RF-AL-C3535L2K1RB-04 Blue LED Specification - 3.45x3.45x2.20mm - 2.6-3.4V - 5.1W - English

1. Product Overview

This ceramic package LED utilizes InGaN technology on a substrate, delivering high brightness blue light in a compact 3.45mm x 3.45mm x 2.20mm footprint. It is designed for general lighting and specialty applications requiring reliable performance and wide viewing angle.

1.1 General Description

The LED is based on InGaN (Indium Gallium Nitride) semiconductor material grown on a substrate, emitting blue light. The package is a ceramic substrate with a silicone encapsulation, providing excellent thermal management and long-term stability.

1.2 Features

• Ceramic package for superior heat dissipation
• Extremely wide viewing angle (120°)
• Suitable for all SMT assembly and reflow soldering processes
• Available on tape and reel (1000pcs/reel)
• Moisture sensitivity level: Level 1 (MSL1)
• RoHS compliant

1.3 Applications

• Decorative color lamps and lamp strips
• Plant lighting (photosynthesis)
• Landscape and architectural lighting
• Stage photography lighting
• Hotels, retail, office, and residential indoor lighting
• General purpose lighting

2. Technical Parameters

2.1 Electrical and Optical Characteristics (at Ts=25°C, IF=350mA)

2.2 Absolute Maximum Ratings (at Ts=25°C)

Note: The above forward voltage measurement tolerance is ±0.1V. Dominant wavelength tolerance ±1nm. Luminous intensity tolerance ±10%.

3. Binning System

LEDs are sorted into bins for forward voltage, luminous flux, and dominant wavelength at IF=350mA to ensure consistency in application.

3.1 Forward Voltage Bins

3.2 Luminous Flux Bins

3.3 Dominant Wavelength Bins

4. Performance Curves

4.1 Forward Voltage vs. Forward Current

Figure 1-6 shows the forward voltage increasing with forward current. At 350mA the typical VF is around 3.0V. Beyond 1000mA the voltage rises to about 3.4V. This curve is essential for designing constant current drivers.

4.2 Forward Current vs. Relative Intensity

Figure 1-7 indicates that relative luminous intensity increases with forward current, but the slope decreases at higher currents due to efficiency droop. The LED achieves maximum relative intensity near 1750mA.

4.3 Temperature vs. Relative Intensity

As shown in Figure 1-8, the relative intensity decreases as the solder point temperature (Ts) rises. At 115°C the intensity drops to about 60% of the value at 25°C. Proper thermal management is critical.

4.4 Maximum Forward Current vs. Ts

Figure 1-9 provides derating information: at Ts=25°C the maximum forward current is 1500mA, while at Ts=85°C it reduces to approximately 400mA. Always operate within the derated limits.

4.5 Spectral Distribution

The emission spectrum (Figure 1-10) peaks around 455nm with a FWHM of about 20-25nm, typical for InGaN blue LEDs. No secondary peaks are observed.

4.6 Radiation Pattern

The LED has a lambertian-like radiation pattern with a wide 120° viewing angle (half angle 60°). The relative intensity drops to 50% at ±60° from the optical axis.

5. Mechanical and Packaging Information

5.1 Package Dimensions

The LED body is 3.45mm × 3.45mm × 2.20mm (length × width × height). The ceramic substrate provides a robust base. The top view shows a square die area; the side view indicates a height of 2.20mm including the silicone lens. The bottom view reveals two large solder pads for anode and cathode, and a smaller pad for thermal connection. Polarity is marked with a notch or '+' symbol as per Figure 1-4.

5.2 Soldering Pattern

Recommended PCB land pattern dimensions are provided in Figure 1-5. The anode pad is 3.40mm × 1.30mm, cathode pad is 3.50mm × 0.50mm, with a gap of 0.30mm. Ensure proper solder mask and copper thickness for thermal management.

5.3 Carrier Tape and Reel

The LEDs are supplied in 12mm wide carrier tape with 4.0mm pitch pocket dimensions. Each reel contains 1000pcs. The tape has 50 empty pockets at both the leader and trailer sections. Reel dimensions: outer diameter 178±1mm, inner diameter 59mm, width 14.0±0.5mm.

5.4 Label Specification

Each reel is labeled with part number, specification number, lot number, bin code (flux, wavelength, voltage), quantity, and date code.

5.5 Moisture Resistant Packing

The reel is sealed in a moisture barrier bag with a desiccant and a humidity indicator card. The bag is packed in a cardboard box for shipping.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Profile

The recommended reflow profile has a ramp-up rate ≤3°C/s, preheat from 150°C to 200°C for 60-120s, then ramp to 217°C (TL) and stay above TL for >60s but <120s, reaching a peak temperature of 260°C for max 10s. Cooling rate ≤6°C/s. Total time from 25°C to peak ≤8 minutes.

6.2 Hand Soldering

If manual soldering is required, use a soldering iron at ≤300°C for ≤3 seconds, and only one time per joint.

6.3 Cautions

The silicone encapsulant is soft. Do not apply pressure on the lens during pick-and-place or after soldering. Avoid warping the PCB after soldering. Do not quickly cool the LED after reflow.

7. Packaging and Ordering Information

Standard packaging: 1000 pieces per reel. Multiple reels are packed in a moisture barrier bag and then in a cardboard box. Storage conditions before opening: temperature ≤30°C, humidity ≤75% RH for up to 6 months. After opening: use within 168 hours at ≤30°C, ≤60% RH. If exceeded, bake at 60±5°C, <5% RH for 24 hours.

Ordering information includes part number designating flux and wavelength bins. Please consult the manufacturer for specific bin availability.

8. Application Suggestions

8.1 Thermal Design

Given the high power capability, adequate heat sinking is required to keep the junction temperature below 125°C. Use thermal vias and a metal-core PCB (MCPCB) for high current applications.

8.2 Current Regulation

Always use a constant current source. Resistors alone are insufficient for series/parallel strings. Consider the VF bin variation and apply appropriate current balancing.

8.3 Environmental Compatibility

Avoid exposure to sulfur compounds (>100ppm), bromine and chlorine (>900ppm each, total <1500ppm). Do not use adhesives or potting materials that outgas volatile organic compounds (VOCs) that can discolor the silicone.

8.4 Electrostatic Discharge

These LEDs are ESD sensitive (HBM 2kV). Use grounded workstations, antistatic wrist straps, and ionizers during handling.

9. Technical Comparison

Compared to traditional PLCC (plastic leaded chip carrier) LEDs, the ceramic package offers lower thermal resistance, higher reliability at elevated temperatures, and better resistance to sulfur attack. The wide 120° viewing angle makes it suitable for diffused lighting applications. The availability of multiple flux and color bins allows fine-tuning of light output and color consistency.

10. Frequently Asked Questions

Q: What is the recommended forward current for optimal efficiency? A: At 350mA the LED provides a good balance of flux and efficacy. Higher currents increase output but reduce efficiency due to droop.

Q: Can these LEDs be used in parallel? A: Yes, but each LED should have its own current-limiting resistor or be driven by a constant current source to account for VF variation.

Q: How should I clean the LEDs after soldering? A: Isopropyl alcohol is recommended. Do not use ultrasonic cleaning as it may damage the LED.

Q: What is the storage life? A: Unopened bags can be stored for 6 months under 30°C/75%RH. After opening, use within 168 hours or bake before use.

11. Case Study: Plant Growth Lighting

A horticultural lighting fixture was designed using 100 pieces of this blue LED combined with red LEDs to produce a spectrum optimized for photosynthesis. The LEDs were mounted on an aluminum MCPCB with thermal vias. Operating at 350mA, the fixture delivered 4000 lumens of blue light with a dominant wavelength of 450nm, covering a 1m² growing area. The ceramic package ensured stable operation at an ambient temperature of 40°C. The wide viewing angle eliminated the need for secondary optics in close-canopy applications.

12. Principle of Operation

This blue LED is based on an InGaN/GaN multiple quantum well structure grown on a sapphire or silicon substrate. When forward bias is applied, electrons and holes recombine in the active region, releasing energy in the form of photons. The bandgap energy of InGaN determines the emitted wavelength, which for this device falls in the blue region (445-460 nm). The ceramic package provides electrical isolation and efficient heat transfer from the die to the PCB.

13. Development Trends

The trend in high-power LED packaging is toward smaller footprints with higher current capabilities. Ceramic packages like this one are becoming standard for applications requiring high reliability and thermal performance. Future developments include further improvements in wall-plug efficiency, narrower binning distributions for better color consistency, and integration of smart control features directly into the package.