Number
2.6.27
Subject
Thermal Stress, Convection Reflow Assembly
3000 Lakeside Drive, Suite 105N Simulation
Bannockburn, IL 60015-1249
Date Revision
2/2020 B
Originating Task Group
IPC-TM-650 Thermal Stress Test Methodology Subcommittee
TEST METHODS MANUAL (D-32)
1 Scope and Purpose 3 Test Specimen
1.1 Scope This method is intended to simulate exposure to 3.1 Design/Construction Criteria
the thermal conditions by convection reflow assembly.
3.1.1 The test specimen shall be the A/B, AB-R, and/or the
1.2 Purpose This method shall be used to replicate the D coupon as designed in accordance with the requirements of
thermodynamic effects by assembly on the test specimen. IPC-2221 Appendix A or B. Use of alternate specimens shall
The use of this method is intended to simulate those effects be AABUS.
that are the result of soldering thermal excursions.
3.1.2 The test specimen(s) shall be constructed with holes
1.2.1 This method shall be used for qualification testing of contained in the printed board it represents as follows:
an applicable test specimen. The evaluation of acceptability a. A/B, A/B-R and D coupons shall be constructed with
for qualification shall be in accordance with the requirements both the largest plated through-holes (PTHs) and the
defined in 5.3. smallest vias.
1.2.2 This method may be used for lot acceptance. The b. Propagated B and D coupons shall be constructed with
evaluation for lot acceptability should be in accordance with the intended via structure. (Multiple B and D coupons are
the requirements defined in 5.3 or as agreed upon between used for designs with multiple structures.)
user and supplier (AABUS). 3.1.2.1 The test specimen(s) shall contain the representa-
tive ground and power planes of the printed board design.
2 Applicable Documents
IPC-T-50 Terms and Definitions 3.1.2.2 The test specimen(s) shall contain the representa-
tive filled through vias, applicable blind and/or buried vias,
IPC-2221 Generic Standard on Printed Board Design including microvias, of the printed board design.
IPC-A-600 Acceptability of Printed Boards
3.1.3 The test specimen(s) shall allow for microsection
IPC-1601 Printed Board Handling and Storage Guidelines evaluation of all the applicable, representative PTHs and vias
defined in 3.1.2 after exposure to the conditions of this Test
IPC-6012 Qualification and Performance Specification for
Method.
Rigid Printed Boards
Note: Special tooling may be required for potting an entire
IPC-6013 Qualification and Performance Specification for
‘‘D’’ Coupon for microsection examination.
Flexible Printed Boards
IPC-6018 Qualification and Performance Specification for 3.1.4 Deviations to the test specimen design/construction
High Frequency (Microwave) Printed Boards or use of an alternate test specimen such as the printed board
or a section of the printed board shall be AABUS.
IPC-9241 Guidelines for Microsection Preparation
4 Apparatus
IPC-9631 User’s Guide for IPC-TM-650, Method 2.6.27
IPC-TM-650 Test Methods Manual1 4.1 Drying Oven
2.1.1 Microsectioning – Microsectioning, Manual and Semi 4.1.1 The oven shall be capable of maintaining a uniform
or Automatic Method set temperature within the 105 to 125 °C [221 to 257 °F]
range.
1. Current and revised IPC Test Methods are available on the IPC Web site (www.ipc.org/test-methods.aspx).
Material in this Test Methods Manual was voluntarily established by Technical Committees of IPC. This material is advisory only
and its use or adaptation is entirely voluntary. IPC disclaims all liability of any kind as to the use, application, or adaptation of this Page 1 of 10
material. Users are also wholly responsible for protecting themselves against all claims or liabilities for patent infringement.
Equipment referenced is for the convenience of the user and does not imply endorsement by IPC.
IPC-TM-650
Number Subject Date
2.6.27 Thermal Stress, Convection Reflow Assembly Simulation 2/2020
Revision
B
4.2 Convection Reflow Oven or Simulator 5.1 Conditioning
4.2.1 The system used to simulate the thermodynamic 5.1.1 The test specimen shall be conditioned by drying in an
effects of assembly shall be convection reflow. oven to remove moisture for a minimum of six (6) hours at 105 to
125 °C [221 to 257 °F].
4.2.1.1 The system shall have adequate environmental
controls to maintain the tolerance range and limits in accor- 5.1.2 Test specimens that are thicker or more complex may
dance with the reflow profile depicted in either Figure 5-1, require longer baking times to achieve acceptable moisture
Figure 5-2 or Figure 5-3. levels. Record the bake times and temperature if different than
those stated in 5.1.1. See IPC-1601 for additional guidance
4.2.1.2 The system should accommodate verifiable calibra- on baking to achieve acceptable moisture levels. See note
tion compliance and reflow profile generation. See note 6.1 for 6.2.
additional considerations.
5.1.3 Deviations to the conditioning requirements in 5.1.1
4.2.1.3 The test specimen shall be handled and stored in a such as when used for acceptance criteria and/or any
controlled environment to minimize moisture ingression. See changes to the time and temperature shall be AABUS. See
IPC-1601 for details on the proper handling and storage of 6.3.
test specimens.
5.2 Reflow Profile
4.2.2 Deviations to the equipment requirements and
5.2.1 Reflow the test specimen in accordance with Table
acceptability of the alternative methods shall be AABUS.
5-1 (default), Table 5-2 (low temperature profile) or Table 5-3.
4.3 Microscope
5.2.2 The reflow profile shall be in accordance with either
4.3.1 The magnification used for defect recognition must be Figure 5-1, Figure 5-2 or Figure 5-3. Figure 5-1 represents the
in agreement with the inspection requirements/capabilities default reflow profile. Figure 5-2 represents the low tempera-
defined in the applicable performance specification (e.g., IPC- ture profile. Figure 5-3 represents a 245 °C reflow profile. The
6012, IPC-6013, IPC-6018, etc.) and IPC-A-600. times to t1, t2 and t3 may vary based on the mass of the
sample test specimen. To avoid over stressing of samples,
4.4 Resistance Measurements of IPC-2221 Appendix A, times should be shortened for low mass samples. Times
D Coupons should be extended for high mass samples, such that the
zone (air) temperature shall not be more than 25 °C above
4.4.1 When specified by performance specification or pro- the target surface temperature at any point in the cycle.
curement documentation, resistance measurements of the
IPC-2221B Appendix A, D coupons shall be required. The attachment of thermocouples to the sample test speci-
men shall be such that the reflow profile is calibrated to the
4.4.2 The resistance measurement shall have enough pre- surface temperature of the test specimen.
cision to clearly determine the resistance percent change as
required by the user for the resistance level of each sample’s 5.2.3 The test specimen shall be subjected to a minimum
nets. of six (6) reflow cycles.
5.2.4 The cool down rate shall be in accordance with Table
4.4.3 The total system uncertainty from resistance, tem-
5-1, Table 5-2 or Table 5-3, based on the reflow profile
perature and time/cycle variations shall be less than 10% of
selected in 5.2.1. The cool down is complete when the test
the failure criteria required by the user. For example, if the
specimen reaches 45 °C. The test specimen shall achieve a
required failure criteria is 5% then the total system uncertainty
thermal equilibrium of 45 °C or less prior to starting the next
shall be no greater than 0.50%.
reflow cycle. If the time it takes to achieve thermal equilibrium
4.4.4 The resistance data shall consist of at least 1 reading cannot be determined, then a five (5) minute dwell between
per sample net every second during the entire reflow cycle. reflow cycles shall be required.
5 Procedure 5.2.5 Deviations to the reflow profile or number of cycles
shall be AABUS.
Page 2 of 10
IPC-TM-650
Number Subject Date
2.6.27 Thermal Stress, Convection Reflow Assembly Simulation 2/2020
Revision
B
Table 5-1 260 °C Nominal Reflow Profile Specifications (Default)*
Value Time (Seconds) Temperature (°C) Description
t1 210 ± 15 – Target preheat time
t2 270 ± 10 – Target peak reflow time
t3 330 ± 15 – Target cool-down start time
t3 - t1 120 ± 30 – Target time above T1
T1 – 230 Maximum preheat temperature
T2 – 260 ± 5 Target reflow temperature
Point Time (Seconds) Temperature (°C) Description
A 0 30
B 100 230
C 195 230
D 255 265 Upper specification limit values
E 285 265
F 345 230
G 550 30
H 30 30
I 157 93
J 225 230
K 260 255 Lower specification limit values
L 280 255
M 315 230
N 383 30
Segment Slope (°C / second) Description
A-B & I-J 2.0 Maximum preheat rate
H-I 0.5 Minimum preheat rate
F-G -1.0 Minimum cool-down rate
M-N -3.0 Maximum cool-down rate
Page 3 of 10
IPC-TM-650
Number Subject Date
2.6.27 Thermal Stress, Convection Reflow Assembly Simulation 2/2020
Revision
B
260 °C Reflow Profile Specifications
t1 t2 t3
300
USL LSL Example
D E
270
T2
B C K L F
240
T1
J M
210
Temperature (°C)
180
150
120
90
I
60
A G
30
0 H 60 120 180 240 300 360 N 420 480 540 600
Time (Seconds)
IPC-2627-5-1
Figure 5-1 260 °C Nominal Reflow Profile Chart (Default)*
Page 4 of 10
IPC-TM-650
Number Subject Date
2.6.27 Thermal Stress, Convection Reflow Assembly Simulation 2/2020
Revision
B
Table 5-2 230 °C Nominal Reflow Profile Specifications (Low Temperature Profile)*
Value Time (Seconds) Temperature (°C) Description
t1 186 ± 15 – Target preheat time
t2 239 ± 10 – Target peak reflow time
t3 292 ± 15 – Target cool-down start time
t3 - t1 106 ± 30 – Target time above T1
T1 – 203 Maximum preheat temperature
T2 – 230 ± 5 Target reflow temperature
Point Time (Seconds) Temperature (°C) Description
A 0 30
B 88 203
C 172 203
D 226 235 Upper specification limit values
E 252 235
F 305 203
G 487 30
H 30 30
I 139 83
J 199 203
K 230 225 Lower specification limit values
L 248 225
M 279 203
N 339 30
Segment Slope (°C / second) Description
A-B & I-J 2.0 Maximum preheat rate
H-I 0.5 Minimum preheat rate
F-G -1.0 Minimum cool-down rate
M-N -3.0 Maximum cool-down rate
Page 5 of 10
IPC-TM-650
Number Subject Date
2.6.27 Thermal Stress, Convection Reflow Assembly Simulation 2/2020
Revision
B
230 °C Reflow Profile Specifications
t1 t2 t3
300
USL LSL Example
270
D E
240
T2
B C K L F
210
Temperature (°C)
T1
J M
180
150
120
90
I
60
A G
30
0 H 60 120 180 240 300 N 360 420 480 540 600
Time (Seconds)
IPC-2627-5-2
Figure 5-2 230 °C Nominal Reflow Profile Chart (Low Temperature Profile)*
Page 6 of 10
IPC-TM-650
Number Subject Date
2.6.27 Thermal Stress, Convection Reflow Assembly Simulation 2/2020
Revision
B
Table 5-3 245 °C Nominal Reflow Profile Specifications*
Value Time (Seconds) Temperature (°C) Description
t1 198 ± 15 – Target preheat time
t2 254 ± 10 – Target peak reflow time
t3 311 ± 15 – Target cool-down start time
t3 - t1 113 ± 30 – Target time above T1
T1 – 217 Maximum preheat temperature
T2 – 245 ± 5 Target reflow temperature
Point Time (Seconds) Temperature (°C) Description
A 0 30
B 94 217
C 184 217
D 240 250 Upper specification limit values
E 269 250
F 325 217
G 518 30
H 30 30
I 148 88
J 212 217
K 245 240 Lower specification limit values
L 264 240
M 297 217
N 361 30
Segment Slope (°C / second) Description
A-B & I-J 2.0 Maximum preheat rate
H-I 0.5 Minimum preheat rate
F-G -1.0 Minimum cool-down rate
M-N -3.0 Maximum cool-down rate
Page 7 of 10
IPC-TM-650
Number Subject Date
2.6.27 Thermal Stress, Convection Reflow Assembly Simulation 2/2020
Revision
B
IPC-2627-5-3
Figure 5-3 245 °C Nominal Reflow Profile Chart*
* The times to t1, t2 and t3 may vary based on the mass of the sample test specimen.
Page 8 of 10
IPC-TM-650
Number Subject Date
2.6.27 Thermal Stress, Convection Reflow Assembly Simulation 2/2020
Revision
B
5.3 Evaluation applicable test specimen designs encountered. Some issues
to consider are as follows:
5.3.1 Microsection The test specimen shall be microsec-
• Thermal mass compensation capability (energy vs. time)
tioned when this test method is used for thermal stress prior
to structural integrity evaluation. After the test specimen has • Environmental control capability (heating and cooling)
been conditioned and reflowed in accordance with the
• Reproducibility of parameters
requirements of 5.1 and 5.2, microsection the test specimen
in accordance with IPC TM-650 Method 2.1.1. Inspect speci- • Preheat
mens required for microsection (e.g., A, B, A/B, AB/R, etc.) for
• Conveyor speed (if applicable)
compliance to the applicable performance specification
and/or AABUS requirement. • Heating ramp rate
Note: For guidelines on microsection preparation see IPC- • Cool down rate
9241.
• Programming capability
5.3.2 Resistance Change Resistance change shall be • Profile memory
used to evaluate IPC-2221 Appendix A (latest revision)
The IPC-TM-650 website provides a non-comprehensive list-
D-coupons for performance-based evaluation of the samples
ing of providers of convection reflow systems suitable for
when specified. Microsectioning of D coupons which have
meeting the reflow profiles within this test method.
been evaluated by resistance change is not required.
6.2 Deviations to the time and temperature specified in 5.1.1
5.3.2.1 Percent change in resistances of each sample’s
should take into consideration maintaining the solderability of
nets shall be determined using the first cycle’s peak tempera-
the surface finish being utilized.
ture resistance as the reference.
6.3 Example Drawing Notes As this method addresses
5.3.2.2 The maximum allowable percent change in resis-
assembly issues with printed boards, it is recommended that
tance after the test specimen has been conditioned and
the user of the printed board establish a drawing note in the
reflowed in accordance with 5.1 and 5.2 shall be 5% maxi-
procurement documentation to provide the printed board fab-
mum unless otherwise specified.
ricators with guidance relative to the intended reflow process
of the printed board. An example of such a drawing note is
5.3.2.3 Cycles to failure, corresponding percent change of
provided as follows:
the failure, and the percent change of the final cycle shall be
documented. A. IPC D COUPONS SHALL BE DESIGNED IAW IPC-2221
APPENDIX A AND SHALL INCLUDE COMPONENT (A),
5.3.3 Deviations to the stated requirements or additional VIA (B) AND ALL PROPAGATED B STRUCTURES. X OF
requirements defined here shall be AABUS. EACH COUPON DESIGN SHALL BE TESTED PER
MANUFACTURING PANEL.
6 Notes B. THE IPC D COUPONS SHALL BE SUBJECTED TO 6
REFLOW SIMULATIONS IAW IPC-TM-650, METHOD
6.1 The design of the convection reflow system should be 2.6.27 USING THE [230 °C, 245 °C, OR 260 °C] PRO-
flexible enough to facilitate the creation of the reflow profiles FILE. ACCEPTANCE CRITERIA SHALL BE < 5%
depicted in Figure 5-1, Figure 5-2 and Figure 5-3 for all the CHANGE IN RESISTANCE.
Page 9 of 10
IPC-TM-650
Number Subject Date
2.6.27 Thermal Stress, Convection Reflow Assembly Simulation 2/2020
Revision
B
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