How can thermal resistance be reduced?
As a general trend, the thermal resistance decreases as the aperture size increases. This is because a larger surface area enhances the heat dissipation and effectively reduces the internal temperature in the device.
What is thermal resistance of heatsink?
The contact between the device case and heat sink may have a thermal resistance between 0.5 and 1.7 °C/W, depending on the case size and use of grease or insulating mica washer.
How much power can a PCB dissipate?
With only natural convection (i.e. no airflow), and no heat sink, a typical two sided PCB with solid copper fills on both sides, needs at least 15.29 cm2 (≊ 2.37 in2) of area to dissipate 1 watt of power for a 40°C rise in temperature. Adding airflow can typically reduce this size requirement by up to half.
How heat sinks work?
Heat sinks work by redirecting heat flow away from a hot device. They do this by increasing the device’s surface area. In order for heat sinks to properly work, they must have a temperature higher than the surroundings to transfer heat.
How can I improve my thermal contact?
Introducing a thin layer of oil or grease between the surfaces [2,16-19] is the most popular to reduce the thermal contact resistance. The optimum thickness of the interstitial material depends on the thermal conductivity of the grease, which can be further improved by adding metallic particles to the silicone greases.
Does thermal resistance change with temperature?
Collisions between ions and electrons assist heat conduction. That’s why thermal resistance decreases with temperature.
What is the thermal resistance of copper?
3.14. 5 Thermal conductivity coefficient
| Metals | ||
|---|---|---|
| Copper | 386 | 8.80 |
| Gold | 310 | 0.21 |
| Inconel | 15 | |
| Iron, cast | 55 | 0.15 |
How do you calculate thermal resistance?
The units for thermal resistance are Kelvins per watts (K/W). By definition, thermal resistance R is the ratio of the temperature difference T2 – T1 and the heat flow Q1-2 between two points. The thermal resistance formula is the following: R = (T2 – T1) / Q.
How do you calculate thermal conductivity of PCB?
Instructions
- Find the thickness of the PCB board and the thickness of the copper traces on the board.
- Calculate the thermal conductivity parallel to the plane of the board using the formula Kp = 0.8 + 350 (ZCu/Z) where the variable “Kp” represents thermal conductivity parallel to the plane of the board.
How do you calculate PCB temperature?
The temperature rise at the base of a component mounted to a PCB can simply be determined by calculating the temperature rise a point P located at the center of the component. The temperature at the base of the component, ΔTb is then used to calculate the component junction temperature using equation 20.