SMD LED Tri-Color White Diffused Specification - Package 3.5x3.2x1.9mm - Voltage 1.8-3.7V - Power 0.56-0.89W - English Technical Document

1. Product Overview

This document details the specifications for a high-performance, surface-mount tri-color LED. The device integrates Red, Green, and Blue semiconductor chips within a single white diffused lens package, enabling the creation of a broad spectrum of colors through individual or combined operation. Designed for automated assembly processes, it is ideal for space-constrained applications requiring status indication, backlighting, or symbolic illumination.

1.1 Core Advantages

• Compliant with RoHS environmental standards.
• Packaged on 12mm tape for 7-inch diameter reels, compatible with high-speed pick-and-place equipment.
• Standardized EIA package footprint ensures design compatibility.
• Integrated Circuit (I.C.) compatible drive levels.
• Withstands infrared reflow soldering processes, suitable for lead-free assembly.
• Preconditioned to JEDEC Level 3 moisture sensitivity standards for reliability.

1.2 Target Markets

This component is suitable for a wide array of electronic equipment, including but not limited to telecommunications devices (cordless/cellular phones), portable computing (notebooks), networking systems, home appliances, industrial control panels, and indoor signage applications where multi-color indication or lighting is required.

2. Technical Parameters: In-Depth Objective Interpretation

2.1 Absolute Maximum Ratings

All ratings are specified at an ambient temperature (Ta) of 25°C. Exceeding these limits may cause permanent damage.

• Power Dissipation (Pd): Varies by color: Green: 740 mW, Red: 560 mW, Blue: 888 mW. This parameter defines the maximum power the LED can dissipate as heat.
• Peak Forward Current (I_F(PEAK)): Measured under pulsed conditions (1/10 duty cycle, 0.1ms pulse width). Green/Red: 400 mA, Blue: 500 mA.
• Continuous Forward Current (I_F): The maximum permissible DC current. Green/Red: 200 mA, Blue: 240 mA.
• Operating Temperature Range: -40°C to +85°C.
• Storage Temperature Range: -40°C to +100°C.

2.2 Thermal Characteristics

Thermal management is critical for LED performance and longevity.

• Maximum Junction Temperature (T_j): Green/Blue: 125°C, Red: 115°C. The semiconductor die must not exceed this temperature.
• Thermal Resistance, Junction-to-Ambient (R_θJA): Green: 70 °C/W, Red/Blue: 40 °C/W. This value indicates how effectively heat is transferred from the chip to the surrounding air. A lower value signifies better thermal performance. The higher value for the green chip may require more careful thermal design in high-power applications.

2.3 Electrical & Optical Characteristics

Measured at Ta=25°C under specified test currents (Red: 150mA, Green/Blue: 120mA).

• Luminous Intensity (I_v): The perceived brightness. Green: 8000-17000 mcd, Red: 5500-13000 mcd, Blue: 1500-3200 mcd. The human eye is less sensitive to blue light, resulting in lower mcd values for similar radiant power.
• Viewing Angle (2θ_1/2): Typically 120 degrees. This wide angle, facilitated by the diffused lens, provides a uniform, non-directional light output suitable for panel illumination.
• Dominant Wavelength (λ_d): Defines the perceived color. Green: 515-530 nm, Red: 615-630 nm, Blue: 448-463 nm.
• Peak Emission Wavelength (λ_p): The wavelength at which the spectral power distribution is maximum. Typically: Green: 521 nm, Red: 631 nm, Blue: 445 nm.
• Spectral Line Half-Width (Δλ): The bandwidth of the emitted light. Typically: Green: 30 nm, Red: 20 nm, Blue: 25 nm.
• Forward Voltage (V_F): The voltage drop across the LED at the test current. Green/Blue: 2.7-3.7 V, Red: 1.8-2.8 V. The red chip, typically based on AlInGaP, has a lower bandgap and thus a lower forward voltage than the InGaN-based green and blue chips.
• Reverse Current (I_R): Maximum 10 μA at V_R=5V. This device is not designed for reverse bias operation; this parameter is for test purposes only.

3. Binning System Explanation

The LEDs are sorted into bins based on key optical parameters to ensure color and brightness consistency within a production batch.

3.1 Luminous Intensity Binning

Units: mcd @ specified test currents. Each bin code (L1-L8) defines a min/max range for each color. For example, bin L1 for Green covers 8000-12000 mcd, while L5 covers 12000-17000 mcd. Tolerance within each intensity bin is +/-11%.

3.2 Dominant Wavelength Binning

Units: nm @ specified test currents. Bin codes D1-D9 define narrow wavelength ranges for each color (e.g., D1 for Green: 515-520 nm, D7: 525-530 nm). Tolerance for each dominant wavelength bin is +/- 1 nm, allowing for precise color matching.

4. Performance Curve Analysis

4.1 Relative Intensity vs. Wavelength (Spectrum)

The spectral distribution curves show distinct, relatively narrow peaks for each color chip, confirming the purity of the red, green, and blue emissions. The half-width values indicate the spectral purity, with red being the narrowest.

4.2 Forward Current vs. Forward Voltage (I-V Curve)

The I-V curves demonstrate the exponential relationship typical of diodes. The curves for Green and Blue are closely aligned due to their similar InGaN material system and higher bandgap, while the Red curve is offset to lower voltages.

4.3 Forward Current vs. Ambient Temperature (Derating Curve)

This graph shows the maximum allowable continuous forward current decreasing as ambient temperature increases. This derating is essential to prevent the junction temperature from exceeding its maximum rating. The curves differ slightly between colors due to variations in thermal resistance and maximum junction temperature.

4.4 Relative Luminous Intensity vs. Forward Current

The light output increases with current but exhibits sub-linear behavior at higher currents, primarily due to thermal effects and efficiency droop. This highlights the importance of driving the LED within its specified range for optimal efficiency and lifetime.

4.5 Spatial Distribution (Viewing Angle Pattern)

The polar diagram confirms the Lambertian-like emission pattern with a full viewing angle of approximately 120 degrees, characteristic of a diffused lens which scatters light to create a wide, even illumination.

5. Mechanical & Packaging Information

5.1 Package Dimensions

The SMD package measures approximately 3.5mm (L) x 3.2mm (W) x 1.9mm (H). All dimensions are in millimeters with a standard tolerance of ±0.2mm unless otherwise noted. A detailed dimensional drawing should be referenced for exact pad layout and keep-out areas.

5.2 Pin Assignment

The 6-pin package assigns individual anodes and cathodes for each color chip: Pins 1 & 6: Blue, Pins 2 & 5: Red, Pins 3 & 4: Green. This configuration allows for independent control of each color.

5.3 Recommended PCB Attachment Pad

A land pattern design is provided to ensure proper soldering, mechanical stability, and optimal thermal conduction away from the LED. Adhering to this recommendation is crucial for assembly yield and long-term reliability.

6. Soldering & Assembly Guidelines

6.1 Recommended IR Reflow Profile

A detailed reflow soldering profile compliant with J-STD-020B for lead-free processes is specified. This profile includes preheat, soak, reflow (peak temperature), and cooling stages with defined time and temperature limits to prevent thermal damage to the LED package and internal die.

6.2 Cleaning

If cleaning after soldering is necessary, only immersion in ethyl alcohol or isopropyl alcohol at normal temperature for less than one minute is recommended. Unspecified chemicals may damage the epoxy lens or package.

6.3 Storage Conditions

Sealed Package: Store at ≤30°C and ≤70% Relative Humidity (RH). The components are rated for a floor life of one year in the moisture-proof bag with desiccant.
Opened Package: For components removed from their sealed bag, the storage ambient should not exceed 30°C and 60% RH. It is recommended to complete IR reflow within 168 hours (7 days) of exposure. For longer storage, use a sealed container with desiccant or a nitrogen desiccator.

7. Packaging & Ordering Information

7.1 Tape and Reel Specifications

The components are supplied on 12mm wide embossed carrier tape wound onto 7-inch (178mm) diameter reels. Standard reel quantity is 1500 pieces. A minimum packing quantity of 500 pieces is available for remainder orders. Packaging conforms to EIA-481-1-B specifications.

8. Application Suggestions

8.1 Typical Application Circuits

Each color channel requires a current-limiting resistor in series with the LED. The resistor value is calculated as R = (V_supply - V_F) / I_F, where V_F and I_F are the target forward voltage and current for the specific color. Microcontrollers or dedicated LED driver ICs can be used for PWM dimming or color mixing.

8.2 Design Considerations

• Thermal Management: Ensure adequate PCB copper area (thermal pads) and possible ventilation to manage the heat dissipation, especially for the green channel which has higher thermal resistance.
• Current Driving: Do not exceed the absolute maximum DC forward current. For extended lifespan and stable color output, consider operating below the maximum rating.
• ESD Protection: Although not explicitly stated as sensitive, standard ESD handling precautions for semiconductor devices are recommended during assembly.

9. Technical Comparison & Differentiation

This tri-color LED in a white diffused package offers key advantages:

• Integrated Solution: Combines three discrete colors in one package, saving PCB space and simplifying assembly compared to using three separate LEDs.
• Color Mixing Capability: Enables the generation of secondary colors (yellow, cyan, magenta) and white by independently controlling the intensity of each primary color chip.
• Uniform Appearance: The white diffused lens blends the light from the individual chips when viewed off-axis, providing a consistent, milky-white appearance when off, and a uniform colored glow when illuminated.
• High Brightness: Offers high luminous intensity across all three colors, suitable for applications requiring good visibility even in well-lit conditions.

10. Frequently Asked Questions (Based on Technical Parameters)

10.1 Can I drive all three colors simultaneously at their maximum current?

No. The total power dissipation must be considered. Simultaneously driving Red (150mA @ ~2.3V = 345mW), Green (120mA @ ~3.2V = 384mW), and Blue (120mA @ ~3.2V = 384mW) would result in a total internal dissipation of approximately 1113mW, which exceeds the maximum power dissipation rating for any single chip (888mW max for Blue) and would cause severe overheating. The thermal design must account for the combined heat from all active chips.

10.2 Why is the forward voltage different for each color?

The forward voltage is determined by the semiconductor material's bandgap energy. Red LEDs typically use AlInGaP which has a lower bandgap (~1.9-2.0 eV), resulting in a lower V_F. Green and Blue LEDs use InGaN with higher bandgaps (~2.4 eV for Green, ~2.7 eV for Blue), leading to higher V_F.

10.3 How do I achieve white light with this LED?

White light can be created by mixing the red, green, and blue light in appropriate intensities. This is an additive color mixing process. The specific ratios (which depend on the binning of the individual chips and target white point e.g., cool white, warm white) must be calibrated through PWM control or adjusted current levels for each channel.

11. Practical Use Case

Scenario: Status Indicator for a Network Router: A single tri-color LED can replace three single-color LEDs to indicate multiple device states: Solid Green for "Normal Operation," Flashing Blue for "Data Transfer," and Solid Red for "Error/Fault." This simplifies the front panel design, reduces component count, and allows for a cleaner aesthetic with a single illuminated aperture that changes color.

12. Operating Principle Introduction

Light Emitting Diodes (LEDs) are semiconductor devices that emit light through electroluminescence. When a forward voltage is applied across the p-n junction, electrons and holes recombine in the active region, releasing energy in the form of photons. The wavelength (color) of the emitted light is determined by the bandgap energy of the semiconductor material used. In this device, three separate semiconductor chips (Red: AlInGaP, Green/Blue: InGaN) are housed together. The white diffused epoxy lens encapsulates the chips, both for protection and to scatter the emitted light, creating a wide, uniform viewing angle.

13. Technology Trends

The development of SMD LEDs continues to focus on several key areas: increased luminous efficacy (more light output per watt of electrical input), improved color rendering and consistency, higher power density handling through enhanced thermal packaging, and further miniaturization. The integration of multiple colors or even phosphor-converted white chips within a single package, as seen in this component, is a trend aimed at simplifying end-product design and enabling advanced lighting effects. Furthermore, there is ongoing research into novel semiconductor materials to improve efficiency, particularly in the green spectral region, and to expand the available color gamut.