SMD LED 18-225A/R6GHW-B01/3T Datasheet - Package 3.2x1.6x1.3mm - Voltage 2.0V/3.3V - Brilliant Red/Green - English Technical Document

1. Product Overview

The 18-225A series represents a compact, high-performance Surface Mount Device (SMD) LED solution. This datasheet covers two primary chip material variants: the R6 (AlGaInP) for brilliant red emission and the GH (InGaN) for brilliant green emission. The device is packaged in white diffused resin. Its core advantage lies in its significantly reduced footprint compared to traditional lead-frame type LEDs, enabling higher packing density on PCBs, reduced storage space requirements, and ultimately contributing to the miniaturization of end equipment. The lightweight construction further makes it ideal for applications where space and weight are critical constraints.

2. Technical Parameter Deep Dive

2.1 Absolute Maximum Ratings

Operating the device beyond these limits may cause permanent damage. The ratings are specified at an ambient temperature (Ta) of 25°C.

• Reverse Voltage (V_R): 5 V (for both R6 and GH). Exceeding this can cause junction breakdown.
• Forward Current (I_F): 25 mA (Continuous DC for both R6 and GH).
• Peak Forward Current (I_FP): 60 mA for R6, 100 mA for GH. This is specified at a duty cycle of 1/10 and a frequency of 1 kHz, suitable for pulsed operation.
• Power Dissipation (P_d): 60 mW for R6, 95 mW for GH. This is the maximum allowable power the package can dissipate without exceeding its thermal limits.
• Electrostatic Discharge (ESD) Human Body Model (HBM): 2000 V for R6, 150 V for GH. The GH (InGaN) variant is more sensitive to ESD, requiring stricter handling precautions.
• Operating Temperature (T_opr): -40°C to +85°C. This defines the ambient temperature range for reliable operation.
• Storage Temperature (T_stg): -40°C to +90°C.
• Soldering Temperature (T_sol): Reflow soldering: 260°C peak for 10 seconds maximum. Hand soldering: 350°C for 3 seconds maximum.

2.2 Electro-Optical Characteristics

These parameters are measured at Ta=25°C and a standard test current of I_F=10mA, unless otherwise noted. They define the light output and electrical behavior of the LED.

• Luminous Intensity (I_v): R6: 28.5 to 72.0 mcd (typical). GH: 72.0 to 180 mcd (typical). The GH chip produces significantly higher luminous intensity under the same drive conditions.
• Viewing Angle (2θ_1/2): 130 degrees (typical). This wide viewing angle is characteristic of the white diffused resin package, providing a Lambertian-like emission pattern suitable for area illumination and indicators.
• Peak Wavelength (λ_p): R6: 632 nm (typical). GH: 518 nm (typical). This is the wavelength at which the spectral power distribution is maximum.
• Dominant Wavelength (λ_d): R6: 615-625 nm. GH: 520-535 nm. This is the single-wavelength perception of the LED's color by the human eye. Tolerances are ±1nm.
• Spectrum Radiation Bandwidth (Δλ): R6: 20 nm (typical). GH: 35 nm (typical). This indicates the spectral purity; a smaller bandwidth means a more saturated color.
• Forward Voltage (V_F): R6: 1.7-2.4 V (Typical 2.0V). GH: 2.7-3.7 V (Typical 3.3V). The voltage drop is a function of the semiconductor material's bandgap. Tolerance is ±0.10V.
• Reverse Current (I_R): R6: 10 μA max at V_R=5V. GH: 50 μA max at V_R=5V.

3. Binning System Explanation

The LEDs are sorted (binned) based on key optical parameters to ensure consistency within a production batch and for design purposes.

3.1 Luminous Intensity Binning

R6 (Red):

• Bin N: 28.5 - 45.0 mcd
• Bin P: 45.0 - 72.0 mcd

GH (Green):

• Bin Q1: 72.0 - 90.0 mcd
• Bin Q2: 90.0 - 112 mcd
• Bin R1: 112 - 140 mcd
• Bin R2: 140 - 180 mcd

Tolerance for luminous intensity is ±11%.

3.2 Dominant Wavelength Binning (GH Green only)

The green LEDs are further binned by dominant wavelength to control color consistency.

• Bin 1: 520 - 525 nm
• Bin 2: 525 - 530 nm
• Bin 3: 530 - 535 nm

Tolerance for dominant wavelength is ±1nm.

4. Performance Curve Analysis

4.1 R6 (AlGaInP Red) Characteristics

The provided curves illustrate key relationships:

• Forward Current vs. Forward Voltage (I-V Curve): Shows the exponential relationship. The forward voltage increases with current and decreases slightly with rising temperature.
• Luminous Intensity vs. Forward Current: Light output increases linearly with current in the normal operating range before saturation effects.
• Luminous Intensity vs. Ambient Temperature: Light output decreases as ambient temperature rises due to reduced internal quantum efficiency and increased non-radiative recombination. This derating is critical for thermal management.
• Forward Current Derating Curve: Specifies the maximum allowable continuous forward current as a function of ambient temperature. The current must be reduced at higher temperatures to stay within the power dissipation limit.
• Spectrum Distribution: Shows the emission peak around 632 nm with a typical bandwidth of 20 nm.
• Radiation Diagram: Depicts the spatial intensity distribution, confirming the wide 130-degree viewing angle with a near-Lambertian pattern.

4.2 GH (InGaN Green) Characteristics

The GH curves show similar relationships but with different quantitative values:

• Higher forward voltage (typical 3.3V vs. 2.0V for R6).
• Different temperature dependence of luminous intensity and forward voltage.
• Spectrum centered around 518 nm with a broader 35 nm bandwidth.
• A different forward current derating profile due to its different power dissipation rating (95 mW vs. 60 mW).

5. Mechanical & Package Information

5.1 Package Dimensions

The SMD package has the following key dimensions (in mm, tolerance ±0.1mm unless specified):

• Length: 3.2 mm
• Width: 1.6 mm
• Height: 1.3 mm ±0.2 mm
• Lead Width: 0.4 mm ±0.15 mm
• Lead Length: 0.7 mm ±0.1 mm
• Lead Pitch: 1.6 mm

5.2 Polarity Identification and Pad Design

The cathode is marked. A recommended solder pad layout is provided with dimensions: pad width 0.8mm, length 0.8mm, with a 0.4mm gap between pads. This is a suggestion; the pad design should be optimized based on the specific PCB manufacturing process and thermal requirements. The document emphasizes that the pad dimension can be modified based on individual needs.

6. Soldering & Assembly Guidelines

6.1 Soldering Process

The device is compatible with infrared and vapor phase reflow processes. A Pb-free reflow soldering profile is specified:

• Pre-heating: 150-200°C for 60-120 seconds.
• Time above liquidus (217°C): 60-150 seconds.
• Peak Temperature: 260°C maximum.
• Time within 5°C of peak: 10 seconds maximum.
• Heating Rate: 3°C/sec maximum.
• Cooling Rate: 6°C/sec maximum.

Critical Notes: Reflow soldering should not be performed more than two times. No stress should be applied to the LED body during heating. The PCB should not be warped after soldering.

6.2 Storage and Moisture Sensitivity

The components are packaged in moisture-resistant barrier bags with desiccant.

• Before opening: Store at ≤30°C and ≤90% RH.
• After opening: The "floor life" is 1 year at ≤30°C and ≤60% RH. Unused parts must be resealed in a moisture-proof package.
• Baking: If the desiccant indicator changes or the storage time is exceeded, bake at 60±5°C for 24 hours before use to remove absorbed moisture and prevent "popcorn" effect during reflow.

7. Packaging & Ordering Information

7.1 Reel and Tape Specifications

The LEDs are supplied in 8mm wide embossed carrier tape on 7-inch diameter reels. The loaded quantity is 3000 pieces per reel. Detailed reel and carrier tape dimensions are provided in the datasheet.

7.2 Label Explanation

The reel label contains several codes:

• P/N: Product Number (e.g., 18-225A/R6GHW-B01/3T).
• QTY: Packing Quantity.
• CAT: Luminous Intensity Rank (Bin code, e.g., P, R1).
• HUE: Chromaticity Coordinates & Dominant Wavelength Rank (e.g., Bin 2).
• REF: Forward Voltage Rank.
• LOT No: Traceable Lot Number.

8. Application Suggestions

8.1 Typical Application Scenarios

As listed in the datasheet:

• Backlighting for automotive dashboards and switches.
• Telecommunication equipment: Status indicators and keypad backlighting in phones and fax machines.
• Flat backlighting for small LCDs, switches, and symbols.
• General purpose indicator and status lights in consumer electronics, industrial controls, and appliances.

8.2 Critical Design Considerations

Current Limiting: An external current-limiting resistor is absolutely mandatory. The LED's forward voltage has a negative temperature coefficient and a tight tolerance. A small increase in supply voltage can cause a large, potentially destructive increase in forward current. The resistor value must be calculated based on the supply voltage (V_CC), the LED's typical forward voltage (V_F), and the desired forward current (I_F): R = (V_CC - V_F) / I_F. Thermal Management: Although a small SMD device, power dissipation (up to 95mW for GH) must be considered, especially at high ambient temperatures. Adhere to the forward current derating curve. Ensure adequate PCB copper area (using the thermal pad design) to conduct heat away from the LED junction. ESD Protection: Implement standard ESD handling procedures, particularly for the more sensitive GH (InGaN) variant. Consider using ESD protection devices on sensitive lines if the LED is in a user-accessible area.

9. Technical Comparison & Differentiation

The 18-225A series offers a clear advantage over larger, through-hole LEDs in terms of board space and automated assembly compatibility. Within the SMD LED landscape, its key differentiators are:

• Wide Viewing Angle (130°): The white diffused resin provides a very broad and uniform emission pattern, ideal for applications requiring wide-angle visibility rather than a focused beam.
• Dual-Chip Material Options: Offering both AlGaInP (R6) and InGaN (GH) in the same package footprint provides design flexibility for red/green indicator pairs or multi-color applications.
• Detailed Binning: The provision of multiple luminous intensity and wavelength bins allows designers to select parts for applications requiring tight brightness or color consistency.
• Robust Reflow Compatibility: Clearly defined Pb-free reflow profiles and moisture sensitivity handling information support modern, high-volume manufacturing processes.

10. Frequently Asked Questions (Based on Technical Parameters)

Q1: Can I drive this LED directly from a 5V or 3.3V logic supply? A: No. You must always use a series current-limiting resistor. For example, with a 5V supply and a green LED (V_F ~3.3V) at I_F=20mA: R = (5V - 3.3V) / 0.020A = 85 Ohms. Use the next standard value (e.g., 82 or 100 Ohms) and check the actual current and power dissipation.

Q2: Why is the ESD rating for the green LED (GH) lower than for the red (R6)? A: This is a fundamental material property. InGaN-based LEDs (blue, green, white) generally have lower ESD withstand voltages compared to AlGaInP-based LEDs (red, amber). This necessitates more careful handling for the green variant.

Q3: What does the "white diffused" resin color mean for the light output? A: The diffused resin scatters the light emitted from the chip, creating a wider, more uniform viewing angle (130°) and giving the un-powered LED a white appearance. It softens the light output, making it less point-like and more suitable for panel illumination.

Q4: How do I interpret the bin codes when ordering? A: Specify the required CAT (brightness) and HUE (color for green) bin codes based on your application's tolerance for brightness variation and color shift. For non-critical indicators, a wider bin may be acceptable and cost-effective. For backlighting arrays where uniformity is key, specifying a tight bin is crucial.

11. Design-in Case Study

Scenario: Designing a compact control panel with multi-status indicators. Requirement: Red for "Fault," Green for "Ready." Space is extremely limited. Indicators must be clearly visible from a wide angle. The assembly process uses automated SMD placement and reflow soldering. Solution Implementation:

1. Part Selection: Use 18-225A/R6 for red and 18-225A/GH for green. The identical 3.2x1.6mm footprint simplifies PCB layout.
2. Circuit Design: For a 3.3V system rail:
   • Red LED: R = (3.3V - 2.0V) / 0.010A = 130 Ohms. Use 130Ω or 120Ω resistor. Power in R: (1.3V^2)/130Ω ≈ 13mW.
   • Green LED: R = (3.3V - 3.3V) / 0.010A = 0 Ohms. This is problematic. A 3.3V supply is at the typical V_F of the green LED, leaving no voltage headroom for the resistor. Solution: a) Use a lower current (e.g., 5mA), b) Use a higher supply voltage for the LED circuit, or c) Use a constant current driver.
3. PCB Layout: Place LEDs near the edge of the panel. Use the recommended or slightly larger solder pads connected to a small copper pour for heat dissipation. Ensure polarity markings on the silkscreen match the cathode mark on the LED.
4. Manufacturing: Program the pick-and-place machine for the 3.2x1.6mm body size. Follow the specified reflow profile precisely. Store opened reels in dry cabinets if not used immediately.
5. Binning: For this panel with multiple identical indicators, specify a single brightness bin (e.g., CAT P for red, CAT R1 for green) to ensure uniform appearance across all units.

12. Technology Principle Introduction

LEDs are semiconductor diodes that emit light through electroluminescence. When a forward voltage is applied across the p-n junction, electrons and holes are injected into the active region where they recombine. The energy released during this recombination is emitted as photons (light). The color (wavelength) of the emitted light is determined by the bandgap energy of the semiconductor material used in the active region.

• R6 (AlGaInP): Aluminum Gallium Indium Phosphide is a material system used to produce high-efficiency LEDs in the red, orange, and amber spectrum. It has a direct bandgap suitable for efficient light emission.
• GH (InGaN): Indium Gallium Nitride is the material system for blue, green, and white LEDs. By varying the indium content, the bandgap can be tuned. Achieving high-efficiency green emission ("green gap") has been a historical challenge in this material system.

The light from the tiny semiconductor chip is encapsulated in an epoxy or silicone resin package. The "white diffused" resin contains scattering particles that randomize the direction of the photons, creating the wide, uniform emission pattern. The package also provides mechanical protection, electrical contacts, and aids in heat dissipation.

13. Industry Trends

The SMD LED market continues to evolve driven by demands for miniaturization, higher efficiency, and lower cost. Trends relevant to devices like the 18-225A include:

• Increased Efficiency: Ongoing improvements in epitaxial growth and chip design lead to higher luminous efficacy (more light output per electrical watt), allowing either brighter indicators or lower power consumption.
• Improved Color Consistency: Advances in manufacturing control and more sophisticated binning strategies enable tighter color and brightness tolerances, which is critical for applications like backlighting arrays and full-color displays.
• Expanded Color Gamut: Development of new phosphors and narrow-band emitters (like quantum dots) allows for LEDs with more saturated colors, expanding the achievable color space for displays.
• Integration: The trend towards integrating multiple LED chips (RGB, RGBW), control ICs, and even passive components into a single package module continues, simplifying end-product assembly.
• Reliability Focus: As LEDs penetrate automotive, industrial, and medical markets, there is increased emphasis on long-term reliability data, failure mode analysis, and qualification under harsh environmental conditions (high temperature, humidity, thermal cycling).

While newer, smaller package formats (e.g., 0201, 01005) exist, the 3.2x1.6mm footprint remains a popular and robust workhorse for general-purpose indicator and backlight applications, offering a good balance of size, brightness, ease of handling, and thermal performance.