SMD LED 15-21/GHC-YR2U1/3T Datasheet - 2.0x1.25x0.8mm - 3.3V - 95mW - Brilliant Green - English Technical Document

1. Product Overview

The 15-21/GHC-YR2U1/3T is a surface-mount device (SMD) light-emitting diode (LED) designed for modern, compact electronic applications. This component represents a significant advancement over traditional lead-frame type LEDs, offering substantial benefits in terms of board space utilization and overall system miniaturization.

The core advantage of this LED lies in its miniature footprint. Its significantly smaller size compared to through-hole components enables designers to achieve higher packing densities on printed circuit boards (PCBs). This directly translates to reduced board size, minimized storage requirements for components, and ultimately, the creation of smaller and lighter end-user equipment. The inherent lightweight nature of the SMD package makes it an ideal choice for applications where weight and space are critical constraints.

This LED is a mono-color type, emitting a brilliant green light, and is constructed using environmentally friendly materials, being both Pb-free and compliant with RoHS, EU REACH, and halogen-free standards (Br <900 ppm, Cl <900 ppm, Br+Cl < 1500 ppm). It is supplied in industry-standard 8mm tape on 7-inch diameter reels, ensuring compatibility with high-speed automated pick-and-place assembly equipment. The device is also designed to withstand standard infrared and vapor phase reflow soldering processes.

2. Technical Parameter Deep Dive

2.1 Absolute Maximum Ratings

Understanding the absolute maximum ratings is crucial for ensuring long-term reliability and preventing catastrophic failure. These ratings specify the limits beyond which permanent damage may occur to the device.

• Forward Current (IF): 25 mA. This is the maximum continuous DC current that can be applied to the LED under normal operating conditions.
• Peak Forward Current (IFP): 50 mA. This rating applies under pulsed conditions with a duty cycle of 1/10 at 1 kHz. Exceeding the continuous current rating is only permissible under these specific pulsed conditions.
• Power Dissipation (Pd): 95 mW. This is the maximum amount of power the device can dissipate as heat at an ambient temperature (Ta) of 25°C. This rating is derated at higher ambient temperatures.
• Electrostatic Discharge (ESD): 150 V (Human Body Model). Proper ESD handling procedures must be followed during assembly and handling to prevent damage from static electricity.
• Operating Temperature (Topr): -40°C to +85°C. The device is guaranteed to function within this ambient temperature range.
• Storage Temperature (Tstg): -40°C to +90°C. The device can be stored within this temperature range when not powered.
• Soldering Temperature (Tsol): The device can withstand reflow soldering with a peak temperature of 260°C for up to 10 seconds. For hand soldering, the iron tip temperature must not exceed 350°C, and contact time should be limited to 3 seconds per terminal.

2.2 Electro-Optical Characteristics

The electro-optical characteristics define the light output and electrical behavior of the LED under specified test conditions (Ta=25°C, IF=20mA unless noted). These are the key parameters for design and performance verification.

• Luminous Intensity (Iv): Ranges from a minimum of 140.0 mcd to a maximum of 565.0 mcd, with a typical value dependent on the specific bin. The tolerance for luminous intensity is ±11%.
• Viewing Angle (2θ1/2): 130 degrees (typical). This wide viewing angle indicates a Lambertian or near-Lambertian emission pattern, suitable for applications requiring broad area illumination.
• Peak Wavelength (λp): 518 nm (typical). This is the wavelength at which the spectral power distribution reaches its maximum.
• Dominant Wavelength (λd): Ranges from 520 nm to 535 nm. This is the single wavelength perceived by the human eye that matches the color of the emitted light. Tolerance is ±1 nm.
• Spectral Bandwidth (Δλ): 35 nm (typical). This is the width of the emitted spectrum, measured at half the maximum intensity (Full Width at Half Maximum - FWHM).
• Forward Voltage (VF): Ranges from 2.7V (min) to 3.7V (max), with a typical value of 3.3V at 20mA. This parameter is crucial for designing the current-limiting circuitry.
• Reverse Current (IR): Maximum of 50 μA when a reverse voltage (VR) of 5V is applied. It is critical to note that this device is not designed for operation in reverse bias; this test condition is for characterization only.

3. Binning System Explanation

To ensure color and brightness consistency in production, LEDs are sorted into bins based on key parameters. The 15-21/GHC-YR2U1/3T uses a two-dimensional binning system.

3.1 Luminous Intensity Binning

The luminous intensity is sorted into six distinct bins (R2, S1, S2, T1, T2, U1), each defining a specific range of minimum and maximum intensity measured in millicandelas (mcd) at IF=20mA. For example, bin U1 represents the highest intensity range from 450.0 to 565.0 mcd, while bin R2 represents the lowest range from 140.0 to 180.0 mcd. The product code \"YR2U1\" indicates specific bins for dominant wavelength (Y) and luminous intensity (U1).

3.2 Dominant Wavelength Binning

The dominant wavelength, which defines the perceived color, is sorted into three bins (X, Y, Z). Bin X covers 520.0-525.0 nm, bin Y covers 525.0-530.0 nm, and bin Z covers 530.0-535.0 nm. This ensures that LEDs from the same wavelength bin will appear visually consistent in color.

4. Performance Curve Analysis

The datasheet provides several characteristic curves that illustrate the device's behavior under varying conditions. These are essential for advanced thermal and optical design.

• Forward Current vs. Forward Voltage (I-V Curve): This curve shows the exponential relationship between current and voltage. It is used to determine the operating point and to design appropriate current-limiting resistors or drivers.
• Relative Luminous Intensity vs. Forward Current: This graph demonstrates how light output increases with drive current. It typically shows a sub-linear relationship, where efficiency may decrease at very high currents.
• Relative Luminous Intensity vs. Ambient Temperature: This critical curve shows the derating of light output as the junction temperature increases. Luminous intensity typically decreases as temperature rises, which must be accounted for in designs operating at high ambient temperatures.
• Forward Current Derating Curve: This graph defines the maximum allowable continuous forward current as a function of ambient temperature. As temperature increases, the maximum current must be reduced to stay within the device's power dissipation limits.
• Spectrum Distribution: This plot shows the relative optical power as a function of wavelength, centered around the peak wavelength of 518 nm with a typical bandwidth of 35 nm.
• Radiation Diagram: This polar plot illustrates the spatial distribution of light intensity, confirming the 130-degree viewing angle.

5. Mechanical and Packaging Information

5.1 Package Dimension

The LED has a compact SMD footprint. Key dimensions include a body size of approximately 2.0mm in length and 1.25mm in width, with a height of 0.8mm. The datasheet provides a detailed dimensional drawing including pad layout, overall size, and the location of the cathode marking. Tolerances are typically ±0.1mm unless otherwise specified. The cathode is clearly marked for correct PCB orientation.

5.2 Packaging Specifications

The device is supplied in moisture-resistant packaging to prevent damage from ambient humidity during storage. The components are loaded into carrier tape with pockets sized for the 15-21 package. This carrier tape is wound onto a standard 7-inch diameter reel. Each reel contains 3000 pieces. The packaging includes a desiccant and is sealed within an aluminum moisture-proof bag. The bag label contains critical information such as the product number (P/N), quantity (QTY), luminous intensity rank (CAT), chromaticity/wavelength rank (HUE), forward voltage rank (REF), and lot number (LOT No).

6. Soldering and Assembly Guidelines

Proper handling and soldering are vital for reliability. Key precautions include:

• Current Limiting: An external current-limiting resistor is mandatory. The LED's exponential I-V characteristic means a small voltage change can cause a large current surge, leading to immediate failure.
• Moisture Sensitivity: The device is packaged in a moisture-barrier bag. Once opened, the LEDs must be used within 168 hours (7 days) if stored at conditions ≤30°C and ≤60% RH. Unused parts should be re-bagged with desiccant. If the exposure time is exceeded or the desiccant indicator has changed color, a bake-out at 60±5°C for 24 hours is required before reflow soldering.
• Reflow Soldering Profile: A lead-free (Pb-free) reflow profile is specified. Key parameters include a pre-heat stage between 150-200°C for 60-120 seconds, a time above liquidus (217°C) of 60-150 seconds, and a peak temperature not exceeding 260°C for a maximum of 10 seconds. The maximum heating rate is 6°C/sec, and the maximum cooling rate is 3°C/sec. Reflow should not be performed more than two times.
• Hand Soldering: If manual repair is necessary, use a soldering iron with a tip temperature below 350°C. Contact time per terminal must be less than 3 seconds, and a double-head soldering iron is recommended for removal to avoid mechanical stress. The iron power should be 25W or less.

7. Application Suggestions

7.1 Typical Application Scenarios

The brilliant green color and compact size make this LED suitable for a variety of applications:

• Backlighting: Ideal for backlighting symbols, switches, and indicators in automotive dashboards, consumer electronics, and industrial control panels.
• Telecommunication Equipment: Used as status indicators and keypad backlights in telephones, fax machines, and networking hardware.
• LCD Flat Backlighting: Can be used in arrays to provide edge-lighting or direct backlighting for small monochrome or color LCD displays.
• General Indication: Any application requiring a bright, reliable, and compact status indicator.

7.2 Design Considerations

• Thermal Management: While the power dissipation is low, maintaining a low junction temperature is key to maximizing luminous output and longevity. Ensure adequate PCB copper area or thermal vias if operating at high ambient temperatures or high drive currents.
• Current Drive Circuit: Always use a constant current source or a voltage source with a series current-limiting resistor. Calculate the resistor value based on the supply voltage (Vs), the LED's forward voltage (VF, use max value for safety), and the desired forward current (IF): R = (Vs - VF) / IF.
• Optical Design: The wide 130-degree viewing angle provides broad illumination. For focused light, external lenses or light guides may be required.

8. Technical Comparison and Differentiation

The primary differentiation of the 15-21 SMD LED lies in its combination of a very small form factor (2.0x1.25mm) with relatively high luminous intensity (up to 565 mcd for the U1 bin). Compared to larger SMD LEDs (e.g., 3528, 5050), it saves significant board space. Compared to even smaller chip-scale packages, it offers easier handling and soldering due to its defined package with solderable terminals. The use of InGaN technology for brilliant green provides higher efficiency and better color saturation compared to older technologies. Its compliance with stringent environmental standards (RoHS, REACH, Halogen-Free) makes it suitable for global markets with strict regulatory requirements.

9. Frequently Asked Questions (Based on Technical Parameters)

Q: What resistor value should I use with a 5V supply?
A: Using the maximum VF of 3.7V and a target IF of 20mA: R = (5V - 3.7V) / 0.020A = 65 Ohms. Use the next standard value higher, such as 68 Ohms, to ensure current does not exceed 20mA.

Q: Can I drive this LED with 30mA for higher brightness?
A: No. The Absolute Maximum Rating for continuous forward current (IF) is 25 mA. Exceeding this rating risks immediate or long-term damage to the device. For higher brightness, select an LED from a higher luminous intensity bin (e.g., T2 or U1).

Q: The bag has been open for 10 days. Can I still use the LEDs?
A: Not directly for reflow soldering. You must first perform a bake-out at 60±5°C for 24 hours to remove absorbed moisture and prevent \"popcorning\" damage during reflow.

Q: How do I identify the cathode?
A: The package has a distinct cathode mark, as shown in the dimension drawing. On the PCB footprint, the cathode pad is typically indicated in the silkscreen.

10. Practical Design and Usage Case

Case: Designing a Multi-Indicator Status Panel
A designer is creating a compact control panel with 12 status indicators. Space is extremely limited. By selecting the 15-21 LED, they can place indicators on a 0.1-inch (2.54mm) grid. They choose the U1 brightness bin for high visibility. They design the PCB with a common 5V rail. For each LED, they place a 68-ohm 0603 resistor in series. They create a thermal relief connection on the cathode pad to aid soldering but ensure a solid ground plane connection for heat dissipation. During assembly, they follow the moisture handling procedures and use the specified reflow profile. The result is a bright, reliable, and densely packed indicator panel that meets all size and performance requirements.

11. Technical Principle Introduction

This LED is based on InGaN (Indium Gallium Nitride) semiconductor technology. When a forward voltage is applied across the p-n junction, electrons and holes are injected into the active region. Their recombination releases energy in the form of photons (light). The specific composition of the InGaN alloy in the active layer determines the bandgap energy, which directly defines the wavelength (color) of the emitted light—in this case, brilliant green at ~518 nm. The water-clear resin encapsulant protects the semiconductor die and acts as a primary lens, helping to shape the 130-degree emission pattern. The SMD package provides mechanical protection, electrical connections, and a thermal path from the die to the PCB.

12. Technology Trends and Developments

The trend in SMD LEDs like the 15-21 continues towards higher efficiency (more lumens per watt), improved color consistency through tighter binning, and increased reliability. There is also a drive towards even smaller package sizes (e.g., chip-scale packages) while maintaining or improving optical performance. The widespread adoption of InGaN technology has enabled high-brightness green and blue LEDs, which were historically more difficult to produce than red LEDs. Future developments may include integrated drivers or control circuitry within the package, as well as advancements in materials to further improve efficiency at high temperatures and extend operational lifetime. The emphasis on environmental compliance and sustainable manufacturing processes is also a persistent and growing trend across the industry.