IPC-TM-650 EN 2022 试验方法.pdf - 第676页
NOTE: 3.98E+11 = 3.98 x 10 11 NOTE: In many spreadsheet software packages (.e.g, Excel®), a Geometric Mean function will yield the same results as IR AVE . No. Pattern Resistance (Ohms) LogOhms 1 1-2 3.98E+11 11.60 2 3-2…
After
96 hours total, repeat the measurement series. Regard-
less of the outcome of the measurements, the test terminates
after this measurement series.
5.6
Data Analysis
The
average insulation resistance (IR
avg
)
is
calculated as follows:
IR
avg
= 10
[
1
N
Σ
1
N
log
10
(IR)
i
]
Where:
N
= Number of Test Points (32 nominal for each set of eight
patterns)
IR
i
=
individual insulation resistance measurements
See 6.4 for an example
No individual insulation resistance value may be more than a
factor of 10 below the specified minimum value.
Where an assignable cause of low insulation resistance, which
is properly attributable to the laminate itself, or to the process
used to produce the PWB, can be found, then such a value
can be excluded from calculating the average value, provided
that at least 30 test points are included in the average. Such
assignable causes include the following:
• Contamination on the insulating surface of the board, such
as lint, solder splines or water droplets from the chamber.
• Incompletely etched patterns that decrease the insulating
space between the conductors by more than the amount
allowed in the appropriate design requirements drawing.
• Scratched, cracked, or obviously damaged insulation
between conductors.
6
Notes
6.1
If
condensation occurs on the test specimens in the
environmental chamber while the samples are under voltage,
dendritic growth will occur. This can be caused by a lack of
sufficient control of the humidification of the oven. Water spot-
ting may also be observed in some ovens where the airflow in
the chamber is from back to front. In this case, water conden-
sation on the cooler oven window can be blown around the
oven as microdroplets which deposit on test specimens and
cause dendritic growth if the spots bridge the distance
between two electrified conductors. Both of these conditions
must be eliminated for proper testing.
6.2
Tight
control of the test humidity is critical for this test
method. A difference of 5% relative humidity can result in a
0.5 - 1.0 decade difference in the measured resistance. The
uniformity of the environment is also important. A fully loaded
chamber, where airflow is severely impeded, may have a
30-40% RH range within the chamber workspace.
6.3
The
polarity of the applied voltage is not important as
long as the application is consistent (e.g., Pads 1, 3, 5 are
positive and 2, 4 are at opposite potential, vs. Pads 2 and 4
positive, and Pads 1, 3, 5 at opposite potential).
6.4
Example of Numerical Calculations
Eight
5-point test patterns (4 measurements each)
LogOhms = base-10 logarithm of measured resistance
Average of LogOhms = 11.62
IR
AVE
=
Antilog (11.62) = 4.19E+11 ohms
IR
AVE
=
Geometric Mean
IPC-TM-650
Number
2.6.3.5
Subject
Bare
Board Cleanliness by Surface Insulation Resistance
Date
01/04
Revision
P
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NOTE: 3.98E+11
= 3.98 x 10
11
NOTE: In
many spreadsheet software packages (.e.g,
Excel®), a Geometric Mean function will yield the same results
as IR
AVE
.
No.
Pattern Resistance (Ohms) LogOhms
1
1-2 3.98E+11 11.60
2 3-2 1.58E+11 11.20
3 3-4 6.31E+11 11.80
4 5-4 7.94E+11 11.90
5 1-2 1.00E+12 12.00
6 3-2 1.00E+12 12.00
7 3-4 3.98E+11 11.60
8 5-4 1.58E+12 12.20
9 1-2 1.26E+12 12.10
10 3-2 1.26E+12 12.10
11 3-4 1.00E+12 12.00
12 5-4 3.98E+11 11.60
13 1-2 5.01E+11 11.70
14 3-2 2.00E+11 11.30
15 3-4 1.26E+11 11.10
16 5-4 1.26E+11 11.10
17 1-2 2.51E+11 11.40
18 3-2 1.58E+11 11.20
19 3-4 2.51E+11 11.40
20 5-4 3.98E+11 11.60
21 1-2 1.26E+12 12.10
22 3-2 5.01E+11 11.70
23 3-4 2.00E+11 11.30
24 5-4 2.00E+11 11.30
25 1-2 7.94E+11 11.90
26 3-2 1.00E+12 12.00
27 3-4 3.98E+11 11.60
28 5-4 7.94E+11 11.90
29 1-2 1.26E+11 11.10
30 3-2 6.31E+11 11.80
31 3-4 2.00E+11 11.30
32 5-4 1.00E+11 11.00
IPC-TM-650
Number
2.6.3.5
Subject
Bare
Board Cleanliness by Surface Insulation Resistance
Date
01/04
Revision
P
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1
Scope
This
test method is used to characterize the
effects of flux residues on electrical performance by determin-
ing the degradation of electrical insulation resistance under
conditions of high temperature and humidity.
This method, in conjunction with the supporting documenta-
tion in IPC-J-STD-004, is intended to be equivalent to Telcor-
dia Technologies GR-78-CORE, Section 13.1, (Corrosiveness
of Soldering Fluxes) and is used primarily by telecommunica-
tions companies to qualify the candidate flux or solder paste.
2
Applicable Documents
IPC-J-STD-004
Requirements
for Soldering Fluxes
IPC-A-600
Acceptability
of Printed Board
GR-78-CORE
Physical
Design and Manufacture of Telecom-
munications Product - Telcordia Technologies (Formerly
Bellcore)
ASTM
D-257
Standard
Test Methods for DC Resistance or
Conductance of Insulating Materials
2.1
Master Drawings
Telcordia
Technologies Test Pattern (GR-78-CORE, Figures
14.1 and 14.2)
IPC-A-25A
Multipurpose
1-sided Test Pattern
IPC-A-50
Surface
Insulation Resistance Phoenix Board
3
Test Specimens
The
test specimens for this test method
may be either of the interdigitated comb pattern shown in Fig-
ures1or2.
These test patterns can be produced in a number of formats.
Both of these patterns can be found on the IPC-B-50 Stan-
dard Test Board. The pattern shown in Figure 2 can be found
on the IPC-B-25A test board (pattern D). Artwork for manu-
facturing these boards is available through the master draw-
ings listed in 2.1. Contact IPC for a listing of vendors provid-
ing prefabricated test boards.
The comb pattern in Figure 1 has 0.65 mm [0.025 in] lines and
1.27 mm [0.050 in] spacings. This test pattern is also com-
monly referred to as the Bellcore pattern.
The comb pattern in Figure 2 has 0.32 mm [0.0125 in] lines
and spaces (see Note 6.4).
Figure
1
IPC-2636-2
Figure
2
2215
Sanders Road
Northbrook, IL 60062-6135
IPC-TM-650
TEST
METHODS MANUAL
Number
2.6.3.6
Subject
Surface
Insulation Resistance - Fluxes -
Telecommunications
Date
01/04
Revision
Originating Task Group
Surface Insulation Resistance Task Group, 5-32b
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.
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