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Course Outline no. 236 
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Cooling Methods
for Electronics Design
Course No. 236
For whom intended Electronic designers and packaging
specialists, environmental test laboratory engineers and technicians,
specification writers, equipment designers, and quality and reliability
specialists.
Brief Course Description The course introduces the
fundamentals and physics of thermodynamics and heat transfer.
It then shows how to apply this information to the design and
testing of electronic and other hardware. Since conventional
methods of electronics cooling may not meet the demands of new
advanced designs, the instructor will discuss some advanced cooling
techniques, some of which will set new industry standards in the
21st century. A class project is included to provide supervised
practice in using the course material.
The course is presented as a series of highly-interactive lecture/discussion
sessions. Problems for individual and group solution are interspersed
throughout the course to act as training aids and to evaluate
class progress. Special-interest discussions are encouraged outside
of the regular course sessions. Student comments on this course are very positive.
Certificate programs This course is required
for TTi's Electronic Design Specialist (EDS) and Mechanical Design Specialist (MDS) Certificate Programs.
It is an elective for any other TTi specialist certificate program.
Prerequisites There are no definite prerequisites.
However, this course is aimed toward individuals involved in related
technical fields.
Text Each student will receive a
course workbook, including most of the viewgraphs used in the course presentation.
Course Hours, Certificate and CEUs Open courses meet seven hours per day. Upcoming presentation dates can be found on our current open course schedule. Class hours/days for on-site courses can vary from 14-35 hours over 2-5 days as requested by our clients. Upon successful course completion, each participant receives a certificate of completion and one Continuing Education Unit (CEU) for every ten class hours.
- Introduction
- Effects of temperature on electronic components
- Junction temperature of an IC
- Trends in thermal variables, emerging technologies
- Definitions, temperature scales
- Basic thermodynamics, heat transfer mechanisms
- How to solve a thermal problem
- Heat Transfer by Conduction
- Heat flows through a solid
- Good thermal design
- Series and parallel thermal resistance and conductance; Example
- Surface roughness and heat flow
- Improving conduction: Metal foils, shims, thermal grease,
- Effect of contact pressure and area
- Contact resistance, minimizing; Example
- Thermal wedge clamp; Example
- Bolt and washer conductance; Example
- Metal core PC boards; materials; determining IC case to board core resistance
- Thermal paths, thru-hole vias,
- Amplifier internal heat sinking
- Thermal conductivity of
- Substrate materials
- IC packaging materials
- Adhesives
- Thermal spread angle; values for common materials; Example
- Diamond heat sinks
- Heat Transfer by Convection
- Definitions, Nomenclature
- Free or natural convection vs forced convection
- Heat transfer and film coefficients for air flow around different shapes
- Heat transfer and fluids
- Convection equation
- Effect of altitude
- Cooling fins and heat sinks
- PC board spacing, power, and heat removal; Example
- Forced convection on PC boards; Example
- Three methods of enhancing forced convection on PC boards
- Turbulent and laminar forced convection inside shrouded fins; effect of fin tip gaps
- Impingement cooling
- Interleaved fins
- Pin Fins plus impingement flow
- Sample problems
- Natural convection
- Heat sink
- Laminar flow
- Turbulent Flow
- Pressure Drop and Fans
- Equation for circular sections
- Fanning friction factor
- Cooling fan selection
- Pressure vs. airflow
- Air flow velocity charts
- Testing at altitude
- Pressure drop measurement-tips
- Flowmeter correction factor
- Cooling air parameters
- Sample problem: electronics cabinet cooling
- Pressure drop in electronics cabinets
- Typical enclosures, characteristics
- Fan selection example
- Heat exchanger
- Cabinet ventilation area calculation for free convection
- Buoyancy pressure formulas
- Flow resistance coefficient
- Sample problem
- Commercial electronics cabinet cooling example
- Fan and blower specifications
- Heat Transfer by Radiation
- Heat exchange between different surfaces
- Radiation heat transfer equation
- Shape or view factor curves
- Normal vs hemispherical emissivity
- Thermal conductivity and insulation materials
- Solar incidence angle
- Radiation heat transfer example
- Spacecraft temperature factors
- Ground operations daily cycle: peak solar radiation vs. peak temperature
- Radiant interchange factor
- Emissive power, sT4 tables
- Configuration factors for satellites
- Heat inputs for satellites: solar, earth, albedo
- Student problem: satellite surface heat, reducing internal heat
- Student problem: Thermal vacuum test setup
- Thermal balance
- Sample Heat Balance Problems
- Calculating external surface temperature
- Calculating internal ambient temperature
- Transient heat balance example
- Example of developmental test data analysis
- Heat Pipes
- Heat sinks and heat exchangers
- Why a heat pipe works
- Heat pipe sinks for electronic component cooling
- Typical heat pipe components, fluid compatibility
- Field experience
- Constant-conductance heat pipe
- Types of groove and wick configurations
- Diode heat pipe types
- Liquid trap
- Liquid blockage
- Gas blockage
- Variable-conductance heat pipes (VCHPs)
- Capillary pumped loop (CPL)
- Comparison of VCHP and CPL performance
- Analysis: Heat pipe capacity
- System pressure drop
- Thermodynamic considerations
- Working fluids, compatibility
- Testing, applications, performance, references
- Experimental investigation of micro heat pipes fabricated in silicon
wafers
- Thermal Modeling
- Steady state mode (uses arithmetic nodes)
- Thermal model used to get boundary temp. for PC board model
- Example of nodal grid overlaid on PC board
- Example of computer input data chart
- Transient mode (uses diffusion nodes)
- Thermal modeling hints and tips
- Thermal incidence angle
- Radome thermal model
- Power Supply Issues
- Calculating power supply requirements
- Sample power supply problem
- Transistor mounting
- Thermal circuit for transistors
- Fixing overheating problems:
- Two power transducers
- Switching power supply--resistor heat sink
- Ceramic dual inline package
- Inductor and transformer
- Diode module assembly
- Use of copper boss
- Ram Air Cooled Electronics Example
- Temperature vs. Altitude
- Cooling airflow vs. Mach number
- Worst steady state conditions
- Air Flow: heat balances
- Ambient cooling and bucket section
- The concept of sigma for pressure drop
- Maximum cooling air circuit pressure drop
- Altitude, pressure, and density
- Pressure drop tests
- Alarm and cut-off switches
- PC Board Cooling Alternatives
- Thermal design concepts for surface mount multilayer boards
- Cooling of electronics boards using internal fluid flows
- Underside Layout Configurations for Some Common ICs
- Mechanical Engineer's Tool Kit
- Off-the-shelf miniature couplers, pumps and fans
- Advanced flow control systems
- Miscellaneous
- Practical suggestions
- Thermal oven design procedure and example
- Compromises relating to other disciplines
- Development temperature tests--tips
- Thermal proposal outline
- Checklist for thermal modeling
- Thermal considerations in automotive electronics
- Dealing with management
- Air Flow Balancing
- Single and multiple path boxes
- Pressure drop tolerances
- Flow balancing example
- Multiple boxes with a common plenum
- Cold plate interchangeability; Examples
- Summary
- Final Examination
- Award of Certificates for Successful Completion
Printable (.pdf) version of course outline no. 236 ( Adobe Acrobat Reader required).
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