LTPL-C16FUVM405 UV LED Datasheet - 3.2x1.6x1.9mm - 3.1V - 22mW - 405nm - 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 an energy-efficient and ultra-compact light source that merges the long operational lifetime and high reliability inherent to Light Emitting Diodes (LEDs) with performance levels suitable for displacing conventional UV lighting systems. Its miniature form factor provides designers with considerable freedom in integrating UV light sources into space-constrained applications, enabling new possibilities across various industries.

1.1 Key Features and Advantages

The device incorporates several design features that enhance its manufacturability and performance:

• Automated Assembly Compatibility: The package is fully compatible with standard automatic pick-and-place equipment, facilitating high-volume, cost-effective production.
• Reflow Soldering Compatibility: It is designed to withstand both infrared (IR) and vapor phase reflow soldering processes, which are standard in surface-mount technology (SMT) assembly lines.
• Standardized Package: The component conforms to EIA (Electronic Industries Alliance) standard package outlines, ensuring broad compatibility with industry design rules and assembly processes.
• Direct Drive Capability: The LED is I.C. (Integrated Circuit) compatible, meaning it can be driven directly by the output of many logic circuits or drivers without requiring complex interfacing components.
• Environmental Compliance: The product is manufactured to meet green product standards and is lead-free (Pb-free) in accordance with the Restriction of Hazardous Substances (RoHS) directive.

1.2 Target Applications

This 405nm UV LED is specifically targeted at applications requiring a compact, reliable source of near-ultraviolet light. Primary application areas include:

• UV Curing: Instantaneous curing of adhesives, coatings, and inks in manufacturing and printing processes.
• UV Marking and Coding: Facilitating photochemical reactions for marking or coding on various materials.
• UV Gluing: Activating light-cure adhesives for bonding in electronics, medical devices, and optics.
• Printing Ink Drying: Accelerating the drying and setting of specialized printing inks.

2. Technical Parameters: In-Depth Objective Interpretation

This section provides a detailed analysis of the device's operational limits and performance characteristics under standard test conditions.

2.1 Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. Operation at or near these limits is not recommended for extended periods. All ratings are specified at an ambient temperature (Ta) of 25°C.

• Power Dissipation (Po): 160 mW. This is the maximum total 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. The device has a built-in Zener protection diode; exceeding this voltage in reverse bias may cause damage.
• Operating Temperature Range (Topr): -40°C to +85°C. The ambient temperature range over which the device is specified to operate.
• Storage Temperature Range (Tstg): -40°C to +100°C.
• Junction Temperature (Tj): 100°C. The maximum permissible temperature of the semiconductor chip itself.

2.2 Electro-Optical Characteristics

These parameters define the typical performance of the LED under normal operating conditions (Ta=25°C, If=20mA).

• Radiant Flux (Φe): 22 mW (Typical), with a range from 16 mW (Min) to 28 mW (Max). This is the total optical power output in the UV spectrum, measured according to the CAS140B standard with a ±10% measurement tolerance. It is the key metric for UV curing efficacy.
• Viewing Angle (2θ1/2): 135° (Typical). This wide viewing angle indicates a Lambertian emission pattern, suitable for illuminating larger areas or targets from a short distance.
• Peak Wavelength (λp): 405 nm (Typical), ranging from 400 nm to 410 nm. This places the emission in the near-UV (UVA) spectrum. Measurement tolerance is ±3 nm.
• Forward Voltage (Vf): 3.1 V (Typical), ranging from 2.8 V to 4.0 V at 20mA. Measurement tolerance is ±0.1V. This parameter is binned for production consistency.
• Reverse Voltage (Vr): 1.2 V (Max) at a reverse current (Ir) of 10µA. Critical Note: This test is solely to verify the Zener protection function. The LED is not designed for operation under reverse bias. Sustained reverse current can lead to device failure.

2.3 Handling and ESD Precautions

The device is sensitive to electrostatic discharge (ESD) and electrical surges. Proper handling procedures are mandatory: use of grounded wrist straps or anti-static gloves, and ensuring all equipment and workstations are properly grounded.

3. Binning System Explanation

To ensure consistent performance in application, LEDs are sorted (binned) based on key parameters post-manufacturing. The bin code is marked on the packaging.

3.1 Forward Voltage (Vf) Binning

LEDs are categorized into three voltage bins at a test current of 20mA:
V1: 2.8V - 3.2V
V2: 3.2V - 3.6V
V3: 3.6V - 4.0V

3.2 Radiant Flux (Φe) Binning

Optical output power is sorted into six bins at 20mA:
R4: 16 mW - 18 mW
R5: 18 mW - 20 mW
R6: 20 mW - 22 mW
R7: 22 mW - 24 mW
R8: 24 mW - 26 mW
R9: 26 mW - 28 mW

3.3 Peak Wavelength (λp) Binning

The emission wavelength is sorted into two primary bins:
P4A: 400 nm - 405 nm
P4B: 405 nm - 410 nm

This binning allows designers to select LEDs matched for specific voltage requirements, optical power needs, and precise spectral output, which is crucial for applications with tight photochemical reaction thresholds.

4. Performance Curve Analysis

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

4.1 Relative Radiant Flux vs. Forward Current

This curve shows that the optical output (Φe) is approximately linear with forward current (If) within the recommended operating range. Driving the LED above the typical 20mA will increase output but also increase power dissipation and junction temperature, which must be managed through thermal design.

4.2 Forward Current vs. Forward Voltage (IV Curve)

The IV curve demonstrates the exponential relationship typical of a diode. The forward voltage has a negative temperature coefficient, meaning Vf will decrease slightly as the junction temperature rises under constant current operation.

4.3 Relative Radiant Flux vs. Junction Temperature

This is one of the most critical curves for design. It shows the derating of optical output as the junction temperature (Tj) increases. UV LEDs are particularly sensitive to temperature. Maintaining a low Tj through effective PCB layout, thermal vias, and possibly heatsinking is paramount to ensuring stable, long-term optical output and device reliability.

4.4 Relative Emission Spectrum

The spectral distribution curve confirms the peak emission at ~405nm with a typical spectral width (Full Width at Half Maximum). This narrowband emission is ideal for targeting specific photoinitiators in curing applications.

5. Mechanical and Packaging Information

5.1 Outline Dimensions

The package is an ultra-compact surface-mount device. Key dimensions (in millimeters, ±0.1mm tolerance) are approximately 3.2mm in length, 1.6mm in width, and 1.9mm in height. The datasheet includes a detailed dimensional drawing showing pad locations, lens shape, and polarity indicator (typically a cathode mark).

5.2 Recommended PCB Attachment Pad Layout

A land pattern design is provided for infrared or vapor phase reflow soldering. This pattern is crucial for achieving a reliable solder joint, ensuring proper self-alignment during reflow, and facilitating heat transfer away from the LED die into the PCB.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Profile

A detailed reflow profile is specified for lead-free (Pb-free) solder processes. Key parameters include:
- Preheat: 150-200°C for up to 120 seconds.
- Peak Temperature: Maximum of 260°C.
- Time Above Liquidus: Recommended to be 10 seconds maximum, and reflow should not be performed more than twice.
The profile emphasizes a gradual ramp-up and cool-down to minimize thermal shock. The lowest possible soldering temperature that achieves a reliable joint is always recommended.

6.2 Hand Soldering

If hand soldering is necessary, a soldering iron tip temperature not exceeding 300°C should be used, with contact time limited to a maximum of 3 seconds per solder joint. This should be performed only once.

6.3 Cleaning

If post-assembly cleaning is required, only specified chemicals should be used. Immersing the LED in ethyl alcohol or isopropyl alcohol at room temperature for less than one minute is acceptable. Unspecified chemicals may damage the silicone lens or package material.

6.4 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% RH. Use within one year of the bag seal date.
- Opened Bag: Store at ≤30°C and ≤60% RH. The components must undergo soldering within 168 hours (7 days) of exposure to the factory floor environment. If the humidity indicator card turns pink (indicating >10% RH) or the exposure time is exceeded, a bake-out at 60°C for at least 48 hours is required before use. Reseal any unused parts 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.
- Tape Dimensions: Detailed drawings specify pocket pitch, width, and cover tape dimensions.
- Reel: Standard 7-inch (178mm) reel.
- Quantity: Typically 1500 pieces per reel.
- Quality: Conforms to EIA-481-1-B specifications, with a maximum of two consecutive missing components allowed.

8. Application Design and Considerations

8.1 Drive Circuit Design

Critical Principle: An LED is a current-operated device, not a voltage-operated one. To ensure uniform brightness and longevity, it must be driven by a controlled current source.
- Constant Current Drive: The recommended method is using a dedicated LED driver IC or a circuit that provides a stable constant current.
- Current Limiting Resistor: For simple applications with a stable voltage supply (Vcc), a series resistor (R = (Vcc - Vf) / If) is the minimum requirement. This is essential when connecting multiple LEDs in parallel to prevent current hogging by the LED with the lowest Vf. Each parallel branch should ideally have its own current-limiting resistor.

8.2 Thermal Management

Effective heat sinking is non-negotiable for performance and reliability. Design considerations include:
- Using a PCB with sufficient copper area (thermal pads) connected to the LED's thermal pad.
- Implementing thermal vias under the LED's footprint to conduct heat to inner or bottom copper layers.
- Ensuring the overall system design allows for heat dissipation to prevent the junction temperature from exceeding its maximum rating, especially when operating at higher currents or in elevated ambient temperatures.

8.3 Application Scope and Safety

The device is intended for standard commercial and industrial electronic equipment. It is not designed or qualified for safety-critical applications where failure could risk life or health (e.g., aviation control, medical life-support, transportation safety systems). For such applications, consultation with the manufacturer for specialized products is required.

9. Technical Comparison and Differentiation

The LTPL-C16FUVM405 differentiates itself in the UV LED market through its combination of attributes:
- Ultra-Compact Size: Its miniature 3.2x1.6mm footprint enables integration into very small products or dense arrays.
- High Efficiency: Delivering up to 28mW of optical power from a low 20mA drive current represents good electrical-to-optical conversion efficiency for its class.
- Wide Viewing Angle: The 135° viewing angle provides broad, even illumination ideal for curing or exposing larger areas without complex optics.
- Robust Packaging: Compatibility with standard SMT reflow processes and MSL3 rating make it suitable for mainstream, high-volume electronics manufacturing.

10. Frequently Asked Questions (Based on Technical Parameters)

Q1: Can I drive this LED directly from a 5V microcontroller pin?
A: No. A 5V supply with a simple series resistor calculation (R = (5V - 3.1V) / 0.02A = 95Ω) might seem feasible, but it is not recommended. The microcontroller pin has a current sourcing limit (often 20-40mA max total for the chip) and is not a stable voltage source under load. Use a dedicated driver circuit or transistor.

Q2: Why is the reverse voltage rating important if I shouldn't operate it in reverse?
A: The rating indicates the level of built-in protection against accidental reverse connection during assembly or testing. It defines the threshold before the internal Zener diode conducts heavily, potentially protecting the LED chip from immediate failure due to a wiring mistake, but sustained reverse bias is harmful.

Q3: My curing process seems slow. Can I increase the drive current above 20mA?
A: You can, but you must operate within the Absolute Maximum Rating of 40mA. Increasing current increases optical output but also increases heat generation exponentially (Power = Vf * If). You must perform thorough thermal analysis and design to ensure the junction temperature (Tj) stays below 100°C. Driving at higher currents without thermal management will reduce output (due to thermal derating), shorten lifespan, and may cause premature failure.

Q4: What is the difference between Radiant Flux (mW) and Luminous Flux (lm)?
A: Radiant flux measures total optical power across all wavelengths (Watts). Luminous flux measures perceived brightness by the human eye (lumens), weighted by the photopic response curve. Since this is a UV LED emitting light invisible to humans, its performance is correctly specified in Radiant Flux (mW), which correlates directly to its effectiveness in photochemical processes like curing.

11. Practical Design and Usage Case Study

Scenario: Designing a compact UV curing station for a desktop 3D printer resin tank.
1. Array Design: Multiple LTPL-C16FUVM405 LEDs would be arranged in a grid on a PCB to uniformly illuminate the tank area. Their wide 135° viewing angle reduces the number of LEDs needed compared to narrower-angle devices.
2. Drive Circuit: A constant-current LED driver IC would be selected to power the array, capable of delivering a stable 20mA per LED string. LEDs would be connected in a series-parallel configuration appropriate for the driver's voltage and current compliance limits.
3. Thermal Design: The PCB would be fabricated on a 1.6mm FR4 board with 2oz copper. A large continuous copper pour on the top and bottom layers, connected by an array of thermal vias under each LED footprint, would act as the primary heatsink. The PCB might be mounted to an aluminum chassis for additional cooling.
4. Optics: While the wide angle is beneficial, a simple diffuser might be placed over the array to ensure perfectly even illumination across the curing surface.
5. Control: The driver IC would be controlled by the system's microcontroller to pulse or dim the UV array as required by the curing recipe, managing exposure dose.

12. Operating Principle and Technology Trends

12.1 Basic Operating Principle

A Light Emitting Diode (LED) is a semiconductor p-n junction diode. When a forward voltage is applied, electrons from the n-type region and holes from the p-type region are injected into the active region. When these charge carriers recombine, they release energy. In this specific device, the semiconductor material (likely based on indium gallium nitride - InGaN) is engineered so that this energy is released as photons in the near-ultraviolet spectrum, with a peak wavelength of approximately 405 nanometers. The built-in Zener diode provides a controlled breakdown path for reverse voltages, offering basic protection for the delicate LED junction.

12.2 Industry Trends

The solid-state lighting industry, including UV LEDs, continues to evolve along several key trajectories:
- Increased Efficiency (WPE - Wall-Plug Efficiency): Ongoing research aims to extract more optical power (mW) from the same electrical input power (mW), reducing heat generation and energy consumption.
- Higher Power Density: Developing packages and chip technologies that can handle higher drive currents and dissipate more heat, enabling smaller LEDs to deliver more UV power.
- Shorter Wavelengths: While this product is in the UVA band (405nm), significant R&D effort is focused on producing reliable and efficient LEDs deeper into the UV spectrum (UVB and UVC) for sterilization, purification, and advanced medical applications.
- Improved Thermal Packaging: Advancements in package materials (e.g., ceramic substrates) and thermal interface technologies to lower thermal resistance from the junction to the ambient environment, which is critical for maintaining performance and lifetime.
- Intelligent Integration: Trends toward combining UV LEDs with onboard sensors (for dose monitoring) or drivers for smarter, more controllable light engines.