Definition
COB (Chip-on-Board) LED technology mounts multiple LED dies directly onto a single thermally-efficient substrate (typically ceramic or aluminum), then covers the entire array with a uniform phosphor layer — creating what appears to be a single large LED rather than multiple individual points. Unlike SMD LEDs where each chip is individually packaged, COB eliminates the individual package substrates and spaces between dies, resulting in: (1) Higher lumen density (lumens per square millimeter), (2) A single uniform light-emitting surface (no multi-shadow effect, no dotting), (3) Superior optical control — the single emission point enables precise beam shaping with simple reflectors and lenses, and (4) Better thermal management — the substrate acts as a direct heat spreader. COB is the preferred technology for directional lighting applications: downlights, spotlights, track lights, and anywhere beam precision matters.
Key Data
| Parameter | Value / Explanation |
|---|---|
| Typical power | 10-100W per COB. High-power COBs (500W+) available for stadium/sports lighting |
| Efficacy | 120-170 lm/W at rated current. Slightly lower than SMD at same power due to thermal density |
| LES (Light Emitting Surface) | 6-32mm diameter typical. Smaller LES = tighter beam control possible |
| CRI | 80-97 typical. COB excels at high CRI due to uniform phosphor coverage |
| Beam control | Superior — single emission point produces clean beam cutoff with simple reflectors. 8-60° typical. |
| Cost premium vs SMD | 20-40% higher per delivered lumen. Justified by beam quality and compact form factor. |
Application Guide
Retail downlight/spotlight
COB LED, 20-40W, CRI 95+, 15-25° beam, 3000K
Single-point source creates clean, sharp beam for merchandise accent; high CRI for accurate color
Museum track light
COB LED, 15-30W, CRI 97+, 8-12° beam, UV-filtered, 3000-4000K
Precision beam control with no spill light; no UV damage to artifacts
High-end hospitality
COB downlight, 15-25W, CRI 95+, warm dim (3000-1800K), deep recessed
Incandescent-like dimming curve with warm color shift; glare-free due to deep recession
Conclusion & Procurement Recommendation
COB is worth the 20-40% premium over SMD when: (1) Beam precision matters — the single emission point produces cleaner shadows and sharper beam cutoff than multi-SMD arrays, (2) Compact form factor is required — a single COB replaces 20-50 SMD chips in downlight/spotlight applications, (3) High CRI is specified — COB's uniform phosphor coverage delivers consistent CRI across the entire beam (SMD arrays can have color-over-angle variation). Key procurement specifications: (1) LES diameter (determines minimum achievable beam angle — smaller LES = tighter beam possible), (2) Color-over-angle consistency (Δu'v' ≤0.004 across 0-60° from center), (3) Hot lumen testing at steady-state operating temperature (not pulsed cold measurement).