5 mm × 3.5 mm in size. The package is reflow-soldered onto the PCB using standard SMT assembly equipment. Each pixel is a discrete, replaceable unit.

What SMD does well:

• Peak brightness: up to 10,000 nit in production outdoor cabinets. No other packaging technology matches this at commercial scale.
• Serviceability: a dead pixel is a single component, de-soldered and replaced in the field with standard rework equipment. Repair economics are well-understood.
• Supply chain maturity: SMD components are produced by hundreds of manufacturers at enormous scale. Spares are globally available.
• Pitch flexibility: practical down to P0.9 using 1010-format packages (1.0 mm × 1.0 mm dies in a 0.6 mm carrier).

SMD’s real limitations:

• The clear lens creates a bright axial lobe — viewable brightness falls off noticeably past 45° horizontal. For screens viewed from sharp angles, SMD shows more colour shift than COB at the same brightness.
• The raised lens is physically proud of the PCB surface. High foot-traffic, hand-contact and abrasive cleaning can dislodge or scratch lenses over time. This matters for interactive surfaces and touch walls — it does not matter for a ceiling-hung corporate wall.
• Below P0.9, the geometry of placing 1.0 mm packages at 0.9 mm centres becomes a yield problem. COB becomes more practical.

COB: bare dies, flooded surface

Chip-on-Board (COB) eliminates the individual pixel package entirely. Bare LED dies (red, green, blue) are placed directly on the PCB substrate using flip-chip or wire-bond methods, and the entire module surface is flooded with a transparent epoxy resin that permanently encapsulates all the dies. The result is a flat, monolithic, continuous surface — there are no individual lenses, no raised components, no seams between pixels.

What COB does well:

• Viewing angle: the epoxy surface emits nearly Lambertian (uniform across angle). Viewing angle falloff that is visible in SMD walls at 60° is absent or greatly reduced in COB. This matters substantially for corners of wide videowall installations.
• Surface ruggedness: the epoxy fill is flush and hard. Finger-press, scratch and cleaning-brush impacts that damage SMD lenses are absorbed by the COB surface. COB walls are significantly more appropriate for touch-interactive and high-traffic public installations than SMD.
• Reflectivity: COB’s matt epoxy surface is 2–4× less reflective than SMD’s clear lenses. Under high-ambient-light conditions — studios, lobbies with large windows, retail — the perceived black level is meaningfully deeper on COB.
• Fine pitch scalability: bare dies at P0.4–P0.9 are geometrically achievable with COB in ways that SMD cannot match.

COB’s real limitations:

• Peak brightness: production COB panels top out at approximately 1,000–1,500 nit. The encapsulation process limits the thermal path from die to heatsink, constraining drive current and maximum brightness. This is not a fixable limitation — it is physics. COB is an indoor technology.
• Serviceability: a dead pixel means a full module replacement. The epoxy fill is permanent — it cannot be opened and re-sealed in the field. For a wall with 100,000+ LEDs over a 10-year life, the module replacement economics are different from SMD. For a P0.9 studio wall where a single dead pixel is already a write-off, COB’s serviceability cost is irrelevant. For a P4 corporate wall where single-pixel repair is routine, it matters.
• Pre-encapsulation binning: the most common reason a COB wall underperforms its datasheet is inadequate chip-level binning before encapsulation. In SMD, each package is tested before placement. In COB, dies are placed then encapsulated — and chip-level binning before encapsulation is labour-intensive. Budget COB from manufacturers who skip this step presents as visible module-to-module colour variation. Ask any COB supplier whether chip-level binning is performed before encapsulation, and ask for multi-module footage at 5% and 50% brightness.

GOB: SMD with a protective coating

Glue-on-Board (GOB) is the most misrepresented of the four technologies in sales contexts, because it is frequently marketed as a COB alternative when it is structurally different.

GOB is not a bare-die technology. GOB takes a conventional SMD module — already assembled with standard pixel packages — and applies a transparent optically-bonded resin coating over the entire surface. The SMD packages remain intact beneath the coating. The result looks superficially similar to COB (flat, continuous, no raised lenses) but the underlying architecture is completely different.

What GOB adds to SMD:

• Physical protection: the GOB layer fills the gaps between SMD lenses and provides a scratch-resistant surface. Abrasion and impact resistance are substantially improved over bare SMD.
• Reduced reflectivity: the GOB resin typically has an anti-reflective formulation that brings SMD module reflectivity closer to COB levels. Not identical to COB, but noticeably improved.
• Moisture resistance: the coating reduces moisture ingress at the package-PCB interface, extending lifespan in high-humidity environments.

What GOB does not do:

• GOB does not change the optical emission properties of the underlying SMD packages. Viewing angle falloff is still present — the lenses beneath the coating still create a directional emission pattern. A GOB wall has better reflectivity than SMD, but the same viewing angle characteristic as SMD.
• GOB does not improve brightness. The SMD packages beneath the coating drive the same current with the same thermal path.
• GOB does not match COB contrast under high-ambient conditions, because the SMD lenses are still there; the GOB layer reduces but does not eliminate their reflectivity.

GOB’s genuine advantage over COB: the GOB resin can be dissolved with an appropriate solvent, and the individual SMD packages beneath are then accessible for standard rework. GOB is therefore field-serviceable in a way that COB is not — a meaningful advantage for large walls in locations where module replacement logistics are difficult.

The honest application for GOB: interactive and high-touch installations at P1.5–P2.5, where SMD economics are attractive, single-pixel serviceability matters, and the added physical protection justifies the GOB premium over standard SMD. GOB is not the right answer at P0.9 or below — COB is more capable at that pitch — and it is not the right answer for a non-touch suspended corporate wall — standard SMD is more cost-effective there.

MIP: pre-binned micro-dies in a carrier package

Mass-in-Package (MIP) is the newest of the four technologies in production, currently shipping from a small number of tier-one manufacturers.

MIP begins with micro-LED dies — red, green and blue chips at approximately 50–100 µm scale. These dies are tested and binned for wavelength and brightness at chip level before any encapsulation. The pre-binned dies are then placed inside a discrete mini-carrier package (approximately 0.2–0.4 mm footprint) using flip-chip bonding, and the carrier package is then surface-mounted onto a PCB using standard SMT equipment.

What MIP does that COB does not:

• Pre-encapsulation binning is built into the process — the uniformity that COB achieves only with premium, labour-intensive manufacturing is standard in MIP. Module-to-module colour consistency is a structural feature, not a quality-control variable.
• The discrete carrier package means that individual pixels are in principle replaceable — though the small package size (0.2 mm) makes field rework much more difficult than SMD, it is possible in a factory setting. MIP is more serviceable than COB.
• Standard SMT placement equipment can handle MIP carriers, meaning the PCB assembly process is closer to SMD than to COB’s bespoke die-placement methods.

MIP’s current limitations:

• Commercial availability: MIP is shipping at scale from only a handful of manufacturers as of mid-2026. Lead times are longer than SMD or COB, and the product range is limited to pitches P0.6–P1.5 in current production.
• Cost: MIP at equivalent pitch is currently 40–70% more expensive than COB, driven by the die testing and binning process. The premium is expected to compress as volume increases.
• Pitch floor: MIP currently targets P0.4–P1.5. Below P0.4 — the territory where micro-LED display research operates — MIP is not yet commercial.

The decision matrix

Your application	Correct packaging
Any outdoor installation in Australia	SMD (brightness)
Stadium scoreboard or perimeter LED	SMD (brightness, serviceability)
P2.5–P5 indoor mid-distance corporate	SMD (cost, serviceability)
P0.9–P1.5 fine-pitch non-touch lobby or studio	COB (contrast, viewing angle)
P0.9–P1.5 fine-pitch touch-interactive	COB if budget allows; GOB otherwise
P1.5–P2.5 high-traffic retail or museum	GOB (protection + serviceability)
Virtual production volume	COB (contrast, low reflectivity, viewing angle)
Fine-pitch P0.6–P1.2 where uniformity is critical	MIP (if lead time and budget allow)
Sub-P0.9 broadcast/broadcast studio	COB or MIP depending on availability

What to push back on

If a supplier is pitching GOB as “equivalent to COB” — specifically for contrast and viewing angle — ask them to show footage of a GOB wall and a COB wall side-by-side under strong ambient light. The reflectivity and viewing angle characteristics are similar in marketing copy and measurably different on-wall.

If a supplier is pitching COB for any outdoor application in Australia, ask for the maximum nit rating at full operation. If the answer is below 3,000 nit, the cabinet is not adequate for daylight outdoor use in AU conditions.

If a supplier is pitching MIP, ask for three completed reference installations with contact details. MIP is real technology and commercially available — but the installed-base of operating MIP walls is still small globally, and warranty service maturity (what happens at year three when a module fails) has not been tested at scale yet.

What Aurora ships

Aurora’s LUX range covers COB at P0.9, P1.2 and P1.5 — the sweet spot where COB’s properties pay off — and SMD at P1.5, P2.5 and P4 where serviceability and cost economics favour traditional packaging. The V-SPEC and GSR ranges are SMD across the board.

Aurora does not currently ship GOB as a standard product — we believe the application case for GOB is narrow, and where it applies (high-traffic interactive walls at P1.5–P2.5), the cost premium requires a genuine serviceability or robustness requirement to justify it.

MIP is on the roadmap. When Aurora ships MIP, it will be documented transparently here.

Talk to us about your project and we’ll recommend the right packaging — including cases where we’ll tell you that a competitor’s product is the better answer for your specific application.