IPC-TM-650 EN 2022 试验方法.pdf - 第588页

1.0 Scope 1.1 Purpose This test method covers procedures for deter- mining the electrical resistivity of copper foil. It provides for an accuracy of ± 0.30 percent of test specimens having a resis- tance of 0.00001 ohm (…

Scope

This

test method is used to determine the resistiv-

ity of copper foil.

Applicable Documents

ASTM-B-193

Resistivity

of Conductive Materials

Test Specimen

3.1

Three

samples should be selected at equal distances

across the width of the material from each lot and the width

and gauge length measured to the nearest 0.025 mm.

Equipment/Apparatus

4.1 Tester

The

resistance of the samples shall be mea-

sured with instruments of suitable sensitivity (see ASTM-B-

193).

Procedure

5.1 Test

5.1.1 Resistance Determination

Three

samples shall be

selected at equal distances across the width of the material

from each lot and the width and gauge length measured to

the nearest 0.025 mm. The resistance of the samples shall be

measured with instruments of suitable sensitivity, in accor-

dance with ASTM-B-193.

5.1.2

For

convenience, the distance between test points

may be 15 cm, and the weight of the 2.5 cm wide sample

being measured is determined by weighing a 2.5 cm x 15 cm

strip from the test specimen.

5.2

Evaluation

5.2.1

Calculate the resistance using the formula:

1 +αT (t − T)

where:

= reference temperature (20°C)

t = temperature at which measurement is made (°C)

αT = temperature coefficient of resistance (0.00388)

resistance at reference temperature (20°C)

measured resistance

5.2.2

Calculate

weight resistivity in ohms - gram/meter

using

the formula:

where:

= weight of test specimen (grams)

gauge length (meters)

length of test specimen (meters)

resistance at reference temperature (20°C)

Note: If the procedure described in 5.1.2 is used, then:

Therefore

is (0.1524 meters)

or:

weight

of 0.040 mm x 0.235 mm specimen

0.02323

The

Institute for Interconnecting and Packaging Electronic Circuits

2215 Sanders Road • Northbrook, IL 60062

IPC-TM-650

TEST

METHODS MANUAL

Number

2.5.13

Subject

Resistance

of Copper Foil

Date

3/76

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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1.0

Scope

1.1 Purpose

This

test method covers procedures for deter-

mining the electrical resistivity of copper foil. It provides for an

accuracy of ± 0.30 percent of test specimens having a resis-

tance of 0.00001 ohm (10 microhms) or more.

1.2

Definition

Resistivity

is the electrical resistance of a

body of unit length and unit cross-sectional area or unit

weight. Volume resistivity is commonly expressed in ohms for

a theoretical conductor of unit length and cross-sectional

area; in English units in ohm–circular mil/ft and in metric units

in ohm–mm

/meter.

It may be calculated by the following for-

mula:

p. =

where:

= volume resistivity in ohm–circular mil/ft or ohm–mm

/meter,

= cross-sectional area in circular mils, or sq mm,

L = gauge length, used to determine R, in ft, or m, and

R = measured resistance in ohms.

Weight resistivity is commonly expressed in ohms for a theo-

retical conductor of unit length and weight. The method for

calculating weight resistivity, based on resistance, length, and

weight measurements, of a test specimen is given in Note 2.

2.0

Applicable Documents

None

3.0

Test Specimen

The

test specimen must have the fol-

lowing characteristics:

1. A resistance of at least 0.00001 ohm (10 microhms) in

the test length between potential contacts,

2. A test length of at least 1 ft or 30 cm,

3. A thickness, width or other dimension suitable to the limi-

tations of the resistance measuring instrument,

4. No surface cracks or defects visible to the unaided nor-

mal eye, and substantially free from surface oxide, dirt

and grease,

5. No joints or splices.

4.0

Apparatus

4.1 Tester

4.1.1

Kelvin-type double bridge or a potentiometer, if the

resistance of the specimen is below 1 ohm,

4.1.2

1 ohm or more, a Wheatstone bridge may be used.

4.1.3 Where

applicable, a Hoopes conductivity bridge may

be used.

4.2

Conditions

When

the measurement is made at any

other than a reference temperature, the resistance may be

corrected for moderate temperature differences to what it

would be at the reference temperatures as follows:

1 +γT

(t−T)

where:

resistance at reference temperature T,

resistance as measured at temperature t,

γT = known or given temperature coefficient of resistance

of the specimen being measured at reference tempera-

ture T,

T = reference temperature, and

t = temperature at which measurement is made.

NOTE:

The

parameter T, in the above equation, varies with

conductivity and temperature. For copper of 100 percent con-

ductivity and a reference temperature of 20°C, its value is

0.00393. Table 2 lists temperature coefficients for copper.

5.0

Procedure

5.1 Preparation

5.1.1

All

determinations of the dimensions and weight of the

test specimen must be accurate within 0.05%.

2215

Sanders Road

Northbrook, IL 60062-6135

IPC-TM-650

TEST

METHODS MANUAL

Number

2.5.14

Subject

Resistivity

of Copper Foil

Date

8/76

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

The

cross-sectional dimensions of the specimen may

be determined by micrometer measurements, and a sufficient

number of measurements shall be made to obtain the mean

cross section to within ± 0.10 percent.

5.1.3

case any dimension of the specimen is less than

0.100 in. and cannot be measured to the required accuracy,

the cross section shall be determined from the weight, den-

sity, and length of the specimen.

5.1.4

When

the density is unknown, it shall be determined

by weighing a specimen first in air and then in a liquid of

known density at the test temperature, which shall be at room

temperature to avoid errors due to convection currents.

5.1.5

Calculate

the density from the following formula:

δ=

− W

where:

δ =

density of the specimen, grams per cu cm,

weight of the specimen in air, grams,

weight of the specimen in the liquid, grams, and

d = density of the liquid at the test temperature, grams per

cu cm.

5.2

Test

5.2.1

When

potential leads are used, the distance between

each potential contact and the corresponding current contact

shall be at least equal to 1-1/2 times the cross-sectional

perimeter of the specimen.

5.2.2

The

yoke resistance (between reference standard and

test specimen) shall be appreciably smaller than that of either

the reference standard or the test specimen unless a suitable

lead compensation method is used, or it is known that the coil

and lead ratios are sufficiently balanced so that variation in

yoke resistance will not decrease the bridge accuracy below

stated requirements.

5.2.3

Make

resistance measurements to an accuracy of ±

0.15 percent.

5.2.4

all resistance measurements, the measuring current

raises the temperature of the specimen above that of the sur-

rounding medium. Therefore, care shall be taken to keep the

magnitude of the current low, and the time of its use short

enough so that the change in resistance cannot be detected

with the galvanometers.

5.2.5

eliminate errors due to contact potential, two read-

ings, one direct and one with current reversed, must be taken

in direct succession.

5.2.6

Check

tests are recommended whereby the specimen

is turned end for end, and the test repeated.

5.2.7

Surface

cleaning of the specimen at current and

potential contact points may be necessary to obtain good

electrical contact.

5.3

Evaluation

5.3.1 Reference Tests

For

reference tests, the report

should include the following:

1.Identification of test specimen,

2.Kind of material,

3.Test temperature,

4.Test length of specimen,

5.Method of obtaining cross-sectional area: the average val-

ues of micrometer readings, or, if by weighing a record of

length, weight, and density determinations that may be

made, and calculated cross-sectional area.

6.Weight, if used,

7.Method of measuring resistance,

8.Value of resistance,

9.Reference temperature,

10.Calculated value of resistivity at the reference temperature,

and

11.Previous mechanical and thermal treatments. (Since the

resistivity of a material usually depends upon them, these

shall be stated whenever the information is available. )

5.3.2

Routing Tests

For

routine tests, only such of the

items in paragraph 5.3.1 as apply to the particular case, or are

significant, shall be reported.

IPC-TM-650

Number

2.5.14

Subject

Resistivity

of Copper Foil

Date

8/76

Revision

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