Yellow SMD LED Specification - 2.0x1.25x0.7mm - Voltage 1.8-2.4V - Power 72mW - English Technical Document

1. Product Overview

This document details the specifications for a compact, surface-mount yellow LED designed for modern electronic applications. The device is fabricated using a yellow semiconductor chip and packaged in a miniature footprint, making it suitable for space-constrained designs requiring reliable visual indicators.

1.1 General Description

The LED is a color light-emitting diode based on a yellow light chip. Its primary package dimensions are 2.0mm in length, 1.25mm in width, and 0.7mm in height. This small form factor allows for high-density placement on printed circuit boards (PCBs).

1.2 Features

• Extremely wide viewing angle for excellent visibility from various positions.
• Fully compatible with standard SMT (Surface Mount Technology) assembly and soldering processes.
• Moisture Sensitivity Level (MSL): Level 3, indicating specific handling and storage requirements to prevent moisture-induced damage during reflow.
• Compliant with RoHS (Restriction of Hazardous Substances) directives, ensuring it is free from specific hazardous materials like lead and mercury.

1.3 Application

This LED is versatile and can be used in numerous applications, including but not limited to:

• Status and power indicators in consumer electronics, appliances, and industrial equipment.
• Backlighting for switches, symbols, and small displays.
• General-purpose indicator lights where a yellow signal is required.

2. Technical Parameters Deep Dive

This section provides a detailed, objective analysis of the LED's key performance characteristics under standard test conditions (Ts=25°C).

2.1 Electrical & Optical Characteristics

The core performance is defined by several key parameters measured at a forward current (IF) of 20mA.

• Dominant Wavelength (λD): Defines the perceived color. This product is offered in bins: 2K (585-590nm) and 2L (590-595nm), producing a yellow hue.
• Forward Voltage (VF): The voltage drop across the LED when operating. It is binned into three categories: B0 (1.8-2.0V), C0 (2.0-2.2V), and D0 (2.2-2.4V). Designers must account for this range when designing driver circuits.
• Luminous Intensity (IV): The amount of visible light emitted. Available in multiple intensity bins: 1AP (90-120 mcd), G20 (120-150 mcd), 1AW (150-200 mcd), and 1AT (200-260 mcd).
• Viewing Angle (2θ1/2): A very wide 140-degree typical angle, ensuring the LED is visible from a broad range of viewpoints.
• Spectral Half Bandwidth (Δλ): Approximately 15nm, indicating the spectral purity of the yellow light.
• Reverse Current (IR): Maximum of 10 μA at a reverse voltage (VR) of 5V, which is also the test condition for sorting.
• Thermal Resistance (RθJ-S): Junction-to-solder point thermal resistance is ≤450 °C/W. This parameter is critical for thermal management, as it affects the maximum allowable operating current based on ambient conditions.

2.2 Absolute Maximum Ratings

These are the stress limits beyond which permanent damage to the device may occur. Operation at or near these limits is not recommended for reliable long-term performance.

• Power Dissipation (Pd): 72 mW
• Continuous Forward Current (IF): 30 mA
• Peak Forward Pulse Current (IFP): 60 mA (under pulsed conditions: 0.1ms pulse width, 1/10 duty cycle)
• Electrostatic Discharge (ESD) HBM: 2000V
• Operating Temperature (Topr): -40°C to +85°C
• Storage Temperature (Tstg): -40°C to +85°C
• Maximum Junction Temperature (Tj): 95°C. This is a key constraint; the actual maximum forward current in an application must be determined by measuring the package temperature to ensure Tj is not exceeded.

Important Notes: Measurement tolerances are specified: Forward Voltage (±0.1V), Dominant Wavelength (±2nm), Luminous Intensity (±10%). All testing is performed under standardized conditions.

3. Performance Curve Analysis

The following characteristic curves provide insight into the LED's behavior under varying conditions.

3.1 Forward Voltage vs. Forward Current (IV Curve)

The curve shows the non-linear relationship between voltage and current. The forward voltage increases with current, typically starting around 1.8V-2.4V at 20mA as per the binning. This curve is essential for selecting appropriate current-limiting resistors or constant-current drivers.

3.2 Relative Intensity vs. Forward Current

This graph demonstrates how light output increases with forward current. It is generally sub-linear; doubling the current does not double the light output and increases heat generation. Operating at or below the recommended 20mA is optimal for efficiency and longevity.

3.3 Relative Intensity vs. Ambient Temperature

LED light output decreases as the ambient (or pin) temperature rises. This thermal quenching effect is a fundamental property of semiconductors. The curve shows the relative intensity dropping as temperature increases from 0°C to 100°C, highlighting the importance of thermal management for consistent brightness.

3.4 Forward Current vs. Pin Temperature

This curve illustrates the self-heating effect. For a given forward current, the pin temperature rises. It underscores the need to derate the maximum operating current in high-ambient-temperature environments to prevent exceeding the maximum junction temperature.

4. Mechanical & Package Information

4.1 Package Dimensions

The LED has a compact rectangular footprint. Key dimensions include a body size of 2.00mm x 1.25mm, a height of 0.70mm, and a lead width of 0.30mm. All dimension tolerances are ±0.2mm unless otherwise specified. Figures include top, bottom, and side views.

4.2 Polarity Identification & Soldering Pattern

The cathode is clearly marked on the top of the package. A recommended soldering land pattern (footprint) is provided for PCB design, which is crucial for achieving reliable solder joints and proper alignment during reflow. The recommended pad dimensions help ensure good solder fillets and mechanical stability.

5. Soldering & Assembly Guidelines

5.1 SMT Reflow Soldering Instructions

As an MSL Level 3 component, this LED requires specific handling. It must be stored in a dry environment (typically <10% RH at 25°C) in its original moisture barrier bag. Once the bag is opened, components must be mounted within 168 hours (7 days) if exposed to factory floor conditions (>30°C/60%RH), or they must be re-baked before use according to the manufacturer's instructions. Standard infrared or convection reflow profiles with peak temperatures not exceeding 260°C are suitable.

5.2 Handling Precautions

• Avoid applying mechanical stress to the LED lens.
• Use proper ESD (Electrostatic Discharge) precautions during handling and assembly.
• Do not exceed the absolute maximum ratings for current, voltage, or temperature.
• Ensure the polarity is correct during placement to prevent reverse bias damage.
• Follow the recommended land pattern for optimal soldering results.

6. Packaging & Ordering Information

6.1 Packaging Specification

The LEDs are supplied in industry-standard packaging for automated assembly.

• Carrier Tape: Dimensions for the embossed carrier tape that holds individual components.
• Reel: Specifications for the reel onto which the carrier tape is wound, including reel diameter and hub size.
• Label: The reel label contains critical information such as part number, quantity, lot number, and date code.

6.2 Moisture Resistant Packing

To maintain MSL Level 3 integrity, the reels are packaged in moisture barrier bags with desiccant and a humidity indicator card to show if the bag's internal environment has been compromised.

7. Application Suggestions & Design Considerations

7.1 Typical Application Circuits

The simplest drive method is a series current-limiting resistor. The resistor value (R) is calculated using the formula: R = (Vcc - VF) / IF, where Vcc is the supply voltage, VF is the forward voltage (use the maximum value from the bin for a safe design), and IF is the desired forward current (e.g., 20mA). For constant brightness across a supply voltage range or among multiple LEDs, a constant-current driver is recommended.

7.2 Design Considerations

• Thermal Management: Due to the thermal resistance of 450 °C/W, ensure adequate PCB copper area or thermal vias under the solder pads to dissipate heat, especially when operating at higher currents or in warm environments.
• Current Derating: Always check the actual junction temperature. The maximum continuous current of 30mA may need to be reduced if the ambient temperature is high or if the thermal path is poor, to keep Tj below 95°C.
• Optical Design: The 140-degree viewing angle provides a wide, diffuse light pattern. For more focused light, an external lens may be required.

8. Technical Comparison & Differentiation

Compared to generic through-hole LEDs, this SMD device offers significant advantages: a much smaller footprint enabling miniaturization, suitability for high-speed automated pick-and-place assembly, and typically better reliability due to the absence of wire bonds that can fatigue. Its specific binning for voltage and intensity allows for tighter consistency in end-product performance compared to unbinned components.

9. Frequently Asked Questions (FAQs)

9.1 What is the difference between the VF bins (B0, C0, D0)?

The bins categorize the forward voltage drop of the LED. B0 LEDs have the lowest voltage (1.8-2.0V), while D0 have the highest (2.2-2.4V). This allows designers to select LEDs for consistent brightness when driven by a constant voltage, or to group LEDs with similar VF when connecting them in parallel.

9.2 How long can I use the LED after opening the moisture barrier bag?

For MSL Level 3, the "floor life" is 168 hours (7 days) when stored at conditions not exceeding 30°C/60% RH. If this time is exceeded or the humidity indicator card shows a warning, the components must be re-baked before reflow soldering to prevent "popcorning" (package cracking due to rapid vapor expansion).

9.3 Can I drive this LED with a 5V supply directly?

No. Connecting a 5V supply directly across the LED would attempt to force a current far exceeding its maximum rating, causing immediate failure. You must always use a series current-limiting resistor or a constant-current driver. For example, with a 5V supply and a typical VF of 2.0V at 20mA, a resistor of (5V - 2.0V) / 0.02A = 150 Ohms would be required.

10. Practical Use Case Example

Scenario: Designing a status indicator for a portable battery-powered device.

• Part Selection: Choose an intensity bin (e.g., 1AW: 150-200mcd) suitable for daytime visibility. Select a VF bin based on your battery voltage to optimize efficiency.
• Circuit Design: With a 3.3V system voltage and using a VF(max) of 2.2V (D0 bin) for a safe calculation, the current-limiting resistor for 20mA is (3.3V - 2.2V) / 0.02A = 55 Ohms. A standard 56-Ohm resistor would be used.
• Layout: Place the LED on the PCB according to the recommended land pattern. Add a small copper pour connected to the cathode pad (typically the thermal pad) to aid heat dissipation.
• Assembly: Follow MSL Level 3 handling procedures. Use a standard lead-free reflow profile with a peak temperature around 245°C.

11. Operating Principle

Light is emitted through a process called electroluminescence. When a forward voltage is applied across the semiconductor p-n junction, electrons and holes are injected into the junction region. When these charge carriers recombine, energy is released in the form of photons (light). The specific material composition of the semiconductor chip determines the wavelength (color) of the emitted light—in this case, a yellow phosphor or semiconductor material produces light in the 585-595nm range.

12. Industry Trends

The trend in indicator LEDs continues toward miniaturization, higher efficiency, and tighter performance consistency. There is increasing integration of control electronics (like constant-current drivers) within LED packages. Furthermore, advancements in materials and packaging techniques are steadily improving thermal performance, allowing for higher power densities and reliability in smaller footprints. The demand for RoHS-compliant and environmentally friendly components remains a strong market driver.