Knowledge & Resources

LED Knowledge & Resources

Technical white papers, case studies, and articles focused on LED component technology — packaging, testing, reliability, and applications. All content here relates to LED chips, packages, and component-level engineering, not lighting fixtures.

LED Component Fundamentals

Package Technologies at a Glance

Through-hole (DIP) LEDs pair a 3–10 mm epoxy lens with a metal lead frame; they are the most economical choice for indicators and low-density displays and are ideal for hand soldering and high-vibration environments. SMD packages (0402 to 5050 and larger) mount directly on PCB pads, enabling compact boards and automated reflow assembly. High-power packages (such as 3535 and 5050 ceramics) dissipate 1 W or more and require an MCPCB or aluminum heat sink. COB (chip-on-board) arrays integrate many dies under a single phosphor layer for uniform, high-flux illumination.

Reading the Key Parameters

• V_F (forward voltage) — the voltage across the LED at rated test current; red/amber dies run 1.9–2.4 V, blue/green/white dies 2.8–3.4 V
• I_V (luminous intensity, cd) — brightness in a given direction; compare only at the same viewing angle
• Φ_V (luminous flux, lm) — total output, the fair comparison metric for lighting-class LEDs
• λ_d / λ_p (dominant / peak wavelength) — how color is actually binned; use λd for color matching and λp for sensor and optical filter design
• CCT (correlated color temperature) — warm white ~2700–3500 K, neutral ~4000–5000 K, cool white ~5700–6500 K
• CRI / R9 — color rendering; R9 (deep red) matters for food, skin tone, and medical lighting
• Viewing angle — the half-intensity cone; narrow (15–30°) for signaling, wide (120–140°) for general illumination

How Binning Works

Manufacturers sort production dies into bins by luminous intensity (or flux), dominant wavelength, and forward voltage. A bin code such as “H1” or a three-part code (intensity/wavelength/VF) therefore defines the exact electrical and colorimetric window you will receive. For multi-LED assemblies — channel-letter signs, backlit panels, display pixels — always specify a single intensity and wavelength bin to avoid visible brightness or color mismatch. When a datasheet shows a range, ask the supplier for the bin structure document; the datasheet center lists bin limits for each series.

Wavelength Selection for IR and UV

For infrared emitters, 850 nm offers higher radiant intensity and slightly better camera sensitivity but produces a faint red glow; 940 nm is completely covert with roughly 30–40% lower output at equal drive. Match the emitter wavelength to your photodiode or camera sensor response curve. For UV, UVA (365–405 nm) serves curing, inspection, and photopolymer applications — shorter wavelengths cure faster but demand stricter handling precautions. Our infrared emitter and UV LED catalogs list the available wavelength options.

Lifetime and Reliability Terms

LED life is expressed as L70 (time to 70% lumen maintenance) or L80/L90 for stricter applications, statistically reported as B50 (median). Projection beyond test duration follows IES TM-21 extrapolation of LM-80 collected data, capped at 6× the actual test hours. Understand the operating temperature at which LM-80 data was collected (typically 55 °C, 85 °C, or 105 °C case temperature) — using 85 °C data for an application running at 105 °C will overstate life. The full methodology is covered in our LM-80 lifetime estimation guide.