IPC-TM-650 EN 2022 试验方法.pdf - 第233页

1.0 Scope With this test method the flexural fatigue life for any given bend radius, the flexural fatigue behavior and the ductility of the conductor metal in percent deformation after tensile failure can be determined. …

1 Scope To determine the number of flexes to conductor

failure of etched flexible printed board conductor patterns.

2 Applicable Documents None

3 Test Specimen The test specimen shall consist of an

etched conductor pattern in accordance with Figure 1. A mini-

mum of six specimens with the long dimension of the conduc-

tors oriented in the transverse direction of the base material

shall be prepared using standard commercial practices.

For double-sided clad constructions, a separate sample

specimen shall be prepared for each side. The opposite

(untested) side shall be completely etched of copper.

4 Apparatus Flexural Endurance Tester (see Figure 2) or

equivalent.

5 Procedures

5.1

Examine the etched conductor specimen for any pre-

existing fractures and look for evidence of process anomalies

(such as pin holes and nicks), which could cause premature

fracture. If such fractures or anomalies are found, the speci-

men shall be discarded and a new specimen selected.

5.2 Attach (solder, clamp, etc.) a short length of insulated

wire to the extreme ends of the conductor pattern of each of

the six specimens.

5.3 Using the flexure test equipment as seen in Figure 2,

mount the specimen so that the inside diameter of the loop is

6mm±1mm[approximately, 0.25 in ± 0.04 in] and connect

the two wires to the relay. The horizontal oscillation of the

reciprocating bar causes the flexible test specimen to move in

what can be described as a rolling, flexible action.

5.4 Test three specimens per clad side with the conductor

on the inside of the loop. The reciprocating travel should not

exceed 10 cycles per minute. The loop shall travel 25 mm ±

5 mm [effectively, 1 in ± 0.2 in].

5.5 The number of cycles to failure is when electrical discon-

tinuity of the conductor occurs.

5.6 Report the average number of cycles to failure for the

three specimens tested per clad side.

6 Note Master set of drawings of a similar test fixture as

seen in Figure 2 is available from the IPC office. This fixture is

not commercially available.

IPC-243-1

Figure 1 Flexural Endurance Test Pattern.

(NOTE: Conductors are 1.5 mm ± 0.1 mm [approximately, 0.059 in ±

0.004 in] wide on 2.5 mm ± 0.1 mm [approximately, 0.01 in ± 0.004 in]

centers.)

IPC-243-2

Figure 2 Typical Flexural Endurance Test Fixture Equipment

3000 Lakeside Drive, Suite 309S

Bannockburn, IL 60015-1249

IPC-TM-650

TEST METHODS MANUAL

Number

2.4.3

Subject

Flexural Endurance, Flexible Printed Board

Materials

Date

6/11

Revision

Originating Task Group

Flexible Circuits Test Methods Subcommittee

(D-15)

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.

Page1of1

1.0

Scope

With

this test method the flexural fatigue life for

any given bend radius, the flexural fatigue behavior and the

ductility of the conductor metal in percent deformation after

tensile failure can be determined.

Note: The indirect determination of conductor ductility by

using a fatigue test is made necessary by the geometry and

dimensions of foil samples which make tensile elongation and

rupture tests inadequate for ductility determination.

2.0

Applicable Documents

IPC-TM-650

Method

2.1.1, Microsectioning

IPC-TM-650

Method

2.4.18, Tensil Strength and Elongation,

Copper Foil

IPC-D-330

IPC

Design Guide

3.0

Test Specimen

3.1

The

test coupon shown in Figure 1 is the recommended

standard test specimen pattern for either single- or double-

sided flexible printed wiring.

3.2

The

conductor width of the standard test pattern (Figure

1) can be changed to determine line width effects.

Note: Narrow conductor width will result in reduced flex lives

due to an increased flaw size/conductor width ratio. Wide

conductors result in increased flex lives due to longer crack

propagation times and the possibility of strain relief due to

cracks propagating in close proximity from opposite conduc-

tor edges.

3.3 Actual

flexible printed wiring product, whole or sections

thereof, can be used if the circuit geometry is such that the

long dimension is at least 63.2 mm [2.5 inches], the wide

dimension no more than 38.1 mm [1.5 inches], and the con-

ductors in the long direction can be electrically connected in

series to give a pattern similar to the standard test pattern (see

Figure 1).

4.0

Apparatus

4.1

Ductility

Flex Tester, Universal Mfg., Model FDF or 2FDF

or equivalent (see 6.4 and Figure 2).

4.2 Sample

cutter, punch or tensile cut router. Note 6.3.2.

4.3

Micrometer

tool capable of measuring 0.0025 mm

[0.0001 inch].

4.4

Hewlett-Packard,

HP-67, Programmable Calculator or

equivalent.

4.5

Sample

holders, 203.2 x 12.7 mm [8 x 1/2 inch] of very

flexible material, e.g., epoxy-impregnated glass cloth, paper,

etc.

4.6 Microscope

5.0

Procedure

5.1 Preparation of Samples

5.1.1

Use

the sample cutter to cut the 3.2 mm [1/8 inch]

wide test specimen. Examine each specimen for nicks, cuts,

or curled edges. Discard any specimen with defects.

IPC-2431-1

Figure

1 Test coupon conﬁguration (recommended)

▼

45327

104mm

[4.10]

76.2mm

[3.00"]

NOTE 3

3.81mm [.150] (NOTE 1)

NOTES:

1. 0.76mm [.030"] Conductor width,

0.76mm [.030"] spacing

2. Pattern on opposite circuit

sides are identical

3. 5-digit lot number of

production lot.

▼

2.54mm

[.100"] 12.7mm

[.050"] 12.7mm

[.050"]

88.9mm

[3.50"]

The

Institute for Interconnecting and Packaging Electronic Circuits

2215 Sanders Road • Northbrook, IL 60062-6135

IPC-TM-650

TEST

METHODS MANUAL

Number

2.4.3.1

Subject

Flexural

Fatigue and Ductility, Flexible Printed

Wiring

Date

3/91

Revision

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.

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5.1.2

Use

the micrometer to determine the specimen thick-

ness, t, at the test region of the specimens to the nearest

0.0025 mm [0.0001 inch]. In the case of single-sided or

cover-coated specimens, core thickness, t

has to be deter-

mined also (see Figure 2).

Note: Thickness is a critical parameter in the determination of

fatigue ductility. A 10% error in t

results

in a 14% error in D

Note: For

asymmetric configuration (2nd configuration in Fig-

ure 2) the core thickness, t

is preferably determined as a

fraction of the specimen thickness, t, from a microsection pre-

pared 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

to be made

once on a batch or lot basis, and this fractional value of t

then multiplied by all other micrometer, t, values to achieve

core values for all samples. This applies only to the second

and third configuration in Figure 2, where t

cannot

be deter-

mined by a micrometer.

5.1.3

For

standard test coupons, connect the meander pat-

terns on opposite circuit sides in series and attach thin relay

leads to the free ends of the meander patterns. For nonstand-

ard test specimens, connect all conductors to be tested and

monitored in series and attach thin relay leads to the two free

ends.

5.1.4

Attach

test specimen to the ends of 2 sample holders

with adhesive tape and clamp 224 grams [8 ounces] circuit

weight to free ends of sample holders to form a loop (see Fig-

ure 3).

Note: For flexural fatigue tests lasting in excess of 1000

cycles, the adhesive tape attachment needs to be substantial

enough to prevent relative sliding of specimen and sample

holder as a result of the cyclic flexure movements.

5.2

Test Procedure

5.2.1

Mount

mandrels to flex tester, adjust the support roller

positions for a clearance of 1.27 mm [0.05 inches] (shim pro-

vided) between rollers and mandrels.

Note: For the ductility test, it is important that the specimens

fail between 30 and 500 cycles. Suggested mandrel diam-

eters are 19.05 mm [0.750 inch] for double-sided circuitry and

6.35 mm [0.250 inch] for single-sided circuitry, but for some

samples, mandrel diameters different from these diameters

may be necessary. Larger mandrel diameters result in longer

cyclic life and smaller diameters in shorter life.

IPC-2431-2

Figure

2 Minimum core thickness

COVERCOAT

▼

t = t

SUBSTRATE

CONDUCTOR

SUBSTRATE

CONDUCTOR

SUBSTRATE

IPC-2421-2

Figure

3 Fatigue ductility ﬂex tester

IPC-TM-650

Number

2.4.3.1

Subject

Flexural

Fatigue and Ductility, Flexible Printed Wiring

Date

3/91

Revision

age2of3

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