LTPL-C16FUVM365 UV LED Datasheet - 3.5x3.2x1.9mm - 3.5V - 160mW - 365nm Peak Wavelength - English Technical Document

1. Product Overview

The LTPL-C16 series represents a significant advancement in solid-state lighting technology, specifically engineered for ultraviolet (UV) applications. This product is a revolutionary, energy-efficient, and ultra-compact light source that merges the long operational lifetime and high reliability inherent to Light Emitting Diodes (LEDs) with the intensity required to displace conventional UV lighting technologies. It provides designers with exceptional freedom due to its miniature form factor and delivers unmatched brightness for its size, opening new possibilities across various industrial and manufacturing processes.

1.1 Key Features and Advantages

The core advantages of this component are derived from its design and manufacturing process:

• Automation Compatibility: The device is fully compatible with standard automatic placement equipment, facilitating high-volume, cost-effective assembly on printed circuit boards (PCBs).
• Reflow Soldering Compatibility: It is designed to withstand both infrared (IR) and vapor phase reflow soldering processes, which are standard in modern electronics manufacturing.
• Standardized Package: The component conforms to EIA (Electronic Industries Alliance) standard package dimensions, ensuring interoperability with industry-standard pick-and-place systems and feeder tapes.
• Integrated Circuit (IC) Compatibility: The electrical characteristics allow for easy direct drive or control using common driver ICs, simplifying circuit design.
• Environmental Compliance: The product is manufactured as a green product and is lead-free (Pb-free), complying with the RoHS (Restriction of Hazardous Substances) directive.

1.2 Target Applications

This UV LED is specifically designed for applications requiring a compact, reliable, and efficient source of ultraviolet light in the 365nm range. Primary application areas include:

• UV Curing: Instantaneous curing of adhesives, coatings, inks, and resins in manufacturing and assembly processes.
• UV Marking and Coding: Facilitating photochemical reactions for marking or coding on various materials.
• UV Gluing: Activating and curing specialized UV-curable adhesives.
• Printing and Drying: Drying and curing of printing inks and other pigmented materials.
• Fluorescence Excitation: Causing materials to fluoresce for inspection, authentication, or decorative purposes.
• Medical and Scientific Instrumentation: Used in equipment for sterilization, analysis, or therapeutic purposes where controlled UV exposure is needed.

2. Technical Specifications Deep Dive

This section provides a detailed, objective analysis of the device's key performance parameters as defined in the datasheet. All specifications are defined at an ambient temperature (Ta) of 25°C unless otherwise stated.

2.1 Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. Operation under or at these limits is not guaranteed and should be avoided in reliable designs.

• Power Dissipation (Po): 160 mW. This is the maximum amount of power the package can dissipate as heat.
• DC Forward Current (If): 40 mA. The maximum continuous forward current that can be applied.
• Reverse Voltage (Vr): 5 V. Exceeding this voltage in reverse bias can cause immediate breakdown.
• Operating Temperature Range (Topr): -40°C to +85°C. The ambient temperature range for normal operation.
• Storage Temperature Range (Tstg): -40°C to +100°C.
• Junction Temperature (Tj): 90°C. The maximum allowable temperature at the semiconductor junction itself.

2.2 Electro-Optical Characteristics

These are the typical performance parameters under specified test conditions.

• Radiant Flux (Φe): 14-26 mW (Min-Typ-Max) at a forward current (If) of 20mA. This is the total optical power output in the UV spectrum. Measurement tolerance is ±10%.
• Viewing Angle (2θ1/2): 135 degrees (Typical). This defines the angular spread of the emitted UV light where intensity is half of the peak value.
• Peak Wavelength (λp): 362.5-370 nm at If=20mA. The specific wavelength at which the LED emits the most optical power, centered around 365nm. Tolerance is ±3nm.
• Forward Voltage (Vf): 2.8-4.0 V at If=20mA. The voltage drop across the LED when conducting the specified current. Measurement tolerance is ±0.1V.
• Reverse Current (Ir): 10 µA at a reverse voltage (Vr) of 1.2V (Max). This parameter is tested to verify the Zener-like characteristic but the device is not designed for reverse operation. Extended reverse bias can cause failure.
• Thermal Resistance (Rθj-s): 53 °C/W (Typical). This critical parameter indicates how effectively heat travels from the semiconductor junction (j) to the solder point or case (s). A lower value means better heat dissipation.

2.3 Thermal Management Considerations

The thermal resistance of 53°C/W is a key design factor. For example, at the maximum rated power dissipation of 160mW, the temperature rise from the solder point to the junction would be approximately 160mW * 53°C/W = 8.5°C. Designers must ensure the PCB and system design keep the solder point temperature sufficiently low so that the junction temperature (Tj) does not exceed its 90°C maximum, especially when operating at high currents or in elevated ambient temperatures. Exceeding Tj reduces lifetime and radiant output.

3. Bin Code System Explanation

The devices are sorted into performance bins based on key parameters to ensure consistency within a production lot. The bin code is marked on the packaging.

3.1 Forward Voltage (Vf) Binning

Devices are categorized into three voltage bins (V1, V2, V3) when measured at If=20mA. This allows designers to select LEDs with similar voltage drops for applications where current matching in parallel strings is critical, or to predict power supply requirements more accurately.

3.2 Radiant Flux (Φe) Binning

Optical output power is binned into six categories (R3 through R8), each representing a 2mW range from 14mW to 26mW (at If=20mA). This enables selection based on required UV intensity, allowing for brightness matching in multi-LED arrays.

3.3 Peak Wavelength (λp) Binning

The central emission wavelength is binned into three tight ranges (P3M2, P3N1, P3N2), each spanning 2.5nm around the 365nm target. This is crucial for applications sensitive to specific UV wavelengths, such as initiating particular photo-initiators in curing processes.

4. Performance Curve Analysis

The datasheet provides several characteristic curves that are essential for understanding device behavior under real-world conditions.

4.1 Relative Radiant Flux vs. Forward Current

This curve shows that the optical output (radiant flux) increases super-linearly with forward current. While driving at higher currents yields more UV output, it also increases power dissipation and junction temperature, which can lead to efficiency droop and accelerated aging. The typical test condition of 20mA represents a balanced operating point.

4.2 Forward Current vs. Forward Voltage (I-V Curve)

The I-V curve demonstrates the exponential relationship typical of a diode. The "knee" voltage is around 3V. This curve is vital for designing the current-limiting circuitry, whether using a simple resistor or a constant-current driver.

4.3 Relative Radiant Flux vs. Junction Temperature

This graph illustrates the negative temperature coefficient of the LED's output. As the junction temperature (Tj) rises, the radiant flux decreases. This underscores the critical importance of effective thermal management in the application to maintain consistent UV output over time and across operating conditions.

4.4 Relative Emission Spectrum

The spectrum plot shows a narrow, Gaussian-like distribution centered at the peak wavelength (e.g., ~365nm). The full width at half maximum (FWHM) is typical for a UV LED, indicating it emits a relatively pure band of UV-A light without significant visible or infrared leakage.

5. Mechanical and Packaging Information

5.1 Outline Dimensions

The device features an ultra-compact surface-mount package. Key dimensions (in millimeters) are: approximately 3.5mm in length, 3.2mm in width, and 1.9mm in height. The cathode is typically identified by a marker on the package. A detailed dimensioned drawing is provided in the source document with a standard tolerance of ±0.1mm.

5.2 Recommended PCB Attachment Pad Layout

A land pattern design is provided for infrared or vapor phase reflow soldering. This pattern is optimized to ensure proper solder joint formation, mechanical stability, and effective heat transfer from the LED's thermal pad (if present) or leads into the copper of the PCB. Following this recommendation is essential for reliability.

6. Assembly, Soldering, and Handling Guide

6.1 Reflow Soldering Profile

A detailed temperature vs. time profile is specified for lead-free (Pb-free) soldering processes. Key parameters include:

• Preheat: 150-200°C for up to 120 seconds.
• Peak Temperature: Maximum of 260°C, measured on the package body surface.
• Time Above Liquidus (TAL): Recommended to be within standard IPC guidelines.
• Cooling Rate: A rapid cool-down from peak temperature is not recommended, as thermal shock can induce stress.

The lowest possible soldering temperature that achieves a reliable joint is always desirable to minimize thermal stress on the LED.

6.2 Hand Soldering

If hand soldering is necessary, extreme care must be taken:

• Iron Temperature: Maximum 300°C.
• Soldering Time: Maximum 3 seconds per solder joint.
• Limit: Soldering should be performed only once. Re-work is strongly discouraged.

6.3 Cleaning

Unspecified chemical cleaners can damage the LED package. If cleaning after soldering is required, the only recommended method is to immerse the LED in ethyl alcohol or isopropyl alcohol at normal temperature for less than one minute.

6.4 Electrostatic Discharge (ESD) Precautions

UV LEDs are sensitive to electrostatic discharge and voltage surges. Proper ESD controls must be in place during handling and assembly:

• Use wrist straps or anti-static gloves.
• Ensure all equipment, tools, and workstations are properly grounded.
• Use conductive or dissipative mats.

6.5 Moisture Sensitivity and Storage

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

• Sealed Bag: Store at ≤30°C and ≤90% Relative Humidity (RH). Shelf life is one year in the original moisture-proof bag with desiccant.
• Opened Bag: After opening, store at ≤30°C and ≤60% RH. The "floor life" for soldering is 168 hours (7 days) from the time the bag is opened.
• Baking: If the humidity indicator card turns pink (≥10% RH) or the floor life is exceeded, the LEDs must be baked at 60°C for at least 48 hours before use. After baking, any remaining devices should be resealed in the original package with fresh desiccant.

7. Packaging and Ordering Information

7.1 Tape and Reel Specifications

The components are supplied on embossed carrier tape for automated assembly.

• Reel Size: Standard 7-inch (178mm) reel.
• Quantity per Reel: Typically 1500 pieces.
• Pocket Sealing: Empty pockets are sealed with cover tape.
• Missing Components: A maximum of two consecutive missing lamps is allowed per specification.
• Standard: Packaging conforms to EIA-481-1-B specifications.

Detailed dimensions for the carrier tape, cover tape, and reel are provided in the source document.

8. Application Design Considerations

8.1 Drive Method

An LED is a current-operated device. For reliable and consistent operation, it must be driven by a constant current source, not a constant voltage source. Driving with a voltage source risks thermal runaway and destruction. When connecting multiple LEDs, series connection is preferred as it ensures identical current through each device. If parallel connection is unavoidable, individual current-limiting resistors or separate drivers for each branch are strongly recommended to compensate for natural variations in forward voltage (Vf) and ensure intensity uniformity.

8.2 Heat Sinking and PCB Design

Given the thermal resistance (Rθj-s) of 53°C/W, the PCB acts as the primary heat sink. Use a PCB with adequate copper thickness (e.g., 2 oz). Design the copper pad under and around the LED to be as large as practically possible. Thermal vias connecting the pad to internal ground planes or bottom-side copper pours significantly improve heat dissipation. In high-power or high-ambient-temperature applications, consider additional thermal management such as metal-core PCBs (MCPCBs) or active cooling.

8.3 Optical Design

The 135-degree viewing angle provides a wide emission pattern. For applications requiring focused or collimated UV light, secondary optics such as lenses or reflectors must be used. The material of these optics must be transparent to UV-A light (e.g., specialized glasses, quartz, or UV-transparent plastics like acrylic). Standard optical materials may absorb UV radiation.

8.4 Safety and Reliability Disclaimer

The device is intended for use in ordinary electronic equipment. It is not designed or qualified for applications where failure could directly jeopardize life, health, or safety—such as in aviation, transportation, medical life-support systems, or nuclear control. For such applications, consultation with the component manufacturer and potentially using components specifically qualified for high-reliability (hi-rel) or medical use is mandatory.

9. Technical Comparison and Market Context

9.1 Advantages Over Conventional UV Sources

Compared to traditional UV sources like mercury-vapor lamps, this LED offers:

• Instant On/Off: No warm-up or cool-down time.
• Long Lifetime: Tens of thousands of hours vs. thousands for lamps.
• Energy Efficiency: Higher radiant efficiency, converting more electrical power into useful UV light.
• Compact Size and Design Flexibility: Enables integration into small, portable devices.
• Cool Operation: Minimal infrared (heat) radiation in the beam.
• Environmental Safety: Contains no mercury.
• Wavelength Specificity: Emits a narrow band, reducing unwanted side reactions or heating.

9.2 Design Trade-offs and Considerations

While powerful for its size, a single LED's total UV output is lower than that of a traditional lamp. Achieving equivalent total irradiance often requires an array of LEDs, which introduces design challenges in thermal management, current drive, and optical uniformity. The initial component cost per unit of optical power may be higher, but this is often offset by savings in energy, maintenance, and system lifetime.

10. Frequently Asked Questions (FAQ)

10.1 What is the recommended operating current?

The datasheet characterizes the device at 20mA, which is a common and reliable operating point. It can be driven up to its absolute maximum of 40mA, but this will increase junction temperature, potentially reduce lifetime, and decrease efficiency (lumens per watt). A detailed analysis of the thermal design is required before operating above 20mA.

10.2 Can I drive this LED directly from a 3.3V or 5V logic supply?

Not directly. The forward voltage ranges from 2.8V to 4.0V. A simple series resistor can be used with a 5V supply to limit current. For a 3.3V supply, if the LED's Vf is on the higher end (e.g., 3.6V-4.0V), there may not be enough voltage headroom, and a boost converter or dedicated LED driver IC would be necessary. Always use a constant current circuit for optimal performance and longevity.

10.3 How do I interpret the bin code on the bag?

The bin code is a combination of letters and numbers (e.g., V2R5P3N1) indicating the performance group for Forward Voltage (V), Radiant Flux (R), and Peak Wavelength (P). Refer to the bin code tables in Section 3 to understand the specific range of each parameter for your batch of components.

10.4 Is eye protection required?

Yes. UV-A radiation (315-400nm) is not as immediately damaging as UV-B or UV-C, but prolonged or high-intensity exposure can cause harm to eyes (photokeratitis) and skin (premature aging, increased cancer risk). Always use appropriate personal protective equipment (PPE) such as UV-blocking safety glasses or face shields when working with or testing these LEDs.

11. Practical Application Example

Scenario: Designing a small, portable UV curing spot light for adhesives.

1. Drive Circuit: Use a constant-current LED driver IC capable of delivering 20mA from a lithium-ion battery (3.7V nominal). The driver will compensate for battery voltage drop over time.
2. Thermal Design: Mount the LED on a small, dedicated metal-core PCB (MCPCB) star board. This MCPCB is then attached to the device's aluminum housing, which acts as a heat sink.
3. Optics: A simple quartz glass window protects the LED. For a more focused beam, a small collimating lens made of UV-transparent material could be added.
4. Control: Include a momentary switch and a timer circuit to control exposure duration, ensuring consistent cures and preventing overheating from continuous operation.

12. Technology Principles and Trends

12.1 Operating Principle

A UV LED operates on the same fundamental principle as a visible LED: electroluminescence in a semiconductor p-n junction. When a forward voltage is applied, electrons and holes recombine in the active region (typically made of aluminum gallium nitride - AlGaN for this wavelength). The energy released during this recombination is emitted as photons. The specific wavelength (color) of the light is determined by the bandgap energy of the semiconductor material. A bandgap corresponding to ~3.4 eV produces photons around 365nm (UV-A).

12.2 Industry Trends

The UV LED market is driven by several key trends:

• Increasing Output Power and Efficiency: Continuous improvements in epitaxial growth and chip design are pushing radiant flux higher and wall-plug efficiency up, enabling more powerful and compact systems.
• Shorter Wavelengths: Significant R&D is focused on developing efficient UV-B and UV-C LEDs (down to 250nm) for sterilization, water purification, and medical therapy, challenging traditional mercury lamps in new markets.
• Cost Reduction: Economies of scale and manufacturing process improvements are steadily reducing the cost per milliwatt of UV output, accelerating adoption across industries.
• System Integration: Trends include integrating drivers, sensors, and multiple LED chips into smart, modular UV emitter packages for easier design-in and more controlled application.