3W UV LED 395nm Ultraviolet - High Power UVA on 20mm Star PCB Heatsink

Specifications

• Power Rating: 3 Watts

• Wavelength: 395nm to 400nm (UVA Spectrum)

• Forward Voltage (Vf): 3.2V to 3.6V DC

• Forward Current (If): ~700mA (Constant Current Required)

• Viewing Angle: 120 Degrees (without external lens)

• PCB Material: Aluminum Core

• PCB Diameter: 20mm (Standard Star base)

• Emitting Color: Ultra-Violet (Appears as a deep, visible purple)

Key Applications and Projects

• PCB Fabrication: Exposing UV-sensitive photoresist film to etch incredibly precise custom copper traces on raw copper-clad boards.

• Fluorescent Inspection: Building custom blacklight flashlights for finding pet stains, identifying scorpions outdoors, or inspecting antique glassware.

• Non-Destructive Testing (NDT): Using UV-reactive penetrant dyes to find microscopic cracks in metal mechanical parts and engine blocks.

• Aquarium Lighting: Simulating deep-water reef environments to make specific corals fluoresce brightly.

Unlock New Capabilities (Project Evolution) The Automated SLA Resin Curing Chamber: If you own a resin 3D printer, washing and curing your prints in the sun is inconsistent and messy. Build an automated curing oven! Line the inside of a small box with reflective aluminum tape. Mount an array of 6 to 8 of these 3W UV LEDs on aluminum heatsinks around the inside of the box. Wire them in series to a high-voltage Constant Current boost driver. Use an Arduino Nano and a MOSFET to control the driver, and attach a small slow-rpm DC motor to the floor to act as a turntable. You can now place your sticky resin print inside, hit a button, and the Arduino will bathe it in 360-degree, high-intensity 395nm UV light for exactly 3 minutes, resulting in a perfectly hardened, tack-free part every single time!

Package Includes:

• 1 x 3W 395nm Ultraviolet LED (Pre-mounted on 20mm Aluminum Star PCB)

FREQUENTLY ASKED QUESTIONS (FAQ)

Q: What does 395nm mean? 395nm refers to the wavelength of the light emitted. The human eye can generally see from about 400nm (violet) up to 700nm (red). 395nm is just below human vision in the Ultraviolet-A (UVA) spectrum, commonly referred to as "blacklight."

Q: Why does the light look intensely purple if it is supposed to be invisible UV? While the peak emission is at 395nm (mostly invisible to us), the LED still produces a small "tail" of light that bleeds into the 400nm-410nm range, which our eyes perceive as a very bright, deep violet.

Q: Is this safe for my skin and eyes? While 395nm UVA is significantly safer than UVC (which is used for sterilization), you should never look directly into a 3W UV LED. Prolonged exposure can cause eye strain or damage. UV-blocking safety glasses are highly recommended when working with these LEDs.

Q: Will this kill bacteria and viruses? No. Sterilization and germicidal applications require UVC light (typically around 254nm or 275nm), which destroys DNA. This is a 395nm UVA light, which is meant for curing and fluorescence, not sterilization.

Q: Can I use this to cure UV resin and UV glues? Yes! 395nm is the standard wavelength used to activate the photo-initiators in almost all commercially available UV craft resins, LOCA screen glues, and gel nail polishes.

Q: Why does the board say "CREE" if it isn't an authentic Cree chip? The aluminum star PCBs are manufactured in massive batches using generic silkscreen templates, which often include well-known branding. The LED diode soldered to it is a generic, high-quality emitter, providing excellent performance at a fraction of the cost of a branded chip.

Q: What is the forward voltage (Vf)? The forward voltage drop for this UV LED is typically between 3.2V and 3.6V DC.

Q: What is the maximum current I can run through it? To achieve the full 3 Watts of power, it should be driven at a constant current of 700mA (0.7 Amps).

Q: Can I connect this directly to a 3.7V Lithium-Ion battery? No. A fully charged Li-ion battery rests at 4.2V. If you connect this directly, the LED will draw too much current and burn out. You must use a current-limiting resistor or, ideally, a constant current driver circuit.

Q: Can I hook this up to an Arduino 5V pin? Absolutely not. The Arduino can only supply about 20mA to 40mA per pin. This LED requires 700mA. Attempting to power it directly will instantly destroy your Arduino's microcontroller. You must use a MOSFET or a relay to switch the power from a dedicated power supply.

Q: Does the aluminum star board mean I don't need a heatsink? False! The 20mm star board is only a heat spreader. If you run this LED at a full 3W for more than a few seconds, it will still overheat. You MUST mount the star board onto a larger, finned aluminum heatsink to use it continuously.

Q: How do I attach the star board to a larger heatsink? You should apply a very thin layer of thermal paste to the back of the star board and use small screws to secure it through the semi-circular notches on the edges. Alternatively, you can use thermal adhesive plaster/glue for a permanent bond.

Q: How do I solder wires to this? Because the aluminum board is literally designed to pull heat away, it will cool down your soldering iron very quickly. You need a powerful iron (40W+) with a large tip. Pre-tin the positive and negative pads quickly with high heat, and then attach your wires.

Q: Can I dim this UV LED? Yes, but you cannot dim it by simply lowering the voltage. You must use a Constant Current driver that supports PWM (Pulse Width Modulation) dimming, which turns the LED on and off thousands of times a second to reduce the perceived brightness.

Q: Can I wire multiple LEDs together? Yes. The most efficient way is to wire them in series. If you wire three LEDs in series, you will need a driver capable of supplying 700mA at around 10.5V to 11V (3 x 3.5V).

Q: What is the beam angle? The bare LED on the star board has a wide viewing angle of approximately 120 degrees, producing a wide flood of UV light.

Q: Can I focus the light into a tight beam? Yes! The 20mm star board is specifically sized to accept standard LED collimator lenses. You can purchase a 20mm lens (e.g., 5-degree or 15-degree) and a plastic housing that snaps directly over the LED to create a focused UV spotlight.

Q: Is this LED waterproof? No, the electrical contacts and the LED dome are completely exposed. If you are using it near water (like aquarium lighting), it must be installed inside a sealed, waterproof enclosure.

Q: What gauge wire should I use for the connections? Because it draws nearly an amp of current, standard 22 AWG or 24 AWG stranded hookup wire is perfectly suitable for short runs.