IPC-TM-650 EN 2022 试验方法.pdf - 第579页

1 Scope The dielectric withstanding voltage test (also called high-potential, over potential or voltage breakdown test) consists of the application of a voltage higher than rated volt- age for a specific time between mut…

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

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Scope

The

dielectric withstanding voltage test (also

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

consists of the application of a voltage higher than rated volt-

age for a specific time between mutually isolated portions of a

PWB or between isolated portions and ground. This is used to

prove that the PWB 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 test, it is not intended that

this test cause insulation breakdown or to be used for detect-

ing corona. Rather, it serves to determine whether insulating

materials and/or conductor spacings are adequate.

Applicable Documents

IPC-CC-830

Qualification

and Performance of Electrical Insu-

lating Compound for Printed Board Assemblies

IPC-A-600

Acceptability

of Printed Wiring Boards

MIL-STD-202

Method

301

J-STD-004

Requirements

for Soldering Fluxes

Test Specimens

3.1 Qualification Testing, Classes 1-3

Five

IPC-B-25A

boards (see Figure 1) using the D comb pattern (one uncoated

and four coated) with conformal coating according to the

coating suppliers recommendations.

3.2

Conformance Testing

Five

IPC-B-25A Boards (See

Figure 1) containing the C pattern (‘‘Y’’ shape pattern) with

0.635 mm lines/0.635 mm spacing [25.00 mil lines/25.00 mil

spacing] or minimum spacing on the production board,

whichever is smaller, coated with conformal coating according

to the coating supplier’s recommendations.

Apparatus

4.1 Soldering Iron

4.2 Flux

Water

white rosin (R or RMA) with halide content

less than 0.5%, i.e., type Symbol A and B or ROL0 and ROL1

according to J-STD-004.

4.3

Hi-Pot Tester

Capable

of supplying a test voltage of

1,500 VAC at 50-60 hertz (Hz) and able to record a leakage

rate.

4.4

Timer

4.5 Oven

Capable

of maintaining 60°C [140°F].

4.6

Desiccator

5 Test Specimens Preparation Prior to Testing

5.1

Solder

wires to the finger tabs on the ‘‘D’’ comb pattern

using R or RMA flux.

5.1.1

Clean

the specimens using a soft bristle brush while

rinsing with deionized water for 30 seconds.

IPC-2571-1

Figure

1 IPC-B-25A Test Board (Leads on D Pattern Are

Identiﬁed)

2215

Sanders Road

Northbrook, IL 60062-6135

IPC-TM-650

TEST

METHODS MANUAL

Number

2.5.7.1

(Supersedes

2.5.7C for Conformal Coating Test)

Subject

Dielectric Withstanding Voltage - Polymeric

Conformal Coating

Date

07/00

Revision

Originating Task Group

Conformal Coating Task Group (5-33a)

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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5.1.2

Immerse

and agitate the test specimens in 2-propanol

for 30 seconds. Scrub with a soft bristle brush and spray with

clean 2-propanol.

5.1.3

Place

the cleaned specimens in an oven maintained at

50°C [122°F] for three to five hours to dry.

5.1.4

Remove

the specimens from the oven and place in a

desiccator to cool.

5.1.5 Conformal

coat the test specimens and cure in accor-

dance with the suppliers recommendations. If the specimens

are not used immediately, seal the specimens in Kapac®

bags.

5.2

Procedure

5.2.1

For

each individual specimen, secure all the positive

leads (1, 3 and 5) together and the negative (2 and 4)

together.

5.2.2

Attach

the leads of the Hi-Pot Tester to the wires of

the test specimen.

5.2.3

Raise the test voltage from zero to 1,500 VAC at 100

VAC per second.

5.2.4 Apply the test voltage of 1,500 VAC at 50-60 Hz for

one minute and record any leakage rate.

5.2.5

After

the one-minute duration, turn off the voltage and

disconnect the test specimen from the Hi-Pot Tester.

6.0

Evaluate

6.1

Record

if the specimen exhibits flashover, sparkover or

breakdown.

6.1.1

Record

the leakage current of each specimen.

IPC-TM-650

Number

2.5.7.1

Subject

Dielectric

Withstanding Voltage - Polymeric Conformal Coating

Date

07/00

Revision

age2of2

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