SMD LED 12-21/GHC-YR2S2/2C Specification - Brilliant Green - 3.5V - 20mA - English Technical Document

1. Product Overview

The 12-21/GHC-YR2S2/2C is a surface-mount device (SMD) 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, assembly efficiency, and overall system miniaturization. Its core advantage lies in its extremely small footprint, which directly contributes to higher packing density on printed circuit boards (PCBs), reduced storage requirements, and ultimately, the creation of smaller and lighter end-user equipment. The lightweight nature of the package makes it particularly suitable for applications where weight and space are critical constraints.

This LED is classified as a mono-color type, emitting a brilliant green light. It is constructed using an InGaN (Indium Gallium Nitride) chip material, which is encapsulated in a water-clear resin. This combination is responsible for its specific optical characteristics. The product is fully compliant with contemporary environmental and safety standards, being lead-free (Pb-free), compliant with the EU REACH regulation, and classified as Halogen-Free, with strict limits on Bromine (Br) and Chlorine (Cl) content.

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. Exceeding this voltage in reverse bias can damage the semiconductor junction.
• Continuous Forward Current (I_F): 25 mA. This is 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.
• Power Dissipation (P_d): 95 mW. This is the maximum power the package can dissipate without exceeding its thermal limits.
• Electrostatic Discharge (ESD) Human Body Model (HBM): 150 V. This indicates the device's sensitivity to static electricity; proper ESD handling procedures are mandatory.
• Operating Temperature (T_opr): -40°C to +85°C. The device is guaranteed to function within this ambient temperature range.
• Storage Temperature (T_stg): -40°C to +90°C.
• Soldering Temperature (T_sol): 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

These parameters define the light output and electrical behavior under normal operating conditions, typically at I_F = 20 mA and Ta = 25°C.

• Luminous Intensity (I_v): Ranges from a minimum of 140 mcd to a maximum of 285 mcd, with a typical tolerance of ±11%. This measures the perceived brightness of the light source.
• Viewing Angle (2θ_1/2): 120 degrees (typical). This wide viewing angle makes the LED suitable for applications requiring broad visibility.
• Peak Wavelength (λ_p): 518 nm (typical). This is the wavelength at which the optical emission is strongest.
• Dominant Wavelength (λ_d): Ranges from 520 nm to 535 nm, with a tolerance of ±1 nm. This wavelength correlates most closely with the perceived color (green).
• Spectral Bandwidth (Δλ): 35 nm (typical). This indicates the spread of wavelengths emitted around the peak.
• Forward Voltage (V_F): Typically 3.5 V, with a maximum of 4.3 V at 20 mA, and a tolerance of ±0.1 V. This is the voltage drop across the LED when operating.
• Reverse Current (I_R): Maximum 50 μA at V_R = 5 V. This is the small leakage current when the device is reverse-biased.

3. Binning System Explanation

To ensure consistency in brightness and color, the LEDs are sorted into bins based on measured performance.

3.1 Luminous Intensity Binning

LEDs are categorized into three bins (R2, S1, S2) based on their measured luminous intensity at I_F = 20 mA.

• Bin R2: 140 mcd (Min) to 180 mcd (Max)
• Bin S1: 180 mcd (Min) to 225 mcd (Max)
• Bin S2: 225 mcd (Min) to 285 mcd (Max)

3.2 Dominant Wavelength Binning

LEDs are also binned by their dominant wavelength to control the shade of green.

• Bin X: 520 nm (Min) to 525 nm (Max)
• Bin Y: 525 nm (Min) to 530 nm (Max)
• Bin Z: 530 nm (Min) to 535 nm (Max)

The specific bin codes (e.g., YR2S2 in the part number) indicate the combination of wavelength and intensity bins for a given unit, allowing designers to select LEDs with tightly matched characteristics for uniform appearance in multi-LED arrays.

4. Performance Curve Analysis

The datasheet references typical electro-optical characteristic curves. While the specific graphs are not reproduced in text, they typically include the following relationships which are critical for design:

• Forward Current vs. Forward Voltage (I-V Curve): This non-linear curve shows how voltage increases with current. Operating at the recommended 20mA ensures stable performance within the specified V_F range.
• Luminous Intensity vs. Forward Current: Shows how light output increases with current, up to the maximum rating. It highlights the importance of current regulation, not voltage regulation, for controlling brightness.
• Luminous Intensity vs. Ambient Temperature: Typically shows a decrease in light output as temperature increases. This is crucial for applications operating in high-temperature environments.
• Spectral Distribution: A plot of relative intensity versus wavelength, centered around the 518 nm peak with the 35 nm bandwidth, confirming the pure green color emission.

5. Mechanical and Package Information

5.1 Package Dimensions

The 12-21 SMD LED has a compact rectangular package. Key dimensions (in mm, with a general tolerance of ±0.1mm unless otherwise noted) include the overall length, width, and height. The package features two anode/cathode terminals on the bottom for surface mounting. The design includes clear polarity markings (typically a notch or a green dot on the cathode side) to ensure correct orientation during assembly. The exact dimensional drawing provides critical information for PCB pad layout design to ensure proper soldering and mechanical stability.

5.2 Packaging for Shipping and Storage

The LEDs are supplied in moisture-resistant packaging to prevent damage from ambient humidity, which is critical for MSL (Moisture Sensitivity Level) compliance. They are loaded into 8mm wide carrier tape, which is then wound onto a 7-inch diameter reel. Each reel contains 2000 pieces. The packaging includes a desiccant and is sealed within an aluminum moisture-proof bag. The bag label contains essential information for traceability and identification, including Product Number (P/N), quantity (QTY), and the specific bin codes for Luminous Intensity (CAT), Dominant Wavelength/Hue (HUE), and Forward Voltage (REF).

6. Soldering and Assembly Guidelines

6.1 Critical Precautions

• Current Limiting: An external current-limiting resistor is absolutely mandatory. The LED's forward voltage has a negative temperature coefficient and slight variations can cause large, damaging increases in current if driven directly from a voltage source.
• Storage and Handling: The bag should not be opened until ready for use. Before opening, store at ≤30°C and ≤90% RH. After opening, the "floor life" is 168 hours at ≤30°C and ≤60% RH. Unused parts must be resealed with desiccant. Exceeded storage requires baking at 60±5°C for 24 hours.
• Reflow Soldering: A lead-free temperature profile is specified. Key parameters include a pre-heat between 150-200°C for 60-120s, time above liquidus (217°C) for 60-150s, and a peak temperature not exceeding 260°C for a maximum of 10 seconds. Reflow should not be performed more than two times.
• Hand Soldering: If necessary, use a soldering iron with a tip temperature ≤350°C, capacity ≤25W, and limit contact time to 3 seconds per terminal. Allow a cooling interval of at least 2 seconds between terminals. Avoid stress on the package during heating.
• Repair: 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. The impact on LED characteristics must be verified beforehand.

7. Application Suggestions

7.1 Typical Application Scenarios

• Backlighting: Ideal for backlighting indicators on automotive dashboards, control panels, switches, and push-buttons due to its small size and bright output.
• Telecommunication Equipment: Used as status indicators and keypad backlights in telephones, fax machines, and networking hardware.
• LCD Panel Backlighting: Suitable for flat backlighting requirements behind small LCD displays, symbols, or legends.
• General Indicator Use: A versatile component for power-on indicators, status lights, and decorative lighting in a wide array of consumer and industrial electronics.

7.2 Design Considerations

• Drive Circuit: Always use a constant-current driver or a voltage source with a series resistor. Calculate the resistor value using R = (V_supply - V_F) / I_F, where V_F should be taken as the maximum value (4.3V) for a robust design.
• Thermal Management: While low-power, ensure the PCB layout provides adequate thermal relief, especially if multiple LEDs are clustered or operated in high ambient temperatures, as heat reduces light output and lifespan.
• Optical Design: The 120-degree viewing angle provides wide visibility. For focused beams, external lenses or light guides may be required.
• ESD Protection: Implement ESD protection on input lines if the LED is in a user-accessible location, as the 150V HBM rating indicates moderate sensitivity.

8. Technical Comparison and Differentiation

Compared to older through-hole LED packages (e.g., 3mm or 5mm LEDs), the 12-21 SMD format offers decisive advantages:

• Size and Density: Drastically smaller, enabling modern miniaturized designs impossible with through-hole parts.
• Assembly Cost and Speed: Fully compatible with high-speed automated pick-and-place and reflow soldering equipment, reducing assembly time and cost versus manual insertion and soldering.
• Performance Consistency: The SMD manufacturing and binning process typically yields more consistent optical and electrical parameters from batch to batch.
• Reliability: The solid construction and surface-mount attachment can offer better resistance to vibration and mechanical shock.

Within the SMD LED category, the specific combination of brilliant green color (via InGaN), wide viewing angle, and the detailed binning system for both intensity and wavelength makes this part suitable for applications requiring color consistency and uniform brightness across multiple units.

9. Frequently Asked Questions (Based on Technical Parameters)

Q: Why is a series resistor necessary if the forward voltage is specified?
A: The forward voltage is a characteristic of the diode, not a stable operating point. It varies slightly from unit to unit (tolerance) and decreases with increasing temperature. Connecting it directly to a voltage source even slightly above its V_F can cause current to rise uncontrollably (thermal runaway), leading to immediate failure. The resistor provides a linear, stable current limit.

Q: What do the bin codes (YR2S2) mean, and why are they important?
A: The codes specify the exact performance subgroup of the LED. 'Y' indicates the dominant wavelength bin (525-530nm), 'R2' and 'S2' are luminous intensity bins. For applications using multiple LEDs (e.g., an array or backlight), ordering parts within the same bin code ensures visually uniform color and brightness, which is critical for product quality.

Q: Can I drive this LED with a 5V supply?
A: Yes, but you must use a current-limiting resistor. For example, targeting I_F=20mA with a worst-case V_F of 4.3V: R = (5V - 4.3V) / 0.020A = 35 ohms. The nearest standard value (33 or 39 ohms) would be chosen, and the resistor's power rating (P = I²R) should be calculated.

Q: How critical are the storage and baking instructions?
A: Very critical. SMD packages can absorb moisture from the air. During reflow soldering, this trapped moisture can vaporize rapidly, causing internal delamination or "popcorning" that cracks the package and destroys the LED. Following the storage and baking procedures prevents this failure mode.

10. Application Restriction Disclaimer

This product is designed for general-purpose indicator and backlighting applications in commercial and industrial electronics. It is explicitly not qualified or recommended for use in high-reliability or safety-critical systems without prior consultation and qualification. Such systems include, but are not limited to:

• Military, aerospace, or aviation equipment.
• Automotive safety systems (e.g., brake lights, airbag indicators).
• Medical life-support or diagnostic equipment.

For these applications, different products with extended temperature ranges, higher reliability screening, and different qualification standards are required. The performance is guaranteed only as an individual component under the conditions specified in this document. Using the product outside these specifications voids any guarantee of performance or reliability.