IPC-TM-650 EN 2022 试验方法.pdf - 第619页

5.2.5 After allowing the meter to ‘‘charge’’ for 60 seconds, switch to ‘‘measure’’ and read the meter in megohms after the indicator settles down (usually within 60 seconds). 5.3 Evaluation Readings shall be recorded to …

Scope

This

test method is designed to determine the sur-

face insulation resistance of dielectric material after the pre-

scribed conditioning cycles.

2 Applicable Documents

MIL-STD-202

Method

106, Electronic Components

Test Specimens

3.1

least two specimens, modeled after the IPC-B-25 (see

Figure 1) shall be made. The copper foil shall be removed by

chemical etching, using standard commercial practices.

Apparatus

4.1

test chamber capable of meeting MIL-STD-202,

Method 106, and elevated temperature of 150°C

4.2

meter capable of applying 500 VDC to the specimens

for a period of 60 +5/-0 seconds and measuring resistance

values between 1 megohm and 10 million megohms with

measurement error of less than 1% — A H/P Model 4329A,

High Resistance Meter, or equivalent

5 Procedure

5.1 Preparation

5.1.1

Double-clad

material shall have one side completely

etched. The other side and single-clad material shall be

etched as specified in 3.1.

5.1.2

Specimens

shall be dried for a period of 24 ± 2 hours

at 50°C ± 5°C. Measurements shall be made immediately

after removal from the chamber.

5.1.3

Specimens

shall be subjected to the conditioning

cycle of MIL-STD-202, Method 106 (except steps 7a and 7b).

The measurements shall be made inside the chamber after

completion of the cycle.

5.1.4 Specimens

shall be subjected to elevated temperature

for 24 hours at 150°C ± 5°C. Measurements shall be made

within 30 minutes after the completion of this cycle.

5.2

Test

5.2.1

Measurements

shall be made after each conditioning

phase. The specimens shall be removed from the chamber

before measurements specified in 5.1.2 and 5.1.4 are taken.

Specimens shall be left inside the chamber for taking mea-

surements specified in 5.1.3. Four readings per the comb pat-

tern shall be taken for each specimen; readings shall be

between pins1&2,1&3,3&5,and4&5(see Figure 1).

5.2.2

Turn

the megohmmeter on prior to the removal of the

specimens from the chamber. Allow the meter to warm up for

a minimum of 30 minutes.

5.2.3

After

warm-up, calibrate the meter and set the voltage

to 500 VDC.

5.2.4

Connect

the leads to the appropriate pins (see Figure

1).

IPC-2-5-27-1

Figure

1 Surface Insulation Resistance Test Pattern

(Modeled

after IPC-B25 Test Board)

The

Institute for Interconnecting and Packaging Electronic Circuits

2215 Sanders Road • Northbrook, IL 60062

IPC-TM-650

TEST

METHODS MANUAL

Number

2.5.27

Subject

Surface

Insulation Resistance of Raw Printed

Wiring Board Material

Date

3/79

Revision

Originating Task Group

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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5.2.5

After

allowing the meter to ‘‘charge’’ for 60 seconds,

switch to ‘‘measure’’ and read the meter in megohms after

the indicator settles down (usually within 60 seconds).

5.3

Evaluation

Readings

shall be recorded to two signifi-

cant digits in megohms.

6 Notes

6.1

This

method can be used in substitution for surface

resistance. Volume resistivity cannot be replaced by this

method, but other tests such as dielectric strength, dissipa-

tion factor, and dielectric constant will give a better indication

of the electrical properties than volume resistivity.

IPC-TM-650

Number

2.5.27

Subject

Surface

Insulation Resistance of Raw Printed Wiring Board

Material

Date

3/79

Revision

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Scope

This

method is used to determine the attenuation

of balanced and unbalanced cables.

Applicable Documents

None

Test Specimen

3.1

30.5

meters of completed flat cable

Apparatus

4.1

H.R.

Model #8568A or equivalent spectrum analyzer

4.2

H.R.

Model #8444A or equivalent 2 tracking generator

4.3

Two

RG-223/U or equivalent 50 Ohm coaxial cables

4.4

North

Hills or equivalent matching transformers

Unbal/Bal

Freq. Range Model No.

50/50

100 KHz to 125 MHz 0001 BB

50/75 100 KHz to 125 MHz 0101 BB

50/90 100 KHz to 125 MHz 0200 BB

50/100 100 KHz to 100 MHz 0300 BB

50/150 100 KHz to 100 MHz 0400 BB

4.5

Resistor

matching network (see Figure 1)

Procedure

5.1 Procedure (Balanced)

5.1.1

Calibrate

spectrum analyzer and adjust the tracking

generator for accurate frequency tracking.

5.1.2

Select

impedance matching transformers that match

(as close as possible) the characteristic impedance of the

cable under test.

5.1.3 Connect

the outputs of the two matching transformers

together. Sweep the spectrum analyzer through the required

frequency range to determine the loss in the matching trans-

formers.

5.1.4

Separate

the two matching transformers and connect

30.5 m of the test cable between them; again sweep the

spectrum analyzer through the required frequency range. This

measurement determines the total loss, which includes the

cable and matching transformers.

5.1.5

determine the cable attenuation, based on 30.5

meters of cable, at each frequency of interest, subtract the

results of 5.1.3 from the results of 5.1.4 (see Figure 2).

5.2

Procedure (Unbalanced)

5.2.1

Calculate

the resistance required to match the 50 ohm

system impedance to the test cable’s characteristic imped-

ance, as shown in Figure 1.

5.2.2

Use

the above resistive matching network in place of

the balanced transformers as indicated in 5.1.3. Perform the

unbalanced attenuation test as described in 5.1.1 through

5.1.5 (see Figure 3).

The

Institute for Interconnecting and Packaging Electronic Circuits

2215 Sanders Road • Northbrook, IL 60062

IPC-TM-650

TEST

METHODS MANUAL

Number

2.5.30

Subject

Balanced

and Unbalanced Cable Attenuation

Measurements

Date

12/87

Revision

Originating Task Group

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.

age1of4

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