Why ARECH fine-pitch LED displays use COB, not SMD

ARECH's fine-pitch indoor displays use COB (Chip-on-Board) packaging rather than SMD (Surface-Mounted Device). The choice is a practical one, driven by three measurable differences in reliability, optics, and thermal performance.

What the packaging difference actually is

In an SMD display, each LED is a pre-packaged component: a tiny plastic housing with the chip inside, soldered onto the PCB. The housing protects the chip, but it also protrudes from the surface, and there are small gaps between each package. At fine pitches below about P1.5, those gaps become significant relative to the pixel size — they scatter ambient light, reduce contrast, and leave the edges of each package exposed to impact, moisture, and ESD.

In a COB display, bare semiconductor chips are bonded directly to the PCB, then the entire surface is covered in a single continuous epoxy layer. The result is a flat, sealed face with no individual component edges and no inter-pixel gaps.

Reliability

The continuous epoxy surface can be touched, wiped, and cleaned without damaging the display. It is resistant to moisture and ESD. In a public environment — a hotel lobby, a conference centre, a retail store — this matters. An SMD panel at the same pitch would need a protective front glass or diffuser, which adds cost, weight, and reduces brightness.

ARECH's COB fine-pitch panels carry a 24/7 operational rating. The sealed surface also performs better in environments with humidity variations, since there are no exposed solder joints or package edges for condensation to reach.

Optical performance

The sealed epoxy surface absorbs ambient light rather than reflecting it between pixels, which raises the effective contrast ratio. The viewing angle is wider and more uniform because light does not diffract off individual package edges. For displays where viewers sit or stand at varying distances and angles — conference rooms, broadcast studios, control rooms — this uniformity reduces eye fatigue over long sessions.

Thermal path

COB bonding puts the chip in direct contact with the PCB substrate with a shorter thermal path than an SMD package. Better heat dissipation at the chip level means lower operating temperatures, which translates directly to longer LED life.

ARECH COB fine-pitch specifications

The current COB fine-pitch range covers pitches P0.78mm, P0.93mm, and P1.87mm, supporting 2K, 4K, and 8K resolutions with 16.8 million colours. Available pixel pitches across the product line: P0.7 / P0.9 / P1.2 / P1.5 / P1.8. Standard panel unit is 27 inches, with assembled display sizes of 108", 136", and 216".

For the full specification table and configuration options, see the HD wall product page or contact us.