IPC-TM-650 EN 2022 试验方法.pdf - 第367页
5.2.2 Condition E-1/110. 5.2.3 Condition C 1 -40/23/50. 5.3 Calibration 5.3.1 The transducer shall be calibrated by imposing a series of known displacements with a precision screw micrometer or set of end gage blocks. 5.…
1.0
Scope
1.1
To
describe the vitreous silica dilatometer method for
determining the linear thermal expansion of laminated materi-
als within the temperature range of –55°C to 100°C. Inorganic
substrates (non-laminated) shall be tested within a range of
–55° to 150°C.
2.0
Applicable Documents
ASTM-E-228
Standard
Test Method for Linear Thermal
Expansion of Solid Materials with a Vitreous Silica Dilatometer
ASTM-D-696
Test
for Coefficient of Linear Thermal Expan-
sion of Plastics
ASTM-E-831
Test
for Linear Thermal Expansion of Solid
Materials by Thermodilatometry
ASTM-E-77
Verification
and Calibration of Liquid-in-Glass
Thermometers
ASTM-E-220
Calibration
of Thermocouples by Comparison
Techniques
ASTM-E-644
Testing
Industrial Resistance Thermometers
3.0
Test Specimen
3.1
Laminated
materials which may or may not contain
metal layers.
3.2
Nominal
test specimen dimensions shall be 1/4 inch
wide x 2 inch –4 inch long x 1/8 inch minimum thickness. End
surfaces shall be ground parallel. Any deviation from nominal
should recognize thermal gradients of the temperature cham-
ber, thermal lag of specimen and any bending of specimen.
Thicknesses under 1/8 inch shall be supported by adequate
clamping devices unless it is certain that the specimen will
remain straight during testing.
4.0 Apparatus
4.1
Vitreous
silica dilatometer of either the tube or push rod
type to determine the change in length of a solid material as a
function of temperature. The temperature is controlled at a
constant heating or cooling rate. The linear thermal expansion
and the coefficients of linear thermal expansion (CTE) are cal-
culated from the recorded data.
This device measures the difference in thermal expansion
between a test specimen and the vitreous silica parts of the
dilatometer (Figure 1).
4.2
Specimen
holder (tube) and probe shall be made of vit-
reous silica. The probe contact shall be flat or be rounded to
approximately a 10 mm radius.
4.3
Chamber
for uniformly heating and cooling the speci-
men. The specimen temperature change rate shall be con-
trolled. The temperature gradient in the specimen shall not
exceed 0.5°C/cm.
4.4
Transducer,
for measuring the difference in length
between the specimen and the specimen holder with an
accuracy of at least ± 0.5µm. The transducer shall be pro-
tected or mounted so that temperature changes will not affect
the readings by more than 1.0µm.
4.5 Micrometer,
for measuring the reference length, L
o
,o
f
the specimen with an accuracy of at least ± 25µm.
4.6
Thermocouple,
types E, K, or T, for measurement of the
specimen temperature. (Type E is NiCr versus constantan,
type K is NiCr versus NiAl and Type T is Cu versus constan-
tan.)
4.7
Recorder
or data logger for collecting temperatures and
lengths.
5.0
Procedure
5.1 Sample Preparation
Rough
cut with a band saw or
metallurgical cut-off wheel and finish machining by grinding.
Care must be exercised to remove roughness from specimen
ends. The ends shall be parallel to ± .001 inch/inch.
5.2
Sample
condition (only for laminated, organic speci-
mens).
5.2.1
The
specimen shall be immersed in isopropyl alcohol
and agitated for twenty seconds.
The
Institute for Interconnecting and Packaging Electronic Circuits
2215 Sanders Road • Northbrook, IL 60062-6135
IPC-TM-650
TEST
METHODS MANUAL
Number
2.4.41.1
Subject
Coefficient
of Thermal Expansion by the Vitreous
Silica (Quartz) Dilatometer Method
Date
8/97
Revision
A
Originating Task Group
N/A
Material
in this Test Methods Manual was voluntarily established by Technical Committees of the 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 the IPC.
P
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5.2.2
Condition
E-1/110.
5.2.3
Condition
C
1
-40/23/50.
5.3
Calibration
5.3.1
The
transducer shall be calibrated by imposing a
series of known displacements with a precision screw
micrometer or set of end gage blocks.
5.3.2
The
temperature sensor shall be calibrated according
to an appropriate ASTM method (E-220) or procedure recom-
mended by the National Bureau of Standards.
5.3.3
The
dilatometer, as a total system, shall be calibrated
by measuring two reference materials of known thermal
expansion. One of the materials should have an expansion
close to the sample specimen, and the other close to that of
the dilatometer.
5.3.4
Recommended standard reference materials:
•
NBS Fused Silica – SRM 739; CTE ∼ .55 PPM/°C (for cali-
bration of dilatometer)
• NBS Single Crystal Sapphire - SRM 732; CTE ∼ 5.5 PPM/°C
(for use with ‘‘low expansion’’ materials)
• OFHC Copper; CTE ∼ 17.3 PPM/°C (for use with ‘‘high
expansion’’ materials)
5.3.5
The
expansion of the dilatometer system, (∆L/L
o
)
s
,
and
the calibration constant, for corrections of lead lag, tem-
peratures, etc., are determined at 20°C intervals using the fol-
lowing equations:
(∆L/L
o
)
s
=(∆L/L
o
)
t
–(∆L/L
o
)
m
A =
(
∆L
L
o
)
t
–
(
∆L
L
o
)
s
(
∆L
L
o
)
m
IPC-24411-1
Figure
1 Cutaway view of vitreous silica tube dilatometer
IPC-TM-650
Number
2.4.41.1
Subject
Coefficient
of Thermal Expansion by the Vitreous Silica (Quartz)
Dilatometer Method
Date
8/97
Revision
A
P
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where:
L
o
=
specimen length
(
∆L
L
o
)
t = certified
expansion of the reference material.
(∆L/L
o
)
m
=
the measured expansion of the reference mate-
rial.
(
∆L
L
o
)
s = the
expansion of the vitreous silica parts of the dila-
tometer.
5.4
Test Procedure
Following
the conditioning steps per
5.2, two thermal cycles shall be conducted per test. The first
is to normalize the specimen and the second to generate data
for the calculation of CTE.
5.4.1
Measure
the initial length of the specimen, using the
micrometer to ± .001 inch.
5.4.2
Place
the specimen in the dilatometer after making
certain that all contacting surfaces are free of foreign material.
Specimens with thickness 0.125 inch shall be supported with
side plates. Care must be taken to assure good seating of the
specimen against the bottom of the tube bottom and the push
rod.
5.4.3
Place
the thermocouple sensor in intimate contact
with the specimen at midlength.
5:4.4 Mount
the transducer to provide a stable contact with
the probe. The sample loading force shall be the minimum
necessary for proper contact between the rod and specimen,
and the bottom of the tube and specimen. Set the transducer
at a nominal initial reading.
5.4.5
Place
the assembled dilatometer into the chamber
and allow the temperature of the specimen to come to equi-
librium.
5.4.6
Record
the initial readings of the thermocouple and
the transducer.
5.4.7
Heat
and cool at a constant rate of 2°C/min.
5.4.8
Record
length changes as a function of temperature.
5.4.9 Remove
the specimen from the fixture and repeat the
procedure per 5.4.1-5.4.8, following the first cycle. Remea-
surement of the specimen length must not be omitted prior to
start of the second cycle.
5.4.10
Test
a total of four specimens, two prepared with the
length in the machine direction of the laminate reinforcement
and two cut in the transverse direction. This quantity is
intended to represent the expansion characteristics of a 18
inch x 24 inch panel size.
6.0
Calculations
6.1
Linear
thermal expansion (LTE), the change in length per
unit length resulting from a temperature change is represented
by:
∆L
L
o
= A
(
∆L
L
o
)
a
+
(
∆L
L
o
)
s
where:
(
∆L
L
o
)
a
is
the expansion as indicated by the transducer, ∆Listhe
observed change in length (∆L=L
2
–L
1
).
LTE is often
expressed in µm/m (parts per million).
6.2
Mean
coefficient of linear thermal expansion – the linear
thermal expansion per change in temperature. Represented
by:
∝ m =
∆L/L
o
∆T
=
(L
2
–L
1
)
L
o
(T
2
–T
1
)
where
L
1
and
L
2
are
the lengths of the specimen at the test
temperatures T
1
and
T
2
.
6.3
Instantaneous
coefficient of linear thermal expansion –
the slope of the linear thermal expansion curve at temperature
T. Represented by:
∝ T =
1
L
o
dL
dT,
6.4
Plots
of the following are commonly used as required:
∆L
L
o
vs.
T; ∝ m vs. T
When reporting the mean coefficient of thermal expansion, the
temperature ranges must be specified.
IPC-TM-650
Number
2.4.41.1
Subject
Coefficient
of Thermal Expansion by the Vitreous Silica (Quartz)
Dilatometer Method
Date
8/97
Revision
A
P
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