FAQs
Featured FAQ
Expert Analysis of UV LED Applications, Mastering Key Selection of COB LED,
SMD LED, and Power LED Solutions
Violumas-Specific Questions
1
What kind of optics does Violumas provide?
Violumas provides a multitude of lens options for UV LEDs depending on the wavelength. We can provide UV LEDs with 15°, 30°, 60°, 90°, 120°, or 135° flat panel optics.
We can also remove the lens completely to maintain the naturally wide angle of the LED chip if that is preferred.
2
What makes 3-PAD LEDs special?
3-PAD LEDs are exclusively manufactured by Violumas and designed with an additional thermal pad, which is an electrically-isolated structure for efficient heat extraction.
The thermal pad rapidly conducts heat from the chip’s junction to the heat sink via a copper pillar mesa structure on our specialized Pillar MCPCBs.
The combination of 3-PAD LEDs on Pillar MCPCBs allows for extremely low thermal resistance and rapid heat dissipation.
Learn more about the advantages of 3-PAD technology
Are you able to provide UV LEDs with specific wavelength constraints?
Yes, we are able to accommodate specific wavelength constraints for the UV LEDs. We can select specific wavelength bins to ensure that all products are between a set wavelength tolerance. The pricing for UV LEDs with specific wavelength constraints may be higher than our standard offerings as the yield for some wavelengths may be low.
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Frequently Asked Questions
How do I determine the best UV LED solution for my application?
Our team can help to identify the best UV LED components for your application with consideration of the optical output, beam angle, and mechanical/electrical requirements. In order to determine the optimal UV LED solution, we recommend the use of optical simulations to better understand the expected irradiance and uniformity for various settings. First, a list of target specifications is generated including information such as the exposure area, wavelength, throw distance, irradiance, uniformity, and mechanical and electrical restrictions. Using the target requirements, optical specialists at Violumas can help you determine the best optics and required number of LEDs for the application.
Learn more about custom UV LED solutions：https://www.violumas.com.tw/customized
How do I determine the best UV LED solution for my application?
What kind of power supply do I need for operating UV LEDs?
What kind of power supply do I need for operating UV LEDs?
We recommend operating UV LEDs with constant-current power supplies, which support limited voltage ranges and maintain the set current without over-driving the LEDs. If a constant voltage driver is used instead and the current is not regulated, as the LED temperature increases when powered ON, the LED forward voltage would decrease accordingly which would eventually lead to thermal runaway.
Learn more about selecting an appropriate power supply for your UV LEDs here: https://www.violumas.com.tw/drivers
What kind of power supply do I need for operating UV LEDs?
How do I determine the best UV LED solution for my application?
UV irradiation can cause degradation such as yellowing, cracking, and becoming brittle on certain materials.
Materials that will be exposed to UV irradiation should be UV-resistant or tested for repeated exposure to UV irradiation.
What is the effect of UV irradiation on material degradation?
What is the difference between SMD and COB UV LEDs?
Surface Mount Device (SMD) LEDs are commonly available, square packages of LED chips available in compact form factors ranging from 3x3mm to 6x6mm.
SMD UV LEDs need to be mounted to PCBs or MCPCBs to be powered on. A more recent development in LED packaging is the Chip-On-Board (COB) LED, which consist of LED chips directly mounted onto the PCB or MCPCB for improved heat dissipation.
COBs do not require additional MCPCBs and can offer high density, flexible arrangements of LED die.
What is the difference between SMD and COB UV LEDs?
Technical Performance
Q1: Is There a Significant Difference in Germicidal Performance Between 265 nm and 275 nm?
Summary: Although 260–265 nm is closest to the peak DNA absorption wavelength, 275 nm LEDs typically offer higher wall-plug efficiency (WPE) and greater optical output power. Detailed Explanation: In practical applications, the higher irradiance available from 275 nm LEDs can compensate for the spectral shift, enabling germicidal performance comparable to that of 265 nm LEDs. However, certain specialized disinfection applications require shorter wavelengths such as 265 nm to achieve optimal effectiveness. Therefore, wavelength selection should always be determined by the specific application requirements.
Q2: How Is UV LED Irradiance Calculated?
UV LED irradiance is the amount of ultraviolet power received per unit area and is commonly expressed in mW/cm². As the distance between the light source and the target increases, irradiance decreases. A simplified estimation can be made using the inverse-square relationship between illuminance and distance: Formula: E = I / d² Where: • E = Illuminance (lux) • I = Luminous Intensity (cd) • d = Distance from the light source to the target (m) Note: For UV applications, irradiance (mW/cm²) is generally more relevant than illuminance (lux), since UV radiation is outside the visible spectrum.
Q3: How Can UV LED Output Power and Intensity Be Measured?
UV LED characterization is generally divided into two key metrics: 『 Total Radiant Flux 』 『 Irradiance 』
測量設備 | 測量目標 | 核心優點 ( Why use it? ) | 備註 |
|---|---|---|---|
Spectroradiomete | Spectral distribution and total radiant flux | Measures wavelength distribution and optical spectrum. When combined with an integrating sphere, total radiant flux can be accurately measured. | 1. Standard measurement method used by Violumas. |
Radiometer | Irradiance (W/cm²) | Easy-to-use solution for field measurements of UV intensity. | Appropriate optical filters are required for wavelength-specific measurements. |
Goniometer | Beam pattern distribution | Measures optical distribution from multiple angles. | Used for advanced optical simulation and validation. |
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Violumas Quality Commitment
All Violumas products are measured using an integrating sphere to ensure wavelength accuracy and output consistency before shipment.
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Recommendation for Customers
Because UV measurement standards and calibration methods are not yet fully standardized across the industry, we strongly recommend that customers verify product performance using properly calibrated instruments during system integration.
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Professional Support
UV measurement equipment requires periodic calibration to maintain accuracy. If you have questions regarding measurement methods or equipment selection, please contact the Violumas team.
Q4: What Type of Power Supply Is Required for UV LEDs?
We recommend driving UV LEDs with a constant-current power supply. A constant-current driver operates within a specified voltage range while maintaining a stable current level, preventing LED overdriving. If a constant-voltage supply is used without proper current regulation, the LED forward voltage decreases as junction temperature rises. This can result in increased current flow and ultimately thermal runaway. Example: "As temperature rises, forward voltage decreases, causing current to increase further and potentially leading to device failure." For more information, please refer to our UV LED Driver Selection Guide.
Q5: What Causes UV LED Degradation?
The primary causes of UV LED degradation include: • Elevated operating temperatures (most significant factor) • Material degradation within the package • High-current stress • UV-induced material damage 👉 UVC LEDs are generally more susceptible than UVA LEDs because the higher photon energy places greater stress on semiconductor materials and package components.
Q6: What Should Be Considered in UV LED Optical Design?
Key Design Considerations • Beam angle • Lens material selection • Irradiance uniformity UV Material Considerations Many standard plastics degrade under prolonged UV exposure. Therefore, UV optical systems typically require: • Quartz optics • UV-grade optical materials to ensure long-term performance and reliability.
Lifetime & Reliability
Q1: How Is UVC LED Lifetime Defined?
UV LED lifetime is commonly expressed as L70. L70 represents the number of operating hours required for the optical output to decrease to 70% of its initial value. Effective thermal management and maintaining a low junction temperature are critical factors in maximizing LED lifetime.
Q2: What Is the Expected Lifetime of UV LEDs?
UV LED lifetime depends on wavelength and operating conditions. Typical values include: UVA LEDs: L70 > 10,000 hours UVB LEDs: LT70 ≥ 6,000 hours UVC LEDs: LT70 ≥ 6,000 hours For detailed lifetime information, please contact us regarding thermal management and system design recommendations.
Q3: How Does Thermal Resistance Affect UV LED Performance?
UV LEDs are highly sensitive to temperature. Increasing temperature not only reduces UV output but can also significantly shorten device lifetime. Lower thermal resistance allows heat to be transferred more efficiently from the LED junction to the substrate, making it a critical factor for high-power UVC LED systems. Key Parameters ● Junction Temperature (Tj) ● Thermal Resistance (Rth)
Thermal Management Solutions
Q1: What Cooling Solution Is Required for UV LEDs?
Thermal management is critical for UV LED performance. Approximately 95% of electrical energy supplied to a UV LED is converted into heat. Excessive junction temperature (Tj) directly accelerates optical degradation and shortens lifetime. Because UV LEDs dissipate heat primarily through the backside of the package, selecting an appropriate cooling solution is essential. 💡Three Keys to Effective Thermal Management 1. High Thermal Conductivity Materials Use copper, aluminum, or other high-conductivity materials. 2. Thermal Interface Materials (TIMs) Apply thermal grease or thermal pads between the LED and heat sink to minimize thermal resistance. 3. Efficient Backside Heat Transfer Since UV LEDs dissipate heat through the substrate, proper contact between the board and heat sink is essential for long-term reliability.
LED 功耗等級 | 推薦冷卻方案 | 運作原理 |
|---|---|---|
Low Power | Passive Cooling | Aluminum or copper heat sinks dissipate heat through natural convection. |
Medium to High Power | Forced-Air Cooling | Heat sinks combined with fans improve heat transfer through forced convection. |
Very High Power / Enclosed Systems | Liquid Cooling | Water-cooling systems provide efficient heat removal where airflow is limited or unavailable. |
Safety
Q2: How Should UV LED Thermal Systems Be Designed?
Effective thermal management should be addressed at three levels: 1. Package Design Flip-chip technology generally provides superior thermal performance compared to wire-bonded structures. 2. Material Selection High thermal conductivity substrates such as: ● Aluminum Nitride (AlN) ● Copper-based substrates 3. System-Level Cooling ● Heat sinks ● Forced-air cooling ● Liquid cooling Design Objective Maintain junction temperature (Tj) well below the maximum rating. For optimal reliability and lifetime, a junction temperature range of 60°C–75°C is generally recommended.
Q1: Is 222 nm Far-UVC Completely Safe for Humans?
Due to its limited penetration depth, 222 nm Far-UVC is generally considered a safer UV wavelength because it cannot penetrate the outer dead-cell layer of the skin or the tear layer of the eye. However, system design must still comply with applicable photobiological safety standards, including: ● ACGIH Exposure Guidelines ● IEC 62471 Photobiological Safety Standard (latest 2026 revision) to ensure exposure levels remain within established safety limits. Far-UVC technology should therefore be evaluated based on actual exposure conditions, system design, and regulatory compliance rather than being assumed to be universally harmless.