IPC-TM-650 EN 2022 试验方法--.pdf - 第717页

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 re…

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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
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Equipment referenced is for the convenience of the user and does not imply endorsement by the IPC.
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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.
1 Scope
This test method is used to determine the ability of
a polymer solder mask protective coating to withstand an
environment conducive to electrochemical migration.
2 Applicable Documents
Multipurpose One-Sided Test Pattern -
Gerber Format
Qualification and Performance of Permanent
Solder Mask
Electrochemical Migration: Electrically Induced
Failures in Printed Wiring Assemblies
Requirements for Soldering Fluxes
3 Test Specimens
The IPC-A-25A-G-KIT artwork package
provides the Gerber files necessary for the fabrication of the
standard IPC-B-25A test board used with this test method.
3.1 Qualification Testing
Three IPC-B-25A boards (see
Figure 1) using the D comb patterns with 0.32 mm [0.0126 in]
lines and spaces for both Classes T and H, coated with sol-
der mask according to the solder mask supplier’s recommen-
dations.
3.2 Conformance Testing
Three IPC-B-25A boards (see
Figure 1) using the C comb pattern (‘‘Y’’ shape pattern) which
should be 0.64 mm lines/0.64 mm spacing [0.025 in lines/
0.025 in spacing] or the pattern with the minimum spacing on
the production board, whichever has the smallest line spac-
ing, coated with solder mask according to the solder mask
supplier’s recommendations.
4 Equipment/Apparatus
4.1 Power Supply
Capable of supplying 10 ± 0.5 VDC at
1 A, maximum.
4.2 Oven
Capable of maintaining up to 90 ± 1 °C [194 ±
1.8 °F].
4.3 Chamber
Capable of maintaining 85 ± 2 °C [185 ± 3.6
°F] with 85%, minimum, relative humidity.
4.4 Desiccator
25 cm [9.84 in] diameter minimum, with
openings for the connecting wires to pass through while main-
taining a hermetic seal.
4.5 Potassium Sulfate
Reagent Grade potassium sulfate.
4.6 RTV
Dow Corning 732 RTV potting compound or
equivalent.
4.7 Resistors
10 megohm resistor for Class H testing and
1 megohm resistors for Class T testing
4.8 Magnifier
Capable of supplying 10X magnification
4.9 Soldering Iron
1. www.ipc.org/onlinestore
IPC-2614-1
3000 Lakeside Drive, Suite 309S
Bannockburn, IL 60015-1249
IPC-TM-650
TEST METHODS MANUAL
Number
2.6.14
Subject
Solder Mask - Resistance to Electrochemical
Migration
Date
03/07
Revision
D
Originating Task Group
Solder Mask Performance Task Group (5-33b)
ASSOCIATION CONNECTING
ELECTRONICS INDUSTRIES
®
IPC-A-25A-G-KIT1
IPC-SM-840
IPC-TR-476
J-STD-004
Figure
1
IPC-B-25A
Test
Board
Material
in
this
Test
Methods
Manual
was
voluntarily
established
by
Technical
Committees
of
IPC.
material
advisory
only
and
its
use
or
adaptation
，
s
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
paten!
infringement.
Equipment
referenced
/s
the
convenience
of
the
user
and
does
not
imply
endorsement
by
IPC.
Page
1
of
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