IPC-TM-650 EN 2022 试验方法.pdf - 第463页

• The center line of the coaxial cable end and the centerline of the stripline resonator in the specimen are aligned within a tolerance of 0.2 mm vertically and horizontally. • Both parts 5.2.3 (Figure 8) are held aligne…

according

to 6.1.2. This can be a manually adjustable

mechanical screw fixture such as a vise, clamp, or a pneu-

matic cylinder fixture with a pressure regulator. One of com-

ponent 5.1.5 with 5.1.4 is needed for every 152 mm of speci-

men length L. See Figure 6.

5.2

Probe Assembly

Two

probe assemblies are needed;

one for each end of the clamped stack. They can be designed

to be attached to the ends of the clamp bars 5.1.1. The fol-

lowing items are needed for each assembly.

5.2.1

Semi

rigid coaxial cable 1.8 mm size about 230 mm

long with 3 mm connector and adapters to the electronic

instrumentation. The probe end of the cable has the center

conductor extending 1.8 mm.

5.2.2 Copper

fitting with reversed bevel soldered to the end

of the coaxial cable jacket, as shown in Figure 7.

5.2.3

means for effecting ground contact between 5.2.2

and both of 5.1.2. Figure 8 shows a suggested beryllium-

copper alloy wire part. Two are required, as shown in the sec-

tional views of Figure 9.

5.2.4

Mechanical

assembly capable of attaching to the ends

of 5.1.1 and using the locations of the inside corners of 5.1.1

and 5.1.2 to align parts 5.2.1 through 5.2.3 with the center

line of the stripline resonator. It must accommodate various

specimen thicknesses, provide alignment of 5.2.1 through

5.2.3, make contact pressure of 5.2.3 to 5.1.2, provide con-

trolled adjustment of the gap between specimen end and

5.2.1, and provide support for the coaxial cable connector to

the instrumentation.

A wide variety of hardware designs for accomplishing the

alignment required in 6.1.5 are acceptable if the following con-

ditions are met for each of the two probes:

IPC-25551-5

Figure

5 Five Assembly Views for a Suggested Two Member Stacking Alignment Jig (See 5.1.3)

Note: Only the right-handed member is shown. Part A with 3.175 mm deep recessed area on the face towards the clamp blocks

assures 6.1.1 items b, c, and d. Its notched out area allows 6.1.1 item 5. Part B assures 6.1.1, item a. Part C eases mounting the jig

member to the end of the lower steel bar (see 5.1.1). Knurled #4-40 nut D, retained by E, fastens A against the steel bar with its

extended threaded rod. Part F assists in meeting 6.1.1, item e.

IPC-TM-650

Number

2.5.5.5.1

Subject

Stripline

Test for Complex Relative Permittivity of Circuit Board

Materials to 14 GHz

Date

3/98

Revision

age5of11

电子技术应用　　　　　　　ｗｗｗ．ＣｈｉｎａＡＥＴ．ｃｏｍ

•

The center line of the coaxial cable end and the centerline of

the stripline resonator in the specimen are aligned within a

tolerance of 0.2 mm vertically and horizontally.

• Both parts 5.2.3 (Figure 8) are held aligned so they are cen-

tered in a vertical plane through the probe axis, each mak-

ing firm electrical contact to 5.2.2 (Figure 7) and to the end

edge surface of part 5.1.2 (Figure 4).

• The coaxial probe end longitudinal position is adjustable so

that the gap between it and the specimen center conductor

is controllable to a tolerance of ± 0.03 mm.

6.0

Measuring Procedure

6.1 Preparation for Testing

The

actual length of the

specimen and resonator element shall be determined by a

vernier caliper or other means capable of accuracy to ± 0.03

mm or smaller.

Unless otherwise specified, specimens shall be stored before

testing at 18°C to 24°C and 50% ± 5% relative humidity. The

referee minimum storage time is 16 hours. Shorter times may

be used if they can be shown to yield equivalent test results.

If electronic equipment as listed in 4.1 is used, it shall be

turned on at least one half hour before use to allow warm-up

and stabilization. The automatic frequency counter listed in

4.1 is provided with temperature control of the clock crystal

that operates even when the power switch is off. Care should

be taken to assure that power is continuously supplied to this

unit to avoid a longer warm-up time. Other equipment using

vacuum tube devices will require a longer warm-up time, as

specified in the manufacturer’s literature.

IPC-25551-6

Figure

6 Clamp Arrangement (See 5.1.5) Showing Side and Front Views for Specimen Lengths of 76.2 mm and 304.8 mm

IPC-25551-7

Figure

7 Copper Fitting with Reverse Bevel (See 5.2.2)

Soldered to the 1.8 mm Semi-Rigid Coaxial Cable Probe

IPC-25551-8

Figure

8 Formed Be-Cu Alloy Wire for Ground Continuity

from Coaxial Cable Fitting to Copper Ground Plate

IPC-TM-650

Number

2.5.5.5.1

Subject

Stripline

Test for Complex Relative Permittivity of Circuit Board

Materials to 14 GHz

Date

3/98

Revision

age6of11

电子技术应用　　　　　　　ｗｗｗ．ＣｈｉｎａＡＥＴ．ｃｏｍ

This

method is best suited for measurements at ambient tem-

peratures in a controlled laboratory atmosphere. It may be

possible to adapt it for measurements at other temperatures.

6.1.1

The

steel clamping bars, copper clamping plates, and

the specimen assembly with copper foil are stacked with the

help of a jig (Figure 5) to assure the following:

a) One side surface or edge of each steel bar, copper plate,

specimen card, and ground plane copper foil lie in a

common plane.

b) The end surfaces of the steel bars lie in a common plane

within a 0.1 mm tolerance.

c) The ends of the copper plates extend beyond the steel

bars equally on both ends within a 0.1 mm tolerance.

d) The ends of copper plates, specimen cards, and copper

foil ground planes lie in a vertical plane within a 0.1 mm

tolerance.

e) In the case of specimen type A, the center conductor,

whose length extends enough beyond both ends of the

specimen cards to be gripped in tension and positioned,

is centered across the width of the specimen cards.

6.1.2

The

stack formed in 6.1.1 is clamped with a specified

total force. For a selected specimen length of 153 mm or less,

the force is applied through a force gage in a line centered on

the outer faces of the steel bars. For greater lengths, the force

should be distributed through force gages at two or more

positions not further than 153 mm apart along the length to

get uniformity of force per unit length along the specimen

length with minimal deflection of the steel bars. Thus, for a

304.8 mm length, apply equal forces at the 76.2 mm and

228.6 mm positions. If a 381 mm was used, apply force at the

63.5 mm, 190.5 mm, and 317.5 mm positions.

6.1.3

Remove

the alignment jig used in 6.1.1.

6.1.4

For

type A specimens, the center copper strip will still

be extending beyond the plane formed by the surfaces of the

copper plates, ground foil, and specimen end. This is clipped

off cleanly flush with that plane. One preferred method for

doing this is to use a lever-action toe nail clipper with a con-

vex shaped cutting pattern modified by grinding so that the

metal extending beyond the cutting edges is removed so that

the cutting edges are able to reach to the specimen edge for

cutting the copper strip.

IPC-25551-9

Figure

9 Probe Assembly Position (See 6.1.5) for One End of the Clamped Stack

Note: This figure shows coaxial probe with fitting and Be-Cu alloy wire for ground continuity without showing supporting mechanical

structures and adjustments.

IPC-TM-650

Number

2.5.5.5.1

Subject

Stripline

Test for Complex Relative Permittivity of Circuit Board

Materials to 14 GHz

Date

3/98

Revision

age7of11

电子技术应用　　　　　　　ｗｗｗ．ＣｈｉｎａＡＥＴ．ｃｏｍ