IPC-TM-650 EN 2022 试验方法.pdf - 第421页

rest on the test specimen. 5.3.2 The arc tester should be set up for operation in the automatic mode. 5.3.3 Set the Variac to the voltage which produces 12,500 volts based on the last calibration of the Instrument (gener…

1.0

Scope

This

method describes a technique for evaluat-

ing a material to resist tracking when subjected to a low cur-

rent arc just above the surface of the material. It can be used

on materials of various thickness by stacking materials. This

procedure is based on techniques described in ASTM D495.

2.0

Applicable Documents

ASTM D495

Standard

Test Method for High Voltage, Low-

Current, Dry Arc Resistance of Solid Electrical

Insulation

Manufacturer’s Instruction Manual

3.0

Test Specimens

3.1 Number

Three

specimens shall be used unless other-

wise specified.

3.2

Form

Each

specimen shall be 3.0 in. x 2.0 in. Material

under 0.06 in. in thickness shall be built up to provide a speci-

men at least 0.06 in. but not exceeding 0.125 in. For very thin

laminates a 1/16 in. laminate of the same type may be used

under the actual specimen subjected to the arc, permitting a

reduction of the material required without significantly affecting

the results.

3.3

Location

Specimens

may be cut from any location in a

sheet (except from the outer 1 in. of full size sheets).

3.4

Foil Clad Materials

All

foil clad materials shall have the

foil removed by etching and shall be thoroughly cleaned prior

to conditioning or testing.

4.0

Apparatus/Materials

4.1

Arc

tester (Beckman ART-1

equivalent, see ASTM

D495).

4.2

Tungsten

electrodes (Beckman

equivalent, see

ASTM D495).

4.3

Constant

temperature water bath capable of 50°C ±

2°C, filled with distilled water.

4.4

Beaker

or pan filled with ambient temperature distilled

water.

4.5

Racks

for supporting specimens in the water bath with

all surfaces exposed.

4.6

Shear,

saw or paper cutter for cutting specimen.

4.7

Alcohol

or other solvent for cleaning electrode.

4.8

Crocus

cloth.

4.9

Gage

blocks for checking electrode spacing 0.248 in.

and 0.252 in.

4.10

Lint

free paper towels.

4.11

Variac

autotransformer

type W1OMT or equivalent.

5.0

Procedure

5.1 Preconditioning

Unless

otherwise specified the speci-

mens shall be conditioned for 48 hours (± 2 hours -0 hours) in

distilled water maintained at 50°C ± 2°C. Following this step

the specimens shall be immersed in ambient temperature dis-

tilled water for 30 minutes minimum, 4 hours maximum, to

allow them to reach temperature equilibrium without loss of

moisture.

5.2

Test Conditions

The

test shall be run at ambient tem-

perature 23°C ± 5°C and ambient humidity.

5.3

Equipment set up

5.3.1

The

electrode assembly shall be cleaned thoroughly

using alcohol or other suitable solvent and, if required, with

crocus cloth. The electrode gap shall be adjusted if necessary

to provide a gap of 0.250 in. ± 0.002 in. when the electrodes

ART-1 or ART-2 manufactured by Beckman Instruments Cedar Grove Essex County New Jersey, U.S.A.

2. Electrodes manufactured by Beckman Instruments

3. Variac available from General Radio

The

Institute for Interconnecting and Packaging Electronic Circuits

2215 Sanders Road • Northbrook, IL 60062

IPC-TM-650

TEST

METHODS MANUAL

Number

2.5.1

Subject

Arc

Resistance of Printed Wiring Material

Date

5/86

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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rest

on the test specimen.

5.3.2

The

arc tester should be set up for operation in the

automatic mode.

5.3.3

Set

the Variac to the voltage which produces 12,500

volts based on the last calibration of the Instrument (generally

105V to 115V).

5.3.4

Reset

the timer on the tester to ‘‘0’’ seconds if

required.

5.4

Test Procedure

5.4.1

Remove

a preconditioned specimen from the ambient

temperature distilled water and wipe dry with a lint free paper

towel.

5,4.2

Place

a specimen (individual or built up) in the elec-

trode fixture.

5.4.3

Operate

the tester in accordance with the manufactur-

er’s instructions such that an arc is generated and automati-

cally switched as indicated below.

ime (sec) On/Off Time Amperage

0-60 0.25 sec/1.75 sec 10 milliamps

60-120 0.25 sec/0.75 sec 10 milliamps

120-180 0.25 sec/0.25 sec 10 milliamps

180 continuous 10 milliamps

5.4.4

Observe

the arc carefully and, at the point which the

arc disappears and tracking occurs, stop the timer and record

the time for the specimen to the nearest second.

5.4.5

Remove

the specimen, remove and clean the elec-

trodes thoroughly using a solvent and if necessary the crocus

cloth.

5.4.6

Replace

the electrode and check the electrode gap.

5.4.7

Reset

the timer and proceed as in 5.4.1 through 5.4.6.

5.5

Calculation

5.5.1

Average

the values of the specimens tested from the

same sample and round to the nearest second.

5.6

Report

5.6.1

Report

the average value of the arc resistance in sec-

onds.

5.6.2 Report

the ambient temperature and relative humidity

at the time of the test.

5.6.3

Report

how the specimen was prepared, e.g. indi-

vidual, # of plies built up, or with a spacer.

5.6.4

Report

the preconditioning procedure.

5.6.5

Report

any anomalies in the test or variations from

procedures or tolerances specified.

6.0 Note

6.1

The

results of arc tests may be significantly affected by

contamination of the electrodes. Any irregularity of the arc in

the early portion of the test may be an indication of contami-

nation. If this occurs, the test should be stopped, the elec-

trodes cleaned and a fresh specimen should be tested (or the

test may be run in a different area of the same specimen).

6.2

While

values for reinforced material may vary with the

grain direction of reinforcement, the effect is generally insignifi-

cant with glass reinforced product. At least one specimen in

both machine and transverse direction is recommended to

verify this.

IPC-TM-650

Number

2.5.1

Subject

Arc

Resistance of Printed Wiring Material

Date

5/86

Revision

age2of2

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Scope

The

purpose of this test is to measure the capaci-

tance effects arising from plastic substrates, adhesives, or

coatings, which may be critical to the reliable functioning of a

circuit.

Applicable Documents

None

Test Specimen

Specimen

thickness for all tests must be

uniform within ±1% of the average thickness. At frequencies

below 1 MHz the specimen shall be large enough to provide

circular electrodes at least 10 cm in diameter and between

1.5 mm to 6.35 mm thick. At frequencies from 1.0 MHz to

1000 MHz, a micrometer electrode holder should be used

with the test specimen.

Equipment/Apparatus

4.1

bridge or resonant circuit capable of measuring the

capacitance and dissipation factor with the required accuracy

at the specified frequency may be used. The inherent accu-

racy of the measurement shall be ± 0.5%, ± 0.2% picofarad,

unless otherwise specified. The electrode material may be thin

foil, evaporated metal, sprayed metal, or air drying conductive

paint.

4.2

The

generating circuit may be any suitable source that

can furnish sufficient current for the specified precision of

measurement or voltage gradient in the dielectric.

Procedure

5.1 Preparation

The

atmospheric conditions surrounding

the specimen prior to and during test must be 23°C, ± 1.1°C

and 50%, ± 4% RH.

5.2

Test

Place

the test specimen in a suitable measuring

cell or holder and measure its capacitance and dissipation

factor with a suitable measuring circuit having required sensi-

tivity and accuracy.

5.3

Evaluation

Record

the shape and dimensions of the

specimen, type and dimensions of electrodes and measuring

cell, test conditions, method of measurement, applied voltage,

voltage gradient, and frequency and capacitance.

5.4

Calculation

C =

4πdo

where:

= capacitance in Farads

Q = total charge in coulombs

V = potential difference between plates in volts

GA = area of plates

4πdo = distance between plates

6 Notes

6.1

Suitable

measurement techniques must be used to mini-

mize errors due to the connections between the measuring

apparatus and the specimen.

6.2

The

AC voltage actually impressed across the specimen

must be as low as possible. When DC polarizing voltages are

required, it must be as specified.

The

Institute for Interconnecting and Packaging Electronic Circuits

2215 Sanders Road • Northbrook, IL 60062

IPC-TM-650

TEST

METHODS MANUAL

Number

2.5.2

Subject

Capacitance

of Insulting Materials

Date

7/75

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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