CardTemp Manual,
Version 3.45
Copyright © 2011 Advanced Thermal Engineering, Inc.
All Rights Reserved
P. O. Box 4528
Huntsville, AL 35815
USA
1
Electronic Packaging
Ten Thermal Solutions
CardTemp, Version 3.45
2
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).
3
CardTemp
PWB 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.
4
CardTemp
Ten 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.
5
Post Processing Values
6
Case Temperature
Plated 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.
7
Case Temperature
Circuit 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 wedgelocks.
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.
8
Case Temperature
Component Side Thermal Rail
Calculate the Component Case Temperature for a Dual-InlinePackage (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
9
Case temperature
Free 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
10
Case Temperature
Radiation
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
11
Junction Temperature
Calculate the Component Junction Temperature.
Tjunc = Tcase + Rcj*Pcase
Where:
Tjunc is the component junction temperature.
Tcase is the component case temperature.
Rcj is the thermal resistance from the case to the junction.
Pcase is the component power dissipation.
12
Electronic Packaging
Reliability
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.
13
User’s Guide
14
CardTemp, Version 3.45
Copyright © 2011 Advanced Thermal Engineering, Inc.
All Rights Reserved
The legal license is found in two
PDF files. Select the executable
file to start the program. Select
buttons to navigate the various
forms.
CARD345.exe
612 KB
LICE343.pdf
7 KB
READ343.pdf
20 KB
15
CardTemp
Look 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.
16
CardTemp
Forms of the Program
Table I. Form Titles
Name
Start:
Finish:
Title
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)
form12 (Output)
Answers (form1-form8)
17
CardTemp
Navigating the Program
Start: form1
form2
form8 [10]
form5
form3 [1-8]
Finish: form12 [1-10]
form6 [9]
form7 [9]
form4 [5-8]
form9 [1-8]
form10 [1-8]
form11 [1-8]
18
CardTemp
Manipulating the Program
Start: form1
form2
form8 [10]
form5
form3 [1-8]
Finish: form12 [1-10]
form6 [9]
form7 [9]
form4 [5-8]
form9 [1-8]
form10 [1-8]
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.
19
CardTemp
Advanced User
Start: form1
form2
form8 [10]
form5
form3 [1-8]
Finish: form12 [1-10]
form6 [9]
form7 [9]
form4 [5-8]
form9 [1-8]
form10 [1-8]
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.
20
CardTemp
Very Advanced User
Start: form1
form2
form8 [10]
form5
form3 [1-8]
Finish: form12 [1-10]
form6 [9]
form7 [9]
form4 [5-8]
form9 [1-8]
form10 [1-8]
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.
21
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.
22
Form Details
23
Start: form1
24
Start: form1
Options
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.)
25
Start: form1
Details
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.
26
form2
27
form2
Options
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.)
28
form2
CCA 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
29
each board dimension and thus prefers small boards.
form2
CCA Descriptions [2]
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.
30
form2
CCA Descriptions [3]
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.
31
form2
CCA Descriptions [4]
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.
32
form2
CCA Descriptions [5]
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.
33
form2
CCA Descriptions [6]
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.
34
form2
CCA Descriptions [7]
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.
35
form2
CCA Descriptions [8]
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.
36
form2
CCA Descriptions [9]
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.
37
form2
CCA Descriptions [10]
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.
38
form3
39
form3
Options
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.)
(“Surface Coefficient” is 5.0 to
50.0 Btu/hr-ft2-F for forced
convection of air.)
4. (Select “End” to end the
program session.)
40
form4
41
form4
Options
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.)
42
form5
43
form5
Options
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.
4. (Select “End” to end the
program session.)
44
form6
45
form6
Options
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 shortcut to your trade study.)
6.
(Select “End” to end the program
session.)
46
form7
47
form7
Options
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.
5.
(Select “End” to end the program
session.)
48
form8
49
form8
Options
1.
Select “CCA Orientation”.
2.
Select “Altitude”.
3.
Select the “Run” command button to
calculate the PWB temperature.
4.
Select the “Card” button to return to
the previous form.
5.
(Select the “Answers [1-10]”
command button for a short-cut to
the trade study.)
6.
(Select “End” to end the program
session.)
50
form8
Details
Pcase=hfree*Acase*(Tcase-Tsink)
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).
51
form9
52
form9
Options
1. Select any scroll bar.
2. Select “Setup Cards” to move
forward.
3. Select the “Card” button to return
to the previous form.
4. (Select “End” to end the program
session.)
53
form9
Numerical 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.
54
form10
55
form10
Options
•
•
(Select “Setup Scheme” to
return to the previous
form.)
(Select “End” to end the
program session.)
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.
56
form10
Details
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).
57
form11
58
form11
Options
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.)
59
form11
Example 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
60
form11
Example Display (2 of 6)
1. “Input Power”
61
form11
Example Display (3 of 6)
1. “Distribute”
62
form11
Example Display (4 of 6)
1. “Number of
iterations” = 4100
2. “Run1”
3. Heat Balance =
0.9920 (99.20%)
after 1800 of 4100
iterations.
63
form11
Example Display (5 of 6)
1. “Run2”
2. Heat Balance and
PWB temperature
statistics are shown.
3. Note that the
boundary condition
is shown.
64
form11
Example Display (6 of 6)
1. “Run3”
2. Tmax, Tmed, and Tmin
are color coded from
“Run2”.
Note: Concentrated heat should be biased
toward the card guides (wedge locks)!
65
Finish: form12
66
Finish: form12
Options
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.)
67
Finish: form12
Notes
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.
68
Government References
United States of America
Department of Defense
Military Handbooks
1.
2.
MIL-HDBK-217D, “Reliability Prediction of
Electronic Equipment”, 15 Jan 1982.
MIL-HDBK-251, “Reliability/Design
Thermal Applications”, 19 Jan 1978.
69
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.
70