Blue LED 3535 - 3.45x3.45x2.20mm - Voltage 2.6-3.4V - Power 5.1W - Dominant Wavelength 465-475nm - Technical Data Sheet

1. Product Overview

The RF-AL-C3535L2K1RB-05 is a high-performance blue light emitting diode (LED) built on advanced InGaN-on-substrate technology. Designed for demanding general lighting and specialty applications, this 3535 package (3.45mm x 3.45mm x 2.20mm) delivers a dominant wavelength range of 465-475nm, producing deep blue light. With a typical forward voltage of 2.6-3.4V at 350mA and a maximum forward current of 1500mA, it offers excellent luminous flux (30-50 lumens) and total radiant flux (400-800mW). The ceramic package ensures superior thermal management and reliability, making it suitable for both standard SMT assembly and high-power lighting designs.

1.1 Core Advantages

• Ceramic substrate for low thermal resistance and improved heat dissipation
• Extremely wide viewing angle (120 degrees) for uniform light distribution
• Compatible with all SMT assembly processes and soldering profiles
• Available in tape and reel packaging (1000 pcs/reel) for efficient manufacturing
• Moisture sensitivity level 1 (MSL1) – no baking required before use
• RoHS compliant – free from hazardous substances

1.2 Target Applications

This blue LED is ideal for a wide range of applications including color accent lighting, flexible LED strips, plant growth lighting (blue spectrum for photosynthesis), landscape lighting, stage photographic lighting, hotels, retail spaces, offices, and general indoor illumination. Its high radiant flux also makes it suitable for UV-curing and specialty industrial lighting where blue wavelengths are required.

2. Technical Parameter Analysis

2.1 Electro-Optical Characteristics (at 25°C, IF=350mA)

The LED's forward voltage (VF) ranges from 2.6V to 3.4V with a typical value of ~3.0V. Luminous flux (IV) is between 30 and 50 lumens, while total radiant flux (Φe) ranges from 400mW to 800mW. Dominant wavelength (λD) is specified as 465-475nm, with a narrow tolerance of ±1nm in measurement. The reverse current (IR) at VR=5V is less than 10µA, ensuring minimal leakage. The viewing angle (2θ1/2) is 120 degrees, providing wide beam coverage.

2.2 Absolute Maximum Ratings

• Power Dissipation (PD): 5100 mW
• Forward Current (IF): 1500 mA
• Peak Forward Current (IFP): 1650 mA (1/10 duty cycle, 0.1ms pulse)
• Reverse Voltage (VR): 5 V
• ESD (HBM): 2000 V
• Operating Temperature (TOPR): -40°C to +85°C
• Storage Temperature (TSTG): -40°C to +85°C
• Junction Temperature (TJ): 125°C

Care must be taken to ensure power dissipation does not exceed the absolute maximum rating. The junction temperature should be kept below 125°C to maintain reliability.

3. Binning System

3.1 Forward Voltage Bins (IF=350mA)

Forward voltage is sorted into four bins:

• F0: 2.6 – 2.8 V
• G0: 2.8 – 3.0 V
• H0: 3.0 – 3.2 V
• I0: 3.2 – 3.4 V

3.2 Luminous Flux Bins (IF=350mA)

• FA3: 30 – 35 lm
• FA4: 35 – 40 lm
• FA5: 40 – 45 lm
• FA6: 45 – 50 lm

3.3 Dominant Wavelength Bins

• D00: 465 – 470 nm
• E00: 470 – 475 nm

Measurement tolerances: VF ±0.1V, λD ±1nm, luminous intensity ±10%. Binning enables customers to select precise color and flux combinations for their application.

4. Performance Curves

4.1 Forward Current vs. Forward Voltage

The forward current increases rapidly with voltage after the turn-on threshold (~2.6V). At 3.0V, current is ~350mA; at 3.4V, current approaches 1500mA. This steep IV characteristic requires careful current regulation to avoid overdrive.

4.2 Relative Intensity vs. Forward Current

Relative light output increases nearly linearly with current up to about 1000mA, then begins to saturate. At 1500mA, relative intensity is approximately 3.0 times the value at 350mA. However, thermal effects at high current may reduce efficiency.

4.3 Temperature vs. Relative Intensity

As the solder point temperature (Ts) rises from 25°C to 105°C, relative intensity decreases by about 20-30%. Adequate heat sinking is essential to maintain luminous output in high-power operations.

4.4 Ts Temperature vs. Forward Current (Derating)

The maximum allowed forward current must be derated as temperature increases: at 85°C Ts, the maximum current is reduced to approximately 800mA (from 1500mA at 25°C). This derating curve ensures the junction temperature does not exceed 125°C.

4.5 Spectrum Distribution

The spectral output peaks at ~465-475nm with a full width at half maximum (FWHM) of about 25-30nm. The spectrum is typical for InGaN blue LEDs, with no significant secondary emission.

4.6 Radiation Diagram

The radiation pattern is Lambertian-like with a half-angle of 60 degrees (120° full angle). Relative luminous intensity drops to 50% at ±60° from the optical axis.

5. Mechanical and Packaging Information

5.1 Package Dimensions

The LED package measures 3.45mm x 3.45mm x 2.20mm (length x width x height). Top view reveals a square light-emitting area; side view shows a thickness of 2.20mm including the ceramic base and silicone lens. Bottom view indicates two electrical pads (anode and cathode) with dimensions 1.30mm x 0.65mm and 0.50mm x 0.65mm respectively. Polarity marking is provided.

5.2 Recommended Soldering Pattern

The suggested PCB land pattern includes two rectangular pads: 1.30mm x 0.85mm for the anode and 1.30mm x 0.50mm for the cathode, with a 0.45mm gap between them. Additional thermal pad (3.50mm x 3.40mm) is recommended for heat dissipation. All dimensions have a tolerance of ±0.2mm.

5.3 Polarity Identification

The cathode is marked with a small notch on the package edge. In the bottom view, the larger pad is typically the anode (positive). Incorrect polarity may permanently damage the LED.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Profile

The recommended SMT reflow profile follows J-STD-020. Key parameters:

• Ramp-up rate: max 3°C/s
• Preheat: 150°C to 200°C for 60-120 seconds
• Time above 217°C (TL): max 60 seconds
• Peak temperature (TP): 260°C, max 10 seconds
• Time within 5°C of peak: max 30 seconds
• Ramp-down rate: max 6°C/s
• Total time from 25°C to peak: max 8 minutes

Reflow should not exceed two cycles. If the interval between reflows exceeds 24 hours, baking is recommended to remove moisture absorbed by the silicone lens.

6.2 Manual Soldering

For hand soldering, keep iron temperature below 300°C and contact time less than 3 seconds. Only one manual soldering operation is allowed. Avoid applying pressure on the silicone lens while hot.

6.3 Handling and Storage

Store the LEDs in the original sealed bag at <30°C and <75% RH. After opening, the device should be used within 168 hours (30°C/60% RH). If storage exceeds 6 months or the moisture indicator changes color, bake at 60±5°C, <5% RH for at least 24 hours before use.

7. Packing and Ordering Information

7.1 Packaging Format

Standard packaging: 1000 pieces per reel. Carrier tape dimensions: 12mm width, 8mm pitch, with 50 empty pockets at both start and end. Reel diameter: 178mm ±1mm, hub diameter 59mm. Label includes part number, spec number, lot code, bin code (flux, wavelength, voltage), quantity, and date code. Moisture barrier bag with desiccant and ESD warning label is used.

7.2 Cardboard Box

Reels are packed in cardboard boxes for mechanical protection during shipping. Customer may specify labeling requirements.

8. Application Recommendations

8.1 Thermal Design

Because of the high power density (up to 5.1W), efficient thermal management is critical. Use a thermal pad on the PCB connected to a large copper area or heatsink. The junction temperature must be kept below 125°C. At 350mA, thermal resistance from junction to solder point should be approximately 10-15°C/W (typical). Derating the current at high ambient temperatures is necessary.

8.2 Circuit Design

Always use current-limiting resistors or constant-current drivers to prevent overcurrent caused by small voltage shifts. Include reverse voltage protection (e.g., a Schottky diode) if the circuit might apply reverse bias. For parallel strings, ensure equal current sharing using individual resistors.

8.3 Compatibility with Materials

Avoid exposing the LED to environments with high sulfur content (>100ppm), as sulfur can corrode the silver pads. Bromine and chlorine content in surrounding materials should each be below 900ppm, and total halogen below 1500ppm. Select adhesives and potting compounds that do not outgas volatile organic compounds (VOCs) which may fog the silicone lens.

9. Technical Comparison with Competing Solutions

Compared to standard plastic package 3535 LEDs (e.g., PLCC), the ceramic package of this LED offers lower thermal resistance (typically 5-10°C/W vs 15-20°C/W), enabling higher drive currents and better lumen maintenance. The silicone lens provides higher optical efficiency and wider viewing angle than epoxy lenses. Additionally, the MSL 1 rating eliminates the need for tedious baking before assembly, reducing production downtime. However, ceramic packages are slightly more expensive, which is offset by superior reliability in high-power applications.

10. Frequently Asked Questions

10.1 Can I drive this LED at 1A continuously?

Yes, but only if the thermal design keeps the junction temperature below 125°C. At 1A (1000mA), the forward voltage will be around 3.2-3.4V, leading to about 3.2-3.4W dissipation. Good heat sinking is mandatory. Refer to the derating curve: at 85°C ambient, maximum current is ~800mA.

10.2 What is the typical lifetime of this LED?

Under rated conditions (350mA, Tj<105°C), lumen maintenance of >70% after 50,000 hours is expected. Higher currents or temperatures will reduce lifetime. For detailed projections, consult the reliability test data (life test: 1000h at 350mA/25°C with no failures).

10.3 How do I handle ESD sensitivity?

The LED has an ESD rating of 2000V HBM. Use grounded workstations, anti-static wrist straps, and conductive packaging. During manual handling, avoid touching the electrical contacts.

11. Practical Design Case Study

Consider a blue LED strip for a plant growth light fixture. Using 24 LEDs per meter, each driven at 350mA (total ~0.84A per meter), the total power per meter is about 24 * 3.0V * 0.35A = 25.2W. The PCB must have a thick copper layer (≥2 oz) and an aluminum core for heat dissipation. To achieve a uniform light distribution, the LEDs are spaced 41.6mm apart. A constant-current driver with a 24V output and current limiting per channel ensures stable operation. The blue wavelength (470nm) is selected for the vegetative growth stage. No additional phosphor is required. The fixture achieves >90% efficiency in converting electrical power to radiant flux.

12. Principle of Operation

This LED uses InGaN (Indium Gallium Nitride) quantum wells as the active layer. When forward biased, electrons and holes recombine in the quantum wells, emitting photons with energy corresponding to the bandgap (approximately 2.6eV for 475nm blue). The substrate is typically sapphire or silicon carbide, on which the epitaxial layers are grown. The ceramic package acts as a heat spreader and provides electrical isolation. A silicone lens encapsulates the die to improve light extraction and protect the chip. The LED's direct bandgap ensures high internal quantum efficiency (>80% at low currents).

13. Development Trends

The industry is moving towards higher efficacy and higher color rendering in white LEDs by combining blue LEDs with phosphors. However, dedicated blue LEDs remain essential for specialty applications such as plant lighting (blue + red spectra), medical phototherapy, and entertainment lighting. Trends include increasing luminous efficacy (target >200 lm/W for blue chips), reducing thermal resistance via improved package designs (e.g., thin-film flip-chip), and integrating ESD protection within the package. The adoption of automated binning at the wafer level allows tighter color and flux distributions, enabling consistent performance in mass production.