SMD LED 19-21 Deep Red Datasheet - Dimensions 2.0x1.25x0.8mm - Voltage 1.7-2.3V - Power 60mW - English Technical Document

1. Product Overview

This document details the specifications for a compact, surface-mount Deep Red LED in the 19-21 package format. Designed for modern automated assembly processes, this component offers significant advantages in board space utilization and design miniaturization. Its primary application is as an indicator or backlight source in various electronic devices, leveraging its high brightness and reliable performance in a small footprint.

1.1 Core Features and Advantages

The key advantages of this LED stem from its SMD (Surface Mount Device) construction. Compared to traditional leaded components, it enables:

• Reduced Board Size & Higher Density: The small 19-21 package allows for tighter component placement, leading to more compact PCB designs.
• Compatibility with Automation: Supplied on 8mm tape on 7-inch reels, it is fully compatible with high-speed pick-and-place equipment, streamlining manufacturing.
• Environmental Compliance: The product is Pb-free, compliant with RoHS and EU REACH regulations, and meets halogen-free standards (Br <900ppm, Cl <900ppm, Br+Cl <1500ppm).
• Robust Soldering: It is suitable for both infrared and vapor phase reflow soldering processes.

1.2 Target Applications

This LED is suited for a variety of applications requiring a reliable red indicator or backlight, including:

• Backlighting for instrument panels, switches, and symbols.
• Status indicators and backlighting in telecommunication equipment (e.g., telephones, fax machines).
• General backlighting for LCD panels.
• General purpose indicator use in consumer and industrial electronics.

2. Technical Parameter Analysis

This section provides a detailed, objective interpretation of the key electrical, optical, and thermal parameters that define the LED's performance envelope.

2.1 Absolute Maximum Ratings

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

• Reverse Voltage (V_R): 5V. Exceeding this voltage in reverse bias can cause immediate junction breakdown.
• Continuous Forward Current (I_F): 25mA. The maximum DC current for reliable long-term operation.
• Peak Forward Current (I_FP): 60mA (at 1/10 duty cycle, 1kHz). Suitable for pulsed operation but not for DC.
• Power Dissipation (P_d): 60mW. The maximum power the package can dissipate at Ta=25°C, limiting the combination of forward voltage and current.
• ESD Sensitivity (HBM): 2000V. Classifies the device as moderately robust against electrostatic discharge, but standard ESD handling precautions are still necessary.
• Temperature Range: Operating from -40°C to +85°C; storage from -40°C to +90°C.
• Soldering Temperature: Withstands reflow profiles with a peak of 260°C for 10 seconds or hand soldering at 350°C for 3 seconds per terminal.

2.2 Electro-Optical Characteristics

Measured at Ta=25°C and I_F=20mA, these are the typical performance parameters.

• Luminous Intensity (I_v): Ranges from 36.0 mcd (min) to 90.0 mcd (max), with a typical tolerance of ±11%. This defines the perceived brightness.
• Viewing Angle (2θ_1/2): Approximately 100 degrees (typical). This wide angle provides good off-axis visibility.
• Peak Wavelength (λ_p): 650 nm (typical). The wavelength at which the spectral output is strongest.
• Dominant Wavelength (λ_d): Between 636.0 nm and 646.0 nm. This defines the perceived color (deep red).
• Spectral Bandwidth (Δλ): Approximately 20 nm (typical). Indicates the spectral purity of the emitted light.
• Forward Voltage (V_F): Between 1.70 V and 2.30 V at 20mA, with a typical tolerance of ±0.05V. This is critical for current-limiting resistor calculation.
• Reverse Current (I_R): Maximum 10 μA at V_R=5V. The device is not intended for operation in reverse bias.

3. Binning System Explanation

The product is sorted into performance bins to ensure consistency within a production lot. The part number 19-21/R8C-FN2Q1/3T incorporates these bin codes.

3.1 Luminous Intensity Binning

Binned at I_F=20mA. The code "Q1" in the part number corresponds to the highest brightness tier.

• N2: 36.0 – 45.0 mcd
• P1: 45.0 – 57.0 mcd
• P2: 57.0 – 72.0 mcd
• Q1: 72.0 – 90.0 mcd

3.2 Dominant Wavelength Binning

Binned at I_F=20mA. The code "FN2" likely relates to this chromaticity sorting.

• FF4: 636.0 – 641.0 nm
• FF5: 641.0 – 646.0 nm

3.3 Forward Voltage Binning

Binned at I_F=20mA. The code "19-21" in the part number indicates the voltage bin range.

• 19: 1.70 – 1.80 V
• 20: 1.80 – 1.90 V
• 21: 1.90 – 2.00 V
• 22: 2.00 – 2.10 V
• 23: 2.10 – 2.20 V
• 24: 2.20 – 2.30 V

4. Performance Curve Analysis

While specific graphs are not detailed in the provided text, typical curves for such a device would include:

• Relative Luminous Intensity vs. Forward Current: Shows how brightness increases with current, typically in a sub-linear fashion at higher currents due to heating.
• Forward Voltage vs. Forward Current: Demonstrates the diode's exponential I-V characteristic.
• Relative Luminous Intensity vs. Ambient Temperature: Shows the decrease in light output as junction temperature rises, a key consideration for thermal management.
• Spectral Distribution: A plot of relative intensity vs. wavelength, centered around 650nm with a ~20nm bandwidth.

Designers should consult these curves to understand performance under non-standard conditions (different currents, temperatures).

5. Mechanical and Package Information

5.1 Package Dimensions

The 19-21 SMD package has nominal dimensions of 2.0mm (length) x 1.25mm (width) x 0.8mm (height). A cathode mark is clearly indicated on the package for correct orientation. All unspecified tolerances are ±0.1mm. The exact dimensional drawing is essential for PCB pad layout design.

5.2 Polarity Identification

Correct polarity is crucial. The package features a distinct cathode mark. Incorrect insertion will prevent the LED from illuminating as it will be reverse-biased.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Profile

The LED is rated for Pb-free reflow soldering. The recommended profile includes:

• Pre-heating: 150–200°C for 60–120 seconds.
• Time Above Liquidus (217°C): 60–150 seconds.
• Peak Temperature: 260°C maximum, held for no more than 10 seconds.
• Heating/Cooling Rates: Maximum 6°C/sec heating and 3°C/sec cooling above 255°C.

Critical: Reflow should not be performed more than two times to avoid thermal stress damage.

6.2 Hand Soldering

If hand soldering is necessary:

• Use a soldering iron with a tip temperature <350°C.
• Limit contact time to 3 seconds per terminal.Use an iron with power ≤25W.
• Allow a minimum 2-second interval between soldering each terminal.
• Avoid applying mechanical stress to the component during soldering.

6.3 Storage and Moisture Sensitivity

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

• Before Use: Do not open the bag until ready for assembly.
• After Opening: Use within 168 hours (7 days) if stored at ≤30°C and ≤60% RH.
• Exposure Limit: If the exposure time is exceeded or the desiccant indicates saturation, a bake-out at 60±5°C for 24 hours is required before reflow.

7. Packaging and Ordering Information

7.1 Packaging Specifications

The LEDs are supplied in a tape-and-reel format suitable for automated assembly.

• Carrier Tape Width: 8mm.
• Reel Diameter: 7 inches.
• Quantity per Reel: 3000 pieces.
• Moisture-proof Bag: Includes desiccant and humidity indicator label.

7.2 Label Explanation

The reel label contains critical information for traceability and verification:

• Customer Part Number (CPN)
• Product Number (P/N)
• Packing Quantity (QTY)
• Luminous Intensity Rank (CAT)
• Chromaticity/Dominant Wavelength Rank (HUE)
• Forward Voltage Rank (REF)
• Lot Number (LOT No.)

8. Application Design Considerations

8.1 Current Limiting is Mandatory

LEDs are current-driven devices. An external current-limiting resistor must always be used in series. The forward voltage has a negative temperature coefficient; a slight increase in voltage can cause a large, potentially destructive increase in current if not properly limited. Calculate the resistor value using R = (V_supply - V_F) / I_F.

8.2 Thermal Management

While the package is small, power dissipation (up to 60mW) generates heat. For continuous operation at high currents or in elevated ambient temperatures, ensure adequate PCB copper area or thermal vias are used to conduct heat away from the LED's solder pads, maintaining a lower junction temperature for optimal lifetime and light output stability.

8.3 Application Restrictions

This product is designed for general commercial and industrial applications. It may not be suitable for high-reliability applications without prior qualification. Such applications include, but are not limited to, automotive safety/security systems, military/aerospace, and life-critical medical equipment. The device must not be operated outside the specifications outlined in this datasheet.

9. Technical Comparison and Differentiation

The primary differentiation of this 19-21 Deep Red LED lies in its specific combination of attributes:

• vs. Larger SMD LEDs (e.g., 3528): Offers a significantly smaller footprint for space-constrained designs, albeit often at a lower total light output.
• vs. Standard Red LEDs (e.g., 630nm): The 650nm deep red emission provides a distinct color point, which may be required for specific aesthetic or functional reasons (e.g., certain sensor applications, specific backlight color requirements).
• vs. Non-binned LEDs: The comprehensive binning system (intensity, wavelength, voltage) ensures much tighter color and brightness consistency within a production run, which is critical for applications using multiple LEDs where uniformity is important.

10. Frequently Asked Questions (FAQs)

10.1 Why does my LED need a series resistor?

An LED's I-V characteristic is very steep. Without a resistor to limit current, any small variation in supply voltage or forward voltage drop (which changes with temperature) will cause a large change in current, likely exceeding the Absolute Maximum Rating and destroying the LED. The resistor provides a stable, predictable current.

10.2 Can I drive this LED with a voltage higher than its V_F?

Yes, but only if you use a series resistor (or a constant-current driver) to drop the excess voltage and set the correct current. Applying a voltage source directly equal to V_F is impractical due to unit-to-unit and temperature variations.

10.3 What happens if I solder it backwards?

The LED will not light up, as it will be reverse-biased. As long as the reverse voltage does not exceed the 5V maximum rating, no immediate damage should occur from brief incorrect insertion. However, it will not function.

10.4 Why is there a 7-day limit after opening the moisture-proof bag?

The plastic packaging of SMD components can absorb moisture from the air. During the high-temperature reflow soldering process, this trapped moisture can rapidly expand, causing internal delamination or "popcorning" that cracks the LED die or package. The 7-day floor life assumes proper storage conditions; exceeding it requires a bake-out to remove moisture.

11. Practical Design and Usage Example

Scenario: Designing a status indicator panel with 10 uniform deep red LEDs powered from a 5V digital logic rail.

1. Current Selection: Choose a drive current. For good brightness and longevity, 20mA is specified. Using 15mA would increase lifetime and reduce heat.
2. Resistor Calculation: Assume worst-case V_F = 2.3V (Max from datasheet). For I_F=20mA at 5V: R = (5V - 2.3V) / 0.02A = 135 Ω. The nearest standard value is 130 Ω or 150 Ω. Using 150 Ω gives I_F ≈ (5-2.3)/150 = 18mA, which is safe and within spec.
3. Power in Resistor: P = I²R = (0.018)² * 150 = 0.0486W. A standard 1/8W (0.125W) resistor is sufficient.
4. PCB Layout: Place the 150Ω resistor in series with each LED's anode. Follow the package dimensions for pad layout. Ensure the cathode mark on the PCB silkscreen matches the LED's marking. For thermal performance, connect the LED pads to a small copper pour.
5. Assembly: Keep reels sealed until the production line is ready. Follow the reflow profile precisely. After assembly, avoid bending the PCB near the LEDs.

12. Operating Principle

This LED is based on an AlGaInP (Aluminum Gallium Indium Phosphide) semiconductor chip. When a forward voltage exceeding the diode's junction potential (V_F) is applied, electrons and holes are injected into the active region where they recombine. In this specific material system, the energy released during recombination corresponds to a photon in the deep red portion of the visible spectrum (approximately 650nm). The epoxy resin package is water-clear to maximize light extraction and also serves to protect the semiconductor die from the environment.

13. Technology Trends

The 19-21 package represents an ongoing trend in optoelectronics towards miniaturization and integration. While not the smallest package available today, it offers a balance between size, manufacturability, and performance. Industry trends for indicator-type LEDs continue to focus on:

• Increased Efficiency: Achieving higher luminous intensity (mcd) at lower drive currents to reduce system power consumption.
• Enhanced Reliability: Improving materials and packaging to withstand higher reflow temperatures and harsher environmental conditions.
• Tighter Binning: Providing more precise sorting on color and intensity to meet the demands of applications requiring high uniformity, such as full-color displays or backlight arrays.
• Broadened Compliance: Adherence to evolving global environmental and safety regulations (RoHS, REACH, halogen-free) is now a standard requirement.