IPC-TM-650 EN 2022 试验方法.pdf - 第236页
1 Scope With this test method, the flexural fatigue life for any given bend radius, the flexural fatigue behavior, and the ductility of the metal cladding in percent deformation after ten- sile failure can be determined.…
5.2.2
Mount
test specimen between mandrels, plug relay
leads into relay jacks, set counter to zero, and start flex tester.
5.2.3
Electrical
discontinuity constitutes failure and the flex
tester stops automatically.
5.2.4
Record
cycles-to-failure indicated on counter.
5.3
Evaluation
5.3.1 Ductility Test
5.3.1.1
Calculate
the ductility for each specimen by itera-
tively solving the formula below:
N
f
−0.6
D
f
0.75
+ 0.9
S
u
E
[
exp(D
f
)
0.36
]
(0.1785
log
10
5
N
f
)
−
2t
M
2
1
+t
= 0
where:
D
f
=
fatigue ductility, inch/inch (x100,%)
N
f
=
cycles-to-failure
S
u
=
ultimate tensile strength, psi
E = modulus of elasticity, psi
t
M
=
core thickness, inch
t = specimen micrometer thickness, inch
ρ = mandrel radius of curvature, within 0.005 mm [0.0002
inch]
Note: This formula is exact only for symmetric cross sections.
In the case of nonsymmetrical single-sided laminate, the
uncertainty of the location of the neutral axis introduces some
error. The error in D, is kept below 20% if
[
t
t
M
−1
]
2
E
substrate
E
≤ 0.1
IPC
Design Guide, IPC-D-330, Section 6, ‘‘Flexibility Consid-
erations in Design of Flexible Printed Wiring,’’ gives more
detailed information for the accurate determination of the loca-
tion of the neutral axis and the cyclic strains.
Note: Determine S
u
as
per IPC-TM-650, Method 2.4.18.
Determine E during the test for S
u
by
unloading and reloading
after about 2% elongation and measuring the slope of the
reloading curve.
Note: The calculator program described in paragraph 6.2
solves the ductility formula and conveniently prompts for all
necessary input parameters.
5.3.1.2
Report
the average product ductility from at least
three specimens.
5.3.2
Fatigue Test
The
number of cycles-to-failure, is the
flexural fatigue life in fully reversed bending for the bend radius
corresponding to the radius (1/2 diameter) of the test mandrel
used. An average flexural life from at least three specimens
should be reported.
5.3.3
Fatigue Behavior
The
fatigue behavior of a sample
can be obtained by determining the flexural fatigue life with a
number of different diameter mandrels. Plotting the results in
a strain range versus fatigue life Manson-Coffin plot log ∆ε =
[2t
M
/(2tρ +
t)] versus log N
f
)
allows intra- and extrapolation to
other bend radii or fatigue lives.
5.3.4
The
flexural fatigue life at bend radii other than the
mandrel radius can also be obtained by evaluating the ductil-
ity formula for the flex life in cycles-to-failure using the product
ductility determined in 5.3.1.2 and the desired bend radius.
6.0 Notes
For
further technical details, reference the mate-
rial shown below.
6.1
Document
in paragraph 2.0.
6.2
Engelmaier,
W., ‘‘Fatigue Ductility for Foils and Flexible
Printed Wiring.’’ Program No. 1883D HP-67/97 User’s
Library, Hewlett Packard Co., Corvallis, Oregon, 1978.
6.3
Engelmaier,
W., ‘‘Fatigue Ductility Flex Tester,’’ Drawing
L520163, Bell Telephone Laboratories, Inc., Whippany, New
Jersey, 1978.
6.4
Test Equipment Sources
The
equipment sources
described below represent those currently known to the
industry. Users of this test method are urged to submit addi-
tional source names as they become available, so that this list
can be kept as current as possible.
6.4.1
Fatigue
Ductility Flex Tester, Universal Mfg. Co., Inc.,
1168 Grove St., Irvington, NJ 07111; 201-374-9800.
6.4.2
JDC
Precision Sample Cutter Model JDC 125-N or
equal.
IPC-TM-650
Number
2.4.3.1
Subject
Flexural
Fatigue and Ductility, Flexible Printed Wiring
Date
3/91
Revision
C
P
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1
Scope
With
this test method, the flexural fatigue life for
any given bend radius, the flexural fatigue behavior, and the
ductility of the metal cladding in percent deformation after ten-
sile failure can be determined.
Note: The indirect determination of cladding ductility by using
a fatigue test is made necessary by the geometry and dimen-
sions of foil samples, which make tensile elongation and rup-
ture tests inadequate for ductility determination.
Note: Processing may change the original mechanical prop-
erties of the conductor metal.
2
Applicable Documents
IPC-TM-650
Test
Methods Manual
2.1.1 Microsectioning
2.4.18 Tensile Strength and Elongation, Copper Foil
IPC-D-330
IPC
Design Guide
3
Test Specimen
Foil/dielectric
laminate of sufficient size
to permit cutting of three 3.2 mm wide specimens of at least
50.8 mm in length. Specimens must be clean cut and free of
burrs and nicks.
4
Equipment/Apparatus
4.1
Ductility
Flex Tester, Universal Mfg., Model FDF or 2FDF
or equivalent (see 6.4 and Figure 1)
4.2
Sample
cutter, punch or tensile cut router (see 6.4.2)
4.3
Micrometer
tool capable of measurement to the nearest
0.0025 mm
4.4 Hewlett-Packard,
HP-67, Programmable Calculator or
equivalent
4.5
Sample
holders, 203.2 mm x 12.7 mm, of very flexible
material (e.g., epoxy impregnated glass cloth, paper, etc.)
4.6
Microscope
– capable of 200X
5
Procedure
5.1 Preparation of Samples
5.1.1
The
samples should be smooth and undistorted
(wrinkle free).
5.1.2
Use
the sample cutter to cut the 3.2 mm-wide test
specimen. Examine each specimen for nicks, cuts, or curled
edges. Discard any specimen with defects.
5.1.3
Use
the micrometer to determine the specimen thick-
ness, t, in the center of each specimen to the nearest 0.0025
mm. In the case of single sided specimens the core thickness,
t
M
has
to be determined also (see Figure 2).
Note: Thickness is a critical parameter in the determination of
fatigue ductility. A 10% error in t
M
results
in a 14% error in D
f
.
Note: The
second configuration in Figure 2, the core thick-
ness, t
M
,
is preferably determined as a fraction of the speci-
men thickness, t, from a microsection prepared per IPC-TM-
650, Method 2.1.1, and measured with a metallurgical
microscope at 200X minimum with a suitable filar eyepiece or
reticle. The measurement is to be made from the valley of the
rough surface to the smooth surface or valley to valley where
both surfaces are rough. The t
M
is
to be made once on a
IPC-2421-2
Figure
1 Fatigue Ductility Flex Tester
The
Institute for Interconnecting and Packaging Electronic Circuits
2215 Sanders Road • Northbrook, IL 60062-6135
IPC-TM-650
TEST
METHODS MANUAL
Number
2.4.3.2
Subject
Flexural
Fatigue and Ductility, Flexible Metal-Clad
Dielectrics
Date
3/91
Revision
C
Originating Task Group
N/A
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.
P
age1of3
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batch
or lot basis, and this fractional value of t
M
/t
is then mul-
tiplied by all other micrometer, t, values to achieve core values
for all samples.
5.1.4
Connect
all conductors to be tested and monitored in
series and attach thin relay leads to the two free ends.
5.1.5
Attach
test specimen to the ends of two sample hold-
ers with adhesive tape and clamp 224 grams circuit weight
to the free ends of the sample holders to form a loop (see Fig-
ure 1).
Note: For flexural fatigue test lasting in excess of 1000 cycles,
the adhesive tape attachment needs to be substantial enough
to prevent relative sliding of the specimen and sample holder
as a result of cyclic flexure movements.
5.2
Test Procedure
5.2.1
Mount
mandrels to flex tester and adjust the support
roller positions for a clearance of 1.27 mm (shim provided)
between rollers and mandrels.
Note: For the ductility test, it is important that the specimens
fail between 30 cycles and 500 cycles. Suggested mandrel
diameters are 19.05 mm for double-sided laminate and 6.35
mm for single-sided laminate, but for some samples, mandrel
diameters different from the above suggested may be neces-
sary. Larger mandrel diameters result in longer cyclic life and
smaller diameters in shorter life.
5.2.2
Mount
the test specimen between mandrels, plug the
relay leads into the relay jacks, set the counter to zero, and
start the flex tester.
5.2.3
Electrical
discontinuity constitutes failure; the flex
tester stops automatically.
5.2.4
Record
cycles-to-failure indicated on counter.
5.3
Evaluation
5.3.1 Ductility Test
5.3.1.1
Calculate
the ductility for each specimen by itera-
tively solving the formula below:
N
f
−0.6
D
f
0.75
+ 0.9
S
u
E
[
exp(D
f
)
0.36
]
(0.1785
log
10
5
N
f
)
−
2t
M
2
e
+ t
= 0
where:
D
f
=
fatigue ductility, inch/inch (x100,%)
N
f
=
cycles-to-failure
S
u
=
ultimate tensile strength, psi
E = modulus of elasticity, psi
t
M
=
core thickness, inch
t = specimen micrometer thickness, inch
ρ = mandrel radius of curvature, within 0.005 mm
Note: This formula is exact only for symmetric cross sections.
In the case of non-symmetrical single-sided laminate, the
uncertainty of the location of the neutral axis introduces some
error. The error in D
f
is
kept below 20% if
[
t
t
M
−1
]
2
E
substrate
E
≤0.1
IPC-D-330
gives more detailed information for the accurate
determination of the location of the neutral axis and the cyclic
strains.
Note: Determine S
u
as
per IPC-TM-650, Method 2.4.18.
Determine E during the test for S
u
by
unloading and reloading
after about 2% elongation and measuring the slope of the
reloading curve.
5.3.1.2
Report
the average product ductility from at least
three specimens.
IPC-2432-1
Figure
2 Core Thickness
t
M
t
t = t
M
SUBSTRA
TE
CONDUCTOR
CONDUCTOR
SUBSTRATE
CONDUCTOR
IPC-TM-650
Number
2.4.3.2
Subject
Flexural
Fatigue and Ductility, Flexible Metal-Clad Dielectrics
Date
3/91
Revision
C
P
age2of3
电子技术应用 ｗｗｗ．ＣｈｉｎａＡＥＴ．ｃｏｍ