Modified Coffin-Manson
Equation for AF Calculations
• Modified Coffin-Manson (Norris-Landzberg) Equation
Used to Determine Acceleration Factor from ATC to
Field Conditions:
1/3
1.9
[ ]() ( {
∆T
AF =
l
∆T f
ff
fl
exp
1414
1
T max
1
f
T max
})
l
• Where:
AF = Calculated Acceleration Factor (on a Cycle Basis).
∆T = Package/Board Temperature Difference Between Ton and Toff (°K).
Tmax = Maximum Solder Joint Temperature (°K).
f = Cyclic Frequency (in Cycles per 24 Hour Day). Minimum Number of Six
Which Assumes Maximum Damage Takes Place Within Four Hours.
f, l = Subscripts to Denote Field and Lab (i.e., ATC) Conditions, Respectively.
m
Customer Applications Support 512-933-7289
10 April , 1998
Information and Asssumptions
The key temperature for predicting the board level solder joint reliability is the
temperature of the solder balls at the board. It is not the device junction temperature.
The examples given are for illustration. Individual applications can be addressed
by contacting the Customer Applications Support department.
The Coffin-Manson predictions are generally recognized as “conservative” or to
pessimistically predict failures under most long term use conditions.
New data and process improvements are an ongoing effort and for the latest
information please contact your SPS Sales contact or the Customer Applications
Support department.
The design of the board that the CBGA is assembled to affects the solder joint reliability as
well as attachment of heat sinks. Most life testing is done on an FR-4 2S,2P board that is
0.062 inches thick and the components are assembled on one side. Other materials and
configurations can be tested by special request through your SPS Sales contact.
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Customer Applications Support 512-933-7289
10 April , 1998
FR-4 Board
1 cycle per day
0.01% Cumulative Failure Rate Prediction
Lifetime in Years
1000.00
CBGA
Size, Thickness
100.00
21 mm, 1.0 mm
25 mm, 1.0 mm
25 mm, 1.2 mm
10.00
35
30
25
20
15
10
1.00
Delta T in Celsius
Toff = 50C
m
Customer Applications Support 512-933-7289
10 April , 1998
Thermount Board
1 cycle per day
0.01% Cumulative Failure Rate Prediction
Lifetime in Years
1000.00
CBGA
Size, Thickness
100.00
21 mm, 1.0 mm
25 mm, 1.0 mm
25 mm, 1.2 mm
10.00
35
30
25
20
15
10
1.00
Delta T in Celsius
Toff = 50C
m
Customer Applications Support 512-933-7289
10 April , 1998
Case A: 21 mm, 1mm Thick CBGA Solder Joint Reliability
Time to 0.5% Packaging Failure (Years)
Norris-Landzberg Predictions from Accelerated Thermal Cycling Data
1000
21mm CBGA 200 work day/yr
21mm CBGA 365 work day/yr
100
Case A Assumptions
• Toff = 23°C
• 6 cycles per 10 hour day
• 200 & 365 work days per year
• Log Normal 0.5% Failure
extrapolations from -40 to 125 °C
21 mm CBGA ATC Data
10
1
0
10
20
30
40
50
60
70
80
Delta T (°C)
m
Customer Applications Support 512-933-7289
10 April , 1998
Case B: 21 mm, 1mm Thick CBGA Solder Joint Reliability
Time to 0.5% Packaging Failure (Years)
Norris-Landzberg Predictions from Accelerated Thermal Cycling Data
1000
21mm CBGA 200 work day/yr
21mm CBGA 365 work day/yr
100
Case B Assumptions
• Toff = 40 °C
• 6 cycles per 10 hour day
• 200 and 365 work days per year
• Log Normal 0.5% Failure
extrapolations from -40 to 125 °C
21 mm CBGA ATC Data
10
1
0
10
20
30
40
50
60
70
80
Delta T (°C)
m
Customer Applications Support 512-933-7289
10 April , 1998
Case C: 21 mm, 1mm Thick CBGA Solder Joint Reliability
Time to 0.5% Packaging Failure (Years)
Norris-Landzberg Predictions from Accelerated Thermal Cycling Data
1000
21mm CBGA 200 work day/yr
21mm CBGA 365 work day/yr
100
Case C Assumptions
• Toff = 23 °C
• 10 cycles per 10 hour day
• 200 and 365 work days per year
• Log Normal 0.5% Failure
extrapolations from -40 to 125 °C
21 mm CBGA ATC Data
10
1
0
m
10
20
30
40
50
60
70
80
Delta T (°C)
Customer Applications Support 512-933-7289
10 April , 1998
Case D: 21 mm, 1mm Thick CBGA Solder Joint Reliability
Time to 0.5% Packaging Failure (Years)
Norris-Landzberg Predictions from Accelerated Thermal Cycling Data
1000
21mm CBGA 200 work day/yr
21mm CBGA 365 work day/yr
100
Case D Assumptions
• Toff = 40 °C
• 10 cycles per 10 hour day
• 200 and 365 work days per year
• Log Normal 0.5% Failure
extrapolations from -40 to 125 °C
21 mm CBGA ATC Data
10
1
0
10
20
30
40
50
60
70
80
Delta T (°C)
m
Customer Applications Support 512-933-7289
10 April , 1998
Case E: 21 mm, 1mm Thick CBGA Solder Joint Reliability
Time to 0.5% Packaging Failure (Years)
Norris-Landzberg Predictions from Accelerated Thermal Cycling Data
1000
21mm CBGA 200 work day/yr
21mm CBGA 365 work day/yr
100
10
Case E Assumptions
• Toff = 23 °C
• 1 cycles per 10 hour day
• 200 and 365 work days per year
• Log Normal 0.5% Failure
extrapolations from -40 to 125 °C
21 mm CBGA ATC Data
1
0
10
20
30
40
50
60
70
80
Delta T (°C)
m
Customer Applications Support 512-933-7289
10 April , 1998
Case F: 21 mm, 1mm Thick CBGA Solder Joint Reliability
Time to 0.5% Packaging Failure (Years)
Norris-Landzberg Predictions from Accelerated Thermal Cycling Data
1000
21mm CBGA 200 work day/yr
21mm CBGA 365 work day/yr
100
Case F Assumptions
• Toff = 40 °C
• 1 cycles per 10 hour day
• 200 and 365 work days per year
• Log Normal 0.5% Failure
extrapolations from -40 to 125 °C
21 mm CBGA ATC Data
10
1
0
10
20
30
40
50
60
70
80
Delta T (°C)
m
Customer Applications Support 512-933-7289
10 April , 1998
25 mm, 1mm Thick CBGA Solder Joint Reliability With 4 Balls Off
Time to 0.5% Packaging Failure (Years)
Norris-Landzberg Predictions from Accelerated Thermal Cycling Data
6
6
3
3
100
cpd,365
cpd,200
cpd,365
cpd,200
day/year,Toff=23
day/year,Toff=23
day/year,Toff=23
day/year,Toff=23
10
Assumptions
• Toff = 23 °C
• 3 & 6 cycles per 10 hour day
• 200 and 365 work days per year
• Log Normal 0.5% Failure
extrapolations from 20-80 °C
25mm ATC Data
1
0.1
0
5
10
15
20
25
30
35
Delta T (°C)
m
Customer Applications Support 512-933-7289
10 April , 1998
25 mm, 1mm Thick CBGA Solder Joint Reliability With 4 Balls Off
Time to 0.5% Packaging Failure (Years)
Norris-Landzberg Predictions from Accelerated Thermal Cycling Data
100
6 cpd,365 day/year,Toff=40
6 cpd,200 day/year,Toff=40
3 cpd,365 day/year,Toff=40
33 cpd,200
cpd,365 day/year,Toff=40
day/year,Toff=40
10
Assumptions
• Toff = 40 °C
• 3 & 6 cycles per 10 hour day
• 200 and 365 work days per year
• Log Normal 0.5% Failure
extrapolations from 20-80 °C
25mm ATC Data
1
0.1
0
m
5
10
15
20
25
30
35
Delta T (°C)
Customer Applications Support 512-933-7289
10 April , 1998
21x25 mm, 1mm Thick CBGA Solder Joint Reliability
Time to 0.5% Packaging Failure (Years)
Norris-Landzberg Predictions from Accelerated Thermal Cycling Data
6
6
3
3
cpd,365
cpd,200
cpd,365
cpd,200
day/year,Toff=23
day/year,Toff=23
day/year,Toff=23
day/year,Toff=23
100
10
Assumptions
• Toff = 23 °C
• 3 & 6 cycles per 10 hour day
• 200 and 365 work days per year
• Log Normal 0.5% Failure
extrapolations from 0-100 °C
21x25mm ATC Data
1
0
m
5
10
15
20
25
30
35
Delta T (°C)
Customer Applications Support 512-933-7289
10 April , 1998
21x25 mm, 1mm Thick CBGA Solder Joint Reliability
Time to 0.5% Packaging Failure (Years)
Norris-Landzberg Predictions from Accelerated Thermal Cycling Data
6 cpd,365 day/year,Toff=40
6 cpd,200 day/year,Toff=40
3 cpd,365 day/year,Toff=40
33 cpd,200
cpd,365 day/year,Toff=40
day/year,Toff=40
100
10
Assumptions
• Toff = 40 °C
• 3 & 6 cycles per 10 hour day
• 200 and 365 work days per year
• Log Normal 0.5% Failure
extrapolations from 0-100 °C
21x25mm ATC Data
1
0.1
0
m
5
10
15
20
25
30
35
Delta T (°C)
Customer Applications Support 512-933-7289
10 April , 1998