SMD LED 19-21/BHC-AP1Q2/3T Datasheet - Blue - 2.0x1.25x0.8mm - 3.3V - 75mW - English Technical Document

1. Product Overview

The 19-21/BHC-AP1Q2/3T is a compact, surface-mount blue LED designed for modern electronic applications requiring high-density component placement and reliable performance. This device utilizes InGaN chip technology to produce a blue emission with a typical dominant wavelength of 468 nm. Its primary advantages include a significantly reduced footprint compared to leaded LEDs, enabling smaller PCB designs, higher packing density, and ultimately more compact end products. The lightweight construction further makes it ideal for miniature and portable applications.

Key product positioning includes use as an indicator or backlight source in consumer electronics, telecommunications equipment, automotive dashboards, and general illumination where a compact blue light source is required. The device is fully compliant with RoHS, REACH, and halogen-free regulations, making it suitable for global markets with strict environmental standards.

1.1 Core Features and Advantages

• Miniaturized Package: The 19-21 SMD format is substantially smaller than traditional lead-frame LEDs, contributing to space savings on the PCB.
• Automation Compatibility: Supplied on 8mm tape on 7-inch reels, it is fully compatible with high-speed automatic pick-and-place equipment.
• Robust Soldering: Compatible with both infrared and vapor phase reflow soldering processes, ensuring reliable assembly in high-volume manufacturing.
• Environmental Compliance: The product is Pb-free, RoHS compliant, REACH compliant, and meets halogen-free requirements (Br <900 ppm, Cl <900 ppm, Br+Cl < 1500 ppm).
• Mono-Color Design: Provides a consistent blue color output.

2. Technical Parameter Deep Dive

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.

Interpretation: The forward current rating of 20mA is standard for small-signal LEDs. The low reverse voltage rating (5V) highlights that this device is not designed for reverse bias operation and requires protection in circuits where reverse voltage might occur. The ESD rating of 150V (HBM) indicates moderate sensitivity; proper ESD handling procedures are essential during assembly.

2.2 Electro-Optical Characteristics

These parameters are measured at Ta=25°C and define the typical performance of the LED under normal operating conditions.

Interpretation: The luminous intensity has a wide range (45-112 mcd), which is managed through a binning system (detailed later). The typical forward voltage of 3.3V at 20mA is a key parameter for circuit design, as it determines the required current-limiting resistor value. The 100-degree viewing angle provides a wide emission pattern suitable for indicator applications.

2.3 Thermal Characteristics

While not explicitly listed in a separate table, thermal management is implied through the power dissipation (75mW) and operating temperature range (-40 to +85°C). The forward current derating curve (shown in the PDF) is critical for design. As ambient temperature increases, the maximum allowable forward current must be reduced to prevent overheating and accelerated degradation. Designers must consult this curve to ensure reliable operation at elevated temperatures.

3. Binning System Explanation

The LED manufacturing process results in natural variations in key parameters. Binning sorts LEDs into groups (bins) with tightly controlled characteristics to ensure consistency in the final application.

3.1 Luminous Intensity Binning

Application Note: For applications requiring uniform brightness across multiple LEDs (e.g., backlighting arrays), specifying a single, narrow bin (e.g., Q1 only) is essential. The product code \"AP1Q2/3T\" likely includes bin information (Q2 for intensity).

3.2 Dominant Wavelength Binning

Application Note: This binning ensures color consistency. The typical peak wavelength is 468nm, which falls within the A10 bin. Matching wavelength bins is crucial for applications where color perception is important.

4. Performance Curve Analysis

The datasheet provides several characteristic curves that are vital for understanding device behavior under non-standard conditions.

4.1 Relative Luminous Intensity vs. Forward Current

This curve shows that luminous intensity is not linearly proportional to current. It increases with current but may saturate or even decrease at very high currents due to thermal effects and efficiency droop. Operating at or below the recommended 20mA ensures optimal efficiency and longevity.

4.2 Relative Luminous Intensity vs. Ambient Temperature

LED light output decreases as the junction temperature rises. This curve quantifies that relationship. For example, at an ambient temperature of 85°C, the light output may be only 70-80% of its value at 25°C. This must be factored into brightness calculations for high-temperature environments.

4.3 Forward Voltage vs. Forward Current

This IV curve demonstrates the diode's exponential relationship between voltage and current. The \"knee\" voltage is around 2.7-3.0V. A small increase in voltage beyond this point causes a large increase in current, underscoring the critical need for a current-limiting driver or resistor.

4.4 Spectrum Distribution

The graph shows a single peak centered around 468nm with a typical full width at half maximum (FWHM) of 25nm. This is characteristic of a blue InGaN LED and defines the pure blue color emitted.

4.5 Radiation Pattern

The polar diagram illustrates the spatial distribution of light. The 19-21 package exhibits a lambertian or near-lambertian pattern with a 100-degree viewing angle, meaning light intensity is highest when viewed head-on and decreases gradually towards the sides.

5. Mechanical and Package Information

5.1 Package Dimensions

The 19-21 SMD LED has nominal dimensions of 2.0mm (length) x 1.25mm (width) x 0.8mm (height). Tolerances are typically ±0.1mm unless otherwise specified. The package drawing clearly indicates the cathode mark, which is essential for correct orientation during PCB assembly. The recommended PCB land pattern (pad design) should follow these dimensions to ensure proper soldering and mechanical stability.

5.2 Polarity Identification

A distinct cathode mark is present on the device. Correct polarity is mandatory; applying reverse voltage exceeding 5V can cause immediate damage.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Profile

A lead-free (Pb-free) reflow profile is specified:

• 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 Rate: Maximum 6°C/sec.
• Cooling Rate: Maximum 3°C/sec.

6.2 Hand Soldering

If hand soldering is unavoidable, use a soldering iron with a tip temperature below 350°C. Contact time per terminal should be less than 3 seconds, with a soldering iron power rating below 25W. Allow a cooling interval of at least 2 seconds between soldering each terminal. Hand soldering poses a higher risk of thermal damage.

6.3 Rework and Repair

Repair after soldering is not recommended. If absolutely necessary, a specialized double-head soldering iron should be used to simultaneously heat both terminals and lift the component without applying mechanical stress to the LED body. The potential for damage is high.

7. Storage and Handling Precautions

7.1 Moisture Sensitivity

The LEDs are packaged in a moisture-resistant bag with desiccant.

1. Do not open the moisture-proof bag until ready for use.
2. After opening, unused LEDs should be stored at ≤30°C and ≤60% Relative Humidity.
3. The \"floor life\" after bag opening is 168 hours (7 days).
4. If not used within this time, or if the desiccant indicator has changed color, a bake-out is required: 60 ±5°C for 24 hours before use.

7.2 ESD Protection

With an ESD rating of 150V (HBM), these devices are sensitive to electrostatic discharge. Use standard ESD precautions during handling and assembly: grounded workstations, wrist straps, and conductive containers.

8. Packaging and Ordering Information

8.1 Standard Packaging

The device is supplied on embossed carrier tape with dimensions tailored for the 19-21 package. The tape is wound on a standard 7-inch diameter reel. Each reel contains 3000 pieces.

8.2 Reel and Tape Dimensions

Detailed drawings for the reel, carrier tape, and cover tape are provided in the datasheet. Adherence to these dimensions ensures compatibility with automated assembly equipment.

8.3 Label Information

The reel label contains critical information for traceability and verification:

• P/N: Product Number (e.g., 19-21/BHC-AP1Q2/3T).
• QTY: Packing Quantity (3000 pcs/reel).
• CAT: Luminous Intensity Rank (e.g., Q2).
• HUE: Chromaticity/Dominant Wavelength Rank (e.g., A10).
• REF: Forward Voltage Rank.
• LOT No: Manufacturing Lot Number for traceability.

9. Application Suggestions and Design Considerations

9.1 Typical Applications

• Backlighting: For buttons, switches, symbols, and LCD panels in consumer electronics, automotive dashboards, and industrial controls.
• Status Indicators: In telecommunications equipment (phones, fax machines), networking devices, and power supplies.
• General Illumination: As a compact blue light source in decorative lighting, signage, and wearable electronics.

9.2 Critical Design Considerations

1. Current Limiting: An external current-limiting resistor is MANDATORY. The LED's exponential V-I characteristic means a small voltage change causes a large current change, leading to thermal runaway and failure. Calculate the resistor value using R = (Vsupply - VF) / IF, where VF is the maximum expected forward voltage from the datasheet (e.g., 3.7V).
2. Thermal Management: Although low-power, heat dissipation must be considered, especially in enclosed spaces or high ambient temperatures. Use the derating curve. Ensure adequate copper area on the PCB under and around the LED pads to act as a heat sink.
3. Optical Design: The 100-degree viewing angle is suitable for wide viewing. For more focused light, external lenses or light guides may be required. Consider the binning codes to ensure color and brightness uniformity in multi-LED designs.
4. PCB Layout: Follow the recommended pad layout from the package drawing. Ensure the cathode mark on the footprint matches the device orientation.

10. Technical Comparison and Differentiation

The 19-21/BHC-AP1Q2/3T differentiates itself primarily through its compact 2.0x1.25mm footprint, which is smaller than many traditional SMD LEDs like the 0603 (1.6x0.8mm) or 0805 (2.0x1.25mm) packages that often house LEDs, offering potential space savings. Its typical 3.3V forward voltage is compatible with common 3.3V logic supplies. Compared to non-binned LEDs, its defined intensity and wavelength bins provide predictable performance, reducing design uncertainty. Compliance with modern environmental standards (RoHS, Halogen-Free) is a baseline requirement but remains a key differentiator in regulated markets.

11. Frequently Asked Questions (FAQ)

Q1: What is the purpose of the binning codes (P1, Q2, A10, etc.)?
A1: Binning ensures consistency. Luminous Intensity bins (P1, Q2) guarantee a minimum brightness. Wavelength bins (A9-A12) guarantee a specific color range. Always specify bins for applications requiring uniformity.

Q2: Can I drive this LED directly from a 3.3V microcontroller pin?
A2: No. The forward voltage is typically 3.3V, leaving no voltage headroom for a current-limiting resistor if connected directly to a 3.3V rail. This would result in uncontrolled current and damage. You must use a driver circuit or a higher supply voltage with a series resistor.

Q3: How do I calculate the correct series resistor?
A3: Use Ohm's Law: R = (Vs - Vf) / If. For a 5V supply (Vs), using the maximum Vf of 3.7V and target If of 20mA: R = (5 - 3.7) / 0.02 = 65 ohms. Use the next standard value (e.g., 68 ohms). Always recalculate power dissipation in the resistor: P = (If^2)*R.

Q4: Why is the storage and baking procedure so important?
A4: SMD packages can absorb moisture. During reflow soldering, this moisture can turn to steam rapidly, causing internal delamination or \"popcorning,\" which cracks the package and destroys the LED. The baking process removes this absorbed moisture.

12. Practical Application Example

Scenario: Designing a status indicator panel with 10 uniform blue LEDs.

1. Specification: Select the 19-21/BHC-AP1Q2/3T for its compact size and blue color.
2. Binning: To ensure uniform brightness and color, specify a single intensity bin (e.g., Q1) and a single wavelength bin (e.g., A10) in the purchase order.
3. Circuit Design: Using a 5V system supply. Calculate resistor: R = (5V - 3.7V) / 0.02A = 65Ω. Use 68Ω 5% resistors. Power per resistor: (0.02^2)*68 = 0.0272W, so a standard 1/10W (0.1W) resistor is sufficient.
4. PCB Layout: Place LEDs with 2.0x1.25mm pads, ensuring correct cathode orientation. Include a small copper pour connected to the cathode pads for slight heat spreading.
5. Assembly: Follow the specified reflow profile. Keep the reel sealed until the moment of use in production.

13. Operating Principle

The 19-21/BHC-AP1Q2/3T is a semiconductor light-emitting diode. Its core is a chip made of Indium Gallium Nitride (InGaN) materials. When a forward voltage exceeding the diode's knee voltage (approx. 2.7V) is applied, electrons and holes are injected into the active region of the semiconductor. These charge carriers recombine, releasing energy in the form of photons (light). The specific composition of the InGaN alloy determines the bandgap energy, which directly corresponds to the wavelength of the emitted light—in this case, blue light around 468 nm. The water-clear resin encapsulant protects the chip and acts as a primary lens, shaping the initial light output pattern.

14. Technology Trends

The development of SMD LEDs like the 19-21 series follows broader industry trends: Miniaturization continues, enabling ever-smaller and denser electronic assemblies. Increased Efficiency is a constant driver, yielding higher luminous intensity from the same or smaller chip sizes. Enhanced Reliability and Robustness are critical, leading to improved materials for encapsulants and higher temperature tolerances for lead-free soldering. Tighter Binning and Color Consistency are increasingly demanded by applications like display backlighting. Finally, integration of control electronics directly with the LED die (e.g., IC-driven LEDs) is a growing trend, though for simple indicator types like this, the discrete, driver-less model remains dominant due to its cost-effectiveness and design flexibility.