Table of Contents
What is contact thermal resistance?
Thermal contact resistance (TCR) is a phenomenon in which heat flow is impeded at the contact interface of two materials. W. A. Little, “The transport of heat between dissimilar solids at low temperatures,” Can.
What is the main cause of thermal contact resistance?
The limited number and size of the contact spots results in an actual contact area which is significantly smaller than the apparent contact area. This limited contact area causes a thermal resistance, the contact resistance or thermal contact resistance.
What are the methods to reduce the thermal contact resistance?
As a result, engineers must find ways to minimize the thermal resistance from the electronic device junction to ambient air. Therefore, one way to reduce Rja is to reduce Rcs, the contact resistance between the electronic device case and ambient-cooled, finned heat sinks or liquid-cooled cold plates.
What is meant by thermal contact resistance upon what parameters does this resistance depend?
The contact resistance depends on the surface roughness to a great extent. The pressure holding the two surfaces together also influences the contact resistance. Thermal contact resistance is observed to decrease with decreasing surface roughness and increasing interface pressure.
How does contact pressure affect thermal contact resistance?
Therefore, the thermal contact resistance decreases and the heat transfer rate increases under the higher contact pressure. (3)The heat transfer decreases and the thermal contact resistance increases under the melting process of PCM.
How do you reduce electrical contact resistance?
For reducing electrical contact resistance, the author proposes two methods. The first method is increase of contact pressure at the junction. The second method is the addition of plating material with higher conductivity and wider surface area.
, is a property indicating the thermal conductivity, or ability to conduct heat, between two bodies in contact. The inverse of this property is termed thermal contact resistance.
What are the various ways to reduce the resistance of a semiconductor?
Increasing the temperature of intrinsic semiconductors provides more thermal energy for electrons to absorb, and thus will increase the number of conduction electrons. Voila – decreased resistance.
How do you measure contact resistance?
The standard method for measuring contact resistance is the 6Volt 1Amp method, sometimes referred to as four wire measurement. It is a simple method that can be easily implemented with two power supplies, and a digital voltage meter (DVM). The following schematic is used to measure contact resistance in our lab:
How does contact pressure effect thermal contact resistance?
The pressure holding the two surfaces together also influences the contact resistance. Thermal contact resistance is observed to decrease with decreasing surface roughness and increasing interface pressure. This is attributed to the fact that the contact surface between the bodies grows as the contact pressure grows.
What is meant by thermal resistance?
Thermal resistance is a measure of a material’s ability to resist heat transfer. The more a material is able to block heat transfer through its surface, the greater its thermal resistance. This concept is often applied to the building industry as a measure of insulation effectiveness and energy efficiency.
What material has the highest thermal resistance?
The most extensively used high working temperature resistance materials are alloys of nickel, chromium and iron called Nichrome and alloys of aluminium, iron and chromium. The quality of these alloys, especially the working temperature strongly depends upon the chromium content.