SMD LED 25-21/GHC-YSU/2A Datasheet - Package 2.5x2.1mm - Voltage 3.5V - Brilliant Green - English Technical Document

1. Product Overview

The 25-21/GHC-YSU/2A is a surface-mount device (SMD) LED designed for modern electronic applications requiring compact size, high reliability, and efficient performance. This component belongs to a family of LEDs characterized by their miniature footprint and suitability for automated assembly processes.

1.1 Core Advantages and Product Positioning

The primary advantage of this LED is its significantly reduced size compared to traditional lead-frame type components. This miniaturization enables several key benefits for designers and manufacturers:

• Space Efficiency: Allows for smaller printed circuit board (PCB) designs, leading to more compact end products.
• High Packing Density: Enables a greater number of components to be placed within a given area, ideal for dense electronic assemblies.
• Reduced Storage and Logistics Footprint: The smaller component size and tape-and-reel packaging minimize storage space requirements.
• Lightweight Construction: Makes the LED ideal for portable and miniature applications where weight is a critical factor.
• Manufacturing Compatibility: The device is supplied in 8mm tape on 7-inch diameter reels, making it fully compatible with standard automatic pick-and-place equipment used in high-volume production.

1.2 Target Market and Applications

This LED is targeted at a broad range of commercial and industrial electronics markets. Its specifications make it suitable for both indicator and backlighting functions. Key application areas include:

• Automotive Interior: Backlighting for dashboard instruments, switches, and control panels.
• Telecommunications Equipment: Status indicators and keypad backlighting in devices such as telephones and fax machines.
• Consumer Electronics: Flat backlighting for liquid crystal displays (LCDs), switch illumination, and symbol lighting.
• General Purpose Indication: Any application requiring a reliable, bright green indicator light.

2. In-Depth Technical Parameter Analysis

This section provides a detailed breakdown of the electrical, optical, and thermal parameters that define the operational boundaries and performance of the LED.

2.1 Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. Operation under or at these limits is not guaranteed and should be avoided in reliable designs.

• Reverse Voltage (V_R): 5 V. Exceeding this voltage in the reverse direction can cause junction breakdown.
• Continuous Forward Current (I_F): 25 mA. The maximum DC current that can be applied continuously.
• Peak Forward Current (I_FP): 100 mA. This is permissible only under pulsed conditions with a duty cycle of 1/10 at 1 kHz. It is useful for multiplexing or brief overdrive scenarios.
• Power Dissipation (P_d): 95 mW. The maximum power the package can dissipate, calculated as V_F * I_F.
• Operating & Storage Temperature: -40°C to +85°C (operating), -40°C to +90°C (storage). This wide range ensures reliability in harsh environments.
• Electrostatic Discharge (ESD): Human Body Model (HBM) rating of 150V. This is a relatively basic level of ESD protection; proper handling procedures are essential.
• Soldering Temperature: Withstands reflow soldering at 260°C for 10 seconds or hand soldering at 350°C for 3 seconds per terminal.

2.2 Electro-Optical Characteristics

These parameters, measured at a standard junction temperature of 25°C and a forward current of 20mA, define the light output and electrical behavior of the LED.

• Luminous Intensity (I_v): Ranges from a minimum of 180 mcd to a maximum of 715 mcd, with a typical value implied by the binning system. The light output has a tolerance of ±11%.
• Viewing Angle (2θ_1/2): 60 degrees (typical). This is the full angle at which the luminous intensity drops to half of its peak value, defining the beam spread.
• Peak Wavelength (λ_p): 518 nm (typical). The wavelength at which the spectral power distribution is maximum.
• Dominant Wavelength (λ_d): Ranges from 520 nm to 535 nm. This is the single-wavelength perception of the LED's color by the human eye and is subject to a tight tolerance of ±1 nm. It is the primary parameter for color binning.
• Spectral Bandwidth (Δλ): 35 nm (typical). The width of the emitted spectrum at half its maximum power.
• Forward Voltage (V_F): 3.5 V (typical), with a maximum of 4.3 V at 20mA. This parameter is crucial for designing the current-limiting circuitry.
• Reverse Current (I_R): Maximum of 50 µA when a 5V reverse bias is applied.

3. Binning System Explanation

To ensure consistency in brightness and color for production runs, the LEDs are sorted into bins. This allows designers to select parts that meet specific application requirements.

3.1 Luminous Intensity Binning

LEDs are categorized into three bins based on their measured luminous intensity at I_F = 20mA:

• Bin S: 180 mcd (Min) to 285 mcd (Max)
• Bin T: 285 mcd (Min) to 450 mcd (Max)
• Bin U: 450 mcd (Min) to 715 mcd (Max)

The bin code (e.g., S, T, U) is indicated on the packaging label (CAT field).

3.2 Dominant Wavelength Binning

LEDs are also binned by their dominant wavelength to control color consistency. They are grouped and binned as follows:

• Group Y:
  • Bin X: 520 nm to 525 nm
  • Bin Y: 525 nm to 530 nm
  • Bin Z: 530 nm to 535 nm

The group and bin code for wavelength (e.g., YX, YY, YZ) is indicated on the packaging label (HUE field).

4. Mechanical and Packaging Information

4.1 Package Dimensions

The LED features a compact "chip" style SMD package. Key dimensions (in millimeters) include a body size of approximately 2.5mm in length and 2.1mm in width. Detailed mechanical drawings in the datasheet specify the exact pad layout, component height, and tolerances (typically ±0.1mm unless otherwise noted). Correct pad design is critical for solder joint reliability and proper alignment during reflow.

4.2 Packaging and Handling

The components are supplied in a moisture-sensitive device (MSD) package to prevent damage from ambient humidity during storage and transport.

• Carrier Tape: Components are loaded into 8mm wide carrier tape.
• Reel: The tape is wound onto a standard 7-inch diameter reel, with a typical loaded quantity of 2000 pieces per reel.
• Moisture Barrier Bag (MBB): The reel is sealed inside an aluminum-laminated moisture-proof bag along with a humidity indicator card and desiccant.

4.3 Label Information

The reel label contains critical information for traceability and correct application:

• CPN (Customer's Product Number)
• P/N (Manufacturer's Product Number: 25-21/GHC-YSU/2A)
• QTY (Packing Quantity)
• CAT (Luminous Intensity Bin Code: S, T, or U)
• HUE (Chromaticity/Dominant Wavelength Bin Code: e.g., YX)
• REF (Forward Voltage Rank, if applicable)
• LOT No (Manufacturing Lot Number for traceability)

5. Soldering and Assembly Guidelines

Adherence to these guidelines is essential for achieving reliable solder joints without damaging the LED.

5.1 Reflow Soldering Profile

The LED is compatible with infrared and vapor phase reflow processes. A recommended Pb-free reflow profile is provided:

• Pre-heating: Ramp from ambient to 150-200°C over 60-120 seconds.
• Soak/Preflow: Maintain between 150-200°C.
• Reflow: Rapid ramp up at a maximum rate of 3°C/sec to the peak temperature.
• Peak Temperature: Maximum of 260°C, held above 217°C for 60-150 seconds, and above 255°C for a maximum of 30 seconds. The time at 260°C must not exceed 10 seconds.
• Cooling: Cool down at a maximum rate of 6°C/sec.

Critical Note: Reflow soldering should not be performed more than two times on the same LED assembly.

5.2 Hand Soldering Instructions

If hand soldering is necessary, extreme care must be taken:

• Use a soldering iron with a tip temperature not exceeding 350°C.
• Apply heat to each terminal for a maximum of 3 seconds.
• Use an iron with a power rating of 25W or less.
• Allow an interval of at least 2 seconds between soldering each terminal to prevent heat buildup.
• Avoid putting mechanical stress on the LED during or after soldering.

5.3 Rework and Repair

Repair after soldering is strongly discouraged. If absolutely unavoidable, a specialized double-head soldering iron must be used to simultaneously heat both terminals, allowing for removal without excessive torsional stress on the solder joints. The potential for damage is high, and the characteristics of the LED post-rework cannot be guaranteed.

6. Storage and Moisture Sensitivity

As a moisture-sensitive device, strict storage protocols must be followed to prevent "popcorning" or internal delamination during reflow.

• Unopened Bag: Store at ≤30°C and ≤90% Relative Humidity.
• Floor Life: Once the moisture-proof bag is opened, the LEDs must be used within 168 hours (7 days).
• Rebagging: If not used within the floor life, unused parts must be re-sealed in a moisture-proof bag with fresh desiccant.
• Baking: If the humidity indicator shows excessive moisture exposure or the floor life is exceeded, the LEDs must be baked at 60 ±5°C for 24 hours before use to drive out moisture.

7. Application Design Considerations

7.1 Current Limiting is Mandatory

The datasheet explicitly warns: "Customer must apply resistors for protection, otherwise slight voltage shift will cause big current change (Burn out will happen)." LEDs exhibit a non-linear, exponential V-I relationship. A small increase in forward voltage beyond the typical value can lead to a very large, potentially destructive, increase in current. An external current-limiting resistor or a constant-current driver circuit is absolutely essential for reliable operation.

7.2 Thermal Management

While the package has a power dissipation rating of 95mW, effective thermal management is key to maintaining performance and longevity. Operating at or near the maximum forward current (25mA) will generate heat. Designers should ensure adequate PCB copper area (thermal relief pads) to help dissipate heat, especially in high ambient temperature environments or when multiple LEDs are clustered.

7.3 Application Restrictions

The datasheet includes a clear disclaimer regarding high-reliability applications. This product is intended for general commercial and industrial use. It is explicitly stated that it may not be suitable for applications requiring ultra-high reliability, such as:

• Military/Aerospace systems
• Automotive Safety/Security systems (e.g., airbag controls, brake lights)
• Medical Life-Support Equipment

For such applications, components with different qualifications and specifications must be sourced.

8. Environmental and Regulatory Compliance

The product is designed to meet several key international environmental standards:

• RoHS Compliant: The product is free of restricted hazardous substances as per the EU Restriction of Hazardous Substances directive.
• Pb-Free: The terminations and soldering process are lead-free.
• EU REACH Compliance: Adheres to the Registration, Evaluation, Authorisation and Restriction of Chemicals regulation.
• Halogen-Free: Compliant with halogen-free requirements, containing less than 900 ppm Bromine (Br), less than 900 ppm Chlorine (Cl), and a sum of Br+Cl less than 1500 ppm.

9. Technical Comparison and Differentiation

The 25-21/GHC-YSU/2A differentiates itself within the SMD LED market through several key attributes:

• Package Size: The 2.5x2.1mm footprint is a common but efficient size, balancing light output with board space. It is smaller than traditional 3mm and 5mm through-hole LEDs, enabling modern miniaturized designs.
• Material Technology: Utilizing an InGaN (Indium Gallium Nitride) chip, it produces a brilliant green color. InGaN technology is known for its efficiency and ability to produce shorter wavelength light (blue, green, white) compared to older technologies like AlGaAs (red).
• Optical Performance: With a luminous intensity up to 715 mcd and a 60-degree viewing angle, it offers a good balance between brightness and beam spread for both indicator and backlighting roles.
• Robustness: The inclusion of basic ESD protection (150V HBM) and a wide operating temperature range (-40°C to +85°C) provides a degree of robustness suitable for many non-critical environments.

10. Frequently Asked Questions (Based on Technical Parameters)

Q: What resistor value should I use to drive this LED at 20mA from a 5V supply?
A: Using Ohm's Law (R = (V_supply - V_F) / I_F) and the typical V_F of 3.5V: R = (5V - 3.5V) / 0.020A = 75 Ohms. A standard 75Ω or 82Ω resistor would be appropriate. Always calculate using the maximum V_F (4.3V) to ensure the current does not exceed limits under worst-case conditions.

Q: Can I use this LED for outdoor applications?
A: The operating temperature range of -40°C to +85°C suggests it can withstand a wide range of ambient conditions. However, the datasheet does not specify an Ingress Protection (IP) rating for the package itself. For outdoor use, the LED would likely need to be protected from direct exposure to water and contaminants by the end-product's enclosure or a conformal coating on the PCB.

Q: The label shows CAT="T" and HUE="YY". What does this mean?
A> This means the LEDs on that reel are from Luminous Intensity Bin T (285-450 mcd) and Dominant Wavelength Bin YY (525-530 nm within Group Y). This information is crucial for ensuring brightness and color consistency across your production run.

Q: Why is the storage and floor life so critical?
A> The plastic resin (encapsulant) of the SMD package can absorb moisture from the air. During the high-temperature reflow soldering process, this trapped moisture can vaporize rapidly, creating internal pressure. This can cause the package to crack ("popcorn") or delaminate internally, leading to immediate failure or reduced long-term reliability.