Table 1. Dynamic Viscosity Values for Various Gases and Liquids When we look at a fluid parcel subject to a velocity gradient in the direction perpendicular to the direction of the flow, we observe that this fluid parcel deforms. This type of deformation is called shear. The ability to withstand shear is a material property called the dynamic viscosity m. The viscosity … [Read more...]
Thermal conductivity of common alloys in electronics packaging
Thermal conductivity of common alloys in electronics packaging Jim Wilson, Associate Technical Editor Property Thermal Conductivity (W/mK) @25°C CTE (ppm/°C) @25°C Copper 395 17.1 Aluminum 200 23.5 CuMo 160-185 7.0-9.0 CuW 180-220 6.5-8.5 Kovar 17 5.9 Alloy42 12-15 4-6 Invar + … [Read more...]
The Seebeck Coefficient
In this issue, we address the Seebeck coefficient, a property that determines the performance of thermocouples and Peltier elements. Basically, the Seebeck coefficient is related to the fact that electrons are both carriers of electricity and heat. If a temperature gradient exists over a piece of electrically conductive wire, there is a net diffusion of electrons from the hot … [Read more...]
Thermal Conductivity of Solders
Soldering has been a primary method of establishing mechanical and electrical connections in electronics for many years and will likely be used in this fashion in the future. While there are several physical properties and characteristics of solders that are of interest to the electronics community at large, one of the most significant physical properties to a thermal engineer … [Read more...]
Thermal Conductivity of Doped, Porous and Isotopically Pure Silicon
Earlier issues of ElectronicsCooling showed the thermal conductivity for pure Si (May '98), SiO2 (Aug '04) and III-V semiconductors (Feb '06). This column focuses on doped Si, porous Si and isotopically pure Si. Table 1. Thermal Conductivity Data at Room Temperature The first seven rows of Table 1 show thermal conductivity data for natural and isotopically pure Si as … [Read more...]
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