IPC-TM-650 EN 2022 试验方法.pdf - 第364页

Note 2— Instruments from duPont and Perkin Elmer have been found suitable. 6.0 Test Specimens 6.1 The test specimen shall be between .05 and 0.3 inches thick. This thickness may be as received or may be laminated by the …

1.0

Scope

1.1

This

method covers determination of the coefficient of

linear thermal expansion of electrical insulating materials

use

of a thermomechanical analyzer.

1.2

This

method is applicable to materials that are solid over

the entire range of temperature used, and that retain sufficient

hardness and rigidity over the temperature range so that irre-

versible indentation of the specimen by the sensing probe

does not occur.

1.3

Transition

temperatures also may be obtained by this

method.

2.0

Applicable Documents

ASTM D-618

Conditioning

Plastics and Electrical Insulating

Materials for Testing

ASTM-D-696

Test

for Coefficient of Linear Thermal Expan-

sion of Plastics

3.0

Summary of Method

3.1

This

method used a thermomechanical analyzer with an

X-Y recorder to graph the change of dimension as a function

of temperature of a small specimen of a solid electrical insu-

lating material. Coefficients of linear thermal expansion can be

calculated from the graph. Other thermal observations may

also be made.

Note

1—

-Other

rapid thermal analysis methods are being

studied by ASTM Subcommittees D09.17 and D20.30.

4.0

Significance

4.1

Measurements

of coefficient of linear thermal expansion

are useful in evaluating the suitability of solid insulating mate-

rials for use in combination with other materials where

mechanical stresses may develop as a result of differences in

coefficients.

4.2

This

method may be compared with Method D-696, but

tests made with this method use much smaller specimens.

This eliminates the need for large liquid baths and greatly

reduces the time required to reach temperature equilibrium.

As a result, the time required for making a test is less than for

Method D-696, and the method can conveniently be used

over a wider temperature range than for Method D-696.

5.0

Apparatus

5.1

The

thermomechanical analyzer shall include:

5.1.1

specimen holder and probe, into which the speci-

men can be placed. Changes in height of the specimen are

sensed by movement of the probe. The shape and size of the

probe shall be such that for the material tested the load

applied to the specimen by the probe shall not cause inden-

tation of the specimen within the range of temperatures of

interest.

5.1.2

Means

for sensing movement of the probe resulting

from changes in height of the specimen and for translating

these movements into a signal suitable for input to the

recorder. The sensing element should be capable of produc-

ing a movement of the recorder pen of at least 1000 times the

change in height of the test specimen, with provisions for less

sensitive ranges when needed.

5.1.3

Means

for uniformly heating the specimen holder at a

predetermined rate over the range of temperatures of interest.

This will consist of a furnace and temperature controller with

provisions for precooking the furnace and specimen holder

when measurements at subambient temperatures are to be

made.

5.1.4 Means

for measuring temperature in immediate prox-

imity to the test specimen.

5.1.5

X-Y recorder for recording changes in specimen

height as a function of specimen temperature.

1. This method is under the jurisdiction of ASTM Committee D-9 on Electrical Insulating Materials and is the direct responsibility of Subcommittee D09.01 on Electri-

cal Insulating Varnishes, Powders, and Encapsulating Compounds.

2. Annual Book of ASTM Standards, Part 39.

3. Annual Book of ASTM Standards, Part 35.

The

Institute for Interconnecting and Packaging Electronic Circuits

2215 Sanders Road • Northbrook, IL 60062-6135

IPC-TM-650

TEST

METHODS MANUAL

Number

2.4.41

Subject

Coefficient

of Linear Thermal Expansion of

Electrical Insulating Materials

Date

3/86

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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Note

2—

Instruments

from duPont and Perkin Elmer have

been found suitable.

6.0

Test Specimens

6.1

The test specimen shall be between .05 and 0.3 inches

thick. This thickness may be as received or may be laminated

by the user from pre-impregnated ‘‘B’’ stage and copper free

‘‘C’’ stage material. It laminated by the user, the user shall be

responsible to contact the manufacturer for the exact layup

and process parameters used for quality acceptance at the

manufacturers facility.

Note

3—

Repeatability

of Test Results will vary with layup,

bake out, laminating pressure/ramp speed, press time, etc.

6.2 Specimens

should be between 0.3 and 0.4 inches in

height and have flat and parallel upper and lower surfaces.

The surfaces to be measured shall be perpendicular to the

fiber fillers and the identity of the direction of the fiber fillers

shall be maintained throughout the test. The upper and lower

surfaces shall be polished with 600 grit paper to remove burrs

or strands of fiber filler. The specimens shall then be cleaned

using isopropyl alcohol, and dried for 1 hour at 10°C above

the maximum specified temperature of the run.

Note

4—

The

1 hour prebake may be eliminated if Condition

(7.), is performed immediately after final polish.

6.3

There

shall be three specimens prepared from the same

piece of material for each direction to be measured.

7.0

Conditioning

7.1

Conditioning

of test specimen shall include immersion in

isopropyl alcohol with agitation for 20 seconds, followed by

Condition E-1/110 and C

40/23/50

in accordance with

D-618.

8.0

Calibration

8.1

Calibrate

the apparatus in accordance with the instru-

ment manufacturer’s recommendations.

9.0

Procedure

9.1

Measure

the height of the specimen.

9.2 Place

the specimen in the specimen holder under the

probe. The thermocouple or other means for sensing speci-

men temperature should be in contact with the specimen, or

as near to the specimen as possible.

9.3

Assemble

the furnace to the specimen holder. If mea-

surements at subambient temperatures are to be made, cool

the specimen holder and furnace to at least 20°C below the

lowest temperature of interest, using procedures as given by

the instrument manufacturer. The refrigerant used for cooling

shall not come into direct contact with the specimen.

Note

5—

The

temperature range to be tested shall be speci-

fied by the user, so that the manufacturer and user will test

over the same temperature range. If tested over different tem-

perature ranges, the repeatability may be unacceptable.

9.4

Place

weights on the sensing probe to ensure that the

probe is in contact with the specimen witha1to3-gload.

9.5

Increase

the furnace temperature at 5 = 0.5°C/min.

over the desired temperature range.

9.6

Record

the specimen temperature and change in speci-

men height using appropriate ranges on the X-Y recorder.

Note

6—

gas purge may be used to replace the air around

the specimen for measurement of expansion in different atmo-

spheres.

9.7

Test

at least three specimens of the same material.

Retest of a specimen may be used only as reference and shall

not be treated as an independent test of a new specimen.

10.0

Calculation

10.1

Calculate

the average coefficient of thermal expan-

sions, α, over the temperature intervals of interest as follows:

α =(∆ H/∆T)/H

where:

H = original height of specimen,

∆ H = change in height of the specimen (in the same units)

over the temperature interval ∆T, and

∆ T = temperature interval, °C (see Figure 1).

Note

7—

∆H

and ∆T may on some instruments be read

directly from the recorder chart. On other instruments con-

stant factors may need to be applied to the chart readings to

obtain these values.

11.0

Report

IPC-TM-650

Number

2.4.41

Subject

Coefficient

of Linear Thermal Expansion of Electrical Insulating

Materials

Date

3/86

Revision

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11.1

The

report shall include the following:

11.1.1

Designation

of the material, including the name of the

manufacturer and information on composition when known.

11.1.2

Method

of preparation of the test specimen.

11.1.3

Specimen

orientation with respect to original sample,

if applicable.

11.1.4

Sample

size.

11.1.5

Temperatures

between which the coefficient of linear

thermal expansion has been determined.

11.1.6

Average

coefficient of linear thermal expansion per

degree Celsius.

11.1.7

Transition

temperatures, if noted.

11.1.8

Instrument

manufacturer and model number.

11.1.9

Purge

gas, if used, and rate of gas flow, and

11.1.10

X-Y

chart record.

NOTE

The

preceding test method was originally ASTM

D3386-75, until modified for use by IPC for round-robin test-

ing of organic substrate materials. Upon completion of the test

program, recommendations for revision will be made to

ASTM.

IPC-2441-1

Figure

1 Specimen height versus temperature

IPC-TM-650

Number

2.4.41

Subject

Coefficient

of Linear Thermal Expansion of Electrical Insulating

Materials

Date

3/86

Revision

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