SMD LED 27-21/GHC-YR1S2M/3C Datasheet - 2.0x1.25x0.8mm - 3.95V Max - 95mW - Brilliant Green - English Technical Document

1. Product Overview

The 27-21 SMD LED is a compact, surface-mount device designed for high-density electronic assemblies. Its primary advantage lies in its significantly reduced footprint compared to traditional lead-frame type LEDs, enabling smaller printed circuit board (PCB) designs, higher component packing density, and ultimately more compact end-user equipment. The device is lightweight, making it particularly suitable for miniature and space-constrained applications.

The core technology utilizes an InGaN (Indium Gallium Nitride) semiconductor chip encapsulated in a water-clear resin, which emits a brilliant green light. It is a mono-color type LED, supplied in a format compatible with standard automated pick-and-place assembly equipment. The product is compliant with major environmental and safety directives, being Pb-free, RoHS compliant, EU REACH compliant, and halogen-free (with Bromine <900 ppm, Chlorine <900 ppm, and Br+Cl < 1500 ppm).

1.1 Key Features and Advantages

• Miniaturization: Enables smaller board designs and higher packing density.
• Automation Friendly: Packaged in 8mm tape on 7-inch diameter reels for compatibility with automatic placement systems.
• Robust Process Compatibility: Suitable for both infrared and vapor phase reflow soldering processes.
• Environmental Compliance: Adheres to Pb-free, RoHS, REACH, and halogen-free standards.

2. Technical Parameter Deep Dive

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. Operation at or beyond these limits is not guaranteed.

• Reverse Voltage (V_R): 5 V - The maximum voltage that can be applied in the reverse direction.
• Forward Current (I_F): 25 mA - The maximum continuous DC forward current.
• Peak Forward Current (I_FP): 100 mA - The maximum pulsed forward current, permissible at a duty cycle of 1/10 and a frequency of 1 kHz.
• Power Dissipation (P_d): 95 mW - The maximum power the device can dissipate at an ambient temperature (T_a) of 25°C.
• Electrostatic Discharge (ESD) Human Body Model (HBM): 150 V - Indicates a moderate sensitivity to ESD; proper handling procedures are required.
• Operating Temperature (T_opr): -40°C to +85°C - The ambient temperature range for reliable operation.
• Storage Temperature (T_stg): -40°C to +90°C.
• Soldering Temperature (T_sol): Reflow: 260°C peak for 10 seconds max. Hand soldering: 350°C for 3 seconds max per terminal.

2.2 Electro-Optical Characteristics

These parameters are measured at a standard test condition of T_a=25°C and I_F=20 mA, unless otherwise specified. They define the optical and electrical performance of the LED.

• Luminous Intensity (I_v): 112 to 285 mcd (millicandela). The typical value is not specified, indicating performance is managed through the binning system described later.
• Viewing Angle (2θ_1/2): 130 degrees (typical). This wide viewing angle makes it suitable for indicator and backlighting applications where visibility from various angles is important.
• Peak Wavelength (λ_p): 518 nm (typical). The wavelength at which the spectral emission is strongest.
• Dominant Wavelength (λ_d): 520 to 535 nm. This is the single-wavelength perception of the LED's color by the human eye.
• Spectral Bandwidth (Δλ): 35 nm (typical). The width of the emitted spectrum at half its maximum intensity (FWHM).
• Forward Voltage (V_F): 2.75 to 3.95 V at I_F=20 mA. This range is critical for circuit design, particularly for current-limiting resistor calculation.
• Reverse Current (I_R): 50 μA (max) at V_R=5V.

Important Notes: The datasheet specifies tolerances for key parameters: Luminous Intensity (±11%), Dominant Wavelength (±1 nm), and Forward Voltage (±0.1 V). It also explicitly warns that the reverse voltage condition is for test purposes only, and the LED should not be operated in reverse bias.

3. Binning System Explanation

To ensure consistent color and brightness in production, LEDs are sorted into performance bins. This device uses a three-dimensional binning system.

3.1 Luminous Intensity Binning

Bins are defined by codes R1, R2, S1, and S2, with minimum and maximum luminous intensity values measured at I_F=20 mA.

• R1: 112 - 140 mcd
• R2: 140 - 180 mcd
• S1: 180 - 225 mcd
• S2: 225 - 285 mcd

3.2 Dominant Wavelength Binning

Bins are defined by codes X, Y, and Z, controlling the precise shade of green.

• X: 520 - 525 nm
• Y: 525 - 530 nm
• Z: 530 - 535 nm

3.3 Forward Voltage Binning

Bins are defined by codes 5, 6, 7, and 8, which is crucial for designing uniform current drive circuits, especially when multiple LEDs are connected in parallel.

• 5: 2.75 - 3.05 V
• 6: 3.05 - 3.35 V
• 7: 3.35 - 3.65 V
• 8: 3.65 - 3.95 V

4. Performance Curve Analysis

The datasheet references typical electro-optical characteristic curves, which are essential for understanding device behavior under non-standard conditions. While the specific graphs are not detailed in the provided text, they typically include:

• Relative Luminous Intensity vs. Ambient Temperature: Shows how light output decreases as the junction temperature rises. This is critical for thermal management in high-power or high-ambient-temperature applications.
• Relative Luminous Intensity vs. Forward Current: Illustrates the non-linear relationship between drive current and light output. Operating above the recommended current leads to diminished efficiency and accelerated degradation.
• Forward Voltage vs. Forward Current (I-V Curve): Demonstrates the exponential relationship, highlighting the need for current-limiting circuitry. A small increase in voltage can cause a large, potentially destructive, increase in current.
• Spectral Distribution: A graph of relative intensity vs. wavelength, showing the peak at ~518 nm and the ~35 nm bandwidth, confirming the brilliant green color point.

5. Mechanical and Package Information

5.1 Package Dimensions

The 27-21 SMD LED has a compact rectangular package. Key dimensions (in mm, with a general tolerance of ±0.1mm unless specified) include the overall length, width, and height, as well as the pad spacing and size. These dimensions are critical for PCB land pattern design to ensure proper soldering and alignment. The polarity is indicated by a marking on the package, which must be aligned with the corresponding marking on the PCB footprint.

5.2 Polarity Identification

Correct polarity is essential for device operation. The datasheet's package drawing will indicate the cathode (negative) terminal, typically with a visual marker such as a notch, dot, or beveled edge on the package. The PCB footprint design must incorporate this marker to prevent assembly errors.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Profile

The device is compatible with Pb-free reflow processes. The recommended temperature profile is crucial to prevent thermal shock and damage:

• Pre-heating: 150–200°C for 60–120 seconds.
• Time Above Liquidus (TAL): 60–150 seconds above 217°C.
• Peak Temperature: 260°C maximum, held for no more than 10 seconds.
• Ramp-up Rate: Maximum 6°C per second.
• Time Above 255°C: Maximum 30 seconds.
• Cooling Rate: Maximum 3°C per second.

Critical Restriction: Reflow soldering should not be performed more than two times on the same device.

6.2 Hand Soldering

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

• Use a soldering iron with a tip temperature less than 350°C.
• Limit contact time to 3 seconds or less per terminal.
• Use an iron with a power rating of 25W or less.
• Allow a minimum interval of 2 seconds between soldering each terminal to allow cooling.

6.3 Storage and Moisture Sensitivity

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

• Before Opening: Store at ≤30°C and ≤60% Relative Humidity.
• Floor Life: After opening the moisture-proof bag, components must be used within 168 hours (7 days).
• Rebaking: If the floor life is exceeded or the desiccant indicator changes color, a bake-out at 60 ±5°C for 24 hours is required before reflow soldering.

6.4 Repair and Rework

Repair after soldering is strongly discouraged. If unavoidable, a specialized double-head soldering iron must be used to simultaneously heat both terminals, preventing mechanical stress on the solder joints. The potential for damaging the LED during repair is high and should be evaluated beforehand.

7. Packaging and Ordering Information

7.1 Packaging Specifications

The device is supplied in a tape-and-reel format for automated assembly.

• Carrier Tape Width: 8 mm.
• Reel Diameter: 7 inches.
• Quantity per Reel: 3000 pieces.
• Moisture-Sensitive Level (MSL): Implied by the 7-day floor life and baking requirements, typically corresponding to MSL 3.

7.2 Label Explanation

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

• P/N: Product Number (e.g., 27-21/GHC-YR1S2M/3C).
• CAT: Luminous Intensity Rank (e.g., S2).
• HUE: Chromaticity Coordinates & Dominant Wavelength Rank (e.g., Y).
• REF: Forward Voltage Rank (e.g., 6).
• LOT No: Manufacturing Lot Number for traceability.

8. Application Suggestions and Design Considerations

8.1 Typical Application Scenarios

• Backlighting: Ideal for dashboard indicators, switch illumination, and flat backlighting for LCDs and symbols due to its wide viewing angle and consistent color.
• Telecommunication Equipment: Status indicators and keypad backlighting in devices like telephones and fax machines.
• General Purpose Indication: Any application requiring a compact, reliable, bright green indicator.

8.2 Critical Design Considerations

1. Current Limiting is Mandatory: LEDs are current-driven devices. An external current-limiting resistor must always be used in series with the LED. The value is calculated using Ohm's Law: R = (V_supply - V_F) / I_F. Use the maximum V_F from the bin or datasheet to ensure the current does not exceed 25 mA under worst-case conditions.
2. Thermal Management: While power dissipation is low, maintaining a low junction temperature is key to long-term reliability and stable light output. Ensure adequate PCB copper area or thermal vias if operating at high ambient temperatures or near maximum current.
3. ESD Protection: Implement standard ESD precautions during handling and assembly. Consider adding transient voltage suppression (TVS) diodes or resistors on sensitive lines if the application environment is prone to static discharge.
4. Binning for Consistency: For applications requiring uniform appearance (e.g., multi-LED arrays), specify tight bins for luminous intensity (CAT) and dominant wavelength (HUE). Using LEDs from the same manufacturing lot (LOT No.) further enhances consistency.

9. Technical Comparison and Differentiation

The 27-21 SMD LED differentiates itself primarily through its balance of size, performance, and reliability features.

• vs. Larger Lead-Frame LEDs: Offers a drastic reduction in footprint and weight, enabling modern miniaturized designs. The SMD format allows for faster, more reliable automated assembly.
• vs. Other SMD Greens: The specific combination of a 130-degree viewing angle, a brilliant green color from the InGaN chip, and comprehensive environmental compliance (Halogen Free, REACH) makes it suitable for a broad range of consumer and industrial applications where these factors are prioritized.
• Integrated Compliance: The pre-compliance with major global regulations (RoHS, REACH, Halogen-Free) reduces qualification overhead for integrators, providing a significant advantage in regulated markets.

10. Frequently Asked Questions (Based on Technical Parameters)

Q1: Why is a current-limiting resistor absolutely necessary?
A1: The I-V characteristic of an LED is exponential. A small increase in forward voltage beyond the typical value causes a very large increase in current, which can instantly exceed the Absolute Maximum Rating of 25 mA and destroy the device. The resistor provides a linear, predictable voltage drop to stabilize the current.

Q2: Can I drive this LED with a 3.3V supply without a resistor?
A2: No. Even if 3.3V is within the V_F range (2.75-3.95V), the actual V_F of a specific LED is not known without binning. A 3.3V supply could apply 3.3V directly to an LED with a V_F of 3.0V, causing excessive current. Always use a series resistor.

Q3: What happens if I exceed the 7-day floor life after opening the bag?
A3: The plastic package absorbs moisture. During reflow soldering, this moisture can rapidly expand, causing internal delamination or \"popcorning,\" which cracks the package and leads to failure. Baking at 60°C for 24 hours removes this absorbed moisture.

Q4: Why is reflow limited to two cycles?
A4: Each reflow cycle subjects the device to significant thermal stress. Multiple cycles can degrade the internal wire bonds, weaken solder joints, or damage the semiconductor chip itself, reducing reliability.

11. Practical Application Case Study

Scenario: Designing a multi-indicator status panel for a consumer electronics device.

1. Requirement: 10 uniform brilliant green LEDs for \"power on\" and \"mode active\" indicators.
2. Design Steps:
   • Circuit Design: A 5V supply is available. Using the maximum V_F of 3.95V and a target I_F of 20 mA, calculate R = (5V - 3.95V) / 0.02A = 52.5Ω. Select the nearest standard value (e.g., 56Ω). Re-calculate actual current: I_F = (5V - 3.2V_typ) / 56Ω ≈ 32 mA (too high). Re-iterate using a more realistic typical V_F of 3.2V: R = (5V - 3.2V) / 0.02A = 90Ω. This gives a safe current between 17.8 mA (at V_F=3.95V) and 20 mA (at V_F=3.2V). A 91Ω or 100Ω resistor is a good choice.
   • PCB Layout: Place LEDs with correct polarity alignment. Provide sufficient spacing for the 130-degree viewing cone if indicators are viewed from an angle.
   • Procurement: Specify tight bins to the distributor: e.g., CAT=S2 (225-285 mcd) and HUE=Y (525-530 nm) to ensure brightness and color consistency across all 10 indicators. Requesting parts from the same LOT No. is advisable.
   • Assembly: Follow the reflow profile precisely. Use the LEDs within 7 days of opening the sealed bag.

12. Operating Principle Introduction

Light Emitting Diodes (LEDs) are semiconductor devices that convert electrical energy directly into light through a process called electroluminescence. The core of the 27-21 LED is a chip made from InGaN (Indium Gallium Nitride) semiconductor materials. When a forward voltage is applied across the P-N junction of this semiconductor, electrons from the N-type material recombine with holes from the P-type material in the active region. This recombination releases energy in the form of photons (light particles). The specific wavelength (color) of the emitted light is determined by the bandgap energy of the semiconductor material. InGaN has a bandgap that corresponds to light in the blue-to-green spectrum. In this device, the composition is tuned to produce brilliant green light with a peak wavelength around 518 nm. The water-clear epoxy resin encapsulant protects the chip and also acts as a lens, shaping the light output into the specified 130-degree viewing angle.

13. Technology Trends and Context

The 27-21 LED represents a mature and widely adopted technology within the broader evolution of solid-state lighting. Key trends influencing this product segment include:

• Continued Miniaturization: The drive for smaller, thinner, and more feature-packed electronic devices pushes the development of ever-smaller LED packages (e.g., 0201, 01005 sizes) while maintaining or improving optical performance.
• Enhanced Efficiency and Luminance: Ongoing improvements in epitaxial growth and chip design lead to higher luminous efficacy (more light output per unit of electrical input), allowing for lower power consumption or higher brightness from the same package size.
• Color Consistency and Advanced Binning: Demands from display and automotive applications are driving tighter binning tolerances and the use of more sophisticated multi-parameter binning (e.g., combining flux, wavelength, and forward voltage into a single code) to achieve perfect uniformity in large arrays.
• Integration of Functionality: A trend towards integrating control circuitry (like constant current drivers) or multiple color chips (RGB) into a single package to simplify system design and reduce PCB real estate.
• Reliability and Harsh Environment Suitability: Development of LEDs with improved performance at high temperatures and under high humidity, expanding their use into automotive, industrial, and outdoor applications. The environmental compliance (Halogen-Free, REACH) highlighted in this datasheet is a direct response to global regulatory trends.

While the 27-21 is a standard component, its design reflects these industry demands for reliability, compliance, and performance in a compact, automatable format.