ELUC3535NUB UVC LED Datasheet - 3.45x3.45x1.1mm - 5.0-7.0V - 0.7W - 270-285nm - English Technical Documentation

1. Product Overview

The ELUC3535NUB series represents a high-reliability, ceramic-based LED solution engineered specifically for demanding ultraviolet (UVC) applications. This product is designed to deliver consistent performance in environments where germicidal efficacy is critical. Its core advantage lies in the robust ceramic package, which provides excellent thermal management, a crucial factor for maintaining LED lifespan and output stability in UVC applications. The primary target market includes manufacturers of water, air, and surface sterilization systems, as well as medical and laboratory equipment requiring reliable UV-C light sources.

1.1 Key Features and Applications

The ELUC3535NUB is characterized by several defining features that make it suitable for professional UV-C applications. It is a high-power UVC LED emitter. The physical dimension is a compact 3.45mm x 3.45mm with a height of 1.1mm, making it suitable for space-constrained designs. It incorporates ESD protection rated up to 2KV (HBM), enhancing its robustness against electrostatic discharge during handling and assembly. The device offers a typical wide viewing angle of 120 degrees, providing broad irradiation coverage. It is fully compliant with RoHS (Restriction of Hazardous Substances), is lead-free (Pb-free), adheres to EU REACH regulations, and meets halogen-free standards with strict limits on Bromine and Chlorine content (Br<900ppm, Cl<900ppm, Br+Cl<1500ppm). The primary application for this LED series is UV sterilization, encompassing disinfection of water, air, and surfaces.

2. Technical Parameter Deep Dive

This section provides an objective and detailed interpretation of the key technical parameters specified in the datasheet, explaining their significance for design engineers.

2.1 Absolute Maximum Ratings

The Absolute Maximum Ratings define the limits beyond which permanent damage to the device may occur. For the ELUC3535NUB, the maximum continuous forward current (I_F) is 150 mA. The maximum electrostatic discharge (ESD) resistance (Human Body Model) is 2000 V. The maximum allowable junction temperature (T_J) is 90°C. The thermal resistance from junction to solder pad (R_th) is specified as 20 °C/W, indicating how effectively heat is transferred away from the semiconductor junction. The operating temperature range (T_Opr) is from -40°C to +85°C, and the storage temperature range (T_Stg) is from -40°C to +100°C. Operating the LED within these limits is essential for reliability.

2.2 Photometric and Electrical Characteristics

The primary photometric output is measured in Radiant Flux (mW), not luminous flux (lm), as this is a non-visible UV emitter. For the example part number ELUC3535NUB-P7085Q15070100-S22Q, the minimum radiant flux is 8mW, typical is 10mW, and maximum is 15mW, all measured at the forward current of 100mA. The peak wavelength bin for this example is 270-285 nm, placing it firmly in the UVC spectrum known for its germicidal properties. The forward voltage (V_F) range at 100mA is specified as 5.0V to 7.0V. The nominal forward current for testing and binning is 100mA.

3. Binning System Explanation

The product is classified into bins based on key performance parameters to ensure consistency within a production batch. This allows designers to select LEDs with tightly controlled characteristics.

3.1 Radiant Flux Bins

Radiant flux is binned into two categories: Bin Q1 covers a minimum of 8mW to a maximum of 10mW. Bin Q2 covers a minimum of 10mW to a maximum of 15mW. The measurement tolerance for radiant flux is ±10%.

3.2 Peak Wavelength Bins

Peak wavelength is critically important for sterilization efficiency. The bins are: U27A (270nm to 275nm), U27B (275nm to 280nm), and U28 (280nm to 285nm). The measurement tolerance is ±1nm.

3.3 Forward Voltage Bins

Forward voltage bins help in designing consistent driver circuits. The bins are defined at I_F=100mA: 5055 (5.0V to 5.5V), 5560 (5.5V to 6.0V), 6065 (6.0V to 6.5V), and 6570 (6.5V to 7.0V). The measurement tolerance is ±2%.

4. Performance Curve Analysis

The typical characteristic curves provide insight into the LED's behavior under various operating conditions.

4.1 Spectrum

The spectrum curve shows a narrow emission peak centered within the 270-285nm range at 25°C thermal pad temperature. The curve demonstrates the LED's purity in emitting UVC light with minimal unwanted wavelengths, which is ideal for targeted germicidal action.

4.2 Relative Radiant Flux vs. Forward Current

This curve shows a near-linear relationship between forward current and relative radiant flux up to the maximum rated current. It indicates that output can be moderately adjusted by varying the drive current, but thermal effects must be managed.

4.3 Peak Wavelength vs. Current

The peak wavelength exhibits minimal shift with increasing forward current, showing good stability. This is important as the germicidal effectiveness is highly wavelength-dependent.

4.4 Forward Current vs. Forward Voltage (IV Curve)

The IV curve demonstrates the diode's characteristic exponential relationship. It shows the forward voltage increasing with current, typically between 5.0V and 7.0V at the nominal 100mA operating point.

4.5 Relative Radiant Flux vs. Ambient Temperature

This curve is crucial for thermal management design. It shows that the radiant flux output decreases as the ambient temperature rises. Effective heat sinking is required to maintain output power, especially since the maximum junction temperature is limited to 90°C.

4.6 Derating Curve

The derating curve provides the maximum allowable forward current at different ambient temperatures. To prevent exceeding the maximum junction temperature, the drive current must be reduced as the ambient temperature increases. This graph is essential for designing reliable systems.

4.7 Typical Radiation Pattern

The radiation pattern plot confirms the 120° viewing angle (where intensity drops to half of the peak value). The pattern is typically Lambertian, providing wide, even coverage which is beneficial for sterilization chambers.

5. Mechanical and Package Information

5.1 Mechanical Dimensions

The LED has a square footprint of 3.45mm x 3.45mm with a height of 1.1mm. The dimensional drawing specifies all critical lengths, including the lens dome. Tolerances are typically ±0.2mm unless otherwise noted.

5.2 Pad Configuration and Polarity

The soldering pad pattern is clearly defined. Pad 1 is the Anode (+), Pad 2 is the Cathode (-), and Pad 3 is a large Thermal Pad. The thermal pad is essential for transferring heat from the ceramic package to the PCB and must be properly soldered for optimal thermal performance.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Process

The ELUC3535NUB is suitable for standard SMT (Surface Mount Technology) processes. A specific reflow soldering profile should be followed, typically provided by the assembly equipment or past manufacturer. Key recommendations include: Curing any adhesive according to standard processes, avoiding more than two reflow soldering cycles to prevent thermal stress, minimizing mechanical stress on the LED during heating, and avoiding bending of the PCB after soldering to prevent solder joint or die cracking.

7. Packaging and Ordering Information

7.1 Emitter Tape and Reel Packaging

The LEDs are supplied on embossed carrier tape wound onto reels. The standard reel contains 1000 pieces. Detailed dimensions for the carrier tape pockets and the reel are provided to facilitate automated pick-and-place machine setup.

7.2 Moisture-Resistant Packaging

For storage and shipment, the reels are sealed inside aluminum moisture-proof bags along with desiccant to protect the LEDs from ambient humidity, which is critical for maintaining solderability and device integrity.

7.3 Product Labeling

The reel label contains essential information for traceability and identification, including the Part Number (P/N), quantity (QTY), and Lot Number (LOT No.). It may also include bin codes for Radiant Flux (CAT), Wavelength (HUE), and Forward Voltage (REF).

7.4 Product Nomenclature Decoding

The part number is a structured code: ELUC3535NUB-P7085Q15070100-S22Q. It decodes as follows: EL (Manufacturer Code), UC (UVC), 3535 (Package Size), N (AIN Ceramic Package), U (Au Coating), B (120° Angle), P (Peak Wavelength), 7085 (270-285nm), Q1 (Radiant Flux Bin), 5070 (Forward Voltage Bin 5.0-7.0V), 100 (100mA Current), S (Submount Chip Type), 2 (20mil Chip Size), 2 (2 Chips), Q (Quartz Glass Lens). This system allows precise specification of the LED's characteristics.

8. Application Suggestions and Design Considerations

8.1 Typical Application Scenarios

The primary application is UV sterilization. This includes point-of-use water purifiers, HVAC air disinfection systems, surface sanitizers for consumer electronics or medical tools, and germicidal fixtures. The 270-285nm wavelength is highly effective at inactivating bacteria, viruses, and other microorganisms by damaging their DNA/RNA.

8.2 Critical Design Considerations

Thermal Management: This is the single most important design factor. The low maximum junction temperature (90°C) and significant thermal dependence of output require an effective thermal path. Use a PCB with thermal vias under the thermal pad connected to a large copper plane or an external heatsink. Drive Circuit: Use a constant current driver suitable for the forward voltage range (5.0-7.0V) at the desired operating current (typically 100mA). Consider dimming or pulsed operation for lifetime extension. Optical Materials: Ensure that any lenses, windows, or enclosures in the light path are made of UVC-transparent materials like quartz glass or specific UV-grade plastics. Ordinary glass and many plastics block UVC. Safety: UVC radiation is harmful to eyes and skin. Designs must incorporate interlocks, shielding, and warnings to prevent user exposure.

9. Technical Comparison and Differentiation

Compared to traditional mercury-vapor UV lamps, this LED offers significant advantages: instant on/off, no warm-up time, compact size, robustness (no glass, no mercury), design flexibility, and the potential for longer lifetime if properly thermally managed. Compared to other UVC LEDs, the key differentiators of the ELUC3535NUB series likely include its ceramic AIN package for superior thermal performance, the integrated 2KV ESD protection, and its compliance with stringent environmental standards (RoHS, Halogen-Free). The 120° viewing angle provides wider coverage than narrower-beam alternatives.

10. Frequently Asked Questions (Based on Technical Parameters)

Q: What is the typical lifetime of this LED?
A: While not explicitly stated in this datasheet, the lifetime of UVC LEDs is heavily dependent on operating conditions, primarily junction temperature and drive current. Operating at or below the recommended current with excellent heat sinking can lead to lifetimes of thousands of hours. Refer to separate lifetime reports for L70/B50 data (time to 70% radiant flux output).

Q: Can I drive this LED with a constant voltage source?
A: It is not recommended. LEDs are current-driven devices. A constant voltage source could lead to thermal runaway due to the negative temperature coefficient of the forward voltage. Always use a constant current driver.

Q: How do I select the correct bin for my application?
A: For sterilization efficacy, prioritize the wavelength bin (U27A, U27B, U28) based on the target microorganism's absorption peak. For consistent light output across multiple LEDs in an array, specify a tight radiant flux bin (e.g., Q1). For driver design efficiency, a tighter forward voltage bin reduces power variation.

Q: Is a lens required?
A: The device has an integrated quartz glass lens providing a 120° beam. Secondary optics may be added to collimate or focus the beam for specific applications, but they must be UVC-transparent.

11. Practical Design and Usage Case

Case: Designing a Compact Water Disinfection Module
A designer is creating a point-of-use water filter with integrated UVC sterilization. They select the ELUC3535NUB for its compact 3535 footprint and ceramic package. The module has a small quartz flow chamber. The designer uses 4 LEDs in an array to ensure all water is exposed. They design a 2-layer aluminum-core PCB (MCPCB) to act as both electrical substrate and heatsink. The thermal pad of each LED is soldered directly to the MCPCB. A constant current driver provides 100mA to each LED in parallel (with individual current-limiting resistors for safety). The LEDs are driven in a pulsed mode (e.g., 50% duty cycle) to reduce average junction temperature and extend lifetime. The enclosure is designed to be completely light-tight to prevent any UVC leakage, with safety interlocks that cut power if the chamber is opened.

12. Operating Principle Introduction

UVC LEDs operate on the same fundamental principle as visible LEDs: electroluminescence in a semiconductor. 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 UVC LEDs (emitting below 280nm), the active region is typically made from aluminum gallium nitride (AlGaN) alloys. Achieving efficient emission in the deep ultraviolet range is technologically challenging due to material quality and light extraction difficulties, which is why UVC LEDs have higher forward voltages and lower wall-plug efficiency compared to visible LEDs.

13. Technology Trends and Development

The UVC LED market is driven by the global phase-out of mercury lamps and demand for safer, more flexible disinfection solutions. Key trends include: Increasing Output Power and Efficiency: Continuous R&D aims to improve the radiant flux per LED and the wall-plug efficiency (optical power out / electrical power in), reducing system cost and size. Longer Wavelengths: Research into LEDs emitting around 260-280nm continues as this range is near the DNA absorption peak for many pathogens. Improved Reliability and Lifetime: Advancements in packaging materials (like the AIN ceramic used here), chip design, and thermal management are extending operational lifetimes, making LEDs viable for more 24/7 applications. Cost Reduction: As manufacturing volumes increase and yields improve, the price per milliwatt of UVC output is steadily decreasing, opening up new consumer and industrial applications.