IPC-TM-650 EN 2022 试验方法.pdf - 第122页
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 …
and
of a thickness when cured not greater than 0.13 mm
[0.005 in] total, using the prepreg manufacturer’s recom-
mended press cycle. Laminate over 0.5 mm [0.020 in] shall be
treated like double clad laminate without lamination.
5.1.2
Resin-coated Foil
Resin-coated
foil samples shall
be laminated together using at least two plies of prepreg
between the coated sides of the foil. The prepreg shall be of
the same basic resin type and of a thickness when cured not
greater than 0.127 mm [0.005 in] total, using a press cycle
and any subsequent post cure which meets the manufactur-
er’s recommendations for both the coated foil and prepreg.
(See 6.2.1.1)
For qualification and referee tests, a 0.50 ± 0.10 mm [0.02 in]
composite core is to be built.
5.1.3
Laminate with Coated Foil Surfaces
Single-sided
laminate
shall be tested after lamination as in 5.1.1. Double-
sided laminate with coated foil on one side shall have the foil
etched from the uncoated side and shall subsequently be
laminated as 5.1.1. Double-sided laminate with coated foil on
both sides shall be tested as is.
5.1.4 Prepreg
Prepreg
shall be laminated to a thickness of
0.50 ± 0.10 mm [0.020 in] using treated copper foil on both
sides and following the prepreg manufacturer’s recommended
press and post cure cycle. (See 6.2.1.1) For prepreg less than
0.13 mm [0.005 in] thick when cured, at least two plies shall
be bonded to either side of an etched laminate of a thickness
such that the pressed sample satisfies the required thickness.
5.1.5
Double-sided Laminate
Double-sided
laminate shall
be submitted for testing as is.
5.2
Specimen Preparation
5.2.1 Etching
Samples,
as specified in 3.0, shall be etched
in accordance with standard industry practices. For referee
purposes, 2.3.6, 2.3.7, 2.3.7.1, or 2.3.7.2 shall be used.
5.2.2
Cut
the specimens to size per 3.2. Cutting shall be
performed using apparatus and in such a manner that pre-
vents edge damage. Edge smoothing is recommended to
prevent excessive absorption.
5.2.3
Markings
Each
specimen shall be identified by mark-
ing with a lead pencil or equivalent technique which is not
removed by the solvent and which doesn’t affect the results.
5.3
Preconditioning
5.3.1
Measure
and record nominal thickness of the test
specimen using IPC-TM-650, Method 2.2.18.
5.3.2
Place
the etched specimens vertically in the metal
rack and dry the specimens in the oven for 60 ± 5 minutes at
105°C [221°F]. Air flow around each specimen must be
assured.
5.3.3
Remove
the specimens from the oven and immedi-
ately place in the desiccator to cool for 60 ± 30 minutes.
5.4
Test Condition
The
test shall be performed at stan-
dard laboratory conditions: 23 ± 2°C [73 ± 0.9°F] and 50 ± 5%
R.H.
5.5
Measurement
5.5.1
Fill
the battery jar with 750 ml of solvent and maintain
the solvent temperature at 23 ± 0.5°C [73 ± 0.9°] using the
water bath.
5.5.2
Remove
the specimens individually from the desicca-
tor and weigh to the nearest milligram on the analytical bal-
ance. Samples must be weighed within 60 seconds of
removal from the desiccator. Record these weights as W
1
.
5.5.3 Place the rack into the beaker of solvent, start the 60
minute timer and using tongs place the specimens in the rack
at suitable intervals (recommend approximately 2 minutes).
Insure that the specimens are completely immersed.
5.5.4
Place
the metal clip on the balance and tare it out.
5.5.5 After
10 minutes +15, –0 seconds, using the tongs
remove the first specimen from the solvent and start the 60
second timer.
5.5.6
Slowly
wag the specimen in the air. As soon as the
specimen is free of surface wetness, but no longer than 30
seconds, place the specimen on the balance supporting it on
the metal clip such that both surfaces of the specimen are
exposed (placing the specimen flat on the balance pan is not
permitted since evaporation from the side next to the pan will
be reduced.)
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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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
P
age3of4
电子技术应用 ｗｗｗ．ＣｈｉｎａＡＥＴ．ｃｏｍ
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
age4of4
电子技术应用 ｗｗｗ．ＣｈｉｎａＡＥＴ．ｃｏｍ