IPC-TM-650 EN 2022 试验方法.pdf - 第230页

5.3.4 The flexural fatigue life at bend radii other than man- drel radius can also be obtained by evaluating the ductility for- mula for the flex life in cycles-to-failure using the fatigue duc- tility determined in 5.3.…

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 inch] (shim

provided) between rollers and mandrels.

Note:

For

the ductility test, it is important that the specimens

fail between 30 and 500 cycles. Mandrels with 2.0 or 1.0 mm

[0.079 or 0.040 inch] diameter are suggested but for some

samples, mandrel diameters different from these diameters

might be necessary. Larger mandrel diameters result in longer

cyclic life and smaller diameters in shorter life.

5.2.2

Mount

test specimen between mandrels, attach relay

leads with alligator clips to foil weight wing nut to form ‘‘slip-

off’’ electrical connections, plug relay leads into relay jacks,

set counter to zero, and start flex tester.

5.2.3 Complete

separation of the foil specimen constitutes

failure and the flex tester stops automatically when the drop-

ping foil weight dislodges the alligator clips from the wing nut.

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:

−0.6

0.75

+ 0.9

[

exp(D

)

0.36

]

(0.1785

log

)

−

21+t

= 0

where:

fatigue ductility, inch/inch (x100,%)

cycles-to-failure

ultimate tensile strength, psi

E = modulus of elasticity, psi

core thickness, inch

t = specimen micrometer thickness, inch

1 = mandrel radius of curvature, inch within 0.005 mm

[0.0002 inch]

Note:

Determine

per Test Method 2.4.18 of IPC-TM-

650. Determine E during the test for S

unloading and

reloading after about 2% elongation and measuring the slope

of the reloading curve.

Note:

The

determination of E foils is not a straightforward

procedure. It is therefore suggested that for specification pur-

poses standard values of E be adopted. For copper foil such

standard values might be: E(CF−E)=12x10

psi

for electro-

deposited foil, E(CF−W)=16x10

psi

for wrought (rolled) foil.

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 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 man-

drels used. An average flexural life from at least three speci-

mens 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 Manon-Coffin plot log ∆ε =

[2t

/(21 +

t)] versus log N

)

allows intra- and extrapolation to

other bend radii or fatigue lives.

IPC-2421-2

Figure

2 Fatigue ductility ﬂex tester

IPC-TM-650

Number

2.4.2.1

Subject

Flexural

Fatigue and Ductility, Foil

Date

3/91

Revision

age2of3

电子技术应用　　　　　　　ｗｗｗ．ＣｈｉｎａＡＥＴ．ｃｏｍ

5.3.4

The

flexural fatigue life at bend radii other than man-

drel radius can also be obtained by evaluating the ductility for-

mula for the flex life in cycles-to-failure using the fatigue duc-

tility 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 (IPC-TP-204).

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 Tool & Machine

Inc., 171 Coit St., Irvington, NJ 07111; 201-374-4400.

6.4.2

JDC

Precision Sample Cutter, Model JDC 125-N or

equal.

IPC-TM-650

Number

2.4.2.1

Subject

Flexural

Fatigue and Ductility, Foil

Date

3/91

Revision

age3of3

电子技术应用　　　　　　　ｗｗｗ．ＣｈｉｎａＡＥＴ．ｃｏｍ

1.0

Scope

With

this test method the flexural fatigue life for

any given bend radius, the flexural fatigue behavior and the

ductility in percent deformation after tensile failure can be

determined.

Note:

The

indirect determination of foil 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.

2.0

Applicable Documents

IPC-TM-650

Method

2.1.1, Microsectioning

Method 2.4.18, Tensile Strength and Elongation, Copper Foils

3.0

Test Specimen

Foil

of sufficient size to permit cutting

of three 3.2 mm [1/8 inch] wide specimens of at least 50.8

mm [2 inches] in length. Specimens must be clean cut and

free of burrs and nicks.

4.0

Apparatus

4.1

Ductility

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

or equal (see 6.4 and Figure 2).

4.2

Sample

cutter, punch or tensile cut router. Note 6.4.

4.3

Micrometer

tool capable of measurement to the nearest

0.0025 mm [0.0001 inch].

4.4

Programmable

Calculator, Hewlett-Packard HP-67, or

equivalent.

4.5

Sample

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

flexible but durable material, e.g., epoxy-impregnated glass

cloth, paper, etc.

4.6

Microscope

5.0 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 [1/8 inch]

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 center of each specimen to the nearest 0.0025 mm

[0.0001 inch]. If one or both specimen surfaces are rough, it

is necessary to determine the core thickness, t

from

a micro-

section (see Figure 1).

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:

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.

Note:

Care

must be taken that during thickness measure-

ments the specimens are not compressed or surface rough-

ness crushed, producing false low thickness readings.

5.1.4

Attach

test specimen to the ends of 2 sample holders

with adhesive tape and clamp 84 grams [3 ounce] foil weight

(not the 8 ounce weight shown in Figure 2) to the free ends of

the sample holders to form a loop (See Figure 2).

IPC-2421-1

Figure

1 Smooth and rough foil

▼

t = t

The

Institute for Interconnecting and Packaging Electronic Circuits

2215 Sanders Road • Northbrook, IL 60062-6135

IPC-TM-650

TEST

METHODS MANUAL

Number

2.4.2.1

Subject

Flexural

Fatigue and Ductility, Foil

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.

age1of3

电子技术应用　　　　　　　ｗｗｗ．ＣｈｉｎａＡＥＴ．ｃｏｍ