Orange SMD LED LTST-M670KFKT Datasheet - AlInGaP - 120° Viewing Angle - 20mA - English Technical Document

1. Product Overview

This document provides the complete technical specifications for a surface-mount device (SMD) light-emitting diode (LED). The device is an orange LED utilizing an Aluminum Indium Gallium Phosphide (AlInGaP) semiconductor material as the light source, housed in a water-clear lens package. It is designed for automated assembly processes and is compatible with infrared reflow soldering techniques, making it suitable for high-volume manufacturing on printed circuit boards (PCBs). The product is compliant with RoHS (Restriction of Hazardous Substances) directives, classifying it as a green product.

1.1 Core Advantages and Target Market

The primary advantages of this LED include its compatibility with automated pick-and-place equipment, which streamlines production, and its qualification for lead-free infrared reflow soldering profiles, aligning with modern environmental and manufacturing standards. Its EIA (Electronic Industries Alliance) standard package ensures mechanical compatibility with industry-standard placement systems. The device is also described as I.C. (Integrated Circuit) compatible, indicating its drive characteristics are suitable for direct interfacing with typical logic-level outputs. The target applications are broad, encompassing general electronic equipment where reliable indicator lighting is required.

2. Technical Parameter Deep Dive

2.1 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.

• Power Dissipation (Pd): 72 mW. This is the maximum amount of power the device can dissipate as heat without exceeding its thermal limits.
• Peak Forward Current (IFP): 80 mA. This is the maximum allowable instantaneous forward current, typically specified under pulsed conditions (1/10 duty cycle, 0.1ms pulse width) to prevent overheating.
• DC Forward Current (IF): 30 mA. This is the maximum continuous forward current that can be applied to the LED under steady-state conditions.
• Reverse Voltage (VR): 5 V. Applying a voltage exceeding this value in the reverse direction can cause breakdown and damage the LED junction.
• Operating Temperature Range: -40°C to +85°C. The ambient temperature range over which the device is guaranteed to operate within its specified parameters.
• Storage Temperature Range: -40°C to +100°C. The temperature range for safe storage when the device is not powered.

2.2 Electrical and Optical Characteristics

These are the typical performance parameters measured at Ta=25°C and a test current (IF) of 20 mA, unless otherwise noted.

• Luminous Intensity (Iv): Ranges from a minimum of 140 mcd to a typical maximum of 450 mcd. This measures the perceived brightness of the LED as seen by the human eye, using a filter that approximates the CIE photopic response curve.
• Viewing Angle (2θ1/2): 120 degrees. This is the full angle at which the luminous intensity drops to half of its value measured on the central axis (0°). A 120° angle indicates a wide viewing pattern.
• Peak Emission Wavelength (λP): 611 nm. This is the wavelength at which the spectral power output of the LED is at its maximum.
• Dominant Wavelength (λd): Ranges from 600 nm to 612 nm. This is derived from the CIE chromaticity diagram and represents the single wavelength that best describes the perceived color of the light. It is the key parameter for color specification.
• Spectral Line Half-Width (Δλ): 17 nm. This is the width of the emission spectrum at half of its maximum power (Full Width at Half Maximum - FWHM). A value of 17nm is typical for an AlInGaP orange LED, indicating a relatively pure color.
• Forward Voltage (VF): Ranges from 1.8 V to 2.4 V at IF=20mA. This is the voltage drop across the LED when it is conducting current.
• Reverse Current (IR): Maximum of 10 μA at VR=5V. This is the small leakage current that flows when the specified reverse voltage is applied.

3. Binning System Explanation

To ensure consistency in production, LEDs are sorted into bins based on key parameters. This allows designers to select parts that meet specific requirements for color and electrical performance.

3.1 Forward Voltage Binning (Unit: V @20mA)

LEDs are categorized by their forward voltage drop:
Bin Code D2: 1.8V (Min) to 2.0V (Max)
Bin Code D3: 2.0V (Min) to 2.2V (Max)
Bin Code D4: 2.2V (Min) to 2.4V (Max)
Tolerance on each bin is +/-0.1V.

3.2 Luminous Intensity Binning (Unit: mcd @20mA)

LEDs are sorted by their brightness output:
Bin Code R2: 140.0 to 180.0 mcd
Bin Code S1: 180.0 to 224.0 mcd
Bin Code S2: 224.0 to 280.0 mcd
Bin Code T1: 280.0 to 355.0 mcd
Bin Code T2: 355.0 to 450.0 mcd
Tolerance on each bin is +/-11%.

3.3 Dominant Wavelength Binning (Unit: nm @20mA)

LEDs are classified by their precise color (dominant wavelength):
Bin Code P: 600.0 to 603.0 nm
Bin Code Q: 603.0 to 606.0 nm
Bin Code R: 606.0 to 609.0 nm
Bin Code S: 609.0 to 612.0 nm
Tolerance for each bin is +/- 1nm.

4. Performance Curve Analysis

The datasheet references typical characteristic curves which are essential for understanding device behavior under different conditions. While the specific graphs are not reproduced in text, their implications are analyzed below.

4.1 Forward Current vs. Forward Voltage (I-V Curve)

The I-V curve for an LED is exponential. For the specified forward voltage range of 1.8V to 2.4V at 20mA, designers can expect the operating point to fall within this window. The curve helps in selecting appropriate current-limiting resistors and understanding the voltage requirements of the drive circuit.

4.2 Luminous Intensity vs. Forward Current

This curve typically shows that luminous intensity increases with forward current, but not necessarily in a linear fashion, especially as the current approaches the maximum rating. It is crucial for determining the drive current needed to achieve a desired brightness level.

4.3 Temperature Characteristics

LED performance is temperature-dependent. Typically, forward voltage decreases with increasing junction temperature, while luminous intensity also decreases. Understanding these curves is vital for applications operating over the full -40°C to +85°C range to ensure consistent performance.

4.4 Spectral Distribution

The spectral output curve shows the intensity of light emitted across different wavelengths, centered around the peak wavelength of 611nm with a half-width of 17nm. This defines the color purity of the orange light.

5. Mechanical and Packaging Information

5.1 Device Package Dimensions

The LED is supplied in a standard SMD package. The datasheet includes a detailed dimensional drawing with all critical measurements in millimeters (and inches). Key dimensions include the body length, width, height, lead spacing, and pad recommendations. Tolerances are typically ±0.2mm unless otherwise specified. This information is critical for PCB land pattern design.

5.2 Polarity Identification

SMD LEDs must be oriented correctly on the PCB. The datasheet drawing indicates the cathode (negative) and anode (positive) terminals, often through a marking on the package body or an asymmetrical feature.

5.3 Tape and Reel Packaging

For automated assembly, the LEDs are supplied on embossed carrier tape and reels.
Tape Dimensions: The tape width, pocket dimensions, and cover tape specifications are provided to ensure compatibility with feeders.
Reel Specifications: The LEDs are packaged on 7-inch (178mm) diameter reels. Each reel contains 2000 pieces. The minimum packing quantity for remainder parts is 500 pieces. The packaging conforms to ANSI/EIA-481 specifications. Notes specify that empty pockets are sealed and a maximum of two consecutive missing components are allowed.

6. Soldering and Assembly Guidelines

6.1 Infrared Reflow Soldering Profile

The device is compatible with infrared reflow soldering processes. A suggested profile compliant with J-STD-020B for lead-free soldering is provided. Key parameters of this profile include:
Pre-heat: 150-200°C.
Pre-heat Time: Maximum 120 seconds.
Peak Temperature: Maximum 260°C.
Time Above Liquidus: Critical for proper solder joint formation (specific time referenced from the profile curve on page 3).
The profile is a generic target; final board-level profiles should be characterized based on the specific PCB design, solder paste, and oven used.

6.2 Hand Soldering (Soldering Iron)

If hand soldering is necessary, the following limits apply:
Iron Temperature: Maximum 300°C.
Soldering Time: Maximum 3 seconds per joint.
Hand soldering should be performed only once to avoid thermal stress.

6.3 Cleaning

If cleaning after soldering is required, only specified solvents should be used. Immersing the LED in ethyl alcohol or isopropyl alcohol at normal temperature for less than one minute is recommended. Unspecified chemicals may damage the package.

6.4 Storage Conditions

Proper storage is essential to maintain solderability, especially for moisture-sensitive components.
Sealed Package: Store at ≤30°C and ≤70% Relative Humidity (RH). The shelf life is one year when stored in the original moisture-proof bag with desiccant.
Opened Package: For components removed from their sealed bag, the storage ambient should not exceed 30°C and 60% RH. It is recommended to complete IR reflow soldering within 168 hours (7 days) of exposure. For longer storage, components should be kept in a sealed container with desiccant or in a nitrogen desiccator. Components exposed for more than 168 hours should be baked at approximately 60°C for at least 48 hours before assembly to remove absorbed moisture and prevent \"popcorning\" during reflow.

7. Application Suggestions and Design Considerations

7.1 Typical Application Circuits

LEDs are current-driven devices. The most common drive method is to use a series current-limiting resistor. The resistor value (R) is calculated using Ohm's Law: R = (Vcc - VF) / IF, where Vcc is the supply voltage, VF is the LED forward voltage (use max value from bin or datasheet for reliability), and IF is the desired forward current (e.g., 20mA). For multiple LEDs, connecting them in series ensures identical current through each, promoting uniform brightness. Parallel connection is not recommended without individual resistors, as slight variations in VF can cause significant current imbalance.

7.2 PCB Pad Design (Land Pattern)

The datasheet provides a recommended pad layout for infrared or vapor phase reflow soldering. Following this recommendation is crucial for achieving reliable solder joints, proper alignment, and minimizing tombstoning. The pad design accounts for thermal mass and solder volume.

7.3 Thermal Management

While the power dissipation is relatively low (72mW max), proper thermal design on the PCB can help maintain lower junction temperatures, which improves luminous efficiency and long-term reliability. This may involve using thermal vias or ensuring adequate copper area connected to the LED pads.

7.4 Application Scope and Caution

The LED is intended for use in ordinary electronic equipment such as office equipment, communication devices, and household appliances. For applications requiring exceptional reliability where failure could jeopardize life or health (e.g., aviation, medical systems, safety devices), specific consultation and qualification are necessary prior to use.

8. Technical Comparison and Differentiation

This AlInGaP orange LED offers specific advantages. Compared to older technologies, AlInGaP provides higher efficiency and better color stability over time and temperature. The 120-degree viewing angle is notably wide for an SMD indicator LED, providing good visibility from off-axis positions. Its compatibility with standard IR reflow profiles for lead-free soldering makes it a modern, environmentally friendly choice suitable for contemporary manufacturing lines. The comprehensive binning structure allows for precise selection based on color and brightness needs, which is critical for applications requiring visual consistency across multiple indicators.

9. Frequently Asked Questions (Based on Technical Parameters)

Q: What current should I drive this LED at?
A: The typical test condition is 20mA, and the maximum continuous current is 30mA. For general indicator use and good longevity, driving at 20mA is standard. Always use a series current-limiting resistor.

Q: How do I interpret the luminous intensity value?
A: Luminous intensity (mcd) is a measure of brightness in a specific direction. The 140-450 mcd range at 20mA, combined with the 120° viewing angle, means it will appear bright when viewed on-axis and remain visible over a wide area.

Q: Can I use this LED outdoors?
A: The operating temperature range of -40°C to +85°C suggests it can withstand a wide range of ambient conditions. However, the package is not specifically rated for waterproofing or UV resistance. For outdoor use, additional environmental protection (conformal coating, enclosures) would be necessary.

Q: Why is the storage condition so important?
A: SMD packages can absorb moisture from the air. If a moist component is subjected to the high temperatures of reflow soldering, the rapid vaporization of the moisture can cause internal delamination or cracking (\"popcorning\"), leading to failure. Adhering to the storage and baking guidelines prevents this.

10. Practical Design and Usage Case

Scenario: Designing a status indicator panel for a network router.
The panel requires multiple orange LEDs to indicate different link and activity statuses. Uniform color and brightness are important for user experience.
Design Steps:
1. Binning Selection: Specify bins for dominant wavelength (e.g., Bin R: 606-609nm) and luminous intensity (e.g., Bin T1: 280-355 mcd) to ensure all LEDs on the panel look identical.
2. Circuit Design: The router's logic supply is 3.3V. Using the maximum VF of 2.4V (from Bin D4) and a target IF of 20mA, calculate the series resistor: R = (3.3V - 2.4V) / 0.020A = 45 Ohms. A standard 47-ohm resistor would be used.
3. PCB Layout: Use the recommended pad dimensions from the datasheet. Place the LEDs with sufficient spacing for the wide 120° viewing angle to prevent optical crosstalk.
4. Assembly: Ensure the factory follows the provided J-STD-020B reflow profile. Verify that components from opened reels are used within 168 hours or are properly baked.
5. Result: A panel with consistently bright, uniformly colored orange indicators that are clearly visible from a wide range of angles.

11. Operating Principle Introduction

Light-emitting diodes are semiconductor devices that emit light through electroluminescence. When a forward voltage is applied across the p-n junction, electrons from the n-type material recombine with holes from the p-type material in the active region. This recombination releases energy in the form of photons (light). The specific wavelength (color) of the emitted light is determined by the bandgap energy of the semiconductor material used. In this device, the AlInGaP (Aluminum Indium Gallium Phosphide) compound semiconductor has a bandgap that corresponds to orange light, with a dominant wavelength in the 600-612 nm range. The water-clear epoxy lens encapsulates the semiconductor die, provides mechanical protection, and shapes the light output to achieve the specified 120-degree viewing angle.

12. Technology Trends

The development of LED technology continues to focus on several key areas relevant to indicator LEDs like this one. Efficiency improvements (more light output per unit of electrical input) are an ongoing trend, potentially allowing for similar brightness at lower drive currents, which reduces power consumption and heat generation. Advancements in packaging materials aim to improve long-term reliability and color stability under high-temperature and high-humidity conditions. There is also a trend towards further miniaturization of packages while maintaining or improving optical performance. Furthermore, the integration of drive electronics or control features (like built-in current regulation or PWM dimming) directly into the LED package is an area of development for more advanced indicator applications, simplifying circuit design for the end user.