SMD LED LTST-M140KRKT Datasheet - AlInGaP Red - 120° Viewing Angle - 2.0V Typ - 30mA Max - English Technical Document

1. Product Overview

This document provides the complete technical specifications for the LTST-M140KRKT, a surface-mount device (SMD) light-emitting diode (LED). This component belongs to a family of LEDs designed in miniature sizes and special configurations to facilitate automated printed circuit board (PCB) assembly. Its compact form factor makes it particularly suitable for space-constrained applications across a broad spectrum of electronic equipment.

1.1 Features

• Compliant with RoHS (Restriction of Hazardous Substances) directives.
• Packaged on 12mm tape wound onto 7-inch diameter reels for automated handling.
• Standard EIA (Electronic Industries Alliance) package outline.
• Input/output characteristics are compatible with integrated circuit (IC) logic levels.
• Designed for compatibility with standard automatic pick-and-place assembly equipment.
• Withstands infrared (IR) reflow soldering processes commonly used in surface-mount technology (SMT).
• Preconditioned to accelerate to JEDEC (Joint Electron Device Engineering Council) moisture sensitivity Level 3.

1.2 Applications

The device is intended for use in a wide variety of electronic equipment where a reliable, compact indicator or light source is required. Typical application fields include:

• Telecommunication equipment (e.g., cordless phones, cellular phones).
• Office automation devices (e.g., notebook computers, network systems).
• Home appliances and consumer electronics.
• Industrial control and instrumentation equipment.
• Status and power indicators.
• Signal and symbol illumination.
• Front panel and display backlighting.

2. Package Dimensions and Mechanical Information

The LED is provided in a surface-mount package. The lens color is water clear, and the light source material is Aluminum Indium Gallium Phosphide (AlInGaP), which emits red light. All dimensional specifications are provided in millimeters (mm). The general tolerance for dimensions is ±0.2 mm unless a specific note indicates otherwise. Detailed dimensional drawings for the component itself, as well as for the recommended PCB attachment pad layout, are included in the datasheet to ensure proper footprint design for reliable soldering.

3. Ratings and Characteristics

All ratings are specified at an ambient temperature (Ta) of 25°C. Exceeding these limits may cause permanent damage to the device.

3.1 Absolute Maximum Ratings

• Power Dissipation (Pd): 72 mW
• Peak Forward Current (IFP): 80 mA (under pulsed conditions: 1/10 duty cycle, 0.1ms pulse width)
• Continuous Forward Current (IF): 30 mA (DC)
• Reverse Voltage (VR): 5 V
• Operating Temperature Range: -40°C to +85°C
• Storage Temperature Range: -40°C to +100°C

3.2 Electrical and Optical Characteristics

The following parameters are measured at Ta=25°C with a forward current (IF) of 20 mA, unless stated otherwise.

• Luminous Flux (Φv): Typical value is provided; minimum and maximum values are defined by the bin rank (see Section 4). Measured with a filter approximating the CIE photopic eye-response curve.
• Luminous Intensity (Iv): Typical value is provided; minimum and maximum values are defined by the bin rank. This is a derived value for reference.
• Viewing Angle (2θ1/2): 120 degrees (typical). This is the full angle at which the luminous intensity is half the value measured on the central axis.
• Peak Emission Wavelength (λP): 639 nm (typical). The wavelength at which the spectral radiant intensity is maximum.
• Dominant Wavelength (λd): 631 nm (typical). The single wavelength that defines the perceived color on the CIE chromaticity diagram. Tolerance is ±1 nm.
• Spectral Line Half-Width (Δλ): 20 nm (typical). The spectral width measured at half the maximum intensity.
• Forward Voltage (VF): 2.0 V (typical), 2.4 V (maximum) at IF=20mA. Tolerance is ±0.1 V.
• Reverse Current (IR): 10 μA (maximum) at VR=5V.

3.3 Soldering Profile

A suggested infrared (IR) reflow soldering profile is provided for lead-free (Pb-free) assembly processes, compliant with the J-STD-020B standard. The profile includes pre-heat, soak, reflow, and cooling stages with specific time and temperature constraints, with a peak package body temperature not exceeding 260°C. Adherence to such profiles is critical to prevent thermal damage to the LED package during assembly.

4. Bin Rank System

To ensure consistency in luminous output, the LEDs are sorted into bins based on their measured luminous flux. The bin code defines a specific range. For the LTST-M140KRKT (Red color, tested at 20mA), the defined bins are:

• B2: Luminous Flux 0.27 - 0.34 lm (Intensity 90 - 112 mcd)
• C1: Luminous Flux 0.34 - 0.42 lm (Intensity 112 - 140 mcd)
• C2: Luminous Flux 0.42 - 0.54 lm (Intensity 140 - 180 mcd)
• D1: Luminous Flux 0.54 - 0.67 lm (Intensity 180 - 224 mcd)
• D2: Luminous Flux 0.67 - 0.84 lm (Intensity 224 - 280 mcd)

The tolerance on each intensity bin is ±11%. The luminous intensity value (mcd) is provided for reference purposes. Designers should specify the required bin code when ordering to guarantee the necessary brightness level for their application.

5. Typical Performance Curves

The datasheet includes graphical representations of key characteristics to aid in design analysis. These curves, typically plotted against forward current or ambient temperature, provide insight into device behavior under non-standard conditions. Common curves include:

• Relative Luminous Intensity vs. Forward Current: Shows how light output increases with current, up to the maximum rating.
• Forward Voltage vs. Forward Current: Illustrates the diode's IV characteristic.
• Relative Luminous Intensity vs. Ambient Temperature: Demonstrates the thermal derating of light output, which is crucial for high-temperature applications.
• Spectral Distribution: A plot of relative intensity versus wavelength, showing the peak at ~639nm and the spectral width.
• Viewing Angle Pattern: A polar diagram showing the angular distribution of luminous intensity.

6. User Guide and Handling Instructions

6.1 Cleaning

If cleaning after soldering is necessary, only use specified solvents. Immersing the LED in ethyl alcohol or isopropyl alcohol at room temperature for less than one minute is acceptable. The use of unspecified or aggressive chemical cleaners can damage the plastic package and lens.

6.2 Storage and Moisture Sensitivity

This component is moisture-sensitive. When the sealed moisture-proof bag (with desiccant) is unopened, LEDs should be stored at ≤30°C and ≤70% RH and used within one year. Once the original packaging is opened, the storage environment must not exceed 30°C and 60% RH. Components exposed to ambient air should be subjected to IR reflow soldering within 168 hours (JEDEC Level 3). For storage beyond this period, they must be stored in a sealed container with desiccant or in a nitrogen ambient. LEDs stored out of packaging for more than 168 hours require baking at approximately 60°C for at least 48 hours prior to solder assembly to remove absorbed moisture and prevent \"popcorning\" during reflow.

6.3 Soldering Recommendations

Two primary soldering methods are supported:

Reflow Soldering (Recommended):
- Pre-heat temperature: 150-200°C
- Pre-heat time: 120 seconds maximum
- Peak temperature: 260°C maximum (package body)
- Time above liquidus: 10 seconds maximum
- Number of reflow cycles: Maximum two times

Hand Soldering (Soldering Iron):
- Iron tip temperature: 300°C maximum
- Soldering time per lead: 3 seconds maximum
- Number of soldering cycles: One time only

It is critical to note that the optimal reflow profile depends on the specific PCB design, solder paste, and oven used. The provided profile serves as a guideline based on JEDEC standards.

6.4 Drive Circuit Design

An LED is a current-operated device. Its light output is primarily a function of forward current, not voltage. To ensure consistent brightness and prevent damage, the drive circuit must include a current-limiting mechanism. When connecting multiple LEDs in parallel, it is strongly recommended to use an individual current-limiting resistor in series with each LED. This practice compensates for minor variations in the forward voltage (VF) of individual devices, ensuring uniform current distribution and, consequently, uniform luminous intensity across all LEDs in the array. Driving LEDs directly from a voltage source without current regulation is not recommended, as it can lead to thermal runaway and device failure.

7. Packaging and Tape & Reel Specifications

The LEDs are supplied in a tape-and-reel format compatible with high-speed automated assembly equipment. Key packaging details include:

• Tape width: 12 mm.
• Reel diameter: 7 inches.
• Quantity per full reel: 3000 pieces.
• Minimum order quantity for remnants: 500 pieces.
• The packaging conforms to ANSI/EIA-481 specifications.
• Empty pockets in the carrier tape are sealed with a top cover tape.
• A maximum of two consecutive missing components is allowed per reel.

Detailed dimensional drawings for the carrier tape, cover tape, and reel are provided to ensure compatibility with feeder systems.

8. Application Notes and Cautions

8.1 Intended Use

This LED is designed for use in standard electronic equipment for general purposes, such as consumer electronics, office equipment, and home appliances. It is not specifically designed or qualified for applications where failure could lead to direct jeopardy of life, health, or safety without prior consultation and additional qualification. Such applications include, but are not limited to, aviation, transportation, traffic control, medical/life-support systems, and critical safety devices.

8.2 Thermal Management

While the package has a specified power dissipation, effective thermal management at the PCB level is essential for maintaining performance and longevity, especially when operating at high ambient temperatures or near maximum current. The PCB layout should provide adequate copper area around the solder pads to act as a heat sink, dissipating heat away from the LED junction.

8.3 Optical Design Considerations

The 120-degree viewing angle provides a wide, diffuse emission pattern suitable for status indicators and backlighting where wide-angle visibility is desired. For applications requiring a more focused beam, secondary optics (e.g., lenses or reflectors) would be necessary. The water-clear lens minimizes light absorption, maximizing the output from the AlInGaP chip.

9. Technology and Material Overview

The LTST-M140KRKT utilizes an Aluminum Indium Gallium Phosphide (AlInGaP) semiconductor material for its light-emitting region. AlInGaP technology is particularly well-suited for producing high-efficiency red, orange, and amber LEDs. Compared to older technologies like Gallium Arsenide Phosphide (GaAsP), AlInGaP offers significantly higher luminous efficacy, better temperature stability, and longer operational lifetime. The light is generated through electroluminescence, where electrons recombine with holes within the semiconductor's active region, releasing energy in the form of photons. The specific composition of the AlInGaP layers is engineered to produce photons at the target dominant wavelength of 631 nm, which is perceived as red light by the human eye.