SMD LED LTST-C19DTGKT-NB Datasheet - 0603 Package - 2.5-3.1V - Green - 38mW - English Technical Document

1. Product Overview

This document provides the complete technical specifications for a miniature surface-mount device (SMD) LED lamp. Designed for automated printed circuit board (PCB) assembly, this component is ideal for space-constrained applications across a wide range of consumer and industrial electronics. Its compact form factor and compatibility with high-volume manufacturing processes make it a versatile choice for modern electronic design.

1.1 Key Features and Advantages

The LED offers several distinct advantages for designers and manufacturers. It utilizes an Ultra Bright InGaN (Indium Gallium Nitride) semiconductor chip, which is known for high efficiency and good color purity in the green spectrum. The component is fully compliant with the Restriction of Hazardous Substances (RoHS) directive. It is supplied in industry-standard 8mm tape on 7-inch diameter reels, facilitating efficient handling by automated pick-and-place equipment. The package design is compatible with infrared (IR) reflow soldering processes, aligning with common lead-free (Pb-free) assembly lines.

1.2 Target Applications and Markets

This SMD LED is suitable for numerous applications where reliable, compact indication or backlighting is required. Primary markets include telecommunications equipment (e.g., cellular and cordless phones), office automation devices (e.g., notebook computers, network systems), and various home appliances. Specific uses encompass keyboard or keypad backlighting, status indicators for electronic devices, integration into microdisplays, and general signal or symbolic luminaires.

2. Package Dimensions and Mechanical Specifications

The LED is housed in a standard 0603 package footprint, which denotes dimensions of approximately 1.6mm in length and 0.8mm in width. The specific lens for this model is water clear with a black cap, which helps to improve contrast by reducing stray light when the LED is off. The light source itself is an InGaN-based green chip. All critical dimensions are provided in millimeters, with a standard tolerance of ±0.1mm unless otherwise specified on the detailed mechanical drawing included in the datasheet.

3. Technical Specifications and Characteristics

3.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. They are specified at an ambient temperature (Ta) of 25°C. The maximum continuous DC forward current (IF) is 10mA. A higher peak forward current of 40mA is permissible under pulsed conditions (1/10 duty cycle, 0.1ms pulse width). The maximum power dissipation is 38mW. The device can withstand an electrostatic discharge (ESD) threshold of 2000V using the Human Body Model (HBM). The allowable operating temperature range is from -20°C to +80°C, while the storage temperature range is wider, from -30°C to +100°C. The LED can endure infrared reflow soldering at a peak temperature of 260°C for a maximum of 10 seconds.

3.2 Suggested IR Reflow Profile for Pb-Free Process

A recommended reflow soldering profile is provided to ensure reliable solder joints without damaging the LED. The profile typically includes a pre-heat stage, a thermal soak, a reflow zone with a peak temperature, and a cooling period. Adherence to the specified time and temperature limits, particularly the 260°C peak for 10 seconds, is crucial for maintaining device integrity.

3.3 Electrical and Optical Characteristics

These are the typical performance parameters measured at Ta=25°C and a forward current (IF) of 5mA, unless stated otherwise.

• Luminous Intensity (Iv): Ranges from a minimum of 45.0 millicandelas (mcd) to a maximum of 180.0 mcd. The typical value falls within this range. Measurement follows the CIE eye-response curve.
• Viewing Angle (2θ½): 50 degrees. This is the full angle at which the luminous intensity is half the value measured on the central axis.
• Peak Emission Wavelength (λP): Typically 534.0 nanometers (nm).
• Dominant Wavelength (λd): Ranges from 520.0 nm to 535.0 nm. This single wavelength best represents the perceived color of the LED.
• Spectral Line Half-Width (Δλ): Typically 35 nm. This indicates the spectral purity of the emitted light.
• Forward Voltage (VF): Ranges from 2.50 Volts to 3.10 Volts at IF=5mA.
• Reverse Current (IR): Maximum of 10 microamperes (µA) when a reverse voltage (VR) of 5V is applied. Note: The device is not designed for operation in reverse bias.

4. Binning and Classification System

To ensure consistency in application, LEDs are sorted into bins based on key parameters. This allows designers to select components that meet specific circuit or aesthetic requirements.

4.1 Forward Voltage (VF) Binning

Bins are defined for the forward voltage drop at IF=5mA. Code E2 covers 2.5V to 2.7V, E3 covers 2.7V to 2.9V, and E4 covers 2.9V to 3.1V. A tolerance of ±0.1V applies within each bin.

4.2 Luminous Intensity (Iv) Binning

Bins are defined for light output at IF=5mA. Code P covers 45.0 to 71.0 mcd, Q covers 71.0 to 112.0 mcd, and R covers 112.0 to 180.0 mcd. A tolerance of ±15% applies within each bin.

4.3 Dominant Wavelength (Hue) Binning

Bins are defined for the color point (dominant wavelength). Code AP covers 520.0 to 525.0 nm, AQ covers 525.0 to 530.0 nm, and AR covers 530.0 to 535.0 nm. A tolerance of ±1nm applies within each bin.

5. Typical Performance Curves and Graphical Data

The datasheet includes several characteristic curves plotted at 25°C ambient temperature. These graphs provide visual insight into device behavior under varying conditions. Typical curves include the relationship between forward voltage and forward current (V-I curve), the variation of luminous intensity with forward current, the effect of ambient temperature on luminous intensity, and the relative spectral power distribution showing the peak wavelength and spectral width. Analyzing these curves is essential for circuit design, such as selecting appropriate current-limiting resistors and understanding performance under different thermal conditions.

6. User Guide and Handling Instructions

6.1 Cleaning Procedures

Unspecified chemical cleaners should be avoided as they may damage the LED package. If cleaning is necessary after soldering or due to contamination, the recommended method is to immerse the LEDs in ethyl alcohol or isopropyl alcohol at room temperature for less than one minute. The components should be thoroughly dried afterward.

6.2 Recommended PCB Land Pattern

A detailed drawing of the suggested solder pad layout on the printed circuit board is provided. Following this pattern ensures proper solder fillet formation, good mechanical adhesion, and correct alignment during the reflow process. The design accounts for the component's dimensions and promotes reliable electrical connection.

6.3 Tape and Reel Packaging Specifications

The LEDs are supplied in embossed carrier tape with a protective cover tape, wound onto 7-inch (178mm) diameter reels. Standard reel quantity is 4000 pieces. Detailed dimensions for the tape pocket, pitch, and reel hub are specified to ensure compatibility with automated assembly equipment. The packaging conforms to ANSI/EIA-481 standards.

7. Important Cautions and Application Notes

7.1 Intended Application and Reliability

This LED is designed for use in standard electronic equipment. For applications requiring exceptional reliability or where failure could risk life or health (e.g., aviation, medical devices, safety systems), a dedicated technical consultation is mandatory prior to design-in to assess suitability and potential need for additional screening or qualifications.

7.2 Storage Conditions and Moisture Sensitivity

Proper storage is critical to prevent moisture absorption, which can cause \"popcorning\" or delamination during reflow soldering. Unopened, moisture-barrier bags should be stored at ≤30°C and ≤90% RH, with the components used within one year. Once the original bag is opened, the LEDs are rated at Moisture Sensitivity Level (MSL) 3. This means they must be subjected to IR reflow soldering within 168 hours (7 days) of exposure to an environment of ≤30°C/60% RH. For storage beyond this period outside the original bag, they should be kept in a sealed container with desiccant. Components exceeding the 168-hour floor life require a baking process (approximately 60°C for at least 20 hours) to remove moisture before soldering.

7.3 Soldering Guidelines

Two soldering methods are addressed. For reflow soldering, the profile should limit pre-heat to 150-200°C, with a maximum pre-heat time of 120 seconds. The peak temperature must not exceed 260°C, and the time above this temperature should be limited to a maximum of 10 seconds. Reflow should be performed a maximum of two times. For hand soldering with an iron, the tip temperature should not exceed 300°C, and contact time should be limited to 3 seconds per solder joint, ideally in a single operation. It is emphasized that the optimal reflow profile depends on the specific PCB design, components, and solder paste used, and should be characterized accordingly.

8. Electrostatic Discharge (ESD) Precautions

LEDs are sensitive to electrostatic discharge and voltage surges. To prevent latent or catastrophic damage, strict ESD control measures must be implemented during handling and assembly. This includes the use of grounded wrist straps, anti-static gloves, and ensuring all workstations, tools, and machinery are properly grounded. The 2000V HBM rating indicates a basic level of protection, but prevention of exposure to ESD sources is always the primary strategy.

9. Design Considerations and Circuit Integration

When integrating this LED into a circuit, several factors must be calculated. A current-limiting resistor is almost always required when driving from a voltage source. Its value can be calculated using Ohm's Law: R = (V_supply - VF_LED) / IF, where VF_LED is the forward voltage of the chosen bin, and IF is the desired drive current (not to exceed 10mA DC). For example, with a 5V supply and a typical VF of 2.8V at 5mA, the resistor would be (5 - 2.8) / 0.005 = 440 Ohms. A standard 470-Ohm resistor would be a suitable choice. Designers should also consider the thermal environment, as elevated ambient temperatures will reduce light output and affect long-term reliability. Adequate spacing on the PCB can help with heat dissipation.

10. Performance Analysis and Comparison Context

The use of an InGaN chip for green emission represents standard modern technology, offering good efficiency and color stability compared to older technologies. The 0603 package is among the smallest commonly used SMD LED footprints, enabling high-density layouts. The specified luminous intensity range and viewing angle make this component well-suited for direct viewing status indicators and low-level backlighting. The detailed binning structure allows for precise selection in applications where color consistency or forward voltage matching across multiple LEDs is important, such as in multi-LED arrays or displays.

11. Frequently Asked Questions (FAQ)

Q: What is the difference between peak wavelength and dominant wavelength?
A: Peak wavelength (λP) is the single wavelength at which the emission spectrum has its maximum intensity. Dominant wavelength (λd) is derived from the color coordinates on the CIE chromaticity diagram and represents the single wavelength of a pure monochromatic light that would appear to have the same color as the LED to the human eye. λd is often more relevant for color specification.

Q: Can I drive this LED without a current-limiting resistor?
A: No. An LED is a current-driven device. Connecting it directly to a voltage source will cause excessive current to flow, rapidly exceeding the maximum ratings and destroying the component. A series resistor or constant-current driver circuit is essential.

Q: Why is the storage and handling moisture sensitivity (MSL) important?
A: Plastic SMD packages can absorb moisture from the air. During the high-temperature reflow soldering process, this trapped moisture can vaporize rapidly, creating internal pressure that can crack the package or delaminate it from the chip (\"popcorning\"). Adhering to MSL ratings and baking procedures prevents this failure mode.

Q: How do I interpret the bin codes when ordering?
A: The full product specification is defined by a combination of bins for VF, Iv, and Hue (e.g., E3-Q-AP). For consistent results in a production run, it is advisable to specify the required bin codes or a permissible range when placing orders.

12. Technology Overview and Trends

This LED utilizes InGaN semiconductor material, which is the standard for producing high-brightness blue, green, and white LEDs. The trend in SMD LEDs continues toward higher efficiency (more light output per electrical watt), smaller package sizes for increased design flexibility, and improved color rendering and consistency. Manufacturing processes focus on tighter binning tolerances and enhanced reliability to meet the demands of automotive, industrial, and consumer applications. The move to lead-free (Pb-free) soldering, as addressed in this datasheet, is now a universal industry standard driven by environmental regulations.