IPC-TM-650 EN 2022 试验方法.pdf - 第600页

5.3.4 All electrical measurements shall be made using 500 volts direct current. The voltage shall be applied to the speci- men for 60 +5, -0 seconds prior to taking the actual reading, for stabilization purposes. 5.3.5 M…

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

age2of4

电子技术应用　　　　　　　ｗｗｗ．ＣｈｉｎａＡＥＴ．ｃｏｍ

5.3.4

All

electrical measurements shall be made using 500

volts direct current. The voltage shall be applied to the speci-

men for 60 +5, -0 seconds prior to taking the actual reading,

for stabilization purposes.

5.3.5

Measure

the volume resistance by connecting the

resistance measuring device to the specimen electrodes

through the fixture system as described in 4.5 in accordance

with Figure 2.

5.3.6

Measure

the surface resistance by interchanging the

test cables connecting the solid back electrode and the outer

ring to the instrument for the arrangement shown in Figure 3.

5.4

Specimen Thickness

Each

specimen shall be mea-

sured for its thickness without cladding. Specimens for each

test condition shall have their thickness readings averaged.

Figure

1 Test pattern dimensions (See table)

Figure

IPC-TM-650

Number

2.5.17.1

Subject

Volume

and Surface Resistivity of Dielectric Materials

Date

12/94

Revision

age3of4

电子技术应用　　　　　　　ｗｗｗ．ＣｈｉｎａＡＥＴ．ｃｏｍ

5.5

Calculations

5.5.1

The

volume resistivity shall be calculated as follows:

r=RA

Where:

r = Volume resistivity in megohm-centimeters

R = Measured volume resistance in megohms

A = Effective area of the guarded electrode in square centi-

meters

T = Average thickness of specimen in centimeters

T = (t) x 2.54 [see 5.2.1]

t = Average thickness (t) in inches (from 5.4)

Note:

The

value of A may be obtained from the Dimension

Table.

5.5.2

The

surface resistivity shall be calculated as follows:

Where:

Surface resistivity in megohms

Measured surface resistance in megohms

P = Effective perimeter of the guarded electrode in centime-

ters

D4 = Width of the test gap in centimeters

Note:

The

ratio of P/D4 for the electrode configuration being

used may be obtained from the Dimension Table included in

Figure 1.

5.6

Reporting

5.6.1

The

volume resistivity of each specimen and the aver-

age shall be reported. Each condition tested shall be reported

separately.

5.6.2 The surface resistivity of each specimen and the aver-

age shall be reported. Each condition shall be reported sepa-

rately.

5.6.2.1 The

surface resistance is the direct reading of the

megohmeter scale and should be recorded in megohms.

6.0

Notes

6.1

For

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

tance or Conductance of Insulating Materials.

6.2

The

system of electrical connections to the specimens

may benefit from a coaxial cable set-up designed to shield the

measurement of volume or surface resistances from electrical

interference.

6.3

Performance Specifications

The

following informa-

tion should be reviewed within the applicable performance

specification or product procurement document:

a. Specimen size, quantity, and configuration, if other than

that specified in 3.0.

b. Conditioning parameters, such as temperature for Elevated

Temperatures.

c. Any other changes to the specified procedures in this

method.

IPC-TM-650

Number

2.5.17.1

Subject

Volume

and Surface Resistivity of Dielectric Materials

Date

12/94

Revision

age4of4

电子技术应用　　　　　　　ｗｗｗ．ＣｈｉｎａＡＥＴ．ｃｏｍ