ELUA3535OGB UVA LED Datasheet - 3.5x3.5x2.35mm - 3.2-4.0V - 1.8W - 360-410nm - English Technical Document

1. Product Overview

The ELUA3535OGB product series represents a high-reliability, ceramic-based LED solution engineered specifically for ultraviolet (UVA) applications. Its core construction utilizes an Al2O3 (Aluminum Oxide) ceramic substrate, which provides superior thermal management compared to traditional plastic packages, leading to enhanced longevity and stable performance under demanding conditions.

Core Advantages: The primary benefits of this series include its robust ceramic package for excellent heat dissipation, integrated ESD protection up to 2KV (Human Body Model), and compliance with major environmental and safety standards including RoHS, Pb-free, EU REACH, and halogen-free requirements (Br<900ppm, Cl<900ppm, Br+Cl<1500ppm). The 120-degree viewing angle offers a broad radiation pattern suitable for area illumination tasks.

Target Market & Applications: This LED is designed for industrial and commercial UV applications where reliability and optical output are critical. Key application areas include UV sterilization systems for air and water purification, UV photocatalyst systems for surface treatment and odor elimination, and as a light source for UV sensors and curing processes.

2. Technical Parameter Deep Dive

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.

• Max. DC Forward Current (I_F): 1000 mA for 385nm, 395nm, and 405nm variants. For the 365nm variant, the maximum current is derated to 700 mA, reflecting its different semiconductor material characteristics and thermal sensitivity.
• Max. ESD Resistance (V_B): 2000 V (HBM), providing good handling robustness.
• Thermal Resistance (R_th): 4 °C/W. This low value, attributed to the ceramic package, indicates efficient heat transfer from the LED junction to the thermal pad.
• Max. Junction Temperature (T_J): 125 °C.
• Operating & Storage Temperature: -10 to +100 °C for operation, and -40 to +100 °C for storage.

2.2 Photometric & Electrical Characteristics

The table lists key performance parameters for different wavelength bins at a standard test current of 500mA and a thermal pad temperature of 25°C.

• Peak Wavelength: Available in four bins: 360-370nm (U36), 380-390nm (U38), 390-400nm (U39), and 400-410nm (U40).
• Radiant Flux: Minimum radiant flux is specified at 1000mW (U2 bin), with typical values around 1250mW and maximum up to 1500mW across all wavelength groups.
• Forward Voltage (V_F): Ranges from 3.2V to 4.0V at 500mA, categorized into specific voltage bins (e.g., 3.2-3.4V, 3.4-3.6V).

3. Binning System Explanation

The product is classified into bins to ensure consistency and allow for precise selection based on application needs.

3.1 Radiant Flux Binning

Radiant flux is measured at I_F=500mA with a tolerance of ±10%. The bins are:
- U2: 1000mW to 1200mW
- U3: 1200mW to 1400mW
- U4: 1400mW to 1500mW

3.2 Peak Wavelength Binning

Peak wavelength is measured with a tolerance of ±1nm. The groups (U36, U38, U39, U40) correspond to the wavelength ranges listed in section 2.2.

3.3 Forward Voltage Binning

Forward voltage is measured at I_F=500mA with a tolerance of ±2%. The bins (3234, 3436, 3638, 3840) define the minimum and maximum V_F range (e.g., 3234 = 3.2V to 3.4V).

4. Performance Curve Analysis

4.1 Spectrum & Relative Radiant Flux vs. Current

The spectral graphs show typical emission curves for the 365nm, 385nm, 395nm, and 405nm variants. The curves are narrowband, characteristic of UV LEDs. The Relative Radiant Flux vs. Forward Current graph demonstrates a near-linear relationship up to the rated current, with the 405nm LED generally showing the highest relative output, followed by 395nm, 385nm, and 365nm at the same current level.

4.2 Peak Wavelength & Forward Voltage vs. Current

The Peak Wavelength vs. Forward Current plot shows minimal shift (<5nm) across the operating current range for all wavelengths, indicating good spectral stability. The Forward Voltage vs. Forward Current curve shows the typical diode exponential characteristic, with V_F increasing with current. The 365nm LED typically exhibits a slightly higher V_F than the longer wavelength variants.

4.3 Temperature Dependence

The Relative Radiant Flux vs. Ambient Temperature graph shows output decreasing as temperature rises, a common behavior for LEDs. The derating curve is crucial for design: it specifies the maximum allowable forward current at a given ambient temperature to ensure the junction temperature (T_J) does not exceed 125°C. For example, at an ambient temperature of 85°C, the maximum current is significantly reduced from its room-temperature rating.

4.4 Radiation Pattern

The typical radiation pattern is Lambertian, centered with a 120-degree full viewing angle (2θ_1/2). This pattern is suitable for applications requiring wide-area coverage rather than focused beams.

5. Mechanical & Packaging Information

5.1 Mechanical Dimensions

The package dimensions are 3.5mm (L) x 3.5mm (W) x 2.35mm (H). The drawings specify the location of the thermal pad (cathode) and the anode pad. The thermal pad is central and large to facilitate heat sinking. All dimensional tolerances are ±0.1mm unless otherwise noted.

5.2 Polarity Identification

The anode is marked on the top of the LED package. The bottom-side thermal pad is electrically connected to the cathode. Correct polarity must be observed during board assembly.

6. Soldering & Assembly Guidelines

6.1 Reflow Soldering Process

The ELUA3535OGB is suitable for standard SMT (Surface Mount Technology) reflow processes. Key instructions include:
- Curing of any adhesive must follow standard processes.
- Reflow soldering should not be performed more than two times to avoid thermal stress.
- Mechanical stress on the LED during heating and cooling should be minimized.
- The circuit board should not be bent after soldering to prevent cracking of the ceramic package or solder joints.

6.2 Storage Conditions

LEDs should be stored in their original moisture-barrier bags at temperatures between -40°C and +100°C and at low humidity to prevent oxidation of the terminals.

7. Model Nomenclature & Ordering Information

The part number follows a detailed structure: ELUA3535OGB-PXXXXYY3240500-VD1M
- EL: Manufacturer code.
- UA: UVA product family.
- 3535: Package size (3.5x3.5mm).
- O: Package material (Al₂O₃ ceramic).
- G: Coating (Ag - Silver).
- B: Viewing angle (120°).
- PXXXX: Peak wavelength code (e.g., 6070 for 360-370nm).
- YY: Minimum Radiant Flux bin (e.g., U2 for 1000mW).
- 3240: Forward voltage range (3.2-4.0V).
- 500: Forward current rating (500mA).
- V: Chip type (Vertical).
- D: Chip size (45mil).
- 1: Number of chips (1).
- M: Process type (Molding).

8. Application Suggestions

8.1 Typical Application Circuits

These LEDs require a constant current driver for stable operation. A simple circuit involves a DC power supply, a constant current driver IC or circuit, and the LED in series. The driver should be selected to provide up to 500mA (or 700mA for 365nm) while respecting the derating curve based on the operating ambient temperature. Transient voltage suppression may be considered in electrically noisy environments, despite the built-in ESD protection.

8.2 Heat Sink Design

Effective thermal management is paramount. The low 4 °C/W thermal resistance is only effective if the heat is conducted away from the thermal pad. A properly designed PCB with thermal vias connecting the pad to a large copper plane or an external heatsink is essential, especially when operating at high currents or in elevated ambient temperatures. The maximum junction temperature (125°C) must not be exceeded.

8.3 Optical Design Considerations

For sterilization and photocatalyst applications, the irradiance (UV power per unit area) on the target surface is critical. The 120-degree beam angle provides wide coverage. For higher irradiance at a specific point, secondary optics (reflectors or lenses) may be needed. Material selection for optics and enclosures must consider UV transparency and resistance to UV degradation (e.g., using quartz, UV-grade glass, or specific UV-stable plastics like PTFE).

9. Technical Comparison & Differentiation

The ELUA3535OGB series differentiates itself through its ceramic package. Compared to plastic SMD UV LEDs, ceramic offers:
- Superior Thermal Performance: Lower thermal resistance leads to lower operating junction temperature at the same drive current, which directly translates to longer lifetime (L70/B50) and higher maintained output.
- Enhanced Reliability: Ceramic is inert and provides a hermetic-like barrier against moisture and environmental contaminants, improving performance in harsh conditions.
- Higher Power Density: The robust package allows for reliable operation at the 1.8W power level, which is at the higher end for LEDs in this physical footprint.

10. Frequently Asked Questions (FAQ)

10.1 What is the difference between the 365nm and 405nm versions beyond wavelength?

The primary difference is the semiconductor material composition, which leads to different electrical and optical properties. The 365nm LED has a lower maximum current rating (700mA vs. 1000mA), typically a slightly higher forward voltage, and lower radiant flux output at the same current. It is also more sensitive to temperature. The choice depends on the required wavelength for the specific application (e.g., 365nm for certain photocatalysts, 405nm for some curing processes).

10.2 How do I interpret the derating curve?

The derating curve defines the maximum safe operating forward current at a given ambient temperature (measured at the LED's thermal pad). To use it, find your expected maximum ambient temperature on the x-axis. Draw a line up to the curve, then left to the y-axis to find the maximum allowable current. You must design your driver to not exceed this current at that temperature. For example, if the ambient is 60°C, the maximum current is approximately 400mA.

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

It is strongly discouraged. LEDs are current-driven devices. Their forward voltage has a negative temperature coefficient and varies from unit to unit (as shown in the voltage bins). Driving with a constant voltage can lead to thermal runaway: as the LED heats up, V_F drops, causing current to increase, which generates more heat, further dropping V_F and increasing current until failure. Always use a constant current driver.

11. Design & Usage Case Study

11.1 Case Study: UV-Curing Station for Adhesives

Scenario: Designing a benchtop station for curing UV-sensitive adhesives on small electronic components.
Selection: The 405nm variant (ELUA3535OGB-P0010U23240500-VD1M) is chosen because many industrial UV-curable adhesives are formulated to cure efficiently around 400nm.
Design: An array of 16 LEDs is planned on an aluminum-core PCB (MCPCB) to create a uniform curing area. Each LED is driven at 450mA by a constant current driver to provide headroom below the 500mA rating, improving lifetime. The MCPCB is attached to a large aluminum heatsink with a fan. The derating curve is consulted: at an estimated internal ambient of 45°C, 450mA is well within the safe operating area. The 120-degree beam angle ensures good overlap between adjacent LEDs for uniformity.
Result: The station provides consistent, high-irradiance UV light for rapid curing, with the ceramic package ensuring stable output over long operational periods.

12. Principle Introduction

UVA LEDs operate on the principle of electroluminescence in semiconductor materials. When a forward voltage is applied across the p-n junction, electrons and holes are injected into the active region. Their recombination releases energy in the form of photons. The wavelength (color) of the emitted light is determined by the bandgap energy of the semiconductor material used in the active region. For UVA light (315-400nm), materials like InGaN/AlGaN are commonly used on specialized substrates. The ceramic package serves primarily as a mechanically robust and thermally conductive platform to extract heat, which is a byproduct of the non-radiative recombination processes within the chip.

13. Development Trends

The UV LED market, particularly for UVA and UVB, is driven by the phase-out of mercury lamps due to environmental regulations (Minamata Convention). Key trends include:
Increased Efficiency (WPE - Wall-Plug Efficiency): Ongoing research focuses on improving internal quantum efficiency and light extraction to deliver more optical power per electrical watt, reducing system energy costs and thermal load.
Higher Power & Power Density: Development continues towards single-die LEDs and multi-chip packages that deliver higher radiant flux from the same or smaller footprints, enabled by better thermal materials like advanced ceramics and composite substrates.
Improved Reliability & Lifetime: Enhancements in chip design, packaging materials (like the ceramic used here), and phosphor technology (for converted UV products) aim to extend operational lifetime, a critical factor for industrial and medical applications.
Cost Reduction: As manufacturing volumes increase and processes mature, the cost per radiant watt is expected to decrease, accelerating adoption across more applications.