SMD LED LTSA-S020ZWETA Datasheet - White Source Yellow Lens - 30mA - 100mW - English Technical Document

1. Product Overview

This document details the specifications for the LTSA-S020ZWETA, a surface-mount device (SMD) light-emitting diode (LED). This component is designed for automated printed circuit board (PCB) assembly processes and is suitable for space-constrained applications across various electronic equipment segments.

1.1 Features

• Compliant with RoHS (Restriction of Hazardous Substances) directives.
• Packaged in 12mm tape on 7-inch diameter reels for automated handling.
• Preconditioned to JEDEC Moisture Sensitivity Level (MSL) 2a.
• Qualification referenced to AEC-Q101 Rev D, a standard for discrete semiconductor components.
• Standard EIA (Electronic Industries Alliance) package outline.
• Integrated circuit (I.C.) compatible drive levels.
• Compatible with standard automatic pick-and-place equipment.
• Suitable for infrared (IR) reflow soldering processes.

1.2 Applications

This LED is intended for use in a wide variety of electronic equipment. The datasheet specifically mentions applications in engineering vehicles for accessory functions. Its general characteristics make it suitable for consumer electronics, indicators, and backlighting where a white light source with a yellow-tinted output is desired.

2. Technical Parameters: In-Depth Objective Interpretation

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. Operation under these conditions is not guaranteed.

• Power Dissipation (Pd): 100 mW. This is the maximum power the package can dissipate as heat.
• Peak Forward Current (I_F(PEAK)): 50 mA. This is the maximum instantaneous current, typically specified under pulsed conditions (1/10 duty cycle, 0.1ms pulse width) to manage thermal stress.
• DC Forward Current (I_F): 30 mA. This is the maximum continuous forward current for reliable operation.
• Operating Temperature Range (T_opr): -40°C to +100°C. The ambient temperature range over which the device is designed to function.
• Storage Temperature Range (T_stg): -40°C to +100°C. The temperature range for non-operational storage.

2.2 Electrical and Optical Characteristics

These parameters are measured at a standard ambient temperature of 25°C and define the typical performance of the device.

• Luminous Intensity (I_V): 180 - 450 mcd (millicandela) at a test current (I_F) of 2 mA. This measures the perceived brightness in a specific direction. The wide range indicates a binning system is used (see Section 3).
• Viewing Angle (2θ_1/2): 120 degrees (typical). This is the full angle at which the luminous intensity drops to half of its axial (on-axis) value, indicating a wide viewing pattern.
• Chromaticity Coordinates (x, y): x=0.3197, y=0.3131 at I_F=2 mA. These CIE 1931 coordinates define the color point of the white light on a chromaticity diagram.
• Forward Voltage (V_F): 2.25 - 2.95 V at I_F=2 mA. The voltage drop across the LED when conducting current. A binning system is also applied here.
• Reverse Voltage (V_Z): 6 - 8 V at I_Z=10 mA. This is the Zener or breakdown voltage. Important: The device is not designed for reverse operation; this parameter is for IR test purposes only.
• Reverse Current (I_R): 10 μA (max) at V_R=5V. The small leakage current when a reverse bias is applied.
• ESD Withstand Voltage: 2000 V (Human Body Model). This indicates a moderate level of electrostatic discharge protection.

3. Binning System Explanation

To ensure consistency in production, LEDs are sorted (binned) based on key parameters. The LTSA-S020ZWETA uses a three-code system: Vf / Iv / Color (e.g., E3 / S2 / LL).

3.1 Forward Voltage (Vf) Binning

LEDs are categorized into bins (E1 to E7) based on their forward voltage at 2 mA. Each bin has a range of 0.1V, with an overall tolerance of ±0.1V per bin. For example, bin E3 covers Vf from 2.45V to 2.55V.

3.2 Luminous Intensity (Iv) Binning

LEDs are sorted into bins (S1, S2, T1, T2) based on their brightness at 2 mA. The bins represent increasing intensity levels, with bin T2 offering the highest output (355-450 mcd). Tolerance on each bin is ±11%.

3.3 Color (Chromaticity) Binning

This is the most complex binning parameter. LEDs are sorted based on their CIE (x, y) chromaticity coordinates measured at 2 mA. The datasheet provides a detailed table with bin codes (e.g., JL, JK, KL, LL, LK, ML, MK, NL, NK, OL, OK, PL, PK) defined by quadrilateral regions on the chromaticity diagram. Each region is specified by four (x, y) coordinate points. The tolerance for hue (x, y) within a bin is ±0.01. A chromaticity diagram graphic is typically included to visualize these bins.

4. Performance Curve Analysis

The datasheet includes typical characteristic curves to aid in design understanding.

4.1 Spatial Distribution

A polar diagram (Fig. 2) illustrates the spatial radiation pattern of the LED. The 120-degree viewing angle is confirmed by this curve, showing how light intensity varies with the angle from the central axis. This is crucial for applications requiring specific illumination patterns.

5. Mechanical and Package Information

5.1 Package Dimensions

The LED conforms to a standard SMD package outline. Key dimensions include the body size, lead spacing, and overall height. All dimensions are provided in millimeters with a typical tolerance of ±0.2 mm unless otherwise noted. The lens color is yellow, while the light source chip material is InGaN, producing white light.

5.2 Recommended PCB Attachment Pad

A footprint diagram is provided showing the recommended copper pad layout on the PCB for reliable soldering. This includes pad size, shape, and spacing to ensure proper solder joint formation during reflow and good mechanical adhesion.

6. Soldering and Assembly Guidelines

6.1 IR Reflow Soldering Profile

A suggested infrared reflow profile is provided for lead-free (Pb-free) solder processes, aligned with the J-STD-020 standard. This profile defines the critical parameters for the reflow oven: preheat temperature and time, temperature ramp-up rate, peak temperature, time above liquidus (TAL), and cooling rate. Adhering to this profile is essential to prevent thermal damage to the LED package.

6.2 Cleaning

If cleaning after soldering is necessary, only specified chemicals should be used. The datasheet recommends immersion in ethyl alcohol or isopropyl alcohol at normal temperature for less than one minute. Unspecified chemicals may damage the LED package material.

6.3 Storage Conditions

• Sealed Package: Store at ≤30°C and ≤70% Relative Humidity (RH). The product has a shelf life of one year when stored in its original moisture-proof bag with desiccant.
• Opened Package: For components removed from their original packaging, the storage ambient should not exceed 30°C and 60% RH. It is strongly recommended that these "floor life" components undergo IR reflow soldering within 168 hours (7 days) of exposure to avoid moisture-induced damage ("popcorning") during reflow.

7. Packaging and Ordering Information

7.1 Tape and Reel Specifications

The LEDs are supplied in industry-standard embossed carrier tape.

• Tape Width: 12 mm.
• Reel Diameter: 7 inches.
• Quantity per Reel: 2000 pieces.
• Minimum Packing Quantity: 500 pieces for remainder quantities.
• The packaging conforms to EIA-481-1-B specifications. The tape is sealed with a cover tape, and there is a maximum allowance of two consecutive missing components.

8. Application Suggestions

8.1 Typical Application Scenarios

This LED is suitable for general indicator lights, status displays, and backlighting in consumer and industrial electronics. Its specific mention in engineering vehicle accessories suggests use in dashboard indicators, control panel backlighting, or exterior accessory lighting where a yellow-tinted white light is desired for aesthetics or specific functional requirements.

8.2 Design Considerations

• Current Limiting: Always use a series current-limiting resistor or a constant-current driver circuit. Do not connect directly to a voltage source. The maximum continuous DC current is 30 mA.
• Thermal Management: While the power dissipation is low (100mW max), ensuring adequate PCB copper area or thermal vias can help maintain lower junction temperatures, promoting longevity and stable light output.
• ESD Precautions: Although rated for 2kV HBM, standard ESD handling precautions should be observed during assembly.
• Optical Design: The 120-degree viewing angle provides wide dispersion. For focused light, secondary optics (lenses, light guides) would be required.

9. Cautions and Reliability Notes

The LEDs described are intended for ordinary electronic equipment. For applications requiring exceptional reliability where failure could jeopardize life or health (e.g., aviation, medical devices, transportation safety systems), specific consultation and qualification beyond this standard datasheet are mandatory. The device is not designed for reverse voltage operation in the application circuit.

10. Technical Comparison and Positioning

This LED positions itself as a general-purpose, cost-effective SMD component. Key differentiators include its specific white-with-yellow-lens color combination, qualification reference to AEC-Q101 (common in automotive contexts), and preconditioning to MSL 2a for improved moisture resistance during soldering. Compared to ultra-high-brightness or narrow-angle LEDs, it offers a balanced combination of adequate brightness, very wide viewing angle, and standard reliability features suitable for volume commercial applications.

11. Frequently Asked Questions (Based on Technical Parameters)

Q: What is the difference between the lens color and source color?
A: The source color (White, from an InGaN chip) is the light generated internally. The yellow lens acts as a filter/encapsulant, tinting the final emitted light, resulting in a warm white or yellowish-white appearance.

Q: How do I select the right bin for my application?
A: For applications where color consistency is critical (e.g., multi-LED arrays), specify a tight color bin (e.g., LL) and potentially a tight Vf bin. For single indicators where absolute brightness is key, specify a higher Iv bin (T1 or T2). Your distributor can provide bins available in stock.

Q: Can I drive this LED at 30mA continuously?
A: Yes, 30mA is the maximum rated continuous DC current. However, for optimal longevity and to account for ambient temperature rises, driving at a lower current (e.g., 20mA) is often recommended and will still provide sufficient brightness for many applications.

Q: Why is the storage condition after opening the bag so strict (168 hours)?
A> SMD packages can absorb moisture from the air. During the high-temperature reflow soldering process, this trapped moisture can vaporize rapidly, causing internal delamination or cracking ("popcorning"). The 168-hour floor life is the maximum safe exposure time for MSL 2a rated components before they must be re-baked to remove moisture.

12. Practical Design and Usage Case

Scenario: Designing a status indicator panel for an industrial controller. The panel requires multiple LEDs to show power, fault, and standby status. The designer chooses the LTSA-S020ZWETA for its wide viewing angle, ensuring visibility from various angles in the control room. To ensure uniform brightness and color across all indicators, the designer specifies a single luminous intensity bin (e.g., T2) and a single color bin (e.g., LL) in the bill of materials (BOM). A constant current of 20mA is chosen for each LED, using a simple resistor calculated from the typical Vf (from the chosen Vf bin, e.g., E3's 2.5V) and the supply voltage. The PCB layout follows the recommended pad footprint, and the assembly house uses the provided lead-free IR reflow profile. Components are used within the 168-hour floor life after bag opening.

13. Operating Principle Introduction

Light Emitting Diodes (LEDs) are semiconductor devices that emit light when an electric current passes through them. This phenomenon is called electroluminescence. In the LTSA-S020ZWETA, the active region is made of Indium Gallium Nitride (InGaN) materials, which are engineered to emit photons in the blue/ultraviolet spectrum. A phosphor layer within the package absorbs a portion of this primary light and re-emits it as yellow light. The combination of the remaining blue light and the converted yellow light results in the perception of white light. The external yellow-tinted epoxy lens further modifies the color temperature and provides environmental protection and mechanical shaping of the light beam.

14. Technology Trends

The optoelectronics industry continues to advance in several key areas relevant to such components: increased luminous efficacy (more light output per watt of electrical input), improved color rendering index (CRI) for white LEDs, and higher reliability under harsh environmental conditions (higher temperature, humidity). Packaging trends include miniaturization, improved thermal management substrates, and more precise optical control integrated into the package. Furthermore, there is a strong drive towards higher levels of standardization in testing, binning, and reliability qualification (like AEC-Q101) to meet the demands of automotive and industrial markets.