IPC-TM-650 EN 2022 试验方法.pdf - 第577页

1 Scope The dielectric withstanding voltage test (also called high-potential, over potential, voltage breakdown, or dielectric strength test) consists of the application of a voltage higher than rated voltage for a speci…

5.4.3

Test to Breakdown, Step-by-Step Test

initial

voltage shall be applied equal to 50 of the breakdown voltage

in the short-time test, adjusted as shown in Table 1.

The voltage shall then be increased in equal increments as

stated in the various material specifications, the voltage being

held at each step for a definite time as stated in the specifica-

tions. The change from each step to the next higher shall be

made as rapidly as possible and the time of change included

in the succeeding test interval.

5.4.4

Test to Breakdown, Slow-Rate-of-Test

initial

voltage shall be applied equal to approximately 50% of the

breakdown voltage in the short time test, unless otherwise

specified. The voltage shall then be increased at a uniform

rate up to the point of breakdown. Unless otherwise specified,

the rate should be chosen to give approximately the same

voltage-time exposure of the test specimen, as provided in

the step-by-step test.

5.4.5

Determining Rate of Rise of Voltage

The

rate of

voltage rise may be calculated from measurements of time

required to raise the voltage between two prescribed values.

When motordriven regulating equipment is used, the speed-

control rheostat may be calibrated in terms of voltage rise for

any particular test transformer.

5.5

Number of Tests

Unless

otherwise specified, five tests

shall be made. If the average deviation from the mean

exceeds 10% or if any individual test deviates more than 15%

from the mean, five additional tests shall be made.

5.6

Report

The

report shall include the following data:

1. The average thickness of the sample

2. Breakdown voltage at each puncture

3. Volts per mil for each puncture

4. The average, maximum, and minimum volts per 0.0075

mm for each sample

5. The temperature of the surrounding medium should be

recorded

6. The RH% of the surrounding air

7. The conditioning treatment

8. The duration of the test

9. In the step-by-step test, the value of the initially applied

voltage and the voltage increment

10. In the slow rate of rise test, the value of the initially applied

voltage and the rate of rise of the voltage

11. The size and type of electrodes

12. The test medium (air or type of oil)

6 Notes

Due

to the high voltage used in this test method,

extreme caution should be exercised.

able 1 Application of Initial Voltage

Breakdown

voltage by

short-time method

Adjust 50% of breakdown

voltage to nearest

kilovolts or less 1.0 kilovolt (unless

otherwise speciﬁed)

Over 25 to 50 kilovolts.

inclusive

2.0 kilovolts

Over 50 to 100 kilovolts,

inclusive

5.0 kilovolts

Over 100 kilovolts 10.0 kilovolts

IPC-TM-650

Number

2.5.6.3

Subject

Dielectric

Breakdown Voltage and Dielectric Strength

Date

10/86

Revision

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Scope

The

dielectric withstanding voltage test (also

called high-potential, over potential, voltage breakdown, or

dielectric strength test) consists of the application of a voltage

higher than rated voltage for a specific time between mutually

isolated portions of a PCB or between isolated portions and

ground. This is used to prove that the PCB can operate safely

at its rated voltage and withstand momentary over potentials

due to switching, surges, and other similar phenomena.

Although this test is often called a voltage breakdown or

dielectric strength test, it is not intended that this test cause

insulation breakdown or that it be used for detecting corona,

rather it serves to determine whether insulating materials

and/or conductor spacings are adequate.

Applicable Documents

None

Test Specimen

The

test specimen shall be comprised of

a minimum of two conductor lines per conductive layer, suffi-

cient to allow a voltage to be applied between adjacent con-

ductor patterns both between conductive layers and on the

same conductive layer (see 6.1).

Apparatus or Material

4.1

A high voltage source capable of supplying the specified

voltage with a tolerance of ± 5% (see 6.2).

4.2

voltage measuring device with an accuracy of 5%. If

leakage current measuring capability is required, the device

shall be capable of detecting the leakage current to within 5%

of the requirement.

4.3

Soft

bristle brush

4.4 Deionized

or distilled water (2 megohm-cm minimum

resistivity recommended)

4.5

Isopropyl

alcohol

4.6

Drying

oven

Procedure

5.1 Specimen Preparation

(see

6.3)

5.1.1

Positive,

permanent, and noncontaminating identifica-

tion of test specimen is of paramount importance.

5.1.2 Visually

inspect the test specimens for any obvious

defects, as described in the applicable performance specifica-

tion. If there is any doubt about the overall quality of any test

specimen, the test specimen should be replaced and this

replacement noted.

5.1.3

Solder

single stranded (to simulate discrete compo-

nent axial leads) polytetrafluroethylene (PTFE) insulated wires

in each of the connection points of the test specimens. These

wires will be used to connect the test patterns of the test

specimens to the high voltage source.

5.1.4

Wet

test lead terminals with deionized or distilled

water and scrub with a soft bristle brush for a minimum of 30

seconds. During the remainder of the test specimen prepara-

tion, handle test specimens by the edges only (see 6.4).

5.1.5

Spray

rinse thoroughly with deionized or distilled

water. Hold test specimen at an approximate 30° angle and

spray from top to bottom.

5.1.6

Wet

test lead terminals with clean isopropyl alcohol

and agitate for a minimum of 30 seconds. Scrub with a soft

bristle brush to remove flux residue.

5.1.7

Rinse

cleaned area thoroughly with fresh isopropyl

alcohol.

5.1.8

Dry

test specimens in a drying oven for a minimum of

three hours at an oven temperature of between 49 °C to

60 °C (120 °F to 140 °F).

5.1.9

Allow

the test specimens to cool to room temperature.

(see 6.5)

2215

Sanders Road

Northbrook, IL 60062-6135

IPC-TM-650

TEST

METHODS MANUAL

Number

2.5.7

Subject

Dielectric

Withstanding Voltage, PCB

Date

05/04

Revision

Originating Task Group

Rigid Printed Board Performance Task Group

(D-33a)

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.

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5.2

Test

(see

6.6)

5.2.1

Raise

the test voltage from zero to one of the follow-

ing specified test condition values (see 6.2) as uniformly as

possible, at a rate of approximately 100 volts DC per second.

If the test condition is not specified Condition A shall be the

default.

Condition A: 500+15/-0 volts DC

Condition B: 1000+25/-0 volts DC

5.2.2

Maintain

the test voltage at the specified value for a

period of 30+3/-0 seconds.

5.2.3

Upon

completion of the test, the test voltage shall be

gradually reduced to avoid surges.

5.3

Evaluation

Examine

the test specimens and note any

evidence of inadequate insulating materials and/or conductor

spacing (i.e., visually inspect for flashover, sparkover or break-

down between conductor patterns or between conductor pat-

terns and mounting hardware).

6 Notes

6.1

Recommended

test specimens include ‘‘Y’’ test pat-

terns (also referred to as ‘‘E’’ test coupons) or ‘‘comb pat-

terns.’’ Production printed boards may also be used as test

specimens.

6.2

Performance

specifications should specify the high volt-

age test condition and any deviations to this test method. If no

test condition is specified, use test condition A.

6.3

This test method may be performed on test specimens

which have previously been prepared and tested for moisture

and insulation resistance.

6.4

Alternative cleaning procedures may be implemented if

there is a concern that scrubbing will adversely affect test

results, e.g., when the test specimens have very fine spacing

and/or are plated with soft metals (tin/lead, gold, etc.).

6.5

Insulating

compound (conformal coating) may be

applied to the test specimens following soldering and clean-

ing. Any coating application and cure shall be as specified by

the coating supplier.

6.6

The

testing process outlined in 5.2 should be used for

qualification testing. For in-plant quality conformance testing,

the following testing modifications may be chosen:

6.6.1

the option of the customer, reduced time with a

possible correlated higher test voltage may be used.

6.6.2

the option of the customer, an AC test voltage may

be applied.

6.6.3

the option of the customer, the test voltage may be

applied instantaneously.

IPC-TM-650

Number

2.5.7

Subject

Dielectric

Withstanding Voltage, PCB

Date

05/04

Revision

age2of2

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