ELUA3535OG5 UVA LED Datasheet - 3.5x3.5x3.5mm - 3.2-4.0V - 500mA - 360-410nm - English Technical Document

1. Product Overview

The ELUA3535OG5 series is a high-quality, high-reliability ceramic-based LED specifically engineered for ultraviolet (UVA) applications. Its robust construction and performance characteristics make it suitable for demanding environments.

1.1 Core Advantages

• High Power Output: Delivers high radiant flux, making it effective for applications requiring significant UV intensity.
• Ceramic Package (Al2O3): Provides excellent thermal management, mechanical strength, and long-term reliability compared to plastic packages.
• Compact Form Factor: The 3.5mm x 3.5mm x 3.5mm footprint allows for high-density PCB layouts.
• Compliance and Safety: The product is RoHS compliant, Pb-free, EU REACH compliant, and halogen-free, meeting stringent environmental and safety standards.
• ESD Protection: Built-in electrostatic discharge protection up to 2KV (HBM), enhancing handling and operational robustness.

1.2 Target Applications

This LED series is designed for various professional and industrial UV applications, including:

• UV sterilization and disinfection systems.
• UV photocatalysis for air and water purification.
• UV sensor and detection lighting.
• Curing processes for adhesives, inks, and coatings.

2. In-Depth Technical Parameter Analysis

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. Operation should be maintained within these boundaries.

• Maximum Forward Current (I_F): 1000mA for 385nm, 395nm, and 405nm variants; 700mA for the 365nm variant. This difference is likely due to the higher photon energy and associated thermal challenges at shorter wavelengths.
• Maximum Junction Temperature (T_J): 105°C. Maintaining the junction temperature below this limit is critical for longevity.
• Thermal Resistance (R_th): 4°C/W. This low value indicates efficient heat transfer from the chip to the thermal pad, facilitated by the ceramic package.
• Operating Temperature Range (T_Opr): -10°C to +100°C.

2.2 Photometric and Electrical Characteristics

The table provides key performance data for standard product configurations at a forward current (I_F) of 500mA.

• Peak Wavelength: Available in four ranges: 360-370nm, 380-390nm, 390-400nm, and 400-410nm, covering the UVA spectrum.
• Radiant Flux: Minimum values range from 900mW (360-370nm) to 1000mW (other wavelengths). Typical values are around 1200-1250mW.
• Forward Voltage (V_F): Typically between 3.2V and 4.0V at 500mA, with specific bins defined for tighter control.

3. Product Binning System Explanation

Binning ensures consistent performance by grouping LEDs with similar characteristics. This is crucial for applications requiring uniform output.

3.1 Radiant Flux Binning

LEDs are sorted based on their minimum radiant flux output. Different bin codes (U1, U2, U3, U4) are used for the 360nm group and the 380-410nm groups, reflecting typical performance variations across wavelengths.

3.2 Peak Wavelength Binning

LEDs are categorized into groups (U36, U38, U39, U40) corresponding to their peak wavelength range (e.g., 360-370nm, 380-390nm). A tight tolerance of ±1nm is specified.

3.3 Forward Voltage Binning

Voltage is binned in 0.2V steps (e.g., 3.2-3.4V, 3.4-3.6V). This helps in designing driver circuits and managing power dissipation across multiple LEDs in series.

4. Performance Curve Analysis

4.1 Spectrum and Relative Emission

The spectrum curves show narrow emission peaks characteristic of LEDs. The 365nm LED has a slightly broader spectrum compared to the longer wavelength variants (385nm, 395nm, 405nm).

4.2 Relative Radiant Flux vs. Forward Current

The radiant flux increases sub-linearly with current. The 405nm LED shows the highest relative output, while the 365nm LED shows the lowest at high currents, consistent with its lower maximum current rating.

4.3 Forward Voltage vs. Forward Current

The V_F curves show a typical diode characteristic. The 365nm LED generally exhibits a higher forward voltage than the others at the same current, which is expected for shorter wavelength semiconductors.

4.4 Temperature Dependence

• Radiant Flux vs. Temperature: Output decreases as ambient temperature rises, with the 365nm LED being most sensitive. Effective heatsinking is essential to maintain performance.
• Peak Wavelength vs. Temperature: The peak wavelength shifts slightly to longer wavelengths (red-shift) with increasing temperature.
• Forward Voltage vs. Temperature: V_F decreases linearly with increasing temperature, a typical behavior for semiconductors.

4.5 Derating Curve

The derating curve is critical for thermal design. It shows the maximum allowable forward current as a function of the ambient temperature. For example, at an ambient temperature of 85°C, the maximum current is significantly reduced to prevent exceeding the 105°C junction temperature.

5. Mechanical and Packaging Information

5.1 Mechanical Dimensions

The LED has a square footprint of 3.5mm x 3.5mm with a height of 3.5mm. The dimensional drawing specifies all critical lengths, including the lens dome and the positioning of the thermal pad and electrical pads. Tolerances are typically ±0.1mm.

5.2 Pad Configuration and Polarity

The bottom view shows the pad layout: two larger pads for the anode and cathode, and a central, larger thermal pad. The thermal pad is electrically isolated and must be connected to a PCB copper pour for optimal heat dissipation. The polarity is clearly marked on the package itself.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Profile

The LED is suitable for standard SMT (Surface Mount Technology) processes. The recommended reflow profile should be followed carefully. Key considerations include:

• Avoid exceeding two reflow cycles to minimize thermal stress on the package and internal bonds.
• Prevent mechanical stress on the LED during the heating and cooling phases of soldering.
• Do not bend the PCB after soldering, as this can crack the ceramic package or solder joints.

6.2 Storage and Handling

Store in a dry environment within the specified storage temperature range (-40°C to +100°C). Use ESD-safe procedures during handling due to the integrated but limited ESD protection.

7. Ordering Information and Model Nomenclature

The part number follows a detailed structure: ELUA3535OG5-PXXXXYY3240500-VD1M

• EL: Manufacturer code.
• UA: Indicates UVA product.
• 3535: Package size (3.5mm x 3.5mm).
• O: Package material (Al₂O₃ ceramic).
• G: Coating (Ag).
• 5: Viewing angle (50°).
• PXXXX: Peak wavelength code (e.g., 6070 for 360-370nm).
• YY: Minimum radiant flux bin (e.g., U1 for 900mW).
• 3240: Forward voltage specification range (3.2-4.0V).
• 500: Rated forward current (500mA).
• V: Chip type (Vertical).
• D: Chip size (45mil).
• 1: Number of chips (1).
• M: Process type (Molding).

8. Application Design Considerations

8.1 Thermal Management

This is the most critical aspect of design. The low thermal resistance (4°C/W) is only effective if the heat is conducted away from the thermal pad. Use a PCB with adequate thermal vias connected to internal ground planes or an external heatsink. Monitor junction temperature using the derating curve.

8.2 Electrical Drive

Use a constant current driver suitable for the forward voltage and current requirements. Consider the voltage binning when designing for multiple LEDs in series to ensure uniform current distribution. Do not exceed the absolute maximum current ratings.

8.3 Optical Design

The 50° viewing angle provides a relatively wide beam. For focused applications, secondary optics (lenses, reflectors) may be required. Ensure any materials used (lenses, encapsulants) are UV-stable to prevent yellowing and degradation over time.

9. Technical Comparison and Differentiation

The primary differentiators of the ELUA3535OG5 series are its ceramic package and high-power UVA output in a compact 3535 footprint.

• vs. Plastic Package UVA LEDs: Ceramic offers superior thermal performance, higher maximum junction temperature, and better long-term reliability under high-power UV operation, which can degrade plastics.
• vs. Larger Ceramic Packages: The 3535 size enables more compact designs without sacrificing the benefits of ceramic construction.
• vs. Lower Power UVA LEDs: The high radiant flux (up to 1500mW) makes it suitable for applications requiring high irradiance, reducing the number of LEDs needed for a given output.

10. Frequently Asked Questions (FAQ)

10.1 Why is the maximum current lower for the 365nm version?

Shorter wavelength LEDs (like 365nm) generally have lower wall-plug efficiency, meaning a higher percentage of electrical power is converted to heat rather than light. To maintain reliability and prevent overheating at the junction, the maximum current is derated.

10.2 How important is connecting the thermal pad?

It is absolutely essential for reliable operation at high currents. The thermal pad is the primary path for heat escape. Not connecting it properly will cause the LED to overheat rapidly, leading to premature failure (lumen depreciation) or instant damage.

10.3 Can I drive this LED with a constant voltage source?

It is not recommended. LEDs are current-driven devices. Their forward voltage has a negative temperature coefficient and varies from unit to unit (as seen in the binning). A constant voltage source can lead to thermal runaway, where increasing current causes more heat, which lowers V_F, causing even more current, ultimately destroying the LED. Always use a constant current driver.

10.4 What is the typical lifetime of this LED?

While a specific L70/L50 lifetime (hours to 70% or 50% of initial output) is not provided in this datasheet, the high-quality ceramic construction and specification of a 105°C maximum junction temperature are indicators of good long-term reliability. Actual lifetime is heavily dependent on operating conditions, especially junction temperature. Operating at or below the recommended current and with excellent thermal management will maximize lifetime.

11. Design and Usage Case Study

11.1 UV-Curing Station for Adhesives

Scenario: Designing a benchtop UV curing station for fast-curing adhesives. The station needs an array of LEDs to provide uniform high-intensity UVA light over a 10cm x 10cm area.

Design Steps:

1. LED Selection: Choose the ELUA3535OG5-P0010U2... (400-410nm) variant, as many adhesives are formulated to cure efficiently in this wavelength range.
2. Array Layout: Calculate the number of LEDs needed based on the required irradiance (mW/cm²) at the working distance. Using optics to focus or diffuse the 50° beam may be necessary for uniformity.
3. Thermal Design: Mount the LEDs on an aluminum-core PCB (MCPCB) with a high thermal conductivity dielectric layer. The entire MCPCB is then attached to an extruded aluminum heatsink with a fan.
4. Electrical Design: Use a constant current driver capable of supplying the total current for all LEDs in series/parallel configuration. Include appropriate fusing and current monitoring.
5. Control: Implement a timer and possibly a temperature sensor on the heatsink to prevent overheating during extended use.

Outcome: A reliable, high-performance curing station with consistent output and long service life, enabled by the robust thermal and optical performance of the ceramic UVA LEDs.

12. Operating Principle Introduction

UVA LEDs operate on the same fundamental principle as visible light LEDs: electroluminescence in a semiconductor material. When a forward voltage is applied across the p-n junction, electrons and holes recombine, releasing energy in the form of photons. The wavelength (color) of the emitted light is determined by the bandgap energy of the semiconductor material. For UVA light (315-400nm), materials like aluminum gallium nitride (AlGaN) or indium gallium nitride (InGaN) with specific compositions are used to achieve the required wide bandgap. The ceramic package serves as a robust substrate that effectively conducts heat away from the semiconductor chip, which is crucial for maintaining performance and longevity, especially at the high drive currents used for UVA applications.

13. Technology Trends and Outlook

The market for UVA LEDs is driven by applications in sterilization, purification, and industrial curing. Key trends include:

• Increased Efficiency (WPE): Ongoing research aims to improve the wall-plug efficiency of UVA LEDs, reducing energy consumption and thermal load for the same optical output.
• Higher Power Density: Development continues towards packing more optical power into the same or smaller package sizes, like the 3535, enabling more compact and powerful systems.
• Improved Reliability at Shorter Wavelengths: Enhancing the longevity and performance of LEDs emitting at the lower end of the UVA spectrum (e.g., 365nm) and into the UVB/UVC ranges remains a significant focus for germicidal applications.
• Advanced Packaging: Innovations in package materials (e.g., other ceramics, composites) and thermal interface technologies to further lower thermal resistance and manage heat in high-power arrays.
• Smart Integration: Potential integration of sensors (e.g., for temperature or irradiance monitoring) within LED modules for closed-loop control in advanced systems.