IPC-TM-650 EN 2022 试验方法.pdf - 第598页

1.0 Scope This test method is designed to determine vol- ume resistivity and surface resistivity of metallic-clad or unclad laminates under conditions of specified humidity and tempera- ture and at elevated temperatures.…

49°C

and 60°C. Coat unclad side with silver conductive paint

(per Figure 2). Sand all edges to remove any silver paint to

prevent a conductive path.

5.1.3

Bare Dielectric

Prepare

test specimens by immers-

ing in distilled water for 24 hours at 23°C ± 2°C, then dry in

an oven for two hours at a temperature between 49°C and

60°C. Coat the unclad material with silver conductive paint

(one side per Figure 1 and the other per Figure 2). Sand all

edges to remove any silver paint.

5.2

Conditioning

5.2.1

Condition

specimens together with the test fixture at

35°C ± 2°C and 90% -0, +5% RH for 96 hours.

5.2.2

Specimens

(and test fixture) must remain in the cham-

ber for all phases of both the volume resistivity and surface

resistance tests.

5.2.3

These

conditions may vary depending on the request

of the material user.

5.3

Test

5.3.1

After

conditioning, and without removing specimens

from the chamber, connect specimen to electrodes as fol-

lows:

Megohmmeter

Leads Specimen Location

High

.................................................. Guarded (5.0 cm circle)

Ground ...............................................Guarded (6.35 cm ring)

Test ................................................Unguarded (7.6 cm circle)

5.3.2

Turn

on the megohm meter and allow to warm up for

a minimum of 15 minutes.

5.3.3

After

warm up, calibrate meter and adjust internal volt-

age to 500 volts DC.

5.3.4

Read

the meter (in megohms) after the test switch is

held depressed for 60 seconds.

5.4

Evaluation

5.4.1

Calculate

the volume resistivity (r) in megohm centime-

ters as derived from the following formula:

r =

= volume resistivity in megohm cm

L = thickness of specimen in cm

A = area of guarded electrodes is 25.6 cm

= volume resistance in megohms (meter reading)

5.5

Preparation for Surface Resistance

Leave

the same

specimens in the test chamber and prepare to test surface

resistance by connecting the specimens to electrodes as fol-

lows:

Megohmmeter

Leads Specimen Location

High

...........................................................................Guarded

Ground ..................................................................Unguarded

Test ...............................................................................Guard

5.6

Test

Perform

the same testing procedures per 5.3.

5.7

Evaluation

The

surface resistance is the direct reading

of the megohmmeter scale and should be recorded in mego-

hms.

6 Notes

This

method may also be used for rigid dielectric

materials.

6.1

For

additional information see ASTM-D-257, DC Resis-

tance or Conductance of Insulating Materials.

IPC-TM-650

Number

2.5.17

Subject

Volume

Resistivity and Surface Resistance of Printed Wiring

Materials

Date

5/98

Revision

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1.0

Scope

This

test method is designed to determine vol-

ume resistivity and surface resistivity of metallic-clad or unclad

laminates under conditions of specified humidity and tempera-

ture and at elevated temperatures.

2.0

Applicable Documents

ASTM-D-257 D-C Resistance or Conductance of Insulating

Materials

IPC-TM-650

Method

2.3.6, Etching, Ammonium Persulfate

Method, 2.3.7 Etching, Ferric Chloride

Method 2.3.7.1, Cupric Chloride Etching

Method 2.6.3, Moisture and Insulation Resistance, Rigid,

Rigid/Flex and Flex Printed Wiring Boards

3.0

Test Specimens

3.1

Laminate

thickness of 0.51 mm [0.020 in] or greater.

Three specimens of dimensions 101.6 ± 3.2 mm x 101.6 ±

3.2 mm [4.0 ± 0.125 in x 4.0 ± 0.125 in] by thickness shall be

prepared for each test condition, unless otherwise specified.

3.2

Laminate

thickness of less than 0.51 mm [0.020 in].

Three specimens of dimensions 50.8 ± 1.6 mm x 50.8 ± 1.6

mm [2.0 ± 0.062 x 2.0 ± 0.062 in] by the thickness shall be

prepared for each test condition, unless otherwise specified.

4.0

Equipment Apparatus

4.1

Conditioning

chamber capable of maintaining 35 ± 2°C

[95 ± 3.6°F] and 90 +5, –0% relative humidity.

4.2

Conditioning

chamber capable of attaining the tempera-

ture and humidity conditions specified in IPC-TM-650, Method

2.6.3.

4.3

Air

circulating oven capable of maintaining the specified

test temperatures to within ± 2°C[±3.6°F].

4.4

Resistance

measuring instrumentation capable of mea-

suring to 10

meg-ohms,

minimum, with an accuracy of ± 5

percent at its highest scale setting. The equipment shall have

the capability of applying 500 volts dc to the test specimen.

4.5

system/fixture for electrical connections into the tem-

perature and humidity chambers (see 4.1, 4.2, 4.3). Three

separate cables shall be provided to make connections to

each specimen being conditioned/tested. The center conduc-

tor of each cable shall be connected to one of the three elec-

trodes applied to the test specimen. The opposite ends of the

cables shall be brought outside the chamber and terminated

at a convenient location for connection to the measuring

instrument. Shields shall be trimmed back from the ends of

the center conductor insulation and interconnected to the

guard post of the measuring instrument. See 6.2 for additional

information.

Support the specimen parallel to the air flow through the

chamber during conditioning.

Special care should be taken to ensure that materials used in

the fixture are such that resistance readings are that of the

material being tested and not the fixture.

4.6

measurement device capable of measuring laminate

thickness to the nearest 0.0025 mm [0.0001 in].

4.7

Material

and apparatus for formation of specimen con-

ductors.

4.7.1 Conductor

silver paint; composition 4817 by Dupont

Company, or equivalent.

4.7.2

system for applying the paint to the specimen, such

as silk screening.

4.7.3

mask, fixture, photoprinting system, or equivalent,

for applying the applicable electrodes/test pattern to the

specimen (See Dimension Table).

4.8

Etching

system in accordance with IPC-TM-650,

Method 2.3.6, 2.3.7, or 2.3.7.1.

5.0 Procedure

5.1 Specimen Preparation

5.1.1

Test

patterns with the applicable dimensions shown in

the Dimension Table, and in accordance with Figures 1, 2,

and 3 shall be generated, as follows:

The

Institute for Interconnecting and Packaging Electronic Circuits

2215 Sanders Road • Northbrook, IL 60062

IPC-TM-650

TEST

METHODS MANUAL

Number

2.5.17.1

Subject

Volume

and Surface Resistivity of Dielectric

Materials

Date

12/94

Revision

Originating Task Group

MIL-P-13949 Test Methods Task Group (7-11b)

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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5.1.1.1

Metallic-clad

materials having a thickness of less

than 0.51 mm [0.020 in] shall be photoprinted with a pattern

of the outline of the conductors and etched in accordance

with IPC-TM-650, Methods 2.3.6, 2.3.7, or 2.3.7.1. The elec-

trodes shall then be completed (filled in) using silver conduc-

tive paint.

5.1.1.2

Metallic-clad

laminates 0.51 mm [0.020 in] or thicker

shall be etched in accordance with IPC-TM-650, Method

2.3.6, 2.3.7, or 2.3.7.1. A pattern of the outline of the conduc-

tors may be photoprinted before etching. Test electrodes shall

be applied using silver conductive paint and an appropriate

test pattern application system.

5.1.1.3

Solid

metal foil electrodes shall not be acceptable in

any case, except for the outer electrode for laminates less

than 0.51 mm [0.020 in]. A small pad of retained cladding may

be retained within the electrode borders to facilitate soldering

of leads.

5.1.2

soldering techniques are used to attach leads, suit-

able cleaning procedures shall be used to remove flux and

other residue.

5.2

Conditioning

5.2.1 Humidity Conditioning

5.2.1.1

Specimens

of a thickness less than 0.51 mm [0.020

in] shall be subjected to 90 + 5-0% relative humidity and 35 ±

2°C [95 ± 3.6°F] for a period of 96 +2, -0 hours prior to elec-

trical measurement.

5.2.1.2

Specimens

of a thickness greater than, or equal to,

0.51 mm [0.020 in] shall be subjected to the conditioning

specified in IPC-TM-650, Method 2.6.3, paragraph 5.1.3. Fol-

lowing the tenth cycle, the conditioning chamber shall main-

tain a temperature of 25 ± 2°C [77 ± 3.6°F] and 90 +5, 0%

relative humidity during the interval that electrical measure-

ments are being made.

5.2.2

At Elevated Temperature Conditioning

Speci-

mens

shall be subjected to the specified temperature (based

on material type and specification requirements) for a period

of 24 hours -0, +2 hours. Unless otherwise specified, the tem-

perature shall be 125 ± 2°C [257 ± 3.6°F].

5.3

Electrical Measurements

All

electrical measurements

shall be made inside the applicable conditioning chamber and

at the conditions specified in 5.2.

5.3.1

Electrical

measurements taken on specimens condi-

tioned in accordance with paragraph 5.2.1 shall be completed

within the 2 hour tolerance of the conditioning.

5.3.2

Electrical

measurements taken on specimens condi-

tioned in accordance with paragraph 5.2.2 shall be made after

achieving 1.5 hours steady state of 25 ± 2°C [77 ± 3.6°F] and

90 +5, -0% relative humidity. All measurements shall be com-

pleted within 2 hours.

5.3.3 Electrical

measurements taken on specimens condi-

tioned in accordance with paragraph 5.3 shall be completed

within the 2 hour tolerance of the conditioning.

Dimension

Table

Base

Thickness

Diameter

A(cm

)

P/D

Less

than

0.51 mm

(0.020 inches)

1.000

(2.540)

1.020

(2.591)

1.375

(3.493)

0.010

(0.025)

0.177

(0.460)

5.169 317.4

±0.005

(0.013)

±0.005

(0.013)

±0.005

(0.013)

±0.001

(0.003)

±0.005

(0.013)

0.51 mm

(0.020 inches)

and greater

2.000

(5.080)

2.500

(6.350)

3.000

(7.520)

0.250

(0.636)

0.250

(0.636)

25.652 28.27

±0.015

(0.038)

±0.015

(0.038)

±0.015

(0.038)

±0.005

(0.038)

±0.015

(0.038)

For the above: Do = (D

)/2

A=πDo

P=πD

Note:

Dimensions

are in inches with metric equivalents in parenthesis (1 inch = 2.54 cm).

IPC-TM-650

Number

2.5.17.1

Subject

Volume

and Surface Resistivity of Dielectric Materials

Date

12/94

Revision

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