LTPL-C036UVG395 UV LED Datasheet - 395nm Peak Wavelength - 3.7V Typ. - 4.4W Max. - English Technical Document

1. Product Overview

The product series represents an advanced, energy-efficient light source engineered for ultraviolet (UV) curing processes and other common UV applications. It successfully merges the long operational lifetime and high reliability inherent to Light Emitting Diode (LED) technology with the intensity levels traditionally associated with conventional UV light sources. This combination provides significant design flexibility and opens new avenues for solid-state UV lighting to replace older, less efficient UV technologies.

1.1 Key Features and Advantages

• Integrated Circuit (I.C.) Compatibility: Designed for easy integration into modern electronic circuits and control systems.
• Environmental Compliance: The product is fully compliant with the Restriction of Hazardous Substances (RoHS) directive and is manufactured using lead-free (Pb-free) processes.
• Operational Cost Reduction: Offers lower overall operating costs compared to traditional UV sources due to higher electrical efficiency and reduced energy consumption.
• Maintenance Cost Savings: The solid-state nature of LEDs leads to significantly reduced maintenance requirements and associated costs over the product's lifespan.
• Design Freedom: Enables new form factors and application designs previously constrained by conventional UV lamp technology.

2. Technical Specifications Deep Dive

2.1 Absolute Maximum Ratings

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

• DC Forward Current (If): 1000 mA (Maximum)
• Power Consumption (Po): 4.4 W (Maximum)
• Operating Temperature Range (Topr): -40°C to +85°C
• Storage Temperature Range (Tstg): -55°C to +100°C
• Junction Temperature (Tj): 110°C (Maximum)

Critical Note: Prolonged operation of the LED under reverse bias conditions can lead to component degradation or catastrophic failure. Proper circuit protection is essential.

2.2 Electro-Optical Characteristics (Ta=25°C)

These parameters are measured under standard test conditions (If = 700mA, Ta=25°C) and define the core performance of the LED.

• Forward Voltage (Vf): Typical value is 3.7V, with a range from 2.8V (Min.) to 4.4V (Max.).
• Radiant Flux (Φe): The total optical power output in the UV spectrum. Typical value is 1240 mW, ranging from a minimum of 1050 mW to a maximum of 1545 mW.
• Peak Wavelength (λp): The wavelength at which the spectral emission is strongest. For this device, it is specified between 390 nm (Min.) and 400 nm (Max.), centered around 395nm.
• Viewing Angle (2θ1/2): The full angle at which the radiant intensity is half of the maximum intensity (typically at 0°). The typical value is 55°.
• Thermal Resistance (Rthjs): This parameter, typically 5.0 °C/W, quantifies the resistance to heat flow from the semiconductor junction to the solder point. A lower value indicates better heat dissipation capability.

3. Binning System Explanation

To ensure consistency in production, LEDs are sorted into performance bins. The bin code is marked on each packaging bag.

3.1 Forward Voltage (Vf) Binning

LEDs are categorized based on their forward voltage drop at 700mA.
V0: 2.8V - 3.2V
V1: 3.2V - 3.6V
V2: 3.6V - 4.0V
V3: 4.0V - 4.4V
Tolerance: ±0.1V

3.2 Radiant Flux (mW) Binning

LEDs are sorted by their optical power output at 700mA.
PR: 1050 mW - 1135 mW
RS: 1135 mW - 1225 mW
ST: 1225 mW - 1325 mW
TU: 1325 mW - 1430 mW
UV: 1430 mW - 1545 mW
Tolerance: ±10%

3.3 Peak Wavelength (Wp) Binning

LEDs are grouped according to their peak emission wavelength.
P3T: 390 nm - 395 nm
P3U: 395 nm - 400 nm
Tolerance: ±3nm

4. Performance Curve Analysis

4.1 Relative Radiant Flux vs. Forward Current

This curve shows that the optical output (radiant flux) increases with forward current but not linearly. It tends to saturate at higher currents due to increased junction temperature and efficiency droop. Designers must select an operating current that balances output intensity with efficiency and longevity.

4.2 Relative Spectral Distribution

The spectral plot confirms the narrowband UV emission centered around 395nm. This is characteristic of InGaN-based UV LEDs. The narrow spectrum is advantageous for applications requiring specific wavelength activation, such as certain photo-initiators in UV-curable resins.

4.3 Radiation Pattern (Viewing Angle)

The radiation characteristic plot illustrates the spatial distribution of light. The typical 55° viewing angle indicates a moderately wide beam, suitable for applications requiring area illumination rather than a highly focused spot.

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

This fundamental curve demonstrates the exponential relationship typical of a diode. The forward voltage increases with current. The curve's slope in the operating region is related to the device's dynamic resistance.

4.5 Relative Radiant Flux vs. Junction Temperature

This is a critical curve for thermal management. It shows that the optical output of the LED decreases as the junction temperature (Tj) rises. Effective heat sinking is paramount to maintain stable, high output and to ensure long-term reliability.

5. Mechanical and Package Information

5.1 Outline Dimensions

The device features a surface-mount package. Key dimensional notes include:
- All linear dimensions are in millimeters (mm).
- General dimensional tolerance is ±0.2mm.
- Lens height and ceramic substrate length/width have a tighter tolerance of ±0.1mm.
- The thermal pad (often the central pad underneath) is electrically isolated (neutral) from the anode and cathode electrical pads. This allows it to be connected to a ground plane or heatsink for thermal management without creating an electrical short.

5.2 Recommended PCB Attachment Pad Layout

A recommended footprint is provided for printed circuit board (PCB) design. This includes the size and spacing for the anode, cathode, and thermal pad. Following this layout ensures proper soldering, electrical connection, and most importantly, optimal thermal transfer from the LED junction to the PCB.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Profile

A detailed temperature vs. time profile is provided for reflow soldering. Key parameters include:
- Preheat ramp rate.
- Soak (preheat) temperature and time.
- Peak reflow temperature (must not exceed the LED's maximum rated temperature).
- Cooling rate. A rapid cooling process is not recommended as it can induce thermal stress.
Important Notes:
1. All temperature specifications refer to the top surface of the LED package.
2. The profile may need adjustment based on the specific solder paste used.
3. The lowest possible soldering temperature that achieves a reliable joint is always desirable to minimize thermal stress on the LED.
4. Hand soldering, if necessary, should be limited to a maximum iron temperature of 300°C for no more than 2 seconds, and performed only once.
5. Reflow soldering should not be performed more than three times on the same device.

6.2 Cleaning

If cleaning is required after soldering, only alcohol-based solvents like isopropyl alcohol (IPA) should be used. Unspecified or aggressive chemical cleaners can damage the LED's package material, lens, or internal components.

6.3 Drive Method

LEDs are current-driven devices. To ensure uniform brightness when multiple LEDs are connected in parallel within a circuit, it is strongly recommended to use a individual current-limiting resistor in series with each LED. This compensates for minor variations in the forward voltage (Vf) between individual devices, preventing current hogging and ensuring consistent performance and longevity across the array.

7. Packaging and Handling

7.1 Tape and Reel Specifications

The LEDs are supplied in industry-standard embossed carrier tape and reels for automated pick-and-place assembly.
- The tape dimensions (pocket size, pitch) are specified.
- Reel dimensions (7-inch diameter) are provided, with a maximum capacity of 500 pieces per reel.
- Empty pockets in the tape are sealed with a cover tape.
- The packaging conforms to EIA-481-1-B specifications.
- A maximum of two consecutive missing components (empty pockets) is allowed per the packaging standard.

8. Reliability Data

A comprehensive reliability test plan was executed, demonstrating the robustness of the product. All tests showed zero failures out of ten samples, indicating high reliability under various stress conditions.

• Low Temperature Operating Life (LTOL): -10°C case temperature, 700mA for 1000 hours.
• Room Temperature Operating Life (RTOL): 25°C ambient, 1000mA for 1000 hours.
• High Temperature Operating Life (HTOL): 85°C case temperature, 60mA for 1000 hours.
• Wet High Temperature Operating Life (WHTOL): 60°C / 90% Relative Humidity, 350mA for 500 hours.
• Thermal Shock (TMSK): -40°C to +125°C, 100 cycles.
• High Temperature Storage: 100°C ambient for 1000 hours.

Failure Criteria: A device is considered a failure if, after testing, its forward voltage (Vf) shifts by more than ±10% or its radiant flux (Φe) degrades by more than ±15% from the initial typical values.

9. Application Notes and Design Considerations

9.1 Primary Application: UV Curing

This LED is ideally suited for UV curing applications, which include:
- Adhesive curing (e.g., in electronics assembly, medical devices).
- Ink and coating curing (e.g., printing, conformal coatings).
- Resin curing for 3D printing (vat polymerization).
The 395nm wavelength is effective for initiating a wide range of common photo-initiators used in industrial formulations.

9.2 Other UV Applications

- Currency and document verification.
- Non-destructive inspection (fluorescent penetrant inspection).
- Medical and cosmetic phototherapy (under appropriate medical guidance and device certification).
- Air and water purification (when combined with appropriate catalysts).

9.3 Critical Design Considerations

1. Thermal Management: This is the single most important factor for performance and lifetime. The low thermal resistance (5°C/W) is only effective if the LED is properly mounted to an adequate heatsink. The junction temperature (Tj) must be kept as low as possible, ideally well below the maximum rating of 110°C.
2. Constant Current Drive: Always use a constant current LED driver, not a constant voltage source. This ensures stable light output and protects the LED from thermal runaway.
3. ESD Protection: While not explicitly stated for this power LED, handling with appropriate Electrostatic Discharge (ESD) precautions is considered good practice for all semiconductor devices.
4. Optical Design: Consider secondary optics (lenses, reflectors) if a specific beam pattern is required, as the native viewing angle is 55°.

10. Technical Comparison and Market Context

This LED represents the evolution of UV light sources. Compared to traditional technologies like mercury-vapor lamps, it offers distinct advantages:
- Instant On/Off: No warm-up or cool-down time.
- Long Lifetime: Tens of thousands of hours vs. thousands for lamps.
- Efficiency: Higher electrical-to-optical conversion efficiency, reducing energy costs.
- Compact Size & Design Flexibility: Enables smaller, more innovative product designs.
- Eco-Friendly: Contains no mercury, is RoHS compliant, and reduces hazardous waste.
- Spectral Purity: Emits a narrow peak at ~395nm without the broad spectrum and infrared (heat) radiation of lamps, which can be beneficial for sensitive substrates.

11. Frequently Asked Questions (FAQs)

Q1: What is the typical operating current for this LED?
A1: While it can handle up to 1000mA, the electro-optical characteristics and binning are specified at 700mA, which is a common recommended operating point balancing output and efficiency.

Q2: Why is the thermal pad electrically neutral?
A2: This allows designers to connect the pad directly to a large copper area (thermal ground) on the PCB for maximum heat dissipation without worrying about creating an electrical short circuit with the anode or cathode.

Q3: Can I drive multiple LEDs in parallel from one current source?
A3: It is not recommended without individual series resistors for each LED. Due to natural variations in Vf, LEDs in parallel will not share current evenly, leading to brightness mismatch and potential over-current in some devices.

Q4: How do I interpret the bin code?
A4: The code on the bag (e.g., V1/ST/P3U) tells you the specific performance group for that LED: its Forward Voltage bin (V1), its Radiant Flux bin (ST), and its Peak Wavelength bin (P3U). This allows for precise selection in applications requiring tight parameter matching.

12. Operating Principles and Technology

This is a semiconductor-based light source. When a forward voltage exceeding its bandgap energy is applied, electrons and holes recombine in the active region of the chip, releasing energy in the form of photons (light). The specific wavelength of 395nm is achieved by engineering the bandgap of the semiconductor materials used, typically aluminum gallium nitride (AlGaN) or indium gallium nitride (InGaN) with specific compositions. The UV light is emitted through a transparent package that includes a lens to shape the output beam.

13. Industry Trends and Future Outlook

The market for UV LEDs is experiencing significant growth, driven by:
1. Phasing out of Mercury Lamps: Global regulations like the Minamata Convention are accelerating the adoption of mercury-free alternatives.
2. Advancements in Efficiency and Power: Continuous R&D is improving the wall-plug efficiency (WPE) and maximum output power of UV-C, UV-B, and UV-A LEDs, making them viable for more demanding applications.
3. Miniaturization and Integration: UV LEDs enable portable, battery-operated devices for disinfection, curing, and sensing, opening new consumer and professional markets.
4. Smart and Connected Systems: Integration with sensors and IoT platforms allows for precise dose control and remote monitoring in curing and purification systems. The product documented here is part of this broader trend towards efficient, reliable, and controllable solid-state UV solutions.