IPC-TM-650 EN 2022 试验方法--.pdf - 第716页

IPC -TR- 476 MIL-P-551 10 Figure 1 The Institute for Int erconnecting and Packaging E lectronic Circuits 2215 S anders Road • Northbrook, IL 60062-6135 Material in this T est M ethods Manual was vol untaril y establis he…

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IPC-TM-650
Page 2 of 2
Number
2.6.11.1
Revision
Subject
Hydrolytic
Stability
-
Conformal
Coating
Date
07/00
5.2
Evaluation
5.2.1
During
testing,
examine
the
test
specimens
at
28th,
56th
and
84th
days.
Prior
to
examining
the
test
specimens,
they
shall
be
returned
to
25℃
[77°F]
and
50%
relative
humid¬
ity
for
two
hours.
Evaluate
the
specimens
for
evidence
of
reversion
as
indicated
by
softening,
chalking,
blistering,
crack¬
ing,
tackiness,
loss
of
adhesion
or
liquefaction.
Evaluate
also
legibility
of
the
markings
on
the
board
and/or
the
resistors.
5.2.2
After
the
1
20-day
aging
period,
the
panels
shall
be
returned
to
25℃
[77°F]
and
50%
relative
humidity
and
held
for
seven
days.
The
specimens
shall
be
evaluated
and
compared
with
the
control
specimen
as
per
5.2.1.
The
specimens
shall
also
be
tested
for
tackiness
in
accordance
with
Method
4061
(Dry-Through
For
Varnish,
Lacquers
And
Enamels)
of
FED-
STD-141.
5.3
Chamber
Method
5.3.1
Place
four
of
the
five
test
specimens
into
the
test
chamber,
by
placing
them
in
a
rack
or
hanging,
so
that
they
do
not
touch
each
other.
The
fifth
specimen
is
held
as
a
con¬
trol.
Close
the
chamber
door.
5.3.2
Set
the
chamber's
parameters
at
85°
±
2
℃
[185°
±
3.6°F]
and
95
±
4%
relative
humidity.
Activate
the
test
cham¬
ber
and
begin
testing.
5.3.3
Allow
the
specimens
to
remain
in
the
test
chamber
for
1
20
days.
5.4
Evaluation
5.4.1
During
testing,
examine
the
test
specimens
at
28th,
56th
and
84th
days.
Prior
to
examining
the
test
specimens,
they
shall
be
returned
to
25℃
[77°F]
and
50%
relative
humid¬
ity
for
two
hours.
Evaluate
the
specimens
for
evidence
of
reversion
as
indicated
by
softening,
chalking,
blistering,
crack¬
ing,
tackiness,
loss
of
adhesion
or
liquefaction.
Evaluate
also
legibility
of
the
markings
on
the
board
and/or
the
resistors.
5.4.2
After
the
1
20-day
aging
period,
the
panels
shall
be
returned
to
25℃
[77°F]
and
50%
relative
humidity
and
held
for
seven
days.
The
specimens
shall
be
evaluated
and
compared
with
the
control
specimen
as
per
5.2.1
.
The
specimens
shall
also
be
tested
for
tackiness
in
accordance
with
Method
4061
(Dry-Through
For
Varnish,
Lacquers
And
Enamels)
of
FED-
STD-141.
IPC-TR-476
MIL-P-55110
Figure 1
The Institute for Interconnecting and Packaging Electronic Circuits
2215 Sanders Road • Northbrook, IL 60062-6135
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.
Page 1 of 2
回
IPC-TM-650
TEST
METHODS
MANUAL
Number
2.6.13
Subject
Assessment
of
Susceptibility
to
Metallic
Dendritic
Growth:
Uncoated
Printed
Wiring
Date
Revision
10/85
Originating
Task
Group
N/A
1
.0
Scope
This
test
method
will
demonstrate
a
relative
degree
to
which
uncoated
printed
wiring
boards
are
suscep¬
tible
to
dendritic
growth
due
to
the
presence
of
ionic
residues
and
condensed
moisture.
This
test
method
is
particularly
suit¬
able
for
printed
wiring
board
manufacturing
process
control.
2
.0
Applicable
Documents
How
to
Avoid
Metallic
Growth
Problems
on
Electronic
Hardware
Printed
Wiring
Boards
3
.0
Test
Specimens
Test
pattern
is
chosen
from,
but
not
restricted
to
e.g.,
MIL-P-551
10
type
"Y”
pattern
with
a
pair
of
conductors
having
typically
15-30
mils
separation
(See
Figure
1).
A
pair
of
parallel
conductors
on
an
uncoated
production
printed
wiring
board,
with
spacing
between
conductors
of
approximately
15-30
mils
is
suitable
as
well.
4
.0
Equipment/Apparatus
4.1
Power
Supply
A
de
power
supply
capable
of
providing
a
metered
0-20
V
de,
and
100
milliamps
current.
4.2
Microscope
50-100
power
microscope
and
means
of
providing
direct
and/or
indirect
lighting
on
specimen.
4.3
Miscellaneous
Items
DI
water
sample
(2
o
乙)
kept
in
a
plastic
bottle,
eye
dropper,
a
1/2
watt-
1
0K
ohm
current
limit¬
ing
resistor
and
a
stop
watch.
5
.0
Procedure
5.1
Preparation
5.1.1
Attach
a
wire
to
each
of
the
conductors
on
the
"Y”
pattern
test
board,
or
to
corresponding,
parallel
conductors
on
a
production
PWB.
5.1.2
Connect
a
10K
resistor
in
series
to
the
power
supply
as
shown
in
Figure
1.
The
resistor
will
limit
the
current
to
1
.5
milliamp
maximum.
5.1.3
Place
the
board
for
viewing
on
the
microscope,
so
that
the
parallel
conductors
are
in
view.
Provide
lighting
that
will
illuminate
the
test
board
on
top
and/or
underneath.
5.1.4
Using
the
eye
dropper,
place
a
drop
of
DI
water
across
the
conductors
that
are
in
view
under
the
microscope,
at
least
0.5
inch
away
from
the
place
where
external
wires
are
attached
to
parallel
conductors.
Adjust
power
supply
to
15
V
and
turn
the
power
supply
on.
Simultaneously
start
the
stop¬
watch.
5.1.5
Carefully
observe
the
action
using
the
microscope.
Adjust
the
power
of
the
microscope
so
the
entire
water
area
is
in
view.
5.1.6
Bubbles
may
appear
within
about
5
seconds.
This
is
hydrogen
evolution-electrolysis
of
water.
5.1.7
Depending
on
PWB
ionic
cleanliness
level
and
the
characteristics
of
the
PWB
surface,
there
may
be
a
dendritic
(tree-like)
growth
from
the
negative
to
positive
conductor,
appearing
within
a
typical
(for
a
given
board)
but
generally
very
broad
time
span
of
a
few
seconds
to
several
minutes.
5.1.8
The
condition
of
dendritic
growth
is
much
easier
to
observe
with
an
artificial
light
source
placed
under
the
test
board.
A
clear
demonstration
of
the
dendritic
growth
can
be
performed
if
tap
water
containing
ionic
contamination
is
used
in
place
of
DI
water
(see
paragraph
5.1
.4).
5.1.9
Once
the
dendritic
growth
has
reached
the
positively
charged
conductor,
most
action
will
cease;
turn
off
the
stop¬
watch.
The
elapsed
time
is
a
relative
measure
of
susceptibility
of
the
PWB
in
question
to
undergo
dendritic
growth
under
high
humidity
(condensed
moisture)
environment.
At
least
ten
IPC-TM-650
Number
Subject Date
Revision
Page 2 of 2
2.6.13
Assessment
of
Susceptibility
to
Metallic
Dendritic
Growth:
Uncoated
Printed
Wiring
10/85
separate
measurements
are
needed
to
obtain
a
statistically
meaningful
result.
6
.0
PWB
Process
Test/Sampling
For
testing
of
lot
con¬
formity
at
least
ten
different
PWBs
with
parallel
conductors
as
per
Section
3
shall
be
tested.
7
.0
Test
Interpretation
Test
for
susceptibility
to
metallic
dendritic
growth
is
a
relative
measure
of
localized
ionic
residue
levels.
As
such,
it
does
not
have
direct
relationship
with
abso¬
lute
PWB
reliability
measure.
The
results
of
this
test
are
found
useful
in
the
PWB
process
control
by
testing
board-to-board
and
lot-to-lot
variations.