LED RF-A4E27-R15E-R4 Red LED Specification - Size 2.7x2.0x0.6mm - Forward Voltage 2.0V to 2.6V - Power 520mW - English Technical Datasheet

1. Product Overview

The RF-A4E27-R15E-R4 is a high-performance red light emitting diode (LED) based on AlGaInP semiconductor technology on a substrate. It is housed in a compact EMC (Epoxy Molding Compound) package measuring 2.7mm x 2.0mm x 0.6mm, designed for surface mount technology (SMT) assembly. This LED offers an extremely wide viewing angle of 120 degrees, making it ideal for applications requiring uniform light distribution. It is qualified according to AEC-Q102 stress test guidelines for automotive-grade discrete semiconductors, ensuring reliability for demanding environments. The product is RoHS compliant and has a moisture sensitivity level of 2 (MSL 2).

1.1 Features

• EMC package for robust mechanical and thermal performance
• Extremely wide viewing angle (2θ_1/2 = 120°)
• Suitable for all SMT assembly and solder processes
• Available on tape and reel for automated pick-and-place
• Moisture sensitivity level: Level 2
• RoHS compliant
• Qualified per AEC-Q102 guidelines

1.2 Applications

Automotive lighting for both interior and exterior applications, including dashboard indicators, courtesy lights, ambient lighting, tail lights, and other signaling functions.

2. Technical Specifications

2.1 Electrical and Optical Characteristics (at Ts=25°C, IF=150mA)

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

Notes: - All measurements are made under standardized conditions at Refond. - The maximum current should be determined after measuring package temperature to ensure junction temperature does not exceed 150°C. - At 25°C, pulse mode test yields photoelectric conversion efficiency ηe = 45%.

3. Bin System

To ensure consistent performance, each LED is sorted into bins based on forward voltage, luminous flux, and dominant wavelength. The bin ranges at IF=150mA and Ts=25°C are as follows:

3.1 Forward Voltage Bins

3.2 Luminous Flux Bins

3.3 Dominant Wavelength Bins

4. Performance Curves Analysis

The data sheet includes several typical optical and electrical characteristics curves measured at 25°C unless otherwise noted. Understanding these curves is essential for proper circuit design and thermal management.

4.1 Forward Voltage vs. Forward Current (Fig. 1-6)

This curve shows the exponential relationship between VF and IF. At 150mA the forward voltage is typically around 2.3V (midpoint of the bin range). The curve helps to predict current variations due to voltage changes.

4.2 Forward Current vs. Relative Luminous Flux (Fig. 1-7)

Relative luminous flux increases with forward current but not linearly. At low currents the efficiency is higher; the curve saturates above 150mA. This indicates that operating near the rated current offers good luminous efficacy while staying within safe thermal limits.

4.3 Junction Temperature vs. Relative Luminous Flux (Fig. 1-8)

As junction temperature rises, the LED becomes less efficient. At Tj=125°C, the relative flux drops to about 85% of the value at 25°C. This necessitates adequate heat sinking in high-temperature automotive environments.

4.4 Solder Temperature vs. Forward Current (Fig. 1-9)

This derating curve shows the maximum allowed forward current as a function of solder point temperature. For example, at Ts=100°C the allowable current decreases to about 150mA. Designers must ensure that the actual operating point falls below this curve.

4.5 Voltage Shift vs. Junction Temperature (Fig. 1-10)

Forward voltage decreases by approximately 0.2V when temperature rises from -40°C to 125°C. This negative temperature coefficient needs to be considered in constant-current drivers to avoid current increase at high temperature.

4.6 Radiation Diagram (Fig. 1-11)

The LED has a wide radiation pattern with a half-intensity angle of ±60° (total 120°). The intensity is relatively uniform across the beam, making it suitable for area lighting without secondary optics in some cases.

4.7 Dominant Wavelength Shift vs. Junction Temperature (Fig. 1-12)

The dominant wavelength shifts toward longer wavelengths (red shift) as temperature increases. The shift is approximately +8nm from -40°C to 125°C. This color shift must be accounted for in color-critical applications.

4.8 Spectrum Distribution (Fig. 1-13)

The emission spectrum peaks around 620nm with a full-width at half-maximum (FWHM) of about 20nm. The purity is high, which is typical for AlGaInP red LEDs.

5. Mechanical and Packaging Information

5.1 Package Dimensions

The LED package has dimensions of 2.70mm (length) × 2.00mm (width) × 0.60mm (height). The top view shows a light-emitting area of 1.70mm × 2.40mm. The bottom view indicates two anode and two cathode pads for optimized thermal and electrical connection. The soldering patterns recommended include a central pad for heat dissipation.

5.2 Carrier Tape and Reel

The LEDs are supplied in 8mm wide carrier tape with 4mm pitch, wound on a 180mm diameter reel. Each reel contains 4000 pieces. The tape includes a cover tape and is sealed in a moisture barrier bag with desiccant and a humidity indicator card.

5.3 Label Information

Each reel is labeled with part number, spec number, lot number, bin code (luminous flux, chromaticity, forward voltage, wavelength), quantity, and manufacture date.

6. Soldering and Assembly Guidelines

6.1 SMT Reflow Soldering Profile

The LED is designed to withstand two reflow cycles with a peak temperature of 260°C (max 10s at peak). The recommended reflow profile:

• Preheat: 150°C to 200°C for 60–120s
• Time above 217°C: max 60s
• Peak temperature: 260°C
• Cooling rate: max 6°C/s
• Total time from 25°C to peak: max 8 minutes

Do not perform more than two reflow cycles. If the interval between cycles exceeds 24 hours, the LEDs may absorb moisture and need baking.

6.2 Repairing and Handling

Repair of soldered LEDs is not recommended. If unavoidable, use a dual-head soldering iron. Do not apply mechanical stress to the silicone encapsulant during or after soldering. Avoid rapid cooling and warping of the PCB.

7. Handling Precautions

• Sulfur and Halogen Control: The environment and mating materials must contain less than 100ppm sulfur and less than 900ppm bromine or chlorine individually, and total Br+Cl less than 1500ppm.
• Outgassing: Volatile organic compounds can penetrate the silicone lens and cause discoloration. Use adhesives that do not outgas organic vapors.
• Mechanical Handling: Use forceps on the side surfaces. Do not touch or press the silicone lens, as it may damage internal circuitry.
• ESD Protection: The LED is sensitive to electrostatic discharge (HBM 2000V). Use proper grounding and anti-static precautions.
• Thermal Design: Always ensure that the junction temperature does not exceed 150°C. Use thermal simulations or measurements to verify proper heat sinking.
• Cleaning: If cleaning is required, use isopropyl alcohol. Do not use ultrasonic cleaning, as it may damage the LED.
• Storage: Unopened bags: <30°C, <75% humidity, use within 1 year. After opening, use within 24 hours under <30°C and <60% humidity. If exceeded, bake at 60±5°C for at least 24 hours before use.

8. Application Considerations

When designing with the RF-A4E27-R15E-R4, pay attention to the following points:

• Current Regulation: Use a constant-current driver to avoid thermal runaway. The forward voltage variation (2.0V to 2.6V) requires a driver that can accommodate the range.
• Thermal Management: The LED’s thermal resistance (Rth JS real = 40°C/W typical) means that at 150mA, with a forward voltage of 2.3V, the power dissipation is about 345mW, causing a junction-to-solder temperature rise of ~13.8°C. In a 85°C ambient, the junction would be around 99°C, which is safe. However, if many LEDs are packed closely, additional heat sinking is needed.
• Optical Design: The wide 120° viewing angle may be advantageous for general illumination, but for focused beams, external optics such as lenses or reflectors should be considered. The spectrum does not contain UV or IR components, so no special filtering is needed.
• Automotive Compliance: The AEC-Q102 qualification covers stress tests like thermal shock, life test, and high humidity. However, designers must still validate the LED in their specific fixture environment, especially regarding vibration and chemical exposure.

9. Reliability and Quality Assurance

The product qualification test plan follows AEC-Q102 guidelines. Reliability tests include:

• Reflow (260°C, 10s, 2 cycles): 0/1 failure allowed
• MSL 2 (85°C/60%RH, 168h): 0/1 failure
• Thermal shock (-40°C to 125°C, 1000 cycles): 0/1 failure
• Life test (Ta=105°C, IF=150mA, 1000h): 0/1 failure
• High temperature high humidity (85°C/85%RH, IF=150mA, 1000h): 0/1 failure

Failure criteria: Forward voltage > 1.1×USL, reverse current > 2×USL, luminous flux < 0.7×LSL.

Note that these tests are performed under good heat dissipation conditions on single LEDs. In array applications, derating may be required.

10. Principles of Operation

The LED uses an AlGaInP (Aluminum Gallium Indium Phosphide) multi-quantum-well structure grown on a GaAs substrate. This material system is well-known for high efficiency in the red to amber spectral range. The EMC package provides mechanical rigidity and good thermal conductivity, allowing the LED to operate at higher currents than traditional epoxy packages. The wide viewing angle is achieved by the encapsulation shape and the chip design.

11. Comparison with Alternative Technologies

Compared to conventional through-hole red LEDs, the RF-A4E27-R15E-R4 offers much smaller footprint, lower profile, and compatibility with automated SMT assembly. Its EMC package provides better moisture resistance and higher reliability under thermal cycling. The AEC-Q102 qualification makes it suitable for automotive use, which is not always available for generic LEDs. However, the cost per lumen may be higher than some high-volume consumer LEDs, but justified for mission-critical applications.

12. Frequently Asked Questions

Q: Can this LED be used with a constant voltage supply?
A: It is recommended to use a constant-current driver because forward voltage varies. Constant voltage can lead to current exceeding the maximum if the voltage is at the high end of the bin.

Q: What is the typical lifetime at 150mA?
A: While specific L70/B10 data is not provided in this datasheet, the AEC-Q102 life test at 105°C for 1000 hours without failure suggests good longevity. For automotive interior applications, lifetimes >10,000 hours are expected under proper thermal management.

Q: Can I use these LEDs in parallel?
A: Paralleling is possible but must be done with current balancing resistors or a shared constant-current source to avoid current hogging due to VF variation.

Q: Are these LEDs compatible with lead-free soldering?
A: Yes, the peak temperature of 260°C is compatible with typical lead-free profiles.

Q: How should I bake the LEDs before use if the moisture barrier bag has been opened too long?
A: Bake at 60±5°C for at least 24 hours. Do not exceed 48 hours to avoid damage.

13. Practical Design Example

Consider a daytime running light (DRL) module requiring 50lm per unit. Using the highest bin (MB: 33.4-37.0lm), two LEDs in series would achieve ~70lm at 150mA. With a typical VF of 2.3V each, the total forward voltage is 4.6V. A boost-type constant-current driver with an input of 12V automotive bus can efficiently drive the string. The PCB should include a thermal pad connected to the metal core of the board to keep junction temperature below 100°C in an under-hood environment (ambient up to 85°C). Optical simulation using the radiation diagram shows that a simple diffuser can achieve the required photometric pattern without secondary reflectors.

14. Industry Trends

The automotive lighting industry continues to shift towards all-semiconductor solutions, with red LEDs replacing incandescent bulbs for stop/tail and turn signals. AEC-Q102 qualification is becoming a baseline requirement. Future developments include higher efficacy (target > 150 lm/W for red) and integration with smart drivers for adaptive lighting. The RF-A4E27-R15E-R4 represents a mature, reliable option that meets current automotive requirements with good performance and ease of assembly.