How to Set the Thermal Resistance of COB?

Release date: 2017-11-15 Source: External Station Share: Share to QQ Friends Share to QQ Space Share to WeChat Share to Sina Weibo

When simulating a COB light source, you often find its thermal resistance specified in the datasheet. For example, if it's listed as 5Â°C/W, and you're working with a power of 14W, the temperature rise would be approximately 70Â°C.

1. How is the final thermal resistance calculated?
The thermal resistance of a COB is typically determined by dividing the temperature difference between the junction and the ambient by the power dissipated. However, this value can vary depending on the mounting method, cooling system, and surrounding environment. Itâ€™s important to consider all these factors when calculating or estimating the actual thermal performance. 2. If the COB light source is ceramic, what thermal conductivity should be set?
Ceramic substrates usually have higher thermal conductivity compared to traditional materials like aluminum. For a ceramic-based COB, the thermal conductivity might range from 10 to 30 W/mÂ·K, depending on the specific type of ceramic used. You should refer to the manufacturer's specifications for accurate values. 3. What area is referred to â€” the largest area of the COB or the effective area of the LED chip?
In most cases, the area used in thermal calculations refers to the effective heat-dissipating surface of the COB. This is typically the area where the heat is transferred from the die to the substrate. Using the largest physical dimension may not provide an accurate representation of the actual thermal behavior.

For finite element analysis (FEA), tools like ANSYS are commonly used to simulate thermal performance. These simulations can help predict how the COB will behave under different conditions. However, real-world testing is still essential due to environmental factors, measurement accuracy, and potential errors during testing. Simulation results can offer guidance, but they should be validated through physical testing whenever possible. Itâ€™s recommended to use empirical values or combine them with ANSYS simulations and then validate through physical testing. This approach ensures that your design is both efficient and reliable in real-world applications.