Technical Information - Thermal Resistance Tool

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• MSDS Safety Sheets

• How to
    select a heat sink

• Determining thermal
    resistance for
    Bonded Fins

• Performance Factor
    Table

• Correction Factors
    for Temperature
    and Length

• Airflow Volume to
    Velocity Conversion

• Reading a Thermal
    Performance Graph

• Technical Papers

Aavid Thermalloy offers 42 different base profiles to which fins with heights from 25mm to 140mm (1.0 inch to 5.5 inches) can be attached. Performance datasheets can be generated for any combination of base profile, fin height, and length.

Predicting Thermal Performance

Use the following steps to determine thermal resistance (°C/W) for various bonded fin lengths at different air velocities.

Step 1
Select a base profile, length and an air velocity.

Step 2
Enter the values for each of the parameters listed and press the Calculate button.
Clicking Calculate with no inputs will load the example below.

Step 3
Read the calculated thermal resistance* in °C/W.

Parameter	Units
Length	inch	mm
Base Width	inch	mm
Fin Height	inch	mm
Air Velocity	LFM	m/s
# of Fins

Thermal Resistance	°C/W

*Actual thermal performance will vary with the amount and position of the heat input(s). Values determined by this calculation can be used for comparisons between various Aavid Thermalloy bonded fin heat sinks.

Thermal resistance = 0.295 °C/W (approximately*)

Example
To calculate the thermal resistance of a 5.0" long by 2.40" wide bonded fin base #66825 with 16 fins at 2.0" high with air velocity of 500 LFM, enter the values in the text boxes and click the calculate button.

Related Factors
Fan manufacturers rate their fans by volume of output. In order to use this tool correctly, volume must be converted to velocity by using Airflow Volume to Velocity Conversion Chart. Remember to derate for static pressure head.