IPC-TM-650 EN 2022 试验方法.pdf - 第462页

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 1…

Such

instruments may be operated either manually or under

computer control with suitable programming to locate the

resonant frequency and the frequencies above and below

resonance where transmitted power is 3 dB below that at

resonance. Network analyzers have several advantages over

the instrumentation described in 4.1. Data collection is rapid

and may be continuously refreshed with averaging. The log

magnitude response curve for ratio of transmitted to incident

power (the S21 parameter) as dB versus frequency is visible

on a screen for easy verification of a valid resonance. A large

number of dB, frequency data points near the resonance, are

readily available for optional use of non-linear regression

analysis techniques to determine the frequency and Q values

with statistically better degrees of uncertainty than those

attainable by the three point (f

and f

)

method in either

section 6.2 or 6.3.

5.0

Test Fixture

5.1 Fixture Parts for Clamping

is the selected length for

the specimen. A fixture may include hardware for more than

one value of L. Suggested L values are 50.8, 76.2, 152.4, and

304.8 mm. Since the fundamental resonant frequency and its

harmonics are inversely proportional to the value of L for a

given ε

the selection of an L value determines the low fre-

quency at which the material may be measured for ε

and

tan

δ. Figure 1 shows the end views of a series of specimen con-

figurations and includes the parts for clamping.

5.1.1

For

each L value, two ground tool steel clamping bars

25.4 mm x 28.58 mm x (L-6.35), as shown in Figure 3. These

are intended to provide uniformly distributed force along the

length of the specimen, transferred through part 5.1.2. A rec-

ommended practice is to provide these with a small diameter

threaded rod, such as #4-40, centered on each end and

extending about 20 mm to serve as a means for attaching the

probe assembly of 5.2 used in 6.1.5 or the alignment jig of

5.1.3 used in 6.1.1.

5.1.2

For

each L value, two pure copper ground plates 25.4

mm x 9.52 mm x L with all edges sharp as in Figure 4. These

provide at the ends a copper surface perpendicular to the

specimen length direction, which serves as a contact area

over a range of specimen thicknesses for making ground con-

tinuity to the coaxial probe. When these are clamped with

5.1.1 as described in 6.1.1, the inside corners at each end

between the outer face of 5.1.2 and the end surface of 5.1.1

form reference locations equidistant from the center line of the

stripline resonator element that are used by the probe assem-

bly 5.2 to align the coaxial probe with that center line.

5.1.3

stacking alignment jig as used in 6.1.1 of an appro-

priate design. Figure 5 shows a suggested design.

5.1.4

low profile mechanical force gage with 4.45 kN

compression capacity such as a Dillon Model U, PN 30482-

0053, available from Dillon Quality Plus, Inc., 1140-T Avenida

Acaso, Camarillo, CA 993012. One is needed for each of part

5.1.5.

5.1.5

clamping arrangement with 5.1.4 properly mounted

in the line of force and with alignment parts for assuring the

line of force is properly located through the stack assembled

IPC-25551-3

Figure

3 Three View Drawing of a Steel Clamping Bar

(See 5.1.1) Cut to Length for the 50.8 mm L Value

(Extended #4-40 Threaded Rod Both Ends is Not Shown)

IPC-25551-4

Figure

4 Three View Drawing of a Copper Ground Plate

(See 5.1.2) for the 50.8 mm L Value

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

age4of11

电子技术应用　　　　　　　ｗｗｗ．ＣｈｉｎａＡＥＴ．ｃｏｍ

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