IPC-TM-650 EN 2022 试验方法.pdf - 第328页
6.2 There are several methods for determining the T g of an organic material: • Differential scanning calorimetry (DSC) • TMA • DMA T g in organic materials is a broad transition, which arises when molecular mobility gre…
a.
CTE below glass transition:
α
(B–A
)
=
(L
B
–L
A
)10
6
L
o
(T
B
–T
A
)
For
most materials, this will be in the range of 7 ppm to 50
ppm (reinforced) or 30 ppm to 150 ppm (unreinforced).
b. CTE above glass transition:
α
(D–C
)
=
(L
D
–L
C
)10
6
L
o
(T
D
–T
C
)
For
most materials, this will be in the range of 50 ppm to 100
ppm (reinforced) or 150 ppm to 500 ppm (unreinforced). Any
reinforced materials, where the reinforcement has a negative
CTE, will shrink rather than expand when heated above T
g
of
the
resin.
Where:
T
A
=
Temperature at point A in Figure 2
T
B
=
Temperature at point B in Figure 2
T
C
=
Temperature at point C in Figure 2
T
D
=
Temperature at point D in Figure 2
L
0
=
Initial Length or thickness
L
A
=
Length or thickness at point A in Figure 2
L
B
=
Length or thickness at point B in Figure 2
L
C
=
Length or thickness at point C in Figure 2
L
D
=
Length or thickness at point D in Figure 2
5.4.3
Instantaneous Coefficient of Thermal Expansion
Curve (Optional)
The
instantaneous CTE expansion curve
is the slope of the TMA expansion curve plotted as a function
of temperature. Figure 3 shows a combined expansion curve
and its resulting instantaneous CTE curve.
Instantaneous CTE (α
Ti
)
is calculated at each temperature (T
i
)
from
the slope of the TMA expansion curve (dL
i
/dT)
at that
temperature:
α
Ti
=
1
L
o
(
dL
i
dT
)
dL/dT
is determined at each temperature (T
i
)
from the L vs. T
curve by:
(
dL
i
dT
)
=
(L
i+1
− L
i
)
(T
i + 1
− T
i
)
This
calculation can be done in a spreadsheet that contains
the L vs. T data. Some TMA computer analysis software per-
forms this calculation for you. For an example of plot αη
Ti
vs
temperature,
see Figure 3.
5.4.4
Percent Thermal Expansion (PTE) (Optional)
The
total
percent of thermal expansion is calculated as follows:
Percent TE =
(T
D
–T
A
)
L
o
*
100
For consistency, it is recommended that the TMA computer
analysis software be used for this calculation.
5.5
Report
5.5.1
Report
the glass transition temperature of each speci-
men, rounding to the nearest whole number.
5.5.2
Report
the CTE in ppm/°C above and below T
g
and
the
temperature ranges over which the thermal expansion
was determined. For Method B, report x and y CTE values.
5.5.3 Optionally
report the PTE in percent and the tempera-
ture ranges over which the thermal expansion was deter-
mined.
5.6 Plot
5.6.1
Plot
the expansion (µm) vs. temperature (°C) for the
specimen. If using computer based analysis, include the T
g
and
CTE measurement start points and computer generated
lines (see Figure 2).
5.6.2
Optionally
plot the instantaneous CTE (µm/°C) vs.
temperature (°C) for the specimen (see Figure 3).
5.6.3
Optionally
plot the percent expansion vs. temperature
(°C) for the specimen. If using computer-based analysis,
include the PTE measurement start points on the plot.
6.0
Notes
6.1
Calibration
of the TMA must be carried out according to
the manufacturer’s instructions for both probe expansion and
specimen temperature.
IPC-TM-650
Number
2.4.24.5
Subject
Glass
Transition Temperature and Thermal Expansion of
Materials Used in High Density Interconnection (HDI) and
Microvias - TMA Method
Date
11/98
Revision
P
age4of5
电子技术应用 ｗｗｗ．ＣｈｉｎａＡＥＴ．ｃｏｍ
6.2
There
are several methods for determining the T
g
of
an
organic material:
• Differential scanning calorimetry (DSC)
• TMA
• DMA
T
g
in organic materials is a broad transition, which arises when
molecular mobility greatly increases in the specimen as a
result of heating. No one method is superior to another; they
each measure different physical changes that occur in a
specimen near and around T
g
.
DSC
measures the heat capacity of a specimen. TMA mea-
sures the expansion of a specimen and DMA (dynamic
mechanical analysis) measures the stiffness of the specimen.
The T
g
determined
from TMA, DSC, and DMA may vary sig-
nificantly (up to 10°C) because they are measuring different
physical properties, which change differently as the specimen
goes through T
g
.
As a result, the test equipment used should
be noted after the reported T
g
value
(i.e., 136°C; DSC, TMA,
or DMA).
6.3
Most
thermal analysis equipment have the software
capability to determine T
g
and
CTE values; it is recommended
that this approach be used for consistency.
6.4
To
improve the accuracy of this test:
Method
A
Increase
the thickness to 0.76 mm or higher. Do
not stack single layers of thinner materials to achieve the mini-
mum thickness; this greatly increases test error.
Method
B
Be
sure the specimen is mounted in the clamps
correctly and that any clamp expansion is corrected properly
by calibration of the probe. Method B clamps and specimens
may have more difficulty reaching thermal equilibrium.
6.5
Load Selection Criteria
Method A
The
initial load is 2 g. The load may be adjusted
for differences in material types or specimen configuration in
order to assure intimate contact between the probe, speci-
men, and stage. Avoid an excess load (15 g), which may
result in penetration or distortion of the specimen.
Method
B
The
initial load is5goftension (approximately
50 mN). The load (or force) may be adjusted for differences in
material types or specimen configuration in order to assure
that the specimen is being held without slack. Avoid an exces-
sive load (or force), which may result in elongation of the
specimen due to the applied tension. Specimens above T
g
may
become so soft as to be stretched.
Examine all specimens after the test to look for signs of exces-
sive loads, distortions, tears, and other defects.
IPC-TM-650
Number
2.4.24.5
Subject
Glass
Transition Temperature and Thermal Expansion of
Materials Used in High Density Interconnection (HDI) and
Microvias - TMA Method
Date
11/98
Revision
P
age5of5
电子技术应用 ｗｗｗ．ＣｈｉｎａＡＥＴ．ｃｏｍ
1 Scope This test method establishes a procedure for
determining the thermal decomposition temperature (T
d
)of
base laminate materials using thermogravimetric analysis
(TGA). Use of this test method for printed wiring boards or
other composites may not yield comparative results.
2 Applicable Documents All terms and definitions in this
document conform to IPC-T-50, Terms and Definitions for
Interconnecting and Packaging Electronic Circuitry.
3 Test Samples
3.1 Sample Construction
The sample may be an unclad
laminate material or laminate material with copper completely
removed and that has been cut (using water cooling/cleaning
only, no oil) approximately square to fit into the TGA sample
pan. Typical sample mass (weight) is 10 mg to 30 mg.
Samples shall be cut to the specified size using appropriate
procedures and equipment to minimize mechanical stress
and/or thermal shock.
Note: Samples of the same mass but with a smaller surface
area may lose mass at a slower rate.
3.2 Surface Preparation All edges of the sample shall be
finished smooth and burr-free by sanding or equivalent (to
allow the sample to rest completely flat on the sample pan).
Use care to minimize the introduction of mechanical stress or
heat to the sample.
3.3 Mass Measurement The accuracy of the mass mea-
surements shall be within ± 0.01 mg.
4 Equipment/Apparatus or Material
4.1 Thermogravimetric Analyzer (TGA)
Thermal gravi-
metric analysis instrument shall comprise the following:
4.1.1 Microbalance, null type, sensitive to 0.001 mg.
4.1.2 Furnace equipped with dry (dew point below -68°C
[-90°F], moisture less than 3.5 ppm) nitrogen (less than
20 ppm oxygen) purge.
4.1.3 Temperature programmer capable of providing con-
trolled 10°C ± 0.1°C [18°F ± 0.18°F] per minute heating rate
from ambient to 800°C [1472°F].
4.2 Mass Measurement Capability The TGA shall be
capable of measuring mass to within 0.01 mg of actual value.
5 Procedure
5.1 Test Sample Preparation
The test samples should be
baked at 110°C ± 2°C [230.0°F ± 3.6°F] for 24 hr and placed
in a desiccator for cooling to room temperature (equilibration)
prior to testing. In standard lab conditions, the TGA test
should be started within 15 minutes of removing test sample
from the dessicator because samples may gain mass due to
moisture absorption.
5.2 Equipment Startup and Calibration (Follow Manu-
facturer’s Recommendations.)
5.2.1 Calibrate the balance to within ± 0.01 mg.
5.2.2 Calibrate the temperature sensor to within ± 1.0°C
[1.8°F].
5.2.3 Set the purge rate of 55 cc/min (0.9 mL/s). Run the
TGA gas purge for 30 minutes before inserting a sample. The
rate of flow of the gas in the cell will have a significant effect
on the calibration, therefore, the instrument must be calibrated
with the same flow rate as is used during the test. The tem-
perature sensor should be positioned so that it does not come
into contact with sample at any time. After the temperature
sensor has been correctly positioned, the instrument can be
calibrated. Neither the sensor position nor the flow rate should
be subsequently changed.
5.3 Heating Sample
5.3.1
Place the sample in the TGA and measure its mass.
5.3.2 Heat the sample at a rate of 10°C/min from ambient
(not to exceed 50°C) to 550°C.
3000 Lakeside Drive, Suite 309S
Bannockburn, IL 60015-1219
IPC-TM-650
TEST METHODS MANUAL
Number
2.4.24.6
Subject
Decomposition Temperature (T
d
) of Laminate
Material Using TGA
Date
4/06
Revision
Originating Task Group
Laminate/Prepreg Materials Subcommittee (3-11)
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
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.
Page1of2
ASSOCIATION CONNECTING
ELECTRONICS INDUSTRIES
®