SMD LED 19-21/G PC-FL1M2B/3T Datasheet - Pure Green - 2.0x1.25x0.8mm - 2.35V Max - 60mW - English Technical Document

1. Product Overview

The 19-21/G PC-FL1M2B/3T is a surface-mount device (SMD) light-emitting diode (LED) designed for modern electronic applications requiring compact, efficient, and reliable indicator or backlighting solutions. This component represents a significant advancement over traditional lead-frame type LEDs, enabling substantial reductions in board space, increased packing density, and ultimately contributing to the miniaturization of end-user equipment. Its lightweight construction further enhances its suitability for applications where size and weight are critical constraints.

1.1 Core Features and Advantages

The primary advantages of this SMD LED stem from its package design and material compliance:

• Compact Packaging: Supplied on 8mm tape wound on a 7-inch diameter reel, making it fully compatible with high-speed automatic pick-and-place assembly equipment, thereby streamlining the manufacturing process.
• Robust Process Compatibility: Designed to withstand standard infrared (IR) and vapor phase reflow soldering processes, ensuring reliable attachment to printed circuit boards (PCBs).
• Environmental and Regulatory Compliance: The device is manufactured as a Pb-free (lead-free) component. It complies with the EU's RoHS (Restriction of Hazardous Substances) directive, REACH regulations, and meets halogen-free standards (Bromine <900 ppm, Chlorine <900 ppm, Br+Cl < 1500 ppm).
• Mono-Color Type: Emits a single, pure green color, providing consistent chromaticity for indicator purposes.

1.2 Target Applications

This LED is engineered for a diverse range of applications, including:

• Automotive Interior: Backlighting for instrument clusters, dashboard indicators, and switch panels.
• Telecommunications: Status indicators and keypad backlighting in telephones, fax machines, and other communication devices.
• Consumer Electronics: Flat backlighting for liquid crystal displays (LCDs), switch illumination, and symbolic indicators.
• General Purpose Indication: Any application requiring a small, bright, and reliable green light source.

2. Technical Specifications: In-Depth Analysis

The performance and reliability of the LED are defined by its absolute maximum ratings and electro-optical characteristics. Operating the device beyond these specified limits may cause permanent damage or degrade its performance.

2.1 Absolute Maximum Ratings

These ratings define the stress limits that should not be exceeded, even momentarily, under any operating condition. All values are specified at an ambient temperature (Ta) of 25°C.

• Reverse Voltage (VR): 5 V. Applying a reverse voltage greater than this can cause immediate junction breakdown.
• Continuous Forward Current (IF): 25 mA. The maximum DC current that can be continuously passed through the LED.
• Peak Forward Current (IFP): 60 mA. This is the maximum pulsed forward current, permissible only under a duty cycle of 1/10 at 1 kHz. It is not for continuous operation.
• Power Dissipation (Pd): 60 mW. The maximum amount of power the package can dissipate as heat, calculated as Forward Voltage (VF) × Forward Current (IF).
• Electrostatic Discharge (ESD) Human Body Model (HBM): 2000 V. This rating indicates the LED's sensitivity to static electricity. Proper ESD handling procedures are mandatory during assembly and handling.
• Operating Temperature (Topr): -40°C to +85°C. The ambient temperature range over which the LED is guaranteed to function.
• Storage Temperature (Tstg): -40°C to +90°C. The temperature range for storing the device when not powered.
• Soldering Temperature (Tsol):
  • Reflow Soldering: Peak temperature of 260°C for a maximum of 10 seconds.
  • Hand Soldering: Iron tip temperature not exceeding 350°C for a maximum of 3 seconds per terminal.

2.2 Electro-Optical Characteristics

These parameters define the light output and electrical behavior of the LED under normal operating conditions (Ta=25°C, IF=20mA unless otherwise stated). The "Typ." column represents typical or average values, while "Min." and "Max." define the guaranteed limits.

• Luminous Intensity (Iv): 11.5 mcd (Min) to 28.5 mcd (Max). This is the perceived brightness of the LED as measured in millicandelas. The actual value for a specific unit depends on its bin code (see Section 3).
• Viewing Angle (2θ1/2): 100 degrees (Typical). This is the full angle at which the luminous intensity is half of the intensity at 0 degrees (on-axis). A 100-degree angle provides a wide viewing cone.
• Peak Wavelength (λp): 561 nm (Typical). The wavelength at which the spectral power distribution of the emitted light is at its maximum.
• Dominant Wavelength (λd): 557.5 nm (Min) to 565.5 nm (Max). This is the single wavelength perceived by the human eye that best matches the color of the LED's light. It is the key parameter for color specification.
• Spectral Radiation Bandwidth (Δλ): 20 nm (Typical). The width of the emitted spectrum at half of the peak intensity (Full Width at Half Maximum - FWHM). A narrower bandwidth indicates a more spectrally pure color.
• Forward Voltage (VF): 1.75 V (Min) to 2.35 V (Max) at IF=20mA. The voltage drop across the LED when it is conducting current. This parameter is crucial for designing the current-limiting circuit.
• Reverse Current (IR): 10 μA (Max) at VR=5V. A small leakage current that flows when the LED is reverse-biased. The datasheet explicitly notes that the device is not designed for reverse operation; this test condition is for characterization only.

Important Notes on Tolerances: The datasheet specifies manufacturing tolerances for key parameters: Luminous Intensity (±11%), Dominant Wavelength (±1nm), and Forward Voltage (±0.1V). These tolerances apply to the values within each bin (see next section).

3. Binning System Explanation

To ensure consistency in mass production, LEDs are sorted into "bins" based on measured performance. This allows designers to select components with tightly controlled characteristics for their specific application needs.

3.1 Luminous Intensity Binning

LEDs are categorized into four intensity bins (L1, L2, M1, M2) based on their measured Iv at 20mA. This allows selection for applications requiring specific brightness levels.

• Bin L1: 11.5 – 14.5 mcd
• Bin L2: 14.5 – 18.0 mcd
• Bin M1: 18.0 – 22.5 mcd
• Bin M2: 22.5 – 28.5 mcd

3.2 Dominant Wavelength Binning

The color (hue) of the green light is controlled by sorting into four wavelength bins (C10 to C13). This is critical for applications where color consistency across multiple indicators is important.

• Bin C10: 557.5 – 559.5 nm
• Bin C11: 559.5 – 561.5 nm
• Bin C12: 561.5 – 563.5 nm
• Bin C13: 563.5 – 565.5 nm

3.3 Forward Voltage Binning

LEDs are also binned by their forward voltage drop at 20mA. This helps in designing power supplies and current-limiting circuits, especially when driving multiple LEDs in series.

• Bin 0: 1.75 – 1.95 V
• Bin 1: 1.95 – 2.15 V
• Bin 2: 2.15 – 2.35 V

The combination of these three bin codes (e.g., M2, C11, 1) uniquely defines the performance characteristics of a specific batch of LEDs.

4. Performance Curve Analysis

The datasheet provides several characteristic curves that illustrate the LED's behavior under varying conditions. Understanding these curves is essential for robust circuit design.

4.1 Forward Current vs. Forward Voltage (I-V Curve)

This curve shows the exponential relationship between the current flowing through the LED and the voltage across it. The forward voltage (VF) increases with current. The curve is crucial for selecting an appropriate current-limiting resistor or designing a constant-current driver. The typical VF at 20mA is around 2.0V, but it can vary between 1.75V and 2.35V as per the binning.

4.2 Relative Luminous Intensity vs. Forward Current

This graph demonstrates how light output increases with drive current. It is typically a sub-linear relationship; doubling the current does not double the light output. Operating at or below the recommended 20mA ensures optimal efficiency and longevity.

4.3 Relative Luminous Intensity vs. Ambient Temperature

LED light output is temperature-dependent. This curve shows that luminous intensity decreases as the ambient temperature (Ta) rises. For example, at the maximum operating temperature of +85°C, the light output may be significantly lower than at 25°C. This must be factored into designs that operate in high-temperature environments.

4.4 Forward Current Derating Curve

This is one of the most critical curves for reliability. It shows the maximum allowable continuous forward current as a function of ambient temperature. As temperature increases, the maximum safe current decreases to prevent overheating and accelerated degradation. At 85°C, the maximum allowable current is less than the 25mA rated at 25°C.

4.5 Spectrum Distribution

The spectral graph plots the relative intensity of light emitted across different wavelengths. For this Pure Green AlGaInP LED, it shows a single, dominant peak centered around 561 nm with a typical FWHM of 20 nm, confirming its monochromatic green output.

4.6 Radiation Diagram (Spatial Distribution)

This polar plot illustrates how light is emitted spatially from the LED. The 100-degree viewing angle is confirmed here, showing the angle at which intensity falls to 50% of the on-axis value. The pattern appears roughly Lambertian (cosine distribution), which is common for SMD LEDs with a diffused lens.

5. Mechanical and Package Information

5.1 Package Dimensions and Outline

The 19-21 SMD LED has a very compact footprint. Key dimensions (in mm, tolerance ±0.1mm unless noted) include a body size of approximately 2.0mm in length and 1.25mm in width, with a typical height of 0.8mm. The detailed drawing specifies pad spacing (1.4mm typical), land pattern recommendations, and overall package contours to guide PCB layout design.

5.2 Polarity Identification

Correct orientation is vital. The cathode (negative terminal) is clearly marked. On the package top, a distinctive cathode mark (typically a green dot, a notch, or a beveled corner) is present. The bottom-side metallization may also differ between anode and cathode pads. Always refer to the datasheet diagram during PCB design and assembly.

6. Soldering and Assembly Guidelines

Adherence to these guidelines is critical for ensuring solder joint reliability and preventing damage to the LED.

6.1 Reflow Soldering Profile (Pb-Free)

The recommended temperature profile for lead-free reflow soldering is provided:

• Pre-heating: Ramp from ambient to 150-200°C over 60-120 seconds to evenly heat the board and activate flux.
• Soak/Reflow: Time above liquidus (217°C) should be 60-150 seconds. The peak temperature must not exceed 260°C, and the time above 255°C must be limited to 30 seconds maximum.
• Cooling: Maximum cooling rate should be 6°C/second.

A maximum of two reflow cycles is permitted.

6.2 Hand Soldering Precautions

If hand soldering is necessary, extreme care is required:

• Use a soldering iron with a tip temperature ≤ 350°C.
• Limit contact time to ≤ 3 seconds per terminal.
• Use an iron with a power rating ≤ 25W.
• Allow a cooling interval of at least 2 seconds between soldering each terminal.
• Avoid applying mechanical stress to the LED body during or after soldering.

6.3 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 safe removal. The potential for thermal damage during rework is high, and the characteristics of the LED should be verified post-repair.

7. Storage and Moisture Sensitivity

This LED is packaged in a moisture-resistant barrier bag with desiccant to prevent absorption of atmospheric moisture, which can cause "popcorning" (package cracking) during reflow.

• Before Use: Do not open the moisture-proof bag until ready for assembly.
• After Opening: Use the LEDs within 168 hours (7 days) of opening. Store opened packages at ≤ 30°C and ≤ 60% Relative Humidity.
• Rebaking: If the storage time is exceeded or the desiccant indicator shows saturation, a bake at 60 ±5°C for 24 hours is required before reflow.

8. Packaging and Ordering Information

8.1 Tape and Reel Specifications

The LEDs are supplied in embossed carrier tape with a width of 8mm. Each reel has a 7-inch diameter and contains 3000 pieces. Detailed drawings for the carrier tape pocket dimensions and reel hub/flange dimensions are provided to ensure compatibility with automated assembly equipment.

8.2 Label Information

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

• P/N: Product Number (e.g., 19-21/G PC-FL1M2B/3T).
• QTY: Packing Quantity (3000 pcs/reel).
• CAT (or Iv Rank): Luminous Intensity Bin Code (e.g., M1).
• HUE: Dominant Wavelength/Chromaticity Bin Code (e.g., C11).
• REF (or VF Rank): Forward Voltage Bin Code (e.g., 1).
• LOT No: Manufacturing Lot Number for traceability.

9. Application Design Considerations

9.1 Current Limiting is Mandatory

The datasheet explicitly warns: "Customer must apply resistors for protection." LEDs are current-driven devices. A small increase in forward voltage can cause a large, potentially destructive increase in current. An external current-limiting resistor or a constant-current driver circuit is absolutely essential. The resistor value can be calculated using Ohm's Law: R = (Vsupply - VF) / IF, where VF is the typical or maximum value from the appropriate bin.

9.2 Thermal Management

While the package is small, power dissipation (up to 60mW) generates heat. For reliable long-term operation, especially at high ambient temperatures or drive currents:

• Follow the current derating curve.
• Ensure adequate copper area on the PCB connected to the LED pads to act as a heat sink.
• Avoid placing the LED near other heat-generating components.

9.3 Optical Considerations

The wide 100-degree viewing angle makes this LED suitable for applications where the indicator needs to be seen from various angles. For more directed light, external lenses or light guides may be necessary. The water-clear resin provides a bright, unsaturated appearance.

10. Technical Comparison and Differentiation

The 19-21/G LED, based on AlGaInP (Aluminum Gallium Indium Phosphide) technology, offers specific advantages for pure green emission:

• vs. Traditional Green LEDs: AlGaInP technology typically offers higher efficiency and better color purity (narrower spectrum) for green and yellow colors compared to older technologies.
• vs. Larger SMD Packages: The 19-21 footprint is among the smaller standard SMD LED packages, enabling higher density layouts compared to 0603 or 0805 sized LEDs.
• vs. Non-Compliant Components: Its full compliance with RoHS, REACH, and halogen-free standards is a key differentiator in markets with strict environmental regulations, ensuring easier integration into products for global sale.

11. Frequently Asked Questions (Based on Technical Parameters)

11.1 What resistor do I need for a 5V supply?

Using the maximum VF of 2.35V (Bin 2) and a target IF of 20mA for safety: R = (5V - 2.35V) / 0.020A = 132.5 Ohms. The nearest standard value is 130 Ohms or 150 Ohms. Using 150 Ohms gives IF ≈ 17.7mA, which is safe and will provide slightly longer life. Always calculate based on your specific supply voltage and chosen current.

11.2 Can I drive it with 3.3V?

Yes, a 3.3V supply is suitable. The calculation for a resistor would be: R = (3.3V - 2.0V) / 0.020A = 65 Ohms. A 68 Ohm resistor would be a good choice. Ensure the supply can deliver the required current.

11.3 Why is the light output lower at high temperature?

This is a fundamental characteristic of semiconductor LEDs. As temperature increases, the internal quantum efficiency of the light-emitting junction decreases, and non-radiative recombination increases, resulting in less light output for the same drive current. The derating curve compensates for this by reducing the allowable current to manage junction temperature.

11.4 What does "Pb-free" and "Halogen-Free" mean for my design?

Pb-free means the solder plating on the component leads and the internal solder used in manufacturing does not contain lead, aligning with global environmental regulations. Halogen-free means the plastic molding compound does not contain brominated or chlorinated flame retardants above specified limits, reducing the emission of toxic fumes if the device is exposed to extreme heat or fire.

12. Design-in Case Study: Dashboard Switch Backlighting

Scenario: Designing backlighting for an automotive dashboard switch that must be visible in both daylight and darkness, across an operating temperature range of -30°C to +85°C. Design Choices:

1. LED Selection: Choose a bin with higher luminous intensity (e.g., M2) to ensure adequate brightness. Select a tight wavelength bin (e.g., C11) for color consistency across all switches.
2. Drive Circuit: Use a constant-current driver IC designed for automotive environments instead of a simple resistor. This ensures consistent brightness regardless of battery voltage fluctuations (e.g., from 9V to 16V). Set the current to 15-18mA to enhance longevity and account for the high ambient temperature.
3. PCB Layout: Provide generous copper pours connected to the LED's thermal pads (anode and cathode) to dissipate heat into the PCB. Use thermal vias if the board is multi-layer.
4. Optical Design: The 100-degree viewing angle is sufficient for most switch designs. A light pipe or diffuser may be used to evenly spread the light under the switch icon.
5. Storage & Assembly: Follow the moisture sensitivity guidelines strictly, as automotive PCB assemblies often undergo multiple reflow cycles.

This approach ensures a reliable, bright, and consistent indicator that meets automotive-grade requirements.

13. Operating Principle

This LED operates on the principle of electroluminescence in a semiconductor p-n junction. The chip material is AlGaInP (Aluminum Gallium Indium Phosphide). When a forward voltage exceeding the junction's built-in potential is applied, electrons from the n-type region and holes from the p-type region are injected into the active region. There, they recombine radiatively, releasing energy in the form of photons (light). The specific composition of the AlGaInP alloy determines the bandgap energy, which directly defines the wavelength (color) of the emitted light—in this case, pure green around 561 nm. The water-clear epoxy resin encapsulant protects the chip, acts as a lens to shape the light output, and may include phosphors or diffusers (though for a mono-color type, it is typically clear).

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