Icepak高阶建模教程

affected by its operating temperature
The Case for Thermal Management
• Virtually all electronic failure mechanisms are
enhanced by the increase in package temperature:
The Case for Thermal Management
10
200
20 30
Inc3793r00ease in Failure Rate with Temperature
40 1310 (from a base temperature of 50 C)
50
2280
60
3860
Increase in Failure, %
Introduction
The Case for Thermal Management
• The heat generated in an electronic circuit is inversely
proportional to the efficiency of the circuit
• The power that is not converted to perform useful
Cooling Methods
• Types of cooling methods:
– Natural convection air cooling – Forced convection air cooling – Immersion liquid cooling – Boiling – Heat pipes – Cold plates – Thermoelectric coolers – Microchannel cooling – Microjet
– Typical applications include mainframe computers,
supercomputers, high-power transmitters, etc.
• Boiling heat transfer is the absorption of heat by a boiling fluid and is used for high power applications
– Stresses due to TCE mismatch – Corrosion – Electro-migration – Oxide breakdown – Current leakage (which doubles with every 10 c in active
devices)
– Degradation in electrical performance (due to change in
device parameters)
The Case for Thermal Management
• The rate of failure of electronic packages is directly
proportional to heat and increases exponentially with the maximum temperature of the package
Component
Temperature = 25C Temperature = 75C
Thick film resistor
5
15
Chip capacitor
10
25
Power transistor
50
300
Diode
1
9
Logic ICs - SSI
125
1125
Logic ICs - MSI
250
Course Outline
17. Wall Effects 18. External Coolers/Heaters
Case Studies: 1. Mesh Refinement 2. Modeling PBGA 3. Selecting Heat Sink 4. Spreading Resistance 5. Effect of Radiation 6. Sealed Systems 7. Modeling TEC 8. Selecting Baffles I 9. Selecting Baffles II 10. Modeling Data Center
electromagnetic work is lost in the form of heat to the surroundings
• The power wasted as heat includes:
– Joule heating (I2R) loss – Power supply
• The reliability of a semiconductor device is directly
• Budget per watt of heat removal is decreasing
Packaging Trends
Package Power Projection Trends (Watts)
Market Application Year 1998-2000 Year 2001-2003 Year 2004-2006
2250
Logic ICs - LSI
500
4500
Source: C.A. Harper, Handbook of Thick Film Hybrid Microelectronics
The Case for Thermal Management
Major Causes of Electronic Failure
Commodity
1
1
1
Hand-Held
2
2
2
Cost/Performance
18
22
28
High Performance
100
120
140
Harsh
3
3
3
Environment
Source: Sandia National Laboratories
Commodity: Low cost (<$300) consumer products Hand-Held: Battery powered (<$1000) products such as cellular, etc. Cost/Performance: Maximum performance with cost limit (<$300) (Notebooks, etc.) High Performance: Performance is the primary driver (Servers, Avionics, etc.) Harsh Environment: Automotive, Military, etc.
2500
2000
1500
1000
500
0
10
20
30
40
50
Temperature Rise, C
The Case for Thermal Management
The Effect of Package Temperature on Failure
(Number of failures after 1000 hr of operation per million units)
– the coolant can be liquid or gas
• Thermoelctric coolers are solid state heat pumps that do not have any moving parts nor any working fluid
– They move heat from one location to another through the Peltier effect
Advanced Thermal Modeling
Course Outline
1. Introduction 2. CFD Basics 3. Printed Circuit Boards 4. IC Packages 5. Heat Sinks 6. Interface Resistance 7. Fans, Impellers and Blowers 8. Altitude Effects 9. Flow Resistances 10. Radiation 11. Heat Pipes 12. Joule Heating 13. Thermoelectric Coolers 14. Cold Plates 15. Transformers 16. Flow Baffles
• Heat pipes are devices that provide a passive method of transferring heat from one area to another
– Moving towards system-on-chip technology
• Packages are dissipating more power • Operating junction temperature remains fixed
– 55 C for commodity and handheld devices – 125 C for automotive systems
• Natural convection air cooling is used for low power
applications
– It is the simplest and cheapest cooling method available