LTPL-C034UVE365 UV LED Datasheet - 3.7x3.7x1.6mm - 3.7V - 2W - 365nm - English Technical Document

1. Product Overview

The LTPL-C034UVE365 is a high-performance ultraviolet (UV) light-emitting diode (LED) designed for solid-state lighting applications requiring UV-A spectrum emission. This product represents an energy-efficient and reliable alternative to conventional UV light sources, offering significant advantages in terms of operational lifetime, maintenance costs, and design flexibility. Its primary application is in UV curing processes, where consistent and powerful UV output is critical for initiating photochemical reactions in adhesives, inks, and coatings. The device is engineered to provide stable performance across a wide operating temperature range, making it suitable for integration into industrial and commercial equipment.

1.1 Key Features and Advantages

The LED incorporates several advanced features that contribute to its superior performance. It is fully compliant with RoHS (Restriction of Hazardous Substances) directives and is manufactured using lead-free processes, ensuring environmental safety. The device is designed to be compatible with integrated circuit (IC) drive systems, simplifying electronic control and integration. A major benefit is the significant reduction in both operating and maintenance costs compared to traditional UV lamps, as LEDs consume less power and have a much longer operational lifespan without the need for frequent bulb replacements.

2. Technical Specifications Deep Dive

This section provides a detailed, objective analysis of the device's key technical parameters as defined in its absolute maximum ratings and electro-optical characteristics.

2.1 Absolute Maximum Ratings

The device is specified to operate reliably within the following absolute limits, which should never be exceeded during application design. The maximum continuous forward current (If) is 500 mA. The maximum power consumption (Po) is 2 Watts. The allowable operating ambient temperature range (Topr) is from -40°C to +85°C, while the storage temperature range (Tstg) extends from -55°C to +100°C. The maximum permissible junction temperature (Tj) is 125°C. It is crucial to note that prolonged operation under reverse bias conditions can lead to permanent damage or failure of the component.

2.2 Electro-Optical Characteristics at 25°C

The core performance metrics are measured under standard test conditions with a forward current of 350mA and an ambient temperature of 25°C. The forward voltage (Vf) has a typical value of 3.7V, with a minimum of 2.8V and a maximum of 4.4V. The radiant flux (Φe), which is the total optical power output measured with an integrating sphere, has a typical value of 600 milliwatts (mW), ranging from a minimum of 470 mW to a maximum of 770 mW. The peak wavelength (Wp) is centered at 365nm, with a specified range from 360nm to 370nm. The viewing angle (2θ1/2), defining the angular spread of the emitted radiation, is typically 130 degrees. The thermal resistance from the junction to the solder point (Rthjs) is typically 9.1 °C/W, with a measurement tolerance of ±10%.

3. Bin Code System Explanation

The manufacturing process results in natural variations in key parameters. To ensure consistency for end-users, LEDs are sorted into performance bins. The bin code marked on the packaging allows designers to select components with tightly grouped characteristics.

3.1 Forward Voltage (Vf) Binning

LEDs are categorized into four voltage bins (V0 to V3) based on their forward voltage at 350mA. V0 bins have voltages between 2.8V and 3.2V, V1 between 3.2V and 3.6V, V2 between 3.6V and 4.0V, and V3 between 4.0V and 4.4V. The tolerance for this classification is ±0.1V.

3.2 Radiant Flux (Φe) Binning

Optical output power is binned into six categories labeled AB through FG. The AB bin covers 470-510 mW, BC covers 510-550 mW, CD covers 550-600 mW, DE covers 600-655 mW, EF covers 655-710 mW, and the FG bin covers the highest output range of 710-770 mW. The tolerance for radiant flux measurement is ±10%.

3.3 Peak Wavelength (Wp) Binning

The UV emission wavelength is binned into two groups. The P3M bin includes LEDs with a peak wavelength between 360nm and 365nm, while the P3N bin includes those between 365nm and 370nm. The tolerance for peak wavelength is ±3nm.

4. Performance Curve Analysis

Graphical data provides deeper insight into the device's behavior under varying conditions.

4.1 Relative Radiant Flux vs. Forward Current

The curve shows that radiant flux increases with forward current in a non-linear relationship. While output rises initially, the rate of increase diminishes at higher currents due to increased thermal effects and efficiency droop. This graph is essential for determining the optimal drive current to balance light output against efficiency and device heating.

4.2 Relative Spectral Distribution

This plot illustrates the spectral power distribution of the emitted UV light. It confirms the narrowband nature of the LED's output, with a dominant peak centered around 365nm and minimal emission at other wavelengths. The spectral purity is critical for applications sensitive to specific UV activation energies.

4.3 Radiation Pattern (Viewing Angle)

The polar radiation diagram visualizes the spatial distribution of light intensity. The typical 130-degree viewing angle indicates a wide, lambertian-like emission pattern. This characteristic is important for ensuring uniform illumination over a target area in curing or exposure applications.

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

This fundamental electrical characteristic shows the exponential relationship between current and voltage. The curve's shape is determined by the semiconductor's physics. The knee voltage, where current begins to rise sharply, is a key parameter for driver circuit design, typically around the lower end of the Vf specification.

4.5 Relative Radiant Flux vs. Junction Temperature

This critical curve demonstrates the negative impact of rising junction temperature on light output. As the junction temperature increases, the radiant flux decreases. The slope of this curve quantifies the thermal derating factor, which must be accounted for in thermal management system design to maintain consistent performance.

5. Mechanical and Package Information

5.1 Outline Dimensions

The device features a surface-mount package. Key dimensions include a body length and width of approximately 3.7mm, a lens height, and a ceramic substrate. All linear dimensions are in millimeters. Tolerances for most dimensions are ±0.2mm, while the lens height and ceramic length/width have tighter tolerances of ±0.1mm. The thermal pad on the bottom of the package is electrically isolated (neutral) from the anode and cathode electrical pads, allowing it to be used solely for heat sinking without causing electrical shorts.

5.2 Recommended PCB Attachment Pad Layout

A detailed diagram is provided for the recommended copper pad pattern on the printed circuit board (PCB). This layout is optimized for reliable soldering, proper thermal conduction to the board, and electrical connection. Adhering to this footprint is crucial for achieving good solder joint integrity and effective heat dissipation from the thermal pad to the PCB's ground plane or dedicated heatsink area.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Profile

A detailed time-temperature profile is specified for reflow soldering processes. Key parameters include a preheat stage, a temperature ramp, a peak temperature not exceeding 260°C measured on the package body surface, and a controlled cooling phase. A rapid cooling rate is not recommended. The profile is designed for lead-free (Pb-free) solder pastes. It is advised to perform reflow soldering a maximum of three times and to use the lowest possible temperature that achieves reliable soldering.

6.2 Hand Soldering Instructions

If hand soldering is necessary, the iron tip temperature should not exceed 300°C, and the contact time with any lead should be limited to a maximum of 2 seconds. This operation should be performed only once per solder joint to prevent thermal damage to the LED die and package materials.

6.3 Cleaning and Handling Cautions

If cleaning is required after soldering, only alcohol-based solvents such as isopropyl alcohol should be used. Harsh or unspecified chemical cleaners must be avoided as they can damage the LED lens or package. The device should be handled with care to avoid electrostatic discharge (ESD), although specific ESD ratings are not provided in this datasheet.

7. Packaging and Ordering Information

7.1 Tape and Reel Packaging

The LEDs are supplied in embossed carrier tape on reels for automated pick-and-place assembly. The tape dimensions and pocket spacing conform to EIA-481-1-B specifications. The reel is a standard 7-inch diameter, capable of holding a maximum of 500 pieces. The tape is sealed with a top cover to protect the components. Quality specifications allow for a maximum of two consecutive missing components in the tape.

8. Reliability and Testing

A comprehensive reliability test plan validates the long-term performance and robustness of the LED. Tests include Low Temperature Operating Life (LTOL at -30°C), Room Temperature Operating Life (RTOL), High Temperature Operating Life (HTOL at 85°C), Thermal Shock cycling between -40°C and 125°C, High Temperature Storage, Resistance to Soldering Heat (simulating reflow), and Solderability testing. All tests were performed on sample sizes with zero failures reported, indicating high reliability. The judgment criteria for failure are defined as a change in forward voltage (Vf) beyond ±10% of its initial value or a change in radiant flux (Φe) beyond ±30% of its initial value when measured at the typical operating current.

9. Application Suggestions and Design Considerations

9.1 Typical Application Scenarios

The primary application for this 365nm UV LED is in UV curing systems for adhesives, inks, resins, and coatings in manufacturing, printing, and electronics assembly. Other potential uses include fluorescence excitation, counterfeit detection, medical and scientific instrumentation, and air/water purification systems where UV-A light is effective.

9.2 Critical Design Considerations

Thermal Management: This is the single most important design factor. The typical thermal resistance of 9.1 °C/W means that for every watt of power dissipated, the junction temperature will rise approximately 9.1°C above the solder point temperature. An effective heatsink connected to the thermal pad is mandatory to keep the junction temperature below 125°C, especially when operating at or near the maximum current of 350-500mA. Poor thermal design will lead to rapid lumen depreciation and reduced lifespan.

Drive Current: The LED should be driven by a constant current source, not a constant voltage source, to ensure stable light output and prevent thermal runaway. The recommended operating point is 350mA for optimal efficiency and lifetime, though it can be pulsed at higher currents with appropriate duty cycles.

Optical Design: The wide 130-degree viewing angle may require secondary optics (lenses or reflectors) to collimate or focus the UV light onto the target area for efficient curing or exposure.

Material Compatibility: Prolonged exposure to UV radiation can degrade many plastics and polymers. Ensure that surrounding materials in the assembly are UV-stable.

10. Technical Comparison and Differentiation

Compared to traditional UV light sources like mercury-vapor lamps, this LED offers distinct advantages: instant on/off capability with no warm-up time, significantly longer operational lifetime (tens of thousands of hours), no hazardous mercury content, compact size enabling flexible form factors, and lower total energy consumption. Within the UV LED market, the key differentiators for this specific part are its combination of relatively high radiant flux (600mW typical) at 365nm, its robust package with a dedicated thermal pad for superior heat dissipation, and its comprehensive binning system ensuring predictable performance for high-volume production.

11. Frequently Asked Questions (Based on Technical Parameters)

Q: What is the difference between radiant flux (mW) and luminous flux (lm)?

A: Radiant flux measures total optical power in watts, which is appropriate for UV LEDs where the human eye's sensitivity (photopic response) is not relevant. Luminous flux measures perceived brightness weighted by the human eye's sensitivity and is used for visible light LEDs.

Q: Can I drive this LED directly from a 5V or 12V supply?

A: No. The LED requires a constant current driver circuit. Connecting it directly to a voltage source will result in excessive current flow, immediate overheating, and destruction of the device due to the diode's negative temperature coefficient.

Q: How do I interpret the bin codes when ordering?

A: Specify the required combination of Vf, Φe, and Wp bins based on your application's needs for voltage consistency, light output level, and precise wavelength. For example, an order might specify bins V1, DE, P3N for LEDs with Vf~3.4V, Φe~625mW, and Wp~367.5nm.

Q: What heatsink is required?

A: The required heatsink thermal resistance depends on your operating current, ambient temperature, and target junction temperature. Using the formula Tj = Ta + (Po * Rthjs) + (Po * Rth_heatsink), you can calculate the necessary heatsink performance. Po is the dissipated power (If * Vf).

12. Design and Usage Case Study

Scenario: Designing a PCB Spot Curing System.

A manufacturer needs to cure small dots of UV adhesive on a circuit board assembly line. A design using four LTPL-C034UVE365 LEDs is proposed. Each LED is driven at 350mA constant current by a dedicated driver IC, resulting in a forward voltage of approximately 3.7V and a radiant flux of 600mW per LED. The LEDs are mounted on a small aluminum core PCB that acts as a heatsink. The calculated power dissipation per LED is about 1.3W (0.35A * 3.7V). With the LED's Rthjs of 9.1 °C/W and an estimated heatsink (PCB) thermal resistance of 15 °C/W to ambient, the total thermal resistance is 24.1 °C/W. In a 40°C ambient environment, the junction temperature would be Tj = 40°C + (1.3W * 24.1 °C/W) = 71.3°C, which is safely below the 125°C maximum. The four LEDs are arranged in a square pattern with simple reflectors to concentrate the combined 2.4W of UV power onto a 5mm diameter spot, providing sufficient irradiance for a fast cure time of 2-3 seconds. The system benefits from instant operation, long maintenance intervals, and low power consumption compared to a traditional mercury lamp system.

13. Operating Principle Introduction

This UV LED is a semiconductor device based on aluminum gallium nitride (AlGaN) material systems. When a forward voltage is applied across the p-n junction, electrons and holes are injected into the active region. These charge carriers recombine, releasing energy in the form of photons. The specific wavelength of these photons (365nm, in the UV-A band) is determined by the bandgap energy of the semiconductor materials used in the active layer. The wide-bandgap nature of AlGaN alloys enables the emission of high-energy ultraviolet light. The generated light escapes through a transparent epoxy lens designed to protect the semiconductor die and shape the radiation pattern.

14. Technology Trends and Developments

The field of UV LEDs is rapidly evolving. Key trends include continuous improvements in wall-plug efficiency (optical power out / electrical power in), which reduces heat generation and energy costs. There is ongoing development to increase the maximum output power (radiant flux) of single-die emitters and multi-chip packages. Research is also focused on extending the wavelength range further into the UV-C band (200-280nm) for germicidal applications, though efficiency challenges remain. Another trend is the improvement of device lifetime and reliability under high-temperature, high-current operating conditions, which is critical for industrial adoption. Packaging technology is advancing to provide even lower thermal resistance and more robust interfaces for harsh environments. As manufacturing volumes increase and efficiencies improve, the cost per milliwatt of UV output continues to decrease, making LED-based solutions economically viable for an ever-wider range of applications previously dominated by traditional UV lamps.