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...]
Synthetic jets for forced air cooling of electronics
Introduction As increasing functionality is packaged into ever-shrinking electronics, cooling requirements rise exponentially. While there have been continued advances in high heat flux technologies [1], commercial, consumer-oriented systems continue to focus on aircooling for reasons of reliability, acoustics, cost and portability [2]. In order to support the increasing power … [Read more...]
Moisture permeation in electronics
Environmental control for electronic packages and enclosures often involves understanding and managing moisture concentration. Excessive moisture combined with processing temperatures can cause damage. High humidity levels have other potentially harmful effects such as corrosion. Since the movement of heat and moisture are similar (i.e., diffusive), thermal engineers may be … [Read more...]
Using a simple air recirculation model to explore computer rack cooling
Figure 1. Schematic diagram of simple computer rack air recirculation model. Figure 2. Schematic diagram of computer rack air recirculation model with heat exchanger in rear of computer rack. In an article in the November 2006 issue of ElectronicsCooling it was noted that “advances in computer clusters have resulted in the introduction of higher density server … [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...]
- « Previous Page
- 1
- …
- 122
- 123
- 124
- 125
- 126
- …
- 176
- Next Page »