White LED LTW-008ZDCG Datasheet - InGaN White - 20mA - 3.6V - 120mW - English Technical Document

1. Product Overview

This document details the technical specifications for a high-brightness, white light-emitting diode (LED) designed for surface-mount technology (SMT) applications. The device utilizes an Indium Gallium Nitride (InGaN) semiconductor material to produce white light, filtered through a yellow lens. It is packaged on 8mm tape and supplied on 7-inch diameter reels, making it fully compatible with automated pick-and-place assembly equipment. The product is classified as green and is compliant with the Restriction of Hazardous Substances (RoHS) directive, indicating it is lead-free. Its primary design caters to applications requiring reliable, consistent white illumination in a compact form factor.

2. Technical Parameters Deep Objective Interpretation

2.1 Absolute Maximum Ratings

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

• Power Dissipation (Pd): 120 mW. This is the maximum amount of power the LED package can dissipate as heat without exceeding its thermal limits.
• Peak Forward Current (I_FP): 100 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 (I_F): 30 mA. This is the maximum continuous forward current recommended for reliable long-term operation.
• Reverse Voltage (V_R): 5 V. Applying a reverse voltage exceeding this value can cause breakdown and damage the LED junction. Continuous reverse voltage operation is prohibited.
• Operating Temperature Range (T_opr): -30°C to +85°C. The ambient temperature range within which the LED is designed to function correctly.
• Storage Temperature Range (T_stg): -40°C to +100°C. The temperature range for non-operational storage.
• Reflow Soldering Condition: Withstands 260°C for 10 seconds, which aligns with typical lead-free solder reflow profiles (e.g., J-STD-020D).

2.2 Electrical & Optical Characteristics

These parameters are measured at a standard test condition of Ta=25°C and I_F = 20 mA, unless otherwise noted.

• Luminous Intensity (I_V): Ranges from a minimum of 860 mcd to a typical value of 1720 mcd. This measures the perceived power of light emitted in a specific direction. The actual value is binned (see Section 3). Measurement follows the CIE eye-response curve.
• Viewing Angle (2θ_1/2): 110 degrees. This is the full angle at which the luminous intensity drops to half of its maximum value (on-axis). It indicates a relatively wide beam pattern.
• Chromaticity Coordinates (x, y): Typical values are x=0.295, y=0.280 on the CIE 1931 chromaticity diagram, defining the white point color. A tolerance of ±0.01 is applied to these coordinates.
• Forward Voltage (V_F): Ranges from 2.9V to 3.6V at 20mA. This is the voltage drop across the LED when operating. Actual values are binned (see Section 3).
• ESD Withstand Voltage: 2000V (Human Body Model, HBM). This specifies the device's sensitivity to electrostatic discharge, indicating a standard level of protection. Handling with proper ESD precautions (wrist straps, grounded equipment) is strongly recommended.

3. Binning System Explanation

To ensure color and performance consistency in production, LEDs are sorted into bins based on key parameters.

3.1 Forward Voltage (V_F) Binning

LEDs are categorized into bins (V0 to V6) based on their forward voltage at I_F = 20 mA. Each bin has a range of 0.1V, from V0 (2.9-3.0V) to V6 (3.5-3.6V). A tolerance of ±0.10V is applied within each bin. This allows designers to select LEDs with closely matched voltage drops for current-sharing applications in parallel circuits.

3.2 Luminous Intensity (I_V) Binning

LEDs are binned (S, T, A, B, C, D) according to their luminous intensity at I_F = 20 mA. The bins range from S (860-1000 mcd) to D (1580-1720 mcd). A tolerance of ±10% is specified for each bin. This enables selection for applications requiring specific brightness levels or uniformity across multiple LEDs.

3.3 Color Coordinate Binning (Color Ranks)

The document provides a detailed Color Ranks Table (e.g., A52, A53, BE1, BG3) defining specific quadrilaterals or triangles on the CIE 1931 chromaticity diagram. Each "rank" specifies the allowable (x, y) coordinate boundaries for the white light output. This precise binning is critical for applications where color consistency is paramount, such as backlighting or signage. The measurement allowance for these coordinates is ±0.01.

4. Performance Curve Analysis

4.1 Relative Intensity vs. Wavelength

Figure 1 in the datasheet shows the spectral power distribution (SPD) of the emitted light. For a white LED using a blue InGaN chip with a yellow phosphor, the curve typically shows a dominant peak in the blue region (around 450-460 nm) from the chip and a broader peak or hump in the yellow/green region (around 550-600 nm) generated by the phosphor. The combination of these spectra results in the perception of white light. The full width of the curve spans from approximately 400 nm to 750 nm, covering the visible spectrum.

5. Mechanical & Package Information

5.1 Package Dimensions and Tolerances

The LED conforms to an EIA standard SMD package outline. All critical dimensions are provided in millimeters, with a standard tolerance of ±0.05 mm unless otherwise specified. Key mechanical definitions include:

• Distance A: The vertical distance between the bottom of the solder pad and the reflector. Minimum is 0.05mm.
• Tolerance B: The alignment tolerance between the left and right solder pads. Maximum is 0.03mm.
• Distance C: The lateral distance between the solder pad and the reflector wall. Minimum is 0.05mm.

These dimensions are crucial for PCB pad design and ensuring proper solder joint formation and light extraction.

5.2 Tape and Reel Packaging Dimensions

Detailed drawings specify the carrier tape dimensions (pocket size, pitch, etc.) and the reel dimensions (7-inch diameter). The packaging follows EIA-481-1-B specifications. Key notes include: 2000 pieces per reel, a maximum of two consecutive missing components allowed, and specified leader/trailer tape lengths (minimum 20 cm at start, 50 cm at end).

6. Soldering & Assembly Guidelines

6.1 Reflow Soldering Profile

The LED is compatible with infrared (IR) and vapor phase reflow soldering processes. A recommended lead-free reflow profile is referenced, conforming to J-STD-020D. The critical parameter is the device's ability to withstand a peak temperature of 260°C for 10 seconds. Following the recommended ramp-up, soak, and cooling rates is essential to prevent thermal shock and ensure reliable solder joints.

6.2 Cleaning

If post-solder cleaning is necessary, only specific chemicals should be used to avoid damaging the LED package. The datasheet recommends immersion in ethyl alcohol or isopropyl alcohol at normal temperature for less than one minute. The use of unspecified chemical liquids is prohibited.

6.3 Storage and Moisture Sensitivity

The product is rated as Moisture Sensitivity Level (MSL) 3 per JEDEC J-STD-020.

• Sealed Package: Store at ≤30°C and ≤90% RH. Shelf life is one year when stored in the original moisture-proof bag with desiccant.
• Opened Package: Store at ≤30°C and ≤60% RH. The components must be soldered within 168 hours (7 days) of exposure to the ambient environment.
• Baking: If the humidity indicator card turns pink (indicating >10% RH) or the 168-hour floor life is exceeded, baking at 60°C for at least 48 hours is recommended before resealing or use.

7. Application Suggestions

7.1 Typical Application Scenarios

This white SMD LED is suitable for a wide range of applications requiring compact, efficient white illumination, including but not limited to:

• Status indicators and backlighting for consumer electronics (e.g., appliances, audio equipment).
• Panel indicators and switch backlighting in industrial control systems.
• General purpose illumination in portable devices.
• Decorative lighting and signage.

Important Note: The datasheet explicitly states these LEDs are intended for ordinary electronic equipment. For applications with exceptional reliability requirements or where failure could jeopardize life or health (aviation, medical devices, safety systems), consultation with the manufacturer is required prior to design-in.

7.2 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. Operate at or below the recommended 30 mA DC forward current.
• Thermal Management: Ensure the PCB provides adequate thermal relief, especially when operating at high currents or in high ambient temperatures, to stay within the 120 mW power dissipation limit.
• ESD Protection: Implement standard ESD handling procedures during assembly. Consider adding transient voltage suppression (TVS) diodes or other protection on the circuit board if the LED is in an exposed location.
• Optical Design: The 110-degree viewing angle provides a wide beam. For more focused light, secondary optics (lenses) may be required.

8. Technical Comparison & Differentiation

While a direct side-by-side comparison with other part numbers is not provided in this single datasheet, key differentiating features of this LED can be inferred:

• Wide Viewing Angle (110°): Offers broader illumination compared to LEDs with narrower viewing angles, suitable for area lighting rather than spot lighting.
• Detailed Binning: The extensive V_F, I_V, and color coordinate binning provides high consistency for applications requiring matched performance across multiple units.
• Robust Packaging: Compatibility with automatic placement and standard lead-free reflow profiles (260°C peak) facilitates high-volume, reliable manufacturing.
• InGaN Technology: Provides efficient white light generation typical of modern high-brightness LED designs.

9. Frequently Asked Questions (Based on Technical Parameters)

9.1 What is the difference between the Peak Forward Current (100mA) and the DC Forward Current (30mA)?

The DC Forward Current (30mA) is the maximum current for continuous, steady-state operation. The Peak Forward Current (100mA) is a much higher current that the LED can handle only for very short pulses (0.1ms width) at a low duty cycle (10%). This is useful for applications like multiplexing or PWM dimming where brief high-current pulses achieve higher instantaneous brightness without overheating the LED. Exceeding the DC current rating continuously will cause excessive heat and rapid degradation.

9.2 How do I interpret the Chromaticity Coordinates (x=0.295, y=0.280)?

These coordinates plot the color of the white light on the CIE 1931 chromaticity diagram. This specific point typically corresponds to a "cool white" or "daylight white" color temperature, often in the range of 6000K-7000K. The ±0.01 tolerance defines a small area on the chart within which the color of any individual LED from this batch should fall, ensuring color uniformity.

9.3 Why is the storage condition so strict (MSL 3)? What happens if I exceed the 168-hour floor life?

SMD packages can absorb moisture from the air. During the high-temperature reflow soldering process, this trapped moisture can rapidly turn to steam, causing internal delamination, cracking, or "popcorning" of the plastic package, which can destroy the LED. MSL 3 and the 168-hour limit define a safe exposure time for the specific moisture absorption rate of this package. If exceeded, baking (60°C for 48hrs) removes the absorbed moisture, restoring the component to a dry state suitable for reflow.

10. Design and Usage Case Example

10.1 Designing a Status Indicator Panel

Scenario: Designing a control panel with 10 uniform white LED status indicators.

Design Steps:

1. Current Setting: Choose an operating point, e.g., I_F = 20 mA, for reliable operation and to use the datasheet's binned data directly.
2. Voltage Calculation: Assuming a 5V supply (V_CC). Select LEDs from the same V_F bin, e.g., V3 (3.2-3.3V). Use the typical value (3.25V) for calculation. The required series resistor R = (V_CC - V_F) / I_F = (5 - 3.25) / 0.020 = 87.5 Ω. A standard 91 Ω or 82 Ω resistor can be used, slightly adjusting the current.
3. Brightness Uniformity: Specify LEDs from the same I_V bin (e.g., Bin C: 1440-1580 mcd) to ensure all indicators have similar perceived brightness.
4. Color Uniformity: Specify LEDs from the same Color Rank (e.g., A63) to guarantee all lights emit an identical shade of white, critical for aesthetic consistency.
5. PCB Layout: Follow the recommended pad dimensions from the datasheet. Ensure pad design respects the minimum distances (A, C) to the LED body/reflector to prevent shorting and allow proper solder fillet formation.
6. Assembly: Use the recommended IR reflow profile. Keep the LEDs in sealed bags until ready for assembly. If the bag is opened, complete soldering of all 10 LEDs within 168 hours.

11. Operating Principle Introduction

This white LED operates on the principle of electroluminescence in a semiconductor. The core is a chip made of Indium Gallium Nitride (InGaN), which emits blue light when electrons recombine with holes across its bandgap upon the application of a forward voltage (typically 2.9-3.6V). To produce white light, the blue-emitting chip is coated with a layer of cerium-doped yttrium aluminum garnet (YAG:Ce) phosphor. A portion of the high-energy blue photons from the chip is absorbed by the phosphor, which then re-emits lower-energy yellow light through a process called photoluminescence. The remaining unabsorbed blue light mixes with the emitted yellow light, and the human eye perceives this combination as white. The yellow lens further diffuses and shapes the final light output.

12. Technology Trends

The technology described in this datasheet represents a mature and widely adopted approach for generating white light with LEDs. Key ongoing trends in the broader LED industry that relate to such components include:

• Increased Efficiency (lm/W): Continuous improvements in InGaN chip design, phosphor efficiency, and package architecture lead to higher luminous efficacy, meaning more light output for the same electrical input power.
• Improved Color Quality: Development of multi-phosphor blends (e.g., adding red phosphor) to enhance the Color Rendering Index (CRI), providing more accurate and pleasing color reproduction under the LED light.
• Miniaturization: The drive for smaller devices in consumer electronics pushes for LEDs in even smaller package footprints while maintaining or increasing light output.
• Higher Reliability & Lifetime: Advancements in materials (epoxy, phosphor, substrates) and thermal management designs are extending the operational lifetime (L70, L90) of LEDs, reducing long-term maintenance costs.
• Smart & Connected Lighting: While this is a basic component, the ecosystem is moving towards LEDs that are integral parts of intelligent systems, often requiring compatible drivers for dimming, color tuning, and connectivity.