LED Spec Sheet Yellow 3.5x2.8x1.85mm - Forward Voltage 3.0V - Power 0.238W - 120° Viewing Angle English Technical Document

1. Product Overview

The RF-A2A31-WYS8-A4 is a high-performance Yellow LED manufactured using a blue chip and phosphor conversion technology. The device is housed in a compact PLCC4 package with dimensions of 3.50 mm × 2.80 mm × 1.85 mm. It is designed to meet the stringent requirements of automotive lighting applications, both interior and exterior, and is qualified under the AEC-Q101 stress test standard for automotive-grade discrete semiconductors.

Key advantages include an extremely wide viewing angle of 120°, compatibility with standard SMT assembly and reflow soldering processes, and a moisture sensitivity level of 2. The LED complies with RoHS and REACH directives, ensuring environmental safety.

2. Technical Parameter In-Depth Objective Analysis

2.1 Electrical and Optical Characteristics (Ts = 25°C)

The LED is tested at a forward current of 50 mA. Under this condition, the forward voltage (VF) ranges from 2.8 V (minimum) to 3.4 V (maximum), with a typical value of 3.0 V. The reverse current (IR) at a reverse voltage of 5 V does not exceed 10 µA. Luminous intensity (IV) is specified between 3500 mcd and 6500 mcd, with a typical value of 5300 mcd. The viewing angle (2θ½) is typically 120°.

2.2 Absolute Maximum Ratings

The absolute maximum ratings at a solder temperature of 25°C are as follows: power dissipation (PD) 238 mW, forward current (IF) 70 mA, peak forward current (IFP) 100 mA (at 1/10 duty cycle, 10 ms pulse width), reverse voltage (VR) 5 V, electrostatic discharge (HBM) 2000 V, operating temperature range (TOPR) -40°C to +100°C, storage temperature range (TSTG) -40°C to +100°C, and junction temperature (TJ) 120°C.

2.3 Thermal Characteristics

The thermal resistance from junction to solder point (RTHJ-S) is specified maximum 180°C/W. Proper thermal management is critical to maintain junction temperature below the maximum rating, as elevated temperature reduces light output and shifts color.

3. Binning System Explanation

3.1 Forward Voltage and Luminous Intensity Bins (IF = 50 mA)

The LED is sorted into bins for forward voltage and luminous intensity. Forward voltage bins are defined as: G1 (2.8-2.9 V), G2 (2.9-3.0 V), H1 (3.0-3.1 V), H2 (3.1-3.2 V), I1 (3.2-3.3 V), I2 (3.3-3.4 V). Luminous intensity bins are: O2 (3500-4300 mcd), P1 (4300-5300 mcd), P2 (5300-6500 mcd).

3.2 Chromaticity Binning

The CIE chromaticity diagram shows a quadrilateral bin designated as 5E. The four corner points are: (0.5536, 0.4221), (0.5764, 0.4075), (0.5883, 0.4111), (0.5705, 0.4289). This ensures tight color consistency for automotive lighting applications where color uniformity is critical.

4. Performance Curve Analysis

4.1 Forward Voltage vs. Forward Current

The forward voltage increases non-linearly with forward current. At 50 mA the typical voltage is 3.0 V; at 70 mA the voltage rises to approximately 3.1 V.

4.2 Forward Current vs. Relative Intensity

Relative intensity increases with current up to 70 mA, reaching about 130% of the value at 50 mA. The curve shows a slight saturation at higher currents.

4.3 Temperature Characteristics

Solder temperature (Ts) affects both forward voltage and relative intensity. As Ts rises from 20°C to 100°C, forward voltage decreases linearly by about 0.15 V, while relative intensity drops by roughly 15%. The maximum allowed forward current also derates with temperature, from 70 mA at 25°C to about 40 mA at 100°C.

4.4 Radiation Diagram

The radiation pattern is Lambertian-like, with a half-angle of about ±60° for 50% relative intensity. The viewing angle (120°) ensures wide coverage for automotive signal lamps.

4.5 Chromaticity Coordinate Shift vs. Forward Current

The CIE x and y coordinates shift slightly with current. At 50 mA the typical point is near (0.57, 0.43). Increasing current to 85°C causes a small shift in the yellow region, remaining within the 5E bin.

4.6 Spectrum Distribution

The emission spectrum peaks at approximately 590 nm, with a full width at half maximum (FWHM) of about 15 nm. The spectrum shows no secondary peaks, confirming pure yellow emission.

5. Mechanical and Packaging Information

5.1 Package Dimensions

The package is 3.50 mm long, 2.80 mm wide, and 1.85 mm high. Tolerances are ±0.2 mm. The top view shows a polarity mark (cathode) at pin 2. The bottom view has four pads: pad 1 is cathode, pad 2 is anode, pads 3 and 4 are mechanical supports (non-connected).

5.2 Soldering Pattern

Recommended PCB land pattern: pad size 0.80 mm × 0.70 mm for each pin, with a central thermal pad of 2.60 mm × 1.60 mm (optional). The distance between pad centers is 2.20 mm.

5.3 Polarity Identification

The polarity mark is a small notch on the top of the package, aligned with the cathode side.

6. Soldering and Assembly Guide

6.1 Reflow Soldering Profile

The recommended reflow profile is based on JEDEC J-STD-020. Preheat from 150°C to 200°C for 60-120 seconds. Ramp-up rate: max 3°C/s. Time above 217°C (TL): 60 seconds max. Peak temperature (TP): 260°C for up to 10 seconds. Cooling rate: max 6°C/s. Total time from 25°C to peak: max 8 minutes. The LED can withstand two reflow cycles; if more than 24 hours elapse between cycles, baking is required.

6.2 Hand Soldering

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

6.3 Storage and Handling

Unopened moisture barrier bags can be stored at ≤30°C and ≤75% RH for up to 1 year. After opening, use within 24 hours at ≤30°C and ≤60% RH. If storage exceeds these limits, bake at 60±5°C for ≥24 hours. The LED surface is soft silicone; avoid mechanical pressure. Do not use ultrasonic cleaning; isopropyl alcohol is recommended.

7. Packaging and Ordering Information

The LED is supplied on tape and reel with 2000 pieces per reel. Carrier tape dimensions: width 8.0 mm, pitch 4.0 mm, cavity size 3.50 mm × 2.80 mm × 1.70 mm. Reel dimensions: A = 330 mm, B = 100 mm, C = 13.0 mm, D = 8.0 mm. Each reel carries a label with part number, spec number, lot number, bin code, luminous flux, chromaticity bin, forward voltage, wavelength code, quantity, and date code. The final packaging includes a moisture barrier bag and cardboard box.

8. Application Recommendations

This Yellow LED is ideal for automotive interior lighting (ambient, reading lights) and exterior signaling (turn signals, brake lights). Due to its wide viewing angle and high brightness, it also suits general indicator applications. Designers should ensure adequate heat sinking to keep the junction temperature below 120°C. A current-limiting resistor is mandatory to prevent overstress. For parallel strings, consider current balancing because of VF binning. The LED is AEC-Q101 qualified, making it suitable for harsh automotive environments.

9. Technical Comparison

Compared to conventional PI film-based yellow LEDs, this phosphor-converted device offers superior color stability and wider viewing angle. The PLCC4 package allows easier PCB assembly and better heat dissipation than smaller packages like 3014. The AEC-Q101 qualification sets it apart from standard commercial LEDs, providing validated reliability for automotive applications.

10. Frequently Asked Questions

Q: What is the typical forward voltage at 50 mA? A: 3.0 V, with a range of 2.8 V to 3.4 V.

Q: Can this LED be used for exterior automotive lighting? A: Yes, it is AEC-Q101 qualified and recommended for both interior and exterior uses.

Q: How many reflow cycles are allowed? A: Maximum two cycles. If more than 24 hours between cycles, bake before second reflow.

Q: What is the recommended storage time after opening the bag? A: Use within 24 hours at ≤30°C / ≤60% RH.

Q: Does the LED require a heat sink? A: For high drive currents or high ambient temperatures, thermal management is necessary. Junction temperature must not exceed 120°C.

11. Practical Application Cases

Case 1: Automotive Turn Signal Module
An array of six RF-A2A31-WYS8-A4 LEDs used in a rear combination lamp. Each LED driven at 50 mA with a common resistor network, achieving 32000 mcd total luminous intensity. The wide 120° viewing angle meets SAE signal requirements. Thermal simulation shows junction temperature of 85°C at ambient 60°C, well below limit.

Case 2: Dashboard Indicator
A single LED used as a warning light. Driven at 30 mA to reduce heat, still providing 3500 mcd brightness. The compact PLCC4 package fits small PCB area. No extra heat sink needed.

12. Principle Introduction

The yellow emission is achieved by coating a blue InGaN LED chip with a yellow-emitting YAG:Ce phosphor. The blue light (450-460 nm) partially excites the phosphor, which emits yellow light (550-600 nm). The combination produces a broad spectrum perceived as yellow. This method offers high efficacy and good color stability compared to direct yellow chips.

13. Development Trends

Phosphor-converted LEDs continue to dominate the automotive market due to cost and performance advantages. Future trends include smaller footprints (e.g., 3030), higher efficacy (100+ lm/W), and improved thermal resistance to reduce derating. The AEC-Q102 qualification (extension of Q101) is becoming mandatory for automotive LEDs. Integration of ESD protection and tighter color binning (MacAdam ellipses) are also expected.