Definition
COB (Chip-on-Board) and SMD (Surface-Mount Device) are the two dominant LED packaging technologies, each optimized for different applications. SMD LEDs are individual chip packages (2835, 3030, 5050) soldered individually onto a PCB — think 'many small points of light'. COB LEDs mount multiple bare LED dies directly onto a single substrate and cover them with a uniform phosphor layer — think 'one large point of light'. This fundamental difference cascades into every application decision: SMD excels at distributed, uniform area illumination (panels, strips, high bays), while COB excels at directional, beam-controlled illumination (downlights, spotlights, track lights). Understanding this difference is essential for B2B procurement — specifying the wrong technology for the application results in poor optical performance regardless of lumen output.
Key Data
| Parameter | Value / Explanation |
|---|---|
| Light source appearance | SMD: multiple individual points | COB: single uniform surface — no multi-shadow, clean beam cutoff |
| Beam control | SMD: requires secondary optics (lens/reflector array) | COB: single reflector achieves tight, clean beam |
| Lumen density | SMD: 50-200 lm per chip | COB: 2,000-10,000+ lm from a single LES (Light Emitting Surface) |
| Efficacy (typical) | SMD: 150-200 lm/W (small chip advantage in thermal management) | COB: 120-170 lm/W (slightly lower) |
| CRI | SMD: 70-95, color-over-angle variation possible | COB: 80-97, excellent color-over-angle uniformity |
| Cost per delivered lumen | SMD: lower (20-40% less) — mature, high-volume manufacturing | COB: higher — premium for beam quality |
Application Guide
LED panel (office ceiling)
SMD 2835, 120° native beam, low cost per lumen
Uniform area illumination needs many light points; SMD's wide native beam is perfect
Retail downlight (accent)
COB, 15-25° beam, CRI 95+, clean single shadow
Single emission point + reflector = precise beam control; merchandise looks premium
Track light (museum)
COB, 8-12° beam, CRI 95+, UV-filtered, precise cutoff
Tightest beam control requires single-point source; no spill light on adjacent artwork
Conclusion & Procurement Recommendation
For B2B procurement: choose SMD when you need broad, uniform light distribution at the lowest cost per lumen. Choose COB when you need controlled, directional light with clean beam cutoff and excellent color-over-angle uniformity. The cost premium for COB (20-40% per delivered lumen) is justified by better optical control and visual quality in directional applications. Hybrid approach: most large projects use both — SMD for ambient/general lighting (80% of fixtures), COB for accent/directional lighting (20% of fixtures).