1. 2 Electronic Packaging Ten Thermal Solutions CardTemp, Version 3.45

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CardTemp Manual,Version 3.45

Copyright © 2011 Advanced Thermal Engineering, Inc.

All Rights Reserved

P. O. Box 4528

Huntsville, AL 35815

USA

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Electronic PackagingTen Thermal Solutions

CardTemp, Version 3.45

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Electronic Packaging CardTemp, Version 3.45

•Solve for the printed wiring board (PWB) temperature in several housings with different cooling schemes.

•Compare two solutions so that the same PWB can be used for two customers.

•Move scroll bars and click option buttons to create an interactive trade study.

This executable (612 KB) operates on an MS Windows platform (3.0 or later).

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CardTempPWB Temperature Management

•Make the PWB compatible with the operating environment before the high hazard rates and low reliability cause a redesign.

•Solve the thermal problem before the environmental test fails and the PWB must be redesigned.

•Manage your resources before a conflict exists between disciplines.

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CardTempTen Thermal Solutions

•Electrical Engineers use it as a quick solution.

•Industrial (Reliability) Engineers use it as a simplified solution.

•Mechanical (Thermal) Engineers use it as a sanity check.

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Post Processing Values

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Case TemperaturePlated Through Holes (PTH)

Calculate the Component Case Temperature of a case mounting in plated through holes of a PWB in a chassis.

Tcase = Tpwb + Rbc*Pcase

Where:

Tcase is the component case temperature.

Tpwb is the local PWB temperature.

Rbc is the thermal resistance from the PWB to the case.

Pcase is the component power dissipation.

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Case TemperatureCircuit Side Thermal Plane

Calculate the Component Case Temperature of a case mounted on a PWB, with a circuit side thermal plane, in a chassis with wedge-locks.

Tcase = Tpwb + Rbc*Pcase

Where:


Tpwb is the local PWB temperature.

Rbc is the thermal resistance from the PWB to the case.


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Case TemperatureComponent Side Thermal Rail

Calculate the Component Case Temperature for a Dual-Inline-Package (DIP) mounted on a component side thermal rail. The component power dissipation leaves the case to enter the thermal rail. It conducts along the rail to the wedge locks of the circuit card assembly and enters the chassis wall. Thus, the PWB and the thermal rail and the component case are all at the same temperature.

Tpwb = Trail; Trail = Tcase

Where:Trail is the temperature of the local thermal rail.

Therefore: Tcase = Tpwb

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Case temperatureFree Convection

Calculate the Component Case Temperature for a case on a PWB cooled by free convection. The component power leaves the case by convection to the air passing over it. The air penetrates to the sides and top of the component case providing a large area for heat transfer. The surface area of the PWB component side approximates the total exposed surface area of all the components. The PWB temperature is now based on the component case temperature. Thus, the PWB and the component case are both at the same temperature.

Tcase = Tpwb

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Case TemperatureRadiation

Calculate the Component Case Temperature for a case on a PWB cooled by radiation. The component power leaves the case and radiates to the sink over it. The radiation leaves the sides and top of the component case providing a large area for heat transfer. The surface area of the PWB component side approximates the total exposed surface area of all the components. The PWB temperature is now based on the component case temperature. Thus, the PWB and the component case are both at the same temperature.

Tcase = Tpwb

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Junction Temperature

Calculate the Component Junction Temperature.

Tjunc = Tcase + Rcj*Pcase

Where:

Tjunc is the component junction temperature.


Rcj is the thermal resistance from the case to the junction.


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Electronic PackagingReliability

Calculate the System Reliability. The Reliability Engineers calculate the component, card, and system reliability. It is based on the component characteristics. The hazard rate for each component is an input to the component reliability. This hazard rate is a function of the component junction temperature. A low component junction temperature produces a low component hazard rate. A component with a low hazard rate has high reliability. A chassis full of high reliability components has high system reliability.

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User’s Guide

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CardTemp, Version 3.45Copyright © 2011 Advanced Thermal Engineering, Inc.

All Rights Reserved

CARD345.exe 612 KB

LICE343.pdf 7 KB

READ343.pdf 20 KB

The legal license is found in two PDF files. Select the executable file to start the program. Select buttons to navigate the various forms.

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CardTempLook and Feel of the Program

The selection of buttons will move the program forward or backward through the interactive forms. Scroll bars and option buttons will change default values to unique values. Moving through the forms will bring the user to the final temperatures of a particular trade study. Every form has a button to end the program.

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CardTempForms of the Program

Table I. Form Titles

Name Title

Start: form1 (Input) PWB Mechanical Design

form2 (Input) Circuit Card Assembly Option

form3 (Input) Chassis Data

form4 (Input) Convection/Radiation Housing [5, 6, 7, 8]

form5 (Input) Circuit Card Assembly and Chassis

form6 (Input) CCA Alone in a Chassis [9]

form7 (Input) CCA Environment Data [9]

form8 (Input) Free Convection Only [10]

form9 (Input) Slot Temperatures, Setup Numerical Scheme

form10 (Input/Output) Slot Temperatures, Setup Cards (form9-form10)

form11 (Input/Output) PWB Detail Power (form11)

Finish: form12 (Output) Answers (form1-form8)

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CardTemp Navigating the Program Start: form1

form2

form5form8 [10] form6 [9] form7 [9]

form3 [1-8] form4 [5-8]

Finish: form12 [1-10] form9 [1-8] form10 [1-8]

form11 [1-8]

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CardTemp Manipulating the Program

Start: form1

form2


form3 [1-8] form4 [5-8]


form11 [1-8]

When the program starts form1 is displayed. The user moves forward to change default values and complete his trade study on form12. If the results are not acceptable to the user, he simply moves backward to the various forms to update new unique values for his design.

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CardTemp Advanced User

Start: form1

form2


form3 [1-8] form4 [5-8]


form11 [1-8]

The advanced user may take solutions [1-8] to form9 and form10. Here the cards are in a chassis and radiating to the neighbor in front and back. High powered cards radiate to lower powered cards. The hot cards cool and the cool cards warm. A fin may be inserted into the chassis to cool very hot cards.

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CardTemp Very Advanced User

Start: form1

form2


form3 [1-8] form4 [5-8]


form11 [1-8]

The very advanced user may take solutions [1-8] to form11. This solution allows the card to be broken into several nodes. “Hot rocks” may be placed in the center. Power is concentrated and spread in a more realistic distribution. This solution is very fine in the slot of the chassis.

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CardTemp Super Advanced User

The super advanced user may take solutions [1-8] from form11 back to form10. This solution allows the card to be placed back in a chassis with radiation to its two neighbors. Now that the new maximum, median, and minimum conduction values are known for the concentrated power distribution, a very fine solution is produced. Note that the heat moves from the printed wiring board to the chassis heat sink through the entire PWB, CCA, chassis, and cooling scheme. The boundary condition is not the boards two mounting edges, but the actual chassis mounting heat sink.

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Form Details

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Start: form1

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Start: form1Options

1. Input “CCA Power”.

2. Input other unique values.

3. Select “Card Options” to move forward to the next form.

4. (Select “End the Program” if you wish to end the program session.)

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Start: form1Details

1. The PWB width is 5200 mil (13.2080 cm) and mounts the connector.

2. The PWB height is 6000 mil (6.00”).

3. The PWB has eight layers, each one has enough copper to represent 23% of the surface area. The outer two layers have 2 oz. copper and each inner layer has 1 oz. copper.

4. The components dissipate 3000 mW (3.0 W or 10.2390 Btu/hr).

5. The boundary condition is 71.0°C.

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form2

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form2Options

1. Select a thermal solution, like “Plain [1]” or “SMT [7]”.

2. (Select “Design” if you wish to return to the previous form.)

3. (Select “End” if you wish to end the program session.)

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form2CCA Descriptions [1]

Solution [1] is the basic PTH PWB in a chassis. The chassis top is removable for CCA removal and instillation. The sides have locking card guides to hold each card in a 0.50” slot. The mother board is at the bottom. Wires from the chassis front face rout to the bottom of the chassis and down the length of the mother board. Heat from the components conduct along the PWB to the card guides. It then conducts down the chassis wall to the mounting feet and into the chassis heat sink (cold plate). The maximum PWB temperature is at the top center. The minimum is at the bottom of each card guide. The median is geometrically between the maximum and each minimum. This solution conducts heat along each board dimension and thus prefers small boards.

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Solution [2] is similar to solution [1]. Each DIP package is mounted on a thermal rail with each lead in a plated through hole. The rails have wedge locks to hold each card in a 0.50” slot. Heat from the components conduct along the rails to the wedge lock. It then conducts down the chassis wall to the mounting feet and into the chassis heat sink (cold plate). The maximum PWB temperature is at the top center. The minimum is at the bottom of each wedge lock. The median is geometrically between the maximum and each minimum. This solution conducts heat along each board dimension and thus prefers small boards.

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Solution [3] has a PWB with surface mount technology (SMT) components and a circuit side thermal plane. The thermal plane has wedge locks to hold each card in a 0.50” slot. Heat from the components conduct through the PWB and along the thermal plane to the wedge lock. It then conducts down the chassis wall to the mounting feet and into the chassis heat sink (cold plate). The maximum PWB temperature is at the top center. The minimum is at the bottom of each wedge lock. The median is geometrically between the maximum and each minimum. This solution conducts heat along each board dimension and thus prefers small boards.

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Solution [4] is like solution [3] with an additional PWB bonded to the thermal plane. Each PWB bonds its circuit side to the thermal plane. The extra PWB has plated through holes, located at the top, with jumper wires to the first PWB pads, located at the top. All input and output is managed through the connector of the first PWB. The thermal plane has wedge locks to hold each card in a 0.75” slot. Heat from the components conduct through each PWB and along the thermal plane to the wedge lock. It then conducts down the chassis wall to the mounting feet and into the chassis heat sink (cold plate). The maximum PWB temperature is at the top center. The minimum is at the bottom of each wedge lock. The median is geometrically between the maximum and each minimum. This solution conducts heat along each board dimension and thus prefers small boards.

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Solution [5] has the same mechanical design as solution [1], only the external cooling scheme is different. The sides have locking card guides to hold each card in a 0.50” slot. Heat from the components conduct along the PWB to the card guides and into the chassis. Radiation or convection (external air) takes the heat to the chassis heat sink. The maximum PWB temperature is in the center. The minimum is at each card guide. The median is geometrically between the maximum and each minimum. This solution conducts heat along the PWB width and thus prefers narrow boards.

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Solution [6] has the same chassis as solution [1] and the same PWB and component side thermal rail as solution [2]. The sides have locking card guides to hold each card in a 0.50” slot. Heat from the components conduct along the thermal rail, and PWB, to the card guides and into the chassis. Radiation or convection (external air) takes the heat to the chassis heat sink. The maximum PWB temperature is in the center. The minimum is at each card guide. The median is geometrically between the maximum and each minimum. This solution conducts heat along the PWB width and thus prefers narrow boards.

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Solution [7] has the same chassis as solution [1] and the same PWB and circuit side thermal plane as solution [3]. The sides have locking card guides to hold each card in a 0.50” slot. Heat from the components conduct along the thermal plane, and PWB, to the card guides and into the chassis. Radiation or convection (external air) takes the heat to the chassis heat sink. The maximum PWB temperature is in the center. The minimum is at each card guide. The median is geometrically between the maximum and each minimum. This solution conducts heat along the PWB width and thus prefers narrow boards.

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Solution [8] has the same chassis as solution [1] and the same PWB’s and circuit side thermal plane as solution [4]. The sides have locking card guides to hold each card in a 0.75” slot. Heat from the components conduct along the thermal plane, and PWB’s, to the card guides and into the chassis. Radiation or convection (external air) takes the heat to the chassis heat sink. The maximum PWB temperature is in the center. The minimum is at each card guide. The median is geometrically between the maximum and each minimum. This solution conducts heat along the PWB width and thus prefers narrow boards.

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Solution [9] is a PWB in a housing. Radiation or convection (internal air) takes the heat from the component case to the housing cover. Heat conducts through the cover. Radiation or convection (external air) takes the heat to the housing heat sink. The maximum, median, and minimum PWB temperature is the same. The component case temperature is the same as the PWB temperature. This solution has radiation and free convection from the entire component side and thus prefers large boards.

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Solution [10] is a PWB in a housing. Convection takes the heat from the component case to the PWB heat sink (internal housing air flow). The maximum, median, and minimum PWB temperature is the same. The component case temperature is the same as the PWB temperature. This solution has free convection from the entire component side and thus prefers large boards.

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form3

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form3Options

1. Select any scroll bar, option button, or “Calculate” button to input a unique value.

2. Select “Answers [1-10]” to move forward.

3. (Select “Card” to return to the previous form.)

4. (Select “End” to end the program session.)(“Surface Coefficient” is 5.0 to

50.0 Btu/hr-ft2-F for forced convection of air.)

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form4

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form4Options

1. Select an “External Cooling” option.

2. Select other options.

3. Select the “Run” button to calculate the new “Surface Coefficient”.

4. Select “Chassis” to return to the previous form.

5. (Select “End” to end the program session.)

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form5

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form5Options

1. Select a button under “CCA Default Values” to move forward.

2. (Select other options for a better view of the chassis cross-section.)

3. Select the “Card” button to return to the previous form.


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form6

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form6Options

1. Select an “External Cooling” option button.

2. Select an “Internal Cooling” option button.

3. Select “CCA Environment Data [9]” to move forward.

4. (Select the “Card” button to return to the previous form.)

5. (Select “Answers [1-10]” for a short-cut to your trade study.)


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form7

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form7Options

1. Select “Cover”, “Cover Width”, and “Cover Thickness”.

2. Select any other scroll bars and option buttons.

3. Select the “Run” command button to calculate the PWB temperature.

4. Select the “CCA Alone” button to return to the previous form.


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form8

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form8Options

1. Select “CCA Orientation”.

2. Select “Altitude”.

3. Select the “Run” command button to calculate the PWB temperature.


5. (Select the “Answers [1-10]” command button for a short-cut to the trade study.)


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form8Details

1. This PWB temperature is 100.65°C, as are the component cases.

2. This ambient air temperature is 71.00°C.

3. The PWB surface coefficient is 0.003243 W/in2-°C at sea level.

4. The surface coefficient is less at high altitude. At 82,000 ft (82 Kft) it is gone!

5. If many different components are on the PWB, each one may be characterized by its own case temperature (Tcase), case exposed surface area (Acase), case power dissipation (Pcase), and the PWB surface coefficient (hfree) to the PWB sink temperature (Tsink).

Pcase=hfree*Acase*(Tcase-Tsink)

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form9

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form9Options

1. Select any scroll bar.

2. Select “Setup Cards” to move forward.



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form9Numerical Solution Details

• The infrared emissivity of each conformal coated PWB and painted fin will be the same.

• The damping factor is the fraction of the latest temperature calculated weighted with the temperature of the previous iteration. Great damping is 0.10 and little damping is 0.90.

• The maximum allowable temperature change between iterations is a measure of the solution accuracy. A value of 0.0005 will take a large number of iterations to achieve, a value of 0.0100 will take only a few iterations.

• The maximum number of iterations is the total number of times that the implicit routine will be exercised. More iterations makes a better solution at the price of longer compute time.

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form10

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form10Options

1. Select “Total Number of slots”.

2. Select “CCA”.

3. Select “Input Data”.

4. Select “Calculate”.

5. Select “Slot Location”.

6. Select “Slot Type” scroll bar.

7. Select “CCA” or “Fin”.

8. Select “Slot Power per PWB”.

9. Select “Input Change”.

10. Repeat steps 5 through 9 for all unique cards.

11. Select “Calculate Changes”.

12. Select “PWB Detail Power” to solve this “Slot Location” PWB with concentrated power.

• (Select “Setup Scheme” to return to the previous form.)

• (Select “End” to end the program session.)

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form10Details

This solution has six cards (one fin and five CCA’s). The first CCA has 5.0 W and the other four have 3.0 W. Only 19 of the 50 iterations were performed. Slot #1 changed only 0.000832°C from the previous iteration and it was the largest changing temperature. A total of 17.0000 W was input and the solution calculated 17.0013 W output by the six cards. This gives a balance of 100.01% using a moderate damping factor (0.600).

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form11

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form11Options

1. Select “Number of Rows” and “Number of Columns” to define the thermal network grid.

2. Select “Row” and “Column” for the location of concentrated heat.

3. Select the “Node Power” scroll bar and “Input Power” command button.

4. Repeat steps 2 and 3 for the other nodes with concentrated heat.

5. Select “Distribute” for the balance of the card power.

6. Select “Display PWB Data” if solution [4] or [8] is being analyzed. Input data for the component and circuit side of the CCA. (The thermal plane mounts to the circuit side of each PWB. Note the view of the CCA is fixed! Input values for the CCA circuit side PWB by reference to the CCA coordinate system.)

7. Select “Number of Iterations”, “DAMPA” (Damping Factor), and “ARLXCA” (Maximum Allowable Temperature Change Per Iteration) as numerical solution criteria.

8. Select “Run1” to solve the network.

9. Select “Run2” to show the numerical values of the PWB maximum, median, and minimum temperatures.

10. Select “Run3” to show the graphical picture of the PWB maximum (Red), median (Blue), and minimum (Green) locations.

11. Select “Column” and “Row” to view that temperature in “Node Temp.” on any interesting node in the grid.

12. Select “Run2” or “Run3” at any time for reference. Select “Display PWB Data” and then “Run3” for solutions [4] or [8].

13. Select “Input to Box” to return to the previous form.

14. (Select “End’ to end the program session.)

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form11Example Display (1 of 6)

1. “Number of Columns”=6

2. “Number of Rows” =6

3. “Row” =3

4. “Column”=2

5. “Node Power”=1000 mW

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1. “Input Power”

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1. “Distribute”

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1. “Number of iterations” = 4100

2. “Run1”

3. Heat Balance = 0.9920 (99.20%) after 1800 of 4100 iterations.

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1. “Run2”

2. Heat Balance and PWB temperature statistics are shown.

3. Note that the boundary condition is shown.

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1. “Run3”

2. Tmax, Tmed, and Tmin are color coded from “Run2”.

Note: Concentrated heat should be biased toward the card guides (wedge locks)!

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Finish: form12

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Finish: form12Options

1. Note the net thermal conductivity of

the PWB is 0.510 W/in-°C.

2. Note the temperature distributions for all ten thermal solutions [1-10] in text and histograms.

3. Select “Forward” to model a box with several cards.

4. (Select under “Return” to return to a previous form.)

5. (Select “End the Program” to end the program session.)

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Finish: form12Notes

All ten thermal solutions are shown. Each has the same boundary

condition (71.000°C) from form1. If a comparison of two boards is made and the boundary condition is different, then the user must set the boundary condition for one, work through the forms to a solution, and then page back to input the second boundary condition to verify the second solution on this form.

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Government ReferencesUnited States of America

Department of DefenseMilitary Handbooks

1. MIL-HDBK-217D, “Reliability Prediction of Electronic Equipment”, 15 Jan 1982.

2. MIL-HDBK-251, “Reliability/Design Thermal Applications”, 19 Jan 1978.

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Specific References

1. Cooling Techniques for Electronic Equipment, Dave S. Steinberg, John Wiley & Sons, New York, 1980, ISBN 0-471-04403-2.

2. Principles of Heat Transfer, 2nd Ed., Frank Kreith, International Textbook Company, Scranton, Pennsylvania, 1965, Library of Congress Catalog Card Number 65-16305.

Documents

1. 2 Electronic Packaging Ten Thermal Solutions CardTemp, Version 3.45