IPC-TM-650 EN 2022 试验方法-- - 第718页

1 Scope This test method is used to determine the ability of a polymer solder mask protective coati ng t o withstan d an environment conducive to electrochemical migration. 2 Applicable Documents Multipurpos e One-Sided …

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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
4
4.10 Flux
Water white rosin (R or RMA) with halide content
less than 0.5%, i.e., type Symbol A and B or ROL0 and ROL1
according to J-STD-004.
5 Test Conditions
5.1.1 Class T
85 ± 2 °C [185 ± 3.6 °F] with 85% relative
humidity minimum, 10 VDC bias, for 500 hours.
5.1.2 Class H
85 ± 2 °C [185 ± 3.6 °F] with 90, +5/-0%
relative humidity, 10 VDC bias for 168 hours.
5.2 Specimen Preparation
5.2.1
Positive, permanent and noncontaminating identifica-
tion of the test specimens is of paramount importance.
5.2.2
Visually inspect the test specimens for any obvious
defects, as described in IPC-A-600. If there is any doubt
about the overall quality of any test specimen, the test speci-
men should be discarded.
5.3 Electrical Connections (Both Classes)
5.3.1
For qualification testing, solder single strand PTFE
insulated wires or equivalent to the lands of each of the D test
patterns using a noncontact shield to protect the patterns
from flux splattering. These wires will be used to connect the
test specimen to the bias voltage or resistance meter. Test
points 1, 3 and 5 are to be connected to the positive terminal
and test points 2 and 4 are to the negative terminal of resis-
tance meter or power supply. When resistors are used, they
are to be connected between test points 1, 3 and 5 and the
positive terminal of power supply.
5.3.2
For conformance testing, solder single strand PTFE
insulated wires or equivalent in each of the connecting points
of the pattern described in 3.2 using a noncontact shield to
protect the patterns from flux splattering. These wires will be
used to connect the test specimen to the bias voltage or
resistance meter. One side of the pattern should be con-
nected to the positive terminal and the other side to the nega-
tive terminal of resistance meter or power supply. When resis-
tors are used, they are to be connected between the pattern
and the positive terminal of power supply.
5.3.3
The flux shall not be removed from the test speci-
mens.
5.4 Procedures
5.4.1 Desiccator Test Method
5.4.2
Take insulation resistance measurements of the test
specimens using 10 VDC, prior to testing. This step will
ensure that the resistance measurements are sufficient to pro-
ceed with testing.
5.4.3
Prepare a saturated solution of distilled water and
potassium sulfate (approximately 35g per 100 mL) at a tem-
perature of 85 °C [185 °F]. Pour the solution into the desicca-
tor just below the ceramic plate. Crystals of potassium sulfate
should remain visible in the saturated solution in the oven at
operating temperature.
5.4.4
Place the test specimens into the desiccator, such
that they do not touch one another. Route the connecting
wires to the outside of the desiccator and seal with a silicone
potting compound such as Dow Corning 732 RTV or a heat
resistant vacuum grease.
5.4.5
Place the desiccator into an oven maintained at 85 °C
[185 °F]. For the remaining test procedures, see 5.5.4 to 5.6.2
for Class H and 5.7.4 to 5.8.4 for Class T.
5.5 Class H – Test Chamber Method
5.5.1
Prior to testing, take insulation resistance measure-
ments of the test specimens using 10 VDC. This step will
ensure that the resistance measurements are sufficient to pro-
ceed with testing.
5.5.2
Place the specimens into the test chamber and route
the wires through the porthole of the test chamber and seal, if
necessary.
5.5.3
Set the chamber’s parameters, which is a noncon-
densing ramp, for 85 °C [185 °F] with 90% relative humidity.
Close the chamber doors and activate the test chamber.
5.5.4
Connect the correct test points as specified in 5.3.1
and 5.3.2 to a 10-megohm resistor before the positive termi-
nal of power supply. (See Figure 2 for configuration for quali-
fication testing.) Apply the bias voltage of 10 VDC.
5.5.5
Allow the test specimens to remain in the test cham-
ber for the duration of 168 hours (seven days).
Number
2.6.14
Subject
Solder Mask - Resistance to Electrochemical Migration
Date
03/07
Revision
D
IPC-TM-650
Page
2
of
4