IPC-TM-650 EN 2022 试验方法.pdf - 第123页
pan. If the balance door is closed immediately after sample entry and exit, 50 ± 5% RH can be maintained. Verification of conditions in the enclosure during a simulated test can be made using a rapid response humidity pr…
5.5.7
After
60 +5, –0 seconds from the time of removal from
the solution, note the weight of the specimen and record it as
W
2
.
5.5.8
Repeat
5.5.5 – 5.5.7 for the remaining specimens
insuring the immersion time of each specimen is kept within
the tolerance.
5.5.9 A
fresh batch of solvent shall be used for no more
than 18 specimens or for a period of time no longer than 8
hours.
5.6
Evaluation
5.6.1 Weight Gain
5.6.1.1
Subtract
the dry weight of each specimen, W
1
,
from
the final weight, W
2
of
each specimen after immersion.
Record the weight gain in mg.
5.6.1.2 Calculate
the average weight gain in mg.
5.6.2
Appearance
Examine
the specimens using 20/20
vision for any changes to the appearance of the material, such
as hazing, whitening or swelling.
5.7
Report
5.7.1
Report
the average weight gain in milligrams for the
material tested.
5.7.2 Report
the measured specimen thickness.
5.7.3
Report
actual test conditions for temperature and
humidity and the solvent temperature.
5.7.4
Report
any anomalies in the test or any variations from
the specified procedures or tolerances.
5.7.5
Report
any changes in the visual quality of the speci-
mens as determined in 5.6.2.
6.0 Notes
6.1 Safety Considerations
See
the MSDS sheet for the
solvent used before running this test.
6.1.1 During
test, the beaker with the test solvent should be
covered or under a ventilation hood.
6.1.2
Dispose
of the spent solvent in accordance with local
regulations.
6.2
Factors Affecting Tests
6.2.1 Sample
6.2.1.1 Same Sample
The
results obtained on the same
sheet of material may be significantly affected by the degree
of cure of the material and the thermal history of the sample.
6.2.1.2
Variation Due to Thickness of Sample
There
is a
very small difference due to sample thickness. This is under
10% on typical epoxy materials for 0.2 mm [0.008 in] to 1.5
mm [0.060 in] and under 5% on more chemical resistant
material from 0.13 mm [0.005 in] to 1.5 mm [0.060 in].
6.2.2
Accuracy
Since
there are no standards for this type
of test, the accuracy of the method cannot be established.
6.2.3
Precision
the
reproducibility of this test depends on
the degree of control over the controlled variables and some
other variables such as atmospheric pressure, which are gen-
erally not controlled in industrial laboratories. Precision
between laboratories with 20% to 50% RH was 10% at the 90
mg level and 16% at the 25 mg level.
6.2.4
Desiccants
Desiccants
capable of 0.002 mg mois-
ture levels include P
205
,
Mg (C10
4
)
2
,
anhydrous BaO and
fused KOH.
Some other desiccants such as CaCl
2
result
in considerably
higher moisture levels and may not be used in this test. (See
Weast R.C., CRC Handbook of Chemistry and Physics, 65th
edition, E–37, 1984.)
6.2.5
Humidity Considerations
6.2.5.1 Effect of Humidity
Higher
humidity will produce
higher solvent pickup due to retarded solvent evaporation.
6.2.5.2
Control of Humidity
Control
of the critical environ-
ment can be obtained in uncontrolled laboratories using an
enclosed balance with a saturated salt solution of Mg(No
3
)
2
,
6H
2
0
(for 50% RH).
All significant openings in the enclosure are sealed with tape
and an inner door is fabricated with a small opening for
sample entry and exit. A shallow pan is fabricated to occupy
most of the balance floor without contacting the weighing
IPC-TM-650
Number
2.3.4.2
Subject
Chemical
Resistance of Laminates, Prepreg, and Coated Foil
Products, by Solvent Exposure
Date
12/94
Revision
A
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pan.
If the balance door is closed immediately after sample
entry and exit, 50 ± 5% RH can be maintained.
Verification of conditions in the enclosure during a simulated
test can be made using a rapid response humidity probe;
however, this should be done with unconditioned specimens
since solvents will affect the response of many humidity
probes.
6.2.6
Temperature Considerations
The
effect of the sol-
vent temperature on results is severe. A variation of 5°C[9°F]
can result in an error as high as 50% relative to values deter-
mined at 23°C [73°F].
6.3
Consideration of Other Test Parameters
6.3.1 Using Same Solvent
Shorter
dwell times, e.g., 3
minutes, generally result in better discrimination between
material of varying chemical resistance. However, test variabil-
ity is generally increased. Shorter tests are excellent for side
by side comparisons of materials.
Longer tests, e.g., 30 minutes, often do not differentiate
adequately between materials, and while useful on homoge-
neous material, variability on material with surface coatings
may be excessive.
6.3.2
Other Solvent Blends
Other
solvents and various
methylene chloride based combinations have been commonly
used in the industry. However, results and precision of the test
may vary significantly and the added problem of variability in
solution make-up is introduced.
6.4
Supercession
This
test method supersedes 2.3.4.2,
dated 5/86, and 2.3.4.3, dated 5/86.
6.5
Desiccator Conditions
The
Test Methods Task Group
determined that a great majority of test laboratories are unable
to consistently hold the Relative Humidity in a desiccator to
less than 20%. Based on data from participating company lab
management, the lowest practically feasible RH for use with
the affected IPC Test Methods is 30% maximum.
IPC-TM-650
Number
2.3.4.2
Subject
Chemical
Resistance of Laminates, Prepreg, and Coated Foil
Products, by Solvent Exposure
Date
12/94
Revision
A
P
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1.0
Scope
This
test method is designed for use in deter-
mining the resistance of core (dielectric) materials used in
printed wiring boards to methylene chloride at laboratory
ambient temperature.
2.0
Applicable documents
IPC-TM-650
Method
2.3.6, Etching, Ammonium Persulfate
Method
IPC-TM-650
Method
2.3.7, Etching, Ferric Chloride Method
IPC-TM-650
Method
2.3.7,1, Etching, Cupric Chloride
Method
3.0
Test specimens
3.1 Dimensions
The
test specimens shall be 2.00 in. x
2.00 in. X thickness of material. Tolerance on the 2.00 in.
dimensions shall be ± .03 in.
3.2
Edge finish
The
edges of the specimens shall be
milled or sanded smooth with 400 grit sandpaper.
3.3
Number of specimens
Three
specimens shall be used
for this test.
3.4
Removal of metal cladding
The
metal cladding shall
be removed by etching per IPC-TM-2.3.6, 2.3.7, 2.3.7.1 or
other suitable method which does not affect the surface of the
pressed sample.
4.0
Apparatus
4.1 Oven
Circulating
air oven capable of maintaining a uni-
form temperature of 105° to 110°C (221° to 230°F).
4.2
Desiccator
4.3 Analytical balance
5.0 Procedure
5.1 Conditioning
The
specimens shall be conditioned by
drying in an oven for 1 hour at 105° to 110°C (221° to 230°F),
then cooled to room temperature in a desiccator.
5.2
Fill
a 3000 ml beaker with methylene chloride to a depth
of 3 in. and maintain at 23°±2°C in a well-ventilated fume
hood. Place a rack in the bottom of the beaker to hold the
samples upright and apart.
5.3
Exposure
Remove
each specimen from the desiccator
and immediately weigh to the nearest 0.1 milligram, recording
the initial weight as ‘‘A’’. Immerse each specimen in the meth-
ylene chloride for 30 ± 0.5 minutes. Remove from the beaker,
air dry for 10 minutes ± 30 seconds, weigh immediately and
record the final weight as ‘‘B.’’ Drying time includes weighing
time.
5.4
Evaluation
5.4.1 Calculation
Calculate
and record the percent
change in weight for each specimen to the nearest 0.01 per-
cent as follows:
Change in weight, percent =
|
B − A
|
A
x
100
The
Institute for Interconnecting and Packaging Electronic Circuits
2215 Sanders Road • Northbrook, IL 60062-6135
IPC-TM-650
TEST
METHODS MANUAL
Number
2.3.4.3
Subject
Chemical
Resistance of Core Materials to
Methylene Chloride
Date
5/86
Revision
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.
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