IPC-TM-650 EN 2022 试验方法--.pdf - 第683页

of one, even though there are four distinct comb patterns and measurements. 7.1.2 Sample Siz es The number of samples should not be stipulated in the test method. The number should be in the specifications referring to t…

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5.1.1
Hardwired samples need to be soldered without
adverse effect to test vehicles. Common good soldering
practice should be followed. Sample should be covered. See
IPC-9201 for reference. Heat should not be allowed to dam-
age sample. Flux is of great concern. Often samples can be
soldered without the use of flux, so users of this method
should have solid wire solder on hand. If flux is deemed nec-
essary by qualitative observation, use rosin nonactivated flux.
Wire all samples and retain relationship of interconnection
between test vehicle and testing system (nets, channels, etc.).
5.1.2
Connector interfacing inside the chamber has been
shown to be a capable implementation for SIR; however, as
the connectors are exposed to high heat and humidity they
obviously require a good deal of maintenance and verification.
5.2
Fixture samples in the chamber uniformly, vertically, and
parallel to airflow. The minimum spacing between samples
shall be 12.5 mm [0.5 in]. If hardwiring is used, dress wires
down from samples. Make appropriate connections to switch-
ing system.
5.3
Measurement and stress bias voltage are the same.
5.3.1
Apply direct current electrical bias to produce a field
strength of 25 ± 1 V/mm between adjacent parallel traces.
Assuming that SIR is much greater than current limiting resis-
tance this field corresponds to an applied voltage of 5 ± 0.2 V
for 200 µm [0.0079 in] spacing (example is technically equiva-
lent to IEC 61189-5). This bias shall be in place during an
aggregate 90% (minimum) of temperature/humidity condition-
ing (remaining percentage is related to measurement) in order
to facilitate electrochemical reactions.
5.3.2
Seal the chamber and ramp from laboratory ambient
conditions to 25 °C and 50% R.H. Dwell for one hour. Verify
the electrical system setup by taking a series of all measure-
ments at these specified ambient conditions. Because classi-
fication or ranking of sample performance by SIR at ambient
is not appropriate for these test vehicles, clarity suggests that
measurements need not be reported unless ‘‘shorts’’ are
observed and therefore the corresponding samples are
deemed inappropriate for test.
5.4
Increase the temperature to 40 °C while maintaining the
humidity at 50% R.H. ± 3% R.H. and dwell at this tempera-
ture for 15 minutes. After this period, gradually increase, within
0.5 hour, the relative humidity to 90 ± 3 % R.H. Do not allow
the temperature of the samples to drop below the dew point.
5.5
Allow chamber to stabilize at set point for one hour.
5.6
Duration of test shall be not less than 72 hours.
5.7
Take and record all SIR measurements (every unique net
or channel) at least once every 20 minutes.
5.8
After conditioning, remove samples from chamber and
examine at 30 to 40X in light field and dark field (back light).
Record the following:
a) Presence of dendrites: Yes/No
b) Maximum percent reduction of spacing: 0% for no den-
drites 1% to 100% for worst-case dendrite. Capture and
record image of worst case dendrite.
c) Presence of discoloration between conductors: Yes/No; if
yes, capture and record image.
d) Presence of water spots. Yes/No; if yes, capture and
record image.
e) Presence of subsurface metal migration. Yes/No; if yes,
capture and record image.
6 Reporting
6.1
Deviations from test method or specification shall be
recorded. All standard reporting shall be incorporated, includ-
ing enough information to exactly reproduce the test (equip-
ment, personnel, deviations or options within the method
etc.).
6.2
All items listed in 5.8.
6.3
All SIR measurements are to be reported in the form of
Log
10
(R
i
), where R
i
is the measured SIR of the i
th
measure-
ment.
7 Notes
7.1 Sampling
When using this test method for materials
characterization the sample selection, preparation and
requirements should follow IPC-J-STD-004.
When using this test method for process characterization the
sample selection, preparation and requirements should follow
IPC-J-STD-001.
This methodology may also be used with other specifications.
7.1.1
A test vehicle should be considered a sample count of
one. For example, an IPC-B-24 test vehicle is a sample count
Number
2.6.3.7
Subject
Surface Insulation Resistance
Date
03/07
Revision
IPC-TM-650
Page
3
of
4
of one, even though there are four distinct comb patterns and
measurements.
7.1.2 Sample Sizes
The number of samples should not be
stipulated in the test method. The number should be in the
specifications referring to this test method. However, it is rec-
ognized that there will be users who are attempting process
or material characterization and may be uncertain about how
many samples to specify.
With respect to the second bulleted item in the scope, (Pro-
vide metric(s) that can appropriately be used for binary classi-
fication (e.g., go/no go, pass/fail), a minimum sample size of
10 is suggested.
With respect to the third bulleted item in the scope, (Compare,
rank or characterize materials and processes) a minimum
sample size of three is suggested.
7.1.3
When characterizing material, samples can be pro-
cessed on the same panel.
7.1.4
When characterizing process(es), samples should at a
minimum be processed on different panels, preferably in dif-
ferent production runs.
7.2
The derived unit of surface resistivity and its expression
as ohm/square cannot be defined for this method or similar
methodologies due to the nonlinear response of the test
vehicles and the assumed nonhomogeneous concentration of
ionic contaminates.
7.3
Careful considerations must be used when developing
an implementation of this method. Seemingly adequate set-
ups can (and historically have) caused unacceptable uncer-
tainty of results. If the user of this method is not intimately
familiar with the technologies involved, ASTM D 257 and IPC-
9201 are highly recommended.
Number
2.6.3.7
Subject
Surface Insulation Resistance
Date
03/07
Revision
IPC-TM-650
Page
4
of
4
NASA General Specification No. SP-R-0022
ASTM E 595
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.
Page 1 of 2
r
ASSOCIATION
CONNECTING
/
ELECTRONICS
INDUSTRIES
®
221
5
Sanders
Road
Northbrook,
IL
60062-6135
IPC-TM-650
TEST
METHODS
MANUAL
Number
2.6.4
Subject
Outgassing,
Printed
Boards
Date
Revision
05/04
B
Originating
Task
Group
Rigid
Printed
Board
Performance
Task
Group
(D-33a)
1
Scope
This
test
method
is
used
to
determine
the
total
mass
loss
(TML)
and
collected
volatile
condensable
material
(CVCM)
of
materials
when
exposed
to
a
heated
vacuum
envi¬
ronment.
Mass
loss
may
be
due
to
outgassing
of
low
molecu¬
lar
weight
materials
present
in
printed
boards
such
as
trapped
plating
solutions,
improper
lamination,
and
uncured
adhesives
which
are
known
to
cause
contamination
or
corrosion
of
spacecraft
equipment.
2
Applicable
Documents
Vacuum
Sta¬
bility
Requirements
of
Polymeric
Material
for
Spacecraft
Appli¬
cation.
Standard
Test
Method
for
Total
Mass
Loss
and
Collected
Volatile
Condensable
Materials
from
Outgassing
in
a
Vacuum
Environment.
3
Test
Specimens
The
test
specimen
shall
be
cut
into
small
pieces
that
can
fit
into
the
specimen
boats
and
whose
total
mass
shall
be
about
200
mg.
If
smaller
masses
are
used
the
accuracy
of
the
TML
and
CVCM
determinations
may
be
impaired.
It
is
imperative
that
the
specimens
not
be
contami¬
nated
during
the
preparation
process.
Specimens
are
not
to
be
handled
with
bare
hands
since
human
skin
oils
are
volatile
and
condensable
by
this
method
thereby
creating
misleading
TML
and
CVCM
results.
If
there
is
any
doubt
about
specimen
contamination
the
specimens
should
be
cleaned
using
sol¬
vents
known
to
be
non
reactive
and
that
leave
no
residue.
An
average
of
at
least
three
(3)
samples
shall
be
made
for
each
test.
4
Apparatus
or
Material
4.1
Multiple
specimen
vacuum
chamber
capable
of
main¬
taining
a
vacuum
of
at
least
7
X
10-3
Pa
(5
X
10-5
Torr)
with
resistance
heated
copper
bars
capable
of
maintaining
1
25
土
1
[257
±
1.8
°F]
during
the
24
hour
test
run
and
typi¬
cally
containing
24
specimen
chambers.
Typically,
three
(3)
of
the
specimen
chambers
are
maintained
as
controls.
The
open
end
of
each
specimen
chamber
allows
vapors
from
the
speci¬
men
to
pass
through
a
hole
into
a
collector
chamber
where
the
vapors
are
condensed
on
a
collector
plate
that
is
main¬
tained
at
25
±
1
[77
°F
±
2
°F)
throughout
the
test.
See
ASTM
E
595
for
further
details
and
requirements
for
the
con¬
struction
and
cleaning
of
the
test
apparatus.
4.2
An
analytical
balance
capable
of
measuring
the
speci¬
mens,
boats,
and
collector
plate
mass
to
the
nearest
micro¬
gram
(0.000001
gram).
4.3
Glass
desiccator
using
active
silica
gel
desiccant.
Low
vapor
pressure
grease
shall
be
used
for
the
ground
glass
joints.
4.4
Conditioning
chamber
capable
of
maintaining
50%
±
5%
relative
humidity
and
23
±
2
[73
°F
±
4
°F).
4.5
Prepared
aluminum
foil
specimen
boats.
4.6
Suitable
cleaning
solvents
Mixtures
of
1:1:1
by
vol¬
ume
chloroform
:acetone:
ethanol
and
1
:1
by
volume
acetone:
ethanol
solvent
blends
have
been
successfully
used
for
cleaning
and
degreasing
the
apparatus,
aluminum
boats,
and
collector
plates.
All
solvents
shall
be
spectrophotometer
grade
purity
or
equivalent.
See
Annex
A1
of
ASTM
E
595
for
details
regarding
cleaning
and
storage
procedures
for
the
equipment
used
in
this
test.
4.7
Nitrogen
gas,
99.9%
pure,
or
better,
with
a
dew
point
of
-60
[-76
°F]
or
less.
The
nitrogen
gas
shall
be
filtered
using
a
Molecular
Sieve
5A
or
equivalent.
4.8
Wiping
materials
and
swabs
for
cleaning.
These
material
shall
be
preextracted
using
solvents
with
which
they
will
be
used.
4.9
Suitable
gloves
or
finger
cots
to
be
used
during
sample
preparation.
5
Procedure
5.1
Weigh
a
prepared
aluminum
foil
boat
to
the
nearest
microgram
and
return
it
to
the
glass
storage
desiccator.
5.2
Weigh
a
prepared
collector
plate
to
the
nearest
micro¬
gram
and
mount
it
into
its
cooling
plate
receptacle.
5.3
Add
the
test
specimen
to
the
boat
and
condition
the
specimen
at
50%
±
5%
relative
humidity
at
23
±
2
[73
°F
±
4
°F]
for
a
minimum
of
24
hours.
Weigh
the
condi¬
tioned
specimen
and
boat
to
the
nearest
microgram.