LTPL-C034UVG405 UV LED Datasheet - 405nm Peak Wavelength - 3.6V Typ. Forward Voltage - 4.4W Max Power - English Technical Document

1. Product Overview

The LTPL-C034UVG405 is a high-power ultraviolet (UV) light-emitting diode (LED) designed for demanding applications such as UV curing and other common UV processes. This product represents an energy-efficient alternative to conventional UV light sources, combining the long operational lifetime and reliability inherent to solid-state lighting with high radiant output. It enables greater design flexibility and creates new opportunities for solid-state UV technology to replace traditional UV systems.

1.1 Key Features

• Integrated Circuit (IC) compatible drive.
• Compliant with RoHS (Restriction of Hazardous Substances) directives and lead-free.
• Lower operational costs compared to conventional UV sources.
• Reduced maintenance requirements due to solid-state reliability.

2. Absolute Maximum Ratings

The following ratings define the limits beyond which permanent damage to the device may occur. All parameters are specified at an ambient temperature (Ta) of 25°C.

• DC Forward Current (If): 1000 mA
• Power Consumption (Po): 4.4 W
• Operating Temperature Range (Topr): -40°C to +85°C
• Storage Temperature Range (Tstg): -55°C to +100°C
• Junction Temperature (Tj): 125°C

Important Note: Operating the LED under reverse bias conditions for extended periods may result in component damage or failure.

3. Electro-Optical Characteristics

The following characteristics are measured at Ta=25°C and a forward current (If) of 700mA, which serves as a typical operating condition.

• Forward Voltage (Vf): Minimum 3.2V, Typical 3.6V, Maximum 4.4V.
• Radiant Flux (Φe): Minimum 1225 mW, Typical 1415 mW, Maximum 1805 mW. This is the total radiant power output measured with an integrating sphere.
• Peak Wavelength (λp): Minimum 400 nm, Maximum 410 nm.
• Viewing Angle (2θ1/2): Typically 130 degrees.
• Thermal Resistance, Junction to Solder Point (Rthjs): Typically 4.1 °C/W. Measurement tolerance is ±10%.

4. Bin Code System

The LEDs are classified into bins based on key parameters to ensure consistency in application. The bin code is marked on each packing bag.

4.1 Forward Voltage (Vf) Binning

• V1: 3.2V to 3.6V
• V2: 3.6V to 4.0V
• V3: 4.0V to 4.4V
• Tolerance: ±0.1V

4.2 Radiant Flux (mW) Binning

• ST: 1225 mW to 1325 mW
• TU: 1325 mW to 1430 mW
• UV: 1430 mW to 1545 mW
• VW: 1545 mW to 1670 mW
• WX: 1670 mW to 1805 mW
• Tolerance: ±10%

4.3 Peak Wavelength (Wp) Binning

• P4A: 400 nm to 405 nm
• P4B: 405 nm to 410 nm
• Tolerance: ±3 nm

5. Performance Curve Analysis

The following typical curves provide insight into the device's behavior under various conditions (25°C ambient unless noted).

5.1 Relative Radiant Flux vs. Forward Current

This curve shows that radiant output increases with forward current but may exhibit non-linear behavior at higher currents due to thermal effects and efficiency droop.

5.2 Relative Spectral Distribution

The spectral plot confirms the narrow emission band centered around the 405nm peak wavelength, which is characteristic of UV LEDs and suitable for curing specific photo-initiators.

5.3 Radiation Pattern (Viewing Angle)

The radiation characteristic plot illustrates the typical 130-degree viewing angle, showing the intensity distribution as a function of angle from the optical axis.

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

The I-V curve demonstrates the diode's exponential relationship between current and voltage, crucial for designing appropriate constant-current drivers.

5.5 Relative Radiant Flux vs. Junction Temperature

This graph highlights the negative impact of rising junction temperature on light output. Radiant flux decreases as temperature increases, emphasizing the need for effective thermal management.

5.6 Forward Current Derating Curve

This curve specifies the maximum allowable forward current as a function of the case temperature (Tc). To ensure reliability and prevent exceeding the maximum junction temperature, the drive current must be reduced when operating at higher ambient temperatures.

6. Reliability Test Summary

The device has undergone a comprehensive suite of reliability tests with zero failures reported from the sample sizes. Tests include:

• Low Temperature Operating Life (LTOL): -10°C case temperature, 700mA, 1000 hours.
• Room Temperature Operating Life (RTOL): 25°C, 1000mA, 1000 hours.
• High Temperature Operating Life (HTOL): 85°C case temperature, 700mA, 1000 hours.
• Wet High Temperature Operating Life (WHTOL): 60°C/90% RH, 700mA, 500 hours.
• Thermal Shock (TMSK): -40°C to 125°C, 100 cycles.
• Resistance to Reflow Soldering Heat: 260°C peak, 10 seconds, 2 cycles.
• Solderability Test: 245°C, 5 seconds, Pb-free solder.

Damage Criteria: A device is considered failed if, after testing, the forward voltage shifts by more than ±10% or the radiant flux degrades by more than -30% from initial values measured at the typical current.

7. Mechanical and Assembly Information

7.1 Outline Dimensions and PCB Pad Layout

The datasheet provides detailed mechanical drawings with dimensions in millimeters. Key notes include:

• General dimension tolerance: ±0.2mm.
• Lens height and ceramic substrate length/width tolerance: ±0.1mm.
• The thermal pad is electrically isolated (neutral) from the anode and cathode pads.
• A recommended printed circuit board (PCB) attachment pad layout is provided to ensure proper soldering and thermal conduction.

7.2 Soldering Guidelines

Reflow Soldering Profile: A recommended temperature profile is provided, with a peak body temperature not exceeding 260°C. A rapid cooling rate from peak temperature is not recommended.

Hand Soldering: Maximum 300°C for a maximum of 2 seconds, only once.

General Notes:

• All temperature references are for the top side of the package body.
• The lowest possible soldering temperature is desirable.
• Reflow soldering should be performed a maximum of three times.
• Dip soldering method is not recommended or guaranteed.

7.3 Packaging

The LEDs are supplied on tape and reel for automated assembly, compliant with EIA-481-1-B specifications.

• Tape Dimensions: Detailed drawings specify pocket size and tape construction.
• Reel Dimensions: Provided for 7-inch reels.
• Packing: Maximum 500 pieces per 7-inch reel. Empty pockets are sealed with cover tape. A maximum of two consecutive missing components is allowed.

8. Application Guidelines and Cautions

8.1 Drive Method

LEDs are current-operated devices. To ensure stable operation and long life, they must be driven by a constant current source, not a constant voltage source. An appropriate current-limiting circuit or dedicated LED driver IC is essential.

8.2 Thermal Management

Given the 4.4W maximum power dissipation and the sensitivity of output and lifetime to junction temperature, effective heat sinking is critical. The low thermal resistance (4.1 °C/W typ.) from junction to solder point facilitates heat transfer, but the overall system thermal path from the PCB to the ambient environment must be designed with care, especially when operating at high currents or in warm environments.

8.3 Cleaning

If cleaning is necessary after soldering, use only alcohol-based solvents such as isopropyl alcohol. The use of unspecified chemical cleaners may damage the LED package material.

9. Technical Comparison and Design Considerations

9.1 Advantages Over Conventional UV Sources

Compared to mercury-vapor lamps or other conventional UV technologies, this UV LED offers:

• Instant On/Off: No warm-up or cool-down time, enabling faster process cycles.
• Long Lifetime: Significantly longer operational life, reducing replacement frequency and maintenance costs.
• Energy Efficiency: Higher electrical-to-optical conversion efficiency, lowering operational power costs.
• Compact Size & Design Freedom: The small form factor allows for integration into tighter spaces and enables novel form factors for curing systems.
• Cooler Operation: Emits very little infrared radiation, reducing heat load on the target substrate.
• Environmental Safety: Contains no mercury, aligning with RoHS and other environmental regulations.

9.2 Design Considerations for UV Curing Systems

• Optical Design: Lenses or reflectors may be needed to focus the 130-degree beam into a more concentrated spot or line for efficient curing.
• Driver Selection: A constant-current driver capable of delivering up to 1000mA with appropriate dimming/pulsing capabilities is required. The driver must account for the forward voltage bin spread (3.2V to 4.4V).
• Heat Sink Design: The PCB should be designed with adequate thermal vias and copper area. For high-power arrays, an external aluminum heat sink is often necessary.
• Wavelength Matching: Ensure the 405nm peak wavelength is optimal for the photo-initiator used in the curing adhesive, ink, or coating.

10. Frequently Asked Questions (FAQs)

10.1 What is the typical operating current for this LED?

The electro-optical characteristics and bin codes are specified at a forward current (If) of 700mA, which is considered a typical operating point balancing output and longevity. The absolute maximum continuous current is 1000mA, but operation at this level requires excellent thermal management.

10.2 How is the radiant flux measured?

Radiant flux (in milliwatts) is the total optical power emitted by the LED, measured using an integrating sphere that captures light from all angles. This is different from luminous flux (lumens), which is weighted by the human eye's sensitivity and is not applicable for UV sources.

10.3 Can multiple LEDs be connected in series or parallel?

Series connection is generally preferred when using a constant-current driver, as it ensures identical current through each LED. Parallel connection is not recommended without individual current-balancing resistors for each LED string, due to variations in forward voltage (Vf) between devices which can lead to uneven current sharing and potential overdrive.

10.4 What is the impact of junction temperature on performance?

As shown in the performance curves, increasing junction temperature leads to a decrease in radiant flux output (efficiency droop) and can accelerate long-term degradation, reducing the device's lifetime. Maintaining a low junction temperature through proper heatsinking is paramount for consistent performance and reliability.

11. Operating Principle and Technology Trends

11.1 Basic Operating Principle

This UV LED is a semiconductor device. When a forward voltage is applied, electrons and holes recombine within the active region of the semiconductor chip, releasing energy in the form of photons. The specific materials (e.g., gallium nitride-based compounds) and quantum well structure are engineered to produce photons in the ultraviolet spectrum, specifically around 405nm.

11.2 Industry Trends

The UV LED market is driven by the replacement of mercury lamps across industries like printing, adhesives, coatings, and disinfection. Key trends include increasing output power (radiant flux) from single emitters, improvements in wall-plug efficiency (WPE), the development of shorter wavelength UVC LEDs for sterilization, and the reduction of cost per milliwatt. The LTPL-C034UVG405 fits into the trend of providing robust, high-power solutions for industrial curing applications.